Centroid computing of far-field spots based on sub-aperture retro array

Since the jitter frequency of incident laser beam becomes higher in the 'Common Path/Common Mode' (CP/CM) system due to the guiding system added to the laser module, the current laser-beam stabilizing control with hartmann-shack sensor is not enough. As we all know, better beam stabilizing control effect requires higher detecting frequency. Generally, the detecting frequency of hartmann-shack sensor in the CP/CM system is far lower than the far-field spot. So we want to use the far-field spot of the SARA to feedback instead of the hartmann-shack sensor. In this work, we study the far-field spot of a 61-unit SARA from the CP/CM system. We ratiocinate the process of the simulation based on Fresnel diffraction and Fourier optics. Comparison between standard far-field spot and the far-field spot from sixty one units SARA based on duty ratio of the retro reflectors and different wavefront tilts aberrations is given, while the wavefront is given in zernike model.