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Free-form surfaces have good aberration correction capability and balance capability for nonrotationally symmetric imaging systems. In this study, we analyzed the quantitative relationship between X–Y polynomial combination and aberration for the efficient design of X–Y free-form optical systems. The purpose of this study was to provide an exhaustive design method for off-axis triple inverse optical systems with X–Y free-form surfaces. Finally, we designed a free-form off-axis optical system with a large field of view (FOV) and low distortion based on the off-axis triple inverse optical system without an intermediate image plane. The primary mirror (PM) of the system adopted an X–Y polynomial free-form surface to correct the aberration of different FOVs of the system and improve the image width and quality. The optical system had a focal length of 1000 mm, an F-value of 9.5, an FOV angle of 23° × 1°, a maximum distortion grid in the FOV less than or equal to −0.05%, and a full-field average wave aberration better than 0.055 λ (λ/18.2, λ = 632.8 nm). The analysis of the design results showed that the system had high-quality imaging and a compact structure. This design method can provide a technical reference for the study of such free-form off-axis systems.

As a high-quality thick glass separation method, multifocus technology has proven its superiority. For a certain thickness of glass, there must be an optimal multifocus distance. But, the positions of the foci cannot be adjusted flexibly in current multifocus schemes without changing the energy proportions; the influence of thermal stress distribution on the quality of thick glass separation has not been systematically studied. An adjustable multifocus laser scheme has been proposed in this paper and proved by optical design, ray tracing, and experiment. First, finite element simulations have been performed to analyze the thermal stress distribution inside 20 mm glass. The simulation results show that thermal tensile stress exceeds the fracture threshold only at the upper and lower sides of the glass but not in the middle; the maximum thermal tensile stress reduces inside the glass when the symmetrical focal distance increases. Then, a series of separation experiments of 20, 22, and 25 mm thick soda lime glass have been carried out, which have adjusted foci positions to control the thermal stress distribution. The experimental results show that the deviation length decreases with an increase of the foci distances, and the optimal symmetrical foci distances reduce as the glass thickness increases. [ABSTRACT FROM AUTHOR]

MEMS-based LIDAR has the advantages of fast-scanning, simple structure, small volume, and light weight, which make it a hot topic for 3D imaging. In order to overcome the limited scanning angle of the current MEMS mirrors, a large angle MEMS-based optical scanning system was designed using telephoto structure. In this design an f-θ lens group is used for flat field scanning and a symmetrical cemented lens group is used for angle expansion. The principle of this system is discussed in detail and an optical design is implemented by ZEMAX software. The designed system realized a scanning angle as large as 57° and is in excellent linear relation with the tilt angle of the MEMS mirror. At the target distance of 100 m, the maximum RMS radius of the light spot is only 7 cm. This optical scanning system shows a significant application potentiality for 3D imaging LIDAR. [ABSTRACT FROM AUTHOR]

This article presents an extra-large (25 × 50 mm2) flexible printed circuit board (FPCB) mirror to cover both the emitting and receiving lenses of a single-point LiDAR to form a biaxial scanning LiDAR with a compact structure and long measurement distance and low cost. The FPCB mirror is fabricated using the low cost and commercially available FPCB fabrication process. In addition, a widely available single–point LiDAR is used as the measurement unit. This article's novelty lies in the following two points: 1) integrating a large aperture scanning mirror and a single-point LiDAR (low cost and widely available) to construct a biaxial scanning LiDAR; 2) proposed a large aperture FPCB mirror using long existing FPCB process such as to achieve low cost. The scanning LiDAR is designed for applications in factory for robots and automated guided vehicles; navigation. The FPCB mirror consists of a mirror plate, two permanent magnets, and a FPCB structure, which includes two torsion beams, a middle seat, and a Flame retardant 4 (FR4) stiffener frame. Four-layer copper coils are embedded in the FPCB structure, which is fabricated using the low cost commercially available FPCB fabrication process. The mirror plate is diced from a thin silicon mirror plate with gold coating and then attached on top of the middle seat of the FPCB structure. With such large aperture FPCB scanning mirror, and a long measurement distance single-point LiDAR, a compact biaxial scanning LiDAR is constructed. The scanning LiDAR based on the FPCB mirror is constructed and tested. Achieved performances are: the field of view of 60°, measurement distance of 50 m, refresh rate of 20 Hz, 500 points for each scanning frame. [ABSTRACT FROM AUTHOR]

