Topic
Parabolic reflector
About: Parabolic reflector is a research topic. Over the lifetime, 3375 publications have been published within this topic receiving 30735 citations. The topic is also known as: paraboloid reflector & paraboloidal reflector.
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Papers
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12 Dec 1995TL;DR: In this paper, the authors described a method for concentrating the energy of laser diode beams by imaging them to obtain a superimposed image and a combined numerical aperture at a focal plane.
Abstract: Methods and apparatus are disclosed for concentrating the energy of laser diode beams (24) by imaging them to obtain a superimposed image and a combined numerical aperture at a focal plane (26) and by guiding them between reflective boundaries (70, 72) to maintain a lesser second numerical aperture at the focal plane. The combined numerical aperture preferably matches the second numerical aperture so that the energy can be received into the entrance end (102) of optical fibers (100) whose numerical apertures also match the second numerical aperture. A described embodiment utilizes collimating lenses (36) and an off-axis parabolic reflector (38). The exit ends (108) of the optical fibers can be grouped and fractionally magnified into a concentrated energy pattern. The final image can be imposed into a single optical fiber (30) for passage along remote or convoluted optical paths.
19 citations
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01 Jun 1974
TL;DR: In this article, the focal region characteristics of offset reflector antennas have been investigated both analytically and experimentally, and the dependence of the beam deviation factor upon the edge angle and the orientation of the feed axis was shown.
Abstract: The focal region characteristics of offset fed reflector antennas have been investigated both analytically and experimentally. In order for offset reflectors to have analogous focal region properties to those of front fed parabolic reflectors, an offset axis and an offset focal plane are defined. The definitions of the offset axis and offset focal plane are essential for satisfactory operations of offset reflectors illuminated by a cluster of feeds. Numerical results using physical optics approximation are presented to show the dependence of the beam deviation factor of offset reflectors upon the edge angle ( \Theta_{E} ) and the orientation of the feed axis( \Theta_C{o} ).
19 citations
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20 May 1988
TL;DR: In this paper, a light fixture includes a parabolic reflector, a light source positioned at the focal point of the reflector and a lens assembly, which includes a front lens for transmitting the primary beam reflected from the parabolic reflection, and a first lens section including one, two or more lateral focussing elements positioned between the front lens and the edge of the paraboloid reflector to intercept omnidirectionally radiated light rays from the light source and to redirect the intercepted light rays into collimated lateral beams to illuminate selected areas at the side of the light
Abstract: A light fixture includes a parabolic reflector, a light source positioned at the focal point of the parabolic reflector and a lens assembly. The lens assembly includes a front lens for transmitting the primary beam reflected from the parabolic reflector. The lens assembly also includes a first lens section including one, two or more lateral focussing elements positioned between the front lens and the edge of the parabolic reflector to intercept omnidirectionally radiated light rays from the light source and to redirect the intercepted light rays into collimated lateral beams to illuminate selected areas at the side of the light fixture.
19 citations
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29 Dec 1987
TL;DR: A light absorption analyzer can work in either a reflection or a transmission mode, according to which probe head is fitted to it as mentioned in this paper, where light is caused to be of a desired wavelength for the analysis by passing non-monochromatic light from a high-intensity flash tube source (which is not a point source) to an interference filter.
Abstract: A light absorption analyzer can work in either a reflection or a transmission mode, according to which probe head is fitted to it. Light is caused to be of a desired wavelength for the analysis by passing non-monochromatic light from a high-intensity flash tube source (which is not a point source) to an interference filter. Only parallel light emanating from the filter is focused by a concave parabolic mirror on a point where at least one fibre-optic collector is positioned. This light can then be passed directly to the probe for passage through the sample, since it is only light of a specified wavelength which will have travelled parallel from the filter and will therefore be focused at the point. Some of the light is taken off a reference detector to provide a reference signal for comparison with that derived from a test detetor fed by a return fibre-optic from the probe. A comparator is programmed to give a quantitiative readout of the absorption by the test sample.
19 citations
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TL;DR: In this article, a composite illuminator is described which does eliminate this form of aberration, enabling beam scanning through as much as 110 degrees to be obtained without beam degradation, and the efficiency for the illuminated portion of the aperture is about 55 per cent and sidelobe levels from 18 to 20 db below the main beam.
Abstract: A portion of a spherical reflecting surface possesses inherent scanning advantages over a paraboloidal reflector. These advantages can only be realized, however, if spherical aberration is eliminated. A composite illuminator is described which does eliminate this form of aberration, enabling beam scanning through as much as 110 degrees to be obtained without beam degradation. Efficiency for the illuminated portion of the aperture is about 55 per cent and sidelobe levels from 18 to 20 db below the main beam are obtained. A set of high gain polyrods provides paraxial zone illumination while the wide-angle primary illumination is derived from a line source consisting of back-to-back channel guides. The phase velocity in the channels varies in such fashion as just to compensate for the path length deviations experienced by nonaxial rays, thereby eliminating spherical aberration. Experimental results for spherical reflecting antennas at X, K_{u} and K_{a} band are given. Use of ad hoc primary illumination functions has allowed theoretical calculations of secondary patterns. These are in qualitative agreement with observed results.
19 citations