Showing papers on "Parabolic reflector published in 1999"

Directive photonic-bandgap antennas

Abstract: This paper introduces two new photonic bandgap (PBG) material applications for antennas, in which a photonic parabolic reflector is studied. It is composed of dielectric parabolic layers associated to obtain a PBG material. The frequency gap is used to reflect and focus the electromagnetic waves. This device has been designed using a finite-difference time-domain (FDTD) code. FDTD computations have provided the theoretical reflector's directivity. These results are in good agreement with measurements, and it appears that the PBG reflector presents the same directivity as a metallic parabola. A second application uses a defect PBG material mode associated with a metallic plate to increase the directivity of a patch antenna. We explain the design of such a device and propose experimental results to validate the theoretical analysis.

Multiple frequency reflector antenna with multiple feeds

Abstract: A reflector antenna system with multiple feeds each operating in a separate frequency band. The antenna system includes a main parabolic reflector and an ellipsoidal subreflector configured in a Gregorian arrangement. Mutual blockage between the multiple feeds is reduced by their orientation and arrangement. The system includes a transversely positioned feed and an axial feed located in the focal region of the main reflector. The transverse feed may be integral with the subreflector. The system also includes a third feed placed at the virtual focal point of the subreflector.

Characterization of sub-10-fs pulse focusing with high-numerical-aperture microscope objectives.

Abstract: Dispersion precompensation with a prism sequence and a third-order dispersion mirror resulted in negligible broadening of sub-10-fs pulses at subwavelength spot sizes when the pulses were focused with microscope objectives and moderate apertures. At larger apertures, lens chromaticity and spherical aberration led to an effective pulse broadening of up to 1.3×, depending on the aperture size and the detector position. The data suggest that intensities exceeding 1014 W/cm2 can be produced directly from femtosecond pulse oscillators.

Lay-in/recessed lighting fixture having direct/indirect reflectors

Abstract: A lighting fixture for reducing glare and darkspots on ceilings and walls. The lighting fixture includes a louver housing for supporting a plurality of fluorescent or high intensity discharge lamps. The lighting fixture further includes a first set of elongated, parallel, and spaced-apart reflectors; and a second set of elongated, parallel, and spaced-apart reflectors intersecting the first set of reflectors at a 90° degree angle for forming an open reflector grid therein. The open reflector grid includes four outer side walls. The open reflector grid is attached to the louver housing. The open parabolic reflector grid extends at least two inches (2″) below the ceiling level. The lighting fixture also includes a plurality of indirect reflectors connected to the four outer side walls of the open reflector grid for reducing glare and darkspots on ceiling and walls caused by the plurality of fluorescent lamps in the louver housing. Each one of the outer side walls is connected to one of the indirect reflectors thereto.

Laterally graded multilayer optics for x-ray analysis

Abstract: Periodic multilayers are well known as Bragg reflectors for X- rays. A high reflectivity and a wide reflection width are their outstanding features. However, if multilayers shall be used as reflective coating for X-ray optics, especially for wide acceptance angles, uniform layer thicknesses cause chromatic aberrations. These aberrations can be overcome by laterally graded multilayer optics. Their Bragg angle is matched laterally to the incidence angle so that for all points on the reflector, Bragg reflection is obtained for the same wavelength. Three major types of laterally graded multilayer mirrors ('Gobel Mirrors') are applied in X-ray diffractometry: (1) parabolic, (2) elliptic and (3) planar. In this paper, we give design criteria and formulae for these mirrors. Furthermore, we discuss the requirements on the dimensions and the fabrication process. Two different processes suitable for the fabrication, sputter coating and pulsed laser deposition (PLD), are described. The X-ray optical parameters and their characterization are presented for various mirrors designed for Cu K(alpha) , Mo K(alpha) and Cr K(alpha) radiation. From Ni/C and Ni/B4C multilayers, high-photon-flux monochromators with a Cu K(beta) /K(alpha) intensity ratio of about 1:1000 have been realized. The divergence of the 'parallel' beam reflected from parabolic mirrors is about 0.02 degrees, which is one order of magnitude lower than the divergence of polycapillary optics, monocapillary optics and waveguides. Comparing the photon flux density in a high resolution diffraction setup with and without mirror optics a gain factor of 16 was achieved for parabolic Ni/B4C multilayer mirrors.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Intermediate and far fields of a reflector antenna energized by a hydrogen spark-gap switched pulser

