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Conference on current developments in Lens design and optical engineering XI - and Advances in Thin Film Coatings VI

作者： Valley, Pouria Dodge, Mohammad Reza Schwiegerling, Jim Mathine, David Peyman, Gholam Peyghambarian, N. Univ Arizona Coll Opt Sci Tucson AZ 85721 USA

ISBN: (纸本)9780819482822

Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and/or liquid crystal lenses were previously proposed(1-4). Here we present tunable-focus flat liquid crystal diffractive lenses (LCDL) employing binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The phase levels can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2 pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = r(m)(2)/2m lambda, where r(m) is m(th) zone radius, and lambda is the wavelength. The lenses operate at very low voltage levels (+/- 2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (> 10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. The promising results make LCDL a good candidate for non-mechanical auto-focus and zoom lenses.

关键词： Diffractive lenses Liquid-crystal devices Active or adaptive optics Non-mechanical optical zoom Auto-focus Telescopes

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GRAVITY: design and performances of the fringe tracker

GRAVITY: Design and performances of the fringe tracker

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Conference on optical and Infrared Interferometry ii

作者： Choquet, E. Cassaing, F. Perrin, G. Eisenhauer, F. Brandner, W. Straubmeier, C. Perraut, K. Gillessen, S. Observ Paris LESIA 5 Pl Jules Janssen F-92195 Meudon France Off Natl Etud & Rech Aerosp DOTA F-92322 Chatillon France Max Planck Inst Extraterr Phys D-85748 Garching Germany Max Planck Inst Astron D-69117 Heidelberg Germany Univ Cologne Inst Phys 1 D-50937 Cologne Germany Observ Grenoble Astrophys Lab F-38041 Grenoble 9 France Univ Paris Diderot CNRS Observ Paris Groupement Interet Sci PHASE ONERA Paris France

ISBN: (纸本)9780819482242

GRAVITY is a second generation instrument for the VLTI. It will combine four telescope in the K band and perform fringe tracking on stars as faint as 10 magnitude with a lambda/8 accuracy, thus counterbalancing atmospheric piston and UTs longitudinal vibrations, despite, flux drop-outs due to residual tip-tilt jitter. To achieve such a performance, new developments have to be tested. We have developed a complete simulator so as to improve algorithms and establish an efficient fringe tracking strategy. In addition, a prototype of the fringe tracker for GRAVITY is being built up in order to demonstrate the results of this simulator. We present here the current status of these developments, achieved by simulating realistic tracking at VLTI.

关键词： Interferometry VLTI GRAVITY Fringe tracking Group delay Phase delay

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SEOP program for neutron spin filters at the Jülich Centre for Neutron Science

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Journal of Physics: Conference Series 2011年第1期294卷

作者： E Babcock A Ioffe Jülich Centre for Neutron Science at FRM II Institut für Festkörperforshung Forschungszentrum Jülich GmbH 85747 Garching Germany

The Jülich Centre for Neutron Science is developing spin-exchange optical pumping systems capable of polarizing the 3He gas for use as neutron spin filters with developments focused on individually optimized solutions for each application. When possible steady polarization achieved with in-situ optical pumping will provide high time averaged neutron performance and time-stability, however some applications are foreseen to use a 'local filling station' approach. In-situ polarizers are being developed for polarization analysis on reflectometry and small angle neutron scattering instruments. This overview of the current status of our SEOP program describes the motivation of in-situ polarization, the design and first results from the polarizer for analysis on reflectometry, and discusses the designs for a SANS analyzer and plans for wide angle analysis.

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design and implementation of HDL modules and circuits for underwater optical wireless communication

Design and implementation of HDL modules and circuits for un...

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作者： Anguita, Davide Brizzolara, Davide Parodi, Giancarlo University of Genova Department of Biophysical and Electronic Engineering Via Opera Pia 11A Genova Italy

ISBN: (纸本)9789549260021

关键词： optical communication

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Proceedings of SPIE - The International Society for optical engineering: Introduction

Proceedings of SPIE - The International Society for Optical ...

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Proceedings of SPIE - The International Society for optical engineering 2010年 7786卷 ix-xii页

作者： Johnson, R. Barry Mahajan, Virendra N. Thibault, Simon

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Flat-panel electronic displays: a triumph of physics, chemistry and engineering

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PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND engineering SCIENCES 2010年第1914期368卷 1027-1082页

作者： Hilsum, Cyril UCL London England

This paper describes the history and science behind the development of modern flat-panel displays, and assesses future trends. Electronic displays are an important feature of modern life. For many years the cathode ray tube, an engineering marvel, was universal, but its shape was cumbersome and its operating voltage too high. The need for a flat-panel display, working at a low voltage, became imperative, and much research has been applied to this need. Any versatile flat-panel display will exploit an electro-optical effect, a transparent conductor and an addressing system to deliver data locally. The first need is to convert an electrical signal into a visible change. Two methods are available, the first giving emission of light, the second modulating ambient illumination. The most useful light-emitting media are semiconductors, historically exploiting iiI-V or ii-VI compounds, but more recently organic or polymer semiconductors. Another possible effect uses gas plasma discharges. The modulating, or subtractive, effects that have been studied include liquid crystals, electrophoresis, electrowetting and electrochromism. A transparent conductor makes it possible to apply a voltage to an extended area while observing the results. The design is a compromise, since the free electrons that carry current also absorb light. The first materials used were metals, but some semiconductors, when heavily doped, give a better balance, with high transmission for a low resistance. Delivering data unambiguously to a million or so picture elements across the display area is no easy task. The preferred solution is an amorphous silicon thin-film transistor deposited at each cross-point in an X-Y matrix. Success in these endeavours has led to many applications for flat-panel displays, including television, flexible displays, electronic paper, electronic books and advertising signs.

