This PDF file contains the front matter associated with SPIE Proceedings Volume 12078, including the Title Page, Copyright information, and Table of Contents.

Most virtual reality (VR) headsets nowadays use conventional, rotationally symmetric optics to create a wide field of view (FOV > 90°) virtual scene enabling the required “immersion” or “presence” feeling. These optics require a long total track length (TTL, distance between the actual panel displaying the contents and user’s pupil) to work well, and headsets become very bulky. The so-called CLOVER is an optic, compatible with VR and video-see-through mixed reality (MR) able to work around the TTL problem by using a freeform multi-channel, light folding approach. In its simplest version, it can reduce the TTL down to a half, compared to conventional solutions, for the same FOV and angular resolution. Along with a review of the original 4-channel CLOVER, this work shows recent results of upscale versions of the optic that utilize myopia and color correction, pupil tracking and staggered surfaces to, respectively, avoid the need of prescription lenses, improve the image quality for all colors, rise the resolution (by a 20%) and reduce the size (20% TTL reduction) of the precursor.

Recently, the general exact equation to design a stigmatic lens has been found and extensively studied. In this manuscript, we discuss what we have learned by obtaining such an equation and its implications.

We present a device based on liquid crystal and via Pancharatnam-Berry phase to generate Poincare beams by the coherent collinear superposition of two Free-Form Dark Hollow (FFDH) beams. We generate beams with spatially-variable polarization encoded on their cross section showing disclinations in the azimuth orientation and mappings of the Poincare sphere onto the transverse mode. We report generated beams characterized by nonuniform rotation rate of the local polarization azimuth in different polarization configurations, radial and azimuthal, lemon and star disclinations, and other richer and complex higher-order disclinations, by using tailored space-varying-axis plates based on liquid crystals.

CMOS compatible on-chip photonic nanojet (PNJ) has been designed. The design consists of a silicon hemisphere on a silicon substrate. Simulations show subwavelength PNJs with potential applications in focal plane arrays and microfluidic devices.

A hyper-aspheroid is a surface of revolution (with a specified vertex curvature) that nears or extends beyond where it’s parallel to the axis. The familiar ‘hyperhemispherical’ is one limiting example, but the superconic and rational Bézier approaches are more flexible. Both will be applied to the redesign of a condenser system from the late Juan Rayces’ Eikonal program but using the author’s own design code.

1st-order color contributions of Seidel often lead to inaccurate results in complex designs. An extension of Seidel's color theory is applied and shows how different color aberrations are balanced for correcting a complex optical design example.

Compensation methods for glass tolerances: performance and manufacturing considerations

Rudolf Kingslake championed the importance of lens design fundamentals and, with the introduction of computer- aided design, was wary of what the future held for theory. The transition from ray tracing taking minutes to taking fractions of a second has changed the way lens design is taught and approached. Today's powerful computational tools have largely supplanted fundamentals, yet the synergy of thoughtfully combining theory with numerical capacity is what leads to the greatest insight, most efficiently. Recently uncovered materials of Professor Kingslake's highlight this fact and suggest how lens design's past has enduring importance today.

An innovative highly symmetrical laser scanning microscope using a toroidal reflective scan lens and a highly efficient, low-noise collection system based on a modified Offner configuration. The system was originally developed for applications in two-photon microscopy (TPM). The optics provide for a perfect scanning spot along an arcuate line with no off-axis aberrations. On-axis aberrations are corrected with a free-form compensator placed on the input beam. The perpendicular scanning dimension to the scan line is obtained by linearly translating the whole microscope with respect to the specimen or moving the specimen. The design examples presented are for a 30-mm scan line and an NA of 0.5, and are both refractive and all-reflective, thus with minimum dispersion to prevent pulse broadening.

