Showing papers on "Parabolic reflector published in 2004"

Toward a spherical spot distribution with 4π focusing of radially polarized light

Abstract: The properties of the focal spot for 4π focusing with radially polarized light are presented for various apodization factors. With a focusing system satisfying the Herschel condition, sharp focal spots with almost-perfect spherical symmetry (leading to equal axial and transverse resolution) and extremely low sidelobes are achieved.

Projection type video display

Abstract: A light source comprises a lamp such as an ultra-high pressure mercury lamp or a metal halide lamp and its irradiated light is emitted after being parallelized by a parabolic reflector The parabolic reflector is made by pressing metal such as stainless and its light exit side aperture is covered with a transparent plate made of glass, etc The transparent plate prevents fragments of glass of the lamp and the like from scattering when the lamp bursts The parabolic reflector does not have an aperture (cut-out) for ventilation, but heat radiation fins are formed on the outer surface of it

LOFAR: first of a new generation of radio telescopes

Abstract: Aperture plane detection of cosmic radio signals can confer several important advantages. The mechanical signal processing of conventional parabolic dish antennas can be replaced by signal processing purely in electronics and software, thereby placing aperture plane array instruments in a regime with decreasing future costs. Aperture arrays using all-sky element antennas also allow multiple, independent, full sensitivity telescopes to be formed in software. The Low Frequency Array (LOFAR) project aims to realize these advantages in a previously largely unexplored frequency domain, 10-240 MHz. Consisting of up to eight shared aperture telescopes operated independently over internet, it will explore the epoch of re-ionization, open the transient radio Universe to systematic study, record ultra-high energy cosmic particles and add a new dimension to solar and space physics research.

Catadioptric light distribution system

Abstract: A Catadioptric Light Distribution System is disclosed. The system collects and collimates the hemispherical pattern of light emitted by a Lambertian light emitting diode (LED) into a collimated beam directed essentially parallel to the optical axis of the LED. The system comprises a circular condensing lens having a center axis that is aligned with the optical axis of the LED and which is configured to receive an collimate a portion of the light from the LED defined by a central cone of light centered around the optical axis. A parabolic reflector having circular opening formed therethrough is centered on the center axis of the parabolic reflector and is positioned around the LED to receive and redirect the light which does not form the cone that impinges upon the condensing lens in a collimated annular beam in a direction away from the condensing lens. The light reflected and culminated by the parabolic reflector is directed onto a circular annular double bounce mirror which is configured and positioned to receive the annular beam from the parabolic reflector and reflect that beam of light 180° so that it is collimated in an annular beam which passes around the edge of the condensing lens. Thus, substantially all the light emitted by the LED is culminated into a beam of light that is substantially parallel to the optical axis of the LED by either the condensing lens or by the combination of the parabolic reflector and the double bounce mirror.

Shock wave therapy method and device

Abstract: An extracorporeal shock wave system provides a planar wave for the treatment of tissue. A parabolic reflector is provided in order to propagate the planar wave through a membrane and to the tissue of a human subject. A piezoelectric, electrohydraulic or electromagnetic source may be used to develop the wave.

Receiver tube with receiver tubular jacket and parabolic trough collector containing same

Abstract: The parabolic trough collector includes a single-axis parabolic mirror (1) and a receiver tube (2) arranged at the focal point (F) of the parabolic mirror (1). The receiver tube (2) includes an absorber tube (4) and an outer tubular glass jacket (3) around it. To compensate for focusing errors in the parabolic collector and thus to reduce associated geometric optical losses, the tubular jacket (3) is provided with structural elements (9 a , 9 b , 9 c , 9 d), which focus sunlight reflected from the mirror as well as sunlight that falls directly on the receiver tube from the sun on the absorber tube. The receiver tube is preferably arranged relative to the parabolic mirror, so that its center is displaced from the focal point (F) by a distance equal to half the spacing between the tubular jacket (3) and the absorber tube (4).

