Optical Design and Engineering IX

Developing an optical system from scratch involves many tasks and activities. From the design step to the delivery of the product, anything can lead to (mostly bad) surprises. Complex specifications, very challenging requirements, difficult technical choices, frightening tests or after-shipping non-compliance... the path to a good product is paved with many traps. This paper will present some of these issues, along with the solutions found to mitigate them, that occurred on the Spectral Separation Assembly, a sub-system of the Flexible Combined Imager, the main imaging instrument of the Meteosat Third Generation mission.

With the STAR Module, Ansys Zemax OpticStudio gains a built-on STOP Analysis tool which allows the user to load, visualize and numerically fit FEA Datasets from any FEA Solution onto the optical system inside Ansys Zemax OpticStudio and utilize the whole optical analysis tool range to assess the influence of thermal and structural loads on the optical performance. Join Flurin Herren, Optomechanical Engineer at Ansys Zemax, for a presentation which will outline the design process of a low-orbit telescope system and utilize the STAR Module to execute a full STOP Analysis workflow, considering the influence of thermal and structural loads on mechanical and optical components.

The Korea Astronomy and Space Science Institute (KASI) is developing GrainCams as a candidate payload for NASA's Commercial Lunar Payload Services (CLPS) mission. GrainCams consists of two cameras designed for scientific research on the lunar regolith and levitating particulates. One of them is LevCam, which observes the motion of levitating dust over the lunar surface. The other is SurfCam, a camera intended for observing the uppermost regolith on the lunar surface. The purpose of SurfCam is to get knowledge of the regolith on the lunar surface and obtain 3D images of the micro-structures through image processing with a micro-lens array (MLA). SurfCam consists of 1 cover glass, 12 spherical lenses, and MLA. All optics use space-qualified glass material to carry out a one-lunar-day mission on the moon. Optical and mechanical designs have been developed so far, and an analysis of how stray light affects the overall system has been conducted. In this paper, I will describe the analysis of ghosting and scattering effects in SurfCam through stray light analysis.

The Cubesat-compatible Morera optical instrument is a very compact, low f/n LWIR camera designed to provide high resolution images at farm level to estimate evapotranspiration data and provide personalized irrigation recommendations directly to final users using a mobile device. A SW-defined system will use Big Data to combine all relevant information (AEMET, Copernicus, S-SEBI algorithms) to optimize water resources. The final optomechanical configuration, its performance and straylight behavior are described in this paper.

NewAthena, the New Advanced Telescope for High Energy Astrophysics, has just been endorsed by ESA as one of its L-class mission, to launch in 2037. We present in this paper the optomechanical design of the Silicon Pore Optics employed for the NewAthena X-Ray telescope mission. Analysis of the structural, thermal and optical design is being validated through FEM simulations and environmental testing, as will be shown.

Chandrayaan-3 is a mission by the Indian Space Research Organisation to perform a safe and soft landing on the moon's surface and to deploy a rover to conduct scientific experiments. The lander (Vikram) has a Lander Horizontal Velocity Camera (LHVC) which is a vision-based navigation sensor to measure the horizontal velocity of Vikram while landing at the Shiv-Shakti point. The rover (Pragyan) has a Navigation Camera (NavCam) for its path planning and navigation. This paper describes the criticalities in the optical design and testing of the lens systems that were developed for LHVC and NavCam. The opto-mechanical design has been carried out for the lens systems to withstand extreme environmental perturbations of the vibration, thermo-vacuum, and radiation loads. The lens systems have been rigorously tested for parameters like effective focal length, modulation transfer function, etc. to ensure their flight-worthiness. The key role played by LHVC in the terminal descent phase of Vikram and the successful maneuvering of Pragyan on the lunar surface along with the images of Vikram taken by Navcam has validated the optical lens systems' performances under extra-terrestrial conditions.

Current optical design methods rely heavily on ray tracing and optimization algorithms, typically requiring substantial expertise, intuition, and often iterative trial-and-error work steps. We propose a new approach that generates promising initial designs directly from the specified requirements and constraints. Our developed 'First Time Right' (FTR)-based design tool automatically calculates all optical surface coefficients to minimize the image blurring per aberration order. Importantly, it also factors in any imposed practical constraints, such as stop position, dimensions, spacings, or back focal length restrictions. Taking our methodology to the next level, we have combined FTR with PanDao, which models fabrication chains based on provided design data. This integration aims to minimize both cost and risk in optics manufacturing. We reviewed and refined several real-world lens design examples, resulting in excellent alternative designs that maintain equivalent optical performance while reducing overall production costs.

A new method for glass substitution during the lens design has been developed. Exploring existing longitudinal aberration contributions, the new method uses sensitivity analysis to find optimal optical glass constants (refractive index, Abbe number, and relative partial dispersion) for certain optical system elements. A case study introducing the glass substitution method to the optical system design is described. It is shown that the new approach provides step-by-step improvements in the optical system’s longitudinal aberration correction. The current limitations of the method are also described.

Natural Guide Star (NGS) wavefront sensors (WFS) play a crucial role in multi-conjugate adaptive optics systems by detecting low-order aberrations that laser guide stars cannot measure. In the framework of MAVIS, we plan to use the light from three NGSs to correct the tip-tilt and low-order errors of the wavefront. In this work, we conducted the analysis of the distortions caused by mid-spatial frequency figure errors of the optical surfaces in the NGS WFS channel of the adaptive optics module of MAVIS. These distortions, stemming from component imperfections, can significantly impact wavefront measurements and, consequently, the plate scale in the image plane of the entire instrument. We analyse their influence on the plate scale variations during tracking. Our study quantifies the effect, shedding light on the impact of non-common path distortions between the NGS WFS and the scientific instruments on plate scale variations, ultimately contributing to optimising the MAVIS performance.

This paper describes a new end-to-end virtual prototyping solution which allows design of both the lens system and CMOS image sensor and subsequent evaluation of the combined system performance in a virtual environment under different illumination conditions. The camera lens system is designed with the optical design software Ansys Zemax OpticStudio. Then an optical ROM (Reduced Order Model) of this lens system is exported to Ansys Speos, a ray tracing software embedded in a 3D CAD environment that provides fast yet accurate simulation while accounting for environmental conditions, including artificial and natural light sources. In parallel, photonic simulation with Ansys Lumerical FDTD and CHARGE solvers provides the quantum efficiency of the CMOS image sensor. Light exposure from the 3D scene through the lens system onto the sensor is combined with the quantum efficiency of the CMOS image sensor to generate raw image and final image based on the digital processing.

