Showing papers on "Parabolic reflector published in 1992"
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30 Nov 1992TL;DR: In this article, a two-way mobile satellite tracking antenna system mounted on a movable vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle.
Abstract: A miniature dual-band two-way mobile satellite-tracking antenna system mounted on a movable vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.
80 citations
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10 Sep 1992TL;DR: In this article, a lighting system particularly suited for an automotive application in which it is desired to utilize a central light source and couple the light output therefrom to a headlamp assembly having a number of conventional components is presented.
Abstract: A lighting system particularly suited for an automotive application in which it is desired to utilize a central light source and couple the light output therefrom to a headlamp assembly having a number of conventional components includes introducing an output end of a light guide to the reflector assembly in place of an incandescent lamp, and disposing a mirror at the output end of the light guide to reflect light onto a conventional parabolic reflector. The mirror is preferably planar and serves to direct the light from the output end of the light guide to the parabolic reflector for collimation thereby and subsequent passage through a conventional lens member.
59 citations
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30 Sep 1992
TL;DR: A radiant energy collecting apparatus for collecting and concentrating solar energy having a primary parabolic reflector (16) which focuses the sun's rays on a focal line (18) and has a principle axis (17) passing through the focal line and a secondary concentrating assembly (20) located adjacent the primary reflector.
Abstract: A radiant energy collecting apparatus (11) for collecting and concentrating solar energy having a primary parabolic reflector (16) which focuses the sun's rays on a focal line (18) and has a principle axis (17) passing through the focal line (18) and a secondary concentrating assembly (20) located adjacent the focal line (17) of the primary reflector (16). The secondary concentrating assembly (20) includes a pair of planar reflectors (26) arranged on opposite sides of the principle axis (17) of the primary reflector (16) and a series of secondary parabolic reflectors (28) between the planar reflectors (26), the secondary parabolic reflectors (28) having focal lines (29) which extend normal to the planar reflectors (26) and to the principle axis (17) of the primary reflector (16). The secondary reflectors (28) are mounted for rotation about their focal lines (29) and concentrate energy on targets (42) extending along their focal lines (29).
40 citations
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09 Mar 1992TL;DR: In this article, a planar line or surface array of reradiating elements of two different polarizations is used to provide a phase shift which causes a collimated beam incident on the array to result in reradiation or reflection of energy in the form of a beam converging at a focal point.
Abstract: A dual-polarized antenna includes a planar line or surface array of reradiating elements of two different polarizations. Each reradiating element in one embodiment is a short-circuited vertical or horizontal dipole. The vertical and horizontal dipoles may be collocated on the array to form crossed short-circuited dipoles. The elements of each polarization form an array separate from the elements of the other polarization. Within each of the two separate arrays, the 1/λ of each reradiator is adjusted to provide a phase shift which causes a collimated beam incident on the array to result in reradiation or "reflection" of energy in the form of a beam converging at a focal point. Therefore, each planar reradiator array acts as a parabolic reflector with a particular focal point. The focal points for the vertical and horizontal arrays are different, and a feed of the appropriate polarization is located at each of the two focal points. A satellite includes a communication system operating in a "frequency re-use" mode, with mutually alternate, overlapping-frequency channels transmitted (and received) on mutually orthogonal polarizations.
27 citations
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TL;DR: In this paper, two parallel laser beams are used to align an off-axis parabolic mirror without alignment telescope and reference flat, in the plane of incidence, by measuring directions of the reflected beams and by changing height and orientation of the mirror.
Abstract: Two parallel laser beams are used to align an off-axis parabolic mirror without alignment telescope and reference flat. In this method the optical axis of an off-axis parabolic mirror is made parallel to the incident laser beams, in the plane of incidence, by measuring directions of the reflected beams and by changing height and orientation of the mirror. Then, the focal point ofthe off-axis parabolic mirror is automatically found where the two reflected beams cross each other. The alignment of the optical axis to the incident beams is done without knowing focal length and off-axis distance of the mirror. Alignment sensitivity is derived both numerically and analytically. When focal length is 457 mm, off-axis distance is 127 mm, and diameter is 178 mm, the off-axis parabolic mirror is aligned to the incident beams with an angular error of less than 3 mrad.
