Effect of Partially Coherent Light on the Contrast of Speckle Patterns Obtained Using Digital Image Processing of Speckle Photography

Abstract

The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theoretical model, the effects of grain height, its density, the band width and spectral distribution of the line profile (Gaussian and Lorentzian) illuminating a rough surface on the visibility of speckle pattern are investigated. An experimental setup was constructed to study the effect of surface roughness and coherence of the illuminating light beam on the contrast of speckle pattern. The general behavior of the experimental results, which agree with published data, is compatible with the new theoretical model.

New analytical expression for speckle contrast of spectral light broadening

“…The speckle contrast of monochromatic and quasi-monochromatic light has been studied by [7][8][9][10][11][12][13][14][15][16]. The effect of the spectral light broadening on the visibility of the interference fringes obtained in the transmission from a surface of regular roughness, in the form of cross-grating, has been presented by [17,18].…”