关键词： displays cathode ray tube liquid crystals

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VHDL modules and circuits for Underwater optical wireless communication systems

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WSEAS Transactions on Communications 2010年第9期9卷 525-552页

作者： Anguita, Davide Brizzolara, Davide Parodi, Giancarlo University of Genova Department of Biophysical and Electronic Engineering Via Opera Pia 11A Genova Italy

Underwater wireless optical communication has been used for establish a link between mobile vehicles and/or fixed nodes because light, especially in the blue/green region, allows to achieve higher data-rate than acoustical or electromagnetic waves for moderate distances. The here proposed work has the aim to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network of dense-deployed fixed nodes for specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. In particular, taking into account already developed protocols for optical wireless communication, the focus is on the hardware implementation of different flexible modules to support both point-to-point and directional communication targeting the use of these technologies in the field of Underwater Wireless Sensor Network and the integration with current terrestrial technologies for Wireless Sensor Network. After a careful analysis of benefits and problems related to optical transmission underwater, design considerations are proposed with the description of the implemented modules. The use of light impulse for communication is motivated by the possibility of targeting high data-rate, low-cost and small dimension components. This paper describes an overall vision of the system: a HDL implementation of flexible modules for the management of optical communication (based on IEEE 802.15.4 and IEEE 802.11 standard) which target the interface with current terrestrial technology for Wireless Sensor Networks;the design and implementation of circuits for underwater optical point-to-point and planar communication. The preliminary results and design consideration are reported considering also future possible developments.

关键词： optical communication

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In situ ellipsometric monitoring of complex multilayer designs

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中国光学快报（英文版） 2010年第S1期8卷 44页

作者： Svetlana Dligatch Commonwealth Scientific and Industrial Research Organisation Materials Science and Engineering PO Box 218 Lindf ield NSW 2070 Australia

current developments in optical multilayer design and computation make it possible to calculate filters that satisfy the most demanding optical specifications. Some of the designs are highly sensitive to manufacturing errors and require accurate monitoring and control during thin film deposition. Ellipsometric monitoring enables the accurate deposition of any thickness, including very thin layers, and in situ measurement of both refractive index and thickness of the layers during deposition, which facilitate the subsequent real-time design reoptimisation. In this letter, a number of complex multilayer designs with the aid of ellipsometric monitoring are presented, including a laser notch plus band-blocker filter, dichroic filter, beamsplitter, and a wide-range broadband multiplayer antireflection coating.

关键词： 240.2130 光学监测椭圆偏光法 310.1860 120.2130 光学薄膜多层滤光片

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optical wireless communication for underwater Wireless Sensor Networks: Hardware modules and circuits design and implementation

Optical wireless communication for underwater Wireless Senso...

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OCEANS

作者： Davide Anguita Davide Brizzolara Giancarlo Parodi DIBE-Department of Biophysical and Electronic Engineering University of Genoa Genoa Italy

Underwater wireless optical communication has been used for establish a link between mobile vehicles and/or fixed nodes because light, especially in the blue/green region, allows to achieve higher data-rate than acoustical or electromagnetic waves for moderate distances. The here proposed work has the aim to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network of dense-deployed fixed nodes for specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. In particular our research explores the possibility of targeting the interface with current available terrestrial technologies. The use of light impulse for communication is motivated by the possibility of targeting high data-rate, low-cost and small dimension components. This paper describes an overall vision of the system: a HDL implementation of flexible modules for the management of optical communication (based on IEEE 802.15.4 and IEEE 802.11 standard) which target the interface with current terrestrial technology for Wireless Sensor Networks; the design and implementation of circuits for underwater optical point-to-point and planar communication. The preliminary results and design consideration are reported considering also future possible developments.

关键词： Wireless sensor networks optical fiber communication Hardware High speed optical techniques optical sensors optical scattering optical attenuators

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current developments in Lens design and optical engineering X

Current Developments in Lens Design and Optical Engineering ...

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current developments in Lens design and optical engineering X

ISBN: (纸本)9780819477187

The proceedings contain 22 papers. The topics discussed include: optical design dependence on technology development;practical design considerations for modern photographic optics;display systems and registration methods for mixed reality applications;efficient design process for the evaluation and control of flare in opto-mechanical systems;finding order in the design landscape of simple optical systems;design and optimization of a collimating optical system for high divergence LED light sources;point symmetric design approach to a wide-field wide-wavelength cat's eye retro-reflector anastigmat;fast catadioptric optics with large field of view;thinking outside the barrel: what really matters in modern photographic lens design;calculation of optical forces on a dielectric bead in a geometrically aberrated trap;and relationships between lens performance and different sensor sizes in professional photographic still SLR cameras.

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