Development And Application Of A Calibration System Used For Laser Transverse Deformation Measure Based On Knifeedge Method

The calibration system in a laser transverse deformation measure instrument provides the fundamental precision reference for measured material deformations,the calibration precision determines the accuracy of the laser instrument in deformation measurements.When the knife edge of simulating the transverse deformation of the material is used to cut the homogenized rectangular laser,the energy of the laser to the photodetector will change linearly,and the output voltage signal will also change linearly.By setting the transverse deformation of blade motion simulation material displacement and corresponding linear relationship between the size of the output voltage signal the deformation measurement calibration,and the corresponding linear relationship is also considered a sign of speckle intensity smoothing,cognizance is the precondition of blade displacement is accurate and laser is rectangular homogenization is good,but such acknowledgment has great randomness,lack of the basis of scientific testing.It is imperative to detect the accuracy of the blade motion,and it can also indirectly confirm the degree of laser homogenization.Therefore,the work of this paper is to test and optimize the motion precision of the knife edge.The encoder mode of STM32 industrial computer is used to collect the grating ruler signal connected to the knife edge in a custom time period,and directly measure the linear velocity and linear displacement of the knife edge moving in any time period.In this way,the uniformity of the blade moving speed is detected,and the motion accuracy of the system is detected by two kinds of motion states: displacement of equal step length and linear motion of uniform speed,and a variety of measurement methods.The experimental results show that the accuracy of the laser deformation measurement calibration system has different degrees of errors.The displacement error can be reflected in the measurement of the shape variable of the material as the calibration system.The results of several tests show that the maximum displacement error is more than 17?m in a single displacement of 2000?m,and the relative error is less than 0.418%in the range of 31 mm stroke.In the equistep displacement measurement,the equistep displacement error within 90?m is measured by timing sampling method.The maximum displacement error reaches 18?m after the motor runs smoothly,and the relative error is more than 20%.There is still a certain gap between the calibration system and the transverse deformation of the material.Velocity error will show in the blade deformation error of the dynamic process simulation material,with the increase of blade speed relative error also increase,blade under the speed of 2.5 mm/s maximum relative error of 18.667%,platform vibration is larger,the error measurement and calibration system no matter in the step length displacement or velocity measurement,the motion state of the whole process has obvious oscillation,step motor at the start and stop when there is an obvious step and overshoot,the calibration system has great effect on the dynamic process of reaction materials,and further analyzes the error sources,According to the above detection results and error source analysis to improve and optimize.The improving direction and content of the moving part of the laser lateral deformation calibration system are analyzed and studied in depth.The main purpose of the improved and optimized equipment is to improve the positioning accuracy;The new movement platform is built on the marble with high levelness.The traditional mechanical transmission mode is still adopted.The moving part is composed of high-performance PLC,position control unit,driver and servo motor,and the closed-loop control is realized with the 23-bit absolute encoder.Laser interferometer is used as standard to detect the positioning accuracy of moving platform.After the improvement and optimization,the vibration of the system is greatly reduced,the dynamic performance of the blade movement is significantly improved,and the error within a single 500 micron stroke is reduced from 50 microns to less than 2 microns,and the positioning accuracy is significantly improved.The precision of grating ruler and lead screw is tested with the existing equipment,and the main source of error is analyzed.The shortcomings of the improved and optimized system and the future development direction are put forward,which greatly promotes the development of the laser lateral deformation measurement and calibration system...