Digital Optical Technologies 2023

Significant advances continue to be made in the design and development of next generation optical and optically enabled products across many industries and applications, from automotive to consumer electronics, healthcare to aerospace and defense, data communications to quantum computing…and much more. These advances are being fueled by innovations in underlying technologies, including scalable manufacturing of complex aspheric and freeform geometries, fabrication of high efficiency micro-optic and diffractive optic components, and the development of photonic devices with directly integrated light engines and sensors. While challenges remain in component-level design, the next set of advancements in optical product development are being driven from a wholistic, integrated approach that incorporates all elements into a system engineering view. Simulation plays a critical role in enabling this system-level view, from the micro- (or nano-) scopic to the macroscopic level. In this talk, I will highlight the role of Multiphysics simulation in the design and development of advanced optical systems, such as optical interconnects, digital lighting, LIDAR sensors, and AR headsets.

For Augmented Reality to spread and reach common usage levels, the visual experience needs to be entirely healthy and natural for the user. This is why CREAL has developed a unique AR display that combines light field imagery with ordinary highly transparent ophthalmic lenses, providing a true-to-life depth perception for the human eye and customizable prescription with classical aesthetic look of the lenses. While almost all AR glasses providers are lumbered with trade-offs between focal depth, image resolution and lens aesthetic, CREAL’s newest display finally enables an AR visual experience that “has it all”. This talk with introduce the solution.

The optics of the human eye is as simple as robust and well adapted to the requirements of the visual system. How different induced optical profiles affect vision is a critical issue in ophthalmology. A very insightful way to evaluate this involves the use of adaptive optics visual simulators. This type of instruments are available in laboratories and clinics in a desktop format. It allows to measure the optics of the eye using a wavefront sensor and to add any particular phase profile with spatial light modulators while performing visual tasks. In the last years, we have been advancing this concept to be integrated in wearable devices allowing to test vision in subjects under more natural conditions. In this presentation, I will revise the history of adaptive optics in the eye with special emphasis in the current efforts to develop wearable devices.

Two technologies were combined to demonstrate a compact, foveated occlusive Mixed Reality headset with a horizontal Field of View (FoV) of 93 degrees. Waveguide displays (HoloLens 2) formed the central, high-resolution FoV and a multi-lens array (MLA)-based display, the periphery. Collectively, the peripheral display lenses created a non-rectangular FoV of 26x26 degrees with a resolution of 10 ppd. The system's optics were less than 5mm thick, though the experimental setup was thicker due to optomechanical and industrial design constraints. A qualitative user study verified that the experience was improved and that the neck strain was significantly reduced and comfort increased.

A novel display solution for Metaverse AR glasses; Novel light engine solution for LCOS and Micro-LED display combine with nano-imprinted waveguide to achieve lightweight, slim, low cost, and high volume Manufactuing.

This work presents proof-of-concept experimental results of a holographic near-eye display. It combines a Holographic Optical Element (HOE) based waveguide, a Liquid Crystal on Silicon (LCoS) dynamic hologram, eye tracking and pupil steering and switching optics. A steerable Maxwellian view system moves the pupil, and the dynamic hologram creates the image. Pupil steering and switching were demonstrated over an eye box of 9x9mm and with a FoV of 20 degrees. The resolution was near-diffraction limited, and users could use the system without prescription glasses.

The limited space-bandwidth product of digital holography results in a trade-off between the field of view (FOV) and eye motion box (EMB) size. One potential approach to overcome this trade-off is to use a waveguide as a pupil expander. However, this approach has the constraint of generating only infinite depth images or 2D images, which can cause visual discomfort. To address this issue, a novel method that enhances the space-bandwidth product while providing a 3D image with full depth range is necessary. In this paper, we introduce a projection-type holographic display that combines a waveguide, a spatial light modulator, and a laser light source to display true 3D holographic images with an extended FOV. Experimental results demonstrate that this method effectively generates holographic 3D images with an FOV expanded 4 times in the horizontal direction compared to conventional methods.

Diffractive optical elements (DOEs) gradually start replacing traditional refractive optics in many applications. The growing interest in DOEs is mainly because of their flexibility in light manipulation with a small form factor and their ability to combine simultaneously optical and computational functions into a single part by applying the software-hardware co-design approach. Two main methods are widely used to fabricate DOEs. The first method is the etched-based method that combines photolithography and reactive-ion etching (RIE). The second method is an additive fabrication, which combines metal deposition and nanoimprinting (NIL). Both methods have many drawbacks. The RIE methods suffer from issues like lags in the etched depth when the feature sizes differ in the same pattern (RIE lags), high surface roughness, and aspect ratio-dependent etching rate. The second method could produce high-resolution micro-optics. However, the technique could suffer from poor adhesion of the patterns with the substrate and poor uniformity across large areas. Here we propose a new way to fabricate multi-level DOEs by directly growing in an optically transparent material on a glass substrate. The method combines the deposition of Silicon dioxide (SiO2) by Plasma-enhanced chemical vapor deposition technique (PECVD) and bi-layer lift-off. We provide evidence of the effectiveness of the fabrication method by comparing a 16-level Fresnel lens fabricated by the RIE method with another lens fabricated by the proposed method. The characterization results show that with the proposed method, the surface roughness is lower, and the depth is uniform. Furthermore, the optical test shows a reduced haze effect.

Selective laser etching is a promising technology to create glass based single optical components or integrated structures. We present a detailed investigation how different laser parameters affect the process results, especially with respect to surface roughness. The process allows for the precise and efficient structuring of glass fibers. Also, it enables access to the fiber core for functionalization purposes or adding further optical structures by using two-photon polymerization. Especially the possibility to easily modify standard glass fibers to sense environmental parameters opens a broad field of interesting applications.

