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 µm) with higher
resolution. Further, the nonlinearity of the camera is shown to
enhance the sensitivity.
© 1999 Optical Society of America
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