连续照明时成像对比度与气象条件的关系

Dependence of image contrast by continuous illumination on weather

通过同轴激光连续照明成像模型分析了大气后向散射对成像对比度的影响,得出了考虑散射因素时成像对比度的计算公式。基于不同气象条件下大气粒子散射特点,讨论了霾和雾两种不同天气时成像对比度随照明距离的变化规律,并与实验结果进行了对比,计算结果与实验吻合较好。

Dependence of image contrast on atmospheric back scattering by continuous coaxial illumination is analyzed. As a result, several equations on imaging contrast are given and relation between image contrast and weather is studied. Scattering flux is calculated by Mie scattering theory on condition that relative scale and refractive index of the particles are known. Dependence of image contrast on weather is presented in this paper. Theoretical results accord with experiments and indicate it is impossible to obtain distinct image of target through long path of atmosphere under coaxial continuous illumination when visibility is not very well. So range-gated method is necessary in active imaging system.