10 Years of development of first-order search and evaluation tools for the design of complex zoom lenses.

Missions to Mars prior to the year 2020 have indicated that Mars once held liquid water. This may have provided an environment suitable for the existence of microbial life. The primary science mission of Mars 2020 is to explore the past habitability of Mars and to prepare and cache a set of samples for potential return to Earth by a future mission. A second mission of Mars 2020 is to demonstrate technologies that can be used for human exploration of Mars. The mission duration of Mars 2020 is 1 Mars year, 668 sols or 1.88 Earth years. To fulfill the mission of Mars 2020, the National Aeronautics and Space Administration (NASA) chose to send a rover, Perseverence, to the surface of Mars. Perseverance is the latest and most sophisticated Mars rover from NASA. It was launched from Cape Canaveral, Florida on July 30, 20201. After a cruise of approximately five and one-half months, it was successfully delivered to Jezero Crater on the surface of Mars on February 18, 2021. The pictures and video of its delivery were viewed with anticipation and awe around the world. However, some of us waited with equal anticipation for another moment, the posting of the first Mastcam-Z images. The Mars 2020 rover, Perseverance, includes 25 cameras, including 2 on the helicopter Ingenuity. There are 16 engineering cameras and 7 science cameras. Two of the science cameras enable the first-ever color imaging in stereo at variable magnification. These two cameras are the Mastcam-Z cameras, which are both mounted on the Remote Sensing Mast, separated by approximately 244 mm. The two Mastcam-Z cameras each make use of the first zoom lenses in interplanetary or deep space applications, which is the reason for the “Z” in the name of the camera (Mast Camera Zoom). In addition to their zoom capability, the lenses can be focused over a broad range of object distances. The optical design of these lenses is interesting in its development and deployment.

Methodology for the rapid design of an objective lens for multiphoton microscopy from off-the-shelf lenses with no a priori design.

Due to a serious pandemic scenario, the surface disinfection process using monochromatic light sources based on UV-C LEDs is becoming more and more required. A brief review of the optoelectronics parameters of the devices based on UV-C LEDs light sources and the UV-C dose required to achieve a 99,9% of inactivation on surfaces (3 log reduction) of human Coronavirus (HCov-OC43 used as SARS-CoV-2 surrogate) has been prepared. A new parameter labeled as “homogeneity factor” has been defined to be applied on a bounded area where the homogeneity of the distribution requires a reliable average dose.

Performances of optical medical devices determine diagnosis and therapy quality. I will overview NIST-developed standards for evaluating imaging techniques: diffuse optical imaging, optical coherence tomography, and photoacoustic microscopy.

In this invited paper, a simple and efficient matrix formalism is presented for computing aberrations in plane-parallel freeform mirror systems. The approach is flexible and can be easily generalized to arbitrary aberration orders and/or to systems with different symmetries. As an illustration, we derive analytical expressions for all 2nd and 3rd order image and pupil aberrations in plane-parallel confocal N-mirror systems. Some design examples are also presented and discussed.

We proposed a method to automatically eliminate the obscuration in the design of off-axis mirror systems without plane of symmetry. Off-axis settings and local surface expression are designed to simplify the system representation. Obscuration error function is established based on the positional relation between the proposed mirror boxes and ray boxes, and through function optimization, the obscuration is eliminated. The method is demonstrated by two examples, indicating its ability to eliminate obscuration for totally off-axis mirror system and the searching for such systems from co-axial starting points.

We present a tunable LED-based illuminator using custom arrays of Alvarez lenses with commercially available secondary optics. Design methods and characterization of the system performance are discussed.

A high-resolution adaptive-driving-beam has been created based on a projection optical system with a pixelated μLED. Covering full FOVs of 40° and 24°, respectively, we will discuss the performance of the combined system.

Axial as well as lateral color aberrations in broadband optical systems can efficiently be corrected by using diffractive optical elements (DOEs). However, DOEs such as kinoforms consisting of only one material are not suitable for high-quality optics because of straylight in spurious diffraction orders. The amount of stray light can significantly be reduced by using so-called efficiency-achromatized DOEs (EA-DOEs), which consist of a material pair whose refractive indices fulfill a specific material condition. Unfortunately, manufacturing of EA-DOEs is very challenging because the grating structures are subject to tight fabrication tolerances. Therefore, only few broadband optical systems with EA-DOEs are on the market. Here we show that DOEs in broadband optical systems can surprisingly be replaced by refractive doublets made of materials that fulfill the material condition for EA-DOEs. As opposed to the EA-DOEs themselves, these purely refractive replacements do not suffer from stray light. In addition, from a theoretical point of view, our result allows for understanding the effect of DOEs in optical designs by classical refractive optical design theory.

