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Topic: Spherical reflector

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Parabolic reflector

Reflector telescope

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	Parabolic reflector - Wikipedia, the free encyclopedia
		A parabolic reflector (also see Parabolic trough), known as a parabolic dish or a parabolic mirror, is a reflective device, formed in the shape of a paraboloid of revolution.
		The parabolic reflector functions due to the geometric properties of the paraboloid shape: if the angle of incidence to the inner surface of the collector equals the angle of reflection, then any incoming ray that is parallel to the axis of the dish will be reflected to a central point, or "focus".
		The Olympic Flame is lit using a parabolic reflector concentrating sunlight.
	en.wikipedia.org /wiki/Parabolic_reflector (434 words)

	Arecibo radio telescope
		It is a spherical reflector[?] (as opposed to a parabolic reflector).
		Originally, a fixed parabolic reflector was envisioned, pointing in a fixed direction with a 500 foot tower to hold equipment at the focus.
		Ward Low of ARPA pointed out this flaw, and put Gordon in touch with the Air Force Cambridge Research Laboratory[?] (AFCRL) in Boston, Massachusetts where a group headed by Phil Blacksmith[?] was working on spherical reflectors and another group was studying the propagation of radio waves in and through the upper atmosphere.
	www.ebroadcast.com.au /lookup/encyclopedia/ar/Arecibo.html (530 words)

	Design Rules for Reflective Solar Cookers
		With a spherical cookware, the locus of equal-span is a circle concentric with the cookware (fig.
		Therefore a parabolic reflector is often adopted for ordinary cookware. An exception occurs when the reflector is homemade out of a flat sheet [3]. In this case maximizing the angular tolerance is important, even in the interior of the reflector.
		12 Optimal reflectors in the xy-plane and the locus of ±15° span in the yz-plane.
	solarcooking.org /reflective-cooker-robustness.htm (2042 words)

	Wikipedia: Arecibo radio telescope
		The Arecibo telescope's dish surface is made of 38,778 perforated aluminium panels, each measuring about 1 m by 2 m (3 ft by 6 ft), supported by a mesh of steel cables.
		The construction of the Arecibo telesope was initiated by Professor William E. Gordon of Cornell University, who originally intended to use it for the study of Earth's ionosphere.
		Originally, a fixed parabolic reflector was envisioned, pointing in a fixed direction with a 150 m (500 ft) tower to hold equipment at the focus.
	www.factbook.org /wikipedia/en/a/ar/arecibo_radio_telescope.html (654 words)

	Reflector antennas
		A spherical wavefront (one in which the energy spreads out in all directions) spreads out as it travels away from the antenna and produces a pattern that is not very directional.
		Since the reflector is narrow in the horizontal plane and wide in the vertical plane, it produces a beam that is wide in the horizontal plane and narrow in the vertical plane.
		The cylindrical paraboloid reflector is fed either by a linear array of dipoles, a slit in the side of a waveguide, or by a thin waveguide radiator.
	www.tpub.com /neets/book11/46a.htm (1029 words)

	solar4.htm
		The size of the reflector is directly proportional to the performance of the cooker, and hence, it is a very important parameter.
		An asymmetrical parabolic reflector enables a cook to be as close as possible to the cooking vessel.
		Focal length of the reflector was 83 cm and the area was 0.8 sq.
	ashokk_3.tripod.com /solar4.htm (3150 words)

	UV Curing Reflector
		Aluminum reflectors are provided to assist engineers to build a UV curing system without investing in extrusion dies, long lead times, and minimum draw charges.
		Parabolic aluminum reflector provide a collimated source and the reflectors bottom edge should be located 4 to 5 inches from the substrate.
		Spherical reflectors provide a non-uniform distribution of energy from UV lamps and are not offered by Hill Technical. For proper lamp operation it is important that each half of our reflectors is separated by approximately one quarter of an inch to allow for convection cooling.
	www.hilltech.com /products/uv_components/UV_reflectors.html (518 words)

