You Kewei, Zhang Yanli, Zhang Xuejie, Sun Mingying, Zhu Jianqiang
Appl Opt. 2017 Jun 1;56(16):4835-4842. doi: 10.1364/AO.56.004835.
The structural evolution of the axial intensity distribution during hot image formation perturbed by a small circular optical obscuration is investigated in detail under different conditions. An analytic expression is derived for the axial intensity distribution around the conjugate plane by assuming the thickness of the nonlinear medium to be infinitely small. In view of the analysis of the axial intensity oscillation, the expression can be extensively utilized to characterize the intensity maxima for a nonlinear medium with a finite thickness. The nonlinear medium thickness and obscuration size both have great influence on the magnitudes and distributed features of the intensity maxima, which initially vary from multiple ones with comparable intensities to ultimately a maximum of one obviously remaining. The reason for this phenomenon is that the nonlinear medium acts like a low-pass filter to the scattering field, and optical interference exists between the scattering and background field. Furthermore, a fixed expression of nonlinear medium thickness and obscuration size is obtained to determine the dividing point of the alterations of the hot image intensity distribution.
详细研究了在不同条件下，由小圆形光学遮挡扰动的热像形成过程中轴向强度分布的结构演变。通过假设非线性介质的厚度无限小，推导了共轭平面周围轴向强度分布的解析表达式。鉴于对轴向强度振荡的分析，该表达式可广泛用于表征具有有限厚度的非线性介质的强度最大值。非线性介质厚度和遮挡尺寸对强度最大值的大小和分布特征都有很大影响，其最初从具有可比强度的多个最大值变化到最终明显只剩下一个最大值。这种现象的原因是，非线性介质对散射场起到低通滤波器的作用，并且散射场与背景场之间存在光学干涉。此外，得到了非线性介质厚度和遮挡尺寸的固定表达式，以确定热像强度分布变化的分界点。
