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optical data storage

作者： H. Kobori Research and Development Center Toshiba Corporation Kawasaki Japan

At the end of last year, DVD-video players and DVD-ROM drives were put on the market as new optical memories for the multimedia era. Following these read-only DVDs, DVD-RAM is expected to be widely used for storing large amounts of information which will be sent to PCs and TVs through the Internet, CATV channels, satellites, etc. In this paper, we discuss first-generation and future DVD-RAM technologies, in particular, high-density recording technologies. Our concept for the future prospects for DVD-RAM technologies is shown. Basically, future trends in DVD-RAMs are expected to progress in line with those of read-only DVDs, namely DVD-Video, DVD-ROM, and High-Definition DVD (HD-DVD). In order to realize many kinds of multimedia applications using DVDs, it is most important to maintain compatibility with not only current DVDs but also future DVDs.

关键词： DVD Disk recording Personal communication networks Drives Maximum likelihood detection optical recording Diode lasers Research and development Internet Satellite broadcasting

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Holographic data storage with 100 bits//spl mu/m/sup 2/ density

Holographic data storage with 100 bits//spl mu/m/sup 2/ dens...

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optical data storage

作者： A. Pu D. Psaltis Department of Electrical Engineering California Institute of Technology Pasadena CA USA

Holographic data storage offers several advantages when compared to conventional storage devices. As a benchmark, we compare holographic memory with optical compact discs. They are both removable, high capacity, and can be randomly accessed. The next generation compact disc due in early 1997, the Digital-Versatile-Disc (DVD), will have a capacity of /spl sim/6 Gbytes per layer, for a maximum planned capacity of /spl sim/20 Gbytes per double-sided disk with two layers on each side. That translates to a surface density of approximately 20 bits//spl mu/m/sup 2/ for the 4 layered DVD disk. In order for holographic 3-D disks to be competitive, we must demonstrate a much higher surface density than the most advanced DVD. A surface density of 100 bits//spl mu/m/sup 2/ was achieved by storing 590000 pixels in each hologram, over an effective hologram area of 5850 /spl mu/m/sup 2/ (7.8 /spl mu/m horizontal displacement /spl times/.75 mm vertical displacement per hologram). The resulting estimated raw bit-error-rate (BER) was approximately 10/sup -4/ and no errors were observed in the sampled hologram when localized threshold values were used. At 100 bits//spl mu/m/sup 2/, we have a comfortable margin over the projected surface density of the most advanced DVD system. Furthermore, the results obtained from this experiment can be applied to a shift multiplexed holographic 3-D disk system. The capacity per 120 mm disk at 100 bits//spl mu/m/sup 2/ is approximately 100 Gbytes.

关键词： Holography Memory Holographic optical components Displacement control Fourier transforms Bit error rate DVD Optimized production technology Radiofrequency interference Cameras

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Automated pavement distress data collection and analysis: a 3-D approach

Automated pavement distress data collection and analysis: a ...

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International conference on 3D Imaging, Modeling, Processing, Visualization and Transmission (3DIMPVT)

作者： L. Bursanescu F. Blais G. I. E. Technologies Montreal QUE Canada National Research Council of Canada Institute for Information Technology Ottawa ONT Canada

This paper describes a 3-D automated pavement distress data collection and analysis system based on NRC's Biris sensor technology. The paper introduces the problem to be solved, the selected design criteria, and the adopted solution to monitor the quality of road surfaces. The system geometry for the acquisition of the three-dimensional coordinates of pavement surface distresses is presented. Multiple feature extraction and system integration concepts are given with emphasis placed on the real-time processing of the raw data by a parallel array of processors. Advantages and disadvantages of this technology are discussed. System performances and experimental results are provided.

关键词： data analysis Roads data acquisition optical sensors Rough surfaces Surface roughness Surface cracks Councils Information technology Information analysis

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advances in optical imaging of biomedical media

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IMAGING BRAIN STRUCTURE AND FUNCTION: EMERGING TECHNOLOGIES IN THE NEUROSCIENCES 1997年第1期820卷 248-271页

作者： Alfano, RR Demos, SG Gayen, SK Institute for Ultrafast Spectroscopy and Lasers New York State Center for Advanced Technology for Ultrafast Photonic Materials and Applications Physics Department The City College of the City University of New York New York New York 10031

In this article, we have presented an overview of fundamental issues involved in mediphotonic imaging, and reviewed some of the emerging techniques for early-light transillumination imaging of body organs. The results on human breast tissues presented here, together with the data accumulated and advances made by researchers around the globe, not only demonstrate the feasibility of optical imaging as a clinical procedure but indicate a road map to reach that goal. The milestones include evaluation of relative merits of available approaches for a particular imaging application; selection of diagnostic wavelengths, as well as sources to generate and detectors to monitor light at those wavelengths; accumulation of data on optical, spectroscopic, and transport properties of tissues and organs; in vivo testing; prototype instrumentation development; clinical trials; governmental approval; cost analysis and marketing; and finally system improvement based on feedback from end users. A new era of optical clinical imaging is at the door.