A mesh reflecting surface with electrical characteristics independent on direction of electric field of incident wave

Abstract: For large deployable antennas on board satellites, a knitted wire mesh is used as reflecting surface because it is lightweight and elastic due to its knitted structure. The mesh reflecting surface has high reflectivity for the electric field parallel to the wire running direction (Takano, T. et al., 1992). This nature of the mesh, the dependence of reflectivity on the direction of the incident wave's polarization, causes a problem that the axial ratio of a circularly polarized wave degrades. We previously reported the transmission loss of mesh reflecting surfaces made from meshes woven in conventional ways (Miura, A. and Tanaka, M., IEEE Topical Conf. on Wireless Commun. Technology, 2003). We now introduce a mesh reflecting surface woven in a new manner. This mesh has an adequate reflectivity with small variation of reflectivity depending on the direction of the electric field of the incident wave. The measured electrical characteristics of this mesh reflector are reported and compared with those of two conventional mesh reflecting surfaces. Parabolic reflector antennas have been made from the three meshes and their radiation patterns with a circularly polarized incident wave have been measured.

The MAGIC telescope reflecting surface

Abstract: The Major Atmospheric Gamma Imaging Cherenkov telescope will achieve an energy threshold lower than any other present IACT (E Th ∼30 Gev ) thanks to the largest reflecting surface, a 17 m diameter, f/1, tessellated parabolic reflector. The tiles are 50 cm ×50 cm all-aluminum spherical mirrors with different radii of curvature to best fit the paraboloid. The technology used to make these mirrors and the method used to measure their optical properties, as the focal length, the spot size and the reflectivity, are described. The results of these measurements are shown.

Vehicle headlight assembly

Abstract: An automotive headlight assembly includes a concave parabolic reflector having a focal axis and a focal point on the axis spaced from the reflector surface. A halogen light source is mounted on an elongated tubular conduit that is oriented on the focal axis of the parabolic reflector. A power mechanism is connected to the tubular conduit for sliding the conduit through a clearance opening aligned with the focal axis, so that the light source is moved between a high beam position on the focal point and a low beam position located at a different point on the focal axis, through an infinite number of in between positions, thus allowing the driver to adjust the focal point of the light to any desired distance.

Light emitting diode optics

Abstract: A bulb ( 10 ) for an automotive taillight has a central stem ( 12 ) that includes a base ( 14 ), a summit ( 16 ), and an intermediate portion ( 18 ). A parabolic reflector ( 20 ) is positioned about the base ( 14 ) and has a first reflector surface ( 22 ) facing the summit ( 16 ). At least one light source ( 24 ) is positioned on the summit ( 16 ) for directing primary illumination toward the reflector surface ( 22 ) on the reflector ( 20 ). In a preferred embodiment of the invention a plurality of light sources ( 24 ) are employed to even the distribution of light and the light sources are red light emitting LEDs. An optic ( 26 ) is associated with at least a part of the intermediate portion ( 18 ), the optic ( 26 ) having a second reflector surface ( 28 ) for directing secondary illumination toward the first reflector surface ( 22 ).

Torus-Less Inflated Membrane Reflector with an Exact Parabolic Center

Abstract: A possible alternative to the lenticular configuration, the concept of a torus-less pressurized membrane antenna with an exact parabolic center, is introduced. For a characteristic symmetric configuration, three membrane regions are identified: the parabolic reflector center, the (wrinkled) perimeter that suspends it, and a transition zone between. Via an analysis of the pressurization kinematics, the last of the three is seen as critical. Structural economy and optimization are considered, and a design paradigm is established and demonstrated. It is also shown that there can exist mechanically sound pressurized membrane shapes for which no strain-free initial configurations correspond. The study is restricted to the pressurized membrane itself: no application-specific system integration issues are addressed.

Ultraviolet illumination system for use in printing industry has strip light in focus of two-dimensional parabolic fixed reflector and has movable flat mirror to deflect light away from absorber

Abstract: The ultraviolet illumination system (30) has a strip light (31). This is placed in the focus of a two-dimensional parabolic fixed reflector (32). An approximately parallel beam of light leaves the lamp and reflector assembly. A flat pivoting mirror (35) is mounted in front of the lamp and the parabolic mirror to deflect ultraviolet light away from an absorber. The flat mirror may be placed parallel to the light beam to let most of the light through, or may be turned through 45 degrees to reflect the beam through 90 degrees. The flat mirror may be made in several sections (35.1-35.3).

