基于二次强度调制的激光测距系统  

Laser ranging system based on double intensity modulation

作　　者：王菊 邵琦 于晋龙 何可瑞 罗浩 马闯 蔡滋恒 郑紫月 蔡奔 Wang Ju;Shao Qi;Yu Jin-Long;He Ke-Rui;Luo Hao;Ma Chuang;Cai Zi-Heng;Zheng Zi-Yue;Cai Ben(School of Electrical and Information Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学电气自动化与信息工程学院,天津300072

出　　处：《物理学报》2023年第22期93-101,共9页Acta Physica Sinica

基　　金：国家自然科学基金青年科学基金(批准号:62005194)资助的课题。

摘　　要：本文提出的二次强度调制测距系统可以实现绝对距离的测量,其利用马赫曾德尔强度调制器代替二次偏振调制测距中的电光相位调制器,通过对信号的光强进行二次调制来进行测距.相比于二次偏振调制测距,二次强度调制测距无需考虑测距系统中的偏振态问题,简化了系统结构,提高了系统的稳定性.经过相关理论推导以及实验验证:二次强度调制测距系统的输出光强与调制频率成余弦关系,并且可以直接测量调制器到目标物体之间的绝对距离,系统的频率稳定度、相对测距精度皆达到10^(-7)量级.本文提出的测距系统量程达到100 m,相对测距精度稳定在10^(-7)量级.采用摇摆法快速测距,避免了直接扫频寻找光强极小值点对应的频率,数据刷新率达到2 kHz.二次强度调制测距系统测距速度快,同时兼顾了较大的量程与较好的测距精度,系统结构简单,易于搭建,具有广阔的应用前景.Long-range,high-precision,and high-refresh rate absolute distance measurement based on double intensity modulation is proposed and experimentally demonstrated.In this scheme,a Mach-Zehnder modulator is utilized to perform bidirectional modulation by a reversible optical path.In the Mach-Zehnder modulator,interference demodulation is completed by bidirectional modulated light with time difference.By adjusting the driving frequency of the modulator,the curve of light intensity versus driving frequency is achieved.Consequently,the distance to be measured can be obtained by extracted the frequency interval between two adjacent light intensity minimum points.In the traditional double polarization modulation ranging,the optical carrier is polarized by a polarizing beam splitter(PBS)before phase modulator.Moreover,a quarter wave or Faraday rotating mirror need to be placed to adjust the polarization in front of the target object.Therefore,the polarization state is an indispensable factor in the traditional double polarization modulation ranging.Due to the advantage of the intensity modulation,absolute distance measurement is achieved without additional polarization control,greatly simplifying the system.Theoretical analysis of the system is developed,which is then demonstrated by experiments.In the experiments,we achieved the following results.Firstly,the relationship between the intensity of the output light of the system and the modulation frequency is theoretically analyzed,which proved to be a cosine form.Secondly,swing method is introduced to realize high-speed absolute distance measurement during the analytical distance algorithm,and we achieved a refresh rate of 2 kHz in the experiments.Thirdly,the relationship between measurement ranging precision and frequency stability is analyzed.When the modulation frequency is 8.9 GHz,the experimentally measured frequency stability is on the order of 10^(-7).And when the distance to be measured is 2.73 m,the standard deviation of ranging reaches 1μm,which represents the pr

关 键 词：激光测距 变频测距 二次强度调制 

分 类 号：TN249[电子电信—物理电子学]