Research On The Surface Three-dimensional Topography Detection System Based On White Light Interference

With the development of precision and ultra-precision machining,the quality of the parts surface is getting higher and higher,and the requirements of three-dimensional shape measurement of surface are stricter.White light scanning interferometry has become an important developing direction of ultra-precision measurement with its characteristics of high accuracy,high speed,wide range and non-contact.In the paper,a three-dimensional shape inspection system for surface of precision device was developed based on white light interferometry.Firstly,the theory and method of white light scanning interferometry were studied,different types of algorithms for extracting coherent peak from white light interference signal were researched and simulated and the effects caused by noise disturbance and scanning error were analyzed.The improved white light phase shift interference algorithm with high accuracy and high speed is determined after comparative analysis.Secondly,the hardware design of the system was completed by the research and parts selection of light source,optical interference system,phase-shifting system,three-dimensional workbench and image acquisition system.Among them,the voltage and displacement curve of the piezoelectric was strictly calibrated and fitted,the working range with high linearity was selected and the driving voltage was controlled according to the preset displacement,so,the nonlinear error of the phase shifter was effectively reduced.Flexible structure was designed to improve the reliability of phase-shifting system.Then,by using C++ language,the software of the system was developed to realize the control of drive signal,image acquisition and processing,evaluation of parameters and reconstruction of three-dimensional topography.With OpenGL,topographic results achieved better visualization.Finally,repeated tests were performed by the standard single-stencil sample with a nominal height of 1.35?m,the relative error of indication and the relative repeatability error were 0.72%and 1.39%respectively.The horizontal and vertical range of the system were 100mm× 100mm and 13?m respectively,the horizontal and vertical resolution were 1.11?m and 0.53nm respectively.The surface of precision machining device was tested by the developed system and the results verified the reliability and practicability of the system.