Abstract: Previously, the design, fabrication and testing of a pulser with a parabolic reflector antenna, known as the prototype impulse-radiating antenna (IRA) has been presented. The paraboloidal reflector was fed by a TEM structure that in-turn was energized by a /spl plusmn/60 kV, /spl sim/100 atm. hydrogen switch operating in a burst mode at up to 200 Hz. The TEM structure also incorporated an electromagnetic lens to ensure a near-ideal spherical TEM wavelaunch. Some of the measured characteristics of this system were: (a) a peak electric field on boresight of 4.2 kV/m at a range r=305 m; (b) an uncorrected pulse rise-time (10-90%) of 99 ps; and (c) a boresight electric fields FWHM of 130 ps. The radiating system has now been more fully characterized with additional measurements and computations of near field, intermediate and far fields on the boresight. While the far fields from such a radiating system have been known for some time, the intermediate field analysis was only published recently. This method substitutes the radiated field from a paraboloidal reflector by the radiation field from the TEM structure reflected in the parabolic mirror. Although this work is limited to fields on the boresight at any distance from the antenna, the authors have been able to extend the analysis to the frequency domain. It has also been verified that the intermediate fields asymptotically tend to the far-field expressions, as the range r is increased. Good agreement between calculated and measured fields has been obtained for the prototype IRA in the near (r=5 m) and in the far field (r=305 m).

Reflective grating interferometer: a folded reversal wave-front interferometer

Abstract: We present a new, folded reversal interferometer. It is based on the reflective grating interferometer and can be applied for optical isolation and testing of coma aberration. The interferometer has several advantages in respect to other existing optical reversal configurations. A carrier can be easily added for phase retrieval in interferometric fringe patterns for mapping coma aberration. Furthermore, in an asymmetric optical configuration a lateral shear can also be added, transforming it in a reversal shearing interferometer. The principle of operation of the interferometer is described, and the application for measuring the coma aberration of a parabolic mirror used off axis is demonstrated.

Unit for measuring optical properties

Abstract: A unit for measuring optical properties. The unit includes the first through sixth reflecting surfaces, a reflecting surface rotating device and an object moving device. In order to accurately measure transmittance, reflectance and phase change in transmittance or reflection of optical elements, especially transmittance of a thick object, the first through the fourth reflecting surfaces M1-M4 are arranged so that an optical path formed by the reflecting surfaces M1-M4 has a shape like an "N" letter and so that light of incidence L1 has the same optical axis as exit light L2. An optical center O is a point that a line segment that connects a point of incidence A with an exit point D intersects an optical path that connects the reflecting surface M2 with the reflecting surface M3. The reflecting surface M2 is an ellipsoid of revolution having foci of the optical center O and the point of incidence A. The reflecting surface M3 is an ellipsoid of revolution having foci of the optical center and the exit point D. A reflecting surface rotating device rotates M4 at the exit point D in conjunction with the reflecting surface M1 that is rotated at the point of incidence A. The reflecting surface M5 is a parabolic mirror that makes light reflected from the reflecting surface M1 parallel. M6 is a parabolic mirror that converges light reflected from the reflecting surface M5 onto the reflecting mirror M4.

Interferometric alignment and figure testing of large (0.5 m) off-axis parabolic mirrors in a challenging cleanroom environment

