Moire deflectometry with a focused beam: radius of curvature, microscopy, and thickness analysis

Three uses of moire deflectometry employing a focused beam are described. A microscopic mode provides inspection of magnified images of the test object. The moire fringes are used as a noncontact tunable caliper for measuring the dimensions of small imperfections and other features of the surface. The tunable scale is independent of the zooming ratio. The spherometer mode measures the radius of curvature of concave or convex spherical objects. Deviations from spherical shape are measured with variable sensitivity. The thickness of transparent objects is measured by focusing the beam on each face in turn.