激光定向干扰是对抗红外成像导引头的最有效方式，因此开展对红外成像 导引头的激光定向干扰研究具有重大意义。影响中波激光定向干扰效能的因素有很多，其中激光 到靶功率密度是影响定向干扰效能的重要因素。从大气传输对中波激光的衰减、导引头光学 系统对中波激光的光学增益、干扰激光光斑随干扰距离的变化等因素出发，研究了中波激光 的大气传输透过率与大气能见度及传输距离的关系，分析了大气湍流强度对激光传输总发散角 的影响。得到了3.8 μm激光对红外成像导引头的定向干扰模型，绘出了激光到靶功率密度、大 气能见度、大气湍流强度以及干扰距离之间的关系曲线，并通过外场实测对该模型进行了验证。结果表明，误 差在一个数量级之内，主要来自于远场激光光斑和传输路径上大气透过率的计算误差。该研究 对于激光定向干扰装备的论证和研制具有一定的参考价值。

Laser directional jamming is the most effective way to countermeasure infrared imaging seekers. Therefore, the research on laser directional jamming to infrared imaging seekers is of significance. There are many factors affecting the jamming effectiveness of mid-wave infrared laser directional jamming. Among those factors, the power density of laser falling on a target is the important affection factor. In view of the attenuation function of atmospheric transmission for mid-wave infrared laser, the optical gain of seeker’s optical system to the mid-wave infrared laser and the variation of jamming laser spot size with distance, the relationships of atmospheric transmission of mid-wave infrared laser with atmospheric visibility and transmission distance are studied. The affection of atmospheric turbulence on the total divergence angle of laser transmission is analyzed. The directional jamming model of 3.8 μm laser for infrared imaging seekers is obtained. The relationship curves among the power density of laser falling on a target, the atmospheric visibility, the atmospheric turbulence intensity and the jamming distance are drawn. The model is verified in outdoor. The result shows that it has an error greater than one order of magnitude which mainly results from the calculation error of far field laser spot and atmospheric transmittance. This research is of a certain referential value to the development of jamming equipment.