基于全相位谱分析的剪切光束成像目标重构  

Sheared-beam imaging target reconstruction based on all-phase spectrum analysis

作　　者：陈明徕 罗秀娟[1] 张羽[1] 兰富洋 刘辉[1] 曹蓓[1] 夏爱利[1] Chen Ming-Lai Luo Xiu-Juan Zhang Yu Lan Fu-Yang Liu Hui Cao Bei Xia Ai-Li(Xi＇an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi＇an 710119, China)

机构地区：[1]中国科学院西安光学精密机械研究所,西安710119

出　　处：《物理学报》2017年第2期141-146,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61505248)资助的课题~~

摘　　要：剪切光束成像技术是一种非传统散斑成像技术,能透过扰动介质对远距离目标进行高分辨率成像.本文提出了一种基于全相位谱分析的图像重构算法,利用全相位谱分析对回波信号数据进行预处理,可有效抑制频谱泄露,校正散斑频谱,消除多种因素引起的频率漂移误差,得到准确的散斑强度和相位差,提高实际成像环境的系统成像能力.仿真结果表明:该图像重构算法有效抑制了频率漂移对成像质量的影响,当信号存在频率误差时,其成像效果大大优于基于传统傅里叶变换谱分析的重构算法.Sheared-beam imaging technique is considered to be a non-conventional speckle technique for remote imaging through turbulent medium. In this high resolution imaging technique, three beams are splitted from one laser source and illuminate a remote target simultaneously in shearing distribution. Each beam is modulated by a tiny frequency shift so that these beams can interfere and beat together. The returning speckle signals are received by an array of detectors. The primary algorithm for the signal processing and image reconstruction has been developed previously.However, the reconstructed image is deteriorated by the frequency drifting error and spectrum leakage. These frequency errors are always from the transmitter and scattered signals that are caused by spectrum-shift errors from acousticoptic modulators, atmospheric turbulence, Doppler effects of moving targets, etc. To solve the problems mentioned above, in this paper we propose a new image reconstruction algorithm based on the all-phase spectrum analysis theory.The all-phase fast Fourier transform（FFT） spectrum analysis theory, which can effectively inhibit spectral leakage and correct speckle spectrum, is used to process the scattered signals. By searching for the accurate positions of the beat frequency components in the transformed frequency domain data, the speckle amplitude and phase difference frames can be extracted accurately. Based on the speckle phase-difference frames, the phase distribution of the wavefront is derived by least-square algorithm. The phase distribution in grid is highly coherent, in which each point is related to the phases of its four nearest neighbors. If an initial phase map is given or preset, the phase map of the wavefront can be estimated accurately by Gauss-Seidel method. Meanwhile, the amplitude of wavefront is obtained by the algebraic operation of speckle amplitude frames. The reconstructed wavefront is inverse Fourier transformed to yield a two dimensional image.A series of speckled images of the same object are av

关 键 词：剪切光束成像 散斑 全相位谱分析 目标重构 

分 类 号：O439[机械工程—光学工程]