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Hard X-Ray and Gamma-Ray Detector Physics and Penetrating Radiation Systems ViiI

作者： Matthews ii, Kenneth L. Smith, Blair M. Lackie, Adam W. Hill Jr., William H. Wang, Wei-Hsung Cherry, Michael L. Dept. of Physics and Astronomy Louisiana State University 202 Nicholson Hall Baton Rouge LA 70803-4001 United States Radiation Safety Office Louisiana State University 112 Nuclear Science Baton Rouge LA 70803-5820 United States

ISBN: (纸本)0819463981

We are developing a detector system for locating environmental radiation sources. The design emphasizes compact size (ideally hand-held), wide field of view and high detection efficiency, and uses cadmium-zinc-telluride (CZT) detectors and electronic collimation via Compton-scatter detection. The detector design is a 6-sided box with a primary scatter detector on one end. GEANT4 simulations, allowing variations of detector parameters and source energies/locations, provided performance estimates. A partial prototype, using 16×16-pixel 38×38×5-mm3 CZT detectors, was developed and tested. Two methods to calculate source direction in real-time from the Compton scatter data were evaluated: (1) filtered backprojection of cones onto a sphere;(2) intersection with the sphere of bounding boxes circumscribed around the cones. Simulation results of the 6-sided box with the current CZT modules indicated 1-5% of incident gamma rays produce valid direction angles, with an angular resolution of ∼15°. The directional algorithms allowed a FOV (directional error <10°) of approximately ±60°. The direction algorithms converge on a source direction estimate in as few as 100 detected events. With improvements in detector energy and spatial resolution, reasonable performance seems achievable for a range of radioisotopes, e.g., from Am-241 through Co-60.

关键词： Radiation detectors

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Roles of Bioelectronics for Quality of Life

Roles of Bioelectronics for Quality of Life

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European Conference on Solid-State Circuits (ESSCIRC)

作者： H. Schmidt A. Shakouri M. Isaacson S. M. Kang Baskin School of Engineering University of California Santa Cruz Santa Cruz CA USA

Bioelectronics is an important technology in enhancing the quality of life, especially for those who are suffering from physiological difficulties. Novel biomimetic microelectronic systems will enable treatment of some of presently incurable human handicaps such as hearing loss, blindness (retinal prosthesis), paralysis (neuron-muscular prosthesis), and memory loss (cortical prosthesis). With advancement of bionanotechnology and quantitative medical research, the potential application of biomimetic systems is highly promising. In this paper we review the current status of biomimetic microelectronic systems and challenging issues in basic interface between electrodes and neuronal network, laboratory on a chip (LoC), and generation of power for implantable devices. For laboratory-on-a-chip (LoC), we examine a new way of detecting and sensing molecules on a chip with single molecule/particle sensitivity by fusing integrated optics with microfluidics, based on integrated hollow-core antiresonant reflecting optical waveguides (ARROW) waveguides. With multilayer dielectric confinement, the light is guided through hollow channels with cross sections of a few microns squared. We have demonstrated efficient light guiding in liquid-core ARROWs, single-molecule fluorescence sensitivity in fully planar beam geometry, surface-enhanced Raman scattering, fluorescence from live ribosomes in buffer solution, and electrical fluorescence control by applying a voltage between fluidic reservoirs connected to the waveguide channels. For electrical power sourcing of implantable biomimetic devices and systems, we illustrate the potential of the diffusion potential differences established between two half-cells of electrolyte solutions of different concentrations to generate directly an electric current. This concentration cell operates solely on a salt concentration gradient. The future advancement of biomimetic systems design will critically depend on computer aids as in VLSI developments

关键词： Biomimetics Prosthetics optical waveguides Fluorescence Laboratories Lab-on-a-chip Power generation Integrated optics optical buffering optical waveguide components

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Proceedings of SPIE: current developments in Lens design and optical engineering VI

Proceedings of SPIE: Current Developments in Lens Design and...

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current developments in Lens design and optical engineering VI

The proceedings contain 27 papers. The topics discussed include: using multi-function components to solve optical design challenges for DUV microlithographic applications;automated synthesis of both the topology and numerical parameters for seven patented optical lens systems using genetic programming;advances in lenticular lens arrays for visual display;wide field-of-view imaging system using a liquid crystal spatial light modulator;design tools for freeform optics;designing and specifying aspheres for manufacturability;infrared hybrid optics with high broadband efficiency;removing challenges in microlithographic optical design;laser beam filtering by refractive or diffractive microstructures;and a hybrid athermal CCD camera.

关键词： optical design

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High efficiency amorphous silicon superlattice solar cells

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WSEAS Transactions on Electronics 2006年第5期3卷 281-287页

作者： Varonides, Argyrios C. Department of Phsyics and Electrical Engineering University of Scranton Scranton PA 18510 United States

High efficiency solar cells seem to be the main direction of current research these days, in spite the high cost of fabrication. Production costs of highly effective solar cells are still very high, and thus amorphous silicon is still the only semiconductor material available for cheap and effective solar cells. On the other hand, amorphous silicon-based alloys have not been incorporated sufficiently by the industry, in spite the fact that they might provide advantages of more than one gap and wider optical window for incident wavelengths. Amorphous silicon/alloy superlattices provide advantages in solar cell design, such as (a) effective band-gap widening (b) effective mass separation (c) increased open-circuit voltage. The latter increases via Fermi level control, due to p-doping of potential barriers, pushing EF towards the valence bands, with simultaneous widening of the effective band gap, thus leading to potentially higher collection incident wavelengths. The density of gap states in the heavily doped layer is modeled as an exponential whose parameter kT* can be varied by the doping concentrations, while its activation energy saturates at some value. This communication provides (i) a general formulation of the problem at finite temperatures as well as numerical results for specific realizable contacts (ii) detailed treatment of gap states (iii) the neutrality condition (iv) a relation between Fermi level position and open-circuit voltage in the nitride region (superlattice p-region). For a p-(a-SiN: H/a-Si: H)-i (a-Si: H)-n (a-Si: H) sample, we compute the Fermi level position relative to the a-Si: H valence band edge. For low and wide gap thin layers of the order of 2.5 to 3.5 nm, open circuit voltage values are predicted in excess of 1.05 V, and efficiencies are predicted in excess of 12%.

