Application Research Of Surface Recovery Algorithm Based On Carrier Method And Phase Shift Method In Multi-surface Interferometry

With the development of technology,the application of ultra-smooth surface materials has become more and more extensive,and the requirements for accurate measurement of the shape of transparent ultra-smooth surface elements have also increased.When measuring the optical components of a transparent parallel plate,a phenomenon of multi-surface interference superposition is usually generated,and the conventional interferometry technique is difficult to simultaneously measure the front and back surface shapes of the transparent element.Therefore,the study of this subject is very important for measuring the shape of transparent optical components.This paper studies the carrier Fourier transform algorithm and the least squares iterative phase shift algorithm,and studies the methods of solving the two surfaces of the front and back of the transparent optical element from both the space and time domain.The carrier Fourier transform algorithm only needs an interferogram to quickly find the surface shape.However,it is necessary to introduce a carrier to perform the Fourier transform on the carrier interferogram and extract the waveforms of each group of interference fringes in its frequency domain.After the inverse Fourier change,the front and back shapes of the measured transparent surface can be obtained,but the surface accuracy is not high.The least square iterative phase shift algorithm requires at least 7 interferograms with different phase shift amounts to solve the surface shape.First,the light intensity distribution formula with the initial phase shift value is used to perform the least squares to obtain the corresponding phase distribution.The phase distribution obtained is then brought into the light intensity distribution formula to obtain a phase shift value.After repeated iterative calculations in this way,the final phase shift value reaches the convergence condition and the iteration is ended.The obtained surface shape accuracy of the measured object is high,but Solving is slow.This paper uses the method of simulation to compare the accuracy gap between the two algorithms.In order to verify the feasibility of the above two algorithms,a Taiman Green interference system was built,and a multi-surface interference fringe pattern was acquired,and the Fourier transform was performed using the interferogram to obtain a spectrogram.Using ZYGO interferometer and domestic self-made interferometer to obtain interference fringe pattern with different phase shift amount,using carrier Fourier transform algorithm and least squares iterative phase shift algorithm to obtain the surface phase distribution map of the measured component,and the result and interference The comparison of the surface results obtained by the instrument confirms that the algorithm of this paper is credible and basically meets the accuracy requirements of optical components.