红外探测器内部颗粒物对图像的影响

Influence of the particulates inside the infrared detector on the image

在高灵敏度的红外光学系统中,来自系统内部的热辐射是影响系统探测性能的重要因素之一。污染颗粒物通常是杂散辐射的主要来源,除了光学元件的表面污染,探测器内部也会存在污染颗粒物。文中主要研究探测器内部颗粒物对焦平面光场分布产生的影响。根据红外辐射及散射原理建立了相应的理论模型,对探测器内部不同温度、不同位置的颗粒物在焦平面上形成的光场分布进行了仿真计算和对比分析,并进行了实验验证。结果表明,探测器内部如有颗粒杂质,在一定的使用环境下,可在探测器焦面上产生黑斑、白斑、黑点白斑等异常现象,而这些异常光场分布会对场景中的红外目标物产生干扰,造成误判,从而影响对目标的准确识别。因此应采用措施以保证探测器内部的洁净度,防止颗粒物的产生。

In the high sensitive infrared optical systems, the self-generated thermal radiation is one of the important factors for the detective property. Particulate contaminants are usually the main source of stray radiation. Besides the surface contaminants, there may be particulates within the detector. The influence on the luminous flux distribution on the image plane of the particulates inside the detector was studied in this paper. According to image plane＇s luminous flux distribution of the particulates inside detector with different temperature from different distance to image plane, relevant theoretical model was built up based on theory of infrared radiation and scattering, which was validated by the corresponding experiments. The results indicate that if there are particulates inside the detector used at the condition of vibration environment, they will form exception image such as black spot and white spot and combination with each other on the image plane. These abnormal distributions of luminous flux disturb the infrared targets in the effective field of view, resulting in false judgments. Thus, the veracity of the identification for infrared targets degraded obviously. Therefore it is of critical importance to keep the inside of the detector clean and prevent the generation of the particulates.