Towards a Novel Phase Unwrapping Model for Three Dimensional Measurement

In order to obtain a higher quantity absolute phase, a novel phase unwrapping model by combination of dual-frequency heterodyne and segmented quantifization phase coding method is proposed in this research. This model also provides a generalized phase order error correction method for eliminate phase order jump errors. Only ten fringe patterns are used for the projection in this study. The workflow of the devised model starts with acquisition of the low frequency wrapped phase by using the classic double-frequency heterodyne method, and then it moves to obtain the fringe order of low frequency wrapped phase based on the projected segmented quantifization phase coding patterns. In this step, two-dimensional scanning lookup method is used to eliminate the noise points caused by the rounding operation. Then, new fringe order can be obtained by combination of the obtained fringe order of low frequency wrapped phase and the new projected binary fringe pattern with complementarity, and this new fringe order combined with the previous fringe order can be used to unwrap the heterodyne phase. Finally, the wrapped phase of the dual-frequency is unwrapped through unwrapped heterodyne phase and the highest frequency phase. This study applies metal workpiece measurements as case studies to test the validity of the proposed model. The experimental results show that the error effects of fringe order can be eliminated, and the high frequency fringes retain more information on the measure workpiece surfaces.