グランテイラープリズム

A Glan-Taylor prisms is an air-spaced prism, which is used as a polarizer or polarizing beam splitter. It is one of the most common types of modern polarizing prism. It was first described by Archard and Taylor in 1948.

The prism is made of two right-angled prisms of (or sometimes other birefringent materials) which are separated on their long faces with an air gap. The optical axes of the calcite crystal are aligned parallel to the plane of reflection. Total internal reflection of s-polarized light at the air-gap ensures that only p-polarized light is transmitted by the device. Because the angle of incidence at the gap can be reasonably close to Brewster’s angle, unwanted reflection of p-polarized light is reduced. Noted that the transmitted beam is 100% polarized, but the reflected beam is not. The sides of the crystal can be polished to allow the reflected beam to exit, or can be blackened to absorb it. The latter reduces unwanted Fresnel reflection of the rejected beam. However, the Glan-Taylor type prisms have a smaller field angle, which is not symmetric about the longitudinal axis of the prism. The total field angle is 8 degree, but the symmetric field angle is only 5.5 degrees.