A Directional Space-scale Based Analysis Method for Three-dimensional Profile Detection by Fringe Projection Technique

The optical methods of metrology are widely used in science and engineering to measure a wide range of parameters (such as deformations) that are related to the optical phase informat ion coded in the intensity images. Two of mostly used techniques, namely a phase shifting algorith m (PS) and a wavelet transform algorith m (WT), are applied in order to estimate optical phase information, after an initial set of fringe patterns acquirement using the fringe pattern technique. In this paper, the 2D wavelet approach used to the phase retrieval problem for surface shape and object's defect measurement is presented and comparatively evaluated. Aim of th is paper is the in-depth investigation of the advantages of the 2D wavelet approach and the gain of a better insight on its use in the industrial context. Extensive work has been conducted for investigating the influence of several factors (such as the noises, the surface variation, the modulation rate, etc.) on the performance of the wavelet phase retrieval technique, while a detailed analysis of the obtained results is also given.