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Conference 13100
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI
16 - 21 June 2024 | Room G214, North - 2F
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Session 1:
Fabrication of Mirrors, Lenses and other Optical Components I
16 June 2024 • 10:20 - 12:05 Japan Standard Time | Room G214, North - 2F
Session Chair:
Marc Cayrel, European Southern Observatory (Germany)
13100-1
16 June 2024 • 10:20 - 10:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
In 2017, the European Southern Observatory (ESO) awarded a contract for the Polishing, integration and final figuring of the Segment Assemblies of the primary mirror (M1) for the Extremely Large Telescope (ELT) to Safran Reosc. Since then, the design and commissioning of a production unit dedicated to ELT M1 has been accomplished and the plant has been producing many mirrors since spring 2022. We will introduce the smart factory, its processes and their automation that enabled reaching the current throughput of one mirror per day. We will then present the status of the project, some lessons learned and highlight the successes that have been achieved so far.
13100-2
16 June 2024 • 10:35 - 10:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Large Fiber Array Spectroscopic Telescope (LFAST) targets large collecting aperture at low cost. Several thousand 0.76m, f/3.5 mirrors focus light into fibers that are combined at a high resolution spectrograph. The mirror substrates are fabricated from 25.4mm thick Borofloat discs in a three-day slump and polish process to provide less than 50nm rms wavefront error in medium and high spatial frequency modes.
Low order figure errors are corrected with a perimeter ring of thermoelectric actuators that induce expansion or contraction with top-to-bottom thermal gradients. In operation, temperature variations from nighttime cooling cause time-varying aberration modes, especially astigmatism. Using feedback from a stellar wavefront sensor, these aberrations are compensated to focus 80% of starlight energy within a 1.4 arcsec fiber.
13100-3
16 June 2024 • 10:50 - 11:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
To unlock the potential of space, there is a push for better optical imaging, including for larger parabolic on and off-axis mirrors. Costs and lead times have prohibited many programs from scaling. To answer this call, Optimax is developing manufacturing capabilities using a Lean Cell approach, where generation, polishing, smoothing, final figuring, and core metrology are centrally located and tightly controlled. This approach, and its adaptability, will allow lead time reduction from 60+ weeks to eight weeks for 0.5 m optics. Because all components are contained in one cell, ownership of results is carefully monitored by engineers and technicians from start to finish, increasing the quality and decreasing the decision-making time between steps. Finally, advances in the coating capabilities allow for a variety of customized, 0.5 m optic size coating formulations to finish the process. Data from recent projects will be shared to highlight the process and capabilities.
13100-4
16 June 2024 • 11:05 - 11:20 Japan Standard Time | Room G214, North - 2F
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Developed by the Observatory of Paris as a prototype for the Small-Sized Telescopes (SST) of the future Cherenkov Telescope Array (CTA), the Gamma-ray Cherenkov Telescope is an Imaging Atmospheric Cherenkov Telescope (IACT) design made to detect Very High Energy (VHE) gamma rays from various cosmic sources. Based on a Schwarzschild-Couder (SC) dual-mirror configuration and implementing some maintenance-friendly features, the design results in a compact telescope and an optimised PSF over a wide field of view. Metallic mirrors compose the optics, providing aspherical profiles and the high durability required for the mirrors. The prototype (pGCT) was built in 2015 and became the same year the first telescope worldwide to obtain its first Cherenkov light on the sky with a SC configuration. Recently, a new batch of upgraded metallic mirrors was provided for pGCT, leading to an unprecedented PSF.
13100-5
16 June 2024 • 11:20 - 11:35 Japan Standard Time | Room G214, North - 2F
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The Čerenkov Telescope Array gamma-ray Observatory (CTAO) is working on developing two large telescopes, each with a diameter of 23 meters, that will be installed in Paranal, Chile. INAF will coordinate the implementation effort. These telescopes will use a single mirror parabolic shape to capture images with moderate angular resolution. To achieve this shape, 198 hexagonal reflecting panels will be assembled. Each panel is roughly 150 cm in size and weighs less than 50 kg. It comprises two solid glass plates bonded to a lightweight honeycomb structure made of an Aluminum alloy core. The panels are spherical and distributed in three coronas with different curvature radii to achieve the desired shape. They will be exposed to the open air for several years and must withstand mechanical stresses, wind impact, and possible strong earthquake solicitations. The panels are the basic elements of the telescope's segmented primary mirror. The development activities, including the design effort based on FEM analysis, performed to optimize the mirror design and prototypes are summarized in this paper.
13100-6
16 June 2024 • 11:35 - 11:50 Japan Standard Time | Room G214, North - 2F
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Space-based mirrors are a developing use-case for Additive Manufacturing; the increased geometric freedom over conventional manufacturing methods allows for part consolidation and mass reduction. Lightweight mirror designs should minimise print-through on the reflective surface and ensure powder/resin can be removed from internal cavities. This paper will describe the design, manufacture and metrology of aluminium and fused silica prototypes of a 52mm diameter, 10mm deep mirror with a convex reflective surface. Mounts for three deployable booms will be combined into the mirror which will have mass reduction targets of 50% and 70%. Both the reflective surface and internal geometry will be evaluated for roughness and porosity respectively.
13100-7
CANCELED: The benefits of metal optics for space instrumentation: two decades of metal optics developments at AMOS
16 June 2024 • 11:50 - 12:05 Japan Standard Time | Room G214, North - 2F
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Aluminium alloys are light, strong, non-brittle, very good electrical and heat conductors, available and very easy to machine.
The manufacture of aluminium alloy mirrors has expanded with the advent of ultra-precise diamond machining, which are available for several decades. Most of the cryogenic experiments on board Herschel, Planck, JWST, etc. are equipped with metal optics, the first in popularity being the 6061-aluminium alloy. It is however not the best polisheable material. To improve its polisheability, a Nickel plating is usually added on the optical side, which generates bi-metallic issues.
In the meantime, these techniques have benefited from significant developments in alloys.
Moreover, reflective surfaces are not the only elements needed to create more complex optical systems such as spectrometers. Other critical components, such as diffraction gratings and slits, will benefit from being made from the same alloy as the supporting structure.
This paper presents a summary of about two decades of technology developments on metal components, especially free-form mirrors, diffraction gratings and long entrance slits, which make the essential ingredients of a spectrometer.
Break
Lunch Break 12:05 - 13:20
Session 2:
Fabrication of Mirrors, Lenses and other Optical Components II
16 June 2024 • 13:20 - 14:50 Japan Standard Time | Room G214, North - 2F
Session Chair:
Camille Frapolli, Safran Reosc (France)
13100-8
16 June 2024 • 13:20 - 13:35 Japan Standard Time | Room G214, North - 2F
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Reflective optical systems typically combine precise aligned mirrors, housings, interface structures et cetera. For MICADO (Multi-AO Imaging Camera for Deep Observations), a first-light instrument for ELT, Fraunhofer IOF realize several optical sub-systems, including ten freeform shaped metal optics for the Collimator, the high-resolution Imager, the low-resolution Imager and the Camera.
In this paper, the challenges of freeform manufacturing and metrology will be described. For manufacturing of those mirror substrates suitable technologies, as slow tool servo (STS) and fast tool servo (FTS) diamond turning and for further correction (e.g., magnetorheological finishing) and smoothing steps (e.g., chemical-mechanical polishing), sub-aperture tools are required. For interferometry of freeform shaped optical surfaces, computer generated holograms including reference fiducials are realized. After manufacturing the mirror substrates, the optical surface will be coated with a high-reflective gold coating.
13100-9
16 June 2024 • 13:35 - 13:50 Japan Standard Time | Room G214, North - 2F
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METIS, the mid-infrared imager and spectrograph, is set to function at ESO's Extremely Large Telescope (ELT) in Chile. The chopper, a mirror in the Common Fore Optics (CFO) which is part of METIS, is a fully integrated tip-tilt mechanism mirror and functions to minimize thermal background noise by shifting between the target object and the background. This cryogenic aluminium mirror is made though in-house CNC programming, milling and thermal aging. The mirror demands tolerances surpassing the accuracy of the milling machine that is used, which typically operates with an accuracy of 20-30 microns on a multi sided part dominated by thermal drift. Therefore a specialized production methodology is developed to ensure the achievements of the critical tolerances. A so-called Golden Sample provides a known and stable reference during manufacturing, allowing to bypass the drift and static errors of the machine. CMM measurements proves that the used production method is giving excellent results.
13100-10
16 June 2024 • 13:50 - 14:05 Japan Standard Time | Room G214, North - 2F
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In this study, we introduce a novel approach in atomic layer deposition (ALD) for telescope mirror protection using a meter-scale ALD system (MSAS) designed for large substrates, addressing previous limitations in ALD applications for telescope mirrors. MSAS incorporates a unique reaction chamber design, allowing uniform protection coatings on 900 mm substrates. We extensively analyzed ALD of aluminum oxide (AlOx), comparing it with a wafer-scale ALD system (WSAS). Our findings reveal scalable ALD processes with optimized parameters, offering applications for silver-based telescope mirrors. For aluminum-based telescope mirrors (Al-mirrors) operating in the far UV spectral range, we explored the use of aluminum fluoride (AlFx) as a transparent protection coating. Unlike traditional ALD of AlOx, ALD of AlFx is uncommon, posing challenges in achieving a 2 nm uniform coating. Furthermore, susceptibility of Al-mirrors to oxidation complicates the coating process. Through the study and modifications in MSAS, we gained critical insights into scaling ALD processes for AlF3 protection coatings, offering unique solutions for improving Al-mirrors’ performance and durability.
13100-11
16 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
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The stressed-mirror polishing process has been successfully deployed for the manufacturing of Nancy Grace Roman Space Telescope coronagraph mirrors. This process combines a simple warping system with an optimized (more complex) thickness distribution of the mirror’s substrates allowing to warp them into the required Off Axis Parabola’s parameters. This way, the polishing process uses full-sized tools, avoiding the generation of undesired high spatial frequency sub-aperture tool marks. The smoothness of the surface is then worked with a super-polishing process, lowering the roughness down to a few Angstroms.
The research we present is done in the frame of the post-RST technology maturation roadmap. The Habitable Worlds Observatory requirements are so drastic that we must push the performance of the stressed mirror polishing process to gain on the roughness.
Together with chemical scientists, we work on the production of nanoparticle slurries with the goal to go below the angstrom in terms of roughness. In this talk, we present the nanoparticles production process, the results obtained on the mirror’s prototypes we produced and the roadmap for the production of hyperpolished OAPs.
13100-12
16 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
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The extreme and out of the ordinary sensitivity shared by the main gravitational waves detector like LIGO, Virgo and KAGRA has recently enabled to access to a new source of information for astronomy. However, future upgrades and new challenges continue to be addressed for reaching wider horizons of measurable universe events through the gravitational waves. It leads to tighter and tighter specifications in several domains and in particular in the accuracy of the optics at the core of the detector.
13100-13
16 June 2024 • 14:35 - 14:50 Japan Standard Time | Room G214, North - 2F
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Many optics applications, including x-ray synchrotron systems and space applications, require increasingly precise mirrors to enable diffraction limited focusing of x-ray beams. These mirrors require nanometer level form error and extremely tight tolerances in the mid-spatial frequency and surface roughness ranges. This talk will discuss efforts at Optimax to address this need through advancement of robotic smoothing platforms and processes. Specifically, process refinement results using a large robot, with up to a 1 meter reach, will be shared.
Break
Coffee Break 14:50 - 15:20
Session 3:
Fabrication of Mirrors, Lenses and other Optical Components III
16 June 2024 • 15:20 - 16:05 Japan Standard Time | Room G214, North - 2F
13100-15
16 June 2024 • 15:20 - 15:35 Japan Standard Time | Room G214, North - 2F
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Mid-spatial frequency manufacturing errors are often present in aspherical optics. These errors arise from the nature of the asphere manufacturing process, whereby many passes are made on multi-axis polishing machines. The process results in mid-spatial frequency artifacts which can typically be characterised into 2 types of form error: rings and spokes. The standard tolerance specifications of form and slope error used in asphere manufacture does not capture the range of possible outcomes for an as manufactured part. The fact that the current tolerance standard does not adequately describe the range of outcomes for as manufactured aspheres has been known for some time. In this work, we present a set of orthogonal basis functions which represent rings and spokes, combined with statistical form errors sampled from an appropriate power law statistical distribution in frequency space. We use real data to verify that our error representation is more efficient mathematically as compared with the standard Zernike decomposition.
13100-16
16 June 2024 • 15:35 - 15:50 Japan Standard Time | Room G214, North - 2F
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It is difficult to manufacture a wide-field telescope using freeform surfaces due to the large gradient of the freeform surfaces. We propose a design method to minimize the gradient by analytical calculations based on the aberration theory. This method has realized the optical system with three mirrors achieving a field-of-view of 16 square degrees with F/3 and 200 mm aperture. The maximum gradient of the freeform surfaces is 98 mdeg, which is reduced by 46% from previous study.
13100-17
The CASTLE telescope: on the use of curved freeform sensors for astronomical applications and beyond
16 June 2024 • 15:50 - 16:05 Japan Standard Time | Room G214, North - 2F
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The field curvature has been a long-term problem optical designers had to deal with, to propose flat corrected field instruments. Combinations of highly aspherical optics, TMA configurations, achromatic doublets or field flatteners are often used to reach good optical quality across the image.
Allowing designers to play with the parameters of the field’s shape is offering them a brand-new game field. The possibility of curving the CMOS sensors to fit curved/aspherical/freeform shapes of focal surfaces has been studied for the last 20 years and led today to different applications and prototypes.
We present in this article 1/ the parameter studies we performed over a large set of optical designs showing the gain offered by this approach, 2/ the CMOS sensors curving process and performance over a large set of prototypes, 3/ Optical systems that have been produced with this technology and 4/ the roadmap related to the development of curved-sensors based instrumentation for astronomy with the CASTLE telescope project and physical sciences through the Auroral UV Imager program led by ESA.
Session 4:
Materials and Metamaterials
16 June 2024 • 16:05 - 17:20 Japan Standard Time | Room G214, North - 2F
Session Chair:
Ralf Jedamzik, SCHOTT AG (Germany)
13100-18
16 June 2024 • 16:05 - 16:20 Japan Standard Time | Room G214, North - 2F
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A methodological approach is proposed to quantify the expected deformation of ZERODUR® based spaceborne mirrors due to ionizing irradiation (compaction) over a GEO orbit. At first, we calculated the expected irradiation level over 4 orbits (LEO, Sun Synchronous and L2). We then selected the harshest environment -GEO- and carried out equivalent irradiation laboratory tests. The deformations observed on coupons are then correlated with those expected on larger isogrid mirror lightweighting structures over mission lifetime. These results demonstrate the resilience of ZERODUR® in these environments as already established over 4 decades of successful missions involving ZERODUR® based mirrors.
13100-19
16 June 2024 • 16:20 - 16:35 Japan Standard Time | Room G214, North - 2F
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Detailed material property data of Fine Cordierite in the space environment has not been made publicly available. Therefore, despite its excellent characteristics, there is currently hesitation among groups who actively adopt it in space applications where proven performance is highly valued. In order to address this issue, we have prepared Fine Cordierite test samples, conducted ground tests simulating the space environment using radiation and atomic oxygen exposure and compiled the results into a database. This database includes mechanical properties (bending strength, Young's modulus, and bulk density), thermal properties (coefficient thermal expansion and thermal conductivity), and optical properties (surface accuracy) before and after applying radiation and atomic oxygen exposure. Additionally, the database also includes information of the outgassing from Fine Cordierite in a vacuum environment.
13100-20
16 June 2024 • 16:35 - 16:50 Japan Standard Time | Room G214, North - 2F
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A new deposition method developed by Goddard Space Flight Center fluorinates Al mirrors with XeF2 followed by a LiF coating to create what they term Al+XeLiF. This in-situ, room temperature process produces mirrors with high reflectivity in a broad spectral range, from the FUV to the IR, and is reported to be stable in relative humidities of 30% and lower. These mirrors are envisioned for missions requiring sensitivity down to 100 nm wavelength such as the habitable worlds observatory. Because most mission integration and testing campaigns require prolonged exposure to lab environments, and launch sites experience high relative humidities (RH) on average, some at 80% RH. We investigate Al+XeLiF stability in a wider range of temperatures and humidities along with employing additional characterization techniques including atomic force microscopy and x-ray photoelectron spectroscopy. We found that Al+XeLiF is stable in environments up to 82%RH when kept at cooler temperatures (3°C and 21°C). However, this material is unstable when stored at 60°C, experiencing roughening and loss in reflection from resulting Al surface plasmon excitation.
13100-21
16 June 2024 • 16:50 - 17:05 Japan Standard Time | Room G214, North - 2F
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Invar, used in optical systems for astronomical equipment, is unsuitable for components susceptible to magnetostriction due to its ferromagnetism. A non-ferromagnetic Cr-based invar-type alloy shows promise with low thermal expansion characteristics. However, its mechanism and magnetic properties are not fully understood. Studies on Cr-Fe-Mn alloys revealed that low thermal expansion becomes apparent below 0ºC when Mn content is less than 0.3%, and between 0 and 77ºC when Mn content is 0.9% or more. The average coefficient of thermal expansion between 0 and 77ºC can be achieved to be 0.94 ppm/ºC in Cr94.6Fe4.7Mn0.7 with the addition of some subtle rare earth elements, which is lower than 1.2 ppm/ºC of conventional Invar. The alloy's residual magnetization is approximately 0.0033 mT, which is also significantly lower than 35 mT typically observed in conventional Invar.
13100-22
16 June 2024 • 17:05 - 17:20 Japan Standard Time | Room G214, North - 2F
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Several near-infrared instruments on upcoming extremely large telescopes use a combination of OHARA S-FPL51 and S-LAH71 glass prisms to correct for the atmospheric differential refraction. Because large parts of these instruments are contained within a vessel cooled to liquid nitrogen temperatures, the changes in optical and mechanical properties should be considered during the design phase.
In this report, we provide an update to our continuing efforts to characterize the S-FPL51 and S-LAH71 glass under cryogenic conditions. These efforts include a measurement of the refractive index (293 K, 100 K and 80 K), transmission measurements (293 K, 77 K and 43 K) and a determination of the coefficient of thermal expansion (between 293 K and 45 K). This characterization will prove useful for conceptual design trade-offs, mechanical interface solutions and detailed optical design for future near-infrared instrumentation on large telescopes.
Monday Plenary
17 June 2024 • 08:20 - 10:00 Japan Standard Time | National Convention Hall, 1F
View Full Details: spie.org/AS/monday-plenary
13173-500
Moving TMT forward: Japan’s contributions and transformative approach toward community engagement
(Plenary Presentation)
17 June 2024 • 08:30 - 09:15 Japan Standard Time | National Convention Hall, 1F
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The Thirty Meter Telescope International Observatory (TIO) is an ambitious international scientific endeavor. In Part 1, we highlight Japan’s contributions toward technical advancements. Building upon the scientific and engineering success of the Subaru Telescope and ALMA, Japan leads in developing the telescope structure, primary mirror production, and cutting-edge science instruments. Part 2 delves into TIO’s transformative shift toward community engagement. At TIO, we believe in community model of astronomy that upholds the values of inclusion, respect, and community stewardship. We are committed to listening to, learning from, and working together with Hawaiʻi commuities to build a brighter future for all.
13173-501
From dark skies to bright futures: the evolution of astronomy in Africa and the hosting of the historic International Astronomical Union General Assembly 2024
(Plenary Presentation)
17 June 2024 • 09:15 - 10:00 Japan Standard Time | National Convention Hall, 1F
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Africa's unique dark skies offer vast potential for astronomy, which has significantly advanced over the last two decades through substantial investment in infrastructure and human capital. The African Astronomical Society (AfAS), relaunched in 2019, plays a crucial role in this ascent, enhancing the network of astronomers across the continent, fostering research collaborations, and advising on policy. Noteworthy achievements for Astronomy in Africa include securing a bid to host the mid-frequency component of the Square Kilometre Array (SKA) telescope, hosting the first International Astronomical Union (IAU) General Assembly in Africa in August 2024, and being home to the IAU Office of Astronomy for Development (OAD) since 2011. This talk highlights these milestones, illustrating the community's commitment to developing astronomy on the continent and utilising astronomy as a tool to address developmental challenges.
Break
Coffee Break 10:00 - 10:30
Session 5:
Calibration, Test and Metrology I
17 June 2024 • 10:30 - 12:15 Japan Standard Time | Room G214, North - 2F
Session Chairs:
Shinobu Ozaki, National Astronomical Observatory of Japan (Japan), Richard A. McCracken, Heriot-Watt Univ. (United Kingdom)
13100-23
17 June 2024 • 10:30 - 10:45 Japan Standard Time | Room G214, North - 2F
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Since the fabrication of the Keck telescope primary mirror segments, radius of curvature matching have been known to be one of the major challenge in manufacturing segmented optics with high accuracy. Curvature is generally not a critical specification for optics as any error can be compensated by alignment (for a telescope mirror, by the distance between M1 and M2). However, for a segmented primary such as the ones in the Keck, GTC or ELT telescopes, a radius of curvature mismatch prevents from generating a continuous surface when assembling the mirror through a residual surface error called scalloping. We will present how this constraint drove the design of ELT metrology means, and how we achieved a radius of curvature metrology with 50 ppm accuracy on a 71m curvature reference.
13100-24
17 June 2024 • 10:45 - 11:00 Japan Standard Time | Room G214, North - 2F
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In this effort, we demonstrate the performance of a highly stable time reference for the proposed Black Hole Explorer (BHEX) mission, a space-based extension to the Event Horizon Telescope (EHT) Very Long Baseline Interferometry (VLBI) project. This precision timing system is based on the use of a space-qualified, ultra-low noise laser developed as part of the Laser Interferometer Space Antenna (LISA) mission as the timing reference, and an optical frequency comb to transfer the stability of this laser to the microwave regime for instrumentation use. We describe the implementation of this system and experimental setup to characterize the stability performance. We present the results of this experiment that demonstrate the performance of this system meets requirements for the BHEX mission.
13100-25
17 June 2024 • 11:00 - 11:15 Japan Standard Time | Room G214, North - 2F
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Tunable laser frequency combs that can map the point spread function across a spectrograph’s entire bandwidth are necessary for improving the instrumental systematics to reach near-infrared radial velocity precision levels < 1 m/s. We demonstrate a scannable 30 GHz electro-optic (EO) comb by tuning a combination of laser center frequency and mode spacing. This tandem tuning is necessary to avoid cavity-comb mode walk-off in a Fabry-Pérot cavity, which is used to suppress the broadband noise between the comb lines. This tuning is well-described by modeling the transmission of the EO comb through the cavity, and the entire supercontinuum spanning 700 – 1350 nm remains unchanged across the 30 GHz tuning range. We intend to implement this tunability for the 30 GHz EO comb deployed at the Habitable Zone Planet Finder (HPF) spectrograph.
13100-26
17 June 2024 • 11:15 - 11:30 Japan Standard Time | Room G214, North - 2F
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We introduce a new technique for directly calibrating an astronomical spectrograph using only a laser frequency comb, without support from auxiliary hollow-cathode-lamp or single-frequency-laser measurements. A comb-mode-resolving spectral shaper is employed in conjunction with a GPS-disciplined 20 GHz visible to near-infrared laser frequency comb to optically isolate a single comb mode. This mode is measured to an accuracy of 60 MHz (0.002 cm-1) by an optical wavemeter, refined to sub-fm precision via the comb-equation, and used with the other comb modes to provide a complete frequency mapping of an astronomical spectrograph. Our approach eliminates the need for pre-calibration using a hollow-cathode lamp or a fiducial spectral marker from a single-frequency laser.
13100-27
17 June 2024 • 11:30 - 11:45 Japan Standard Time | Room G214, North - 2F
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The instrumentation plan for the ELT foresees the ArmazoNes high Dispersion Echelle Spectrograph (ANDES). The ANDES-project and consortium entered phase B in January 2022 and underwent several (internal and external) revisions by now to ensure that the requirements and eventually the challenging goals can be met by the physical design of the spectrograph.
Among its main scientific goals are the detection of atmospheres of exoplanets and the determination of fundamental physical constants. For this, high radial velocity precision and accuracy are required. Even though the ANDES-spectrograph is designed for maximum intrinsic stability, a calibration and thus a calibration unit is mandatory. To allow for maximum flexibility and modularity the calibration unit is physically split into three calibration units.
We show the physical design of the calibration units and their individual components. This includes the electronics, the mechanics and the software supporting and controlling the light guiding and calibration sources.
13100-28
MOONS – Multi object spectroscopy for the VLT: testing and integration of the MOONS metrology system
17 June 2024 • 11:45 - 12:00 Japan Standard Time | Room G214, North - 2F
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MOONS is the Multi-Object Optical and Near-IR Spectrograph for ESO’s Very Large Telescope. The instrument will use ~1000 optical fibres which can be individually aligned to on-sky targets across a field of view of ~500 square arcmin. Each fibre is positioned using a dual arm theta-phi fibre positioning unit (FPU). The MOONS metrology system must be able to simultaneously measure the position of each fibre to a high accuracy (~15 micrometres) as well as measuring the orientation of the FPU arms. In this paper, we present a description of photogrammetry-based metrology system design and its implementation in the instrument. We also report on the integration, testing, and performance of the system within the instrument.
13100-29
17 June 2024 • 12:00 - 12:15 Japan Standard Time | Room G214, North - 2F
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The KASM (Keck Adaptive Secondary Mirror) project requires Calibration and Verification Equipment (CAVE) to verify the performance of both the optical surface and the actuators’ motion. The designed system must accommodate use both as a tool for verification and integration as well as calibration during operation at the telescope facility. We detail the proposed optomechanical design for CAVE including error budgets and a concept for operation at the telescope.
Break
Lunch Break 12:15 - 13:20
Session 6:
Calibration, Test and Metrology II
17 June 2024 • 13:20 - 15:05 Japan Standard Time | Room G214, North - 2F
Session Chair:
Trupti Ranka, GMTO Corp. (United States)
13100-30
17 June 2024 • 13:20 - 13:35 Japan Standard Time | Room G214, North - 2F
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We designed and manufactured two OGSE dedicated to the alignment of the EUCLID telescope. These two wavefront-based platforms, set on hexapods, have been used to measure the transmitted WFE in the VIS path and the NISP path of the EUCLID payload. We present the OGSE and more specifically the Imagine Optic R-FLEX platforms. Some wavefront error maps obtained by ADS team during the AIT campaign in Toulouse are discussed.