22 citations
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16 Apr 1992
TL;DR: In this article, a vehicular warning light has multiple segments of concave parabolic reflectors assembled for cooperative spreading of the light emitted from a single electric lamp to form an elongated wide angle beam of light in a horizontal plane for alerting the neighborhood to the presence and movement of the emergency vehicle.
Abstract: A vehicular warning light has multiple segments of concave parabolic reflectors assembled for cooperative spreading of the light emitted from a single electric lamp to form an elongated wide angle beam of light in a horizontal plane for alerting the neighborhood to the presence and movement of the emergency vehicle. The axis of revolution of each parabolic reflector is assembled at a differing azimuth angle within the common horizontal plane and the focal points and focal planes of the respective reflectors are dispersed. The equivalent center point of the single light source is therefore defocused relative to at least some of the reflectors. The axis of the elongated light source is centered on the common horizontal plane and is parallel to the fluted light cover lens which is contoured for efficiency in light transmission from the multiple reflectors and for additional spreading and luminous uniformity.
16 citations
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17 Jul 1992
TL;DR: In this paper, an edge detector is used to measure scattered measured light along the main axis of the incident laser beam or at an angle which is smaller than that between the main laser light axis and the main working surface.
Abstract: In an edge detector process, a working plane (A) is scanned by a focussed light beam, e.g. a laser beam emitted by a light source (L) projected at an angle of typically 40° to 45° from the working plane. A first and a second detector (D1, D2) receive the scattered light from the working plane. The first detector (D1) is positioned behind a focussing imaging optics (0), such as an off-axis parabolic mirror, which is arranged coaxially, i.e. all round the laser beam, or is positioned below the emitted light beam relative to a main working plane (H). The second detector (D2) is positioned approximately over the light spot produced by the emitted light on the main working surface. The stray light measured by the first detector (D1) is therefore received at an angle to the main working plane, which is equal to or smaller than the angle between the emitted light and said plane. An apparatus according to the invention has imaging optics (0) and one of the detectors is positioned in such a way that it measures scattered measured light along the main axis of the incident laser beam or at an angle which is smaller than that between the main laser light axis and the main working plane.
15 citations
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18 Aug 1992
TL;DR: In this paper, the beam focusing means are constructed by axially long dielectric members mounted on a waveguide opening part approximately at the focal position of the reflector and also forming both ends of the conical shapes.
Abstract: PROBLEM TO BE SOLVED: To miniaturize a reflection mirror even when the separation angle of radiated beams is small by placing plural primary radiators containing the beam focusing means consisting of axially long dielectric members mounted on a waveguide opening part approximately at the focal position of the reflector and also forming both ends of the dielectric member constructing each beam focusing means in the conical shapes. SOLUTION: A primary radiator 2 is placed near and against the focal position F of a parabolic reflector 1, and a primary radiator 3 is also placed near and against the position F and opposite to the radiator 2. The radiator 2 and 3 have the same shapes, and each of both radiators 2 and 3 consists of a waveguide having its circular section, a dielectric substance mounted at the front edge of the waveguide and a converter placed at the rear end of the waveguide. Then one of both ends of the dielectric substance has a conical shape to secure the matching of impedance with the waveguide with the other end projecting to the outside of the waveguide respectively.
9 citations
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26 Oct 1992
TL;DR: In this paper, a convex parabolic mirror and a concave paraboloid mirror are arranged opposite each other to increase the light resistance and reduce the disorder of a beam due to aberrations.
Abstract: PURPOSE:To increase the light resistance; reduce the disorder of a beam due to aberrations, and also reduce the size by arranging a convex parabolic mirror and a concave parabolic mirror so that their mirror surfaces face each other. CONSTITUTION:The convex parabolic mirror 1 and concave parabolic mirror 2 which are a confocal type and reflect reflected light at right angles to incident light are arranged having their parabolic surfaces opposite each other. The reflecting surfaces on the surfaces of the parabolic mirrors 1 and 2 are made of a material with high light resistance like Cu and Mo. A beam with a diameter d1 which is made incident from the side of the convex parabolic mirror 1 is reflected and expanded by the parabolic surfaces of the convex parabolic mirror 1 and concave parabolic mirror 2 and outputted as a beam with a diameter d2 from the concave parabolic mirror 2. The parabolic mirrors have no aberration, so the quality of the beam is not disordered and the incidence angle of the beam is set large. Therefore, the device can be made compact by making the interval between both the parabolic mirrors 1 and 2 small. When the incident light is made incident in the reverse direction, the device functions as the beam reduction unit.
