Search

The field of advanced metamaterial design has witnessed the great progress of artificial intelligence (AI) for science. Typically, the widely used deep learning is a purely data‐driven approach. However, it is often assumed as a black box performing interpolation among training data in a fuzzy way, which suffers from poor generalization outside the training domain of critical physical parameters. Inspired by physics‐guided deep learning, a circuit‐theory‐informed neural network (CTINN) in order to strengthen the generalization of metamaterial design is proposed. A series of plasmonic stack metamaterials (PSMs) are taken as learning paradigms of CTINN. Compared to conventional deep learning, the scheme decreases one‐order lower test loss of spectral prediction beyond the structure training span, and it possesses an extraordinary function to predict spectra of the extrapolated wavelength range. Due to the physics‐informed mechanism, the CTINN only adopts 10% training samples of the pure data‐driven counterpart, while it reduces >50% test loss. Moreover, the CTINN design is used to guide the PSM experiments and demonstrate its great potential for metamaterial development. This work introduces the theory of equivalent circuits into the neural network, empowers physics supervision to AI, and accomplishes the smart and powerful design of PSMs. [ABSTRACT FROM AUTHOR]

The off-axis three-mirror anastigmatic (TMA) optical system has the advantages of eliminating all primary aberrations, having no aperture obscuration, no chromatic aberration, and good environmental adaptability, making it essential in high-performance optical instruments. Freeform surfaces, with their rich degrees of freedom (DOFs) in mathematical representation, positively affect the image quality and sensitivity of optical systems. When applied correctly to off-axis TMA optical systems, they can achieve fast F -numbers, large fields of view (FOVs), and long focal lengths. There are dozens of configurations for off-axis TMA optical systems, and freeform surfaces can be combined in numerous ways within these systems. This paper first analyzes the sensitivity of off-axis TMA optical systems with different configurations, selects the configuration with the lowest sensitivity, and combines it with a low sensitivity freeform surface combination to achieve high-performance freeform off-axis TMA optical systems with low sensitivity. [ABSTRACT FROM AUTHOR]

UVC‐LEDs have drawn attention recently because of their benefits to sterilization, decontamination, etc. Since the internal quantum efficiency and light extraction efficiency (LEE) of UVC‐LEDs are low, their external quantum efficiency remains unsatisfied. To enhance the LEE, this study proposes an integration design with the features of substrate‐thickness optimization, substrate shaping, diffuse‐reflective coating, an index‐matching layer, and taper‐base optimization. In addition to optical modeling via ray tracing, thermal modeling is conducted to evaluate both the optical and thermal performances of each feature. The simulation results show that, by means of the combination of these features, the LEE of the chip can be raised from 18.5% to more than 40%, and the average temperature of the device can be lowered by 2.2°C via the design of the diffuse‐reflective coating. [ABSTRACT FROM AUTHOR]

The near-eye display (NED) systems, designed to project content into the human eye, are pivotal in the realms of augmented reality (AR) and virtual reality (VR), offering users immersive experiences. A small volume is the key for a fashionable, easy-to-wear, comfortable NED system for industrial and consumer use. Freeform surfaces can significantly reduce the system volume and weight while improving the system specifications. However, great challenges still exist in further reducing the volume of near-eye display systems as there is also a limit when using only freeform optics. This paper introduces a novel method for designing compact freeform NED systems through a powerful optical-digital joint design. The method integrates a geometrical freeform optical design with deep learning of an image compensation neural network, addressing off-axis nonsymmetric structures with complex freeform surfaces. A design example is presented to demonstrate the effectiveness of the proposed method. Specifically, the volume of a freeform NED system is reduced by approximately 63% compared to the system designed by the traditional method, while still maintaining high-quality display performance. The proposed method opens a new pathway for the design of a next-generation ultra-compact NED system. [ABSTRACT FROM AUTHOR]

Freeform liquid–crystal polarization imaging optics (LPIOs) have vast potential for application in next‐generation interactive displays like augmented reality and virtual reality. However, tailoring the phase profile of a freeform LPIO for flexible aberration correction and diffraction efficiency control is still a big challenge due to the difficulties arising from the non‐zero étendue of an imaging system and the finite bandwidth of LPIOs. Here, a practical approach to creating freeform LPIOs from design to fabrication is proposed. A freeform polarization exposure is developed to produce a flexible, precise, and ultra‐high‐resolution photoalignment pattern for a freeform LPIO. A cooperative optimization is performed between the freeform LPIO and the freeform polarization exposure system to find the optimal phase of the freeform LPIO and the optimal surface profiles of the freeform lenses employed in the exposure system to produce freeform wavefronts. The optimal phase of the freeform LPIO is then achieved by superposition interference of the engineered freeform wavefronts via freeform polarization exposure. The effectiveness of the approach and the advantages of freeform LPIOs is experimentally demonstrated. The proposed approach will significantly promote the widespread applications of freeform LPIOs in the field of optics and photonics. [ABSTRACT FROM AUTHOR]

