This PDF file contains the front matter associated with SPIE Proceedings Volume 13131, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

This paper announces the development of a new, cryogenic refractometer at Leviton Metrology Solutions in Boulder, CO known as the Differential High Accuracy Refraction Measuring Apparatus, or DHARMA, which is nearing completion. DHARMA has been developed in part to provide a commercially-available source of cryogenic, refractive index measurements of similar or better quality to those provided by the CHARMS facility at NASA’s Goddard Space Flight Center. It was also conceived to provide the same the state-of-the art capabilities as CHARMS but extending into the long wave infrared (LWIR) where there is a growing need for such measurements. DHARMA’s basic design is presented along with preliminary data for measurements of cryogenic, absolute, refractive index for several prisms previously measured using CHARMS.

Urine test strips aid in prompt health assessment through color changes, but visual interpretation can be misleading, particularly with strips having multiple functions. To tackle this, some companies and studies have created paper strip analyzers using CMOS sensors. However, issues like ambient light and shooting angles often cause detection failures. Therefore, this study proposes integrating a multi-channel color sensor as the core component of a urine test strip analysis system and optical waveguide technology for optical system design architecture. This design aims to capture more color information in urine, and the optical waveguide technology ensures uniform light guidance, providing real-time transmission and high-quality signal data for urine analysis systems.

These days, nothing lasts very long, and things often change for the better, but there are sure things in our community, such as this annual event, which has been going on for 25 years. The first edition in 2000 of the Current Developments in Lens Design and Optical Systems Engineering Conference took place during International Symposium on optical science and technology, 30 July - 4 August 2000 in San Diego. Over 45 oral presentations and ten posters were presented. The chairs were Robert E. Fischer, Warren J. Smith, R. Barry Johnson, and William H. Swantner. The proceeding was numbered 4093 and 24 years later the number is 12666 (2023). This paper looks back on the great moments of our conference, its speakers, the subjects that have come and gone, and those that have remained.

Several new optical design methods have been developed over the last 25 years for lithographic optics, leading to greatly improved designs.

Optical simulations have always been tightly linked to our computational abilities, from the days of raytracing by hand through today's high-powered tools. Simulations become viable when they reach high enough accuracy to compete with hardware tests, and usually save time and money. For NASA, the James Webb Space Telescope marked the transition from direct hardware testing to a simulation-led build and pushed all of our simulation tools forward in the process. The transition to simulation-led projects continues apace with integrated multiphysics tools, digital twins, AI/ML assistance, and smarter system engineering. To some extent, we can see where these initial steps will lead and imagine the simulation capabilities of the future.

Depth of field (DoF) determines the focused object depth in an optical imaging system. An extended depth of field (EDoF) should provide a larger axial resolution without significantly sacrificing the spatial resolution of the image. An optical-computational technique that uses a Trefoil Phase Mask (PM) to optically encode the scene and a Convolutional Neural Network (CNN) to restore the acquired encoded image is presented. Simulations and experimental results are compared.

Vein pattern recognition is a biometric identification technology that relies on the unique vascular patterns of each person’s hand. In this paper, we propose a method for people recognition that uses a combination of wavelet invariant moments and Convolutional Neural Networks (CNNs). Wavelet moments are a set of features extracted from an image using wavelet transform. These features can be invariant to translation, rotation, and scaling, which makes them well-suited for people recognition. CNNs have been shown to be very effective for image classification tasks. In this paper, the method is evaluated on 6000 palm vein images from the PolyU Multispectral Palmprint Database. The results show that the proposed method achieves an accuracy of 99%, which is higher than the accuracy of existing methods.

Liquid Mirror Telescopes have been shown to be a credible alternative to traditional telescopes for building low-cost observatories. Previous LMTs were based on the rotation of a pool of mercury which, from the rotation, takes the shape of a parabola. However, they cannot be tilted as traditional telescopes to observe at fields away from the zenith. In the context of the DARPA Zenith program, we present a telescope concept where a magnetic fluid is shaped to a parabolic surface by combining wetting effects and magnetic fields which allow the telescope to be tilted. We also show that the off-axis optical aberrations of the telescope, when observing off-axis, can be cancelled by a surface correction of the parabolic liquid surface by adding a correction to the already applied magnetic field that shapes the mirror surface. In this approach, the scientific instruments are located at the focal plane and designed to track the beam as the field changes.

