T. Fricke-begemann et J. Burke, Speckle interferometry: three-dimensional deformation field measurement with a single interferogram, APPL OPTICS, 40(28), 2001, pp. 5011-5022
An electronic speckle interferometer, arranged for out-of-plane sensitivity
and with an off-axis reference beam to produce spatial phase bias, is used
for three-dimensional deformation field measurements. The complex amplitud
e of the object wave is calculated by application of a Fourier-transform me
thod to a single interferogram. The change in phase after object deformatio
n yields the out-of-plane component of the displacement field. The two in-p
lane components are obtained by cross correlation of subimages of the recon
structed object wave's intensity, a method that is also referred to as digi
tal speckle photography. The Fourier-transform algorithm is extended and mo
dified, leading to random measurement errors that are below widely accepted
theoretical limits and also to an extended measuring range. These properti
es and the mutually combined information improve the accuracy of both metho
ds compared with their usual single implementation. The performance is eval
uated in experiments with pure out-of-plane, pure in-plane, and combined de
formations and compared with theoretical values. An example of a practical
application is given. (C) 2001 Optical Society of America.