Recently developed sixth-order wave aberration expressions of soft X-rays and a vacuum ultraviolet optical system are first extended to plane-symmetric refractive optical systems, and then, applying the transformation relations between plane-symmetric and paraxial refractive optical system, the sixth-order intrinsic and extrinsic wave aberration coefficient expressions of a paraxial refractive optical system are derived. In addition, the corresponding fifth-order aberration expressions are also obtained. Finally, the resultant aberration expressions are applied to calculate the aberration on the image plane of one design example of a paraxial refractive optical system with a large aperture, and these calculation results are compared with ones obtained by ray-tracing software Zemax to prove that they have satisfactory calculation accuracy. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) excels in engineering intricate shapes, pioneering functional components, and lightweight structures. Nevertheless, components fabricated through AM often manifest elevated residual stresses and a myriad of thermally induced micro-instabilities, including cracking, incomplete fusion, crazing, porosity, spheroidization, and inclusions. In response, this study proposed a sophisticated multi-sensing inspection system specifically tailored for the inspection of thermally induced micro-instabilities at the micro–nano scale. Simulation results substantiate that the modulation transfer function (MTF) values for each field of view in both visible and infrared optical channels surpass the benchmark of 0.3, ensuring imaging fidelity conducive to meticulous examination. Furthermore, the innovative system can discern and accurately capture data pertaining to thermally induced micro-instabilities across visible and infrared spectra, seamlessly integrating this information into a backend image processing system within operational parameters of a 380–450 mm distance and a 20–70 °C temperature range. Notably, the system's design is harmoniously aligned with the requisites of processing and assembly, heralding a significant advancement in bolstering the inspection effect of thermally induced micro-instabilities for the AM component. [ABSTRACT FROM AUTHOR]

This study presents the design and development of a high-resolution convex grating dispersion hyperspectral imaging system tailored for unmanned aerial vehicle (UAV) remote sensing applications. The system operates within a spectral range of 400 to 1000 nm, encompassing over 150 channels, and achieves an average spectral resolution of less than 4 nm. It features a field of view of 30°, a focal length of 20 mm, a compact volume of only 200 mm × 167 mm × 78 mm, and a total weight of less than 1.5 kg. Based on the design specifications, the system was meticulously adjusted, calibrated, and tested. Additionally, custom software for the hyperspectral system was independently developed to facilitate functions such as control parameter adjustments, real-time display, and data preprocessing of the hyperspectral camera. Subsequently, the prototype was integrated onto a drone for remote sensing observations of Spartina alterniflora at Yangkou Beach in Shouguang City, Shandong Province. Various algorithms were employed for data classification and comparison, with support vector machine (SVM) and neural network algorithms demonstrating superior classification accuracy. The experimental results indicate that the UAV-based hyperspectral imaging system exhibits high imaging quality, minimal distortion, excellent resolution, an expansive camera field of view, a broad detection range, high experimental efficiency, and remarkable capabilities for remote sensing detection. [ABSTRACT FROM AUTHOR]

Improving the spectral signal-to-noise ratio is crucial for obtaining high-quality Raman spectra of target substances. To achieve a higher instrument signal-to-noise ratio in the development of spatial heterodyne Raman spectrometer, the effect of spatially compressed illumination on the spectral signal-to-noise ratio was theoretically analyzed. A spatial heterodyne Raman spectroscopic experimental setup with compressed illumination was constructed. The experimental results with ethanol validate the significant enhancement of the signal-to-noise ratio achieved through compressed illumination. The ethanol spectra exhibited signal-to-noise ratio enhancements ranging from 1.38 to 7.98 times under various excitation powers and integration times. These findings provide valuable guidance for further improving the performance of spatial heterodyne Raman spectrometers. [ABSTRACT FROM AUTHOR]

Augmented reality overlays computer-generated virtual information onto real-world scenes, enhancing user interaction and perception. However, traditional augmented reality optical systems are usually large, bulky, and have limited optical performance. In this paper, we propose a novel compact monochrome reflective dielectric metalens visor with see-through properties, engineered using a periodic structure of spin-dependent supercells. The supercell, which is composed of staggered twin nanofins, provides spin-dependent destructive or constructive interference with different circularly polarized incidences. The design combines the principles of interference with the Pancharatnam–Berry phase to enhance reflection at a working wavelength of 650 nm while maintaining good transmission. Right circularly polarized light incident from the substrate side causes destructive interference, enabling the supercell to work in reflection mode, while left circularly polarized light causes constructive interference, enabling the supercell to work in transmission mode. Furthermore, the supercell-constructed metalens can achieve near-diffraction-limited reflective focusing and a broad diagonal field of view of approximately 96°. In addition, compared to transmissive metalens visors, the reflective design eliminates the need for a beam splitter, significantly reducing the size and weight of the system. Our work could facilitate the development of compact and lightweight imaging systems and provide valuable insights for augmented reality near-eye display applications. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Light field cameras are unsuitable for further acquisition of high-quality images due to their small depth of field, insufficient spatial resolution, and poor imaging quality. To address these issues, we proposed a novel four-focal-square microlens and light field system. A square aspheric microlens array with four orthogonal focal lengths was designed, in which the aperture of a single lens was 100 μm. The square arrangement improves pixel utilization, the four focal lengths increase the depth of field, and the aspheric improves image quality. The simulations demonstrate pixel utilization rates exceeding 90%, depth-of-field ranges 6.57 times that of a single focal length, and image quality is significantly improved. We have provided a potential solution for improving the depth of field and image quality of the light field imaging system. [ABSTRACT FROM AUTHOR]