• Ray tracing analysis was conducted to reduce stray light of OROCHI onboard the MMX. • OROCHI's optical system is simulated and its CCD reflectance was measured. • Our techniques are incorporated into the preliminary design of OROCHI. The Martian Moons eXploration (MMX) spacecraft is equipped with two cameras, i.e., the TElescopic Nadir imager for GeOmOrphology (TENGOO) and the Optical Radiometer composed Of CHromatic Imagers (OROCHI), for the scientific observation of the Martian moon Phobos. OROCHI is a wide-angle multiband camera system comprising seven cameras with different bandpass filters and one monochromatic camera in the visible and near-infrared range. Thus, OROCHI can simultaneously obtain multiband images. Previous space observations have revealed that the reflection spectra of Phobos exhibit regional differences, including a red unit and a blue unit with weak redness. Moreover, Phobos shows an absorption band near 650 nm, attributed to the red unit of Phobos. Global observations using OROCHI require the determination of such regional variations with high precision; therefore, we must reduce noise in the optical system design. In this study, to meet this requirement, we focus on stray light reduction. Stray light is a source of noise generated by reflections at surfaces of optical components (e.g., sensors, filters, lenses, and lens barrels). We design simulation models of the OROCHI optical system, measure the reflectance of its charge-coupled device (CCD) image sensor, and conduct stray light analysis via ray tracing. We estimate the ratio of the stray light intensity to the target signal intensity by deriving both the reflected (constituting stray light) and unreflected rays. We show that placing the filter away from the sensor and reducing the reflectances of the filter and lenses effectively reduce stray light. Such approaches are incorporated into the preliminary design of OROCHI. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She 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 large numerical aperture and high resolution mobile phone lens using the plastic asphere lenses E48R and LEXANH is demanded with the development of mobile phone market. A kind of large numerical aperture and high resolution mobile phone lens was designed by using Code-v optical design software. The mobile phone lens is constituted by five plastic asphere lenses, an infrared cut filter, and a sensor cover glass. The first and fourth lenses are positive lenses. The second, third, and fifth lenses are negative lenses. Design results show that when the space frequency is 350lp/mm, the modulation transfer function ( MTF) of all field of view are more than 0.2, and the MTF of 0.7 field of view are more than 0.34. The field curves are less than 0.02mm, and the distortion are less than 2.55%. It provides a reference value for similar systems. [ABSTRACT FROM AUTHOR]

As implantable optical systems recently enabled new approaches to study the brain with optical radiations, tapered optical fibers emerged as promising implantable waveguides to deliver and collect light from sub-cortical structures of the mouse brain.They rely on a specific feature of multimodal fiber optics: as the waveguide narrows, the number of guided modes decreases and the radiation can gradually couple with the environment. This happens along a taper segment whose length can be tailored to match with the depth of functional structures of the mouse brain, and can extend for a few millimeters. This anatomical requirement results in optical systems which have an active area that is very long compared to the wavelength of the light they guide and their behavior is typically estimated by ray tracing simulations, because finite element methods are too computationally demanding. Here we present a computational technique that exploits the beam-envelope method and the cylindrical symmetry of the fibers to provide an efficient and exact calculation of the electric field along the fibers, which may enable the design of neural interfaces optimized to meet different goals. [ABSTRACT FROM AUTHOR]

During endoscopic surgery, the operation accuracy can be improved if the endoscope system provides 3D information. In this paper, an adaptor lens is presented for a commercial 2D endoscope to generate stereoscopic images. The function of the adaptor lens is verified in this study, and we prove the adaptor lens can be compatible with an arbitrary rigid 2D endoscope system even if its original imaging lens specifications are unknown. The prototype adaptor lens kit, which was utilized to verify the basic idea, includes two commercial plastic lens modules. Furthermore, an optimized design of the adaptor lens system is also presented. The optical features of the optimized adaptor lens kit was analyzed via the ray-tracing software Zemax. The field of view (FOV) of the optimized adaptor lens system is 70°, and the dispersion of the optimized adaptor lens is small enough to be neglected. [ABSTRACT FROM AUTHOR]

The Laser Guide Star Facility (LGSF), as the most important part of the adaptive optics system of the large ground-based telescope, is aimed to generate multiple laser guide stars at the sodium layer. Laser Launch Telescope is employed to implement this requirement by projecting the Gauss beam to the sodium layer with a small beam size in LGSF system. As the diffraction and interference effects of laser’s long-distance transmission, the conventional optical design based on the geometrical optics mechanism cannot achieve the expected laser propagation. In this paper, we propose a method to design optical system for laser launch telescope based on the physical optics theorem to generate an acceptable light spot at the sodium layer in the atmosphere. Besides, a tolerance analysis method based on physical optics propagation is also demonstrated to be necessitated to optimize the system’s instrumentation performance. The numerical results show that the optical design considering physical optics propagation is highly rewarding and even necessitated in many occasions, especially for laser beam propagation systems.

Macro vivo fluorescence imaging is becoming more and more important in the medical field. It is also necessary to design the optical design system for the visible light of the NIR-II detector. This paper discusses the design method of the wide spectrum achromatic optical system from visible light to NIR-II. Based on ZEMAX, a wide spectrum zoom system is designed to freely observe experimental targets in the fields of view of 3.1–18.6°. The four components layout was adopted by the wide spectrum zoom system, which is suitable for 8.2 mm (1/2 inch) CCD, with an f-number of 5.0~6.0, zoom range of 25 mm~150 mm, working spectral band of 400 nm~1700 nm, full field MTF ≥ 0.3 at the spatial frequency of 100 lp/mm, and the maximum distortion of ≤±3%. All optical elements adopt the standard spherical, which can correct all kinds of aberrations well and meet each part’s basic processing requirements.