The Constellation-X Spectroscopy X-ray Telescope

Abstract: The status of technology development for the Constellation-X Spectroscopy X-ray Telescope (SXT) mirror is presented. The SXT mirror combines a large (1.6 m) aperture with modest (12 arc sec half power diameter) angular resolution and low mass (750 kg). The overall collecting area, larger than 9,600 square cm at 0.25 keV, requires high throughput, and thus nesting of a substantial number of thin reflectors. A phased development program is underway to develop reflectors, mounting and alignment approaches, and metrology techniques for components and the mirror has a whole. The latest results in all these areas are summarized, along with an overview of results of optical testing of reflector performance.

Structural Design and Analysis of the Dish Solar Thermal Power System

Abstract: ISH solar thermal power system consists of a support, a concentrator, a receiver, a thermo-electric conversion unit and a sun-tracking control unit. The concentrator including a parabolic reflector, a truss and an elevation- driving circle, reflects the sun's rays into the receiver which is located at the reflector's focus. The concentrated solar energy is absorbed by the receiver and then converted into electricity by the thermo-electric conversion unit. The system works in an exposed environment bearing its own gravity and the wind load. The system's structure should be reasonably designed so that its reliability and stability can be assured. Recently, finite element method has become an effective tool for data analysis and it has been widely used in structural analysis and optimization design. The Visual Structural Analysis Program (VSAP), which is a finite element computation software, has a friendly interface for preprocessing and post-processing of finite elements and has the advantages of easy operation and mastery. Since VSAP is suitable for analyzing special structures, the 10KW dish solar thermal power system is designed and analyzed with VSAP. Furthermore, the problems associated with the concentrator's balancing and system's stability are solved.

Real-time goniospectrophotometer

Abstract: In accordance with embodiments of the present invention, a goniospectrophotometer is provided for quickly obtaining a goniospectrum using a goniospectrophotometer. In some embodiments, a parabolic reflector is used to optically transform the angular space of a source at the parabola focus into a linear space and facilitate the use of a single diffracting element and area camera to simultaneously measure the angular spectrum of the source. Spectra corresponding to zenith angles of light reflection by the parabolic reflector can be acquired by a detector and analyzed in a computer.

Telescope resolution using negative refractive index materials

Abstract: Concepts are presented for using negative refractive index (NRI) materials to design parabolic reflector telescopes and antennas with resolutions significantly better than the diffractions limit. The main question we are attempting to answer is can negative refractive material be used to improve performance of parabolic systems even when the signal or light source is far away and no evanescent fields are present when they arrive at the parabolic reflector. The main approach is to take advantage of any knowledge that we have to recreate the evanescent fields. Fields are then adapted to improve a performance measure such a sharper focus or antenna rejection of interference. A negative refraction index lens is placed between the conventional reflector and focal plane to shape the point spread function. To produce telescope resolutions that are better than the diffraction limit, evanescent fields created by the reflection off of the parabolic surface are amplified and modified to generate fields that sharpen the focus. A second approach use available knowledge of an emitting aperture to synthesize a field at a distance that matches as closely as possible the field of the emitting aperture. The yet unproven conclusion is that techniques can be developed that will improve antenna and telescopes resolution that is better than the diffraction limit.

Kilometer scale primary collector telescopy

Abstract: We present an improved model for a spectrographic survey telescope with a kilometer scale diffraction grating collector. Refining the initial public disclosures, the new model quantifies flux collection for telescopes of this type. An option in the new model allows a trade of reduced spectral bandwidth for increased flux collection. We provide experimental evidence to demonstrate an earlier prediction of Angstrom spectral resolution with relaxed tolerances for grating flatness. This model also posits a kilometer focal length secondary parabolic mirror and details its secondary spectrometer. Terrestrial installations for telescopes of this type can be at the ground level, presenting a near-zero wind profile despite the unprecedented kilometer scale aperture. The secondary, consisting of a parabolic reflector, is mechanically independent of the primary and completely static. The resulting open frame eliminates the need for a secondary spyder and has no obstructions in the active ray path. The grating primary can be combined with zenith tube liquid mirrors to provide full coverage of right ascension and all angles of declination. A folding mirror can be used as adaptive wave front correction. In space-based deployment, the kilometer length primary can be stowed as a membrane and unfurled in orbit using simple inertial forces.