In the scope of the latest upgrade of the Swiss Light Source, five hard X-ray beamlines will be constructed or rebuilt. To use synergies between these beamline projects, a concept is developed here for hard X-ray beamlines that is tailored to the new storage ring. Herein, this concept is described from the source, via the front end, to the beamline optics. The latter will be outlined in detail, including a new and modular concept for hard X-ray monochromators, focusing optics and heat-load management. With a simple, easy-to-operate and robust beamline design, the new beamlines will greatly profit from the increased brilliance of the new storage ring. The performance increase is up to four orders of magnitude, while the beamline concept allows for the broad application of experimental techniques, from propagation-based methods, such as phase-contrast tomography, to imaging techniques with nanometre resolution. At the same time, spectroscopy experiments are possible as well as high-performance serial X-ray crystallography.

In the athermal and apochromatic design of optical systems, the distribution of lens' optical powers and the selection of optical glass and structural materials are crucial. In this paper, an athermal and apochromatic design method is proposed for optical systems with a long focal length, large relative aperture, and wide spectrum. Firstly, a complex optical system composed of multiple lenses is equivalent to a two-component, single-lens system consisting of a replacement and an equivalent lens group. The optical glass for the replacement lens group is selected based on weight and the principle of material replacement in the 3D glass diagram, thus achieving an athermal and apochromatic design. Secondly, an athermal and apochromatic optical system with a focal length of 130 mm, an F-number of 2.0, a spectral range of 480 nm~800 nm, a field of view angle of 22°, and an operating temperature of −40 °C~+60 °C is designed. The modulation transfer function (MTF) at each field of view is greater than 0.6 at 50 lp/mm in the −40 °C~+60 °C temperature range, and the secondary spectrum aberration is 0.0056 mm, which is within the focal depth range of the optical system. [ABSTRACT FROM AUTHOR]

With off-axis reflection systems with specific distortion values serving as objectives or collimators, it is possible to compensate and correct for spectral line bending in spectroscopic instruments. However, there is limited research on the precise control of distortion, which poses particular challenges in large field-of-view optical systems. This paper presents a method for controlling distortion in off-axis reflection systems. Based on Seidel aberration theory and the relationship between distortion wavefront error and primary ray error, we construct objective functions with structural constraints and aberration constraints. The initial structure with specific distortion values is then solved using a differential evolution algorithm. The effectiveness and reliability of this method are verified through the design of an off-axis three-reflection system. The method provided in this study facilitates the design of remote sensing instruments. [ABSTRACT FROM AUTHOR]

Hyperspectral detection of the change rate of organic matter content in agricultural remote sensing requires a high signal-to-noise ratio (SNR). However, due to the large number and efficiency limitation of the components, it is difficult to improve the SNR. This study uses high-efficiency convex grating with a diffraction efficiency exceeding 50% across the 360–850 nm range, a back-illuminated Complementary Metal Oxide Semiconductor (CMOS) detector with a 95% efficiency in peak wavelength, and silver-coated mirrors to develop an imaging spectrometer for detecting soil organic matter (SOM). The designed system meets the spectral resolution of 10 nm in the 360–850 nm range and achieves a swath of 100 km and a spatial resolution of 100 m at an orbital height of 648.2 km. This study also uses the basic structure of Offner with fewer components in the design and sets the mirrors of the Offner structure to have the same sphere, which can achieve the rapid adjustment of the co-standard. This study performs a theoretical analysis of the developed Offner imaging spectrometer based on the classical Rowland circular structure, with a 21.8 mm slit length; simulates its capacity for suppressing the +2nd-order diffraction stray light with the filter; and analyzes the imaging quality after meeting the tolerance requirements, which is combined with the surface shape characteristics of the high-efficiency grating. After this test, the grating has a diffraction efficiency above 50%, and the silver-coated mirrors have a reflection value above 95% on average. Finally, the laboratory tests show that the SNR over the waveband exceeds 300 and reaches 800 at 550 nm, which is higher than some current instruments in orbit for soil observation. The proposed imaging spectrometer has a spectral resolution of 10 nm, and its modulation transfer function (MTF) is greater than 0.23 at the Nyquist frequency, making it suitable for remote sensing observation of SOM change rate. The manufacture of such a high-efficiency broadband grating and the development of the proposed instrument with high energy transmission efficiency can provide a feasible technical solution for observing faint targets with a high SNR. [ABSTRACT FROM AUTHOR]