The arrival of ChatGPT, Google Bard, and other highly advanced artificial intelligence model show us just how brilliantly tasks can be reproduced by those engines. So, it's legitimate to wonder how our field (or any fields) might be affected in the future. We've already seen the beginnings of the possibilities, notably with LensNet [1], which provides optical designers with starting points for common cases; we can also study a solution space of certain type of lenses using deep learning [2]; and more recently, papers on the use of deep learning to simulate the entire chain of an optical system from object to final image processing, including tasks such as recognition. These latest end-to-end simulations have shown that in some cases, it is even necessary to redefine the optical optimization criteria to maximize certain computer tasks. In short, the computer doesn't necessarily need a good image in terms of MTF to perform its task. In this context, how the future will be affected or enhanced by these new AI approaches. In this presentation, I will first give a brief history of how AI has impacted optical system design since 40 years. Then I will use examples to discuss the extraordinary acceleration in works over the past 5 years, the choices that have or haven't been made, and the importance of having access to source code from publications. Finally, I will conclude with some thoughts on what may or may not lie ahead, and how we can introduce these new technologies into the training of future optical system designers. [1] Geoffroi Côté, Jean-François Lalonde, and Simon Thibault, "Deep learning-enabled framework for automatic lens design starting point generation," Opt. Express 29, 3841-3854 (2021). [2] Geoffroi Côté, Yueqian Zhang, Christoph Menke, Jean-François Lalonde, and Simon Thibault, "Inferring the solution space of microscope objective lenses using deep learning," Opt. Express 30, 6531-6545 (2022).

Freeform optics for illumination, pioneered over 20 years ago, are now widely used to light up streets, automobiles, architecture and more. But many questions remain: Do we have good, accessible design methods, especially for extended sources? Do we have proven processes to estimate and specify tolerances, to ensure full production yield without overengineering? Do we fully understand diffractive structures on freeform surfaces? The talk discusses the progress of design and manufacturing methods over the last 30 years, shows the knowledge gaps we’re suffering from, and concludes with an outlook to a non-obvious but exciting new approach for coherent light: What happens when we combine freeform surfaces with scattering and spatial light modulation?

INO developed a quick and easy way to simulate model optomechanical errors according to the chosen lens assembly method. A better optomechanical modeling for the tolerances analysis helps avoid the production of overly expensive optical systems with excellent performances, or on the other hand, the production of inexpensive optical systems with unexpectedly erratic performances. This article presents the methodology used to find the best centering method for an infrared dual-band objective lens for which almost diffraction limited performances are required.

To properly account for imperfections in fabrication of lenses and mechanics as well as optics alignment limitations, it is necessary to run a tolerance analysis during the optical design process. But it is often unclear what level of detail the tolerance model necessitates to accurately predict the variation in performance, and there are consequences of time and money for both overly optimistic and overly pessimistic designs. In this work, we compare the assembly results of a precision microscope system with an initially overly pessimistic tolerance analysis, and develop an improved tolerance model in agreement with the performance of as-built systems. The system is analysed in two industry-standard optical design software, Zemax’s Monte Carlo and CODE V’s TOR, and the results are compared with each other and with assembly data. We discuss the aspects of the tolerance model developed here that are generalizable to other systems.

Aperture and volume constraints can impact the design form of a telescope. While freeform optics may positively impact volume, opting for a conventional approach might still be the optimal choice. This presentation will include a design for an Earth-observing telescope, along with an exploration of the methodology and trade-offs associated with various design forms investigated throughout the design process.

The adoption of freeform optics by designers and manufacturers has increased in recent years. With the increase of flexibility a freeform surface can bring a system, it also brings more sensitivities. To effectively control these sensitivities during integration, the tolerancing needs to incorporate the limits of the metrology device for the tolerance operand under test. Understanding a vendor’s manufacturing and metrology capabilities is critical to designing and tolerancing a freeform surface that uses its physical features to aid in integration. Interfacing with a vendor early in the design process may improve manufacturing timelines due to the alignment of the freeform definition with the available metrology. Favorable freeform definitions will be reviewed along with tolerancing and specification recommendations.

We present a new approach for the tolerancing of correlated optical systems. These systems consist of at least two optical channels which are linked together. To represent the correlations e.g., for compensators correctly in the tolerancing procedure, tabulated pseudo random numbers are used. This leads to efficient tolerancing and accurate results.

Rudolf Kingslake is widely regarded as one of the founders of modern optical design. When educating his students at The Institute of Optics, Professor Kingslake championed the importance of lens design fundamentals as a complement to computer-aided design. At that time, ray tracing speed was a major bottleneck in the lens design process. Now that lens designers can trace rays in fractions of a second and have access to powerful computational tools like global optimization and AI are these same fundamentals needed? Should we keep teaching them? One of Kingslake’s biggest fears was that we would forget “our laboriously acquired knowledge of geometrical optics and substitute for it the mathematical problem of optimizing a merit function”. There is no question that computers have done wonders for lens design and have enabled far more advanced designs than thought possible. The issue at hand is if mastery of both lens design fundamentals and computer software is required for success. Unfortunately, the current educational landscape places much more emphasis on the latter than the former, and many of the fundamentals impressed by Kingslake have been lost. However, three boxes of index cards belonging to Rudolf Kingslake were recently uncovered. Included in the collection are 171 lens design exam problems which present a fascinating perspective on lens design as it was taught in the pre-computer age. In this talk we’ll take a closer look at several of these forgotten problems and discuss how their solutions are still relevant for modern lens design today.

In 2017, the European Southern Observatory (ESO) awarded a contract for the Polishing, integration and final figuring of the Segment Assemblies of the primary mirror (M1) for the Extremely Large Telescope (ELT) to Safran Reosc. Since then, the design and commissioning of a production unit dedicated to ELT M1 has been accomplished and the plant has been producing many mirrors since spring 2022. We will introduce the smart factory, its processes and their automation that enabled reaching the current throughput of one mirror per day. We will then present the status of the project, some lessons learned and highlight the successes that have been achieved so far.

Ghost images in optical systems are undesirable secondary images or reflections that appear alongside the primary image, often caused by multiple reflections of in-field rays within the optical system. These ghost images can lead to interference and a reduction in image quality. They are problematic in applications such as microscopy, and telescopes, where image clarity and contrast are essential. This study investigates ghost reflections in catadioptric multi-spectral imaging systems, offering qualitative and quantitative analyses. We identify cross-talk ghost as a significant issue, even with low surface reflection coefficients. The research assesses mitigation strategies, including masking and tilting filter surfaces, with a standout solution: the Ghost Blocker Plate. Experimental results demonstrate its remarkable effectiveness, reducing ghost reflections from 23% to under 1%. This research is crucial for multi-spectral imaging system designers, emphasising the need for addressing ghost reflections early in the design phase. The Ghost Blocker Plate proves to be a practical and highly successful approach to minimize ghost reflections.

