Nicol prism

Description

A device for producing plane-polarized light. Invented by William Nicol about 1870, a Nicol prism is composed of two flawless pieces of optical grade calcite (Iceland spar). The pieces are cut and ground to form matching prisms. One prism is placed upside down on the other, then they are cemented together with colorless Canada balsam. When unpolarized light is passed through the first prism, it is separated into two components with different refractive indices (1.685 and 1.486). Since Canada balsam has a refractive index of 1.53, the light ray with the higher refractive index (the ordinary ray) is reflected back into the first prism while the light ray with the lower refractive index (the extraordinary ray) passes through to the second prism. The light that emerges from the second prism is polarized in one direction.

Synonyms and Related Terms

Nicol'sches Prisma (Deut.); prisme de Nicot (Fr.); Nicol polarizer;