Research On High-resolution Laser Self-mixing Measurement System

Since the 21st century,nanotechnology has become one of the most important technologies besides biotechnology and optoelectronics,which has been listed as a strategic basic research project by the developed countries.As an important part of nanotechnology,nanometer measurement technology plays a decisive role in precision processing,aerospace defense and other fields.In recent years,laser self-mixing interference has rapidly emerged in the field of laser measurement due to its advantages of compact structure,low cost,easy alignment and high precision.Laser self-mixing interference technology has been extensively studied by domestic and foreign researchers.It has been developed into a new type sensor measurement method of high-resolution,high-precision,which has been widely used in the fields of displacement,vibration,speed,and biomedicine.Focusing on the self-mixing interference effect of semiconductor lasers,the thesis intends to carry out in-depth research on high-resolution and high-precision nano-scale micro-vibration measurement through the optimization of optical system design and signal processing analysis.Firstly,the development history and application research progress of laser self-mixing interference are summarized.Then,the thesis deduces the theory of semiconductor laser self-mixing interference based on the three-mirror cavity model.And the mathematical model of the system is established by detailed formula derivation.The effect of each parameter on the self-mixing signal is simulated and analyzed by MATALB math software.Besides,from the time domain and frequency domain,the displacement reconstruction methods of phase unwrapping and phase modulation has been analyzed and simulated theoretically.Based on this,the thesis proposes the even-power fast algorithm for time domain analysis of self-mixing fringes,which can greatly improve the accuracy of self-mixing fringes with the advantage of not adding any additional optical elements in the light path.This greatly expands the application of self-mixing technology in the field of nanometer measurement.In addition,the thesis also proposes a self-mixing signal spectrum analysis method based on multi-reflection technology,which realizes fast demodulation of the amplitude of external objects from the frequency domain.This method has the advantages of wide measurement range,fast acquisition amplitude and high measurement accuracy.Finally,the thesis also designed a large-scale fast real-time laser self-mixing sensor system based on Lab VIEW.The optical-mechanical-electrical integration system has the ability to perform real-time monitoring of nano-resolution vibration objects.The research work carried out in the thesis and the design of a large-scale fast real-time sensing system demonstrate the advantages of high-resolution and high-precision laser self-mixing measurement technology,and deepen the understanding of laser self-mixing interferometry technology.Moreover,to some extent,it promotes the application of laser self-mixing interference technology in the field of non-contact nanometer measurement.