基于希尔伯特变换的激光自混合信号处理方法  

Laser Self-Mixing Interference Signal Processing Method Based on Hilbert Transform

作　　者：王雨宁 王汉睦 冯艺聪 周健[1,2] 聂晓明 Wang Yuning;Wang Hanmu;Feng Yicong;Zhou Jian;Nie Xiaoming(College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,Hunan,China;Nanhu Laser Laboratory,National University of Defense Technology,Changsha 410073,Hunan,China)

机构地区：[1]国防科技大学前沿交叉学科学院,湖南长沙410073 [2]国防科技大学南湖之光实验室,湖南长沙410073

出　　处：《光学学报》2024年第19期212-221,共10页Acta Optica Sinica

基　　金：湖南省自然科学基金(2021JJ30782)。

摘　　要：针对自混合电光调制系统中的谐波信号提取问题,提出了一种新的基于希尔伯特变换的自混合信号处理方法。直接将电光调制信号的一倍频、二倍频与自混合功率信号进行混频,提取一阶与二阶谐波,并基于希尔伯特变换对提取的谐波进行归一化处理,以消除额外的比例系数,提高系统测量精度。基于混频的基本机理,分析了谐波振幅不对称性原因,通过仿真得到了谐波振幅不一致对测量结果的影响,并对基于希尔伯特变换的归一化方法进行了理论解释,之后搭建了激光自混合测振装置。实验结果表明,归一化后装置的标准差减小了30%。Objective Self-mixing interference(SMI)is a novel optical measurement technique that utilizes the light reflected back into the laser cavity.Due to the interaction between the feedback light and the medium in the cavity,SMI has high sensitivity.It can obtain high quality signals for targets with rough surfaces without the need for additional target mirrors.SMI also features high resolution,low cost,and compactness,making it widely used in sensing applications.The effective signal of SMI is related to the phase of the laser,so phase demodulation is particularly important.Recently,researchers have used electro-optic crystals and mixers for orthogonal phase demodulation,which can eliminate baseline noise,simplify the algorithm,and increase the measurement speed.However,this method requires the orthogonal signal of the electro-optic modulation signal.Due to the high-frequency nature of electro-optic signals,it is difficult to construct the orthogonal signal.This method does not consider the influence of the initial phase on the harmonic amplitude,while the variation of the harmonic amplitudes can lead to a decrease in accuracy.To address the challenge of constructing orthogonal signals and to solve the problem of random fluctuations in harmonic amplitudes,we propose a new signal processing method based on the Hilbert transform,which can simultaneously simplify the system and improve measurement accuracy.Methods First,the basic SMI model and the fundamental principle of electro-optic modulation are introduced.Subsequently,based on the principle of heterodyning,the reason for the inconsistency in the amplitudes of the two harmonics is discussed,and the influence of this inconsistency on the measurement variance is analyzed by numerical simulation.Then,a self-mixing interference electro-optic modulation device is constructed using a 532 nm solid-state laser,a 251 kHz resonant electro-optic phase modulator,and a photodetector.The laser beam is irradiated onto an aluminum reflector mounted on a piezoelectric transducer(PZ

关 键 词：自混合干涉 希尔伯特变换 电光调制 正交解调 

分 类 号：O436[机械工程—光学工程]