Showing papers on "Parabolic reflector published in 1983"

Solar tracking unit

Abstract: A solar tracking system having particular utility for insuring that a relatively lightweight solar collector is properly positioned with respect to the sun. A parabolic reflector surface is included to provide a line of focus of the sunlight directed toward a cylindrical energy absorption tube. Photovoltaic cells provided on either side of the energy absorption tube are directed toward the parabolic reflector surface. A reversible motor is electrically connected to the cells and physically connected to the reflector system for correcting any misalignment with respect to the sun. The reversible motor can be used as the sole means for powering the tracking system or can be used in conjunction with an outside power source.

Multi-chamber light for motor vehicles

Abstract: The invention relates to a multi-chamber light for motor vehicles, in which a light chamber is formed by a lens which has a meander-shaped cross-section, and a parabolic reflector. The filament of a fog tail light filament lamp is arranged at the focal point of the reflector. In the light chamber, a tail light filament lamp is additionally inserted at a distance from the fog tail light filament lamp. A second lens with light-directing prisms is arranged between the two filament lamps and the lens with a meander-shaped cross-section. Areas of the second lens with light-directing prisms are each connected in front of the sections, extending parallel to the optical axis of the reflector, of the lens constructed with the meander-shaped cross-section. The prisms concentrate the light emerging directly from the filament of the tail light filament lamp onto the optical axis of the parabolic reflector. The light beams, directed in parallel by the reflector, of the fog tail light filament lamp pass through the areas remaining free from a light-concentrating optical system between the prisms on the second lens.

High intensity security flashlight with duffusing parabolic reflector

Abstract: Although small enough to fit in a purse, this flashlight operates on six volts using a full-size flashlight bulb and casts a bright and quite-uniform beam of light, primarily for brief uses at relatively short range. The uniformity of the beam is obtained by a novel optical system, that includes an unsilvered, preferably generally parabolic reflector and a beam-narrowing lens. The combination of compactness and brightness is obtained by novel arrangement of the bulb and four penlight cells within the battery case, enhanced by the geometry of the reflector and lens.

Initial '80s Development of Inflated Antennas

Abstract: State of the art technology was considered in the definition and documentation of a membrane surface suitable for use in a space reflector system for long durations in orbit. Requirements for a metal foil-plastic laminate structural element were determined and a laboratory model of a rigidized element to test for strength characteristics was constructed. Characteristics of antennas ranging from 10 meters to 1000 meters were determined. The basic antenna configuration studied consists of (1) a thin film reflector, (2) a thin film cone, (3) a self-rigidizing structural torus at the interface of the cone and reflector; and (4) an inflation system. The reflector is metallized and, when inflated, has a parabolic shape. The cone not only completes the enclosure of the inflatant, but also holds the antenna feed at its apex. The torus keeps the inflated cone-reflector from collapsing inward. Laser test equipment determined the accuracy of the inflated paraboloids.

Integrated optical beam expander

Abstract: A reflective afocal beam expander optical system 50 is disclosed for transmitting electromagnetic (EM) energy. The beam expander, in the preferred embodiment, is comprised of a reflective afocal system 30 including a section of a primary parabolic mirror 32, a section of a secondary parabolic mirror 34, and a beam splitter 48. The two mirrors have a common axis of rotational symmetry 40 and a common focus point and the centerline 46 of the incoming EM energy is displaced from the axis of rotational symmetry. The beam splitter 48 is positioned with respect to the primary mirror 32 to receive the edge rays of the EM energy and cause the EM energy to be folded and exit through a window while clearing all optical elements. A viewing system 70 having a viewing axis 72, through the beam splitter48 allows a viewer to see through the same window 67 as the exiting EM energy. A second refractive afocal optical system 52 is made integral to the specific laser system being used in order to control beam expansion ratios.

Efficient computation of the far field of parabolic reflectors by pseudo-sampling algorithm

Abstract: The newly developed pseudo-sampling representation is applied for computing the far field of an offset parabolic reflector with a cluster feed illumination. A new comb-type fast Fourier transform (FFT) algorithm is used in a computer program. Both precision and computational time are analyzed, demonstrating the excellent performance of the method.

