Secondary mirror position error detection method based on multi-field wavefront sensing

When the space-to-ground optical remote sensing system with a segmented primary worked, the alignment degeneracies of secondary mirror relative to the primary mirror would have an impact on the image quality, which should be detected and corrected online. When there was no center segmented-mirror in the segmented primary mirror, the traditional sensitivity matrix inversion method would not be used to calculate the alignment degeneracies of secondary mirror. It proposed a method to calculate the misalignment of the secondary mirror by using the multi-field wavefront sensing information. Based on ZEMAX, it established a space-to-ground remote sensing system with 36 segmented primary mirror, in which there was no center mirror. For the optical system with special aberration characteristics, it built a mathematical model to obtain the misalignment of secondary mirror by means of the field-dependent wavefront aberration which can be got by multi-field wavefront sensing. The simulation results showed that when the wavefront sensing error is 1/40(=632.8 nm), the detection accuracy of the misalignment of secondary mirror on X,Y-translation and X,Y-tilt reached 30 nm and 15 respectively; the detection range of the misalignment of secondary mirror on X,Y-translation and X,Y-tilt are 0-1.5 mm and 0-0.03 respectively. And a lot of simulations based on the real space optical remote system were done to prove the feasibility of the proposed method.