Cassegrain telescope
noun
Cas·se·grain telescope
| \ ˈka-sə-ˌgrān-
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variants:
or less commonly Cassegrain
or Cassegrainian telescope \ ˌka-sə-ˈgrā-nē-ən-
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Definition of Cassegrain telescope
: a reflecting telescope that has a paraboloidal primary mirror and hyperboloidal secondary mirror, is equivalent in its optical effects to a telephoto lens, and usually has the light brought to a focus through a perforation in the center of the primary mirror
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