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Design of online damage images detection system for large-aperture mirrors of high power laser facility based on wavefront coding technology

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NUCLEAR ENGINEERING AND TECHNOLOGY 2021年第9期53卷 2899-2908页

作者： Wang Fang Liu Qinxiao Hu Dongxia Liu Hongjie Zheng Tianran Sichuan Univ Coll Elect & Informat Engn Chengdu 610065 Sichuan Peoples R China China Acad Engn Phys Res Ctr Laser Fus Mianyang 621900 Sichuan Peoples R China Chongqing Univ Technol Sch Artificial Intelligence Chongqing 400054 Peoples R China

The laser transport system of the high power laser facility is mainly composed of large-aperture laser transport mirrors (TMs). Obtaining the high-resolution online damage images during the operation, which is of great significance for operating safely of the mirrors and the facility. Based on wavefront coding, pan-tilt scanning and image stitching technologies, an online laser-damage images detection system is designed, and it can achieve high-precision detection of surface characteristics of large aperture laser transport mirrors. The preliminary simulation proves that the system can solve the depth of field matching problem caused by pan-tilt tilt imaging and achieve higher resolution. (c) 2021 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Online damage detection wavefront coding Large-aperture laser transport mirrors High power laser facility

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Aperture shape dependencies in extended depth of focus for imaging camera by wavefront coding

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OPTICAL REVIEW 2015年第1期22卷 9-18页

作者： Sakita, Koichi Ohta, Mitsuhiko Shimano, Takeshi Sakemoto, Akito Hitachi Ltd Yokohama Res Lab Yokohama Kanagawa 2440817 Japan Hitachi Maxell Ltd Finetech Div Watarai Miyagi 9892383 Japan

Optical transfer functions (OTFs) on various directional spatial frequency axes for cubic phase mask (CPM) with circular and square apertures are investigated. Although OTF has no zero points, it has a very close value to zero for a circular aperture at low frequencies on diagonal axis, which results in degradation of restored images. The reason for close-to-zero value in OTF is also analyzed in connection with point spread function profiles using Fourier slice theorem. To avoid close-to-zero condition, square aperture with CPM is indispensable in WFC. We optimized cubic coefficient a of CPM and coefficients of digital filter, and succeeded to get excellent de-blurred images at large depth of field.

关键词： wavefront coding EDOF Aperture stop PSF OTF MTF De-convolution

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The application of wavefront coding in the infrared optical system in the tokomak fusion reaction

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FUSION ENGINEERING AND DESIGN 2012年第4期87卷 369-372页

作者： Zhang Bang-shuai Chang Jun Gong Xian-zu Gan Kai-fu Feng Shu-long Ouyang Jiao Beijing Inst Technol Sch Optoelect Dept Optoelect Engn Beijing 100081 Peoples R China Chinese Acad Sci Inst Plasma Phys Hefei 230031 Anhui Peoples R China Chinese Acad Sci Changchun Inst Opt & Fine Mech Changchun 130022 Jilin Peoples R China

This article describes the principle of wavefront coding (WFC) technology and the role it plays in optical system. The infrared optical system in tokamak includes three parts: (1) the combination of the concave aspheric mirror and flat mirror;(2) the Cassegrain system;(3) the relay group lenses. Because of the application of wavefront coding, the optical system is less sensitive to the change of the temperature and the depth of field is enlarged. Comparing the modulation transfer function (MTF) of the original optical system and the improved system in different temperatures, the results show that the new system can be used in a larger range of temperature. (C) 2012 Elsevier B.V. All rights reserved.

关键词： wavefront coding Nuclear fusion Tokomak Infrared ray (IR) optical system

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Study on the properties of infrared wavefront coding athermal system under several typical temperature gradient distributions

Study on the properties of infrared wavefront coding atherma...

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International Conference on Optical Instruments and Technology (OIT) at the Topical Meeting on Optoelectronic Imaging/Spectroscopy and Signal Processing Technology

作者： Cai Huai-yu Dong Xiao-tong Zhu Meng Huang Zhan-hua Tianjin Univ Sch Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China Tianjin Jinhang Inst Tech Phys Tianjin 300192 Peoples R China

