| High precision optical surface is the core components of high-resolution opticalremote sensing system, while manufacturing precision and processing ability limitthe development of the high-resolution optical system. Existed processingtechnology could produce errors which affect the high-resolution system’sperformance, such as the frequency response and SNR, thus have further influenceon the imaging quality. The new high-resolution system puts forward higherrequirements to the fabrication of reflector, however, the traditional evaluationmethods are unable to meet the demand of high surface quality. Therefore, furtherstudy on surface characterization methods of ultra-high-precision optical elements,and the impact of the surface frequency error on the system imaging quality underthe diffraction limitation are significant to improve the imaging quality of thehigh-resolution space optical remote sensing system.Errors in different frequency range have different point spread function (PSF).Finally, they bring different effects on the image resolution, sharpness, contrast, andso on. Hence, it is necessary to put forward clear goals on the amplitude, spectrumand distribution form of full frequency error and realize its uniform convergence asfor manufacturing high-resolution imaging system. According to the influence offrequency error on the optical system performance, a dividing method of fullfrequency error has been put forward. The optical system imaging simulations revealthe influences of the optical surface’s low, middle, high frequency on the imaging quality of optical system, thus the tolerance of different frequency band could bedetermined. Combined with modern optical processing technology, an evaluationsystem of full frequency error has been set up. On one hand, it provides guidance toprocessing, on the other hand, it provides references to optical design and systemperformance prediction.The thesis includes four parts as follows.1, The division of optical surface full frequency error.Optical surface error contains the distribution of the low-middle frequency errorand the statistical information of middle-high frequency error. They affect the systemwave aberration and stray light, and finally influence the optical system imagingquality. According to the special frequency error’s periodicity of imaging opticalsystem, a full frequency error characterization model is established, and thefrequency error is divided into three parts;2, Research on optical surface frequency error’s influences on the performanceof optical system.To research the effect of optical surface residual on the performance of imagingsystem, spatial frequency error division method is proposed based on the phasedifference of optical system pupil. The analytic expression, which manifest theinfluence of the Mid-Spatial Frequency Errors (MSF) on modulation TransferFunction (MTF), has been derived in statistical sense. And the MTF featuredresolution affected by the mid-spatial frequency error has been determined. Theinfluence of low-spatial frequency error and mid-spatial frequency error has beencompared. The mid-spatial frequency error causes the rapid decline of MTF at lowresolution, and that feature resolution of MTF is obtained according to the analyticexpression of mid-spatial frequency error influence function;3, The study of the optical system performance parameters’ influence onimaging quality.Substituting the actual manufacturing parameters into optical system design, therelationship between the system performance and the processing error are analyzedaccording to the actual manufacturing results. The influence of optical processing error on the image of diffraction limited system. The system PSF is calculated by thewave aberration containing frequency error. Such PSF can be used to perform theimage degradation, and the brightness, contrast, resolution and sharpness of thedegraded image are calculated. Hence, the influences of frequency error on opticalsystem imaging quality are studied. How to analyze the specific influence of thesefactors on the optical system is important to forecast the space optical systemimaging quality;4,Imaging experiments, and analyzing the influence of frequency error onoptical system imaging quality.In the diffraction limited finite distance coaxial imaging system, waveaberration with same amplitude and different frequency is introduced by the phaseplate, and the influences of frequency error on imaging quality are analyzed.This paper mainly researches the influences of optical surface frequency erroron the system imaging quality. Modeling of full frequency error and dividing methodare completed. The impacts of full frequency error on the system frequency responseand signal-to-noise ratio are studied by simulation. The influences of mid-spatialfrequency error on system MTF and PSF were deduced in statistical significance.The experiments on the diffraction limited finite d istance coaxial imaging system areconducted, in order to study frequency error’s influence on imaging quality andexplore the impacts of frequency error on the imaging quality of infinite distancespace telescope. |
