Research On High Sensitive Micro-displacement Measurement Technology Based On White Light And Laser Interference

Interferometry is a widely used precision measurement method.Depending on the light source used,there are mainly white light interference and laser interference.In the existing white light interference,the positioning of the zero optical path difference is not accurate enough,so that the measurement accuracy is difficult to meet the requirements of ultra-high precision micro-nano manufacturing.In this paper,a new type of high-sensitivity interferometric measurement system is designed based on white light homodyne interference and laser secondary interference.The main research contents of this article are as follows:Firstly,the basic principles,advantages and disadvantages of the current interferometric technology are analyzed,the existing white light interference and laser interference technologies are analyzed,and their respective advantages and disadvantages are summarized.On this basis,combining the basic principle of white light interference and the advantages of the second interference of laser,a new white light homodyne interferometry system is proposed to improve the sensitivity of the position of zero optical path difference.Secondly,based on the analysis of the white light micro-interference technology,the measurement principle of the highly sensitive interferometric measurement system is introduced,and the characteristics and influencing factors of the white light interference signal and the laser interference signal are analyzed.The expression of white light interference light field and the effect of coherence length and noise on the interference signal are derived theoretically.The expression of laser homodyne interference light intensity is derived using Jones matrix.The process of fusion analysis using white light interference and laser interference signals is elaborated to improve the measurement sensitivity,and Matlab simulation is carried out.The simulation results show that the sensitivity of various types of interferometric measurement systems is significantly improved compared to white light interference systems.Thirdly,according to the signal characteristics of white light interference and laser secondary interference,an appropriate light source,dielectric mirror and micro-displacement generating device(PZT)were selected,a phase shift driving method and a signal receiving circuit were designed,and an experimental system was built.Finally,the experimental platform built was used for experimental verification.In order to achieve the best results of the experiment,the reference mirror of the interference optical path was driven by PZT,and the interference signals of white homodyne interference and laser secondary interference were collected by the detector respectively.It can be found that the zero optical path difference position of the white light corresponds to the zero position of the laser,and the zero difference position of the white light can be locked by the zero position of the laser.Through the processing and analysis of the collected data,it is found that the sensitivity of the measurement method proposed in this paper is at least 12 times higher than that of white light interference,and the corresponding measurement accuracy reaches±0.406 nm,indicating that the measurement system has high sensitivity and high precision.