Thermal requirements often constrain optical designs resulting in cost or performance compromises. Unless an optical system is designed from the start considering thermal requirements, effects including thermal defocus can become detrimental to the system’s real-world performance. Novel negative thermal expansion ALLVAR Alloys enable a new degree of freedom during initial system design or can be used to passively athermalize an existing optical system without having to re-design. This work discusses the analysis and integration of ALLVAR Alloy 30 into an optomechanical housing to athermalize mounted Commercial Off-the-Shelf (COTS) doublets. Calculations for the thermal defocus of the doublets and the requisite opto-mechanics to athermalize each system are first presented. The target athermalization of the doublets is also discussed. The ALLVAR Alloy 30 athermalized doublet assemblies are then manufactured, built, and tested. The results of the as-built data and testing are presented as compared to the thermal defocus analysis. This work demonstrates that an existing optical system design can be athermalized by utilizing an ALLVAR Alloy material in the optomechanical design.

The fabrication of curved compound eye camera systems is usually complex since it can involve multiple non-standard components to achieve the desired effect. In this paper we aim to provide a close alternative to these custom optical elements using off the shelf components or to provide a framework to design these system using standard fabrication techniques. We will first demonstrate how lens distortion can be leveraged to optically bend a standard planar micro-lens array, and how this bending correlates to a curved micro-lens array. We will then show lab results of curved compound eye camera made using an off-the-shelf fisheye lens and a standard micro-lens array and how the equivalent curved micro-lens array system would reproduces image in the real world and provide a comparison using image simulation from an optical design software and a scene recorded using a neural radiance field.

We propose a novel manufacturing technology for monolithic polymer optics such as aspherical lenses. UV-replication is well known from wafer level optics. Here supporting glass wafers remain in the final lens. This severely limits the degrees of freedom of the optical design. In addition, material shrinkage, when the polymer is cured, limits reasonable sag heights of the lenses, so that only low-resolution imaging optics are possible. In our UV-replication approach, there is no glass substrate in the individual lenses and the shrinkage is compensated in the process to achieve minimum form error. This enables large sag heights and aspherical lens profiles on both sides of thin menisci as required in high-resolution imaging optics which so far can be realized by injection molding only. Combining this with a high degree of parallelization such as in wafer-level-optics is the key to a large-scale and economical production. We present details of our new technology at the example of realized demo systems for 3D-sensing applications using nano-optical structures, imaging use-cases in endoscopy and those ultimately targeting mobile phone camera modules.

Our study presents recent progress in modelling and performing lens optical design with metasurfaces. We developed semi-analytical models that recover the output phase, polarization, dispersion and group delay of various nanostructures. This enables the mixing of different nanostructures to obtain a target dispersion profile an interesting application of the model. These models can readily be implemented within optical design software such as Zemax and use the built-in optimization of optical design processes while avoiding time-consuming electrodynamics computation. We also introduce the metasurfaces to the analytical lens design framework. This enables us to analytically compute the phase profile of freeform metasurface doublet concerning particular ray conditions such as the Abbe Sine condition as we presented here.

Most Silicon based depth and lidar sensors rely on near-infrared (NIR 750-900nm) sources to produce depth images as Silicon CMOS sensors can achieve a high quantum efficiency for an unbeatable cost at such wavelengths. Advances in Short Wave Infrared (SWIR) sensor technologies, such as Silicon-Germanium sensors, changes this paradigm and opens a new window for groundbreaking sensor designs, as SWIR can push the wavelength above retinal hazard area (⪆1400nm), allowing for much higher eye safety, due to the low penetration of those wavelengths through the eye lens. Here, we propose to use a Silicon Metalens flat optics and build upon our stacked sensor technologies to obtain a fully Silicon integrated stacked sensor at SWIR wavelengths. We will discuss the design of the stacked sensor and focus on the Silicon Metalens for multiple use-cases. We will demonstrate the results of our Silicon metalens prototype at 1550nm. We will show numerical simulations of the optical stack for eye-tracking application or wide-angle Time of Flight (TOF) and discuss the necessary trade-offs.

The Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA’s Goddard Space Flight Center (GSFC) has undergone some recent upgrades enabling refractive index measurements without the use of either liquid nitrogen (LN2) or liquid helium (LHe) cryogens, once again achieving sample temperatures around 30 K. CHARMS has also enjoyed the replacement of its very old, LN2-cooled, InSb mid-wave infrared (MWIR) camera with a new, state-of-the-art InSb camera cooled with a closed-cycle Stirling cooler enabling unattended operation. The new camera improves signal-to-noise in MWIR index measurements. We report on measurements of two each Si and Ge prisms from room temperature down to below 35 K which are the first to benefit from these two recent upgrades. We also report on upgrades to CHARMS still in work which will enable cryogenic index measurements in the Long Wavelength Infrared (LWIR) to wavelengths as long as 12.5µm for the first time.

