基于光谱等分法估算复杂大气条件下红外成像系统的MRTD和作用距离

大气透过率是影响红外成像系统作用距离的重要因素。在大气传输过程中,红外辐射会受到大气分子的选择性吸收、散射以及复杂气象条件等的影响,这使得大气透过率成了一个复杂参量。用光谱等分法计算了大气透过率。首先利用MODTRAN软件计算一定距离时各谱线的大气透过率并建立数据库,然后按一定间隔等分光谱区域并调用数据库计算出各微小光谱区域内的大气透过率,最后将其代入模型用以计算红外系统的作用距离。与利用常数或者平均大气透过率的计算方法相比,该方法提高了计算结果的准确度。计算并分析了探测高度、湿度以及雾霾等复杂气象条件对红外成像系统MRTD和作用距离的影响。

Estimation of MRTD and Operating Distance of Infrared Imaging System under Complex Atmospheric Condition Based on Spectral Bisection Method

Atmospheric transmittance is an important factor affecting the operating distance of an infrared imaging system. In the process of atmospheric transmission, the infrared radiation may be affected by the selective absorption of atmospheric molecules, scattering and complicated weather conditions. This makes the atmospheric transmittance become a complex parameter. A spectral bisection method is used to calculate the atmospheric transmittance. Firstly, the MODTRAN software is used to calculate the atmospheric transmittance of each spectral line at a certain distance and establish a database. Then, the spectral region is divided at a certain interval and the atmospheric transmittance in each mini spectral region is calculated by calling the database. Finally, the calculated result is put into the model to calculate the operating distance of the infrared system. Compared with the calculation method which uses constant or average atmospheric transmittance, the calculation accuracy of the proposed method is improved. The effects of detecting height, humidity and fog on MRTD and operating distance of an infrared imaging system are calculated and analyzed.