Patent ID: 8748801

Claim:
A discrete wavefront measurement device for discretely sampling local tilt across different sub-regions of a continuous optical wavefront at an object plane, comprising: an optical system having an effective numerical aperture (NA), said optical system mapping the local tilt of each sub-region of the optical wavefront to a spatial displacement at the back focal plane of the system and imaging a wavefront spatial extent at a conjugate image plane beyond the back focal plane; a variable transmission filter (VTF) at or near the back focal plane, said VTF exhibiting a variable amplitude transmission profile over an active region up to a cut-off angle imposed by the NA of the optical system, said VTF attenuating an amplitude of each sub-region of the optical wavefront in accordance with the spatial displacements in the VTF's active region; a pixilated detector at the conjugate image plane located at greater than twice the back focal length thereby increasing the cut-off angle, said detector responsive to the attenuated wavefront and discretely reads out the optical intensities across the different sub-regions of the wavefront to quantify the local tilts of each sub-region of the optical wavefront; and an afocal wavefront compressor that compresses the wavefront prior to the optical system, said compressor maintaining the sampling of the wavefront over the same spatial extent and spatial sampling resolution at the increased cut-off angle.