The Method Of Cophase Detection And Correction For Optical Synthetic Aperture Imaging

The optical synthetic aperture system achieves coherent imaging by arranging and combining multiple telescope subsystems,so as to achieve the effect equivalent to large aperture imaging system.In the imaging process,it is necessary to ensure the requirement of common phase between the sub telescope subsystems.However,due to the influence of actual productionand processing,assembly and external environment factors,there will be some errors in the phase information between the subsystems,which will affect the coherent imaging of the whole system,so that the resolution of the system will be degraded.In this paper,the special beam combining error of the synthetic aperture system is studied to explore its impact on the imaging quality.At the same time,the system cophase detection method is studied and the phase compensation device is designed to ensure the high-resolution imaging of the system.Firstly,in this paper,the imaging principle and characteristics of the optical synthetic aperture system are studied,meanwhile its imaging model is established;and the beam combining error of each subsystem in the synthetic aperture system is studied.By analyzing the PSF,MTF,Sr curves during the imaging of the system,the characteristics of the beam synthesis error are obtained,and its influence on the imaging is explored.Secondly,the detection method of the common phase in the synthetic aperture system is studied and the detection error is analyzed.Based on the comparison of the common phase detection methods,according to the characteristics of the synthetic aperture system,the phase diversity algorithm is used for phase detection.The principle of the phase diversity algorithm and the detection model under noise are studied,the phase information is detected through simulation,and the beam combining error and the detection accuracy are obtained.Then the error that will appear in the detection is analyzed,including the defocusing error,focal plane error,position registration error and the noise.The tolerance of phase diversity algorithm for various errors and the compensation method for errors are studied.According to the characteristics that the noise of synthetic aperture system is difficult to be removed directly,the phase diversity algorithm is improved so that it can detect the phase information more effectively.Finally,the phase compensation method is studied and the compensation device is designed.Through the theoretical analysis and the calculation,the micro adjustment device including one-dimensional micro displacement device and two-dimensional deflection device is designed with vertical structure,so as to realize the phase compensation;the finite element analysis of the device is carried out with ANSYS,including static analysis and dynamic analysis,the stiffness of the device is obtained by static analysis,and the deviation from thetheoretical design is less than 3%.The dynamic analysis includes modal,harmonic response and random vibration show that the modal frequency of the compensation mechanism is greater than 280 Hz,Under the condition of random vibration,there is no plastic deformation and the stability of the compensation device is good.The overall design can effectively compensate the phase information and realize the high-resolution imaging of the synthetic aperture system.