This PDF file contains the front matter associated with SPIE Proceedings Volume 12666, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

In conventional free space optical communication receivers, focusing optics reduces the field of regard (in the range of millidegree) while increasing the power received by the detector. As a result, a receiver communicates with one transmitter at a time. In this paper, we propose a novel two-metalens-receiver system that offers a wider field of regard (in the range of degrees) to capture the optical signal from a large Angle of Arrival (AoA). The first metalens of the system compresses and separates optical beams, based on different incident angles. The compression factor of the first metalens needs to be chosen based on the receiver system’s overall length, aperture size, and minimum angular separation between the transmitters. The second metalens redirects and focuses the beam to the detector sitting on the optical axis. Physical Optics calculation with the proposed phase profile as a phase mask shows that our proposed system increases the power received by the detector up to 1000 times compared to the conventional system for large AoA. As a result, transmitters with wide angular (and spatial) separation can communicate with the proposed receiver simultaneously. The designed phase profile is implemented by a meta-unit cell with varying diameters of Si nanopillars sitting on the quartz substrate. Finally, Quasi- 3D full wave simulation is carried out to show the effectiveness of the two metalens-receiver systems.

Advancements in inkjet printing technology have enabled the manufacturing of volumetric gradient-index (GRIN) optics, which offer added degrees of freedom (DOF) in controlling geometric and chromatic aberrations. By precisely formulating the refractive index spectra of the feedstock, GRIN lenses can achieve independent control over primary and secondary dispersion, eliminating the need for multiple surface-figured lenses. This allows a single monolithic GRIN device to perform the optical functions of multiple homogeneous-index surface-shaped optics. The measured results from a series of up to 50-mm diameter GRIN lenses implementing spheric, high-order aspheric, freeform, plano-convex, and aspheric-GRIN optical elements will be discussed, showcasing what may be the highest DOF ever exhibited in a monolithic optical lens.

Spectacle lenses are an important application of freeform manufacturing, with complex designs such as progressive lenses requiring nontraditional and specialized surface shapes. Such lenses also pose special challenges for optical design, as the eye’s gaze constantly changes relative to the lens. At the same time, many applications require sacrificing one region, such as the transition in a smooth bifocal, while achieving high quality in other regions. Common representations of freeform lens surfaces using polynomials or splines are poorly suited for such requirements. We describe an approach to optimize freeform spectacle lenses using a nonparametric representation of the surfaces at high resolution. Requirements for smoothness are quantified in terms of high-order aberrations. This allows us to describe spatial variations in the design while also incorporating a constraint for optical smoothness and manufacturability. We show how this can be formulated as a regularized optimization problem incorporating raytracing, which can be solved efficiently. The approach can be used to design various kinds of lenses including progressive, bifocal, and lenticular designs. The designs have been successfully manufactured on multiple different brands of freeform generators. Manufactured lenses are found to perform as designed, including without polishing when supported by the material and generator.

Metalenses can be used as standalone single elements or incorporated as one component of a subassembly that also includes other non-metalens optical elements. Because of the sub-wavelength length scale of the meta-atoms, ray-based methods for analysis and optimization may not be considered appropriate. However, by treating the imparted phase appropriately, ray-based methods can be used to design and analyze optical systems that incorporate one or more metalenses. These methods can be applied to imaging systems or illumination systems composed solely of metalenses, or systems that incorporate a mix of metalenses and conventional refractive, reflective, or diffractive optical elements. There are two pieces of information that are required by the ray trace: i) the ray directions following the metalens, and ii) the amount of energy that the ray carries. The distribution of the meta-atoms in the metalens can be used to determine ray directions and Fourier analysis allows for estimation of the energy carried by the rays. The method relies on having access to the imparted phase (from an EM solver, say) that can be accessed during the ray trace. This approach allows for workflows that are familiar to lens designers—even those without experience designing metalenses—while offering results that are in excellent agreement with more rigorous wave-based analyses. This approach is applicable to both polarization-insensitive and polarization-sensitive designs. In this paper, we discuss the design approach and offer design examples.