Composite parabolic light-collecting comprehensive utilization device

Abstract: A composite parabolic light-gathering application device of combined heat and power is composed of a sunlight receiving system, a generating system and a box cooling-utilization system, characterized by using composite parabolic for light-gathering and installing solar cell for generating, and a heat exchanger is installed under the solar cell at the same time to realize refrigerant and heat recovery of solar cell The sunlight receiving system is composed of a plurality of units of composite parabolic light-gathering device 1 which is composed of two parabolic reflectors in the shape of dent, and the generating system is composed of a solar cell 2, an accumulator unit 9, a load 10 and a charge and discharge controller 11, wherein the solar cell 2 is connected with the charge and discharge controller 11 and the accumulator unit 9 in sequence to form a series circuit and is connected with the load 10 in parallel connection The cooling-utilization system is composed of a tube sheets heat exchanger 4, a reservoir 12, a circulation water pipe, a hot water outlet 13 and an admission port 14 to form cold-and-hot water circulation by using natural convection The device has a simple structure and no need for follow-up, capable of providing hot water and power and completely making efficient overall utilization of solar energy

Zero- and One-g Comparison of Ripple Amplitude in Single- Curved Parabolic Membranes using Photogrammetry

Abstract: This experiment was designed to quantify the effects of gravity and boundary support conditions on a scale model of an orbiting, singly-curved parabolic thin-film reflector planned for deployment by the end of this decade. As it is well-known that membrane elements supported in tension are prone to out-of-plane rippling, a 1-m scale model of the parabolic reflector support system was constructed and tested on NASA's KC-135A "Weightless Wonder" microgravity aircraft. Two membranes were tested: a fabric-backed metallized membrane (76.2 µm Nylon, 38.1 µm Mylar, 0.1 µm Al) and a 127 µm metallized Kapton membrane. Each membrane was placed in the fixture, and tensioned using edge clamps that maintained the desired parabolic profile at the membrane boundaries. Targets for tracking the full-field surface deflection were provided by about 7000 2-mm dots placed on the membrane surface. In flight, the membrane configuration was monitored by four digital cameras mounted in the test enclosure. Wide-angle lenses were used on the cameras, as they had to be mounted quite close to the membrane due to restrictions imposed by the size of the aircraft. Using photogrammetry, the high-resolution digital images taken in-flight (at zero-g conditions) and on the ground (at one-g) were processed, and the three- dimensional location of each target visible in at least three images was calculated. It was found that for the same boundary condition, surface rippling under zero-g conditions was less pronounced than at one-g conditions for the fabric-backed Mylar test article.

Light emission device, optical writing apparatus and optical communication apparatus

Abstract: PROBLEM TO BE SOLVED: To provide a configuration wherein light is emitted from a plurality of positions, in a light emission device utilizing a one-dimensional photonic crystal and having an array shape with an optional pitch SOLUTION: A one-dimensional photonic crystal multilayered film 2 wherein a plurality of defective layers 3 are provided in an array shape with a prescribed pitch is provided on one surface of a light guide body 1 A laser light source 4 is made to oppositely face to an inclined side surface 1a of the light guide body 1 A parabolic mirror 1b having the position of the light source 4 as a focal point and an optical axis (symmetric axis) orthogonal to the multilayered film 2 is disposed in the light guide body and all the incident luminous flux is reflected so as to be vertical to the multilayered film 2 Thereby, emission of the luminous flux is controlled by electric control of the defective layers 3 COPYRIGHT: (C)2006,JPO&NCIPI

Indicator lighting system for road vehicle has housing with front glass and lens in front of lamp and reflector unit held by snap fastenings

Abstract: The light module (1) is especially used as a brake light. It has a circular parabolic reflector (6) enclosing a main light bulb held in a housing (2) behind a cover glass with a refracting lens (3). The housing may be lined with a reflecting layer of aluminum. A reflecting tube (5) holds the parabolic mirror and the main light bulb and has a holder (11) with a LED (7) in the side, surrounded by a lens (8) to act as a side marker.

Lighting unit e.g. headlight, for motor vehicle, has light conductor which is mounted in series with light source and includes light conducting surface which is turned towards parabolic reflector

Abstract: The unit has a light source (10) e.g. electroluminescent diode, and a light conductor (20) mounted in series with the light source. The conductor has a light conducting surface (27) which is turned towards a parabolic reflector (40). Light rays emitted by the source are conducted through the conductor to reach the surface of the reflector and are diffused to the environment.

