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Topic: Cassegrainian reflector

	Reflecting Telescope
		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)

	Kellner eyepiece (Site not responding. Last check: 2007-10-23)
		It is essentially a Cassegrainian reflector whose steeply curved objective is corrected by a meniscus.
		It is essentially a Newtonian reflector whose steeply curved objective mirror is corrected by a Maksutov style meniscus.
		Newtonian reflector - A telescope whose objective is a concave mirror and whose flat secondary mirror is tilted 45
	www.singularsci.com /Glossary4.htm (245 words)

	Bin's On-Line Dictionary (Site not responding. Last check: 2007-10-23)
		Cassegrainian telescope, a reflecting telescope invented by Cassegrain, which differs from the Gregorian only in having the secondary speculum convex instead of concave, and placed nearer the large speculum.
		Galilean telescope, a refracting telescope in which the eyeglass is a concave instead of a convex lens, as in the common opera glass.
		Reflecting telescope, a telescope in which the image is formed by a speculum or mirror (or usually by two speculums, a large one at the lower end of the telescope, and the smaller one near the open end) instead of an object glass.
	language.bin.org /ref/dict/?t=Herschelian+telescope (433 words)

	3.6 Types of Antenna (Site not responding. Last check: 2007-10-23)
		The horn antenna such as the conical horn or rectangular horn is used for power supply to the reflector antenna, calibration of low temperatures for the microwave radiometer in the form of a sky horn looking upward, and calibration for active radar as shown in Figure 3.6.1.
		Reflector antenna such as parabolic antenna and Cassegrainian antenna are composed of primary radiator and a reflective mirror as shown in Figure 3.6.2.
		The reflector antenna is used for microwave radiometers, altimeters and scatterometers.
	www.profc.udec.cl /~gabriel/tutoriales/rsnote/cp3/cp3-6.htm (326 words)

	Multibeam antenna arrangement with minimal astignatism and coma - Patent 4484197
		The present antenna comprises a plurality of N reflectors arranged confocally in a sequence along a feed axis of the antenna and at least one feed disposed in the vicinity of a focal point on the focal surface.
		The reflectors and the at least one feed are further arranged to provide an equivalent centered antenna arrangement with the longitudinal axis of the feed substantially parallel to an equivalent axis of the centered arrangement for eliminating astigmatism.
		Primary astigmatism and primary coma are the aberrations that arise in the vicinity of the focus of the reflector arrangement.
	www.freepatentsonline.com /4484197.html (2563 words)

	Astronomical Telescopes (Site not responding. Last check: 2007-10-23)
		In the case of a Newtonian reflector, this is accomplished with a single small flat mirror.
		More practical is the Cassegrainian scheme, which utilizes a small convex mirro to reflect the light back through a small hole in the primary mirror.
		There is an additional advantage of the Cassegrainian telescope, for it is uncommonly short and compact for its magnifying power.
	members.localnet.com /~atheneum/astronomy/telescopes.html (644 words)

	Chp 2: Space And Ground Antennas
		An alternative approach to large reflectors is to deploy an array of small antennas over a large area and connect them in such a way that their received or transmitted signals are in the correct electrical relationship (phase) with each other, i.e., a "phased array" or simply an array.
		Horn-fed reflector antennas constitute a mature technology which is particularly suited to those applications where an earth station or a satellite communicates with space or ground terminals in relatively fixed locations where there is room to install a dish.
		The reflector doesn't rest directly on the spars but on a network of dielectric wires ("quartz fibers") that are connected to the mesh, to the spars, and to each other.
	www.wtec.org /loyola/satcom/c2_s1a.htm (3947 words)

	Apollo Observatory - Wikipedia, the free encyclopedia
		Due to the selected design, the optical train was complex and turned out to be problematic to maintain.
		It was therefore later modified to a simpler Dall-Kirkham Cassegrainian design.
		The original building and the 50cm (20-inch) telescope located in the dome were designed under the advice and guidance of MVAS members.
	en.wikipedia.org /wiki/Apollo_Observatory (369 words)

