White-light image processing using oriented speckle-screen encoding

Abstract

We present a new technique of spatially oriented speckle-screen encoding to improve on the grating encoding technique for white-light image processing.

Recognition of Direction of New Apertures from the Elongated Speckle Images: Simulation

“…The symbol    stands for the convolution product. Equation (5) means that the modulated elongated speckles are formed from the convolution product of both of the Fourier spectrum of the diffuser and the sharp elongated aperture. The direction of speckle is elongated normal to the semi-major axis of the elliptic aperture.…”

“…The auto-covariance function corresponds to the normalized autocorrelation function of the intensity which has zero base and its full width at half maximum (FWHM) provides a reasonable measurement of the average width of a speckle [6]. In order to use autocorrelation function method to calculate the average speckle size, it requires sufficient sampling speckles in an image to give a reasonable statistical evaluation.…”

“…The production of elongated speckle images was obtained using the mechanical scanning of the static speckle pattern [1]. The author presented a technique of spatially oriented speckle-screen encoding to improve the grating encoding technique for white-light image processing.…”

“…The laser speckle pattern, arising from light scattered from rough surfaces that are illuminated by polychromatic laser light, is detected in the far-field region. The incoherent superposition of these light intensities and the angular dispersion cause the effect of speckle elongation [4,5]. This is characterized by increasing speckle widths and leads to a radial structure of the speckle patterns.…”

“…The relation between surface roughness, speckle elongation, and correlation length of autocorrelation function can be obtained. Consequently, the measured surface roughness can be achieved [6]. An oriented photographic diffuser was used to record an elongated speckle pattern.…”