Showing papers on "Reflector (antenna) published in 1997"

Differential interferometer system and lithographic step-and-scan apparatus provided with such a system

Abstract: A differential interferometer system for measuring the mutual positions and movements of a first object (WH) and a second object (MH) is described, which system comprises a first interferometer unit (1, 2, 3, 4) with a first measuring reflector (RW) and a second interferometer unit (5, 6, 7, 8) with a second measuring reflector (RM). Since a measuring beam (bm) passes through both the first and the second interferometer unit and is reflected by both the first and the second measuring reflector, and since the measuring beam and the reference beam (br) traverse the same path at least between the two interferometer units, accurate measurements can be performed very rapidly. The interferometer system may be used to great advantage in a step-and-scan lithographic projection apparatus.

Illuminating assembly for use with bar code readers

Abstract: An array of reflectors is arranged to approximately match the arrangement of a two-dimensional array of LEDs such as used in a 2-D bar code scanner. Each reflector has at least one reflecting wall for reflecting light from a respective LED, thus increasing the amount of LED light illuminating the target.

Focussed ultrasound tissue treatment method

Abstract: A method of treatment of tissue with focussed ultrasound comprises placing adjacent the tissue to be treated a reflector of ultrasound or an ultrasound energy conversion device which converts received ultrasound energy to heat, stores the heat and then releases the heat over time into the tissue to be treated. An ultrasound transducer is then oriented with its focal point adjacent the reflector or ultrasound energy conversion device. The tissue is then irradiated with high intensity focussed ultrasound while the reflector or ultrasound energy conversion device is in place.

Feeder link antenna

Abstract: A steerable feeder link antenna is formed of a steerable reflector and a stationary feed horn assembly. A novel feed horn assembly allows dual mode transmit and receive functions for circularly polarized microwaves. The feed horn assembly includes a four arm turnstile junction coupled to a feed horn through the feed horn's side wall to couple transmit frequencies and an axially coupled transmission line for the receive frequencies. Each turnstile junction arm incorporates chokes for the receive frequencies. The transmission line's cut off frequency is above the transmit frequency to prevent transmit signals from interfering with receive signal receivers.

Mobile tracking antenna made by semiconductor technique

Abstract: A mobile tracking antenna for microwave signals from a satellite or distant transmitter includes a micro- electromechanical system produced by semiconductor processing. Specifically several micro faceted reflector segments have their facets selectively controlled by a feedback control system and reflects the signal onto a four sector horn which then by error signals actuates electrostatic positioning means on the micro facets to center the signal on the optimum receiving portion of the horn. Each segment covers a portion of the 360° receiving spectrum. The particular segment is selected by a maximum signal being received.

Optical limiting and switching of short pulses by use of a nonlinear photonic bandgap structure with a defect

Abstract: An extension of the recently introduced nonlinear finite-difference time-domain technique [Opt. Lett.21, 1138 (1996)] for the study of electromagnetic wave propagation in a non-linear Kerr medium to include absorption is presented. The optical limiting and switching of short pulses by use of a nonlinear quarter-wave reflector (a one-dimensional photonic bandgap structure) with a defect is studied. Comparison with an optical limiter and with an optical switch with a perfect nonlinear quarter-wave reflector shows that introducing a defect can improve the performance of these devices.

Excitation system for an antenna with a parabolic reflector and a dielectric radiator

Abstract: An excitation system which can be used with sector antennas which do not have circular reflectors is described. The reflector is designed as a rectangular strip which curves parabolically in the direction of its long axis to form a sector antenna. The end face of the radiator has four partial faces which form equal pairs and their opposing faces are arranged with respect to the central axis of the hollow conductor so that the surfaces of the two pairs extend at approximately right angles to each other. The partial faces of the radiator extending in the direction of the long axis of the reflector are large in relation to the two partial faces extending crosswise thereto.

