An Etymological Dictionary of Astronomy and Astrophysics
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A → transparent → crystalline substance (such as calcite, quartz, and tourmaline) that is → anisotropic relative to the → speed of light. A ray incident normally on such crystals is broken up into two rays in traversing the crystal, → ordinary ray and → extraordinary ray.

→ doubly; → refracting; → crystal.

1) The action or result of the verb → refract.
2) Participial adjective of → refract.

From → refract + → -ing.

A prism that is used as a dispersing element in a spectrograph.

→ refracting; → prism.

A telescope in which an image is formed by the refraction of light through a lens or lens system.

→ refracting; → telescope.