%A Sihua FU, Xuejun LONG, Hui LIN, Qifeng YU %T Fringe-contoured-window sine/cosine filter for saw-tooth phase maps in ESPI %0 Journal Article %D 2008 %J Front. Optoelectron. %J Frontiers of Optoelectronics %@ 2095-2759 %R 10.1007/s12200-008-0044-y %P 345-351 %V 1 %N 3-4 %U {https://journal.hep.com.cn/foe/EN/10.1007/s12200-008-0044-y %8 2008-08-05 %X

In electronic speckle pattern interferometry (ESPI), because saw-tooth phase map obtained by phase-shifting is inherently full of speckle noise, noise reduction should be carried out to suppress high-level noise before it is unwrapped. In accordance with the feature of the saw-tooth phase map, an adaptive filter method combining the classical sine/cosine filter and the fringe orientation information of the phase map is developed. A fringe orientation map is first generated from the saw-tooth phase map, and then a fringe-contoured window is derived accordingly. Finally, filtering is carried out within the window. Compared with existing filters, it has a better performance on phase jump information preservation without any blurring effect on phase distribution provided that filtering is implemented on the equal-phase window. Moreover, its capability for noise reduction is more powerful. The effectiveness and advantages of the novel filter have been also verified by both simulated and real saw-tooth phase maps.