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International conference on Solid-State Sensors, Actuators and Microsystems

作者： M.E. Swanwick P. D. Keathley F. X Kartner L. F. velasquez-Garcia Microsystems Technology Laboratories Massachusetts Institute of Technology Dept. of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology

ISBN: (纸本)9781467359825

We report the design, fabrication, and experimental characterization of a novel ultrafast optical field emission cathode comprised of a large and dense array of nanosharp high-aspect-ratio single-crystal silicon columns (>100,000 tips, 4.6-million ***~(-2)). The cathode emits electrons with as little as 25 nJ and can produce up to 2.54 pC electron bunches per laser pulse when interacting with 35 fs 800 nm laser pulses with a 765 μm by 80 μm elliptical spot size. This is the first report of current measurements from Si tip arrays using photo-field emission;in addition, this is the first demonstration of a photocathode array that, depending on the energy of the laser pulses, can emit in the multi-photon or the tunnelling regime.

关键词： Coherent x-rays field emission MEMS multiplexed photo-emission ultrafast optics

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Eliminating Dewar Narcissus artifacts induced by moving optics in infrared staring focal plane sensors

Eliminating Dewar Narcissus artifacts induced by moving opti...

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conference on current developments in Lens design and optical engineering XIII

作者： McCulloch, Philip M. Olson, Craig Goodman, Timothy D. L3 Commun Sonoma EO Santa Rosa CA 95403 USA

ISBN: (纸本)9780819492036

Staring infrared imagers have multiple surfaces within the integrated Dewar assembly which contribute to non-traditional Narcissus artifacts. Static non-uniformity correction is insufficient to remove dynamic Narcissus artifacts caused by moving focus or zoom groups. Dynamic Narcissus artifacts often manifest as rings apparent to the human eye, although they may lie near the noise floor of the imager. Moreover, strong field curvature of the Narcissus can complicate diagnosis using paraxial methods. We compare a simple pupil ghost metric to traditional Narcissus metrics and present an experimental case study illustrating how the metric can be used during optimization to eliminate the effect.

关键词： optical design Narcissus staring array infrared optics YNI i/ibar

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design of Large Aperture Four Group Elements Mid-wave Infrared Zoom Lens

Design of Large Aperture Four Group Elements Mid-wave Infrar...

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conference on current developments in Lens design and optical engineering XIII

作者： Ji Yiqun Shi Rongbao He Hucheng Shen Weimin Soochow Univ Inst Modern Opt Technol Key Lab Adv Opt Mfg Technol Jiangsu Prov Suzhou 215006 Jiangsu Peoples R China

ISBN: (纸本)9780819492036

Zoom lens with variable focal length is well fit for researching objectives far and near. design of zoom lens working at mid-wave infrared wavelength (7.7-10.3 m) and its view field 10 degrees is presented. Determination of the initial configuration of the variable and the compensate groups are discussed according to the mechanism compensate curves. The compensate group is determined with positive power. Its focal length changes during a large scope, which is from 300mm to 100mm. And the corresponding F number variables from 3.75 to 1.25. So the residual aberration needs to be carefully corrected. The optimized zoom lens is composed of four group elements, and its performance reaches diffraction limited at each focal position.

关键词： optical design mid-wave infrared zoom lens four group elements mechanical compensate curve large aperture

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design and development of bi-directional viewer

Design and development of bi-directional Viewer

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conference on current developments in Lens design and optical engineering XIII

作者： Yu, Zong-Ru Ho, Cheng-Fang Liu, Annie Lee, Tai-Wen Lin, Wen-Lung Hsu, Wei-Yao Natl Appl Res Labs Instrument Technol Res Ctr Hsinchu 300 Taiwan

ISBN: (纸本)9780819492036

Bi-directional viewer just likes a lens of camera. Unlike conventional camera lens, the bi-directional viewer captures not only front view but also side view around the bi-directional viewer. The barrel of bi-directional viewer was designed to have cuts in the side to allow side light to come through, and we use two aspherical mirrors to receive and change the side light to converge on the main optical path. The front view and side view can be imaged simultaneously on an image sensor. Commercial aspherized achromatic lens and micro video lens were also used to keep the image quality and miniaturize the size of the bi-directional viewer respectively. We report on the development of bi-directional viewer, including optical design, optical simulation, optomechanics design, fabrication techniques, assembly procedure and performance testing. The MTF of the bi-directional viewer is also measured and discussed in this paper. We successfully design and realize a bi-directional viewer, which can perform 100 lp/mm spatial frequency image in detail above 20% contrast in the 7.6 mm front view area. And we keep the dimensions of this device within 35 mm in total length and phi 20 mm in diameter.

