Babinet–Soleil compensator
The Babinet–Soleil compensator is a continuously variable, zero-order retarder. It consists of two birefringent wedges, one of which is movable, and another is fixed to a compensator plate. The orientation of the long axis of the wedges is perpendicular to the long axis of the compensator plate.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Babinet-Soleil.png/400px-Babinet-Soleil.png)
References
- Iizuka, K (2002). Elements of Photonics, John Wiley & Sons.