激光多普勒测速中连续波调频非线性的分析与校正

Analysis and rectification of nonlinearity in frequency sweep of laser Doppler velocity measurement

基于多普勒效应的线性调频激光测速系统的原理是:激光照射到运动目标,引起光束频率发生改变,返回的光束与本振光进行相干混频后得到多普勒频移,进而可以推算出目标的相对运动速度值,但调频的非线性严重影响了测量结果的准确性。仿真分析了调频非线性对测量的影响,调频非线性会使混频后频移产生误差,造成速度测量不准,并且影响速度极性的判断,验证了激光调频线性度对测速有很大影响的结论,并对校正调频非线性提出了可行的方法,完成了调频线性化的矫正,降低了系统测量误差。

In laser Doppler velocity measurement system based on linear frequency sweep mode, laser irradiates the moving target, which causes the change in laser frequency, the change is called Doppler frequency offset. Doppler frequency offset can be obtained from the mixture of the local vibration of laser and the returned laser from the target, and then the velocity can be calculated based on the offset. However, the nonlinearity in frequency sweep deeply impacts the accuracy of velocity measture. First, the effects of the nonlinearity in frequency sweep was simulated, the nonlinearity in frequency sweep could deeply affect the accuracy of the velocity measurement and caused the error of polarity, the effect was velificated. And a method was proposed to correct the nonlinearity and it was verified through the experiment. This will improve the the accuracy and reduce the error in laser Doppler velocity measurement.