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Topic: Cassegrain reflector

	Schmidt Cassegrain and Newtonian reflector telescopes
		After reading a few lengthy debates between die-hard apochromatic refractor fans and Newtonian reflector devotees, I was pretty much sold on the reflector idea.
		Orion's line of reflectors had especially interested me, particularly since their introduction of the "Intelliscope," which was their "Classic" dob to which they had added digital setting circles.
		Another interesting aspect of their line of reflectors was the reported quality of the mass-produced Chinese mirrors they used.
	www.backyardvoyager.com /Equipment.html (334 words)

	Cassegrain telescope
		Light strikes the primary mirror, which reflects the image back to the smaller convex secondary mirror, which in turn reflects the magnified image through the center hole and on to the eyepiece.
		In an alternate scheme, called a modified Cassegrain, a small optical flat placed immediately in front of the primary brings the light out to the side of the telescope tube and eliminates the need for a perforated primary.
		The Dall-Kirkham telescope is a variant of the Cassegrain that uses a concave ellipsoidal primary mirror and a convex spherical secondary.
	www.daviddarling.info /encyclopedia/C/Cassegrain_telescope.html (221 words)

	Cassegrain reflector - Encyclopedia, History, Geography and Biography
		The Cassegrain reflector is a combination of two mirrors used in some telescopes, which are then known as Cassegrain telescopes.
		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.
		Of the three basic types of telescopes: refractors, reflectors and catadioptrics, the Cassegrain reflector falls under the category of reflecting telescopes but is also used in Catadioptric designs.
	www.arikah.net /encyclopedia/Cassegrain_telescope (635 words)

	Cassegrain reflector - Wikipedia, the free encyclopedia
		The Cassegrain reflector is a combination of two mirrors used in some telescopes, which are then known as Cassegrain telescopes.
		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.
		Another descendant of the Cassegrain design is the Ritchey-Chrétien telescope, which uses a hyperboloid primary and secondary mirror, eliminating the corrector plate needed for the catadioptic telescopes.
	en.wikipedia.org /wiki/Cassegrain_telescope (298 words)

	Satellite Receiving Antennas
		The reflector surface should appear to be continuous, with minimal variation from petal to petal and few noticeable bumps or waves along the surface of mesh antennas.
		There are two main design disadvantages, however: the feedhorn and feed support structure block part of the reflector surface and the feedhorn must look back at the dish at such an angle that it can also intercept noise from the "hot" earth located directly behind the reflector.
		The sub reflector deflects the microwaves back toward the center of the reflector, where the feedhorn is actually mounted.
	www.mlesat.com /antennas.html (2655 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: )
		A reflecting telescope (reflector) is an optical telescope which uses a combination of curved or plane (flat) mirrors to reflect light and form an image (catoptric), rather than lenses to refract or bend light to form an image (dioptric).
		He designed his reflector, which used a concave objective and a smaller "diagonal" mirror, in order to solve the problem of chromatic aberration, a serious degradation in all refracting telescopes before the perfection of achromatic lenses.
		Reflectors work in a wider spectrum of light since certain wavelengths are absorbed when passing through glass elements like those found in a refractor or catadioptric.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=reflecting_telescope (1048 words)

	Reflecting telescope - Wikipedia, the free encyclopedia
		A reflecting telescope (reflector) is an optical telescope which uses a combination of curved and plane (flat) mirrors to reflect light and form an image, rather than lenses to refract or bend light to form an image.
		An unusual variant of the Cassegrain is the Schiefspiegler telescope ("skewed" or "oblique reflector"), which uses tilted mirrors to avoid the secondary mirror casting a shadow on the primary.
		The Coudé design is similar to the Cassegrain except no hole is drilled in the primary mirror; instead, a third mirror reflects the light to the side, and further optics deliver the light to a fixed focus point that does not move as the telescope is reoriented.
	en.wikipedia.org /wiki/Reflecting_telescope (2076 words)

	Cassegrain Reflector (Site not responding. Last check: )
		First developed in 1672 by Laurent Cassegrain, a Cassegrain Telescope this type of reflector is a combination of a prime concave and a secondary convex mirror, both aligned axially.
		In a traditional Newtonian reflector, light from the primary mirror is deflected by a flat mirror to the eye-piece, placed on the side of the telescope body.
		In a Cassegrain telescope, there is a hole in the primary mirror; light from the primary mirror is reflected by the secondary mirror through the hole in the primary to reach the eyepiece, placed behind the telescope.
	www.toolhost.com /Cassegrain_Reflector.html (241 words)

