Design And Application Of Ring Source Of Fizeau Interference System

As an important part of precision optical measurement,interferometry,is widely used in national defense,aerospace,astronomical observation and other fields,but due to the highly coherent nature of laser sources,the coherent noise generated by surface defects and tiny particles of optical elements in the system can introduce measurement errors,so it is especially important to suppress coherent noise in precision optical measurement system.In this dissertation,design a virtual ring source generated by the rotating optical wedge for Fizeau interferometer to achieve the suppression of coherent noise,and the main work includes:(1)Based on the Van Cittert-Zernike theorem to analyse the spatial complex coherence and study the spatial coherence of ring source.Based on the off-axis point source interferometer imaging system,a system model is established to analyze the principle of ring source for coherent noise suppression,and the relevant structural parameters of the ring source is discussed.(2)A virtual ring source generated by rotating optical wedge is designed for the typical Fizeau interferometer.A simulation model is established to compare and analyze the effects of different wedge angles on wavefront error,suppressible defect cycle radius and off-axis amount,and the optical wedge angle is determined to be 1°56′.(3)Simulation to establish a virtual ring source mode Fizeau interferometer,set up noise points and coherent noise sources at different locations in the system,respectively compare the point source and virtual ring source mode interference fringe contrast,vertical stripe direction normalized light intensity distribution,establish a model to evaluate the virtual ring source mode noise points,coherent noise suppression effect,the highest noise suppression rate of 13.23%.The simulation results show that the virtual ring source can effectively suppress the coherent noise in the system,while maintaining the interference fringe contrast.(4)Experimentally set up the virtual ring source mode Fizeau interferometer,fixed exposure time 40 ms,compare the fringe contrast,vertical stripe direction normalized light intensity distribution and its corresponding root mean square at different speeds,determine the best speed is 3000r/min,its noise suppression rate reached 34.93%.The experimental results show that the virtual ring source mode can effectively suppress the coherent noise in the system while maintaining the interference fringe contrast.