	Curved mirror - Wikipedia, the free encyclopedia
		The mathematical treatment is done under the paraxial approximation, meaning that the under first approximation a spherical mirror is a parabolic reflector.
		The ray matrix of a spherical mirror is shown here for the concave reflecting surface of a spherical mirror.
		The derivations of the ray matrices of a convex spherical mirror and a thin lens are very similar.
	en.wikipedia.org /wiki/Spherical_reflector (555 words)

	Arecibo radio telescope depends on accuracy
		Most reflectors on both optical and radio telescopes are parabolic, with a curve that looks like part of a sphere but is a bit flatter.
		The reflectors and dome were built on the floor of the dish then hoisted into place on the supporting structure above, replacing one of the two carriage houses on which line-feed antennae were mounted.
		Those in the secondary reflector are adjusted to within 12-thousandths of an inch, and those on the tertiary reflector to within eight-thousandths of an inch.
	www.news.cornell.edu /Chronicle/97/6.19.97/Arecibo_science.html (1222 words)

	Radar Calibration Reflectors (Site not responding. Last check: 2007-10-19)
		Radar calibration reflectors are typically used in the development and testing of radar systems, and in the measurement of radar cross section.
		Spherical reflectors are employed where a precise, angle and frequency independent reflection is needed.
		These reflectors are often used to align and calibrate radar systems because their return is relatively constant over large angles in azimuth and elevation.
	www.gosti.com /Cal_Tgts/Cal_Tgts.html (718 words)

	Apparatus for measuring scalar irradiance - Patent 4511250
		In accordance with the present invention, a spherical surface reflective of the electromagnetic energy to be measured is used to redistribute incoming flux equally in all directions.
		Therefore, a sensing means viewing a spherical reflector will indicate the same output regardless of the directional relationship between the source(s), the reflector and the sensor with the proviso that the sensor cannot detect flux from a source which is hidden from it by the reflector.
		The spherical surface is constructed of a material having relatively constant reflectance over the electromagnetic spectrum to be measured and the detector, likewise, is sensitive to said spectrum and preferably is capable of detecting a number of narrow bands within said spectrum.
	www.freepatentsonline.com /4511250.html (2675 words)

	Telescopes (Site not responding. Last check: 2007-10-19)
		In both the reflector and refractor telescopes, the focus is before the eyepiece, so the image in astronomical telescopes is upside down.
		Many reflector telescope use another light path design called the cassegrain design to reflect the light back through a hole in the primary mirror, so that detectors or the eyepiece can be conveniently placed behind the telescope.
		The images in reflector telescopes do not have holes or shadows in them because the light rays from the unblocked parts of the primary mirror are all added together when they are focussed together.
	www.astronomynotes.com /telescop/s3.htm (989 words)

	How a Telescope Works
		Behind the lens, then, the parabolic reflector is now replaced by a spherical one, so that the light from the point source going directly to the back is reflected back onto the point source, from there to continue in the right direction to be collimated by the lens.
		Replacing the part of the parabolic reflector lying in front of the point source with a spherical reflector, so that again the light is reflected back on itself, avoids the need for a very large parabolic reflector, reducing the bulk of the assembly.
		Shrinking the lens, and the spherical portion of the mirror behind it, results in the spherical mirror in front becoming larger; also, using a Fresnel lens allows a lens to be achieved with a fairly high proportion of diameter to focal length.
	www.quadibloc.com /science/opt01.htm (1215 words)

