Showing papers on "Reflector (antenna) published in 2010"

Planar high-numerical-aperture low-loss focusing reflectors and lenses using subwavelength high contrast gratings.

Abstract: We propose planar, high numerical aperture (NA), low loss, focusing reflectors and lenses using subwavelength high contrast gratings (HCGs). By designing the reflectance and the phase of non-periodic HCGs, both focusing reflectors and lenses can be constructed. Numerical aperture values as high as 0.81 and 0.96 are achieved for a reflector and lens with very low losses of 0.3 and 0.2 dB, respectively. The design algorithm is also shown to be readily extended to a 2D lens. Furthermore, HCG optics can simultaneously focus the reflected and transmitted waves, with important technological implications. HCG focusing optics are defined by one-step photolithography and thus can be readily integrated with many devices including VCSELs, saturable absorbers, telescopes, CCDs and solar cells.

High contrast gratings for integrated optoelectronics

Abstract: We discuss a new concept of dielectric subwavelength grating leveraging high index contrast to manipulate light to achieve ultra broad band reflector, high-Q resonator, planar high numerical aperture lens and reflector, and hollow-core integrated optics.

Multi-band antenna system for satellite communications

Abstract: The present invention provides an improved single antenna system that allows reception of RF energy at multiple frequencies. In one embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a dual mode feed tube and a switchable LNB that supports both Ka band and Ku band reception. In another embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a feed horn and a LNB that is capable of providing movement such that the feed horn with the LNB is at a focal point with the primary reflector for both Ka and Ku band reception. In another embodiment, the antennae is implemented as a multi-beam, multi-feed antenna having a primary reflected fitted with a feed horn assembly and a switchable LNB that supports both Ka band and Ku band reception.

Switchable metamaterial reflector/absorber for different polarized electromagnetic waves

Abstract: We demonstrate a controllable electromagnetic wave reflector/absorber for different polarizations with metamaterial involving electromagnetic resonant structures coupled with diodes. Through biasing at different voltages to turn ON and OFF the diodes, we are able to switch the structure between nearly total reflection and total absorption of a particularly polarized incident wave. By arranging orthogonally orientated resonant cells, the metamaterial can react to different polarized waves by selectively biasing the corresponding diodes. Both numerical simulations and microwave measurements have verified the performance.

Reflector antenna radome attachment band clamp

Abstract: A band clamp for coupling a radome to a distal end of a reflector dish for improving the front to back ratio of a reflector antenna, the band clamp provided with an inward projecting proximal lip and an inward projecting distal lip. The distal lip dimensioned with an inner diameter equal to or less than a reflector aperture of the reflector dish. The proximal lip provided with a turnback region dimensioned to engage an outer surface of a signal area of the reflector dish in an interference fit. A width of the band clamp may be dimensioned, for example, between 0.8 and 1.5 wavelengths of an operating frequency.

Modular type cellular antenna assembly

Abstract: A individually formed radiating unit, an antenna array, and an antenna assembly are provided. The individually formed radiating unit includes a reflector, at least one radiating element integrated into a first side of the reflector, and a housing disposed on a second side of the reflector. The housing forms a chamber for housing a feed network.

Energy assisted magnetic recording head having a reflector for improving efficiency of the light beam

Abstract: A method and system for providing an EAMR transducer is described. The EAMR transducer is coupled with a laser for providing energy and has an ABS that resides near a media during use. The EAMR transducer includes a write pole, coil(s) that energize the pole, a near field transducer (NFT) proximate to the ABS, a waveguide, and a reflector. The write pole has a back gap region and writes to a region of the media. The NFT focuses the energy onto the media. The waveguide directs the energy from the laser toward the NFT at an incident angle with respect to the ABS. A first portion of the energy reflects off of the ABS at a reflected angle. The reflector receives the first portion of the energy from the ABS and reflects a second portion of the energy toward the ABS. The NFT resides between the waveguide and the reflector.

Infrared vision with liquid crystal display device

Abstract: Various embodiments related to infrared vision for a liquid crystal display (LCD) device are disclosed herein. For example, one disclosed embodiment provides a display system, comprising an LCD device and a display backlight configured to illuminate the LCD device by directing visible light toward an interior surface of the LCD device. The display system further comprises a wavelength-selective reflector disposed between the display backlight and the LCD device and having a smooth surface facing the interior surface of the LCD device, where the wavelength-selective reflector has a wavelength- selective coating configured to cause incident visible light from the display backlight to be transmitted through the wavelength-selective reflector to the LCD device, and cause incident infrared light reflected from an object on or near an exterior surface of the LCD device to be reflected off of the wavelength-selective reflector and directed to an infrared vision subsystem.

