Patent ID: 6704112
Filing Date: 2004-03-09
Classification: G01B

Abstract:
A method for measuring the aberrations of a convex mirror, comprising:producing a reference wavefront and a first measurement wavefront of light both diverging from a first diffracting aperture and phase shifted relative to each other; propagating a portion of said reference wavefront onto a detector; converting a portion of said first measurement wavefront from a diverging to a converging wavefront to produce a converted first measurement wavefront; positioning a convex mirror under test in said converted first measurement wavefront such that said convex mirror modifies and substantially reflects said converted first measurement wavefront to produce a modified converted first measurement wavefront; introducing an aperture stop at said convex mirror under test; converting a portion of said modified converted first measurement wavefront from a diverging to a converging wavefront to produce a modified first measurement wavefront; reflecting said modified first measurement wavefront from a surface of said diffracting aperture onto said detector, wherein said reference wavefront and said modified first measurement wavefront combine to form a first interference pattern on said detector; producing a second measurement wavefront of light diverging from a second diffracting aperture that is spatially separated from said first diffracting aperture, wherein said second measurement wavefront is phase shifted relative to said reference wavefront; traversing said second measurement wavefront over the same optical path, less said convex mirror under test, as said modified first measurement wavefront; and combining said second measurement wavefront and said reference wavefront to produce a second interference pattern on said detector.