We built an externally dispersed interferometer (EDI) testbed for exploring methods of improving high resolution spectrograph performance. We tested the EDI on the Keck Planet Finder (KPF) spectrograph May 11, 2022 measuring a Fabry-Perot (FP) etalon back lit by white light. This is also the first time an EDI has been used to measure a periodic source. The data shows that the EDI is useful for diagnosing the point spread function (PSF) width and shape, in particular the asymmetry of the PSF. This EDI ability comes because EDI can simultaneously measure both the conventional nonfringing spectrum, and the fringing derived spectrum. A conventional spectrograph resolution is limited by slit blur– the EDI resolution is not. A heterodyning effect shifts the fringing sensitivity peak to arbitrarily higher frequency, set by the interferometer delay value, and thus its resolution can exceed the spectrograph used alone. By comparing the Fourier transforms of the two measured signals, we can compare the phase shift changes, which gives information about the small asymmetry of the spectrograph blur, independent of the much larger asymmetry of the FP source spectrum. We show that comparing the phases of the nonfringing and fringing components versus harmonic number in the Fourier Transform is a useful method for measuring the asymmetry in the PSF. We report the first measurements of an EDI measuring a periodic source, which is a Fabry-Perot (FP) interferometer back illuminated by white light. The periodic character of the FP source created spikes in the Fourier transform, which was very convenient for analysis.

State of the art astrophysics demands extremely stable wavelength measurements, e.g. few cm/s scale Doppler radial velocimetry for Earth-like planet detection or multi-year cosmic redshift drift measurements. We present new techniques for 500 − 1000× improvement in stability using an interferometer in series with a spectrograph to form an Externally Dispersed Interferometer (EDI). When the received spectrum suffers a wavelength jitter, the phase of the moir´e pattern from the interferometer delay shifts in opposite directions for two signal paths, nonfringing and fringing; with appropriate weightings (“crossfading”) the net phase reaction cancels, stabilizing the spectrum. We present an improvement to our previous technique of multiple delays, using a single delay to crossfade, and demonstrate stabilization of ≳ 500× on existing Hale Telescope data. Single-delay EDIs are easier to construct and operate than those with multiple delays, and the EDI ensures that exactly the same pixels are used for the science and calibration signals, and in constant proportion under intensity fluctuations, greatly easing positional requirements.

This PDF file contains the front matter associated with SPIE Proceedings Volume 12184, including the Title Page, Copyright information, Table of Contents and Conference Committee lists.

In 2022, Subaru is entering a new stage called ”Subaru-2” which will be realized by the three wide-field facility instruments. The first one is the Hyper Suprime-Cam (HSC), the prime focus optical imager with 1.5 deg FoV. It started the science operation in 2014 and completed the strategic survey program last year with total of 330 observing nights. The second instrument is the Prime Focus Spectrograph (PFS), which is an optical to nearinfrared multiobject fiber spectrograph with a similar FoV to HSC. In 2021, it started engineering observations with all of the delivered subsystems; the Prime Focus Instrument, Spectrograph Module 1, Fiber Cable System 1, and Metrology Camera System. The commissioning and installation of the other subsystems will continue in 2022-2023. The third system is the ULTIMATE-Subaru which consists of the Ground Layer AO (GLAO) system and wide-field near-infrared instruments. The conceptual design review of the instruments was done in 2021, and the preliminary design review of the GLAO system is planned in 2022. Among the existing facility instruments, the Adaptive Optics system, AO188, is undergoing active upgrades which include the new laser guide star system, real-time computer system, deformable mirror, NIR wavefront sensor, and relay optics to quickly switch the downstream science instruments. We will also present the status and plan of the other facility instruments as well as the visitor instruments.

The Paranal Instrumentation Programme, presented for the first time ten years ago at SPIE, is responsible for planning and delivering the instruments and the associated infrastructures needed to keep the VLT and La Silla Observatories at the forefront of ground-based astronomy. After the completion of the second generation VLT/I instruments (MUSE, SPHERE, MATISSE, GRAVITY, ESPRESSO) and infrastructures (AOF, VLTI), a new generation of instruments is In commissioning, or close to be commissioned, for the VLT (ERIS, MOONS) and for the 4 m class telescopes (NIRPS, SoXS, 4MOST). Following a strategy that aims at maximizing the scientific output of the VLT/I in the ELT era, upgrades are performed (CRIRES, FORS) and three new projects (MAVIS, CUBES and GRAVITY+) have recently started, with BlueMUSE in the pipeline as next. In addition to providing an overview on the status of the programme, a few facts on the twelve major projects delivered are provided.

Since the start of science operations in 1993, the twin 10-meter W. M. Keck Observatory (WMKO) telescopes have continued to maximize their scientific impact and to produce transformative discoveries that keep the observing community on the frontiers of astronomical research. Upgraded capabilities and new instrumentation are provided though collaborative partnerships with Caltech, the University of California, and the University of Hawaii instrument development teams, as well as industry and other organizations. This paper summarizes the performance of recently commissioned infrastructure projects, technology upgrades, and new additions to the suite of observatory instrumentation. We also provide a status of projects currently in design or development phases and, since we keep our eye on the future, summarize projects in exploratory phases that originate from our 2022 strategic plan developed in collaboration with our science community to adapt and respond to evolving science needs.

The Gemini Observatory* instrument program supports breakthrough research in areas like extrasolar planets, time domain astrophysics, dark matter and dark energy, with the best possible competitive instrumentation suite given technological and budget constraints. This talk will give a broad overview of Gemini's instrumentation program focusing on achievements, challenges and strategies. We report the status of the currently offered facility instruments and AO systems at each telescope. The facility instrument program offers a strong suite of capabilities with broad applicability, which can handle the largest share of science return and as a consequence concentrates the largest development efforts. We recently completed integration and started the commissioning of GHOST, a high-resolution optical spectrograph; we are starting the integration of SCORPIO, a simultaneous 8-channel, optical to infrared camera and spectrograph, and the integration of the near-infrared high-resolution spectrograph IGRINS-2. There has been continued progress on the design of the community lead multi-IFU MOAO spectrograph, GIRMOS, which will operate with GNAO, the future adaptive optics facility at Gemini North, which is also in its design stage. In addition, the visiting instrument and instrument upgrade programs support more unique observing modes, which might have narrow scope but potentially high scientific impact. We summarize the progress and next stage of the radial velocity spectrograph MAROON-X, the performance of the speckle imagers in each site, the ongoing improvements to the GeMS MCAO system at Gemini South, the upgrades of GPI prior to its relocation to Gemini North, and the start of the commissioning phase of the first of two IFUs for GNIRS at Gemini North.

Washburn Astronomical Laboratories of the University of Wisconsin-Madison Astronomy Department has developed a near infrared (NIR) integral field spectrograph for the 11-meter Southern African Large Telescope (SALT). This instrument will be the first to extend SALT’s capabilities into the NIR, providing medium resolution spectroscopy at R = 2000-5000 over the wavelength range of 0.8 to 1.7 microns. The spectrograph is cooled to -40 C in an enclosure beneath the telescope, with the cryogenic dewar inside this enclosure operating at 120 K via a separate closed cycle cooler. The spectrograph uses volume phase holographic gratings with an articulated camera for setup versatility. The integral field unit (IFU) is an elongated hexagonal bundle of 212 fibers, each of which subtends 1.3 arcsec on the sky, matching the median site seeing. The IFU has on-sky dimensions of 29 x 18 arcsec, ideally suited for studies of nearby galaxies. A separate 38-fiber sky bundle can be adjusted to distances ranging 48.6 to 159.2 arcsec from the object IFU with a gimbaled jaw that maintains telecentricity and equal field angles for the object and sky bundles. Sky fibers are interleaved with object fibers along the 8-arcmin long spectrograph slit. The instrument has been fully tested in the laboratory and began installation and commissioning on SALT in May 2022. In this paper we present design highlights of the as-built instrument and IFU, optical alignment procedures, performance results from laboratory characterization, and the current status of installation and commissioning on the telescope.

MAVIS is the world’s first facility-grade visible MCAO instrument, currently under development for the VLT. The AO system will feed an imager and an integral field spectrograph, with 50% sky coverage at the Galactic pole. MAVIS has unique angular resolution and sensitivity at visible wavelengths, and is highly complementary to both JWST and ELTs. We describe both instruments in detail and the broad range of science cases enabled by them. The imager will be diffraction-limited in V, with 7.36 mas per pixel covering a 30” FOV. A set of at least 7 broad-band and 15 narrow-band filters will provide imaging from u to z. The spectrograph uses an advanced image slicer with a selectable spatial sampling of 25 or 50 mas to provide integral field spectroscopy over a FOV of 2.5”x3.6”, or 5”x7.2”. The spectrograph has two identical arms each covering half the FOV. Four interchangeable grisms allow spectroscopy with R=5,000 to R=15,000, from 380-950 nm.

In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (> 40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R >20, 000 (with a lower-resolution, sky-limited mode of R ~7, 000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio (SNR) ~20 per high-resolution element at 313 nm for U ~18.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients. The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the detailed design and construction phase. First science operations are planned for 2028.

Liger is a next-generation near-infrared (810 - 2450 nm) integral field spectrograph (IFS) and imaging camera for the Keck Observatory adaptive optics (AO) system. Liger will enable new science by providing enhanced capabilities, including higher spectral resolving power (R=4,000 – 10,000), access to shorter wavelengths (< 1000 nm), and larger fields of view (13 arcsec x 7 arcsec) than any current or planned ground- or space-based IFS system. The imaging camera sequentially feeds an IFS that makes use of slicer assembly unit and lenslet array. We will present the overall design of the Liger subsystems and review the key science drivers.

FRIDA is a diffraction-limited imager and integral-field spectrograph for the adaptive-optics focus of the Gran Telescopio Canarias. In imaging mode FRIDA provides scales of 10, 20 and 40 mas/pixel and in IFS mode spectral resolutions of about 1200, 4000 and 30,000. Coronographic masks are available in both modes for high-contrast images. FRIDA is starting systems integration and is scheduled to complete system testing at the laboratory by the end of 2023 and to be delivered to the telescope shortly thereafter. In this contribution we present a summary of its design, fabrication, current status and potential scientific applications.

The Large Lenslet Array Magellan Spectrograph (LLAMAS) is a facility-class Integral Field Spectrograph slated for commissioning on the 6.5-meter Magellan Baade telescope in Fall 2022. LLAMAS' Integral Field Unit (IFU) contains a 2400-element microlens array which projects pupil images onto corresponding optical fibers for high fill factor and illumination stability. The IFU subtends a 34" x 34" sky area sampled at 0.75" pitch with ~95% fill. The fibers fan out to eight replicated spectrometers. Each spectrometer covers 350-980nm per exposure at R=2200, split over three separately optimized wavelength channels. A set of 24 thermo-electrically cooled COTS CCD cameras records data for each exposure, with heat loads transferred to a dedicated chilled water loop. We provide a status update on LLAMAS' integration and test, which is in advanced stages. Upon commissioning, LLAMAS will be available to all Magellan users, and any US investigator through NOIRLab allocation of NSF/MSIP nights.

We present the detailed performance of the preliminary end-to-end optical design of GIRMOS that is designed to take advantage of the multi-object adaptive optics corrected field at the Gemini North telescope. GIRMOS’s optical design consists of object selection pick-offs, adaptive optics, and four identical Integral-Field Spectrographs (IFSes), which employ image slicers to arrange the integral field along a slit. Each IFS can image the individual FOV of 1.0x1.0”, 2.0x2.0”, 4.0x4.0” over a 2’ diameter field-of-regard at different spatial sampling. The pick-offs can also be configured in close-packed arrangement to image a single field. Spectral resolutions of R~3000 and 8000 are available in 0.95-2.4 μm.

The GIRMOS instrument is a multi-object spectrograph with four channels combined with an infrared imager housed within a common cryostat. This instrument will be fed by ground-layer adaptive optics (GLAO) or laser tomography AO (LTAO) corrected light from the Gemini North Adaptive Optics (GNAO) system. The combined instrument will provide unique scientific capabilities such as simultaneous imaging/spectroscopy modes (for precision spectrophotometry) and interleaved imaging-spectroscopy-imaging modes (for characterizing time-variable sources). The National Research Council Canada has recently completed the Preliminary Design of the Imager opto-mechanics. In this paper, we present the driving requirements, as derived from the science cases, and the optical and mechanical designs. The optical design maps a large fraction of the GIRMOS field-of-view onto a single engineering-grade 4Kx4K HAWAII 4RG detector with 21 mas pixels, provided by the Gemini Observatory. The imager produces diffraction-limited image quality across Y, J, H, and Ks-bands across an 85x85” field for an f/32 beam. It includes a location for a full filter complement, an accessible pupil for a cold stop to minimize thermal background, and a pupil imaging mode to align the cold stop to the telescope pupil. The lenses are mounted in cells with rolled flexures or athermalized centering pins and are preloaded to withstand 5g accelerations and provide thermal stability. The filters are housed in a double wheel assembly with cryogenic bearings and roller detents. All of the imager components are connected with a substructure that interfaces with the spectrograph optical bench. This substructure allows for easier testing and integration of the imager, independent from the spectrographs.

EIFIS (Extreme Integral FIeld Spectrograph) is a modular integral field spectrograph, based on image slicers, and makes use of new, large format detectors. The concept is thought to cover the largest possible field of view while producing spectroscopy over the complete optical range (3 000 - 10 000 ˚A) at a medium resolving power of ∼2400. In the optimal concept, each module covers a field of view of 38” x 38” with 0.3” spaxels, which is fed into a double spectrograph with common collimator optics. The blue arm covers the spectral range between 3000 and 5600 ˚A and the red arm between 5400 and 10100 ˚A, allowing for an overlap range. The spectra are imaged onto 9.2k x 9.2k detectors using a double pseudoslit. The proposed design for the 10.4m Gran Telescopio Canarias uses a total of 6 such modules to cover a total of 2.43 square arcminutes. Here we will present the conceptual design of the instrument and a feasibility study of the optical and mechanical design of the spectrographs. We discuss the limitations and alternative designs and its potential to produce leading edge science in the era of extremely large telescopes and the James Webb Space Telescope.