Confocal Ellipsoidal Reflector System for a Mechanically Scanned Active Terahertz Imager

Abstract: We present the design of a reflector system that can rapidly scan and refocus a terahertz beam for high-resolution standoff imaging applications. The proposed optical system utilizes a confocal Gregorian geometry with a small mechanical rotating mirror and an axial displacement of the feed. For operation at submillimeter wavelengths and standoff ranges of many meters, the imaging targets are electrically very close to the antenna aperture. Therefore the main reflector surface must be an ellipse, instead of a parabola, in order to achieve the best imaging performance. Here we demonstrate how a simple design equivalence can be used to generalize the design of a Gregorian reflector system based on a paraboloidal main reflector to one with an ellipsoidal main reflector. The system parameters are determined by minimizing the optical path length error, and the results are validated with numerical simulations from the commercial antenna software package GRASP. The system is able to scan the beam over 0.5 m in cross-range at a 25 m standoff range with less than 1% increase of the half-power beam-width.

LED downlight retaining ring

Abstract: An LED downlight comprises a primary reflector having an upper end and an open lower end, an LED printed circuit board assembly disposed in the upper end of the reflector, an optical assembly positioned beneath the LED printed circuit board assembly, a secondary reflective ring positioned beneath the LED printed circuit board assembly and within the primary reflector housing, the secondary reflector ring supporting the optical assembly and improving light distribution.

Head-up display device

Abstract: A head-up display device includes a display unit for displaying information, a reflector rotatably supported by frame members fixed to a vehicle, and an adjuster for adjusting a rotational position of the reflector by a gearing system. The information displayed on the display unit is reflected by the reflector to a projection area on a vehicle windshield. The adjuster so adjusts the rotational position to allow a vehicle driver to see both a front view through the windshield and a superimposed reflected image of the information. The head-up display device further includes a regulator to allow the reflector to rotate in a rotational direction within a range where the reflector is adjustable by the adjuster, and to prevent the reflector from shifting in a direction other than the rotational direction.

Miniaturized photoacoustic imaging apparatus including a rotatable reflector

Abstract: A reflection-mode photoacoustic endoscope includes a light source configured to emit a light pulse, a signal detection or transmission unit configured to detect or emit an ultrasonic pulse, and a rotatable reflector. The rotatable reflector is configured to reflect at least one of the light pulse and the ultrasonic pulse into a target area of an object, and reflect a response signal to the signal detection unit. The response signal is one of a photoacoustic wave generated by the object responsive to the light pulse and an ultrasonic pulse echo generated by the object responsive to the ultrasonic pulse.

Apparatus for biomedical imaging

Abstract: A system that incorporates teachings of the present disclosure may include, for example, a method involving capturing spectral interference from an optical coherence tomography imaging probe comprising a micro-electro-mechanical system (MEMS) scanning mirror, and a partial reflector for supplying images to an image sensor. Additional embodiments are disclosed.

Forward-imaging optical coherence tomography (OCT) systems and probes

Abstract: Provided are forward-imaging optical coherence tomography (OCT) systems and probes. In one embodiment, a scanning reflector surface is configured to be rotated about two axes in a single operating plane to direct light transmitted along the sample path to a sample to be imaged.

Long-pitch cholesteric liquid crystal cell for switchable achromatic reflection

Abstract: We propose a switchable achromatic reflector using a long-pitch cholesteric liquid crystal (CLC) whose Bragg reflection wavelength is chosen to be infrared by controlling the pitch of the CLC so that the planar texture is transparent over the entire visible wavelength. By using the light scattering of the focal conic texture, achromatic reflection can be achieved. Both textures are stable at zero electric field and the operating voltage of the proposed CLC device is much lower than that of conventional CLC devices. The proposed switchable reflector, which can be operated at a low voltage with low power, can be applied to reflective displays and to light shutters. By coupling with a reflective polarizer the efficiency of light scattering at the focal conic texture can be enhanced.

