WorldWideScience

Sample records for range optical distance

  1. An optical distance sensor : tilt robust differential confocal measurement with mm range and nm uncertainty

    NARCIS (Netherlands)

    Cacace, L.A.

    2009-01-01

    Compared with conventional high-end optical systems, application of freeform optics offers many advantages. Their widespread use, however, is held back by the lack of a suitable measurement method.The NANOMEFOS project aims at realizing a universal freeform measurement machine to fill that void.The

  2. Research on volume metrology method of large vertical energy storage tank based on internal electro-optical distance-ranging method

    Science.gov (United States)

    Hao, Huadong; Shi, Haolei; Yi, Pengju; Liu, Ying; Li, Cunjun; Li, Shuguang

    2018-01-01

    A Volume Metrology method based on Internal Electro-optical Distance-ranging method is established for large vertical energy storage tank. After analyzing the vertical tank volume calculation mathematical model, the key processing algorithms, such as gross error elimination, filtering, streamline, and radius calculation are studied for the point cloud data. The corresponding volume values are automatically calculated in the different liquids by calculating the cross-sectional area along the horizontal direction and integrating from vertical direction. To design the comparison system, a vertical tank which the nominal capacity is 20,000 m3 is selected as the research object, and there are shown that the method has good repeatability and reproducibility. Through using the conventional capacity measurement method as reference, the relative deviation of calculated volume is less than 0.1%, meeting the measurement requirements. And the feasibility and effectiveness are demonstrated.

  3. Machine learning enhanced optical distance sensor

    Science.gov (United States)

    Amin, M. Junaid; Riza, N. A.

    2018-01-01

    Presented for the first time is a machine learning enhanced optical distance sensor. The distance sensor is based on our previously demonstrated distance measurement technique that uses an Electronically Controlled Variable Focus Lens (ECVFL) with a laser source to illuminate a target plane with a controlled optical beam spot. This spot with varying spot sizes is viewed by an off-axis camera and the spot size data is processed to compute the distance. In particular, proposed and demonstrated in this paper is the use of a regularized polynomial regression based supervised machine learning algorithm to enhance the accuracy of the operational sensor. The algorithm uses the acquired features and corresponding labels that are the actual target distance values to train a machine learning model. The optimized training model is trained over a 1000 mm (or 1 m) experimental target distance range. Using the machine learning algorithm produces a training set and testing set distance measurement errors of learning. Applications for the proposed sensor include industrial scenario distance sensing where target material specific training models can be generated to realize low <1% measurement error distance measurements.

  4. A Short-Range Distance Sensor with Exceptional Linearity

    Science.gov (United States)

    Simmons, Steven; Youngquist, Robert

    2013-01-01

    A sensor has been demonstrated that can measure distance over a total range of about 300 microns to an accuracy of about 0.1 nm (resolution of about 0.01 nm). This represents an exceptionally large dynamic range of operation - over 1,000,000. The sensor is optical in nature, and requires the attachment of a mirror to the object whose distance is being measured. This work resulted from actively developing a white light interferometric system to be used to measure the depths of defects in the Space Shuttle Orbiter windows. The concept was then applied to measuring distance. The concept later expanded to include spectrometer calibration. In summary, broadband (i.e., white) light is launched into a Michelson interferometer, one mirror of which is fixed and one of which is attached to the object whose distance is to be measured. The light emerging from the interferometer has traveled one of two distances: either the distance to the fixed mirror and back, or the distance to the moving mirror and back. These two light beams mix and produce an interference pattern where some wavelengths interfere constructively and some destructively. Sending this light into a spectrometer allows this interference pattern to be analyzed, yielding the net distance difference between the two paths. The unique feature of this distance sensor is its ability to measure accurately distance over a dynamic range of more than one million, the ratio of its range (about 300 microns) to its accuracy (about 0.1 nanometer). Such a large linear operating range is rare and arises here because both amplitude and phase-matching algorithms contribute to the performance. The sensor is limited by the need to attach a mirror of some kind to the object being tracked, and by the fairly small total range, but the exceptional dynamic range should make it of interest.

  5. Distance Ranging Based on Quantum Entanglement

    International Nuclear Information System (INIS)

    Xiao Jun-Jun; Han Xiao-Chun; Zeng Gui-Hua; Fang Chen; Zhao Jian-Kang

    2013-01-01

    In the quantum metrology, applications of quantum techniques based on entanglement bring in some better performances than conventional approaches. We experimentally investigate an application of entanglement in accurate ranging based on the second-order coherence in the time domain. By a fitting algorithm in the data processing, the optimization results show a precision of ±200 μm at a distance of 1043.3m. In addition, the influence of jamming noise on the ranging scheme is studied. With some different fitting parameters, the result shows that the proposed scheme has a powerful anti-jamming capability for white noise

  6. Ultrafast optical ranging using microresonator soliton frequency combs

    Science.gov (United States)

    Trocha, P.; Karpov, M.; Ganin, D.; Pfeiffer, M. H. P.; Kordts, A.; Wolf, S.; Krockenberger, J.; Marin-Palomo, P.; Weimann, C.; Randel, S.; Freude, W.; Kippenberg, T. J.; Koos, C.

    2018-02-01

    Light detection and ranging is widely used in science and industry. Over the past decade, optical frequency combs were shown to offer advantages in optical ranging, enabling fast distance acquisition with high accuracy. Driven by emerging high-volume applications such as industrial sensing, drone navigation, or autonomous driving, there is now a growing demand for compact ranging systems. Here, we show that soliton Kerr comb generation in integrated silicon nitride microresonators provides a route to high-performance chip-scale ranging systems. We demonstrate dual-comb distance measurements with Allan deviations down to 12 nanometers at averaging times of 13 microseconds along with ultrafast ranging at acquisition rates of 100 megahertz, allowing for in-flight sampling of gun projectiles moving at 150 meters per second. Combining integrated soliton-comb ranging systems with chip-scale nanophotonic phased arrays could enable compact ultrafast ranging systems for emerging mass applications.

  7. Scanning optical microscope with long working distance objective

    Science.gov (United States)

    Cloutier, Sylvain G.

    2010-10-19

    A scanning optical microscope, including: a light source to generate a beam of probe light; collimation optics to substantially collimate the probe beam; a probe-result beamsplitter; a long working-distance, infinity-corrected objective; scanning means to scan a beam spot of the focused probe beam on or within a sample; relay optics; and a detector. The collimation optics are disposed in the probe beam. The probe-result beamsplitter is arranged in the optical paths of the probe beam and the resultant light from the sample. The beamsplitter reflects the probe beam into the objective and transmits resultant light. The long working-distance, infinity-corrected objective is also arranged in the optical paths of the probe beam and the resultant light. It focuses the reflected probe beam onto the sample, and collects and substantially collimates the resultant light. The relay optics are arranged to relay the transmitted resultant light from the beamsplitter to the detector.

  8. Passive long range acousto-optic sensor

    Science.gov (United States)

    Slater, Dan

    2006-08-01

    Alexander Graham Bell's photophone of 1880 was a simple free space optical communication device that used the sun to illuminate a reflective acoustic diaphragm. A selenium photocell located 213 m (700 ft) away converted the acoustically modulated light beam back into sound. A variation of the photophone is presented here that uses naturally formed free space acousto-optic communications links to provide passive multichannel long range acoustic sensing. This system, called RAS (remote acoustic sensor), functions as a long range microphone with a demonstrated range in excess of 40 km (25 miles).

  9. Theoretical antineutrino detection, direction and ranging at long distances

    Energy Technology Data Exchange (ETDEWEB)

    Jocher, Glenn R., E-mail: gjocher@integrity-apps.com [Integrity Applications Incorporated, 15020 Conference Center Drive, Chantilly, VA, 20151 (United States); Bondy, Daniel A., E-mail: dbondy@integrity-apps.com [Integrity Applications Incorporated, 15020 Conference Center Drive, Chantilly, VA, 20151 (United States); Dobbs, Brian M., E-mail: Brian.M.Dobbs.ctr@nga.mil [Integrity Applications Incorporated, 15020 Conference Center Drive, Chantilly, VA, 20151 (United States); Dye, Stephen T., E-mail: sdye@phys.hawaii.edu [College of Natural Sciences, Hawaii Pacific University, Kaneohe, HI 96744 (United States); Department of Physics and Astronomy, University of Hawaii, Honolulu, HI, 96822 (United States); Georges, James A., E-mail: James.A.Georges.ctr@nga.mil [Integrity Applications Incorporated, 15020 Conference Center Drive, Chantilly, VA, 20151 (United States); Learned, John G., E-mail: jgl@phys.hawaii.edu [Department of Physics and Astronomy, University of Hawaii, Honolulu, HI, 96822 (United States); Mulliss, Christopher L., E-mail: Christopher.L.Mulliss.ctr@nga.mil [Integrity Applications Incorporated, 15020 Conference Center Drive, Chantilly, VA, 20151 (United States); Usman, Shawn, E-mail: Shawn.Usman@nga.mil [InnoVision Basic and Applied Research Office, Sensor Geopositioning Center, National Geospatial-Intelligence Agency, 7500 GEOINT Dr., Springfield, VA, 22150 (United States)

    2013-06-20

    In this paper we introduce the concept of what we call “NUDAR” (NeUtrino Direction and Ranging), making the point that measurements of the observed energy and direction vectors can be employed to passively deduce the exact three-dimensional location and thermal power of geophysical and anthropogenic neutrino sources from even a single detector. Earlier studies have presented the challenges of long-range detection, dominated by the unavoidable inverse-square falloff in neutrinos, which force the use of kiloton scale detectors beyond a few kilometers. Earlier work has also presented the case for multiple detectors, and has reviewed the background challenges. We present the most precise background estimates to date, all handled in full three dimensions, as functions of depth and geographical location. For the present calculations, we consider a hypothetical 138 kiloton detector which can be transported to an ocean site and deployed to an operational depth. We present a Bayesian estimation framework to incorporate any a priori knowledge of the reactor that we are trying to detect, as well as the estimated uncertainty in the background and the oscillation parameters. Most importantly, we fully employ the knowledge of the reactor spectrum and the distance-dependent effects of neutrino oscillations on such spectra. The latter, in particular, makes possible determination of range from one location, given adequate signal statistics. Further, we explore the rich potential of improving detection with even modest improvements in individual neutrino direction determination. We conclude that a 300 MW{sub th} reactor can indeed be geolocated, and its operating power estimated with one or two detectors in the hundred kiloton class at ranges out to a few hundred kilometers. We note that such detectors would have natural and non-interfering utility for scientific studies of geo-neutrinos, neutrino oscillations, and astrophysical neutrinos. This motivates the development of cost

  10. Range detection using entangled optical photons

    Science.gov (United States)

    Brandsema, Matthew J.; Narayanan, Ram M.; Lanzagorta, Marco

    2015-05-01

    Quantum radar is an emerging field that shows a lot of promise in providing significantly improved resolution compared to its classical radar counterpart. The key to this kind of resolution lies in the correlations created from the entanglement of the photons being used. Currently, the technology available only supports quantum radar implementation and validation in the optical regime, as opposed to the microwave regime, because microwave photons have very low energy compared to optical photons. Furthermore, there currently do not exist practical single photon detectors and generators in the microwave spectrum. Viable applications in the optical regime include deep sea target detection and high resolution detection in space. In this paper, we propose a conceptual architecture of a quantum radar which uses entangled optical photons based on Spontaneous Parametric Down Conversion (SPDC) methods. After the entangled photons are created and emerge from the crystal, the idler photon is detected very shortly thereafter. At the same time, the signal photon is sent out towards the target and upon its reflection will impinge on the detector of the radar. From these two measurements, correlation data processing is done to obtain the distance of the target away from the radar. Various simulations are then shown to display the resolution that is possible.

  11. A Passive Optical Location with Limited Range

    Directory of Open Access Journals (Sweden)

    Pavel Fiala

    2008-01-01

    Full Text Available We know active and passive methods of a location. This article deals only with a passive location of dynamic targets. The passive optics location is suitable just for tracking of targets with mean velocity which is limited by the hardware basis. The aim of this work is to recognize plasma, particles etc. It is possible to propose such kind of evaluation methods which improve the capture probability markedly. Suggested method is dealing with the short-distance evaluation of targets. We suppose the application of three independent principles how to recognize an object in a scanned picture. These principles use similar stochastic functions in order to evaluate an object location by means of simple mathematical operations. Methods are based on direct evaluation of picture sequence by the help of the histogram and frequency spectrum. We find out the probability of unidentified moving object in pictures. If the probability reaches a setting value we will get a signal.

