Nonlinear Error Detection Of Length Measurement By Laser Polarization Interferometry

Length and displacement are important physical quantities in the field of science and technology.With the progress and development of science and technology,the precision and accuracy of displacement measurement are required to be higher and higher in various fields such as aerospace,precision machinery manufacturing and processing,and nanotechnology industrial equipment.Among the various methods of displacement measurement,laser measurement is widely used in various fields because of its non-contact characteristics,fast measurement speed and traceability.Compared with heterodyne interferometer,the homodyne interferometer has the characteristics of simple signal processing,integration easily and system structure simply under the condition of high precision and high resolution.Based on the basic principle of Michelson interference,this system adopts the method of polarization state to design the optical path,and designs a method to detect displacement and displacement nonlinear error,which is verified by experiments.The main work of this paper is summarized as follows:(1)The basic principle of laser interference length measurement is introduced,and the optical path of the experimental system is perfected.The clamping part of the driving structure of the measuring mirror is designed,so that the measuring mirror can move with the fluctuation of the given voltage.(2)The hardware circuit design of laser interference length measurement system is completed.A charge driving circuit is designed to drive piezoelectric ceramics.The photoelectric conversion circuit and post-processing circuit are designed to reduce the DC bias error and unequal amplitude error of four optical signals.(3)The software program design of laser interference length measurement system is completed.Using Lab VIEW to compile the software program,the functions of data acquisition,displacement calculation,displacement error calculation and displacement error analysis are realized.(4)The nonlinear error measurement experiment of laser interference length measurement is carried out.Different displacement values caused by different input signals are calculated.The calculation of nonlinear error of measurement system is completed.The nonlinear error analysis of the measurement system is completed.The experimental results show that the nonlinear errors in the laser interference length measurement system mainly include Single frequency error and Double frequency error.Among them,the double frequency error is almost constant under the condition of constant measurement conditions.However,the single frequency error will fluctuate irregularly in a certain range.