Patent ID: 7390999
Filing Date: 2008-06-24
Classification: G01J

Abstract:
1. A differential Shack-Hartmann curvature sensing device for measuring a wavefront curvature comprising: a Shack-Hartmann sensor having an output beam; an optical element to split said output beam into a first, second and third beam, each of said first, second and third beam traveling in one of an x, y and z direction, respectively; a first, second and third lenslet array in the path of the first, second and third beam, respectively, to generate a corresponding first, second and third Hartmann grid each having plural grid points; a first and second shearing element for shifting said first and second Hartmann grids a lateral differential distance in a first direction and a second direction perpendicular to said first direction; and a measuring device for measuring plural slopes of plural wave fronts at each Hartmann grid point generated by said first, second and third beams to obtain a wavefront normal curvature and corresponding twist curvature terms to determine a principal curvature and direction, wherein said plural slopes at each of the plural Hartmann grid points is measured approximately simultaneously with and without differentially shifting the first and second Hartmann grids.