针对编码掩模红外成像系统提出了一种建模方法。该模型将成像系统视为由两个功能部分组成，一部分为编码掩模与理想聚焦透镜的理想成像，另一部分为实际透镜自身的非理想成像。据此，系统点扩散函数可以由掩模结构的衍射模式和实际透镜的点扩散函数联合表示。此外，文中对视场内倾斜入射平面波的成像结果进行分析，从而得到了视场内的点扩散函数的变动情况。由码型及相应点扩散函数的指标评价结果可以看出，文中提出的基于Dammann阵列的码型结构对直接成像和图像还原处理具有较为平衡的性能。实验表明，对于编码掩模直接成像系统的码型中应当具有较多的随机性结构，而对于能够做进一步图像还原处理的系统码型中应当具有较多的周期性结构。

The model for infrared coded mask imaging systems was presented. It was composed with two functional components, the coded mask imaging with ideal focused lenses and the imperfection of practical lenses. The system′s point spread function(PSF) can then be represented by the diffraction pattern of the mask and the PSF of the practical lenses. The imaging results with inclined plane waves were also analyzed to achieve the variation of PSF within the view field. According to indices for mask pattern evaluation and system′s PSF assessment, mask pattern we proposed based on Dammann grating had a balanced performance for direct imaging and imaging reconstruction. Experiment shows that mask pattern for direct imaging should have more random structures, while more periodic structures in system with image reconstruction.