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Combination of color coding and wavefront coding for extended depth of field

OPTICS COMMUNICATIONS 2017年 392卷 252-257页

作者： Cao, Zhaolou Zhai, Chunjie Li, Jinhua Xian, Fenglin Pei, Shixin Nanjing Univ Informat Sci & Technol Sch Phys & Optoelect Engn Nanjing 210044 Jiangsu Peoples R China Nanjing Forest Police Coll Dept Forest Fire Protect Nanjing 210008 Jiangsu Peoples R China

Color coding has been experimentally demonstrated to be able to extend the depth of field (DoF) of an imaging system in single snapshot. A numerical model is adopted in this paper to quantitatively characterize its imaging properties (strehl ratio, point spread function and modulation transfer function). To improve the system's performance under nonuniform spectrum, we proposed to introduce wavefront coding into the system. Numerical results show that wavefront coding acts as an average filter of the spectrum, so that it is able to get an almost invariant MTF across the focal line even under nonuniform spectrum, which is desirable in many applications.

关键词： Extended depth of field Chromatic aberration wavefront coding

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Reduction of spherical-aberration impact in microscopy by wavefront coding

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OPTICS EXPRESS 2009年第16期17卷 13810-13818页

作者： Saavedra, G. Escobar, I. Martinez-Cuenca, R. Sanchez-Ortiga, E. Martinez-Corral, M. Univ Valencia Dept Opt E-46100 Burjassot Spain Univ Castilla La Mancha Dept Appl Phys E-16071 Cuenca Spain

In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging deep inside the specimen, spreading out the impulse response. Since such aberration depends on the focalization depth, it is not possible to achieve a static global compensation for the whole 3D sample in scanning microscopy. Therefore a depth-variant impulse response is generated. Consequently, the design of pupil elements that increase the tolerance to this aberration is of great interest. In this paper we report a hybrid technique that provides a focal spot that remains almost invariant in the depth-scanning processing of thick samples. This invariance allows the application of 3D deconvolution techniques to that provide an improved recovery of the specimen structure when imaging thick samples. (C) 2009 Optical Society of America

关键词： .correction immersion mismatch pupil defocus spherical aberration wavefront coding Impulse Response focal spot thick samples high-NA significant amount Ojeda-Casta

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Analytical model for effect of temperature variation on PSF consistency in wavefront coding infrared imaging system

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OPTICS COMMUNICATIONS 2016年 367卷 35-43页

作者： Feng, Bin Shi, Zelin Zhang, Chengshuo Xu, Baoshu Zhang, Xiaodong Chinese Acad Sci Shenyang Inst Automat Shenyang 110016 Peoples R China Chinese Acad Sci Key Lab Optoelect Informat Proc Shenyang 110016 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Tianjin Univ Ctr MicroNano Mfg Technol State Key Lab Precis Measuring Technol & Instrume Tianjin 300072 Peoples R China

The point spread function (PSF) inconsistency caused by temperature variation leads to artifacts in decoded images of a wavefront coding infrared imaging system. Therefore, this paper proposes an analytical model for the effect of temperature variation on the PSF consistency. In the proposed model, a formula for the thermal deformation of an optical phase mask is derived. This formula indicates that a cubic optical phase mask (CPM) is still cubic after thermal deformation. A proposed equivalent cubic phase mask (E-CPM) is a virtual and room-temperature lens which characterizes the optical effect of temperature variation on the CPM. Additionally, a calculating method for PSF consistency after temperature variation is presented. Numerical simulation illustrates the validity of the proposed model and some significant conclusions are drawn. Given the form parameter, the PSF consistency achieved by a Ge-material CPM is better than the PSF consistency by a ZnSe-material CPM. The effect of the optical phase mask on PSF inconsistency is much slighter than that of the auxiliary lens group. A large form parameter of the CPM will introduce large defocus-insensitive aberrations, which improves the PSF consistency but degrades the room-temperature MTF. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Analytical model wavefront coding PSF consistency Infrared imaging Athermalization

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110 °C range athermalization of wavefront coding infrared imaging systems

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INFRARED PHYSICS & TECHNOLOGY 2017年 85卷 157-162页

作者： Feng, Bin Shi, Zelin Chang, Zheng Liu, Haizheng Zhao, Yaohong Chinese Acad Sci Key Lab Optoelect Informat Proc Shenyang 110016 Liaoning Peoples R China Chinese Acad Sci Shenyang Inst Automat Shenyang 110016 Liaoning Peoples R China Xian Technol Univ Sch Optoelect Engn Xian 710032 Shaanxi Peoples R China

