Glan-Thompson prism
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A Glan-Thompson prism is a type of polarizing prism similar to a Nicol prism. It consists of two right-angled calcite prisms that are cemented together by their long faces. The optical axes of the calcite crystals are parallel and aligned perpendicular to the plane of reflection. Birefringence splits light entering the prism into two rays, experiencing different refractive indices; the p-polarized o-ray is totally internally reflected from the calcite-cement interface, leaving the s-polarized e-ray to be transmitted. The prism can therefore be used as a polarizing beam splitter. Traditionally Canada balsam was used as the cement in assembling these prisms.
Compared to the similar Glan-Foucault prism, the Glan-Thompson has a wider acceptance angle, but a much lower limit of maximum irradiance (due to optical damage limitations of the cement layer).
