The formation of Young fringes that are observed in speckle photography is discussed. Both the shape and the contrast of the fringes are derived by starting from the cross-correlation function of the light intensities to be recorded in a double-exposure specklegram. The effects of focusing and defocusing in specklegram recording on speckle displacement affecting the shape, as well as the origin of speckle decorrelation affecting the contrast, are discussed in detail. The degree of the decorrelation is shown to be given by the squared modulation transfer function of the imaging lens for a spatial frequency that is proportional to the speckle displacement at its pupil plane. These theoretical relations are verified by experiments performed for in-plane object translation combined with tilt.
© 1984 Optical Society of America
Equations on this page are rendered with MathJax. Learn more.