变光外差为电外差的双频激光探测

演示一种双频激光位移探测系统,阐述光载波激光雷达的概念。由单块非平面环形腔固体激光器和声光调制器产生100MHz载波频率的双频激光束,作为探测光束,经过光路收发系统,探测位于电动导轨上目标的位移变化,信号处理部分采用高速光电探测器响应后信号的电子外差解调方式,位移量的获得通过高频锁相放大器解算参考光束与信号光束的相位差并计算获得。通过双频激光把光学外差探测变为了电子外差探测,系统重复误差小于3%。系统在利用无线电雷达信号处理方式的同时,保留了激光探测的优点,位移测量系统具有良好的重复性。

Laser Detection by Electronic Instead of Optical Using Two-Frequency Laser

A ranging system using two-frequency laser was demonstrated,and the lidar-radar system concept was introduced.The two-frequency coherent laser beam carrying 100 MHz radio beat frequency was obtained by a monolithic nonplanar ring single-frequency oscillator and an acousto-optical modulator,and used as a probe.Through the optical transmitting and collecting system,the displacement of the object mounted on a motorized translation stage was detected.In the signal processing,the electronic heterodyne demodulation method was adopted to deal with the signals received by high-speed photodiodes.The displacement was obtained by calculating the phase difference between reference and detection signal achieved by a high-frequency lock-in amplifier.The ranging system turns optical heterodyne into electronic heterodyne demodulation,and the repetition error is less than 3%.The system takes advantage of the signal processing technologies of radar,and meanwhile,maintains the advantages of laser detection.The ranging system provides a good repetition.