Showing papers on "Collimated light published in 2001"

Flat-panel display

Abstract: A flat-panel display comprises a projector (21-23) illuminated by a collimate light source such as an infra-red laser, a waveguide (1) which ejects rays at a distance along the axis of propagation related to their angle of injection into the edge of the waveguide, an input slab (3) for magnifying the projected image in the width dimension in the plane of the panel perpendicular to the axis of propagation, and a phosphor output screen which converts the infra-red light to the visible. The use of monochromatic light within the waveguide reduces dispersion problems, and the use of a triad of projectors, each injecting at a different angle, makes registration relatively simple.

Afterglow Emission from Highly Collimated Jets with Flat Electron Spectra: Application to the GRB 010222 Case?

Abstract: We derive light curves of the afterglow emission from highly collimated jets if the power-law index (p )o f the electron energy distribution is above 1 but below 2. We find the following: (1) Below the characteristic synchrotron frequency, the light-curve index depends generally on p. (2) As long as the jet expansion is spherical, the light-curve index above the characteristic frequency increases slowly as the spectral index of the emission increases. (3) Once the jet enters the spreading phase, the high-frequency emission flux decays as proportional to rather than proportional to . All these results differ from those in the case of . We compare ( p6)/4 p tt p 1 2 our analytical results with the observations on the GRB 010222 afterglow and conclude that the jet model may be unable to explain the observed data. Thus, a more promising explanation for this afterglow seems to be the expansion of a relativistic fireball or a mildly collimated jet in a dense medium. Subject headings: gamma rays: bursts — relativity — shock waves

Optical free space signalling system

Abstract: There is a described a free space optical signalling system in which data is transmitted from an optical transmitter to an optical receiver. The optical transmitter includes means for modulating one or more light beams in accordance with the data to be transmitted so as to generate a plurality of modulated light beams which are output from the optical transmitter as substantially collimated, spatially-separated, parallel free-space light beams. The optical receiver includes a plurality of detectors, each detector detecting a corresponding one of the plurality of modulated, parallel, free-space light beams and converting the detected light beam into a corresponding electrical signal from which the data can be recovered.

Production and characterization of highly intense and collimated cluster beams by inertial focusing in supersonic expansions

Abstract: Intense and collimated supersonic cluster beams have been produced by exploiting inertial focusing effects. To this goal we have developed and tested a novel focusing nozzle (focuser). Using this device with a pulsed microplasma cluster source we have obtained cluster beams with a divergence of 10 mrad and average densities of 3×1010 atoms/cm3 (2×1012 atoms/cm3 pulsed) corresponding to deposition rates of 2 nm/s at 300 mm distance from the source nozzle. With a focusing nozzle cluster thermal relaxation and mass distribution in a supersonic expansion can be controlled. We have measured the cluster transverse velocities, with extremely high precision, by characterizing the cluster beam deposition on a substrate by an atomic force microscope. Besides the relevance for the understanding of relaxation processes in expanding jets, the inertial focusing of clusters has several important consequences for the synthesis of nanostructured films with controlled structure and for all the experimental techniques requi...

One-piece lens arrays for collimating and focusing light and led light generators using same

Abstract: A lens array (10) useful for a light emitting diode (LED) light generator (16) containing an array (17) of LED sources (18) The lens array (10) is a unitarily formed member (12) having a plurality of collimator lenses (14) arranged in a predetermined array so that each lens (14) operates as a collimator for a corresponding LED source (18) The lenses (14) of the array are constructed to direct the collimated beams of the individual LED sources (18) toward a predetermined target (22), thus, enabling a less refractive collection element In addition, the efficiency of the individual collimators can be varied, leading to increased system efficiency

A Focused Ultrasoft X-Ray Microbeam for Targeting Cells Individually with Submicrometer Accuracy

Abstract: Folkard, M., Schettino, G., Vojnovic, B., Gilchrist, S., Michette, A. G., Pfauntsch, S. J., Prise, K. M. and Michael, B. D. A Focused Ultrasoft X-Ray Microbeam for Targeting Cells Individually with Submicrometer Accuracy. Radiat. Res. 156, 796–804 (2001). The application of microbeams is providing new insights into the actions of radiation at the cell and tissue levels. So far, this has been achieved exclusively through the use of collimated charged particles. One alternative is to use ultrasoft X rays, focused by X-ray diffractive optics. We have developed a unique facility that uses 0.2–0.8-mm-diameter zone plates to focus ultrasoft X rays to a beam of less than 1 μm diameter. The zone plate images characteristic K-shell X rays of carbon or aluminum, generated by focusing a beam of 5–10 keV electrons onto the appropriate target. By reflecting the X rays off a grazing-incidence mirror, the contaminating bremsstrahlung radiation is reduced to 2%. The focused X rays are then aimed at selected subc...