Augmented reality (AR) is the trend of future life. Until now, many technologies have been developed for AR glass. With the high brightness and light characteristic, we use Micro-LED as the source and the metalenses array to form the collimated light. The image can be projected onto the retina using sequential scanning technology. However, the divergent angle of the collimated light would increase along with the increase in pixel number. In this paper, we simulate the collimation properties of metalenses. To increase the number of pixels, we propose to arrange the pixels on a retina well according to the simulation results. The corresponding results of the simulation and calculation will be shown.

Illumination optical design using non-coherent sources is of major interest for sensing applications requiring a uniform illumination. We present the development of a custom biconic lens array, enabling beam shaping of a halogen source array to a rectangular uniform illumination. First, the tungsten halogen sources were accurately modelled considering the nearfield emission pattern and broadband spectrum. Following, the illumination lens array is optimized, including a study on the optimal arrangement and pitch of the array, and ensuring a manufacturable design by taking the optical and mechanical tolerances into account. The optimized lens array comprises of custom lenses (Ø 20 mm) featuring a first spherical surface and a second biconic surface with different radii of curvature and aspherical coefficients (up to the 8th order) in the X and Y direction. A spatial uniformity, defined as the standard deviation of the flux distribution, of 0.0002 was achieved within the envisioned illumination area of 50 x 20 mm², being close to a perfect uniformity considering a targeted value of 0. Finally, the aspheric biconic lens is manufactured using ultraprecision diamond tooling (Nanotech 350FG), and its performance is successfully validated in a laboratory demonstrator setup, giving rise to an optimized and uniform halogen source illumination.

Micro-optical projectors consist of a double-sided, aligned microlens array (MLA) with an absorptive slide mask array buried under the entrance condenser lenslets. While the exit lenslets project the slides, the condenser lenslets realize Kohler illumination of the multiple projector channels. To achieve high system transmission, the condenser lenslets have to be positioned in a space-filling arrangement. For arbitrary projected shapes, the slide further reduces the effective fill-factor of a channel. We propose to increase fill-factor and simplify architecture of the MLA by replacing the buried slides by condenser lenslets with certain elementary shapes, building an irregular entrance array with space-filling parqueting. The condenser lenslets´ apertures are imaged by the projector lenslets towards certain positions in the far-field, controlled by the decentration between condenser contour and projector vertex. This enables for optional ‘jigsawing’ of the intended pattern from elementary images. Any residual MLA regions, that cannot be covered by condenser lenslet apertures, can be excluded from projection by patterning with diffusor structures, which scatter away incident light under large angles. Now, that we have excluded the buried mask array, such double-sided MLA can be replicated not only as precise polymer-on-glass elements (POG), but also by cheaper high-volume techniques like injection molding (IM), making the latter attractive for the automotive industry. An automotive projecting chase light blinker based on this concept, employing controlled channel crosstalk, replicated as POG is presented. IM replication of MLA is currently underway. We evaluate the performance and present a brief outlook of mask-less, multi-aperture microoptics.

First Contact (FC) Polymer™, developed by Photonic Cleaning Technologies, is used to clean and protect surfaces from contamination. The polymer creates a peelable coating that renders the surface clean while not leaving visible residues. To investigate the effectiveness of FC at the subnanometer level, we used variable-angle, spectroscopic ellipsometry (VASE) to measure sample top-layer thickness after repeated application/storage/removal cycles of standard (red) FC with three sample sets (CVD Si₃N₄ on Si, bare Si, and SiO₂ on Si). The samples were measured via VASE after every FC removal to understand contaminant thickness changes with “peel-off” count. Control samples were also measured at each iteration. Ellipsometric analysis revealed FC removed, during the first peel-off, impurity from the surface of samples treated with impure isopropyl alcohol. Linear regressions and t-tests comparing samples with and without FC were employed for evaluating changes with peel-off counts. There is evidence for the very slight build-up of material which is not removed by iterative FC application/removal cycles on these samples. It is slight, <0.1 nm after 17 iterations, in the case of native oxide on Si.

