• branch cut method;
  • discontinuous object;
  • phase discontinuity;
  • regional phase unwrapping

Abstract:  This work presents an effective scheme for the phase unwrapping of electronic speckle pattern interferometry (ESPI) map of discontinuous objects. ESPI is a highly effective measurement approach for industry and academia. However, due to the speckle noise, its unwrapping job is quite difficult, especially, when treating ESPI maps obtained from the deformation field of an object containing height discontinuities. The minimum Lp norm method developed by Ghiglia and Romero can treat the aforementioned problem with acceptable accuracy, but takes a long time to run. Therefore, this study presents a novel method based on a hybrid of the regional algorithm proposed by Gierloff, the branch cut method presented by Goldstein et al. and the (spatially) parallel unwrapping method with region-referenced algorithm developed by Huang and He. The proposed algorithm can retrieve ESPI maps with height discontinuities within acceptable accuracy and effectiveness.