  12. Application of velocity filtering to optical-flow passive ranging

    Science.gov (United States)

    Barniv, Yair

    1992-01-01

    The performance of the velocity filtering method as applied to optical-flow passive ranging under real-world conditions is evaluated. The theory of the 3-D Fourier transform as applied to constant-speed moving points is reviewed, and the space-domain shift-and-add algorithm is derived from the general 3-D matched filtering formulation. The constant-speed algorithm is then modified to fit the actual speed encountered in the optical flow application, and the passband of that filter is found in terms of depth (sensor/object distance) so as to cover any given range of depths. Two algorithmic solutions for the problems associated with pixel interpolation and object expansion are developed, and experimental results are presented.

  13. Monocular distance estimation from optic flow during active landing maneuvers

    International Nuclear Information System (INIS)

    Van Breugel, Floris; Morgansen, Kristi; Dickinson, Michael H

    2014-01-01

    Vision is arguably the most widely used sensor for position and velocity estimation in animals, and it is increasingly used in robotic systems as well. Many animals use stereopsis and object recognition in order to make a true estimate of distance. For a tiny insect such as a fruit fly or honeybee, however, these methods fall short. Instead, an insect must rely on calculations of optic flow, which can provide a measure of the ratio of velocity to distance, but not either parameter independently. Nevertheless, flies and other insects are adept at landing on a variety of substrates, a behavior that inherently requires some form of distance estimation in order to trigger distance-appropriate motor actions such as deceleration or leg extension. Previous studies have shown that these behaviors are indeed under visual control, raising the question: how does an insect estimate distance solely using optic flow? In this paper we use a nonlinear control theoretic approach to propose a solution for this problem. Our algorithm takes advantage of visually controlled landing trajectories that have been observed in flies and honeybees. Finally, we implement our algorithm, which we term dynamic peering, using a camera mounted to a linear stage to demonstrate its real-world feasibility. (paper)

  14. Long-distance thermal temporal ghost imaging over optical fibers

    Science.gov (United States)

    Yao, Xin; Zhang, Wei; Li, Hao; You, Lixing; Wang, Zhen; Huang, Yidong

    2018-02-01

    A thermal ghost imaging scheme between two distant parties is proposed and experimentally demonstrated over long-distance optical fibers. In the scheme, the weak thermal light is split into two paths. Photons in one path are spatially diffused according to their frequencies by a spatial dispersion component, then illuminate the object and record its spatial transmission information. Photons in the other path are temporally diffused by a temporal dispersion component. By the coincidence measurement between photons of two paths, the object can be imaged in a way of ghost imaging, based on the frequency correlation between photons in the two paths. In the experiment, the weak thermal light source is prepared by the spontaneous four-wave mixing in a silicon waveguide. The temporal dispersion is introduced by single mode fibers of 50 km, which also could be looked as a fiber link. Experimental results show that this scheme can be realized over long-distance optical fibers.

  15. US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 2: Fiber optic technology and long distance networks

    Science.gov (United States)

    1986-10-01

    The study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the Executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

  16. On the accuracy potential of focused plenoptic camera range determination in long distance operation

    Science.gov (United States)

    Sardemann, Hannes; Maas, Hans-Gerd

    2016-04-01

    Plenoptic cameras have found increasing interest in optical 3D measurement techniques in recent years. While their basic principle is 100 years old, the development in digital photography, micro-lens fabrication technology and computer hardware has boosted the development and lead to several commercially available ready-to-use cameras. Beyond their popular option of a posteriori image focusing or total focus image generation, their basic ability of generating 3D information from single camera imagery depicts a very beneficial option for certain applications. The paper will first present some fundamentals on the design and history of plenoptic cameras and will describe depth determination from plenoptic camera image data. It will then present an analysis of the depth determination accuracy potential of plenoptic cameras. While most research on plenoptic camera accuracy so far has focused on close range applications, we will focus on mid and long ranges of up to 100 m. This range is especially relevant, if plenoptic cameras are discussed as potential mono-sensorial range imaging devices in (semi-)autonomous cars or in mobile robotics. The results show the expected deterioration of depth measurement accuracy with depth. At depths of 30-100 m, which may be considered typical in autonomous driving, depth errors in the order of 3% (with peaks up to 10-13 m) were obtained from processing small point clusters on an imaged target. Outliers much higher than these values were observed in single point analysis, stressing the necessity of spatial or spatio-temporal filtering of the plenoptic camera depth measurements. Despite these obviously large errors, a plenoptic camera may nevertheless be considered a valid option for the application fields of real-time robotics like autonomous driving or unmanned aerial and underwater vehicles, where the accuracy requirements decrease with distance.

  17. Nanoparticle heterodimers: The role of size and interparticle gap distance on the optical response

    Science.gov (United States)

    Mokkath, Junais Habeeb

    2018-05-01

    Composite plasmonic nanostructures with controlled size, shape and relative arrangement is a subject of significant current research interest. Much of this is stimulated by the prospects by generating enormous near-field enhancements of the surface and interparticle gap regions for potential applications in surface-enhanced spectroscopies. In this manuscript, using time-dependent density functional theory (TDDFT) calculations, we investigate how the optical response in size matched homodimers and size mismatched heterodimers composed of Aluminum modify while varying the size and interparticle gap distances in the sub-nanometer range. Both systems show interesting optical response evolution. In particular, the size mismatched heterodimers show even more complex optical response evolution due to a symmetry-breaking in the system.

  18. A coherent free space optical link for long distance clock comparison, navigation, and communication: The Mini-Doll project

    Science.gov (United States)

    Djerroud, K.; Samain, E.; Clairon, A.; Acef, O.; Man, N.; Lemonde, P.; Wolf, P.

    2017-11-01

    We describe the realization of a 5 km free space coherent optical link through the turbulent atmosphere between a telescope and a ground target. We present the phase noise of the link, limited mainly by atmospheric turbulence and mechanical vibrations of the telescope and the target. We discuss the implications of our results for applications, with particular emphasis on optical Doppler ranging to satellites and long distance frequency transfer.

  19. Multiple-Zone Diffractive Optic Element for Laser Ranging Applications

    Science.gov (United States)

    Ramos-Izquierdo, Luis A.

    2011-01-01

    A diffractive optic element (DOE) can be used as a beam splitter to generate multiple laser beams from a single input laser beam. This technology has been recently used in LRO s Lunar Orbiter Laser Altimeter (LOLA) instrument to generate five laser beams that measure the lunar topography from a 50-km nominal mapping orbit (see figure). An extension of this approach is to use a multiple-zone DOE to allow a laser altimeter instrument to operate over a wider range of distances. In particular, a multiple-zone DOE could be used for applications that require both mapping and landing on a planetary body. In this case, the laser altimeter operating range would need to extend from several hundred kilometers down to a few meters. The innovator was recently involved in an investigation how to modify the LOLA instrument for the OSIRIS asteroid mapping and sample return mission. One approach is to replace the DOE in the LOLA laser beam expander assembly with a multiple-zone DOE that would allow for the simultaneous illumination of the asteroid with mapping and landing laser beams. The proposed OSIRIS multiple-zone DOE would generate the same LOLA five-beam output pattern for high-altitude topographic mapping, but would simultaneously generate a wide divergence angle beam using a small portion of the total laser energy for the approach and landing portion of the mission. Only a few percent of the total laser energy is required for approach and landing operations as the return signal increases as the inverse square of the ranging height. A wide divergence beam could be implemented by making the center of the DOE a diffractive or refractive negative lens. The beam energy and beam divergence characteristics of a multiple-zone DOE could be easily tailored to meet the requirements of other missions that require laser ranging data. Current single-zone DOE lithographic manufacturing techniques could also be used to fabricate a multiple-zone DOE by masking the different DOE zones during

  20. Small Device For Short-Range Antenna Measurements Using Optics

    DEFF Research Database (Denmark)

    Yanakiev, Boyan Radkov; Nielsen, Jesper Ødum; Christensen, Morten

    2011-01-01

    This paper gives a practical solution for implementing an antenna radiation pattern measurement device using optical fibers. It is suitable for anechoic chambers as well as short range channel sounding. The device is optimized for small size and provides a cheap and easy way to make optical antenna...

  1. Correlation of optical energy gap with the nearest neighbour short range order in amorphous V2O5 films

    International Nuclear Information System (INIS)

    Dhawan, Sahil; Vedeshwar, Agnikumar G; Tandon, R P

    2011-01-01

    The optical and structural properties of well characterized vacuum-evaporated amorphous V 2 O 5 films were studied in the thickness range 5-500 nm. The structural analyses show that V-O, O-O and V-V nearest neighbour distances defining the short range order vary nonlinearly with film thickness. The optical absorption shows thickness-dependent energy gap (E g ) and the nonlinear behaviour of thickness-dependent E g is similar to that of nearest neighbour distance with film thickness. The E g correlates linearly very well with all the three nearest neighbour distances. The variation of E g with film thickness is attributed to the residual stress in the film which causes the changes in short range order. The change in E g corresponding to the change in V-O distance was found to be 35 eV nm -1 . This change is almost three times of that with V-V distance.

  2. Absolute distance measurement with extension of nonambiguity range using the frequency comb of a femtosecond laser

    Science.gov (United States)

    Jang, Yoon-Soo; Lee, Keunwoo; Han, Seongheum; Lee, Joohyung; Kim, Young-Jin; Kim, Seung-Woo

    2014-12-01

    We revisit the method of synthetic wavelength interferometry (SWI) for absolute measurement of long distances using the radio-frequency harmonics of the pulse repetition rate of a mode-locked femtosecond laser. Our intention here is to extend the nonambiguity range (NAR) of the SWI method using a coarse virtual wavelength synthesized by shifting the pulse repetition rate. The proposed concept of NAR extension is experimentally verified by measuring a ˜13-m distance with repeatability of 9.5 μm (root-mean-square). The measurement precision is estimated to be 31.2 μm in comparison with an incremental He-Ne laser interferometer. This extended SWI method is found to be well suited for long-distance measurements demanded in the fields of large-scale precision engineering, geodetic survey, and future space missions.

  3. Optical fiber cable for transmission of high power laser energy over great distances

    Science.gov (United States)

    Zediker, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Moxley, Joel F.; Koblick, Yeshaya

    2016-05-24

    There is provided a system and apparatus for the transmission of high power laser energy over great distances without substantial power loss and without the presence of stimulated Raman scattering. There is further provided systems and optical fiber cable configurations and optical fiber structures for the delivering high power laser energy over great distances to a tool or surface to perform an operation or work with the tool or upon the surface.

  4. Optical design of soft multifocal contact lens with uniform optical power in center-distance zone with optimized NURBS.

    Science.gov (United States)

    Vu, Lien T; Chen, Chao-Chang A; Yu, Chia-Wei

    2018-02-05

    This study aims to develop a new optical design method of soft multifocal contact lens (CLs) to obtain uniform optical power in large center-distance zone with optimized Non-Uniform Rational B-spline (NURBS). For the anterior surface profiles of CLs, the NURBS design curves are optimized to match given optical power distributions. Then, the NURBS in the center-distance zones are fitted in the corresponding spherical/aspheric curves for both data points and their centers of curvature to achieve the uniform power. Four cases of soft CLs have been manufactured by casting in shell molds by injection molding and then measured to verify the design specifications. Results of power profiles of these CLs are concord with the given clinical requirements of uniform powers in larger center-distance zone. The developed optical design method has been verified for multifocal CLs design and can be further applied for production of soft multifocal CLs.

  5. Optical bistability of graphene in the terahertz range

    DEFF Research Database (Denmark)

    Peres, N. M. R.; Bludov, Yu V.; Santos, Jaime E.

    2014-01-01

    We use an exact solution of the relaxation-time Boltzmann equation in a uniform ac electric field to describe the nonlinear optical response of graphene in the terahertz (THz) range. The cases of monolayer, bilayer, and ABA-stacked trilayer graphene are considered, and the monolayer species...

  6. Orthogonal trapping and sensing with long working distance optics [invited

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin; Tauro, Sandeep

    2010-01-01

    We are developing a next generation BioPhotonics Workstation to be applied in research on regulated microbial cell growth including their underlying physiological mechanisms, in vivo characterization of cell constituents and manufacturing of nanostructures and meta-materials. The workstation......Photonics Workstation that allows the user to directly control and simultaneously measure a portfolio of important chemical and biological processes. We arc currently able to generate up to 100 powerful optical traps using well-separated objectives, which eliminates the need for high numerical aperture oil or water...... immersion objectives required in conventional optical tweezers. This generates a large field of view and leaves vital space for integrating other enabling tools for probing the trapped particles, such as linear and nonlinear microscopy or micro-spectroscopy. Together with chcmists at another Danish...

