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Freeform aplanatic reflective imaging systems with several stigmatic pairs

APPLIED OPTICS 2025年第3期64卷 721-727页

作者： Gonzalez-acuna, Rafael G. Apice Tres Punta Lara 119 Santa Catarina 66365 Mexico

This manuscript introduces a method to design a freeform reflective optical system with the particularity of being aplanatic and having several stigmatic pairs. To achieve this goal the mathematical expressions in [Appl. Opt. 63, 8068 (2024);Appl. Opt. 62,5260 (2023)] are merged into a single set of expressions that leads to a system of differential equations that can be solved. The paper shows an illustrative example that explains how the method works. The resulting design is as expected by the theory proposed. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： Chromatic aberration Imaging systems modulation transfer function Nodal aberration theory Optical design software Optical systems

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Method to derive nonredundant point arrays with high cut-off frequency and compact point array autocorrelations for sparse aperture imaging systems

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OPTICAL ENGINEERING 2025年第2期64卷

作者： Liu, Tai Zhao, Yang Li, Jiabiao Zhang, Chunyue Xu, Feiyang Wu, Qingwen Xu, Zhenbang Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys Changchun Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Chinese Acad Sci Key Lab On Orbit Mfg & Integrat Space Opt Syst Changchun Peoples R China

In sparse aperture imaging systems (SAISs), point arrays (PAs) determine the center coordinates of sub-apertures and, in turn, influence the modulation transfer function (MTF) of the SAISs, which can be used to assess the contrast resolution of imaging systems. We propose a method to derive PAs with good performance based on a nonredundant points selection method and objective functions. The nonredundant point selection method is defined to obtain nonredundant PAs while reducing computational requirements. Objective functions are then proposed to ensure the performance of resulting point array autocorrelations. The proposed method is evaluated in a triangular grid using the adaptive simulated annealing algorithm, considering both full degrees of freedom and threefold symmetry. Several new PAs with good performance have been found, some of which outperform threefold-symmetry arrays, which are typically considered optimal. Experiments are then constructed to evaluate the performance of the MTF of SAIS based on obtained PAs, and the results confirm the effectiveness of the proposed method.

关键词： sparse aperture imaging systems point array nonredundant modulation transfer function

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Single-shot 2D detector point-spread function analysis employing a circular aperture and a back-projection approach

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OPTICS EXPRESS 2025年第4期33卷 7409-7433页

作者： Forster, Lennart Dierolf, Martin Achterhold, Klaus Pfeiffer, Franz Guenther, Benedikt Tech Univ Munich Chair Biomed Phys TUM Sch Nat Sci Dept Phys D-85748 Garching Germany Tech Univ Munich Munich Inst Biomed Engn D-85748 Garching Germany Tech Univ Munich TUM Sch Med Dept Diagnost & Intervent Radiol Klinikum rechts Isar D-81675 Munich Germany Tech Univ Munich TUM Inst Adv Study D-85748 Garching Germany

Knowledge of a detection system's point-spread function (PSF) allows improving image resolution by deconvolving this PSF. The slanted-edge or Siemens-star approaches are commonly used to retrieve the PSF. The latter retrieves the PSF with a poor angular resolution and requires an intricate, sometimes expensive test pattern. The former provides the line-spread function only. Rotating this edge, the PSF could be retrieved in a tedious and time-consuming procedure. Other alternatives are line-pair resolution test charts or point-like light sources, e.g., tiny pinholes or fluorescent beads, which suffer from long acquisition times either due to the need for pattern rotation or very low flux. Here, a single-shot method is presented to retrieve the complete two-dimensional PSF by employing a circular aperture and a back-projection approach similar to computed tomography, which overcomes the issues mentioned above. Additionally, the accuracy of the PSF determination is improved by integrating a sub-pixel-resolution approach. Furthermore, simulations are employed to analyze the method's susceptibility to noise and to assess its intrinsic accuracy. Lastly, an X-ray detector assembly is characterized with this method to showcase the detailed insights into the system's aberrations that can be obtained. Since this technique is not restricted to the X-ray regime, it can be applied to characterize detector systems in other regions of the electromagnetic spectrum. This enables the method's widespread use in the imaging community. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Computed tomography Image resolution modulation transfer function Optical systems Phase retrieval Spatial resolution

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Accurate and noise robust crosstalk removal techniques for edge illumination phase-based x-ray imaging systems

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OPTICS EXPRESS 2025年第7期33卷 16187-16201页

作者： Mazzolani, Andrea Astolfo, Alberto Buchanan, Ian Savvidis, Savvas Didziokas, Marius Moazen, Mehran Fardin, Luca Munro, Peter R. T. Olivo, Alessandro UCL Dept Med Phys & Biomed Engn Malet PlGower St London WC1E 6BT England UCL Dept Mech Engn Roberts Engn BldgTorrington Pl London WC1E 7JE England