Cygnus is a dual beam high-energy radiographic x-ray source. Ten years ago, three large zoom lenses were assembled to collect images from 200 mm x 200 mm square scintillators. The zoom capability allows zooming down to a 60 mm x 60 mm picture from the scintillator. Current radiographic imaging needs now require larger 270 mm x 270 mm square scintillators and the capability to use both 92 mm x 92 mm and 62 mm x 62 mm CCD cameras, and a new lens design to meet these needs. This zoom lens incorporates 11 elements and is designed to be telecentric. It images a scintillator emitting light peaking at 435 nm, so special glass types are required for the lens elements. Much larger elliptical pellicles are needed to deflect the scintillator light out of the x-ray path into the lens. The optical axis of the imaging system must be colinear with the x-ray axis. Two scintillators are positioned in each of two Cygnus x-ray axes, for a total of four scintillators and four lens systems. An optional configuration will be shown, enabling two lens systems imaging opposite sides of a single scintillator, for a total of four lenses and two scintillators. Although this configuration has advantages, it suffers from crosstalk. Care must be taken to analyze the anti-reflection coatings applied to all the elements in the imaging chain, including the CCD array and its vacuum window. The evolution of our Cygnus radiographic systems over the last two decades will be discussed.

This presentation was presented at SPIE Optics + Photonics 2023 Conference.

In this paper, we propose an innovative adaptive automotive headlamp design that incorporates a volume holographic optical element (VHOE) as a beam splitter. The VHOE is recorded with an infrared divergent spherical wave, allowing for the efficient combination of both time-of-flight (ToF) laser beam and miniLED imaging automotive headlamp. By exploiting the Bragg selectivity property of the VHOE, only the ToF light is affected while the imaging headlamp light passes through unaffected. This facilitates the adaptation of the automotive headlamp to different lighting conditions, providing enhanced visibility and safety for drivers. The ToF laser beam provides accurate depth information, while the miniLED can create a high-contrast cut-off line. The VHOE beam splitter enables the effective combination of these two lighting sources, ensuring that each is used to its full potential. Our design offers a promising solution for adaptive automotive headlamp systems that could potentially improve driver safety on the road.

Antifungal effects of ultraviolet C (UV-C) irradiation have been considered a potential solution to reduce the severity of black spots on postharvest fruits. In this work, a 30 × 30 × 30 cm system was made based on UV-C light-emitting diodes (LEDs) to apply in reducing disease symptoms for bananas which could be used in industrial conveyor belts. The UV-C irradiance monitoring was carefully carried out for several sections at various box heights in simulation and measurement. The findings experienced a dominating range of 6 to 9 W/m² in the central sections. Regarding in vivo conditions, the observation after a week from experiment showed that the disease symptoms on the UVC-treated banana peel, which was exposed under UV-C light around 5 s, dramatically decreased compared to a natural banana. Consequently, the UV-C dose range is proposed from 0.030 to 0.045 kJ/m² with minimum damage in terms of sensory properties. Owing to the flexible shape and short exposure time, the system promises to provide many potential applications to prolong the quality of bananas.

The FORMOSAT-8 Program aims to develop high-resolution optical remote sensing satellites through collaboration with industry, academia, and research teams in Taiwan. In order to enhance the signal-to-noise ratio (SNR) of the images, it is crucial to understand the surface scattering characteristics and implement effective measures to suppress stray light in the optical system. In this study, a combination of bidirectional reflectance distribution function (BRDF) and total integrated scattering (TIS) measurements is utilized to identify materials that exhibit ultra diffusive-matt characteristics. All the selected materials underwent environmental tests to verify their durability for space environment usage. The databases of BRDF and TIS also facilitate the construction of mathematical models representing surface scattering characteristics. All the findings of this study were utilized to arrange the surface blackening methods for various components within the optical system and proved highly advantageous for FORMOSAT-8 satellite program.