Analysis of a Combined Thermal-Photovoltaic Solar System Based on the Spherical Reflector/Tracking Absorber Concentrator

Abstract: The Stationary Reflector/Tracking Absorber (SRTA) solar system, which has been described and used in the past for heat and steam generation, is analyzed with the aim of combining with it photovoltaic (PV) generation. The light concentration function along a finite size absorber is calculated. The areas of the absorber which may be unilluminated during parts of the day are determined. It is shown that for a system to be useful for PV generation, the absorber must turn one side toward the outside perimeter of the reflector while tracking, and its diameter must increase with the distance from the reflector. A special two-section polygonal cone is shown to give an approximately constant light concentration along most of its length, and can therefore be used with an array of solar cells of one type only. Such a design also contributes to an incidence angle of the reflected light rays on the absorber surface that is closer to normal than with a cylindrical shape. It is also shown that the length of a real absorber is always shorter than that of an ideal line absorber of zero radius, and that only about 50 percent of the area should be covered with cells, withmore » the rest to be used for thermal absorption and heat generation only.« less

Aberrations in Plane Grating Spectrometers

Abstract: The aberrations of off-axis plane grating spectrometers with one mirror in the camera and another in the collimator are calculated by means of the plate diagram method. Spectrometers in the Z and U configurations with spherical, centred parabolic and off-axis parabolic mirrors are studied. Making use of the opportunity provided by the method, the aberrations in each system are rapidly analysed in order to make a first selection among the designs under consideration. The analytical results are compared with those obtained by ray tracing. The study shows clearly the optimal field of application of each design.

Lighting fixture with a concave reflector, such as a tail, warning or signal light etc.

Abstract: Lighting fixture including an enclosure, means disposed in the enclosure for supplying a central source of light therein, a concave, generally parabolic reflector for directing a main beam of light out of the enclosure from the source generally along a given optical axis, the central source of light being located at the focal region of the concave reflector, the concave reflector having a light penetrable region thereof disposed at least at one side of the optical axis in a horizontal plane in common with the central light source, the light-penetrable region forming an escape window out of the enclosure for part of the light from the source.

A parabolic reflector with asymmetric low sidelobes

Abstract: A technique for generating low sidelobes on one side of the main lobe for a parabolic reflector antenna is presented. The reflector system that generates such an asymmetric sidelobe pattern consists of a central parabola with two sections of offset parabolas situated at the top and bottom of the central parabola. By adjusting the positions and dimensions of the side reflectors, considerable suppression of the first few sidelobes can be obtained. Further, by similar adjustments it is possible to achieve suppression of sidelobes on both sides of the main beam, though this suppression is relatively less. The technique, though explained in detail with reference to a cylindrical geometry, is extended for a paraboloid of revolution. The analysis program utilized for the optimization of the side reflectors is based on physical optics current integration.

External optical device for laser

Abstract: PURPOSE:To permit inexpensive manufacture of the entire part of a titled device by making parallel visible beams incident through the opening of a total reflecting mirror for laser beams having the opening in the central part and superposing the reflected laser beams and the parallel visible beams on the same axis. CONSTITUTION:A CO2 laser beam 1 from a laser oscillator transmits through an oblique window 3 which consists of a GaAs substrate material having high transmittance to the wavelength of CO2 lasers and is inclined at 45 deg. with respect to a beam axis. A nonreflection film is coated on the surface of the window 3, and about 2-3% reflected CO2 laser beams 5 are split on the surface. The CO2 laser beam 4 transmitted through the window 3 is condensed at the focal position by a parabolic mirror 6. The visible light beam 2 by an He-Ne laser is superposed on the same axis of the beam 4, so that both beams are condensed at the same focus position 7.