Commercial off-the-shelf optics enable economic and rapid solutions in the photonics industry and academia. However, the design of optical systems with off-the-shelf optics is a time-consuming task for experienced optical designers and hopeless for novice designers. In this paper, we propose an automatic optical design tool to generate optical systems using only off-the-shelf optical components without human assistance. Our solution is based on an evolution strategy (ES) that performs a discrete combinatorial optimization following optical design-based methodologies that satisfy user-defined specifications. Unlike the conventional methods, the algorithm decreases the design process time and provides optical designers with several optical solutions from where to choose and adapt for targeted applications. In this work, the ES is described and tested with front stop optical configurations. We demonstrate the broad solution domain of the algorithm through the generation of optical systems with F-numbers within a range F/1 to F/90 and field of views up to 300 mm at the image plane. To analyze the solution domain and the characteristics of the solution, we used the design specifications of 29 commercially available scan lenses and compared the performance of different ES parameters. The compatibility of our algorithm with (standard) commercially available optical design software unlocks automatic design tools for off-the-shelf optical systems.

The ability to detect and recognize the low-contrast and distance targets in a complex environment is of great importance for many applications. However, one or two single spectral channel imaging cannot obtain adequate information. This study reports the design and construction of a common-aperture multispectral polarization imaging system, which can simultaneously obtain visible, short-wave infrared and mid-wave infrared wavebands. Such a system enables the acquirement of spatial, polarization and multispectral information of distance targets simultaneously. The experimental set-up is built to verify the basic principle of the device. The device is used to image optical resolution targets and the car at different times and distances in several complex backgrounds. The generated images are fused by polarization using image processing. The results indicate that the system performs well for imaging low-contrast objects in each waveband. [ABSTRACT FROM AUTHOR]

In fields such as biology, archeology, and industry, underwater photogrammetry can be achieved using consumer-grade equipment. However, camera operations underwater differ considerably from those on land because underwater photogrammetry involves different optical phenomena. On the basis of the requirements and specifications of the marine vessel Polaris, we developed a novel underwater camera with prime and zoom lenses and a high resolving power. The camera can be used in the spectrum in shallow water and the blue–green spectrum in deep water. In the past, ordinary cameras would be placed in waterproof airtight boxes for underwater photography. These cameras were not optimized to the underwater spectrum and environment, resulting in no breakthroughs in resolving power. Furthermore, the use of the blue spectrum greatly increases during underwater and particularly deep-water surveying. Chromatic aberration and focus-point displacement generated by the shift from the shallow-water spectrum to the blue–green spectrum in deep water makes universal underwater photography even more difficult. Our proposed optical design aimed to overcome such challenges for the development of a high-resolution underwater surveying camera. We designed a prime lens and a zoom lens. We adopted a waterproof dome window on the outer surface as the basic structure and optimized it in accordance with the conditions of different water depths and spectra to obtain distortion within ±2% and high-resolution underwater imaging quality. For the zoom lens design, we employed a genetic algorithm in Zemax to attenuate chromatic aberration as a kind of extended optimization. This novel optical design that can be used in all waters is expected to greatly reduce the volume and weight of conventional underwater cameras by more than 50% and 60%, respectively, and increase their resolving power by 30–40%. [ABSTRACT FROM AUTHOR]

Discrete frequency infrared chemical imaging is transforming the practice of microspectroscopy by enabling a diversity of instrumentation and new measurement capabilities. While a variety of hardware implementations have been realized, design considerations that are unique to infrared (IR) microscopes have not yet been compiled in literature. Here, we describe the evolution of IR microscopes, provide rationales for design choices, and catalog some major considerations for each of the optical components in an imaging system. We analyze design choices that use these components to optimize performance, under their particular constraints, while providing illustrative examples. We then summarize a framework to assess the factors that determine an instrument's performance mathematically. Finally, we provide a validation approach by enumerating performance metrics that can be used to evaluate the capabilities of imaging systems or suitability for specific intended applications. Together, the presented concepts and examples should aid in understanding available instrument configurations, while guiding innovations in design of the next generation of IR chemical imaging spectrometers. Graphical Abstract [ABSTRACT FROM AUTHOR]

The engineering of light confinement is a topic with a long history in optics and with significant implications for the control of light‐matter interaction. In inhomogeneous and disordered media, however, multiple scattering prevents the application of conventional approaches for the design of light fields with desired properties. This is because any local change to such a medium typically affects these fields in a non‐local and complicated fashion. Here, we present a theoretical methodology for tailoring an inhomogeneous 1D Hermitian dielectric index distribution that allows us to control the intensity profile of an incoming light field purely locally, that is, with little or no influence on the field profile outside of a designated region of interest. Strongly increasing or decreasing the light's intensity at arbitrary positions inside the medium thereby becomes possible without, in fact, changing the external reflectance or transmittance. These local modifications of the medium can thus be made undetectable to far field measurements. We apply this approach to locally control the confinement of light inside 1D materials with inhomogeneous continuous refractive index profiles and extend it to multilayer films as well as to chains of coupled micro‐resonators. [ABSTRACT FROM AUTHOR]

