Sénarmont prism

The Sénarmont prism is a type of polariser. It is made from two prisms of a birefringent material such as calcite, usually cemented together.^[1] The Sénarmont prism is named after Henri Hureau de Sénarmont. It is similar to the Rochon and Wollaston prisms.

Working principle of a Sénarmont prism

In the Sénarmont prism the s-polarized ray (i.e., the ray with polarization direction perpendicular to the plane in which all rays are contained, called the plane of incidence) passes through without being deflected, while the p-polarized ray (with polarization direction in the plane of incidence) is deflected (refracted) at the internal interface into a different direction. Both rays correspond to ordinary rays (o-rays) in the first component prism, since both polarization directions are perpendicular to the optical axis, which is the propagation direction. In the second component prism the s-polarized ray remains ordinary (o-ray, polarized perpendicular to the optical axis), while the p-polarized ray becomes extraordinary (e-ray), with a polarization component along the optical axis. As a consequence, the s-polarized ray is not deflected since the effective refractive index does not change across the interface. The p-polarized wave, on the other hand, is refracted because the effective refractive index changes upon changing from o-ray to e-ray.

The Sénarmont prism is similar in construction and action to the Rochon prism, as in both polarizers the ray that is not deflected is the o-ray after the internal interface, while the deflected ray is the e-ray. However, in the Rochon prism, it is the p-polarized ray that remains an o-ray on both sides of the interface, and is therefore not deflected, while the s-polarized ray changes from o-ray to e-ray and is therefore deflected.

References

1. Damask, JN (2005). Polarization Optics in Telecommunications. New York: Springer. ISBN 0-387-22493-9.

External links

• Olympus Microscopy primer on polarising prisms, but note labelling error in the figure for the Sénarmont prism.