Automotive rearview mirror assembly

Abstract: An automotive rearview mirror assembly includes an electrochromic reflective element having a transparent electrical conductor disposed at a second surface of a first substrate and a mirror reflector disposed at a third surface of a second substrate. The mirror assembly includes electrochromic mirror dimming circuitry for controlling dimming of the electrochromic medium. The mirror assembly may include one or more features and at least one of the features may share a component with the electrochromic mirror dimming circuitry and/or share circuitry with the electrochromic mirror dimming circuitry. The mirror assembly may include a video camera and/or an on-demand display viewable through the mirror reflector by the driver of the equipped vehicle when displaying information and substantially non-viewable by the driver of the equipped vehicle when not displaying information.

Noncontact ultrasonic transportation of small objects in a circular trajectory in air by flexural vibrations of a circular disc

Abstract: We have developed a noncontact ultrasonic technique for transporting small objects with a linear trajectory over long distances using a bending vibrating plate and a reflector. In this paper, noncontact transportation of small particles around a circular trajectory was investigated. A circular aluminum plate with a piezoelectric ring was employed as a vibrating plate. On the basis of finite element analysis (FEA) calculations, the electrodes of the piezoelectric ring were divided into 24 pieces to generate a flexural vibration mode with one nodal circle and four nodal lines at the resonance frequency of 47.8 kHz. A circular plate having the same dimensions as the vibrating plate was installed parallel to the vibrator. It was used as a reflector to generate an acoustic standing wave in the air between the two plates. The acoustic field between the vibrating plate and reflector was calculated by FEA and the distribution of the acoustic radiation force acting on a small rigid particle was calculated to predict the position of the trapped particle. Using a prototype of the vibrating plate, polystyrene particles with diameters of several millimeters could be trapped at regular intervals along the horizontal nodal line of the standing wave. The sound pressure distribution between the vibrating plate and reflector was measured by a fiber optic probe and the experimental and calculated results showed good agreement. By switching the driving conditions of the divided electrodes in the circumferential direction, the nodal lines of the vibrating plate could be rotated and the trapped particle could be manipulated with a circular trajectory in air.

Folded Reflectarrays With Shaped Beam Pattern for Foreign Object Debris Detection on Runways

Abstract: Design of a folded reflectarray antenna (FRA) by phase only control to provide a cosecan squared beam pattern in elevation and a pencil-beam pattern in azimuth to detect objects on the ground, e.g., on runways. A very compact folded reflectarray antenna was fabricated and its radiation pattern over frequency was simulated. During the design process a conical horn was developed, which illuminates the array, with symmetrical radiation pattern for all planes and for a frequency range of 76 to 81 GHz. As the FRA consists of a single layer substrate this kind of antenna could be a candidate for low-cost production in FOD detection on airports in the future.

Frequency Selective Surfaces for Extended Bandwidth Backing Reflector Functions

Abstract: This paper deals with the use of frequency selective surfaces (FSS) to increase the efficiency X bandwidth product in wideband antenna arrays, whose efficiency is limited by the front-to-back ratio. If the backing reflector for the antenna is realized through a single metal plane solution, its location will be suitable only on a relatively limited frequency range especially if wide angle scanning is required. In order to extend the frequency range of usability, an FSS can be sandwiched between the antenna and the ground plane, providing an additional reflecting plane for an higher frequency band. The possibility to integrate in the antenna different functionalities, otherwise performed by several antennas, is also discussed in the paper. The proposed backing structure composed by the FSS and the ground plane has been designed to be used in conjunction with a wideband antenna consisting of an array of connected dipoles. A hardware demonstrator of the backing structure has also been manufactured and tested.

Surface-emission laser diode and fabrication process thereof

Abstract: A surface-emission laser diode includes a GaAs substrate, a cavity region, and upper and lower reflectors provided at a top part and a bottom part of the cavity region, the upper reflector and/or the lower reflector including a semiconductor Bragg reflector, at least a part of the semiconductor distributed Bragg reflector includes a semiconductor layer containing Al, Ga and As as major components, there being provided, between the active layer and the semiconductor layer that contains Al, Ga and As as major components, a semiconductor layer containing Al, In and P as major components adjacent to the semiconductor layer that contains Al, Ga and As as major components, with an interface formed coincident to a location of a node of electric strength distribution.

