Cassegrain telescope

American  

[kas-uh-greyn] / ˈkæs əˌgreɪn /

noun

Astronomy.

1. a reflecting telescope in which the light, passing through a central opening in the primary mirror, is brought into focus a short distance behind it by a secondary mirror.

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Cassegrain telescope British  

/ ˈkæsɪˌɡreɪn /

noun

1. an astronomical reflecting telescope in which incident light is reflected from a large concave paraboloid mirror onto a smaller convex hyperboloid mirror and then back through a hole in the concave mirror to form the image

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Etymology

Origin of Cassegrain telescope

1805–15; named after N. Cassegrain, 17th-century French scientist, its inventor