Moiré Topography Applied to Surface Measurement

Abstract

Two sorts of contour mapping method using Moiré Topography are described.
The first method employs a plane optical grating that is placed in front of the test surface. The contour moiré pattern is produced by the reflected pattern from the test surface and the fixed standard grating. The reflected light is diffracted at the grating, and selected by the special filter so that the contour moiré is produced through an optical system onto an observation screen or can be directly viewed.
The second method is contour moiré method using a curved optical grating such as the surface of a test object. A contour moiré pattern is produced within a space between the surface of grating and the test surface.
These methods are simple but precise enough for testing the surfaces of optical parts in the course of manufacturing. The sensitivity of contour moiré methods can be chosen between 0.003mm and 0.1 mm.