Cassegrain telescope

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Cassegrain telescope

A compound reflecting telescope designed, according to some sources, by a French sculptor, Sieur Guillaume Cassegrain, in 1672. Others attribute its invention to a 17th-century astronomer known to us only as N. Cassegrain. It is similar to the Gregorian telescope but has a secondary mirror with a convex hyperboloid shape mounted inside the focal plane of the primary mirror. The telescope has a small field, limited mainly by coma, but is compact, portable, and easily mounted and thus very popular. Most large modern reflectors include this facility. See Cassegrain configuration; catadioptric telescope; Ritchey–Chrétien optics; Schmidt telescope.

Cassegrain telescope

[kas·gran ′tel·ə′skōp]
(optics)
A reflecting telescope in which a small hyperboloidal mirror reflects the convergent beam from the paraboloidal primary mirror through a hole in the primary mirror to an eyepiece in back of the primary mirror.
References in periodicals archive ?
Gray's 16-inch Dall-Kirkham Cassegrain reflector has a secondary mirror that is supported by an optical window, giving refractor-like images free of the diffraction spikes produced by the spider supports common to most reflectors.
I tested Nightscape at the f/4 Newtonian focus of my vintage 12(1/2)-inch classical Cassegrain reflector, using a Baader MPCC coma corrector to improve star images at the edges of the field covered by Nightscape's large chip.
Light diffracted by the spider supports of the secondary mirror of a Newtonian or Cassegrain reflector can also produce the appearance of a glow on the planet's nightside.
However, the club pays most expenses for operating the observatory and its two large telescopes--a 24-inch Cassegrain reflector, purchased with AAI funds in 1974, and a member-constructed 10-inch refractor, built in 1972.
DETAILS: 24-inch Cassegrain reflector at f/8 and SBIG ST-10XME.
6-meter (24-inch) Cassegrain reflector at f/8 and SBIG ST-10XME CCD camera.
In 1872 he completed a 28-inch Cassegrain reflector, which he used to photograph the first spectrum of a star, Vega.