Abstract—

The features of the development and application of the procedures for measuring refractive coefficients based on multiangle spectrophotometric methods of reflection are considered. The effect of the shape, size, and surface treatment of the samples on their spectral dependences of the reflection is described. The possibility of determining the refraction coefficients by two spectrophotometric methods is demonstrated: using the spectrum of reflection from a single face at a small angle of light incidence close to normal and using the method of reflection of light incident at the Brewster angle. The method of reflection at an incidence angle close to normal can be applied in the case of a nonabsorbing sample characterized by an extinction coefficient not exceeding 10^–6 to 10^–4. This is a so-called express method, because it allows us to immediately obtain the dispersion dependence of the refraction coefficient. The method allows measuring the dispersion dependences of the refraction coefficients for the samples whose shape excludes multiple reflections: plates with one polished side, plates with a large thickness polished on two sides, and prisms or plates with non-plane-parallel faces. In measurements using the Brewster method, there are no requirements for the value of the extinction coefficient of the sample (absorption) and we can use a sample of any shape, including plates with a small thickness polished on both sides. However, the resulting values of the refraction coefficients are discrete, and a large array of measurement results must be accumulated. The determined measurement accuracy of both methods was Δ = ±0.001 at a confidence probability of P = 0.95. Applicability of the spectrophotometric methods of measurement is demonstrated for the samples of a gadolinium aluminum gallium garnet, which is a crystal of a cubic system and is characterized by a single refraction coefficient. It is shown that the values of the refraction coefficients obtained by these two methods agree well within the measurement accuracy.

中文翻译：

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反射光的多角度分光光度法测定折光系数

摘要—

考虑了基于多角度分光光度法反射的折射率测量程序的开发和应用特点。描述了样品的形状，大小和表面处理对其反射光谱依赖性的影响。证明了通过两种分光光度法确定折射系数的可能性：使用来自单个面的反射光谱以接近法线的小入射角和使用以布儒斯特角入射的光进行反射的方法。对于消光系数不超过10 ^–6至10 ^–4的非吸收性样品，可以采用接近法线入射角的反射方法。这是所谓的快速方法，因为它使我们可以立即获得折射率的色散依赖性。该方法可以测量形状不包含多次反射的样品的折射率的色散依赖性：具有一侧抛光面的板，两侧具有较大厚度抛光的板以及具有非平面平行面的棱镜或板。在使用Brewster方法进行的测量中，对样品的消光系数（吸收）的值没有要求，我们可以使用任何形状的样品，包括在两面上抛光的小厚度板。然而，所得的折光系数值是离散的，并且必须累积大量的测量结果。P＝ 0.95。证明了metric铝镓石榴石样品的分光光度法测量方法的适用性，which铝镓石榴石是立方晶系晶体，具有单一折射率。结果表明，这两种方法得到的折光系数值在测量精度内吻合良好。