In this work, detailed literature about the power allocation schemes in optical wireless communication has been presented and discussed. The main goal is to evaluate the Gain Ratio Power Allocation (GRPA) and Normalized Gain Difference Power Allocation (NGDPA) schemes in a 4x4 Multiple-Input Multiple-Output (MIMO) Non-Orthogonal Multiple Access (NOMA) based Visible Light Communication (VLC) system. The work will evaluate the GRPA and NGDPA according to the system's overall achievable sum-rate and the sum-rate gain. The proposed MIMO-VLC system can utilize up to four subscribers regardless of their current position within the system coverage area. The work will examine the received bit rate of each user in different positions within the system coverage area. Target to maintain the same bit rate for each user, especially when the user is at the border of the system coverage area. Finally, the study will discuss the results before and after applying the power allocation schemes GRPA and NGPDA. It has been concluded the overall sum rate gain percentages after applying GRPA are lower than NGDPA, which gives the GRPA allocation scheme an advantage over NGDPA.

A transmission and receiving optical antenna is built-in-house by TASA and Taiwan domestic optical company CALIN. A Cassegrain type telescope is designed and manufactured with primary aperture 80 mm. It could provide the transmitted and received gain about 104 dB, and the obscuration loss about -3.8 dB in the link channel for free space optical laser communication. It could also be integrated in the CubeSat or in the optical communication terminal for small satellite missions. The root-mean-square wave front error for the optical antenna is less than 100 nm. The optical aberrations introduced on-axis WFE loss is estimated about -0.72 dB in the link budget. An eyepiece is designed to locate near the focus of telescope to collimate the output beam with beam size about 3.3~4.7 mm for propagating 50 cm distance in the follow-up communication module system. With the strong supporting domestic electro-optical industry, it is expected to help a lot on the development of the Taiwan space technology.

This paper investigates the design of an ophthalmic rigid Contact Lens (CL) that has a Q-type aspheric surface to reduce the tolerance error budget and produce higher visual acuity. CLs for myopia correction are typically made with spherical surfaces; when such CLs are worn in darkness, the visual acuity degrades severely due to the spherical aberration generated by pupil dilation. To maximize visual acuity, an aspheric CL is essential because it can correct the spherical aberration. In this study, a CL is designed based on a schematic eye model for evaluating the Modulation Transfer Function (MTF) on the retina, and the result shows that the visual acuity produced by an aspheric CL is superior to that produced by a spherical CL. The traditional power-series polynomial is commonly used for aspheric surface design, but the aspheric slope cannot be controlled during optimization. The large slope departure from a best-fit sphere leads to high tolerance sensitivity and an inflection point; however, the CL does not permit such results. To solve this problem, the Q-type polynomial with slope constraint proposed by Forbes is applied to the aspheric CL in this study. The Q-type aspheric polynomial can not only enhance the optimization efficiency due to its orthogonal characteristics, but also reduce error budget for maximal manufacturing yield. The simulation results demonstrated that the spherical aberration is successfully reduced by the Q-type aspheric CL for better visual acuity in darkness.

This study aims to investigate the impact of Bulk Scattering Diffuser (BSD) on color variation in Mini-LED backlight modules under different optical parameters. To predict spectral distribution distortion of BSD in Mini-LED backlight module, a virtual Mini-LED backlight is built in the optical simulation software. The scattering behavior of BSD is also established by the calculation model based on Mie scattering theory. In simulations, the corresponding color coordinate of distorted spectrum is moved in the CIE 1931 color space owing to varying parameters of BSD. Finally, under the condition of highly color uniformity, through the comparison between the color coordinates and the MacAdam ellipse, the suitable manufacturing parameters of BSD are discussed.

A luminaire designed for tunnel lighting is proposed, featuring the ability to adjust the ratio between counter-beam and pro-beam lighting based on different contexts. This allows the luminaire to achieve the optimal lighting mode for the conditions within the tunnel at that time. When both side LEDs are activated, it operates in symmetric lighting mode. When a single-side LED is activated, it switches to either counter-beam or pro-beam lighting mode. The advantage of this luminaire lies in the use of a single freeform secondary lens and LEDs, making installation simpler. It ensures driver safety and is more energy-efficient than traditional tunnel lights.