Showing papers on "Parabolic reflector published in 2003"

Concentrating solar energy receiver

Abstract: There is disclosed herein a concentrating solar energy receiver comprising a primary parabolic reflector having a center and a high reflectivity surface on a concave side of the reflector and having a focal axis extending from the concave side of the reflector and passing through a focal point of the primary parabolic reflector, and a conversion module having a reception surface wherein the reception surface is spaced from the focal point by a predetermined distance and disposed to receive a predetermined cross section of radiant solar energy reflected from the concave side of the primary parabolic reflector for conversion to electrical energy in the conversion module. In one aspect, the conversion module includes a reception surface comprising a planar array of at least one photovoltaic solar cell. In another aspect, the conversion module includes a reception surface coupled to a thermal cycle engine. The mechanical output of the thermal cycle engine drives an electric generator.

Composite reflecting surface for linear LED array

Abstract: A composite reflecting surface for a linear LED array incorporates a truncated circular parabolic reflector surrounding each LED and a trough axially above the circular parabolic reflectors defined between parallel longitudinal reflecting surfaces. The short circular parabolic reflectors collimate wide angle light from the LED into a direction parallel to the LED optical axis. The longitudinal reflecting surfaces are linear parabolic surfaces altered to improve the vertical spread of the light radiation pattern. Longitudinal convex ribs project inwardly from the basic linear parabolic shape. The convex shape of the ribs “sprays” the light incident upon it in a vertically spread pattern. The composite reflecting surface makes use of light from a linear array of LEDs that would otherwise be wasted.

Compact micro-concentrator for photovoltaic cells

Abstract: A reflector array comprises a plurality of partial parabolic reflectors arranged in rows and columns with each reflector directing radiation to a receiver or from a transmitter located at the focus of the reflector. In a compact photovoltaic cell arrangement, each cell is shielded from direct radiation by the adjacent reflector. The reflectors can be formed as one unit with reflective material or with the reflecting surfaces coated with aluminum, silver, or other suitable reflecting material. A secondary reflector can be positioned at the focus of a reflector for directing radiation to a receiver or from a transmitter located at a more accessible location in the array.

Probing highly confined optical fields in the focal region of a high NA parabolic mirror with subwavelength spatial resolution.

Abstract: Parabolic mirrors with a high numerical aperture can be conveniently used to produce highly confined optical fields in the focal region. Furthermore, these fields can have interesting polarization behaviour due to the high numerical aperture. In particular, if the mirror is illuminated with a size matched radially polarized or azimuthally polarized doughnut mode, the electric field has in the focal region almost exclusively a longitudinal or a transverse polarization component. Such field distributions are interesting for applications in confocal or near-field optical microscopy. Here we present experimental results where we have probed some of these field distributions by raster scanning a fine gold tip in nanometer steps through the focal region and detecting the scattered light intensity. The measured intensity patterns are compared with corresponding vector-field calculations.

Offset cylindrical reflector antenna fed by a parallel-plate Luneburg lens for automotive radar applications in millimeter-wave

Abstract: Using a single offset cylindrical parabolic reflector and a parallel-plate Luneburg lens, a novel high-gain and high-efficiency antenna is developed for automotive radar at mm-wave frequencies. Particularly, a pair of small corrugated extensions is added to the lens for a cylindrical wave. Thus, by feeding a cylindrical wave to the reflector, especially the performance in elevation is enhanced, keeping the complete antenna compact. For verification, a prototype antenna for an adaptive cruise control radar at 76.5 GHz is designed and measured. The theoretical results are verified with good agreement.

Near-field line-integral representation of the Kirchhoff-type aperture radiation for a parabolic reflector

Abstract: A line-integral representation is presented for a linearly polarized Kirchhoff-type aperture radiation from a parabolic reflector antenna. The main purpose of this result is concerned with the acceleration of the numerical integration for calculating the near field of large reflector antennas. The formulation, which is rigorous for a uniform aperture field, is based on the application of the equivalence principle to a projecting surface, which allows the analytical evaluation in a closed form of a twofold surface integral which defines the radiated field at any space point; the extension to a slowly varying primary feed pattern is based on an asymptotic approximation, which is proved to be accurate in the proximity of the aperture to -30 dB of amplitude edge illumination. The present formulation is well suited to be improved by fringe diffraction contributions in the framework of edge-wave theories such as the physical theory of diffraction (PTD) and the incremental theory of diffraction (ITD).