Minimizing glare and ghost images in an optical system through stray light control is a significant percentage of the system’s design time and cost. Fresnel reflections that cause stray light are often among the worst offenders, and companies rely on optical coatings to reduce the reflections' impact and increase the signal-to-noise ratio (SNR). To facilitate component-level stray light analysis and reduce cost by coating only needed surfaces, we have created a stand-alone tool that uses the OpticStudio Application Programming Interface (API ) to analyze the stray light optical paths and identify the contribution of each component to the noise. Once the contributing surfaces are identified, coatings can be applied only to the worst offenders until the desired SNR is achieved. This process reduces the analysis time and helps to reduce costs compared to coating all the surfaces in the optical system. Use cases and SNR analysis to validate the tool will be presented.

Stray light analysis is essential for high-quality optical systems, minimizing unwanted light such as lens flare issues. This article introduces a system-level approach with Ansys optics simulation tools, considering stray light from optical and non-optical components and integrating with optiSLang for automated exploration and design optimization. The practical camera use-case highlights seamless data exchange between Ansys optics simulation tools. It employs a range of intuitive features, from Zemax OpticStudio's sequential ray tracing, extending to Speos ray path analysis while leveraging GPU and Cloud Computing. The combined capabilities offer an efficient solution, streamlining collaboration and enabling optimized optical system designs.

The ESA LSTM mission requires for very stringent straylight performances, that should be met over a wide spectral range and drives the optical design. We have developed a complete straylight model of the whole instrument, including optics and mechanics, with their respective coatings and scattering models using non sequential raytracing software. We have performed ghosts and scatter simulations in the frame of instrument PDR, taking into account multispectral effects. We also describe the methodology used for baffle optimization, especially slit masks implemented on spectral filter subassemblies, at each focal plane. A parametric study has been performed, to get an optimized set for mask parameters.

Since the development of the first achromatic lenses back in the 18th century, dispersion models have been constant companions of optical designers. Various alternatives and extensions to the classical Abbe number and partial dispersion model have been proposed over the years, with the goal of making first- and higher order analysis and correction easier accessible. Hoogland’s reformulation of the classical quantities allowed to visually select glasses and read optical powers for an apochromatic lens from a diagram, and Buchdahl dispersion coefficients have been used as basis for similar work in the infrared spectrum. In both cases however, model parameters must be tuned to arrive at the desired representation. Here we present a model-free approach using principal component analysis of normalized refractive index data at the system wavelengths. We show how it can be applied to understand simultaneously both the dispersion properties and color correction capabilities of a selection of glasses in any part of the optical spectrum, and how to derive favorable glass combinations for apochromatic and superapochromatic lenses including a prediction of residual color.

Hybrid diffractive lenses are an enabling technology that allows the shaping and control of wavefronts by precisely controlled zone structures, a coherent version of a standard Fresnel lens. They are extremely useful in the medium and long wave infrared spectral regions for performing colour correction, where traditional cemented doublets (that are used in the visible region) are not an option. In the current presentation, we move to a more physical model based on the ideas of zone decomposition and how this may be applied to advantage for multi-order diffractive lenses. From this standpoint, one sees how interpolation takes place from a standard diffractive surface all the way up to purely refractive Fresnel lens. The multi-order diffractive surface sits between these exhibiting both coherence across different zones but also the onset of incoherence, thereby returning to a surface with only refractive properties.

Recently the first automotive vehicles with micro-optical headlights entered the market as series production models. However, the currently implemented low-beam systems suffer from low transmission and notable cost for the micro-optics elements. Both problems can be traced back to the buried micro-slides within the micro lens arrays (MLA) which shape the distribution. We developed a micro-optical solution for a low beam without mask layers, thereby significantly increasing transmission to a very competitive level and enabling more cost-effective manufacturing processes. Our design comprises of a multitude of differently shaped lenslets, which form the beam collectively. The design process includes the generation of the overall distribution as well as detailed features such as the sharp and specially shaped cut-off. A first LED-illuminated demonstrator showed that the shape and the required sharpness of the cut-off as well as accordance with UNECE safety regulations can be achieved even without the use of absorbing masks.

Performance and reliability requirements for modern optical systems dictate that they can no longer be simulated in isolation without reference to external and environmental factors which can adversely impact image quality. Applications where light propagates through a fluid surrounding or within an optical system present a particular simulation challenge in this regard, and one that requires new simulation techniques. Variations in pressure, temperature, and density of the fluid lead to variations in refractive index that, in turn, induce optical aberrations in a transmitted wavefront. We present a solution, utilizing coupled computational fluid dynamics (CFD) simulations and optical ray tracing, to model the effects of light propagation through optical fluids accurately. Use cases including electro-optic infrared and laser communication airborne optical systems will be investigated.

For the design of well corrected optical systems with a certain spectral bandwidth, it is often not sufficient to only control axial and lateral color, but also chromatic variations of the 4th order wave aberrations or Seidel coefficients need to be considered. This has already been studied in detail in the literature by Berner. We propose a different approach to calculate the induced surface contributions to chromatic variations of the Seidel coefficients which is based on the principles of stop and object shift. This offers a different perspective that might be helpful for optical designers.

In this presentation, we will showcase a differential ray tracer with NURBS capabilities called FORMIDABLE. Compared to available commercial optical design software, this code can simulate and especially optimize Non-Uniform Rational B-Spline (NURBS). FORMIDABLE's implementation of differential ray-tracing capabilities allows faster convergence of systems described by many degrees of freedom and makes optimization with NURBS surfaces viable. The features of FORMIDABLE will first be described. Then its capabilities will be illustrated with the optimization of a classical non-reimaging Three-Mirror Anastigmat (TMA) by considering either a description of surfaces by NURBS or a description by the polynomial basis XY. Then this optimized TMA will be compared with its equivalent optimized with ZEMAX OpticStudio software. To enable this software comparison, we will use the same starting point and practically the same merit function. Standard metrics, such as RMS spot size across the field of view will be used to assess the imaging quality. FORMIDABLE is an open-source library distributed under the ESA Software community License.

The use of a photon sieve (PS) structure has been suggested to design intracorneal implants with drainage holes and multifocal properties. In this study we present how the customization of the 3D hole profile allows designing an innovative implant for the correction of presbyopia. This new implant consists in an apodized transparent PS with bevelled holes whose use in a bilateral mix-and-match approach can provide good visual acuity on an extended range of distance.

Using freeform surfaces, an Offner spectrometer with a freeform grating has been designed to enhance the instrument's field of view while maintaining performance. Initial layout studies with standard optics were followed by the implementation of freeform polynomials on the grating’s surface, expanding the field of view from 51 mm to 58mm. Zernike FRINGE sag polynomials up to the 21st order coefficients were employed. Performance benchmarks including smile and keystone distortions, MTF and grating dispersion were consistently met, showcasing the efficacy of freeform optics in advancing optical technology and optimizing imaging system.