Abstract: The Far Ultraviolet Spectroscopic Explorer (FUSE), successfully launched in June 1999, is an astrophysics satellite designed to provide high resolution spectra ((lambda) /(Delta) (lambda) equals 24,000 - 30,000) with large effective area (20 - 70 cm2) over the interval 90.5 - 118.7 nm. The FUSE instrument consists of four co-aligned, off-axis parabolic primary mirrors which focus light into separate spectrograph channels. The mirrors are rectangular (407 X 372 mm) and fabricated from lightweighted Zerodur blanks. We describe a straightforward method for aligning these off-axis parabolas in an autocollimation setup via qualitative and quantitative analysis of static interferograms. Initial alignment is achieved rapidly by visual inspection of the interferogram as adjustments are made in vertical and horizontal alignment. Fine alignment to the limit of the optical system then proceeds with small alignment steps and fringe analysis software to find the position which minimizes wavefront error. This method was used for figure testing the FUSE primary mirrors throughout build-up and qualification of the flight mirror assemblies. The far- ultraviolet reflectivity of the FUSE mirrors is very sensitive to molecular contamination. All mirror testing thus took place in a strictly controlled class 1000 clean room environment. In addition to the challenging vibration and turbulence problems this environment presented, two of the fight mirrors were coated with lithium fluoride over aluminum. This necessitated purging the setup with dry nitrogen, as the lithium fluoride coating degrades with exposure to water vapor. We discuss the difficulties these environmental constraints presented and summarize the mitigating action.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A dielectric photonic parabolic reflector

Abstract: This paper presents a study of a photonic parabolic reflector. The structure is exclusively composed of dielectric materials which are associated to build a photonic bandgap (PBG) structure with a forbidden frequency band located at the working frequency of the reflector. The dish was designed with FDTD computations using a surface-impedance formalism. The directivity of an experimental device has been measured and compared to the directivity calculated with the FDTD simulations. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 411–414, 1999.

Optical design of the Hobby-Eberly Telescope four-mirror spherical aberration corrector

Abstract: The Hobby-Eberly Telescope uses a 11-meter diameter F/1.45 segmented spherical primary mirror. A spherical mirror of this size generates large amounts of spherical aberration. To be used successfully in a tilted optical Arecibo type telescope, the spherical aberration needs to be corrected. This means that tracking of astronomical targets is achieved through moving a tracker optical package which imposes somewhat severe packaging constraints. Given these packaging constraints, novel methods must be employed to correct the aberrations with the Spherical Aberration COrrector contained in the moving tracker optical package. The paper reviews the pertinent requirements, constraints and the resultant design of the Hobby-Eberly Telescope Four Mirror Spherical Aberration Corrector.

Integrated headlamp system for motor vehicles

Abstract: A lamp assembly (12, 12A) has a lamp housing (14) and a lens (16) cooperatively forming an enclosure within which an electric light bulb (78) is disposed to place a focal point (82) of the bulb at the focus of a parabolic reflector surface (56) of a reflector (52) that is also disposed within the enclosure. The reflector collects light from the bulb and reflects it as a beam through the lens. A socket (76) that holds the bulb mounts in a rear wall (24) of the enclosure, and the reflector has a through-aperture (74) through which the bulb passes. A positioning mechanism (84) selectively positions the reflector about an axis (61) perpendicularly intersecting the bulb axis (26) to aim the light beam. As the reflector is being positioned, the bulb remains stationary, and the focus of the parabola remains at the focal point of the bulb.

Dual gridded reflector antenna

Abstract: An improved dual gridded reflector antenna configuration which allows cross-polarization radiation to be scanned in any given direction. The dual-gridded reflector assembly includes a front parabolic reflector illuminated by a first source, and a second parabolic reflector illuminated by a second source. The second reflector is positioned adjacent to and behind the front reflector such that the center points of the reflectors align to define a center axis. Additionally, the first and second sources are positioned at different offsets with respect to the reflectors and have a respective rotated offset angle with respect to the center axis such that the sources define an antenna feed separation. By modifying the offsets and the rotated offset angles, the feed separation can be designed to have an inclination with respect to the north-south or east-west feed separation direction.