Wavefront coding (WFC) technique has been used to extend the depth of field (DoF) in an imaging system. Its effectiveness lies in using a phase mask (PM), which allows the point spread function (PSF) to remain almost invariant in an axial range of the DoF. Subsequently, a restoration method of the acquired coded images is required. An optical-computational technique that uses Trefoil profile PM for encoding and a convolutional neural network (CNN) to restore is presented. Comparative results are done between the restored image using the Wiener filter and the one obtained with a CNN. An image quality evaluation is done in terms of spatial resolution and contrast.

This paper proposes the use of a phase mask as an ophthalmic element to correct presbyopia in moderate cases and improve the visual acuity of people who suffer from it. Taking advantage of the main characteristic of the phase mask, which delivers a blur-invariant PSF in an axial range. The Neuronal Transfer Function (NTF) allows an improvement of the retinal images due to its behavior as a bandpass filter that increases the contrast of the degraded images. The simulations were carried out using two different mask profiles and pupil sizes of 2 mm, 4 mm, and 6 mm. To quantify the performance of the optical system, some metrics known as Visual Strehl are used, specifically VSOTF and VScombined.

At Southwest Research Institute (SwRI), the ultraviolet (UV) calibration lab successfully tested First Contact Polymer (FCP) cleaning solution on unprotected gold mirrors in the UV region. This investigation proved that the cleaning solution meets the contamination threshold of < 100 ng/cm² and passes the relative reflectance differences threshold of <10% difference. Future internal research funding would include UV testing with other optics (mirrors/lenses with different coatings and substrates, diffraction gratings, and freeform optics) to establish its effectiveness over a variety of optical elements.

This paper presents the active alignment of miniaturized, substrate-free optical thin-film filters (TFFs) according to the filters’ spectral transfer properties for integration into fiber optical networks. Optical TFFs are often designed for a specific narrow angle of incidence (AOI) range. Hence, a sufficient manufacturing precision of the angled photonic components connected to the optical filter is needed. These components then can no longer be used for different scenarios where i.e. the incident angle is changed. Conversely, the individual miniaturized optical filter chips can also vary in specification due to slight inhomogeneities during the production on a largescale wafer. Therefore, not all filter chips on the wafer meet the demanded specifications at the designed AOI, resulting in a reduced yield. Moreover, it requires a time-consuming separation into different quality classes by measuring single filter chips on the wafer. To maximize the amount of usable chips, a procedure was developed to actively align the chips inside a precision optics assembly system by measuring the transmitted power at different wavelengths while tilting them towards the optical axis. When the optimal angle is found, the chip is glued into the optical network platform. Next to maximizing the yield, the production steps can be reduced because the prior separation into quality classes becomes redundant. Manufacturing tolerances during the thinfilm deposition are equalized due to the active spectral alignment on a universal optical platform. With this technique, a more versatile process for TFF integration compared to passively aligned assemblies on fixed angle components is demonstrated.

For some types of studies on a microscope, optics is required, which has a multi apochromatic aberration correction in a continuous spectral range from the nearest short -wave UV to the nearest IR spectral areas. In the NUV range, in some cases, it is required to ensure the focus of laser sources radiation on the wavelengths of 248, 222, 213 and even 193 Nm. The work is also required for the near IR region, for example, for focusing laser sources radiation on wavelengths 1315, 1523 and even 2010 and 2080 nm. A priori such optics should also work in a visible spectral range. All studies can be carried out within the indicated a continuous NUV - NIR of the range. We propose to investigate the fundamental possibility of creating lens objectives for which chromatic aberrations are corrected in a wide spectral range. In addition, optics are required for research in the SWIR, MWIR, and LWIR spectral ranges.