In the scope of the latest upgrade of the Swiss Light Source, five hard X‐ray beamlines will be constructed or rebuilt. To use synergies between these beamline projects, a concept is developed here for hard X‐ray beamlines that is tailored to the new storage ring. Herein, this concept is described from the source, via the front end, to the beamline optics. The latter will be outlined in detail, including a new and modular concept for hard X‐ray monochromators, focusing optics and heat‐load management. With a simple, easy‐to‐operate and robust beamline design, the new beamlines will greatly profit from the increased brilliance of the new storage ring. The performance increase is up to four orders of magnitude, while the beamline concept allows for the broad application of experimental techniques, from propagation‐based methods, such as phase‐contrast tomography, to imaging techniques with nanometre resolution. At the same time, spectroscopy experiments are possible as well as high‐performance serial X‐ray crystallography. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The off-axis three-mirror anastigmatic (TMA) optical system has the advantages of eliminating all primary aberrations, having no aperture obscuration, no chromatic aberration, and good environmental adaptability, making it essential in high-performance optical instruments. Freeform surfaces, with their rich degrees of freedom (DOFs) in mathematical representation, positively affect the image quality and sensitivity of optical systems. When applied correctly to off-axis TMA optical systems, they can achieve fast F-numbers, large fields of view (FOVs), and long focal lengths. There are dozens of configurations for off-axis TMA optical systems, and freeform surfaces can be combined in numerous ways within these systems. This paper first analyzes the sensitivity of off-axis TMA optical systems with different configurations, selects the configuration with the lowest sensitivity, and combines it with a low sensitivity freeform surface combination to achieve high-performance freeform off-axis TMA optical systems with low sensitivity.

Accurately modelling the propagation of radiant intensity in aqueous environments poses significant challenges for both academia and industry, due to complex interactions like absorption, scattering, and reflection. This study aims to improve the accuracy of optical modeling in water-based systems by comparing experimental data with numerical simulation techniques, addressing the need for more reliable simulation methods in multiple applications like treatment of water and environmental monitoring.Implementation has been done by analyzing how the method compares with the discrete ordinate method, radiometry, and actinometry. The study further quantifies the effect of the photoreactor quartz tube on measured intensity for multiple wavelengths. Losses in light intensity are estimated to be 10 ± 0.5% for FX-1 265 source. In contrast, the simulation in a water medium showed an increase of up to 64% in the light intensity delivered to the central part of the tube due to internal reflections and scattering. Model predictions from ray tracing successfully compared with the Discrete Ordinate Method (DOM) and experimental data (within ± 6%), ensuring the accurate design of complex systems for water disinfection. The data from simulations is seen to tackle challenges faced in complex radiation modeling and demonstrates that the method can be utilized as a useful tool for optimization and prediction.

Abstract UVC‐LEDs have drawn attention recently because of their benefits to sterilization, decontamination, etc. Since the internal quantum efficiency and light extraction efficiency (LEE) of UVC‐LEDs are low, their external quantum efficiency remains unsatisfied. To enhance the LEE, this study proposes an integration design with the features of substrate‐thickness optimization, substrate shaping, diffuse‐reflective coating, an index‐matching layer, and taper‐base optimization. In addition to optical modeling via ray tracing, thermal modeling is conducted to evaluate both the optical and thermal performances of each feature. The simulation results show that, by means of the combination of these features, the LEE of the chip can be raised from 18.5% to more than 40%, and the average temperature of the device can be lowered by 2.2°C via the design of the diffuse‐reflective coating.

This work presents a novel optimization strategy for maximum coupling results in optical coupler design. It was performed by the association between Evolutionary Strategy based metaheuristic with Fuzzy Logic and Shannon’s Entropy estimation for fitness bias support and control population diversity, respectively. This solution provided convergence for better results with fewer iterations and, consequently, reduced processing time. The results of some of the performance tests are presented, in which the best configuration obtained using the ES+Fuzzy with Shannon’s Entropy leads to an optical coupling around 86% by a device operating at a wavelength of 1.55μm to support the telecommunication services.

Abstract This article proposes a line scanning chromatic confocal sensor to solve the problem of limited chromatic confocal measurement due to the small measurement range and low measurement efficiency in the industrial inspection process. To obtain an extensive dispersion range, the advantages of a simple single-axis structure are combined with the advantages of a large luminous flux of a biaxial structure. Considering large-scale measurement, our sensor uses off-axis rays to limit the illumination path and imaging path to the same optical path structure. At the same time, the field of view is expanded, and a symmetrical structure is adopted to provide a compact optical path and improve space utilization. The simulation and physical system test results shows that the sensor scanning line length is 12.5 mm, and the axial measurement range in the 450 nm to 750 nm band is better than 20 mm. The axial resolution of the detector is ±1 µm combined with the subpixel centroid extraction data processing method, and the maximum allowable tilt angle for specular reflection samples is ±7°. The thicknesses of transparent standard flat glass and the wet collagen membrane are measured. The maximum average error is 1.3 µm, and the relative error is within 0.7%. The constructed sensor is of great significance for rapidly measuring the three-dimensional profile, flatness, and thickness in the fields of transparent biological samples, optics, micromechanics, and semiconductors.

Artificial vision systems pervade our daily lives as a foremost sensing apparatus in various digital technologies, from smartphones to autonomous cars and robotics. The broad range of applications for conventional vision systems requires facile adaptation under extreme and dynamic visual environments. However, these current needs have complicated individual visual components for high-quality image acquisition and processing, which indeed leads to a decline in efficiency in the overall system. Here, we review recent advancements in visual components for high-performance visual processing based on strategies of biological eyes that execute diverse imaging functionalities and sophisticated visual processes with simple and concise ocular structures. This review first covers the structures and functions of biological eyes (i.e., single-lens eyes and compound eyes), which contain micro-optic components and nanophotonic structures. After that, we focus on their inspirations in imaging optics/photonics, light-trapping and filtering components, and retinomorphic devices. We discuss the remaining challenges and notable biological structures waiting to be implemented.

