Glan-type polarizers

Glan-type polarizers are based on birefringence phenomena in transparent crystalline material. Therefore, they are sometimes called as birefringence polarizers. These polarizers consists of two right-angle prisms separated by an air-gap to eliminate the adhesive and reduce laser damage. The angle of a boundary between the crystalline material and an air-gap is chosen so that the total internal reflection (TIR) for the ordinary wave occurs. The optical axes of prisms are aligned parallel to the plane of reflection of an ordinary wave. The reflected wave is absorbed in the housing, if it is Glan-Taylor polarizer, while the side surface of the Glan-laser polarizer material is polished and the housing has holes in order to allow the reflected beam to exit. Therefore, Glan-laser type polarizers are suitable for high-power applications. The reflected beam is partially polarized, therefore it cannot be used for polarization sensitive applications, while the transmitted beam has high extinction ratio for both Glan-Taylor and Glan-Laser polarizers. The drawback of Glan-type polarizers is that their acceptance angle is relatively low 6-7°.

4Lasers offer Glan-taylor and Glan-laser type polarizers made from alpha-BBO (UV), calcite (VIS to NIR) and YVO₄ (VIS to MIR) in black anodized aluminium mount. In order to optimize broadband transmission ratio single layer MgF₂ coatings are applied onto the Glan-laser polarizer optical surfaces.