Projection-type image display device

Abstract: A projection-type image display device includes a light source, converging optics, a rod integrator having a first optical axis, a light deflecting structure, and a light beam separating structure The light beam separating structure directs light to a digital micromirror device and modulated light from the digital micromirror device along a second optical axis of a projection lens that projects an image formed by the modulated light on a screen The rod integrator is between the light beam separating structure and the projection lens in the direction of the second optical axis and is outside the optical path of the modulated light beam from the digital micromirror device The rod integrator may include a solid rod member and a leaky ray shielding member at least at one of the entrance end, the exit end, and around the solid rod member The converging optics may include a parabolic reflector and an aspheric lens

Indirect luminaire optical system

Abstract: An indirect luminaire optical system having linear tubular lamps, parabolic reflector assemblies positioned under the lamps, kick reflectors positioned adjacent to the sides of the lamps, and a housing positioned around the lamps and reflectors, with the housing having a substantially open top for allowing light to exit the optical system. Each parabolic reflector assembly may have a pair of substantially parabolic shaped reflectors joined to form a apex along and directly under the corresponding lamp lamp. The kick reflectors may be in a spaced relationship with the parabolic reflector assemblies, thereby defining openings therebetween. The bottom portion of the housing may have translucent areas which are in optical communication with the lamp through the openings.

Parabolic Mirror and Air-Coupled Transducer for Multimodal Plate Wave Detection

Abstract: A conventional contact piezoelectric transducer, excited by a broadband burst (chirp) that covers its whole frequency bandwidth, is used as a transmitter to simultaneously generate several Lamb waves in a plate Throughout the propagation, these modes leak energy into the ambient air, producing bulk waves in many directions The association of a parabolic mirror and an air‐coupled transducer (PMAT) allows these waves to be received in air with a large angular aperture By displacing the PMAT in a direction parallel to the plate, but without changing its orientation like when standard air‐coupled receivers are used, a series of temporal waveforms are captured Signal processing then allows the phase velocity of the several Lamb waves to be measured in large wave number and frequency domains These resulting data are used to identify the moduli of elasticity for composite plates made of long glass fibers and polymer matrix

Heat Losses from the Receivers of a Multifaceted Parabolic Solar Energy Collecting System

Abstract: Heat losses from the receivers of a dish-type solar energy collecting system at the Korea Institute of Energy Research (KIER) are numerically investigated. It is assumed that a number of flat square mirrors are arranged on the parabolic dish structure to serve as a reflector. Two different types of receivers. which have conical and dome shapes. are considered for the system. and several modes of heat losses from the receivers are thoroughly studied. Using the Stine and McDonald model convective heat loss from a receiver is estimated. The Net Radiation Method is used to calculate the radiation heat transfer rate by emission from the inside surface of the cavity receiver to the environment. The Monte-Carlo Method is used to predict the radiation heat transfer rate from the reflector to the receiver. Tracing the photons generated. the reflection loss from the receivers can be estimated. The radiative heat flux distribution produced by a multifaceted parabolic concentrator on the focal plane is estimated using the cone optics method. Also. the solar radiation spillage around the aperture is calculated. Based on the results of the analysis. the performances of two different receivers with multifaceted parabolic solar energy collectors are evaluated.

Method and apparatus for infrared welding of thermoplastic parts

Abstract: An infrared welder for thermoplastic materials comprising the combination of a halogen lamp producing illumination in the infrared band located at the focal point of a first parabolic reflector. The parabolic reflector is joined in a substantially continuous fashion with a non-imaging lower reflector such as a Winston cone or a “CPC” having a lower aperture through which essentially all of the radiation from the source is directed. The aperture defines the shape and size of the weld area. The lower reflector may be brought into contact with the thermoplastic materials during the welding operation. Alternatively, a selectively operable press device may be used. Several embodiments are disclosed including embodiments which produce circular spot welds, linear welds, curved welds and corner welds.

Optical assemblies for concentration of radial light distribution within confined luminaire packages

Abstract: An optical assembly for architectural illumination which includes a quasi point source surrounded by a collimating ring lens designed to radially project collimated beams. A segmented, off axis, parabolic reflector to collect and reflect light (not gathered by the collimating ring lens) as collimated beams and a ring reflector, the segments of which designed to gather beams from both the collimating ring lens and the off axis reflector and the direct them in substantially the same direction.

Motor vehicle headlamp with enhanced light dark boundary on the road has light diode source with ovoid central region and two parabolic reflectors

Abstract: A lamp, especially for a motor vehicle, comprises a field of separate optics from a semiconductor light source, especially light diodes. The light opening comprises a long rectangle giving an ovoid central region (10) perpendicular to the light entry surface combined with two parabolic reflectors (40a,b,42a,b) giving a beam perpendicular to the axis (30).

