摘要
本文证明了Gladstone-Dale折射度指示体可以用主轴为n—1的椭球近似表示,在主轴出露点二者重合,其余各处折射度指示体恒小于n—1椭球,最大向径差一般小于0.0008,最大(苏打石)为0.010.2V差一般小于2°,但有时可以较大。Gladstone-Dale公式可视为Lorentz-Lorenz公式的近似。Gladstone-Dale折射度指示体也可以近似代替按其它关系式所定义的折射度指示体,这就可以方便地用来讨论晶体的光学异向性。
The indicatrix of Gladstone-Dale refractivity is the one whose radius in a cer-tain direction equals n - 1 in this direction. It can be replaced by an ellipsoid whose principal axes are n - 1 The refractivity indicatrix is always smaller than the n ?l ellipsoid,but the difference is negligible. The radial difference can be cal-culated by an equation from which we can estimate that the maximum difference is usually below 0.0008. For most minerals the difference of 2V between the re-fractivity indicatrix and the n -1 ellipsoid is smaller than 2?but it may be quite large when a mineral has a strong birefringence and a small refractive index, and the 2V approaches 90? Gladstone - Dale equation can be regarded as an approxi-mation of Lorentz-Lorenz equation. Other equations including Lichtenecker equa-tion, Drude equation and Allen equation can also be substituted for by Gladstone-Dale equation. As a result of these approximations,if other refractivity indicatri-xes are to be defined, based on different equations, they will be in effect the same as the Gladstone-Dale refractivity indicatrix.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
1990年第2期159-168,共10页
Earth Science-Journal of China University of Geosciences
关键词
折射度
指示体
晶体光学
异向性
optical crystallography, optical anisotropism, refractivity indica-trix, Gladstone-Dale equation, Lorentz-Lorenz equation.