Optimization of the current integration method for a front-fed parabolic reflector antenna

Abstract: This work centers on an optimization of the current integration method for determining the field radiated by a centered parabolic reflector fed at its focus. A nonredundant sampling representation of the physical optics (PO) current, induced on the main reflector by the electromagnetic field radiated from the primary field source, and an optimal sampling interpolation algorithm are developed to this end. Such an approach allows one to reduce the number of points where the knowledge of the current is required, so that the computation time decreases remarkably when the evaluation of the field radiated from the feed is burdensome. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 235–239, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11339

Light path device with laterally standing box for large-area tester solar battery

Abstract: A light path device with laterally standing box for the large-area solar cell tester is composed of two pulse xenon lamps to form a linear light source, a parabolic reflector, barrier, spectrum correcting filter, silk screen filter, and adjustable guide track for putting the solar cell module on it. Its advantages are compact structure, and high light uniformity.

Etendue dependent optimization for coupling with dual paraboloid reflectors for projection display

Abstract: A dual paraboloid reflector system conserves the source brightness by producing a real image of the arc on the target space. Traditional elliptical and parabolic reflector tends to degrade the brightness of the arc due to the angular dependence of the magnification such that the image at the target space is the superposition of multiple images of the arc with varying degree of magnifications. In this paper, we present steps for optimizing a projection illumination system consisting of the dual paraboloid reflectors. The effects of various parameters including reflector sizes, scattering and angular extents were evaluated using ray-tracing model. The results of the calculations are compared with experimental measurement.

Nanocarbon-producing device

Abstract: In a nanocarbon-producing device (173), a plane mirror (169) and a parabolic mirror (171) are arranged in a production chamber (107). Light, emitted from a laser light source (111), transmitted through a ZnSe window (133) is reflected at the plane mirror (169) and the parabolic mirror (171), collected at the parabolic mirror (171), and then irradiated onto the surface of a graphite rod (101).

Process for the direct conversion of solar energy into mechanical energy has two adjacent beams of bimetallic working elements onto which a parabolic mirror alternately reflects rays

Abstract: A process for the direct conversion of solar into mechanical energy comprises using two aluminum or brass beams (1) of thin-walled double-T profile with a steel lower draw band (2) connected by a drive (11) to an electric generator (12) Sunlight is reflected from a parabolic mirror and controlled to fall alternately on the two profiles An independent claim is also included for a device for the above process

A large bifacial photovoltaic-thermal hybrid low-concentrating module

Abstract: Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimensional parabolic reflectors were studied and optimised, and a new biaxial model for the incidence angle dependence of the optical efficiency was proposed. Concentration of light generally results in high cell temperatures, and the uneven irradiance distribution on cells with parabolic reflectors leads to high local currents and temperatures, which reduce fill-factor and voltage. Cooling the cells by means of water increases the voltage and makes it possible to utilize the thermal energy. The performance of a 4X concentrating photovoltaic-thermal system was evaluated. If operated at 50°C, this system would produce 250 kWhelectrical and 800 kWhthermal per m2 cell area and year. Optical performance can be increased by 20% by using better reflectors and anti-reflectance glazing. Low-concentrating photovoltaic systems for facade-integration were studied and optimised for maximum annual electricity production. The optimisation was based on measured short-circuit currents versus solar altitude. Measurements were performed outdoors and in a solar simulator. It was found that the use of 3X parabolic reflectors increases the annual electricity production by more than 40%. High solar reflectance is crucial to system performance but by using a low-angle scattering reflector, the fill-factor and power are increased due to a more even irradiance on the modules. Long-term system performance depends on the durability of the components. The optical properties and degradation of reflector materials were assessed using spectrophotometry, angular resolved scatterometry, Fresnel modelling, optical microscopy, and surface profilometry before and after ageing. The degradation of reflectors was found to be strongly dependent on material composition and environmental conditions. Back surface mirrors, all-metal reflectors, and polymer-metal laminates degraded in different ways, and therefore accelerated ageing must be tailored for testing of different types of reflector materials. However, new types of reflector laminates showed a potential for increasing the cost-effectiveness of low-concentrating solar energy systems.