We aim to integrate two-photon polymerization (TPP) in a fully digitalized and automated workflow for micro- and nanooptics production. This requires linking the coordinate system of the writing laser scanner to the geometry of the sample or previously fabricated structures on the sample. We developed a fast layer detection algorithm, which determines the axial position and the tilt angles of both interface planes of the photosensitive material using the integrated microscope camera of the TPP system. Furthermore, we identify the shear angles between the camera and the lateral scanner axes. The individual measurement results are stored and accessible via direct-written identification QR code on the sample itself. This is an important step towards an individualized automatic workflow based on digital twins.

Thanks to clear advantages in picture quality, power efficiency, and compactness, OLED micro-displays have captured the market for "near eye displays," from consumer cameras, to professional cameras, to industrial and military applications such as night vision. OLED brightness and durability meets or exceeds market requirements, and growth in OLED micro-displays is very strong thanks to these and other advantages and benefits. But what about OLED application in augmented reality ("AR")? Until recently, LEDs were often selected for AR products due to high brightness. However, OLED technology is evolving rapidly, and the primary challenge with AR is not necessarily brightness. In this presentation, we will highlight the evolution of OLED technology, and how OLED can directly contribute to breakthroughs in the design and development of AR devices at the system level.

As flat optics become increasingly mainstream, there is high interest in improving patterning resolution, making new materials available, and lowering manufacturing costs for these components. Because of their maturity across the entire supply chain, 300 mm m offer one of the best opportunities to simultaneously achieve all of these goals. By leveraging existing tooling and knowledge from 300 mm CMOS patterning, the high-pattern resolution of immersion DUV mastering can be combined with nanoimprint lithography and etching to achieve pattern transfer to optical materials. Wafer scale CMOS metrology can also be leveraged to optimize process uniformity and repeatability. This talk will present imec’s recent developments in utilizing CMOS fab tools to pattern high-index dielectrics on 300 mm substrates.

Optical scanning approach to image processing has advantages over frequency-plane architecture in terms of accuracy and flexibility. In this talk, we will review an optical scanning approach to image processing that includes the capability of holographic recording.

In Big Data era, holographic data storage has become a good candidate recording technology, because of there are not only large storage capacities, but also high transfer rates. However, the realized capacity of it has a big gap to the theory. Polarization holography, a newly researched field, with the extraordinary capabilities in modulating the amplitude, phase, and polarization of light have resulted in several new applications, such as holographic storage technology, multichannel polarization multiplexing, vector beams, and optical functional devices. In this paper, the fundamental research on polarization holography with linear polarized light, a component of the theory of polarization holography, has been introduced. The polarization modulation realized using these polarization characteristics exhibits unusual functionalities, rendering polarization holography as an attractive research topic in a novel method for increasing the capacity of holographic data storage has been provided.

Holographic optical element (HOE) has excellent potential advantages to accomplish the complex optical characteristic in a single thin and light film. For augmented reality near-eye displays, it is one of the most suitable materials to achieve the desired optical components while maintaining a small form factor. However, the aberrations in the HOE causes critical disruption to image quality when holographic 3D images are displayed. Therefore, it is essential to correct the aberrations for holographic near-eye displays. In this paper, we propose a holographic augmented reality display with aberration compensated by wavefront control. With this approach our system provides a wide viewing angle (80 degrees) with negligible aberration compensating.

Cardiomyocytes form an electrically coupled syncytium which is the basis for the spatiotemporally synchronized propagation of macroscopic action potential wavefronts. Dysfunctional signal propagation patterns are a main cause of deadly tachycardia and are not yet fully understood. Optogenetics is a versatile toolset for the functional investigation of excitable cells and well-suited for the investigation of excitation wavefronts. We present a two-wavelength system using computer-generated holograms for the simultaneous stimulation and inhibition of induced stem-cell-derived human cardiomyocytes genetically sensitized to light, providing non-destructive models of myocardial scarring in vitro. The system is based on two beam paths, each comprising a binary ferroelectric SLM with frame rates reaching 1.7 kHz in a Fourier hologram configuration. To achieve near diffraction-limited spatial resolution, system-inherent aberrations are corrected digitally by superposing the light-pattern-generating holograms with sets of Zernike polynomials determined by an iterative optimization procedure. Thus, multiple foci or complex illumination patterns can be positioned three-dimensionally to illuminate multiple locations simultaneously to create defined excitation wavefronts. We show investigations on myocardial excitation control using different opsins like ChR2, ChRimson and BiPoles. This paves the way for future optogenetic heart rhythm control and the modeling of arrythmia induced by myocardial fibrosis using cardiac organoids in vitro.

Spatial light modulator is an essential electro-optical device in applications that require to modulate the amplitude, phase, or polarization of light. Its proper use requires to determine its Mueller matrix. In this work, we compare different methods to calculate the condition number of Mueller-Stokes polarimetry techniques, which defines their maximum relative error. Combining experimental and calculated values, we determined the most suitable method for calculating the condition number.

Presented is a technique for 3D structured light scanning based on Laser Beam Scanning with a two-dimensional resonantly operated MEMS mirror coupled with a continuous-wave infrared laser, and a low-cost imaging sensor. Dynamic lissajous patterns generated by a bi-resonant MEMS scanner improve the level of detail of 3D scans over time. Lissajous patterns are captured by a low-cost CMOS imaging sensor with short integration time. Due to pseudo-non-repeatedness of patterns, all pixels are illuminated within few consecutive images. The hardware complexity is reduced, making the system advantageous for mass production and integration in AR/MR headsets for various use-cases, such as hand gesture scanning, indoor SLAM, facial scanning, and avatar generation.

The Computed Tomography Imaging Spectrometer (CTIS) is a snapshot capable hyperspectral camera. A diffractive optical element is used to create multiple projections of the hyperspectral data cube side by side on the image sensor. A reconstruction algorithm computes the hyperspectral image from the spatio-spectral multiplexed signal. It solves a similar problem as the reconstruction algorithms used for Computed Tomography Scanners. We present how such a system can be realized by a parallelized approach. Several apertures are placed next to each other. Each aperture creates only one projection using a grating prism.

