超声波的光外差接收

Laser Heterodyne Interferomteric System for Ultrasonic Detection

激光接收超声是一种非接触式的超声接收技术，它在超声无损评估及检测领域有重要的应用。本文设计研制了激光外差干涉接收超声的实验系统，该系统由声光调制器产生光频的频移，锁相环进行位相解调。文中重点讨论：（１）在光学部分，外差干涉光路空间准直性对信噪比的影响。（２）在信号处理电路部分。

Receiving ultrasonic wave by laser is an non contact ultrasonic detection technique,it is quite important for ultrasonic nondestructive evaluation and measurement.In this paper,a laser heterodyne interferometric system for ultrasonic detection is reported.In the system,alock phase loop (LPL) is used for phase demodulation.The emphases of our discussion are placed on (1) in the optics,the effect of space collimation of signal light wave and reference light wave on the signal to noise ratio of detect system,and (2) in the electronic process,the analysis of lock phase loop characteristic.The signal to noise will decrease sharply with θ according to sincfuntion, θ is the angle between the signal light path and reference light path.LPL is a key part for phase demodulation and decreasing of noise by correlation technique,it is important to determine properly the parameters of LPL acording to the analysis of characteristic of LPL.