Micro Deformation Measurement Using Temporal Phase-Shifting and Spatial-Carrier Digital Speckle Pattern Interferometry

Temporal phase-shifting and spatial-carrier techniques are the two dominant phase extraction methods used in digital speckle pattern interferometry (DSPI). Temporal phase-shifting technique enjoys the advantages of precise phase extraction and capability of high-quality phase map formation, but suffers from the limitation in its use in dynamic measurement due to the time cost for carrying out the phase shift. To meet the rising demand of dynamic measurement of deformations in modern industry, spatial-carrier technique is developed to extract the phase information from a single speckle interferogram, yielding less time cost during a test. In this paper, both temporal phase-shifting and spatial-carrier techniques are investigated in theory as well as experiment. The experiment results from measuring a same deformation behavior using both techniques are used to compare the performances of the two phase extraction techniques. The results support the conclusion that the DSPI with the spatial-carrier technique can also be used to measure deformations precisely, although its phase maps are of less quality in comparison to those obtained by the DSPI with the temporal phase-shifting technique.