Patent ID: 6031611
Filing Date: 2000-02-29
Classification: G01B

Abstract:
A coherent optical system for measuring curvatures of specularly reflective surfaces, comprising:a light source configured to produce a substantially collimated coherent probe beam to impinge upon a specularly reflective surface so as to produce a reflected probe beam that has phase information of different points within an illuminated area;first and second gratings spaced relative to each other in an optical path of said reflected probe beam and configured to produce a predetermined phase manipulation on a wavefront of said reflected probe beam, wherein said predetermined phase manipulation is produced by diffractions that are produced by said first and second gratings;an optical element positioned to receive said reflected probe beam from said first and second gratings and configured to select and combine two diffraction components from said second grating to produce an interference pattern, wherein said selected two diffraction components are produced by said second grating from diffracting two different diffraction components from said first grating and are substantially parallel to each other;an optical sensing device disposed relative to said optical element to receive said interference pattern and produce an electrical signal indicative of said interference pattern; anda signal processor connected to receive said electrical signal and configured to extract a spatial gradient information on the wavefront of said reflected probe beam caused by a curvature of said specularly reflective surface,wherein said signal processor determines said curvature of said specularly reflective surface according to said spatial gradient information.