随着红外测温技术的快速发展, 红外测温仪在军事及民用领域得到广泛应用, 对测量准确度的要求提升到了新的高度。 面源黑体辐射源作为非接触测温设备校准的核心装置, 近年来受到广泛的关注。 发射率是描述辐射源性能的重要指标, 目前缺少黑体表面形貌对发射率影响的研究。 面源黑体发射率主要由表面凸锥结构和涂覆涂层决定。 为设计出高发射率面源黑体, 以具有凸锥结构的面源黑体为基础模型, 引入间距及涂层结构, 建立具有不同表面结构参数、 单元间距及涂层厚度的面源黑体模型, 设置基底材料为石墨, 涂层材料为氮化硅, 通过有限元软件得到仿真模型的反射率, 利用反射率反演得到其发射率, 绘制3~14 μm范围内的光谱发射率曲线; 研究面源黑体表面的电场分布情况。 分析结构单元的宽高比、 涂层厚度和结构单元间距等参数对发射率的影响。 结构单元高度与发射率成正比、 较窄的宽度对发射率有优化作用, 发射率随宽高比的减小而增大。 涂层结构改变了光谱发射率的下降趋势, 在11 μm后发射率上升, 发射率随厚度增加而增大; 单元间距变化与发射率成正比。 设置初始面源黑体单元结构高度为10 μm、 宽度为1 μm, 在该模型上依次添加2 μm涂层及2 μm间距结构, 进行仿真计算。 优化后黑体辐射源在长波段具有优势, 在3~14 μm波段内光谱发射率稳定, 最低值为0.966; 电场分布图表明了三种结构因素对面源黑体表面能量的影响, 优化得到的模型参数可用于面源黑体的实际制造。 仿真结果表明较小宽高比、 较厚涂层、 较大间距具有提高发射率的能力, 为制造高辐射性能面源黑体辐射源提供了理论参考。

With the rapid development of infrared temperature measurement technology, infrared thermometer plays an important role in both military and civil fields, so it calls for higher measurement accuracy. It should be observed that a couple of years have witnessed an increasing number of people who are concerned that radiation source consisting of area blackbody is the vital device to calibrate the non-contact thermometer. Spectral emissivity is an essential parameter to describe the performance of radiation sources, while there is less research involved in the effect of blackbody surface topography on emissivity. It is manifested that the emissivity of the area blackbody is related to the combination structure of the evagination cone and coating. In order to design a remarkable performance area blackbody with high emissivity, the paper takes the area blackbody with convex cone structure as the basic model, adding components of spacing resembling grating and coating, and establishes an area blackbody model with different structural parameters, cell spacing and coating thickness. Graphite and silicon nitride is set as the base material and the coating material, respectively. Reflectivity is obtained by measuring the variation of reflected radiation with related soft. Then the emissivity is calculated through the relationship between reflectivity and emissivity, drawing the curve of spectral emissivity in the range of 3~14 μm. According to the electric field distribution of the surface and curve of spectral emissivity, we analyze the influence of parameters such as the ratio of width to length, coating thickness and spacing on emissivity. It is shown that the height of the structure unit is proportional to spectral emissivity, and emissivity is optimized due to narrower width, which increases as the ratio of width to length decreases. The dropping trend of spectral emissivity is changed by the coating structure in which the emissivity increased at the wavelength above 11 μm, and the emissivity rise with the increasing coating thickness. What's more, the spacing structure is proportional to emissivity. The height and width of the unit structure of the original area blackbody are set at 10 and 1 μm, respectively. A coating with a thickness of 2 μm and a spacing structure with a width of 2 μm are sequentially added to the original model for simulation calculation. The optimized blackbody radiation source has advantages in the long wavelength band, and the spectral emissivity with a minimum value of 0.966 is stable in the range of 3~14 μm. The electric field distribution shows the influence of these structural factors on the surface energy of the area blackbody, and the optimized model parameters can be used to manufacture a realistic area blackbody. Simulation results illustrate that a smaller aspect ratio, thicker coating and larger spacing improve spectral emissivity, which provide a theoretical reference for the manufacture of radiation sources consisting of area blackbody with high radiation performance.