Slot antenna device and wireless apparatus employing the antenna device

Abstract: A miniaturized and thin slot antenna device maintains high transmitting and receiving performance by improving the configuration of an antenna body and a circuit substrate. The slot antenna device includes an antenna body made of an electrically conductive member having a slot into which the circuit substrate is placed. Alternatively, the slotted, electrically conductive member can be placed flat on a first surface of the circuit substrate, which can contain a reflector on its second, opposite surface. The slot antenna device also can be constructed from two parallel, opposed, electrically conductive members spaced apart by a gap so that a slot is defined by outer peripheries of the electrically conductive members. The electrically conductive members can be provided on opposite surfaces of a circuit substrate.

Inexpensive modulated backscatter reflector

Abstract: The present invention provides for an inexpensive RFID Tag design which uses an inexpensive Backscatter Modulator. The modulator is simply a CMOS gate driven by a shift register containing a modulating signal. The CMOS gate is connected to the antenna such that it modulates the reflectivity of the antenna in accordance with the modulating signal. In a second embodiment, the Tag is incorporated into a single CMOS integrated circuit which comprises all of the components, except for the antenna, necessary to implement an inexpensive read-only RFID Tag.

Determination of reflector surfaces from near-field scattering data

Abstract: Consider a reflector system consisting of a reflecting surface R, a point light source O and some object T. Suppose that the source O, reflector R and object T are positioned so that the rays reflected off R are incident on T. Depending on the geometry of R, the energy, radiated by O and redirected by R, is distributed on T producing a certain illumination pattern. We present here a solution of the inverse problem consisting of reconstructing the reflector R from the following data: the position of the source O, its radiation intensity I, the object T, and prespecified energy pattern to be achieved on T. It is shown that under assumptions of geometric optics theory the problem admits a solution, provided the total input and output energies are equal, and some other geometric conditions are satisfied. In analytic formulation, the problem leads to an equation of Monge - Ampere type in a domain on a unit sphere. In this paper we formulate the problem in terms of certain associated measures and establish the existence of weak solutions.

Angled distributed reflector optical device with enhanced light confinement

Abstract: A optical medium, such as an angled distributed reflector, e.g., an angular grating, or α-DFB laser diode or a waveguide wavelength selective filter, has a mean optical axis defining an optical cavity for substantially confined light propagation within the device. An angular grating is provided in at least a portion of the optical cavity forming a grating region permitting light to propagate along the optical cavity in two coupled waves or modes incident along the angular grating, a first incident propagating wave substantially parallel with respect to the mean optical axis and a second incident propagating wave at an angle with respect to the mean optical axis. At least one preferential coupling region in the optical cavity at an interface or boundary with the grating region to receive both propagating waves and provide for preferential treatment to the first incident propagating wave by coupling propagating light in the second incident propagating wave into the first incident propagating wave prior to light output from the medium via the non-grating region, forming a boundary with the grating region. The angle of the boundary at the interface of these respective regions is chosen to be substantially collinear with a propagation direction of the second incident propagating wave so that propagating light in the second incident propagating wave will substantially enter the preferential coupling region from the grating region via the boundary in a propagation direction substantially parallel with the mean optical axis.

Seismic data processing in vertically inhomogeneous TI media

Abstract: The first and most important step in processing data in transversely isotropic (TI) media for which velocities vary with depth is parameter estimation. The multilayer normal‐moveout (NMO) equation for a dipping reflector provides the basis for extending the TI velocity analysis of Alkhalifah and Tsvankin to vertically inhomogeneous media. This NMO equation is based on a root‐mean‐square (rms) average of interval NMO velocities that correspond to a single ray parameter, that of the dipping event. Therefore, interval NMO velocities [including the normal‐moveout velocity for horizontal events, Vnmo(0)] can be extracted from the stacking velocities using a Dix‐type differentiation procedure. On the other hand, η, which is a key combination of Thomsen's parameters that time‐related processing relies on, is extracted from the interval NMO velocities using a homogeneous inversion within each layer. Time migration, like dip moveout, depends on the same two parameters in vertically inhomogeneous media, namely Vnmo...