Space-based spectrometers are of high importance for Earth observation and greenhouse gas sensing. We present a novel freeform pushbroom imaging spectrometer, covering the near-infrared (1100 – 1700 nm) and thermal (8 – 14 µm) wavelength range, showing a full field-of-view of 120°, while fitting within only 2 CubeSat Units. The design is composed of a freeform 2-mirror telescope, followed by a 2-channel freeform spectrometer unit. The freeform telescope guides the light to a spectrometer entrance slit, after which a collimating mirror is present, and the light is split to the 2 spectrometer channels. Both spectrometers comprise of a reflection grating and 2 freeform mirrors to focus the light on a 2D detector, providing both spatial and spectral information. All mirrors are described using XY polynomials, up to the 4th order, enabling a close to diffraction-limited performance. Consequently, this design might benefit future space missions enabling an improved Earth observation and climate monitoring.

Planetary exploration missions generally impose high demands on both the imaging quality and the size-weight constraints of optical systems. Therefore, this paper proposes using curved detector in the design of a fast and wide-field off-axis freeform three-mirror optical system, aiming to achieve high imaging performance within a relatively small volume. Specifically, a freeform-shaped curved detector is considered in the off-axis system design, which ultimately enables the system reach a near diffraction limited image quality within 10-liter volume. The proposed design shows great potential for application in planetary exploration missions, making the higher performance imaging instruments feasible in the future missions.

This paper introduces the tolerancing and design–for–manufacture in the catadioptric telescope for the remote sensing instrument (RSI) in the FORMOSAT–8 satellites program. The study utilized wavefront differential tolerance analysis to accelerate the tolerancing process efficiently. To address potential performance variations stemming from manufacture, assembly or alignment regulations, compensators were used to model these adjustments. The outcome delves into the strategic choices of specification and ion beam figuring (IBF) to trade–off manufacturability within the RSI system.

The aim of this study is to perform experimentally the multi-parameter analysis of the characteristics of laser scanners with rotational refractive polygons (RPs). This analysis encompasses scanning function and speed, limit angles, Field-of-View (FOV), and duty cycle. Also, dispersion is studied due to do the refractive constituent of the device, as well as vignetting of the beam at the beginning and end of the facets. The study is performed with regard to the constructive parameters of the regular RPs: apothem, number of facets, refraction index, and eccentricity of the incident beam with regard to the polygon pivot. Regular convex RPs with an even number of facets are considered, because of the main advantage of this optical set-up: the laser beam emerges parallel at all times to the incident one, in contrast to other optomechanical laser scanners such as galvanometer-based (GS) or with polygon mirrors (PMs). The above characteristics are determined and compared for these three RPs. Also, a validation of the theory we developed is made using this experimental study. A comparison is made between such devices and the common GS and PM-based scanners.

The completely open dome provides excellent dome Seeing, but at the same time wind loads are applied directly to the telescope, and the wind screen structure can be a good solution to this contradiction. The effects of the wind screen structure on the wind speed around the telescope, dome Seeing, mirror wind pressure, etc. are investigated by simulation and wind tunnel tests, and the optimal wind screen transmittance, structural rod size, and the distance between the wind screen and the telescope are finally obtained.

In this work we introduce a new category of diffractive lenses called multifocal binary Gabor zone plates (MGZP). These lenses are designed by integrating in a single plate multiple binary Gabor zone plates with distinct harmonic terms. We demonstrate how this binding allows the creation of a desired multifocal distribution that can be customized in the lens design to generate multiple focal points with adjustable focal distances of variable intensity. Numerical examples are presented of a bifocal and to a trifocal lenses with equi-energetic foci.

This paper introduced a meticulous design and optimization of a Mid-Wave Infrared (MWIR) continuous zoom lens system which is compatible with high definition detector. In addition to these specifications, the research focuses on integrating narcissus reduction techniques and implementing opto-mechanical optimization which ultimately enhance overall system performance in practical applicaition. This research is poised to advance MWIR imaging capabilities significantly, benefiting a wide array of applications and driving the evolution of next-generation MWIR imaging technology.

As the first time proposed the scanner with deflection two laser sources beam just by one reflective element – polygon mirrors. This work will take a new look and comprehensive on polygon scanners. In terms of theoretical understanding, the 2D analysis of the scanner head needs to be addressed. This first step will give us the optical characteristics of the polygon scanner as well as give the future user a list of equations to design their own needed polygon scanner (desired scanning length, focusing length, size of polygon, number of facets. Although our main purpose in this study is to design a polygon scanner with two laser sources, we also examine the feasibility of using our polygon scanner for surface cleaning applications and optimize the scanner parameters to improve the efficiency of laser cleaning. We believe that we will design an innovative solution for ultrahigh-speed scanners.

We propose and discuss a structure and performance of a projector with compact appearance and enlarged exit-pupil for NED. A NED with 4-layer holographic waveguide is designed to verify the performance of the projector. The projector can provide images with a FOV of 52° and an exit pupil diameter of 8mm at an exit pupil distance of 30 mm, and the NED system could be achieved a FOV of 52° with the eyebox of 6mm. The design provides the projector with a wide FOV and large exit-pupil, making it a potential technique to be applied for wide-angle NED.

We will first present the optical design compromise between two interesting compact ring telescope solutions for imaging applications. In a second part, a description of the finalized prototype will be proposed. It will focus on the opto-mechanical principle but also on the manufacturing quality obtained with diamond machining. Finally, we will detail all the characterizations on the prototype with and without sensor: optical performances evaluated in the laboratory as well as a set of images acquired on different realistic scenes. We will conclude and present perspectives for future versions.

The proposed off-axis optical design of HMDs consists of an image source, a relay lens, and an ellipso-toroidal combiner. The ellipso-toroidal mirror is employed to improve the field of view and make the system compact. The relay lens is a Cooke triplet variant, which compensates for the aberration introduced by the combiner. The diagonal field of view achieved for the HMD system is 40º with an exit pupil diameter and distance of 10 mm and 50mm respectively. The MTF achieved for the targeted field of view is 0.2 at 64 cycles per mm according to the Nyquist frequency of the OLED source, which has a pixel dimension of 7.9 µm.

Solar Ultraviolet Imaging Telescope (SUIT) onboard the Aditya-L1 satellite consists of an off-axis RC telescope with a set of science filters and a CCD detector designed to take high-resolution images of the solar disk in different band pass filters in UV region between 200-400 nm at Sun-Earth Lagrange (L1) point. SUIT is a unique telescope of its kind with challenge to design a telescope which can accommodate a field of view of 0.7964 degrees (Field extending up to ~1.6 Solar Radius) with minimum number of components. Traditionally, two-mirror on-axis RC-telescope with field correcting optics is used to design such telescopes. However, due to limited number of refracting materials available in the transmission range of 200-400 nm, a critical compact system with minimum optical components and an off-axis RC-telescope is designed with diffraction limited performance.This paper describes in detail the optical system design of the SUIT optics , the test configurations of the primary and secondary mirror, performance parameters like encircled energy of the Spot and the Modulation transfer function(MTF) for the required nyquist frequency.