7 citations
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13 Mar 1992
TL;DR: The parabolic reflector forming part of a satellite station receiver has a surface that is covered with photovoltaic elements e.g. solar cells as mentioned in this paper, and the energy from the cells is used to maintain the charge in a battery power pack.
Abstract: The parabolic reflector forming part of a satellite station receiver has a surface that is covered with photovoltaic elements e.g. solar cells. The energy from the cells is used to maintain the charge in a battery power pack. The cells are produced from iron and magnetic free material. The electrical energy is used to supply the elements of a receiver such as a polarising element, low noise amplifier, converter and coaxial switches. USE/ADVANTAGE - Reception interference avoided. Environmentally friendly power source. Low cost.
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01 Apr 1992TL;DR: In this article, the results of an experimental study of two compound parabolic reflector antennas were reported, where the reflectors were designed to have equal beamwidths at two separate frequency bands and the inner region of the reflector was formed as a conducting metallic surface; the outer region was a frequency-selective surface designed to be highly reflecting at the lower frequency band, and transmitting at the higher band.
Abstract: The results of an experimental study of two compound parabolic reflector antennas are reported. The reflectors were designed to have equal beamwidths at two separate frequency bands. The inner region of the reflector was formed as a conducting metallic surface; the outer region was a frequency-selective surface designed to be highly reflecting at the lower frequency band, and transmitting at the higher band. The performance of the compound reflector is compared with that of an equivalent wholly metallic paraboloid.
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07 Jul 1992
TL;DR: A mirror collimator has a larger parabolic mirror (11) and a smaller convexly shaped capture mirror (12) arranged at the concave side of the parabolic image and on its optical axis (27) as mentioned in this paper.
Abstract: A mirror collimator has a larger parabolic mirror (11) and a smaller convexly shaped capture mirror (12) arranged at the concave side of the parabolic mirror and on its optical axis (27). A cut-out 15 is formed at the common focal point of the parabolic mirror (11) and of the capture mirror (12) and a photo-element (16) is arranged in the area of this cut-out (15). The capture mirror (12) is secured to the parabolic mirror (11) by at least one carrying device (17) extending alongside the cut-out (15).
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15 Apr 1992
TL;DR: In this paper, the authors proposed to increase the utilization efficiency of light by forming the circumference of a main mirror as translucent part so that the shape of the reflecting surface of the main mirror forms a noncircular light-emitting region in a view from an optical axial direction.
Abstract: PURPOSE:To increase the utilization efficiency of light by forming the circumference of a main mirror as translucent part so that the shape of the reflecting surface of the main mirror forms a noncircular light-emitting region in a view from an optical axial direction. CONSTITUTION:The reflecting surface 11a of the main mirror 11 is formed only on a part corresponding to a prescribed light-emitting surface (a rectangle in this example), and its outside is the translucent part 11b. It does not partici pate in the light-emitting region of the rectangle. The rays of the light passing through the translucent part 11b are reflected by a reflecting surface 13a, returned to the reflecting surface 11a, reflected thereby and turned into luminous flux parallel to an optical axis O, to be emitted from a projection opening 14. Thus, the utilization efficiency of the light can be increased.
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30 Jul 1992
TL;DR: The concentrator has two stages for concentrating solar radiation onto solar cells, and is tracked in the polar axis as mentioned in this paper, where a first concentrator placed above a second and forming a half angle theta2 of about 20 to 30 degrees.
Abstract: The concentrator has two stages for concentrating solar radiation onto solar cells, and is tracked in the polar axis. A first concentrator placed above a second and forming a half angle theta2 of about 20 to 30 degrees. The first concentrator is linear and the second two-dimensional. The concentrators may comprise linear or rectangular fresnel lenses, e.g. made of glass. The first concentrator may be a parabolic reflector, and the second a compound parabolic concentrator (CPC). The half-angle theta2 is pref. 25.5 degrees. USE/ADVANTAGE - Increased concentration factor. Need only be tracked in polar (north-south) axis during day. Small dimensions.