The manufacturing process of airbags products involves different and complex phases. An important one is the quality check using optical metrology methods both during the process and in its final phase. The aim of the present work is to study the advantages and limitations of utilizing a machine vision system for the above purposes. Thus, we report the development of a machine vision system for inter-phase and final quality check related to shape, dimensions, patterns, holes diameter, orientation, as well as the right sequence of processing airbag components. We utilized Basler/Cognex cameras with machine learning (ML)/artificial intelligence (AI) algorithms for inspection and CO2 lasers for cutting the components. Also, we developed (and further on optimized) in-house processes such as ultrasonic welding and dynamic positioning of components using cameras-guided robots. To validate the concept of the studies, several methods and tools have been utilized: virtual simulations programing tool (RobotStudio), CAD 3D mechanical design program (SolidWorks), Design of Experiments (DOE), Statistical Process Control (SPC), problem solving DMAIC (Define, Measure, Analyze, Improve, Control), as well as Process Failure Mode & Effects Analysis (PFMEA). The initial rejection rates (i.e., before applying these methods) were >30%, including false rejections. Overall, we reached an accuracy of 0.5 mm for dimensional measurements for textiles parts with different shapes in a field of view of 300 to 400 mm; rejection rate and false rejections <1.3%; an appropriate stability and repeatability of the manufacturing process.

Beam and image steering by Micro Electro Mechanical System (MEMS) Spatial Light Modulators decouples trade-offs between resolution, field of view, and size of displays and optics that is a common challenges found in optical designs. We overview solid state lidar and augmented reality display engine employing MEMS SLMs, Texas Instruments Digital Micromirror Device and Phase Light Modulators.

The need for free-form micro-optics (FFMO) is constantly growing in well-established business segments including flat-panel displays, solid-state illumination, thin-film solutions for security/anti-counterfeiting applications, AR/VR wearables, and automotive headlights. However, the high access barriers to pre-commercial production capabilities prevent companies, especially SMEs, from exploiting the FFMO technology in commercial products and hinder further innovation. To lower the barrier to access FMOA technology, CSEM and their partners have established the PHABULOµS Pilot Line. PHABULOµS offers a unique one-stop shop for all requests for prototyping and manufacturing of free-form micro-optics services, from pilot to full-scale production. To mature the FMOA technology, the Pilot Line members have developed high precision origination techniques complemented by industry-fit, high-throughput up-scaling technologies for the cost-effective production of large-area FFMO. At the core of these technologies is Step & Repeat UV imprinting. The method has been successfully demonstrated in the PHABULOµS project for high precision upscaling of rigid small masters to flexible tools with 600 x 300 mm2 dimensions using a standard UV-NIL stepper modified for this purpose. Since there is currently no commercial Step & Repeat machine on the market able to replicate free-form micro-structures on large area with the required precision, CSEM has developed a high precision S&R UV-replication platform designed specifically to this purpose. Combined with the expertise in design and optical simulation, origination, electroforming and metrology, the newly developed Step&Repeat and Roll-to-plate UV-imprinting capabilities at CSEM strengthens the PHABULOµS Pilot Line offerings.

We propose a scalable and energy-saving technology for monolithic polymer components such as aspheric lenses. UV-replication is well known from wafer level optics, where supporting glass wafers remain in the final lens, severely limiting the degrees of freedom of the optical design. In addition, material shrinkage occurring during curing the polymer limits reasonable sag heights of the lenses, so that only low-resolution imaging optics are possible. In our approach, the substrate in the individual lenses can now be omitted and a compensation of the shrinkage is achieved with minimum form error. This enables sag heights and aspherical lens profiles on both sides of thin menisci as required in high-resolution imaging optics so far realized by injection molding only. Since the replication is carried out at room temperature, less energy is required compared to injection molding leading to a more eco-friendly production. In addition, demonstrators, prototypes, small and medium series products of complex imaging systems can now be addressed economically due to low-cost material for tools and masters. The used materials are compliant to high temperature requirements enabling reflow-soldering. We present details of our technology at the example of realized demo systems towards high-volume, low-cost and high-performance lens stacks ultimately targeting mobile imaging applications.

Digital Optics, especially in the form of flat wafer level optics (as with diffractive optics, computer generated holograms, holographic optical elements, MEMS and MOEMS, metasurfaces,...) are key building blocks to achieve small form factor display, imaging and sensing systems. However, flat optics do not necessarily lead to flat optical systems. Moreover, alignment of optical elements within a system can often be more costly than the optics themselves, leading to lower systems yields or to systems prone to misalignment in the field. We review here various optical architectures using wafer scale digital optics along with specific fabrication technologies that eventually lead to flat optical systems with high yields and very tight alignment features.

High power VCSEL systems are a versatile and powerful tool for thermal treatment in industrial production where they enable a very homogeneous and locally controllable irradiance distribution at small working distances. Due to the inherent divergence of VCSELs, both characteristics degrade with increasing working distance. Depending on the size of the used VCSEL system, already at distances of about 100 mm the irradiation is not homogenous anymore and the local controllability is strongly limited already at even smaller distances. To extend the application range of VCSEL systems for increased working distances while maintaining homogeneity and local controllability, two multi-aperture beam integrators have been designed. Simulation results as well as measurements of a prototype system are presented in this work.