ISBN: (数字)9781510617520

ISBN: (纸本)9781510617520;9781510617513

wavefront coding for athermal technique can effectively ensure the stability of the optical system imaging in large temperature range, as well as the advantages of compact structure and low cost. Using simulation method to analyze the properties such as PSF and MTF of wavefront coding athermal system under several typical temperature gradient distributions has directive function to characterize the working state of non-ideal temperature environment, and can effectively realize the system design indicators as well. In this paper, we utilize the interoperability of data between Solidworks and ZEMAX to simplify the traditional process of structure/thermal/optical integrated analysis. Besides, we design and build the optical model and corresponding mechanical model of the infrared imaging wavefront coding athermal system. The axial and radial temperature gradients of different degrees are applied to the whole system by using SolidWorks software, thus the changes of curvature, refractive index and the distance between the lenses are obtained. Then, we import the deformation model to ZEMAX for ray tracing, and obtain the changes of PSF and MTF in optical system. Finally, we discuss and evaluate the consistency of the PSF (MTF) of the wavefront coding athermal system and the image restorability, which provides the basis and reference for the optimal design of the wavefront coding athermal system. The results show that the adaptability of single material infrared wavefront coding athermal system to axial temperature gradient can reach the upper limit of temperature fluctuation of 60 degrees C, which is much higher than that of radial temperature gradient.

关键词： athermalization temperature gradient wavefront coding infrared optical systems

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USE OF SPATIAL LIGHT MODULATORS IN wavefront coding FOR FIELD IMAGING: ADAPTATION OF THE FILTER DESIGN PROCEDURE

USE OF SPATIAL LIGHT MODULATORS IN WAVEFRONT CODING FOR FIEL...

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Conference on Optics, Photonics, and Digital Technologies for Multimedia Applications

作者： Ferran, Carme Vallmitjana, Santiago Bosch, Salvador Univ Barcelona Dept Fis Aplicada & Opt Barcelona Spain

ISBN: (纸本)9780819481962

wavefront coding (WFC) is an imaging technique for enhancing some invariance capabilities of optical instruments (typically invariance against defocus). So far, the procedure has been mostly used in practical environments where the optical aberrations of the optical system correspond to a rotationally symmetrical one, i.e., on-axis imaging. These problems have been extensively tackled in recent years, leading to successful designs like the cubic and petal-shaped phase plates. An interesting aspect of the implementation of the phase plate is the use of a liquid crystal spatial light modulator (SLM) placed at the pupil of the instrument, since it allows enhanced versatility. Under these circumstances, the characteristics of the pupil phase plate, in order to provide invariance, refer only to spherical and defocus aberrations. However, when the optical system is not rotationally symmetrical, like for field imaging, the theoretical framework of the problem is quite different, as one has to deal with more general aberrations. Our aim is to analyze this field imaging invariance problem when using WFC techniques and to try to extend the well known on-axis techniques to this new application.

关键词： wavefront coding Hybrid imaging systems Aberrations in optical systems

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Field depth extension of 2D barcode scanner based on wavefront coding and projection algorithm

Field depth extension of 2D barcode scanner based on wavefro...

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Conference on Information Optics and Photonics Technologies II

作者： Zhao Tingyu Zi, Ye Zhang Wenzi Huang Weiwei Yu Feihong Zhejiang Univ Dept Opt Engn State Key Lab Modern Opt Instrumentat Hangzhou 310027 Peoples R China

ISBN: (纸本)9780819470126

wavefront coding (WFC) used in 2D barcode scanners can extend the depth of field into a great extent with simpler structure compared to the autofocus microscope system. With a cubic phase mask (CPM) employed in the STOP, blurred images will be obtained in charge coupled device (CCD), which can be restored by digital filters. Direct methods are used widely in real-time restoration with good computational efficiency but with details smoothed. Here, the results of direct method are firstly filtered by hard-threshold function. The positions of the steps can be detected by simple differential operators. With the positions corrected by projection algorithm, the exact barcode information is restored. A wavefront coding system with 7mm effective focal length and 6 F-number is designed as an example. Although with the different magnification, images of different object distances can be restored by one point spread function (PSF) with 200mm object distance. A QR code (Quickly Response Code) of 31mm X 27mm is used as a target object. The simulation results showed that the sharp imaging objective distance is from 80mm to 355mm. The 2D barcode scanner with wavefront coding extends field depth with simple structure, low cost and large manufacture tolerance. This combination of the direct filter and projection algorithm proposed here could get the exact 2D barcode information with good computational efficiency.

关键词： 2D barcode scanner field depth extension wavefront coding projection algorithm

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Iterative design of mesh-defined phase masks for wavefront coding

Iterative design of mesh-defined phase masks for wavefront c...