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01 Jan 1992TL;DR: In this article, a beam waveguide (BWG) design suitable for high-power applications is described, which features a transmit-only, four-port high-gain horn as input to a BWG system with a single parabolic mirror and three flat plates.
Abstract: A beam waveguide (BWG) design suitable for high-power applications is described. The design features a transmit-only, four-port high-gain horn as input to a BWG system with a single parabolic mirror and three flat plates. The use of a single parabolic mirror is such that the highest field concentration is no greater than that caused by the horn itself. The horn is linearly polarized and a grid reflector is used to reflect the orthogonal polarization into the receive feed. A rotatable dual polarizer provides for arbitrary transmit polarization. The dual-reflector system is shaped to provide uniform illumination over the main reflector and therefore maximum gain for the given size aperture. Measured data from a scale model BWG system are presented.
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25 Mar 1992
TL;DR: In this article, the authors proposed to reduce the size of a head lamp by forming the one of two head lamps by using an ordinary lamp having a reflector formed of a parabolic mirror and forming the other by using a projector lamp having an oval reflection mirror and a convex lens.
Abstract: PURPOSE:To reduce the size of a head lamp by forming the one of two head lamps by using an ordinary lamp having a reflector formed of a parabolic mirror and forming the other by using a projector lamp having a reflector formed of an oval reflection mirror and a convex lens. CONSTITUTION:In a head lamp device 10, an ordinary lamp 13 and a projector lamp 14 are disposed at the right and the left in a rectangular frameform body 11 having a front covered with a front glass 12, namely an ordinary lamp 13 and a projector lamp 14 are disposed on both sides with the center of a car body therebetween in a manner to approach each other. The ordinary lamp 13 is for Hi beams and has a reflector 15 formed by using a parabolic mirror 15a, and a halogen bulb 16 is located in the vicinity of the focus of the parabolic mirror 15a. Meanwhile, the projector lamp 14 is for Lo beams and has a reflector 19 formed by using an oval reflection mirror 19a, and a halogen bulb 20 is situated in the vicinity of the first focus of the oval reflection mirror 19a. A convex lens 21 having a focus at the second focus is arranged in front of the second fodus.
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20 Oct 1992
TL;DR: In this article, the authors proposed a method to efficiently converge projection luminous flux from a light source, guiding the converged luminous flow to a necessary restricted lighting area and making the luminous fluid into a parallel light beam, and obtaining uniform and bright illumination light.
Abstract: PURPOSE: To efficiently converge projection luminous flux from a light source, guides the converged luminous flux to a necessary restricted lighting area and make the luminous flux into a parallel light beam, and to obtain uniform and bright illumination light. CONSTITUTION: The light beams (A 1 and B 1 ) which are emitted by the light source positioned at a focus F1 of a parabolic reflector 21 and directly reflected by reflecting surfaces 21A and 21B of the parabolic reflector 21 are made into parallel beams, which are projected. Light beams (A 2 and B 2 ) which are emitted from F1 and directly reflected by the reflecting surfaces 21A and 21B of the parabolic reflector 21 become slanting lights which slant to an optical axis of projection. Light beams (C 2-1 and D 2-1 ) which are emitted from F2 and reflected by reflecting surfaces 23C and 23D of an elliptic reflector 23, on the other hand, pass the focus F1 of the parabolic reflector 21 and are then reflected by reflecting surfaces 21C and 21D of the parabolic reflector 21 to become parallel light beams. COPYRIGHT: (C)1994,JPO&Japio
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28 Dec 1992
TL;DR: In this article, a lens is slant to the main axis of a reflector without making a dark part in the lens corner part nor sacrificing an effective reflecting surface, and the parabolic mirror has an aperture larger than the length of the segment connecting the corner part to main axis.