110 degrees C range athermalization is significant but difficult for designing infrared imaging systems. Our wavefront coding athermalized infrared imaging system adopts an optical phase mask with less manufacturing errors and a decoding method based on shrinkage function. The qualitative experiments prove that our wavefront coding athermalized infrared imaging system has three prominent merits: (1) working well over a temperature range of 110 degrees C;(2) extending the focal depth up to 15.2 times;(3) achieving a decoded image being approximate to its corresponding in-focus infrared image, with a mean structural similarity index (MSSIM) value greater than 0.85. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Computational imaging wavefront coding Athermalization Infrared imaging

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Athermalization of infrared optical system through wavefront coding

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OPTICS COMMUNICATIONS 2019年 441卷 106-112页

作者： Xie, Hongbo Su, Yongpeng Zhu, Meng Yang, Lei Wang, Shanshan Wang, Xiaobo Yang, Tong Tianjin Univ Coll Precis Instrument & Optoelect Engn Key Lab Optoelect Informat Technol Minist Educ Tianjin 300072 Peoples R China Tianjin Jinhang Inst Tech Phys Tianjin 300308 Peoples R China

Owing to the thermal effect of optical components, it has been challenging for conventional infrared optical imaging system to work in a large temperature range. wavefront coding technique has been shown to greatly increase tolerance to manufacturing inaccuracies and various defocus, particularly thermal defocus. In this paper, we develop an entirely new infrared imaging modality in 3.7 similar to 4.8 mu m waveband, realized with a secondary imaging structure, a non-rotationally symmetric phase mask and a cooled infrared focal plane arrays. The proposed system offers the ability to overcome the temperature limitations of conventional infrared system as well as effectively eliminate the thermal aberration. Proof-of-concept results demonstrate significantly our athermalized optical system perform high-quality images in the operation temperature range of -40 degrees C to 70 degrees C.

关键词： Athermalization Infrared optical imaging Non-rotationally symmetric phase mask wavefront coding

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Performance Analysis of Spiral Axicon wavefront coding Imaging System for Laser Protection

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CURRENT OPTICS AND PHOTONICS 2024年第4期8卷 355-365页

作者： Luo, Haoqi Li, Yangliang Zhang, Junyu Zhang, Hao Wu, Yunlong Ye, Qing Natl Univ Def Technol State Key Lab Pulsed Power Laser Technol Hefei 230037 Peoples R China Adv Laser Technol Lab Anhui Prov Hefei 230026 Peoples R China Univ Sci & Technol China Dept Opt & Opt Engn Hefei 230026 Peoples R China

wavefront coding (WFC) imaging systems can redistribute the energy of an interference laser spot on an image plane sensor by wavefront phase modulation and reduce the peak intensity, realizing laser protection while maintaining imaging functionality by leveraging algorithmic post-processing. In this paper, a spiral axicon WFC imaging system is proposed, and the performance for laser protection is investigated by constructing a laser transmission model. An Airy disk on an image plane sensor is refactored into a symmetrical hollow ring by a spiral axicon phase mask, and the maximum intensity can be reduced to lower than 1% and single-pixel power to 1.2%. The spiral axicon phase mask exhibits strong robustness to the position of the interference laser source and can effectively reduce the risk of sensor damage for an almost arbitrary lase propagation distance. Moreover, we revealed that there is a sensor hazard distance for both conventional and WFC imaging systems where the maximum single-pixel power reaches a peak value under irradiation of a power-fixed laser source. Our findings can offer guidance for the anti-laser reinforcement design of photoelectric imaging systems, thereby enhancing the adaptability of imaging systems in a complex laser environment. The laser blinding-resistant imaging system has potential applications in security monitoring, autonomous driving, and intense-laser-pulse experiments.

关键词： Anti-laser damage Imaging system Laser safety Laser transmission wavefront coding

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Performance analysis of wavefront coding system with spherical aberration by using ray aberration approach

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OPTIK 2017年 130卷 1266-1271页

作者： Shi, Yaotao Chen, Shouqian Van Nhu Le Fan, Zhigang Zhang, Wang Harbin Inst Technol Res Ctr Space Opt Engn Harbin 150001 Heilongjiang Peoples R China

Imaging characteristics of wavefront coding systems in the presence of spherical aberration are analyzed by using ray aberration approach. The analytical expressions for ray aberration, the boundary of ray map and the size of spot diagram of a wavefront coding system in the presence of defocus and spherical aberration are obtained by wave aberration theory. The effect of spherical aberration on imaging performance of wavefront coding systems with a cubic phase mask is presented by ray aberration and spot diagram. The results show that the wavefront coding systems have a high tolerance to spherical aberration through a given defocus range. (C) 2016 Published by Elsevier GmbH.

