Image reconstruction and isoplanatic patch measurements with phase diversity in day and night-time astronomy

Phase diversity techniques use the information in the 3-D volume near the focal plane to measure the optical wavefront errors present in an imaging system. Usually, the "focal volume" is sampled by recording an image at the best focus and an additional image taken slightly out of focus. Since phase diversity techniques do not require a point source, they are well suited for making wavefront measurements from extended objects. Once the wavefront errors are determined, the OTF associated with the optical aberrations can be deconvolved from both the focused and the defocused images to make a more accurate estimation of the object.