This paper describes a method by which recorded moire interferograms of diffuse, non optical surfaces may be processed using the principle of optical phase measurement by AC interferometry. In this method, a moire interferogram is recorded and processed as a transparency. The resulting interferogram is equivalent to a low spatial frequency optical hologram. An optical wavefront whose phase variations can be reconstructed from a plane wavefront and interfered with a second coherent plane wavefront of slightly different optical frequency, resulting in an interferogram appropriate for measurement by temporal electronic phase measurement. The results compare favorably to direct contact measurements.