Digital image processing of moiré fringe patterns with an application to fractures in bovine dentin

Min Ma National University of Defense Technology Department of Astronautical Technology Changsha, 410073, China Abstract. A single fringe phase shifting technique is presented for extracting the whole-field displacement distribution from single fringe patterns. By making a small modification in the traditional Fourier transform (FFT) method for fringe processing, the proposed method is capable of maintaining the fringe sign information. An additional approach is introduced that utilizes knowledge of the fringe sign in identifying fringe skeletons with high precision. A combination of these methods of fringe pattern processing was used to examine the whole-field displacement distribution in double cantilever beam (DCB) fracture specimens prepared from bovine maxillary molars. Phase maps and precise fringe skeletons were generated using the proposed techniques from fringe patterns obtained using moiré interferometry. Both aspects of the displacement measurements were used to determine the local displacement distribution near the crack tip, and to study the mechanics of fracture. © 2002 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.1467938]