关键词： Bi-directional viewer Side view MTF Catadioptric Dual-view

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Nanotools for Neuroscience and Brain Activity Mapping

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ACS NANO 2013年第3期7卷 1850-1866页

作者： Alivisatos, A. Paul Andrews, Anne M. Boyden, Edward S. Chun, Miyoung Church, George M. Deisseroth, Karl Donoghue, John P. Fraser, Scott E. Lippincott-Schwartz, Jennifer Looger, Loren L. Masmanidis, Sotiris McEuen, Paul L. Nurmikko, Arto v. Park, Hongkun Peterka, Darcy S. Reid, Clay Roukes, Michael L. Scherer, Axel Schnitzer, Mark Sejnowski, Terrence J. Shepard, Kenneth L. Tsao, Doris Turrigiano, Gina Weiss, Paul S. Xu, Chris Yuste, Rafael Zhuang, Xiaowei Univ Calif Berkeley Dept Chem Berkeley CA 94720 USA Univ Calif Berkeley Lawrence Berkeley Natl Lab Berkeley CA 94720 USA Univ Calif Los Angeles Calif NanoSyst Inst Los Angeles CA 90095 USA Univ Calif Los Angeles Dept Psychiat Los Angeles CA 90095 USA Univ Calif Los Angeles Semel Inst Neurosci & Human Behav Dept Chem & Biochem Los Angeles CA 90095 USA MIT Dept Biol Engn Brain & Cognit Sci Media Lab Cambridge MA 02139 USA MIT McGovern Inst Cambridge MA 02139 USA Kavli Fdn Oxnard CA 93030 USA Harvard Univ Sch Med Dept Genet Boston MA 02115 USA Harvard Univ Wyss Inst Biol Inspired Engn Boston MA 02115 USA Harvard Univ Biophys Program Boston MA 02115 USA Stanford Univ Howard Hughes Med Inst Stanford CA 94305 USA Stanford Univ Dept Bioengn Stanford CA 94305 USA Stanford Univ Dept Psychiat Stanford CA 94305 USA Brown Univ Dept Comp Sci Div Engn Dept Neurosci Providence RI 02912 USA Univ So Calif Dept Biol Sci Los Angeles CA 90089 USA Univ So Calif Dept Biomed Engn Los Angeles CA 90089 USA Univ So Calif Dept Physiol & Biophys Los Angeles CA 90089 USA Univ So Calif Dept Stem Cell Biol & Regenerat Med Los Angeles CA 90089 USA Univ So Calif Dept Pediat Radiol & Ophthalmol Los Angeles CA 90089 USA Eunice Kennedy Shriver Natl Inst Child Hlth & Hum Cell Biol & Metab Program NIH Bethesda MD 20892 USA Howard Hughes Med Inst Ashburn VA 20147 USA Univ Calif Los Angeles Dept Neurobiol Los Angeles CA 90095 USA Cornell Univ Dept Phys Lab Atom & Solid State Phys Ithaca NY 14853 USA Cornell Univ Kavli Inst Cornell Nanoscale Sci Ithaca NY 14853 USA Brown Univ Dept Phys Providence RI 02912 USA Brown Univ Div Engn Providence RI 02912 USA Harvard Univ Dept Chem & Chem Biol Cambridge MA 02138 USA Harvard Univ Dept Phys Cambridge MA 02138 USA Columbia Univ Howard Hughes Med Inst New York NY 10027 USA Columbia Univ Dept Biol Sci New York NY 10027 USA Allen Inst Brain Sci Seattle WA 98103 USA CALTECH Kavli Nanosci Inst Pasadena CA 91125 USA C