This investigation provides the design and optical analysis of an innovative solar beam-down configuration, which can be a promising passive solution for indoor solar-based cooking, offering an eco-friendly and sustainable approach. The system uses a beam-down parabolic dish concentrator to concentrate the solar radiation onto a ground-mounted receiver module, which has a secondary optical module consisting of a secondary reflector-light pipe system. The receiver module is a well-insulated tank consisting of a receiver in contact with a primary heat transfer fluid. The thermal energy stored in the receiver module is transported via a secondary heat transfer fluid to and from the cooktop via a tube-in-tube arrangement, which induces a thermosyphon effect. A multi-variable optical analysis through an efficient ray tracing methodology has been adopted to identify optimal design values of optical components such as parabolic dish concentrators, secondary reflectors, and light pipe-receiver assemblies. The optimal optical design parameters and their corresponding ray trace analysis results are elaborated. It was found that the designed beam-down parabolic dish concentrator system provides an ideal thermal energy of 10.3 kWh per day at an average DNI of 650 W/m2. Further, this investigation provides a design for a beam-down parabolic dish concentrating system that may be used for efficient and sustainable solar energy solutions.

The Space High-cadence Observing Telescope (SHOT) is proposed to conduct a wide-field survey in one of the frequency bands between 1 and 3 THz with an aperture of 0.8 m. It will provide complete terahertz and far-infrared photometry with low-resolution spectroscopy throughout the sky, promoting the study of fast radio bursts, the formation and evolution of stars, and other scientific goals. The telescope will adopt a superconducting kinetic inductance detector to achieve a wide survey of terahertz imaging. This work designs the optical system of SHOT to obtain a large FOV of up to 1.5 deg and match the detector with the size of 60 mm × 60 mm and pixel pitch of 0.8 mm. The primary optical system adopts a Ritchey–Chrétien design. By adding a corrector lens to the optical system and optimization, the aberrations mainly caused by the optical elements in the detector system are reduced. The influence of each component assigned to different terahertz materials is analyzed. The results show that TPX is more suitable than the other two materials. The performance of the optimized optical system is close to its diffraction limit. It will have the characteristics of high image quality and compact layout. [ABSTRACT FROM AUTHOR]

Public awareness of preventing pathogenic microorganisms has significantly increased. Among numerous microbial prevention methods, the deep-ultraviolet (DUV) disinfection technology has received wide attention by using the nitride-based light-emitting diode (LED). However, the light extraction efficiency of DUV LEDs and the utilization rate of emitted DUV light are relatively low at the current stage. In this study, a light distribution design (referred to as the reflective system) was explored to enhance the utilization of emitted DUV from LEDs, leading to successful and efficient surface and air disinfection. Optical power measurements and microbial inactivation tests demonstrated an approximately 79% improvement in average radiation power density achieved by the reflective system when measured at a 5 cm distance from the irradiation surface. Moreover, a statistically significant enhancement in local surface disinfection was observed with low electric power consumption. The reflective system was integrated into an air purifier and underwent air disinfection testing, effectively disinfecting a 3 m3 space within ten minutes. Additionally, a fluorine resin film at the nanolevel was developed to protect the light module from oxidation, validated through a 1200 h accelerated aging test under humid conditions. This research offers valuable guidance for efficient and energy-saving DUV disinfection applications. [ABSTRACT FROM AUTHOR]

In this article we describe the implementation of Freeform Optics Raytracer with Manufacturable Imaging Design cApaBiLitiEs (FORMIDABLE): an optical design library capable of simulating optical systems by ray-tracing. Optical performance can be quantified and optimised using third-party optimisation algorithms. Compared to available commercial optical design software and similarly to fast accurate NURBS optimization (FANO), our code can simulate and optimise Non-uniform rational B-Spline (NURBS). It also implements generalized differential capabilities that allows faster convergence compared to state-of-the-art. The implementation of FORMIDABLE and its innovative capabilities are described and illustrated with a representative case-study. The source code is available to eligible third-parties under the ECSL licence. [ABSTRACT FROM AUTHOR]

Underwater spectral detection plays an important role in the study of the underwater environment, ecology, oceanography, and environmental monitoring. A kind of underwater spectral radiometer that can observe the distribution of underwater spectral radiation bidirectionally has been developed. The flat-field concave holographic grating is used as the only optical component, the optical design parameters are optimized, and the system is miniaturized. The mechanism of stray light generation in the spectrometer is studied, and a method of suppressing stray light is proposed and simulated. The level of stray light in the system is suppressed to the order of 10−4, the signal-to-noise ratio of the system is improved, and the ability to detect weak light is enhanced. The wavelength calibration experiment was completed, and the experimental results show that the wavelength resolution of the underwater spectral radiometer is better than 3 nm. Finally, the quantitative relationship between spectral irradiance and digital output is obtained through radiation in the calibration of the system. [ABSTRACT FROM AUTHOR]

