Phase Diversity

Phase diversity [1] implies that an image is measured through two or more phase "channels". The primary channel uses an adaptive optical system which attempts to remove phase distortions. The secondary channel introduces phase diversity by adding a known phase aberration to the adaptive optical system. In the simplest form of phase diversity the image plane is displaced, which introduces a quadratic phase into the optical path. The two outputs might be recorded simultaneously by using two focal planes; or they might be recorded sequentially, in which case the time lapse must be small enough that the primary channel's state is unchanged for the second measurement.