  7. Integrated Optical Components Utilizing Long-Range Surface Plasmon Polaritons

    DEFF Research Database (Denmark)

    Boltasseva, Alexandra; Nikolajsen, Thomas; Leosson, Kristjan

    2005-01-01

    New optical waveguide technology for integrated optics, based on propagation of long-range surface plasmon polaritons (LR-SPPs) along metal stripes embedded in dielectric, is presented. Guiding and routing of electromagnetic radiation along nanometer-thin and micrometer-wide gold stripes embedded......), and a bend loss of ~5 dB for a bend radius of 15 mm are evaluated for 15-nm-thick and 8-mm-wide stripes at the wavelength of 1550 nm. LR-SPP-based 3-dB power Y-splitters, multimode interference waveguides, and directional couplers are demonstrated and investigated. At 1570 nm, coupling lengths of 1.9 and 0...

  8. Optical polarimetry and distance estimate for Nova Cygni 1975

    Energy Technology Data Exchange (ETDEWEB)

    McLean, I S [Glasgow Univ. (UK). Observatory

    1976-07-01

    Polarization observations of Nova Cygni 1975 were obtained with several passbands in the wavelength interval lambda lambda 4600 to 6700 A before and after maximum light. Special attention was given to the regions of H..cap alpha.. and H..beta.. emission. On average, a precision of +- 0.04 per cent polarization was obtained in these observations. Statistically significant evidence for the presence of an intrinsically-polarized component in the light from the nova is very weak, but such a component is not completely ruled out. Any variability, however, is likely to be less than 0.18 per cent polarization. The observed polarization (1.38 per cent at lambda 5460), is therefore attributed mainly to scattering in the interstellar medium and the amount of polarization is employed to give a rough estimate of the distance of the nova and its absolute magnitude at maximum brightness, namely 1.14 kpc and -10sup(m).1.

  9. Experimental study on performance verification tests for coordinate measuring systems with optical distance sensors

    Science.gov (United States)

    Carmignato, Simone

    2009-01-01

    Optical sensors are increasingly used for dimensional and geometrical metrology. However, the lack of international standards for testing optical coordinate measuring systems is currently limiting the traceability of measurements and the easy comparison of different optical systems. This paper presents an experimental investigation on artefacts and procedures for testing coordinate measuring systems equipped with optical distance sensors. The work is aimed at contributing to the standardization of testing methods. The VDI/VDE 2617-6.2:2005 guideline, which is probably the most complete document available at the state of the art for testing systems with optical distance sensors, is examined with specific experiments. Results from the experiments are discussed, with particular reference to the tests used for determining the following characteristics: error of indication for size measurement, probing error and structural resolution. Particular attention is given to the use of artefacts alternative to gauge blocks for determining the error of indication for size measurement.

  10. Note: Optical and electronic design of an amplitude-modulated continuous-wave laser scanner for high-accuracy distance measurement

    International Nuclear Information System (INIS)

    Jang, Junhwan; Hwang, Sungui; Park, Kyihwan

    2015-01-01

    To utilize a time-of-flight-based laser scanner as a distance measurement sensor, the measurable distance and accuracy are the most important performance parameters to consider. For these purposes, the optical system and electronic signal processing of the laser scanner should be optimally designed in order to reduce a distance error caused by the optical crosstalk and wide dynamic range input. Optical system design for removing optical crosstalk problem is proposed in this work. Intensity control is also considered to solve the problem of a phase-shift variation in the signal processing circuit caused by object reflectivity. The experimental results for optical system and signal processing design are performed using 3D measurements

  11. Note: Optical and electronic design of an amplitude-modulated continuous-wave laser scanner for high-accuracy distance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Junhwan; Hwang, Sungui; Park, Kyihwan, E-mail: khpark@gist.ac.kr [School of Mechatronics, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju (Korea, Republic of)

    2015-04-15

    To utilize a time-of-flight-based laser scanner as a distance measurement sensor, the measurable distance and accuracy are the most important performance parameters to consider. For these purposes, the optical system and electronic signal processing of the laser scanner should be optimally designed in order to reduce a distance error caused by the optical crosstalk and wide dynamic range input. Optical system design for removing optical crosstalk problem is proposed in this work. Intensity control is also considered to solve the problem of a phase-shift variation in the signal processing circuit caused by object reflectivity. The experimental results for optical system and signal processing design are performed using 3D measurements.

  12. Relativistic analysis of the LISA long range optical links

    International Nuclear Information System (INIS)

    Chauvineau, Bertrand; Regimbau, Tania; Vinet, Jean-Yves; Pireaux, Sophie

    2005-01-01

    The joint ESA/NASA LISA mission consists of three spacecraft on heliocentric orbits, flying in a triangular formation of 5 Mkm each side, linked by infrared optical beams. The aim of the mission is to detect gravitational waves in a low frequency band. For properly processing the scientific data, the propagation delays between spacecraft must be accurately known. We thus analyze the propagation of light between spacecraft in order to systematically derive the relativistic effects due to the static curvature of the Schwarzschild space-time in which the spacecraft are orbiting with time-varying light distances. In particular, our analysis allows us to evaluate rigorously the Sagnac effect, and the gravitational (Einstein) redshift

  13. Communication with diode laser: short distance line of sight communication using fiber optics

    International Nuclear Information System (INIS)

    Mirza, A.H.

    1999-01-01

    The objective of this project is to carry audio signal from transmitting station to a short distance receiving station along line of sight and also communication through fiber optics is performed, using diode laser light as carrier. In this project optical communication system, modulation techniques, basics of laser and causes of using diode laser are discussed briefly. Transmitter circuit and receiver circuit are fully described. Communication was performed using pulse width modulation technique. Optical fiber communication have many advantages over other type of conventional communication techniques. This report contains the description of optical fiber communication and compared with other communication systems. (author)

  14. Improved optical ranging for space based gravitational wave detection

    International Nuclear Information System (INIS)

    Sutton, Andrew J; Shaddock, Daniel A; McKenzie, Kirk; Ware, Brent; De Vine, Glenn; Spero, Robert E; Klipstein, W

    2013-01-01

    The operation of 10 6  km scale laser interferometers in space will permit the detection of gravitational waves at previously unaccessible frequency regions. Multi-spacecraft missions, such as the Laser Interferometer Space Antenna (LISA), will use time delay interferometry to suppress the otherwise dominant laser frequency noise from their measurements. This is accomplished by performing sub-sample interpolation of the optical phase measurements recorded at each spacecraft for synchronization and cancellation of the otherwise dominant laser frequency noise. These sub-sample interpolation time shifts are dependent upon the inter-spacecraft range and will be measured using a pseudo-random noise ranging modulation upon the science laser. One limit to the ranging performance is mutual interference between the outgoing and incoming ranging signals upon each spacecraft. This paper reports on the demonstration of a noise cancellation algorithm which is shown to providing a factor of ∼8 suppression of the mutual interference noise. Demonstration of the algorithm in an optical test bed showed an rms ranging error of 0.06 m, improved from 0.19 m in previous results, surpassing the 1 m RMS LISA specification and potentially improving the cancellation of laser frequency noise. (paper)

  15. MTF measurement of IR optics in different temperature ranges

    Science.gov (United States)

    Bai, Alexander; Duncker, Hannes; Dumitrescu, Eugen

    2017-10-01

    Infrared (IR) optical systems are at the core of many military, civilian and manufacturing applications and perform mission critical functions. To reliably fulfill the demanding requirements imposed on today's high performance IR optics, highly accurate, reproducible and fast lens testing is of crucial importance. Testing the optical performance within different temperature ranges becomes key in many military applications. Due to highly complex IR-Applications in the fields of aerospace, military and automotive industries, MTF Measurement under realistic environmental conditions become more and more relevant. A Modulation Transfer Function (MTF) test bench with an integrated thermal chamber allows measuring several sample sizes in a temperature range from -40 °C to +120°C. To reach reliable measurement results under these difficult conditions, a specially developed temperature stable design including an insulating vacuum are used. The main function of this instrument is the measurement of the MTF both on- and off-axis at up to +/-70° field angle, as well as measurement of effective focal length, flange focal length and distortion. The vertical configuration of the system guarantees a small overall footprint. By integrating a high-resolution IR camera with focal plane array (FPA) in the detection unit, time consuming measurement procedures such as scanning slit with liquid nitrogen cooled detectors can be avoided. The specified absolute accuracy of +/- 3% MTF is validated using internationally traceable reference optics. Together with a complete and intuitive software solution, this makes the instrument a turn-key device for today's state-of- the-art optical testing.

  16. High-speed optical coherence tomography by circular interferometric ranging

    Science.gov (United States)

    Siddiqui, Meena; Nam, Ahhyun S.; Tozburun, Serhat; Lippok, Norman; Blatter, Cedric; Vakoc, Benjamin J.

    2018-02-01

    Existing three-dimensional optical imaging methods excel in controlled environments, but are difficult to deploy over large, irregular and dynamic fields. This means that they can be ill-suited for use in areas such as material inspection and medicine. To better address these applications, we developed methods in optical coherence tomography to efficiently interrogate sparse scattering fields, that is, those in which most locations (voxels) do not generate meaningful signal. Frequency comb sources are used to superimpose reflected signals from equispaced locations through optical subsampling. This results in circular ranging, and reduces the number of measurements required to interrogate large volumetric fields. As a result, signal acquisition barriers that have limited speed and field in optical coherence tomography are avoided. With a new ultrafast, time-stretched frequency comb laser design operating with 7.6 MHz to 18.9 MHz repetition rates, we achieved imaging of multi-cm3 fields at up to 7.5 volumes per second.

  17. Optical study of plasma sprayed hydroxyapatite coatings deposited at different spray distance

    Science.gov (United States)

    Belka, R.; Kowalski, S.; Żórawski, W.

    2017-08-01

    Series of hydroxyapatite (HA) coatings deposited on titanium substrate at different spray (plasma gun to workpiece) distance were investigated. The optical methods as dark field confocal microscopy, Raman/PL and UV-VIS spectroscopy were used for study the influence of deposition process on structural degradation of HA precursor. The hydroxyl group concentration was investigated by study the OH mode intensity in the Raman spectra. Optical absorption coefficients at near UV region were analyzed by Diffuse Reflectance Spectroscopy. PL intensity observed during Raman measurement was also considered as relation to defects concentration and degradation level. It was confirmed the different gunsubstrate distance has a great impact on structure of deposited HA ceramics.

  18. Optical fiber configurations for transmission of laser energy over great distances

    Science.gov (United States)

    Rinzler, Charles C; Zediker, Mark S

    2013-10-29

    There are provided optical fiber configurations that provide for the delivery of laser energy, and in particular, the transmission and delivery of high power laser energy over great distances. These configurations further are hardened to protect the optical fibers from the stresses and conditions of an intended application. The configurations provide means for determining the additional fiber length (AFL) need to obtain the benefits of such additional fiber, while avoiding bending losses.

  19. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  20. Extending the Effective Ranging Depth of Spectral Domain Optical Coherence Tomography by Spatial Frequency Domain Multiplexing

    Directory of Open Access Journals (Sweden)

    Tong Wu

    2016-11-01

    Full Text Available We present a spatial frequency domain multiplexing method for extending the imaging depth range of a spectral domain optical coherence tomography (SDOCT system without any expensive device. This method uses two galvo scanners with different pivot-offset distances in two independent reference arms for spatial frequency modulation and multiplexing. The spatial frequency contents corresponding to different depth regions of the sample can be shifted to different frequency bands. The spatial frequency domain multiplexing SDOCT system provides an approximately 1.9-fold increase in the effective ranging depth compared with that of a conventional full-range SDOCT system. The reconstructed images of phantom and biological tissue demonstrate the expected increase in ranging depth. The parameters choice criterion for this method is discussed.

  1. Investigation of a slot nanoantenna in optical frequency range

    Science.gov (United States)

    Dinesh kumar, V.; Asakawa, Kiyoshi

    2009-11-01

    Following the analogy of radio frequency slot antenna and its complementary dipole, we propose the implementation of a slot nanoantenna (SNA) in the optical frequency range. Using finite-difference time-domain (FDTD) method, we investigate the electromagnetic (EM) properties of a SNA formed in a thin gold film and compare the results with the properties of a gold dipole nanoantenna (DNA) of the same dimension as the slot. It is found that the response of the SNA is very similar to the DNA, like their counterparts in the radio frequency (RF) range. The SNA can enhance the near field intensity of incident field which strongly depends on its feedgap dimension. The resonance of the SNA is influenced by its slot length; for the increasing slot length, resonant frequency decreases whereas the sharpness of resonance increases. Besides, the resonance of the SNA is found sensitive to the thickness of metal film, when the latter is smaller than the skin depth. The effect of polarization of incident field on the EM response of the SNA was examined; the field enhancement is optimum when polarization is parallel to the feedgap. Finally, we calculate the radiation patterns of the DNA and SNA and compare them with those of the RF dipole antenna. The radiation pattern of the SNA is found to be independent of its slot length when excited at resonant frequency. To the best of our knowledge, this is the first study on a slot antenna in the optical frequency.

