大散射角散斑场中有关相位奇异新特性的研究

利用散斑场和参考光的干涉提取散斑场复振幅和相位, 研究了不同散射角下散斑场相位的分布规律以及相位奇异处光波复振幅实部零值线和虚部零值线夹角、光强等值线离心率的统计特性. 在大散射角散斑中发现了一种新的相位奇异现象, 即相位奇异线; 研究了相位在跨越奇异线时的突变规律及涡旋状相位的分布特征, 发现在相位奇异线处存在着呈双曲线或抛物线状的光强等值线.

New features of the speckle phase singularity produced in large angle scattering

Based on the interference patterns of the speckle field and the reference beam recorded by the charge-coupled device, and the digital Fourier transform technique, the complex amplitudes and phases of speckle field produced at different scattering angles are extracted. The phase distribution and the statistical properties at the singular point, such as the angle between two zero-contour lines of real part and imaginary part of the complex amplitude, the eccentricity of the intensity contours, etc. are studied. We find that there are some special properties of phase singularity when the scattering angle is large enough. With the increase of the scattering angle, great changes have taken place in the spatial distributions of the amplitude and the phase, and the probability of the angle between two zero-contour lines of real part and imaginary part is close to a smaller value, and the average eccentricity of the intensity contours around the phase singularity gradually increase. Moreover, the most interesting thing is that the eccentricity is probably greater than 1 in large anger scattering. The phase singular line as a new kind of phase singularity is found at a large scattering angle; the phase mutation rules and the vortex distribution characteristics of the phase on both sides of the phase singular line are investigated, and the hyperbolic or parabolic shape intensity contour around the phase singular line is found.