We present the design of SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) a new 2-5 micron coronagraphic integral field spectrograph under construction for Keck Observatory. SCALES enables low-resolution (R∼50) spectroscopy, as well as medium-resolution (R∼4,000) spectroscopy with the goal of discovering and characterizing cold exoplanets that are brightest in the thermal infrared. Additionally, SCALES has a 12x12” field-of-view imager that will be used for general adaptive optics science at Keck. We present SCALES’s specifications, its science case, its overall design, and simulations of its expected performance. Additionally, we present progress on procuring, fabricating and testing long lead-time components.

The Rubin Observatory Commissioning Camera (ComCam) is a scaled down (144 Megapixel) version of the 3.2 Gigapixel LSSTCam which will start the Legacy Survey of Space and Time (LSST), currently scheduled to start in 2024. The purpose of the ComCam is to verify the LSSTCam interfaces with the major subsystems of the observatory as well as evaluate the overall performance of the system prior to the start of the commissioning of the LSSTCam hardware on the telescope. With the delivery of all the telescope components to the summit site by 2020, the team has already started the high-level interface verification, exercising the system in a steady state model similar to that expected during the operations phase of the project. Notable activities include a simulated “slew and expose” sequence that includes moving the optical components, a settling time to account for the dynamical environment when on the telescope, and then taking an actual sequence of images with the ComCam. Another critical effort is to verify the performance of the camera refrigeration system, and testing the operational aspects of running such a system on a moving telescope in 2022. Here we present the status of the interface verification and the planned sequence of activities culminating with on-sky performance testing during the early-commissioning phase.

GNIRS (Gemini Near-InfraRed Spectrograph) is a multi-function spectrograph at Gemini North telescope offering four observational modes in the spectral range of 0.8 to 5.4 µm. It provides 2-pixel spectral resolutions from 1,200 up to 18,0000 and has single disperser and cross-disperser modes yielding simultaneous spectral bandwidths from 40 nm to 1,650 nm. GNIRS presented three existing modes: long-slit (50-100" slit), cross-dispersed (5-7" slit) and low resolution (LR) Integral Field Unit (IFU) (3.15" x 4.80") and it is now being upgraded with a fourth mode allowing high resolution (HR) IFU spectroscopy using an image slicer optimised for fully adaptively corrected images over a field of view of 2.25 arcsec² (1.80" x 1.25") covered by 25 slices of 410 µm width offering a spatial sampling of 0.05 x 0.05 arscec2 with a diffraction limited optical quality. The proposed layout meets specifications and some challenging design constraints: it shall be contained within the same envelope defined by the LR image slicer (0.1 x 0.2 x 0.1 m3 ), the input and output focal-ratios of both image slicers shall be the same and at exact positions but providing different anamorphic magnifications and preserving the optical quality. The length of the generated slit will be similar to the length of the slit in long-slit mode to maximise detector use and avoid vignetting. This communication presents the optical design and performance of the high resolution image slicer compliant with all specifications and constraints and it shows some design adaptations adopted in order to facilitate its manufacturing in metal at Durham University.

Commissioning results, on-sky performance and first operations of the Javalambre Panoramic Camera (JPCam) are presented in this paper. JPCam is a 1.2 Gpixel camera deployed on the 2.6m, large field-of-vie Javalambre Survey Telescope (JST250) at the Observatorio Astrof´ısico de Javalambre. JPCam has been conceived to perform J-PAS, a photometric survey of several thousand square degrees of the northern sky in 56 optical bands, 54 of them narrow-band filters (145 ˚A FWHM), contiguous and equi-spaced between 370 and 920nm, producing a low resolution photo-spectrum of every pixel of the observed sky, hence promising crucial breakthroughs in Cosmology and galaxy formation and evolution. JPCam has been designed to maximize field-of-view and wavelength coverage while guaranteeing a high image quality over the entire focal plane. To this aim, JPCam is equipped with a mosaic of 14 9.2k x 9.2k, 10µm pixel, low noise detectors from Teledyne-E2V, providing a FoV of 4.1 square degrees with a plate scale of 0.2267′′/pix. In full frame mode, camera electronics allows read times of 10.9s at 633kHz read frequency (16.4s at 400kHz) with a readout noise of 5.5e− (4.3e−). Its filter unit admits 5 filter trays, each mounting 14 filters corresponding to the 14 CCDs of the mosaic and allowing all the J-PAS filters to be permanently installed. To fully optimize image quality, position of JST250 secondary mirror and JPCam focal plane are maintained optically aligned by means of two hexapod systems. To perform this task, JPCam includes 12 auxiliary detectors, 4 for autoguiding and 8 for image quality control through wavefront sensing.

The Keck Wide Field Imager (KWFI) is a 1-degree field of view imager optimized to take advantage of the superb UV performance of the W.M. Keck Observatory (WMKO) located atop Mauna Kea in Hawaii. The project is an international collaboration between Swinburne University, ANU Macquarie University, Caltech, UC Observatories, and W.M Keck Observatory. KWFI is an all-fused silica 4-lens element corrector that operates over u,g,r,i, and z photometric bands from 300 – 1000 nm where the design achieves 0.5” 80% encircled energy diameter rms over the FOV within each photometric band. The KWFI collaboration is completing an 18-month conceptual design phase and is preparing to issue the most critical, long-lead-time procurements to address the critical path to first-light operations, following a public/private fundraising model. Our technically paced schedule, driven by corrector lens figuring, is expected to culminate in KWFI First Light in Summer 2027. We report here on the instrument concept and the progress towards a significant new capability for the WMKO.

SOXS (Son Of X-Shooter) is a single object spectrograph offering a simultaneous spectral coverage from U- to H-band, built by an international consortium for the 3.58-m ESO New Technology Telescope at the La Silla Observatory. It is designed to observe all kind of transients and variable sources discovered by different surveys with a highly flexible schedule maintained by the consortium, based on the Target of Opportunity concept. SOXS is going to be a fundamental spectroscopic partner for any kind of imaging survey, becoming one of the premier transient follow-up instruments in the Southern hemisphere. This paper gives an updated status of the project, when the instrument is in the advanced phase of integration and testing in Europe, prior to the activities in Chile.

The Wide-Field Infrared Transient Explorer (WINTER) is a new infrared time-domain survey instrument which will be deployed on a dedicated 1 meter robotic telescope at Palomar Observatory. WINTER will perform a seeing-limited time domain survey of the infrared (IR) sky, with a particular emphasis on identifying r-process material in binary neutron star (BNS) merger remnants detected by LIGO. As a dedicated observatory for real-time detection and rapid follow-up of infrared transient events, WINTER represents a new capability for multi-messenger astrophysics. We present the status of the WINTER instrument, including laboratory characterization and initial results from commissioning at its robotic observatory.

IceCube-Gen2 is a planned extension to the existing IceCube Neutrino Observatory currently operating at the South Pole. IceCube-Gen2 will provide an order of magnitude increase in the detection rate of cosmic neutrinos by deploying ∼10,000 novel sensors deep in the glacial ice. The IceCube-Gen2 sensor comprises up to eighteen photomultiplier tubes (PMTs) read out with custom electronics. The PMTs are mounted inside a borosilicate glass pressure vessel and optically coupled via “gel pads” to increase the probability of photon capture. The use of multiple PMTs provides coverage in every direction, aiding in event localization and reconstruction. The tight constraints on the in-ice borehole size, coupled with power constraints for instrumentation at the South Pole, presents several design challenges. Prototypes of the IceCube-Gen2 optical module are currently under development, and several will be deployed as part of the IceCube Upgrade. In this contribution, we will provide an overview of IceCube-Gen2 with a specific focus on the optical module currently under development.

The Transneptunian Automated Occultation Survey (TAOS II) is a three robotic telescope project to detect stellar occultation events generated by TransNeptunian objects (TNOs). TAOS II aims to monitor about 10000 stars simultaneously at 20Hz to generate a significant event rate. The TAOS II cameras are designed to cover the 1.7 degree diameter field of view of the 1.3m telescopes with a mosaic of ten 4.5k × 2k Teledyne e2v CIS 113 CMOS sensors. The CIS 113 has a back-illuminated thinned structure to provide similar performance to that of back-thinned CCDs. The CIS 113 device has 16 micron pixels with 8 outputs, with a plate scale about 0.63”/pixel. With the freedom of direct row and column addressing, star boxes with sizes of 8 × 8 pixels in each sensor can be sampled at 20 Hz or higher with a pixel rate of 1M pixel/sec per channel. The sensors, mounted on a single Invar plate, are cooled to an operating temperature of about 200K by a cryogenic cooler. The surfaces of the sensors were mounted to be within 30 microns to maintain a flat focal plane. The gap between two sensors is about 0.5mm. The control electronics consist of an analog part and a Xilinx FPGA based digital circuit. One FPGA controls and processes the signal from each CIS 113 chip. Two large PCBs were used to fanout signals from the 10 CMOS devices through the vacuum chamber wall. A synchronization circuit receives a pulse from the control center to ensure the timing accuracy of exposures of the three cameras is within 1 ms.

The polarimetric zero-level accuracy of spectropolarimetric measurements with ground-based solar telescopes usually suffers from systematic telescopic and instrumental effects which are difficult to model, and therefore, cannot be easily removed during post-measurement data reduction. Here, a novel measurement method to enhance the zero-level accuracy to an unprecedented level of such compromised measurements is presented. The method is comprised of adding a slow polarization modulation (< 1 Hz) before any polarizing component of the telescope to a high-sensitivity polarimeter with fast modulation (> 1 kHz). This additional slow modulation significantly mitigates systematic instrumental polarization signals induced by the telescope and post-focus instruments such as polarimetric offsets or cross-talk between polarization states. We present the results and limitations learned from implementing the method at the 45 cm Gregory-Coudé telescope at IRSOL, Locarno. The slow modulation is performed with a low-cost zero-order retarder film mounted in front of the telescope and is combined with the fast modulating Z¨urich IMaging POLarimeter (ZIMPOL). We find that the ground zero of polarization normalized to the intensity is determined within a few 10⁻⁵ . This level is consistently achieved over a wide wavelength range in the visible. An improvement of up to a few orders of magnitude for cases where the polarization offset induced by the telescope is as high as 10⁻² is achieved. This measurement technique allows for enhancing the zero-level accuracy of solar polarimetry, which is crucial for scattering polarization measurements and their theoretical interpretations.

For more than ten years, the GREGOR Infrared Spectrograph (GRIS) has been the main spectropolarimeter on the GREGOR telescope since its inauguration in 2012. The instrument mainly performs polarimetric observations of the wavelength regions at 1083 and 1565 nm, with high scientific potential. There, observers can find spectral lines that provide information on the atmospheric parameters over a vast range of atmospheric layers and with high sensitivity to the magnetic field. Due to the high demand for GRIS and the versatility of the GREGOR environment, we decided to upgrade the system once more, allowing it to become one of the instruments with the highest potential in any ground-based solar observatory. This time, the upgrades add two spectral channels for performing multi-wavelength observations, either in long-slit or IFU mode.

The EXoplanet Climate Infrared TElescope (EXCITE) is a 0.5 meter near-infrared spectrograph that will fly from a high altitude balloon platform. EXCITE is designed to perform phase-resolved spectroscopy – continuous spectroscopic observations of a planet’s entire orbit about its host star – of transiting hot Jupiter-type exoplanets. With spectral coverage from 0.8 – 4 um, EXCITE will measure the peak of a target’s spectral energy distribution and the spectral signatures of many hydrogen and carbon-containing molecules. Phase curve observations are highly resource intensive, especially for shared-use facilities, and they require exceptional photometric stability that is difficult to achieve, even from space. In this work, we introduce the EXCITE experiment and explain how it will solve both these problems. We discuss its sensitivity and stability, then provide an update on its current status as we work toward a 2024 long duration science flight.

The Coronal Magnetograph - CorMag - experiment aims at studying the magnetic field topology of the solar corona. The direction of the coronal magnetic field vector would be derived from narrow-wavelength bandpass observations of the linearly polarized FeXIV line-emission (530.3 nm), interpreted through the "saturated" Hanle effect. CorMag will be a medium-duration, high-altitude balloon payload of the European Union-funded HEMERA Program. CorMag is an internally-occulted coronagraph whose design was derived from the externally-occulted, formation-flying ASPIICS coronagraph of the PROBA-3 ESA solar mission. The configuration for this mission will be illustrated, together with the expected polarization sensitivity. This mission is a demonstrator for future space-based coronagraphs with the capability of visible-light and infrared polarization measurements for coronal magnetic field diagnostics.

The Dark Energy Spectroscopic Instrument (DESI) on the Mayall 4-m telescope has begun an ambitious survey of spectroscopic measurements of 40 million galaxies and quasars over an area of 14,000 deg2 . DESI is a wide field, multi-object, fiber-fed spectrograph, operating in the wavelength range of 360 - 980 nm. In this paper we present an overview of the DESI instrument focusing on key components including the prime-focus corrector, the focal plane with 5,020 remotely controlled fiber positioners, the procedures to position the fibers on selected targets and the spectrograph system. We then discuss the performance of the instrument during the first year of the DESI survey.

The TAIPAN instrument is installed on the UK Schmidt Telescope and has undergone 5 years of commissioning and verification. It utilizes the Starbug fibre positioning technology and is a proof-of-concept design for future Starbug-based instrumentation. The installation and commissioning of this new technology has provided opportunities to understand the Starbugs in detail. Science verification began in 2021 and has demonstrated the sub-10 minute configuration time, efficiency of small field ‘tweaks’ to correct for atmospheric refraction, and positioning accuracy of the Starbugs. Lessons learned from the commissioning of TAIPAN will directly impact future projects in which the Starbug technology is proposed, such as MANIFEST and FOBOS.

PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is now being tested on the telescope. The instrument is equipped with very wide (1.3 degrees in diameter) field of view on the Subaru’s prime focus, high multiplexity by 2394 reconfigurable fibers, and wide waveband spectrograph that covers from 380nm to 1260nm simultaneously in one exposure. Currently engineering observations are ongoing with Prime Focus Instrument (PFI), Metrology Camera System (MCS), the first spectrpgraph module (SM1) with visible cameras and the first fiber cable providing optical link between PFI and SM1. Among the rest of the hardware, the second fiber cable has been already installed on the telescope and in the dome building since April 2022, and the two others were also delivered in June 2022. The integration and test of next SMs including near-infrared cameras are ongoing for timely deliveries. The progress in the software development is also worth noting. The instrument control software delivered with the subsystems is being well integrated with its system-level layer, the telescope system, observation planning software and associated databases. The data reduction pipelines are also rapidly progressing especially since sky spectra started being taken in early 2021 using Subaru Nigh Sky Spectrograph (SuNSS), and more recently using PFI during the engineering observations. In parallel to these instrumentation activities, the PFS science team in the collaboration is timely formulating a plan of large-sky survey observation to be proposed and conducted as a Subaru Strategic Program (SSP) from 2024. In this article, we report these recent progresses, ongoing developments and future perspectives of the PFS instrumentation.

We describe the on-sky performance of the robotic Focal Plane System (FPS) units that replace the fiber plug-plate systems at the Sloan and duPont telescopes for the SDSS-V survey. The first FPS was arrived at Apache Point in December 2021, and the second unit will be delivered to Las Campanas in spring 2022. Each FPS carries 500 zonal fiber positioners carrying three fibers: two science fibers for the BOSS and APOGEE spectrographs and a back-illuminated metrology fiber. The FPS enables the SDSS-V Milky Way and Black Hole Mapper surveys that will begin survey operations in 2022.

The Multi Object Optical and Near-infrared Spectrograph (MOONS) instrument is the next generation multi-object spectrograph for the Very Large Telescope (VLT). The instrument combines the high multiplexing capability offered by 1000 optical fibres deployed by individual robotic positioners with a novel spectrograph able to provide both low- and high-resolution spectroscopy simultaneously across the wavelength range 0.64μm - 1.8μm. Powered by the collecting area of the 8-m VLT, MOONS will provide the astronomical community with a world-leading facility able to serve a wide range of Galactic, Extragalactic and Cosmological studies. This paper provides an updated overview of the instrument and its construction progress, reporting on the ongoing integration phase.

The VIRUS2 instrument is a new fiber-fed multiplexed integral field spectrograph consisting of 6 units, each with 4 spectral channels, to provide large on-sky area coverage coupled with broad spectral coverage. VIRUS2 will be a new facility instrument on the McDonald Observatory 2.7 m Harlan J Smith Telescope with 2.33 arcminute field of view and 2.5 arcsecond sampling. The instrument employs a novel beam-switch module within the fiber feed to split the light into the 4 spectral channels covering 370-930 nm at R~2000, while achieving a very compact and highly stable instrument. The design of VIRUS2 emphasizes stability and careful calibration, with scrambling in the beam-switch module, compact spectrograph format, and tight thermal control. This is the first time such measures have been employed at moderate spectral resolution. In this paper, we provide an overview of the instrument and the build status of the 24 spectrographs, detector system, integral field units, and telescope interface. VIRUS2 is funded by NSF and deployment is planned in 2023.

4MOST is a new high-multiplex, wide-field spectroscopic survey facility under construction for ESO's 4m-VISTA telescope at Paranal, Chile. Its key specifications are: a large field of view of 4.4 square degrees, a high multiplex fibre positioner based on the tilting spine principle that positions 2436 science fibres in the focal surface of which 1624 fibres go to two low-resolution optical spectrographs (R = λ/Δλ ~ 6500) and 812 fibres transfer light to the high-resolution optical spectrograph (R ~ 20,000). Currently, almost all subsystems are completed and full testing in Europe will be finished in spring 2023, after which 4MOST will be shipped to Chile. An overview is given of instrument construction and capabilities, the planned science of the consortium and the recently selected community programmes, and the unique operational scheme of 4MOST.

The Magellan Infrared Multi-object Spectrograph (MIRMOS) is a near-infrared (NIR) spectrograph with both multi-object (MOS) and integral field unit (IFU) capabilities designed for the Magellan 6.5-meter telescopes. MIRMOS’s design is optimized for both faint-object spectroscopy, and with the insertion of a diffuser, for ultra-high-signal-to-noise transmission spectroscopy of exoplanet atmospheres. To maximize MIRMOS’s scientific returns, it has an instantaneous wavelength range from 0.89-2.4 µm with a spectral resolution >3, 400 in the Y, J, H, and K bands. The front end switches between a mechanical slit mask robot capable of deploying 92 slits over a 13′ × 3 ′ field, and an image slicer IFU with a wide field of 26′′ × 20′′. In this proceeding, we will describe the current state of the instrument, with a focus on its optical design.

The Many Instrument Fiber System (MANIFEST) is a facility fiber system for the Giant Magellan Telescope (GMT). MANIFEST will be capable of feeding current and upcoming GMT instruments light from the telescopes full 20-arcmin field of view. The MANIFEST concept uses “Starbugs” – self-motile fiber heads deployed on a glass plate. MANIFEST will enhance the capabilities of different optical and near-infrared spectrographs at the GMT by feeding fibres and providing simultaneous observations. We have so far developed 15 science cases for MANIFEST which are listed under five broad science themes. Many science cases from galactic surveys, nearby galaxy surveys, intergalactic medium tomography, and spatially resolved studies of distant universe are of interest. These science cases drive the instrument requirements, modes of observations, and operation conditions for MANIFEST. Defined from the science cases, MANIFEST offers nine different modes of observations including high multiplexing, multiple and high sensitivity integral-field spectroscopy, polarimetry, and near-infrared spectroscopy. We discuss in this paper the latest developments of GMT/MANIFEST.

Microwave Kinetic Inductance Detectors (MKIDs) are beginning to become more prominent in astronomical instrumentation, due to their sensitivity, low noise, high pixel count for superconducting detectors, and inherent energy and time resolving capability. The Kinetic Inductance Detector Spectrometer (KIDSpec) will take advantage of these features, KIDSpec is a medium resolution MKID spectrograph for the optical/near infrared. KIDSpec will contribute to many science areas particularly those involving short and/or faint observations. When short period binary systems are found, typical CCD detectors will struggle to characterise these systems due to the very short exposures required, causing errors as large as the estimated parameter itself. The KIDSpec Simulator (KSIM) has been developed to investigate how much KIDSpec could improve on this. KIDSpec was simulated on an ELT class telescope to find the extent of its potential, and it was found that KIDSpec could observe a mV ≈ 24 with an SNR of 5 for a 10s exposure at 1420 spectral resolution. This would mean that KIDSpec on an ELT class telescope could spectroscopically follow up on any LSST photometric discoveries of LISA verification sources.

Following the idea originally proposed during the ESO-Workshop The Very Large Telescope in 2030, the concept of a high resolution spectrograph for the VLT has been further explored, both for the science and technological aspects. Such an instrument will fill a gap in capabilities amongst the landscape of future instrumentation planned for the next decade. Its key characteristic will be high spectral resolution (R = 60000-80000) with multi-object (50-100) capabilities and, possibly, a stability that would provide high radial velocity precision (∼10m/s). In this work, we describe the science cases and driving science requirements for the instrument. Furthermore we will present some design solutions and technical options considered to meet these requirements.

MSE is a massively multiplexed spectroscopic survey facility that will replace the Canada-France-Hawaii-Telescope. This 11.25-m telescope, with its 1.5 square degrees field-of-view, will observe 4,332 astronomical targets in every pointing by using fibers to pick up the light at the prime focus w and transmitting it to banks of low/moderate (R=3,000/6,000) and high (R=30,000) resolution spectrographs. Piezo actuators position individual fibers in the field of view to enable simultaneous full field coverage for both resolution modes. A Calibration system ensures good quality and reliable raw data. This instrument suite, dedicated to large scale surveys, will enable MSE to collect a massive amount of data: equivalent to a full SDSS Legacy Survey every 7 weeks. Since 2018, MSE has made progress by refining the science cases, exploring design space for the instrumentation and understanding the limits of chosen telescope and instrument architecture to achieve the science cases. To improve performance and reduce risk, challenging conceptual designs for spectrographs have been reconsidered. As well, the science calibration plan and associated technical hardware system have been developed to a conceptual design level. This paper includes a discussion of the trades, design decisions and outstanding risks for the entire instrument suite with a focus on recent developments for the spectrographs and calibration system.

MSE/CFHT plan to develop an end-to-end Pathfinder or for the Maunakea Spectroscopic Explorer (MSE). The MSE Project office is developing a new massively multiplexed spectroscopic facility on the site of the existing CFHT. MSE has currently passed its externally vetted Conceptual Design Stage. It will be a minimum 11-meter aperture telescope feeding 4000-10,000 fibers mated to a battery of medium and high-resolution spectrographs in the visible and NIR. The goal of the Pathfinder will be to fast-track technology development for MSE by demonstrating on-sky the ability of the major components of MSE and the major software packages in parallel with producing an initial science product that can be shared with the community. Among the primary science goals of the Pathfinder are time-domain astrophysics, specifically spectroscopic follow-up of transients identified by facilities such as Rubin Observatory and Zwicky Transient Factory to optimize their identification and classification; galactic archeology; and the spectroscopy of stars for stellar abundance studies and stellar evolution studies. The end-to-end Pathfinder will be a multi-object spectrograph fed at prime focus from the Canada France Hawaii telescope. It will utilize the same MSE spectrograph design with a multiplexing of ~800-1400 fibers using the same fiber positioner technology as MSE. The Pathfinder will prototype the software architecture for MSE including, scheduling; targeting; data reduction and analysis; and data management, archiving and database manipulation.

The Gemini High-Resolution Optical SpecTrograph (GHOST) instrument is the next generation high resolution spectrograph for the Gemini telescope. The GHOST instrument was developed for the Gemini telescope as a collaboration between Australian Astronomical Optics (AAO) at Macquarie University, the Herzberg Astronomy and Astrophysics (HAA) in Canada and the Australian National University (ANU). The instrument is a fiber fed spectrograph with R<50,000 in two-object mode and R<75,000 in single object mode. The bench spectrograph was integrated at Gemini South from April to June 2022. This paper presents the final integration and alignment of the spectrograph at Gemini South and the measured spectrograph performance at the telescope.

The Gemini High Resolution Optical Spectrograph (GHOST) is the next generation high resolution spectrograph for the Gemini South Observatory, and this has recently been commissioned in May 2021. In a single exposure, it can obtain the full optical spectrum from blueward of 360nm to beyond 1 micron. Two modes of operation mean that either one object can be observed at R~80000, or two objects can be observed at R~55000. First light results have tested all aspects of the scientific performance of GHOST from the science user perspective, including a range of aquisition procedures and its two spectral resolution modes. On-sky observations of scientific and library targets reveal GHOST to be the most sensitive spectrograph across the full optical range of any of the 8-10m class spectrographs currently in operation. This paper presents a full discussion of the commissioning process, tests, on-sky performance and first science observations.

CRIRES⁺ extended the capabilities of CRIRES, the CRyogenic InfraRed Echelle Spectrograph. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 μm cut-off wavelength replaced the existing detectors. Amongst many other improvements a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remote from Europe due to the pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of this development and presents on sky results.

MAROON-X is a fiber-fed, optical EPRV spectrograph at the 8-m Gemini North Telescope on Mauna Kea, Hawai’i. MAROON-X was commissioned as a visiting instrument in December 2019 and is in regular use since May 2020. Originally designed for RV observations of M-dwarfs, the instrument is used for a broad range of exoplanet and stellar science cases and has transitioned to be the second-most requested instrument on Gemini North over a number of semesters. We report here on the first two years of operations and radial velocity observations. MAROON-X regularly achieves sub-m/s RV performance on sky with a short-term instrumental noise floor at the 30 cm/s level. We will discuss various technical aspects in achieving this level of precision and how to further improve long-term performance

NIRPS is an infrared precision Radial Velocity (pRV) spectrograph covering the range 950 nm-1800 nm. NIRPS uses a high-order Adaptive Optics (AO) system to couple the starlight into a fiber corresponding to 0.4" on the sky as efficiently or better than HARPS or ESPRESSO couple the light in a 1.0" fiber. This allows the spectrograph to be very compact, more thermally stable, and less costly. Using a custom tan(θ)=4 dispersion grating in combination with a start-of-the-art Hawaii4RG detector makes NIRPS very efficient with complete coverage of the YJH bands at just under 100 000 resolution. On the ESO 3.6-m telescope, NIRPS and HARPS are working simultaneously on the same target, building a single powerful high-resolution, high-fidelity spectrograph covering the 0.37-1.8 µm domain. NIRPS will complement HARPS in validating Earth-like planets found around G and K-type stars whose signal is at the same order of magnitude than the stellar noise. While the telescope-side AO system was installed on the ESO 3.6-m telescope in 2019, the infrared cryogenic spectrograph has been integrated at the telescope in early-2022 and has had first light in June 2022. Results from the first light mission show that NIRPS performs very nicely, that the AO system works up to magnitude I=14.5, that the transmission matches requirements and that the RV stability of 1 m/s is within reach While performance assessment is ongoing, NIRPS has demonstrated on-sky m/s-level stability over a night and <3 m/s level over two weeks. Limitations on the RV performances arise from modal noise that can be mitigated through better scrambling strategies. Better performances are also expected following a grating upgrade in July 2022; these will be tested in late-2022.