关键词： wavefront coding Spherical aberration Ray aberration Phase mask Aperture

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Extended-depth-of-field object detection with wavefront coding imaging system

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PATTERN RECOGNITION LETTERS 2019年 125卷 597-603页

作者： Dong, Liquan Du, Haoyuan Liu, Ming Zhao, Yuejin Li, Xueyan Feng, Shijia Liu, Xiaohua Hui, Mei Kong, Lingqin Hao, Qun Beijing Inst Technol Sch Opt & Photon Beijing Key Lab Precis Optoelect Measurement Inst Beijing Peoples R China

As an important issue in the field of computer vision, object detection has broad application prospects. Recent researches using convolutional neural networks (CNN) have shown the state-of-the-art results in the challenge competition. Most of them focused on improving the precision under ideal imaging conditions. However, it is hard to ensure that the optical imaging system works in the focused state in practice. In this study, we examine the impact of defocus on detection accuracy. The results show that even the state-of-the-art network is sensitive to a different defocus situation. Thus we put forward wavefront coding (WFC) technique for improving the performance over a large range of depth of field (DOF). Simulation results indicate the improvement on average precision of detection results by applying WFC. In addition, we propose a novel WFC method for overcoming the defects of the traditional one. Then the optical imaging system is designed under the guidance of the proposed theory. Experiments are conducted to suggest that the detection accuracy rate can be enhanced considerably with WFC. (C) 2019 Published by Elsevier B.V.

关键词： Object detection wavefront coding Computational imaging Imaging systems

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Breaking diffraction limit of a small f-number compact camera using wavefront coding

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OPTICS EXPRESS 2008年第18期16卷 13569-13578页

作者： Lee, Sang-Hyuck Park, No-Cheol Park, Young-Pil Yonsei Univ Ctr Informat Storage Device Seoul 120749 South Korea Yonsei Univ Dept Mech Engn Seoul 120749 South Korea

We propose a resolution enhancement method for mobile small f-number compact imaging systems based on wavefront coding and superresolution image processing. wavefront coding increases the focus depth of an optical system and produces point spread functions (PSFs) with similar characteristics at different field and defocus positions. The designed target wavefront is realized as a combination of wavefront errors of each rotationally symmetric lens, without including an additional phase plate. Finally, using one deconvolution filter containing all the characteristics of the PSFs, we achieve high resolution, breaking the diffraction limit of small f-number and the resolution limit of the image sensor by super-resolution image processing. (c) 2008 Optical Society of America.

关键词： .optical system small number PSFs SPATIAL FREQUENCY image restoration wavefront errors diffraction limit IMAGE SENSOR wavefront coding resolution limit compact imaging field and defocus target wavefront deconvolution filter

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The dynamic aberrations suppression of conformal optical system by wavefront coding

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OPTICS COMMUNICATIONS 2020年第0期463卷 125121-000页

作者： Yu, Jiaqian Chen, Shouqian Dang, Fanyang Li, Xueshen Shi, Xiaotian Ju, Lin Wang, Hui Xu, Xianmei Fan, Zhigang Harbin Inst Technol Res Ctr Space Opt Engn Harbin 150001 Heilongjiang Peoples R China Harbin Engn Univ Key Lab Fiber Integrated Opt Minist Educ China Harbin 150001 Peoples R China

In conformal optics, the dynamic aberrations of conformal optical system (DACOS) are difficult to correct and would cause serious image degradation. In this work, we propose a method based on wavefront coding (WFC) technology to suppress the DACOS. A conformal dome with highly significant dynamic aberrations (about +/- 8 lambda) is established and its aberration characteristics are investigated using Zernike aberration theory. A simple cubic phase mask (CPM) is inserted in its pupil plane to suppress residual dynamic aberrations after preliminary aberration correction. The simulation results show that, the utilization of WFC technology could not only suppress the DACOS efficiently, but also reduce physical imaging elements, which could in turn relax the alignment and fabrication tolerances. This work is of consequence in conformal optical systems design.

关键词： Optical system design Infrared optics Conformal optics wavefront coding

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