Deep reinforcement learning (DRL) enables autonomic optical networking by allowing the network control and management systems to self-learn successful networking policies from operational experiences. This paper proposes a transfer learning approach for effective and scalable DRL in optical networks. We first present a modular DRL agent design to facilitate retrieving and transferring relevant knowledge between tasks requiring different dimensions of network state data. In particular, we partition network state data into common states, which contain generic information critical to multiple tasks (e.g., the spectrum utilization on fiber links), and task-specific states that are only used by a specific task (e.g., the utilization of virtual network functions). Separate neural network blocks are employed to process different state data. Based on the modular agent design, a multi-task learning (MTL) aided knowledge transferring scheme is proposed. The proposed scheme trains an MTL agent that can master multiple tasks simultaneously and thus enables to learn and transfer better-generalized knowledge across tasks. We perform case studies on the proposed transfer DRL approach considering two scenarios, namely, knowledge transferring between routing, modulation and spectrum assignment (RMSA) tasks for different networks and knowledge transferring from RMSA tasks to anycast service provisioning tasks. The DRL designs for RMSA and anycast service provisioning, including the state, action, and reward formulations and the training mechanisms, are also elaborated. Performance evaluations under both scenarios show that the proposed approach can effectively expedite the training processes of the target tasks and improve the ultimate service throughput. [ABSTRACT FROM AUTHOR]

• MicroMED is the first OPC developed to monitor airborne dust on Mars. • MicroMED is characterized by low mass, size, and power consumption. • The optical design is simplified by using an optical fibre coupled to a laser source. • The optical system is designed to detect dust particles with diameters ≥ 0.4 µm. Airborne dust monitoring is crucial to characterize the thermal structure and evolution of the Martian atmosphere and climate. For this purpose, the MicroMED instrument has been selected within the ExoMars program to be deployed on Mars. It is an optical particle counter that measures the dust amount and size distribution of airborne dust close to the Martian surface. MicroMED is characterized by low mass, size and power consumption and is suitable to be accommodated on both rovers and landers. In this paper, the MicroMED optical design is described along with the analysis performed to prove compliance with all requirements needed for its nominal performance. [ABSTRACT FROM AUTHOR]

This article describes the design of an optical system using multi-wavelength illumination and dispersion principle to achieve iris recognition imaging with a large depth of field in noncooperative environments. Through the use of optical design software, the iris acquisition imaging system was designed with the modulation transfer function (MTF) curve serving as the evaluation criteria for this system. It was found that at different object distances, the MTF value at a spatial frequency of 100 lp/mm is greater than 0.33, indicating that the iris acquisition imaging system has a significant depth of field. To further validate the performance of the system, we set up an actual optical platform based on the parameters designed by the optical design software for the iris acquisition imaging system and conducted iris image acquisition experiments at different object distances, obtaining iris images of three different individuals. We performed algorithm verification on the iris recognition of the three sets of iris images and found that the average interclass matching result was 0.44, while the average intraclass matching result was 0.30, demonstrating a high level of accuracy in iris recognition. This indicates that the iris images obtained by the system have a high resolution, thereby confirming the feasibility of depth extension using multi-wavelength illumination and lens chromatic aberration imaging principle. It is worth mentioning that this method is not only applicable to iris recognition but also holds reference value in other biometric recognition fields. [ABSTRACT FROM AUTHOR]

We present practical laboratory work for master's students in photonics. The laboratory session is based on the construction of a telescope, emulating the one used by Galileo Galilei and analyzing the effect of aberrations and other practical limitations on the quality of the image. Different situations and configurations are analyzed, and the recreation of historical observations is carried out to generate a debate on the limitations of real telescopes with the students. The impact on the learning procedure of the students is analyzed by means of the results they have obtained during several academic years. [ABSTRACT FROM AUTHOR]

The climate on Earth is affected by the Sun. It is thus necessary to determine the solar spectral irradiance (SSI) with high precision on the ground for the improved accuracy of climate models used for Earth. To achieve this purpose, a solar spectral irradiance monitor (VISM) with a wavelength ranging from 380 to 2400 nm is developed. In this work, the optical design and spectral calibration of the VISM are explored, with two optical paths designed to determine the SSI in the wide spectral region. One of them is the main optical path through which the sunlight is dispersed and imaged by a single Féry prism. A laser and a concave mirror are used in the other optical path to determine the rotated angle of the Féry prism, which is crucial to determining the spectral information. Furthermore, a new spectral calibration method is developed for VISM. According to this method, the dispersion equation of the prism is combined with the results of three characteristic wavelengths to determine the relationship between the dispersed wavelengths and the pixels in the detector for the whole spectrum. An apparatus is set up in the laboratory for spectral calibration. It is revealed that the uncertainty of spectral calibration is about 0.3 nm, which exceeds the design requirement. When the designed VISM works outdoor, the SSI can be determined readily. It is shown that the optical design and spectral calibration proposed in this study for VISM are correct. [ABSTRACT FROM AUTHOR]

Free-form surface has a wide range of applications in imaging and non-imaging optics, which can simplify the optical components, support structures required by the system and make the overall optical space more compact, but because of the large freedom of design, the design difficulty is greatly increased, how to meet the design requirements while improving efficiency, is the focus and difficulty of current research. Therefore, this paper proposed an improved optimization method for designing of free-form lens for light-emitting diode (LED) light distribution. Based on the lens matching curve obtained by weighted superposition, feedback optimization method was used to further improve the optimization possibility of lens. The weight factors of each surface are optimized by particle swarm optimization algorithm to minimize the evaluation function based on illuminance uniformity of the target surface. The illuminance uniformity on the target plane is optimized from 72.8% to 93.2% start form initial structure. The results show that the proposed algorithm has the advantages of high optimization efficiency and good optimization effect. • Using machine learning algorithm to optimize lens structure. • Using weighted superposition and feedback optimization algorithms to further optimize the initial structure of the lens. • Using API tools to achieve cross-software optimization. [ABSTRACT FROM AUTHOR]