Illumination device and projection type display device using it

Abstract: PROBLEM TO BE SOLVED: To illuminate a surface to be irradiated with extremely parallel and uniform luminous flux when a light source such as a xenon lamp whose point light source property is excellent is used. SOLUTION: A reflection mirror 170 is shaped so that the axis 173 of a parabola is inclined with respect to an optical axis and rotated around the optical axis (subsequently mentioned as the rotary inclined parabolic mirror or the inclined parabolic mirror). When a light beam emitted from the focal point 172 of the inclined parabolic mirror 170 is reflected on the upper side of the mirror 170 than the optical axis 12, it becomes the light beam being in parallel with the axis 173 of the parabola. Then, the luminous flux reflected on the lower side of the mirror 170 than the optical axis 12 similarly becomes the parallel luminous flux. The respective parallel luminous flux existing within a surface including the optical axis 12 are guided in a direction such that they are condensed to the optical axis 12. Besides, all of the luminous flux transmitted through a conical lens 171 being the concave lens including a conical surface becomes the luminous flux being in parallel with the optical axis 12 so as to be made incident on the surface 21 to be irradiated. COPYRIGHT: (C)2000,JPO

Reflective antenna system with increased focal length

Abstract: A multiple beam antenna system including an offset parabolic reflector has an increased focal length (FL) and/or an increased FL/D (where D is a diameter of the reflector) in order to improve off-axis performance of the system. In certain embodiments, the system can simultaneously receive different signals from different satellites that are orbitally spaced.

High efficiency asymmetrical optical assembly

Abstract: A parabolic reflector with an asymmetrical light distribution is disclosed. The inside surface of the reflector is divided into four quadrants, and two of the four opposing quadrants are coated with a reflective material. The two remaining quadrants are uncoated or specular. With the uncoated quadrants aligned along a longitudinal center line of a narrow area to be lit, the reflector provides an asymmetrical or elliptical light distribution for more efficient lighting of narrow hallways and passageways. The reflector is particularly useful in a warehouse environment.

Optical characteristic measuring unit

Abstract: PROBLEM TO BE SOLVED: To accurately measure the transmittance of a thick object to be measured. SOLUTION: First to fourth reflection surfaces M1 to M4 are arranged so that a light path passing through the reflection surfaces forms an N shape, and at the same time incidence light L1 and emission light L2 become coaxial. The intersection of a segment for connecting an incidence point A to an emission point D and the race of a ray advancing from the M2 to the M3 is set to a center O of an optical system. The M2 is a rotary elliptical surface where the center O of the optical system and the incidence point A are used as a focus. The M3 is a rotary elliptical surface where the center O of the optical. system and the emission point D are used as the focus. In each of the arrangement positions A and D of M1 and M4, each axis that orthogonally crosses a plane including the N-shaped light path is set to the center, and a reflection surface rotation device 31 that rotates while linking the M1 and M4 is provided. Also, when a thick object to be measured is to be measured, light is reflected in the order of the M1, M5, M6, and the M4. The M5 is a parabolic mirror that changes light from the M1 to parallel light for sending to the M5. The M6 is the parabolic mirror that condenses light from the M5 to the M4.

Tera hertz spectrophotometer

Abstract: PROBLEM TO BE SOLVED: To provide a spectrophotometer which can measure spectroscopy in THr(tera Hertz) region with good S/N by combining a variable wavelength tera Hertz wave light source having high spectral strength with a Type Fourier interferometer. SOLUTION: The tera Hertz spectrometer 15 comprises a TPG(tera Hertz parametric generation) light source for radiating a THz wave generated by pumping a nonlinear crystal LiNbO3 3 through an Nd:YAG laser 1 into the space using an Si prism and collimating it through an off-axis parabolic mirror 9, an MP type interferometer for splitting the THz wave through a beam splitter 4 into two light beams and causing interference by superposing them again by means of a fixed mirror M16 and a movable mirror M27, a gas cell 10 filled with a sample for spectroscopy, and a 4K-Si bolometer 11 for detecting THz wave.

Optical head for laser beam welding

Abstract: PROBLEM TO BE SOLVED: To provide an optical head for laser beam welding which is manufactured at a low cost and improved in the welding quality. SOLUTION: Relating to an optical head 1 for laser beam welding that the laser beam LA is guided to a parabolic mirror 5 using plane mirrors 3, 4, and the laser beam LB converged by the parabolic mirror 5 is irradiated on a weld part 2 to implement the welding, the parabolic mirror 5 is a 30 deg. off-axis parabolic mirror in which the optical axis of the emitting beam is deviated by about 30 deg. from the optical axis of the incident beam, and the converged laser beam LB is scanned by oscillating at least one of the parabolic mirror 5 and the plane mirror 4 disposed immediately therebefore around a specified axis of rotation.

