Patent ID: 7781712

Claim:
An image-based wavefront sensing apparatus to remove piston wraps from the segments of the segmented mirror of a telescope or other optical instrument, comprising: a digital camera configured to produce digital images; an actively controlled, segmented mirror which images a distant point source of light onto the digital camera; a lens to introduce defocus into the optical path between said mirror and said camera, as needed to image a defocused image on said camera; narrowband optical filters in the optical path between said mirror and said camera, as needed to image monochromatically at wavelengths λ and λ 1 on said camera; a phase retriever to process diverse digital images, one in-focus and another out-of-focus, produced by the camera to produce an estimate, φ, of the abreveating phase, θ, formed by the segments of an unaligned mirror when it images the distant point source; and a segment controller to convert φ into a vector C of parameters to control the segmented mirror (about 3 to 6 parameters per segment) to remove the aberrating phase, θ, and to produce a residual phase, ε=θ−φ, in the segmented mirror.