Showing papers on "Parabolic reflector published in 2005"

Illumination apparatus and a liquid crystal projector using the illumination apparatus

Abstract: An illumination apparatus includes a reflector including a parabolic or ellipsoidal mirror, a light source arranged near a (first) focal point of the reflector, and a front mirror having a transparent window and a mirror surface symmetrical about the light axis. Luminous flux emitted from the light source is reflected from the reflector. In the case of the parabolic mirror, the front mirror has the same size as an entrance of an output light utilizing optical system, and the luminous flux exits toward the optical system as collimated light. In the case of the ellipsoidal mirror, the front mirror is arranged between two focal points of the ellipsoidal mirror, and the luminous flux is directed toward the second focal point. However, at least one part of the luminous flux is reflected from the front mirror and returned toward the first focal point.

Optical Design and Characterization of Solar Concentrators for Photovoltaics

Abstract: Stationary solar energy concentrators are a promising option for decreasing the price of photovoltaic electricity. This thesis studies stationary concentrators in PV/Thermal applications. The studied systems are parabolic troughs intended for building integration. The first chapters briefly explain the optics of solar energy concentrators. The theoretical maximum concentration ratios of two and three dimensional systems were derived using the concept of etendue conservation and a review of current concentrators was presented. An asymmetrically truncated compound parabolic concentrator, CPC, for flat roof integration was characterized as an example of a stationary concentrator. The current-voltage characteristics were measured, the optical efficiency was calculated, and the annual thermal and electrical output were simulated. This was done for two systems, one with aluminium reflectors, and one with aluminium laminated steel reflectors. The output estimates show no difference in annual output between the two materials. It was estimated that the bifacial system would produce 37% more electricity than a reference mounted in the plane of the concentrator aperture. The estimated annual output of thermal energy was 145 kWh/m2 of hot water at 50°C. It was concluded that the system should have cells facing both the front and back reflectors to maximize the system performance. The actual output of stationary concentrators with standard photovoltaic cells is often lower than what could be expected. This is due to the highly non-uniform irradiation distribution on the cells created by the parabolic reflectors. Three microstructured reflectors in asymmetric CPC troughs were evaluated using ray tracing in an attempt to homogenize the irradiation on the cells. The simulations show that all three proposed structures reduce the peak irradiance with only small reductions in the optical efficiency. The microstructured reflectors were shown to increase the concentration ratio of the troughs which gives higher flexibility in designing new concentrators. The structured reflector troughs had a high optical efficiency when the sun was in the meridian plane, but the structures lowered the efficiency outside this plane. This was due to the disruption of the translational symmetry when the microstructured reflectors were introduced. It was concluded that structured reflectors are used at their largest benefit if they are applied in new concentrators designed for structures. For the existing designs, only a small input increase can be expected when structured reflectors are used. A new biaxial model for the incidence angle dependent optical efficiency of concentrators was presented. It is valid for translationally symmetric concentrators, flat plate collectors, and planar photovoltaic modules. It models the reflector and the cover glazing separately, and these model functions are multiplied at each angle of incidence to form the system model. The optical efficiency of the reflector was modelled as a function of the transverse angle of incidence. Existing models tend to overestimate the optical losses of the cover glazing, and the proposed model addressed this problem by modelling the optical efficiency of the glazing as a function of the true angle of incidence. The biaxial model was used to estimate the annual output of electricity from a concentrator and the estimates were compared with measurements during two summer months. The comparison showed that the proposed model is a good tool for estimating the output of photovoltaic concentrators. (Less)

Fully reflective deep ultraviolet to near infrared spectrometer and entrance optics for resonance Raman spectroscopy

Abstract: We present the design and performance of a new triple-grating deep ultraviolet to near-infrared spectrometer. The system is fully achromatic due to the use of reflective optics. The minimization of image aberrations by using on- and off- axis parabolic mirrors as well as elliptical mirrors yields a strong stray light rejection with high resolution over a wavelength range between 165 and 1000nm. The Raman signal is collected with a reflective entrance objective with a numerical aperture of 0.5, featuring a Cassegrain-type design. Resonance Raman studies on semiconductors and on correlated compounds, such as LaMnO3, highlight the performance of this instrument, and show diverse resonance effects between 1.96 and 5.4eV.

Off-axis parabolic reflector

Abstract: A lamp (8, 108, 208) includes a reflector (10, 110, 210) with a plurality of off-axis reflector segments (20, 22, 24, 120a, 120b, 220). Each off-axis reflector segment has a focus at a perimeter (12, 112, 112a, 112b, 212) of the reflector. A plurality of light emitting elements (40, 42, 44, 140a, 140b, 240) are disposed at the foci of the off-axis reflector segments.