Theoretical analysis of the Pickett Potter horn-reflector antenna for submillimetre-wave applications

Abstract: A Pickett-Potter (1984, 1963) horn-reflector feed for short wavelength (>700 GHz) SIS mixer has been theoretically designed and a 15 GHz scale model of a Pickett-Potter horn has been developed and tested. The antenna comprises of offset parabolic reflector fed by a Pickett-Potter horn. The horn is easy to machine, and yet still preserves the desirable electrical properties of a corrugated horn, namely low cross polarisation, low sidelobe level and nearly circular beam shape, albeit over a reduced bandwidth. The calculations are based on the modal matching method and conformal mapping.

Light conduction lighting device

Abstract: The utility model relates to a light conducting lighting device. In the utility model, a parabolic reflector is connected with a bracket and can do pitching actions, a bracket food is fixed on a rotary disc which can be rotated on a supporting disc rack, the focal point of the parabolic reflector is provided with a focusing mirror whose the other surface tightly supports the end surface of an optical fiber bundle, the other end surface of the optical fiber bundle in a room tightly supports a lens, the position of the light emitting surface of the lens is provided with a shutter, a pitching motor and a rotary motor are controlled by a time relay and intermittent breaking. The utility model has the advantages of simple structure, low cost and low energy consumption, and the utility model can fully utilize solar energy for improving the environment of living rooms, protect physical and mental health for human being, save large amounts of energy and protect natural environment.

Laser with phase conjugation for high intensity interactions

Abstract: We present the results of the experimental testing of the laser facility LAMBDA, created and built at the Institute of Experimental Physics of the Russian Federal Nuclear Center for generation of quasi-steady-state laser fields in microvolumes.The facility includes: a single mode generator of reference radiation (RR) producing about 10 mJ energy in a pulse of controlled length from 3 to 30 ns; a target chamber with an input objective focusing the RR beam to a micron-size spot, and a 280-mm-diameter parabolic mirror with the focal length also of 270 mm; a two-stage iodine amplifier with the small signal gain coefficient 3·105 per one pass, to the input of which radiation from the target chamber formed by the (microobjective + parabolic mirror) system is applied; a phase conjugating device with the system for the selection of the phase-conjugated component, which allows us to realize the pulse compression in the amplifier stages, and to provide the compensation of the optical aberrations after the second pass amplification and focusing of high-power radiation into the microvolume; a complex for diagnostics of plasma and laser radiation parameters.

Multifunctional solar range

Abstract: The utility model provides a solar range. The utility model is composed of a solar condensing reflector with a parabolic mirror face, and a heater which is arranged at the focusing point of the paraboloid of the condensing reflector. The utility model is characterized in that an insulating cover is arranged on the condensing reflector, the heat radiation of the heater can be effectively prevented, and solar thermal utilization factor is enhanced. Because a turret and the bracket of the heater are connected into integrationand a slope angle regulator is arranged, when the utility model is used, the utility model can be rotated following the turret so that optimal heat absorbing effect can be maintained, and the thermal utilization factor is increased. The utility model also has the characteristics of simple structure, flexible and convenient use and regulation, fast heating, high thermal efficiency, etc., and the heat radiation is not easy.

Genetic Algorithm Implementation for Array-Feed Parabolic Reflector

Abstract: A genetic algorithm (GA) is used to obtain pattern nulling and main beam scanning of the array feed parabolic reflector. Unlike conventional GA using a random initial population, in this study, one of the initial individuals is designated as conjugate field matching (CFM) weight vector. The implemented GA algorithm is tested for both phase-amplitude array and phase-only array feed for parabolic reflectors. Various results are presented to show the performance of the algorithm.

System for determining unsafe intensities of infrared radiation

Abstract: The system has a collimator (1), moving outside a hemispherical chamber (6) parallel to the symmetry axis (7). A sensor chip (9) is fitted on the axis near the center of curvature (0) with a convex lens (10) on its top face. A glass tube (14) with lightly etched inner walls is fitted over the sensor and its other opening is sealed by a parabolic mirror (15). The tube extends over most of the length of the axis in the chamber.

