Glan Thompson polarizer Beamsplitter Cube is made of two Calcite prisms or two a-BBO prisms cemented together .It have high extinction ratio below 5×10-5 is obtained. The Calcite type can be used in the range of 350-2300nm, and a-BBO crystal usable in the range of 220-900nm. It can separate the nature light for O polarized light and E polarized light, and the separate angle is 45°. Since there are two ports, the prism can also be used by replacing the input and output direction
The polarizers have the widest field angle of any design. The standard form of this polarizer with 2.5:1 length to aperture ratio has a full acceptance cone angle of more than 15 °@589nm, symmetric about the input axis, while the long form with 3:1 ratio has a field angle>26°. The polarized field F1 and F2 of all these is shown in the plot below.