| 摘要 |
PURPOSE:To use the titled prism for various multi-port type optical devices by a simple constitution, by separating the light beams, respectively, and thereafter, emitting them from the same part of a second double refraction plate, when two parallel light beams have been made incident from a first double refraction plate. CONSTITUTION:The first double refraction plate 11 and the second double refraction plates 12, whose incident/emitting surfaces have been polished in parallel are placed in parallel to each other. On prescribed positions between both the double refraction plates 11, 12, compensating plates 13, 14 for rotating the plane of polarization of a transmission light by 90 deg. are provided. This prescribed position is on one optical path in a linearly polarized light component having each orthogonal plane of polarization which has been separated at every light beam, when two parallel light beams have been made incident on the first double refraction plate 11. Thickness of the second double refraction plate 12 and a distance between the two parallel light beams are set so that the separated linearly polarized light component is emitted from the same part of the second double refraction plate 12 with regard to the two light beams. In such a way, the double refraction plate having a high polarized light separation degree extending over a wide wavelength band can be applied to an optical device of a multi-port type.
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