13100-31
17 June 2024 • 13:35 - 13:50 Japan Standard Time | Room G214, North - 2F
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Stray light testing is a crucial step in the development of space optical instruments, ensuring that designs perform as theoretically predicted and are free from unexpected stray light effects. Beyond this verification, stray light testing also generates kernels for stray light correction algorithms. Traditional stray light testing methods, while essential, often fall short due to their binary pass/fail output and increasingly stringent stray light requirements. To address this limitation, we have developed and demonstrated the Time-of-Flight (ToF) method for stray light characterization. Our initial application on a simple three-lens system showcased the method's potential for comprehensive stray light assessment, effectively deriving the origin of individual stray light contributors. This paper presents the latest advancements in the ToF method, highlighting its successful application in the test campaign for the NAC instrument, designed for returning samples from Mars in the frame of the Earth Return Observatory mission. Additionally, we will discuss the ToF method's effectiveness in characterizing a stray light baffle, demonstrating its broader applicability.
13100-32
17 June 2024 • 13:50 - 14:05 Japan Standard Time | Room G214, North - 2F
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We developed a new opto-mechanical tool to quickly align an optical beam to a reference mechanics. In the alignment of the SOXS Common Path, one of the sub-systems of the SOXS instrument, we used a referenced (and characterized) detector to align the master laser beam to the mechanical structure of the subsystem, and to place and align individual opto-mechanical components to the master laser beam.
Based on that experience, we conceptualized and prototype a new effective and much more efficient and easier to handle tool for alignment. A sphere is 3D printed to host a small bare-board CMOS detector with the sensor plane passing through the center of the sphere. This tool used in combination with a portable Coordinate-Measuring Machine (pCMM) allows for a quick alignment of a narrow collimated laser beam or a converging beam on an optical bench as in 3D space. We describe the design, prototyping and test of this new alignment tool.
13100-33
17 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
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India joined as one of the partner to Thirty Meter Telescope (TMT) project and delivers 84 hexagonal segments for the primary mirror. Stressed Mirror Polishing (SMP) technology is being adopted for polishing the glass roundels and cropped into hexagon before mounting over the segment support assembly. Low spatial frequency error from the polished roundel surface is measured with 2D Profilometer (2DP) built by Coherent Inc., USA. 2DP is constructed with two thin Carbon Fiber Reinforced Panels of ~1600mm diameter sandwiched by an aluminium honeycomb structure of thickness ~75mm. Sixty-one mechanical probes are distributed across panels in a spiral pattern to avoid any overlapping while 2DP collecting data on roundel by multiple clocking. 2DP panels tend to bow when the temperature between the top and bottom panel changes and hence power to the measurement on the roundel surface. The sensitivity of the 2DP to the temperature gradient is studied in the laboratory and we present the results in this paper.
13100-34
CANCELED: Innovative design concept combining freeform mirrors and freeform sensor
17 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
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To achieve high imaging performance in a compact form factor for space imaging applications, we propose a novel design concept that combines freeform mirrors and freeform sensor. First, we analytically demonstrate that an off-axis system exhibits an optimal focal surface with a freeform shape according to nodal aberration theory. We then validate our approach by designing a three-mirror system featuring a 10cm aperture, F/2, and a 12-degree diagonal field of view. The combination of freeform mirrors and freeform sensor enables the system to achieve diffraction-limited imaging performance within a 10-liter volume. Moreover, the manufacturability of the freeform sensor is ensured through the analysis of CMOS chip bending capability and the evaluation of sensor manufacturing precision. We anticipate that our work will provide innovative solutions for future high-performance small satellite imaging instruments, applicable to earth and space observations.
13100-311
17 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
13100-35
17 June 2024 • 14:35 - 14:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Small Aperture Telescopes of Simons Observatory aim to detect the primordial B-mode power spectrum in Cosmic Microwave Background. For the precise measurement of the B-mode, we need to reduce systematic errors from the miscalibration of the polarization angle of transition-edge sensors. We have developed a calibrator using Sparse Wire Grid (SWG). It can calibrate all the detectors at the same time and allows us to extract information on polarization angle, time constant, and polarization efficiency. In this conference, we will present the calibration method and results using SWG.
13100-36
17 June 2024 • 14:50 - 15:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Wind load will lead to structural deformation and severely influence the radiation pattern of the reflector antenna of Leighton Chajnantor Telescope (LCT). For accurately and rapidly analyzing the radiation pattern of LCT’s reflector antenna under wind load, we develop a quick calculation method for the radiation pattern of LCT’s deformed reflector antenna based on our previous work on the effect of gravitational load on the radiation pattern. By proposing an approximate optical path difference (OPD) calculation method for LCT’s deformed reflector antenna and an OPD fitting function based on the modified Zernike polynomials, we obtain the radiation pattern by the aperture field integration method. Numerical experiments demonstrate the accuracy and rapidity of the proposed method for analyzing the radiation pattern of the LCT’s reformed reflector antenna under wind load.
Break
Coffee Break 15:05 - 15:30
Session 7:
Adaptive Optics, Active Instruments and Vibrations
17 June 2024 • 15:30 - 17:15 Japan Standard Time | Room G214, North - 2F
Session Chair:
Eduard R. Muslimov, Univ. of Oxford (United Kingdom)
13100-37
17 June 2024 • 15:30 - 15:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Integral fields units such as lenslet-arrays, fibre-bundles or image-slicers all suffer from inefficient over-sampling of the spatial PSF unless anamorphic magnifying optics are used, which adds optical aberrations, and reduces optical throughput. In 2014 we presented the novel twisted image slicer concept that produces fully Nyquist-sampled data cubes without the use of anamorphic optics; in 2022 we presented the opto-mechanical design of a prototype twisted image slicer, its nominal performance, and preliminary characterisation results; in this paper we present the full characterisation of the individual image slicer mirror surfaces, and the overall wavefront error of the image slicer, demonstrating the feasibility of the concept and the excellent finish of the mirror surfaces of the prototype image slicer.
13100-38
17 June 2024 • 15:45 - 16:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This paper describes the status and first results of the Adaptive Secondary Mirror (ASM) for the NASA InfraRed Telescope Facility (IRTF). The ASM consists of a 244mm-diameter convex aspherical mirror shell, manipulated by 36 variable-reluctance actuators, designed to retrofit the passive M2.
The ASM was shipped to UH in Hilo in February 2024, where performance was tested in the lab. The IRTF ASM saw ‘first light’ on telescope on the 23rd of April, already attaining a closed loop image that was diffraction limited at the H-band with a long-exposure Strehl at 1.62 microns of ~35%-40% in sub-arcsecond seeing during the first night. This paper will report on the status and first results of the IRTF ASM, including the latest status of the deformable mirror technology at TNO and an outlook to a second generation IRTF ASM with improved dynamic performance and increased actuator count.
13100-39
17 June 2024 • 16:00 - 16:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Adaptive optics systems that use adaptive secondary mirrors can potentially broaden the use of AO in astronomy. However, unlike post-focal plane AO systems, ASM-based AO systems require large (200-1500 mm diameter), curved, aspheric membranes to replicate the standard telescope secondary mirror that it replaces. A key limitation of current devices is the cost (and associated risk) of manufacturing thin (<3 mm) curved facesheets. We have developed a new approach for fabrication of these facesheets that uses initially flat, polished sheets of glass that are formed into curves via heating, while being held only by a ring on the outer diameter and a distributed weight on the top side. We have tested this over a variety of size ranges from 300-600 mm, and for a range of radii of curvature from 1000-5000 mm. We will report on the final surface errors of these devices and the status of developing a process to integrate the initially flat sheets into a curved deformable mirror assembly suitable for adaptive secondary mirror on medium to large aperture telescopes. Demonstration of such a technique will lay the groundwork for more economical and robust ASM’s.
13100-40
CANCELED: Broadband vibration control using an inertial actuator
17 June 2024 • 16:15 - 16:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
We investigate using an inertial actuator to actively attenuate mechanical vibrations. We want broadband performance where “broadband” means multiple octaves in frequency.
We start with an analysis of the fundamental behavior of a model system and its closed-loop control, and then test a hardware system that represents a cryogenic cooler mounted on a spring suspension. This is something that might be found on an instrument used on a large astronomical telescope.
The hardware test results show appreciable vibration attenuation over more than 3 octaves. This is despite the presence of resonances and other dynamics not considered in the analytical model. Additionally, neither the analytical nor hardware controller required sensitive tuning to the plant dynamics, and both systems are unconditionally stable.
13100-41
17 June 2024 • 16:15 - 16:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Instrument rotators provide high accuracy instrument rotation at a commanded angle to ensure telescope pupil tracking. The experience gained over the years in working with several types of rotators is summarized in this paper. Not only experimental methods, but also mechanical and control models have allowed us to understand the system in depth. The paper focuses on rotators with two servomotors working together to counteract backlash and rotators with directly coupled motors. For the latter, balanced and unbalanced loads are studied. The mechanical model used to control the servo is explained and analyzed. During the development of the study, different rotator work schedules will be investigated. Tracking will be the focus of the study. The HARMONI rotator and the QUIJOTE telescopes (telescopes built by the Spanish company IDOM) in operation at the Teide Observatory (Tenerife) will therefore be the focus of our attention.
13100-42
17 June 2024 • 16:45 - 17:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The TOLIMAN space telescope is purpose-built to probe our stellar neighbourhood for potentially habitable Earth-like exoplanets. Our novel diffractive pupil design will allow TOLIMAN to detect extremely subtle changes in the positions of stars in binary systems, down to the microarcsecond scale. One of the many limiting factors in the detection of this diminutive astrometric signal is instability in the telescope pointing, such as jitter and wander.
This work demonstrates the capability of mitigating the blurring effects of telescope jitter through a forward modelling approach and the use of a new piezo-driven tip/tilt system. This methodology enables us to recover crucial astrometric parameters despite telescope pointing instability, offering TOLIMAN the opportunity to observe exoplanetary signatures with unprecedented precision.
13100-43
17 June 2024 • 17:00 - 17:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This article presented the design improvement based on the modal frequency shifting method for resolving the structural response excitation of a catadioptric telescope. For the high image quality demand optical system, the positioning stability of optics is crucial. Taking the catadioptric telescope for example, the most sensitive part is the position of secondary mirror within several micrometer tolerance along optical axis. Therefore, the opto-mechanical design for maintaining the positioning of optics while the system suffering from the harsh environmental vibration becomes important.
Tuesday Plenary
18 June 2024 • 08:30 - 10:00 Japan Standard Time | National Convention Hall, 1F
View Full Details: spie.org/AS/tuesday-plenary
13173-502
The present and future of Japan's space program
(Plenary Presentation)
18 June 2024 • 08:30 - 09:15 Japan Standard Time | National Convention Hall, 1F
Show Abstract +
The Basic Plan on Space Policy sets forth the basic principles of Japan's space policy with an aim to promote policies for space development. The latest version, approved by the Cabinet in June 2023, marks a significant shift by defining space science as a crucial integral part of Japan's space development efforts, transitioning from treating it solely as an isolated academic activity. For instance, the Artemis program is promoted as a policy initiative where scientific exploration is positioned to serve a precursor role. It also encourages Japan’s involvement in NASA's post-JWST efforts. Here, I will present Japan's recent accomplishments and future plans in space science.
13173-503
NASA astrophysics: from today to the Habitable Worlds Observatory
(Plenary Presentation)
18 June 2024 • 09:15 - 10:00 Japan Standard Time | National Convention Hall, 1F
Show Abstract +
The goals of the Astrophysics Division are to understand how the universe works, understand how we got here and to address the question, are we alone? In this talk, Dr. Clampin will discuss the current goals of the Astrophysics Division, and its suite of current and future missions. He will also preview progress towards the 2020 National Academies (NAS) Decadal Survey including the key recommendation, the Habitable Worlds Observatory and NASA’s approach to its implementation. Dr. O’Meara will discuss the first steps towards implementation, the formation of a Science, Technology, Architecture Review Team (START) and Technical Analysis Group (TAG) for HWO. He will describe how these teams, along with a large cohort of volunteers are working to define the trade space that must be explored for HWO to meet its top science goals of surveying exoplanets for the signatures of life and performing transformational astrophysics.
Break
Coffee Break 10:00 - 10:30
Session 8:
Optics and Support Systems
18 June 2024 • 10:30 - 12:45 Japan Standard Time | Room G214, North - 2F
Session Chair:
Ralf Jedamzik, SCHOTT AG (Germany)
13100-44
18 June 2024 • 10:30 - 10:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Space telescopes often face aperture size constraints due to launch vehicle dimensions, resulting in reduced apertures and compromised optical resolution. Addressing this, deployable optical payloads with segmented mirrors unfolding like petals can enhance synthetic apertures and spatial resolution. This paper compares Additive Manufacturing (AM) and Topology Optimization (TO) design in ultra-precision machining, with a focus on single-point diamond machining. The dual goal is to simultaneously reduce fixture weight and increase stiffness, countering deformations induced by rotational and cutting forces. Finite Element Analysis compares fixtures from conventional machining with those using AM and TO, shows a 68% weight reduction in TO-designed fixtures. This advancement allows a single operator to handle assembly without specialized lifting equipment, offering a promising solution to overcome space telescope limitations by significantly reducing deformation caused by forces, benefiting astronomical and Earth Observation telescope apertures.
13100-45
18 June 2024 • 10:45 - 11:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This presentation will discuss potential solutions for making thermally feasible a space-based telescope concept that would use a 6.5 m monolithic borosilicate primary mirror. The models include orbital calculations to account for environmental constraints and internal heat transfer models to account for thermal stability. In the future, such a telescope could be launched into space without the need for in-orbit assembly or deployments, decreasing the project complexity and cost.
13100-46
18 June 2024 • 11:00 - 11:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Center of Curvature Optical Bench (CoCOB) hexapod, originally designed for James Webb Space Telescope program testing, was re-purposed to provide precision positioning of large test articles as part of a facility capability upgrade at the X-Ray & Cryogenic Facility (XRCF) at the NASA Marshall Space Flight Center. The analytical tools developed to assess and display the possible range of motion combinations for various center of rotation locations are discussed along with the results of the study. A hexapod load study was also completed to determine maximum allowable payload mass across a wide array of possible hexapod poses. Modeling was used to assess deflections as a function of the displacement away from the hexapod’s null position and the associated impact on accuracy performance. Software techniques to prevent collisions between internal hexapod geometry and avoid overtravel of both actuator stroke and end-joint angular travel ranges are also discussed.
13100-184
18 June 2024 • 11:15 - 11:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
COSMO Large Coronagraph is a 1.4m diameter lens refractive coronagraph dedicated to the measurement of the magnetic field of the Sun corona. The internal occulter can adjust its size as the Sun apparent dimension changes through the year. In addition, this object prevents the formation of internal seeing: the intense heat coming from the Sun activates significant hot air motion (natural convection) which is detrimental to the quality of the image. Seeing prevention is accomplished by a cooling subsystem which employs a liquid cooling circuit and an air system management.
13100-48
18 June 2024 • 11:30 - 11:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
A global overview of the system setup will be presented including the main system performance parameters. Most important will be the results concerning its performance characteristics. Main topics will be image quality (low and high power), pointing stability, output beam polarization, irradiance profile and throughput. All these performance parameters are measured as function of variable environmental conditions. Test results concerning the robustness to handling operations will also be reported
13100-49
18 June 2024 • 11:45 - 12:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Safran Reosc was awarded the manufacturing of the Secondary Mirror of the Extremely Large Telescope by ESO in 2016. The secondary mirror is a 4-meter convex mirror, the world’s largest convex precision mirror ever made. This mirror is currently in its final phase of polishing. It is controlled on a dedicated interferometric test bench specifically designed to achieve the best accuracy on such a large mirror. The test bench has been thoroughly validated in September 2023 and all its requirements were demonstrated. In this paper, we present the design of the test bench and the results of its calibration and validation. This bench includes a convex-concave test plate together with a unique custom interferometer system, which are both presented. The test bench makes a measurement on several sub-pupils which are stitched together to reconstruct the final surface error of the mirror. A specific stitching algorithm was developed and is presented in this paper. We also present the design and validation of the supporting device, which allows to hold the mirror on the test bench without deformation. Lastly, the full performance budget is detailed along with the main critical tolerances.
13100-50
18 June 2024 • 12:00 - 12:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This paper details the design, prototyping and testing of several types of low-cost semi-kinematic optical mounts at NRC-Herzberg from a practical standpoint. Optical mounts tested cover a range of types intended to be easy to manufacture, quick to assemble and suitable for various instrument environments. Assembly repeatability in tip/tilt/focus, assembly time, and wavefront error due to stress birefringence (simulated) are quantified and results presented. Thermal stability, suitability for use in cryogenic environments and ease of manufacture/assembly are also analyzed. Various qualitative metrics are also discussed. Quantitative and qualitative metrics are discussed and presented in a design table to aid in directly comparing lens mounting concepts. Results are also interpreted to determine the direction of future R&D efforts towards creating large-scale, multiplexed instruments.
13100-51
18 June 2024 • 12:15 - 12:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Arrayed Wide-Angle Camera System (AWACS) is based on segmented-field corrector architecture and can be scaled to a much larger than meter-size field of view featured in Extremely Large Telescopes (ELTs). In essence, the AWACS accomplishes desired field expansion via a suite of small cost-effective electro-opto-mechanical units over a telescope’s focal surface, for local and simultaneous telescope field aberration and atmospheric dispersion compensation (ADC). In our previous report, we summarized the architectural features and design examples of the AWACS and discussed the snapshots of the components/subsystems of the AWACS-Duo at various development stages. In April 2023, we had a first on-sky run on the 2.7m Harlan J Smith Telescope to commission the rest of the system functionalities. The on-sky commissioning included verifying the guiding and acquisition, imaging performance and field aberration compensation across 1.2-degree telescope field, the ADC operation and performance, and throughput consistency between two AWACS units, all with respect to the model expectations. This report summarizes the results from this commission effort and the plan forward.
13100-52
18 June 2024 • 12:30 - 12:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
In ground-based mid-infrared observations the background radiation must be removed. Chopping is a background removal method requiring fast switching of the observation field. For MIMIZUKU, the mid-infrared instrument for the TAO telescope, we have developed a cold chopper which switches the observing field by tilting a movable mirror inside MIMIZUKU, instead of tilting the large secondary mirror.
We require a short transition time, sufficient amplitude, high frequency and steadyness for observation in the chopper movement.
With Repetitive Control we significantly increase performance by iteratively improving a feedforward trajectory and continously adapting to changes in the nonlinear dynamics.
This allows for much shorter transition time (<30 ms) and more freedom in the design of a feedback controller. Furthermore, repetitive disturbances originating from the cryo-cooler can be countered thus improving stability on sky.
Controller design, stabilisation, choice of reference trajectory, real-time computability and performance trade-offs are subjects in this research.
Break
Lunch/Exhibition Break 12:45 - 13:50
Session 9:
Telescope Structures, Domes and Additive Manufacturing
18 June 2024 • 13:50 - 14:50 Japan Standard Time | Room G214, North - 2F
Session Chair:
Eduard R. Muslimov, Univ. of Oxford (United Kingdom)
13100-53
18 June 2024 • 13:50 - 14:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Recently approved by the European Space Agency (ESA), the large-scale scientific mission NewATHENA will explore the hot and energetic universe using advanced X-ray technology. The key component of the telescope will be hundreds of Silicon Porous Optics (SPO) modules arranged in an optical bench with a diameter of around 2.7 metres. Considering the overall size, the delicate cell structure and the high aspect ratio in combination with the material-related challenges of Ti6Al4V, addi-tive manufacturing using Direct Energy Deposition (DED) is a promising alternative to conventional processing. In addition to discussing fundamental challenges (e.g. shielding), the development of a high-performance hybrid DED process and associa-ted equipment for robust long-term production will be presented. The developed end-to-end manufacturing approach will be verified by manufacturing and analysing test specimens, geometric demonstrators and representative large scale breadboards.
13100-54
18 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This paper reports on a nested freeform Three Mirror Anastigmat (TMA) telescope designed for a 3U CubeSat, achieving a compact 1.5U form factor with a focal length of 500mm, F/4.6. Capable of near-diffraction-limited performance in a 0.37°x0.42° field of view, it provides 5m Ground Sampling Resolution in Low Earth Orbit. The paper explores two housing options: one for additive manufacturing (AM) and the other for conventional machining (CM), aiming to determine the optimal approach for creating an AM-based optical system housing suitable for space. The AM option offers lightweighting opportunities and enhanced structural integrity.
The mirrors, manufactured in RSA 443 with Nickel Phosphorus plating, alongside the AM material, AlSi40, are discussed for their homogeneous coefficient of thermal expansion crucial for orbital conditions. The paper reports on the AM process, system metrology, and high precision finishing through Ion Beam Figuring.
13100-56
18 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Additive Manufacture (AM) comprises a group of technologies that allow to go from a 3D model to manufactured components, creating them layer by layer until the part is complete. Among the advantages of AM, the ones that apply most to astronomical instrumentation are part complexity and consolidation, the addition of functionalities, design freedom and lightweighting capability.
The aim of this paper is to present the results of the studies carried out on the lightweight metal mirror samples with the two typologies and the most promising material of those studied within the IAC for H2020. Comparisons will be made mainly in terms of metrology, dimensional tolerances and optical surface finishes of the mirrors (roughness, SFE, etc.).
13100-57
18 June 2024 • 14:35 - 14:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Despite the established role of Additive Manufacturing (AM) in aerospace and medical fields, its adoption in astronomy remains low. Encouraging its integration in a risk-averse community necessitates documentation and dissemination of AM case studies. To address this challenge, this paper endeavours to be the first review in this field, with the main scope being the dissemination of current applications and understanding the status of AM adoption. This will be done through compiling components, applications, and previously non reported AM case studies in astronomy hardware. A qualitative analysis of compiled literature, revealing application trends and benefits, challenges, as well as untapped opportunities where AM can be further researched and implemented. Qualitative data collected through interviews and forms with different engineers and scientists who previously researched/used AM in astronomical hardware will be presented, highlighting the obstacles and challenges hindering a wider adoption of AM.
Break
Coffee Break 14:50 - 15:20
Session 10:
Spectroscopy: Gratings, Dispersers and Image Slicers I
18 June 2024 • 15:20 - 16:50 Japan Standard Time | Room G214, North - 2F
Session Chair:
Andrea Bianco, INAF - Osservatorio Astronomico di Brera (Italy)
13100-58
18 June 2024 • 15:20 - 15:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The solar corona has a temperature of millions of K and a series of emission lines in the UV and EUV that have a crucial role in the full understanding of its physics. The only UV coronagraph/spectrometer flown so far is SOHO/UVCS, operative from 1995 to 2009. It was characterized by a 40 arcmin linear slit tangent to the solar limb, moved at different heliocentric heights by means of a tiltable mirror. Different polar angles were explored by rolling the whole instrument. Despite the milestone results it successfully provided, UVCS was not suited to follow the solar corona dynamics: coronal phenomena may evolve on times that range from minutes to hours, while a complete coronal spectrocopic map at full resolution took about 1 day for UVCS to be acquired.
A circular slit with variable radius coupled with a circular grating would reduce by at least 1 order of magnitude the time range for mapping the whole solar corona spectrum. CISS (Circular Slit Spectrometer) is a project funded by the Italian National Institute for Astrophysics (INAF) dedicated to the development of a prototype of such a spectrometer. This work presents the prototype design and the status of the project.
13100-60
18 June 2024 • 15:35 - 15:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
We present the most up to date advancements in production, design, and performance of the NexGen Micro-Shutter Array (NGMSA) for Multi-object Spectroscopy (MOS), intended for the future Habitable Worlds Observatory (HWO) Flagship. A microshutter array functions as a programmable slit mask, to generate slits corresponding to sparsely distributed sources in the field of view of a telescope. In contrast to the magnetic/electrostatic microshutter arrays used in the James Webb Space Telescope (JWST), the NGMSA is fully operated by electrostatics, simplifying overall system. Our small pilot array proved its capability from FORTIS sounding rocket mission in 2019. As we are switching to a larger HWO flight size array process, we encounter multiple processing related issues. Also, there has been individual shutter level issue that impairs operation and performance. We will discuss those problems and strategies to overcome the challenges to achieve an on/off contrast of >1e5 with near 100% shutter operability.
13100-61
18 June 2024 • 15:50 - 16:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
With the ambitious goal of characterizing nearby Earth-like exoplanets, the Planetary Camera and Spectrograph for the Extremely Large Telescope (ELT-PCS) will need to push the boundaries of both high contrast coronagraphic imaging and integral field spectrograph technology. High contrast imaging spectrographs typically employ microlens array-based integral field units (IFU), which provide a large number of spaxels in exchange for short spectra and an inefficient use of detector pixels. In contrast, image slicers provide a high detector use efficiency with a broader spectral bandpass. We report on the progress of a trade study into IFU design choices for ELT-PCS using a modular integral field spectrograph test-bench. At the core of the experiment are two custom-built IFUs: a novel image slicer-based IFU manufactured by Canon Inc. and BIGRE-like microlens array IFU. We provide an overview of the experiment, the individual performances of the two IFUs, and outline future applications of the test-bench for the design of the integral field spectrograph sub-system of ELT-PCS.
13100-62
18 June 2024 • 16:05 - 16:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Image slicer technology is in high demand for the largest night-time and solar telescopes, as well as for space applications. The science cases that define the design and development for current instrumentation, and the next generation of instruments, require pushing image slicer technology beyond current limitations. The need for narrower slicer mirrors to achieve higher resolution, better surface roughness to reduce stray light, and innovative ideas for highly efficient Integral Field Spectrographs led two projects developed in the UK by a consortium between Durham University and University College London: MINOS and LUCES. MINOS has produced a prototype of slicer mirrors with the best results ever achieved in glass: a surface roughness of 0.2nm RMS in the thinnest glass slicers with a width of 70 microns on a spherical substrate, while LUCES investigates the best performance for metallic slicers using diamond machining producing nine demonstrators to determine the thinnest slicer width possible and the material that offers the best surface roughness. This communication presents the best performance currently achievable for glass and metallic image slicers.
13100-63
18 June 2024 • 16:20 - 16:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Fiber optics based spectrographs have seen drastic improvements in multiplex capability; the number of simultaneously observable astronomical objects are expected to reach the tens of thousands. A large number of spectrographs are needed in order to accommodate this increasing target count.
We present a design and laboratory evaluation of a prototype pre-spectrograph wavelength splitter and pupil slicer (WSPS) in order to nullify large wavelength splitters within multiwavelength channel spectrograph optics, and increase packaging efficiency of the single channel spectrographs.
The WSPS is an optical assembly that interfaces to a subset of the incoming fiber optics (~100 per unit), splits the light into multiple wavelength channels (Blue, Green, Red, J, and H), and allows implementation of an arrayed output configuration to slice up the pupil. This assembly must achieve excellent light coupling and effectively suppress scattered light in order to distinguish faint from bright objects illuminating the same WSPS unit.
