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ABSTRACT: The analytical expression for the Bi-frequency correlation function of the intensity scattered from two-dimensional dielectric randomly rough surfaces obeying Gaussian distribution are presented based on the scalar Kirchhoff approximation theory with the root-mean-square (rms) slope of the surface less than 0.25 and the Gaussian moment theorem. The results show that the bi-frequency correlation properties of the scattered intensity closely depend on the incident and scattered conditions as well as on the statistical parameters and complex refractive index of the surface. Especially, the correlation function mainly comes from the specular direction, and the coherence bandwidth and the function decrease with the increase of the roughness of the rough surface. In addition, comparing with the real part, the imagery of the complex refractive index has a greater impact on the bi-frequency correlation function.
Optics Express 07/2012; 20(14):14833-47. · 3.59 Impact Factor
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ABSTRACT: From scalar Helmholtz integral relation and by coordinate system transformation, this paper begins with a derivation of the far-zone speckle field in the observation plane perpendicular to the scattering direction from an arbitrarily shaped conducting rough object illuminated by a plane wave illumination, followed by the spatial correlation function of the speckle intensity to obtain the speckle size from the objects. Especially, the specific expressions for the speckle sizes of light backscattered from spheres, cylinders and cones are obtained in detail showing that the speckle size along one direction in the observation plane is proportional to the incident wavelength and the distance between the object and the observation plane, and is inverse proportional to the maximal illuminated dimension of the object parallel to the direction. In addition, the shapes of the speckle of the rough objects with different shapes are different. The investigation on the speckle size in this paper will be useful for the statistical properties of speckle from complicated rough objects and the speckle imaging to target detection and identification.
Optics Express 02/2012; 20(4):4726-37. · 3.59 Impact Factor
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ABSTRACT: The fourth-order moment of the scattered light, namely, the correlation function of the scattered intensity fluctuation from two-dimensional optically weak homogeneous and isotropic rough surfaces obeying Gaussian distribution are investigated based on Beckmann theory and Gaussian moment theorem. Analytical and numerical results are given for the correlation functions of the scattered intensity fluctuation. Also two important special cases, two-frequency correlation and angular correlation, are discussed, as well as the influence of the incident and observation conditions and the characteristic parameters of the rough surfaces on the correlation function which could lead to a more clear understanding of the scattering property of the rough surface and provide a theoretical basis for the 3D target recognition.
Optics Express 01/2012; 20(2):1491-502. · 3.59 Impact Factor
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ABSTRACT: Based on the Physical optics approximation, the scattering field in the far zone by arbitrarily shaped objects with slightly rough surface which obeys Gaussian distribution and its two-frequency mutual coherence function are derived theoretically, and the numerical results for rough spheres and rough cylinders are given and analyzed. The results show that the function has closely relationship with the roughness and the dimension of the rough objects. The roughness and the curvature of the object influence both the amplitude and the profile of the two-frequency mutual coherence function. Also, the smaller the radius of the object, the larger the coherent bandwidth. The two-frequency mutual coherence function can be used to investigate the laser pulse scattering characteristics of arbitrarily shaped rough objects, provide theoretical basis for target recognition.
Optics Express 04/2011; 19(8):7007-19. · 3.59 Impact Factor
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ABSTRACT: Based on the theory of Kirchhoff approximation, the explicit expression of the fourth order moment of the field scattered from a homogeneous, isotropic and zero-mean Gaussian fluctuating rough surface whose irregularities are small compared to the incident wavelength have been driven. In this paper, the attention is strictly paid to the scattered field produced by one-dimensional rough surfaces. The statistical properties of the intensity of the backscattered field closely dependent on the wavelength have been investigated and the numerical results and some relating analysis have been given.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