	Reflecting telescope (Site not responding. Last check: )
		Reflectors which have spherical mirrors (rather than parabolic mirrors) tend to suffer from sphericalaberrations.
		An unusual variant of the Cassegrain is the Schiefspiegler telescope ("skewed" or "oblique reflector"), which uses tiltedmirrors to avoid the secondary mirror casting a shadow on the primary.
		The Coudé design is similar to the Cassegrain except no hole is drilled in the primary mirror; instead, a third mirrorreflects the light to the side, and further optics deliver the light to a fixed focus point that does not move as the telescopeis reoriented.
	www.therfcc.org /reflecting-telescope-42107.html (1076 words)

	Omniramic optical system having central coverage means which is associated with a camera, projector, or similar article ...
		Apparatus according to claim 1 in which said primary reflector is made of optically transparent material, said optically transparent central zone of said primary reflector consisting of a hole in its reflective coating, the surface of said substrate being radially symmetrical within said hole in reflective coating.
		In a Cassegrain telescope, the figures of the primary and secondary mirrors can be optimized to affect off-axis aberrations in a way which reduces the severity of aberrations or results in an aberration which is relatively practical to correct by means of comparatively small auxiliary refracting optics which are located relatively near the focal plane.
		The primary reflector 57d has an optically transparent central zone 57p which may consist of a hole 57p through the reflector substrate 57d, a hole in only reflective coating 55c of a transparent reflector substrate 55a or a partially reflective area in the reflective coating on a transparent reflector substrate.
	www.freepatentsonline.com /6333826.html (11772 words)

	Photonics.com \| Search
		Cassegrain lens system - A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a...
		Ritchey-Chretien telescope - A form of Cassegrain telescope having a concave hyperbolic primary and a convex hyperbolic secondar...
		Wynne-Rosin telescope - A Cassegrain telescope having a parabolic primary mirror, a spherical secondary mirror and a zero-power...
	www.photonics.com /photonicsFind.aspx?searchString=Cassegrain&searchIndex=0 (384 words)

	Reflecting telescope (Site not responding. Last check: )
		He designed the reflector in order solve the problem of chromatic aberration which occurred in all refracting telescopes before the perfection of achromatic lenses.
		Reflectors which have spherical mirrors (rather than parabolic mirrors) tend to suffer from spherical aberrations.
		An unusual variant of the Cassegrain is Schiefspiegler telescope ("skewed" or "oblique reflector") which tilted mirrors to avoid the secondary mirror a shadow on the primary.
	www.freeglossary.com /Reflecting_telescopes (1408 words)

	Designs
		Offset Front-fed Reflector, X-band, fed by a cluster of 4 polyrods.
		Front-fed Reflector, C-band, fed by a cluster of 4 polyrods.
		Cassegrain with rotating subreflector W-band, fed by a corrugated horn (94 GHz).
	www.anteg.net /html/designs.html (265 words)

	KnoxNews: Science
		Newtonian Reflector -- Contains two mirrors, a large primary at the bottom of the optical tube and a small secondary near the top, where light is reflected to the eyepiece on the side of the telescope.
		Cassegrain Reflector -- Also contains two mirrors, but the secondary mirror reflects light back toward the primary mirror at the bottom of the optical tube, where it passes through a hole and to the eyepiece.
		Disadvantages of reflectors: Obstruction caused by the secondary mirror in the light path and spherical aberration (light rays do not converge to a single point).
	www.knoxnews.com /kns/science/article/0,1406,KNS_9116_5187968,00.html (888 words)

	Reflecting Telescope (Site not responding. Last check: )
		Reflectors are used not only to examine the visible region of the electromagnetic spectrum but also to explore both the shorter- and longer-wavelength regions adjacent to it (i.e., the ultraviolet and the infrared).
		Also, the telescope tube of a reflector is shorter than that of a refractor of the same diameter, which reduces the cost of the tube.
		Reflectors, like refractors, usually have small guide telescopes mounted parallel to their main optical axis to facilitate locating the desired object.
	abyss.uoregon.edu /~js/glossary/reflecting_telescope.html (624 words)

	Secondary mirror - Wikipedia, the free encyclopedia
		A secondary mirror (or secondary) is a second light gathering and focusing surface in a reflector telescope.
		The secondary directs the light either out a side opening of the tube (Newtonian reflector) or back towards a focal point behind and through the primary (Cassegrain reflector).
		The secondary is typically suspended by X-shaped struts (sometimes called a "spider") in the path of light between the source and the primary, however it is important to realize that this does not cause large distortions in the image.
	www.sciencedaily.com /encyclopedia/secondary_mirror (191 words)

