Researches Of Sensing Applications Based On Laser Self-mixing Interference Effect

As a new laser technique called,self-mixing interference(SMI),which is due to the interaction of cavity field with the field backscatter from the remote target,has gained widely attention.The SMI does not only have the same precision with traditional interferometry,but also have advantages of simple light path,easy collimation and high sensitivity.Therefore,the applications of the SMI have been popularized in many fields,including displacement metrology,vibration detection,velocimeter,biomedical signals sensing and laser parameters.In this article,we introduce the historical development and the research status of the SMI firstly.Then based on two kinds of mathematic models,we discuss the mechanism of the SMI operation.Besides,we analysis the influence of different parameters on the simulation results of the SMI.On this basis,the feasibility of phase unwrapping algorithm is verified by simulation using MATLAB,which would be prepared for subsequent experiments.Based on theoretical research of the SMI and simulation,we discuss respectively these applications for measurement precision improved,Pulse Wave Transit Time(PWTT)measurement,vibration and velocity measurement simultaneously:(1)based on the method of multiple reflection,analyzing the error in the SMI system,improving the precision to ?/40 in experiment and applying to measure the profile of pulse wave;(2)proposing a method of double-path acquisition of PWTT,studying the feasibility of applying to human body measurement and building the blood pressure fitting model;(3)designing the optical paths of vibration and velocity measurement simultaneously,discussing the feasibility of system by simulation,analyzing the demodulated information in time-frequency domain and deviations with different conditions.In conclusion,based on the contrastive demonstration in the terms of experiments and theories,the research work realizes the improvement of measuring precision,the sensing of human physiological signal,and the measurement of multiple physical parameters.Moreover,we have improved the system of the SMI and promoted the SMI as a non-invasive measuring method towards applications in different areas.