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Determination of the optic axial angle of biaxial crystals in parallel polarized light
Published online by Cambridge University Press: 14 March 2018
Extract
It will in the first place be assumed for the sake of simplicity that the crystal to be investigated is immersed in a liquid having a refractive index as nearly as possible equal to the intermediate refractive index (β), so that light travelling along the optic axis t is not appreciably refracted on entering or leaving the crystal.
The observation is made in parallel ight between crossed nicols, which are rotated together till a position of extinction is reached, when the directions of vibration of the nicols wilI be parallel to those in the crystal. If the latter be now rotated on an axis parallel to one of these directions, it will in general show light throughout the revolution, except in the original position and that opposite to it. Occasionally, however, it will remain dark throughout; in that case the axis of rotation is the bisectrix of an optic axial angle.
- Type
- Research Article
- Information
- Mineralogical magazine and journal of the Mineralogical Society , Volume 14 , Issue 65 , May 1906 , pp. 157 - 159
- Copyright
- Copyright © The Mineralogical Society of Great Britain and Ireland 1906
References
Page 157 note 1 Or, to use more accurate language, light whose wave-surface is at right angles to a binormal.
Page 158 note 2 The ‘Universal-Drehapparat’ designed by C. Klein is well suited for use with this method ; see H. Rosenbuseh, ‘Mikroskopische Physiographie der Mineralien uud Gesteine,’ vol. i, part 1, 4th edition, by E. A. Wülfing, 1904, pp. 204-205.
Page 159 note 1 Becke, F., ‘Die Skiodromen,’ Min. petr. Mitt. (Tschermak), 1905, vol. xxiv, pp. 1-34 Google Scholar.
Page 159 note 2 Zeits. Kryst. Min., 1893, vol. xxii, p. 229; 1896, xxvi, p 225; 1896, xxvii, p. 337 ; 1898, xxix, p. 604.