Sequentially timed all-optical mapping photography is one of the main emerging ultra-fast detection technologies that can be widely applicable to ultra-fast detection at the picosecond level in fields such as materials and life sciences. We propose a new optical structure for an all-optical spatial mapping module that can control the optical field of two-dimensional imaging while improving spectral resolution and detector sensor utilization. The model of optical parameters based on geometrical optics theory for the given structure has been established, and the theoretical analysis of the inter-frame energy crosstalk caused by incident beam spot width, chromatic aberration, and main errors of the periscope array has been conducted. The optical design of the two-dimensional (2D) all-optical spatial mapping module was finally completed using ZEMAX OpticStudio 2018 software. The results show that our optical module can realize targets of 16 frames and 1.25 nm spectral resolution. [ABSTRACT FROM AUTHOR]

Optical systems have conventionally been evaluated by means of ray-tracing techniques, which can extract performance parameters such as aberration and spot size. However, current ray tracing methods in the field of optical design lack satisfactory methods for error analysis and improving its accuracy. Additionally, numerical calculations of large-scale, lengthy, and multi-scale ray tracing often result in inaccurate and even invalid outcomes due to round-off errors. In response to this challenge, we adopt the floating arithmetic theory to analyze the accumulative impact of round-off errors during the ray tracing process and develop a numerical error model for ray tracing. Using this model, we introduce compensation measures to achieve higher precision and then implemented a high-precision ray tracing algorithm. Finally, we conduct numerical experiments to validate our error model and high-precision algorithm, demonstrating their superior precision in comparison to the state-of-the-art authoritative optical design software, Zemax and CODE V. • Optical design demands higher precision in ray tracing algorithms. • The error model reveals the sources and constituents of errors in ray tracing. • Five measures are derived from the model to improve the precision of ray tracing. • Our approach excels beyond the state-of-the-art algorithms of Zemax and CODE V. [ABSTRACT FROM AUTHOR]

Self‐luminous projection technologies, such as Micro‐LED chips, compared with traditional projection methods, does not require complex lighting path. So it can significantly improve light utilization rate and reduce costs. However, technical challenges in Micro‐LED chip production make it difficult to improve the chip's resolution further. Some studies have shown that compared with the original image resolution of the spatial light modulator (SLM), the projection images overlapped is an effective method to improve the resolution of the projector. In this paper, we study the working principle of the extended pixel resolution actuator and propose a self‐luminous projection resolution enhancement system based on Micro‐LED chip. It can improve the resolution of the projection images with the resolution of the Micro‐LED chip unchanged. The resolution enhancement system consists of a Micro‐LED chip, an extended pixel resolution actuator and a projection lens. According to the working principle of the extended pixel resolution actuator, the projection lens is an image‐space telecentric structure, in which modulation transfer function of projection imaging at Nyquist frequency 100 lp/mm is greater than 0.4. Finally, the tolerance analysis on the projection lens is completed. The results show that the projection lens has a high success rate in processing. This work is of great significance for improving the resolution of Micro‐LED self‐luminous projection images. [ABSTRACT FROM AUTHOR]

In this paper, we deduce and analyze the relationship between the back working distance and the design difficulty of the telecentric and reverse‐telephoto system in detail, and propose an innovative design idea for the LCoS projection system to solve this limitation. By employing optical path multiplexing in the imaging and illumination systems, the back working distance is reduced, leading to improved imaging performance and reduced system volume. Furthermore, a novel illumination system design method utilizing an independent eccentric microlens array is proposed for the new system configuration. This method achieves comparable illuminating quality with fewer elements and a smaller overall size compared to conventional approaches. [ABSTRACT FROM AUTHOR]

Wavelength selective switches (WSSs) are essential elements for wavelength division multiplexing (WDM) optical networks, as they offer cost-effective, high port-count and flexible spectral channel switching. This work proposes a new hybrid WSS architecture that leverages the beam shaping and steering features of uniform silicon nitride-based end-fire optical phased arrays (OPAs). By introducing beamforming to a WSS system, the spectral channels on the liquid crystal on silicon (LCoS) panel can be tailored and arranged properly, depending on the optical configuration, using the beam control capabilities of OPAs. Combining 3D-FDTD and ray tracing simulations, the study shows that, by reducing the input beam dimensions with proper sizing of the OPAs, the WSS design with a null-steering OPA layout and 4 × No switch size features increased spectral resolution. This extensive beamforming study on the steering-enabled layout reveals the acquirement of an even higher input channel number, matching the 8 × No WSS scheme, with flexible channel routing on the LCoS panel. Such implementation of beamsteerers can unlock an extra degree of freedom for the switching capabilities of hybrid WSS devices. The results show great promise for the introduction of OPAs in WSS systems and provide valuable insight for the design of future wireless communication links and WDM systems. [ABSTRACT FROM AUTHOR]