Apparatus and method for optical characterization of a sample over a broadband of wavelengths with a small spot size

Abstract: An apparatus and method for optically characterizing the reflection and transmission properties of a sample with a beam of light having a small diameter on a surface of the sample over a broadband of wavelengths, from 190 nm to 1100 nm Reflective optical components, including off-axis parabolic mirrors with a collimated incident or reflected broadband beam of light, minimize non-chromatic aberration The apparatus and method further disclose an optical light path that can be focused by adjusting the position of an off-axis parabolic mirror and a planar mirror

Hybrid synthetic/real aperture antenna for high resolution microwave imaging

Abstract: Observations of key hydrological parameters at the spatial and temporal scales required in the post-2002 era face significant technological challenges. These measurements are based on relatively low frequency thermal microwave emission (at 1.4 GHz for soil moisture and salinity, 10 GHz and up for precipitation, and 19 and 37 GHz for snow). The long wavelengths at these frequencies coupled with the high spatial and radiometric resolutions required by the various global hydrology missions necessitate the use of very large apertures. Two-dimensional Synthetic Thinned Array Radiometry (2-D STAR), though promising in the long term, has many technical challenges in the areas of power, and sensitivity for very large apertures (i.e. greater than 300 wavelengths). This paper will discuss an alternative approach to the pure 2-D STAR, which uses an offset parabolic cylinder reflector fed by multiple elements to form a 1-D STAR. In essence a single STAR element is composed of a feedhorn and parabolic cylinder reflector. The elements are sparsely arrayed and thus can share a single reflector. This antenna would have no moving parts once deployed, have much higher sensitivity than a Y-shaped 2-D STAR of equivalent size, many fewer receivers than that 2-D STAR, and the reflector could be made of a thin film and lightweight deployment system for high packing density. The instrument using this approach would be a cross track push broom imager. An overview of the design parameters, potential deployment mechanisms and applications will be presented.

Achromatic spectroscopic ellipsometer with high spatial resolution

Abstract: Disclosed is an achromatic spectroscopic ellispometer for analyzing small regions of a sample over a wide range of wavelengths from ultraviolet (UV) to infrared (IR). The spectroscopic ellipsometer contains a light source emitting a light beam which passes through a polarisation state generator section before being focused at an incidence angle q by a first parabolic mirror to a small spot on a sample. A second parabolic mirror collects the reflected beam and connects said beam to an analyzing section. The reflected beam emerges from the analyzing section and is spectroscopically detected and analyzed. The light beam through the polarisation state generator section up to the first parabolic mirror and the light beam from the second mirror through the analyzing section are parallel enabling achromatism. The incidence angle q is largely varied without shifting of the location of the small spot on the sample surface.

Tapered waveguide with parabolic lens: theory and experiment

Abstract: Theoretical and experimental work to integrate parabolic intracavity lens into a high-power tapered ridge-waveguide semiconductor laser diode is carried out. A finite difference beam propagation model is used to simulate the laser operation with and without the lens. Focused ion-beam etching is used to integrate the lens with the laser cavity. The lens is designed to compensate for the phase curvature of the incident mode on the output facet. This leads to improved linearity in the light-current characteristics of the device, showing an increase of up to 47% in power slope efficiency, 2-μm broadening in near field pattern, and 1-deg narrowing in the far-field pattern.

Shaping of parabolic cylindrical membrane reflectors for the DART precision test bed

Abstract: The DART is a new telescope architecture consisting of two cylindrical parabolic reflectors. The system is ideally suited to using tensioned membranes for the reflective surfaces, owing to the zero Gaussian curvature of a cylindrical parabola.

Coupling of light from small lignt source for projection systems using parabolic reflectors

Abstract: A portion of a first paraboloid collects and concentrates randomized light from a lamp into parallel beams directed to a portion of a second paraboloid which refocuses the light onto a homogenizer. The second paraboloid has a shape that is substantially similar to the first paraboloid reflector. The source and the target are located at the respective foci of the paraboloids such that the optical flux from the source is imaged to the target with minimal distortion in an approximately no magnification imaging system. The system may be configured to control wavelength and intensity by inserting an additional filter. In addition, a retro-reflector may be added to increase the overall flux density at homogenizer. The output is particular suitable for providing light to the light engine of projectors.

