Research On Absolute Testing Technology Of Standard Plane Based On Multi-flat Mutual Inspection

The large-aperture plane optical element has been widely used in the field of science and technology,its surface shape is often measured by the interferometry technique with high-precision.The Fizeau interferometer is a typical interferometer,which detection accuracy is mainly determined by the surface shape accuracy of the standard mirror of the interferometer.When the surface shape accuracy of the optical element under testing reaches the same level as the standard flat surface,the influence of the surface shape error of the standard mirror flat on the measurement results cannot be ignored.With the increasing of diameter of the optical element,the deformation of the standard mirror flat clamping has a great impact on the accuracy of testing.In order to obtain higher testing accuracy,the system error of the interferometer must be compensated.The surface shape error of the standard mirror flat is obtained by the absolute testing technology,the clamping deformation of the standard flat is analyzed by the finite element method,finally the influence of shape error of the standard mirror flat and deformation on the measurement result is eliminated.The theoretical analyses are firstly performed,including the Zernike polynomial fitting method,odd and even function method and N time of rotation method;The simulation compares the detection accuracy of these three methods,and using the N time of rotation method as the target algorithm;the influence of the number of rotations and surface accuracy on the simulation calculation of N time of rotation method is analyzed.Secondly,the finite element method is used to simulate the deformation of the 320 mm standard mirror in different clamping methods.The clamping deformation caused by different number and different sizes of glue points are analyzed in terms of clamping method of side glue point support,and the theoretical results of clamping deformation are obtained.Thirdly,the influence of clamping deformation on the simulation results of the N-rotation method is analyzed,and a system error compensation method in the large-diameter plane interferometric measurement process is proposed.Finally,the experiment of large-caliber interferometer is designed.In this experiment,N time of rotation absolute texting is used on a 320 mm standard flat to obtain the clamping deformation of the standard mirror flat and complete the clamping deformation compensation.The deviation of the residual surface PV value of the 320 mm standard flat measurement result is less than 3.34 nm.This paper using theoretical derivation,simulation analysis and experiment measurement,N time of rotation absolute texting and clamping deformation compensation is verified,which provides a basis method and data support for large-diameter and high-precision optical component surface interference testing.