Abstract: PURPOSE: To slant a lens to the main axis of a reflector without making a dark part in the lens corner part nor sacrificing an effective reflecting surface CONSTITUTION: A reflector setting position 20' is formed in the side part of a lens present on one side in vehicle width direction when visually seen from the front, a lens corner part 27 formed by a curved outer shape line 25 and a liner outer shape line 26 is present on the lens side part, and the dimension L in the vehicle width direction of the reflector setting position 20' is set within a determined width with the corner point 27a of the lens corner part 27 as a standard A reflector consisting of a parabolic mirror 22 is arranged on the reflector setting position 20', the focus F of the parabolic mirror 22 is situated on the side distant from the corner point 27a with the center of the determined width L as a boundary A bulb 23 is set in the focus F, the parabolic mirror 22 has an aperture larger than the length L' of the segment connecting the corner part to the main axis, and a lens 21 is mounted on a housing 20 slantingly to the main axis 24 of the parabolic mirror 22 COPYRIGHT: (C)1994,JPO&Japio
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06 Oct 1992
TL;DR: In this paper, an auxiliary reflecting mirror 66 of a spherical mirror is arranged so as to be deviated a little to the reflecting mirror 60 side from the light emission center of a parabolic mirror.
Abstract: PURPOSE: To improve the utilizing efficiency of light, and also, to improve a peripheral light quantity ratio. CONSTITUTION: In the light source unit for projection for reflecting light from a light emission source 10 and irradiating a body 26 to be projected therewith, and in he outside periphery of an opening end of a reflecting mirror 60 of a parabolic mirror, an auxiliary reflecting mirror 66 of a spherical mirror is provided, a focus F of the reflecting mirror 60 is arranged so as to be deviated a little to the reflecting mirror 60 side from the light emission center 11, the spherical center O of the auxiliary reflecting mirror 66 is arranged in one of a position of a middle point M of the focus F and the light emission center O, and a position deviated a little to the reflecting mirror 60 side from the middle point M, a first irradiation light 61 for irradiating the body 26 to be projected through the reflecting mirror 60 from the light emission soruce 10 is condensed to the inside a little from light being parallel to an optical axis 13, and a second irradiation light 63 for irradiating the body 26 to be projected through the auxiliary reflecting mirror 66 and the reflecting mirror 60 from the light emission source 10 is made parallel to the optical axis 13, or is allowed to diverge to the outside a little from the light being parallel to the optical axis 13. COPYRIGHT: (C)1994,JPO&Japio
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06 Feb 1992
TL;DR: In this paper, the authors proposed to emit X-rays in parallel beam by arranging parabolic mirrors, in which the focus is located at the target position and which shape Xrays from the target into parallel beam, around the target.
Abstract: PURPOSE:To emit X-rays in parallel beam by arranging parabolic mirrors, in which the focus is located at the target position and which shape X-rays from the target into parallel beam, around the target. CONSTITUTION:Rotary parabolic surface mirrors 15, 16 rotate in a single piece relative to a base 10 and a casing 13 in response to operation of a motor. If in this condition power is supplied to a filament 20, electrons are emitted at a high speed. This high speed electron beam runs against a target 11 to generate X-rays, which are emitted from the target 11 in a wide angle range. These rays are reflected by the mirrors 15, 16, and their transfer path is varied. That is, because the focal positions of the mirrors 15, 16 are located on the target 11, the X-rays reflected by the mirrors 15, 16 are shaped into parallel beam. Thus X-rays in parallel beam can be emitted directly from the X-ray tube.
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02 Sep 1992TL;DR: In this article, the use of a projection moire system to test the surface shape of an injection molded f/0.1 parabolic reflector is presented, and some alignment errors associated with the system and how to correct them are presented.
Abstract: Testing injection molded aspheres, with large deviations from spherical is difficult. One solution is to use a long wavelength interferometer, such as an infrared interferometer. Another solution is to use moire. This paper presents the use of a projection moire system to test the surface shape of an injection molded f/0.1 parabolic reflector. The theory of moire and its effective wavelength is presented. A projection system is constructed and data taken for a reflector is shown. Finally, some alignment errors associated with the system and how to correct them is presented.
01 Jan 1992
TL;DR: In this article, the authors report broadband monolithic transmitters and receivers IC's for mm-wave electromagnetic measurements using nonlinear transmission lines (NLTL) and sampling circuits as picosecond pulse generators and detectors.