13100-64
18 June 2024 • 16:35 - 16:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The TOLIMAN space mission confronts the challenge of detecting Earth analogues in the immediate solar neighbourhood by using novel astrometric techniques. This bespoke, low-cost mission will employ a novel optical and signal encoding system, enabling high-precision measurements typically requiring larger instruments. Targeting the Alpha Centauri system, TOLIMAN will utilise an innovative diffractive pupil to mitigate the limitations of a relatively modest satellite and payload infrastructure to make measurements at the extreme precisions required. Here we describe the design and manufacturing of the pupil, which employs liquid-crystal technologies and low CTE substrates, all aiming to render measurements impervious to unavoidable optical distortions and aberrations.
Wednesday Plenary
19 June 2024 • 08:30 - 10:00 Japan Standard Time | National Convention Hall, 1F
View Full Details: spie.org/AS/wednesday-plenary
13173-504
Euclid mission: first year of operations
(Plenary Presentation)
19 June 2024 • 08:30 - 09:15 Japan Standard Time | National Convention Hall, 1F
Show Abstract +
After launch on 1 July 2023, the Euclid space telescope of the European Space Agency (ESA) has begun its 6-year mission designed to understand the origin of the Universe's accelerating expansion, which is commonly associated with Dark Energy. By observing billions of galaxies, Euclid will create a 3-dimensional map of the Universe covering 10 billion years of cosmic history. It contains the hierarchical assembly of (dark) matter in galaxies, clusters and superclusters telling us about the nature of gravity and giving us a detailed measurement of the accelerated expansion of the Universe in time. The stringent image quality and sky survey requirements impose extreme performances of the telescope, instruments, and spacecraft. After a mission summary, I will describe the in-orbit spacecraft and instrument performances. A notable challenge is the processing of the large volume of data. The scientific prospects of Euclid are illustrated with the first images and early science results.
13173-505
The ultraviolet explorer: new views of the UV universe
(Plenary Presentation)
19 June 2024 • 09:15 - 10:00 Japan Standard Time | National Convention Hall, 1F
Show Abstract +
The Ultraviolet Explorer (UVEX) mission, scheduled for launch in 2030, advances three scientific pillars: exploring the low-mass, low-metallicity galaxy frontier; providing new views of the dynamic universe, and leaving a broad legacy of modern, deep synoptic surveys adding to the panchromatic richness of 21st century astrophysics. The UVEX instrument consists of a single module with simultaneous FUV and NUV imaging over a wide (10 sq. deg) FOV and sensitive R>1000 spectroscopy over a broad band from 1150 - 2650 Angstroms. In this talk I will describe the UVEX scientific program and provide an overview of the instrument and mission.
Break
Coffee Break 10:00 - 10:30
Session 11:
Spectroscopy: Gratings, Dispersers and Image Slicers II
19 June 2024 • 10:30 - 12:15 Japan Standard Time | Room G214, North - 2F
Session Chair:
Andrea Bianco, INAF - Osservatorio Astronomico di Brera (Italy)
13100-65
19 June 2024 • 10:30 - 10:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Volume phase holographic gratings (VPHGs) manufactured with dichromated gelatin (DCG) have become a staple of astronomical spectrograph design due to their high first order diffraction efficiency, low stray light, and high index modulation, which enables wide spectral bandwidths and angular tuning. In this talk, we will look at one optical limitation of VPHGs – wavefront error – and how custom magnetorheological finishing (MRF) can be used to mitigate it. We will demonstrate the improvement achieved with MRF using an exploratory grating fabricated for the future HARMONI Spectrograph to be deployed at ESO’s Extremely Large Telescope (ELT).
13100-66
19 June 2024 • 10:45 - 11:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews.
The diffraction gratings are the single biggest contributor to the instrument’s throughput loss. Additionally, the range of operating modes and configurations available to HARMONI users will result in a varying beam footprint at the grating surface. HARMONI’s four spectrographs will be equipped with 10 gratings each, requiring a bespoke automated test facility to qualify the transmission performance of all the HARMONI gratings.
This paper describes the test bench, and presents transmission efficiency results for different HARMONI gratings.
13100-67
19 June 2024 • 11:00 - 11:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Volume Phase Holographic Gratings (VPHGs) have introduced, in recent years, a significant improvement in low and medium resolution spectrographs with an apparent throughput step up. They are still considered the baseline for the DE in low and medium resolution spectrographs. At INAF-Osservatorio Astronomico di Brera, we have been developing VPHGs based on an innovative approach for some years. Almost 15 produced VPHGs are operating in spectroscopic facilities and some prototypes are under production for several spectrographs. VPHGs up to 190 mm in diameter can be manufactured in a wide range of line density. Moreover, innovative configurations, such as multiorder grating and stacked grating, have been developed to increase the spectral range and resolution at the same time.
The next steps will be the improvement of the VPHG performances especially in the diffraction efficiency across the bandwidth and the transparency in the UV. Concerning the size of the diffraction elements, a new facility is under building that will be capable to produce VPHGs up to 450 mm in diameter.
13100-68
19 June 2024 • 11:15 - 11:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Over the past three years, we have been developing the Reactive Ion-PLasma Etched (RIPLE) grating technology and have demonstrated it to be a highly predictive process that has resulted in near theoretical super-broadband DE from the prototype 1x1 sq. inch RIPLE grating. All measured DE scans from this prototype closely resembled those from model predictions within 2% at 1σ-level, indicating the highly predictive nature of the process and the presence of a non-significant level of defects in the device. The fabrication process has shown to be repeatable over the same area and grating parameters, and we extended it to larger grating areas with deeply-etched grating line features. We demonstrated the area scaling to 2x2 sq. inch via an iterative etching technique. We are about to reach the primary 4x4 sq. inch target with strong possibility to ramp up to 5x5 sq. inch. We discuss the evaluation of the area scaling effort.
13100-69
19 June 2024 • 11:30 - 11:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Future far-infrared space missions bridging the gap between JWST and ALMA will utilize low-resolution grating spectrometers. To fully exploit the astronomical potential these instruments require compact, cryogenic and wideband grating modules with a large telecentric field of view. We present the opto-mechanical design and realization of a multi-purpose Grating Module Bread-Board (GMBB). Our design features a modular configuration consisting of a diffraction-limited collimator unit and camera bay optics allowing for easy adaptation to different wavelength/dispersion combinations of grating and detector. The opto-mechanical design is monolithic, and implements highly accurate and reproducable kinematic mounts. We present the driving concepts, methodologies, and engineering solutions, with special emphasis to blazed grating developments, supported by optical verification results.
13100-70
19 June 2024 • 11:45 - 12:00 Japan Standard Time | Room G214, North - 2F
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This paper focuses on the development of on-chip integrated spectrometry techniques with potential applications in the field of astronomy. The main objectives of this project are to achieve high-resolution spectrometry and improve the sensitivity of SWIFTS (Standing Wave Fourier Transform Spectrometer). The primary applications will be high-resolution spectrometry for precise measurement of atmospheric compositions of detected exoplanets well as other celestial bodies, such as the detection and analysis of specific gases like carbon dioxide (CO2) and methane (CH4) that are linked to life. The proposed SWIFTS approach offers advantages of high spectral resolution, compact size, and robust design. The project targets adaptation for astronomical observations in the short-wave infrared (SWIR) range (1000-2500nm) by employing directional nano-emitters to improve spectral range and sensitivity. Specific objectives include optimizing antenna fabrication for high resolution and creating a robust, one-piece spectrometer suitable for outdoor and airborne astronomical applications.
13100-71
19 June 2024 • 12:00 - 12:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Off-plane Grating Rocket Experiment pathfinder (OGRE-P) payload is a sub-orbital sounding rocket payload designed to obtain the highest resolution soft X-ray spectrum of Capella to date. OGRE was originally designed with a monocrystalline silicon X-ray optic developed by the Next Generation X-ray Optics Group (NGXO) at Goddard Space Flight Center (GSFC). This version of OGRE will be launched in the ultimate OGRE mission, OGRE-U. OGRE-P will use the Joint European X-ray Telescope (JET-X) in place of the GSFC optic in order to achieve an earlier launch date and test other components prior to the ultimate launch. JET-X has an angular resolution of 15 arcsec, which will produce an X-ray spectrum a factor of 3 broader than the GSFC optic. An updated error budget will be presented to reflect the alignment requirements for this lower spectral resolution optic, and the expected achievable resolution will be calculated. A plan for achieving alignment within these new tolerance requirements will be explained.
Break
Lunch/Exhibition Break 12:15 - 13:35
Session 12:
Coatings, Dichroics, Filters and Metasurfaces I
19 June 2024 • 13:35 - 15:20 Japan Standard Time | Room G214, North - 2F
Session Chair:
Hélène T. Krol, CILAS (France)
13100-72
19 June 2024 • 13:35 - 13:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Silver-based astronomical telescope mirrors (Ag-mirrors) excels in their optical performance across the visible to infrared spectrum. However, without proper safeguarding, they degrade significantly in high temperature/humidity environmental durability tests. Our research explored low-temperature atomic layer deposition (ALD) to prepare a 60 nm aluminum oxide (AlOx) protection coating for Ag-mirrors. We compared two oxygen precursors: water (H2O) and high-purity ozone (PO). PO, with over 80% purity, enables efficient ALD processes at lower temperatures, addressing challenges posed by H2O. During environmental tests, PO samples outperformed H2O samples. PO samples exhibited a minimal reduction (12%) in optical reflectance in comparison to H2O samples that showed substantial reduction (30%). Additionally, PO samples displayed a mere 6 nm phase shift in ellipsometry compared to 74 nm of H2O samples, indicating better structural integrity. Structural analysis revealed that H2O samples experienced erratic changes, compromising integrity, while PO samples maintained their original structure.
13100-73
19 June 2024 • 13:50 - 14:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Most telescope mirrors of the European ELT shall have protected silver coatings that are highly reflective across all astronomic wavelength bands from the UV (370 nm) to the far infrared. Another aspect is that the coatings shall be frequently cleaned in situ, so they must be highly durable against abrasion and chemical agents such as sulfur and salt. However, they also must be easy to strip with a non-toxic etchant before each recoating. We identify trades and optimize silver coating recipes with different protection layer materials and thicknesses to meet these partly contradictory objectives. A test coating campaign is ongoing.
13100-74
19 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Advanced telescope mirror coatings have become essential for enabling new and exciting astronomical discoveries. With their ability to maximize reflectivity, reduce scattering, withstand aggressive environments, and optimize specific optical properties, advanced thin film deposition systems help telescopes to see farther and fainter with less light than ever before. This paper discusses various types of film stacks and coating technologies that can be used for demanding coating applications. An overview of challenges with different system configurations will be discussed along with practical solutions to enable uniform, high performance, coatings on large mirrors. The suitability of various mirror coating technologies, such as filament evaporation, electron beam evaporation, and magnetron sputtering, will be discussed and compared for specific mirror coating applications. Hardware design challenges, including source placement, mask and uniformity optimization, and shutter reliability, will be evaluated. Prevalent issues with mirror handling, particles, and long-run reliability will also be discussed in detail.
13100-75
19 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The dielectric film is an important component of the reflective film. With the increasing requirements for the spectral range, reflectivity, environmental stability, and other performance of reflective films in large-aperture telescopes, the role of dielectric films in large-aperture mirrors is becoming increasingly crucial. With the development of optical coating technology, reflective films with different structures have been developed to meet the needs of different telescopes, and dielectric films play a crucial role in them. This article studies the application direction and key technologies of dielectric films in large-aperture astronomical telescopes, based on the coating situation of primary mirrors such as LAMOST and the Chinese National Astronomical Observatory's 2.5-meter telescope.
13100-76
19 June 2024 • 14:35 - 14:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Instrumentation Division of the Instituto de Astrofísica de Canarias (IAC) is involved since several years in upgrading its capacities to design and manufacture optical components. To this end, we have created a new laboratory (Centre for Advanced Optical Systems, CSOA) which will be capable to design, fabricate and qualify large optical elements. Within these efforts, an optical coating facility is being built aimed at coating and surface finishing of different components, such filters, mirrors and alike, with sizes ranging from few cm to about 1.5 m. The facilities are still in construction and we have already started to experience with medium size filters and mirrors, using a large variety of metallic coatings, both for anti-reflection properties and spectral band selection.
Our present capacities included a sputtering coating machine, capable to treat pieces up to half a meter of diameter, and E-beam and thermal evaporation. In this contribution we describe the current laboratory setup and report on the results achieved so far in the field of surface coating with different materials.
13100-77
19 June 2024 • 14:50 - 15:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
NASA’s future Habitable Worlds Observatory (HWO) will enable the direct detection and characterization of Earth-like planets around Sun-like stars using high-contrast imaging. One of the most promising approaches to achieve this goal is to use a vortex coronagraph. However, at the contrast levels required for HWO (1e-10), the polarization dependency and chromatic leakage of the vector vortex coronagraph becomes a limiting factor, making it challenging to perform wavefront control in both polarizations simultaneously. An alternative approach is to use a scalar vortex phase mask, which imprints the same phase ramp onto both polarizations. However, the broadband performance of the scalar vortex has to be improved to meet the contrast goal of HWO. Here, we present our advancements in optimizing metasurface-based scalar phase masks. We discuss broadband designs of different mask topographies, present first manufacturing results and outline the next steps needed to push the performance towards the levels needed for HWO.
13100-231
19 June 2024 • 15:05 - 15:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
ALD and ALE have emerged as thin-film coating techniques able to address several technical challenges in space instrumentation. This paper will describe recent work that applies these methods to improve the performance and stability of broadband protected-Al coatings, detector-integrated bandpass filter coatings, and narrowband reflective dielectric coatings. Systems that require the use of thin Al films can benefit from ALE methods that can remove the native oxide that would otherwise degrade UV performance. The performance of ALD mirror coatings operating at far UV wavelengths (90–200 nm) is presented in the context of the emerging needs of the Habitable Worlds Observatory. Trends in spatial uniformity are discussed considering the potential requirements of planned coronagraphic instruments. Extension of the same aluminum/fluoride material system to bandpass filters operating in the far UV are also discussed. Finally, we present recent work on new ALD process for high-index materials like LaF3, and present initial results of high-low multilayer stacks which can which can be useful to produce dichroic or narrowband reflective coatings in the UV.
Break
Coffee Break 15:20 - 15:45
Session 13:
Coatings, Dichroics, Filters and Metasurfaces II
19 June 2024 • 15:45 - 16:45 Japan Standard Time | Room G214, North - 2F
Session Chair:
Richard A. McCracken, Heriot-Watt Univ. (United Kingdom)
13100-226
19 June 2024 • 15:45 - 16:00 Japan Standard Time | Room G214, North - 2F
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This work addresses the need for efficient and uniform Al-based broadband mirrors in UV/O/IR-sensitive observatories while leveraging plasma-enhanced atomic layer deposition (PEALD) as a scalable, low-temperature, and highly conformal coating process. Hence, our collaboration between the US NRL and NASA GSFC focuses on enhancing the UV/O/IR performance of PEALD AlF3 films on Aluminum mirrors.
We are currently testing trimethylaluminum and SF6 plasma precursors in a customized Veeco Fiji G2 reactor, which includes an electron beam generated plasma to aid in native oxide removal from aluminum mirrors prior to deposition of AlF3 films. In-situ ellipsometry, plasma diagnostics, ex-situ x-ray photoelectron spectroscopy, atomic force microscopy, and reflectometry are used to optimize ALD windows and understand the influence of these parameters on the AlF3/Al interface and UV/O/IR optical performance.
13100-80
19 June 2024 • 16:00 - 16:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
We designed and manufactured an optical bench to characterize the EUCLID dichroic reflected wavefront at all useful incidences, all polarization states and each wavelength from 550nm to 950nm. The multilayer coating adds indeed some phase effect that vary suddenly in function of the wavelength. The testbed architecture, main functionalities and performances are presented. The preliminary results obtained on the dichroic mirror are compared to some simulations based on an up-to-date model of the multilayer coating.
13100-81
19 June 2024 • 16:15 - 16:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Habitable Worlds Observatory (HWO) concept NASA flagship mission aims to extend wavelength sensitivity down to 100 nm. Adding sensitivity capabilities near the Lyman series spectra of ~100-121.6 nm allows for observations of key diagnostic lines and heavily ionized gases with slight reliance of redshift. The lithium fluoride (LiF) overcoated aluminum (Al) coating offers high spectral efficiency down to ~100 nm while preventing oxidation of the Al. We investigate the optimization of the deposition of the Al+LiF coating material composition to attain high spectral efficiency and durable broadband reflectors down to 100 nm.
13100-82
19 June 2024 • 16:30 - 16:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The GMT-Consortium Large Earth Finder (G-CLEF) is a spectrograph, to be delivered as the first light scientific instrument for the Giant Magellan Telescope (GMT), and divided into a red and a blue channel.
In the frame of this project, Bertin Winlight is in charge of the manufacturing of the blue camera lenses, and entrusted CILAS to develop and realize the antireflection coatings on the 8 different lenses of this camera. The camera consist of 8 lenses with diameter in the 190 – 323 mm range made of CaF2 and other optical glass (BAL35Y, PBM18Y, BSM51Y).
We present the results on the design, development and manufacturing of antireflection coating with PIAD (Plasma-Ion Assisted Deposition) technology, which is well adapted to produce very dense layers and high quality coatings for severe environments.
The design of antireflection coating, in the spectral range 350-541nm, has taken into account large diameter and high curvature of the lenses and has been experimentally validated on a dummy shape. Moreover a dedicated coating process has been implemented and qualified on CaF2 substrates, leading to the successful coating of the 8 different lenses.
Thursday Plenary
20 June 2024 • 08:30 - 10:00 Japan Standard Time | National Convention Hall, 1F
View Full Details: spie.org/AS/thursday-plenary
13173-506
Navigating the radio astronomy renaissance: challenges and opportunities for a sustainable future
(Plenary Presentation)
20 June 2024 • 08:30 - 09:15 Japan Standard Time | National Convention Hall, 1F
Show Abstract +
The next decade heralds a renaissance in radio astronomy, with a formidable complement of global Observatories, from LOFAR2.0, to the SKA becoming powerful discovery engines at these lowest frequencies. While they commit to lowering data access barriers, managing the deluge of data poses challenges, as the new constraint on viable astronomy must move from hours on sky to data product cost in energy, compute and carbon and data footprint. I will explore with you the challenges and opportunities in creating a new frontier of sustainable, ethical, affordable astronomy.
13173-507
The x-ray imaging and spectroscopy mission (XRISM): development and expected science
(Plenary Presentation)
20 June 2024 • 09:15 - 10:00 Japan Standard Time | National Convention Hall, 1F
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The X-Ray Imaging and Spectroscopy Mission (XRISM) project was initiated in 2018 as the recovery mission resuming the high-resolution X-ray spectroscopy with imaging once realized but unexpectedly terminated by a mishap of ASTRO-H/Hitomi. XRISM carries a pixelized X-ray micro-calorimeter array and an X-ray CCD on the focal planes of two sets of X-ray mirror assemblies. The spacecraft was successfully launched from JAXA Tanegashima Space Center on September 7, 2023, and is now conducting performance verification observation followed by guest observations starting in August 2024. In this paper, we present the history of development and recent results.
Break
Coffee Break 10:00 - 10:30
Session 14:
Optical Fibers, Positioners, Photonic Techniques I
20 June 2024 • 10:30 - 12:15 Japan Standard Time | Room G214, North - 2F
Session Chair:
Andreas Kelz, Leibniz-Institut für Astrophysik Potsdam (Germany)
13100-83
20 June 2024 • 10:30 - 10:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
We present a new fibre positioner concept inspired by mechanisms used for minimally invasive surgery. The concept consists of a parallel mechanism that can be mass produced with laser cutting techniques and a tripod actuator mechanism for both positioning and maintaining focus. Advantages of the new design compared to existing positioner designs include very large patrol diameter per fibre (>30 mm) while allowing for very small pitch (~7 mm), very small minimal approaches between fibres, good clustering capabilities (20 fibres can reach a given sky location), easy control path and collision avoidance, robustness, mass producibility, the ability to accommodate non-telecentric and low-order polynomial focal surfaces, and the minimal bending and twisting of the fibre. A few design implementations will be presented.
13100-84
20 June 2024 • 10:45 - 11:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This paper presents the performances of recent high-tech hexapod positioning systems. Those devices with six degrees of freedom, are commonly used in Ground System Equipment (GSE) design, to qualify and conduct, for example, optical performance test activities. They are frequently used in vacuum environments. This is the case for example for EUCLID, CHIME, PLATO missions. They are also commonly used on large scientific instruments like Telescope or synchrotrons.
The latest innovations in terms of the performances, measurement technology, stability and control of those positioners are presented. The know-how the manufacturer has mastered to mature this technology and push the boundaries is on display. The characterization of the performance in terms of resolution, repeatability, accuracy, cross-coupling, backlash, and stiffness is clarified. The methods and measurement instruments used to characterize each specification are explained. Then, the most advanced performances of different hexapod positioners are described in detail. The goal of this step is to provide the current state of the art of hexapod technology and describe the most advanced system.
13100-85
20 June 2024 • 11:00 - 11:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Multi-Object Spectroscopy surveys are an essential tool for gathering astronomical data at sufficiently large volumes to draw statistically significant conclusions. A key enabling technology of MOS instrumentation is the fibre positioners which move optical fibres around the focal plane; maximising light throughput requires the fibre positioners to follow focal surface curvature within small tolerances while orienting the fibre tip towards the incoming light. Flexure-based designs have the potential to deliver several benefits for the next generation of MOS facilities and are being actively investigated.
In this paper we demonstrate two approaches for optimising flexure geometry to follow arbitrary focal surface curvature and to orient the optical fibre with arbitrary tilt. We demonstrate the applicability both to the UKATC’s preferred design for the Wide-field Spectroscopic Telescope, and to flexure-based fibre positioner designs generally. We also present a sensitivity analysis relating small changes in design parameters to changes in fibre tip motion.
13100-86
20 June 2024 • 11:15 - 11:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The fiber positioner robot is the most crucial actuator in the focal positioning system of a Multi-Object Spectrographs. The double-rotation form of fiber positioner was first extensively used in the Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST) in 2012. However, as multi-spectral telescopes continue to develop, there is a growing demand for smaller and lighter fiber positioners. Current focal positioning systems are now considering the use of 4mm motors, which are smaller than stepper motors. However, these motors do not come with a position sensor solution. Researchers have developed a miniaturized position sensor solution compatible with this motor, and it is installed in the center arm of the fiber positioner. Prototypes have been fabricated and, in conjunction with relevant experiments, this paper provides a detailed introduction to the specific impact this angle sensor has on the fiber positioner.
13100-87
20 June 2024 • 11:30 - 11:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Every photon of light is precious for astronomical observation. Light losses within telescope guiding systems and or losses via poor fiber coupling are common despite advances in photonic technologies in other industries. At CREOL, we develop a fiber feed assembly and alignment method which minimizes vignetting, light losses, optimizes fiber coupling, and optimizes signal-to-noise within our different COTS telescope guiding systems during astronomical observations. We can apply our techniques to the PolyOculus case and single-unit telescopes. We present our lithographic etching process, each variation of mechanical and optical alignment processes, the final coupling and assembly process, and how the assembly is integrated into a larger acquisition and guiding system for COTS telescopes.
13100-88
20 June 2024 • 11:45 - 12:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The demand for optical fibre connectors, which offer high throughput, outstanding reliability, and minimal Focal Ratio Degradation (FRD) has become critical in the era of large telescopes where science productivity could be enhanced if focal plane fibres and fibre bundles had the flexibility to be reconnected to feed to any of the instrument suite or for instrument changes. At Astralis we are investigating if it will be physically possible to develop a fibre connector with the ability to connect any fibre pairs without a difference in throughput at a 1% (aim, 2% requirement) level, which has not previously been possible, and is very challenging. The initial stages of this work have been focused on analysis of the best-performing existing connector with the goal of identifying areas where connector improvements are most needed. From that analysis, the main causes of FRD and throughput loss have been identified. New connectors are being prototyped to improve the fibre alignment, FRD from both the connector holes, expansion of materials and fibre pressures. We present our findings on the performance of the existing connectors in terms of fibre throughput and FRD.
13100-89
20 June 2024 • 12:00 - 12:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Photonic platforms and technologies can facilitate the miniaturization of astronomical instruments for high-resolution cross-correlation spectroscopy. Cascaded fibre Bragg grating (FBG) arrays, inscribed into optical fibres using direct femtosecond laser writing, form a target-tailored instrument spectrum. Flexible modulation of spectral features is achievable during instrument operation via strain tuning of the FBG arrays. We present a prototype astrophotonic fibre instrument based on this concept for cross-correlation spectroscopy. Experimental laboratory results of spectral modulation and cross-correlation analysis are presented for infrared molecular gas absorption. Additionally, efforts toward the on-sky integration of the instrument on a 1-meter-class telescope are demonstrated for targeted near-infrared spectral features.
Break
Lunch/Exhibition Break 12:15 - 13:20
Session 15:
Optical Fibers, Positioners, Photonic Techniques II
20 June 2024 • 13:20 - 15:05 Japan Standard Time | Room G214, North - 2F
Session Chair:
Andreas Kelz, Leibniz-Institut für Astrophysik Potsdam (Germany)
13100-90
20 June 2024 • 13:20 - 13:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
We present the design of an athermal package for fiber Bragg grating (FBG) filters for use in suppressing atmospheric hydroxyl (OH) emission lines in ground-based near-infrared (NIR) astronomy. We demonstrate the complete design methodology of such a package in a temperature range of of about 40 K (i.e. 263 K to 303 K). The design steps include, measurement of fiber characteristics, selection of possible combinations of materials for the temperature compensation, followed by determination of the nominal dimensions of the components. We finally discuss the novel aspects of the design to achieve high-precision thermal stabilization of these filters in the temperature range of interest. Our design is scalable to longer filter lengths and can also be used for other in-fiber devices for their stable operations in astronomical applications.
13100-91
20 June 2024 • 13:35 - 13:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Optical fibers are widely used in ground-based astrophysics, especially in the visible and near-infrared regimes. The use of fibers in other spectral regimes (such as the ultraviolet) and in the space environment has been limited due to the high absorption of most glasses in the UV and the radiation-induced degradation of glasses, respectively. Recently, we have demonstrated hollow-core optical fibers that transmit wavelengths as short as approximately 140 nm. Because oxygen and water vapor strongly absorb light with wavelengths shorter than 180 nm, we performed our transmission measurements in a chamber filled with high purity nitrogen. The fibers we measured show high transmission and low bend-induced losses in the 140 - 250 nm regime. Most recently, we have developed a vacuum system, capable of transmission measurements across the full FUV range (100 - 200 nm). Here, we present fiber transmission measurements in the 115 - 250 nm range and introduce some instrument concepts that are made possible by these FUV fibers.
