Stitching path optimization for a rough surface interference test

Phase unwrapping is a crucial step in phase-shifting interferometry for processing phase information, and it will directly impact the precision of measurement results. The discrete cosine transform-based least-squares method (DCT-LS) is applicable for phase unwrapping of the wrapped phase derived from the interference detection of rough surfaces in optical processing. While this method can yield a globally smooth unwrapping result, it may also introduce global phase errors. To suppress the error propagation inherent in the least-squares method, a scheme of block phase unwrapping and stitching is adopted. Additionally, an optimized stitching path planning method is proposed to get the optimal unwrapping result of rough surfaces. Simulation and experimental results show that the block phase unwrapping and stitching method significantly reduces the global phase errors caused by the least-squares method. Furthermore, after the stitching path optimization, the unwrapping results are obviously better than those obtained by stitching with the serpentine path.