Nicol prism

A Nicol prism ( after William Nicol, 1828) is a polarization prism which is composed of two birefringent prisms.

The prisms are usually made of calcite. They are assembled to form a parallelepiped, that the optical axis of the crystal is parallel to the cut surface. The refractive index of the adhesive is between the values ​​for calcite. Traditionally has been used as an adhesive Canada balsam, which has a refractive index of. Today, synthetic adhesives are common.

The angle of the separation surface to the beam trajectory is chosen so that the ordinary ray at the boundary between the calcite and adhesive undergoes total reflection. The extraordinary beam enters the other hand, largely through the interfaces between calcite and glue through. The result is two mutually perpendicular polarized light exiting rays. The ordinary ray passes perpendicular to the optical axis ( TE ) of polarized. The extraordinary ray which exits from the second calcite is polarized parallel to the optical axis ( TM ).

Nicol prism were used for a long time as a polarizer in polarization microscopy. Today, they are replaced by polarizing films. These are cheaper and take up less space.