Optical systems in lithography machines play a significant role in their performance and, therefore, need to be optimized for specific applications. Artificial Intelligence (AI) and, in particular, metaheuristics are utilized in optimization algorithms for finding a diverse set of feasible and high-performing designs. The diversity requirement of the produced solutions is enforced to allow taking into account additional constraints that are difficult to formalize. In this work, we analyse the space of solutions previously produced by a niching evolutionary algorithm for the Cooke Triplet optical system and propose an approximation of the manifold where all high-performing designs exist. First, we show the existence of high-performing optical designs that are structurally different from the 21 previously known theoretical solutions. In order to do this, we develop a general computationally efficient methodology to create a partition of known high-quality points and their (accidentally found) improvements to their corresponding attraction basins, in the case when neither the exact number of landscape attractors nor their locations are known. We construct a manifold estimation which contains high-performing solutions by fitting a Gaussian Process-based classifier which predicts if an arbitrary design is close to high-performing. The proposed approach shows that AI-assisted optimization is beneficial, and it can be used to extend the capabilities of lithographic scanners and metrology equipment. Furthermore, it opens the possibility of studying other industrial applications.

In previous work, we have demonstrated that machine learning algorithms are powerful design tools for systems of multiple cascaded phase masks (diffractive neural networks). By treating each phase mask as a layer and using machine learning techniques to this network of layers is trained. We show here that this method also has advantages for designing single phase masks, when compared to phase mask design based on variations of the Gerchberg-Saxton algorithm. Our algorithm allows setting of additional optimization goals for instance for the homogeneity of the resulting mask.

We introduce an innovative concept for 3D imaging that utilizes a structured light principle. While our design is specifically tailored for collaborative scenarios involving mobile transport robots, it is also applicable to similar contexts. Our system pairs a standard camera with a projector that employs a diffractive optical element (DOE) and a collimated laser beam to generate a coded light pattern. This allows a three-dimensional measurement of objects from a single camera shot. The main objective of the 3D-sensor is to facilitate the development of automatic, dynamic and adaptive logistics processes capable of managing diverse and unpredictable events. The key novelty of our proposed system for triangulation-based 3D reconstruction is the unique coding of the light pattern, ensuring robust and efficient 3D data generation, even within challenging environments such as industrial settings. Our pattern relies on a perfect submap, a matrix featuring pseudorandomly distributed dots, where each submatrix of a fixed size is distinct from the others. Based on the size of the working space and known geometrical parameters of the optical components, we establish vital design constraints like minimum pattern size, uniqueness window size, and minimum Hamming distance for the design of an optimal pattern. We empirically examine the impact of these pattern constraints on the quality of the 3D data and compare our proposed encoding with some single-shot patterns found in existing literature. Additionally, we provide detailed explanations on how we addressed several challenges during the fabrication of the DOE, which are crucial in determining the usability of the application. These challenges include reducing the 0th diffraction order, accommodating a large horizontal field of view, achieving high point density, and managing a large number of points. Lastly, we propose a real-time processing pipeline that transforms an image of the captured dot pattern into a high-resolution 3D point cloud using a computationally efficient pattern decoding methodology.

Traditional optical design aims to minimize aberrations by utilizing multiple surfaces and/or lens materials to achieve the degrees of freedom (DOF) that satisfy given performance requirements and constraints. Currently available spherical refractive and reflective surfaces, including aspheric surfaces, offer limited DOFs per surface for controlling geometric aberrations and when created using different Abbe number materials, the additional DOF allow for chromatic aberrations to be compensated. Recent advancements in the inkjet print manufacturing of volumetric gradient-index (GRIN) optics have demonstrated added DOF in the form of dimensionally varying index gradients that make it possible to eliminate the need for multiple homogeneous-index surface-figured lenses. When the refractive index spectra of the feedstock is precisely formulated, it is possible to obtain the DOF to achieve independent control over primary and secondary dispersion. This permits a single monolithic GRIN device to accomplish the optical functions of multiple homogeneous-index surface-shaped optics. The measured results from a series of GRIN lenses, sized up to 75-mm diameter, will be described. The lenses will include plano-plano GRIN lenses that implement spheric , high-order aspheric, and freeform optical functions, plano-convex GRIN lenses, which distribute optical functions between the optical surface and the embedded index distributions, as well as aspheric-surfaced, aspheric-GRIN optical elements, which may be the most DOF ever exhibited in a monolithic optical lens element.

The Hong-Ou-Mandel phenomenon is essential for quantum computing with linear optics which is facilitated via beam-splitters in integrated optics. Based on this effect, the sum of output phases α= θ1+θ2 of a beam-splitter affects the quantum interference between two photons, where θ1 (θ2) is the phase between the output ports from the first (second) input port. However, lossless beam splitters yield an immutable α= π. However, we demonstrate manufacturable lossy beam-splitter designs for an adjustable α, with adjoint-based topology optimization. This exhibited tunability of α in an integrated beam-splitter encourages new applications in quantum simulation and quantum information processing.

Optical metasurfaces are arrays of nanoparticles with designed shapes and materials that can alter light-matter interaction. In most cases, metasurfaces are built on a substrate which makes its surrounding environment inhomogeneous. The latter can lead to significant changes in the optical properties of metasurfaces compared to the case of a homogeneous environment. We analyzed such systems via relatively simple coupled-dipole approach and unveiled physical mechanisms behind the change of optical properties. Based on these results, we present a new practical strategy for dynamic manipulation of optical metasurfaces response via inhomogenity that is experimentally validated.

In recent years, Multipole decomposition of the scatterers’ response has found a lot of application in the analysis and design of photonic structures like nan-particles, nano-antennas and metasurfaces. Another computational photonic design approach is topology optimization, which is one of the most versatile and powerful methods in inverse design and it is capable of handling very large number of optimization parameters when combined with the adjoint methods. In this paper, we combined these two powerful design approaches to optimize electromagnetic response of photonic meta-atoms based on the Multipole decomposition. Using this approach, we are able to design dielectric nanostructures like nano-antenna and nano-particles with desired set of excited multipoles. A few examples will be presented to demonstrate the power and applications of the method. We will also discuss challenges and prospectives of the method.