The aim of this paper is to review the existing techniques for optical glass selection to be applied during the design of colour corrected lens-based systems. Special attention has been given into their application to optical instrumentation working along a wide spectral range (VIS and SWIR). Finally, a case study introducing glass selection strategies applied to the design of lens-based diffraction limited instrumentation is described.

Curved sensors bring a paradigm shift in the design of optical systems, enhancing performance and unlocking new scientific and consumer applications. We present our wafer-level shaping capability enabling to reach various sensor shapes.

Multichannel imaging systems consist of multiple channels which could have different imaging characteristics (field-of- view and angular resolution). The different imaging characteristics would enable the imaging system to achieve a variety of functionalities. In our approach, we designed and demonstrated a miniaturized six-channel multiresolution imaging system which allows a relative magnification ratio of up to 10 times between the different channels. The imaging system consists of two double-sided lens arrays replicated in-house in a polymer material through hot embossing. The mold inserts of the lens arrays were made in brass through ultra-precision diamond tooling. The replicated lens arrays were assembled together with a baffle block aiming at reducing crosstalk between neighboring channels. The assembled system was then integrated with a Sony full-frame image sensor and tested in proof-of-concept experiment. The acquired images using the integrated imaging system met the expectations compared to the simulation. This opens up new possibilities and functionalities in a compact imaging system.

In traditional confocal microscopes, high resolution and large fields of view are difficult to achieve simultaneously by microscope objectives, which limit the space-bandwidth products of the systems. With the proposed diffractive lens arrays, an objective with a low numerical aperture can have much higher resolution while maintaining its large field of view. Application of the diffractive lens arrays in fluorescence microscopy is presented in this work. The resolution enhancement is demonstrated by experiments with the fluorescent beads.

The Maxwell fish eye lens is a gradient index design from 1854 with a spherically symmetrical gradient. In one version the gradient index ball has an index of refraction of 3.0 at the center and 1.5 at its outer surface. It images perfectly any point on its surface to a point on the opposite side of the sphere. The ray paths are arcs of circles. A diagram like Fig.1 can be found everywhere in textbooks or on the internet. Fig 1. .Maxwell gradient index fish eye lens with spherical symmetry. In 1991 at the OSA annual meeting I pointed out that if a reflecting coating is placed on the outside of the ball then any ray from a point #1 on the surface will go to point #2, reflect and go back to point #1, reflect and continue around back and forth forever [1]. Then I showed by a very simple geometrical argument that such a system has a very unexpected property. Any point inside the volume of the ball is imaged perfectly, after just one reflection from the inside of the outer surface, to another point inside the ball with a magnification of -1.0 X. That means that the entire inner volume of the ball is perfectly imaged at -1.0X. After two reflections inside the ball every point is imaged perfectly back onto itself with a magnification of +1.0X. Since every point inside the gradient index ball is imaged perfectly after one inside reflection that means that any interior flat surface is also perfectly imaged to another interior flat surface. That type of perfect system had never existed before, of perfectly imaging a flat surface that is real to a flat image that is real. Table 1 shows how that new design from 1991 compared to the very few previously known perfect imaging systems. The perfect flat object and image are not in air, however, but are buried inside the gradient index ball. Point

Panoramic photography has an old history, mostly because since the beginning of the photography around 1840, we try to capture the world we see. The fascination for Panoramic image was and is still remains today.

A recently proposed concept for the Next Generation Arecibo Telescope involves an array of tightly packed small dishes [1]. In support, we present mitigation methods for grating lobe effects inherent in regularly spaced aperture synthesis.

With advances in optical material design, it is now possible to expand the waveband for IR imaging systems. This paper will focus on evaluating and comparing optical designs that use newer materials that have been developed from NRL (Naval Research Labs), and materials that are readily available material to design. A 3x zoom lens will be used for these comparisons to determine if there is a reduction in the size, weight and power of the lens system.