13100-92
20 June 2024 • 13:50 - 14:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This work aims to present two different mid-IR (L-band) high resolution miniature integrated spectrometers, based on the novel Gabor approach of SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer). A stationary wave is obtained by injecting the light from the source on both sides of a channel waveguide. The stationary wave is sampled by nano-scattering centres (= nano-grooves) placed on top of the waveguide, that extract the interferogram : the spectrum of the source is then retrieved through a Fourier Transform. Ultrafast laser writing and ion-diffusion are used to fabricate two types of waveguides in Lithium Niobate substrates, an electro-optic crystal, that allows to finely scan the fringe packet under the sampling centres when an electric field ramp is applied.
13100-93
20 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
High-precision timing is vital in space communication for tasks like navigation, data transfer, and coordinating satellite constellations. Currently, ground segments rely on microwave clocks, but emerging optical clocks and links offer great improvements in resolution, precision, and stability for next generation systems. However, integrating optical clocks with conventional microwave sources presents a challenge. Our solution, an optical-to-microwave phase detector, addresses this by enabling synchronization with few-femtosecond residual jitter between an optical- and a microwave source. With a phase/timing resolution of 0.01 fs RMS and a noise-floor below 1 fs RMS, this detector becomes a key technology as optical clock adoption grows in ground segments.
13100-94
20 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Nulling interferometry has emerged as a promising technique for imaging exoplanets, effectively overcoming the challenges of contrast and angular resolution faced by ground-based telescopes. The Guided Light Interferometric Nulling Technology (GLINT) instrument at the Subaru telescope in Hawaii utilises this technique, where a new integrated optics beam combiner will be deployed, capable of simultaneously performing nulling interferometry and fringe tracking. Fabricated using the femtosecond laser direct write technique in boro-aluminosilicate glass, the beam combiner integrates three input single-mode waveguides forming 3 interferometric baselines. The design, fabrication and laboratory characterisation of the new beam combiner will be presented. The beam combiner comprises of 3D-printed micro lenses, a chrome mask, Y-Junctions, achromatic phase shifters and tricouplers to produce for each baseline an achromatically-nulled and two phase-sensitive bright outputs. This results in a total of 12 outputs that are directed onto a CRED1 camera.
13100-95
20 June 2024 • 14:35 - 14:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Using ultrafast laser inscription, a 2mm long 180° differential achromatic phase shifter was fabricated in borosilicate glass. An average phase shift of 171 ± 6° was measured between 1440-1640nm. Strategies to improve the phase shifters’ accuracy and fabrication tolerances are also discussed.
13100-96
20 June 2024 • 14:50 - 15:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Optical fiber spectroscopy technology is widely used in astronomical surveys. Due to the flexibility and long-distance transmission characteristics of the fiber, astronomical observation can gain larger scale and higher precision spectral data. Nowadays, a lot of representative technologies have been presented to enhance spectral resolution, including fiber integral field spectroscopy, fiber positioning technology in the sky survey, adaptive optics, and photonic lantern technology. The intrinsic flexibility of fibers lends itself readily to reconfigurable sampling of the field. Fiber integral field spectroscopy is one of the most typical techniques to enhance the spectrum resolution. The flexible combination of fiber bundle and microlens is used to improve the sampling rate of target stars and fitting factor. In the observation of target stars by a single fiber, the alignment accuracy between the fiber and the star image determines the spectrum resolution. In the multi-object telescope, the position of a large number of multi-mode fibers needs to be detected. Photonic lantern can convert the energy collected by multi-mode fiber into the output of single-mode fiber.
Break
Coffee Break 15:05 - 15:30
Session 16:
High Contrast Imaging and Polarimetry
20 June 2024 • 15:30 - 17:00 Japan Standard Time | Room G214, North - 2F
Session Chair:
Daewook Kim, The Univ. of Arizona (United States)
13100-97
20 June 2024 • 15:30 - 15:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The PLACID instrument installed at the new Turkish 4m-DAG telescope in 2024 will be the first active stellar coronagraph, offering a unique facility to perform innovative high-contrast imaging observing strategies. It is composed of a Spatial Light Modulator (SLM) in reflection in lieu of the usual fixed focal plane mask to digitally set up any phase mask in real time. However, such hardware works with a linearly polarized wave causing the loss of 50% throughput. To retrieve full capacity, PLACID will then be upgraded with polarization-independent solutions to be first tested on the Swiss Wideband Active Testbed for Coronagraphic High-contrast imaging (SWATCHi) 2.0. This testbed is also employed to investigate coherent differential imaging techniques that relies on the fast modulation of the speckle intensity whose signal is recorded with a C-RED ONE camera. This work presents the optical design and first results of SWATCHi 2.0.
13100-258
20 June 2024 • 15:45 - 16:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Mid-Infrared ELT Imager and Spectrograph (METIS) is one of the three first-generation instruments of the Extremely Large Telescope (ELT). One of the high-contrast imaging modes of METIS is implemented with a vortex coronagraph. However, the complex pupil of the ELT with its large central obscuration limits the performance of a classical vortex coronagraph. Using a grayscale ring apodizer in a pupil plane upstream of the vortex phase mask can correct for the effect of the central obscuration and partly restore the coronagraphic performance of the vortex for the ELT pupil. Here, we present the ring apodizer for the METIS instrument based on a Chromium microdots technology. We describe the design process of the microdot patterns and perform simulations with various geometric parameters, describe the manufacturing and testing of three prototypes and of the final ring apodizer for METIS.
13100-99
20 June 2024 • 16:00 - 16:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Visible light high-contrast imaging is exciting because of the possibility to detect accretion tracers like Hα at extremely small separations, but this is complicated by high atmospheric turbulence. To overcome this limit, AO188 is being upgraded and SCExAO/VAMPIRES has received more sensitive cameras and a multi-band imaging mode. To take advantage of these upgrades, a high-performance broadband coronagraph is needed. In this paper, we report on the installation of a liquid-crystal double-grating vector-vortex coronagraph with these properties in October 2023. We detail the high-quality manufacturing of the mask by Colorlink Japan, ltd and show its performance characterization with an internal source and on-sky using the multi-band imaging mode, simultaneously imaging four wavelength bands. We describe our efforts to calibrate the mask for polarimetry, review possibilities for an upgrade for simultaneous multi-band focal-plane wavefront sensing, and discuss the performance in the context of the balloon-borne PICTURE-D mission and future space missions.
13100-100
20 June 2024 • 16:15 - 16:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
High-contrast imaging instruments employ coronagraphs to study stellar environments by reducing the glare of stars. The Annular Groove Phase Mask (AGPM), a vector vortex coronagraph, is a valuable tool for achieving high-contrast performance at small angular separations. The METIS project, integrating multiple AGPMs for various LMN spectrum wavelengths, is currently in its Manufacture, Assembly, Integration, and Test (MAIT) phase. The performance of the METIS AGPMs is evaluated on two test benches: VODCA at the University of Liège for L- and M-band AGPMs and a cryogenic testbed at CEA Paris-Saclay for N-band AGPMs. The present study covers manufacturing, testing, centering processes, and coronagraphic performance results for all METIS AGPMs.
13100-101
20 June 2024 • 16:30 - 16:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Evanescent Wave Coronagraph (EvWaCo) uses the principle of frustrated total internal reflection to suppress the starlight. Its achromatic focal plane mask comprises a lens and a prism placed in contact. By varying the pressure between these components, the size of the mask is adjustable. Furthermore, this configuration allows light from the star and companion to be collected simultaneously. The EvWaCo testbed has been upgraded to include a deformable mirror. This paper shows preliminary results on correcting the non-common path aberrations using the algorithms designed for EvWaCo.
13100-103
20 June 2024 • 16:45 - 17:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The objective of the coronagraphic IFU of RISTRETTO is to enable High Dispersion Coronagraphy of planets
at a distance of 2λ/D from their star, without compromising on transmission. The new idea of a PIAA Nuller
(PIAAN) allows contrast down to 10−5 over large bandwidth ≥ 25%, with high transmission ≥ 70% at the
distance of 2λ/D. While RISTRETTO will be installed on a VLT, this development is of tremendous importance
for fully exploiting future ELTs XAO. We will discuss our PIAAN prototyping activities. This covers 1) the
characterisation of our 2nd set of IFU bundles, with 3D-printed MLAs; 2) the characterisation of our first PIAA
optics; 3) the integration of a high contrast bench, planned for prototyping of Front-End control strategies; 4)
the characterisation of the PIAAN system on the bench.
Session 17:
Technologies for Vacuum and Cryogenic Instruments I
21 June 2024 • 08:30 - 10:00 Japan Standard Time | Room G214, North - 2F
Session Chair:
Huub Janssen, Janssen Precision Engineering B.V. (Netherlands)
13100-265
21 June 2024 • 08:30 - 08:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Presently, the field of astronomy is transitioning towards the analysis of extensive datasets and all-encompassing sky surveys, moving away from the traditional study of individual celestial bodies. The imaging terminal of large field of view sky survey telescopes is typically equipped with a splicing camera consisting of CCD/COMS detectors. In order to enhance the signal-to-noise ratio of imaging and mitigate dark current, the splicing CCD imaging surface must be enclosed within a vacuum Dewar and cooled to temperatures ranging from -80 to -100 ℃. This poses a significant challenge in facilitating the electrical signal feeding and readout of multiple detectors within a low-temperature vacuum environment. This study employs glass sintering and bonding techniques in conjunction with thermodynamic simulation analysis to achieve the transmission of more than 1600 signals through a constrained flange surface. Environmental adaptability is maintained through the thermal matching of materials, and the introduction of a stress relief groove mitigates the impact of flange surface deformation on bonding positions under vacuum conditions. Following multiple rounds of temperature loop test, i
13100-104
21 June 2024 • 08:45 - 09:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The FIRSST (Far-Infrared Spectroscopy Space Telescope) identifies the physical processes of planets formation, traces the flow of water, witnesses the galaxy growth to cosmological distances. The payload consists of a primary telescope and two instruments spanning tens to hundreds of micron wavelengths provide low to super high spectral resolving power. One instrument is cooled to 120 mK with a flight heritage ADR design. The other instrument detector, the heat sink for the ADR, and the entire telescope are cooled to 4.5 K with the Ball 4 K Cryocooler. The passive thermal system significantly reduces the cooling requirement for the 4 K Cryocooler. The multiple thermal stage architecture provides thermal immunity to the thermal environment load. FIRSST’s cryogenic thermal system meets all thermal requirements with margin. Ball’s experienced design team leverages lessons learned from past programs, included verification testing throughout all program stages, ensuring all thermal requirements are met with margin.
13100-105
21 June 2024 • 09:00 - 09:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This work highlights the design and characterization tests of different strap prototypes in order to achieve the necessary resistivity and thermal conductivity for low cryogenic temperatures. In cryogenics, working together with cryocoolers, the thermal straps are a critical thermal element, since they thermally link the instrument with the cold source. In optical elements that work at low temperatures, the thermal path, and therefore the straps, must isolate them from the vibrations of the cryocoolers. Consequently, the thermal strap stiffness is an important characteristic to consider in the design.
13100-106
21 June 2024 • 09:15 - 09:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Camera Head of the Wide Field Imager (WFI), which is to fly on the X-ray telescope NewAthena, is a compact sub-system requiring the integration of three separate temperature regions. One will be the environment temperature of the instruments support structure. The other two temperature environments are governed by the requirements of the detector front-end electronics and the sensor itself. Due to the limited space available and high heat fluxes that the system needs to remove at temperatures as low as 160 K, graphene thermal straps are used. Although already in use in some space applications, space qualified graphene thermal straps are not available on the market, therefore a qualification program, specific for the environmental conditions and requirements of the WFI system, has been carried out. The thermal straps are tested for their thermal performance, structural stability and particle shedding, thermally cycled and outgassed.
13100-107
21 June 2024 • 09:30 - 09:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This paper presents the design and technical progress of a precision X-Y stage for detector dithering and flexure compensation being developed for the Magellan InfraRed Multi-Object Spectrograph, MIRMOS. Designed to operate at 80 K, the stage will accurately control detector position in two orthogonal degrees of freedom. The piezo-driven flexure stage is very compact providing high-resolution backlash-free motion of the detector. A magneto resistive bridge provides position feedback in each degree of freedom, greatly reducing hysteresis, which is common in piezoelectric actuators. The system is designed to operate in open loop using a lookup table keyed to the Nasmyth rotator angle for flexure control. Here, the optomechanical design of the stage, electrical control system, and performance results from early prototype efforts are presented and discussed.
13100-108
21 June 2024 • 09:45 - 10:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
NASA’s Astrophysics Division (APD) funds, through multiple programs, development of cutting-edge technologies to enable its strategic missions to achieve ambitious and groundbreaking science goals. These technology development efforts are managed by the Cosmic Origins (COR), Exoplanet Exploration (ExE), and Physics of the Cosmos (PhysCOS) Programs. The 2020 Astronomy and Astrophysics Decadal Survey, “Pathways to Discovery in Astronomy and Astrophysics for the 2020s,” recommended a pan-chromatic set of missions, including three Great Observatories and three Probe-class missions that could collect unprecedented data over the coming decades. We show the correlation between these strategic missions and the current set of Astrophysics technology gaps, and recent and current technology maturation projects funded to help close these technology gaps. We also cover how these investments advanced the Technology Readiness Levels (TRLs) of the technologies, and where they have been infused into missions and projects.
Break
Coffee Break 10:00 - 10:30
Session 18:
Technologies for Vacuum and Cryogenic Instruments II
21 June 2024 • 10:30 - 12:15 Japan Standard Time | Room G214, North - 2F
Session Chair:
Gabby Aitink-Kroes, SRON Netherlands Institute for Space Research (Netherlands)
13100-109
21 June 2024 • 10:30 - 10:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The European Southern Observatory (ESO) is at present constructing the Extremely Large Telescope (ELT), a 40-m class astronomical telescope on top of the 3046 m high mountain Cerro Armazones in the central part of Chile’s Atacama Desert. In combination with its powerful facility instruments, it will be the largest optical/near-infrared telescope in the world. The instrument roadmap lists up to eight scientific instruments.
The paper outlines the cryogenic requirements defined by the ELT instrument suite and describes concept and design of the cryogenic infrastructure. A centralized and fully automated system combining open loop Liquid Nitrogen cooling in combination with low-vibration mechanical cryo-coolers is the baseline for providing the required cooling capacity and temperature levels as low as 4 Kelvin. Project status and timeline are presented.
13100-110
21 June 2024 • 10:45 - 11:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Mid-infrared ELT Imager and Spectrograph (METIS) is one of the scientific instruments for the ELT. The Common Fore Optics (CFO) is the first set of optics and mechanisms within the cryogenic instrument. A key element of the CFO is the Pupil Stabilization Mechanism (PSM), a tip/tilt mirror used for periodic adjustments of the pupil alignment during observations. The design challenges for the PSM involved achieving the required stability, resolution, and a sufficient stroke range/hold power while operating within the stringent requirements of the CFO. The design development lead to a monolithic design and integrated flexures driven by actuators with an integrated closed loop optical encoder.
13100-111
21 June 2024 • 11:00 - 11:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
This paper describes the work performed by the CEA Paris-Saclay team to build and qualify a cryogenic derotator mechanism for the ELT-METIS instrument. As the Extremely Large Telescope is an azimuthal telescope, a field derotator device is mandatory to keep the sky image perfectly aligned on the detector frame during the observations. The METIS consortium has chosen to place the derotator mechanism inside the cryogenic vessel, operating at 70 K under vacuum to reduce the background noise at the lowest level. This article gives the main results of the achieved performances, including a positioning accuracy in the arc second range.
13100-112
21 June 2024 • 11:15 - 11:30 Japan Standard Time | Room G214, North - 2F
Show Abstract +
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. The core of HARMONI is the Integral Field Spectrograph (IFS) which includes the Pre-Optics Fast Shutter (POFS), a mechanical cryogenic shutter which will be used with both the visible and infrared detectors. This mechanism has been designed to be fast and reliable and its design has already passed the Critical Design Review (CDR) but specific issues that require further analysis have been identified . This works presents the POFS design and the tests performed on a prototype to validate it and analyze possible improvements before the Final Design Review (FDR).
13100-113
21 June 2024 • 11:30 - 11:45 Japan Standard Time | Room G214, North - 2F
Show Abstract +
HARMONI is the high angular resolution optical and near-IR integral field spectrograph for the Extremely Large telescope (ELT). It covers a large spectral range from 470nm to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60mas to 4mas. The Instrument Pre-Optics (IPO), a sub-system under the responsibility of the Instituto de Astrofísica de Canarias (IAC), consists of several opto-mechanical mounts operating at cryogenic temperatures. Among these, toroidal mirrors stand out as the most sensitive and accurate elements of the IPO. An athermal design has been achieved by combining different materials for both the mount and the pads that define the position of the optical element. This design compensates the differential contractions during cooling, which allows the optical element alignment to be maintained within the tight tolerance when transitioning from warm to cryogenic operating temperatures. This paper presents the design of the athermal toroidal mirror mount, the tests carried out on its prototype and the final optomechanical mount.
13100-114
21 June 2024 • 11:45 - 12:00 Japan Standard Time | Room G214, North - 2F
Show Abstract +
MICADO is a first-generation instruments for the ELT, which will provide diffraction limited imaging in standard, astrometric, and coronagraphic modes, and long-slit spectroscopy at near-IR wavelengths. The core of the MICADO instrument is its cryostat. Following a light ray entering the cryostat through the entrance window, the first mechanism it encounters is the Focal Plane Mechanism (FPM). It consist of two independent movable devices mounted together in one assembly: the aperture wheel (AW) and the focal plane wheel (FPW). The FPW holds field stops, calibration masks, slits and coronagraphs, which require better than 15 µm RMS repeatability of the mechanism. To fulfill this specifications and avoid mechanical wear in the drive a novel magnetically coupled gear system was developed at our institute. This contribution will describe the design and performance of the magnetic drive as well as the first results of the FPW prototype tests.
13100-115
21 June 2024 • 12:00 - 12:15 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Detector Positioning System (DPS) is a cryogenic mechanism operating at 82 K installed in the cryostat of the Multi-AO Imaging Camera for Deep Observations (MICADO) at the Extremely Large Telescope (ELT).
The DPS mechanism will be exclusively utilized during the alignment and test phase. On the successful completion of the test phase, it will be mechanically locked at a best pre-determined focus so that it cannot be moved anymore during the observation period.
The DPS has been conceptualized as a fixed and reproducible interface to the Main Bench Structure in the cryostat and as an adjustable unit containing the Detector Array mounted on the DPS frame, which is installed on a linear guide mounted on the base plate. The linear guide is further actuated by a cryogenic motor during the alignment phase to bring the focal plane array into focus.
Break
Lunch Break 12:15 - 13:20
Session 19:
Novel and Disruptive Concepts
21 June 2024 • 13:20 - 14:50 Japan Standard Time | Room G214, North - 2F
Session Chair:
Ramón Navarro, NOVA (Netherlands)
13100-116
21 June 2024 • 13:20 - 13:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Astronomy and Space Domain Awareness are limited by the size of available
telescope optics, the cost for which scales exponentially due to the exquisitely ground and polished glass primary mirrors. Liquid mirrors (LMs) may break this cost scaling. When rotated at a constant angular velocity, fluid surfaces take the form of a paraboloid. However, LMs cannot slew or tilt off-Zenith without spilling. To address these limitations and enable low-cost, very-large-aperture telescopes, DARPA launched the Zenith program. Zenith will develop modeling tools, materials, surface and field controls, and structures to demonstrate a meter-scale LM telescope without the need for rotation.
13100-117
21 June 2024 • 13:35 - 13:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
We present experiments performed in parabolic flights and in space, demonstrating the use of Fluidic Shaping to create optical components in microgravity. By injecting optical liquid into a circular bounding frame in microgravity, surface tension drives the liquid to a minimum energy form of a spherical lens with sub-nanometric surface roughness. We will discuss the engineering challenges encountered in such experiments, and provide details and insights towards the future implementation of similar experiments in microgravity.
We view this set of experiments as the first milestones in expanding in-space manufacturing capabilities to also include optical components. Due to its simplicity, low power consumption and essentially zero waste, Fluidic Shaping can serve as a fabrication infrastructure for future long-duration space missions that must be self-sufficient. Due to its scale invariance, the method could potentially be used for the creation of large space telescopes, thus overcoming launch constraints.
13100-118
21 June 2024 • 13:50 - 14:05 Japan Standard Time | Room G214, North - 2F
Show Abstract +
As a collaborative effort within the Thirty Meter Telescope (TMT) project, India is committed to supplying 84 polished segments for the primary mirror, employing the innovative Stressed Mirror Polishing (SMP) technology obtained from Coherent Inc., USA. SMP allows for the efficient polishing of highly aspheric non-axisymmetrical glass blanks at an accelerated rate. India-TMT (I-TMT) successfully applied SMP to qualify three glass roundels at Coherent's facility in Richmond, CA. The study focuses on a comparative analysis of Buyoff Stations (BOS) used in the SMP process. It contrasts results from the 43-point hydraulic-based BOS at Coherent with simulated outcomes from the 27-point whiffletree-based BOS at I-TMT. This analysis assesses efficacy and performance differences between the two BOS configurations, involving a comprehensive examination of a 1520mm diameter polished glass roundel. The study integrates Finite Element Method (FEM) simulations with experimental data, providing insights into the efficiency of the respective BOS setups.
13100-119
CANCELED: An Emerging and Disruptive Technology towards ultra-light, fire-polished & self-correcting, Live Mirror
21 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
The Horizon European Innovation Council’s funded Live Mirror consortium is developing a pathfinder disruptive technology towards a new lightweight, hybrid and self-correcting mirror. Such a new mirror development is based on (1) the state processes to deterministically slump very accurately fire-polished sheet glass and (2) a dynamical hybrid structure via 3D printed electroactive polymers or ceramics actuators to mirror self-support and correct the deformation of the optics as it responds to changes due the glass thermal deformations and the gravity and/or wind loads. These breakthrough developments will lead to cost-effective and lightweight integrated optoelectronic systems and demonstrate the potential for new remote sensing capabilities from the ground and space. We will present the status and what is next for the Live Mirror technology.
13100-312
21 June 2024 • 14:05 - 14:20 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Image slicers are key components in many astronomical instruments, notably in the VLT-MUSE instrument. However, the precision manufacturing of image slicers is costly and time-consuming. One technology that could transform the manufacturing of fused silica image slicers is ultrafast laser-assisted etching (ULAE), as it enables micron-level precision shaping of fused silica over multi-mm scales. In this paper, we demonstrate the fabrication of a 10 x 1 mm fused silica surface with ~700 nm (peak-to-valley) surface form error and ~70 nm (rms) roughness. If combined with post-processing polishing techniques, such as CO2 laser polishing, ULAE could yield high-performance freeform fused silica image slicers for diverse applications, including astronomy.
13100-120
21 June 2024 • 14:20 - 14:35 Japan Standard Time | Room G214, North - 2F
Show Abstract +
A novel route of achieving a continuous broadband ultraviolet to blue-green astrocomb is reported, based on nonlinear mixing between broadband infrared ultrashort laser pulses in a MgO:PPLN waveguide. The generated 1-GHz comb, spanning 390–520 nm, was filtered to a 30 GHz sub-comb using a low-dispersion Fabry-Perot etalon. Limited only by the bandwidth of the coatings of the filter cavity, the resulting astrocomb from 392–472 nm was then visualised on a lab-built cross-dispersion echelle-prism spectrograph, demonstrating well resolved comb lines across 24 diffraction orders.
13100-121
21 June 2024 • 14:35 - 14:50 Japan Standard Time | Room G214, North - 2F
Show Abstract +
Modern spectro-polarimeters in solar astronomy usually require splitting different wavebands into separate monochromatic arms that operate as independent sub-instruments. We present a concept of polarimeter that operates at two wavebands simultaneously through a common optical system and detector. By using chromatic zero-order waveplates, polarized light propagates differently through the instrument for the two wavebands, allowing to measure both polarizations simultaneously. We present Stokes vectors measurements with ~1% accuracy using a proof-of-concept instrument built with standard off-the-shelf components, thus demonstrating the relevance of this concept for fields like solar astronomy and space instrumentation.
Award Ceremony
21 June 2024 • 14:50 - 15:05 Japan Standard Time | Room G214, North - 2F
Session Chair:
Ramón Navarro, NOVA (Netherlands)
This session will include the presentation of conference awards.
Session PS1:
Posters - Fabrication of Mirrors, Lenses and other Optical Components
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Wednesday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-122
On demand | Presented live 19 June 2024
Show Abstract +
This study presents a proposed method of shaping, grinding and polishing of thin shell mirrors for adaptive optics in the context of the development of an adaptive secondary mirror (ASM) for the UH 2.2 meter and NASA IRTF telescopes. The ASM shells are slumped, with a thickness of ~3mm, and a diameter of 620 and 243 mm respectively, and then ground/polished. A set of fast actuators is then mounted on the backside of the mirror to correct the wavefront errors caused by atmospheric turbulence.
We will discuss the metrology, grinding and polishing methods to achieve a surface form error of ~40nm RMS, and roughness RMS of ~1nm.
The ease of warping and unwanted deformation of the thin shells, highlight the difficulty but also the novelty of the used methods. Such relatively easily manufacturable mirrors can unlock adaptive technologies for more and potentially larger telescopes.
13100-123
On demand | Presented live 19 June 2024
Show Abstract +
Additive manufacturing (AM; 3D printing) has clear benefits in the production of lightweight mirrors for astronomy: it can create optimised lightweight structures and combine multiple components into one. New capabilities in AM ceramics, silicon carbide infiltrated with silicon and fused silica, offer the possibility to combine the design benefits of AM with a material suitable for visible, ultraviolet and X-ray applications. This paper will introduce the printing methods and post-processing steps to convert AM ceramic samples into reflective mirrors. Surface roughness measurements after abrasive polishing of the AM ceramics will be presented.
Show Abstract +
WindCube is a NASA HFORT funded mission to study the coupling of thermospheric winds with the earth’s ionosphere. The optical system is based on a limb sensing Fabry-Perot etalon designed to measure the doppler shift of the 630 nm Oxygen airglow emission. The instrument payload is designed to fit within a 6U volume in a 12U cubesat. The accuracy requirement for the wind speed retrieval is 5 m/s. This is the driving requirement for the opto-mechanical stability of the etalon system. Active temperature control of the etalon is employed to keep the mounted etalon within a +/- 0.1 C range. This paper discusses the design and analysis of the mounted etalon system to meet the accuracy requirement as well as surviving the rigors of vibration testing and the launch environment.