  2. ON THE DISTANCE OF THE MAGELLANIC CLOUDS USING CEPHEID NIR AND OPTICAL-NIR PERIOD-WESENHEIT RELATIONS

    International Nuclear Information System (INIS)

    Inno, L.; Bono, G.; Buonanno, R.; Genovali, K.; Matsunaga, N.; Caputo, F.; Laney, C. D.; Marconi, M.; Piersimoni, A. M.; Primas, F.; Romaniello, M.

    2013-01-01

    We present the largest near-infrared (NIR) data sets, JHKs, ever collected for classical Cepheids in the Magellanic Clouds (MCs). We selected fundamental (FU) and first overtone (FO) pulsators, and found 4150 (2571 FU, 1579 FO) Cepheids for Small Magellanic Cloud (SMC) and 3042 (1840 FU, 1202 FO) for Large Magellanic Cloud (LMC). Current sample is 2-3 times larger than any sample used in previous investigations with NIR photometry. We also discuss optical VI photometry from OGLE-III. NIR and optical-NIR Period-Wesenheit (PW) relations are linear over the entire period range (0.0 FU ≤ 1.65) and their slopes are, within the intrinsic dispersions, common between the MCs. These are consistent with recent results from pulsation models and observations suggesting that the PW relations are minimally affected by the metal content. The new FU and FO PW relations were calibrated using a sample of Galactic Cepheids with distances based on trigonometric parallaxes and Cepheid pulsation models. By using FU Cepheids we found a true distance moduli of 18.45 ± 0.02(random) ± 0.10(systematic) mag (LMC) and 18.93 ± 0.02(random) ± 0.10(systematic) mag (SMC). These estimates are the weighted mean over 10 PW relations and the systematic errors account for uncertainties in the zero point and in the reddening law. We found similar distances using FO Cepheids (18.60 ± 0.03(random) ± 0.10(systematic) mag (LMC) and 19.12 ± 0.03(random) ± 0.10(systematic) mag (SMC)). These new MC distances lead to the relative distance, Δμ = 0.48 ± 0.03 mag (FU, log P = 1) and Δμ = 0.52 ± 0.03 mag (FO, log P = 0.5), which agrees quite well with previous estimates based on robust distance indicators.

  3. Shoulder-Rotator Strength, Range of Motion, and Acromiohumeral Distance in Asymptomatic Adolescent Volleyball Attackers.

    Science.gov (United States)

    Harput, Gulcan; Guney, Hande; Toprak, Ugur; Kaya, Tunca; Colakoglu, Fatma Filiz; Baltaci, Gul

    2016-09-01

    Sport-specific adaptations at the glenohumeral joint could occur in adolescent athletes because they start participating in high-performance sports in early childhood. To investigate shoulder-rotator strength, internal-rotation (IR) and external-rotation (ER) range of motion (ROM), and acromiohumeral distance (AHD) in asymptomatic adolescent volleyball attackers to determine if they have risk factors for injury. Cross-sectional study. University laboratory. Thirty-nine adolescent high school-aged volleyball attackers (22 boys, 17 girls; age = 16.0 ± 1.4 years, height = 179.2 ± 9.0 cm, mass = 67.1 ± 10.9 kg, body mass index = 20.7 ± 2.6 kg/m 2 ). Shoulder IR and ER ROM, total-rotation ROM, glenohumeral IR deficit, AHD, and concentric and eccentric strength of the shoulder internal and external rotators were tested bilaterally. External-rotation ROM was greater (t 38 = 4.92, P 18°). We observed greater concentric internal-rotator (t 38 = 2.89, P = .006) and eccentric external-rotator (t 38 = 2.65, P = .01) strength in the dominant than in the nondominant shoulder. The AHD was less in the dominant shoulder (t 38 = -3.60, P volleyball attackers demonstrated decreased IR ROM, total ROM, and AHD and increased ER ROM in their dominant shoulder. Therefore, routine screening of adolescent athletes and designing training programs for hazardous adaptive changes could be important in preventing shoulder injuries.

  4. [Mechanisms of primary reception of electromagnetic waves of optical range].

    Science.gov (United States)

    Huliar, S O; Lymans'kyĭ, Iu P

    2003-01-01

    An existence of separate functional system of regulation of electromagnetic balance of organism has been substantiated and a working conception of light therapy has been formulated. As a basis, there is a possibility to use the acupuncture points for input of biologically necessary electromagnetic waves into the system of their conductors in a body that might be considered as a transport facility for energy of the polarized electromagnetic waves. Zones-recipients are organs having an electromagnetic disbalance due to excess of biologically inadequate radiation and being the targets for peroxide oxidation. Foremost, a body has the neurohormonal and immune regulatory systems. Electromagnetic stimulation or modification of functions of the zones-recipients determines the achievement of therapeutic and useful effects, and their combination with local reparative processes allows to attain a clinical goal. We represent own and literary experimental data about the development of physiological responses (analgesia) to BIOPTRON-light exposure on the acupuncture points or biologically active zones. We show the experimental facts in support of a hypothesis that a living organism can perceive an action of the electromagnetic fields of optical range not only via the visual system, but also through the off-nerve receptors (specific energy-sensitive proteins detecting critical changes of energy in cells and functioning as the "sensory" cell systems), as well as via the acupuncture points. It confirms an important role of the electromagnetic waves of optical range in providing normal vital functions of living organisms. A current approach to BIOPTRON light therapy (by polarized polychromatic coherent low energy light) consists in combined (local and system) exposure of the electromagnetic waves within the biologically necessary range.

  5. A hybrid active optical system for wave front preservation and variable focal distance

    Energy Technology Data Exchange (ETDEWEB)

    Cocco, Daniele, E-mail: daniele.cocco@elettra.trieste.i [Sincrotrone Trieste ScpA, 34012 Trieste (Italy); Bortoletto, Gianluca; Sergo, Rudi; Sostero, Giovanni; Cudin, Ivan [Sincrotrone Trieste ScpA, 34012 Trieste (Italy)

    2010-05-01

    A new Free Electron Laser (FEL) user facility, named FERMI-Elettra, is under construction at Sincrotrone Trieste (Italy). It is based on a seeded scheme to provide an almost perfect transform limited beam with fully spatial coherence. The wavelength range will be 100-3 nm with fundamental and will go down to 1 nm by using higher harmonics. It will be operative by autumn 2010. The exceptional characteristics of the source must be preserved until the experimental chamber, where a large set of different experiments will be performed. This condition poses very tight requirements to the design of the beamlines and, in particular, to the focusing optics. Here we will present the active optics system developed for Fermi but intended to be used also on the Elettra beamlines. It is based on the adoption of a hybrid active system composed by UHV compatible stepping motors and piezo ceramic actuators. These mirrors are supposed to provide focal distances from 0.8 m to infinity with an angle of incidence up to a few degrees and residual shape errors below 10 or 5 nm (depending on the wavelength). In this way it is possible to work with an almost perfect focused coherent beam as well as with a uniform defocused or unfocused image. The metrology results on the first 400 mm long mirror will be shown and the actuator system described. A strain gauge assembly, calibrated in Elettra by means of a long trace profiler, and controlled by a custom made electronic system developed by us, is used as a direct in situ encoder.

  6. Fiber optic probe of free electron evanescent fields in the optical frequency range

    Energy Technology Data Exchange (ETDEWEB)

    So, Jin-Kyu, E-mail: js1m10@orc.soton.ac.uk; MacDonald, Kevin F. [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Zheludev, Nikolay I. [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371 (Singapore)

    2014-05-19

    We introduce an optical fiber platform which can be used to interrogate proximity interactions between free-electron evanescent fields and photonic nanostructures at optical frequencies in a manner similar to that in which optical evanescent fields are sampled using nanoscale aperture probes in scanning near-field microscopy. Conically profiled optical fiber tips functionalized with nano-gratings are employed to couple electron evanescent fields to light via the Smith-Purcell effect. We demonstrate the interrogation of medium energy (30–50 keV) electron fields with a lateral resolution of a few micrometers via the generation and detection of visible/UV radiation in the 700–300 nm (free-space) wavelength range.

  7. Ultra-stable long distance optical frequency distribution using the Internet fiber network.

    Science.gov (United States)

    Lopez, Olivier; Haboucha, Adil; Chanteau, Bruno; Chardonnet, Christian; Amy-Klein, Anne; Santarelli, Giorgio

    2012-10-08

    We report an optical link of 540 km for ultrastable frequency distribution over the Internet fiber network. The stable frequency optical signal is processed enabling uninterrupted propagation on both directions. The robustness and the performance of the link are enhanced by a cost effective fully automated optoelectronic station. This device is able to coherently regenerate the return optical signal with a heterodyne optical phase locking of a low noise laser diode. Moreover the incoming signal polarization variation are tracked and processed in order to maintain beat note amplitudes within the operation range. Stable fibered optical interferometer enables optical detection of the link round trip phase signal. The phase-noise compensated link shows a fractional frequency instability in 10 Hz bandwidth of 5 × 10(-15) at one second measurement time and 2 × 10(-19) at 30,000 s. This work is a significant step towards a sustainable wide area ultrastable optical frequency distribution and comparison network.

  8. The extra mile: Ungulate migration distance alters the use of seasonal range and exposure to anthropogenic risk

    Science.gov (United States)

    Sawyer, Hall; Middleton, Arthur D.; Hayes, Matthew M.; Kauffman, Matthew J.; Monteith, Kevin L.

    2016-01-01

    Partial migration occurs across a variety of taxa and has important ecological and evolutionary consequences. Among ungulates, studies of partially migratory populations have allowed researchers to compare and contrast performance metrics of migrants versus residents and examine how environmental factors influence the relative abundance of each. Such studies tend to characterize animals discretely as either migratory or resident, but we suggest that variable migration distances within migratory herds are an important and overlooked form of population structure, with potential consequences for animal fitness. We examined whether the variation in individual migration distances (20–264 km) within a single wintering population of mule deer (Odocoileus hemionus) was associated with several critical behavioral attributes of migration, including timing of migration, time allocation to seasonal ranges, and exposure to anthropogenic mortality risks. Both the timing of migration and the amount of time animals allocated to seasonal ranges varied with migration distance. Animals migrating long distances (150–250 km) initiated spring migration more than three weeks before than those migrating moderate (50–150 km) or short distances (forage and effectively increase carrying capacity. Clear differences in winter residency, migration duration, and risk of anthropogenic mortality among short-, moderate-, and long-distance migrants suggest fitness trade-offs may exist among migratory segments of the population. Future studies of partial migration may benefit from expanding comparisons of residents and migrants, to consider how variable migration distances of migrants may influence the costs and benefits of migration.

  9. Volumetric full-range magnetomotive optical coherence tomography

    Science.gov (United States)

    Ahmad, Adeel; Kim, Jongsik; Shemonski, Nathan D.; Marjanovic, Marina; Boppart, Stephen A.

    2014-01-01

    Abstract. Magnetomotive optical coherence tomography (MM-OCT) can be utilized to spatially localize the presence of magnetic particles within tissues or organs. These magnetic particle-containing regions are detected by using the capability of OCT to measure small-scale displacements induced by the activation of an external electromagnet coil typically driven by a harmonic excitation signal. The constraints imposed by the scanning schemes employed and tissue viscoelastic properties limit the speed at which conventional MM-OCT data can be acquired. Realizing that electromagnet coils can be designed to exert MM force on relatively large tissue volumes (comparable or larger than typical OCT imaging fields of view), we show that an order-of-magnitude improvement in three-dimensional (3-D) MM-OCT imaging speed can be achieved by rapid acquisition of a volumetric scan during the activation of the coil. Furthermore, we show volumetric (3-D) MM-OCT imaging over a large imaging depth range by combining this volumetric scan scheme with full-range OCT. Results with tissue equivalent phantoms and a biological tissue are shown to demonstrate this technique. PMID:25472770

  10. Effect Of Platooning on Fuel Consumption of Class 8 Vehicles Over a Range of Speeds, Following Distances, and Mass

    Energy Technology Data Exchange (ETDEWEB)

    Lammert, M. P.; Duran, A.; Diez, J.; Burton, K.; Nicholson, A.