In physics and engineering, abstract spaces composed of different system parameters allow visualizing fundamental laws and employing geometrical tricks. Here we discuss some examples for the study of imaging and nonimaging optical systems.

Some useful displays that reveal structural performance of lens systems are presented and discussed. They are useful for gleaning into how lenses work, their problems, and their imaging potential. An imaging simulation of a square wave is also presented to complement MTF plots.

Waveguide combiners are a key component of Augmented Reality displays, but the process used to design them is significantly different from lens design, and therefore a new course is required to train designers.

Multi-order diffractive (MOD) lenses provide solutions for large transmissive telescope arrays. Methods to correct the classical and MOD-specific aberrations to achieve near diffraction limited performance over astronomical R-band are discussed.

A theory of correcting residual change in focal length with wavelength is presented for high-harmonic diffractive lenses. The theory is based on a multiple-order diffractive (MOD) lens in combination with a stepped plate called an Arizona total energy color corrector (AZTECC) lens. Results indicate that best performance in terms of on-axis focused irradiance versus wavelength is found when low-dispersion glass is used for the AZTECC lens. A single-order diffractive Fresnel lens (DFL) in combination with the AZTECC lens makes the system achromatic over a wide bandwidth.

Gradient-index (GRIN) optics are commonly optimized with pre-determined materials, but the material choices limit the solution space of optimized index profiles. If the dispersive properties of the materials generating GRIN can be optimized, the performance of the optics can be further improved. This paper proposes a material concentration-based GRIN representation to replace the widely-used index-based representation, allowing simultaneous optimization of materials and the GRIN profile. The paper also proposed an efficient iterative algorithm capable of calculating the refractive indices, Abbe numbers and partial dispersions of material pairs from the optimized GRIN profiles. The new representation and the algorithm are used to optimize an F/2.5 GRIN singlet to diffraction-limited performance over the visible spectrum.

The diffraction efficiency of conventional diffractive lenses is typically analyzed using the complex Fourier series expansion coefficients. While conventional diffractive lenses typically target high diffraction efficiency in a single diffractive order, applications such as multifocal intraocular lenses seek high diffraction efficiency in multiple diffractive orders. Here, the complex Fourier series technique is generalized to handle these multifocal lenses, and applied to a novel trifocal intraocular lens design.

The design and performance of two multilayer polymer gradient index (GRIN) singlets are discussed. One singlet is an f/4 monochromat based on an axial GRIN geometry. The other is an f/6 achromat based on a spherical GRIN geometry. The design for each lens was modified to account for as-manufactured GRIN contours and final layer thicknesses. Asmanufactured performance for each lens was consistent with the performance of a commercial, air-spaced doublet predicted to be diffraction-limited at 532 nm, within the resolution of our setup for measuring the point spread functions of our lens elements.

The use of Freeform surfaces in illumination systems continues to increase. We explore the approach of combining a NURBS surface with an analytic surface and the impact on optimization and tolerancing.

Farfield beam shaping e.g. with diffusers often enlarges etendue. We discuss etendue conserving, high transmission beam shaping with irregular fly's eye condensers. Examples of automotive LED headlamp demonstrators using this design principle are presented.

In the field of Entertainment Stage Lighting there is wide variety of luminaires with beams of different intensity distributions. It would be advantageous if the optics allowed to adjust the edge sharpness.

In this work we theoretically confirm that the constant term of the measured signal of the Fringe-Resolved Autocorrelation technique using a two-photon absorption photodiode as sensor provides the same information as the intensity autocorrelation amplitude obtained from this technique. We achieve this result by computing the temporal intensity pulse distributions of focused femtosecond pulses around the focal region of an aberrated system and calculating both the intensity autocorrelation and the quadratic interferometric autocorrelation equation. Pulses with initial Full-Width Half-Maximum pulse widths of 50.0 and 20.0 [fs] were focused with a BK7 double convex lens.

