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三光路结构的调频连续波重采样测距方法
引用本文:张桐,曲兴华,张福民.三光路结构的调频连续波重采样测距方法[J].光谱学与光谱分析,2020(4):1007-1011.
作者姓名:张桐  曲兴华  张福民
作者单位:天津大学精密测试技术及仪器国家重点实验室
基金项目:国家自然科学基金项目(51675380);“光电测试技术”北京市重点实验室开放课题(GDKF2015007);国家重点研发计划项目(2018YFF0212702)资助。
摘    要:调频重采样是一种绝对测距技术。这种方法采用的光源波长随时间变化,形成一束宽光谱激光。激光在各时刻的波长通过辅助干涉装置进行测量,并对其中频率间隔相同的部分进行重采样,使调频测距系统具有较大的线性光谱带宽,较高的分辨率及精度。在实际测量过程中,测量装置本身及待测物都容易受到振动的影响,导致待测距离及辅助光纤长度发生变化,引入测距误差。针对这个问题,分析了振动对重采样测量结果产生的误差:(1)待测物的移动引入一个多普勒频移分量;(2)辅助光纤的振动使重采样频率也发生变化。为了弥补这两种误差,提出了一种三光路结构的补偿方法,在辅助光路中,使用一种光路结构简单小巧,且测量速度更快的全光纤马赫泽德干涉仪等效代替光谱仪,实时的监测信号光的瞬时频率。在测量光部分,在测量光路中引入两个部分反射镜产生两路补偿光信号,并通过FFT算法产生频谱。频谱的三个峰值分别与三路信号相对应。通过测量信号与其中一路补偿信号的峰值相减即可补偿多普勒误差,通过两路补偿信号的频率差与相对距离的比值即可得出实际的辅助光纤长度。实验证明,传统的重采样测距方法精度为23.6μm,三光路测距方法的精度可达到11μm,可见这种方法能够对系统的振动误差进行有效补偿。

关 键 词:调频连续波测距  激光雷达  激光干涉测距

The Slight Vibrations Compensation of FMCW Ranging Method Based on Three Light Paths Structure
ZHANG Tong,QU Xing-hua,ZHANG Fu-min.The Slight Vibrations Compensation of FMCW Ranging Method Based on Three Light Paths Structure[J].Spectroscopy and Spectral Analysis,2020(4):1007-1011.
Authors:ZHANG Tong  QU Xing-hua  ZHANG Fu-min
Institution:(State Key Laboratory of Precision Measurement Technology and Instrument,Tianjin University,Tianjin 300072,China)
Abstract:The re-sample frequency modulation technology is a kind of ranging method.The optical structure of this method has boarder frequency modulated bandwidth,higher spatial resolution and accuracy.However,in the processing of practice measurement,the re-sample measurement device and the object to be measured are easily disturbed by the vibration from the outside environment.This paper analyses the influence of the Doppler error and the re-sample frequency error from vibration.In order to compensate these errors from the two kinds of vibrations,we present a vibration compensation method based on three light paths structure,this method brings two partial reflectors on the measurement light path to produce two compensatory lights,and the Doppler error and the auxiliary fiber error can be reduced by the differential value of the measurement signal and the compensation signals.The experiment verifies that the ranging accuracy of the typical re-sample method is 23.6μm,and the ranging accuracy of the three-light-paths ranging method can achieve to 11μm.It is proved that the three-light-paths ranging method can effectively compensate the vibration error of the measurement system.
Keywords:Frequency modulation continous wave ranging  Laser radar  Laser interferometry ranging
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