    2014-10-01

    This research project evaluates fuel consumption results of two Class 8 tractor-trailer combinations platooned together compared to their standalone fuel consumption. A series of ten modified SAE Type II J1321 fuel consumption track tests were performed to document fuel consumption of two platooned vehicles and a control vehicle at varying steady-state speeds, following distances, and gross vehicle weights (GVWs). The steady-state speeds ranged from 55 mph to 70 mph, the following distances ranged from a 20-ft following distance to a 75-ft following distance, and the GVWs were 65K lbs and 80K lbs. All tractors involved had U.S. Environmental Protection Agency (EPA) SmartWay-compliant aerodynamics packages installed, and the trailers were equipped with side skirts. Effects of vehicle speed, following distance, and GVW on fuel consumption were observed and analyzed. The platooning demonstration system used in this study consisted of radar systems, Dedicated Short-Range Communication (DSRC) vehicle-to-vehicle (V2V) communications, vehicle braking and torque control interface, cameras and driver displays. The lead tractor consistently demonstrated an improvement in average fuel consumption reduction as following distance decreased, with results showing 2.7% to 5.3% fuel savings at a GVW of 65k. The trailing vehicle achieved fuel consumption savings ranging from 2.8% to 9.7%; tests during which the engine cooling fan did not operate achieved savings of 8.4% to 9.7%. 'Team' fuel savings, considering the platooned vehicles as one, ranged from 3.7% to 6.4%, with the best combined result being for 55 mph, 30-ft following distance, and 65k GVW.

  11. Laser distance measurement using a newly developed composite-type optical fiberscope for fetoscopic laser surgery

    Science.gov (United States)

    Seki, Takeshi; Oka, Kiyoshi; Naganawa, Akihiro; Yamashita, Hiromasa; Kim, Keri; Chiba, Toshio

    2010-10-01

    Twin-twin transfusion syndrome (TTTS) is a condition of twins disproportionately sharing blood by the communicating vessels in the shared placenta and resulting in the significantly high fetal and perinatal mortality rate. Fetoscopic laser surgery is performed to block these communicating vessels. It is difficult, however, to perceive the distance from the tip of the fetoscope to the placental surface with only a two-dimensional fetoscopic view. When the distance is too short it causes excessive irradiation and even the risk of inadvertent damage to the placenta. On the other hand, not only target vessels but also adjacent tissues can be irradiated when it is too long. We have developed a composite-type optical fiberscope (COF) that was able to observe the target area and also to perform laser irradiation at the same time. In this paper, we studied a method to estimate the distance from the tip of the COF to the target area. We combined the COF with a laser blood-flow meter. Using laser light from the meter, we measured the total amount of light received ("REFLEX") and estimated the relation between the "REFLEX" value and the laser irradiation distance. Further in vivo experiments were subsequently carried out using porcine mesenteric blood vessels. The results showed that the distance and the "REFLEX" value were inversely proportional, irrespective of the experimental environment (e.g. in air, water and amniotic fluid-like solution) and the target object. In the in vivo experiments, we quantitatively measured the distance within an accuracy of ±1 mm (approximately 10%). In conclusion, our new system was able to measure the distance in vivo enabling a surgeon to safely and effectively perform laser irradiation at a suitable distance. The system can be used not only for fetoscopic surgery but also for general endoscopic surgery.

  12. Binary stars observed with adaptive optics at the starfire optical range

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, Jack D. [Air Force Research Laboratory, Directed Energy Directorate, RDSAM, 3550 Aberdeen Avenue SE, Kirtland AFB, NM 87117-5776 (United States)

    2014-03-01

    In reviewing observations taken of binary stars used as calibration objects for non-astronomical purposes with adaptive optics on the 3.5 m Starfire Optical Range telescope over the past 2 years, one-fifth of them were found to be off-orbit. In order to understand such a high number of discrepant position angles and separations, all previous observations in the Washington Double Star Catalog for these rogue binaries were obtained from the Naval Observatory. Adding our observations to these yields new orbits for all, resolving the discrepancies. We have detected both components of γ Gem for the first time, and we have shown that 7 Cam is an optical pair, not physically bound.

  13. Comprehensive long distance and real-time pipeline monitoring system based on fiber optic sensing

    Energy Technology Data Exchange (ETDEWEB)

    Nikles, Marc; Ravet, Fabien; Briffod, Fabien [Omnisens S.A., Morges (Switzerland)

    2009-07-01

    An increasing number of pipelines are constructed in remote regions affected by harsh environmental conditions. These pipeline routes often cross mountain areas which are characterized by unstable grounds and where soil texture changes between winter and summer increase the probability of hazards. Due to the long distances to be monitored and the linear nature of pipelines, distributed fiber optic sensing techniques offer significant advantages and the capability to detect and localize pipeline disturbance with great precision. Furthermore pipeline owner/operators lay fiber optic cable parallel to transmission pipelines for telecommunication purposes and at minimum additional cost monitoring capabilities can be added to the communication system. The Brillouin-based Omnisens DITEST monitoring system has been used in several long distance pipeline projects. The technique is capable of measuring strain and temperature over 100's kilometers with meter spatial resolution. Dedicated fiber optic cables have been developed for continuous strain and temperature monitoring and their deployment along the pipeline has enabled permanent and continuous pipeline ground movement, intrusion and leak detection. This paper presents a description of the fiber optic Brillouin-based DITEST sensing technique, its measurement performance and limits, while addressing future perspectives for pipeline monitoring. (author)

  14. Long-distance fiber optic sensing solutions for pipeline leakage, intrusion, and ground movement detection

    Science.gov (United States)

    Nikles, Marc

    2009-05-01

    An increasing number of pipelines are constructed in remote regions affected by harsh environmental conditions where pipeline routes often cross mountain areas which are characterized by unstable grounds and where soil texture changes between winter and summer increase the probability of hazards. Third party intentional interference or accidental intrusions are a major cause of pipeline failures leading to large leaks or even explosions. Due to the long distances to be monitored and the linear nature of pipelines, distributed fiber optic sensing techniques offer significant advantages and the capability to detect and localize pipeline disturbance with great precision. Furthermore pipeline owner/operators lay fiber optic cable parallel to transmission pipelines for telecommunication purposes and at minimum additional cost monitoring capabilities can be added to the communication system. The Brillouin-based Omnisens DITEST monitoring system has been used in several long distance pipeline projects. The technique is capable of measuring strain and temperature over 100's kilometers with meter spatial resolution. Dedicated fiber optic cables have been developed for continuous strain and temperature monitoring and their deployment along the pipeline has enabled permanent and continuous pipeline ground movement, intrusion and leak detection. This paper presents a description of the fiber optic Brillouin-based DITEST sensing technique, its measurement performance and limits, while addressing future perspectives for pipeline monitoring. The description is supported by case studies and illustrated by field data.

  15. Optical nutation in the exciton range of spectrum

    International Nuclear Information System (INIS)

    Khadzhi, P. I.; Vasiliev, V. V.

    2013-01-01

    Optical nutation in the exciton range of spectrum is studied in the mean field approximation taking into account exciton-photon and elastic exciton-exciton interactions. It is shown that the features of nutation development are determined by the initial exciton and photon densities, the resonance detuning, the nonlinearity parameter, and the initial phase difference. For nonzero initial exciton and photon concentrations, three regimes of temporal evolution of excitons and photons exist: periodic conversion of excitons to photons and vice versa, aperiodic conversion of photons to excitons, and the rest regime. In the rest regime, the initial exciton and photon densities are nonzero and do not change with time. The oscillation amplitudes and periods of particle densities determined by the system parameters are found. The exciton self-trapping and photon trapping appearing in the system at threshold values of the nonlinearity parameter were predicted. As this parameter increases, the oscillation amplitudes of the exciton and photon densities sharply change at the critical value of the nonlinearity parameter. These two phenomena are shown to be caused by the elastic exciton-exciton interaction, resulting in the dynamic concentration shift of the exciton level

  16. Long-distance entanglement in many-body atomic and optical systems

    Energy Technology Data Exchange (ETDEWEB)

    Giampaolo, Salvatore M; Illuminati, Fabrizio [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano, SA (Italy)], E-mail: illuminati@sa.infn.it

    2010-02-15

    We discuss the phenomenon of long-distance entanglement (LDE) in the ground state of quantum spin models, its use in high-fidelity and robust quantum communication, and its realization in many-body systems of ultracold atoms in optical lattices and in arrays of coupled optical cavities. We investigate XX quantum spin models on one-dimensional lattices with open ends and different patterns of site-dependent interaction couplings, singling out two general settings: patterns that allow for perfect LDE in the ground state of the system, namely such that the end-to-end entanglement remains finite in the thermodynamic limit, and patterns of quasi-long-distance entanglement (QLDE) in the ground state of the system, namely such that the end-to-end entanglement vanishes with a very slow power-law decay as the length of the spin chain is increased. We discuss physical realizations of these models in ensembles of ultracold bosonic atoms loaded in optical lattices. We show how, using either suitably engineered super-lattice structures or exploiting the presence of edge impurities in lattices with single periodicity, it is possible to realize models endowed with nonvanishing LDE or QLDE. We then study how to realize models that optimize the robustness of QLDE at finite temperature and in the presence of imperfections using suitably engineered arrays of coupled optical cavities. For both cases the numerical estimates of the end-to-end entanglement in the actual physical systems are thoroughly compared with the analytical results obtained for the spin model systems. We finally introduce LDE-based schemes of long-distance quantum teleportation in linear arrays of coupled cavities, and show that they allow for high-fidelity and high success rates even at moderately high temperatures.

  17. Long-distance entanglement in many-body atomic and optical systems

    International Nuclear Information System (INIS)

    Giampaolo, Salvatore M; Illuminati, Fabrizio

    2010-01-01

    We discuss the phenomenon of long-distance entanglement (LDE) in the ground state of quantum spin models, its use in high-fidelity and robust quantum communication, and its realization in many-body systems of ultracold atoms in optical lattices and in arrays of coupled optical cavities. We investigate XX quantum spin models on one-dimensional lattices with open ends and different patterns of site-dependent interaction couplings, singling out two general settings: patterns that allow for perfect LDE in the ground state of the system, namely such that the end-to-end entanglement remains finite in the thermodynamic limit, and patterns of quasi-long-distance entanglement (QLDE) in the ground state of the system, namely such that the end-to-end entanglement vanishes with a very slow power-law decay as the length of the spin chain is increased. We discuss physical realizations of these models in ensembles of ultracold bosonic atoms loaded in optical lattices. We show how, using either suitably engineered super-lattice structures or exploiting the presence of edge impurities in lattices with single periodicity, it is possible to realize models endowed with nonvanishing LDE or QLDE. We then study how to realize models that optimize the robustness of QLDE at finite temperature and in the presence of imperfections using suitably engineered arrays of coupled optical cavities. For both cases the numerical estimates of the end-to-end entanglement in the actual physical systems are thoroughly compared with the analytical results obtained for the spin model systems. We finally introduce LDE-based schemes of long-distance quantum teleportation in linear arrays of coupled cavities, and show that they allow for high-fidelity and high success rates even at moderately high temperatures.

  18. Dispersion free full range spectral intensity optical coherence tomography

    DEFF Research Database (Denmark)

    Jensen, Mikkel; Israelsen, Niels Møller; Maria, Michael

    2017-01-01

    Optical coherence tomography (OCT) is a non-invasive imaging technique with many applications and widespread use in ophthalmology [1]. The axial resolution in OCT is inversely proportional to the bandwidth of the optical source used, but the improved axial resolution comes at the price of more...

  19. Long working distance optical coherence tomography for pediatric imaging (Conference Presentation)

    Science.gov (United States)

    Qian, Ruobing; Carrasco-Zevallos, Oscar; Vajzovic, Lejla; Gramatikov, Boris I.; Guyton, David L.; Toth, Cynthia A.; Izatt, Joseph A.

    2016-03-01

    Conventional optical coherence tomography (OCT) systems have working distances of about 25 mm, and require cooperative subjects to immobilize and fixate on a target. Handheld OCT probes have also been demonstrated for successful imaging of pre-term infants and neonates up to ~1 year old. However, no technology yet exists for OCT in young children due to their lack of attention and inherent fear of large objects close to their face. In this work, we demonstrate a prototype retinal swept-source OCT system with a long working distance (from the last optical element to the subject's eye) to facilitate pediatric imaging. To reduce the footprint and weight of the system compared to the conventional 4f scheme, a novel 2f scanning configuration was implemented to achieve a working distance of 348mm with a +/- 8° scanning angle prior to cornea. Employing two custom-designed lenses, the system design resolution was nearly diffraction limited throughout a -8D to +5D refractive corrections. A fixation target displayed on a LCD monitor and an iris camera were used to facilitate alignment and imaging. Our prototype was tested in consented adult subjects and has the potential to facilitate imaging of young children. With this apparatus, young children could potentially sit comfortably in caretaker's lap while viewing entertainment on the fixation screen designed to direct their gaze into the imaging apparatus.

