Digital Photography in Measuring the Inclination of the Object Surface with Formation of a Speckle Structure

Abstract

Optical schemes for measuring surface inclination due to shift or deformation are considered. Speckle-interferometry methods are used. The distinguished features of these schemes are connected with using a digital photocamera and a forming speckle structure in nonmonochromatic light. Several technical solutions are proposed making it possibile to measure inclination with an accuracy up to tenths of degree using standard cheap equipment. To form the speckle structure, the pattern of a random binary structure with unit size of several millimeters is used in the base fixed plane. The digital camera was placed in the analyzed plane and turned together with the plane. It registered a reduced image of the pattern. The registration was done for two positions of the surface, the pattern being illuminated by the camera flash lamp. Measuring the width and orientation of the interference fringes formed for the two speckle structures allows one to determine the inclination and orientation of the rotation axis.