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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.

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of Cassegrain telescope

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

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.