  20. Characterization of Long Working Distance Optical Coherence Tomography for Imaging of Pediatric Retinal Pathology.

    Science.gov (United States)

    Qian, Ruobing; Carrasco-Zevallos, Oscar M; Mangalesh, Shwetha; Sarin, Neeru; Vajzovic, Lejla; Farsiu, Sina; Izatt, Joseph A; Toth, Cynthia A

    2017-10-01

    We determined the feasibility of fovea and optic nerve head imaging with a long working distance (LWD) swept source optical coherence tomography (OCT) prototype in adults, teenagers, and young children. A prototype swept source OCT system with a LWD (defined as distance from the last optical element of the imaging system to the eye) of 350 mm with custom fixation targets was developed to facilitate imaging of children. Imaging was performed in 49 participants from three age groups: 26 adults, 16 children 13 to 18 years old (teenagers), and seven children under 6 years old (young children) under an approved institutional review board protocol. The imaging goal was to acquire high quality scans of the fovea and optic nerve in each eye in the shortest time possible. OCT B-scans and volumes of the fovea and optic nerve head of each eligible eye were captured and graded based on four categories (lateral and axial centration, contrast, and resolution) and on ability to determine presence or absence of pathology. LWD-OCT imaging was successful in 88 of 94 eligible eyes, including seven of 10 eyes of young children. Of the successfully acquired OCT images, 83% of B-scan and volumetric images, including 86% from young children, were graded as high-quality scans. Pathology was observed in high-quality OCT images. The prototype LWD-OCT system achieved high quality retinal imaging of adults, teenagers, and some young children with and without pathology with reasonable alignment time. The LWD-OCT system can facilitate imaging in children.

  1. The effect of neighbourhood definitions on spatio-temporal models of disease outbreaks: Separation distance versus range overlap.

    Science.gov (United States)

    Laffan, Shawn W; Wang, Zhaoyuan; Ward, Michael P

    2011-12-01

    The definition of the spatial relatedness between infectious and susceptible animal groups is a fundamental component of spatio-temporal modelling of disease outbreaks. A common neighbourhood definition for disease spread in wild and feral animal populations is the distance between the centroids of neighbouring group home ranges. This distance can be used to define neighbourhood interactions, and also to describe the probability of successful disease transmission. Key limitations of this approach are (1) that a susceptible neighbour of an infectious group with an overlapping home range - but whose centroid lies outside the home range of an infectious group - will not be considered for disease transmission, and (2) the degree of overlap between the home ranges is not taken into account for those groups with centroids inside the infectious home range. We assessed the impact of both distance-based and range overlap methods of disease transmission on model-predicted disease spread. Range overlap was calculated using home ranges modelled as circles. We used the Sirca geographic automata model, with the population data from a nine-county study area in Texas that we have previously described. For each method we applied 100 model repetitions, each of 100 time steps, to 30 index locations. The results show that the rate of disease spread for the range-overlap method is clearly less than the distance-based method, with median outbreaks modelled using the latter being 1.4-1.45 times larger. However, the two methods show similar overall trends in the area infected, and the range-overlap median (48 and 120 for cattle and pigs, respectively) falls within the 5th-95th percentile range of the distance-based method (0-96 and 0-252 for cattle and pigs, respectively). These differences can be attributed to the calculation of the interaction probabilities in the two methods, with overlap weights generally resulting in lower interaction probabilities. The definition of spatial

  2. Lidar: range-resolved optical remote sensing of the atmosphere

    National Research Council Canada - National Science Library

    Weitkamp, Claus; Walther, Herbert

    2005-01-01

    "Written by leading experts in optical radar, or lidar, this book brings all the recent practices up-to-date and covers a multitude of applications, from atmospheric sciences to environmental protection...

  3. Vibration Isolation Platform for Long Range Optical Communications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical communication links provide higher data transfer rates with lower mass, power, and volume than conventional radio-frequency links. For deep space...

  4. Quantum metamaterials in the microwave and optical ranges

    Energy Technology Data Exchange (ETDEWEB)

    Zagoskin, Alexandre M. [Loughborough University, Department of Physics, Loughborough (United Kingdom); Moscow Institute for Steel and Alloys, Theoretical Physics and Quantum Technologies Department, Moscow (Russian Federation); Felbacq, Didier; Rousseau, Emmanuel [University of Montpellier, Laboratory Charles Coulomb UMR CNRS-UM 5221, Montpellier (France)

    2016-12-15

    Quantum metamaterials generalize the concept of metamaterials (artificial optical media) to the case when their optical properties are determined by the interplay of quantum effects in the constituent 'artificial atoms' with the electromagnetic field modes in the system. The theoretical investigation of these structures demonstrated that a number of new effects (such as quantum birefringence, strongly nonclassical states of light, etc.) are to be expected, prompting the efforts on their fabrication and experimental investigation. Here we provide a summary of the principal features of quantum metamaterials and review the current state of research in this quickly developing field, which bridges quantum optics, quantum condensed matter theory and quantum information processing. (orig.)

  5. Longer wings for faster springs - wing length relates to spring phenology in a long-distance migrant across its range.

    Science.gov (United States)

    Hahn, Steffen; Korner-Nievergelt, Fränzi; Emmenegger, Tamara; Amrhein, Valentin; Csörgő, Tibor; Gursoy, Arzu; Ilieva, Mihaela; Kverek, Pavel; Pérez-Tris, Javier; Pirrello, Simone; Zehtindjiev, Pavel; Salewski, Volker

    2016-01-01

    In migratory birds, morphological adaptations for efficient migratory flight often oppose morphological adaptations for efficient behavior during resident periods. This includes adaptations in wing shape for either flying long distances or foraging in the vegetation and in climate-driven variation of body size. In addition, the timing of migratory flights and particularly the timely arrival at local breeding sites is crucial because fitness prospects depend on site-specific phenology. Thus, adaptations for efficient long-distance flights might be also related to conditions at destination areas. For an obligatory long-distance migrant, the common nightingale, we verified that wing length as the aerodynamically important trait, but not structural body size increased from the western to the eastern parts of the species range. In contrast with expectation from aerodynamic theory, however, wing length did not increase with increasing migration distances. Instead, wing length was associated with the phenology at breeding destinations, namely the speed of local spring green-up. We argue that longer wings are beneficial for adjusting migration speed to local conditions for birds breeding in habitats with fast spring green-up and thus short optimal arrival periods. We suggest that the speed of spring green-up at breeding sites is a fundamental variable determining the timing of migration that fine tune phenotypes in migrants across their range.

  6. Optical Sensor for Diverse Organic Vapors at ppm Concentration Ranges

    Directory of Open Access Journals (Sweden)

    Dora M. Paolucci

    2011-03-01

    Full Text Available A broadly responsive optical organic vapor sensor is described that responds to low concentrations of organic vapors without significant interference from water vapor. Responses to several classes of organic vapors are highlighted, and trends within classes are presented. The relationship between molecular properties (vapor pressure, boiling point, polarizability, and refractive index and sensor response are discussed.

  7. Conception and development of an optical methodology applied to long-distance measurement of suspension bridges dynamic displacement

    International Nuclear Information System (INIS)

    Martins, L Lages; Ribeiro, A Silva; Rebordão, J M

    2013-01-01

    This paper describes the conception and development of an optical system applied to suspension bridge structural monitoring, aiming real-time and long-distance measurement of dynamical three-dimensional displacement, namely, in the central section of the main span. The main innovative issues related to this optical approach are described and a comparison with other optical and non-optical measurement systems is performed. Moreover, a computational simulator tool developed for the optical system design and validation of the implemented image processing and calculation algorithms is also presented

  8. An experimentally verified model for estimating the distance resolution capability of direct time of flight 3D optical imaging systems

    International Nuclear Information System (INIS)

    Nguyen, K Q K; Fisher, E M D; Walton, A J; Underwood, I

    2013-01-01

    This report introduces a new statistical model for time-resolved photon detection in a generic single-photon-sensitive sensor array. The model is validated by comparing modelled data with experimental data collected on a single-photon avalanche diode sensor array. Data produced by the model are used alongside corresponding experimental data to calculate, for the first time, the effective distance resolution of a pulsed direct time of flight 3D optical imaging system over a range of conditions using four peak-detection algorithms. The relative performance of the algorithms is compared. The model can be used to improve the system design process and inform selection of the optimal peak-detection algorithm. (paper)

  9. Lidar Range-Resolved Optical Remote Sensing of the Atmosphere

    CERN Document Server

    Weitkamp, Claus

    2005-01-01

    Written by leading experts in optical radar, or lidar, this book brings all the recent practices up-to-date and covers a multitude of applications, from atmospheric sciences to environmental protection. Its broad cross-disciplinary scope should appeal to both the experienced scientist and the novice in the field. The Foreword is by one of the early pioneers in the area, Herbert Walther.

  10. A study of the normal interpedicular distance of the spine in Korean teenagers (Estimation of normal range by roentgenographic measurement)

    International Nuclear Information System (INIS)

    Lee, Myung Uk

    1979-01-01

    The radiological measurement of the interpedicular disease using a routine antero-posterior view of the spine gives important clinical criteria in evaluation of the intraspinal tumor and stenosis of the spinal canal, and aids for diagnosis of the lesions. In 1934 Elsberg and Dyke reported values of interpedicular distance as determined on roentgenograms for spine of white adult, and in 1968 Song prepared normal values of interpedicular distance for Korean adult. The present investigation was undertaken to provide normal interpedicular distance of Korean teenagers. The author observed the antero-posterior films of the spine of 200 normal teenagers which were composed of 100 male and 100 female. The normal values of the interpedicular distance of Korean teenagers were obtained, as well as 90% tolerance range for clinical use. In this statistical analysis, there were noted significant differences between male and female, and each age groups. It was observed that average male measurement were consistently larger than female by about 1 mm and the growth of the spinal canal appeared to be continued.

  11. Optical method for distance and displacement measurements of the probe-sample separation in a scanning near-field optical microscope

    International Nuclear Information System (INIS)

    Santamaria, L.; Siller, H. R.; Garcia-Ortiz, C. E.; Cortes, R.; Coello, V.

    2016-01-01

    In this work, we present an alternative optical method to determine the probe-sample separation distance in a scanning near-field optical microscope. The experimental method is based in a Lloyd’s mirror interferometer and offers a measurement precision deviation of ∼100 nm using digital image processing and numerical analysis. The technique can also be strategically combined with the characterization of piezoelectric actuators and stability evaluation of the optical system. It also opens the possibility for the development of an automatic approximation control system valid for probe-sample distances from 5 to 500 μm.

  12. Optical method for distance and displacement measurements of the probe-sample separation in a scanning near-field optical microscope

    Energy Technology Data Exchange (ETDEWEB)

    Santamaria, L.; Siller, H. R. [Tecnológico de Monterrey, Eugenio Garza Sada 2501 Sur, Monterrey, N.L., 64849 (Mexico); Garcia-Ortiz, C. E., E-mail: cegarcia@cicese.mx [CONACYT Research Fellow – CICESE, Unidad Monterrey, Alianza Centro 504, Apodaca, NL, 66629 (Mexico); Cortes, R.; Coello, V. [CICESE, Unidad Monterrey, PIIT, Alianza Centro 504, Apodaca, NL, 66629 (Mexico)

    2016-04-15

    In this work, we present an alternative optical method to determine the probe-sample separation distance in a scanning near-field optical microscope. The experimental method is based in a Lloyd’s mirror interferometer and offers a measurement precision deviation of ∼100 nm using digital image processing and numerical analysis. The technique can also be strategically combined with the characterization of piezoelectric actuators and stability evaluation of the optical system. It also opens the possibility for the development of an automatic approximation control system valid for probe-sample distances from 5 to 500 μm.

  13. Back mobility and interincisor distance ranges in racially diverse North American healthy children and relationship to generalized hypermobility

    Directory of Open Access Journals (Sweden)

    Woolston Sophie L

    2012-06-01

    Full Text Available Abstract Background Given the dearth of normal values, we conducted a cross-sectional study of North American racially diverse children to determine normal values of interincisor distance and lower spine flexion. Methods Demographs of 307 children aged 5–17 seeking treatment emergency care were obtained along with interincisor distance measured by incisor tooth-to-tooth gap, lower spine flexion measured by the Schober and modified Schober measurements, popliteal extension, hypermobility (Beighton score, weight and height. Results Normal range of motion values for the Schober was a mean of 14.3 cm (95% confidence interval (CI was 11.2 to 17. cm and the mean modified Schober’s was 21.6 cm (95% CI 18.4 cm to 24.8 cm. Retained lumbar lordosis on forward flexion was observed in 33%. Back mobility was associated with body mass index (BMI, popliteal angle, and Beighton score but not sex, race or retained lordosis. The mean interincisor distance measurement was 47 mm (95% CI 35 mm to 60 mm and was associated with height and BMI but not sex, race, or Beighton score. Conclusion Normal values for lower back range of motion and interincisor distance were obtained which are needed in pediatric rheumatologic clinics and do not significantly vary as to race or sex. Retained lordosis on forward flexion is a normal variant. Hamstring tightness, hypermobility and BMI need to be considered when ascertaining back mobility.