13100-126
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The standard configuration for Small-Size (4 m diameter class) Imaging Atmospheric Cherenkov Telescopes (IACTs) is the ASTRI-like dual-mirror telescope adopted for both ASTRI Mini-Array and CTA SST subarray. It provides a wide field of view and a flat optical response. The innovative aplanatic design reduced the plate scale, making it an ideal choice for compact cameras. The introduction of telescopes with secondary mirrors in IACTs marked a significant milestone. However, the challenge of producing large secondary mirrors had to be overcome to bring this optical design to fruition. The ASTRI-secondary (aspherical) mirrors are characterized by a diameter of 1.8 meters, and a hot-slumping replication process was adopted to produce the sizeable monolithic glass substrates. In the context of developing the ASTRI Mini-Array, our Institute (INAF) established a new procurement chain with external companies. This paper presents the manufacturing and characterization results of the prototypal mirrors.
13100-127
CANCELED: Heat Rejecter preliminary design of the European Solar Telescope
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The European Solar Telescope (EST) is a 4.2-m solar telescope, currently in the preliminary design phase. The Heat Rejecter is a mirror with a central hole that lies at the prime focus of the telescope (F1) and operates as a first field stop of the optical system. The Heat Rejecter aims to reject the solar radiation outside the selected field of view to avoid extra thermal load in the following optical elements and the seeing degradation, avoiding the development of thermal plumes in the optical path. This paper shows the status of the Heat Rejecter preliminary design.
13100-128
On demand | Presented live 19 June 2024
Show Abstract +
Developed largely for LSST follow-up, the SOAR Adaptive Module Optical Spectrograph (SAMOS) is a multi-object spectrograph that utilizes a Digital Micromirror Device (DMD) as a programmable slit mask for ground layer adaptive optics (GLAO) corrected observations. The SAMOS optical system is highly folded and very compact, using a grism exchange mechanism to switch between dispersion modes and resolving powers. To conserve space SAMOS uses round grisms, 70 mm in diameter. With no straight references edges on either the prisms or the VPH grating, the grism alignment and bonding proved to be challenging. This paper presents the method used to align and bond the SAMOS grisms. This method utilizes an elegant optical alignment technique to precisely align the VPH grating fringes to the prism facets during the bonding process, with minimal adhesive cleanup, zero bubbles in the clear aperture, and in the end producing exceptionally well-aligned spectra at the detector.
13100-129
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
We fabricated three freeform mirrors for the KASI-Deep Rolling Imaging Fast Telescope, which is a confocal off-axis freeform three-mirror system with a 300 mm entrance pupil diameter. We applied lightweight design and analysis to minimize weight while preserving the performance of the system. As a result, the weight of the primary and tertiary mirrors was reduced by 72.4% and 74.2%, respectively. Additionally, the wavefront analysis yielded RMS surface error less than 20 nm. The surfaces of these off-axis freeform mirrors were formed by a series of production process, including grinding, polishing, forming, and finishing. Measuring surface profile has been performed by using Coordinate Measuring Machines (CMMs) for the grinding process and an interferometer with Computer Generated Holograms (CGHs) for polishing, forming, and finishing process. The test results for all three mirrors were well within the required value of 20 nm RMS and 100 nm PV.
13100-130
On demand | Presented live 19 June 2024
Show Abstract +
ARIEL is ESA's fourth medium-class mission in the Cosmic Vision program, is scheduled for launch in 2029. The telescope aims to conduct an expansive, unbiased spectroscopic survey, unraveling the complexities of exoplanet atmospheres and interiors to better comprehend the key factors influencing planetary system formation and evolution. The baseline payload features an off-axis Cassegrain telescope (M1-M2), a collimating off-axis parabola (M3), and a plane folding mirror (M4) channeling the collimated beam into two instrument modules. ARIEL's capabilities span primary and secondary transit spectroscopy (1.10 to 7.80 μm), broad-band photometry in the Optical (0.50 - 0.80 μm) and Near IR (0.80 - 1.10 μm) ranges, and a Fine Guidance System. This work will focus on M1, an aluminum mirror with an unobscured elliptical shape of size 1100 x 730 mm. The Surface Error (SFE) budget for M1 covers low and mid spatial frequencies (MSF). The work describes the manufacturing process of the mirror, the method used for quantify surface roughness, the characterization of MSF errors, and the study of the degradation of the system performance due to MSF errors.
13100-132
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
This study explores the use of adjustable X-ray mirror technologies, specifically employing electroactive polymer films as actuators to correct figure deformations in thin X-ray mirror shells. These deformations can arise during the preparation, thermal stress, or mounting of the optical assembly, impacting the mirror's effective areas and angular resolution. Our research focuses on the fabrication, testing, and potential applications of micrometer-scale electroactive polymer (PVDF-TrFE) films sandwiched between electrodes on flat silicon wafers. We present a low-cost, low-temperature, and scalable technology for actuator fabrication, with a particular emphasis on its adaptability to curved mirror substrates.
13100-133
On demand | Presented live 19 June 2024
Show Abstract +
The NMF non-contact measurement machine range for freeform optics by Dutch United Instruments (DUI) can be employed for measurements during the entire production process. It can measure ground, polished and coated surfaces. It has the versatility to measure all sorts of dimensions and surface shapes (flat, convex, concave, asphere to freeform with up to +/-2.5 mm departure from the best-fit asphere), the accuracy to measure with nanometer level accuracy and the speed to gather the required high data density to characterize mid-spatial content. The latest platform can measure up to 1000 mm diameter and combines optical and tactile measurement capabilities.
Show Abstract +
The study explores the intricacies of crafting resilient broadband telescope mirrors, utilizing silver (Ag) and aluminum (Al). Ag-mirrors, renowned for exceptional reflectivity, demand protection from corrosion, necessitating coatings like aluminum oxide (AlOx). Similarly, Al-mirrors, effective in the far UV spectral range, require safeguarding due to Al's susceptibility to oxidation, employing coatings such as aluminum fluoride (AlFx). These scenarios emphasize the critical role played by the metal-dielectric interface (i.e., Ag/AlOx and Ag/AlFx) in achieving durable and high-performance mirrors. We currently use physical vapor deposition (PVD) and thermal atomic layer deposition (ALD) separately to fabricate these mirrors, leading to interface deterioration. The study proposes a solution using sputtering atomic layer augmented deposition (SALAD), seamlessly integrating PVD and ALD without breaking the vacuum. The study addresses multi-physics modeling, SALAD sample preparation, environmental testing, advanced characterization, and degradation mechanism assessment. By optimizing the metal-dielectric interface, aiming to enhance endurance and spectral responses of these mirrors.
13100-135
On demand | Presented live 19 June 2024
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This study aims to enhance protective coatings for silver-based astronomical telescope mirrors (Ag-mirrors). Despite their excellent reflectivity, Ag-mirrors have limited durability, necessitating optically transparent coatings. The proposed solution is diamond-like carbon (DLC) known for hydrophobicity and damage resistance. Using filtered cathodic arc (FCA) deposition, the study achieves high sp3 to sp2 bond ratios in DLC at room temperature. High-temperature high-humidity (HTHH) testing demonstrates DLC's superior resistance to hydrolyzation compared to usual aluminum oxide (AlOx) coatings. While AlOx outperforms DLC in spectral reflectance, adjusting DLC thickness compensates, making it competitive. DLC shows better resistance to corrosion and abrasion than AlOx. Substrate biasing at ~-80V improves abrasion resistance, deposition rate, and sp3 to sp2 ratio. DLC coatings exhibit uniform surfaces, minimizing scattering effects from roughness. In conclusion, FCA-deposited DLC emerges as a promising protective coating for Ag-mirrors, providing optical transparency, durability, and resistance to damage and degradation, surpassing traditional coatings like AlOx in specific aspects.
13100-136
On demand | Presented live 19 June 2024
Show Abstract +
Coronagraphs are instruments that are designed to block on-axis light from a bright source to improve imaging of a nearby dim target. This technology is key to the detection and characterization of Earth-like exoplanets which requires 10^-8 to 10^-10 contrast for detection. Errors in fabricating complex coronagraph masks are one of the limiting factors in achieving the fundamental limit of high-contrast observations. To address this issue Starfire Optical Range (SOR) of the Air Force Research Laboratory (AFRL) is collaborating with the AFRL Materials and Manufacturing Directorate (RX) to fabricate custom coronagraph masks. We present the results of a fabrication effort of Lyot coronagraph masks with high performance anti-reflection (AR), reflective, and absorption coatings for use in the Advanced Testbed for Laser beacon Adaptive optics and Next-generation Turbulent Imaging Science (ATLANTIS) testbed at SOR. In this poster we include a section on our concepts for a next phase of coronagraph mask fabrication that involves the use of complex materials such as liquid crystals or meta-surfaces to improve contrast and decrease the coronagraph inner working angle.
13100-137
On demand | Presented live 19 June 2024
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Novel MLA geometries and design methods are introduced, enabling 'second-generation' and 'third-generation' products. They offer higher flexibility in lens segment design and expand the range of possible applications and associated performance. The second-generation MLA features lens segments with different freeform surface shapes, and irregular arrangement intervals between segments. This product enables simultaneous measurements of multiple depth points while controlling image intensities. The third-generation MLA is created using a topology optimization method based on internal stresses, allowing the unsupervised design of optical segments. The designed freeform segments can be used to convert a Gaussian beam into multiple and flexible distributions of light beams.
Show Abstract +
Hexagonal cutting of pre-polished circular segments is one of the critical process step in the manufacturing of ELT-M1 mirrors. This enables edge-to-edge optical performance, and precise mechanical references used to align the segment during operation of the segmented primary mirror. This paper presents the novel technology developed by Safran REOSC to guarantee fast and precise referencing of all critical features, hexagonal shaping, edge sensor interface machining, cutouts handling, and throughput over one segment per day. We will analyse the machining performance over 100 mirrors, and the effect of cutting on optical surface.
13100-139
On demand | Presented live 19 June 2024
Show Abstract +
Flat, Lightweight optics have the potential to significantly reduce the cost of space-based observing by reducing launch costs and vehicle sizes. We have designed, manufactured, and tested a metamaterial flat lens which operates at 480GHz. The lens is constructed from polyimide (generic Kapton) and aluminum. It has an aperture size of 124mm and an f-number of f/1.2. It weighs approximately three grams and is 110 microns thick. We have measured the optical performance the lens and found it to have good performance, but slightly worse loss than expected.
13100-140
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Additive manufacturing (AM) allows for the use of complex geometries and consolidation of parts, which has expansive applications to space-based optics. By using internal latticing to reduce mass, satellites can be less expensive to launch. However, issues of print-through and internal stresses, caused by the machining processes, can distort the reflective surface, impacting the optical performance at shorter wavelengths (visible and ultraviolet). This paper will explore these issues through the re-design of a mirror for a CubeSat, concluded by a metrology evaluation.
13100-141
On demand | Presented live 19 June 2024
Show Abstract +
Additive manufacturing (AM) in aluminium using laser powder bed fusion provides a new design space for lightweight mirror production. However, internal porosity, a common AM defect, results increased scattered light from the reflective surface of the AM mirror. One strategy to reduce porosity is to apply a hot isostatic press (HIP) to the part after printing. This paper presents the results of balancing the ability of HIP to reduce porosity in aluminium samples with its ability to promote grain growth, which has a negative impact when generating the reflective surface. The impact of HIP is assessed using x-ray computed tomography, micro-roughness measurements, mechanical testing, and electro backscatter diffraction.
13100-143
On demand | Presented live 19 June 2024
Show Abstract +
Ion Beam Figuring is a key technology after polishing, hexagonal cutting and integration to obtain ELT-M1 hexagonal segments without edge effects. This process used at REOSC over 30 years offer an efficient solution for finishing these large freeform optical components.
This paper presents a dedicated figuring process strategy to maximize throughput and process convergence as well as to limit temperature increase during processing. We analysed the results of optical surface improvement over 100 ELT-M1 segments. These results highlight the high accuracy of IBF technology to correct hexagonal surfaces all the way to the edge. The final surface figure error was obtained while keeping low surface roughness. This is obtained after less than two figuring iterations leading to a throughput over one segment per day.
13100-144
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Increasingly popular Additive Manufacturing (AM) techniques have been shown to improve traditional manufacturing practices by reducing overhead costs without sacrificing instrument size or design complexity. AM has seen success in some areas of astronomical instrumentation research, including the production of micro-lens arrays from high purity fused silica glass. This poster characterizes three thermoplastics commonly used in AM for the construction of a 5x5 micro-lens array.
13100-145
On demand | Presented live 19 June 2024
Show Abstract +
Fiber optic based multi-object spectrographs have been used for astronomical surveys since the 1980’s. Recent instruments can observe higher target counts on larger aperture telescopes. Studies are in progress for more massively multiplexed spectrographs on these telescopes where the size spectrograph designs become difficult and risky.
We present a fabrication study based upon a prototyped pre-spectrograph wavelength splitter and pupil slicer (WSPS). WSPS is an assembly interfaced to a subset of the incoming fiber optics, splitting light into multiple wavelength channels, and allowing use of an arrayed output to slice up the pupil. Excellent light coupling of incoming light is needed to the output channels. Hundreds of high precision units are required. Mass production and simplified alignment techniques are desired to minimize the resources required for assembly. This evaluation includes consideration of materials, fabrication techniques and machine learning applications.
13100-146
On demand | Presented live 19 June 2024
Show Abstract +
Space telescopes are required to be lightweight and small without compromising high optical performance. A Metallic mirror is one of the technologies that could achieve space requirements mission. Flexible mounting pads are a very critical part of the mirror that mounts the mirror to the structure. This study will optimize the shape of the flexible pads using Finite Element Analysis to understand its effects on mechanical and optical performance by defining the geometric dimension of the design as an input variable parameter to a perform parametric study by varying those input variable parameters. The parametric study could be analyzed with the sensitivity study, response surface and optimization. The results highlight the parameters that have the biggest impact on performance and describe the relation between the parameters affect mechanical and optical performance that improve the understanding of the opto-mechanical design of metallic mirror which will be optimize to the most optimal design.
13100-147
On demand | Presented live 19 June 2024
Show Abstract +
The monolithic telescope is a complete, small telescope, containing refractive- and reflective surfaces, baffles and more, all brought together in just one single piece of glass. Such devices have potentially a wide range of applications, especially because of their unique compactness and robustness. However, due to the tight optical and mechanical tolerances, it has been notoriously difficult to produce such monolithic telescopes. First successful prototypes have been made and published in the 1990s, but it never really took off as a scientific or commercial product. We would like to present some new, innovative designs for monolithic telescopes, with improved manufacturability, which makes this tiny telescope more interesting for high volume production.
13100-148
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The optical design of the GMTIFS integral field unit includes several mirror arrays that are proposed to be diamond machined, including the pupil and field mirror arrays as well as the image slicer. The fabrication process of diamond machined surfaces often leaves behind tool marks at mid-spatial frequencies which can have significant impact on optical performance that is not fully accounted for by errors in high-spatial frequency (surface roughness) or low-spatial frequency (form error). The structure and form of these mid-spatial frequencies is dependent on the specific machining and polishing techniques used in the fabrication of the optical elements. In this study, we model and implement representative surfaces in ray tracing software to characterise the effects of mid-spatial frequency errors on the mirror arrays in the GMTIFS spectrograph
13100-149
On demand | Presented live 19 June 2024
Show Abstract +
Polishing of large telescope mirrors made from low thermal expansion ceramics such as ZerodurTM is ubiquitous to achieve high resolution imaging and long service life. Contact polishing with elastic abrasive tools (Shape Adaptive Grinding, SAG) can achieve sub-nanometric surface finish and tens of nanometers form error on such mirror segments, but is always limited by relatively low removal rate. A variant of the process called SAG+ is introduced here to polish ZerodurTM and silicon, in which cerium is used as a slurry to increase the material removal rate through chemo-mechanical effect. The new process reduces polishing time on ZerodurTM by ~ 50% and surface roughness on silicon by ~ 40-60%. The technology has much potential in reducing the manufacturing cycle time and overall energy footprint of large telescope primary mirrors made of hundreds of segments, where the overall mirror size can reach up-to 30-40 meters.
Show Abstract +
Current ELTs use comparatively thick segmented mirrors with a support structure / warping structure of significant mass. In this publication we present a method to develop Segmented Thin Shell Mirrors that shall be supported by multiple actuators mounted on a backing structure. This enables active and or adaptive segmented mirrors for a variety of applications. Starting with a Adaptive Secondary Mirror The pre and post surface form error was measured and compared. The difference between the two is17.7 µm peak-to-valley and 3.7 µm rms. The error is gradual and can easily be compensated by pre-loading the actuators that support and deform the mirror.
Session PS2:
Posters - Materials and Metamaterials
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Wednesday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-150
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
In large sized mirrors used for space and astronomical applications and mirrors used in low-temperature environments, not only coefficient of thermal expansion (CTE) but also the homogeneity of CTE within the material is important in thermal property because it is unfavorable deformation of the mirror shape due to changes in environmental temperature. we investigated the inhomogeneity of the CTE of low-expansion ceramic named Fine Cordierite that has been attracting attention as a new material. A Fine Cordierite mirror is fabricated, and CTE is measured to estimate the spatial inhomogeneity by using a laser thermal dilatometer.
13100-151
On demand | Presented live 19 June 2024
Show Abstract +
The control of temperature dependence of thermal expansion of cordierite ceramics was investigated for application to optical components onboard spacecraft. Conventional cordierite ceramics exhibit zero expansion at room temperature, but not at other temperatures. This limits the application of cordierite as a low thermal expansion material.
We have developed a cordierite material that exhibits zero expansion at the operating temperature.
13100-152
On demand | Presented live 19 June 2024
Show Abstract +
MezzoCielo (or “half of the sky”), novel concept of extremely large field-of-view monocentric optical devices designed
to continuously patrol the whole sky, is an optical sphere which requires the filling of its inner volume with
special fluid in order to be actually convergent with reasonable focal ratio (for spherical aberration reduction).
This fluid has to be characterized by two main properties, namely low refractive index and extremely high transparency in the visible range, but, of course, many other characteristics, such as thermal and chemical stability
over time, no toxicity or flammability, compatibility with glass and metals, are also desirable. By virtue of these
considerations, two fluorine liquids have been selected: the fluids commercially known as FC-72, perfluorohexane
with nd = 1.251 at T = 25°C, and Novec7200, ethoxy-nonafluorobutane with nd = 1.282 at T = 25°C. In this
work, the experimental evaluation of their optical properties (refractive index and transparency) in the visible
range and in the thermal interval [-10,+25]°C has been carried out in order to verify the data supplied by the
manufacturer and to fully characterize their optical behaviour.
13100-154
On demand | Presented live 19 June 2024
Show Abstract +
The degradation of large rotating cryogenic structures such as the Central Wheel Mechanism for MICADO, particularly in terms of wear and friction, has not been fully understood. This work aims to address this gap by developing computational and experimental tools to tackle these issues. By developing a numerical model and subsequently validating it with an experimental cryogenic setup, we aim to quantify the wear and the evolution of friction in some of the MICADO cryogenic rotating components.
13100-288
On demand | Presented live 19 June 2024
Show Abstract +
Ion beam polishing processing technology is a processing method developed in recent decades using high-energy ion beams, which is suitable to removal and processing different materials, because its working process has incomparable advantages compared to other processing methods. Process studies involving multiple materials in the same area have not been reported. In this paper, the influence of Ion beam polishing processing technology parameters on the removal rate of different materials in a small area is studied experimentally, and the removal rate of high-purity silica glass, doped silica glass and epoxy resin adhesive layer is tested by single factor and orthogonal test method, and the corresponding removal rate prediction formula is established through analysis. Experiments show that within a certain range of process parameters, gate voltage, gate current and gate size have obvious effects on the removal rate, while working distance and step size have the lowest impact. Prediction formulas and experiments are used to derive optimal process parameters for simultaneous removal of different materials.
Session PS3:
Posters - Calibration, Test and Metrology
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Wednesday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-155
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
We report on the design and status of the slicing unit of SCALES (Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy), which sits behind the lenslet array and produces a pseudoslit suitable for higher dispersion than is achievable with a lenslet alone. Our ‘slenslit’ (SLiced LENlet pseudoSLIT) is being built in collaboration with University of Durham’s Precision Optics group. SCALES’ diffraction-limited integral field spectrograph operates from 1 to 5 microns behind the W.M. Keck Observatory’s AO system, and coronagraphic masks unlock the high contrast needed to observe and characterize exoplanets. The SCALES slenslit opens up new parameter space heretofore untapped by rearranging a small patch of lenslets into a pseudoslit before being dispersed at moderate spectral resolution (R~2500 - 7500) over the SCALES bandpass while preserving the spatial resolution offered by the Keck AO system.
13100-157
On demand | Presented live 19 June 2024
Show Abstract +
SOLAR-C is a solar mission for extreme ultraviolet spectroscopic observations. The Ultra Fine Sun Sensor (UFSS) will make a vital contribution to achieving a high pointing accuracy of the mission. One of the requirements on accuracy of the UFSS is a “linearity error” ---bias error after characterization--- of less than 2 arcseconds (peak-to-peak) over the UFSS’s field of view (FOV) of 1.0×1.0 degrees. In this study, we developed a measurement system with a laser interferometer in the current test facility consisting of a solar simulator light source and a two-axis gimbal stage, allowing us to calibrate the measurements and characterize the UFSS with accuracy better than 1 arcsecond. We evaluated how well we could determine the gimbal's pointing and its stability with respect to the solar light beam from the solar simulator. We concluded that by using the developed testing system and the procedures, we can measure the UFSS with sufficient accuracy.
13100-158
On demand | Presented live 19 June 2024
Show Abstract +
Attitude verification is required for ground-based, balloon-borne, and space-based observatories. A system typically responsible for this verification comprises one or more optical star cameras. This poster presents the design, software, and performance of a star camera developed for the Simons Observatory (SO) Large Aperture Telescope (LAT). The star camera is robustly compatible with experiments that have pointing specifications >=10”. The system comprises a 2.35 megapixel CCD coupled to a Canon EF 200mm f/2.8L lens, providing a 3.3◦×2.1◦ field of view. The star camera images the sky and employs simple blob-finding techniques to provide a list of positions and brightnesses to the Astrometry.net solving library, producing the best-match RA and Dec of the image. For camera integrations of ~100msec, total processing times of <400msec are typical, nearly an order of magnitude improvement over the systems used with predecessor experiments. After elevation and azimuth solutions are found, they are used to generate a pointing solution for the SO LAT. The system typically reports solutions with <5” pointing accuracy, is easily modified, and comprises commercial hardware.
13100-159
On demand | Presented live 19 June 2024
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The laboratory measurement and evaluation of the performance of an apo-achromatic collimator is presented in this work. This customized collimator was optimized to utilize with a high-resolution spectrograph located at Thai National Telescope (TNT). The Center for Optics and Photonics (COP) under the National Astronomical Research Institute of Thailand (NARIT) aims to evaluate and control the performance of the achromatic triplet collimator with a Fizeau interferometer to ensure that the correspondence with optical and opto-mechanical tolerances. The parameters controlled include the Root-Mean-Square (RMS) and Peak-To-Valley (PTV) wavefront errors and the Modulation Transfer Function (MTF). The result suggests the performance of the assembled achromatic triplet lens conforms with Zemax optical design below 0.1 NA. The RMS and PTV wavefront errors and MTF measured with the interferometer appear comparable to the Zemax optical design of the collimator within this range. Therefore, we conclude that our in-house manufacturing, assembly, and control are acceptable for astronomy applications.
13100-160
On demand | Presented live 19 June 2024
Show Abstract +
We are in the process of developing the KASI Deep Rolling Imaging Fast Telescope Generation 1 (K-DRIFT G1) based on the on-site performance assessment of the K-DRIFT pathfinder. This telescope is a confocal off-axis freeform three-mirror system designed for the detection of extremely low surface brightness structures in the sky. The optical specifications of the K-DRIFT G1 are as follows: the entrance pupil diameter is 300 mm, the focal ratio is 3.5, and the field of view is 4.43° × 4.43°. During the integration stage, we measured the position of those mirrors, flexures, and bezels by using a coordinate measuring machine. Following the system integration, we will measure wavefront errors at several edge fields using an interferometer at 633 nm. We will get alignment solutions through the measured wavefront errors. In this paper, we briefly present the current status of integrating the K-DRIFT G1 and the future plans for the project.
13100-162
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
We have developed a new non-contact profiler which can measure aspherical mirrors including freeform surfaces. One of the best feature of this instrument is its very wide dynamic range of 10 nm to 100 μm, while maintaining interferometer-level measurement precision. It utilizes Computer-Generated Holograms (CGH) for generating the arbitrary wavefront. The wide dynamic range is achieved by integrating two modes, “Interferometer Mode" and "Hartmann Mode," which can be switched by changing the internal optical path without the need to move the measurement target. The measurement accuracy is 5.3 nm RMS in Interferometer Mode and 0.055 µm RMS in Hartmann Mode. The Interferometer Mode provides a measurement range from 0.0053 µm to 31 μm, while the Hartmann Mode extends from 0.055 to 625 µm when measuring the test surface of F-number 1.0.
13100-163
On demand | Presented live 19 June 2024
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The dimensional acceptance reports of the DDRAGO instrument structure for Colibri 1.3 mteter telescope of the Observatorio Astronómico Nacional in San Pedro Martir, Baja California, Mexico, are shown. And a series of guidelines for the manufacture, assembly, integration and validation for mechanical structures in astronomical instrumentation are proposed.
13100-164
On demand | Presented live 19 June 2024
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The SONG telescope, part of the global SONG program of 1-meter telescopes, is located at the Cold Lake Observatory in Qinghai, China, and is designed to serve two major scientific goals in stellar physics research: detection of exoplanets by micro-gravitational lensing methods based on the Lucky Imaging Technique (LIT), and study of the internal structure of stars by means of astro-seismic methods based on apparent velocities. Telescopes are often required to use pointing models to correct for these errors, taking into account various factors such as telescope mechanics, drive systems, atmospheric effects, sensors, and feedback. However, residual pointing errors can still occur due to factors that are difficult to model accurately. Here, we present a machine learning-based proof-of-concept for reducing pointing errors at the SONG telescope at Cold Lake Observatory. Using recent historical pointing data, the machine learning algorithm XGBoost is applied to train the model, which can effectively help to improve the precision of telescope pointing, thus improving the quality of observational data and the accuracy of scientific research.
13100-165
On demand | Presented live 19 June 2024
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The high-precision calibration technique of stereo photography systems plays a crucial role in determining the
three-dimensional position of LAMOST fibers. This paper proposes an improved calibration method for stereo
photography systems. Firstly, building upon four sets of purely translational vertical movements, precise camera
intrinsic parameters can be obtained by compensating for verticality errors. Secondly, a principal point estimation
model with varying focal lengths effectively reduces the strong coupling of camera intrinsic parameters. Finally,
a precise global optimization method based on the coplanarity of chessboard grid corner points is proposed.
