A phase-diversity speckle experimental system for one meter-scale ground-based telescope

Phase-diversity (PD) is the least square adaptive-filter of the imaging system based on wave optics theory. It can use unknown extended object as the observation object to collect two or more images whose wave-front diversities are known and fixed. According to the images, the wave-front of the optical system can be calculated by PD, and simultaneously the estimation of ideal image for the observation object can be obtained. Phase-diverse speckle (PDS) technique extends PD by using a series of short-expose frames as the input. In this paper, we designed PDS experiment on a 1.23 m telescope and successfully got clear restored images of space objects. Under the observation condition that the atmospheric coherent length was not more than 8 cm at 500 nm wavelength in Changchun city, we replaced the deformable mirror with a plane mirror in adaptive optical system and separately used the moon and Polaris as the observation objects. For Polaris, the FWHW reduced from 20.6 to 5.3 (in pixel), which decreased about 74%. The experimental results demonstrate that PDS algorithm can be used on one meter-scale telescope in practical observation.