A near-IR high-resolution, R≈80000 spectrometer has been developed at IPAG to directly characterize the atmosphere of exoplanets using adaptive optics (AO) assisted telescopes, and a single-mode fiber-injection unit. A first technical test with the 200’ Hale telescope at Palomar Observatory occurred in March 2022 using the PALM3000 AO system offered by this telescope. Observations have also been made at the same time with the PARVI spectrometer so that a direct comparison can be made between the two instruments. This spectrometer uses a virtually imaged phased array (VIPA) instead of an echelle grating, resulting in a very compact optical layout that fits in a 0.25m³ cryostat. Using a quarter of an H2RG detector, the spectrometer analyses the middle part of the H-band, from 1.57 to 1.7 microns for 2 sources whose light is transferred from the telescope to the spectrometer using single-mode fibers. By design, the transmission of the spectrometer is expected to be 40-50%, which is 2-3 times higher than the transmission of current high-resolution spectrometers such as CRIRES+ and NIRSPEC. A damaged cross-disperser limited it to 21%, however. A replacement grating with a correct, twice as high efficiency has been procured after the on-sky demonstration. In addition to recalling the main specifications of the VIPA spectrometer, this paper presents the control software, the calibration process, and the reduction pipeline that have been developed for the instrument. It also presents the results of the on-sky technical test with the Hale telescope, as well as measurements of the effective resolution and transmission, along with a comparison of a spectrum of the sun obtained with the spectrometer with the BASS2000 reference spectrum. Planned modifications are also discussed. That includes the integration of a new dedicated H2RG detector, and of K-band optics.

e report a latest generation of the laser frequency comb (LFC) for astronomy. The new features include all fiber coupled, alignment-free filter cavities; specially designed photonic crystal fiber for spectral broadening; reflective spectral flattening systems. All the features ensure the long-term stability of the whole LFC system. The LFC is designed to operate in two modes. The visible mode generates a supercontinuum from 445 nm to 870 nm, that covers 100 % spectral range of the Keck Planet Finder (KPF) spectrograph. The near-infrared mode offers a flat-top supercontinuum from 915 nm to 1450 nm, is prepared as a calibration source of the short-wavelength part of a near infrared (NIR) spectrograph

Using photonic devices, we developed a new approach to traditional spectroscopy where the spectral cross-correlation with a template spectrum can be done entirely on-device. By creating photonic devices with a carefully designed, modulated transmission spectrum, the cross-correlation can be carried out optically without requiring any dispersion, vastly simplifying the instrument and reducing its cost. The measured correlation lag can be used for detecting atomic/molecular species within and determining the radial velocity of a particular astrophysical object. We present an overview of two design approaches that are currently being developed that use different photonic platforms: silicon and fibre-based photonics. The silicon photonic approach utilizes ring resonators that can be thermo-optically modulated to carry out the cross-correlation. The fibre approach uses customized fibre Bragg gratings (FBGs) with transmission spectra that can be strain-modulated. Both approaches have been able to detect molecular gas in a lab setting, and we are now in the process of on-sky testing. Lastly, we discuss the future for these types of devices as their simplicity opens up the possibility of developing low-cost, purpose-built multi-object or integral field spectroscopic instruments that could make significant contributions to scientific programs requiring stellar RV measurements and exoplanet detections.

MARVEL is a novel facility targeting extreme-precision radial velocity observations. Dedicated to confirming and characterizing planet candidates from the TESS and future PLATO missions, MARVEL will provide mass measurements of a multitude of exoplanets. The MARVEL instrument consists of an array of four 80-cm robotic telescopes, linked to one state-of-the-art high-resolution echelle spectrograph, through a set of optical fibers. MARVEL can observe the radial velocities of four different stars simultaneously or, alternatively, combine the flux from four telescopes pointing to a single faint target in one spectrum. It will be installed next to the Mercator Telescope at the Roque De Los Muchachos Observatory on La Palma (SPAIN). MARVEL is designed and built by a KU Leuven (Belgium) led consortium, with contributions from Australia, Austria, Denmark, Germany, Spain, Sweden and the UK.

In this presentation, we detail the optical fiber-feed system for the new ultra-precise radial velocity spectrometer – NEID, which is an ultrastable instrument spanning a wavelength range of 380 to 930 nm. We discuss the various subsystems of the optical fiber-feed, including the process of design, assembly and testing of each component to ensure that it meets the strict requirements to achieve the instrumental precision goal for NEID.

This paper describes the deployment of the GMT-Consortium Large Earth Finder (G-CLEF) at the Clay telescope, one of the two Magellan telescopes, in late 2025, moving to the GMT in 2030. G-CLEF is a fiber-fed, ultra-high stability optical band echelle spectrograph designed for extremely precise stellar radial velocity measurement. On the Magellan Clay telescope, G-CLEF will take spectra with resolution up to ~300,000, fully resolving molecular spectral features and opening totally new discovery space for exoplanet atmosphere composition studies. G@M will also be coupled to the Magellan extreme adaptive optics facility, MagAO-X which will allow it to spatially resolve several exoplanets from their host stars. We provide a system description of the G@M instrument as it will be configured at Magellan. A top-level review of optomechanics, electronics and control systems follows, as well as a description of several risk-reduction exercises the team has undertaken.

The Potsdam Arrayed Waveguide Spectrograph (PAWS) is built upon an integrated photonic spectrograph designed for astronomy. Similar to integrated optic beam combiners for interferometry, PAWS is intended to demonstrate on sky how a traditional bulk optics spectrograph with R = 15.000 in the H band can be miniaturized to fit on a chip. The integrated photonic spectrograph is based on second-generation Arrayed Waveguide Gratings (AWG) with unprecedented performance in terms of spectral resolution and throughput. The fibre-coupled AWG serves as a first dispersive element. The pre-dispersed light is fed into a free-space optical system located in a cryostat. Here the overlapping spectral orders are separated by cross-dispersion. The resulting echellogram is recorded by a Teledyne 2kx2k H2RG near-infrared array. Locally controlled constant cryogenic temperatures are required for the operation of the cryostat. This was achieved by fine-tuning and optimizing the original cryostat design using experimental data from multiple cryogenic cycles. These steps included the optimization of thermal interfaces, gold coating of the radiation shield, and an appropriate cooling sequence using the constraints of the allowed cooling rate for H2RG focal plane arrays. Using the readout electronics and GEIRS software provided by the Max Planck Institute for Astronomy (MPIA), frames of the H2RG were obtained, allowing performance calculations and dark pre-characterization of the system. For the optimum alignment of the optical system, the coefficient of thermal expansion (CTE) was measured with an interferometric set-up that recorded the spatial displacements of two reflecting optical elements within the cryostat during a cryogenic cycle. An appropriate strategy was developed to adjust the cryogenic cross dispersion optics inside the vacuum chamber to the AWG coupling optics outside the chamber.

iLocater is a near-infrared, extremely precise radial velocity (EPRV) spectrograph under construction for the dual 8.4 m diameter Large Binocular Telescope (LBT). The instrument will undertake precision radial velocity studies of Earth-like planets orbiting low-mass stars. Operating in the diffraction-limited regime, iLocater uses adaptive optics to efficiently inject starlight directly into single-mode fibers that illuminate a high spectral resolution (R=190,500 median), cryogenic, diffraction-limited spectrograph. To maximize performance, the spectrograph uses a new design strategy for EPRV instruments, combining intrinsically stable materials for its optomechanical fabrication with precision optical fabrication. This novel combination will enable unique EPRV capabilities for exoplanet and astrophysics studies of the solar neighborhood. We present the final optical and mechanical designs of the spectrograph system. Ensuring the as-built spectrograph achieves its designed spectral resolution and diffraction-limited performance has required careful control of the end-to-end system wavefront error (WFE) budget. We discuss the efforts undertaken to achieve this goal including minimizing residual WFE in the optical design, assessing diffraction grating WFE performance, optimizing material choices, and requiring precision optical design and fabrication. Our goal is to deliver diffraction-limited performance across the full spectral format, which, combined with intrinsic thermal stability requirements for EPRV science, has driven the selection of silicon optics and Invar optomechanics. The system performance is further optimized using precision (sub-mK) thermal control. This set of design features will allow iLocater to achieve sub-m/s radial velocity precision in the near-infrared, and to serve as the first optimized diffraction-limited spectrograph for EPRV science

RISTRETTO is a visible high-resolution spectrograph fed by an extreme adaptive optics (AO) system, to be proposed as a visitor instrument on ESO VLT. The main science goal of RISTRETTO is the detection and atmospheric characterisation of exoplanets in reflected light, in particular the temperate rocky planet Proxima b. RISTRETTO will be able to measure albedos and detect atmospheric features in a number of exoplanets orbiting nearby stars for the first time. It will do so by combining a high-contrast AO system working at the diffraction limit of the telescope to a high-resolution spectrograph, via a 7-spaxel integral-field unit (IFU) feeding single-mode fibers. Further science cases for RISTRETTO include the study of accreting protoplanets such as PDS70b/c through spectrally-resolved H-alpha emission, and spatially-resolved studies of Solar System objects such as icy moons and the ice giants Uranus and Neptune. The project is in an advanced design phase for the spectrograph and IFU/fiber-link sub-systems, and a preliminary design phase for the AO front-end. Construction of the spectrograph and IFU/fiber-link will start early 2022. RISTRETTO is a pathfinder instrument in view of similar developments at the ELT, in particular the SCAO-IFU mode of ELT-HIRES and the future ELT-PCS instrument.

HISPEC (High-resolution Infrared Spectrograph for Exoplanet Characterization) is an infrared (0.95 to 2.46 microns) cross-dispersed, R=100,000 single-mode fiber-fed diffraction-limited echellette spectrograph for the Keck II telescope’s adaptive optics (AO) system. MODHIS (Multi-Objective Diffraction-limited High-resolution Infrared Spectrograph) shares similar specifications as HISPEC while being optimized for TMT’s first-light AO system NFIRAOS. Keck-HISPEC (2025) then TMT-MODHIS will provide increasingly compelling science capabilities from exoplanet atmosphere characterization through both transit and direct high-contrast spectroscopy, to detection and mass measurements through infrared precision radial velocity (RV). The science cases include the precise RV measurements of stars orbiting the Galactic Center, Solar System studies, and the chemodynamical history of nearby dwarf galaxies and the galactic halo.

SPHERE+ is a proposed upgrade of the SPHERE instrument at the VLT, which is intended to boost the current performances of detection and characterization for exoplanets and disks. SPHERE+ will also serve as a demonstrator for the future planet finder (PCS) of the European ELT. The main science drivers for SPHERE+ are 1/ to access the bulk of the young giant planet population down to the snow line (3 − 10 au), to bridge the gap with complementary techniques (radial velocity, astrometry); 2/ to observe fainter and redder targets in the youngest (1 − 10 Myr) associations compared to those observed with SPHERE to directly study the formation of giant planets in their birth environment; 3/ to improve the level of characterization of exoplanetary atmospheres by increasing the spectral resolution in order to break degeneracies in giant planet atmosphere models. Achieving these objectives requires to increase the bandwidth of the xAO system (from ~1 to 3 kHz) as well as the sensitivity in the infrared (2 to 3 mag). These features will be brought by a second stage AO system optimized in the infrared with a pyramid wavefront sensor. As a new science instrument, a medium resolution integral field spectrograph will provide a spectral resolution from 1000 to 5000 in the J and H bands. This paper gives an overview of the science drivers, requirements and key instrumental tradeoff that were done for SPHERE+ to reach the final selected baseline concept.

GPI is a facility instrument designed for the direct detection and characterization of young Jupiter mass exoplanets. GPI has helped establish that the occurrence rate of Jovian planets peaks near the snow line (~3 AU), and falls off toward larger separations. This motivates an upgrade of GPI to achieve deeper contrasts, especially at small inner working angles, to extend GPI’s operating range to fainter stars, and to broaden its scientific capabilities, all while leveraging its historical success. GPI was packed and shipped in 2022, and is undergoing a major science-driven upgrade. We present the status and purpose of the upgrades including an EMCCD-based pyramid wavefront sensor, broadband low spectral resolution prisms, new apodized-pupil Lyot coronagraph designs, upgrades of the calibration wavefront sensor and increased queue operability. We discuss the expected performance improvements and enhanced science capabilities to be made available in 2024.

We present the fifth incarnation of the Mid-Infrared Array Camera (MIRAC-5) instrument which will use a new GeoSnap (3 – 13 microns) detector. Advances in adaptive optics (AO) systems and detectors are enabling ground based mid-infrared systems capable of high spatial resolution and deep contrast. As one of the only 3 – 13 micron cameras used in tandem with AO, MIRAC-5 will be complementary to the James Webb Space Telescope (JWST) and capable of characterizing gas giant exoplanets and imaging forming protoplanets (helping to characterize their circumplanetary disks). We describe key features of the MIRAC-5 GeoSnap detector, a long-wave Mercury-Cadmium-Telluride (MCT) array produced by Teledyne Imaging Sensors (TIS), including its high quantum efficiency (> 65%), large well-depth, and low noise. We summarize MIRAC-5’s important capabilities, including prospects for obtaining the first continuum mid-infrared measurements for several gas giants and the first 10.2-10.8 micron NH3 detection in the atmosphere of the warm companion GJ 504b (Teff ~ 550 K) within 8 hours of observing time. Finally, we describe plans for future upgrades to MIRAC-5 such as adding a coronagraph. MIRAC5 will be commissioned on the MMT utilizing the new MAPS AO system in late 2022 with plans to move to Magellan with the MagAO system in the future.

The PLACID instrument is a novel high-contrast direct imaging facility that will come online on the Turkish 4-m DAG telescope in 2022. The project has just passed Final Design Review (FDR) in December 2021, with first light scheduled for the end of 2022. In practice, PLACID will be the world’s first ever “active coronagraph” facility, fielding a customized spatial light modulator (SLM) acting as a dynamically programmable coronagraph from H- to Ks-band. This will provide a wealth of interesting options to the observers. We hereby present the FDR base design of PLACID, and early laboratory and factory results illustrating the performance.

The Keck Planet Imager and Characterizer (KPIC) is a series of upgrades for the Keck II Adaptive Optics system and the NIRSPEC spectrograph to enable diffraction-limited, high-resolution (R>30,000) spectroscopy in the K and L bands. KPIC’s use of single-mode fibers provides a substantial reduction in sky background as well as an extremely stable line-spread function. In this paper we present the results of extensive system-level laboratory testing and characterization of Phase II of the instrument and each of its modes. We also show early on-sky results from the first few months of commissioning with these upgrades along with the next steps for the instrument.