Gas detection system

Abstract: PURPOSE:To detect gases contained in the air in a wide range from an early stage, by combining a plane mirror for sending and receiving scanning light with plural reciprocating reflective mirrors. CONSTITUTION:Light emitted from a semiconductor laser L is projected through a light projection collimator mirror 1, and the light transmitting hole H of a reflective mirror 2 to a scanning plane mirror SM as a means for projecting and receiving light. Next, the light reflected from the mirror SM is reflected with a reciprocating reflective mirror RR1 and projected via the mirror SM, the mirror 2, and a parabolic mirror 3 to a photodetector D to convert the light into an electric signal. When the light path of the mirror SM is directed toward a reciprocating reflective mirror RR2, the light reflected from the mirror RR2 is likewise projected to the photodetector D. Therefore, gases contained in the air can be detected in a wide range in an early stage by arranging plural reciprocating reflective mirrors and the plane mirror SM in the center.

Fourier transform spectrum device

Abstract: PURPOSE:To eliminate influence by deflection of a mirror, and expand a measuring wavelength area, by providing a pair of rotary phase plates between a fixed mirror and a beam splitter, instead of a moving mirror, and forming an optical path difference. CONSTITUTION:Light to be detected A is reflected by a mirror 16 and a parabolic mirror 17 and becomes parallel light beams, and they are split to a transmission light beam and a reflection light beam by a beam splitter. The transmission light beam passes through phase fixed plates 15a, 15b, is reflected by a fixed mirror and is returned to the beam splitter 10. On the other hand, the reflection light beam passes through rotary position plates 10a, 10b, is reflected by the fixed mirror 12, becomes a luminous flux whose optical path length has been varied, and is returned to the beam splitter 10. Both its luminous fluxes are synthesized and are made incident to a detector 22 through a parabolic mirror 18, a mirror 19, a slit 20 and a lens 21. Since an optical path difference has been formed by using the fixed mirror 12 and a pair of rotary phase plates 14a, 14b instead of a moving mirror, and changing its opening angle (theta), influence by deflection of a mirror is removed and a measuring wavelength area is expanded.

GTD analysis of the radiation patterns of a prime focus paraboloid with shroud

Abstract: The uniform geometrical theory of diffraction (UGTD) is employed to analyze the far-field radiation patterns of a prime focus paraboloid with a cylindrical shroud. The blockage of the aperture illumination of the dish by the gooseneck and the primary feed is also taken into account in the analysis. Far-field radiation patterns (for 0\deg\leq\Theta \leq 180\deg ), calculated for a typical prime focus paraboloid with 2 m aperture diameter, designed and fabricated, are compared with the experimentally derived patterns at 8.8 GHz in the E - and H -planes. There is a satisfactory agreement between the two results.

Dipped headlamp for vehicles

Abstract: A dipped headlamp comprising a parabolic reflector defining an optical axis A-A and a focus F, a light source L placed on the optical axis slightly in front of the said focus, and cut-off means C to intercept a proportion of the rays emitted by the source travelling towards the reflector, in order to define a cut-off limit on the beam reflected by the reflector. The reflector R is formed by two paraboloidal portions having the same focus and extending respectively to the left and to the right of the optical axis. The paraboloidal portion RD has a greater focal length than the paraboloidal portion RG.

Laser beam scanning method

Abstract: PURPOSE:To obtain the laser beam scanning method characterized by a uniform scanning speed and high accuracy, by selecting a parabolic mirror or a spherical mirror which is used as a concave mirror in correspondence with a slant angle or a scanning angle. CONSTITUTION:For example, in an off axis method, a scanner 7 is arranged on two axes, with the center of the concave mirror 6' as an original point 0. Then, a value XP of an x coordinate of a scanning point P at the scanning angle theta by the laser beam 10 is determined by whether the concave mirror 6' is the spherical mirror or the parabolic mirror based on the slant angle OMEGA and the scanning angle theta. The coordinate XP in the case for the axial center at the slant angle OMEGA/2 is likewise determined. Then a distortion rate TAU corresponding to the deviation in the scanning speed is computed based on the equation I. When the method which satisfies conditions I-IV is selected so that said distortion rate becomes small, the laser beam scanning method characterized by the uniform scanning speed and the high accuracy is obtained. Note: XP (1); the value of the coordinate XP for the scanning angle of l deg..