A method for designing afocal achromatic doublet is presented. We have implemented an exact ray trace through a separated doublet lens considering a plane wavefront propagating along the optical axis. The analytic equation of both the caustic surface and the back focal length for separated doublet lenses are provided. Demanding that the back focal length tends to infinity, we impose the conditions to design afocal optical systems, obtaining sixth and fourth degree polynomials as a function of the radii of curvature. In order to produce an afocal achromatic optical system, we solve numerically a set of two nonlinear equations assuming two spectral lines. Therefore, we have two unknowns which are the curvature radii for both the front surface and the rear surface. The contribution of this work is to provide simple formulas for designing optical beam expander or reducer devices based on separated doublets.

Computerized ray-tracing has exponentially evolved since its inception. Various software companies have assisted the optical designer in optimization of lens designs. We introduce a fully automatic optimization method reducing optimization time ten-fold.

Zoom lenses have greatly improved to the extent that today many major performance characteristics are now equal to or come close to matching those of fixed focal length lenses. Some of these characteristics including size, weight, cost, producibility and general image performance are dependent on widely differing technologies. For example, optical design, coatings, refractive materials, surface types and the use of computers with suitable optical design software are just some of the technologies that when combined have driven the continuous development of zoom lenses and their optical designs.

Data-driven methods to assist lens design have recently begun to emerge, in particular under the form of lens design extrapolation: using machine learning, the features of successful lens design forms can be extracted, then recombined to create new designs. Here, we discuss the core aspects and next challenges of the LensNet framework, a deep learning-enabled tool that leverages lens design extrapolation as a more powerful alternative to lens design databases when searching for starting points. We also propose to borrow ideas and tools from the practice of machine learning and deep learning, and integrate them into standard lens design optimization. Namely, we recommend using automatic differentiation to power ray tracing engines, along with considering recent and powerful first-order gradient-based optimizers, and using data-driven glass models that are more suited for optimization than traditional variables.

Tolerance analysis and tolerance sensitivity optimization (desensitization) are important and necessary for manufacturability. However, compared to the optimization of optical performance, tolerance analysis is still time-consuming. A machine learning approach for the fast robustness estimation of lens systems is proposed. The results of the machine learning estimation and the other four different methods are compared with the results of the Monte Carlo analysis. The proposed model is added to the merit function in commercial software for optimization to reduce the sensitivity.

Tolerances on surface slope error raise the question of the spatial frequency range to which the specification applies. In this paper we develop a method of determining this range based on scalar wave diffraction.

I present a new aiming adjustment mechanism for riflescopes featuring partially-rotatable wedge prisms. The optical adjustment mechanism introduced in this paper does not require any laterally-moving components, off- axis optical components or turrets. Furthermore, the wedge prisms used in the system have no optical axis which makes the proposed solution immune to many types of mounting misalignments or decentering errors caused by shock and vibrations.

We define quantitative measures for parallax error in riflescopes and demonstrate that they increase proportional to magnification. We advise against current industry trends which advocate riflescopes with high magnification and large objective lenses.

We present useful relations between multiple formulations for specifying and constraining off-axis conics of revolution.

At the 2017 IODC, David Shafer gave a paper [1], and showed how a catadioptric design form could be improved by evolving from some elements being used in single pass to them being used double pass. He observed that this evolution couldn’t occur with a design program’s optimizer because the sequential modeling paradigm doesn’t support this without additional input from the user. The designer, on the other hand, can see the possibility of moving elements to jump to a new solution space. This comment was a catalyst for reexamining how sequential optical modeling developed. The goal is to address the modeling issue identified by Shafer without sacrificing the simplicity of sequential model specification. In other words, can an image forming modeling system be built that: • Retains the optimum performance and convenience of sequential models • While providing greater support for the designer’s view of the actual optical system. To assess the feasibility of these ideas, the software package ray-optics was developed using the Python language. Python is very advantageous for prototyping scientific software because of its broad ecosystem of open-source math and science software packages.

Alvarez lens is one of varifocal zoom lens to change field of view while shifting freeform lenses perpendicular to the optical axis. We analyze the aberration sensitivity of each coefficient in normalized XY polynomial.

To conform to the widening of head-mounted displays, stereoscopic optical systems require a high resolution of at least 4 K, and a field of view of at least 120°. However, the dimensions of the large-format cameras used to record high-quality content mean an appropriate stereo base cannot be achieved. Moreover, the wide angle of view prevents the use of a half-mirror rig to reduce the stereo base. Therefore, this study presents a solution where the stereo base is reduced using ultrashort throw lenses with a catadioptric relay in which the pupil is formed on the object side. Hence, a basic design for a wide-angle stereoscopic system with a half-field angle of ~126° and a stereo base of 62 mm is proposed.