Uniform asymptotic solution for electromagnetic reflection and diffraction of an arbitrary Gaussian beam by a smooth surface with an edge

Abstract: A closed form solution is obtained to describe, in a physically appealing manner, the reflection and diffraction of a general astigmatic Gaussian beam which is incident on an arbitrary smooth, electrically large, slowly varying curved, perfectly conducting screen (or reflector). This closed form solution is obtained via an asymptotic evaluation of the radiation integral for the fields scattered from the reflector, to within the physical optics approximation that remains valid for the present situation. The analysis developed here is particularly well suited for the fast analysis of electrically large reflector antennas by representing the feed illumination by a relatively small set of Gaussian beams launched from the feed plane. Each of these Gaussian beams after being launched undergoes reflection and diffraction at the reflector; the expressions for the reflected and diffracted fields are developed in this paper and utilized by Chou [1996] to compute the radiation pattern of large reflector antennas in a matter of a few seconds as compared to the conventional numerical physical optics integral method which takes hours on the same computer.

Medical diagnostic apparatus using a Fresnel reflector

Abstract: A device for use in a medical diagnostic apparatus includes an area for containing a sample of biological fluid as it undergoes a reaction that causes a detectable change in the sample's optical properties. The reaction area is sandwiched between a transparent front layer and a Fresnel reflector layer. The area is illuminated through the front layer, and the light is reflected from the reflector layer to a detector. The detector monitors the light incident on it and calculates, from the change during the course of the reaction, an analyte concentration or property of the fluid sample. The reaction area is optionally heated.

Low threshold vertical-cavity surface-emitting lasers based on high contrast distributed bragg reflectors

Abstract: Data are presented on vertical-cavity surface-emitting lasers that use high contrast distributed Bragg reflectors on both sides of the cavity. The upper reflector consists of a six pair ZnSe/MgF quarter-wave stack, while the lower reflector consists of an eleven pair AlxOy/GaAs stack fabricated using selective oxidation. Strain due to the lower reflector is reduced by using AlxOy layers of less than a quarter-wave thickness. Device sizes ranging from 1 to 7 μm diameters are characterized, with a minimum threshold current of 53 μA.

Battery operated appliance, flashlight and switching systems

Abstract: An electric appliance includes a first electric power supply of first batteries arranged in a first pattern, and alternatively a different second electric power supply of second batteries arranged in a second pattern. An electrical ON-OFF switch has an ON-OFF position push-button switch actuator ard a rotary switch actuator which releasably blocks that ON-OFF position push-button switch actuator in an OFF position. A tail end is equipped with a bistable OFF and ON switching function and with a momentary ON switching function unified into one electric toggle switch having a stable OFF position, a stable ON position, and a momentary ON position. A flashlight beam is cast with a first lamp and reflector assembly, an alternative second lamp and reflector assembly is substituted for that first lamp and reflector assembly and a second light beam of a different configuration is cast with that alternative second lamp and reflector assembly.

Position tracking system

Abstract: An optical position tracking system that tracks the position of objects, using light intensity and/or frequency with the application of geometry and ratios of detector responses, is provided, having light distributing and light detecting components that employ the concepts of constructive occlusion and diffuse reflection. Diffusely reflective cavities, masks and baffles are used to improve certain radiating characteristics of the distributing components and certain response characteristics of the detecting components, to tailor the radiation and detection profiles thereof, including them substantially uniform for all angles within a hemispheric area which the distributing and detecting components face. The distributing and/or detecting components are partitioned with specially-configured baffles. A partitioned distributor has distinct emission sections where the sections can emit spectrally-different or distinguishable radiation. A partitioned detector has distinct detection sections where the sections can detect radiation from different directions. The system may be variously configured, to use different combinations of partitioned and nonpartitioned devices. In most configurations, a single head module provides one set of directional data about two coordinates (e.g., ρ and Θ) for one reflector. An additional head module remotely positioned from the first head module can provide a second set of directional data for the reflector (e.g., ρ2 and Θ2), for cross-referencing with the first set of directional data to obtain positional data in three dimensions of the object being tracked. The system can also track multiple objects, using spectrally-different (or at least spectrally distinguishable reflectors) in conjunction with correspondingly spectrally-compatible sensors to distinguish between data collected for each reflector. Numerous variations particularly on the concept of constructive occlusion may be accomplished with varying results as desired or appropriate. By reconfiguring the radiation/detection surface, the cavity, the mask and/or the baffle, the radiation/detection profile may be varied in substantially unlimited ways.

