Laser Active Imaging Research Articles

大气条件下距离选通激光主动成像技术发展现状

大气条件下距离选通激光主动成像技术发展现状

基于信号子空间谱域约束的激光主动成像散斑噪声去除

基于信号子空间谱域约束的激光主动成像散斑噪声去除

Intensity image denoising for laser active imaging system using nonsubsampled contourlet transform and SURE approach

This paper presents an algorithm based on nonsubsampled contourlet transform (NSCT) and Stein's unbiased risk estimate with a linear expansion of thresholds (SURE-LET) approach for intensity image denoising. First, we analyzed the multiplicative noise model of intensity image and make the non-logarithmic transform on the noisy signal. Then, as a multiscale geometric representation tool with multi-directivity and shift-invariance, NSCT was performed to capture the geometric information of images. Finally, SURE-LET strategy was modified to minimize the estimation of the mean square error between the clean image and the denoised one in the NSCT domain. Experiments on real intensity images show that the algorithm has excellent denoising performance in terms of the peak signal-to-noise ratio (PSNR), the computation time and the visual quality.

Design and simulation of a high resolution active imaging technique utilizing Fresnel telescopy

A new technique for high resolution active laser imaging of space objects is demonstrated. The technique, referred as Fresnel telescopy, is a variant of Fourier telescopy, which additionally uses Fresnel zone plates to scan objects. The design scheme of a compact schematic of transmitting and receiving system for Fresnel telescopy is proposed. We provide simulations results for imaging of a photograph of satellite to illustrate and clarify the proposed idea. The technique is found to have substantial practical value and offers significant practical benefit for high resolution imaging of objects in the field of military applications.

Influence of Atmospheric Propagation on Performance of Laser Active Imaging System

Atmospheric propagation has serious influence on the performance of a good designed laser active imaging system. Atmospheric attenuation and turbulence are two main effects on laser atmospheric propagation. Imaging SNR (Signal-Noise-Ratio) and resolution are two key indexes to describe the performance of a laser active imaging system. Establishing the relation between system performance index and atmospheric propagation effect is significant. The paper analyzed the relation between imaging performance and atmospheric attenuation and turbulence through simulation. And also the experiments were done under different weather to validate the conclusion of simulation.

半导体激光器主动红外夜视监控系统设计

Active night vision imaging is an active laser imaging,it is a new technology of the laser technology,imaging sensor technology,weak target imaging processing technology combined with the development of new technologies.NIR diode laser as a light source,on the low-light situation,the long-range target was detected and imaged.The principle of active laser night vision surveillance and active night vision surveillance system components were described in detail,while the experimental results of monitoring different targets were compared.

提高激光主动成像系统性能的匹配设计

提高激光主动成像系统性能的匹配设计

基于序贯检验的激光主动成像目标探测方法

基于序贯检验的激光主动成像目标探测方法

Beam-shaping method for uniform illumination by superposition of tilted Gaussian beams

Efficient beam shaping with uniform illumination is required in laser active imaging and detecting systems. In this paper, a beam-shaping method by superposition of tilted fundamental-mode Gaussian beams to produce nearly uniform illumination is proposed. The analytical formula for the average intensity of propagating multitilted Gaussian beams (MTGBs) is derived and used to study the uniformity of the beam profile with Fourier analysis. It is found that the MTGB maintains its flat-topped shape as it propagates and its uniformity is controlled by the parameters of fundamental-mode beams and superposition. Numerical examples are given. The method is used to reconfigure the beams of a high-power laser diode stack to form a MTGB shape for illumination of a 9×11.6-deg angular field. The simulation results from ASAP software show a shaping efficiency of 75%, and the rms deviation of the irradiance distribution from a flat-top shape is approximately 8%.