Research on the influence of different pyramid array structures on plane blackbody emissivity

Abstract

The plane blackbody radiation source is pivotal to the infrared remote sensing detection system, with emissivity serving as a critical metric for its performance evaluation. This metric is predominantly influenced by the surface structure and coating properties. To improve emissivity, existing works have utilized pyramid structures to expand the contact area between the radiation surface and light, thereby augmenting light absorption. Nonetheless, there is relatively little research exploring the impact of pyramid structure on emissivity, leading to a scarcity of related emissivity data for plane blackbody. In this paper, we explored the impact on the blackbody emissivity induced by different pyramid structures, including the triangular pyramid array (TPA), the quadrangular pyramid array (QPA), the pentagonal pyramid array (PPA), and the hexagonal pyramid array (HPA). Also, the effects involving coating properties, the base-height ratio of the pyramid, and reflection characteristics on emissivity were investigated based on the Monte Carlo Method. Then, the specimens with diffuse reflection (DR) and near-specular reflection (NSR) were fabricated and tested experimentally. The uncertainties of simulation and experiment were maintained below 0.21 % and 0.50 %, respectively. Experimental results are well aligned with the corresponding simulation results, indicating that the normal emissivity of the TPA blackbody is 0.12 % higher than the QPA blackbody, and the directional emissivity uniform of the TPA blackbody is superior to that of the QPA blackbody for the DR model in the 8–14 μm waveband. Furthermore, the temperature field distributions of radiation surface for TPA and QPA blackbody were analysed, noting a maximum temperature difference of 50 mK and 30 mK, respectively. This paper provides experimental support and design references for further improving the emissivity of plane blackbodies.