PHASE-LOCKED MOIRE FRINGE ANALYSIS FOR AUTOMATED CONTOURING OF DIFFUSE SURFACES

Phase-locked moiré systems have the advantage of rapid data acquisition and accuracy of better than one twentieth of the fringe spacing. In conventional moiré systems data acquisition is performed by making a photographic plate and taking measurements from the plate either visually or with a microdensitometer. This is slow, and the accuracy is about one-quarter of the fringe spacing. The phase-locked system is more accurate and permits a more favorable trade-off between accuracy and working depth. The equations governing moiré contouring are examined, and the theory of phase-locked moiré fringe analysis is presented. The design and operation of the phase-locked moiré contouring system are described, and the results of measurements made with the instrument are presented. © 1979 Optical Society of America.