As the next generation of in-vehicle intelligent platforms, the augmented reality heads-up display (AR-HUD) has a huge information interaction capacity, can provide drivers with auxiliary driving information, avoid the distractions caused by the lower head during the driving process, and greatly improve driving safety. However, AR-HUD systems still face great challenges in the realization of multi-plane full-color display, and they cannot truly achieve the integration of virtual information and real road conditions. To overcome these problems, many new devices and materials have been applied to AR-HUDs, and many novel systems have been developed. This study first reviews some key metrics of HUDs, investigates the structures of various picture generation units (PGUs), and finally focuses on the development status of AR-HUDs, analyzes the advantages and disadvantages of existing technologies, and points out the future research directions for AR-HUDs. [ABSTRACT FROM AUTHOR]

Fingerprint recognition is a widely used biometric authentication method in LED-backlight smartphones. Due to the increasing demand for full-screen smartphones, under-display fingerprint recognition has become a popular trend. In this paper, we propose a design of an optical fingerprint recognition lens for under-display smartphones. The lens is composed of three plastic aspheric lenses, with an effective focal length (EFL) of 0.61 mm, a field of view (FOV) of 126°, and a total track length (TTL) of 2.54 mm. The image quality of the lens meets the target specifications, with MTF over 80% in the center FOV and over 70% in the 0.7 FOV, distortion less than 8% at an image height of 1.0 mm, and relative illumination (RI) greater than 25% at an image height of 1.0 mm. The lens also meets the current industry standards in terms of tolerance sensitivity and Monte Carlo analysis. [ABSTRACT FROM AUTHOR]

This article proposes a line scanning chromatic confocal sensor to solve the problem of limited chromatic confocal measurement due to the small measurement range and low measurement efficiency in the industrial inspection process. To obtain an extensive dispersion range, the advantages of a simple single-axis structure are combined with the advantages of a large luminous flux of a biaxial structure. Considering large-scale measurement, our sensor uses off-axis rays to limit the illumination path and imaging path to the same optical path structure. At the same time, the field of view is expanded, and a symmetrical structure is adopted to provide a compact optical path and improve space utilization. The simulation and physical system test results shows that the sensor scanning line length is 12.5 mm, and the axial measurement range in the 450 nm to 750 nm band is better than 20 mm. The axial resolution of the detector is ±1 µm combined with the subpixel centroid extraction data processing method, and the maximum allowable tilt angle for specular reflection samples is ±7°. The thicknesses of transparent standard flat glass and the wet collagen membrane are measured. The maximum average error is 1.3 µm, and the relative error is within 0.7%. The constructed sensor is of great significance for rapidly measuring the three-dimensional profile, flatness, and thickness in the fields of transparent biological samples, optics, micromechanics, and semiconductors. [ABSTRACT FROM AUTHOR]

The near-eye display (NED) systems, designed to project content into the human eye, are pivotal in the realms of augmented reality (AR) and virtual reality (VR), offering users immersive experiences. A small volume is the key for a fashionable, easy-to-wear, comfortable NED system for industrial and consumer use. Freeform surfaces can significantly reduce the system volume and weight while improving the system specifications. However, great challenges still exist in further reducing the volume of near-eye display systems as there is also a limit when using only freeform optics. This paper introduces a novel method for designing compact freeform NED systems through a powerful optical–digital joint design. The method integrates a geometrical freeform optical design with deep learning of an image compensation neural network, addressing off-axis nonsymmetric structures with complex freeform surfaces. A design example is presented to demonstrate the effectiveness of the proposed method. Specifically, the volume of a freeform NED system is reduced by approximately 63% compared to the system designed by the traditional method, while still maintaining high-quality display performance. The proposed method opens a new pathway for the design of a next-generation ultra-compact NED system.

In order to meet the demand for accurate identification of distant targets by improving the resolution of multi-scale imaging systems, from primary lenses focus, a design scheme of a multi-scale long-focal imaging system based on the Tessar primary lenses is proposed in this paper. Two constraints that need to be added to the primary lenses for meeting the linear arrangement of secondary lenses are analyzed. In response to the problem of the imaging quali-ty degradation of the system as the off-axis angle of the secondary lenses array increases, synergy optimization is applied to the secondary lenses in adjacent areas. Additionally, free-form surface types are used to correct aberrations in the off-axis position optimization of the secondary lenses. The MTF curves of different field-of-view areas are consistent, showing that the system achieves ideal imaging quality across the full field of view. The spatial resolution of the multi-scale imaging system designed using the Tessar primary lenses structure is 14 μrad. Compared to multi-scale systems based on concentric spherical lenses, it is significantly higher.