On the reflector shape design

Abstract: In this paper we study the problem of recovering the reflecting surface in a reflector system which consists of a point light source, a reflecting surface, and an object to be illuminated. This problem involves a fully nonlinear partial differential equation of Monge

A Reflector Antenna for Focusing Subnanosecond Pulses in the Near Field

Abstract: A prolate-spheroidal reflector antenna focusing subnanosecond pulsed electromagnetic radiation in the near field is studied. This antenna reflector is fed by a pair of balanced, conical-plate transmission lines and the radiated pulse consists of a prepulse, an impulse, and a postpulse. Whereas the prepulse amplitude decreases inversely with distance, the impulse is maximum near the geometric focus, and its power density distribution has a full-width at half-maximum (FWHM) width of 32 cm in the axial direction and 10 cm in the lateral direction.

Monolithic Geared Optical Reflector

Abstract: A novel monolithic geared optical reflector apparatus which is configured from a gear blank machined to have an integral shaft and integral reflective surface with desired optical properties is introduced herein. Such a rotating mirror device is beneficially capable of being configured into any optical instrument, such as, but not limited to a spectrophotometer, wherein the reflector is adapted to accurately point to a plurality of locations within or out of the system via gear to gear rotation.

Phased Array Feed Calibration, Beamforming and Imaging

Abstract: Phased array feeds (PAFs) for reflector antennas offer the potential for increased reflector field of view and faster survey speeds. To address some of the development challenges that remain for scientifically useful PAFs, including calibration and beamforming algorithms, sensitivity optimization, and demonstration of wide field of view imaging, we report experimental results from a 19 element room temperature L-band PAF mounted on the Green Bank 20 Meter Telescope. Formed beams achieved an aperture efficiency of 69% and a system noise temperature of 66 K. Radio camera images of several sky regions are presented. We investigate the noise performance and sensitivity of the system as a function of elevation angle with statistically optimal beamforming and demonstrate cancelation of radio frequency interference sources with adaptive spatial filtering.

Standoff range sense through obstruction radar system

Abstract: A standoff range, sense-through-obstruction radar system is capable of detecting micro-Doppler, or life form signatures, and movements through obstructions at stand-off ranges and displaying the target information over a live video feed of the area under surveillance. The sense-through-obstruction radar system comprises an antenna assembly that includes a horn antenna and a reflector configured to reflect radio frequency (RF) energy to/from the horn antenna. An antenna pointing assembly supports the antenna assembly. The antenna pointing assembly is configured to move the antenna assembly to point the antenna assembly toward an obstruction. A sensor assembly is mounted to the antenna assembly so that the sensor assembly is aligned with the RF beam formed from the RF energy reflected from the reflector to the horn antenna. The sensor assembly is configured to detect the location of the obstruction and to provide information to assist pointing of the antenna assembly toward the obstruction.

Modular light reflectors and assemblies for luminaire

Abstract: A reflector assembly for a lighting apparatus, the reflector assembly comprising two or more reflector modules configured for associating with one or more light sources, each reflector module comprising one or more reflectors for being located adjacent to a light source when the reflector module is associated with the one or more light sources, the one or more reflectors configured to reflect light from the adjacent light source. The reflector modules may further comprising a cover plate defining a plurality of light source apertures for allowing a light source to protrude through the cover plate, at least a first of the one or more light source apertures disposed adjacent to an overhead reflector and at least a second of the one or more light source apertures disposed adjacent to a lateral reflector. The reflector assembly can comprising any number of reflector modules and the reflector modules can be arranged in different configurations to create different light distributions with the same reflector modules.

Resolution analysis for imaging with noise

Abstract: We analyze the resolution of imaging functionals that migrate the cross-correlation matrices of passive sensor arrays. These matrices are obtained by cross-correlating signals emitted by ambient noise sources and recorded by the passive sensor array. They contain information about reflectors in the surrounding medium. Therefore, travel time or Kirchhoff migration of the cross-correlations can, under favorable circumstances, produce images of such reflectors. However, migration should be carried out appropriately depending on the type of illumination provided by the ambient noise sources. We present here a detailed resolution analysis of these functionals in a homogeneous medium. Resolution depends on the sensor array diameter, the distance from the array to the reflector and the central frequency, as is the case in active array imaging. When imaging with passive sensor arrays and ambient noise, resolution also depends on the space and time coherence of the noise sources because it determines an effective noise bandwidth.