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High-speed optical logic

High-speed optical logic

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optical Fiber Communication (OFC) conference

作者： K.L. Hall K.A. Rauschenbach N.S. Patel MIT Lincoln Laboratories Lexington MA USA Massachusetts Institute of Technology Cambridge MA US

ISBN: (纸本)1557524815

All-optical switches and logic gates have been studied for many years, primarily because of their potential for high-speed operation. High-speed operation has been demonstrated in optical AND (demultiplexing) gates. For example, researchers have demonstrated all-optical demultiplexing of 100 Gbit/s data streams using a variety of optical switching elements. Still, all-optical bit-wise logic has not been demonstrated above 40 Gbit/s. However, rapid advances in the demonstrated switching speeds of optical logic gates are expected in the near future.

关键词： High speed optical techniques Logic Nonlinear optics optical interferometry Fiber nonlinear optics optical waveguides optical refraction optical saturation optical solitons optical filters

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Absolute calibration of the AXAF telescope effective area

Absolute calibration of the AXAF telescope effective area

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conference on Grazing Incidence and Multilayer X-ray optical Systems

作者： Kellogg, E Cohen, L Edgar, R Evans, I Freeman, M Gaetz, T Jerius, D McDermott, WC McKinnon, P Murray, S Podgorski, W Schwartz, D VanSpeybroeck, L Wargelin, B Zombeck, M Weisskopf, M Elsner, R ODell, S Tennant, A Kolodziejczak, J Garmire, G Nousek, J Kraft, S Scholze, F Thornagel, R Ulm, G Flanagan, K Dewey, D Bautz, M Texter, S Arenberg, J Carlson, R Harvard-Smithsonian Ctr. for Astrophysics (United States) NASA Marshall Space Flight Ctr. (United States) Universities' Space Research Association (United States) The Pennsylvania State Univ. (United States) Physikalisch-Technische Bundesanstalt (Netherlands) Physikalisch-Technische Bundesanstalt (Germany) Massachusetts Institute of Technology (United States) TRW Inc. (United States)

ISBN: (纸本)0819425354

The prelaunch calibration of AXAF encompasses many aspects of the telescope. In principle, all that is needed is the complete point response function. This is, however, a function of energy, off-axis angle of the source, and operating mode of the facility. No single measurement would yield the entire result. Also, any calibration made prior to launch will be affected by changes in conditions after launch, such as the change from one g to zero g. The reflectivity of the mirror and perhaps even the detectors can change as well, for example by addition or removal of small amounts of material deposited on their surfaces. In this paper, we give a broad view of the issues in performing such a calibration, and discuss how they are being addressed in prelaunch preparation of AXAF;. As our title indicates, we concentrate here on the total throughput of the observatory. This can be thought of as the integral of the point response function, i.e. the encircled energy, out to the largest practical solid angle for an observation. Since there is no standard x-ray source in the sky whose flux is well known to the similar to 1% accuracy we are trying to achieve, we must do this calibration on the ground. We also must provide a means for monitoring any possible changes in this calibration from prelaunch until on-orbit operation can transfer the calibration to a celestial x-ray source whose emission is stable. In the paper, we analyze the elements of the absolute throughput calibration, which we call the Effective Area. We review the requirements for calibrations of components or subsystems of the AXAF facility, including the mirror, detectors, and gratings. We show how it is necessary to have an absolute calibrated detection system available during the prelaunch calibrations to measure the flux in the x-ray beam used for calibrating AXAF. We show how it is necessary to calibrate this ground-based detection system at standard man-made x-ray sources, such as electron storage rings. We

关键词： Calibration Sensors X-rays Quantum efficiency data modeling X-ray sources Error analysis Telescopes Mirrors X-ray telescopes

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Compact lens-less holographic memory

Compact lens-less holographic memory

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optical data storage

作者： E. Chuang J.-J. Drolet G. Barbastathis D. Psaltis Department of Electrical Engineering California Institute of Technology Pasadena CA USA

