Multi Wavelength Surface Topography Measurement System Based On Linnik And Its Software Design

The continuous change of the direction of integration with the fineness,automation,wide function of the high precision instruments combined with light,computer and electronics,In the field of modern precision manufacturing detection,the quality requirement and the accuracy requirement is higher and higher.The interference microscopy in non-contact surface topography measurement has many advantages,such as high speed,high accuracy and nondestructive testing.It has been widely applied in surface profile measurement.Single wave length interferometry with high precision but limited range of measurement and low precision of dual wavelength interferometry,In this paper,a method of combining three wavelengths with wavelength rotation and phase shift is proposed and a multi wavelength surface morphology micro interference measurement system is designed.At the same time,based on the VC++ language platform to develop software for measuring system,the specific work contents are as follows.First,the methods used to measure the profile of surface topography are described in this paper,The basic principle of optical measurement is emphatically analyzed.On this basis,the method of surface topography interferometry with the combination of three wavelength rotation and phase shift scanning is analyzed.Second,the multi wavelength topography measurement system is designed and the design of each sub module is described in detail.Designing the phase shift interferometry and micro measurement module driving unit and optical interferometry.Using ZEMAX software to Simulate the LINNIK multi wavelength micro interferon metric optical path.Selecting the model of white light source,filter and piezoelectric ceramic PZT.The scanning and positioning module composed of two dimensional translation table and grating ruler is designed and the hardware selection is chosen,and the image acquisition system module is designed.Third,a method of wavelength calibration in multi wavelength profile measurement system is proposed.The specific process of the methods are as follows: after obtaining the initial phase from the relative phase calculation,we deduce the absolute height of the pixel series,and get the relation between the height and wavelength of the measured surface accordingly.Finally,we get the calibration equation by fitting the equation.A mosaic algorithm based on ICP algorithm combined with kd-tree is proposed to solve the problem of slow point correspondences in the traditional ICP algorithm when the number of point clouds is large.Fourth,based on Windows XP/7 as the development environment,Microsoft Visual studio C++ as the development platform,we have developed two dimensional translation platform positioning control,wavelength conversion control,interference image acquisition,data processing,3D shape display and other functions of the system software.Finally,the functional integrity of the software designed by measuring the sine wave template is measured,and the results show that the designed software can complete the specified function.The feasibility of the designed system is tested by measuring the square wave sample which passes through the test roughness.The results show that the relative error of measurement results is only 4.1% compared with the Ra value of China Metro-logy Institute,which proves that the designed profile and profile measurement system can measure its morphology with high accuracy.