Study of multi-kilowatt solar arrays for Earth orbit applications

Abstract: A miniaturized Cassegrainian concentrator (MCC) solar array concept is being developed with the objective of significantly reducing the recurring cost of multikilowatt solar arrays. The desired cost reduction is obtained as a result of using very small high efficiency solar cells in conjuction with low cost optics. The MCC single element concept incident slar radiation is reflected rom a primary parabolic reflector to a secondary hyperbolic reflector and finally to a 4 millimeter diameter solar cell. A light catcher cone is used to improve off axis performance. The solar cell is mounted to a heat fin. An element is approximately 13 millimeters thick which permits efficient launch stowage of the concentrator system panels without complex optical component deployments or retractions. The MCC elements are packed in bays within graphite epoxy frames and are electrically connected into appropriate series-parallel circuits. A MCC sngle element with a 21 sq cm entrance aperture and a 20 efficient, 0.25 sq cm gallium arsenide solar cell has the same power output as 30 sq cm of 11-percent efficiency (at 68 C) silicon solar cells.

Some limitations in the broadband operation of segmented reflectors

Abstract: Arrays of finite conducting linear elements are often used to approximate solid reflectors in applications where weight and wind loading make it impractical to use large, solid surfaces A common configuration for such an array is achieved by simply connecting the centres of the linear elements by a single structural member such that the reflector is an array of parasitic dipoles excited by a driven element located in front of the reflector Theoretical and experimental data obtained for several plane, corner and parabolic reflector configurations show that distinct resonances, characterized by narrowband fluctuations in the radiation pattern may seriously affect the operation of these antennas Adjustment of the reflector element length and spacing provides an effective means of controlling these resonances

Deformation of a thin, elastic plate to a deep parabolic cylinder

Abstract: Equations governing the elastic deformation of thin plates through large displacements to deep parabolic cylinders are presented and solved. The solution consists of expressions for a spatially distributed surface pressure and uniform rim loads which, when applied to the plate, produce the specified, deep parabolic cylindrical shape. These forming loads are written in dimensionless form for parabolic cylinders of arbitrary focal length and arbitrary rim to rim aperture. Numerical results are presented and limiting values are discussed. The solution and results find immediate application to mechanical forming and adhesive retention of parabolic solar collector components.

Parabolic antenna device

Abstract: PURPOSE:To obtain a high aperture area efficiency with a determined aperture area, by arranging a parabolic reflector a prescribed length apart from the aperture end face of an aperture waveguide part so as to face to a primary radiator provided with a flange. CONSTITUTION:A primary radiator 2 where a waveguide 5 is connected through a connecting part 6 is arranged in the focus position of the parabolic reflective face of a parabolic reflector 1 and faces to the parabolic reflector 1. This primary radiator 2 forms an electromagnetic horn and consists of an aperture round waveguide part 3 and a discoidal flange part 4 which is arranged on the outside circumference of the aperture round waveguide part 3 and in a position distant from an aperture end face 3' of this part 3. The diameter of the flange part 4 and the distance of the flange part 4 from the aperture end face 3' of the aperture round waveguide part 3 are changed to control the directivity of the primary radiator 2, and thus, the aperture area efficiency is set as high as possible with the parabolic reflector 1 having a determined diameter.

Bicollimated near-field Gregorian reflector antenna

Abstract: : A bicollimated near-field Gregorian reflector is structurally similar to a classical confocal parabolic reflector, but its surfaces are shaped to have better scan capability. A geometrical optics procedure is used in designing the reflector surfaces. A three-dimensional ray tracing procedure is used in analyzing the aperture phase errors as the beam is scanned to different angles. The results show that the bicollimated configuration has about 45% greater angular scanning range than the corresponding confocal parabolic dual-reflector system.

Reflex camera capable of adjusting quantity of light

Abstract: PURPOSE:To make the adjustment of the quantity of light possible, by arranging a liquid crystal display element, which changes the transmittance in accordance with an applied voltage, in front of a parabolic reflector of a reflex camera. CONSTITUTION:A liquid crystal display element 5 is arranged in front of the second parabolic reflector 4 of reflex camera. Therefore, the voltage applied to the liquid crystal display element 5 is changed to change the quantity of the transmitted light in accordance with the voltage, and the liquid crystal display element 5 is used as an aperture to adjust easily the quantity of the light led to the camera main body.