Parabolic antenna of a level measuring instrument and level measuring instrument with a parabolic antenna

Abstract: This invention concerns a parabolic antenna with a parabolic reflector ( 2 ) having a parabolic reflector rim ( 20 ), a collar ( 9 ), which is positioned on the parabolic reflector ( 2 ), in particular on the parabolic reflector rim ( 20 ) and which has an outside collar rim ( 90 ), and having an exciter and/or a receiver ( 3 ), such that the exciter and/or receiver ( 3 ) are/is located in the axial direction (X) partly within the parabolic reflector rim ( 20 ) and partly outside thereof.

Kirkpatrick-Baez type x-ray focusing mirror fabricated by the bent-polishing method

Abstract: Microfocusing optics with total reflection mirrors has been constructed, and a performance test in the hard x-ray region has been carried out. The material of the mirror is fused quartz, and parabolic surface figures are fabricated by the bent-polishing method. The reflective surface is coated with platinum. By configuring two parabolic mirrors in the Kirkpatrick-Baez optics, a focused beam size of 150nm in the vertical direction ×110nm in the horizontal direction has been achieved at an x-ray energy of 12keV. A focused beam size of smaller than 300nm is obtained within an x-ray energy range of 8–28keV. In a performance test of the scanning microscope, fine periodic structures with a line pitch of 140nm are clearly resolved. Diffraction limit and modulation transfer function of these focusing optics are discussed.

An array-compensated spherical reflector antenna for a very large number of scanned beams

Abstract: There are many stringent demands imposed on the applications of spaceborne antenna systems. One of the most challenging demands is the generation of multiple beams with the ability to scan a very large number of beamwidths. Since the parabolic reflectors have limitations in this application, a 35-m spherical reflector antenna is proposed for a geostationary radar antenna at Ka-band (35.6 GHz) due to its inherent capability of scanning the beams to very large number of beamwidths. The utility of using planar array feeds for correcting spherical phase aberrations is investigated to overcome the performance degradation effects. Two different methodologies are developed for the array excitation coefficients determination based on phase conjugate matching and the results are compared. Using the compensating feed array, the radiation characteristics of the compensated spherical reflector are simulated for no scan and large scan cases and the results are compared with the uncompensated case to show performance improvement. In order to demonstrate the technological readiness of the concept a 1.5-m breadboard model is designed to be built for experimental measurements. Some important mechanical design tolerances and realistic array feed topologies are investigated. The antenna concept developed in this paper is advocated to be used in the next generation of geostationary satellite antenna systems for remote sensing radar applications.

Stroboscopic led light source for blood processing apparatus

Abstract: The invention relates to apparatus for controlling the processing of blood into blood components, particularly components for stroboscopic LED light sources for centrifuges. The stroboscopic apparatus comprises a first light source (110) with reflective surfaces spaced around a central illumination axis, and light-emitting diodes (1336) spaced away from the axis radially outward from the reflective surfaces. An additional light source (230) comprises a modified parabolic reflector surrounding a light emitting diode, the parabolic reflector having walls spaced outwardly from an axis of symmetry such that focal points fall radially outwardly from a center of the LED, forming a circular focal area. A controller (225) that energizes the diodes for selected periods of time comprises a pair of switches connected in series, with an LED connected between the switches. One of the switches is connected to ground and is closed at the end of a period of illumination.

Testing a fast off-axis parabolic mirror using tilted null-screens

Abstract: We propose the design of tilted null screens in order to test the off-axis segments of conic surfaces. Furthermore we reduce the size of the screen in order to increase the performance of the test. The sensitivity is increased while the size of the screen is reduced in the saggital caustic region and vice versa in the tangential caustic region. Further analysis and experimental results are presented, for an off-axis concave parabolic mirror which has an elliptical aperture, with a distance offset Xc =25.4mm, the radius of curvature at the vertex R = 20.4mm, major axis of the mirror DM =49.4mm and minor axis Dm=29.5mm.