We present highly miniaturized optical and electronic components for a two-channel fluorimeter with pin photodiodes with a very small detection limit (with an excitation of 100 μW and 590 nm, we can detect one nW at 650 nm). The central component consists of newly developed dichroic beam splitter cubes made of quartz glass with an edge length of 3 mm. The wavelength ranges are between 560 and 750 nm. In addition, very thin optically direction-selective filters have been developed to reduce stray light on the photodiodes. Here, glass substrates with a 100 μm thick Si-layer were used. This silicon layer was structured using inductively coupled plasma etching (ICP). Breakthroughs measuring 40 μm by 40 μm were created with inner walls made of black silicon. The transmission of these filters is 0.4 at angle of incidence at zero degrees and is less than 0.01 at angles of incidence greater than 13°.

A detailed case study is done on the optical design of phakic Intraocular Lenses (pIOLs). Depending on the position of pIOL in the human eye, three possible types of pIOLs have been simulated in Zemax Opticstudio - Anterior Chamber phakic IOL - angle supported IOL or fixated on Iris and Posterior Chamber phakic IOL. The myopic condition of the eye could be attributed to mainly two reasons - 1) elongation of the eyeball or increase in the axial length, 2) increase in the total power of the eye beyond 60D. In this study, the model of human eye (high myopia) with pIOL is simulated and its optical performance has been evaluated. The comparison of performance parameters like spot radius, MTF and Strehl ratio show that the pIOLs in high myopic eyes can achieve optical performance close to that of the normal eye.

Co-phasing is the critical factor for resolution enhancement in segmented or sparse aperture telescopes. We have been developed the image-based piston correction method via an optimization procedure, which is suitable for both point objects and extended scenes. In this paper, the summary of the proposed method will be presented.

This paper presents a magnetic field optical sensor developed for measuring the magnetic field in a brushless DC motor used in GUCnoid 1.0 humanoid robots. The sensor employs advanced optical techniques, providing real-time measurements with high resolution and linearity. Experimental tests on the GUCnoid 1.0 motor validate the sensor's accuracy under varying operational conditions. The data acquired by the sensor is used for closed-loop control algorithms, enhancing motor control and overall system performance. This compact, low-power sensor contributes to humanoid robot technology by offering a reliable solution for magnetic field measurement in BLDC motors, enabling improved control precision and energy efficiency.

Lenslet-based integral field units are notable for the large field of view and high throughput. But the structure in the image plane of these instruments is inherently highly complex due to the spatial and spectral packing of information, and often has large dynamic range between neighbouring pixels. This may make their optical design challenging in terms of the image quality and the technological complexty. We consider design options to implement such an instrument for a 40 cm - class telescope with a focus on the fast spectrograph camera design. It is demonstrated that with a relatively simple and compact optical system relying mainly on off-the- shelf components it is possible to reach the spectral resolving power up to R390 and cover at least 3.75′ angular field. It may be reached with a F/1.2 Schmidt camera or a custom 5-lens objective, using a curved sensor.

In the present work, we consider application of the multiplexed dispersive unit principle for building a wideband spectrograph for the 6-m BTA telescope at Special Astrophysical Observatory. It is designed for the Nasmyth F/30 focus and should cover the range from 365 to 700 nm with the spectral resolving power up to R2430. The spectrograph equips an image slicer to operate with a telescope image blurred by the atmospheric turbulence. It uses relatively simple commercial optics for the collimator and camera part and a custom grism, combining two prisms and three volume phase holographic gratings, which form spectral images in three sub-bands. The expected throughput varies from 25 to 70%. We present an analysis of the instrument performance paying more attention to the diffraction efficiency curves tuning and tracing the diffraction ghosts.

This study presents an in depth system modelling of silicon photonics biosensor system, integrating a ring resonator, microfluidics, photodiodes, and CMOS evaluation for enhanced biosensing. Central to the system is a ring resonator optimized for high sensitivity, facilitating precise biomolecular interactions and detection. The modelling incorporates microfluidics for efficient sample delivery, reducing volumes and speeding up analysis, ideal for high-throughput screening. Photodiodes convert optical to electrical signals, improving sensitivity and response time. The CMOS module processes these signals, enhancing signal-to-noise ratio and allowing device miniaturization. Advanced surface chemistry techniques are used for functionalization, ensuring selective detection of target biomolecules.

This paper introduced an improved design of a previously developed large aperture 2D micromirror featuring cascaded torsional beams on the frame to enhance the robustness and field of view(FoV) of the micromirror. The primary goal of this improvement was to increase the scanning angle without compromising robustness. the increase in scanning angle was achieved by reducing the stiffness of the torsion beams and the mass moment of inertia of the Ti-frame. These adjustments were made while ensuring a minimal impact on the micromirror's first-order resonant frequency, thereby preserving its robustness. The micromirror is composed of an FPCB layer with embedded coils for actuation, a gold-coated silicon layer serving as the reflective surface, and a Ti-alloy layer providing structural reinforcement. In this improved design, the Ti-Alloy frame optimization expanded the FoV to 23.8°±0.2 horizontally and 7.9°±0.2 vertically at 5V actuation. This represents a 46% increase horizontally and a 79% increase vertically compared to the original design. Additionally, the first-order resonance frequency was tested at 275Hz for horizontal actuation, only 5.2% lower than the original design.

We focus on freeform lens design for irradiance tailoring on tilted target planes. We develop a differentiable Monte Carlo ray tracing for simulating freeform lenses based on the computational graph. Such a simulation facilitates the evaluation of irradiance distribution on tilted target plane by incorporating differentiable 3D coordinate rotation. We then efficiently update freeform surface parameters through back-propagation while constraining the surface curvature. The design example demonstrates that the proposed method can effectively generate a high quality uniform irradiance distribution on a tilted receiver.

A small fundus optical imaging system based on aspheric technology and non-coaxial illumination is proposed,which can resolve the structure of 6 um，realize miniaturized design, improve the versatility of fundus examination, and provide technical support for the intelligent diagnosis system.

ANSER Atmosphere (AT) is the second mission of INTA’s SmallSat constellation program. Its main objective is the study and monitoring of greenhouse gases, air quality and polar ozone by absorption spectroscopy. It is composed of a cluster of four CubeSats flying in formation, each of them comprised of 6U. The main payload of each CubeSat consists of a catadioptric telescope (1U) and a refractive spectrometer (2U) each of them working in a different spectral range from UV to SWIR. The optical design of the spectrometer, which spectrally disperses and analyses the energy collected by the telescope, is based on a reflective diffraction grating with a slit at the entrance. Due to the fact that this is an atmospheric observation mission and the precision required for the measurements, it is necessary to eliminate the polarization of the incoming light. For this reason, depolarizers have been included in the instrument design.