The design of a push-broom radiometer operating from 0.2 μm to greater than 50 μm with a FOR > 120° is presented. The challenge is to design a WFOV radiometer with high accuracy and low uncertainty. This paper will present the results of an effort to design an ultra-broadband WFOV imaging radiometer, while balancing conditions that can impact the radiometric accuracy of the instrument. This system is further complicated by implementation of a single detector array that is sensitive to light over this very broad spectral range.

An off-axis Schmidt telescope based remote imaging system is under development for in-situ viewing of high-energy proton beam distribution at the Spallation Neutron Source. The optical architecture, design parameters and challenges of this design will be discussed.

A method is proposed to build and design modularize system to implement solar illumination system. Using Oliker-like freeform reflector to achieve uniform and precisely illumination distribution.

In this paper, we show, via a design example, how to leverage the parameters of a base off-axis conic to design freeform optical systems using the full-field display driven aberration-based design method discussed in [1]. Off-axis conic sections are often considered when designing unobscured or non-axisymmetric systems, including as base surfaces for freeform optics [2-8]. Likewise, design methods that use nodal aberration theory and full-field displays to gain insight into the aberrations of freeform systems have been demonstrated to be effective at generating starting points and performing designs (e.g., [1, 9-11]). However, in these aberration-based design methods, a central consideration is the correction of coma and astigmatism, which often involves the introduction of orthogonal polynomial astigmatism and coma terms (i.e.,, Z5/Z6 and Z7/Z8 for the Fringe Zernike polynomials). These terms are often major contributors to freeform departures, thus reducing or eliminating the need for orthogonal polynomial astigmatism and coma may improve interferometric testability estimates based on the magnitude of freeform departures. Consequently, in this paper, we leverage the parameters of base off-axis conics to follow the aberration-based design method without the use of additional orthogonal polynomial astigmatism and coma terms. While an off-axis conic is not exactly equivalent to a sphere plus astigmatism and coma, it is shown via a design example that re-designing with base off-axis conic parameters from the start can yield a new design that achieves equivalent optical performance without orthogonal polynomial astigmatism and coma. When these design methods are coupled with design methods aimed at reducing surface departures, significant improvements in interferometric testability estimates can be achieved, including when compared to fitting freeform surfaces designed with base spheres with the best-fit off-axis conic after optimization. For comparison, the design study in this paper is conducted twice: once using base off-axis conics with Fringe Zernike sag departure terms (excluding Zernike astigmatism and coma), and once using base spheres with Fringe Zernike sag departure terms (including Zernike astigmatism and coma).

The achievable design space for three-mirror unobscured imagers utilizing freeform surfaces was mapped out. The smallest volume diffraction-limited design was targeted for each combination of field-of-view, F-number, and entrance pupil diameter.

We propose a lens design ray tracing engine that is derivative-aware, using automatic differentiation. This derivative-aware property enables the engine to infer gradients of current design parameters, i.e., how design parameters affect a given error metric (e.g., spot RMS or irradiance values), by back-propagating the derivatives through a computational graph via differentiable ray tracing. Our engine not only enables designers to employ gradient descent and variants for design optimization, but also provides a numerically compatible way to perform back-propagation on both the optical design and the post-processing algorithm (e.g., a neural network), making hardware-software end-to-end designs possible. Examples are demonstrated by freeform designs and joint optics-network optimization for extended-depth-of-field applications.

In this study, we present a simulation and experimental investigation of binodal astigmatism in NAT with a Cassegrain telescope. The high-precision telescope system utilizes a piezo-actuated flexural mechanism to introduce secondary mirror misalignments and generate aberrations intentionally. The induced aberrations are measured interferometrically and quantified for a grid of field points on the image plane of the telescope. For this purpose, a coma-free pivot point of the secondary mirror was simulated for isolating the binodal astigmatism field response. A simulation of binodal astigmatism was generated using a real ray trace model of the Cassegrain system and analyzed to compare to the experimental results. The experimental results were consistent with the simulations, hence experimentally validating NAT for binodal astigmatism for the first time.