Experimental results demonstrate that the single-target calibration reprojection error of this method can be
reduced to as low as 0.0697 pixels, with a stereo distance measurement accuracy of up to 99.9806%.
13100-166
On demand | Presented live 19 June 2024
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LAMOST closed-loop fiber position system have been established based on the fiducial fibers. The more accurate the benchmark position of the fiducial fibers, the higher the accuracy of the closed-loop fiber position system. We have measured the position of the fiducial fibers for two years. Two laser trackers installed at different sites were used to simultaneously measure the position of the fiducial fibers, and the measurement result were compensated for errors and fused, ultimately obtaining the benchmark position. Compared the benchmark position with the theoretical hole position, the result showed that the average measurement accuracy of the fiducial fibers was within 200 µm. The stability difference between the benchmark position obtained in the two years was around 100 µm. After applying the benchmark position to the closed-loop fiber position system, the residual value of fiber position error is 16.57 µm, and the position accuracy of 97.45% fibers is within 40 µm.
13100-167
On demand | Presented live 19 June 2024
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The intensity spectra recovered from the spectroscopic photographic plates were compared with the CCD spectra, and we found the difference between the two was only a few percent.
The measurements were taken using a commercial flatbed scanner instead of a microdensitometer.
The results indicate that the following two statements are inaccurate:
(1) Correct measurement of spectroscopic plates requires a microdensitometer and a commercial flatbed scanner is insufficient;
(2) The accuracy of the spectrum obtained from spectroscopic plates is approximately 10%.
These results will encourage the creation and publication of a digital archive of spectroscopic plates.
This paper presents the evaluated results of the optical resolution of the flatbed scanner, the measurement of spectroscopic plates, the method of recovering intensity spectra from photographic density data, and the results of comparison with CCD spectra, and discusses the causes of the high accuracy spectra obtained with the flatbed scanner.
13100-168
On demand | Presented live 19 June 2024
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The paper discusses the development of a versatile characterization setup at the INAF-Osservatorio Astronomico di Brera for measuring the diffraction efficiency of dispersing elements (DEs), which are crucial in modern optical spectrographs for astronomy. The setup accommodates DEs such as ruled gratings, volume phase holographic gratings (VPHGs) and lithographic gratings, allowing tailor-made designs for different facilities. It measures diffraction efficiency over parameters such as angle of incidence, wavelength and polarization, providing accuracy and precision in characterizing DEs up to 250 mm in diameter. The flexibility of the setup extends to the characterization of optical filters. The paper highlights the setup, features and results of the instrument and its importance for the advancement of astronomical instrumentation.
13100-169
On demand | Presented live 19 June 2024
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HARMONI is the ELT’s first light visible and near-infrared (0.45 to 2.45 µm) integral field spectrograph over a range of resolving powers from R~3500 to R~18000. It will provide 4 different spatial scales from 4*4mas to 30*60mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. This paper depicts the test tools developed to validate the Integral Field Unit (IFU) developed in Centre de Recherche Astrophysique de Lyon. The IFU is in charge of splitting, slicing and rearranging the rectangular field of view into 4 long slits (~540mm) to feed the 4 spectrographs. The IFU operates at 130K. The tools are measuring position, angular deviation, wavefront or geometry of the field at ambient and operating temperature. Their design and validation are described with measurements on prototypes in our test cryostat. Their use for the final validation of the IFU performances are also addressed
13100-170
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
A concept of the small radiation monitor was developed in the bridge phase of the ESA planned VIGIL mission. RM was required to dissipate its heat to the outer space while the thermal link with the S/C was designed to be weak. Radiation monitor had an aluminum housing consisting of an upper and a lower parts, as well as a rear wall which served as a radiator. Within the housing, detector telescopes and PCBs were mounted. Heat from both solar radiance and internal generation was dissipated solely through radiators while the unit was isolated and protected with MLI.
Technical challenges of heat dissipation were addressed and solved using modelling based on the ANSYS software. Fully representative thermal model was constructed and tested using dedicated experimental setup in a cryogenic chamber. Measurements obtained for various operation modes of the instrument proved the thermal model concept and validated calculation results.
13100-171
On demand | Presented live 19 June 2024
Show Abstract +
The precision of interferometry combined with the ability of computer generated holograms to accurately create arbitrary wavefronts provides the gold standard for measuring aspherical optical components. The additional ability of a single CGH to simultaneously create multiple perfectly aligned wavefronts opens the door for more complex metrology for aligning and verifying optical systems. This talk summarizes the general capabilities of CGH metrology and provides some examples where simultaneous measurements of multiple optical elements are used for efficiently aligning and accurately verifying optical systems.
13100-172
On demand | Presented live 19 June 2024
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The 2.34m Vainu Bappu Telescope (VBT) is a reflecting telescope that operates in two modes, prime focus and cassegrain focus, and is equipped with two instruments. In prime focus mode, the telescope has the F-number of f/3.25, and the high-resolution Echelle Spectrograph (HRES) is employed through an optical fiber. On the other hand, in Cassegrain focus mode, the F-number is f/13, and the OMR spectrograph (OMRS) is mounted for low and medium resolution spectroscopy. Currently, the VBT faces a limitation: either the OMRS or the HRES can be used due to the switch in the heavy secondary mirror. To overcome this, we present a novel method enabling the OMRS to operate from prime mode alongside the HRES. The fiber setup for OMRS is optimized with a 25-lenslet + fiber-based Integral Field Unit (IFU) capable of observing both point and extended sources. The optimized lenslet, fiber, and fore optics design is undergoing lab testing. Our approach allows seamless operation of both spectrographs on the same night, enhancing the observational capabilities of astronomical studies.
13100-173
On demand | Presented live 19 June 2024
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Key science drivers for ELT/ANDES, in particular the search for a possible change of the fine-structure constant and the direct observation of cosmic expansion in real time (a.k.a the Sandage test), require exquisite wavelength calibration. To ensure that ANDES can actually benefit from the unprecedented photon-gathering power and not be limited by systematics, an order-of-magnitude improvement in wavelength calibration compared to current instruments like VLT/ESPRESSO is needed. As a first step, substantial improvements in the ESPRESSO wavelength calibration accuracy could be achieved by a careful modeling of the line-spread function, utilizing the rich information of laser frequency comb spectra. This reduced the instrument-related systematics from over 30 m/s to 2 m/s.
In addition, the feasibility of using iodine absorption cells for an end-to-end validation of the wavelength calibration, probing the full optical path from sky to detector, was recently demonstrated. Still, achieving the ambitious goals for the ANDES wavelength calibration of 1 m/s accuracy and 1 cm/s stability over decades will require further active and dedicated research in the next years.
Session PS4:
Posters - Adaptive Optics, Active Instruments and Vibrations
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Wednesday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-174
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Focal plane wavefront sensing techniques are generally limited to using imaging systems that have below 1% spectral bandwidths, due to the radial “smearing” of speckles from chromatic diffraction that causes optical image magnification over larger spectral bandwidths. Wyne (1979) designed a pair of triplet lenses to optically minimize this chromatic magnification and increase the spectral bandwidth. Such a Wyne corrector could enable focal plane wavefront sensing at up to 50% spectral bandwidths and as a result open enable >50x higher-speed focal plane wavefront sensing. We present results of the design and laboratory testing of a Wyne corrector prototype, including a detailed tolerancing analysis considering manufactural wavelength ranges and alignment tolerances. These tests show promising results that this technology can be deployed to current and future high speed focal plane wavefront sensing instruments to enable significant performance enhancements. This document number is LLNL-ABS-857246.
13100-175
On demand | Presented live 19 June 2024
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Varying gravitational and especially asymmetric thermal influences cause relative position deviations between the primary and secondary mirror of small telescope systems. These deviations limit the achievable imaging quality. This publication characterizes an active position compensation system for the secondary mirror of a small Ritchey-Chrétien telescope. Dimensional metrology and a custom-made actuator for the secondary mirror are used in a feedback control loop to compensate these deviations in three degrees of freedom (tip, tilt and piston). Using a Shack-Hartmann wavefront sensor and an artificial star the resulting RMS wavefront errors without and with active compensation are recorded and show an improvement by up to a factor 7.2.
13100-176
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Reporting on the measurement and mitigation of vibrations of a cryostat-mounted detector relative to an optical table mounted experiment. Pulse-tube precoolers of multi stage dilution refrigerators impart small vibrations into the structure onto which the device is mounted. Issues arise if these movements exceed the pixel pitch of the detectors (100-200µm).
13100-178
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Vibrations propagating into the mechanical systems can cause many problems at different levels causing performance degradation for sensitive systems. The proposed solution in this work is to use a six-axis active hexapod based on Stewart platform configuration. The rigidity of the legs of this hexapod determines the application to be used for; a stiff hexapod, for example, is used as a rigid interface for active damping and precision pointing applications while a soft hexapod is used, in general, for the purpose of active isolation of vibrations. Notice here that introducing the appropriate design, soft Stewart platform can be used for both precision pointing and vibration isolation.
13100-179
CANCELED: Uncertainty on material properties in mirrors vibration analysis
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Propagation of uncertainty for mirrors vibration analysis in their early design phase
Session PS5:
Posters - Optics and Support Systems
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Wednesday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-47
On demand | Presented live 19 June 2024
Show Abstract +
MezzoCielo represents a novel type of monocentric optical instrument devoted to whole-sky monitoring due to
its extremely large field of view. The latter property, combined with the need to realize relative wide optical
spheres (with diameters up to few meters) and the limitations related to the manufacturing of large optical
elements having high performance, requires the adoption of a segmented structure, presenting, for instance, a
Platonic solid-like shape, composed by several equal lenses, supported by a metallic frame along the edges of the
solid itself. In this paper, the main aspects concerning the sizing of such frame (chosen to be dodecahedral) and
a thermo-mechanical analysis of the lenses support assembly, both analytical and numerical, will be presented.
It will be shown how the lenses are able to operate with little temperature difference across
their volume independently from the surrounding conditions and the way in which the telescope can withstand
external low temperatures without manifesting high thermal stresses, while maintaining, at the same time,
constant focal length. Subsequently, a birefringence investigation completes the opto-mechanical analysis.
13100-180
On demand | Presented live 19 June 2024
Show Abstract +
In LAMOST, 4,000 fiber positioners accept DC voltages for power from 64 switch power sources. The working conditions of fiber positioners need to be monitored in case that over-current phenomenon damages positioners and raises the temperature of positioners and focal plane which can seriously damage position accuracy. Considering that positioners being used in LAMOST cannot change their electrical properties, this paper implemented a power monitoring and control system based on RS485 bus and LabVIEW to avoid over-current phenomenon in LAMOST. CC6920, distributing voltage circuit and DS18B20 are used to monitor the output current, voltage and temperature of the power source respectively in real time. The monitoring values are shown on LCD and returned to IPC to be saved. When the value exceeds the rated value, relay will cut off the power and a mail will be sent to staff. The validity of the power monitoring and control system is verified by experiment in the actual environment. The preliminary results show that the system has good stability and the response time is less than 70ms.
13100-181
On demand | Presented live 19 June 2024
Show Abstract +
The well-known formulation of the maximum deflection of an optics due to its self-weight is here extended to have a direct reliable estimation of the induced defocus and spherical aberration, once the mechanical and geometrical properties of the optics are defined.
13100-183
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The paper presents a novel type of axial actuator for active optics systems of primary mirrors aimed at telescopes operated in open air.
The current prototype is designed as a force feedback actuator with a typical maximum force of 500 N, a resolution better than 0.1 N, which are typical performances for current active optics axial actuators.
The novel aspect is a fast dynamic response with a closed loop bandwidth approaching 10 Hz, hence able to compensate wind gust buffeting in open air as well as dynamic loads of any origin.
The actuator closed loop performance was evaluated by feeding force time sequences obtained from the wind buffeting spectra specified for the European Solar Telescope (EST) project, which has a primary mirror exposed to open air.
The test results show that the prototype would amply provide the surface error requirement (150 nm rms) expressed for the case of no adaptive optics (AO) rejection.
With the input spectrum attenuated by AO rejection, the surface error is currently evaluated at 8.4 nm rms, close to the current EST requirement of 5 nm rms.
13100-185
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The Vera C. Rubin Observatory is an astronomical survey facility nearing completion in Chile. Its mission is to accomplish the 10-year Legacy Survey of space and Time (LSST) survey - a 6-color optical imaging survey of the southern sky.
The science mission for the LSST resulted in demanding requirements for optical performance and system dynamics. Producing a Telescope and an Observatory meeting these requirements resulted in multiple technical challenges which were encountered and resolved during the design and construction of the project. Resolving these challenges has impacted the assembly and integration of the overall system. Analyses were performed and solutions were developed. This paper provides a general overview of these challenges and highlights some specific examples where resolutions were found and implemented.
13100-186
On demand | Presented live 19 June 2024
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The Space High-cadence Observing Telescope (SHOT) is an instrument that will operate between 1 THz and 3 THz, to obtain more information about the dynamic universe and realize a large sky survey. The prototype telescope with a 500 mm aperture is designed for technology tests. The surface accuracy is required to be better than 5 μm to ensure precise observations within its operation wavelengths. The structures of reflectors are designed through topology and multiple-objective size optimization to get the optimal shape and suitable materials. The gravity, thermal and dynamic performance structural design are analyzed and satisfy the requirements.
13100-187
On demand | Presented live 19 June 2024
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A large adapter has been designed and tested to support the weight of the Evanescent Wave Coronagraph (EvWaCo) prototype at left Nasmyth port of the 2.4 m Thai National Telescope that will be used for the first time. The EvWaCo prototype will serve as an on-sky demonstrator of the achromatic rejection capabilities of EvWaCo, and the performances of its adaptive optics system. The large adapter comprises twelve carbon fiber poles serving as supporting beams, and capable of supporting up to eight times the prototype’s weight. The installation of this adapter is expected to start by the end of 2024.
13100-188
On demand | Presented live 19 June 2024
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HARMONI is the high angular optical and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 470nm to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. HARMONI project is now finishing phase C, ready for Final Design Reviews of all subsystems.
The IFS (Integral Field Spectrograph) Pre-Optics (IPO), sub-system under the responsibility of the Institute of Astrophysics of the Canary Islands (IAC), comprises 26 Opto-mechanical mounts working at cryogenic temperatures. These mounts are classified into two types based on the optics they support: sprung kinematic mounts and thermally compensated kinematic sprung mounts. Designed to maintain optical alignment at cryogenic temperatures, they minimize optical surface deformation within the limits specified by the error budget. Thus, they ensure compliance with requirements even in the worst-case scenarios.
This work describes the verification tests performed to the Opto-mechanics to comply with the sub-system optical and mechanical requirements.
13100-189
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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The preliminary mechanical design of RIZ & UBV visible spectrographs of the ANDES instrument is presented. Those spectrographs pose an enormous challenge in their mechanical design due to their large size, mass of their optical components and the strict stability requirements, In this paper we describe how we handle these challenges thanks to the experience gained in previous successful projects, mainly ESPRESSO.
13100-190
On demand | Presented live 19 June 2024
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The Narrow Field Infrared Adaptive Optics System (NFIRAOS) within the Thirty Meter Telescope (TMT) is a large, complex instrument. NFIRAOS supports three near infrared (NIR) instruments, and therefore, is cooled to -30C to reduce background radiation. One challenge is mounting massive optics capable of withstanding a 50 degree temperature differential from mounting to operation. The use of RTV (Room Temperature Vulcanizing) silicone as an adhesive allows a more flexible bond and is capable of withstanding temperature changes without losing bond strength. The paper builds on previous analysis and initial prototype efforts by combining simulations, iterative prototyping, and stress testing to validate the design.
13100-191
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Wide Field Optical Spectrometer (WFOS) is a seeing-limited instrument under development for first-light operation on Thirty Meter Telescope (TMT). WFOS will be the only first-light instrument capable of spectroscopy and imaging between 310 and 1000 nm. It has a ~8.3’ x 3’ field of view, with a low resolution mode at R~1500, medium resolution at R~3500 and R~5000 and an imaging mode. The optical design includes an on-axis two-mirror collimator, nearly identical blue and red channel mechanisms for camera rotation and grating and filter exchange. The red and blue channels house the Grating Rotator and Exchange (GRX) subsystem and Camera Rotator Subsystem (CRS).
The grating needs to be rotated to various angles as per the requirement. The time budget for reconfiguration between observing modes is also a critical challenge that limits serial operations. The CRS and GRX comprises fully automated spectrograph mechanisms that facilitate different observing modes as per requirement. This paper discusses the various design challenges and philosophies in developing these sub-systems for the WFOS.
13100-192
On demand | Presented live 19 June 2024
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With the breakthrough development of telescope aperture, the structural weight of telescopes has significantly increased. Adopting segmented torque motor direct drive is an inevitable trend for the development of large-aperture telescopes, and the performance of the motor used directly affects the pointing and tracking accuracy of the telescope. This article focuses on the analysis of factors affecting the integrated performance of segmented motors in large-aperture telescopes, covering four aspects: segmented motor integration technology, axis support technology, high-precision position sensing technology, and high-performance servo drive technology. By delving into these influencing factors, reliable technical support is provided for subsequent integrated design of segmented motor tracking frameworks and performance testing of electromechanical integration..
Session PS6:
Posters - Telescope Structures, Domes and Additive Manufacturing
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Wednesday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-193
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Field driven design has several potential advantages for astronomical instrumentation: particularly the optimisation of geometries based on simulation data. When coupled with the ability of additive manufacturing to create lightweight, stiff structures, the benefits are clear.
Vibration loads were applied to the 6U A-DOT (Active Deployable Optical Telescope) CubeSat assembly to simulate launch conditions including modal analysis, sine vibration, and random vibration. A lightweight yet stiff, customised CubeSat chassis was then designed based on the response to this loading. The CubeSat chassis panels were additively manufactured in aluminium (AlSi10Mg) and the mounting features were machined.
13100-194
On demand | Presented live 19 June 2024
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CHORUS ( Canary Hybrid Optical high-Resolution Ultra-stable Spectrograph ) has been extended toward the short wavelength with a medium resolution spectrograph covering the range from 310nm to 410nm. For obvious reason this spectrograph could not stand in the Coudé room close to it high stability visible brother. The paper reports on the mechanical design used to place the long spectrograph in a rather uncommon place under the Nasmyth platform. A complex mechanical design is also necessary to avoid the last meter of fiber and implement a fully optical feeding.
13100-195
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Over the past decade, the National Astronomical Research Institute of Thailand (NARIT) has primarily focused on astrophysics and space science missions. NARIT currently operates a robotic national observatory system with 0.7-, 1.0-, and 2.4-meter telescopes. To enhance engineering capacity, we are developing a cost-efficient 0.5-meter Cassegrain telescope using an ultra-low expansion glass ceramic mirror (Clearceram-Z® HS). However, this material induces dynamic mirror bending during altitude adjustments, impacting astrophotography efficiency. This paper explores finite element-guided optimal engineering techniques, specifically adjusting the optomechanical support structure for the primary mirror. Calculating, designing, and simulating 6 Whiffle trees as actuators aim to minimize gravitational sag in curved mirrors. Determining optimal bolt lengths for the 0.5-meter in-house NARIT Cassegrain telescope, tested at the NARIT laboratory, is part of the process. Utilizing mechanical and optical design software, the study employs integrated simulation and co-simulation, validating their effectiveness in the primary experiment. The proposed optimization streamlines telescope adjustments.
13100-196
On demand | Presented live 19 June 2024
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A short focal length telescope is essential for remote sensing instruments (RSI) to achieve sub-meter resolution, with the premise of precise fabrication and alignment. The tolerance becomes tighter when the focal length becomes shorter, which makes the assembly issue even harder. In this paper, the catadioptric telescope with short focal length is taken as the target for developing a design methodology with the consideration on the permissible tolerance specifications of mirror surface root-mean-square (RMS) wavefront error (WFE) in system tolerance for fabrication, as well as the tolerance of surface tilt and decenter of mirror in assembly process. The parameter chosen as the trade-off variable is the aperture size of the telescope, and the tolerance budget for aligning high-resolution RSI is evaluated upon the requirement of a ground sampling distance (GSD) less than 60 cm. The result has been used as the guideline for finding optimal aperture size in an experimental remote sensing satellite (RSS) project.
13100-197
On demand | Presented live 19 June 2024
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Ensuring earthquake resilience is paramount for the upcoming Extremely Large Telescope (ELT). Instruments positioned on the Nasmyth platform are anticipated to endure substantial seismic accelerations, peaking at 3.6g in specific scenarios. These instruments have to be designed not only to survive such events but also to only require minimal repairs for sustained optimal functionality. This paper presents our approach to mitigate the dynamic forces impacting the rotary platform.
Furthermore, this paper tackles the challenge of minimizing instrument-induced vibrations affecting the telescope's structure. Given that the ELT’s optical system, composed of 798 segments, operates very similar to an interferometer, maintaining an extremely stable wavefront is crucial - a key insight learned from the Very Large Telescope Interferometer. Our focus is on identifying potential sources of vibration within specific frequency ranges where the telescope demonstrates increased sensitivity. We will explore strategies for mitigating these vibrations to maintain a wavefront error below 50nm.
13100-198
19 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
In order to meet the needs of more scientific target observations, a switching device with a wide variety of filters is necessary in a well-established focal terminal system. At the same time, this filter switching device generally has a series of characteristics such as free switching, mutual combination, fast switching, accurate operation, and no difference in image quality.
13100-200
On demand | Presented live 19 June 2024
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A unique large-span cable-net structure, as key unit of the active reflector of FAST, is introduced. The cable-net structure contains huge cable mesh and thousands of down-tied cables driven by hydraulic actuators. The illumination area of cable mesh may change spherical shape to form paraboloid during FAST works, under the condition that hundreds of hydraulic actuators drive coordinately. Therefore deformation strategy is necessary to be discussed in details on how much each actuator should stretch out or draw back to keep shape of paraboloid. Its simulation based on finite element method is further given for demonstration. The regular strategy works well if the illumination area are limited within the spherical mesh. Otherwise, it may induce such structural dangers as slack cable, over-stressed cable or fatigue failure. A new strategy is then developed to crack such problem. It first follows the regular strategy, then checks and finds out all the potentially dangerous cables. The stresses of these dangerous cables are controlled in the safe range via adjusting the related down-tied cables. A comparative simulation result with the measurement on site verifies its effectiveness.
Session PS7:
Posters - Spectroscopy: Gratings, Dispersers and Image Slicers
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Thursday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-201
On demand | Presenting live 20 June 2024
Show Abstract +
In time-domain astronomy, achieving high-speed optical spectroscopy within 10 seconds presents a significant
challenge. We are developing an efficient three-channel, image slicer-type integral field unit (IFU) for the Seimei
Telescope’s TriCCS instrument. To maximize throughput within the constraints of limited space, the IFU
optics consist exclusively of a slicer unit and spherical mirrors that form an Offner optical system, omitting
the magnification optics commonly used in conventional IFUs. The slicer unit employs a medium transmission
slit in the transmission channel instead of an air slit, resulting in a 4.6 mm backward shift of the pseudo-focal
plane, which effectively reduces dust impact on the mirror at the image plane. Our design achieves both
sufficient imaging performance and over 90 % throughput in the 400-1000 nm wavelength range, despite the
limited available space, making it adaptable to other slit spectroscopy instruments. This presentation provides
an overview of the TriCCS IFU design and its current development status.
13100-202
On demand | Presenting live 20 June 2024
Show Abstract +
The European Solar Telescope (EST), with its primary mirror of 4.2 diameter, will be the largest solar telescope available in Europe. EST will offer Integral Field Spectropolarimetry (IFS) by incorporating the EST spec- tropolariMeter Based on slicEr-mirrors for the near-infraRed (EMBER). This instrument is a high-resolution spectropolarimeter that allows for the analysis of a 2D field of view by using a slicer mirror-based Integral Field Unit (IFU) as input to the spectrograph. The slicer mirror, which is placed at the focal plane of the telescope, allows the observation of the integral field of view by slicing the entire field. After that, an optical system reorganizes the field of view and provides the spectrograph with an output slit composed of multiple slitlets. The spectrograph has a Czerny-Turner design and will cover the solar spectrum from 1 to 1.8 μm. Additionally, EMBER will offer spectropolarimetry observations with a dual-beam configuration. In this contribution, we present the conceptual optical design of the spectrograph and the IFU as a solution that meets the scientific requirements.
Show Abstract +
A new set of GRISMs based on Volume Phase Holographic (VPH) gratings is developed for the MIRC-X/MYSTIC beam combiners at the CHARA telescope array. Two of them, for MIRC-X, work in the J band and provide R = 6000; the other two, for MYSTIC, work in the K band and provide R = 4000. The design, manufacturing and test of the dispersing elements are reported and discussed.
13100-205
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Polarization measurement is a technique that investigates the polarization state of light by measuring the vibration direction of light waves, obtaining information about materials, structures, or the interaction between light and substances. It finds extensive applications in various fields such as astronomy, remote sensing, and target detection. Most current polarimeters in use require moving components and involve multiple measurement steps. To address these shortcomings, this paper proposes a polarization polarimeter with a split-pupil design based on the combination of a quarter-wave plate and a liquid crystal polarization grating. This configuration allows the polarimeter to obtain the complete set of linear Stokes parameters in a single exposure. Therefore, it has high detection efficiency. The polarimeter has no mechanical moving parts and features a compact structure., This technique can play an important role on polarization measurement instruments.
13100-206
On demand | Presenting live 20 June 2024
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The GREGOR Infrared Spectrograph (GRIS) can perform spectropolarimetric observations in the infrared. The spectrograph has a Czerny-Turner design and offered traditional long-slit observations since 2014. Later on, in 2018, it was upgraded with an Integral Field Unit (IFU) based on a slicer mirror, which has slicers of 100-μm width. The latter option makes GRIS a unique instrument in solar physics. A third upgrade took place in 2021, where optomechanical, control and software improvements have been conducted to introduce new optical channels that operate below 1 μm. These new spectral channels allow simultaneous observations with the previous infrared camera. Between these improvements, a new diffraction grating was installed to enable multi-wavelength configurations with high scientific potential. This new diffraction grating will be interchangeable with the previous one, offering flexibility between spectral resolution, simultaneity, and spectral coverage. Additionally, two more IFUs will be offered to the community with different specifications. This work presents the final optical configuration of the upgraded GRIS and the installation procedure of the most recent upgrades.
