The Cassegrain reflector is a combination of two coaxial reflectors used in Cassegrain telescopes and radio antennas.First developed in 1672 by Laurent Cassegrain, this reflector is a combination of a primary concave mirror and a secondary convex mirror, both aligned symmetrically about the optical axis. The primary mirror usually contains a hole in the centre thus permitting the light to reach an eyepiece, a camera, or a light detector. The primary mirror is parabolic while the secondary mirror is hyperbolic.
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