Research On Self-mixing Sensor System Of Multi-longitudinal Laser And A New Method For Measuring Feedback Factor

With the development of modern science and technology,the requirements for precise measurement of related physical quantities are increasing in many fields.As a precision measurement technique,self-mixing interference technology has a simple,compact and easy-to-align system structure and has been a large number of scholars extensively studied and applied to high-sensitivity and high-resolution optical non-contact measurement.Based on the self-mixing interference effect,this dissertation measured the feedback factor C in the self-mixing interference system,the free spectral range FSR of the semiconductor laser and the He-Ne laser,and the resonator temperature of the semiconductor laser and the ambient temperature of the external cavity.In the theoretical research,combining the L-K rate equation model,the three-mirror cavity model and the multi-longitudinal mode laser interferometric mixing model,the corresponding theoretical models of measuring feedback factor C,free spectral range FSR,laser cavity temperature and ambient temperature were proposed.Experimentally,a system for measuring the feedback factor C in the self-mixing interferometer system,the free spectral range FSR of the semiconductor laser and the He-Ne laser,and the temperature of the cavity of the semiconductor laser and the ambient temperature of the external cavity were built.The accurate measurement of the feedback factor C in the self-mixing interference system,the free spectral range FSR of the semiconductor laser and the He-Ne laser,and the cavity temperature of the semiconductor laser and the ambient temperature of the external cavity are realized.The measurement results and theoretical simulation results were compared and analyzed.The innovations of this paper mainly includes:1.A new method for measuring the feedback factor C in a self-mixing interference system using power hop difference is proposed,and a corresponding theoretical model of measuring C using power hop different is established and simulated.An experimental system for measuring C using power hop difference is set up.It realizes accurate measurement of the feedback factor C value in the self-mixing interference system,and further discusses and analyzes the experimental results.2.A novel method for measuring the free spectral range(FSR)of the laser based on the multi-longitudinal self-mixing effect is proposed.The theoretical model of measing FSR using laser self-mixing is established and simulated.An experimental system for measuring FSR of the semiconductor lasers and He-Ne lasers are respectively built.It realizes measurement of FSR in semiconductor lasers and He-Ne lasers,and makes in-depth studies on the phase delays of two-longitudinal mode interference signals and the applicable feedback levels for measurement.3.A new method for measuring the cavity temperature of a semiconductor laser and the ambient temperature of the cavity by using the multi-longitudinal mode self-mixing effect was proposed.The theoretical model of measing the cavity temperature of a semiconductor laser and the ambient temperature of the cavity is established.An experimental system for measuring the cavity temperature of the semiconductor laser and the ambient temperature of the external cavity is set up.It realizes accurate measurement of the cavity temperature of the semiconductor laser and the ambient temperature,and the accuracy of the measurement and sources of error are discussed and analyzed.