Abstract: We report broadband monolithic transmitters and receivers IC's for mm-wave electromagnetic measurements. The IC's use nonlinear transmission lines (NLTL) and sampling circuits as picosecond pulse generators and detectors. The pulses are radiated and received by planar monolithic bow-tie antennas, collimated with silicon substrate lenses and off-axis parabolic reflectors. Through Fourier transformation of the received pulse, 30-250 GHz free space gain-frequency measurements are demonstrated with an accuracy approximately = 0.17 dB, RMS.
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01 Jan 1992
TL;DR: In this article, the beam propagation characteristics of ZnSe optics used in kilo Watt power CO2 laser aided material processing applications are determined using the Prometec Laser Beam Analyzer.
Abstract: Beam propagation characteristics of ZnSe optics used in kilo Watt power CO2 laser aided material processing applications are determined using the Prometec Laser Beam Analyzer. The laser used was a Rofin Sinar RS6000 CO2 laser with mode aperturing. Beam power varied from 500W to 6300W and beam modes used were TEM00, TEM01*, TEM10, and TEM20. Both transmissive and reflective optics were examined. The ZnSe lenses tested included meniscus, diffractive and cylindrical lenses of 5in focal length and a 10in focal length integrating lens. Reflective optics included an integrator and a 5in focal length parabolic mirror for welding. Parameters obtained included beam propagation profiles, intensity profiles, depth of focus, spot size and back focal length. A subset of the data obtained is presented here. Details of the work will appear in a full length paper.Beam propagation characteristics of ZnSe optics used in kilo Watt power CO2 laser aided material processing applications are determined using the Prometec Laser Beam Analyzer. The laser used was a Rofin Sinar RS6000 CO2 laser with mode aperturing. Beam power varied from 500W to 6300W and beam modes used were TEM00, TEM01*, TEM10, and TEM20. Both transmissive and reflective optics were examined. The ZnSe lenses tested included meniscus, diffractive and cylindrical lenses of 5in focal length and a 10in focal length integrating lens. Reflective optics included an integrator and a 5in focal length parabolic mirror for welding. Parameters obtained included beam propagation profiles, intensity profiles, depth of focus, spot size and back focal length. A subset of the data obtained is presented here. Details of the work will appear in a full length paper.
01 Mar 1992
TL;DR: This thesis modifies an existing method of moments computer code to handle the displaced axis geometry, and computes the radiation pattern and the efficiency of this antenna as a function of geometrical and electrical design parameters.
Abstract: : Small symmetric dual reflector antennas suffer from low efficiency due to subreflector blockage of the main reflector and subreflector scattering. These can be reduced by slicing the main dish and translating its rotational axis, along with modifying the subreflector geometry. This type of design is usually applied to low-frequency reflectors, but high-frequency analysis techniques are used. Consequently the agreement between measured and computed data is not good as it would be for rigorous solution such as the method of moments. This thesis modifies an existing method of moments computer code to handle the displaced axis geometry, and computes the radiation pattern and the efficiency of this antenna as a function of geometrical and electrical design parameters. Optimum configurations are identified for several feed types. The paraboloidal antenna with a feed at the focus does not allow much control of the power distribution over the aperture surface, except for what can be accomplished by changing the focal length and feed pattern.
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18 Jun 1992
TL;DR: In this paper, a self-supported magnetic current loop array operating at 9 GHz has been designed as a feed for a reflector antenna, where the feed is a circular waveguide that protrudes into the paraboloidal reflector through the center.
Abstract: To eliminate the blockage caused by mechanical support, a self-supported magnetic current loop array operating at 9 GHz has been designed as a feed for a reflector antenna. In the present arrangement, the feed is a circular waveguide that protrudes into the paraboloidal reflector through the center. To generate magnetic current loops, circumferential slots can be cut on a coaxial or circular waveguide. For narrow slots, energy radiated per slot is small and negligible; the electromagnetic field inside the waveguide is therefore not affected. A number of prototype antenna feeds have been fabricated and compared. In the Fresnel zone, the E-plane and H-plane radiation patterns of the feed at center frequency, 9 GHz, are illustrated. The estimated efficiency of the antenna is greater than 80%. >
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20 Jan 1992
TL;DR: In this article, a curved surface mirror consisting of two specified parabolic mirrors is used to improve the utilization efficiency of projected light from a light source in a curve surface mirror by irradiating a rectangular area to be irradiated through the rectangular aperture of the parabolic mirror.