13100-208
On demand | Presenting live 20 June 2024
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Silicon immersion gratings offer a compact, high-resolution way to disperse the light for near-infrared spectrographs. Definitive characterization of these gratings is crucial as it enables these instruments to perform at their intended throughput. In this work, we present a procedure that precisely measures the blaze of these gratings and perform this procedure on 17 of our in-house gratings including immersion gratings manufactured for the Giant Magellan Telescope Near-Infrared Spectrograph (GMTNIRS).
13100-209
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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HARMONI is the first light, adaptive optics assisted, visible and near-infrared integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope (ELT). As a `work-horse’ instrument, HARMONI will offer low, medium, and high spectral resolution volume phase diffraction gratings (VPH) across the I, z, J, H, and K-bands, operating at four spatial sampling scales including at the diffraction limit of the ELT. Consequently, understanding and controlling sources of wavefront error (WFE) is of critical importance to the instrument performance. We present a comprehensive overview of the WFE performance verification for the VPH element of the HARMONI infrared grating module. In collaboration with Wasatch Photonics, we compare the measured WFE at different test wavelengths to investigate the presence of any chromatic dependence or lack thereof. Finally, we discuss the origin of the observed wavefront error and the effectiveness of mitigation techniques such as magnetorheological finishing.
13100-210
On demand | Presenting live 20 June 2024
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BlueMUSE is a blue-optimised, medium spectral resolution, panoramic integral field spectrograph under development for the Very Large Telescope (VLT). With an optimised transmission down to 350 nm, spectral resolution of R~3500 on average across the wavelength range, and a large FoV (1 arcmin²), BlueMUSE will open up a new range of galactic and extragalactic science cases facilitated by its specific capabilities.
Efficient Volume Phase Holographic Gratings (VPHGs) are key to the high and consistent transmission of BlueMUSE, both across its 16 replicated spectrographs (therefore with a particular attention to repeatability) and across the spectrum. In this paper, we present two prototypes based on dichromated gelatin and photopolymer recording materials. These were respectively manufactured by Wasatch and the Osservatorio Astronomico di Brera (INAF-OAB). We highlight key differences in the manufacturing process and compare the prototypes on the basis of their diffraction efficiency, wavefront error and scattering properties.
13100-211
On demand | Presenting live 20 June 2024
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In next generation instrumentation for Universe and Earth Observation, new instrument concepts include often non planar gratings. We propose two new technologies using lithography techniques and metasurfaces, for designing and realizing convex blazed gratings for high throughput spectrographs.
Lithographic gratings have been fabricated by lithography, angular Ar ion etching, transfer of the blazed grating from a flat surface onto a convex substrate, and finally etched by RIE into the substrate. Efficiency close to 90% on the 1st diffraction order at 700nm has been obtained and a low straylight level has been measured on the silver coated device.
Metasurface gratings have been designed using topology optimization based on finite element modeling of Maxwell’s equations. Single and multi-wavelengths optimization leads to gratings with much higher performance than the classical triangular blazed gratings, on one wavelength and on a large 400-1500nm wavelength range. First gratings with Nb2O5, 200nm thick and 220-70nm wide features (pillars and holes) on a silver layer have been realized. Performances characterization including diffraction efficiency and straylight level are under way.
13100-212
On demand | Presenting live 20 June 2024
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Conventional reflection echelle gratings of surface relief (SR) type have significantly different spectral characteristics for s- and p-polarizations. Another problem was the phenomenon of an anomaly, in which the efficiency of p-polarization of a specific diffraction order is greatly reduced due to the influence of surface plasmons. The reflector facet transmission (RFT) grating is a new echelle grating of transmission type in which the incident light from one side facet of the sawtooth-shaped grating is reflected by the other side facet, and the diffracted light is exited from the flat back side of the grating. The RFT grating achieves a large angular dispersion, higher diffraction efficiency and wider bandwidth than SR echelle gratings. Furthermore, since the RFT grating can be placed near the collimator and camera (imaging) optical system, the astronomical instrument can be made smaller than the reflective echelle grating. We prototyped a RFT grating with hard resin by ultra-precision cutting using a diamond tool. As a result of measurement of the diffraction efficiency, it demonstrates that a RFT grating is highly efficient and has small scattering losses.
13100-213
On demand | Presenting live 20 June 2024
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Transmission gratings can be placed near the collimator or camera (imaging) optical system, allowing the instruments to be made smaller. We are developing fabrication methods of a volume binary (VB) grating, trapezoid grating and reflector facet transmission (RFT) grating. The VB grating can achieve a larger angular dispersion and higher diffraction efficiency than conventional surface-relief transmission gratings with step shaped grooves, and can be achieved a wider spectral bandwidth than volume phase holographic (VPH) gratings whose refractive index is sinusoidally modulated. The trapezoid grating can bring the spectral characteristics of s- and p-polarization closer to each other than a VB grating, so it can further improve the peak diffraction efficiency. The RFT grating is a new transmission type echelle grating in which the incident light on one side facet of the sharp sawtooth-shaped grating is reflected on the other side facet, and the diffracted light is emitted from the plane on the back side of the grating. The RFT grating has higher diffraction efficiency and wider spectral bandwidth than a conventional reflection echelle grating.
Show Abstract +
Canon has been continuously developing its own machine for precision and has the capability to obtain sufficient performance even for ultraviolet. The machined grating can realize an ideal shape without material distortion and can handle many materials. The ability to produce an ideal shape makes it possible to acquire the characteristics expected from the geometry (design characteristics) even in a classical echelle grating, and it is possible to select an apex angle that is more efficient in polarization characteristics. Canon provides the degree of freedom from a small pitch to a large pitch for infrared using the characteristics of cutting. The target material can be made of a brittle material (Germanium, InP) from a metallic reflection type, and the brittle material with a high transmittance in infrared can also be used as an immersion grating or a grism. In this paper we show particularly the influence of the apex angle with the echelle grating and introduce the machinability of the Apex angle by cutting.
13100-215
On demand | Presenting live 20 June 2024
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Volume Phase Holographic Gratings (VPHGs) have proved to show interesting features, such as diffraction efficiencies larger than 90%, they can be tailored according to the requirements of the spectrograph and they are relatively cheaper compared to other technologies on the market.
Different VPHGs have been manufactured at INAF-Osservatorio Astronomico di Brera and they are now available in observing facilities. In the UV-vis spectral range, some of those VPHGs reach a peak efficiency larger than 90 % and high value across the bandwidth. Innovative solutions, such the dual order and stacked gratings have also been produced to improve the resolving power and bandwidth.
13100-216
On demand | Presenting live 20 June 2024
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Cross-dispersed echelle spectrographs (CDES) are a fundamental tool for modern astronomy. Their performance relies on the echelle pupil size and collimator focal length. Due to this, ground-based observatories, that are seeing limited, often necessitate larger instrument sizes to achieve high spectral resolutions. In contrast, space observatories, operating in a diffraction-limited regime, can utilize CDES with a smaller footprint to achieve HR performances.
The most obvious solution for size reduction is to employ a three-mirror anastigmat (TMA) telescope in a double-pass configuration. This design minimizes instrument size without compromising optical performance, but with drawbacks in its alignment sensitivity. Alternatively, a monolithic parabolic mirror provides a simpler and sturdier option but results in increased non-usable space.
Our work presents a first approach design of a CDES using a Cassegrain telescope as the spectrograph collimator. This approach effectively increases the instrument layout efficiency in terms of used space while achieving high spectral capabilities.
13100-217
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) is a thermal infrared instrument being built for Keck-II by a consortium comprising UC Santa Cruz, UC Irvine, UCLA, the Indian Institute for Astrophysics, Keck Observatory, and Caltech. SCALES comprises an Integral Field Spectrograph (IFS) and a high-contrast Imaging Channel for characterizing planetary atmospheres and detecting exoplanets, respectively. It uses a lenslet array to perform low-resolution integral field spectroscopy. The lenslets sample the 2D field disperse the spots into individually separable spectra. The Lenslet Array is a rectangular arrangement of lenslets. Maintaining the position of the Point of Contraction (PoC), which is a reference lenslet, poses a significant optomechanical challenge as it must be held in place during assembly and when the instrument is operating at temperatures of approximately 20°C and -196°C, respectively. This paper discusses an athermal design of the Lenslet Array mount, which passively maintains the PoC's position at all temperatures by utilizing the thermal expansion properties of different materials used in the mount.
13100-218
On demand | Presenting live 20 June 2024
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We developed a new germanium reflective echelle grating for HISPEC (The High-Resolution Infrared Spectrograph for Exoplanet Characterization) for the Keck telescope. We employed germanium as a substrate, which is an ideal material to achieve small wavefront error (WFE) and high diffraction efficiencies close to the theoretical limit, with robust wavefront stability against temperature change. Furthermore, to enhance the diffraction efficiency of both polarization states, we developed a grating with an apex angle of less than 90 degrees. We report that the full-size gratings with 80-degree apex angles show very high diffraction efficiencies, 96% of the theoretical limit, and very small WFE (~ 13 nm). In addition, we present WFE measurements of a small prototype germanium echelle grating at the cryogenic conditions and we confirmed that the WFE of the diffracted beam is almost identical at room temperature and at 84 K.
13100-219
On demand | Presenting live 20 June 2024
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Precision radial velocity measurement requires spectral calibration sources that exhibit short to long term wavelength stability and high modal density. Here we report on our efforts to develop a novel 400-1800 nm whispering gallery mode resonator etalon for calibration of optical or infrared spectrographs. The small crystalline MgF2 ring etalon is stable to better than 10-11 levels on 1 s timescales but requires environmental isolation and an referencing to an external standard to maintain long term performance. We will summarize our efforts thus far, as well as the performance achieved over 10 day measurements.
13100-220
On demand | Presenting live 20 June 2024
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As the telescopes of the future grow in size, survey spectrographs naturally follow that trend. The massive appearance of the instruments designed for the ELTs seems to visualize such. At some point, we hit the size ceiling, due to many reasons including available optics size, beyond which the traditional one-off way of building an instrument might be much riskier than before. One logical way to get around the limit is to break up an instrument into much manageable “replicated” units. The overall system size may still be the same, but the highly concentrated risk can now be diluted across the units that, individually, it becomes much less risky although some types of risk may be transformed into something else in the name of “consistency”. One specific area that this mattered was the alignment quality across many spectrograph units. Spanning a little more than a decade, several replicated instrument projects forced us to go through evolution cycles to refine our approach to the alignment of replicated spectrographs. This report is to give an overview of the methods and techniques we used over the years and how they could be applied to ELT-generation instruments yet to come.
13100-221
On demand | Presenting live 20 June 2024
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The accuracy of state-of-the-art EPRV spectrographs depends on the access to extremely precise and stable wavelength calibration sources. There are several available calibration sources (e.g., emission lamps, laser frequency combs, reference cavities) that can be used to calibrate an astronomical spectrograph. However, the calibration as it is currently performed is always 'local'. In the proposed talk we will present the νANCESTOR concept that proposes an accurate (absolute) and common wavelength calibration for astronomical high-resolution, high-precision spectrographs by embarking an optical frequency comb on-board a satellite equipped with an actively pointing telescope and precision orbitography. This calibration satellite shall be available and serve EPRV spectrographs in *all* major observatories around the world.
Session PS8:
Posters - Coatings, Dichroics, Filters and Metasurfaces
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Thursday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-222
On demand | Presenting live 20 June 2024
Show Abstract +
The IBS2000 project aims to develop a coating machine to coat optics with complex coating designs up to 2m in diameter. Due to the high optical quality and precision, low losses, and high mechanical and environmental stability, IBS is chosen as the coating process.
The novel approach is based on the concept, where both the substrate and the sputter assembly are in motion. The assembly is hereby located below the substrate and will move linearly while the substrate rotates around the short main axis of inertia.
Simulations are performed applying a virtual coater concept and are used to validate homogeneity and the layer deposition parameters. The results will be applied to homogenize the projected coating distribution on the final 2m optics.
13100-223
On demand | Presenting live 20 June 2024
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We demonstrate a custom hovercraft for in-situ telescope mirror cleaning that levitates above a mirror, maintaining a safe working distance to the surface of a few millimeters. The hovercraft carries an airknife to blow off large dust particles and an array of slowly spinning brushes with super-soft tapered PTFE bristles that remove the very small particles, supported by electrostatic forces. The hovercraft is powered by an external blower through an air hose and guided by a tether or crane. We demonstrate the thorough cleaning of large dusty mirrors and examine the cleaned mirrors microscopically for scratches.
13100-224
On demand | Presenting live 20 June 2024
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The ASTRI Mini-Array is an international collaboration, led by the Italian National Institute for Astrophysics (INAF), devoted to the construction, deployment and operation of a set of nine identical dual-mirror Cherenkov telescopes. They will be located at the Teide Astronomical Observatory, operated by IAC, in the Canary island of Tenerife.
The secondary mirrors of the ASTRI telescopes were realized already at the beginning of the ASTRI Project. After a few years, some of them revealed a clear degradation of the surface reflective coating. Therefore, it was necessary to look for a qualified industrial supplier able to perform a new coating of these mirrors. To this aim, the ASTRI Collaboration identified the French company CILAS as the best option. In this paper, we present the activities performed by CILAS on the mirrors. We first describe the coating approach adopted by CILAS and its tuning to the case of the ASTRI M2 mirrors. Then, we describe the qualification activities of the coating process, the problems arised and the remedial actions which were adopted. Finally, we report the obtained results from the reflectivity and homogeneity points of view.
13100-225
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
MORFEO, the Multiconjugate adaptive Optics Relay For ELT Observations, is a first generation instrument of ELT that feeds MICADO and a second generation infrared spectrograph. The optical layout is based on two deformable mirrors and there is a very large size dichroic mirror with a clear aperture larger than 800 mm, which reflects the scientific infrared light up to the Ks band and transmits the sodium emission line at 589 nm for the laser guide star system. The spectral requirements are very tight especially in the red part of the spectrum to ensure the reaching of the scientific goals; moreover the wavefront distortion has to be minimized over the wide clear aperture. The coating design strategies are reported together with the expected coating performances and the main challenges in the manufacturing of such large filter.
13100-227
On demand | Presenting live 20 June 2024
Show Abstract +
The narrow-band filters based on thin layers of dielectric material present a blue shift of the transmission curve with a larger angle from the normal.
Fast and large field of view instruments limit the ability of such filters to select small spectral features that can highlight multiple star populations in globular clusters.
We will to make an instrument like the first focus one of the LBT the spearhead facility to identify the multiple populations in galactic globular clusters.
A new set of simulations has been developed to identify the best thin-layer filter to be used to separate populations with different light element abundances. We also built an optomechanical set-up to test the filter behavior in a LBC-like configuration. We present here the simulation strategy and some transmission curve obtained with the laboratory set-up.
13100-228
On demand | Presenting live 20 June 2024
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We present a theoretical analysis of the possible optical coating for the Slit Assembly of the mission Solar-C EUVST. To achieve the highest possible heat rejection and maintain high reflectivity in a narrow band centered at 280 nm, we analyze several Al-based coating. Two of the proposed coatings, the SiO2/Al and the SiO2/[ZrO2/SiO2]^3/Al, have been produced and their reflectivity has been analyzed in a broadband spectrum from near UV to mid IR.
13100-229
On demand | Presenting live 20 June 2024
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As exoplanet direct imaging progresses, the demand for high performance coronagraphic phase masks is ever increasing. Metasurfaces, or arrays of subwavelength structures with highly tailorable geometry and material composition on thin substrate, have the potential to revolutionize starlight-blocking optics. We report on the design, fabrication, and characterization of one such device for the H-band. The optic, a charge-2, all-Si metasurface scalar vortex (MSV), is designed using a novel variable spacing framework which enables it to exhibit achromatic behavior over a 230 nm bandwidth (1.45-1.70µm). We fabricate the MSV using a photolithography based process, which is fast and relatively cheap. We characterize the phase and amplitude apodization of the mask using a digital holographic microscope. We test the coronagraphic performance of the MSV and report contrast results. We report on paths for future improvement and progress on a charge-6, Si3N4 on SiO2 visible light metasurface design.
13100-230
On demand | Presenting live 20 June 2024
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POMATA (Protective Oils for Mirrors Aging on Telescopes Alfresco) is a project funded by the Italian National Institute for Astrophysics (INAF) addressing the critical challenge of safeguarding mirrors on Cherenkov telescopes from environmental degradation. Unlike traditional observatories with domes, Cherenkov instruments lack protective enclosures, exposing their mirrors to a range of detrimental elements. POMATA seeks to identify a superior over-coating layer for the mirrors along with an optimal application method. This would prevent micro-damages and mitigate the accumulation of contaminants that may degrade the performance of the whole instrument over time. In this contribution we present the preliminary results of a comparative study that we conducted, evaluating four products for their efficacy as a cost-effective anti-aging layer using spare mirrors from the Cherenkov telescopes developed by the ASTRI project.
13100-232
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The Giant Magellan Telescope's (GMT) high angular resolution and light collecting area are key in enabling its mission to characterize the atmospheres of rocky exoplanets. The high-contrast imaging instrument GMagAO-X will enable high-angular resolution due to its advanced wavefront sensing and control (WFS&C) techniques and coronagraphic imaging capability. However, to support high-fidelity WFS&C many intermediate optics are necessary. For commercially available coatings, the cumulative throughput of GMagAO-X ranges from 5-15%. To enhance the throughput of GMagAO-X we present a design study of customized optical coatings that enable broadband throughput of greater than 50%. We implement these coatings in a polarization ray trace model of the GMagAO-X optics and investigate whether (chromatic) polarization aberrations are introduced by these coatings. These coating designs will increase the throughput of GMagAO-X significantly and bring the detection of bio-signatures within reach. We will present the results of our coating optimization strategy for high-contrast imaging instruments.
13100-233
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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The large number of sub-mirrors in the segmented reflecting telescope introduces significant challenges in maintaining the coating. Therefore, the coating for the sub-mirror needs to ensure both efficiency and longevity. This article combines the great development needs of telescopes in China to conduct experimental research on UV enhanced gold based reflective film systems. Gold is a reflective film material used in the infrared band. It has high reflection efficiency in the infrared band and the gold film is very stable. It does not react with acidic or alkaline substances in the air. However, its reflection efficiency rapidly decreases in the short wavelength range of less than 600 nm, making it unsuitable for use in visible and ultraviolet wavelengths. The project team conducted research on the UV enhanced reflection film system, utilizing the advantages of good environmental stability of gold film and high reflection efficiency in the infrared band. By optimizing the design of the dielectric film stack, the reflection efficiency in the UV and visible bands was improved, achieving an average reflection efficiency of 98% in the ultraviolet, visible, and near-infrared bands.
13100-234
On demand | Presenting live 20 June 2024
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The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel), selected as ESA’s fourth medium-class mission in the Cosmic Vision program, is set to launch in 2029, to conduct spectroscopic observations of approximately one thousand exoplanetary atmospheres, enhancing our understanding of planetary system formation and evolution.
The complex telescope, an off-axis Cassegrain design, is constructed from Al 6061, optimized for visible and
infrared wavelengths. The mirrors, coated in cryogenic-resistant protected silver, are crucial for precise observations.
The qualification of the coating was performed according to the ECSS Q-ST-70-17C standard, on a set of Aluminum alloy Al 6061-T651 disks coated with protected silver, usually stored in ISO 6 cleanroom conditions.
This paper presents the results of the morphological characterization of the samples based on Atomic Force Microscopy (AFM) and the reflectivity measurement in the infrared by Fourier Transform Infrared (FTIR) spectroscopy.
Session PS9:
Posters - Optical Fibers, Positioners, Photonic Techniques
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Thursday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-235
On demand | Presenting live 20 June 2024
Show Abstract +
We analyze aperiodic fiber Bragg gratings (FBGs) fabricated using an aperiodic phase mask, involving partial overlaps of distinct mask regions. Multichannel aperiodic FBG filters are promising candidates for suppressing hydroxyl (OH) emission lines in ground-based near-infrared astronomical observations. However, the fabrication of such multichannel aperiodic FBGs demands high repeatability. We explore the design of phase masks with repeatable FBG inscriptions. Previously, we have explored a phase mask (1st generation) designed and fabricated with partial overlapping regions using logical OR operation. Continuing this effort, we investigate three distinct phase mask designs capable of generating FBGs corresponding to five OH lines. The first mask features five discrete regions, each producing a specific FBG channel, while the other two masks incorporate numerically obtained overlap regions using logical OR and XOR operations. We present here the performances of the fabricated masks by comparing the Bragg wavelengths and the reflectivities of the inscribed FBGs.
13100-236
On demand | Presenting live 20 June 2024
Show Abstract +
Currently, ground-based infrared astronomical observations suffer from an irreducible background generated by emission from OH (hydroxyl) molecules in the upper atmosphere. However, if narrow-band notch filters could be incorporated into the optical path of astronomical instruments, then this background could be effectively suppressed with very little accompanying loss of signal from the astronomical sources of interest. Photonic ring resonators are one technology that provides a promising method of generating such notch filters. We describe our efforts to resolve heretofore-intractable engineering problems in the application of photonic ring resonators, improving their performance to the point where they can be usefully integrated with functional astronomical instrumentation.
13100-237
On demand | Presenting live 20 June 2024
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Massively-multiplexed spectroscopic surveys rely on precise optical fiber-positioning technology to match the fiber positions in physical space to targets observed on-sky. Several different technologies have been used for such devices, including pick-and-place robots, tilting spines, twirling posts, and Starbugs; each of these has its own advantages and drawbacks in terms of parallelization, pitch, exclusion radius, and other relevant operational factors. Current instruments using tilting spines operate with a pitch (that is, the separation between adjacent spines) of approximately 9 mm. Reducing the pitch to 5 mm allows for observations of many more targets in parallel, as well as (potentially) much denser target fields. Here we describe engineering efforts and progress towards reducing the pitch between adjacent tilting spines. We conclude with a brief discussion of the impact an instrument with very densely packed tilting spines would have on massively-multiplexed astronomical observations.
13100-238
On demand | Presenting live 20 June 2024
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Fiber spectroscopy technology is important in many areas of astronomical surveys. The fiber is used to transfer light from the telescope to the spectrograph. On the detector of the spectrograph, the image of fiber ends after dispersing can be obtained. In multi-mode fiber, multiple modes propagating in the fiber form a granular speckle pattern on the fiber end. In high-resolution spectral measurement, the speckle disturbs the energy distribution of the spot and reduces spectral resolution. The influence of fibers with different parameters on the centroid shift, signal-noise ratio, and radial power spectrum under artificial and mechanical disturbance is explored in this paper. The experimental results show that when the number of modes propagating in the fiber is higher, the precision of the centroid offset of the speckle is higher. Under the same disturbance condition, the speckle suppression effect is better with more mode numbers. This will be a reference for the parameter selection of optical fiber in the new instrument.
Show Abstract +
In multi-target telescopes, the back-illuminated method is commonly used to correct the position of optical fibers. A design named Special-shaped Micro-lens Aimer for Real-time Targeting (SMART) is presented to correct the position of the science fiber during astronomical observation. The characters are chosen based on the requirement of LAMOST. When the science fiber is offset from the image the target star, the offset direction and the relative offset distance can be identified by the signals in the feedback fiber. Based on the dual rotary fiber positioning structure of LAMOST, a set of position correction algorithms suitable for SMART is designed. The offset direction and the relative offset distance are decomposed into several θ and φ. The position of the science fiber is corrected by stepping movement. The experimental results show that the average farthest distance that the method could correct is 600μm, and 75.9% positioning accuracy under our closed control method can reach 10μm, 94.8% positioning accuracy can reach 20μm, 100% positioning accuracy can reach 30μm. For corrections within the 500μm offset distance, 97.5 % of the correction time is within one minute.
13100-240
On demand | Presenting live 20 June 2024
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This research explores the potential of machine learning and neural networks in recognizing the input features of aberrated wavefronts transmitted through multimode optical fibers, in view of applications for wavefront sensing in ground-based telescopes. Recent studies highlight the efficacy of multimode fibers for imaging and sensing, suggesting neural networks effectiveness in mapping relationships between output distortions and input wavefront aberrations.
The initial step of our study concerned multimode fiber propagation simulations where an input Gaussian beam was distorted with known aberrations and then sent through the fiber, to analyze the effects on the output. This groundwork is used to train and validate a convolutional neural network architecture, providing a preliminary reconstruction accuracy from the simulated output images. The subsequent phase is experimental, and it aims to validate and potentially optimize neural network training based on the new outcomes.
13100-241
On demand | Presenting live 20 June 2024
Show Abstract +
In recent years, as the exploration of cosmology has deepened, the demand for more sophisticated observational equipment has become imperative. The optical fiber positioning unit, a crucial component of the LAMOST, has emerged as a focal point of research. As a high-precision device, even minute errors can have significant ramifications (ideally controlled within the micron level). However, errors are difficult to avoid, component assembly or motion control may have an impact on the results. Our team's research focus is to explore the impact of various factors on system accuracy through software simulation. First, we establish the kinematic model of theta-phi positioners based on the geometry and D-H method. Then, the factors are analyzed and their impacts are simulated. Finally, we discuss possible methods to mitigate the influences of these factors. This study provides a reference for the design, calibration and control of positioners.
13100-243
On demand | Presenting live 20 June 2024
Show Abstract +
The key to solving numerous crucial astronomical and astrophysics issues lies in massive spectroscopic surveys mainly conducted at multi-object spectroscopy (MOS) facilities on large-aperture telescopes such as LAMOST. The efficiency of these surveys is greatly influenced by the fast and accurate movement of optical fiber positioners. However, due to the overlapped patrol discs and unexpected mechanical failure, mutual interference and collisions between positioners may occur. One existing solution is based on Markov chains and greedy selection method, which has high time complexity and results in oscillations of fiber positioners. Through analysis on collision types, a fast collision-free path planning method for fiber positioners based on the RRT algorithm and B-spline curve-fitting is proposed. The proposed algorithm can generate continuous and smooth feasible paths when collisions happen. Simulation experiments show that the proposed method can meet the requirements of fast and collision-free path planning for fiber positioners, help to improve the efficiency of massive spectroscopic surveys. This method can be adopted by not only LAMOST but also other MOS such as DESI.
13100-244
A new type of R- θ optical fiber positioning robot based on double composite parallelogram mechanism
On demand | Presenting live 20 June 2024
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Fiber positioners are essential for contemporary multi-object spectroscopic facilities as fiber positioner arrays can simultaneously place thousands of fibers. Reducing the pitch between fiber positioners increases the number of positioners at the focal plate, improving the efficiency of sky surveys. However, the collision probabilities between positioners will also increase, making path planning challenge. To solve this problem, a new R- θ fiber positioner with the double composite parallelogram mechanism is proposed It adopts the micro displacement system containing a piezoelectric ceramic actuator and a flexible hinge mechanism. To guarantee the precise linear movement of R mechanism, a parameterized virtual prototype of the robot is constructed and optimized. Finally, the performance of the manufactured R mechanism is verified by experiment. Results show that the newly designed R- θ fiber positioner can meet the requirements of accuracy.
