Technology Of Nonlinearity Correction At Original Position And Adaptive Interference Light Intensity In Homodyne Laser Interferometer

Homodyne laser interferometry has many advantages in vibration measurement because of its advantages such as optical fiber transmission,easy integration and easy traceability of measurement results.In recent years,with the homodyne laser interferometry method of continuous application of the field of expansion,the diversity of the measured object makes the measurement of the surface reflectivity is very different,while the measured vibration of the form of high-frequency micro-vibration and low-frequency large amplitude Vibration in both directions at the same time,which requires homodyne laser interference vibration technology toward the broadband,reflectivity adaptive direction,and put forward high precision,high resolution,high measurement speed measurement needs.In this paper,the nonlinearity correction at original position and interference light intensity adaptive technology of homodyne laser interferometer are studied.On the one hand,the nonlinear error can not be corrected for homodyne laser measurement.The difference of measurement result is very different.Based on the online correction of nonlinear error,a nonlinearity correction at original position technique for micro vibration measurement is proposed,which solves the problem that the measurement result changes with the nonlinear error and realizes the high precision measurement of the system under different vibration.On the other hand,in this paper,a method of measuring light intensity adaptive is proposed,which is different from the field of homodyne laser measurement,which leads to different reflectivity of measurement surface,different application system laser power and remote light intensity loss.To achieve a high resolution,high signal to noise ratio,high precision measurement.At the same time,due to the integration,product application requirements,developed an integrated interferometer optical platform and signal processing card.The main contents of this paper are as follows:On the basis of the existing research contents,namely,the ultra-precision homodyne laser interferometry on-line nonlinear correction key technology,the non-linear error can not be corrected for the homodyne laser measurement,which causes the measurement result to be very different.This paper analyzes the influence of nonlinear error under different measurement vibration,and points out the shortcomings of the traditional nonlinear error online correction technique.Based on the on-line correction of the original periodic nonlinear error,a nonlinearity correction scheme at original position for micro vibration measurement is proposed.At the same time,ANSYS software is used to simulate the mechanical structure,and the feasibility of the experimental scheme is verified.Finally,the design of nonlinearity correction at original position technique,the implementation of excitation drive and the signal processing of nonlinearity correction at original position are realized,and the wide range measurement of the system under different vibration is realized.Aiming at the problem that the reflectivity of the measured surface is different,the laser power of different application system is different and the loss of long-term light intensity is different for the homodyne laser measurement object.In this paper,the method of interferometric light intensity adaptation is proposed,Adaptive homodyne interference signal processing system.For the adaptive circuit,on the one hand,because of the problem that the design of the adaptive circuit loop stabilization time changes with the input signal lead to adaptive adjustment time inconsistency that can not determine the control time,it put forward an index control algorithm,and MATLAB software to its algorithm The simulation results show that the algorithm is correct and the stability of the control loop is constant.On the other hand,for the problem that the adaptive single threshold threshold is easy to make the system oscillate,a double threshold threshold adjustment method is proposed to ensure the stability of the control system.To achieve high resolution system,high signal to noise ratio.Aiming at the nonlinear in a nonlinearity correction at original position scheme,the interferometer optical platform is redesigned and built to realize the miniaturization and integration of the system.Aiming at the interference light intensity adaptive technology,the signal processing card corresponding to the homodyne interferometer is developed to realize the high speed acquisition as well as high-precision measurements.Finally,on the basis of the above research,this paper designs and develops a single frequency laser interferometer system.The experimental results show that the amplitude of the single frequency laser interferometer can be measured below ?/316 and the residual nonlinearity error is less than ±2nm(??/126)under the slight vibration.Adaptive module processing card dynamic measurement range of 0~20dB,the maximum measurement speed of 1.58m/s,displacement data update rate of 40 MHz.The results of the system test show that the adaptive SNR is greatly increased at different reflectivities,and the maximum adaptive signal-to-noise ratio is increased by 40 dB and the measurable range is 0.05% ~100%.In the 400 Hz below the vibration,the non-linear relative error within ± 0.6%.