关键词： Solar cells

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Mechanical fabrication of precision microlenses on optical fiber endfaces

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optical engineering 2005年第12期44卷 123402-1-123402页

作者： Milton, G Gharbia, Y Katupitiya, J Univ New S Wales Sch Mech & Mfg Engn Sydney NSW 2052 Australia

We present a purely mechanical means of producing highly concentric spherical lenses at the endfaces of optical fibers. The production process has two stages. First, conical lenses are produced in a grinding process that ensures excellent concentricity. Then, the conical lenses are transformed to spherical lenses using a novel process called loose abrasive blasting. The cone grinding is carried out on a microgrinding machine, which has a sophisticated control system that enables the production of precision conical lenses. The blasting is carried out on a diamond blasting machine. Plots showing automatic centering performance of the microgrinding machine and scanning electron microscopy images of the conical and spherical lenses are presented. (c) 2005 Society of Photo-optical Instrumentation Engineers.

关键词： microlens optical fiber endface cone grinding

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optical design of the Terrestrial Planet Finder Coronagraph starlight suppression system

Optical design of the Terrestrial Planet Finder Coronagraph ...

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current developments in Lens design and optical engineering VI

作者： Mouroulis, Pantazis Shaklan, Stuart B. Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109

A baseline design for NASA's Terrestrial Planet Finder Coronagraph (TPFC) starlight suppression system (SSS) is described. The design is based on a 8×3.5m elliptical aperture telescope leading to terrestrial planet detection at a minimum angle of ∼4λ/D. The design accommodates classical Lyot coronagraph as well as shaped pupil approaches and includes separate optical paths for two polarizations each with its own deformable mirror control. Critical design challenges and trades are described.

关键词： optical design

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optical design considerations for the Terrestrial Planet Finder - Coronagraph Mission: optical telescope assembly

Optical design considerations for the Terrestrial Planet Fin...

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current developments in Lens design and optical engineering VI

作者： Howard, Joseph M. Mouroulis, Pantazis Thompson, Anita Smith, Andrew Content, David Ho, Timothy Jackson, Clifton Ohl, Raymond G. Shaklan, Stuart B. NASA Goddard Space Flight Center Greenbelt MD NASA Jet Propulsion Laboratory Pasadena CA Swales Aerospace Beltsville MD

The Terrestrial Planet Finder-Coronagraph (TPF-C) is a NASA exploration mission to directly detect and characterize terrestrial exoplanets at visible wavelengths. The TPF-C observatory must be able to distinguish a planet that is more than 10 orders of magnitude fainter than its parent star at a separation of 75 milli-arc-seconds (mas). Coronagraphic detection requires a large aperture telescope to resolve the exoplanet from its star, and extreme stability during detection and characterization observations. This paper discusses the requirements and trade studies leading to the current baseline optical design for the TPF-C telescope. The current baseline design is summarized and its prescription is presented.

关键词： optical design

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Remaining challenges in microlithographic optical design

Remaining challenges in microlithographic optical design

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current developments in Lens design and optical engineering VI

作者： Williamson, David M. Nikon Research Corporation of America 12490 N. Rancho Vistoso Blvd. Tucson AZ 85737 United States

Rayleigh scaling equations for resolution and the control of computer chip critical dimensions (CD) within a finite depth of focus (DOF) have always indicated that resolution is better improved by reductions in wavelength of exposure light rather than by increasing the numerical aperture (NA) of the projection optics, particularly as it approaches the physical limit in air of 1.0. However, liquid immersion of the image increases the physical NA limits and presents new optical design challenges, while postponing the necessity for drastic reductions in the wavelength.

关键词： optical design

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Mechanical fabrication of precision microlenses on optical fiber endfaces

Mechanical fabrication of precision microlenses on optical f...

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Conference on current developments in Lens design and optical engineering V

作者： Milton, G Gharbia, Y Katupitiya, J Univ New S Wales Sch Mech & Mfg Engn Sydney NSW 2052 Australia

ISBN: (纸本)0819454613

关键词： microlens optical fiber endface cone grinding

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optical design of liquid crystal lenses: Off-axis modelling

Optical design of liquid crystal lenses: Off-axis modelling

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current developments in Lens design and optical engineering VI

作者： Kirby, A.K. Hands, P.J.W. Love, G.D. Durham University Dept. of Physics Durham DH1 3LE United Kingdom

We report on our work on producing liquid crystal switchable modal lenses and their use in a compound lens system in order to produce variable focus/zoom lenses. We describe work on producing a high power lens, and present theoretical work on off-axis phase modulation in a liquid crystal lens which is important in order to be able to carry out a complete optical design of a liquid crystal lens.

关键词： Liquid crystal displays

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