After the three-dimensional self-affine fractal random surface simulation, we use the optical scattering theory to calculate the deep Fresnel region speckle (DFRS) under consideration of the more strict shadowing effect. The evolution of DFRS with the scattering distance and the intensity probability distribution are studied. It is found that the morphology of the scatterer has an antisymmetric relationship with the intensity distribution of DFRS, and the effect of micro-lenses on the scattering surface causes the intensity probability distribution of DFRS to deviate from the Gaussian speckle in the high light intensity area.

在计算鬼成像(Computational ghost imaging，CGI)系统中，可以通过估计重构图像的模糊程度获取目标的轴向深度。但该方法易受到背景噪声干扰，且要求像质评价函数有较长的工作距离，导致所需的采样次数较高，限制其实用性。针对这一问题，提出了一种基于自适应对焦窗口的目标深度估计方法。首先根据评价函数的整体特征划分搜索区间，然后在给定区域内对目标实际轴向深度进行迭代搜索。在迭代过程中，通过设计自适应窗口，有效减少背景区域的同时，也保证了窗口内目标的完整性。实验结果表明：该方法大幅降低了评价函数所需的必要工作距离，使其在欠采样条件下同样适用，也减小了背景噪声对评价函数的影响，增强了算法的鲁棒性，进一步完善了基于计算鬼成像系统的深度估计方法。