Metasurfaces are promising disruptive technology for diverse applications: it can be a encouraging candidate to overcome the limitations of conventional diffractive optical element as the limited field-of-view (FoV) and the limited diffraction efficiency (DE). In addition, due to their high flexibility in terms of design, metasurfaces with fully arbitrary far-field patterns can be fabricated. In most commercial scanning imaging LiDAR, a compromise has to be found between the FoV and the frame rate. For flash LiDAR systems, the concession must be made between the FoV and the depth of field. To overcome these limitations, metasurfaces have been proposed as a good alternative to conventional components, for both detection and illumination. However, the design, the fabrication and the characterization of those functionalized surface remain a challenge. In this paper, we demonstrate the advantage of design flow based on inverse design capability for the generation of a metasurface targeting beam steering for sensing. Then a discussion will be conducted on the characterization of the metasurface as well numerically than experimentally.

The hologram is an ideal method for displaying three-dimensional images visible to the naked eye. Metasurfaces consisting of subwavelength structures show great potential in light field manipulation, which is useful for overcoming the drawbacks of common computer-generated holography. However, there are long-existing challenges to achieving dynamic meta-holography in the visible range, such as low frame rate and low frame number. In this work, we demonstrate a design of an optical-addressed dynamic meta-hologram, which can achieve good meta-holographic display with large frame numbers and extremely high frame rates. Based on this design, we realized the world's first practical interactive meta-holographic prototype and optical-addressed pixel-controlled metasurface spatial light modulator. This method can satisfy the needs of a holographic display and be useful in other applications, such as laser fabrication, optical storage, optics communications, and information processing.

Both lighting and camera systems must be highly integrated in optical systems that recognise food. Homogeneous light distribution throughout the region is required in food identification systems in order for the food to be detected by the camera, cooking, and frying circumstances to be clearly seen when the instant food photo is given to the user. Although there is no single proper method for ensuring light homogeneity in a specific region, particular design and optimisation are necessary. In camera products, optical design and analysis studies should be designed using a specific methodology. In camera products, optical design and analysis studies should be designed using a specific methodology. First, lighting and camera designs should be created, followed by determining the number and location of light sources, and last, optimal conditions should be discovered by analysing the entire optical system in conjunction with the camera.

The ESA LSTM mission requires very strict optical performance. The complexity of the optical system and the need for drastic accuracy requires high-performance and perfectly controlled metrology. We have developed an OGSE including active optic that simulate the telescope performances in order to co-align VIS&NIR LSTM imagers. In order to validate the performance of the OGSE, we fully simulated the different stages of calibration and use of the OGSE in the optical design software (CodeV) by integrating the deformable mirror, the wavefront sensor and the active loop.

Research and developments on thermal infrared zoom lenses over the last decade (2010 onwards) will be surveyed in this talk, with a special focus on mechanically compensated continuous zooms for cooled detectors. During the time period under consideration, SWaP (Size- Weight and Power) optimized optomechanical systems were realized, to compactly fit zoom imaging functionality in previously unconventional platforms such as UAVs (Unmanned Aerial Vehicles). Dual band zoom systems, imaging in both the Mid wave (MWIR) and Long Wave (LWIR) thermal regimes have been explored. There has been considerable research and development activity in the field of chalcogenide material technologies which open up design possibilities for broadband transmission applications (VIS through LWIR). The feasibility of zoom functions implemented via non-traditional elements such as metalenses, Alvarez lenses, deformable mirrors, and multi-layer Diffractive Optical Elements (MLDOE) have been demonstrated.

The field curvature has been a long-term problem optical designers had to deal with, to propose flat corrected field instruments. Combinations of highly aspherical optics, TMA configurations, achromatic doublets or field flatteners are often used to reach good optical quality across the image. Allowing designers to play with the parameters of the field’s shape is offering them a brand-new game field. The possibility of curving the CMOS sensors to fit curved/aspherical/freeform shapes of focal surfaces has been studied for the last 20 years and led today to different applications and prototypes. We present in this article 1/ the parameter studies we performed over a large set of optical designs showing the gain offered by this approach, 2/ the CMOS sensors curving process and performance over a large set of prototypes, 3/ Optical systems that have been produced with this technology and 4/ the roadmap related to the development of curved-sensors based instrumentation for astronomy with the CASTLE telescope project and physical sciences through the Auroral UV Imager program led by ESA, and the IMANCES project led by the Neurosciences Institute INT.

On the 26th September 2022, the NASA DART spacecraft successfully completed its kinematic impact with the binary asteroid Didymos. Hera is the European component of this ESA–NASA AIDA, double spacecraft mission. HyperScout is a commercial miniaturized Near InfraRed spectral imager developed by cosine Remote Sensing, to be used for the observation of the binary asteroid Didymos as part of the Hera mission. Some of the mechanical challenges of this deep space mission include the interface to the spacecraft, the thermal environment, effects on optical performance, and more. This paper will describe how cosine has tuned its existing product to meet these challenges, with analyses, tests and experimental results to discuss.

A miniaturized tuneable light source is demonstrated using a piezo-actuated Fabry-Pérot Interferometer (FPI) combined with a broadband light source. We built a test setup combining the tuneable FPI with a white light source and conducted a spectroscopic investigation of the light produced by the tuneable light source under applied voltages. We developed a theoretical model and experimentally verified it by studying optical performance like transmission and spectral resolution. The influence of the thickness variations of the coated multilayer structure on the spectral resolution is analyzed, and a combination of six different FPI modules is proposed to develop a miniaturized broadband tuneable light source covering the wavelength range between 360 nm and 1700 nm.

Sentinel-4 is an imaging UVN (UV-VIS-NIR) spectrometer, developed by Airbus under ESA contract in the frame of the joint EU/ESA COPERNICUS program. The mission objective is the operational monitoring of trace gas concentrations for atmospheric chemistry and climate over Europe. Sentinel-4 will provide accurate measurements of key atmospheric constituents such as ozone, nitrogen dioxide, sulfur dioxide, methane, and aerosol properties. The Instrument Proto Flight Model (PFM) was aligned in 2020 and after undergoing the Calibration & Characterization campaign was finally integrated onto the Meteosat Third Generation (MTG-S) platform. This paper gives an overview of the Flight Model 2 optical integration and alignment activities performed at the Airbus premises in Ottobrunn, Germany, during the first half of 2023. The results of the optical tests, performed before and after transition from ambient laboratory conditions to the operating conditions reproduced in a thermal vacuum chamber, will be presented and compared to those of the PFM instrument.