The optical design of a reflective objective system of a thermal camera for a syndromic surveillance system that captures bio-clinical signals, like temperature, directly related to the physical symptoms of the COVID-19 disease through thermal images is presented. The design is based on an off-axis four mirror system that allows for correcting spherical, coma, astigmatism, and field curvature aberrations. The OFOS design works on wavelengths of 7.5 μm - 14 μm, with an f-number less than 5, and a field of view (FOV) greater than 10 degrees.

A raytrace method is developed for evaluation of progressive addition lens (PAL) designs with freeform surfaces and gradient index (GRIN) profiles. The raytrace analysis is adapted from a Hartmann test method. More common surface-geometric evaluations for freeform surface PAL designs are presented for comparison. Sur- face geometric and real raytrace methods are compared for evaluation of homogeneous freeform surface PALs. Raytrace evaluation is compared with evaluation results from commercial lens design software for single vision lenses. A GRIN PAL base design is evaluated using the real raytrace method, and characteristic PAL behavior is demonstrated. This raytrace evaluation method enables new directions in using GRIN for ophthalmic lenses.

Annular folded lenses (AFLs) offer high resolution monochromatic imaging in a low telephoto ratio package. Monolithic designs offer advantages but are inflicted with chromatic aberrations. Applying freeform gradient- index media enables more advanced, diffraction-limited monochromatic AFL designs. By optimizing the GRIN profile along with its dispersion, chromatic aberrations can also be corrected, granting high performing poly- chromatic designs.

We have proposed a design method of a freeform refractive surface for illumination using multiple faceted refractors. The reflection loss on the refractive surface also has been considered during the design process. As an example, a smooth freeform lens with uniform illumination distribution is designed. Compared with the direct method without consideration of the loss of energy, the method achieved a great improvement in the uniformity of illumination distribution with no loss of output efficiency.

An all-spherical catadioptric telescope with an aperture of 75 cm and an angular field of view with a diameter of 10◦ (260 mm) is described. The design provides D80 image quality better than 1.9′′ (13.6 μm) on a flat detector. The limiting stellar magnitude and speed of the sky survey achievable with this system are estimated.

A method to integrate metasurfaces in lens design is proposed. Thanks to a model based on effective medium theory used in conjunction with lens design software, the optical properties of custom metasurfaces within a complex system can be calculated. Compared to simple phase surfaces embedded in common lens design software, the phase shift profile given by our model is dependent on the wavelength and field of view. We thus demonstrate that those phase surfaces cannot accurately reproduce the behaviour of metasurfaces in every system. As a proof- of-concept, a hybrid refractive and metalens design was also made. The metasurface located within two refractive lenses corrects mainly the spherical aberration and allows the system to be almost diffraction-limited for the whole field of view.

We introduce a universal design platform for the development of highly-efficient wavefront engineering structures. To validate this methodology, we fabricated many different optical devices with an experimental efficiency exceeding 99%.

For the 5th time, the International Optical Design Conference (IODC) included an Illumination Design contest. This year, the contest involved designing the optics to reverse a magical curse that was placed on Prince Lambert. The goal of the problem was to maximize the flux when a specified ray source was traced back through optics that had to fit within a 220 mm by 220 mm by 220 mm box. The winning solution was provided by Jake Jacobsen and the winning student solution by Shohreh Shadalou.

The lens design problem for the 2021 IODC is to design a 100 mm focal length lens where if the lens is flipped end-to-end but the radii are not reversed in sign, the lens has to perform the same as in its original form. The lens is used monochromatically. The goal of the problem is to maximize the product of the entrance pupil diameter and the semi-field of view while holding the RMS wavefront error to ≤ 0.070 wave within the field of view. There were 43 entries from 13 different countries. Three different commercial lens design programs were used, along with four in-house programs. The winning entry from Damien Gawron has an entrance pupil diameter of 198.4083 mm and a semi-field of view of 90° for a merit function product of 17,857 out of a maximum possible 18,000.