Neuroscience is at a crossroads. Great effort is being invested into deciphering specific neural interactions and circuits. At the same time, there exist few general theories or principles that explain brain function. We attribute this disparity, in part, to limitations In current methodologies. Traditional neurophysiological approaches record the activities of one neuron or a few neurons at a time. Neurochemical approaches focus on single neurotransmitters. Yet, there Is an increasing realization that neural circuits operate at emergent levels, where the interactions between hundreds or thousands of neurons, utilizing multiple chemical transmitters, generate functional states. Brains function at the nanoscale, so tools to study brains must ultimately operate at this scale, as well. Nanoscience and nanotechnology are poised to provide a rich toolkit of novel methods to explore brain function by enabling simultaneous measurement and manipulation of activity of thousands or even millions of neurons. We and others refer to this goal as the Brain Activity Mapping Project. In this Nano Focus, we discuss how recent developments in nanoscale analysis tools and In the design and synthesis of nanomaterials have generated optical, electrical, and chemical methods that can readily be adapted for use in neuroscience. These approaches represent exciting areas of technical development and research. Moreover, unique opportunities exist for nanoscientists, nanotechnologists, and other physical scientists and engineers to contribute to tackling the challenging problems involved in understanding the fundamentals of brain function.

关键词： Central nervous system Circuits Electrodes Light Nanoscale

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Investigation of the optical and Structural Properties of WO₃ Thin Films with Different Sputtering Power Supplies

Investigation of the Optical and Structural Properties of WO...

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conference on current developments in Lens design and optical engineering XIII

作者： Chen, Hsi-Chao Jan, Der-Jun Chen, Chien-Han Huang, Kuo-Ting Luo, Yu-Siang Chen, Jia-Min Natl Yunlin Univ Sci & Technol Grad Sch Optoelect Yunlin 64002 Taiwan

ISBN: (纸本)9780819492036

The purpose of this research was to investigate the optical and structural properties of tungsten oxide (WO3) thin films deposited with three different sputtering power supplies: direct current (DC), DC pulse and radio frequency (RF). These WO3 thin films were deposited on ITO glass and silicon substrate with different gas ratios of oxygen and argon (O-2/Ar ratio). WO3 thin film is the role of the electrochromic window was resulted from the advantages of large variation in optical density, high response efficiency, no toxicity and low cost. The experimental results showed that optical intensity increased with the increasing of O-2/Ar ratio and all films have the 950cm(-1) peak which the bonding of W+6=O in Raman spectra. Hence, the O-2/Ar ratio was changed from 0.4 to 0.8 to study the ability of coloring and bleaching for the three different power supplies. Anyways, the WO3 thin films had the best electrochromic property at the O-2/Ar ratio of 0.7, 0.6 and 0.6 for DC, DC pulse, and RF, respectively. The transmittances could be over 75% for all films at as-deposited and the deposition rates were between 0.8 and 0.1 angstrom s(-1). Simultaneously, the transmittance variations (Delta T) were 51%, 57% and 53% for DC, DC pulse, and RF power sources at wavelength of 550 nm, respectively. The coloration ability of WO3 thin film deposition with power supply of DC pulse was better than that of the DC and RF.

关键词： Tungsten oxide (WO3) direct current (DC) magnetron sputtering pulsed DC sputtering radio frequency (RF) sputtering Raman spectra

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design and fabrication of the near-ultraviolet birefringent Solc filter for the NASA IRIS solar physics mission

Design and fabrication of the near-ultraviolet birefringent ...

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conference on current developments in Lens design and optical engineering XIII

作者： Berger, Thomas Mudge, Jason Holmes, Buck Searcy, Paul Wuelser, Jean-Pierre Lemen, James Title, Alan Adv Technol Ctr Palo Alto CA 94304 USA

ISBN: (纸本)9780819492036

The NASA Interface Region Imaging Spectrograph (IRIS) mission is a Small Explorer (SMEX) satellite mission designed to study plasma dynamics in the "interface region" between the Sun's chromosphere and corona with high spatial, spectral, and temporal resolution. The primary instrument is a dual Czerny-Turner spectrograph fed by a 20-cm Cassegrain telescope measuring near-and far-ultraviolet (NUv, FUv) spectral lines in the ranges 133-141 nm and 278-283 nm. To determine the position of the slit on the solar disk, a slit-jaw imaging system is used. The NUv slit-jaw imaging system produces high spatial resolution images at two positions in the Mg II 280 nm spectral line complex using a birefringent Solc filter with two wide-band interference pre-filters for spectral order selection. The Solc filter produces a 0.36 nm full-width at half-maximum (FWHM) filter profile with low sidelobes and a peak transmission of 15% at 279.6 nm. The filter consists of two "wire grid'' polarizers surrounding 8 quartz waveplates configured in a modified Solc "fan" rotational pattern. The elements are optically coupled using DC200 silicon-based grease. The NUv Solc filter is sealed in a windowed cell to prevent silicon contamination of the FUv channel. The design of the sealed cell and assembly of the filter into the cell were among the most challenging optomechanical aspects of the IRIS spectrograph system.