We present a novel optical system for image processing using geometric-phase lenses, or Pancharatnam-Berry lenses. These are patterned half-wave plates, where the optical axis follows a quadratic relation with the radial coordinate. They are planar lenses that offer high diffraction efficiency and polarization selectivity, and present convergent and divergent focalization for left and right circularly polarized input light. This polarization selectivity introduces a new degree of freedom for optical imaging. Different simple band-pass filtering experiments for binary objects are presented. As a new optical device, the unique performance of such multifunctional geometric-phase lenses offer potential applications in optical imaging.

Holographic laser processing system has an architecture composed of three subsystems of a laser processing system, a holographic optical engine (HolOE), and a computer-generated hologram (CGH) server for easy instruction and improvements. They perform small dependent operation because they have separate computers . The holographic beam shaping achieved by exploiting the rewritable capability of a spatial light modulator (SLM) displaying a CGH is very useful in a variety of applications, especially material laser processing. The HolOE that performs an optimization of the CGH in the optical system, called as an in-system optimization, was developed to use the holographic method toward the real industrial implementation in material laser processing. The HolOE can automatically compensate static imperfections and dynamic changes of the optical system and perform shaped-beam laser processing with a high quality.

For Augmented Reality Head-up Displays (AR-HUDs), the main challenge is to realize the good imaging performance within a small volume. ZEISS Microoptics introduces an innovative technology based on multilayer holographic structure. It offers large degrees of freedom to improve the imaging performance of the AR-HUDs in a compact volume. It provides large flexibilities of the shape, the size, and the position and to increase the color performance. This work of ZEISS Microoptics provides a break-through solution, which overcomes the disadvantages of mirrors, lenses and the single-layer Holographic-optical elements (HOEs). It provides an insight to realize compact high-performance optical functions.

Micro-optics and microlens arrays (MLA) are becoming the enabling technology in the miniaturisation of projectors and beam shapers in automotive lighting and 3D optical sensing applications. The technology is based on advanced micro-optical homogenisers with embedded pattern generation. While the basic concept has become rather mature in a handful of applications over the last few years, we are currently extending the functionality and optical quality of the systems. This requires the application of physical optics in a typical ray tracing domain. We will present our hybrid approach of physical optics and partial coherence simulation for beam shaping and real-world microprojectors. While advancing the technology to smaller feature sizes and higher quality in the micro-optics manufacturing, we are being pulled by demanding imaging and vision application towards very challenging optical designs and simulation approaches. The diffraction effects caused by either embedded metallic patterns or simple microlens arrays are becoming the limiting influence on the image quality of the target pattern and beam shapes, respectively. Multimode laser, partial coherent light sources and broadband LED sources can be handled with similar optical design tools to address these challenges and to understand the limits and opportunities in micro-optics-based illumination and lighting applications. We are applying Gaussian beamlet decomposition, large numbers of optical modes in pseudo-coherent raytracing or field tracing. These tools have been available for some time, but their true potential can only be tapped now with massive parallel computing (MPC) and recent advancements in sophisticated field tracing algorithms. Especially in high-quality imaging systems for microprojectors and 3D sensing systems a predictive optical modelling is mandatory and being demonstrated to better understand and utilise the interaction of light sources, pattern generator and optical detection, be it a camera or simply the demanding human perception.

LIV curves are fundamental measurement of laser diodes to determine electrical and optical operating characteristics. LIV curves consist of L-I curves (optical intensity against current) and V-I curves (voltage against current). LIV curve determine power conversion efficiency, threshold current, slope efficiency, kinks, rollover point and more. They are widely used at various stages since it is critical to identify failed DUTs early in the manufacturing process. LIV curves are always measured for the DUTs with single emitter or for DUT as a whole when consist of many emitters. Detailed and comprehensive LIV test, spectrum and beam analysis of each single emitters of an array is the focus of this study. We extended existing one-dimensional LIV test, spectral and beam analysis (including beam numerical aperture, M2 and beam waist) to each single emitters of the laser diode array at well-controlled conditions. Our experimental design consists of camera based radiant power and spectrum measurement. This approach allows parallelization of the measurements, which reduces overall measurements time, and investigation on the cross-talk between individual emitters. We analyzed electrical, optical and spectral differences within emitters of a VCSEL array and as well with the array as a whole. The accepted range of variation can be set in order to identify underperforming or out-of-specification single emitters. Therefore defect or deficient laser diodes are detected at early stages of the manufacturing process, saving time and money. Such comprehensive characterization of arrays individual emitters is crucial for demanding applications such as facial recognition, 3D sensing, in cabin sensing, LiDAR and ranging.

We demonstrate the second generation of miniaturized, full-color RGB light source modulea with a collimated beam output for near-to-eye display systems, incorporating semiconductor laser diodes (LDs) for blue and green emission and a broadband superluminescent diode (SLED) for red emission. This new generation of hybrid LD-SLED RGB light source modules supports output power levels per color ranging from a few milliwatt up to 50 mW per color, in combination with diffraction-limited, collimated beams having a high circularization of better than 80% with beam diameters from 0.6 mm up to 2.0 mm, supporting high efficiencies and high resolution for waveguide-based AR glasses.

Emissive OLED-on-silicon microdisplays have been considered being opaque only so far. However, modern and advanced silicon CMOS process nodes are increasingly made on silicon-on-insulator (SOI) substrates. By separating the SOI handle wafer from the buried oxide (BOX) layer (that has the active silicon on top) and applying space-cautious layout design of the CMOS active devices as well as wiring layers it is possible to achieve semitransparent, high-resolution CMOS backplanes for microdisplays. Similar to regular OLED-on-silicon the emissive frontplane becomes embedded by wafer-level OLED post-processing. Yet, depending on pixel density and array layout a microdisplay transparency of >20% can be achieved now. Consequently, the semi-transparent microdisplay becomes the optical combiner itself, eliminating the exit pupil expander (EPE), which drastically improves the optical efficiency from the light source into the eye box. Additionally, new high-brightness OLED achieving >35kcd/m² in monochrome, or 10kcd/m² in color versions, and their integration onto the OLED-on-SOI platform and an ultra-low power pixel cell backplane architecture (power consumption <10mW) pave the way for matching both form factor and battery life requirements in optical see-through NTE, enabling new optical concepts for augmented-reality (AR) devices. This presentation will report on an initial technology demonstrator, featuring a semi-transparent OLED-on-SOI backplane.

