Estimation of the adaptive optics long-exposure point-spread function using control loop data

TLDR

Astronomical images from adaptive optics can be improved with image restoration, but this requires accurate, time‑varying PSF knowledge. The authors propose a PSF estimation method that uses adaptive optics control loop data synchronized with image acquisition. The method operates without additional observing time and has been validated on the PUEO system at CFHT. Accurate PSF estimates were obtained for guide stars up to magnitude 13.

Abstract

Astronomical images obtained with adaptive optics systems can be enhanced by using image restoration techniques. However, this usually requires an accurate knowledge of the system point-spread function (PSF) which is variable in time. We present a method to estimate the PSF related to each image, using data from the adaptive optics control computer, namely, the wave-front sensor measurements and the commands to the deformable mirror, accumulated in synchronization with the acquisition. This method requires no extra observing time and has been successfully tested on PUEO, the Canada–France–Hawaii Telescope adaptive optics system. With this system, accurate PSF estimations could be achieved for guide stars of magnitude 13 or brighter.