A birefringent polarizer constructed from two triangular calcite prisms oriented with their optical axes parallel to the entrance face. The prisms are separated by a thin air gap where total internal reflection rejects the ordinary ray, transmitting only the extraordinary ray. It handles high power well because the rejected beam escapes without hitting any optical cement.
Heard on the job
The unexpanded YAG beam will burn right through cement, so use a Glan-Foucault prism for the isolation stage.
Also heard as
- Glan-air prism
Do not mix it up with
- Glan-Thompson prism: A Glan-Foucault uses an air gap and handles higher power, while a Glan-Thompson is cemented and has a wider acceptance angle.