In x-ray phase contrast imaging (XPCI) using the edge illumination method (EI), crosstalk (XT) between adjacent pixels due to, e.g., light diffusion in the scintillator in indirect conversion detector systems is an issue that blurs images and reduces both image sharpness and quantitative accuracy. We provide a detailed mathematical description of this phenomenon and propose two independent methods to mitigate its negative effects. The effectiveness of these techniques is demonstrated through both simulated and experimental data, showcasing the improvements in image quality and quantitative accuracy. In particular, the experimental data include an intact mouse skull where soft tissue details of the brain are visualized and improved with the proposed deconvolution methods;to the best of our knowledge, details of the murine brain structure inside an intact skull had not been observed before with laboratory-based XPCI systems.

关键词： Image metrics Imaging systems modulation transfer function Phase contrast Phase retrieval X-ray imaging

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Writing and optical characteristics of anti-glare screens for educational applications

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JOURNAL OF THE SOCIETY FOR INFORMATION DISPLAY 2025年第3期33卷 159-167页

作者： Kurashige, Makio Kosaka, Yosuke Ishida, Kazutoshi Shibata, Takashi Dai Nippon Printing Co Ltd Tokyo Japan Tokai Univ Sch Informat Sci & Technol Hiratsuka Kanagawa Japan

As electronic displays have become to be used under ambient illumination environment, the situations have been increased which the screens are exposed to the various types of ambient light sources. Since the reflection of ambient light by the screen generally results in the lack of visibility of the displayed contents, anti-glare layer (AGL) on top of the screen has been applied to suppress unwanted reflection. Meanwhile, handheld digital devices have been actively adopted to enhance the quality of learning experiences. Although it was pointed out that the impact of glare may lead to shorter viewing distance or poor posture of the students, there was not enough information regarding the relation between writing and optical characteristics of the anti-glare screen. The purpose of this study is to provide information, which will help to select the appropriate screens for each application. Through the experiments with different AGLs and the displays, coefficient of friction, gloss value, sparkle contrast, and display modulation transfer function (MTF) were selected to characterize the writing and the optical characteristics. While the trend of the gloss values was similar to that of the display MTF, the trend of the sparkle contrast was different from them. These results were summarized as radar charts.

关键词： anti-glare education glare layer modulation transfer function pen writing sparkle

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Analytical and numerical fresnel models of phase diffractive optical elements for imaging applications

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OPTICAL AND QUANTUM ELECTRONICS 2024年第6期56卷 1-24页

作者： Unal, A. Middle East Tech Univ Dept Elect & Elect Engn Ankara Turkiye

Diffractive optical elements (DOEs) provide significant advantages over refractive optical elements due to their flexible design capabilities, leading to increasing usage in electro-optical systems. When the transmission function of diffractive lenses can be known analytically, determining the point spread function (PSF) becomes straightforward. However, in cases where analytical transmission equations cannot be derived, a general approach is necessary. In this study, we propose a new method that can be applied to any type of DOE to determine the numerical PSF. The simulation results are then compared to analytical and numerical methods. The findings of this research make significant contributions to the advancement of diffractive lenses by addressing the challenge of designing and analyzing these diffractive lenses. By offering a general approach for determining the PSF, the modulation transfer function (MTF) of the elements can also be determined by the proposed approach, even when the specific transmission function is difficult to ascertain. This study provides important contributions to the development of DOEs.

关键词： Phase fresnel zone plate Point spread function modulation transfer function Diffraction efficiency

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Theoretical and experimental study on spatial characteristics of a large imaging area streak camera developed for ICF precise diagnostics

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OPTICS COMMUNICATIONS 2024年 565卷

作者： Gu, Li He, Dong Lu, Guangzhao Yang, Yang Yu, Sheng Shenzhen Inst Informat Technol Shenzhen 518172 Peoples R China

The modulation transfer function (MTF) offers an objective measure to assess the imaging performance of streak cameras. This study aims to enhance the diagnostic precision of streak camera used in laser-driven inertial confinement fusion research. We introduce a novel method for evaluating the MTF of a recently developed large imaging area streak tube. This method integrates the electron optical MTF theory and the production of a reticle plate-type photocathode. Using ultraviolet and femtosecond lasers, we established two calibration platforms for the streak camera in both static and dynamic modes. We measured the radius of the electrons reaching fluorescent screen and obtained MTFs. Our findings reveal that the ultimate spatial resolutions at off-axis distances of 1.2, 4.7, 8.2, and 11.7mm are 28.5, 27.2, 26.4, 24.9 lp/mm (static) and 25.0, 22.8, 23.0, 21.2 lp/mm (dynamic). Notably, we successfully charted the ultimate spatial resolution distributions across the streak camera's full imaging area in both modes.