We describe the development status of the first-generation science instruments for the Giant Magellan Telescope (GMT). The first-generation suite includes two infrared and two visible light spectrographs that together will deliver from wide-band imaging to R~200,000 spectroscopy at wavelengths from 0.3 to 5 µm. All four instruments are designed for use with diffraction limited or ground-layer adaptive optics modes. G-CLEF, a visible light echelle designed for broad scientific use and for precision radial velocity measurements, is in fabrication. The other three (GMACS, a wide field multi-object spectrograph; GMTNIRS, a near- to thermal-infrared echelle spectrograph utilizing silicon immersion gratings; and GMTIFS, a near-infrared imager and integral field spectrograph) are in Preliminary Design. The first-generation suite also includes a robotic fiber-feed system called MANIFEST, which enables spectroscopy over the 20 arcmin field of view of the telescope with custom fibers for G-CLEF, GMACS, and GMTNIRS. An additional facility instrument, GMagAO-X, is being developed to provide high-contrast imaging at visible and near-infrared wavelengths and is in Preliminary Design. We also discuss the visible and infrared cameras (called ComCam and AOTC, respectively) that will be used for alignment, verification, and commissioning of the active and adaptive optics modes of the telescope and enable early science activities.

MICADO, a first light ELT instrument, will provide diffraction limited imaging, astrometry, high contrast imaging, and slit spectroscopy. It will achieve an unprecedented combination of sensitivity and resolution at near-infrared wavelengths using its own SCAO system as well as the LGS-MCAO module MAORY. This contribution describes MICADO at its Final Design Review, explaining how the instrument was developed to fulfil the science and technical requirements, as well as meet the operational and maintenance requirements. Some thoughts about the dramatic difference between ELT and VLT projects are presented, and what this might mean for future instrumentation.

HARMONI is the first light, adaptive optics assisted, integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope (ELT). A work-horse instrument, it provides the ELT’s diffraction limited spectroscopic capability across the near-infrared wavelength range. HARMONI will exploit the ELT’s unique combination of exquisite spatial resolution and enormous collecting area, enabling transformational science. The design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, and provide a summary of the instrument’s design. We also include recent changes to the project, both technical and programmatic, that have resulted from red-flag actions. Finally, we outline some of the simulated HARMONI observations currently being analyzed.

The Mid-Infrared ELT Imager and Spectrograph (METIS) is one of the first generation science instruments on ESO's 39m Extremely Large Telescope (ELT). METIS will provide diffraction-limited imaging and medium resolution slit-spectroscopy from 3 – 13 microns (L, M, and N bands), as well as high resolution (R ~ 100,000) integral field spectroscopy from 2.9 – 5.3 microns. After passing its preliminary design review (PDR) in May 2019, and the final design review (FDR) of its optical system in June 2021, METIS is now preparing for the FDR of its entire system in the fall of 2022, while the procurements of many optical components have already started. First light at the telescope is expected in 2028, after a comprehensive assembly integration and test phase. We describe the conceptual setup of METIS, its key functional components, and the resulting observing modes. Last but not least, we present the expected sensitivity, adaptive optics, and high contrast imaging performance.

MOSAIC is the Multi-Object Spectrograph for the ESO Extremely Large Telescope, approved to enter Phase B beginning 2022. It is conceived as a multi- purpose instrument covering the Visible and Near Infrared bandwidth (0.45 –1.8 μm) with two observing modes: spatially resolved spectroscopy with 8 integral field units; and the simultaneous observation of 200 objects in the VIS and NIR in unresolved spectroscopy. We present an overview of the main MOSAIC science drivers and the actual baseline design for the instrument. The prototyping and developments undertaken by the consortium to evaluate the feasibility of the project are also discussed.

We present the current design of WFOS, a wide-field UV/optical (0.31-1.0 µm) imaging spectrograph planned for first-light on the TMT International Observatory 30 m telescope. WFOS is optimized for high sensitivity across the entire optical waveband for low-to-moderate resolution (R ∼ 1500-5000) long-slit and multi-slit spectroscopy of very faint targets over a contiguous field of view of 8′ .3×3 ′ .0 at the f/15 Nasmyth focus of TMT. A key design goal for WFOS is stability and repeatability in all observing modes, made possible by its gravity-invariant opto-mechanical structure, with a vertical rotation axis and all reconfigurable components moving only in planes defined by tiered optical benches parallel to the Nasmyth platform. WFOS’s optics include a linear ADC correcting a 9′ diameter field, including both the science FoV and 4 patrolling acquisition, guiding, and wavefront sensing camera systems; a novel 2-mirror reflective collimator allowing the science FoV to be centered on the telescope optical axis; a dichroic beamsplitter dividing the collimated beam into 2 wavelength-optimized spectrometer channels (blue: 0.31-0.56 µm; red: 0.54-1.04 µm); selectable transmissive dispersers (VPH and/or VBG) with remotely configurable grating tilt (angle of incidence) and camera articulation that enable optimization of diffraction efficiency and wavelength coverage in each channel; all-refractive, wavelength-optimized f/2 spectrograph cameras, and UV/blue and red-optimized detector systems. The predicted instrumental through put of WFOS for spectroscopy averages > 56% over the full 0.31-1 µm range, from the ADC to the detector. When combined with the 30 m TMT aperture, WFOS will realize a factor of ∼20 gain in sensitivity compared to the current state of the art on 8-10 m-class telescopes.

The first generation of ELT instruments includes an optical-infrared high resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs (UBV, RIZ, YJH) providing a spectral resolution of ∼100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 µm with the goal of extending it to 0.35-2.4 µm with the addition of a K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre-feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Its modularity will ensure that ANDES can be placed entirely on the ELT Nasmyth platform, if enough mass and volume is available, or partly in the Coudé room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of more than 200 scientists and engineers which represent the majority of the scientific and technical expertise in the field among ESO member states.

We will provide a summary review of the capabilities and the overall status of the Planetary Systems Instrument (PSI), a second-generation instrumentation suite for the TMT. The PSI concept follows a modular design and operates from optical to thermal infrared wavelengths, combining high-order AO correction with coronagraphs, imaging and low-resolution integral-field spectroscopy, and fiber-coupled spectrometers. We will provide an overview of recent development, including description of the key requirements, performance simulation, optical front-end AO design concept, and precursor instrumentation and technique status.

SUNRISE III is an international balloon-borne solar observatory with a 1m diameter telescope and is scheduled to fly in 2022. The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is being developed as a focal plane instrument for SUNRISE III, which will perform multi-wavelength spectropolarimetric observations with high spatial and spectral resolution (0.21 arcsec and 2 × 10⁵ ). The SCIP is a quasi-Littrow-type spectropolarimeter mainly composed of an echelle grating and two aspheric mirrors. A polarizing beam splitter is used for simultaneous measurement of p- and s-polarization. To ensure the imaging performance, correct the image rotation and shift, and avoid vignetting, we performed the optical alignment. The optical elements were firstly aligned by shimming with mechanical precision of 1-20 arcmin for tilt and 0.1-0.3 mm for shift using a coordinate measuring machine. After the mechanical alignment, we constructed the telecentric feed optical system to mimic the light distribution instrument of SUNRISE III telescope, which is called Image Stabilization and Light Distribution (ISLiD). To reduce the astigmatism, we measured the contrast of the spot in the spatial direction and the width of the spot in the wavelength direction and adjusted the two aspheric mirrors. For the correction of the image rotation, the Z-tilt of grating was adjusted with a wavelength tunable laser by evaluating the tilt of the slit image in the wavelength direction. The wavelength position in cameras was adjusted with tunable lasers and sunlight. We evaluated the modulation transfer function of SCIP using a Ronchi ruling target with a white light source.

New Jersey Institute of Technology (NJIT) has built, and now operates the 1.6-meter Goode Solar Telescope (GST) at the Big Bear Solar Observatory (BBSO), which was the highest-resolution solar telescope built in the U.S. in a generation. GST observations have been put in a campaign mode to support the NASA Parker Solar Probe (PSP) mission during its perihelia in 2019, 2020, 2021 and 2022, by providing unique high-resolution observations and critically complementary information on the photosphere and chromosphere at the source regions of solar wind acceleration and heating of solar corona. This paper presents the acquisition, processing, and archiving of high-resolution imaging spectroscopy and polarimetry data generated with GST instruments, as well as the preliminary scientific results.

The EXoplanet Climate Infrared TElescope (EXCITE) experiment is a balloon-borne, purpose-designed mission to measure spectroscopic phase curves of short-period extrasolar giant planets (EGPs, or “hot Jupiters”). Here, we present EXCITE’s principal science instrument: a high-throughput, single-object spectrograph operating in the 0.8-2.5 µm and 2.5-4.0 µm bands with R≥50. Our compact design achieves diffraction-limited, on-axis performance with just three powered optics: two off-axis parabolic mirrors and a CaF2 prism. We discuss the optical and mechanical design, the expected optical performance of the spectrograph, and summarize the tolerances needed to achieve that performance. We also discuss plans for establishing alignment of the optics and verifying the optical performance.

The IBIS 2.0 Interferometric BIdimensional Spectrometer 2.0 instrument combines two tunable Fabry-P´erot interferometers, narrowband interference filters, a polarimetric unit, fast cameras, and a proper Instrument Control System to perform high-resolution solar spectropolarimetric observations at high cadence with short exposures. A previous version of the instrument, named IBIS, operated at the Dunn Solar Telescope (DST) of the National Solar Observatory (NSO) from 2003 to 2019. IBIS 2.0 is planned to enter operations over the spectral range 580-860 nm at the Teide Observatory in 2023. In this paper we describe the final optical layout adopted for IBIS 2.0 along with its polarimetric unit, which is realized with two Liquid Crystals Variable Retarders and a Wollaston prism acting as a Polarizing Beam Splitter. We also present the final design of the Instrument Control System, the expected performances of the IBIS 2.0 instrument, and the planned sequence of operations.

The Sunrise Chromospheric Infrared spectroPolarimter (SCIP) is an instrument for the third flight of the SUNRISE balloon-borne solar observatory planned for 2022. To verify the high spatial and spectral resolutions required in the balloon flight, the SCIP optical unit was subjected to a thermal-vacuum test in which the SCIP optical unit was installed in a vacuum chamber and was exposed to the thermal environment expected in the flight. We verified the heater control performance and the temperature distribution in the SCIP optical unit and confirmed the optical performance by injecting the laser and white light through a vacuum window.

SUNRISE III mission is a one-meter aperture telescope onboard a balloon within NASA Long Duration Balloon Program. Three post-focus instruments are used for studying the Sun’s dynamics and magnetism, among which the Tunable Magnetograph (TuMag) is a tunable imaging spectropolarimeter. TuMag is a diffraction-limited imager, a high sensitivity polarimeter (< 10-3 ), and a high-resolution spectrometer ( ~ 65 mÅ). It will be able to study solar magnetic fields at high spatial resolution (~100 km on the solar surface). It will make images of the solar surface magnetic field after measuring the state of polarization of light within three selected spectral lines: the Fe I lines at 525.02 nm and 525.06 nm, and the Mg I b2 line at 517.27 nm. It will be sensitive to the solar vector magnetic fields and line-of-sight velocities, in the photospheric and chromospheric layers. TuMag will be the first solar magnetograph onboard an aerospace platform with the capability of tuning the solar line to be observed. In this paper the TuMag end-to-end tests carried out during the verification phase are described. These tests are performed to characterize and calibrate the instrument. Specifically, they determine the polarimetric and spectroscopic performances of the instrument as well as the image quality. The availability of a singular facility, an ISO6 clean room with a coelostat on the building roof, allowed the use of solar light during the verification campaign. This was key to a complete instrument verification due to the unique spectroscopic and polarimetric characteristics of solar light.

The Tunable Magnetograph (TuMag) is one of the three post-focus instruments onboard the SUNRISE III mission. It consists of a one-meter aperture telescope onboard a balloon within NASA Long Duration Balloon Program to study the solar dynamics. TuMag is a diffraction-limited imager, a high sensitivity polarimeter and a high resolution spectrometer. It will be able to study solar magnetic fields at high spatial resolution (~100km on the solar surface). It will make images of the solar surface magnetic field after measuring the state of polarization of light within three selected spectral lines: the Fe I lines at 525.02nm and 525.06nm, and the Mg I b2 line at 517.27nm. It will allow to be sensitive to physical quantities, and specifically to the magnetic fields, in the photospheric and chromospheric layers. TuMag will be the first solar magnetograph onboard an aerospace platform with the capability of tuning the solar line to be observed. TuMag consists of an Optical-Unit and an Electronic Unit to control it. The optical design is an optical relay of the telescope post-focal intermediate image where the light analysis is carried out in several stages. The polarization analysis is carried out with a polarization modulator based on Liquid Crystal Variable Retarders developed for the Solar Orbiter mission in operation currently. The spectral lines are scanned during the observation using a LiNbO3 etalon in double-pass configuration with a 65mÅ bandwidth. Additionally, to remove undesired orders of the Fabry-Perot interferometer, three narrow bandpass filters with a ~1.5 Å FWHM (Full Width at Half Maximum) are consecutively inserted in the optical path using a high precision and thermal controlled filter wheel. In this paper the optical, mechanical and thermal design of the TuMag optical unit is described as well as a brief summary of the results obtained during the manufacturing, assembling, integration and verification phases

The National Science Foundation Daniel K. Inouye Solar Telescope (DKIST) is a 4-m off-axis telescope that points directly at the sun. Pointing at the sun generates a tremendous amount of heat (approximately 12kW) which requires an innovative cooling method and thermal control to avoid damaging telescope equipment and the building. The heat stop is one component DKIST implemented as part of the thermal control system. The heat stop is located at the telescope’s prime focus and blocks most light from proceeding to the M2 mirror and subsequent optics with a five (5) arcmin field of view diameter. The surface temperatures of the heat stop are also maintained near ambient temperatures to minimize self-induced seeing and maintain high-quality images. The heat stop comprises of the following: a reflector and an absorber. Computational fluid dynamics (CFD) modeled the thermal performance of the current heat stop reflector and absorber design. Installed temperature sensors and historical data shall then determine the actual fluid thermal heat loads and rise in surface temperatures. The results shall verify the thermal performance of the heat stop. Future work includes investigating whether or not the heat stop contributes to any seeing that may be present in the instrumentation images.