Acoustic wave filter

Abstract: A surface acoustic wave filter provided on a substrate, comprising a transducer and a first reflector for surface acoustic waves at one end of the transducer, the first reflector being integral with conductive material that defines a busbar of the filter.

Apparatus for and method of detecting a reflector within a medium

Abstract: An apparatus is provided in which a phased transmitting array (21) is arranged to irradiate a selected voxel within a search volume. Energy reflected from the voxel is received by a further antenna and the signals received from a plurality of voxels are analysed to search for reflectors or discontinuities within the search space.

Liquid crystal display apparatus

Abstract: A liquid crystal display device is provided by forming an optical blocking layer which blocks intensive incident light leaking into switching elements. A plurality of switching elements 1 is formed on a substrate 10. A first electrode 2 is connected to and positioned over the switching element. A storage capacitor 3 is connected and positioned under the first electrode. An optical reflector 15 is formed on the first electrode. A transparent second electrode 4 is spaced apart from the optical reflector. A layer of liquid crystal material 5 is positioned between the optical reflector and the second electrode. A substantially nonconductive optical blocking layer 20 is formed between the first electrode and the switching element.

Combined satellite and terrestrial antenna

Abstract: A combined satellite and terrestrial antenna has a reflector dish formed of a conductive metal supported by but electrically insulated from a support structure. A pick-up for the satellite transmission signal is also supported by the support structure at a position to receive satellite microwave signals reflected from the dish. An electrical connector is attached to and in electrical contact with the metal of the dish and a transmission line extends from the connector to transmit UHF/VHF signals which are received by the metal dish itself. The UHF/VHF signals may be combined with the signals from the satellite pick-up and transmitted together on a common transmission line leading to a receiver. A loop section may be connected by swivel connectors to the periphery of the reflector dish to be in electrical contact therewith to further enhance the reception of UHF/VHF frequencies. The loop section may be adjusted to a position either in the front or the back of the dish to maximize reception of UHF/VHF signals.

Multi-colour reflector device and display

Abstract: A reflector device has a stack of three reflective layers 100,102,108 each of which selectively reflects different a part of the spectrum of white light 106 to a different region. The respective regions may or may not overlap each other. The layers 100,102,108 may be reflective cholesteric liquid crystal materials, dichroic mirrors or reflective multi-layer interference structures. The layers 100,102,108 may be, planar, curved or formed from several curved surfaces in series (fig.11) and may be mutually inclined. The third layer 108 may be combined with either a black absorber layer (110, fig.5) or a panchromatic layer (112, fig.6). The incoming light may be focused by a plano-convex lens array (116,fig.13). The reflector device may be used in a display in conjunction with a spatial light modulator 104, such as a liquid crystal device, having pixels 104a-c, selectively illuminated by light from the regions.

Acoustic wave impedance element ladder filter having a reflector integral with a busbar

Abstract: A surface acoustic wave filter provided on a substrate, comprising a transducer and a first reflector for surface acoustic waves at one end of the transducer, the first reflector being integral with conductive material that defines a busbar of the filter.

