| 摘要 |
PROBLEM TO BE SOLVED: To obtain the polarizer which has a high extinction ratio and high durability to a high-output laser is stably usable for a long period and superior in reliability by specifying the number density of metal particles and also specifying the heat conductivity of a substrate and a dielectric layer. SOLUTION: The polarizer 1 is provided with a polarizing layer 3 on at least one main surface of a translucent dielectric substrate 2. The polarizing layer 3 is formed by laminating island-shaped metal thin-film layers 4 wherein many metal particles 4a having shape anisotropy (light absorption anisotropy) are dispersed and translucent dielectric layers 5 alternately on the substrate 2. The substrate 2 and dielectric layers 5 have >=1.0 W/(mK) heat conductivity and the dielectric layers 5 are formed preferably of the same kind of material as the substrate and, for example, borosilicate glass is used. The number density of the metal particles 4a in the metal particle layers 4 is 2 to 37 particles perμm<2> in the substrate surface direction.
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