Research On Impact Of Mid And High Spatial Frequency Error To Signal To Noise Ratio Of Optical Surfaces

The high-resolution space telescope is the key to the study of the evolution of the universe,the search for terrestrial planets,and the detection of cosmic dust gas.With the development of optical processing technology,computer controlled optical surfacing(CCOS)technology has made the construction of large-aperture,high-resolution telescopes to be accomplished.However,the current processing technology in the processing of large-aperture mirror will cause periodic surface marks and broken tape on the mirror at the same time of manufacture due to the processing path,periodic feed and other factors,which brings a mid to high spatial frequency error for the telescope optical system.The study of mid and high spatial frequency errors has important implications for improving the resolution of telescopes at the current processing technic.In this paper,Harvey-Shack scattering model is introduced.Starting from statistical theory and Fourier theory,the effects of mid-to-high spatial frequency errors on imaging SNR are studied.Through simulation,the statistical characteristics of mid-to-high spatial frequency errors are indicated,and how the mid-to-high spatial frequency errors affect the imaging quality statistical parameters is shown also,such as surface shape.Provide reference for lifting the telescope due to the performance degradation caused by mid-to-high spatial frequency errors.Based on the above issues,this article includes the following aspects:1.The method of characterization of spatial frequency errors and the characteristics of mid-to-high spatial frequency errors are studied.The sources of mid-to-high spatial frequency errors are qualitatively explored.The spatial frequency errors division model commonly used in the world are introduced and a comprehensive testing scheme for spatial frequency errors is proposed.Statistics characters and fractal features and other parameters of mid-to-high spatial frequency errors are also given.2.The effect of mid to high spatial frequency errors on imaging quality was brought into the actual off-axis three mirror optical system,and the influence of the actual manufacturing surface shape error on the imaging quality parameters of the ring encircled energy ratio and signal-to-noise ratio was given.3.The characterization parameters of imaging quality are studied.The influence of mid-to-high spatial frequency errors on properties such as signal-to-noise ratio of imaging is given through simulation analysis.