The relationship between image quality and piston errors of synthetical aperture optical imaging system has been studied. An active segmented cophasing imaging system and its Zemax simulation model were set up. Diversity piston errors were introduced and the corresponding MTF were calculated with the Zemax simulation model. Simulation experiments have been carried out with the cophasing imaging system, and the results are coincident with the simulated results. The results show that image quality changes with the increase of the piston error periodically if the piston error is smaller than the coherent length of the light source, and the image quality becomes the worst if the piston error is an odd multiple of π.
Satellite platform vibration causes the image quality to be degraded, it is necessary to study its influence on image quality. The forms of Satellite platform vibration consist of linear vibration, sinusoidal vibration and random vibration. Based on Matlab
& Zemax, the simulation system has been developed for simulating impact caused by satellite platform vibration on image quality. Dynamic Data Exchange is used for the communication between Matlab and Zemax. The data of sinusoidal vibration are produced by sinusoidal curve with specific amplitude and frequency. The data of random vibration are obtained by combining sinusoidal signals with 10Hz, 100Hz and 200Hz’s frequency, 100, 12, 1.9’s amplitude and white noise with zero mean value. Satellite platform vibration data which produced by Matlab are added to the optical system, and its point spread function can be obtained by Zemax. Blurred image can be gained by making the convolution of PSF and the original image. The definition of the original image and the blurred image are evaluated by using average gradient values of image gray. The impact caused by the sine and random vibration of six DOFs on the image quality are respectively simulated. The simulation result reveal that the decenter of X-, Y-, Z- direction and the tilt of Z-direction have a little effect on image quality, while the tilt of X-, Y- direction make image quality seriously degraded. Thus, it can be concluded that correcting the error of satellite platform vibration by FSM is a viable and effective way.