Phase Shift Interferometer Simulation Analysis And Modular Design Research

Phase-shift interferometer is an optical measuring instrument based on four-step phase-shifting measurement.With decades of development,it will soon be included in the new flatness measuring standards.This article is based on phase-shift interferometer,we design a flatness measurement system for precision optics.The system replaces the tandem interferometer and the equal thickness interferometer used in conventional flat crystal metering,improve the sampling accuracy while maintaining the original sampling index,ensure the versatility of measurement and advanced.In the designing process of metrological phase shift interferometer,we introduce a method called modular design.We divide the hardware and software into several modules according to different functions,each module corresponds to a specific requirement.In the whole system,we mainly study the testing module of hardware part and the image processing module of software part,calculate the flatness data of tesing components in the original measurement standard,prove that compatibility of phase-shifting interference with traditional measurement methods.In this paper,we use optical modeling software ’TRED’ to complete simulation and analysis of parts of module’s in the measurement of phase-shift interferometer We established the optical path model according to the basic parameters of the interferometer,select specified coherent light for tracing and testing,discuss the scattering light’s distribution inside the system.Model zoom module by the lens parameters,analysis the influence of image with different reflectivity of prism in the splitter module,compare the relationship between the hotspots of pairing point module and the scattered light,prove the feasibility of test module.After measuring the flatness of the flattened and polished surfaces using metrological interferometer,we calculate the flatness of each element under the condition of phase shift interference.Measure the flat crystal using absolute inspection method of three sides mutual inspection;compare the results of directing measurement and built-in program,come up with a well-fitted conclusion;use two kinds of methods for tilting measurement and image splicing measurement,come up with the conclusion that the flatness of polished surface is 0.30 μm by tilt measurement,0.379lμm by image stitching measurement,the measuring result shows that the data deviation is small,this polished surface is fulfill the measuring requirement.