【摘要】 本文介绍了激光外差探测超声位移的原理，用布喇格声光衍射盒作为激光移频，锁相环作调相信号解调等方法组成的外差干涉探测装置和实验结果，并分析了空间准直性对激光外差干涉信噪比的影响以及减小探测极限和抑制噪声的途径。更多还原

【Abstract】 This paper describes the measuring principle, method and experiment of ultrasonic displacement by Laser heterodyne interferometer. We use a Bragg diffraction cell as the frequency shifter, PPLas the PM demodulater. The effect of space collimation on the signal-to-noise ratio and decreasing thedetection limit are discussed更多还原