红外光的角谱传输成像模型

An Imaging Model of Infrared Light Based on Angular Spectrum Transmission

提出了一种基于CFD网格和傅里叶光学方法的高速流场中红外光传输的计算模型。模型中划分的网格足够小,可认为一个网格单元是一个线性滤波器,最终将网格化的高速流场看作为由多个线性空间滤波器组成的一个空间滤波器。针对正入射情况,应用一种红外光对某流场进行了仿真计算,得到了几个流场的成像特性参数并生成了仿真图片。此模型结合傅里叶光学在频域内研究问题,可直接给出光学传递函数从而利于成像质量的评价。最后分析了它相对几何光学方法的几个优势及将它推广到斜入射情形的方法。

This paper advances a calculation model based on the computational fluid dynamics （CFD） and Fourier-optics method to study infrared light transmission in a hypersonic fluid filed. In this model, the filed is divided into many enough small grids. So we can consider one grid as a linear spatial filter （LSF） ,and regard the supersonic flows as the combination of many LSFs. The paper applies a kind of infrared light to calculate and emulate one fluid field in the case of vertical incidence, and gets some parameters of the fluid filed to estimate its imaging characteristic. This model, combining with Fourier optics and analyzing problems in frequency-domain, gives the optical transformation function （OTF） directly. So it is convenient to evaluate imaging quality of the fluid field to use this model. At last, this paper analysis the advances of this model compared with the geometrical optical method and the methods to gener- alize it in the case of oblique incidence.