Selection of a suitable surface emissivity for coatings and assessment of thermal camouflage performance via spectral radiance analysis.

内容摘要

The contrast between a target and its background is particularly pronounced in the infrared spectral region, which has led modern surveillance systems to widely adopt thermal imaging technology for detection and identification purposes. To mitigate detectability under thermal infrared observation, thermal infrared camouflage has emerged as an active research field with broad practical applications. Two principal approaches are commonly employed: enhancing the thermal insulation and heat-shielding performance of camouflage materials and tailoring their surface emissivity to achieve radiative compatibility with the surrounding environment. This study elucidates the fundamental mechanism of thermal infrared camouflage by analyzing the relationship between the actual surface temperature of an object and its apparent temperature measured by a thermal imaging system. On this basis, a computational framework is developed to determine the appropriate surface emissivity of camouflage coatings for ground vehicles. The suitable surface emissivity is theoretically derived as a function of background temperature, atmospheric temperature, and target temperature. The results indicate that an emissivity range of 0.66-0.70 is suitable for effective thermal infrared camouflage. The proposed approach is experimentally validated through field observations using a thermal imaging system and spectral emission data acquired by a spectroradiometer (SR-5000N) in both the mid-wave infrared (MWIR) and long-wave infrared (LWIR) bands. Experimental results show that when the average surface emissivity of the coating over the 3-14 µm spectral range is approximately 0.7, the spectral radiance contrast of the non-camouflaged target is nearly three times greater than that of the camouflaged target relative to the background across both spectral regions. These findings demonstrate that an appropriate design of surface emissivity significantly enhances thermal infrared camouflage performance. Furthermore, the evaluation method based on spectral radiance analysis provides a reliable and meaningful framework for the design and assessment of thermal infrared camouflage systems.