  14. Improved laser-based triangulation sensor with enhanced range and resolution through adaptive optics-based active beam control.

    Science.gov (United States)

    Reza, Syed Azer; Khwaja, Tariq Shamim; Mazhar, Mohsin Ali; Niazi, Haris Khan; Nawab, Rahma

    2017-07-20

    Various existing target ranging techniques are limited in terms of the dynamic range of operation and measurement resolution. These limitations arise as a result of a particular measurement methodology, the finite processing capability of the hardware components deployed within the sensor module, and the medium through which the target is viewed. Generally, improving the sensor range adversely affects its resolution and vice versa. Often, a distance sensor is designed for an optimal range/resolution setting depending on its intended application. Optical triangulation is broadly classified as a spatial-signal-processing-based ranging technique and measures target distance from the location of the reflected spot on a position sensitive detector (PSD). In most triangulation sensors that use lasers as a light source, beam divergence-which severely affects sensor measurement range-is often ignored in calculations. In this paper, we first discuss in detail the limitations to ranging imposed by beam divergence, which, in effect, sets the sensor dynamic range. Next, we show how the resolution of laser-based triangulation sensors is limited by the interpixel pitch of a finite-sized PSD. In this paper, through the use of tunable focus lenses (TFLs), we propose a novel design of a triangulation-based optical rangefinder that improves both the sensor resolution and its dynamic range through adaptive electronic control of beam propagation parameters. We present the theory and operation of the proposed sensor and clearly demonstrate a range and resolution improvement with the use of TFLs. Experimental results in support of our claims are shown to be in strong agreement with theory.

  15. Interferometric 30 m bench for calibrations of 1D scales and optical distance measuring instruments

    International Nuclear Information System (INIS)

    Unkuri, J; Rantanen, A; Manninen, J; Esala, V-P; Lassila, A

    2012-01-01

    During construction of a new metrology building for MIKES, a 30 m interferometric bench was designed. The objective was to implement a straight, stable, adjustable and multifunctional 30 m measuring bench for calibrations. Special attention was paid to eliminating the effects of thermal expansion and inevitable concrete shrinkage. The linear guide, situated on top of a monolithic concrete beam, comprises two parallel round shafts with adjustable fixtures every 1 m. A carriage is moved along the rail and its position is followed by a reference interferometer. Depending on the measurement task, one or two retro-reflectors are fixed on the carriage. A microscope with a CCD camera and a monitor can be used to detect line mark positions on different line standards. When calibrating optical distance measuring instruments, various targets can be fixed to the carriage. For the most accurate measurements an online Abbe-error correction based on simultaneous carriage pitch measurement by a separate laser interferometer is applied. The bench is used for calibrations of machinist scales, tapes, circometers, electronic distance meters, total stations and laser trackers. The estimated expanded uncertainty for 30 m displacement for highest accuracy calibrations is 2.6 µm. (paper)

  16. LSPR Coupling and Distribution of Interparticle Distances between Nanoparticles in Hydrogel on Optical Fiber End Face

    Directory of Open Access Journals (Sweden)

    Harald Ian Muri

    2017-11-01

    Full Text Available We report on a new localized surface plasmon resonance (LSPR-based optical fiber (OF architecture with a potential in sensor applications. The LSPR-OF system is fabricated by immobilizing gold nanoparticles (GNPs in a hydrogel droplet polymerized on the fiber end face. This design has several advantages over earlier designs. It dramatically increase the number nanoparticles (NP available for sensing, it offers precise control over the NP density, and the NPs are positioned in a true 3D aqueous environment. The OF-hydrogel design is also compatible with low-cost manufacturing. The LSPR-OF platform can measure volumetric changes in a stimuli-responsive hydrogel or measure binding to receptors on the NP surface. It can also be used as a two-parameter sensor by utilizing both effects. We present results from proof-of-concept experiments exploring the properties of LSPR and interparticle distances of the GNP-hydrogel OF design by characterizing the distribution of distances between NPs in the hydrogel, the refractive index of the hydrogel and the LSPR attributes of peak position, amplitude and linewidth for hydrogel deswelling controlled with pH solutions.

  17. Behavioural repertoire of free-range laying hens indoors and outdoors, and in relation to distance from the shed.

    Science.gov (United States)

    Thuy Diep, A; Larsen, H; Rault, J-L

    2018-04-01

    Access to an outdoor area is believed to allow free-range hens to express a greater behavioural repertoire. However, very little research has been done in this area. We hypothesised that the type and frequency of behaviours would differ between areas that vary in their characteristics and distance from the shed. This preliminary study investigated the behaviour of free-range laying hens in indoor and outdoor areas on one commercial free-range farm, through video recordings and scan sampling of focal hens, with the aim of determining their behavioural repertoire and time budget. While ranging, hens spent most of their time foraging. Indoors, hens preened and rested. Behaviour in the wintergarden showed similarities to both the indoor and outdoor areas, with preening, resting and foraging behaviours. Differences were not in the main behavioural repertoire, but rather in terms of time budget, with access to the range and wintergarden encouraging exploration. There was no difference in the types of behaviours that hens performed in the outdoor range compared with inside the shed, but access to a wintergarden and the outdoor range were favoured by the hens for foraging. © 2018 Australian Veterinary Association.

  18. Effective distance adaptation traffic dispatching in software defined IP over optical network

    Science.gov (United States)

    Duan, Zhiwei; Li, Hui; Liu, Yuze; Ji, Yuefeng; Li, Hongfa; Lin, Yi

    2017-10-01

    The rapid growth of IP traffic has contributed to the wide deployment of optical devices (ROADM/OXC, etc.). Meanwhile, with the emergence and application of high-performance network services such as ultra-high video transmission, people are increasingly becoming more and more particular about the quality of service (QoS) of network. However, the pass-band shape of WSSs which is utilized in the ROADM/OXC is not ideal, causing narrowing of spectrum. Spectral narrowing can lead to signal impairment. Therefore, guard-bands need to be inserted between adjacent paths. In order to minimize the bandwidth waste due to guard bands, we propose an effective distance-adaptation traffic dispatching algorithm in IP over optical network based on SDON architecture. We use virtualization technology to set up virtual resources direct links by extracting part of the resources on paths which meet certain specific constraints. We also assign different bandwidth to each IP request based on path length. There is no need for guard-bands between the adjacent paths on the virtual link, which can effectively reduce the number of guard-bands and save the spectrum.

  19. Agreement between intraoperative measurements and optical coherence tomography of the limbus-insertion distance of the extraocular muscles.

    Science.gov (United States)

    de-Pablo-Gómez-de-Liaño, L; Fernández-Vigo, J I; Ventura-Abreu, N; Morales-Fernández, L; García-Feijóo, J; Gómez-de-Liaño, R

    2016-12-01

    To assess the agreement between intraoperative measurements of the limbus-insertion distance of the extraocular muscles with those measured by spectral domain optical coherence tomography. An analysis was made of a total of 67 muscles of 21 patients with strabismus. The limbus-insertion distance of the horizontal rectus muscles were measured using pre-operative SD-OCT and intra-operatively in 2 ways: 1) direct, after a conjunctival dissection in patients who underwent surgery, or 2) transconjunctival in patients who were treated with botulinum toxin, or in those who were not going to be operated. The intraclass correlation coefficient and Bland-Altman plots were calculated to determine the concordance between the 2 methods. The mean age was 45.9 ±20.9 years (range 16 to 85), with 52% being women. The percentage of identification by direct intraoperative measurement was 95.6% (22/23), by transconjunctival intraoperative measurement 90.9% (40/44), and by OCT 85% (57/67), with 22 muscles finally being analysed for the agreement study between direct intraoperative measurement and OCT measurements, and 35 muscles for the agreement between transconjuctival intraoperative measurement and OCT. The intraclass correlation coefficient showed good agreement with OCT and direct intraoperative measurements (0.931; 95% confidence interval (95% CI): 0.839-0.972; P<.001), and with transconjunctival intraoperative measurements (0.889; 95% CI: 0.790-0.942; P<.001). The SD-OCT is an effective technique to measure the distance from the insertion of the horizontal rectus muscles to the limbus, with a high agreement with intraoperative measurements being demonstrated. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  20. High-Capacity Short-Range Optical Communication Links

    DEFF Research Database (Denmark)

    Tatarczak, Anna

    Over the last decade, we have observed a tremendous spread of end-user mobile devices. The user base of a mobile application can grow or shrink by millions per day. This situation creates a pressing need for highly scalable server infrastructure; a need nowadays satisfied through cloud computing...... offered by data centers. As the popularity of cloud computing soars, the demand for high-speed, short-range data center links grows. Vertical cavity surface emitting lasers (VCSEL) and multimode fibers (MMF) prove especially well-suited for such scenarios. VCSELs have high modulation bandwidths......, we achieve 10 Gbps over 400 m and then conrm the approach in an optimized system at 25 Gbps over 300 m. The techniques described in this thesis leverage additional degrees of freedom to better utilize the available resources of short-range links. The proposed schemes enable higher speeds and longer...

  1. THE PLASMA ENVIRONMENT IN COMETS OVER A WIDE RANGE OF HELIOCENTRIC DISTANCES: APPLICATION TO COMET C/2006 P1 (MCNAUGHT)

    Energy Technology Data Exchange (ETDEWEB)

    Shou, Y.; Combi, M.; Gombosi, T.; Toth, G. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI (United States); Jia, Y.-D. [IGPP, and EPSS, University of California, Los Angeles, CA 90095 (United States); Rubin, M. [Physikalisches Institut, University of Bern, Sidlerstrasse. 5, CH-3012 Bern (Switzerland)

    2015-08-20

    On 2007 January 12, comet C/2006 P1 (McNaught) passed its perihelion at 0.17 AU. Abundant remote observations offer plenty of information on the neutral composition and neutral velocities within 1 million kilometers of the comet nucleus. In early February, the Ulysses spacecraft made an in situ measurement of the ion composition, plasma velocity, and magnetic field when passing through the distant ion tail and the ambient solar wind. The measurement by Ulysses was made when the comet was at around 0.8 AU. With the constraints provided by remote and in situ observations, we simulated the plasma environment of Comet C/2006 P1 (McNaught) using a multi-species comet MHD model over a wide range of heliocentric distances from 0.17 to 1.75 AU. The solar wind interaction of the comet at various locations is characterized and typical subsolar standoff distances of the bow shock and contact surface are presented and compared to analytic solutions. We find the variation in the bow shock standoff distances at different heliocentric distances is smaller than the contact surface. In addition, we modified the multi-species model for the case when the comet was at 0.7 AU and achieved comparable water group ion abundances, proton densities, plasma velocities, and plasma temperatures to the Ulysses/SWICS and SWOOPS observations. We discuss the dominating chemical reactions throughout the comet-solar wind interaction region and demonstrate the link between the ion composition near the comet and in the distant tail as measured by Ulysses.

  2. THE PLASMA ENVIRONMENT IN COMETS OVER A WIDE RANGE OF HELIOCENTRIC DISTANCES: APPLICATION TO COMET C/2006 P1 (MCNAUGHT)

    International Nuclear Information System (INIS)

    Shou, Y.; Combi, M.; Gombosi, T.; Toth, G.; Jia, Y.-D.; Rubin, M.

