Research On Key Technology Of Dynamic Mach-Zehnder Interferometer

Mach-Zehnder interferometers are extensively used in studies of gas flow,combustion,plasma density and wavefront of optical elements.At present,phase-shifting methods used in Mach-Zehnder interferometers are generally based on polarization phase-shifting technique,polarization state of polarization elements is difficult to accurately control,and residual stress of optical materials will introduce phase-shifting error into the results.In this paper,a non-polarization phase-shifting method based on the lateral displacement of a point source is studied,it is combined with Mach-Zehnder interferometer,and temporal phase-shifting measurements and dynamic measurements are realized.A phase-shifting method that based on the lateral displacement of a point source is proposed.The traditional Mach-Zehnder interferometer is of equal optical path.In order to meet the requirement of the proposed phase-shifting method,a retarder,such as a parallel plate and a right-angle prism,is introduced into the test arm,which increases the optical path difference(OPD).For the characteristic of transmission,studies in the relationship between the lateral displacement of the point source and OPD are done,and the influence on the phase shift is given.To realize instantaneous phase shift,a point source array is constructed with four point sources,and simultaneous phase shift is introduced by the different lateral displacements of each point sources.A temporal phase-shifting Mach-Zehnder interferometer is studied,which is based on the phase-shifting method of the lateral displacement of a point source.Through the transmission of phase shifter,the small angle deflection of a reflector is used to replace the lateral displacement of a point source,which simplifies the phase shifting system.By selecting the appropriate thickness and tilt angle of the parallel plate,fast cycle phase shift and system accuracy can be guaranteed.In order to suppress the phase shift error introduced by vibration,an iterative algorithm using least-squares techniques to solve linear regression is studied,where the traditional phase shifting interference model is optimized.The phase is retrieved by the iterative algorithm and least-squares techniques.Experiments verify the accuracy and reliability of the temporal phase-shifting Mach-Zehnder,and the effectiveness of the algorithm,where the transmitted wavefront of a laser rod is measured.A spatial phase-shifting dynamic Mach-Zehnder interferometer is studied,which is based on the instantaneous phase-shifting method of the lateral displacement of a point source array.A spatial split imaging system based on a lens array is designed,which realizes that four spatially separated and clearly imaging simultaneous phase-shifting interferograms can be captured in a single shot.Experiments of measuring static wavefront and real-time flow are carried out,which verify the correctness and ability in dynamic measurement of the proposed dynamic Mach-Zehnder interferometer respectively.The system error and influences of key elements are analyzed,and selection range of parameters of the key elements is given quantitatively.The advantages of single transmission of Mach-Zehnder interferometers are analyzed,which are obvious in measurements of small aperture.