Although being a rapidly developing field, autonomous driving already starts facing challenges in terms of safety for the humans surrounding the vehicle, like pedestrians or cyclists. The communication between the vehicle and its close proximity could overcome such issues, e.g., by projecting patterns onto the street to inform about actions which will be taken by the vehicle: turn, stop... Such a projection system is required to yield a large projection pattern in order to cover the whole circumference of the vehicle with few projectors only, dynamic content to be adapted to the traffic situation, and a very high brightness for daylight situations. We propose a high-performance solution based on holographic projection. It utilizes the collimated beams of four laser diodes that are independently shaped by one reflective, high-definition LCOS Spatial Light Modulator. A compact optomechanical design includes telescope optics to enlarge the projected fields, which are stitched laterally to achieve a 0.3 x 1 m² projection separated less than 50 cm from the vehicle. Image stitching as well as distortion correction is applied in the hologram generation algorithm. In result, we achieve the projection of dynamic patterns (above 60 fps) that can surround the full perimeter of the vehicle with a brightness in the 1-10 klux range depending on the projected pattern.

We present a roadmap for integrating metasurfaces with conventional optics in digital optical systems. It highlights the current design, fabrication, and testing challenges and underscores the role of digital tools in the system integration process. The potential of metasurfaces is illustrated through applications such as compact imaging systems for AR displays.

We present a method to measure Modulation transfert function (MTF) of an optical device with digital random target Current know method using this way to compute MTF must average the calculus accross a part of the Field of View of the device We use the digital target with the possiblity to display a sequence of random target and we use the local intensity correlation identify pixels of the target and pixels of the sensor : this permit the calculation of the MTF in local region of the Field of view (center or border for example) by also and direct measurement of the Point Spread Function and primary aberration and distortion with very low noise

Optical imaging deep into biological tissue is a great challenge due to strong scattering. It has been shown in the last years that wavefront shaping employing a digital spatial light modulator (SLM) has the power to exploit the scattered light to enhance the penetration depth. Commonly, a guide star emitting a known wavefront is required to probe the scattering events and to figure out the required mask to be displayed. To easily separate the illumination and guide star light, two-photon processes are suitable. However, two-photon effects based on fluorophores are incoherent and thus most often iterative approaches are used which can be time-consuming. The second harmonic generation (SHG) is a coherent process, which enables harmonic holography and therefore direct determination of an appropriate mask. However, the asymmetry of excitation and detection wavelengths has to be studied for the resulting penetration depth. We use Monte-Carlo simulations to study the achievable penetration depths of SHG-based guide stars and compare the results with the penetration depth of conventional techniques. Furthermore, we present experimental wavefront shaping results that show an excellent agreement to the simulations and that promise penetration depths in the cm range.

Fresnel zone aperture (FZA) lensless imaging encodes the incident light into hologram-like pattern, so that the scene image can be refocused by back propagation method. However, the inherent twin image and inaccuracy focusing distance degrade the imaging quality. This brings difficulties for the target classification and recognition applications. We proposed a high-quality reconstruction and autofocusing method for FZA lensless imaging. By investigating the image sharpness metrics on the back propagation images, the accuracy focusing distance could be estimated. Total variation regularization based alternating direction method of multipliers algorithm is proposed to suppress the twin image existing in the back propagation reconstruction. Experimental results show that the proposed method can significantly improve the target recognition rate.

Model predictive control (MPC) can use the state of the current measurement processing to predict future events and be able to take control processing accordingly. To implement MPC in our adaptive optics system (AOS), a multichannel state-space model is first identified between the driving voltage for a 61-channel deformable mirror (DM) as the input and the 8-order Zernike polynomial coefficients via a lab-made Shack-Hartmann wavefront sensor (SHWS) as the output. Conventionally, the center of weight algorithm is utilized to reconstruct the wavefront from SHWS, but it takes a lot of computation time. Therefore, a deep learning (DL) approach based on U-Net is adopted to rapid reconstruct the wavefront. The U-Net significantly reduces the time to compute the wavefront and also gets the higher accuracy. After that, the MPC controller based on the identified system model is implemented in AOS. Currently, the simulation results demonstrate that the MPC with the DL-SHWS can fast correct the wavefront aberration. Eventually, the MPC-based AOS will be implemented under Robot Operating System (ROS) to achieve real-time control.

The Talbot effect was first observed in 1936 by Henry Talbot and has been widely applied in many optical techniques. In this work, we use the Talbot effect to project the scanning basis functions used in single-pixel imaging techniques onto the object. We codify Walsh-Hadamard patterns in each unit cell of a 2D binary grating by means of a DMD, and apply single pixel imaging techniques to record images with high resolution by using a light sensor with a low number of pixels. The idea can be useful to increase resolution of IR or THz cameras. Preliminary results are shown.

