Exit pupil wavefront of segmented mirror synthetic aperture optics is discrete

and much different from traditional systems’. Theory of wave aberration and diffraction optics should be introduced to evaluate imaging quality simultaneously. By using the diffraction integral

two methods are used to evaluate imaging quality

which one is fit the exit pupil wavefront to Zernike polynomial directly and calculate the complex amplitude distribution

and the other way is calculate the complex amplitude distribution of each sub-exit-pupil individually

and overlap them in image plane. A segmented mirror system with three sub-mirrors primary is built

and the wavefront is obtained by ZYGO GPI interferometer

include overall exit pupil wavefront and each sub-exit-pupil wavefront. The two methods are compared and the result shows that the latter way is more precision but complex; on the other hand

the former way can satisfy the required precision and more simple

when the system exit pupil wavefront is near the diffraction limit.