The ITER Core Plasma Thomson Scattering (CPTS) diagnostic system is designed to measure the electron temperature and density with an accuracy of 10 % and 5 %, respectively, at the Tokamak plasma core with a spatial resolution of 66 mm. A 1064 nm laser is injected into the vacuum vessel during the plasma pulse, where the laser light is scattered by the plasma electrons due to Thomson Scattering. The scattered light is collected and analysed to determine the electron temperature and density. The CPTS diagnostic PDR design proposes a complete, detailed and robust preliminary design, compliant with the system requirements and nuclear regulations. [ABSTRACT FROM AUTHOR]

The article deals with a problem of calculating two reflecting surfaces that form a given irradiance distribution with a flat wavefront, provided that a point source of light is used. A notion of a weak solution for the said problem is formulated and the equivalence of this problem and the Monge–Kantorovich mass transfer is proven.

A problem of calculating a refractive surface that forms a required irradiance distribution in the far field in the case of a plane illuminating beam is considered. We show that this problem can be formulated as a mass transportation problem. The specific form of the cost function for this problem is obtained. It is shown that with a certain choice of coordinates, the cost function becomes quadratic. The resulting mass transportation problem also describes a problem of calculating a mirror, which can be considered as a special case of the problem of calculating a refractive surface.

Abstract For lighting applications demanding high brightness, a new type of LED-based light source has been developed, the high lumen density (HLD) source (luminance > 2·109 cd/m2). The performance can be improved further, among other things by optimizing the concentrator used as extraction optics. For this optimization, much insight is obtained by ray-tracing simulations. The efficiency can be improved by more than 20% if a high-index concentrator could be used. Furthermore, it is possible to optimize the shape of the concentrator. For a low-index (n ≈ 1.5) concentrator, the light leakage can be reduced, but the gain in useful light is only marginal. For a high-index (n ≈ 1.8) concentrator, the gain in useful light amounts to a few percent.

An anamorphic telescope has different magnifications in the tangential and sagittal directions, and it can be applied to atmospheric remote sensing satellites to effectively improve the spectral sampling rate. However, the initial structure of an anamorphic system is rare and its optimization requires extensive experience, which brings a challenge to the design of anamorphic telescopes. In this study, we propose a design method that is effective in obtaining the initial structure of an anamorphic system and discuss the conversion relationship between the Biconic surface and the XY polynomial surface. The XY polynomial provides design capabilities with an ultrawide field of view (FOV). With this insight, an initial anamorphic system with XY polynomial surfaces is constructed as a good starting point for further ultrawide FOV optimization. Consequently, an off-axis freeform anamorphic telescope with a focal length of 34 mm × 68 mm, and an ultrawide FOV of 110° × 0.24° is designed as an example. The telescope is a Gregorian structure with two concave mirrors as anamorphic elements, and the simulated design exhibits excellent performance. The method provided in this study facilitates the design of remote sensing instruments.

The echelle grating spectrometer, with a wide spectral range and high-resolution spectral analysis, is one of the best tools for fine spectral measurement. Nevertheless, it suffers from excessive residual aberrations and a large overall size. In this study, the design and implementation of a novel asymmetric Czerny–Turner ultra-wide spectral range achromatic echelle spectrometer are described. The echelle spectrometer has three channels, and it uses an off-axis parabolic mirror to obtain collimated light without aberrations. Three sets of gratings and dispersive prisms with different coatings are utilized as cross-dispersion elements to acquire two-dimensional images containing spectral information. Suitable detectors are selected according to the requirements of each channel, and three sets of coaxial focusing lenses are designed separately to minimize the aberration. The results of the simulation analysis by ZEMAX indicate that in the entire operating band (200–1100 nm), the root mean square radius of the dispersion spots is ≤ 2.2 μm, all of which are located within the limited range of the size of the detector, thus ensuring that the system’s spectral resolution reaches 0.02 nm at 200 nm, 0.04 nm at 650 nm, and 0.1 nm at 1100 nm.

An integrated direct-reading spectrometer scheme using seven concave gratings is proposed. At present, the optical design simulation has been completed, and the subsequent physical design may be carried out according to the simulation results. Ray-tracing software (Zemax) is used to divide the spectrum on the grating into seven bands, and an area array detector is used to receive the spectral signals simultaneously, which reduces the volume of the spectrometer and improves the spectral consistency. Using this method, a spectrometer covering 230–440 nm is designed, and the spectral resolution of the center wavelength corresponding to the seven grating windows of 230–260 nm, 260–290 nm, 290–320 nm, 320–350 nm, 350–380 nm, 380–410 nm, and 410–440 nm can reach 0.0974 nm, 0.0652 nm, 0.0361 nm, 0.0157 nm, 0.0838 nm, 0.0872 nm, and 0.1471 nm.