	Chapter 9
		The parabolic trough subsystem illustrated in Figure 9.12 is constructed from parabolic trough reflector panels 1.0 m long with an aperture width of 2.0 m. Six 90° rim angle reflector panels are then mounted on a steel torque tube 6.0 m in length, and the torque tube, in turn, is mounted on steel pylons.
		Reflectors - Perhaps the component most unique to the parabolic trough subsystem shown in Figure 9.12 is the reflector panel. The challenge is to produce a structure with an accurate parabolic contour and high specular reflectivity. One of the many possible designs for the reflector panels is shown in Figure 9.16.
		Figure 9.17 shows a prototype parabolic trough concept in which the reflector panel is simply a parabolic glass mirror supported by two stamped sheet metal ribs. This concept, referred to as the spaceframe concept, is potentially attractive since it reduces the reflector structure to the reflector itself with a minimum of other structural components.
	www.powerfromthesun.net /Chapter9/Chapter9new.htm (3615 words)

	diyAudio Forums Archive - reflector, reflector and reflector!!!!
		Put it this way, they are OK lol ive out done the brightness of one of those reflectors before with the spherical reflector and decent optics, it comes down to the coating on the reflector realy.
		I can also suggest that the relationship between the size of the spherical reflector and the condensor lens is that they should cover the same number of radians of arc.
		Or if the reflector is 2" from the lamp and the condensor is 1" from the lamp, then the reflector should have twice the diameter of the condensor lens.
	www.diyaudio.com /forums/showthread/t-38711.html (2107 words)

	The 305 meter telescope
		By aiming a feed antenna at a certain point on the reflector, radio emissions originating from a very small area of the sky in line with the feed antenna will be focused on the feed antenna.
		The tertiary reflector can be moved to improve focusing, receivers are moved into focus on a rotating floor inside the gregorian and the dynamical tie downs activate as needed to maintain platform position.
		And from the farthest reaches of the Universe quasars and galaxies emit radio waves which arrive at earth 100 million years later as signals so weak that they can only be detected by a giant eye like this one.
	www.naic.edu /public/the_telescope.htm (669 words)

	Spherical Concave (Site not responding. Last check: 2007-10-19)
		When the light-emitting filament of a bulb is placed near the center of curvature of a spherical, concave mirror, the reflecting surface creates a well-corrected image of the filament.
		Figure C-3: A spherical mirror nearly doubles the apparent brightness of a source through its return of backward-propagating rays of light to the condensing lens.
		With this reflector, light that would have been lost to the projector’s housing is collected and sent back to its point of origin, where it can be collected by the condensing lenses.
	www.jmloptical.com /level2/ProductInfo/m_spherical_info.aspx (657 words)

	Spherical mirrors
		A spherical mirror is a mirror which has the shape of a piece cut out of a spherical surface.
		The use of a parabolic reflector enables the headlight to cast a very straight beam of light ahead of the car.
		The beam would be nowhere near as well focused were a spherical reflector used instead.
	farside.ph.utexas.edu /teaching/302l/lectures/node114.html (716 words)

	Spherical Camera & Projection System
		Even though only one half of the spherical reflector is visible, the entire surrounding space is visible in the reflection from the hemisphere which is visible.
		The upper hemisphere of the scene is captured in the central 70% of the reflector.
		The only hidden portion in the scene is in the shadow below the reflector (later occupied by the viewer standing in the screen) and the reflection of the camera (later occupied by the hole for the projector lens).
	www.hineslab.com /idSphericalProjection.html (423 words)

	United States Patent: 5,572,355
		at least one spherical reflector in the pulse stretcher/compressor having a negative spherical aberration selected to compensate for the spherical aberration of the at least one element to produce a net spherical aberration in the pulse stretcher/compressor close to zero for reducing quartic phase error.
		It is a further object of the invention to compress an ultrashort pulse using a pair of spherical reflective surfaces, one concave and the other convex, with radii chosen to control the quartic phase error of the system.
		The flat reflector intercepts this spatially dispersed beam and reflects it back through the optical system along the same path in the reverse direction, whereupon it exits the system along a path substantially identical to that taken by the input, but this time propagating in the opposite direction.
	www2.rpa.net /~ase/patent5572355.html (4633 words)

