On-line automated phase-measuring profilometry

Abstract A simple phase reduction algorithm is used for on-line automated phase measuring profilometry of 3D diffuse objects through a projection moire method and image processing techniques. The error of the algorithm is within 1 20 th wavelength of the projected fringe. In contrast to phase shifting interferometry, this method eliminates the need for an accurate phase shifter and isolation table, thus an on-line or in-process measurement can be executed more easily. Experimental results show that a surface height resolution of better than 60 μm has been attained as the phase of four deformed grating images with random phase shifts are averaged.