近距离激光外差探测光学极限位移分辨率  

Short-range optical limited displacement resolution in laser heterodyne detection system

作　　者：晏春回 王挺峰[1] 张合勇[1] 吕韬 吴世松 

机构地区：[1]中国科学院长春光学精密机械与物理研究所,激光与物质相互作用国家重点实验室,长春130033 [2]中国科学院大学,北京100049

出　　处：《物理学报》2017年第23期192-199,共8页Acta Physica Sinica

基　　金：中国科学院前沿科学重点研究计划(批准号:QYZDB-SSW-SLH014);国家自然基金青年科学基金(批准号:61205143)资助的课题~~

摘　　要：通过统计理论和维纳-辛钦定理推导出激光外差探测系统光电流的功率谱函数,分析了光电流谱线分布与激光光源线宽、中频信号频率以及信号光相对本振光传输延迟时间的关系,修正了相关文献中光电流功率谱的理论公式.根据信号与噪声理论建立了激光线宽引起的相位噪声的一维概率分布模型,并据此得到了基于激光波长、探测距离以及激光线宽的极限位移分辨率的数学模型.对光电流的功率谱和外差光学极限位移分辨率进行了相关的数值仿真,结果表明延迟时间与相干时间的关系决定光电流谱线分布的情况.当激光波长为532 nm,激光线宽在1 kHz,探测距离为100 m时,光学极限位移分辨率为0.266 nm,相关文献中的实验数据与理论推导结果相符合.Photocurrent power spectral density function of laser heterodyne detection is obtained by the statistical theory and Wiener-Khinchin theorem. For a short-range distance heterodyne system without considering atmospheric turbulence, we observe the relations between the photocurrent spectral line distribution and the laser linewidth, the intermediate-frequency signal, and the propagation delay time of signal light relative to local oscillator light. Theoretical formula of photocurrent power spectrum in relevant papers is revised to eliminate the effect of laser linewidth. Onedimensional probability distribution model of phase noise caused by laser linewidth is built based on the signal and noise theory. Accordingly we establish a mathematical model of limit detection accuracy based on laser wavelength, detection distance, and laser linewidth, which indicates the minimum detectable amplitude of heterodyne system. According to the numerical results, we find that the distribution of photocurrent spectral line intensities is greatly dependent on the relation between delay time and coherent time. And the minimum resolvable displacement increases with the detection distance and laser linewidth increasing. When the optical limited displacement resolution is 0.266 nm with a laser wavelength of 532 nm, a laser linewidth is 1 kHz, and a detection distance is 100 m. Experimental data in relevant papers agree well with the theoretical derivations. Our findings show that the research of displacement resolution might provide a quantitative reference for the theoretical research and engineering application of short-range heterodyne resolution.

关 键 词：激光多普勒测振 激光应用 激光 

分 类 号：TN24[电子电信—物理电子学]