Free form defects measurement by interferometry

Applied Optics Laboratory, Optics and Precision Mechanics Institute, University of Sétif 1 - Algeria

^* meguellati_said@yahoo.fr

Abstract

This optical scan method presented in this paper is used for precision measurement defects in form or absolute forms in comparison with a reference component form, of optical or mechanical components, surfaces. The principle of the method is to project the image of the source grating to palpate optically surface to be inspected, after reflection; the image of the source grating is printed by the object topography and is then projected onto the plane of reference grating for generate moiré fringe for defects detection. The optical device used allows a significant dimensional surface magnification of the surface inspected, which allows easy processing and reaches an exceptional precision of measurements. According to the measurement principle, the sensitivity for displacement measurement using moiré technique depends on the spatial frequency grating, for increase the detection resolution. This measurement technique can be used advantageously to measure the deformations generated by the production process or constraints on functional parts and the influence of these variations on the function.