Method and apparatus for determining a material of a detected item

Abstract: A method for determining the material of a detected item in objects, especially explosives in luggage, using X-ray diffraction. In this method, wherein scatter radiation deflected at the crystal-lattice structure of the material is measured and compared to characteristic energy spectra or diffraction spectra of various explosives, the absorption by the material influences the X-ray diffraction spectrum, so that information is missing, and inaccurate conclusions may be drawn regarding the material. To improve this method, the primary beam of an X-ray source is used for measuring the absorption. The beam passes through the material, and, from the absorption, an average atomic number of the material is determined, and this additional information is used for the identification of material known by comparing the recorded spectra with diffraction spectra. For this purpose, a collimation/detector arrangement preferably has only one collimator ( 8 ) and one detector ( 9 ), with the collimator ( 8 ) having a conically-expanding circular slot ( 1 ), which defines a predetermined diffraction angle, and a central blind bore ( 1 ) opening toward the x-ray source. First and second detectors ( 13, 14 ) are disposed in the bore to detect lower and higher x-ray energy, respectively.

Illumination device and method for laser projector

Abstract: Systems and methods for providing illumination suitable for imaging devices such as laser projection systems. In one embodiment, a highly collimated (e.g., laser light) beam is passed through a holographic diffuser to create a well defined cone angle for the light emanating from each point on the diffuser. This light is focused into an illumination image that is controlled by the prescription of the diffuser. In one embodiment, the image is a uniformly intense rectangle having a 4:3 aspect ratio to match an imager for a projection display. The diffuser prescription and resulting illumination image can be selected to match any desired imager. The present systems and methods may provide the advantages of high level of light efficiency, reduction or elimination of speckle and 'worminess' and reduction or elimination of cosine4 and gaussian intensity falloff, all of which are common in prior art designs.

Optical system and method for optically analyzing light from a sample

Abstract: An optical system for analyzing light from a plurality of samples is provided. The optical system includes a plurality of holders adapted to have samples located therein, a collection lens, a transmission grating, and a reimaging lens. The collection lens is configured to receive and substantially collimate light from the samples. The transmission grating is configured to spectrally disperse the substantially collimated light from the collection lens. The reimaging lens is configured to receive the light from the light dispersing element and direct the light onto a light detection device. A method of optically analyzing at least one sample is also provided.

Optical characterization of melanin

Abstract: The optical properties of melanin have been characterized for a number of laser wavelengths in the visible region. The index of refraction of melanin is measured by the conventional method of minimum deviation using a hollow quartz prism at these wavelengths. The inverse adding doubling method based on the diffusion approximation and radiative transport theory have been employed to determine the absorption, scattering, and scattering anisotropy coefficients of melanin from the measurements of diffuse transmission, diffuse reflection and collimated transmission using double integrating spheres. The results obtained by the use of inverse adding doubling method have been compared to the Monte Carlo simulation technique.

Illuminating device and liquid-crystal display apparatus

Abstract: The illuminating device includes light sources, a housing of the light sources that has its inner surfaces covered with a diffuse reflecting layer, an optical collimator for collimating the light issued from the light sources and the light reflected by the diffuse reflecting layer, and a directivity regulating member for regulating the directivity of the collimated light emerging from the optical collimator. The liquid-crystal display apparatus has a liquid-crystal display panel and the illuminating device. The illuminating device can emit collimated light of very high directivity and may be utilized in the liquid-crystal display apparatus to display images of high quality and contrast over a wide range of viewing angles.