A common problem of many holographic memory systems is that they must occupy relatively large areas in order to accommodate the various imaging optics necessary for system operation. A typical memory system requires an imaging lens system between the input and output devices, such as a spatial light modulator (SLM) and charge-coupled device (CCD). The memory system we describe here integrates the various system components very closely to the crystal by using a smart pixel array and making use of phase-conjugate read-out to eliminate the need for imaging optics. This significantly reduces the alignment requirements and the number of required components. Our angularly multiplexed integrated read/write memory system is shown. An optoelectronic integrated circuit, which we refer to as the dynamic hologram refresher (DHR), functions as both a spatial light modulator and a detector array. Liquid crystal beam steerers are attached to the two faces of the crystal perpendicular to the signal beam path. These beam steerers address the angularly multiplexed memory. Holograms are recorded by the interference of the signal beam (from the DHR) with the forward reference wave entering the top face of the crystal; when writing holograms, the DHR acts as a spatial light modulator. The counter-propagating reference wave (illuminating the crystal from the bottom) is employed to reconstruct holograms. The reference beam is steered into either the forward or conjugate paths by means of a twisted-nematic liquid crystal (TNLC) device which switches the polarization in the reference arm.

关键词： Holography optical modulation Liquid crystals optical imaging optical arrays DH-HEMTs Holographic optical components Phased arrays Face detection Liquid crystal devices

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Frequency domain estimation of 3-D rigid motion based on range and intensity data

Frequency domain estimation of 3-D rigid motion based on ran...

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International conference on 3D Imaging, Modeling, Processing, Visualization and Transmission (3DIMPVT)

作者： L. Lucchese G. Doretto G.M. Cortelazzo Department of Electronics and Informatics University of Padova Padova Italy

Video-rate registered range and intensity data are at reach of current sensor technology. This wealth of data can be profitably exploited in order to estimate rigid motion parameters as the approaches to 3-D motion estimation, based on the optical flow of both types of data, indicate. This work introduces an alternative for 3-D motion estimation based on the Fourier transform of the 3-D intensity function implicitly described by the registered time-sequences of range and intensity data. The proposed procedure can lead to an unsupervised method for 3-D rigid motion estimation. This method has several advantages related to the fact that it uses the total available information and not sets of features. With respect to memory occupancy the use of a time-sequence of a 3-D intensity function represents a considerable data reduction with respect to a pair of time-sequences of 2-D functions. The proposed technique, which extends to the 3-D case previous frequency domain estimation algorithms developed for the planar case, retain their robustness.

关键词： Frequency domain analysis Frequency estimation Motion estimation Fourier transforms Parameter estimation Robustness Surface texture Solids Informatics optical sensors

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Digital superconductive electronics: where does it fit?

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SUPERCONDUCTOR SCIENCE & technology 1997年第12期10卷 927-928页

作者： Bedard, FD Lab Phys Sci College Pk MD 20740 USA

Superconductivity has been pursuing the world of digital electronics ever since 1956. During all this time its supporters have emphasized the 'obvious' advantages of 'low power' and 'unmatched device speed'. However, still no digital electronics product is in a system;silicon-based digital devices overwhelm all others in the applications world. This is true today, in spite of even faster superconductive devices and circuits as well as greatly reduced power. The major issues that must be faced and resolved in order to insert this immature,technology into the market place are the following. (i) What is the problem for which we are the enabling solution? (ii) Is it important enough to warrant the 'inconvenience' of cryogenics? (iii) Can we make the cryogenics 'transparent' to the user? (iv) Can we interface to the ubiquitous room-temperature electronics? (v) At what size (chip count, MCM count) are we attractive? In spite of the customer reluctance, there are some very important niches which this technology can fit provided that we take lessons from those which support the silicon 'master'. Magnetics (data storage), GaAs (optical communications) and optics (communications, storage) are all examples. These questions of system applications, examples of small-or large-scale uses and the problems to be solved will be discussed together with competing technology alternatives.

关键词： Superconductivity Electronics and devices Condensed matter: electrical magnetic and optical

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Analysis of a single-shot longitudinal bunch profiling system based on an ultra-short pulse Ti:sapphire laser

Analysis of a single-shot longitudinal bunch profiling syste...

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IEEE conference on Particle Accelerator

作者： R. Tatchyn Stanford Synchrotron Radiation Laboratory SLAC National Accelerator Laboratory Stanford CA USA

Recent advances in ultra-short pulse high-power laser technology include the generation of <10 fs pulses at 1 /spl mu/ wavelengths in the multi-terawatt regime. These parameters, coupled with the high per-pulse energy of the new sources, make possible the consideration of longitudinal bunch profiling schemes capable of accurately registering the longitudinal bunch density in a single shot. In this paper we assess the performance and advantages of a longitudinal bunch profiling system based on multi-photon absorption and fluorescence stimulated by the combined bunch and laser fields in a gaseous medium.

关键词： optical pulse generation Gas lasers Synchrotron radiation Particle beams Pulse modulation Absorption Linear particle accelerator storage rings Sampling methods Electrons

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