Commissioned in 2017 by the Italian Space Agency (ASI), the Sardinia Deep Space Antenna (SDSA) is currently able to operate in the X-band, supporting deep space and near Earth telemetry missions and scientific experiments. While sharing its infrastructure with the Sardinia Radio Telescope (SRT), the SDSA boasts its own dedicated control center and specific equipment. This paper outlines a new optical design and the radio frequency upgrades to enhance the SDSA’s capabilities for current and future tracking of deep space and near Earth missions. The proposed design aims to establish the SDSA as a state-of-the-art antenna in the field of space activities by capitalizing on its exceptional versatility. This includes its ability to accommodate new equipment and leverage the inherent characteristics of the SRT antenna, such as its active surface and frequency agility. A collaborative effort with ESA has resulted in a newly designed optical configuration enabling reception and transmission in the X, K, and Ka frequency bands. Specifically, the X and K frequency bands are allocated to near Earth radio communication (within a 2 million kilometer range). Additionally, the X- and Ka- bands configurations are designed for deep space operations, including the well-known triple-link technique for radio science missions beyond 2 million kilometers. To characterize the performance of the upgraded antenna, we present the electromagnetic simulations of the new optical design. We analyze the antenna radiation pattern across various downlink and uplink frequency bands and evaluate key parameters like gain-to-noise system temperature ( $G/T_{sys}$ ) and effective isotropic radiated power (EIRP). The simulations were conducted using the dedicated commercial software GRASP and CHAMP 3D by TICRA. The results of this study provide valuable information on the capability of the upgraded SDSA to enable a wide range of space communication and space science applications, making the SRT in its SDSA configuration one of the most equipped and technologically advanced ground segment facility.

In this paper, a novel design of the illumination optical system for a laser target simulator is investigated to determine the optimal relationship between the uniformity of the illumination system and the energy utilization in a laser target simulator. First, the optimal size of the fly-eye lens unit is calculated from the parameters of the DMD to improve the energy utilization of the system; second, the optimal parameters of the TIR prism group are calculated based on the size of the illuminating beam and the optimal deflection angle of the TIR prism group is analyzed, which results in the compact overall structure of the system and improves the uniformity under the premise of ensuring that there is not much change in the energy utilization; and finally, the optimal design of the illumination optics system for laser target simulators is investigated based on the Finally, based on the Scheimpflug principle, the uniformity of the illumination system is further improved by solving the deformation of the image plane caused by the insertion of the TIR prism group. The results show that the simulation results of the system's uniformity reach 96.93%, the simulation results of the energy utilization are 60.05%, and the structure is compact, and the system designed by this method can provide a good design solution to obtain high energy utilization and uniformity.

We propose a reverse design technique for WOLEDs using an artificial neural network. The inverse neural network is trained by combining forward and inverse neural networks and predicts the thin‐film structure from the out‐coupling spectrum. The predicted structures have a low error rate of less than 9 percent, demonstrating effectiveness of the inverse neural network. [ABSTRACT FROM AUTHOR]

Dispelix has developed an advanced design toolset capable of optimizing the image quality and performance of augmented reality near‐eye and head‐up displays based on diffractive waveguide technology. The design toolset can solve the unique challenge prevalent in diffractive optical waveguide systems by accurately simulating the operation of nano‐scale diffractive surface relief gratings in an optical waveguide with macro‐scale dimensions. This paper presents simulation results of key performance metrics and compares them to measurement data from samples manufactured by state‐of‐the‐art nanofabrication tools. [ABSTRACT FROM AUTHOR]

Light field cameras are unsuitable for further acquisition of high-quality images due to their small depth of field, insufficient spatial resolution, and poor imaging quality. To address these issues, we proposed a novel four-focal-square microlens and light field system. A square aspheric microlens array with four orthogonal focal lengths was designed, in which the aperture of a single lens was 100 μm. The square arrangement improves pixel utilization, the four focal lengths increase the depth of field, and the aspheric improves image quality. The simulations demonstrate pixel utilization rates exceeding 90%, depth-of-field ranges 6.57 times that of a single focal length, and image quality is significantly improved. We have provided a potential solution for improving the depth of field and image quality of the light field imaging system.

Augmented reality overlays computer-generated virtual information onto real-world scenes, enhancing user interaction and perception. However, traditional augmented reality optical systems are usually large, bulky, and have limited optical performance. In this paper, we propose a novel compact monochrome reflective dielectric metalens visor with see-through properties, engineered using a periodic structure of spin-dependent supercells. The supercell, which is composed of staggered twin nanofins, provides spin-dependent destructive or constructive interference with different circularly polarized incidences. The design combines the principles of interference with the Pancharatnam–Berry phase to enhance reflection at a working wavelength of 650 nm while maintaining good transmission. Right circularly polarized light incident from the substrate side causes destructive interference, enabling the supercell to work in reflection mode, while left circularly polarized light causes constructive interference, enabling the supercell to work in transmission mode. Furthermore, the supercell-constructed metalens can achieve near-diffraction-limited reflective focusing and a broad diagonal field of view of approximately 96°. In addition, compared to transmissive metalens visors, the reflective design eliminates the need for a beam splitter, significantly reducing the size and weight of the system. Our work could facilitate the development of compact and lightweight imaging systems and provide valuable insights for augmented reality near-eye display applications.

Recently developed sixth-order wave aberration expressions of soft X-rays and a vacuum ultraviolet optical system are first extended to plane-symmetric refractive optical systems, and then, applying the transformation relations between plane-symmetric and paraxial refractive optical system, the sixth-order intrinsic and extrinsic wave aberration coefficient expressions of a paraxial refractive optical system are derived. In addition, the corresponding fifth-order aberration expressions are also obtained. Finally, the resultant aberration expressions are applied to calculate the aberration on the image plane of one design example of a paraxial refractive optical system with a large aperture, and these calculation results are compared with ones obtained by ray-tracing software Zemax to prove that they have satisfactory calculation accuracy.