Grum F, Luckey G W
Appl Opt. 1968 Nov 1;7(11):2289-94. doi: 10.1364/AO.7.002289.
Specially prepared barium sulfate powders and coatings of these powders with polyvinyl alcohol have been used as working standards of reflectance and for coating integrating spheres. These materials are satisfactory for use in the wavelength range 0.20-2.00 micro. Since the refractive index of barium sulfate is rather low, it is necessary to use fairly thick layers in order to obtain good results. The absolute value of luminous reflectance of the barium sulfate powder, described in this paper, is 0.995 +/- 0.001, and that of the paint, when properly applied, is 0.992 +/- 0.001. The spectral reflectance of this material is higher than that of magnesium oxide, particularly in the uv region of the spectrum. By using barium sulfate as reference standard and as a coating on the integrating spheres of spectrophotometers, it is now possible to measure spectral reflectance reliably in the uv region to 200 nm. Because the reflectance of barium sulfate paint is significantly greater than that of magnes um oxide in the shortwave region, there is a corresponding gain in instrument sensitivity when barium sulfate is used as a sphere coating and as a comparison material.
特制的硫酸钡粉末以及这些粉末与聚乙烯醇的涂层已被用作反射率的工作标准以及用于涂覆积分球。这些材料适用于0.20 - 2.00微米的波长范围。由于硫酸钡的折射率相当低，为了获得良好的效果，有必要使用相当厚的层。本文所述硫酸钡粉末的发光反射率绝对值为0.995±0.001，涂料在正确涂覆时的发光反射率为0.992±0.001。这种材料的光谱反射率高于氧化镁，特别是在光谱的紫外区域。通过使用硫酸钡作为参考标准并作为分光光度计积分球的涂层，现在可以在紫外区域可靠地测量至200纳米的光谱反射率。由于硫酸钡涂料在短波区域的反射率明显大于氧化镁，当硫酸钡用作球涂层和比较材料时，仪器灵敏度相应提高。