High-sensitivity absorption measurement in water and glass samples using a mode-mismatched pump-probe thermal lens method

Abstract: We report on a mode-mismatched pump-probe thermal lens experiment performed to measure absorption coefficients as small as 10−8 cm−1 in liquid and solid samples. We take advantage of the large axial dimension of the thermal lens by focusing the pump beam in the presence of a collimated probe beam. We measure an absorption coefficient at 533 nm of (6.8±0.1)×10−4 cm−1 and of (3±0.3)×10−6 cm−1 for distilled water and BK7 optical glass, respectively.

Pixel element for a three-dimensional screen

Abstract: A pixel element for a 3D display, wherein multiple substantially collimated controllable light beams are emitted in multiple directions, with each light beam associated with a predetermined viewing direction. A set of substantially point type sources are individually addressable and are arranged in a line. The light sources are serially addressed; and the light from each source is imaged in a collimated light beam and deflected in a predetermined individual deflection direction.

The versatility of collimated plane grating monochromators

Abstract: In the last few years monochromator development at the German synchrotron radiation facility BESSY II improved conventional monochromator designs, especially the SX700 design, considerably. It was possible to convert the high brilliance of undulator radiation at third generation synchrotron sources very successfully into outstanding monochromator performance in terms of high energy resolution, photon flux and focus size. New mechanical designs and precise control of the angular settings of optical elements resulted in very high monochromator stability and allowed even for an absolute energy calibration of monochromators. This report reviews the design principles of collimated plane grating monochromators and presents results obtained within the first two years of BESSY II operation.

One-sided jet at milliarcsecond scales in LSI+61303

Abstract: We present Very Long Baseline Interferometry (VLBI) observations of the high mass X-ray binary LSI+61303, carried out with the European VLBI Network (EVN). Over the 11 hour observing run, performed 10 days after a radio outburst, the radio source showed a constant flux density, which allowed sensitive imaging of the emission distribution. The structure in the map shows a clear extension to the southeast. Comparing our data with previous VLBI observations we interpret the extension as a collimated radio jet as found in several other X-ray binaries. Assuming that the structure is the result of an expansion that started at the onset of the outburst, we derive an apparent expansion velocity of 0.003 c, which, in the context of Doppler boosting, corresponds to an intrinsic velocity of at least 0.4 c for an ejection close to the line of sight. From the apparent velocity in all available epochs we are able to establish variations in the ejection angle which imply a precessing accretion disk. Finally we point out that LSI+61303, like SS433 and Cygnus X-1, shows evidence for an emission region almost orthogonal to the relativistic jet.

Optical configuration for a dynamic gain equalizer and a configurable add/drop multiplexer

Abstract: An optical device for rerouting and modifying an optical signal that is capable of operating as a dynamic gain equalizer (DGE) and/or a configurable optical add/drop multiplexer (COADM) is disclosed. The optical design includes a front-end unit for providing a collimated beam of light, an element having optical power for providing collimating/focusing effects, a diffraction element for providing spatial dispersion, and modifying means which in a preferred embodiment includes one of a MEMS array and a liquid crystal array for reflecting and modifying at least a portion of a beam of light. The modifying means functions as an attenuator when the optical device operates as a DGE and as a switching array when the optical device operates as a COADM. Advantageously, this invention provides a 4-f system wherein a preferred embodiment the element having optical power is a concave reflector for providing a single means for receiving light from the front-end unit, reflecting the received light to the dispersive element, receiving light from the dispersive element, and providing dispersed light to the modifying means. Conveniently and advantageously, this same concave reflector is utilized on a return path, obviating the requirement of matching elements. In one embodiment a single focussing/collimating lens is provided substantially at a focal plane of the element having optical power.

Multidimensional sensing system for atomic force microscopy

Abstract: A six degree of freedom atomic force microscope (6-DOF AFM) is provided by the present invention. This 6-DOF AFM includes an AFM cantilever coupled to an AFM tip wherein the AFM tip deflects the cantilever in response to topographical changes on a sample. The AFM cantilever is illuminated by a collimated light beam generated by a collimated light source. The collimated light is reflected by the top surface of the AFM cantilever towards a PSD placed in the path of the reflected collimated light beam. The PSD produces an output containing data representing a deflection of the AFM cantilever. This output is processed by a data acquisition system to produce a representation of the topographical changes of the sample.

