DEVELOPMENT AND APPLICATION OF COMPUTER-AIDED FRINGE ANALYSIS

Abstract

Photo-mechanics methods have matured and emerged as important engineering tools. Although numerous image-processing algorithms have been developed to complement interferometric measurement techniques, these algorithms have been implemented originally for classical interferometry and the extensions to the general photo-mechanics fringe analysis have been limited. In this dissertation, the existing computer-aided digital fringe image analysis and processing techniques are investigated; the most appropriate fringe image processing schemes and their limitations are identified. To make the computer-aided fringe analysis practical to the real engineering problems, the existing schemes are improved and a series of new fringe analysis techniques are developed. Among these new techniques, the self-adaptive fringe filtering scheme considers not only the orientations of the local fringes but also the local fringe densities; the enhanced random phase shifting algorithm can detect the phase shift amounts and the full-field phase distributions automatically and simultaneously; the hybrid semi-automatic O/DFM fringe centering technique combines the advantages of existing techniques and can be employed to obtain full-field fractional fringe orders and their gradients accurately. Based on the study, a Windows GUI-based expert software system is developed for interferogram fringe analysis and processing. This expert system includes all the algorithms presented in this dissertation.

Selected but original applications of the computer-aided fringe analysis are presented. They include: (1) development of infrared diffraction interferometer for co-planarity of high-density solder bump patterns; the infrared light enables the regularly spaced solder bump arrays to produce well-defined diffracted wavefronts, (2) development of an inverse method to determine elastic constants using circular disc and moiré interferometry; this method uses a non-linear over-deterministic approach to determine elastic constants simultaneously, and (3) applications to out-of-plane shape and warpage measurement and in-plane displacement and strain measurements of electronic packaging components.