	Feeds for dual-reflector Antenna Systems (Site not responding. Last check: )
		Cassegrain and Gregorian feeds are universally used in dual-reflector antenna systems to achieve high efficiency, low antenna noise temperature and good cross-polarization.
		Monopod feeds are pre-aligned and mount to the vertex of the reflector.
		The feed is a corrugated horn equipped with a hybrid circular polarizer.
	www.seaveyantenna.com /catalog/p90/pg90.htm (398 words)

	reflector Comparison Table (Site not responding. Last check: )
		Telescope devised by Cassegrain in which an auxiliary convex mirror reflects the magnified image, upside down, through a hole in the center of the main objective mirror - i.e., through the end of the telescope itself.
		The Cassegrain telescope is similar but produces an inverted image.
		A reflector whose primary mirror is spheroidal instead of parabolic.
	www.site.uottawa.ca:4321 /astronomy/reflector_table.html (500 words)

	Parabolic Reflector or Dish Antenna - Radio-Electronics.Com
		These are termed the focal feed reflector where source of radiation is placed at the focal point of the parabola and this is used to illuminate the reflector.
		The parabolic reflector or dish antenna consists of a radiating element which may be a simple dipole or a waveguide horn antenna.
		The Cassegrain feed system, although requiring a second reflecting surface has the advantage that the overall length of the dish antenna between the two reflectors is shorter than the length between the radiating element and the parabolic reflector.
	www.radio-electronics.com /info/antennas/parabolic/parabolic_reflector.php (916 words)

	Cassegrain - InformationBlast
		Sieur Guillaume Cassegrain was a French sculptor who invented a form of wide angle reflecting telescope in 1672.
		There are three basic types of telescopes: refractors, reflectors (aka Newtonian-reflectors) and combined lens-mirror systems or catadioptric sensors.
		Cassegrain Telescope: First developed in 1672 by the French sculptor Sieur Guillaume Cassegrain (1625–1712), this type of reflector is a combination of a prime concave and a secondary convex mirror, both aligned axially.
	www.informationblast.com /Cassegrain_telescope.html (256 words)

	UREI- Undergraduate Research Educational Initiative
		The cassegrain utilizes a subreflector to reflect the light back through a hole in the primary mirror, and the detector can be placed behind the mirror.
		There are four basic elements to a radio telescope, the reflector, the subreflector, the feed and transmission line and the receiver.
		The subreflector is a surface that directs the radiation to the feed at the center of the reflector.
	www.haystack.mit.edu /edu/undergrad/materials/tut3.html (1121 words)

	Laurent Cassegrain Summary
		Cassegrain reflectors employ a concave primary mirror to focus and reflect light onto a convex secondary mirror.
		Laurent Cassegrain was a Catholic priest born in the region of Chartres around 1629 and died at Chaudon (Eure-et-Loir) on August 31, 1693.
		Cassegrain crater, on the Moon, is said to be named after Giovanni Cassegrain.
	www.bookrags.com /Laurent_Cassegrain (734 words)

	spacegazer - Cassegrains
		To overcome some of the disadvantages of the Newtonian reflector, other configurations have been developed, of which the Cassegrain telescope is probably the most well known version.
		Schmidt Cassegrains are becoming more and more popular and are the most common form of Cassegrain reflector on the market.
		A close brother of the Schmidt Cassegrain is the Maksutov Cassegrain scope which also incorporates a corrector plate, but one of a simpler design, but thicker and therefore heavier.
	www.spacegazer.com /cassegrains-g.asp (710 words)

	Schmidt Cassegrain Reflecting telescopes Newtonian dimensions aperture mounts
		A Newtonian reflector telescope bounces the collected light from it's main mirror out the side of the tube via the secondary mirror to the awaiting eyepiece.
		The light travels up the tube once, whereas the Cassegrain, the light bounces back from the secondary mirror towards the main mirror and through a hole in it's center to the eyepiece behind it.
		Collimation of Schmidt-Cassegrain reflector is easier physically than the Newtonian reflector, but the design of the telescope means it must be highly accurate.
	www.telescopes-astronomy.com.au /telescopes056.htm (395 words)

	Catadioptrics - Catadioptric Telescopes - OMC 140, Meade LX series etc.
		In a maksutov cassegrain telescope the light enters through a correcting lens where it is then brought to the primary mirror.
		It is much the same as the maksutov cassegrain reflector, but the corrector plate at the front of the tube is slightly different.
		It works in the same way as the schmidt cassegrain reflector but with one difference - the light that has been reflected by the primary mirror then hits a flat as in the newtonian refector, and leaves the tube through the side, not through a hole in the mirror.
	www.btinternet.com /~hubbletelescope/catadioptrics.shtml (321 words)

	Cassegrain reflector Information
		Catadioptrics are a combination of a refractor and reflector telescope, using both mirrors and lens to focus the incoming light.
		Another descendant of the Cassegrain design is the Ritchey-Chrétien telescope, which uses a hyperboloid primary and secondary mirror, eliminating the corrector plate needed for the catadioptic telescopes.
		The term Cassegrain has also been associated with a number of science fiction novels, such as David Drake's Igniting the Reaches and Patriots.
	www.bookrags.com /Cassegrain_Reflector (275 words)

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