Incoherent projection Moire contour sensing with coherent processing for large structures

Abstract

This paper presents the theory and results of three Moire methods 1) the incoherent projection Moire method, 2) the electronic phase detection method, and 3) the fringe multiplication method. It is proposed that these three methods be used together in a system to measure out-of-plane displacements of large diffusely reflecting surfaces. The operation of the system is divided into two processes. The first process records an incoherent moire pattern which contains the out-of-plane displacement information. The second process uses a transduced coherent image of the pattern produced in the first process to optically generate a quantitative result with variable sensitivity. The coherent processing is a technique that uses the fringe multiplication method with the electronic phase-detection method. The result is the quantitative, out-of-plane displacement measurement with sensitivity enhancement that can be altered during coherent processing of the Moire fringe pattern.