A curvature sensor using white-light scanning interferometry

Abstract

We present a method of free-form surface profile measurement using white-light scanning interferometry. This method is based on the principle of curvature sensor which measures the local curvature under test along a line. The profile is then reconstructed from the curvature data on the each point. Unlike subaperture-stiching method and slope detection method curvature sensing have strong points from a geometric point of view in measuring the free-form surface profile. Curvature is related to second derivative terms of surface profile and an intrinsic property of the test piece, which is independent of its position and tip-tilt motion. The curvature is measured at every local area with high accuracy and high lateral resolution by using White-light scanning interferometry.