Speckle interferometry with temporal phase evaluation: influence of decorrelation, speckle size, and nonlinearity of the camera

Recently, a new method to measure object shape and deformation with temporal evolution of speckles in speckle interferometry was reported. In this method, Certain parameters, sensitive to shape or deformation are changed continuously, and the fluctuations in the irradiance of each speckle is recorded. The information over the whole object deformation is retrieved by Fourier-transformation techniques. We present a detailed theory and analyze the influence of decorrelation due to longitudinal and lateral size of the speckles. It is also shown that the method can be used to measure small deformations (less than 5 mu m) with higher resolution. Further, the nonlinearity of the camera is shown to enhance the sensitivity. (C) 1999 Optical Society of America. OCIS codes: 030.6140, 070.2590, 120.3180, 120.6160.