Development of fiber optical networks as the backbone of the global infrastructure has driven exponential growth in data demands. Space division multiplexing (SDM) over few-mode fibers (FMF) spatial domain is proposed to enhance optical networks’ capacity limits by orders of magnitude compared to state-of-the-art single mode fibers. Based on multiplane light conversion (MPLC), multiple input beams are converted to the FMFs mode domain and launched into the fiber. Inside the MPLC the beams are modulated by a phase-changing element within several passages and are shaped in amplitude and phase due to diffraction. We use a spatial light modulator (SLM) for the implementation of the MPLC, whose programmability allows us to sample the MPLCs behavior and compensate on phase and polarization aberrations during operation. Conventionally, phase masks are calculated in advance that carry out a spatial transformation between spatially distributed input spots and coaxial output modes. After calculation, phase masks are either printed on dielectric mirrors or displayed on diffractive optics. This process entails two-fold problems. First, the phase masks are calculated offline and inserted into the experiment later on, where small deviations cause enormous performance reductions. Second, phase mask printing can barely adapted after fabrication. We propose a data-driven optimization of the displayed phase mask by using machine learning to overcome the hurdles of re-configurability and alignment. We use neural networks (NNs) for digital calibration to ensure pixel-precise alignment. Our implementation of the MPLC with a SLM is mimicked as a digital twin by a NN, the model-NN. In a second step, the fixed model-NN is controlled by another neural network called actor-NN. After the calibration, our Actor-Model scheme predicts phase patterns for the SLM based on the desired intensity distribution after the MPLC, i.e. the FMFs mode patterns. By digitally sampling and control of the MPLCs behavior with NNs, we improved the SLMs beam-shaping quality without suffering from the SLMs refresh rate limitations, depending on the available filling factor and resolution. The adaptability of the SLM as a digital optical device allows further re-calibration during operation. Due to the all-optical implementation, transmission and multiplexing of delicate quantum states is proposed.

Fixation stability is the ability of the eyes to maintain a constant and stable gaze on the fixation target. One of the visual functions that can be affected by unstable fixation is stereopsis. Stereovision is important for a variety of daily tasks, as well as for using stereoscopic displays in visualizations and entertainment, such as watching movies and playing video games. The interaction between fixational stability and stereopsis in different conditions has often been studied in children with amblyopia. The aim of our research is to explore the relationships between binocular fixation stability and stereopsis in school-aged children who do not have amblyopia and strabismus in their anamnesis. The children were divided into two groups: those with normal stereoacuity (≤ 60 arcsec in the TNO test) and those with reduced stereoacuity (≥120 arcsec in the TNO test). The fixation target was demonstrated on a computer screen, and eye movements during fixation were recorded using a Tobii Pro Fusion eye tracker operating at 250 Hz. The results demonstrate that children with better stereoacuity tend to have more stable fixation compared to children with reduced stereoacuity. However, the difference in fixation stability was not significant.

The alignment of optical components is one of the fundamental tasks faced in the optical manufacturing industry. If the problem is extended to miniaturized aspheric glass lenses, or lens systems, the complexity is further increased. Wavefront sensors are commonly used in the precision alignment of optical components, and they provide an elegant and efficient tool for systems with high complexity. We have implemented an alignment simulation environment which is based on the Zemax optics studio (ZOS) and related application interface (API). This tool is used to create a set of linear equations or neural network which are used to solve the relation between the wavefront and the optical element alignment.

Angular diffractive lenses can produce narrow and elongated focal regions. We generalize the definition of its focal length by expanding its angular variation as a Fourier series, whose coefficients are optimized by Particle Swarm Optimization algorithm. We compare the performance of the Fourier series diffractive lens (FSDL) with other previous extended depth-of-focus diffractive lenses. Our FSDL design generates the narrowest and, especially, the most uniform beam. Finally, we have verified experimentally the FSDL performance with a spatial light modulator, concluding that the experimental results are in good agreement with the simulations.

Laser scanners using Micro-Electro-Mechanical Systems (MEMS) with oscillatory mirrors are one of the most promising types of such devices. The aim of this work is to approach the implementation of various scan patterns using such MEMS scanners. Raster, spiral, and Lissajous scan patterns are programmed and generated, with different characteristic parameters. The starting point of the study is our approach on raster scanning using galvanometer-based scanners (GSs) to design optimal functions of such systems. In this respect, MEMS scanners are a particular case of GSs for which both oscillatory mirrors are placed in the same plane, thus improving the focusing of the device. A comparison is made between such scanning modalities: performances are evaluated based on the several criteria such as speed, resolution, field-of-view (FOV), fill factor (FF) and linearity of the generated scan patterns. Experimental validations are performed to determine the offset that is occurred in the actual implementation. Possible applications where this scanning technique may be preferred are pointed out.

We propose the use of a simplified model for the analysis of the scattering elements used in edge-lit systems. By modelling their behavior as lambertian light sources whose properties depend on the size and geometry of the scatterer and LGP (Light Guide Plane), it is possible to simulate the illuminance map of the edge-lit structure using only 2D ray-traced simulation. This reduces the computational complexity in the optimisation process used to calculate the scatterers distribution for achieving maximum uniformity in light extraction. The results obtained by comparison between the proposed algorithm and the a commercial software demonstrate the validity of the proposal.

The propagation of a light beam through a photo-sensitive photo-polymer Polyvinyl Alcohol/Acrylamide (PVA/AA) and the creation of self- writing waveguides (SWW) have received much attention. Here we explore the manufacture of SWW in PVA/AA for applications at near infrared and at telecommunication wavelengths. The PVA/AA was photo-sensitized using the dye Erythrosine B (EB), at a wavelength of λ=532nm. Waveguides are created through a self-writing process. Light from a multi-mode fibre, incident on a solid bulk sample, generates an index change through photo-polymerization to produce a stable (permanent) waveguide. We use the reflection method to characterize the self-written waveguide. The use of a Y-Splitter multi-mode testing system is to aid in the measurement of the optical medium and the light source is generated by a wide band optical transceiver with a sensitivity of 10 x 10-9 watts. The mirror, acts as the reflector, has been tested with various wavelengths including the test wavelength λ=532nm. The Y-Splitter multi-mode test system is used to trap the reflected light towards the optical receiver and to measure a sample of the optical power. By having already characterized the Y-Splitter multi-mode optical system it is possible to calculate the optical return loss and the reflected light thereby calculating the loss across the photopolymer. The photopolymer and the creation of self- writing waveguides are also investigated with the use of two other wavelengths, used in the communication industry, λ=850nm and λ=1300nm. By using these two wavelengths along with wavelength λ=532nm to characterize the SWW and to calculate the characterisation loss of the three wavelengths (using λ=532nm as the reference), we investigate the future purpose of the photo-polymer material within the communication and sensing industry.