Reflector type antenna device

Abstract: PURPOSE:To make an irradiation area slightly different for every frequency band by setting the phase center of a primary horn to the focal point of a parabolic reflector for one frequency band, and shifting it from the focal point for the other frequency band and also selecting an angle of feeding to the reflector CONSTITUTION:A multifrequency common-use antenna for mounting on an artifricial satellite has an offset parabolic reflector 1 fed by a multifrequency common-use primary horn 2 In a frequency band having a phase center point 8, the direction of a radiant beam of the antenna is specified without reference to an angle 4 of feeding In a frequency band having a phase center point 9, a phase distribution in the opening surface of the reflector 1 is not vertically symmetrical in Fig according to variation in feeding angl 4 As a result, the direction of the radiant beam of the antenna varies vertically For this purpose, the feeding angle 4 is selected to obtain a slightly different irradiation area for each frequency band, incrasing a minimum gain in the irradiation area

Convergent transmitter of solar ray

Abstract: PURPOSE:To utilize solar energy effectively, by forming an axially long-sized hole in the reverse surface of the peripheral wall of a cylindrical body having a specular surface as it inner circumferential surface and arranging a parabolic mirror having a focus on the center axis of the long-sized hole at a lower part. CONSTITUTION:The cylindrical body 5 having the specular surface 1 as its inner circumferential surface has the axially long-sized hole 4 and under it, the parabolic mirror 7 having the focus on the center axis of the long-sized hole 4 is arranged. Solar light S incident to the reflecting surface 6 of the parabolic mirror 7 is condensed onto the long-sized hole 4 and then reflected by the specular surface 1 to heat water flowing in the cylinder 5. Thus, the solar energy is utilized effectively.

Wavelength stabiliser for semiconductor laser - comprises concave mirror and diffraction grating selecting required wavelength from laser emission

Abstract: The semiconductor laser wavelength stabilising system includes an optical fibre (2) taking radiation from the laser (1) to a point near to the focus of a concave spherical or parabolic mirror. Light from the optical fibre then travels to the mirror (5) and is reflected back on to a plane diffraction grating (4) lying in a plane surrounding the end of the fibre. The diffraction grating returns light to the mirror so that it is again reflected, falling on the end (9) of a second optical fibre (8) which then carries the radiation as the stabilised output. The mirror and grating serve to select the required wavelength from the range of wavelengths present in the original laser beam.

LDR segmented mirror technology assessment study

Abstract: In the mid-1990s, NASA plans to orbit a giant telescope, whose aperture may be as great as 30 meters, for infrared and sub-millimeter astronomy. Its primary mirror will be deployed or assembled in orbit from a mosaic of possibly hundreds of mirror segments. Each segment must be shaped to precise curvature tolerances so that diffraction-limited performance will be achieved at 30 micron (nominal operating wavelength). All panels must lie within 1 micron on a theoretical surface described by the optical precipitation of the telescope's primary mirror. To attain diffraction-limited performance, the issues of alignment and/or position sensing, position control of micron tolerances, and structural, thermal, and mechanical considerations for stowing, deploying, and erecting the reflector must be resolved. Radius of curvature precision influences panel size, shape, material, and type of construction. Two superior material choices emerged: fused quartz (sufficiently homogeneous with respect to thermal expansivity to permit a thin shell substrate to be drape molded between graphite dies to a precise enough off-axis asphere for optical finishing on the as-received a segment) and a Pyrex or Duran (less expensive than quartz and formable at lower temperatures). The optimal reflector panel size is between 1-1/2 and 2 meters. Making one, two-meter mirror every two weeks requires new approaches to manufacturing off-axis parabolic or aspheric segments (drape molding on precision dies and subsequent finishing on a nonrotationally symmetric dependent machine). Proof-of-concept developmental programs were identified to prove the feasibility of the materials and manufacturing ideas.