	The Yolo Reflector, a booklet by Arthur Leonard, page 22 (Site not responding. Last check: 2007-10-23)
		By designing the Yolo so that the tilt angles are a little greater than the minimum required to make the light path just clear mirrors of the minimum required diameters, the central illuminated part of the secondary is moved a short distance away from the open end of the tube.
		Having the eyepiece located at the bottom of the tube and looking up instead of at the top of the tube and looking across, as is the situation in the Newtonian reflector, is both a disadvantage and an advantage.
		It is a disadvantage in that it makes the light baffle system necessary in the Yolo; but it is an advantage in that once the system of baffles is installed, the field of view in the Yolo is much darker than that which can be obtained in Newtonian.
	www.atmsite.org /contrib/Holm/yolo/yolopage22.html (356 words)

	Glossary Terms: C
		a dark field condenser consisting of a convex spherical reflector mounted concentric with a larger concave reflector.
		The rays are formed into a diverging cone by the convex reflector.
		The annular concave reflector then forms a hollow converging cone which is focused on the subject.
	www.charfac.umn.edu /glossary/c.html (1908 words)

	Telescope
		A few are: meridian transit (altitude only); fixed with movable plane mirror for solar observing; ball-and-socket (ancient and useless for astronomy).
		Most large research telescopes can operate as either a cassegrainian (longer focal length, and a narrower field with higher magnification) or newtonian (brighter field).
		They have a pierced primary, a newtonian focus, and a spider to mount a variety of replaceable secondaries.
	www.brainyencyclopedia.com /encyclopedia/t/te/telescope_1.html (1208 words)

	Compound Telescopes (Site not responding. Last check: 2007-10-23)
		All variants of the Cassegrainian and Gregorian telescope are considered to be compound telescopes...
		reflector, they add little convenience, but they do cost a lot more.
		Compound telescopes or catadioptrics - a combinaton of lenses and mirrors is used to gather light.
	telescopes-and-binoculars.info /optics/compound-telescopes.html (287 words)

	Reflecting Telescope 1668 Data \| Reflecting Telescope 1668 Content (Site not responding. Last check: 2007-10-23)
		Reflecting telescope, reflector optical telescope consisting of a large concave mirror that produces an image that is magnified by the eyepiece.
		The form of reflecting telescope suggested by james gregory predates the familiar form of reflector.
		Cassegrainian telescope, gregorian telescope a reflecting telescope that has a paraboloidal primary.
	www.telescope-heavens.com /reflecting-telescope-1668.html (833 words)

	RAND \| Paul Baran: Distributed Communications - Mini-Cost Microwave - Implementation of a Mini-Cost Station
		The foam antenna serves more purposes than solely as an antenna reflector; it forms the housing for the transmitter/receiver unit and feed horn.
		A horizontal and a vertical steel shaft intersect at the point at which the antenna is clamped to the tower and the sway and torsion guys are attached.
		Three or four steel straps center the secondary reflector and accurately reference it to the antenna feed horn and main reflector.
	www.rand.org /pubs/research_memoranda/RM3762/RM3762.chap6.html (4099 words)

	Cassegrainian Telescope (Site not responding. Last check: 2007-10-23)
		man, in 1672 designed a second compound reflector, differing from Gregory's in that it employed a convex secondary, to be of hyperboloidal figure, placed inside of the focus of the paraboloidal primary (Fig.
		from the Cassegrainian, and it has the advantage of being a much more compact instrument.
		Although little was heard of this telescope for the next two centuries, it is worth observing that it survived the Gregorian, and is still widely used in observatories.
	www.best-telescope-guide.com /6cassegrainiantelescope.html (231 words)

	James Short Biography / Biography of James Short 1700 To 1799: Technology and Invention Biography
		The Cassegrainian reflector used curved mirrors instead of lenses to concentrate light into a sharp and useable image for study.
		Although first designed in 1672, the technology to shape mirrors to the precise specifications needed for an effective instrument was lacking until 1740.
		The Cassegrainian reflector is still used today, as is its primary competitor, the Newtonian reflector.
	www.bookrags.com /biography-james-short-scit-0412345 (147 words)