	AWI Industries - Optics - Reflectors
		Reflectors are generally used for redirecting light from a non directional light source, such as a light bulb, to a particular direction.
		For Spherical Reflectors, if the light source is placed at the center of the sphere, the light rays will be directed back to the source:
		The focal surface is defined as a spherical surface with half the radius as the reflector:
	home1.gte.net /res6x2yr/relectors.html (162 words)

	Seismic R&D
		Analytical expressions (based on the spherical representation of wavefronts) describe the moveout correction for a given source-receiver pair with respect to a zero-offset image trace by three parameters measured at the image point.
		In particular, the multifocusing formulas are very accurate for a spherical reflector under a homogeneous overburden, and also for a smoothly curved dome-like reflector (Tygel et al., 1997).
		For a flat reflector under a homogeneous overburden the NIP radius depends on the distance between the image point and the reflector and is independent of the reflector dip.
	www.gii.co.il /html/rd/rd_seismic_theory.html (1721 words)

	Lumenlab > Spherical Reflector, Half-collimated Light, Funky Fresnel Required?
		In the image below the green is a reflector (doesn't have to be spherical, any curved mirror has a focal point, right?) and the projection lens, blue is the LCD and front fresnel (combined for simplicity), red is "bad" light, and yellow is "good" light.
		The problem is that the bulb itself blocks light from reflecting back off the center of the reflector, leaving a dim spot in the middle of your collimated light cylinder.
		You use a decent amount of the light w/ a spherical reflector and a 220mm fresnel.
	www.lumenlab.com /forums/lofiversion/index.php/t16759.html (1524 words)

	Radar Reflector 4
		A Target Pattern Map (TPM) is a method of representing three-dimensional data on paper, where azimuth (horizontal) angles are shown on the horizontal X-axis, elevation data is shown on the vertical Y-axis, and the strength of the return is shown by color or gray-scale shading.
		None of the reflectors would be more than marginally useful in offshore situations where only S-band were being used, except perhaps in calm sea conditions.
		The marginal performance of radar reflectors in general does not mean that they should not be carried.
	www.ussailing.org /safety/Studies/radar_reflector_4.htm (1117 words)

	Howstuffworks "How Telescopes Work"
		Reflectors have large light gathering capacities, and can produce bright images of faint, deep-sky objects for visual observing as well as astrophotography.
		One disadvantage of reflectors is that you occasionally have to clean and align the mirrors.
		In addition, all reflectors are subject to some light loss, for two reasons: First, the secondary mirror obstructs some of the light coming into the telescope; second, no reflective coating for a mirror returns 100 percent of the light striking it -- the best coatings return 90 percent of incoming light.
	science.howstuffworks.com /telescope3.htm (697 words)

	[No title]
		The spherical reflector can observe about one eighth of the sky at any one time and over the course of a day about half comes into view.
		The Large Adaptive Reflector as proposed by the Canadians should be able to observe over a greater range of elevations but is still limited to a minimum elevation of about 300 and at that elevation the effective collecting area is reduced by half due to foreshortening.
		The phased array performs somewhat better than the spherical reflector But its performance could be improved to equal the LAR if problems due to beamshape and interelement coupling could be overcome.
	www.atnf.csiro.au /projects/ska/archive/Case_for_Doublet.doc (2783 words)

	Reflectors
		If a light source is placed in the center of a spherical reflector, all of the rays will be reflected back 180 degrees of their original trajectory.
		A spherical reflector in concert with a special Fresnel lens is used for Fresnel spotlights.
		When a reflector is placed at the focal point at that end, all rays of the light that strike the reflector will be diverted through the second focal point.
	www.designersfortheatre.com /TAT/391/Electrics2.htm (6864 words)

	The Newton reflector
		Ideal shape of the primary mirror is paraboloid, which is free from spherical aberration when imaging distant objects.
		Medium and larger diameters mirrors have to be parabolized, due to spherical aberration of a sphere becoming excessive for astronomical observations.
		Longitudinal and transverse aberrations are as given in 2.1 Spherical aberration.
	www.telescope-optics.net /reflecting.htm (1879 words)

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