A low-cost medium-power carbon dioxide (CO2) laser system is designed, constructed, and characterized to produce coherent, monochromatic laser radiation in the infrared region. The laser cavity is simulated and designed by using ZEMAX optic studio. A switch-mode high-tension pump source is designed and constructed using a flyback transformer and simulated using NI Multisim to study the voltage behavior at different node points. A prototype cooling system/chiller is designed and built using thermo-electric coolers (TEC) to remove the excess heat produced during laser action. Various parameters, such as pumping mechanism, chiller stability, efficiency, output power, and current at different applied voltages, are studied. The chiller efficiency at different output powers of the laser is analyzed, which clearly shows that the chiller’s cooling rate is good enough to compensate for the heat generated by the laser system. The center wavelength of the carbon dioxide laser is 10.6 μm with an FWHM of 1.2 nm simulated in the ZEMAX optic studio. The output beam penetration through salt rock (NaCl), wood, and acrylic sheet (PMMA) at various output powers is analyzed to measure the penetration depth rate of the CO2 laser.

In this study, we propose a method of evaluating the spectral resolution of crossed-asymmetric Czerny-Turner spectrometers by comparing the impact of different slit functions on the optical transfer function, and different slit widths, through simulation and experiments. The results show that, the Gaussian function is suitable for narrower slit widths, such as 25 μm, and the rectangle function or convolution of slit-scattering function with rectangle function is suitable for wider slit widths, such as 50 μm, 150 μm, and 200 μm. The proposed method can provide guidance in the evaluation of spectral resolution in the preliminary optical design process of spectrometers.

An incoherent optical system with wavefront coding extends the depth of field (DOF) by employing a cubic phase plate (CPP). We designed a digital microscope with a CPP in the aperture stop and on the surface of the lens, which extended the DOF. In addition, we proposed a method in which the CPP can be shifted and assigned to the surface of the lens by adjusting the third-order coefficient of the xy polynomial surface, so that the CPP on the surface of the lens can replace a single CPP in the aperture stop, which collided with the optical elements and mechanism in some cases, to reduce the difficulty in assembling. The microscope with flexibility and without loss of the illumination level can considerably improve the efficiency of microscopic applications.

Planar optical device with continuous phase shifting (CPS) has raised widespread interest recently. Formed by subwavelength micro/nano structures, planar optics are able to control wavefront in multi aspects including phase and polarization. Most phase shifters for CPS devices are individual structures such as cylinders or cuboids. In this study, we specifically discuss grating based continuous phase shifting lenses comparing with aforementioned counterparts, in terms of differences of design mechanism and polarization responses. In addition we found that grating based metalens has outstanding potential in generating emerging artificial focus pattern. A grating based CPS lens with ‘U’ shaped focus was fabricated and characterized for prove of concept. Planar optics with artificial focus pattern has great potential for future applications including micro beam shaping and maskless nano lithography. [ABSTRACT FROM AUTHOR]

• A review of literature on optical design methodologies of linear Fresnel is given. • Designing for peak conditions is first considered. • Using multi-objective optimisation methods is covered in detail. • Analytical and finite-volume methods to determine optical performance are listed. • Novel linear Fresnel layouts are critiqued with a discussion of their cost. Linear Fresnel collector plants represent a promising line-focusing concentrating solar thermal technology that has not yet reached commercial maturity. This technology has many advantages, but its core disadvantage is the low optical performance of the primary collector field. The design of the primary is therefore of vital importance to the competitiveness of the technology. The large number of independent parameters in primary collector designs has led to many different optical design methodologies and optimisation studies. This review paper firstly details the different optical loss mechanisms and their relative importance to the performance of the primary. The different models used to quantify performance are then detailed. The subsequent sections categorise the collector primary design into three broad themes: designing for peak conditions (no blocking and shading for a vertical sun); design optimisation (from sensitivity studies to particle swarm and multi-objective optimisation studies); and novel linear Fresnel layouts. Novel layouts make use of additional degrees of freedom and non-imaging optics to create hybridised collector fields with enhanced optical efficiency. While this avenue shows much promise, the cost implications of the added complexity are typically not fully quantified. [ABSTRACT FROM AUTHOR]

The optical design of a seeker, operating in two bands of infrared (MWIR-LWIR), is performed. The dual-band design has been developed on Zemax OpticStudio. Considering the optical parameters of commercially available dual-band IR detectors, the design of the IR imaging seeker is completed for the operation within the wavelength range of 3–10 µm. The temperature dependence of the optical design is also examined for four different lens barrel materials, for the large temperature interval ranging from −40°C to 80°C. The defocusing effect caused by using different lens barrel is fixed by the passive-optical-athermalization technique. The field of view of the optical system is found to be 16°. The modulation transfer function (MTF) value of each field is higher than 0.50 when the spatial frequency takes a value of 20.8 lp/mm. The results are analyzed and discussed in terms of spot diagram, MTF. [ABSTRACT FROM AUTHOR]

