The Sénarmont prism is a type of

polariser A polarizer or polariser is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. It can filter a beam of light of undefined or mixed polarization into a beam of well- ...

. It is made from two

prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...

s of a

birefringent Birefringence is the optics, optical property of a material having a refractive index that depends on the Polarization (waves), polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or ...

material such as

calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scra ...

, usually cemented together. The Sénarmont prism is named after

Henri Hureau de Sénarmont Henri Hureau de Sénarmont (6 September 1808 – 30 June 1862) was a French mineralogist and physicist. He was born in Broué, Eure-et-Loir. From 1822 to 1826, he studied at the École Polytechnique in Paris, then furthered his education at the � ...

. It is similar to the Rochon and Wollaston prisms. 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

External links

An article by CVI (optics manufacturer) about different types of polariser
BROKEN LINK left in for now in the hope of fixing it later -->

Olympus Microscopy primer on polarising prisms, but note labelling error in the figure for the Sénarmont prism. {{DEFAULTSORT:Senarmont Prism Prisms (optics) Polarization (waves)