Bessel beams, known for maintaining focus over long distances, find applications in imaging and laser ablation. To enhance ablation efficiency, generating sub-micrometer Bessel beams is essential, demanding complex optical systems. Traditional optical software, designed for ray tracing, can be challenging for this task. This study explores how we can use optical software to create and optimize this unconventional beams. The research involves high numerical aperture systems, the influence of polarization, and the use of diffractive optical elements. Numerical findings are compared to experimental results, highlighting the potential of software-assisted beam design for various applications.

Stock lenses are attractive components in optical system design, offering lower cost and ready availability when compared to custom lenses. However, the lack of effective (optimization) tools to design systems with stock lenses often leads to a manual, thus time-consuming and highly iterative design process with low success rate and clearly non-ideal results. In this work, we present an automatic optical design tool that uses only stock lenses from known suppliers to generate lens systems directly from the specifications and constraints given by the user, without requiring any nominal starting or reference design. To efficiently master this complex problem of selecting working stock lens combinations, our proposed tool makes use of the ‘First Time Right’ design method to generate constraint stock-based lens systems of both finite and infinite conjugate configurations from scratch. We will demonstrate and discuss the extensive and fast exploration of stock lens solutions offered by the stock lens-based design tool using several- practical lens design examples. These results clearly highlight the tool’s capabilities for streamlined stock lens-based system exploration.

Focused Narcissus for a MWIR zoom system has been measured and reproduced with simulations in Zemax Optics Studio. These simulations allowed to isolate the cause of the focused Narcissus, that cannot be eliminated with a One Point NUC algorithm. Therefore, this needs to be controlled establishing solid requirements for Narcissus control during the design process. This papers present details on the testing and simulations results, together with some aspects to consider while designing a continuous zoom in the infrared wavebands.

Future large-scale spaceborne optical instruments for Earth observation or astronomy will call for large primary mirrors with very challenging performance specifications. At design level, our work focuses on improving the integration of mechanical, thermal and optical analysis in efficient iterative loops, to quickly lock-in on mirror designs which simultaneously balance mechanical and thermal constraints. We rely on a new automatic mesher called PAMPA which quickly generates parametric models, and is iteratively called upon by an end-to-end automatic workflow to evaluate the mirrors’ performance.

This paper provides an accurate and simple simulation workflow for Structural, Thermal and Optical Performance (STOP) analysis on complex optical systems. Applying this workflow to a High-Power Laser, we use Ansys Zemax OpticStudio for both optical design and wavefront analysis. Then Ansys Speos is used for optical heat load calculation on each component of the system. Finally, Ansys Mechanical is used to perform thermal and structural analysis, providing back this information to OpticStudio for wavefront error analysis and optical tolerancing. The workflow is fully automated thanks to Ansys System Coupling interface. Besides the ease of use, this workflow captures the impact of structural deformations and refractive index changes on the key performances of any optical system, accounting for opto-mechanical component contributions. The approach can be steady-state or transient.

Wood's unique combination of lightness and strength makes it a valuable resource with potential in various industries while also serving as a carbon sink. However, the diversity of wood species, particularly in temperate regions, makes it challenging to assess their mechanical properties for widespread applications. The wood manufacturing industry is seeking automated techniques, such as the "tracheid effect," to determine wood characteristics, especially in French wood species of all grades. This approach, although promising, has limitations and relies on Monte-Carlo simulations. Optics Studio, an optical design software, can enhance our understanding of the tracheid effect, enabling better wood fiber orientation characterization. This advancement aims to improve wood property measurement and optimize the use of secondary-grade wood in construction, furniture, and packaging industries.

The MMX Infrared Spectrometer (MIRS) is an imaging spectrometer aboard the MMX (Martian Moon eXploration) JAXA mission. A span of three and a half years separates the initial optical design studies for this instrument and the ongoing final tests conducted under vacuum on MIRS PFM (Proto-Flight Model) at LESIA facilities. This paper will describe the key stages in the optical architecture's evolution during the instrument's development, guided by a design-to-effectiveness philosophy. Following an overview of the mission, its objectives, and the optical requirements of the instrument, we will expose the trade-off between a dioptric and a catoptric design, resulting in a catadioptric design including four freeform mirrors, a plane-ruled grating, two lens assemblies, and a linear variable filter. Each optical sub-assembly will be detailed, presenting its primary as-built characteristics. The alignment tolerances and procedures will also be briefly explained. Lastly, the measured optical performances of MIRS PFM will be presented and compared to the theoretical expectations.

Understanding the history of a scientific field is crucial for grasping its depth. Optics, is no exception to that rule. Exploring its past enriches optical education, allowing students to trace the evolution of scientific ideas and learn from past challenges. Despite this potential, the history of smaller universities and notable figures is often overlooked. Since 2015, we have been preserving the scientific heritage of our laboratory by conserving, contextualizing, and exhibiting historical scientific documents and objects. This includes offering students internships that blend history and science, such as using Optics Studio to model Charles Féry's spectrophotometer from the 1910s. This approach demonstrates how modern tools can shed light on the historical roots of optics through the examination of historical artifacts.

In this study, we have used the policy-gradient based reinforcement learning approach to generate initial design for microscope objective lenses. The lens parameters within the defined ranges can be determined by the model based on the given specifications. The results obtained from our analysis suggest that the reinforcement learning model can generate appropriate starting points which expedite the convergence of the optimisation process.

Traditionally, gradient-index (GRIN) optics have been made by varying the ratio of two distinct materials or exchanging two components within a base material. This has largely been dictated by manufacturing methods. However, due to recent advancements in additive manufacturing, GRIN optics can now be composed of a blend of multiple materials (i.e., more than two). It can be shown that these new, multi-material GRIN optics possess numerous advantages over traditional GRIN optics, especially in the realm of color correction. Such advantages arise due to multi-material GRIN’s ability to separately vary the GRIN power and the GRIN dispersion, a feat not possible with only two materials. Additionally, when the GRIN power is allowed to vary along the optical axis, the GRIN dispersion can also vary along the optical axis. This means that a single multi-material GRIN element can have regions of both positive and negative dispersion, allowing for planar, achromatized elements.

Detection of electro-optical prescriptions is crucial for locating adversarial or threat optics. Advancements in sensor and sensing technology has provided threats in many forms, whether it be the traditional direct view optic, protected CCD camera or infrared focal plane array. The wide variety of sensing options is creating a more difficult scenario for detecting and locating threat optics using traditional retroreflection detection systems. The purpose of this paper is to describe a retroreflection system that makes use of a single broadly tunable source that is frequency agile that will provide a much broader detection range and is significantly harder to protect against.

