Roy S, Bang S Y, Modest M F, Stubican V S
Appl Opt. 1993 Jul 1;32(19):3550-8. doi: 10.1364/AO.32.003550.
A new apparatus to measure spectral,<directional reflectivities of solids for temperatures up to 1100 °C is developed. Reflectivities of two ceramic materials, silicon nitride (Si(3)N(4)) and silicon carbide α-SiC, are measured at wavelengths between 9 and 11 µm (the operating range of tunable CO(2) lasers) for various temperatures, angles of incidence, and for two types of polarization, the electric vector perpendicular and parallel to the plane of incidence. Reflectivities are measured by comparing the power of the beam reflected from the sample (heated in the furnace) with that of the incident beam. This experimental setup is limited to relatively specular surfaces (with a collection half-angle of 15°). The measurements show that the reflectivity of α-SiC at room temperature rises sharply near ~10.2 µm because of the presence of a 12.6-µm reflection band (restrahlen band), and the occurrence of this phenomenon gradually shifts to longer wavelengths as the temperature is raised to 1000 °C. At 10.6 µm, where most CO(3) lasers operate, the reflectivity of SiC diminishes rapidly as the temperature is raised. Si(3)N(4) has two restrahlen bands on both sides of 9.9 µm at room temperature that gradually shift to longer wavelengths with temperature. However, the decrease in reflectivity of Si(3)N(4) with temperature at 10.6 µm is very small.
开发了一种新装置，用于测量温度高达1100°C的固体的光谱定向反射率。在9至11微米波长（可调谐CO₂激光器的工作范围）下，针对各种温度、入射角以及两种偏振类型（电矢量垂直和平行于入射平面），测量了两种陶瓷材料——氮化硅（Si₃N₄）和碳化硅α-SiC的反射率。通过比较从样品（在炉中加热）反射的光束功率与入射光束功率来测量反射率。该实验装置限于相对镜面的表面（收集半角为15°）。测量结果表明，由于存在12.6微米的反射带（剩余射线带），室温下α-SiC在~10.2微米附近的反射率急剧上升，并且随着温度升高到1000°C，这种现象的发生逐渐向更长波长偏移。在大多数CO₂激光器工作的10.6微米处，SiC的反射率随着温度升高而迅速降低。室温下，Si₃N₄在9.9微米两侧有两个剩余射线带，它们随着温度逐渐向更长波长偏移。然而，Si₃N₄在10.6微米处的反射率随温度的降低非常小。