Apparatus and method for measuring spatially varying bidirectional reflectance distribution function

Abstract: An apparatus and method for measuring spatially varying bidirectional reflectance distribution function and method are provided. The apparatus and method provide means to illuminate different areas of a sample at different angles of incidence and detect the angular variation of radiation emitted from the sample in response to the illumination. The apparatus includes a paraboloidal reflector for delivering the illumination and receiving the radiation emitted by the sample, a radiation source for generating a beam of collimated radiation, a beam steering device for controlling the angle of incidence with which the focused cone of light strikes the sample, and a detector to receive the collected light from the reflector.

Radiation element method for transient hyperbolic radiative transfer in plane-parallel inhomogeneous media

Abstract: In this study the radiation element method is formulated to solve transient radiative transfer with light radiation propagation effect in scattering, absorbing, and emitting media with inhomogeneous property. The accuracy of the method is verified by good agreement between the present calculations and Monte Carlo simulations. The sensitivity of the method against element size, ray emission number, and time increment size is examined. The transient effect of radiation propagation is essential in short-pulse laser radiation transport when the input pulse width is not considerably larger than the system radiation propagation time. The transient characteristics of radiative transfer are investigated in the media subject to collimated laser irradiation and/or diffuse irradiation withtemporal Gaussian and/or square profiles. The inhomogeneous profile of extinction coefficient of the medium affects strongly the transient radiative flux divergence inside the medium.

X-ray collimator

Abstract: A collimator having slits of varied widths, wherein each slit includes a curved side profile having a common axis of curvature for providing a cross-section of an emitted beam of energy with a substantially uniform width when the common axis of curvature of the slit intersects a focal spot of a source of the beam. The collimator is curved about a rotation axis substantially normal to the common axis of curvature, such that rotating the collimator about the rotation axis will sequentially position the slits to collimate the emitted beam.

Collimator scatter and 2D dosimetry in small proton beams

Abstract: Monte Carlo simulations have been performed to determine the influence of collimator-scattered protons from a 150 MeV proton beam on the dose distribution behind a collimator. Slit-shaped collimators with apertures between 2 and 20 mm have been simulated. The Monte Carlo code GEANT 3.21 has been validated against one-dimensional dose measurements with a scintillating screen, observed by a CCD camera. In order to account for the effects of the spatial response of the CCD/scintillator system, the line-spread function was determined by comparison with measurements made with a diamond detector. The line-spread function of the CCD/scintillator system is described by a Gaussian distribution with a standard deviation of 0.22 mm. The Monte Carlo simulations show that protons that hit the collimator on the entrance face and leave it through the wall of the aperture make the largest scatter contribution. Scatter on air is the major contribution to the extent of the penumbra. From the energy spectra it is derived that protons with a relative biological effectiveness greater than 1 cause at most 1% more damage in tissue than what would be expected from the physical dose.

Double-resonance-absorption microscope

Abstract: The present invention provides various techniques useful for a double-resonance-absorption microscope which realizes a super-resolution by using a double resonance absorption. As one technique, there is provided a double-resonance-absorption microscope comprising a light source for a pump light of a wavelength λ1 which excites a sample molecule to a first electronic excited state from a ground state, a light source for an erase light of a wavelength λ2 which excites the sample molecule to a second electronic excited state or a higher excited state from the first electronic excited state and overlap means for partially overlapping irradiating areas of the pump light and the erase light with each other, wherein an emission area upon deexcitation of the sample molecule to the ground state from the first electronic excited state is partially inhibited by irradiating the pump light and the erase light through the overlap means, said double-resonance-absorption microscope characterized in that there is provided, on an optical path of the erase light, a spatial filter which has a condenser lens and a collimate lens and a pinhole therebetween and performs condensing of the erase light onto the pinhole by the condenser lens and collimating of the erase light passed through the pinhole into a parallel beam by the collimate lens.

Three-dimensional resolution enhancement in fluorescence microscopy by harmonic excitation.