Rectangular parabolic reflector by means of multiple mirrors

Abstract: PROBLEM TO BE SOLVED: To provide a rectangular parabolic reflector by means of multiple mirrors, that is simple and capable of making economy compatible with efficiency. SOLUTION: A bookshelf-shaped box is sealed with glass so that mirror surface will not be contaminated, and an actuator is controlled by a computer so that multi-mirrors focus one point, thereby reducing the installation area and also serving, as a wall. The reflector is divided into many parts and made as a reflecting surface as a whole, to function as a focusing concave mirror, and a heat pipe is also used, thereby making economy, and efficiency, compatible, in a simple manner. COPYRIGHT: (C)2007,JPO&INPIT

Off-axis parabolic mirrors: A method of adjusting them and of measuring and correcting their aberrations

Abstract: This paper proposes a method of adjusting off-axis parabolic mirrors, based on the minimization of beam-quality parameter M². This method requires no additional adjustment elements and possesses adequate accuracy: 1% for the angular orientation of the mirror and 2.3% for the rms deviation of the M² value. An experimental technique is given for measuring and correcting the aberrations of strongly focusing off-axis optical elements. The technique is based on measuring the wave front by the Shack-Hartmann method. The aberrations were corrected using a controllable flexible mirror in the manual and automatic regimes by the aperture-probing and phase-conjugation methods, respectively. © 2005 Optical Society of America

Adaptive nulling with a reflector antenna using movable scattering elements

Abstract: This paper describes an adaptive nulling system for reflector antennas that uses a genetic algorithm to mechanically adjust scattering elements in order to place nulls in the sidelobes of cylindrical parabolic reflector antennas.

Off-axis paraboloid interferometric mirror with off focus illumination

Abstract: An off axis paraboloid mirror is used to provide object illumination in an interferometric imaging system. The light from an object illumination light source diverges from a point apart from the focus point of the paraboloid, proceeds to the parabolic mirror surface, and is reflected as a nearly parallel beam to illuminate the object.

Deployable reflector system for satellite applications

Abstract: A prototype is herein presented for a new mechanism for deploying reflector antennas introduced by the authors in M. Terada et al. (2005, 1999). The prototype, herein referred to as DRSAT (deployable reflector for satellite applications), was constructed using sheet aluminum, a fine metal mesh, an existing feed and low noise block, and a directionally adjustable base. The deployment mechanism and reflector surface were designed and constructed using these base materials. The DRSAT design employs a 39-cm offset reflector antenna, which when collapsed occupies less than 0.03 m/sup 3/. Computer simulations performed with the program PRAC (parabolic reflector analysis code) (M. Terada, 1999) were conducted to validate the design and assess the impact of surface errors during manufacturing.

Parabolic aerial for fill level measurement, comprises parabolic mirror, exciter, and diffusion disc arranged in center of parabolic mirror for laterally removing interfering fraction of electromagnetic waves past the exciter

Abstract: A parabolic aerial comprises a parabolic mirror (2), an exciter (3) for transmitting electromagnetic waves to the parabolic mirror, and a diffusion disc (1) for laterally removing interfering fraction of electromagnetic waves past the exciter. The parabolic mirror concentrates the electromagnetic waves. The diffusion disc is arranged in the center of parabolic mirror. The shape of diffusion disc is such that a beam of parallel radiation that impinges the diffusion disc along an axis from the exciter is diverted from the axis by a backscatter process at the diffusion disc. Independent claims are included for: (1) a fill level radar; and (2) fill level measurement.

Collimator optical system and illumination optical system

Abstract: PROBLEM TO BE SOLVED: To provide a reflection member or collimator optical system which performs deformed illumination only by itself without installing any mechanism which needs replacement such as a shading plate and a fly eye mirror. SOLUTION: The collimator optical system which is used in a reflection type illumination optical system, etc. to convert incident flux of light into parallel flux of light is constructed by a parabolic reflector divided into a plurality of parts, and performs deformed illumination by changing the arrangements of the divided parts of the parabolic reflector. Specifically, the parabolic reflector is divided into four parts, each of which is equipped with a driving mechanism, and the positions of the divided parts of the parabolic reflector are adjusted by the driving mechanisms. Thus, parallel flux of light which is necessary for various deformed illuminations such as zonal illumination and multipolar illumination is obtained by just one collimator optical system. COPYRIGHT: (C)2005,JPO&NCIPI

Image entropy as a metric for iterative optimization of large aberrations

Abstract: Image metric optimization is an attractive alternative to conventional wavefront sensing for optical systems that are constrained by weight, cost, size, and power consumption and required to operate using light from extended object scenes. For these optical systems, an image metric optimizer must be able to function in the presence of potentially large system aberrations. This paper examines the usefulness of image entropy as a metric for measuring changes in image quality in the presence of large aberrations. In our experiment, we use a liquid-crystal spatial light modulator as a programmable diffractive optic to compensate for roughly 40 waves of peak-to-valley aberration introduced by using a parabolic mirror tilted 5 degrees off the optic axis. The results of our experiment show that image entropy does function well as a metric for measuring changes in image quality for 20 waves of aberration or less. For aberrations greater than 20 waves peak-to-valley the total optical power incident on the camera is a better metric.

