Patent ID: 7525076

Claim:
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 plurality of beams traveling in x, y and z directions; a lenslet array in the path of the beams that generate a corresponding Hartmann grids each having plural grid points; a shearing element for shifting said 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 beams to obtain a wavefront normal curvature and corresponding twist curvature terms to determine a principal curvature and direction, wherein said plural slopes at the plural Hartmann grid points is measured approximately simultaneously with and without differentially shifting the Hartmann grids.