关键词： Detector Streak camera modulation transfer function Spatial resolution

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Simulation framework for X-ray grating interferometry optimization

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OPTICS EXPRESS 2025年第1期33卷 1345-1358页

作者： Spindler, Simon Pereira, Alexandre Sommer, Pascal Rawlik, Michal Romano, Lucia Stampanoni, Marco Swiss Fed Inst Technol Inst Biomed Engn CH-8092 Zurich Switzerland Paul Scherrer Inst Ctr Photon Sci Villigen Switzerland

Wave-front propagation simulations have been a tool to design and optimize X-ray interferometry devices. The often used plane wave approaches, however, lack the angular resolution to describe effects like system imperfections or inhomogeneous samples in conjunction with the X-ray source size. We developed a framework that allows to simulate optical components as well as samples with any source size in arbitrary configurations by inducing the mentioned effects within the wave propagation instead of adding intermediate models. The simulation results were able to predict and explain the impact of local grating defects for different focal spot sizes and provided a spectral sampling optimization for image acquisition. The simulation framework can run on GPU, do out-of-memory calculations, and is publicly available on Github. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

关键词： Imaging systems modulation transfer function Optical components Spatial resolution Wave propagation X-ray interferometry

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A direct comparison of a next generation hyperspectral camera to state-of-the-art

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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2025年 325卷 125068页

作者： Henriksen, Martin Lahn Pedersen, Jens-Christian Jensen, Bjarke Bror Egede Jorgensen, Bjarke Eriksen, Rene Lynge Hinge, Mogens Aarhus Univ Dept Biol & Chem Engn Plast & Polymer Engn Aabogade 40 DK-8200 Aarhus Denmark Univ Southern Denmark Mads Clausen Inst SDU NanoSYD Campusvej 55 DK-5230 Odense M Denmark Newtec Engn AS Staermosegaardsvej 18 DK-5230 Odense M Denmark

Hyperspectral camera technology is advancing rapidly, and this paper seeks to compare a state-of-the-art industrial dual-camera setup to a single-camera system employing the latest chip technology (IMX990 from Sony). The hyperspectral cameras are compared over both the Visual and Short-Wave Infrared range (400-1700 nm) of the electromagnet spectrum. The spectral range and resolution, as well as spatial parameters and spectroscopic information are quantified with comparable optics, electronics, and test targets. Generally, enhanced spectral detail and reduced noise were observed for the single-camera compared to its peers. Thus, the IMX990 shows promising performance for the new generation of hyperspectral cameras directly relevant to industrial applications, such as detection, documentation, and sorting.

关键词： Hyperspectral imaging Hyperspectral cameras modulation transfer function Short Wave Infrared Spectroscopy

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Experimental studies of the effect of measurement data loss on the quality of wavefront reconstruction using a Shack-Hartmann sensor in the presence of distortions from atmospheric turbulence

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JOURNAL OF OPTICAL TECHNOLOGY 2024年第8期91卷 527-532页

作者： Bolbasova, Lidia a. Lukin, Vladimir p. Soin, Egor l. Russian Acad Sci V E Zuev Inst Atmospher Opt Siberian Branch Tomsk 634055 Russia

Subject of study. The distortion of an optical laser wavefront by atmospheric turbulence is studied. Aim of study. The effect of data loss due to vignetting and central obscuration in the entrance pupil of an optical system on the Shack-Hartmann sensor reconstruction of a horizontally propagating laser wavefront distorted by atmospheric turbulence is experimentally determined. Method. Experimental studies were performed by studying the propagation of laser radiation along a horizontal atmospheric path with various vignetting and central obscuration ratios. The results were analyzed using Zernike polynomials. Main results. We describe the experimental results for the Shack-Hartmann sensor reconstruction of a horizontally propagating laser wavefront distorted by atmospheric turbulence, where the entrance pupil of the optical system was affected by vignetting and central obscuration. We show that central obscuration has no significant effect on wavefront reconstruction;however, artificially low spherical aberration values may require modification of the adaptive correction algorithm in the adaptive optics system. Coma aberration values will be artificially high in the presence of vignetting. Practical significance. Wavefront sensors are a key component in adaptive optics systems, and the measurements provided by such sensors affect the final result for correction of the optical wavefront distortions. The research results obtained herein will be important in the development of adaptive optics systems for atmospheric transmission and focusing of laser light passing through the atmosphere. (c) 2025 Optica Publishing Group

关键词： Adaptive optics Laser light modulation transfer function Optical systems Spherical aberration Systems design

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