13100-245
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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This paper fumishes a optical fiber position units auto-match method for LAMOST using delaunay triangulation method. In order to match the fiber units' pixel coordinates of the camera images with the micron coordinates of LAMOST's focal plane, we need to extract feature of each fiber units and match similar feature in micron coordinates and pixel coordinates. This paper use delaunay triangulation method to extract feature of each fiber unit, and match the fiber coordinate automatically, Relying on the methods mentioned in this papar, we can automatically and accurately achieve fiber unit matching and use it to detect fiber positioning units.
13100-246
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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The distributive parallel-controllable fiber positioning system is a key designed for The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The focal surface of the telescope with a diameter of 1.75m is divided into 4000 individual domains.A mobile parallel control system is set to control all the units, so the 4000 fibers can all move separately.In open-loop operation mode, there is no data on positioning accuracy of the FPU after operation. In this paper, we present an algorithm base on binocular vision to detect the FPU’s position using the back illuminated image of LAMOST focal plane.
13100-247
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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The technique of nulling interferometry is helping to overcome the challenges of directly detecting exoplanets and is the foundation for the Guided Light Interferometric Nulling Technology (GLINT) instrument located at the Subaru telescope in Hawaii. A new integrated optics beam combiner will be deployed to simultaneously perform nulling interferometry and fringe tracking. This is enabled by using a photonic device called a tricoupler fabricated using the femtosecond direct-write technique. The tricoupler has 3 input single-mode waveguides, producing 3 outputs consisting of an interferometric output and two phase-sensitive bright outputs. We present a rigorous optimisation of the tricouplers which includes a numerical solution to coupled mode equations to obtain coupling coefficients and propagation constants, used to optimise the fabrication process for the J- and H- bands. The polarisation behaviour, the wavelength behaviour and interferometric performance has been investigated to create an accurate transfer matrix of the device.
13100-248
On demand | Presenting live 20 June 2024
Show Abstract +
The second generation of LAMOST Telescope increased the number of fiber control units from 4,000 to 12,000, bringing great challenges to the control system. In order to obtain precise feedback control, a time sychronization algorithm based on PTP is introduced into the system, making it possible to calculate operation errors in real time, thus realize close-loop control in the two-layer system.
13100-249
On demand | Presenting live 20 June 2024
Show Abstract +
LAMOST improvement project plans to adopt a metrology camera system to update open-loop control to closed-loop control. To improve spectrum acquiring rate, the new generation of LAMOST being build is pursuing miniaturization and high-density of fiber positions, which takes more iteration time and is more likely to collide. Considering this situation, this paper presents a brand-new and real-time fiber positioning strategy with a fast fiber position recognition algorithm based on FPGA. A hardware acceleration platform is built on the main control board to process images of fiber positioners and calculate positions of each fiber throughout the overall configuration. Then the main control board re-issues operation instructions to positioners based on the information, ensuring that positioners can update its running steps and speed in real time. When the offset of positioner’s actual position from target position is less than expected value, the configuration is finished. A prototype measurement platform was set up to verify the scientific validity of this strategy.e
13100-250
On demand | Presenting live 20 June 2024
Show Abstract +
NFIRAOS (Narrow Field InfraRed Adaptive Optics System) is the first-light adaptive optics system designed for the Thirty Meter Telescope (TMT). NFIRAOS includes a laser guide star wavefront sensor system (NLGS) which contains a trombone mirror assembly that accounts for variations in the sodium layer. Within the trombone mirror assembly, there are two heavy fold-mirrors whose housings contain precision adjusters to align the laser guide stars with the wavefront sensors. The adjuster design has many unknows so a prototype of these adjusters was developed and tested to determine the best design and material selection for use in NLGS.
13100-251
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Fiber positioning technology is widely used in spectroscopic telescopes. The Z-axis position of the optical fiber tip must be strictly constrained on the focal plane, otherwise the skylight of the celestial body cannot be focused on the optical fiber tip, thus affecting the observation efficiency of the telescope. Taking the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) as an example, 4,000 optical fibers are densely distributed on the focal panel, and the distance between adjacent ones is very small, which means that contact-type instruments cannot be used. Therefore, this article proposes a fiber Z-axis position measurement method based on depth from focus (DFF). First, a new sharpness function based on the maximum edge gradient is proposed according to the edge diffusion distribution of spots in a backlight environment, which can accurately calculate the sharpness value of light spot images at different focus levels. Secondly, in order to improve the measurement speed of DFF, a focus search algorithm based on the blurred spot radius is proposed, which establishes the relationship between the defocus radius of the spot and the focus position. The displacement
13100-252
On demand | Presenting live 20 June 2024
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Photonic materials suitable for the mid-infrared wavelength range are in high demand for future astronomical instruments, particularly for space missions like the beam-combiner of the Large Interferometer For Exoplanets (LIFE). In this work, we have developed a high-performance photonic integrated platform with the potential to operate in the entire wavelength range required by the LIFE mission (4–18.5µm). Buried InGaAs waveguides with InP cladding are used, with wet-etch fabrication patterning and Fe doping incorporation during material growth. Thanks to these approaches, the first experimental results demonstrate remarkably low propagation losses below 2.5 dB/cm at 9.5 wavelengths in both TE and TM polarization modes. The achieved results of this new platform are the starting point for more complex photonic devices including nulling beam-combiners among other astronomical applications.
13100-254
On demand | Presenting live 20 June 2024
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Photonic Lanterns (PLs) play a crucial role in astrophotonic technologies, converting multi-mode inputs to single-mode outputs with low losses. Despite technical advancements, the reproducibility of PLs remains unexplored. We present a study characterizing multiple PLs to address the challenges of mass production. Initial results indicate high taper rate consistency, vital for PL stability and their integration into astrophotonic instruments. Beyond taper measurements, our comprehensive evaluation includes throughput, near-field, and chromatic analyses, ensuring mass produced PLs meet stringent telescope requirements.
13100-255
On demand | Presenting live 20 June 2024
Show Abstract +
Fibre Bragg gratings (FBGs) have found several uses in astronomical instrumentation such as spectral filtering and spectroscopic analysis. FBGs are conventionally inscribed in single-mode fibres where spectral responses are easily modelled and desired features are readily fabricated. Generally, light is coupled into single-mode fibres from multimode fibres using photonic lanterns, which are currently only available in a limited wavelength range, or by accepting a significant coupling loss. Fabrication of FBGs directly in multimode fibres has the potential to reduce coupling losses and output a more versatile beam post-filtering by the FBG. We explore the properties of FBGs fabricated in multimode and few-mode fibres using direct laser writing, discuss the options for their modelling, and consider potential applications for astronomical instrumentation.
13100-256
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Arrayed waveguide gratings (AWGs) offer a promising photonic architecture to miniaturize astronomical spectrographs by several orders of magnitudes. However, the overlapping spectral orders in an AWG need to be separated using bulk-optics cross-dispersion to retrieve the full spectrum, which reduces the photonic advantage. In this paper, we present experimental results from a proof-of-concept cascaded AWG setup, which eliminates the need for bulk-optics cross-dispersion. A low-resolution, high-FSR AWG (channel spacing ~ 8.75 nm , FSR ~ 200 nm) splits the input spectrum into coarse channels which are then dispersed at high-resolution (R ~ 30,000, FSR ~ 12 nm) using the fine AWG. Thus, the entire spectrum across ~200 nm can be imaged using one coarse AWG and a stack of fine AWGs, one corresponding to each coarse channel. Both coarse and fine AWGs are built using doped-SiO2 platform. The peak efficiencies of the low- and high-resolution chips are ~80% and ~40%, respectively, thus giving a total peak efficiency of 32% for the cascaded AWG. This high-efficiency cascaded AWG demonstration paves the way for a fully integrated photonic spectrograph for ground- and space-based telescopes.
Session PS10:
Posters - High Contrast Imaging and Polarimetry
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Thursday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-257
On demand | Presenting live 20 June 2024
Show Abstract +
The vector-Apodizing Phase Plate (vAPP) coronagraph is a single-element pupil-plane coronagraph that achromatically modifies phase to null star light in regions close to the star. The vAPP phase design can be optimized for any pupil shape to have small inner working angles and has been installed on multiple 8-m class telescopes. In this paper, we describe the manufacturing and performance testing of ELT/METIS and ELT/MICADO prototype vAPPs. We show the new vAPP designs and describe the manufacturing by Colorlink Japan, ltd. First, we demonstrate the performance of scaled vAPP prototypes manufactured in Nov 2023. We review the development and manufacturing of the liquid-crystal film, the alignment and performance of the chromium amplitude mask, and component level tests.
13100-259
CANCELED: Dot-blooming pre-compensation of halftone patterns for pupil apodizer masks
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Pupil apodizer masks used in high contrast imaging instruments require a very specific and accurate transmission profile to achieve the best performance with an Apodized-Pupil Lyot Coronagraph. However, the microdots of halftone patterns used in photomasks seem to be systematically slightly larger than nominal after fabrication, which impacts the resulting continuous-tone profile. Two solutions for pre-compensating this dot "blooming" effect are presented, as well as some measurement results obtained on pre-compensated pupil apodizer masks for the SPIDERS instrument.
13100-260
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
Abstract: A method for full Stokes polarization imaging based on liquid crystal polarization grating (LCPG) is presented. Firstly, the theory of the LCPG-based polarization detection
module, which consists of a quarter wave plate and a polarization grating, was investigated by means of Stokes calculus and Mueller matrix. The relationship between the polarization state of the incidence and the efficiencies of the diffractions was derived. The proposed Stokes polarimeter has the advantages of compact structure, and obtains the image directly in CCD camera. Therefore, this instrument has high detection efficiency.
Keywords: liquid crystal polarization grating; quarter wave plate; Stokes parameters; polarimeter
Session PS11:
Posters - Technologies for Vacuum and Cryogenic Instruments
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
View
Thursday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-262
On demand | Presenting live 20 June 2024
Show Abstract +
GRANCAIN (GRAN CAmara INfrarroja) is a first light imaging instrument in J, H and K infrared bands for GTC’s Adaptive Optics system. The symmetrical and athermalized optomechanical design, free of residual stresses, effectively reduces optical axis deviations, simplifying the iterative process of optical alignment in cryogenic conditions. The article contains a detailed description of the design, fabrication techniques, metrology, integration, aligning and testing of the athermalized opto-mechanical elements
13100-263
On demand | Presenting live 20 June 2024
Show Abstract +
At INTA, a passive heat switch was designed, produced and tested, in order to obtain a thermal conductivity curve of the material through experimental means, and the total conductance of the thermal switch. This characterization should enable to validate this design, and conclude on the introduction of this element in the thermal design of cryostats for cryogenics projects.
13100-266
On demand | Presenting live 20 June 2024
Show Abstract +
The SCALES instrument being developed at UC Observatories is designed to take spectra of directly imaged exoplanets in the thermal infrared (1-5 microns). The ability to switch from science imaging mode to pupil imaging mode to taking spectra at specific wavelengths requires precision mechanical subsystems to enable these different modes of operation at cryogenic temperatures. In this paper we discuss the design of a rotary stage that can position different Lyot masks, as well as different high precision metal optics to enable some of the broad functionality of SCALES. We will also review some of the analysis involved with validating the design, and specifics pertaining to the design of the precision mirrors mounted to this stage.
13100-267
On demand | Presenting live 20 June 2024
Show Abstract +
MIMIZUKU, the mid-infrared instrument for the 6.5-m telescope at the University of Tokyo Atacama Observatory (TAO), employs a cold chopper to perform chopping, which tilts the mirror placed at a temperature of about 20 K. The mirror rotates around two orthogonal axes, and its tilt angle is controlled by the balance between the restoring force of the flexural pivots and the magnetic force driven by the coils in the system. In this study, we developed a final-product model of the chopper and tested its on-board performance in MIMIZUKU. This experiment showed that the mirror could be operated with a stability of 3.34 × 10-4 and 3.24 × 10-4 degrees, and a transition time of 31.5 and 31.2 milliseconds for each rotation, when both rotations were driven at 5 Hz with an amplitude of 0.58 degrees, satisfying the performance requirements.
13100-268
On demand | Presenting live 20 June 2024
Show Abstract +
For giant telescopes using mosaic technology, the flatness of the Mosaic Focal Plane Arrays (MFPAs) is an important determinant of their image quality. In order to measure the flatness through the flat dewar window of cryogenic chamber, a measurement system called differential triangulation measurement system (DTMS) is designed. The DTMS mainly includes four parts: a displacement platform, two laser triangulation sensors, the connecting structure and an optical flat as reference surface. To operate DTMS, an operational software system is developed. The operational software consists of the control and processing software developed by QT, the displacement platform control module realized by PLC and the sensor control module. Through the operational software, users can easily operate the DTMS to scan the MFPAs and calculate the flatness. As for data processing, it is implemented based on the Progressive Sample Consensus (PROSAC) algorithm which can reduce the effect of anomalous data points on flatness calculation. The DTMS and its operational software have been used to measure the flatness of the Wide Field Survey Telescope (WFST).
13100-269
CANCELED: Opto-Mechanical Mount design for the Dirac Cryostat
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
The optical design for the DIRAC instrument, which is an infra red instrument for the DAG telescope, identified the requirement of optical elements made from CaF2 and LiF2. These materials are very sensitive and require mechanical mounts that produce very low stresses during operation at cryogenic temperature. The AAO developed the optomechanical train as a part of the instrument development.
13100-270
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
Show Abstract +
SCALES (Slicer Combined with Array of lenslets for Exoplanet Studies) is a high-contrast lenslet integral-field spectrograph for W. M. Keck Observatory. SCALES will facilitate exoplanet characterization in the 2-5 micron range. Featuring a cryogenic optical system, it conducts integral field spectroscopy with low spectral resolution (<300) and medium spectral resolution (5000−10000). SCALES characterizes cold exoplanet and brown dwarf atmospheres (<600 K), capturing spectral features that no existing IFS instruments are capable of.
Radiation from the telescope structure can contribute to the background noise in infrared instruments, impacting the signal-to-noise ratio (SNR) which negatively affects the performance of the instrument. Therefore, to enhance the SNR, a pupil mask, synchronized with telescope pupil rotation, is implemented to eliminate background radiations during observation. The paper outlines the design of a pupil mask rotator mechanism, incorporating bought-out items such as a direct drive brushless motor for use in cryogenic conditions, presenting a solutions to the mechanical engineering and control challenges posed by this intricate implementation.
13100-271
On demand | Presenting live 20 June 2024
Show Abstract +
In this contribution we will focus on new synthesized metamaterials that we propose to include in future ground and space cryostats. These metamaterials are functional nanocomposites for thermal and electromagnetic isolation. We have followed two parallel scalable synthesis strategies:
i) Nanocomposite flexible films composed of Polyether-ether-ketone matrix filled with different TiO2 nanotubes, FeNi thin films and Au nanocolumns.
ii) Self-ordered three-dimensional networks of nanowires and TiO2 nanotubes obtained by electrochemical routes on aluminum and titanium.
The results show suitable electromagnetic responses at DC and GHz range combined with appropriate thermal conductivity. Nanocomposites are suitable for integration into additively manufactured PEEK structures, while three-dimensional nanonetworks could be implemented as conformal coatings on aluminum or titanium parts.
This work was supported by: Karlsruhe Nano Micro Facility, a Helmholtz Research Infrastructure at the Karlsruhe Institute of Technology, EU MSCA project 101107507-MIDAS, PID2020-115325GB-C31, PID2020-117024GB-C42 and PID2020-118430GB-100 funded by MCIN/AEI/ 10.13039/501100011033.
13100-272
On demand | Presenting live 20 June 2024
Show Abstract +
At the IAC (Instituto de Astrofísica de Canarias) different lubrication techniques have been applied over the years to prepare commercial bearings at room temperature for operation at cryogenic temperatures. This paper discusses these techniques and the selected materials for bearings preparation and presents the results of the latest cryogenic temperature life tests conducted on the produced bearings, along with the conclusions reached.
13100-273
On demand | Presenting live 20 June 2024
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HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews.
The spectrographs of HARMONI collimate and direct the output beam at 3 different incidence angles on the holographic gratings, one angle per family of gratings (low, medium and high resolution).
To maximize the observing efficiency of the ELT, the operation of HARMONI envisages the calibration exposures to occur during day time. This requires the collimated beam to be positioned at the grating with a repeatability of 1.4 arc seconds in a 24-hour period along the spectral direction and 10 times smaller along the slit, independently of the resolution used.
This work presents the design, analysis and prototyping performed on the Folding Mirror Mechanism in order to comply with the repeatability requirements under cryogenic conditions, highlighting the improvements incorporated into the final design.
13100-274
On demand | Presenting live 20 June 2024
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Infrared astronomy has become an important branch of contemporary astronomy, and infrared telescope is the observation basis of infrared astronomy. In this paper the method and realization of low temperature control and vibration measurement of an infrared camera using MCT-25(Hg-Cd-Te) detectors are introduced.
The MCT-25 detector is a refrigerated near-infrared detector, which needs to work at a temperature below 80K. In this paper, a tube refrigerator is used to refrigerate the detector at low temperature in vacuum chamber. In order to avoid damage of the cold optical lens caused by low temperature, two-stage temperature control is carried out on the base-plate of detectors and cold optics through temperature control circuit. The detector temperature is cooled to below 80K, and the temperature of cold optics is kept at 135K.
The work of the refrigerator will cause small vibration of the detector, which will reduce the imaging quality of the camera. In this paper, the three-axis vibration of the detector is measured by mechanical method and optical method respectively, which provides data basis for the analysis of the influence of vibration on imaging and image correction.
Session PS12:
Posters - Novel and Disruptive Concepts
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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Thursday Poster Session schedule and event details
Each day includes a unique set of posters. Poster groupings are listed below by topic.
13100-275
CANCELED: New generation cutting-edge technologies for 3D printed high-speed deformable silicon-based mirrors: PEPR Origins/FlexSiMirror
20 June 2024 • 17:30 - 19:00 Japan Standard Time | Room G5, North - 1F
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PEPR Origins FlexSiMirror consortium is developing a new lightweight, hybrid and high-speed mirror technology based on the state processes to fabricate defects-free and self-supporting silicon membranes with locally doped areas and also develop a disruptive technology using 3D printed electroactive polymers or ceramics actuators to produce, at higher temporal bandwidth (1-to-3kHz), large and very accurate displacements compliant with the needs of future instruments.
13100-276
On demand | Presenting live 20 June 2024
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To image nearby Earth-like exoplanets (located 10 parsecs from us) with a spatial resolution of less than 1 microarcsecond, which would allow us to distinguish surface environments, we would need an optical space telescope with an aperture exceeding 100 km. Accordingly, we have initiated a study to assess the feasibility of a novel telescope concept. This concept employs a combination of “magnetic formation flight of ultra-small satellites” and a “diffractive optical system”. For a ground-based demonstration, we have fabricated two types of diffractive optical elements (DOEs): binary amplitude and 4-level phase. Each DOE is a 30 mm square and part of 100 mm diameter optics with a focal length of 1000 mm. We present experimental results of their point spread functions, wavefront errors, and transmittances. We also discuss the potential of the diffractive optical system for future large optical space telescopes.
13100-277
On demand | Presenting live 20 June 2024
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IMAGO is a prototype for the application of augmented reality to the images produced by historical telescopes. Its purpose is to offer an innovative experience to the public, increasing their interest in astronomy and revitalizing those telescopes, no longer suitable for scientific purposes but always impressive and evocative.
13100-278
On demand | Presenting live 20 June 2024
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One of the challenges of astronomical instrumentation is to overcome the intermediate stages between design and acceptance testing of the instruments. Manufacturing, integration tasks and, above all, testing to validate them requires adequate infrastructure. At the Institute of Astronomy of the UNAM we have identified the importance, in terms of quality, cost and time, of investing in this. In this work we will present the development of methodologies and instrumentation that we have implemented for the integration and validation stages of the instruments; the design, manufacturing and metrology capabilities of optical and mechanical components complying with aerospace quality requirements and standards, as well as the adaptation of the necessary spaces to perform these tasks.
13100-279
On demand | Presenting live 20 June 2024
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Image slicers are key components in many astronomical instruments, notably in the VLT-MUSE instrument. However, the precision manufacturing of image slicers is costly and time-consuming. One technology that could transform the manufacturing of fused silica image slicers is ultrafast laser-assisted etching (ULAE), as it enables micron-level precision shaping of fused silica over multi-mm scales. In this paper, we demonstrate the fabrication of a 10 x 1 mm fused silica surface with ~700 nm (peak-to-valley) surface form error and ~70 nm (rms) roughness. If combined with post-processing polishing techniques, such as CO2 laser polishing, ULAE could yield high-performance freeform fused silica image slicers for diverse applications, including astronomy.
13100-281
On demand | Presenting live 20 June 2024
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Advancements in ground-based liquid mirror telescopes that enable tilt and slew while maintaining mirror functionality would allow for very large-scale, low-cost mirror solutions. Here, we present both a solution framework as well as preliminary modeling results to demonstrate feasibility for a reflective ferrofluid, magnetically-actuated approach. We propose reflective ferrofluid development and optimization as well as manufacturing of a magnetically permeable paraboloid shell with surface wicking structure and electromagnetic coil arrays to deliver required wavefront performance and maintain fluid stability. We share our initial model and small-scale test results with baseline ferrofluid, wicking structure, and actuation inputs to demonstrate feasibility and describe our plans for a 50 cm mirror build in the near future.
13100-282
On demand | Presenting live 20 June 2024
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The context of this work is to improve the performances of the FIRST instrument, already on-sky at SUBARU Telescope. In the framework of astrophotonics, in order to reduce crosstalk observed in planar photonic integrated circuits (PICs), and therefore increase the instrument’s stability and sensitivity, we have designed and fabricated a series of 3D laser-written optical chips with 5T beam combiners. These chips have been tested in the FIRST/SUBARU optical bench simulator at LESIA, injecting five inputs simultaneously and scanning the fringes using independent MEMS segments, inducing a relative OPD modulation. The results of this study, comparing the signature obtained for a single source (star) as compared to a binary, with different relative flux will be presented in this work. We will show that both polarizations are guided, with no crosstalk, and analyze the interferometric performances as a function of the source type, showing that the binary companion can be detected, and evaluate the detection limit
13100-283
On demand | Presenting live 20 June 2024
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The Low Order Wavefront Subsystem (LOWFS) provides field stabilisation and low-order wavefront sensing in seeing-limited and LTAO observing modes, measuring the motion of the instrument focal plane relative to the telescope wavefront sensors. A new set of requirements have been set for the LOWFS, Prompting a complete redesign of the subsystem to accomodate two pick-off arms instead of just one.
A trade-off process has been conducted to explore different architecture options. This process starts with the selection of the trade-off main criteria and metrics that will drive the decision. Among those metrics there are performance and functionality requirements, impact on cost and schedule, among others. Additionally, weights are allocated for each one of the metrics. After analysing the different architectures, a set of two solution was selected to be further developed. Finally, the final trade-off matrix as well as the selected architecture are described in this paper.
13100-284
On demand | Presenting live 20 June 2024
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Wavefront sensors (WFS) have now become core components in the fields of metrology of optical systems, biomedical optics, or adaptive optics systems for astronomy. However, none of the designs used or proposed so far achieve simultaneously a high spatial resolution at the pupil of the tested optics and absolute measurement accuracy comparable to those of modern laser-interferometers. This paper presents an improved WFS concept that reaches both previous goals. The device is named Crossed-sine phase wavefront sensor (CSPS) and is based on a fully transparent gradient phase filter located at an intermediate location between the virtual pupil and image planes of the tested optics. The theoretical principle of the sensor is described in Fourier optics formalism. Numerical simulations confirm that a measurement accuracy of /100 RMS is achievable. The CSPS also offers the advantages of being quasi-achromatic and working on spatially or spectrally extended natural or artificial light sources
13100-285
On demand | Presenting live 20 June 2024
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author listing:Bo Zheng,Guomin Wang,Hai Wang,Yabo Wu,Canyi Jiang,
This paper puts forward an electromagnetic suspension (EMS) axial unloading scheme,the effectiveness of the scheme is verified from the perspective of power.The model is verified by simulation software.
13100-286
Off-axis aberrations correction in liquid mirror telescopes using magnetic liquid deformable mirrors
On demand | Presenting live 20 June 2024
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Liquid Mirror Telescopes (LMTs) are based on a large objective mirror formed by spinning a reflective liquid around the zenith. LMTs offer numerous advantages but are limited to observations along the zenith only. We present a solution which expands their field of view around the zenith by effectively compensating for the large off-axis aberrations inherent to the LMTs. The rotating liquid mirror is augmented with an adaptive optics system based on a magnetic liquid deformable mirror (DM) which cancels out the large off-axis aberrations. We present the simulation results of a prototype setup comprising a 30 cm rotating liquid mirror used as the primary mirror. The large off-axis aberrations at 25o from the zenith are corrected by a convex secondary mirror and a magnetic liquid DM controlled by an array of dual-layer electromagnetic actuators. We demonstrate the feasibility of expanding the application of the LMTs while retaining their cost-effectiveness as an advantage over the conventional telescopes.
13100-287
On demand | Presenting live 20 June 2024
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We report here on the development of a self-assembling ferrofluidic ionic liquid mirror (FILM) telescope. This work has two primary thrusts: modeling and simulation of the magnetic fluid system optimized for a 0.5 m diameter demonstration mirror capable of tilting 10° off-axis, and the supporting development of laboratory 0.1 m prototypes of the fluid and magnetic systems. Prototypes of a self-organizing bilayer liquid mirror that is both a ferrofluid and reflective have been developed and tested. The liquids are held in place and shaped within the mirror by use of the magnetic array, hydrophilic materials, and the high surface tension and high viscosity of the liquid.
Digital Posters
The posters listed below are available exclusively for online viewing during the week of SPIE Astronomical Telescopes + Instrumentation 2024.
13100-177
21 June 2024 • 20:00 Japan Standard Time | On Demand Only
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This project focuses on the safety issues of the space telescope's primary mirror using active support technology. It analyzes the external load conditions during the telescope launch process, understands the power transmission characteristics of the primary mirror isolation system, fully utilizes the existing active support behind the primary mirror, and designs a main mirror active isolation immune control system under the coordinated action of multiple actuators. Through the method of active isolation, it effectively suppresses the low-frequency vibration loads acting on the primary mirror, thereby ensuring the safety of the primary mirror during the launch process while minimizing the weight of the primary mirror as much as possible.
Conference Chair
NOVA Optical & Infrared Instrumentation Group at ASTRON (Netherlands)
Additional Information
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- Check the individual conference call for papers for additional requirements (i.e. extended abstract PDF upload for review or instructions for award competitions)
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