Abstract: PURPOSE:To improve the utilization efficiency of projected light from a light source in a curved surface mirror by irradiating a rectangular area to be irradiated through the rectangular aperture of the curved surface mirror consisting of two specified parabolic mirrors. CONSTITUTION:This illuminating system is composed of the 1st parabolic mirror 2 having a circular aperture, the light source 1 arranged near the focal point of the mirror 2, and the 2nd parabolic mirror 3 having the rectangular aperture 4 whose diameter is nearly the same as the mirror 2 in its center and curvature smaller than the mirror 2 and then the focal points of the mirrors 2 and 3 are allowed to agree with each other. It is desirable to form an illuminating device for displaying an image 120 which illuminates a liquid crystal light valve 108 having a rectangular display area by using this illuminating system and a luminous flux from the valve 108 is cast to a screen 110.
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09 Dec 1992
TL;DR: In this paper, an auxiliary lamp is incorporated in a camera in a compact size without making the camera itself larger in size, and also, to easily attach the lamp by separately providing the auxiliary lamp for preventing a red-eye phenomenon other than a main lamp and having such a constitution that the outer circumferential part of the lamp is directly covered with a cylindrical reflector.
Abstract: PURPOSE:To incorporate an auxiliary lamp in a camera in a compact size without making the camera itself larger in size, and also, to easily attach the lamp by separately providing the auxiliary lamp for preventing a red-eye phenomenon other than a main lamp and having such a constitution that the outer circumferential part of the lamp is directly covered with a cylindrical reflector. CONSTITUTION:It is a conventional concept that the auxiliary lamp is incorporated in the camera other than a strobe lamp in order to prevent the occurrence of the red-eye phenomenon, in this case, the lamp 6 is provided with a parabolic reflector, so that the camera itself becomes larger in size. but in this case, the outer circumferential part of the lamp 6 is directly covered with the cylindrical reflector 7. That means, the light of the lamp is efficiently radiated forward by the cylindrical reflector 7, and the light quantity is increased by about 50% as compared with the case without using the reflector 7. Then, the light quantity enough for preventing the red-eye phenomenon can be efficiently obtained even in the case of not using the conventional parabolic reflector. And also, as to the auxiliary lamp, the reflector for covering the lamp 6 with it is formed to be cylindrical, so that it can be easily attached with a holder 10 and also easily positioned, thus, it can be contained in a compact size.
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22 Mar 1992
TL;DR: In this paper, a study of contoured beam onboard a Japanese direct broadcasting satellite (DBS) with pattern analysis and test results for the full-scale bread board model (BBM) is described.
Abstract: This paper describes a study of contoured beam onboard a n t e n n a for f u t u r e Japanese direct broadcasting satellites (DBS) with pattern analysis and test results for the full-scale bread board model (BBM). The BS-3a and BS-3b were launched in 1990 and 1991, respectively, by the HI launch vehicle into a geo-synchronous orbit of 110 degrees east longitude. A follow-on DBS will be launched before the end of the BS-3's life (7 years). As the methods to realize the contoured-beam pattern for Japanese territory, the BS-3 antenna employs an elliptical offset parabolic reflector fed with a new type. \rJ of elliptical corrugated horn as well as a rectanylar horn. Thus, the contoured beam is based on an el ipse, and it is difficult to achieve the best fitting contour patterns for the Japanese territory. The antenna examined herein consists of a shaped reflector and a horn. This shaped reflector antenna has achieved a better shaped radiation pattern than the BS-3, and has attained a gain of more than 38 dBi for the major parts of Japan while, maintaining the RR.AP30* regulations for sidelobe and cross-polarization levels, theoretically and experimentally. In order to verify our shaped reflector antenna characteristic, a BBM antenna with 2.3m aperture was constructed and has shown good agreement with the analytical results. The authors propose this reflector antenna as a candidate for the next Japanese direct broadcasting satellite antenna system.