Patent ID: 6304325
Filing Date: 2001-10-16
Classification: G01B

Abstract:
Interferometer apparatus for producing a shearing interferogram of a wavefront emanating from a reference object comprising:a. a rotating diffraction grating in the path of said wavefront, said diffraction grating comprising a radial diffraction grating having alternating light transmissive and lights reflective lines radially disposed and of equal width to one another at any radius;b. first and second detector planes;c. optical means including first lens means positioned in advance of said grating for focusing an image of said reference object onto said rotating diffraction grating to produce multiple images of the input aperture of said interferometer apparatus on said detector planes due to diffraction, and second lens means for imaging said wavefront onto said detector planes such that each location on said detector planes corresponds to a specific zone of said wavefront whereby overlapping sheared images of said wavefront will be produced on said detector planes which interfere causing intensity variations related to the phase difference between the sheared wavefronts, said second lens means being positioned both in advance of said grating and between said grating and said detector planes and including a transmissive second lens means for imaging said wavefront transmitted through said grating onto said first detector plane, and another transmissive second lens means for imaging said wavefront reflected from said grating onto said second detector plane; andd. detector means for monitoring the intensity variations at each said location on said detector planes.