The EXoplanet Climate Infrared TElescope (EXCITE) is an instrument dedicated to measuring spectroscopic phase curves of extrasolar giant planets. EXCITE will carry a moderate resolution near-infrared spectrograph and will fly on a long duration balloon mission. We give an overview of the mechanical and thermal design and development status of the EXCITE cryogenic receiver. Active cooling for the EXCITE cryostat is provided by two linear pulse-tube cryocoolers. We discuss cryocooler thermal performance, integration of the spectrometer and detector, and the mounting scheme that attaches the cryostat to the backplate of the telescope. To reject heat power from the cryocoolers, gravity-assisted copper-methanol thermosyphons will maintain cryocooler temperatures within 20 ◦C of ambient temperature during operation. We discuss the results of preliminary thermal modeling of the thermosyphons as well as performance testing of a prototype built for in-lab verification.

HARMONI is the first light visible and near-IR integral field spectrograph for the Extremely Large Telescope (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. The IFS Pre-Optics (IPO), sub-system under the responsibility of the Institute of Astrophysics of the Canary Islands (IAC), contains 30 opto-mechanical mounts working at cryogenic temperatures and are classified into three types depending on the mirror shape: [1] - Sprung kinematic mount for flat mirrors: By spring loading, the mirror is constrained radially against a Vee-groove. - Thermally compensated kinematic sprung mount for power mirrors: It is similar to the previous mount but the radial pads compensate mirror radial movement. - Bonded mount for toroidal mirrors: The mirror is bonded to a rear invar pad, which serves as an interface to the support. This work describes the designs developed for the opto-mechanical modules of the Instrument IPO in order to comply with the sub-system requirements. We also present the prototypes developed to prove some of the adopted concepts in the design.

We present the final design of the cryostat of the Mid-infrared ELT Imager and Spectrograph (METIS) instrument to be operated at ESO’s Extremely Large Telescope (ELT). The cryostat provides the cold optics of the instrument with the required cryo-vacuum environment. The radiation shields of the cryostat are cooled with liquid nitrogen and the cold optics is cooled via pulse-tube coolers down to temperatures between 35 K and 70K. The cold-warm interface is provided with G10 blades that build together with the top part of the cryostat vessel the structural interface to the cold optics, the warm support structure and the warm calibration source. The cryostat development is now complete and the instrument Final Design Review is scheduled for November 2022. We present in this paper the final design status, the key design considerations and the cooling concept.

HARMONI is the first light visible and near-IR integral field spectrograph for the Extremely Large Telescope (ELT). This instrument covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. The Pre-Optics (sub-system under the responsibility of the IAC) contains five mechanisms working at cryogenic temperatures. Three types of mechanisms are needed to provide full functionality: wheels (2), turrets (2) and shutter (1). The wheels and turrets, supported by a series of radial and axial bearings, are driven by stepper motors through a system of gears that provide mechanical reduction. In addition, the focal plane mask wheel has a detent system to improve repeatability to within +/- 2.5 microns. Finally, the shutter consists in two masks with three clover shape blades mounted on a stepper motors. The work describes the main IPO mechanisms requirements and the design developed for every module. We also present some of the prototypes developed to proof the concepts adopted in the design..

The Natural Guide Star Sensors (NGSS) system of HARMONI provides wavefront and image stabilisation sensing for each of the observing modes of the instrument. The Focal Plane Relay System (FPRS) relays and redirects the telescope beam from the ELT Prefocal Station (PFS) to the NGSS and spectrograph. To limit thermal background and to ensure the required stability, the sensors and optics are contained in a dry gas environment stabilized at -15 degrees Celsius. Achieving this cooled, dry environment requires an insulated enclosure, cooling system and dry air flushing system. These measures present certain novel challenges; the design solutions are described here.

The following paper illustrates the submodeling technique applied to mechanical structures, that can be considered a tradeoff between the burdensome, under a computational point of view, fully 3D models and the simpler defeatured model obtained from lines and surfaces. This approach allows to have results that are compliant to the actual behaviour of the real object and on the other hand a quick response by the calculation and analysis software. The case study refers to a main support structure of an optical instrument, and focuses in particular on the central joint between the main parts composing the full structure. The way to model truss-shaped structure is investigated both from a geometric point of view and with boundary conditions. The nomenclature and materials mostly refer to the ANSYS Workbench (R) software.

The following paper compares two different FE models, each one based on a FE model philosophy for mechanical structures. The aim of the work is to find a trade-off between cost and effectiveness, in terms of computational burdens, mechanical performances and simulation accuracy, compared to actual structure. The models taken under investigation simulate the same structure: one is composed only of 3D elements, while the other one, the “simplified”, is a mix of 1D and 2D elements, that streamlines the FE model although its geometry fits the actual one. Due to this, the simplified model gives back results comparable to the 3D one, but in a quicker way. The nomenclature and materials, recalled in the following paper, mostly refer to the ANSYS Workbench software. The object under investigation is a mechanical selector hosting a calibration unit and an optomechanical element (folding mirror). The different models are compared under a geometrical point of view, global weight and loads.

GMTNIRS, the first-generation instrument of the Giant Magellan Telescope, is a high-resolution (R = 65,000 – 80,000) near-infrared spectrograph. We introduce the preliminary design of optical mounts for slit, beam splitters, mirrors, and gratings installed in the cryogenic spectrograph. Optical components are mounted on aluminum structures and fixed by titanium springs and spring plungers. Static analysis of optical mounts with 1g-force at various directions has been performed to verify the stability of the optical system. In addition, stability in the seismic environment is evaluated with modal analysis and non-linear dynamic analysis. Design and simulation results are compared to the tolerance limits of the system.

GMTNIRS, the Giant Magellan Telescope Near-Infrared Spectrograph, is a high resolution (R = 65,000 - 80,000) near infrared spectrograph selected as a first-generation instrument for the Giant Magellan Telescope (GMT). It simultaneously observes the J, H, K, L, and M bands using five immersion gratings. GMTNIRS will be located on the GMT instrument rotator upper disk and operating in adaptive optics mode. The cryostat and optical bench design is based on the heritage of the highly successful immersion grating spectrograph, IGRINS. The cryostat is octagonal with a width of 1.7 m and a height of 1 m. It consists of top piece, bottom plate, passive radiation shields, and warm window assembly. Cryocoolers, electronics, and vacuum components are installed on the bottom plate. The optical bench system is comprised of two optical benches, bench interface structure, and active radiation shield. It is thermally isolated from the cryostat by eight sets of G10 supports. The sub-bench accommodates the fore-optics, a pupil mask, and an on instrument wave front sensor, while the spectrographs, slit-mask imager, and slit viewing camera are located on the main bench. Structure and thermal analysis have been performed to verify bench flexure by gravity vector change, integrity of the cryostat by vacuum pressure, and temperature distribution at the operating temperature of 70 K. We also present some design strategies to prevent light leakage.

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. The pre-optics take light entering the science cryostat (from the telescope or calibration system), reformatting and conditioning to be suitable for input for the rest of the instrument. In this paper, we present a complete stray light analysis of the HARMONI pre-optics including scattering from optical surface roughness and coatings, unwanted light from mechanical mounts and mechanisms, ghost reflections and scattering from particulate contaminants. Several solutions to reduce this unwanted light are proposed.

The differential refraction of light passing through the atmosphere can have a severe impact on image quality if no atmospheric dispersion corrector (ADC) is used. For the Extremely Large Telescope (ELT) this holds true up into the infrared. MICADO, the near-infrared imaging camera for the ELT, will employ a cryogenic ADC consisting of two counter-rotating Amici prisms with diameters of 125 mm. The mechanism will reduce the atmospheric dispersion to below 2.5 milli arcseconds (mas), with a set goal of 1 mas. In this report, we provide an overview of the current status of the ADC in development for MICADO. We summarise the optomechanical design and discuss how the cryogenic environment impacts the performance. We will also discuss our plan to use a diffraction mask in the cold pupil to calibrate and validate the performance, once the instrument is fully integrated.

Formerly known as MAORY [1][2][3], “MORFEO” (Multiconjugate adaptive Optics Relay For ELT Observations) is a post-focal adaptive optics module for the ELT designed to help compensate for distortions caused by turbulence in the Earth’s atmosphere that shall provide two exit ports: one for MICADO and one for a second instrument. This module, able to compensate the wave-front disturbances affecting the scientific observations, will be installed on the Nasmyth platform of the ELT telescope at the straight-through focus, and shall re-image the telescope focal plane to MICADO (the first light imager of the ELT) and in a second instrument port. In this paper we give a general overview of the mechanical design for MORFEO Main Structure (MMS) in the configuration presented for the Preliminary Design Review (PDR) in the first half of 2021, showing the proposed technical solutions for the MMS to fulfill the System requirements.

MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi conjugate Adaptive Optics RelaY (MAORY). MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. Here, we present the opto-mechanical final design of the Relay Optics (RO), the optical system relaying the ELT focal plane to an accessible position of MICADO for that SCAO-only stand-alone observing mode. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat, motorized tip-tilt-piston mirrors and three powered mirrors of up to ~500 mm in diameter, the MICADO calibration assembly and a cover to protect all opto-mechanical components on top of the bench. A 9-point whiffletree support, combined with a thermal compensation system is implemented for the critical flat mirror (M6), while a more simple 3- point support is employed for the other two flat mirror M1 and M5. The powered mirrors (M2, M3, M4) comprising the relay's three mirror anastigmat (TMA) are supported by V-shape mounts. The static and the dynamic performance of the MICADO RO are investigated through a detailed Finite Element Analysis (FEA), whose results are combined with a Zernike basis representation of the surface deformations performed in Zemax for assessing the optical performance. The variation of the mirror position due to the operational temperature drift Delta T and other disturbances, is also considered in an end-to-end simulation. The required overall wavefront error of 100 nm rms is fulfilled with the current design proposal. Additionally, the results of a motorized tip-tilt-piston mirror mount prototype are presented as well..

MOSAIC is a multi-object spectrograph planned to be installed on the ESO-Extremely Large Telescope. The project is approved to start its phase B in September/October 2022. The main science cases addressed by MOSAIC go from the study of faint stars in the Milky Way and in the local group, to the study of dark matter, galaxy evolution and first-light objects at the epoch of reionisation. The MOSAIC instrument offers Multi-Object Spectroscopy and Integral Field Units capabilities from the visible (VIS) to the near-infrared (NIR). The Laboratoire d’Astrophysique de Marseille is responsible for the development of the near infrared spectrograph. More precisely, it is in charge of the global architecture and design of the NIR spectrograph (optical, mechanical, thermal) and the assembly, integration, tests and verification (AIT/V) activities in cryogenic environment. In this article, the main tradeoffs in terms of optical and mechanical architectures are analyzed; the main technical choices are justified according to the science requirements (from which technical requirement specifications are derived) and the level of maturity of key critical technologies. The NIR spectrograph will be described in terms of system engineering approach. The requirement flow-down strategy, from high-level requirements at the system level toward technical specifications at the module and component levels will be presented. The main interfaces and the development philosophy (with an emphasis on the AIT/V plan) will also be included.

This paper describes the mechanical and electronic design of the Calibration Unit selector for MORFEO. MORFEO is a post-focal adaptive optics module for the ELT designed to help compensate for distortions caused by turbulence in the Earth’s atmosphere [1][2]. MORFEO is designed to support MICADO near-infrared camera in order to have stable and sharp images across a large field of view in the near infrared [3]. The Calibration Unit position selector is a motorized slider that allows to choose between three different positions: MORFEO calibration, MICADO calibration and observation[17]. In this paper the mechanical design and the corresponding FE analyses are shown and compared to the requirements. The design of the motorized function, in terms of components, driver and harness is also described. Finally, a safety and reliability analysis on the electromechanical subsystem is performed.

This paper provides a description of the Instrument Control Hardware design for MORFEO (Multiconjugate adaptive Optics Relay For ELT Observations), an adaptive optics module for ESO ELT. The MORFEO Instrument Control Hardware is in charge of the control electronics of the entire system. The architecture of the control system is thus based on the paradigm of decentralized functions, connected via EtherCAT fieldbus, allowing for easy communication between components that are not physically near each other. The use of industrial standards and COTS elements also leads to rapid development, easier update of the components, lower cost for spare parts and a widespread understanding of architecture among specialized firms. The Instrument Control Hardware design described in this paper is an updated version of the configuration presented for the Preliminary Design Review in the first half of 2021.

The Instrument Control Hardware design for the Extremely Large Telescope (ELT) class of instrumentation is largely based on the use of PLCs and EtherCAT fieldbus. The division into multiple subsystems that work independently for the most part encourages the use of different PLC CPUs for each subsystem, all connected to the same Control Network. However, some of the interfaces among the subsystems are more pervasive, and the necessity of a robust method of communication among subsystems arises. In this paper various methods for data exchange between subsystems, based on the use cases, are described and analyzed. Starting from this analysis, a trade-off among several architectures is presented, ranging between two opposite design approaches. All the solutions are compliant to the design requirements, but show key differences in the approach to the parameters presented in the paper.

In the ESO ELT control electronics guidelines, the hardware devices are located in standard COTS cabinets, each equipped with an air-liquid heat exchanger and customized for the specific application. The customization is done in order to achieve compliance to the stringent thermal and vibrational requirements. The cabinet design must also fulfill the required earthquake protection. In this paper these requirements are highlighted and analyzed. An alternative custom design of the cooling system is then proposed and analyzed, with specific focus on the thermal and vibrational aspects. The custom solution also allows for the use of a different cabinet, optimized for the use of DIN rail electronic components. The possibility of not using fans for air recirculation inside the cabinet is also considered, in order not to introduce further vibrations to the system.

The Main Selection Mechanism (MSM) is the cryogenic subsystem of the Multi-AO Imaging Camera for Deep Observations (MICADO) which allows to switch between the operational modes (imaging, spectroscopy, calibration) of the instrument. MICADO is one of the first light instruments for the ESO Extremely Large Telescope (ELT) and operates in the near-infrared wavelength range. The MSM is located inside the MICADO cryostat and it operates under vacuum conditions and cryogenic temperatures (`~82K). The mechanism consists of a main support structure and a rotating platform, where the MICADO Low Resolution Imager, Spectrometer and Pupil Imager modules are located. In this paper we give an overview of the final design of the MSM, which was presented at the MICADO final design review (FDR) in October 2021.

MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi-conjugate Adaptive Optics RelaY (MAORY). The instrument will provide a narrow (19′′) and a wide (51′′) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. In this mode, the ELT focal plane is reimaged to the MICADO focal plane via the relay optics (RO). This subsystem consists of an optical bench made of carbon fiber reinforced plastic, the MICADO calibration assembly, a cover to protect all opto-mechanical components on top of the bench, and an optical assembly. The optical assembly consists of six mirrors, with diameters that go up to around 500 mm. Three of the mirrors are powered, and make a TMA. The remaining mirrors are flat motorized piston, tip-tilt mirrors for interface alignment. The nominal design provides a WFE below 25.3 nmRMS for the full FoV, and a high quality exit pupil. In this work, we present the optical design of the RO, and a comprehensive tolerance analysis. This includes alignment and manufacturing tolerances, mount-induced aberrations, warping of the RO bench, and the thermal behaviour of the complete subsystem, and looking at its effects on the WFE, and exit pupil quality. We have a compliant subsystem, which has been approved at FDR level.

GMTNIRS (Giant Magellan Telescope Near-Infrared Spectrograph) is a high resolution (R = 65,000 – 80,000) wide-band near-infrared spectrograph, one of the first-generation instruments of the Giant Magellan Telescope. We present the preliminary design of the electronics system including temperature control, power distribution, vacuum pressure monitoring, moving mechanism, and packaging. Design for infrared detector subsystems for science bands (J, H, K, L, and M) and a slit-view camera is planned. The electronics system makes use of EtherCAT as fieldbus standard according to the requirement of the GMT.

METIS, the Mid-infrared E-ELT Imager and Spectrometer, is being designed for the Extremely Large Telescope (ELT) and is currently expected to arrive at the telescope early 2028. As part of the design of the instrument, we are developing the Assembly, Integration and Verification strategy for METIS. Although the sub-systems will be largely qualified at their respective institutes, only once all components come together at system level will it be possible to verify all the interfaces, full system thermal characteristics and full instrument performance. Although one of the smaller instruments for the ELT, the fully integrated METIS will still be more than 7 meters high, with a footprint in excess of 15 square meters and a weight of the order of 10 tons. This paper describes the system level assembly, integration and verification of METIS, both in Europe as well as once delivered to the telescope.

The first generation of ELT instruments include an optical-infrared High Resolution Spectrograph, formerly indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). Its modular design allows to position the calibration unit and the red & infrared spectrograph modules in the Coude room of the ELT for better thermal and mechanical stability. But to accommodate for a better UV throughput, the blue spectrograph module (UBV) will be positioned on the Nasmyth-platform of the telescope along with the front end of the system. We present the preliminary optical design of this UBV module, which extends the 400 nm blue cutoff of the baseline design to 350 nm by adding a third (the U-) arm. In addition to classical image quality calculations, we produce echelle-footprints which can be analyzed like regular observations.

This article presents the final design of the METIS/ELT warm support structure subsystem. The warm support structure provides the mechanical interface between the cryostat and the Nasmyth platform. It consists of three substructures: the elevation platform, the cryostat alignment structure (CAS), and the instrument access platform. The elevation platform is connected to the Nasmyth platform and holds the CAS. It consists of seven legs connected to three notes. The CAS is a hexapod holding the cryostat, allowing maintenance, alignment, and positioning. The instrument access platform allows human access to the cryostat, it holds the cable support system and is prepared to support the future Single Laser Adaptive Optics system. The subsystem requirements, design trade-offs, interface considerations, final design and simulation results of the substructures will be detailed as presented to the METIS Final Design Review, in 2022.

The Planetary Camera and Spectrograph (ELT-PCS) will provide an unprecedented combination of high contrast imaging and spectral resolving power to the Extremely Large Telescope (ELT) with the ambitious goal of characterizing nearby Earth-like exoplanets. We present the initial results of a laboratory experiment that aims to compare the performances of both a novel, high contrast image slicer-based integral field unit (IFU) and a traditional lenslet-based IFU for use in ELT-PCS. The slicer-based IFU mirrors are manufactured by Canon Inc. who recently developed a diamond machining technique to achieve an extremely low surface-roughness (≤1.5 nm). The experimental integral field spectrograph (IFS) is modular to operate with both custom IFUs and to ensure that differences in the optical performance are entirely driven by the IFU design. We provide an overview of the individual IFS subsystems, initial optical performance metrics, and outline the future objectives for the experiment.

MOSAIC is the Muti-Object Spectrograph for the ESO Extremely Large Telescope. The Laboratoire d’Astrophysique de Marseille (LAM) is in charge of the instrument “Assembly, Integration, Test and Verification (AIT/V)” phases. AITV for AO instruments, in laboratory as in the telescope, always represent numerous technical challenges. We already started the preparation and planning for the instrument level AIT activities, from identification of needs, challenges, risks, to defining the optimal AIT strategy. In this paper, we present the state of this study and describe several AIT/V scenarios and a planning for AIT phases in Europe and in Chile. We also show our capacity, experience and expertise to lead the instrument MOSAIC AIT/V activities.

InfraRed Imaging Spectrograph (IRIS) is one of the first light instruments for the Thirty Meter Telescope which offers the diffraction-limited imaging and integral field spectroscopic capability in the near-infrared wavelength range. One of the challenging requirements of IRIS is to achieve a 40 nm rms wavefront error in the imaging mode at the operating temperature of 77 K while achieving throughput higher than 30% in the integral field spectrograph mode. We present results of our prototyping and modeling efforts to realize the low wavefront error and highly reflective mirror, specifically focusing on the stress and deformation caused by the mirror support and the multi-layer dielectric coatings.

MICADO is one of the first-light imaging instruments of the ELT and will provide superb imaging capabilities through two AO systems to the community. Being designed to work with the MCAO system MAORY, its additional ability to operate in a stand-alone mode without MAORY includes an additional SCAO wavefront sensing system. Therefore, the instrument support structure has to fulfil two purposes, the positioning of the camera in its stand-alone mode and when it will be mounted downstream of the MCAO facility MAORY. The main instrument structure is addressed here in its basic functions such as passive positioning of the instrument in the two observing modes and linking all its subsystems together. FEA results will be given as well as other performance assessments and design trade-offs. The secondary subsystem, the rotating platform is presented in its two main functions; this platform carries six cabinets containing the instrument’s electric supply, electronic control and data links as well as the supply with coolant liquids and with LN2. It drives additionally the surrounding cable wrap that contains all the supply lines to compensate the instrument’s rotation in a gravity-invariant orientation. Finally, a permanent two-story scaffold provides convenient access to the MICADO instrument in both observing modes, in stand-alone SCAO mode (full 360° access) and in MCAO mode slightly reduced including access to MAORY’s down folding M12 mirror.

The GMT-Consortium Large Earth Finder (G-CLEF) is a fiber-fed, optical echelle spectrograph that will be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF is a general-purpose echelle spectrograph with precision radial velocity (PRV) capability. The radial velocity (RV) precision goal of G-CLEF is 10 cm/sec; necessary for detection of Earth-sized exoplanets orbiting Solar-type stars in their habitable zone. This imposes challenging stability requirements on the optical mounts and spectrograph support structures especially when considering the instrument’s operational environment. G-CLEF’s accuracy will be influenced by thermal effects, ambient air pressure, vibration, and micro gravity vector variations caused by normal telescope slewing. The design and fabrication schedule for the G-CLEF spectrograph and ancillary systems will lead the GMT telescope by approximately 5 years, therefore, we will design and build an interim installation configuration for G-CLEF at Magellan’s 6.5m telescopes. This will allow us to complete and commission the spectrograph. During this period, we will collect at least 5 years of data at Magellan from roughly 2025 to 2030. We will also optimize major subsystems including; spectrograph optics and mechanics, vacuum systems, thermal control, and vibration isolation. G-CLEF completed its Critical Design Phase for the GMT configuration in 2018. In this paper, we provide an update on the G-CLEF spectrograph’s opto-mechanical design, including the GMT front end assembly. We also provide an update on our current fabrication status including procurement of camera optics, reflective optics, carbon-fiber optical bench, camera optical mounts, and vacuum chamber assembly. We also discuss adaptations required to support the interim deployment at Magellan.

GMTNIRS, the Giant Magellan Telescope Near-Infrared Spectrograph, is a high resolution (R=65,000~80,000) near-infrared spectrograph selected as a first-generation instrument for the Giant Magellan Telescope. The instrument covers J, H, K, L, and M spectral bands in a single shot through 6-channel spectrographs. The L band is shared by two channels. Thanks to the use of silicon immersion gratings, the design is compact for its capability. GMTNIRS will be located on the GMT instrument rotator upper disk and operating in adaptive optics mode. We detail the optical system design, imaging performance, spectral formats, and fabrication/alignment budget.

The Multi-Adaptive Optics Imaging Camera for Deep Observations is one of the first light ESO Extremely-Large-Telescope (ELT) Instruments and now in it's final design stage. At a previous SPIE we sketched the PLC-based instrument control system, now we highlight more specific issues like efforts on thermal management system optimization, improvements on harness properties and advantageous controller conceptions - all seen in the context of ESOs requirements. We focus now on details for the 9 motorized cryogenic axis as well as the cryogenic and vacuum control and supervision for the delicate cryostat opto-mechanical and detector components embedded into ESO`s instrument control system environment.

METIS, the Mid-infrared Imager and Spectrograph for the Extremely Large Telescope (ELT), is one of the three first generation science instruments and about to complete its final design phase [1]. The Imager sub-system provides diffraction-limited imaging capabilities and low-resolution grism-spectroscopy in two channels: one covers the atmospheric LM bands with a field of view of 11x11 arcsec, and the second covers the N band, with a field of view of 14x14 arcsec. Both channels have a common collimator and a dichroic beam splitter dividing the light into two dedicated cameras and the corresponding detectors. In addition, the Imager provides a precise pupil re-imaging implementation allowing the positioning of high-contrast imaging masks for coronagraphic applications. The two channels are equipped with a HAWAII-2RG detector for LM-band and a GeoSnap detector for the N-band. We present the final optical design of the Imager in a summary, as well as the cryo-mechanical concept. The mechanical design gives an overview of the general design aspects and the analyses that demonstrate the approach how to deal with demanding stability and alignment requirements for high-contrast imaging. It further focuses on the design of individual units as e.g., on the GeoSnap detector mount and on the pupil re-imager. In addition, we exemplarily outline some of the key alignment and verification tasks, essential to guarantee the performance of the Imager.

METIS, the mid-infrared imager and spectrograph for the wavelength range 2.9 -13.5 µm (astronomical L-, MN- band), will be one of the three science instruments at the Extremely Large Telescope (ELT). It will provide diffraction-limited imaging, coronagraphy, high-resolution integral field spectroscopy, and low and medium resolution slit spectroscopy. Within the international METIS consortium, the University of Cologne is responsible for the design, manufacturing, integration, and qualification of the Warm Calibration Unit (WCU) of the instrument. In this contribution, we present the current status of the optical design and principle of optical operation of the WCU. The main train of the WCU optics is based on a modified F/17.75 Offner relay, with the optical output parameters matching the plate scale, F-number, as well as the exit-pupil position and size of that of the ELT. We discuss the optical design, and tolerance analysis of the WCU relay optics as part of the Optics FDR review by ESO. In addition, we present the concept and design of the Invar mechanical mounts for the WCU Zerodur mirrors, which are expected to undergo thermal and mechanical stresses. Finally, we present the optical design and analysis of the visible channel of the WCU that is aimed at alignment verification, as well as visualization of the METIS focal and pupil planes.

The warm calibration unit (WCU) is one of the subsystems of the future METIS instrument on the Extremely Large Telescope (ELT). Operating at room temperature, the WCU is mounted above the main cryostat of METIS. It will be employed as a calibration reference for science observations, as well as for verification and alignment purposes during the AIT phase. The WCU is designed and constructed at the University of Cologne, one of the partner in the METIS consortium. WCU recently went through a successful Optics Long Lead Items Review by ESO. Now, the WCU is entering the last phase of the project, the Final Design Review (FDR). In this paper, we present the current status of the WCU design and summarize the mechanical and system engineering work. We describe the design of the hexapod formed by six manually adjustable links and its interfaces with the METIS cryostat together with the CFRP-based optical bench and Invar-based optical mounts. Lab prototyping results of one actuator under a nominal load of 5 kN confirms the achievable high linear resolution (20 µm). We present the status of the WCU laser cabinet. We discuss the lastest progress in the laboratory testing of some WCU functionalities, such as the fibre-fed monochromatic sources for the spectral calibration of the LM-Spectrograph of METIS, and the spatial calibration sources using the integrating sphere. We detail the activities foreseen until FDR together with the preparation of the sub-system MAIT work.

The first generation of ELT instruments includes an optical-infrared High Resolution Spectrograph, formerly indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). This paper describes the design of the fiber link that carries the light from the telescope to the spectrometers via several selectable optical paths that in turn define the two baseline observing modes of the instrument, namely: – Seeing limited observing mode, where the light from the ELT is collected by two large fibers (~0.8" sky projected diameter) and is uniformly redistributed into smaller fibers that terminate in a linear structure aligned along the spectrometer slit. – Integral field (IFU) observing mode, where the focal plane of the ELT is reimaged at different scales (down to the diffraction limit) and fed into a bundle of fibers that covers a small hexagonal field of view and terminate in a linear structure aligned along the spectrometer slit.