Minimizing distortion throughout zoom is often one of the most challenging aspects of a zoom lens design problem. In traditional aberration theory, distortion is analyzed through the fifth Seidel Sum. However, distortion can also be expressed as a sum of pupil coma and a second term we call the natural distortion, which is a quantity that is only dependent on the paraxial chief ray angles in object and image space. Examining distortion through the natural distortion and pupil coma provides new insights into the origins of distortion in optical design. Zoom lenses are a particularly interesting class of systems to analyze in this context because the distortion correction is typically more difficult than a prime lens. Using the natural distortion and the pupil coma, we explain why distortion is so difficult to correct in zoom lenses, as well as provide insight into trends in the behavior of distortion in commercially available zoom lenses.

Stress birefringence may lead to appreciable wavefront and polarization errors, especially in polarization sensitive systems. The effect is becoming increasingly important, as complex polarization-dependent and polymer-based optical systems become more prevalent, impacting imaging quality in systems such as Augmented and Virtual Reality. Advancements in multiphysics simulation, including the combination of Finite Element Analysis and optical simulation, enable optical designers to simulate and assess the effect of stress birefringence in the final performance of the optical system. We have developed a simulation method that combines 3D fitting of FEA non-uniform stress data with non-uniform gradient index ray tracing, calculating the polarization and wavefront error from the propagation of the wavefront through the system. We demonstrate the model with practical examples, in which we analyze the impact of stress birefringence on the polarization and image quality. The robustness of the technology is demonstrated with different types of stress data and optical systems.

Optical systems used in aerospace applications are often subject to random vibrations, and time is a new factor to consider. The sensor integration time draws a line between slow (drift) and fast (jitter) vibrations and resulting pointing errors. We propose a new Multiphysics workflow to assess the performance impacts in optical systems using finite elements analysis (FEA) results. Both structural data (surface deformations, rigid body motions) and thermal data (temperature gradient, automatically converted into a gradient index) are used to update the nominal design. New tools have been developed to easily consider series of these datasets, to fully understand vibration impacts and their time dependence.

For a given f-number, refractive optical systems are traditionally favoured over reflective systems due to their increased diffraction-limited field of view and preferable form factor. With commercial emphasis propelling the requirement of wide field of view compact reflective systems with, the first order design parameter of distance between telescope mirrors can be revisited. We present an analytical study where the optical performance across the field of view is investigated for a two-mirror telescope system as a function of separation between the primary and secondary reflectors. It is proposed that as this separation approaches the thickness of an aplanatic refractive singlet of comparable f-number, the diffraction-limited field of view of the reflective telescope can be extended beyond the expected field of traditional reflective systems. Here, we consider the relationship between reflector separation and field of view for optical systems with f-numbers of f/10 and f/5. For λ=1 um, an aplanatic singlet with a 1 degree field of view is compared to that of a Richey-Chrétien telescope.

We present the design and fabrication of a multicomponent optical system for LiDAR applications. The system comprises four stages: a commercial cylindrical lens, a custom freeform trilobated lens, a set of three custom reflective diffraction gratings, and a custom monolithic array of nine freeform mirrors. This optical system is coupled to an on-chip linear Optical Phase Array: the combination of linear beam steering provided by the OPA, and orthogonal linear steering achieved by the diffraction gratings results in a beam scan over nine directions in 3D. All the custom components have been designed and fabricated at VUB – B-PHOT’s Photonics Innovation Center. We discuss the details of the optical design and of the manufacturing.

Concerning the general performance of an imaging spectrometer, the correction of spot size and distortion has a great impact on the resolution and efficiency. The broken symmetry due to dispersive elements makes it difficult to correct higher-order aberrations with only rotationally symmetric surfaces. Freeforms can be introduced in such systems to specifically correct the aberrations caused by asymmetry. Due to the off-axis structure, the classical analysis of aberrations based on a paraxial reference is not valid anymore. Therefore, a higher-order aberration analysis tool is developed based on the mixed ray-tracing method. The essential concept is a flexible switch between the real and generalized paraxial ray trace to obtain the full-order surface-decomposed aberrations in arbitrary systems. The method helps maximizing the correctability of freeforms with higher efficiency in the design process in an imaging spectrometer. The advantage of the method to select the best appropriated freeform surface is demonstrated with a multi-element example of a spectrometer, where the correction and the use of a freeform is not easy and obvious.

For adaptive optics ophthalmoscopes, it is critical that both the field and pupil conjugate are wellcorrected for the adaptive optics to properly correct for the intrinsic aberrations of the eye. The need to correct an additional set of conjugates can present a unique challenge to an optical designer seeking to design a zoom system, as it makes creating a first order starting point much more difficult. Here we present a method for analytically generating zoom kernels consisting of three moving lens groups that controls the imaging of 2 simultaneous conjugates. Our first order starting point generator takes as input the powers of all lens groups, if they are refractive or reflective, and some basic information about magnification range and then calculates lens positions through zoom such that the afocal magnification changes from A to B while the pupil magnification changes from 1/A to 1/B. We used this capability to design an all reflective 1.75x–3.5x zoom relay for integration into an adaptive optics ophthalmoscope. We incorporated freeform optical surfaces to correct for the aberrations introduced while unobscuring the design and achieve the required performance.

We want to present the result we obtained by optimizing a four-mirror system to achieve a wide field of view (65°x13.5°) with a high angular resolution of 10 arc seconds. Our system is designed in a context of situational awareness which adds a few constraints: we work on a wide spectrum covering the visible and the near infrared, our volume has to be limited to allow it to adapt itself to its carrier, and the design has to be simple enough to guarantee a certain robustness of manufacturing and alignment.

HARMONI is the first light visible and near-IR integral field spectrograph for the Extremely Large Telescope. It covers a large spectral range from 470nm to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes (including a High Contrast capability) - or with Non Adaptive Optics. The project is preparing for Final Design Reviews. In this paper, we present the optical design of the Pre-Optics for Final Design Reviews, 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. This involves many functions, mainly relaying the light from the telescope focal plane to the integral field unit focal plane via a set of interchangeable scale changing optics. The pre-optics also provides components including a focal plane mask wheel, cold pupil masks, spectral order sorting filters, a fast shutter, and a pupil imaging capability to check telescope/instrument pupil alignment.

This paper describes the challenges involves in designing a space qualified Raman Spectrometer for Lunar exploration. In order to perform under the harsh environment of moon requires a very sensitive, compact, lightweight, and robust Raman instrument that can also be carried by a rover. ISRO is developing a Raman instrument for its future lunar missions with science objective of identifying minerals constituents of the lunar soil with a resolution of 8cm-1 in wave number range of 150 cm-1 to 3800 cm-1. The current design is carried for measurement in-situ at a distance of 20 mm. It is a monostatic design, in which a common optics is used for laser focussing, sample positioning and for receiving signal from the spectrograph. This makes the system free from Laser source and receiver misalignment errors due to the common path. Additionally, the optimization considerations for mass, volume, and sensitivity highlight the challenges of developing instruments for space missions, where every gram and cubic centimeter counts. The design is based on Volume Phase Holographic(VPH) transmission grating with 1500lp/mm grove density.