By use of a numerical calculation based on Green’s integral equation, we study the near-field speckles produced by the random self-affine fractal surfaces of a dielectric medium. The speckle intensities evolve considerably in the near-field region, and the local fluctuations in them disappear before they have traversed the distance of a wavelength. The transition of the speckle contrast either on the surface or in the near field and in the neighborhood non-near-field regions depends on lateral correlation length ξ and roughness exponent α of the random surfaces.
© 2003 Optical Society of America
(030.6140) Coherence and statistical optics : Speckle
(050.1940) Diffraction and gratings : Diffraction
(120.6160) Instrumentation, measurement, and metrology : Speckle interferometry
(240.6690) Optics at surfaces : Surface waves
Chuanfu Cheng, Chunxiang Liu, Xiaorong Ren, Man Liu, Shuyun Teng, and Zhizhan Xu, "Near-field speckles produced by random self-affine surfaces and their contrast transitions," Opt. Lett. 28, 1531-1533 (2003)