Microscopists are often adapting techniques pioneered for astronomy. Adaptive optics is the example you all probably know. Relatedly, phase retrieval was originally developed for telescopic imaging systems, and was adapted for high NA microscopic imaging systems by Mats Gustafsson and colleagues (Hanser et al. 2003 Optics Letters).
A couple of excellent optics people, Kyle Douglass and Reto Fiolka, commented on the Confocal Listserv about this process recently (post 1, post 2). Kyle mentioned this freely available code for this application.