doubly refracting crystal
bolur-e šakst-e dotâyi
Fr.: cristal à double réfraction
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.
Fr.: réfraction; à réfraction
manšur-e šekastgar (#)
Fr.: prisme réfractant
A prism that is used as a dispersing element in a spectrograph.
teleskop-e šekasti (#), durbin-e ~ (#)
Fr.: lunette astronomique
A telescope in which an image is formed by the refraction of light through a lens or lens system.