针对经典视距模型对于三代与超二代像增强器的直视型微光夜视系统评价方面缺乏差异性，模拟仿真结果在10^-4 lx超低照度下不甚理想这一问题，对现有的经典视距模型进行了三个方面的优化：在系统的传递函数模型加入了人眼的传递函数；基于光阴极与景物的光谱匹配修正了景物在光阴极产生的平均光电子数和光电子对比度公式；在噪声来源中加入了背景噪声项.进而推导出改进的视距模型，并通过头盔系统的实际外场实验结果进行了验证.结果表明，改进的视距模型能有效分辨出超二代和三代夜视系统的识别距离的差异，计算结果更接近实际测量结果.

There is no difference in the evaluation of the direct-view low-light-level night vision system for the three-generation and super-second generation image intensifiers. The simulation results are not ideal under the ultra-low illumination of 10^-4 lx. Therefore, three optimizations were made for the model: the transfer function of the human eye was added into the transfer function model of the system; the average photoelectron number and photoelectron contrast formula generated by the scene at the photocathode were corrected based on the spectral matching between the scene and the photocathode; the background noise term was added to the noise source. The improved apparent distance model was verified by the experimental results of the helmet system in field conditions. The results show that the improved model can effectively distinguish the difference between the recognition distances of the super-second generation and three-generation night vision systems, the calculation results are closer to the actual measurement results.