Light guide lighting system

Abstract: PROBLEM TO BE SOLVED: To supply much quantity of the incident light even to a narrow- diameter light guide by arranging a luminescent spot of a light source so as to obtain the maximum converged quantity of light in relation to the diameter of the light guide. SOLUTION: A light source device set so as to obtain the maximum quantity of light in the case where diameter of a light guide 4 is set at 3.4 mm has a hot spot at 0.33 mm from a focal point of a parabolic reflector 2. In order to obtain the maximum quantity of light in relation to the light guide 4 having a diameter at 0.8-1.5 mm, the hot spot is desirably set at +0.18 mm, 0.23 mm respectively from the focal point. Namely, the light guide 4 and the parabolic reflector 2 are arranged so that as the diameter of the light guide is formed smaller, the hot spot and the focal point of the parabolic reflector 2 comes closer to each other. Position of the hot spot is set at +0.18 mm from the focal point so as to obtain the maximum quantity of the incident light with the light guide 4 having a narrow diameter at 0.8 mm.

Optical system for three-dimensional shape measurement

Abstract: PROBLEM TO BE SOLVED: To realize an optical system which can simply measure a three- dimensional form at a high speed SOLUTION: This optical system is provided with a collimator lens 23 converting a laser beam from a laser light source 21 to a parallel light, a scanning optical system 31 scanning vertically an object 50 with the laser parallel light, a mirror 29 which makes a specified angle, nearly vertical to the object, is arranged at a specified distance from the scanning beam, and receives an obliquely reflected light from the object, an imagery lens 33 which forms again the image of reflected light from the object by a mirror, via the scanning optical system, and a photo detector 35 detecting an imagery beam spot by the imagery lens The scanning optical system 31 is provided with a deflection mirror 25 deflecting the laser parallel light to a specified direction, and a parabolic mirror 27 which reflects the deflected light and makes a beam enter the object from the vertical direction

Antenna system provided with plural reflectors

Abstract: PROBLEM TO BE SOLVED: To irradiate a grounding surface with two beams which do not interfere mutually by using two sets of feeds and reflectors arranged in the front and behind. SOLUTION: This antenna system 10 consists of two parabolic reflectors 12 and 14 and two feeds 16 and 18 which are supported and positioned by a supporting body 20. The feeds 16 and 18 are connected to transmitting and receiving equipment 22. Beams 28 and 30 of the reflectors 12 and 14 form beam footmarks 32 and 34 on the ground 26. Although radiation of the feed 18 is reflected by the reflector 14, the reflector 12 permeates the greater part of the radiation. An interference pattern due to a part of the reflection is so designed as to come outside the footmarks 32 and 34.

Solar energy receiving and conveying device

Abstract: FIELD: solar engineering. SUBSTANCE: device has parabolic mirror to receive input solar energy flux Φ1, which is mounted on sun orienting unit and has hole 2 at base for securing flexible part 3 of optical conductor; second mirror 7 secured in focus aligning unit that functions to convert flux reflected from first mirror 1 to cylindrical flux Φ2 of higher density and same direction as input flux Φ1. Movable part 3 of optical conductor is assembled as set of conical mirrors 5 mounted in rubberized perforated tube 6; fixed part 4 is, essentially, tube having internal mirror surface. EFFECT: facilitated manufacture. 2 dwg

Innovative telescope system for SLR

Abstract: For the SLR system to be described, it has been decided to use the bistatic approach. The two separate telescopes are spaced by about 2 meters and are using identical azimuthal mounts. A 130 mm diam. lens is used for transmitting the laser beam and a 450 mm parabolic mirror for the receiver. Each telescope is enclosed by an independently driven housing isolating it from wind forces as well as environmental contamination thus enabling even a use without any dome. The telescopes are driven by direct on-axis motors which are controlled by built-in digital servo systems. Moving cables are avoided by sliding contacts allowing a continuous rotation in both axes without limitation. The focal units of each telescope are mounted in separate boxes below the platform of the observation building. The transmitter box contains the variable beam expander and the receiver box contains the filters (spatial and spectral) as well as the photoelectric receivers.