激光光强扰动对相干场成像降质影响理论研究  

Theoretical research of influence of laser intensity fluctuation on imaging quality degradation of coherent field

作　　者：程志远[1] 马彩文[1] 马青[2] 

机构地区：[1]中国科学院西安光学精密机械研究所,西安710119 [2]西安建筑科技大学,西安710055

出　　处：《物理学报》2017年第24期49-55,共7页Acta Physica Sinica

基　　金：陕西省自然科学基金(批准号:2017JM6035)资助的课题~~

摘　　要：激光相干场成像系统发射多束激光,经大气传输对远程目标成像,大气湍流引起的激光束光强扰动是影响成像质量的一个关键因素.本文从湍流引起的激光束光强扰动对回波解调信号的影响关系入手,建立了激光回波光强扰动因子对相位闭合系数和成像频谱分量的降质传函理论模型;基于三光束激光相干场成像系统仿真验证了理论模型的有效性.研究表明激光相干场成像频谱分量和成像像质主要受三光束相位闭合求解算法中第二光束光强扰动影响.该研究揭示了激光回波光强扰动对成像像质的影响机理,对于分析大气湍流等引起的光强扰动降质效应和合理分配多光束光强稳定性以提高成像质量具有理论指导意义.The laser coherent field imaging system emits multiple beams of laser from earth to space, and laser scans remote space target by passing through turbulence atmosphere. Multi-beam laser intensity fluctuation caused by atmosphere turbulence is a key factor affecting high-resolution imaging quality of the coherent field imaging system. Aiming at solving the problem of imaging quality degradation caused by laser intensity fluctuation error, we discuss the mechanism of laser intensity fluctuation error influencing the imaging quality of laser coherent field high-resolution imaging system. The theoretical model about the relationship between laser intensity fluctuation factor and imaging quality is proposed for the first time. Firstly, the laser echo field signal error induced by laser intensity amplitude fluctuation factor is deduced according to laser transmitting atmosphere theory. Then adopting multi-beam phase closure arithmetic, the phase closure coefficient error is derived from the laser intensity fluctuation factor and laser echo field signal. The mechanism of disturbed laser echo signal influencing phase closure coefficient is investigated in detail. In the following, based on reconstructed spectrum theory, the model of imaging frequency spectrum error propagation, caused by laser intensity fluctuation factor, is proposed. Finally, we reveal the mechanism of laser intensity amplitude fluctuation factor influencing reconstructed imaging frequency spectrum and imaging quality. The correctness and validity of the theoretical model are verified in simulation experiment. In the three-beam laser coherent field imaging simulation experiment, the imaging quality is evaluated by the Strehl ratio of the image. Experimental result shows that the Strehl ratio is only related to the light intensity fluctuation of one of the three beams of laser, and the greater the fluctuation of laser intensity, the more serious the degradation of imaging quality is. The research draws the conclusion that the reconstructed imaging frequ

关 键 词：激光光强扰动 频谱误差 成像质量 激光相干场成像 

分 类 号：O436[机械工程—光学工程]