偏光による宝石研究の基礎 : 5
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概要
- 論文の詳細を見る
The basic knowledge on the optical crystallograghy is introduced as a basis of investigation of gemstone. In this part, the phenomena concernig the optical activity of crystals, especially those of quartz are explained. The quartz plates cut perpendicular or nearly perpendicular to the optic axis give rise. to two circularly polarized or two elliptically polarized light wave, one right-handed the other left-handed. Therefore, the plate fails to show extinction between crossed polars even with the monochromatic light. By observing the {000l} plate with white light, the sense of rotation of the linearly polarized light are readily distinguished by the order of succession of the observed colour on rotating the analyzer. The most salient characteristics of the interference figure of quartz is the disappearence of isogyres at the central portion of the conoscopic field. When the 1/4 λ plate is inserted, right or left-handed spiral can be seen. The sense of the spiral depends upon the rotation sense of the linearly polarized light in quartz as well as the insertion position of the 1/4 λ plate.
- 宝石学会(日本)の論文
- 1977-10-15