Abstract: A method for increasing lateral as well as axial resolution in fluorescence microscopy is presented. A passband with a high cutoff frequency throughout reciprocal space can be achieved by illumination of the object with spatially harmonic excitation patterns generated by the interference of two collimated laser beams. Theoretical calculations show an almost isotropic point-spread function with a FWHM near 100 nm.

Method and apparatus for measuring optical aberrations of the human eye

Abstract: An apparatus for measuring optical aberrations of the human eye wherein the person positions his or her eye on an optical axis of the apparatus and looks at an illuminated target on the optical axis that is visible to the eye for allowing the eye to focus on the target and establish a position of the eye. A collimating lens on the optical axis is movable along the optical axis for adjusting the apparent optical distance between the eye and the target. A light source directs a predetermined light beam along the optical axis into the eye and onto the retina of the eye as a spot of light. A lens reimages the light scattered from the light spot on the eye retina into a wavefront curvature sensor that forms two oppositely defocused images on an image detector, and a computer processes and analyzes the two defocused images for measuring the optical aberrations of the eye.

Apparatus for determining the crystalline and polycrystalline materials of an item

Abstract: A diffraction apparatus ( 10 ) for determining crystalline and polycrystalline materials of an item in objects, preferably in luggage, having a collimation/detector arrangement ( 11 ) and an X-ray source ( 12 ) and which is mounted to be adjustable in an X-ray testing machine ( 13 ). The collimation/detector arrangement ( 13 ) is adjustable in height relative to the X-ray source ( 12 ), and the two are also laterally and synchronously adjustable via respective adjustment elements ( 5,6 ). The collimator ( 13 ) has a conically-expanding round slot ( 15 ), which simulates a predetermined angle (Θ M ) of a scatter-beam path.

The Jet and the Supernova in GRB990712

Abstract: The optical light curve of the afterglow following the gamma-ray burst GRB990712 is re-examined. Recently published polarization measurements of that source require a collimated outflow geometry that in turn predicts a break in the light curve. We show that the V-band light curve is consistent with such a break and that the post-break light curve evolution is dominated by a supernova contribution.

Method and apparatus for high-energy generation and for inducing nuclear reactions

Abstract: A system is provided for generating high-energy particles and for inducing nuclear reactions The system includes a laser and for emitting a laser beam, an irradiation target for receiving the laser beam and producing high-energy particles, and a secondary target for receiving the high-energy particles, thereby inducing a nuclear reaction A method is also provided including producing a laser beam of high-intensity with an ultra-short pulse duration, irradiating the laser beam onto an irradiation target in order to ionize the irradiation target and produce a collimated beam of high-energy particles, and colliding the collimated beam of high-energy particles onto a secondary target containing a nuclei, thereby inducing a nuclear reaction on the secondary target

Optical cross-connect switch with integrated optical signal tap

Abstract: An optical cross-connect with integrated optical signal tap is disclosed. In one embodiment, the switch includes two or more optical fiber input ports, lenses to produce collimated beams, one or more optical taps to couple a portion of the optical power from one or more input ports to one or more sample ports, movable mirrors to connect any input port with any output port, two or more optical fiber output ports, and lens to couple collimated beams into the output ports.

Stabilization of a laser array module

Abstract: A laser array system (100) including a plurality of lasers (102), a switching mechanism (108), a wavelength locking mechanism (110), and a laser parameter feedback control (116). Each laser provides a collimated beam having certain wavelength and power. The beam has at least two parts (104, 106), first part (104) of the two is used for stabilization of the wavelength and power. The switching mechanism (108) is configured to receive and sequentially select the first part (104) of the beam from the lasers (102). The laser parameter feedback control (116) is configured to adjust laser parameters of the selected laser.

Hollow cavity light guide for the distribution of collimated light to a liquid crystal display

Abstract: An optical light guide comprising optical elements enclosing a hollow cavity (7) is configured to uniformly distributed homogenized collimated light (1) to a liquid crystal display (16). The optical light guide includes a beam splitting structure (3) covering the entrance aperture (2) of the light guide, a retarder (13) and specular reflector (15) on the face of the light guide opposite the entrance aperture, an exit aperture (11) orthogonal to the entrance aperture with a reflective polarizer (8) and a beam directing structure (10) over the exit aperture, and a specular reflector (12) on the bottom of the light guide opposite the exit aperture.