Research On Dynamic Fizeau Interferometer Based On Optical Spatial Split And Its Key Techniques

Dynamic interferometry is an important technology in optical interferometry.It solves the difficulty of conducting high-accuracy measurement under unstable environment by temporal phase-shifting Interferometry.As an important method in dynamic interferometry,the simultaneous phase-shifting interferometry has been widely used in the aspect of high precision phase measurement.In order to eliminate errors of temporal phase-shifting,the simultaneous phase-shifting interferometry recovers the phase to be measured by multiple phase-shifting interferograms obtained at the same time.In order to achieve instantaneous phase-shifting,most of the instantaneous phase-shifting schemes conduct the phase-shifting process in the spatial dimension and a variety of instantaneous phase-shifting methods have been carried out.This paper focuses on the research of instantaneous phase-shifting interferometry based on optical spatial split,and the main work includes:Firstly,a dynamic Fizeau interferometer based on optical spatial split has been proposed.The principle of phase-shifting introduced by the lateral displacement of the point source has been researched and changing the offset of the light source in the direction of the vertical axis of the interferometer can introduce phase shift between reference wavefront and testing wavefront in Fizeau interferometer.Equal interval phase shift can be produced by different displacement of four point light sources in the direction of the vertical axis.Four phase shift interferograms are obtained instantaneously with an imaging lens array and the dynamic measurement is realized.Secondly,the instantaneous phase-shifting dynamic Fizeau interferometer based on optical spatial split and its key technology are researched.In order to obtain a high quality point light source array,the grating light source system and the optical fiber light source system are designed and made.A synchronous imaging system based on the imaging lens array is developed,and clear phase-shifting interferograms spatially separated are obtained.Thirdly,an absolute measurement method based on the dynamic Fizeau interferometer for the optical homogeneity was proposed.In order to verify the accuracy of the proposed method,the optical homogeneity of a parallel plate is measured.Compared with the results obtained by the wavelength tuning interferometer,the deviation of the peak-to-valley value is 5x10-7 and the deviation of the root-mean-square value is-7×10-9.The distribution of optical homogeneity is the same.Fourthly,the measurement errors of the interferometer are studied.Error sources in dynamic Fizeau interferometer are analyzed and suppressing method of errors is discussed.The errors introduced by the wavefront of the system is studied.The position matching error of instantaneous phase-shifting interferograms and the inconsistency of intensity of light sources are also studied and analyzed.