	University of London Observatory: Allen Telescope (Site not responding. Last check: 2007-10-23)
		It was acquired by the Observatory at a cost of 42000 pounds to replace the 24-inch Newtonian/Cassegrain reflector built in 1880 by Grubb of Dublin for use by W. Wilson at his observatory in Daramona, Co. Westmeath, Ireland, and donated to UCL in 1925 by Mr.
		The telescope's focus is located a short distance behind the hole, as with all Cassegrainian designs.
		Accurate focussing of the Allen telescope is accomplished by moving the secondary mirror a small amount using an electric motor.
	uranus.ulo.ucl.ac.uk /telescopes/allen (385 words)

	The Yolo Reflector, a booklet by Arthur Leonard, page 21 (Site not responding. Last check: 2007-10-23)
		With the light source, mirror, and eyepiece set up as shown in Figure 4, and the warping harness unstressed, the image seen in the eyepiece should show only one aberration - astigmatism - but lots of that.
		Since its eyepiece looks right up at the sky through the open end of the tube, it has some of the problems of the Cassegrainian reflector.
		Its main problem differs from that in the Cassegrainian, however, in that the open end of the Yolo is confined to only one side of the secondary and does not extend all the way around, as it does
	www.atmsite.org /contrib/Holm/yolo/yolopage21.html (311 words)

	Introduction
		The Monash observatory, situated approximately 50 km East-South-East of Melbourne at an elevation of 308 metres, is currently used for differential photometric studies of rapidly rotating, active-chromosphere, cool stars.
		To expand the range of studies at the observatory, the Physics Department plans to attach a visible-wavelength spectrograph to its 0.46-metre Cassegrainian reflector.
		This spectrograph is of a crossed Czerny-Turner design that is to operate in the visible wavelength band (3000 Å to 7000 Å).
	www.atnf.csiro.au /pasa/test/marsden/paper/node1.html (277 words)

	equip
		The most common telescopes in use today are: the Refractor achromatic or apochromatic lens system, the Newtonian reflector all mirror optical system, the Classical Cassegrain reflector folded mirror optical system, and the Schmidt-Cassegrain, or Catadioptric, which combines elements of both the refractor and the reflector.
		The Newtonian reflector is completely achromatic and gives sharp images through all color filters.
		The Classical Cassegrainian reflecting telescope has focal ratios from f/15 to f/60 with small secondary mirrors.
	www.tnni.net /~dustymars/Observing_Mars_7 (4140 words)

	Appendix B: ANT Bosch Telecom
		Technology areas include structural elements, shaped reflector and deployable reflector antennas, waveguide and feed technologies including rotary joint, corrugated feed and direct radiating array developments.
		ANT has recently completed a study and breadboard hardware of shaped dual offset reflector antennas (Cassegrainian and Gregorian) for prescribed aperture distributions, sidelobe suppression and cross-polarization optimization including a feed system development.
		A large internal RandD program is underway that will develop reconfigurable and adaptive antennas, multibeam reflector antennas, direct radiating arrays, including beam-forming networks, and feed technology developments.
	www.wtec.org /loyola/satcom/ab_ant.htm (1149 words)

	UK Astronomy
		Its instrumentation has now been updated by the incorporation of the Submillimetre Common-User Bolometer Array (SCUBA), which can process observational data 10,000 times faster than before, and greatly enhances the capabilities of an instrument rightly regarded as one of the finest radio telescopes in the world.
		Jointly constructed by Britain and the Netherlands 10 years ago, and now operated by these two countries and Canada, the James Clerk Maxwell Telescope (JCMT) on the extinct volcano of Mauna Kea (pictured here) is a classical Cassegrainian instrument, specially designed for radio astronomy at submillimetre wavelengths.
		The primary reflector is a 15 metre disc which reflects incoming radio waves back up to a 0.75 metre secondary so that they are re-reflected back down through an aperture in the primary reflector to a focus at the base of the instrument where recording and analytical instrumentation is located.
	www.britannia.com /newsbits/radoeye.html (903 words)

	3-MM Wave Fast Scanning Antenna
		The antenna is so called inversed Cassegrainian antenna type, that is antenna, having two reflectors- stationary
		The proposed idea to do fast antenna scanning (antenna beam velocity up to 2000 deg/sec) is to convert continuous rotary motion of electric engine (effector) into oscillatory motion of the flat twist reflector.
		If we could do parameters twist reflector positioning gear matched to inertia oscillations of the twist reflector, the
	members.tripod.com /~lreri/FastScAntenna.html (263 words)