Angle multiplexing holographic storage device and method

Abstract: In an angle multiplexing holographic storage device, a movable beam splitter is used for splitting a source beam into an object beam and a reference beam. An encoding device is used for encoding the object beam with pixel data. A parabolic reflector differentially reflects the reference beam with the movement of the movable beam splitter. A holographic storage medium is arranged at the focal point of the parabolic reflector and made to lie in the optical path of the encoded object beam so that the differentially reflected reference beams encounter and interfere with the encoded object beam at the same site of the holographic storage medium to form and record various interference patterns.

Phasing a segmented mirror using the subapertures method

Abstract: At the present time, some astronomical telescopes exist with segmented primary mirrors, as those located in Mauna Kea, Hawai. The Keck telescopes are a classical example. With the purpose of collecting light of weak stellar objects, it is necessary to control the segments of the primary mirror of the telescope, so that whole mirror works as a monolithic mirror. In this paper, it is proposed the subapertures method for the alignment of the segments of the primary mirror. The subapertures method finds tilt, tip, and pistons effects or longitudinal displacements as the defocus error; all of them are necessary to achieve the fitting of a series of measurements. It is shown the experimental results for a parabolic mirror divided in two segments using the proposed method; for this case, the particular equations were developed as well as the necessary software for the alignment of the two parts. The experimental results were obtained in a controlled situation in the laboratory. The alignment process is achieved in a short time, and furthermore is an interactive process.

Detection device comprising a parabolic mirror and use of said device in an overflight machine

Abstract: The invention relates to a detection device, comprising a parabolic mirror (1) and several radiation detectors (2-5). The detectors are placed in the focal plane (O, X'-X, Y'-Y) of the mirror with respective spacings in a common fixed direction (Y'-Y). The detection device further comprises a selector system, connected to each of the detectors (2-5), embodied to successively select each of the detectors and to transmit a received signal from the selected detector. The separations of the detectors (d2-d5) are selected such that a gain diagram, for the reception of said device, has a gain minimum, between two successive gain maxima, each corresponding respectively to one of the detectors, of less than 3.0 dB less than said gain maxima. Such a device permits a sweeping of a zone with several adjacent sub-sweeps from a machine overflying said zone.

Apparatus and method for measuring reflecting mirror focal length of concave paraboloid

Abstract: A measuring device consists of parallel optical tube of Newton type, eyelet, diffuse reflection optical source, microcalliper, telescopic length bar and standard measuring tool. The method for measuring focal length of concave parabolic reflector includes using diffuse reflection optical source to provide measuring datum, utilizing microcalliper to ensure to two arc ends of telescopic length bar to contact with toppoints of cancave parabolic reflector and diffuse reflection optical source, using standard measuring tool to calibrate length bar for obtaining focal length in accuracy of 0.02-0.05mm.

Radar-invisibility on axis of rotationally symmetric reflectors

Abstract: It has been observed that the monostatic radar cross section (RCS) of parabolic perfect electric conductor (PEC) reflectors vanishes at certain frequencies for broadside wave incidence. It has also been noticed that hyperbolic reflectors behave similarly, with very low RCS minima. This behavior is explained by using physical optics (PO) and verified via a numerical full-wave analysis. Relations between the physical dimensions of the reflector and the characteristic values of the RCS (notch frequencies, minimum and maximum value), as well as a comparison of different canonical reflectors, are given. The interest in the phenomenon described is at present essentially speculative, since, as pointed out in this letter, there are some significant limitations which restrict its practical utilization.

Optical Transform Limitations in Headlamp Photometric Performance

Abstract: Automotive lamps are essentially the optical transform devices. A light intensity angular distribution from a given light source (filament, HID arc, LED, etc.) is transformed to a desired new light intensity angular distribution namely beam pattern by means of an optical system such as a reflector or lens optics, or a projector module system. There are fundamentally five types of optical transformations occurring in a headlamp optical design: A). Light intensity angular distribution transforms from a light source to a beam pattern that is another fashion of angular distribution via a reflector-optics device. This transform device, sometimes, is referred to as the free-form reflector design; B). Light intensity angular distribution from a light source is transformed to a spatial distribution on a focal plane of an ellipsoidal (or similar) reflector; C). Light intensity spatial distribution on the focal plane of the ellipsoidal reflector is transformed to a beam pattern (angular distribution) using a projection lens. The combination of these transforms, B and C, is referred to a projector module system; D) Light intensity angular distribution is transformed to a quasi-parallel beam (uniform angle) via a parabolic reflector; E) The quasi-parallel beam is transformed to a beam pattern (angular distribution) using a traditional lens array. The combination of the transforms of D and E is referred to the lens optical design. In an optical system, both luminous flux and etendue is conserved. These conservations dominate optical design limits for a headlamp photometric performance. This paper discusses these limitations: luminous intensity and size for a headlamp using studies of the above mentioned optical transformations. Furthermore, the paper will show that these limitations are related to the light source and the uniqueness of LEDs. This is the continuation of the studies published in the last year's SAE paper written by the same authors.