Fiber optic light source apparatus and method

Abstract: A fiber optic cable lateral illumination system (100) comprising a housing (14) having an internal cavity and an aperture communicating the cavity externally of the housing, an optical system located within the internal cavity; the optical system (30) comprising a reflector and a high intensity lamp (31) positioned within the reflector (32) for directing light along an optical axis (44), a plate (48) of heat absorbing material spaced from the reflector (32), and at least one color filter spaced from the plate (48) and the reflector (32); the optical cable (100) including a plurality of optical fibers (99) and a ferrule assembly (200) for supporting the cable to the optical system (30).

Analytical solution for early-time transient radiation from pulse-excited parabolic reflector antennas

Abstract: A closed-form analytical solution is developed for predicting the early-time transient electromagnetic fields which are generated by a perfectly conducting parabolic reflector antenna when it is illuminated by a transient step spherical wave due to an elemental Huygen's source located at the focus. This closed-form time-domain solution, which is valid both near and far from the reflector (and anywhere in the forward region) can be used via the convolution theorem to efficiently obtain the early-time transient fields generated by the same parabolic reflector antenna when it is illuminated by a realistic finite-energy pulse which emanates as a spherical wave from the focus. The transient solution is developed here by analytically inverting, in closed form, the corresponding frequency-domain solution in terms of a radiation integral that employs an asymptotic high-frequency geometrical optics (GO)-based approximation for the fields in the aperture. Numerical results are presented for the transient fields both near and far from the reflector. The fields on boresight exhibit an impulse-like behavior similar to that of the impulse radiating antenna (IRA) introduced by Baum et al. (1989, 1993).

Method of radio transmission between a radio transmitter and radio receiver

Abstract: An antenna assembly providing selectable omnidirectional or directional reception of radio transmissions in a frequency band in accordance with the invention includes an electrically conductive reflector (432) defining a cavity (702) having a bottom (708), an opening (714) and a surface (704 and 706) extending from the bottom to the opening and an electrical output (763); an electrically conductive loop (431) coupled to ground and having an electrical outlet (766) for coupling to an RF amplifier (407), the loop being positioned between the bottom opening of the cavity; a RF switch (406) having an input (760) and first and second outputs (762 and 764), the RF switch having a first switching state electrically connecting the input to the first output and a second switching state electrically connecting the input to the second output, the first switch output being electrically coupled to ground and the second switch output being electrically coupled to the output of the electrically conductive loop; and wherein the first switching state provides the directional reception and the second switching state provides the omnidirectional reception of the radio transmissions.

Telescoping deployable antenna reflector and method of deployment

Abstract: In accordance with the teachings of the present invention, a telescoping deployable mesh antenna reflector for space communication applications and a method of deployment is provided. The antenna reflector includes a plurality of telescoping radially extending ribs between which a plurality of interconnected guylines are secured to form a wire truss structure. The telescoping radially extending ribs include pivotally coupled inner and outer ribs that are collapsed and folded to stow the antenna. A highly reflective wire woven mesh is connected to the front surface of the wire truss structure with flexible radially extending strip members allowing for folding and telescoping of the antenna reflector.

External resonator type wavelength- tunable light source

Abstract: A wavelength-tunable light source is provided, by which an output beam of a stable wavelength can be obtained even if a driving condition of the optical amplifier is changed, and in which stable wavelength tuning without mode hopping can be performed. The light source comprises: an optical amplifier, both end faces thereof being antireflection-processed, for generating a natural emission beam from one end face of the amplifier, and for amplifying a beam input into the one end face and outputting the amplified beam from the other end face of the amplifier; an optical amplifier drive circuit for driving the optical amplifier; an optical resonance reflector for resonating the natural emission beam output from the optical amplifier at an optical resonance wavelength, and reflecting the resonated beam to the one end face of the optical amplifier; a wavelength controller for controlling the optical resonance wavelength of the optical resonance reflector; a resonance length controller for controlling a resonance length of the optical resonance reflector; and a beam outputter for extracting a beam, which was reflected by the optical resonance reflector, amplified by the optical amplifier, and output from the other end face of the optical amplifier, and outputting the extracted beam.