This paper offers an overview of the structural analyses of the MORFEO (formerly known as MAORY [1][2][3]) Main Support Structure (MSS). MORFEO is a first light instrument for ELT (Extremely Large Telescope) that passed, recently, the Preliminary Design Review. The models are validated through FEM Analysis approach, utilizing CAD (Autodesk Inventor) and CAE (Ansys Workbench) software. In order to have a lighter model for the MORFEO MSS, and shorter computational times, simpler FE models than the 3D CAD have been developed. This discretization of reality is a standard approach in the FE analysis and in this paper it is demonstrated that this method provides accurate results at global level. A complete setting of all analyses performed to satisfy the technical requirements and specifications is shown

MAVIS (MCAO Assisted Visible Imager and Spectrograph) is a new instrument that will operate on the UT4 of the ESO Very Large Telescope (VLT), delivering comparable angular resolution in the optical to that delivered by ELTs in the infrared. The MAVIS core is represented by a multi-conjugate Adaptive Optics Module (AOM) designed to feed an Imager, a Spectrograph and a visiting instrument, all operating in the visible range. The project is now in the preliminary design phase and will be commissioned in 2027 according to the current plan. We present the current status of the MAVIS AOM instrument control electronics that will manage all the motorized functions and auxiliary sensors, focusing on the main design concepts and the preliminary prototyping activities. The design includes ESO standards and Commercial Off-The-Shelf (COTS) industrial components organized in a modular architecture to simplify the AOM preliminary integration activities, planned simultaneously in different sites. Important guidelines to the design are the attention to the overall reliability and maintainability and the minimization of risks. Almost all the motorized functions are implemented adopting preassembled industrial motorized stages. For the tracking axes, a prototyping activity has been envisaged during the design phases, in order to assess the adopted solutions are compatible with the positioning and tracking requirements.

The Exoplanets at LBT with a Visible IFS for SHARK-VIS (ELVIS) is an add-on imaging spectrograph to be integrated in the new LBT high-contrast high-resolution AO-assisted imager SHARK-VIS. ELVIS is optimized for a medium/high spectral resolution of 10-20k with a limited bandwidth around the Hα, and it is planned fed by a small core (10-20 ⊘ µm) multi mode fiber bundle providing about 140 spaxels on a field of view around 300×300 sqmas. This instrument has a very compact design based on a VPH dispersing element to allow its installation within a standard 19” rack mount. As shown in the literature, young accreting sub-stellar and planetary companions are better detected and analyzed by these instruments allowing to reach contrast at least ten times fainter (in their Hα emission) with respect to standard imagers.

SHARK-NIR is a high contrast camera for the LBT, spanning the Y, J and H bands. It has been designed to fully exploit the high Strehl adaptive optics correction delivered by the FLAO module, recently upgraded to SOUL, and implements different coronagraphic techniques, with contrast as high as 10-6 up to 65 mas from the star. It also has spectroscopical capabilities, with low and medium resolution, and its relatively wide Field of View (18 x 18 arcsec) makes it accessible to other scientific targets, such as galactic jets and disks, as well as extra-galactic cases. The nature of the instrument, requiring deep exploration of stars very close neighborhood, translates into the requirements of extreme delivered optical quality and stability, ideally not to degrade the exquisite correction performed by SOUL. To improve its performance, SHARK-NIR includes a couple of peculiar features, such as a fast internal TT loop to minimize the residual jitter and a local NCPA correction, performed through a DM inside the instrument itself. SHARK-NIR will be mounted at a gravity variant focal station, thus it has to cope with flexures, whose effects could kill the coronagraphic performance. To minimize the effect of flexures, SHARK-NIR is a very compact and stiff instrument, whose flexures have been characterized during a dedicated campaign in laboratory, where the whole instrument was mounted on a dedicated handling simulating different telescope elevations. We report here the main results of the flexures tests and of the AIV phase, ended at the beginning of 2022..

The SPEED test-bed is completed and operational at Lagrange Laboratory in Nice. The bench optical design allows a wide range of applications in high-contrast imaging: cophasing optics, coronagraphy, and wavefront shaping for large segmented on-axis telescopes. SPEED offers an ad hoc and representative lab environment for studying the effect of pupil fragmentation in a high-correction contrast regime to assess quasi-static speckle control and stability. The SPEED prime goal is to demonstrate high contrast at short angular separations with an unfriendly telescope aperture. After years of developments, from early design to first lights, we thoroughly present the SPEED facility by discussing the principal elements that have driven the design. The main characteristics and exploitation modes of this unique facility are presented.

Here we present modeling of the polarization aberrations of the Gemini telescope as seen by the Gemini Planet Imager’s dual-channel polarimetry mode. We first calculate the Jones pupil using a polarization sensitive ray-tracing program and theoretical properties for the Gemini mirror coatings. The predominant effect is a differential astigmatism between incident x and y polarization states, also known as retardance defocus. We use this Jones pupil as an input to a Fourier optics model of the Gemini Planet Imager to create model Stokes Q and U images, which we compare to on-sky data. We demonstrate that the effects of the telescope polarization aberrations can be detected in the on-sky data and speculate that they may be limiting the polarimetric contrasts at the smallest inner working angles. Finally, we explore how the polarization aberrations couple with residual atmospheric wavefront error from the adaptive optics system, and how they affect the polarimetric performance of new GPI 2.0 coronagraph designs.

The SPEED test-bed (Segmented Pupil Experiment for Exoplanet Detection) is a high contrast imaging platform whose prime objective is to study coronagraphy and wavefront shaping for large segmented on-axis telescopes. Active control and temporal stability of residual wavefront errors is one pillar to consider for improving detection yields and getting access to object classes with masses ideally down to exoEarths. The SPEED test-bed being more complex than a simple laboratory test bench but less demanding than an on-sky instrument at a telescope, imposes a specific and adapted system and software control development. The paper reports the design of the SPEED system control hardware and software infrastructure that enables the bench to operate efficiently and safely. Because having experts in software engineering processes for laboratory development is rather difficult to afford, the paper will touch on several design items, highlighting aspects which, in our opinion, may be of particular interest for designers and implementers of laboratory control software.

MagAO-X is a visible to near-IR AO system that will enable a suite of instruments to perform high-contrast, high-resolution science. During its "Phase II" plan a 10-kilopixel Microwave Kinetic Inductance Detector (MKID) IFU will be deployed as a science camera behind MagAO-X. MKIDs are photon-counting detectors with energy resolution up to 30. The photon counting capability and readout allow for microsecond time resolution with no associated read noise. As a consequence of the high readout rate the MKID camera can be used as a Focal Plane Wavefront Sensor (FPWFS) allowing real-time speckle control while simultaneously taking science observations. With the high resolution and contrasts delivered by MagAO-X the MKID camera will aim to directly image and characterize exoplanets in the near-IR. The camera's IR filters can also be replaced with visible filters that will allow for further characterization and the potential for exploration of the inner regions of circumstellar disks.

The 4m DAG telescope is under construction at East Anatolia Observatory in Turkey. DIRAC, the “DAG InfraRed Adaptive optics Camera”, is one of the facility instruments. This paper describes the design of the camera to meet the performance specifications. Adaptive and auxiliary optics relay the telescope F/14 input 1:1 into DIRAC. The camera has an all refractive design for the wavelength range 0.9 - 2.4 micron. Lenses reimage the telescope focal plane 33 x 33 as (9 x 9 mm) on a 1k x 1k focal plane array. With magnification of 2x, the plate scale on the detector is 33 mas/pixel. There are 4 standard filters (Y, J, H, K) and 4 narrowband continuum filters. A 12 position filter wheel allows installation of 2 extra customer filters for specific needs; the filter wheel also deploys a pupil viewer lens. Optical tolerancing is carried out to deliver the required image quality at polychromatic Strehl ratio of 90% with focus compensator. This reveals some challenges in the precision assembly of optics for cryogenic environments. We require cells capable of maintaining precision alignment and keeping lenses stress free. The goal is achieved by a combination of flexures with special bonding epoxy matching closely the CTE of the lens cells and crystalline materials. The camera design is very compact with object to image distance <220 mm and lens diameters <25 mm. A standalone cryostat is LN2 cooled for vibration free operation with the bench mounted adaptive optics module (TROIA) and coronagraph (PLACID) at the Nasmyth focus of the DAG telescope.

MAVIS is a Multi-Conjugate Adaptive Optics for the UT4 of VLT designed to deliver a corrected FoV to a spectrograph, an imager, and a visiting instrument. An optical bench is used to support the post focal relay optics, which include the ADC, a K-mirror, the DM, and the selector. Said bench also rigidly supports the calibration, the LGS module, the NGS module and the imager providing the maximum stability and repeatability during maintenance operations. The Adaptive Optics Module structure (AOMS) was rigidly connected to the Nasmyth platform structure via the Overall Mechanical Structure (OMS). The OMS also provides structural integrity for the Spectrograph sub-system while isolating it from the main enclosure. At this level the AOMS and the OMS have been merged in a single structure; the decision about keeping them together or separated will be taken in the future depending on mechanical and integration considerations. The preliminary design choices adopted while designing these subsystems are presented considering the actual mechanical and thermal requirements. Particular attention is given to the derotation system design (K-mirror) and the analyses done to choose the materials and the adhesives.

The Arizona Lenslets for Exoplanet Spectroscopy (ALES) is an integral field spectrograph implemented with a modular design comprising magnifiers, a lenslet array, and direct-vision prisms all installed in filterwheels within the LBTI/LMIRCam instrument. ALES is unique among high-contrast instruments for providing spatially resolved spectroscopy out to 5 microns. ALES has been operating with an upgraded lenslet array and prism assembly since late 2018. The new lenslet array includes larger lenslets to reduce diffraction losses and spatial crosstalk in the data. The lenslet array is fabricated with a unique sag surface for each lenslet, correcting for rotating off-axis astigmatism in the magnified intermediate focal plane. The result is tighter lenslet spots and better data. The new prism assembly provides increased spectral resolution in the 2.9 to 4.2 micron wavelength range. Here we characterize the performance of upgraded ALES, and report initial results probing the atmospheres of high-contrast companions to nearby stars. A calibration and data pre-processing strategy unique to the upgraded instrument is discussed. We also report laboratory tests of additional future upgrades including prism and blocking filter pairs for added bandpasses and magnification modes to facilitate Fizeau interferometry with LMIRCam and ALES.

The Gemini Planet Imager (GPI) is a facility class instrument for the Gemini Observatory with the primary goal of directly detecting young Jovian planets. After several years of successful operations on sky at Gemini South, GPI is undergoing an upgrade at the University of Notre Dame and is being moved to Gemini North. We present the current performance results, from in-lab testing, for several of the upgraded components to the Integral Field Spectrograph (IFS) and the Calibration Wavefront Sensor (CAL) for GPI 2.0. These upgrades include changes to the IFS dispersion prisms, changes to the pupil viewing cameras, and changes to the low order wavefront sensor. These improvements are designed to improve the magnitude and contrast range of GPI. We describe the alignment of several components, their noise characteristics, and their performance in the GPI environment.

The proposed MAVIS instrument for the VLT UT4 delivers a 30" x 30" MCAO-corrected field for 370-950nm. It includes an integral-field spectroscopic mode, whereby a subsection of the field is delivered to an image slicer and spectrograph, with either 25mas or 50mas spatial sampling, and R<4000 and R<10000 modes in either the red or the blue. Three designs are being considered for the image slicer, two with all-reflective optics, and the other, presented here, derived from the existing WiFeS spectrograph and including arrays of small lenses. A spectrograph design is also presented, challenging because of the need to be close to diffraction-limited across the entire wavelength range, while maintaining high throughput, in all 4 modes and over the entire 9cm x 9cm detector.

SCALES (Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy) is a 2 - 5 micron high-contrast lenslet-based integral field spectrograph (IFS) designed to characterize exoplanets and their atmospheres. Like other lenslet-based IFSs, SCALES produces a short micro-spectrum of each lenslet’s micro-pupil. We have developed an image slicer that sits behind the lenslet array & dissects and rearranges a subset of micro-pupils into a pseudo-slit. The combination lenslet array and slicer (or slenslit) allows SCALES to produce much longer spectra, thereby increasing the spectral resolution by over an order of magnitude and allowing for comparisons to atmospheric modeling at unprecedented resolution. This proceeding describes the design and performance of the slenslit.

The Planetary Systems Imager (PSI) is a second-generation exoplanet detection and characterization instrument concept for the Thirty Meter Telescope (TMT). PSI will enable extreme adaptive optics imaging and spectroscopy from the visible into the infrared. Its high contrast, coupled with TMT’s sensitivity, will access entirely new regions of exoplanet parameter space. Here we describe the driving exoplanet science cases for PSI, including detecting and characterizing rocky planets around nearby M dwarfs, constraining atmospheric and surface compositions and variability, measuring accretion onto protoplanets on Solar System orbital scales, and more. We present the top level instrument requirements for each subsystem, which we derive from these science cases and inform using simulations. We discuss PSI’s expected science outcomes for exoplanet studies, and also highlight examples of its potential for Solar System, galactic, and extragalactic science.

Over the past six years the Gemini Planet Imager instrument has carried out adaptive-optics fed high-contrast imaging observations from the Gemini South telescope in Chile. GPI will now be upgraded for increased sensitivity and science capabilities as GPI 2.0, and will be moved to the Gemini North telescope in Hawaii. Here we describe tests we conducted remotely of the GPI instrument before shipment from Chile, and in-person following its arrival at the University of Notre Dame, where the upgrade will take place. These tests were originally designed to accommodate science program requirements and to ensure compatibility with the host observatory. We have now re-performed tests so as to assess the state of the instrument following six years of scientific performance. We present the high-level results of this baselining process, describe their implications and limitations, and compare them with results from tests performed when the original instrument was shipped to Chile in 2013.

New frontiers of astronomical science push the imaging capabilities of modern AO-equipped telescopes. However, precision measurement at the diffraction limit is made challenging by time-varying residual aberrations in AO-corrected wavefronts. Photonic lanterns (PLs) are a novel technology whose spatial filtering and coherence properties may be exploited to enable new capabilities in precision measurement at the diffraction limit. We aim to determine the potential of AO-fed PL fiber spectrometers for spectroastrometry. We define spectroastrometric signals for a 6-port PL and perform numerical simulations to calculate expected signals for a binary point source model, as a function of contrast, separation, and position angle. In addition, we simulate the effects of AO residual wavefront error on spectroastrometric signals. We also present simulated spectroastrometric signals for accreting planets, which are expected to show strong hydrogen emission lines.