关键词： Optics imaging birefringent filter near-ultraviolet far-ultraviolet satellite systems solar spectrum

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Electron over-barrier emission mechanism of single layer graphene

Electron over-barrier emission mechanism of single layer gra...

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IEEE International vacuum Electronics conference

作者： Shijun Liang L. K. Ang Engineering Produce Development Singapore University of Technology and Design Singapore 138682

ISBN: (纸本)9781467359764

We propose a model which describes the side-band electrons emission from a vertically aligned monolayer graphene with an internal time-oscillating barrier and static surface barrier. Our results show that electron emission is governed by the over-barrier emission process, where the emitting current line density J [nA/nm] is only dependent on the amplitude v_1 and frequency ω of the oscillating barrier, which is characterized by 0< γ= v_1/hω<1. It is found that J is maximized around the optical frequency at ω= 10~(14) to 10~(15) rad/s, and J is higher for larger γ.

关键词： over-barrier emission graphene

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Comparison of Peak-To-Peak current Ripple Amplitude in Multiphase PWM voltage Source Inverters

Comparison of Peak-To-Peak Current Ripple Amplitude in Multi...

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European conference on Power Electronics and Applications

作者： Gabriele Grandi Jelena Loncarski Claudio Rossi Dept. of Electrical Engineering University of Bologna

ISBN: (纸本)9781479901159

Multiphase systems are nowadays considered for various industrial applications. Numerous PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but just recently the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been considered. Determination of current ripple in multiphase PWM voltage source inverters is important for both design and control purposes. This paper gives the comparison of the peak-to-peak current ripple distribution over a fundamental period for multiphase vSIs, starting from three-phase and extended to the multiphase inverters, with emphasis on five and seven phases. Simplified expressions to get maximum value of the ripple are carried out and compared among inverters with different phase number. Although reference is made to the centered symmetrical PWM, being the most simple and effective solution to maximize the dc bus utilization, leading to a nearly-optimal modulation to minimize the rms of the current ripple, the analysis can be readily extended to either discontinuous or asymmetrical modulations, both carrier-based and space vector PWM. The results obtained by the proposed analytical approach are backed with the numerical simulations of the peak-to-peak ripple for inverters with different phase numbers and in case of different modulation indexes to prove the effectiveness of mathematical developments.

关键词： DC-AC power conversion Inverters current distribution Distortion Pulse width modulation

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Recent developments in computer supported cooperative work in design: From group collaboration through global connectivity to informing apobetics

Recent developments in computer supported cooperative work i...

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2012 IEEE 16th International conference on Computer Supported Cooperative Work in design, CSCWD 2012

作者： Horváth, Imre Faculty of Industrial Design Engineering Delft University of Technology Delft Netherlands

ISBN: (纸本)9781467312127

This paper surveys the recent developments and future research opportunities in computer supported cooperative work in design. This domain of interest has been variously conceptualized and described in different publications. There is a broader interpretation that considers the entirety of product lifecycle as a target domain and aims at a holistic optimization of all related engineering processes by connecting them through design. There exists a narrower interpretation that concentrates on the enhancement of the product conceptualization and creative design activities in distributed, multidisciplinary and volatile environments. The former is most frequently referred to as collaborative engineering and the latter as collaborative design. The paper concentrates on collaborative design and investigates the concepts, advancements and issues from: (i) philosophical and theoretical, (ii) technological and infrastructural, (iii) organizational and methodological, (iv) social and cultural, (v) cognitive and behavioral perspectives. Based on literature sources and the own work of the author in the last three decades, it provides a broadly-based analysis of the related concepts, knowledge, means, systems and concerns in current research, development and application with the objective to point towards future progression opportunities. The paper identifies a gradual shift in the research interest from the technological and procedural aspects to the socio-cultural, inter-personal and informational aspects. It proposes that collaborative design is eventually about people and that mobile, ubiquitous and smart technologies create many new opportunities for conducting collaborative design. Semantics, pragmatics and apobetics of inter-personal interaction and communication play a key role in the success of collaborative design. © 2012 IEEE.

关键词： Semantics

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