Small form-factor sensors are widely used in minimally invasive intravascular diagnostic procedures. Manufacturing complexities associated with miniaturizing current fiber-optic probes, particularly for multi-parameter sensing, severely constrain their adoption outside of niche fields. It is especially challenging to rapidly prototype and iterate upon sensor designs to optimize performance for medical devices. In this work, a novel technique to construct a microscale extrinsic fiber-optic sensor with a confined air cavity and sub-micron geometric resolution is presented. The confined air cavity is enclosed between a 3 μm thick pressure-sensitive distal diaphragm and a proximal temperature-sensitive plano-convex microlens segment unresponsive to changes in external pressure. Simultaneous pressure and temperature measurements are possible through optical interrogation via phase-resolved low-coherence interferometry (LCI). Upon characterization in a simulated intravascular environment, we find these sensors capable of detecting pressure changes down to 0.11 mmHg (in the range of 760 to 1060 mmHg) and temperature changes of 0.036 °C (in the range 34 to 50 °C). By virtue of these sensitivity values suited to intravascular physiological monitoring, and the scope of design flexibility enabled by the precision-fabricated photoresist microstructure, it is envisaged that this technique will enable construction of a wide range of fiber-optic sensors for guiding minimally invasive medical procedures. [ABSTRACT FROM AUTHOR]

A single mode condition (SMC) for silica-titania rib waveguides on glass is the subject of this work. There are two mechanisms leading to the single mode propagation of a lightwave in rib waveguides. Considering waveguides whose rib width is greater than a thickness of a parent-slab waveguide, the one that would be created by extending the rib in the horizontal direction, the first mechanism is related to the leaking of HE01 and EH01 modes to slab waveguides on either side of the rib. The second mechanism is related to cut-off of those modes. Presented condition is expressed by two criterion functions. The first function, corresponding with the first mechanism, was introduced in our previous work describing the SMC for shallow rib waveguides. The second one, allowing to predict when the first order modes are cut-off is presented in this work. As a result, the complete SMC is formulated. It allows to predict a range of morphological parameters in which propagation is single mode, not only in shallow but also in deep rib waveguides. Moreover, considering the leaking of the HE01 mode, it is shown that the prediction is accurate by using coefficients of criterion functions obtained by the linear interpolation. [ABSTRACT FROM AUTHOR]

Massive open online courses (MOOCs) provide anyone with an Internet connection easy access to a wealth of learning and computer training opportunities. Optics and photonics devices are frequently used in numerous academic fields and industries. Therefore, a MOOC approach to optics education would be beneficial to many students, researchers, and professionals all over the world, as this would empower personal and professional development with global reach. As part of online education, students can learn professional computer modeling tools and use them for completing course assignments. In this paper, several optical design packages are reviewed and evaluated for their applicability to MOOC optics education in terms of availability, functionality, and wealth of training resources. An example of an optics MOOC case‐study is also presented. [ABSTRACT FROM AUTHOR]

Optical instrumentation with reliable performance is essential for the research of exoplanet atmosphere characteristics. However, due to long distances and weak signals, exoplanets are difficult to be imaged by traditional optical systems. To this end, a novel optical system based on transit spectroscopy is proposed in this paper. On the basis of the principle of the transit-spectroscopy method and the astronomical parameters of observed targets, the optional parameter ranges of a dedicated optical system are analyzed. The transit signal-to-noise ratio (SNR) is introduced for the determination of telescope aperture and throughput. Furthermore, an example of the optical system with a space telescope and spectrometer is proposed according to the above optical index, which is proven to meet the performance requirements. The optical system is required to cover the wavelength of 0.5–8 μm and the field of view (FOV) of 27.9 ″ within the diffraction limit. The collecting aperture should be greater than 2 m, and spectral resolutions of two spectrometer channels should approximately be 100 (2–4 μm) and 30 (4–8 μm). The point-spread function (PSF) of each channel at the minimal wavelength should cover 2 pixels. The telescope and dichroic system provide diffraction-limited input beams with the required aperture, FOV, and wavelength for the spectrometer slits. The simulation results of the optical system show that the spectral resolutions of the dual-channel spectrometer were 111–200 and 43–94. The image points of the spectrometer in each wavelength were smaller than the Airy spot within the slit FOV, and the full width at half-maximum (FWHM) of PSF at λ m i n provided 2 pixels of 18 μm sampling. The feasibility of the demonstrated optical parameters is proven by the design. [ABSTRACT FROM AUTHOR]

Low-altitude astronomical sites are generally considered as suboptimal for NIR (near-infrared: 0.9–3.6 microns) astronomical observations because of high and variable water vapour concentration. However with the availability of newer type of detectors and filter sets it might be possible to fully utilize such sites in this wavelength range. In context of this we discuss possible optical designs for a photometer that can be used on the 1 meter Carl Zeiss telescope at the VBO (Vainu Bappu Observatory), Kavalur. We have estimated the expected sky transmission variability for this site and achievable SNR (signal-to-noise ratio) using the designed instrument. [ABSTRACT FROM AUTHOR]

From optical point of view, an imaging application includes the sensor (CCD or CMOS) and the objective. The simplest objective consists of a cemented doublet. The paper proposes a design algorithm of the doublet and describes a software application based on this algorithm. The results provided by the original software are validated by means of a professional application in optical system analysis. [ABSTRACT FROM AUTHOR]

