Based On Self-mixing Interference Displacement Measurement

Self-mixing Interference (SMI) technology arose some years ago. The system based on SMI has high sensitivity, precision and is non-invasive which are the advantages of traditional interference technology. Additionally the structure is simple and compact self-aligning as well as cheap. Self-mixing Feedback Interference is a solution to the problems of complexity, large size, costliness and sensitive alignment which are disadvantage of conventional interferometers.The ascendancy of SMI technology just consists in the measurement of geometric sense. And the measurement of displacement is an important part of geometric sense measurement.The development of Self-mixing Interference technology and its application have been elaborated. The method of displacement measurement based on Self-mixing Interference was briefly introduced. Then the basic theory model of self-mixing effect which is based on the Long and Kobayashi equations and the three-mirror cavity approach respectively is described. The main emphasis of research is the method based on Fast Fourier Transform (FFT) and fringe count.In accordance with the actual conditions a displacement measurement system was designed based on the method of fringe count. The method of measurement and the algorithm of data processing were designed. System of measurement has been set up and debugged.The system can be used to measure arbitrary signal displacement. The minimal definition is less than the half wavelength of diode laser.