| 摘要 |
PURPOSE:To adjust easily the angle of a critical angle prism and to improve the precision by allowing the prism assembly formed by uniting a polarizing prism and the critical angle prism together to turn around an axis parallel to the optical axis of return light incident to an optical surface of the critical angle prism. CONSTITUTION:The polarizing prism 23 and critical angle prism 28 are adhered in one body in crossing relation, and this prism assembly is made turnable around the axis O parallel to the optical axis of return light incident to the optical surface 28a of the critical angle prism 28. Consequently, the angle of incidence of the optical axis of the return light from an optical disk to the optical surface 28a of the critical angle prism 28 is adjusted. Thus, the angle relation between the polarizing film 24 of the polarizing prism 23 and the optical surface 28a of the critical angle prism 28 is fixed, so almost no deviation due to temperature fluctuations is caused. Therefore, the angle of the critical angle prism 28 is adjusted easily and speedily and the precision after the adjustment is held for a long period.
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