Thanks to their portability, connectivity, and their image performance – which is constantly improving – smartphone cameras (SPCs) have been people's loyal companions for quite a while now. In the past few years, multicamera systems have become well and truly established, alongside 3D acquisition systems such as time-of-flight (ToF) sensors. This article looks at the evolution and status of SPC imaging technology. After a brief assessment of the SPC market and supply chain, the camera system and optical image formation is described in more detail. Subsequently, the basic requirements and physical limitations of smartphone imaging are examined, and the optical design of state-of-the-art multicameras is reviewed alongside their optical technology and manufacturing process. The evolution of complementary metal oxide semiconductor (CMOS) image sensors and basic image processing is then briefly summarized. Advanced functions such as a zoom, shallow depth-of-field portrait mode, high dynamic range (HDR), and fast focusing are enabled by computational imaging. Optical image stabilization has greatly improved image performance, enabled as it is by built-in sensors such as a gyroscope and accelerometer. Finally, SPCs' connection interface with telescopes, microscopes, and other auxiliary optical systems is reviewed. [ABSTRACT FROM AUTHOR]

This paper proposes a high-accuracy distortion correction method for optical imaging distortion mapping and computational image predistortion. Due to the establishment of the predistortion is based on the distortion evaluation in the common optical design software CODE V, it can be used in the broad field of optical imaging system. Two distortion correction methods considering radial and tangential distortion rates which defined by optical design are introduced to perform distortion correction, and the forward and inverse image warping interpolation methods are adopted, separately. Simulations are conducted to verify the effectiveness in correcting complex distortion for freeform off-axis optical system. Furthermore, we implement a distortion correction experiment for an augmented reality head-mounted display that suffers from an asymmetric distortion with the maximum tangential distortion over 7%. For the first method, fast and high-accuracy image warping is achieved, and the RMS error of the approximation predistortion image is less than 1 pixel. Meanwhile, the RMS errors of the corrected imaging points are approximately 1.93 pixels vertically and 2.16 pixels horizontally when using a 5-megapixel camera. The second method considers the additional influence of the actual machining and assembly errors of the optical system, and the RMS errors of 0.89 pixels vertically and 0.85 pixels horizontally are achieved.

With the emergence of high-performance infrared detectors and the latest progress in grating manufacturing technology, high-resolution and high-sensitivity infrared spectrometers provide new methods for application to many fields, including astronomy and remote sensing detection. Spectral detection has attracted considerable attention due to its advantages of noncontact and stability. To obtain the detailed features of the missile’s tail flame spectrum, traditional plane reflection gratings are used as the main dispersive element; however, the instrument’s volume will increase with increasing resolution, which is not conducive to remote sensing detection from airborne platforms. Such spectrometers cannot meet high-resolution spectroscopy requirements. To address this problem, this paper proposes an immersion echelle spectrometer combined with a three-mirror astigmatism optical system. High resolution and compact size were achieved. In this paper, a small high-resolution infrared echelle spectrometer optical system was created by combining an off-axis three-mirror anti-astigmatism system, a Littrow structure, and a concave grating Wadsworth imaging device. The optical system operated in the 3.7–4.8 μm band; the echelle grating worked under quasi-Littrow conditions, while the concave grating was used for auxiliary dispersion to separate overlapping orders. The resolution of the optical system in the entire working band was 23,000–45,000. The optical plane size of the spectrometer was around 360 mm × 165 mm. The results show that the Mid-IR echelle spectrometer achieved high spectral resolution, better than 0.25 cm−1, meeting missile tail flame detection requirements. This device has the potential for real-time long-range target detection when warheads are destroyed. While this study focuses on the mid-wave infrared band, its approach can also be extended to other infrared bands.

The use of airborne-mapping technology plays a key role in the acquisition of large-scale basic geographic data information, especially in various important civil/military-mapping missions. However, most airborne-mapping cameras are limited by parameters, such as the flight altitude, working-environment temperature, and so on. To solve this problem, in this paper, we designed a panchromatic wide-spectrum optical system with a focusing function. Based on the catadioptric optical structure, the optical system approached a telecentric optical structure. Sharp images at different object distances could be acquired by micro-moving the focusing lens. At the same time, an optical passive compensation method was adopted to realize an athermalization design in the range of −40–60 °C. According to the design parameters of the optical system, we analyzed the influence of system focusing on mapping accuracy during the focusing process of the airborne-mapping camera. In the laboratory, the camera calibration and imaging experiments were performed at different focusing positions. The results show that the experimental data are consistent with the analysis results. Due to the limited experiment conditions, only a single flight experiment was performed. The results show that the airborne-mapping camera can achieve 1:5000 scale-imaging accuracy. Flight experiments for different flight altitudes are being planned, and the relevant experimental data will be released in the future. In conclusion, the airborne-mapping camera is expected to be applied in various high-precision scale-mapping fields.

We develop a ‘perfect’ design for PAM4 Segmented Mach-Zehnder Modulators (SEMZM), featuring a fully linear (uniform) optical DAC (oDAC) staircase (i.e., having equi-spaced PAM4 levels) and no intrinsic modulation loss (the qualifier ‘perfect’ pertains to ideal conditions, barring optical excess losses and other impairments). This is achieved by leveraging our recently introduced maximin optimization strategy, enabling to locate the hitherto unknown optimal operating point in the serial oDAC parameters space, gaining ~7 dB relative to conventional PAM4 designs (typically based on a pair of segment electrodes in 2:1 lengths ratio and using 3 dB modulation backoff in order to compensate for degradation in oDAC linearity). The same photonic design may be reused to generate DAC-free coherent PAM4 (bipolar symmetric field-domain equi-spaced max-full-scale constellations), for efficient I/Q tributaries of 16QAM. [ABSTRACT FROM AUTHOR]