In hybridized nanostructures with a metallic counterpart, light beams can be trapped locally by the surface plasmons near the interface. However, dual plasmonic responses of such nanostructures can be further modified by the hot carrier mechanism taking place at the metal-semiconductor interface. Here, we simulated the optical responses, and absorption interplays in complex nanostructures made from gold and a highly doped semiconductor, namely copper sulfide, with respect to excitation wavelengths in broadband regime both in quasi-static approximation and transient regimes, respectively. Our simulation findings can well explain the mysterious puzzling behavior captured in experiments due to the hot carrier perturbations and plasmonic resonances.

Within PhoenixD project the design and construction of a phase-modulator based spectroscopic ellipsometer was realized which is orders of magnitude faster than the commercial rotation polarizer, or rotation compensator based ellipsometers available on the market. The device was attached to the linear moving stage so it can be easily integrated to the roll-to-roll type of production line. In this work we want to demonstrate the spatial accuracy and scanning capability of our home-made device using samples with horizontally different thin film structures on them. Furthermore, we want to analyze the lowest measurement time frame we can reach to extract the ellipsometric angles.

Introduction - Kilim plastics is a family business started in 1985. A company converting metal parts into plastic injection molded parts. Most are made of engineering glass filled polymers. We supply a cross section of the high tech and medical, aerospace and defense companies in Israel. (IAI, Orbotech , Elbit/Elop ,) and are ISO certified. For the last 6 years we invested in creating a department in our company, dedicated to optics by investing in diamond turning, and inspection equipment to measure optic lens profile. We engaged and are at a late stage and manufacture a high-quality optical test set directed for the education field mostly made off injection molded engineering polymers. The project is to enable learning and working with optics in a price bracket for use on each student table rather than an only set for a class, without reducing the quality. The optical kit includes: • A modular optical table, that can be configured to customer needs • Clamp forks, posts and kinematic mount holders Simcha kilim

With the development of industrial, medical and educational fields, industrial cameras that transmit and display images through a single interface cannot meet the needs of users. A multifunctional industrial camera that can transmit and display images through multiple interfaces and support switching between different frame format outputs can better meet the development needs of most industries. The camera designed in this paper supports real-time image output and display via HDMI and USB at the same time, supports real-time control of image ISP parameters at the PC side, and simplifies the operation of camera ISP parameter control under the UVC framework by designing private protocol commands.

Quality control is a critical aspect in the manufacturing of high-quality optical components. However, the traditional metrology techniques sag meters and test plates are often performed as the final step in the polishing process, leading to an increased number of defective parts and increased production costs caused by the need of many test plates. In this paper, we present an innovative approach to measuring radius of curvature and form error using an interferometer. The traditional method needs a pair of test plates for each curvature radius. This could cause very high costs in storage and maintenance for long-term use. In contrast, an interferometer can measure different radii of workpieces and is highly accurate. The measured data can be used in a closed-loop feedback system to compensate for form error and radius error in CNC controlled polishing machines. This innovative approach will significantly improve the flexibility and reduce the costs of the polishing process.

Image inpaintnig in textile manufacturing is a new emerging research topic in preprocessing for jacquard CAD systems. One of the most important aspects of a jacquard CAD system is the simulation of the appearance of a jacquard texture during inference. Jacquard image inpainting has become an indispensable process for the Jacquard CAD system. Jacquard image reconstruction is designed to restore a damaged image with missing information, so it is necessary to determine which parts of the image need to be repaired. Thus, this task includes two processing stages: the detection of defects and their recovery. This article presents a two-stage approach that combines new and traditional algorithms for detecting defects and repairing damaged areas. The first stage is a defect detection method based on a convolutional autoencoder (U-Net). The second stage is image inpainting based on exemplar-based concepts and the anisotropic gradient. Our system quantitatively outperforms state-of-the-art methods regarding reconstruction accuracy in the benchmark.

The construction of control and security systems is based on the use of data recording devices. The main element is the camera. The use of cameras has found wide application for many tasks. Most often they are stationary and do not allow to cover the entire territory, but allow to consider only its part. A camera system is used to expand the field of view. Reducing the number of fixation devices and, as a result, analyzing video streams is an urgent task that allows you to increase the efficiency and speed of decision-making. Implementation of camera movement systems can be realized with aircraft or fixed mount movement devices. The areas of application of such systems can be both security systems and devices for monitoring and analyzing processes. An example of such systems is an analyzer of filling storages, an analysis of the movement of people on the field (contact sports), manufacturing enterprises, etc. Manipulators with a suspension on flexible links are mechatronic devices, the design of which excludes rigid massive moving elements, and the movement of goods is ensured by changing the lengths of the cables. For such systems, fully automatic control, manual control by analogy with traditional cranes is possible. However, the most promising is the direct impact of a person on a suspended load in order to form the necessary movement vector. In this case, the person is in the working area of the manipulator and for him there is a risk of physical injury from the suspended load and cables. This paper considers the construction of an algorithm for automated analysis of the position of objects in a limited space (field, workshop, warehouse) with the possibility of constructing a control action for moving the camera and stitching video data. The method of parallel data analysis allows, in addition to constructing the optimal movement trajectory, to integrate the video subsystem into the manipulator control system, which will also allow assessing the relative position of the operator, cargo and obstacles located in the manipulator service area. The paper presents the structure and description of the construction of a video subsystem consisting of several neural accelerators with RISC-V core controllers and a video camera system. The structure of control formation for a group of controllers united in a single network with a central computer that transmits pre-processed data to the control system is presented. The presented technique makes it possible to form a system including: controllers, video processing, a computer and a control system that allow real-time processing.