Method and apparatus for measuring field in compact range

Abstract: PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring a field in a compact range which measure a distribution of the radiation field in a predetermined plane by using an antenna module having a transmission antenna and a reception antenna integrally formed. SOLUTION: The antenna module 4 having the transmission antenna 41 and the reception antenna 42 integrally formed is disposed at a focus of a parabolic reflector 1 and connected to a vector network analyzer 3. A reflection panel 21 for returning a predetermined RCS is installed in a field scanner 2 so as to move within a plane opposite to the parabolic reflector. Information of an amplitude and a phase variation of an electromagnetic wave obtained from a calculation process by a S21 method implemented by the vector network analyzer 3 is outputted to a computer apparatus 5. COPYRIGHT: (C)2004,JPO

Controlled solar device

Abstract: An apparatus for converting dynamic solar energy to controllable one for cooking, electric generation, lighting, etc is characterized by that a large parabolic reflector is used for tracking the sun and gathering the sunlight to a focuse point, a small parabolic reflector at said focus point is used to make the gathered sunlight become dense parallel light beams, and serially connected 4 right-angle turning units are used to convert the direction-changing parallel light beams to the dense ones with the direction controlled manually.

Method and instrument for measuring bistatic radar cross-sectional area

Abstract: PROBLEM TO BE SOLVED: To provide a method and instrument by which the bistatic radar cross-sectional area of an object can be measured easily even in a limited space. SOLUTION: The instrument has a transmission antenna 6 disposed at the focal position of a parabolic reflector 1 and uses a compact range which forms an electromagnetic far field falsely by means of the reflector 1. In the instrument, an object 8 to be measured is rotatably provided in a space facing the reflector 1, and a reception probe 7 is disposed toward the object 8 so that the probe 7 may move around the object 8. The bistatic radar cross-sectional area of the object 8 is measured by rotating the object 8 around a rotating shaft perpendicular to the radiated direction of electromagnetic waves radiated from the reflector 1 and, at the same time, by rotationally moving the reception probe 7 around the rotating shaft. COPYRIGHT: (C)2004,JPO

Segmented reflector systems and combined reflector and refractor systems

Abstract: An optical assembly for architectural illumination having a quasi point source surrounded by a collimating ring lens designed to radially project collimated beams. A segmented off axis parabolic reflector to collect and reflect light (not gathered by the collimating ring lens) as collimated beams and a segmented ring reflector, the segments of which are arranged to gather beams from both the collimating ring lens and the off axis reflector and then direct them in substantially the same direction.

Calculation of non-axisymmetrical parabolic reflector antennas

Abstract: An aperture method is used for calculation of non-axisymmetrical parabolic reflector antennas. The possibility of scanning of horizontal-plane pattern at rotation of reflector at fixed radiatorer is investigated. The results of numerical and measurement experiments are presented in the paper.

Radiant light collection and distribution from segmented reflector systems and combined reflector and refractor systems

Abstract: An optical assembly for architectural illumination having a quasi point source surrounded by a collimating ring lens designed to radially project collimated beams. A segmented off axis parabolic reflector to collect and reflect light (not gathered by the collimating ring lens) as collimated beams and a segmented ring reflector, the segments of which are arranged to gather beams from both the collimating ring lens and the off axis reflector and then direct them in substantially the same direction.

Proposal for enhanced spatial resolution and efficiency of a fast-neutron scintillator detector by use of a parabolic mirror

Abstract: The limitation on the detector efficiency due to the required spatial resolution of a fast-neutron imaging system is known as the detector problem. Here, this problem is described and a proposal for a novel fast-neutron imaging system is given to overcome this problem. The novelty is to replace the standard flat mirror in an imaging system by a parabolic mirror with its focal point at the fast-neutron source position. The spatial resolution will only be limited by the intrinsic resolution of the scintillator of the order of 0.06 mm. The intrinsic fast-neutron detection efficiency can be increased to about 20–30% without loss of spatial resolution.

Novel beam scanning technique for circularly-polarized reflector antennas

Abstract: This paper introduces a new technique for scanning circularly-polarized (CP) beams in reflector antennas. The technique explores the intrinsic properties associated with crosspolarization (XPOL) and beam squint in offset parabolic reflectors. Furthermore the beams are scanned while keeping the whole reflector system focused throughout the scanning process, thus reducing degradations commonly encountered in other procedures. Preliminary numerical results indicate the viability of the proposed procedure over limited scan regions (e.g., /spl plusmn/2/spl deg/), which suggests its use in space applications.