| Laser has been applied in many precision machinery industry sectors,including precision manufacturing and precision measurement because of a series of significant characteristics and advantages.But there are still many interference factors in the practical processing of laser applications.The main interfering factors include the thermal deformation of the inner structure of the laser,the change of the air refractive index,and the interference of atmospheric turbulence.This study focuses on improving the stability of laser precision measurement because of that laser beam jitter caused by air disturbance is the main cause of measurement uncertainty,Based on the random characteristics of laser beam jitter,this study firstly used the time series analysis method to design the ARMA filter to filter the laser beam jitter passively.Secondly,the PZT micro-displacement actuator was used to design the optical path terminal feedback measurement method for laser beam jitter.Finally,experimental verification showed the stability of the measured results has been improved to a large extent through.The causes of laser beam jitter and the error modes caused by jitter were analyzed firstly in this paper,and the influence factor of atmospheric turbulence was elaborated in detail.The separation and detection of laser beam drift and angular drift are studied based on the detection principle of four-quadrant detector.A new method with feedback measurement was designed based on the realization of the four-degree-of-freedom error measurement.Then,this study used the time series analysis method to analyze the drift data of laser measurement considering the random characteristics of laser beam jitter.The ARMA filter was designed by mathematical operation based on the general theory model,and the corresponding MATLAB algorithm was developed.The program performed filtering simulation on the existing laser drift data,and the simulation results showed a good suppression effect.A laser straightness measurement platform was built to perform real-time filtering experiments.The experimental results showed that the filter can reduce the measurement uncertainty of laser measurement by about 20%.Finally,based on the four-degree-of-freedom measurement principle and the PZT feedback actuator,a 4m optical path terminal feedback measurement optical path was built.In order to verify the feedback effect,verification experiments were carried out at 0.5m,1.0m,1.5m,2.0m,2.5m,3.0m and 3.5m in the entire optical path.Because of the unequal trend drift of the drift data,the data was subjected to trend removal measures and the uncertainty of the data was calculated.The results showed that the uncertainty of laser measurement can be greatly reduced by feedback compensation. |
