Measuring the curvatures of machined surfaces using laser speckle interferometry

Abstract

Dimensional accuracy of components is of paramount importance to the manufacturing industry. Very often curvatures are used in specifying the profile of components which, after being machined, can be difficult to measure with profilometers or coordinate measuring devices. This paper presents a non-contacting and whole-field method of measuring curvatures using a moving laser source and an image-shearing camera. The resulting interference fringe pattern, which is related to the slope of the profile, enables easy computation of local curvatures with only one differentiation. To enhance the viability of this technique in the industrial environment, optical fibres were used so that the desired movement of the laser source could be achieved readily. In this paper, the technique described was applied to measuring the profile of wire-cut cylinders having circular and elliptical cross-sections. © 1991.