Abstract

A method is proposed whereby the spatial speckles created in front of a plate with an optically rough surface when illuminated by a coherent laser beam is used to generate slope contour fringes. This is done by photographing the speckles contained in a parallel plane in front of the plate before and after deformation via double exposure. The resulting speckle interferogram is then optically Fourier transformed to yield the fringe pattern of slope contours. It is shown that the method is analogous to the Ligtenberg reflection moiré method with a grating of continuously variable pitch and orientation. The method can be applied to plates made of almost any material.

© 1976 Optical Society of America

Strain analysis by one-beam laser speckle interferometry. 1: Single aperture method

R. P. Khetan and F. P. Chiang
Appl. Opt. 15(9) 2205-2215 (1976)

Effect of magnification change in laser speckle photography

M. G. Pedretti and F. P. Chiang
J. Opt. Soc. Am. 68(12) 1742-1748 (1978)

Time-average reflection-moiré method for vibration analysis of plates

F. P. Chiang and C. J. Lin
Appl. Opt. 18(9) 1424-1427 (1979)

Strain analysis by one-beam laser speckle interferometry. 2: Multiaperture method

F. D. Chiang and R. P. Khetan
Appl. Opt. 18(13) 2175-2186 (1979)

Problem of defocusing in speckle photography, its connection to hologram interferometry, and its solutions

Karl A. Stetson
J. Opt. Soc. Am. 66(11) 1267-1271 (1976)