Two-index holographic contouring: application of digital techniques

Abstract

Holographic contouring is a simple and flexible method of producing a contour map of the shape of a three-dimensional object with a contour interval from 1 to 300 μm. However, a limitation of the method is that precise information on the shape of the object is not available at points between the contours. This can sometimes result in ambiguities in the interpretation of the results. In addition, evaluation of the deviations of the shape of the object from a specified shape is not easy. This paper shows how these problems can be solved by the application of digital techniques of phase measurement. A simple technique by which the sensitivity of the method can be varied continuously over a wide range is also described.