Parabolic Reflector Modelling Techniques with a Laterally Displaced Feed

Abstract: : This document looks at two techniques for modelling the radiation pattern of a parabolic reflector antenna. Both these methods use physical optics to determine the induced currents on the reflector due to the feed. The first method uses MATLAB's numerical integration routine to compute the far-field radiation pattern. The second method involves segmenting the reflector surface and approximating the amplitude and phase of the surface currents by a first degree polynomial. This approximation allows the integration to be performed analytically in closed-form. Three different reflector configurations are investigated including two configurations with a laterally displaced feed. Both these techniques yield accurate results but the latter technique had a significant improvement in computational efficiency.

Gimbaled gregorian antenna

Abstract: In one embodiment, a gimbaled reflector antenna is provided that includes only four reflectors comprising: a first flat plate reflector, a second flat plate reflector, and an ellipsoidal reflector, and a parabolic reflector. By rotating some or all of the reflectors with respect to a fixed feed, a projected beam may be scanned across a hemispherical field of regard.

Processing chamber with wave reflector

Abstract: The processing chamber comprises an energy wave source and a curved spherical surface, wherein the curved spherical surface of the chamber is composed of at least a Fresnel reflector for reflecting the energy wave discharged from the energy wave source and projecting the same onto a platform as the energy wave source is operating in coordination with the curved spherical surface. In addition, the energy wave source can be a microwave source or a light source. It is noted that the curved spherical surface can be a Fresnel reflector, a wave spherical surface with a portion thereof being replaced by a Fresnel reflector, a curved spherical surface with a portion therof being replaced by at least two Fresnel reflectors, and a surface entirely formed of a plurality of Fresnel reflectors. The processing chamber disclosed in the present invention significantly increases energy density, area, and energy uniformity of the projection region so as to diminish required space of equipment and costs of equipment and manufacture.

High efficiency dual bulbs illumination system

Abstract: This invention provides a double light source lighting system including a confocal focusing lens set composed of a first focusing lens and a second focusing lens, the first light source system is set opposite to the first lens, the second adjacent to the first and opposite to the second lens, among which, said first light source system includes a first bubb, a first parabolic reflector and a first reflecting plane mirror, said first bulb is set at the focus point of the reflector and the first mirror is set between said first parabolic reflector and first focusing lens, said second light source system contains the second bulb, second parabolic mirror and second plane mirror, the bulb is at the focus point of second parabolic reflector and the second plane mirror is between the second parabolic mirror and the second focusing lens

A horn-fed reflector optimized with a genetic algorithm

Abstract: Designing reflector antennas to minimize the effects of spillover and feed blockage requires optimization of accurate numerical models. A FEKO [2003] model of a horn-fed parabolic reflector is optimized for maximum directivity using a genetic algorithm (GA).

Light condensing device and method

Abstract: PROBLEM TO BE SOLVED: To inexpensively provide a light condensing device capable of flattening the light condensing profile of an incident laser beam regardless of the wavelength of the incident laser beam. SOLUTION: The light condensing device is equipped with a parabolic mirror 3 where a plurality of dimples 2 are formed continuously in a concave shape, and constituted so that the light condensing distance of the dimple 2 may be shorter than that of the parabolic mirror 3. By such constitution, the laser beams divided by a plurality of dimples 2 are superimposed by the parabolic mirror 3 in a state where the respective light condensing profiles are somewhat deviated. Thus, the light condensing profile is flattened regardless of the wavelength of the incident laser beam. COPYRIGHT: (C)2005,JPO&NCIPI

Holder for light source with open flame e.g. teat-light, candle or oil or gas burner, provided with reflector for concentrating light radiation in upwards direction

Abstract: The holder (1) has a reception seating (2) for the tea-light (3) and a peripheral wall section projecting upwards from the seating which is open at the top, acting as a parabolic reflector (4), for concentrating the light radiation provided by the tea-light in an upwards direction. The reflector is made of metal, glass or plastics, e.g. a colored light-transmitting material.