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Conference on Optics, Photonics, and Digital Technologies for Multimedia Applications

作者： Carles, G. Carnicer, A. Bosch, S. Univ Barcelona Dept Fis Aplicada & Opt E-08028 Barcelona Spain

ISBN: (纸本)9780819481962

A new phase mask typology for wavefront-coding is proposed, the meshed phase mask (MPM). It is intended to be a flexible form in order to be easily adaptable. The use of an evaluating criterion to measure the performance of the MPM is used to optimize its shape. The MPM is uniquely defined by the fixed phase in a number of control points equally spaced in the pupil area. These control points define a regular mesh, and the continuous MPM phase surface is obtained from cubic spline interpolation. A global search algorithm is used to optimize the values at the control points, thus optimizing the MPM. The preliminary results show an improvement over the conventional cubic phase mask, especially in reducing the undesired artefacts in the final restored images.

关键词： wavefront coding image processing imaging systems phase mask optimization

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DECONVOLUTION PROCESS WITH GPU IN A wavefront coding MICROSCOPY SYSTEM 20

DECONVOLUTION PROCESS WITH GPU IN A WAVEFRONT CODING MICROSC...

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Conference on Current Developments in Lens Design and Optical Engineering XX

作者： Ortega-Sanchez, K. Toxqui-Quitl, C. Padilla-Vivanco, A. Univ Politecn Tulancingo Ingn 100 Tulancingo 43629 Hidalgo Mexico

ISBN: (数字)9781510629028

ISBN: (纸本)9781510629028

A wavefront coding microscopy system is implemented in order to extend the depth of field of an optical system. An LC - SLM is used to display the profile of a phase mask. A set of optically coded images is recorded in an axial range [-1, 1.5] mm. To accelerate the deconvolution process, a routine developed directly on a GPU is implemented. Using this GPU based approach, the deconvolution time is reduced by providing an additional speed up to the visualization. Digital images are acquired using an experimental setup and results are presented.

关键词： wavefront coding GPU Microscopy system Spatial Light Modulator

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Miniaturization and simplification of zoom lenses using wavefront coding

Miniaturization and simplification of zoom lenses using wave...

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11th Conference on Novel Optical Systems Design and Optimization

作者： Demenikov, Mads Findlay, Ewan Harvey, Andrew R. Heriot Watt Univ Imaging Concepts Grp Sch Engn & Phys Sci Edinburgh EH14 4AS Midlothian Scotland STMicroelect Edinburgh EH12 7BF Midlothian Scotland

ISBN: (纸本)9780819472816

Traditional zoom lens designs employ multiple moving lens elements to provide simultaneous control of focal length and focal plane. We present an approach to a design of a simplified zoom lens by employing a single moving element to control only the focal length. We show that the defocus in miniaturized zoom lenses with a single moving element can be corrected by the use of wavefront coding, although this introduces a modest reduction in signal-noise-ratio. As an example, we present a design of a miniaturized 10 mm long wavefront coded 2.3x optical zoom lens with a single moving lens element.

关键词： Zoom lenses wavefront coding extended depth of field optical design design miniaturization and design simplification

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A new kind of phase mask and its properties using in wavefront coding systems

A new kind of phase mask and its properties using in wavefro...

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International Conference on Optical Instruments and Technology - Optical Systems and Optoelectronic Instruments

作者： Cai, Huaiyu Fang, Chao Fan, Liqiang Huang, Zhanhua Zhang, Yinxin Tianjin Univ Coll Precis Instrument & Optoelect Engn Minist Educ Key Lab Optoelect Informat Sci & Technol Tianjin 300072 Peoples R China

ISBN: (纸本)9780819474001

The phase mask plays a key role in wavefront coding systems. In order to find the phase coding device with better performance, a new kind of phase mask--five times phase mask is proposed, based on cubic phase mask in common use, and its coding properties are studied in the paper. First of all, the reason of depressing spherical aberration is analyzed by deriving the asymptotic solution to OTF of the wavefront coding systems with five times phase mask. And then we compare the effects of inhibition of spherical aberration when place the cubic and five times phase mask respectively. Finally, the experimental simulation is done. The results show that on the specific threshold (MTF=0.1) the normalized bandwidth of the system with five times phase mask can be reached 3 times of that with the cubic one;at the same characteristic frequency (u = 0.5), the MTF value is 2 times of that in system with cubic one. Both the MTF consistency in the low frequency region and the PTF consistency in the high frequency region of the system with a five times phase mask are better than those with a cubic one in condition of different spherical aberration. Compared with the cubic phase mask, the five times phase mask performs better in inhibition of spherical aberration.

关键词： wavefront coding five times phase mask cubic phase mask OTF MTF PTF inhibition of spherical aberration consistency

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