	AXIAL
		A typical example is an axisymmetric Cassegrainian reflector with a splashplate feed [1], [2], [3].
		The exciting waveguide with its dielectric is modelled as a circular waveguide while the exterior of the waveguide and the reflector are modelled as a coaxial section (Figure 3).
		The result is an ability to design a high efficiency (65%) reflector with sidelobes of -22 dB and low spillover (<-40 dB) when the aperture is relatively small in wavelengths.
	www.maasdesign.co.uk /axial.html (706 words)

	Complete List of Publications
		Mittra, W. Ko, and M. Sheshadri, "A transform technique for computing the radiation pattern of prime-focal and Cassegrainian reflector antennas," IEEE Trans.
		Galindo-Israel, W. Imbriale and R. Mittra, "On the theory of the synthesis of single and dual offset shaped reflector antennas," IEE Fifth International Conference on Antennas and Propagation ICAP 87, pp.
		Galindo-Israel, W. Imbriale, and R. Mittra, "On the theory of the synthesis of single and dual offset shaped reflector antennas," IEEE Trans.
	www.ecl.ee.psu.edu /ecl/CompleteList.html (8072 words)

	List of Publications
		R. Mittra, W. Ko, and M. Sheshadri, "A transform technique for computing the radiation pattern of prime-focal and Cassegrainian reflector antennas," IEEE Trans.
		V. Galindo-Israel, W. Imbriale and R. Mittra, "On the theory of the synthesis of single and dual offset shaped reflector antennas," IEE Fifth International Conference on Antennas and Propagation ICAP 87, pp.
		V. Galindo-Israel, W. Imbriale, and R. Mittra, "On the theory of the synthesis of single and dual offset shaped reflector antennas," IEEE Trans.
	www.ee.psu.edu /faculty/mittra/Mittra_Public.html (14381 words)

	What is the largest telescope you've observed through? - Astronomy.com Forums
		It was an 18 inch classic cassegrainian reflector.
		It was made in the 1950's by a physics professor at the college I attended.
		My own scope is a 4.5inch reflector that I would love to trash for a 6inch Mak or a 6inch refractor.
	www.astronomy.com /ASY/CS/forums/296200/ShowPost.aspx (1062 words)

	RAND \| Paul Baran: Distributed Communications - Mini-Cost Microwave - Specifications
		Replacement units may be interchanged without need for field alignment or adjustment.
		The transmitter and receiver shall mount integrally with the antenna reflector to avoid the cost and losses of long waveguide runs.
		The antenna feed horn shall be designed so that excess heat dissipation from the transmitter/receiver unit is used to aid in the melting of ice from the front of the antenna feed, where such a problem exists.
	www.rand.org /pubs/research_memoranda/RM3762/RM3762.chap2.html (1084 words)

	Active Electronically Steered Arrays - A Maturing Technology
		The first generation of microwave fighter radar antennas were mechnically steered concave reflectors, colloquially termed dish antennas.
		By using a cleverly designed and oft complex network of microwave waveguides on the rear surface of the array, a designer could produce the desired fixed beam shape and do so with much smaller sidelobes compared to a concave reflecting antenna.
		As the antenna is a flat plate, it tends to act like a flat panel reflector to impinging transmissions from hostile radars and thus has a lower radar signature than a concave antenna.
	www.ausairpower.net /aesa-intro.html (3554 words)

	Data Collection
		Launched in April, 1996, the Midcouse Space Experiment (MSX) satellite carried several imaging instruments, among which was the middle ultraviolet imager of the Ultraviolet and Visible Imaging and Spectrographic Imaging (UVISI) instrument [Mill et al., 1994].
		The imager consists of an intensified CCD mated to Cassegrainian reflector optics [Carbary et al, 1994].
		The imager's filter and RbTe photocathode combination provide superior out-of-band ("red leak'') rejection from visible wavelengths, which reduces albedo effects from the ground and lower atmosphere.
	www.agu.org /pubs/toc/gl/gl/gl0113/2001GL013086/node2.html (436 words)

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