    2015-01-01

    On 2007 January 12, comet C/2006 P1 (McNaught) passed its perihelion at 0.17 AU. Abundant remote observations offer plenty of information on the neutral composition and neutral velocities within 1 million kilometers of the comet nucleus. In early February, the Ulysses spacecraft made an in situ measurement of the ion composition, plasma velocity, and magnetic field when passing through the distant ion tail and the ambient solar wind. The measurement by Ulysses was made when the comet was at around 0.8 AU. With the constraints provided by remote and in situ observations, we simulated the plasma environment of Comet C/2006 P1 (McNaught) using a multi-species comet MHD model over a wide range of heliocentric distances from 0.17 to 1.75 AU. The solar wind interaction of the comet at various locations is characterized and typical subsolar standoff distances of the bow shock and contact surface are presented and compared to analytic solutions. We find the variation in the bow shock standoff distances at different heliocentric distances is smaller than the contact surface. In addition, we modified the multi-species model for the case when the comet was at 0.7 AU and achieved comparable water group ion abundances, proton densities, plasma velocities, and plasma temperatures to the Ulysses/SWICS and SWOOPS observations. We discuss the dominating chemical reactions throughout the comet-solar wind interaction region and demonstrate the link between the ion composition near the comet and in the distant tail as measured by Ulysses

  3. Short-range structure of barium tellurite glasses and its correlation with stress-optic response

    Science.gov (United States)

    Kaur, Amarjot; Khanna, Atul; Fábián, Margit

    2018-06-01

    The atomic parameters of metal ion-oxygen speciation such as bond-lengths and nearest neighbor distances for Ba-O, Te-O and O-O pairs, co-ordination numbers and bond angle distributions for O-Ba-O, O-Te-O and O-O-O linkages are determined by neutron diffraction and Reverse Monte Carlo simulations on the series of xBaO-(100-x)TeO2 glasses containing 10, 15 and 20 mol% BaO. The glass network depolymerizes and the average Te-O co-ordination number decreases from 3.60 ± 0.02 to 3.48 ± 0.02 with increase in BaO concentration. Te-O bond lengths are in the range: 1.97 ± 0.01–1.92 ± 0.01 Å. Ba2+ is mostly in octahedral coordination and the Ba-O bond lengths are in the range: 2.73 ± 0.01 to 2.76 ± 0.03 Å. Te-O co-ordination number is also determined by Raman spectroscopy and it shows good agreement with the neutron data. The short-range structural properties i.e. metal ion coordination number (Nc) and bond lengths (d) were correlated with the stress-optic response. The bonding characteristic, Br values were determined from the structural data of xBaO-(100-x)TeO2 glasses and were used to predict the stress-induced birefringence properties.

  4. Many faces of compact objects: distance, optical extinction and multi-wavelength behaviour

    International Nuclear Information System (INIS)

    Corbel, Stephane

    1999-01-01

    This thesis is devoted to a multi-wavelength study of accretion-ejection phenomena around compact stars (black holes and neutron stars). The first part of this manuscript describes problems related to the determination of the distance and the optical extinction to compact objects - fundamental parameters for the evaluation of the energy budget of these systems. To this end, the structure and the dynamics of the Galaxy are studied by observations of the atomic and molecular gas along the line of sight to compact stars. This method leads to the first evaluation of the distance to two Soft Gamma Repeaters: SGR 1806-20 and SGR 1627-41. We then draw some conclusions on the nature of these sources of recurrent gamma-ray bursts. The above method is then applied to two X-ray binaries: Cir X-1 and GX 339-4. In the second part of this thesis, we present a multi-wavelength study of the Galactic black hole candidate GX 339-4. We first discuss the characteristics of the radio emission from GX 339-4. In 1998, GX 339-4 underwent a transition to a soft-high X-ray state and observations in three wavelength regimes (radio, soft and hard X-rays) revealed new patterns of behaviour. This allowed us to constrain the region of origin of the radio emission (a compact jet) in GX 339-4 and allowed a better understanding of the physical coupling between accretion and ejection in GX 339-4. An analogy with the black hole candidate Cyg X-1 is then presented. Finally, these results are discussed in the context of micro-quasars and active galactic nuclei in order to gain a deeper insight into the accretion-ejection coupling around compact objects. (author) [fr

  5. Multi-distance diffuse optical spectroscopy with a single optode via hypotrochoidal scanning.

    Science.gov (United States)

    Applegate, Matthew B; Roblyer, Darren

    2018-02-15

    Frequency-domain diffuse optical spectroscopy (FD-DOS) is an established technique capable of determining optical properties and chromophore concentrations in biological tissue. Most FD-DOS systems use either manually positioned, handheld probes or complex arrays of source and detector fibers to acquire data from many tissue locations, allowing for the generation of 2D or 3D maps of tissue. Here, we present a new method to rapidly acquire a wide range of source-detector (SD) separations by mechanically scanning a single SD pair. The source and detector fibers are mounted on a scan head that traces a hypotrochoidal pattern over the sample that, when coupled with a high-speed FD-DOS system, enables the rapid collection of dozens of SD separations for depth-resolved imaging. We demonstrate that this system has an average error of 4±2.6% in absorption and 2±1.8% in scattering across all SD separations. Additionally, by linearly translating the device, the size and location of an absorbing inhomogeneity can be determined through the generation of B-scan images in a manner conceptually analogous to ultrasound imaging. This work demonstrates the potential of single optode diffuse optical scanning for depth resolved visualization of heterogeneous biological tissues at near real-time rates.

  6. High resolution kilometric range optical telemetry in air by radio frequency phase measurement

    Energy Technology Data Exchange (ETDEWEB)

    Guillory, Joffray; García-Márquez, Jorge; Truong, Daniel; Wallerand, Jean-Pierre [Laboratoire Commun de Métrologie LNE-Cnam (LCM), LNE, 1 rue Gaston Boissier, 75015 Paris (France); Šmíd, Radek [Laboratoire Commun de Métrologie LNE-Cnam (LCM), LNE, 1 rue Gaston Boissier, 75015 Paris (France); Institute of Scientific Instruments of the CAS, Kralovopolska 147, 612 64 Brno (Czech Republic); Alexandre, Christophe [Centre d’Études et de Recherche en Informatique et Communications (CEDRIC), Cnam, 292 rue St-Martin, 75003 Paris (France)

    2016-07-15

    We have developed an optical Absolute Distance Meter (ADM) based on the measurement of the phase accumulated by a Radio Frequency wave during its propagation in the air by a laser beam. In this article, the ADM principle will be described and the main results will be presented. In particular, we will emphasize how the choice of an appropriate photodetector can significantly improve the telemeter performances by minimizing the amplitude to phase conversion. Our prototype, tested in the field, has proven its efficiency with a resolution better than 15 μm for a measurement time of 10 ms and distances up to 1.2 km.

  7. Limitations in distance and frequency due to chromatic dispersion in fibre-optic microwave and millimeter-wave links

    DEFF Research Database (Denmark)

    Gliese, Ulrik Bo; Nielsen, Søren Nørskov; Nielsen, Søren Nørskov

    1996-01-01

    Chromatic dispersion significantly limits the distance and/or frequency in fibre-optic microwave and millimeter-wave links based on direct detection due to a decrease of the carrier to noise ratio. The limitations in links based on coherent remote heterodyne detection, however, are far less...

  8. Overpotential-induced lability of the electronic overlap factor in long-range electrochemical electron transfer: charge and distance dependence

    DEFF Research Database (Denmark)

    Kornyshev, A. A.; Kuznetsov, A. M.; Nielsen, Jens Ulrik

    2000-01-01

    Long-distance electrochemical electron transfer exhibits approximately exponential dependence on the electron transfer distance. On the basis of a jellium model of the metal surface we show that the slope of the logarithm of the current vs. the transfer distance also depends strongly...

  9. Enhancing the use of Argos satellite data for home range and long distance migration studies of marine animals.

    Directory of Open Access Journals (Sweden)

    Xavier Hoenner

    Full Text Available Accurately quantifying animals' spatial utilisation is critical for conservation, but has long remained an elusive goal due to technological impediments. The Argos telemetry system has been extensively used to remotely track marine animals, however location estimates are characterised by substantial spatial error. State-space models (SSM constitute a robust statistical approach to refine Argos tracking data by accounting for observation errors and stochasticity in animal movement. Despite their wide use in ecology, few studies have thoroughly quantified the error associated with SSM predicted locations and no research has assessed their validity for describing animal movement behaviour. We compared home ranges and migratory pathways of seven hawksbill sea turtles (Eretmochelys imbricata estimated from (a highly accurate Fastloc GPS data and (b locations computed using common Argos data analytical approaches. Argos 68(th percentile error was 4 km for LC ≤ 0. Argos error structure was highly longitudinally skewed and was, for all LC, adequately modelled by a Student's t distribution. Both habitat use and migration routes were best recreated using SSM locations post-processed by re-adding good Argos positions (LC 1, 2 and 3 and filtering terrestrial points (mean distance to migratory tracks ± SD = 2.2 ± 2.4 km; mean home range overlap and error ratio = 92.2% and 285.6 respectively. This parsimonious and objective statistical procedure however still markedly overestimated true home range sizes, especially for animals exhibiting restricted movements. Post-processing SSM locations nonetheless constitutes the best analytical technique for remotely sensed Argos tracking data and we therefore recommend using this approach to rework historical Argos datasets for better estimation of animal spatial utilisation for research and evidence-based conservation purposes.

  10. US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 3: Advanced networks and economics

    Science.gov (United States)

    1986-10-01

    This study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

  11. Fiber optics frequency comb enabled linear optical sampling with operation wavelength range extension.

    Science.gov (United States)

    Liao, Ruolin; Wu, Zhichao; Fu, Songnian; Zhu, Shengnan; Yu, Zhe; Tang, Ming; Liu, Deming

    2018-02-01

    Although the linear optical sampling (LOS) technique is powerful enough to characterize various advanced modulation formats with high symbol rates, the central wavelength of a pulsed local oscillator (LO) needs to be carefully set according to that of the signal under test, due to the coherent mixing operation. Here, we experimentally demonstrate wideband LOS enabled by a fiber optics frequency comb (FOFC). Meanwhile, when the broadband FOFC acts as the pulsed LO, we propose a scheme to mitigate the enhanced sampling error arising in the non-ideal response of a balanced photodetector. Finally, precise characterizations of arbitrary 128 Gbps PDM-QPSK wavelength channels from 1550 to 1570 nm are successfully achieved, when a 101.3 MHz frequency spaced comb with a 3 dB spectral power ripple of 20 nm is used.

  12. Optical pulling of airborne absorbing particles and smut spores over a meter-scale distance with negative photophoretic force

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jinda; Hart, Adam G.; Li, Yong-qing, E-mail: liy@ecu.edu [Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353 (United States)

    2015-04-27

    We demonstrate optical pulling of single light-absorbing particles and smut spores in air over a meter-scale distance using a single collimated laser beam based on negative photophoretic force. The micron-sized particles are pulled towards the light source at a constant speed of 1–10 cm/s in the optical pulling pipeline while undergoing transverse rotation at 0.2–10 kHz. The pulled particles can be manipulated and precisely positioned on the entrance window with an accuracy of ∼20 μm, and their chemical compositions can be characterized with micro-Raman spectroscopy.

  13. RFID-over-Fiber system for agricultural exploitations - Wireless track and trace with range extension using optical fiber

    DEFF Research Database (Denmark)

    Madsen, Peter; Suhr, Lau Frejstrup; Cavalcante, Lucas Costa Pereira

    2015-01-01

    This paper proposes and demonstrates an RFIDover-Fiber wireless track and trace system using active RFID tags and operating over distances up to 30 km of optical fiber and 35 meters of wireless readability......This paper proposes and demonstrates an RFIDover-Fiber wireless track and trace system using active RFID tags and operating over distances up to 30 km of optical fiber and 35 meters of wireless readability...

  14. Measurement range of phase retrieval in optical surface and wavefront metrology

    International Nuclear Information System (INIS)

    Brady, Gregory R.; Fienup, James R.

    2009-01-01

    Phase retrieval employs very simple data collection hardware and iterative algorithms to determine the phase of an optical field. We have derived limitations on phase retrieval, as applied to optical surface and wavefront metrology, in terms of the speed of beam (i.e., f-number or numerical aperture) and amount of aberration using arguments based on sampling theory and geometrical optics. These limitations suggest methodologies for expanding these ranges by increasing the complexity of the measurement arrangement, the phase-retrieval algorithm, or both. We have simulated one of these methods where a surface is measured at unusual conjugates

  15. Foraging range, habitat use and minimum flight distances of East Atlantic Light-bellied Brent Geese Branta bernicla hrota in their spring staging areas

    DEFF Research Database (Denmark)

    Clausen, Kevin Kuhlmann; Clausen, Preben; Hounisen, Jens Peder

    2013-01-01

    Global Positioning System (GPS) satellite telemetry was used to determine the foraging range, habitat use and minimum flight distances for individual East Atlantic Light-bellied Brent Geese Branta bernicla hrota at two spring staging areas in Denmark. Foraging ranges (mean ± s.d. = 53.0 ± 23.4 km...

  16. Distance and velocity estimation using optical flow from a monocular camera

    NARCIS (Netherlands)

    Ho, H.W.; de Croon, G.C.H.E.; Chu, Q.

    2016-01-01

    Monocular vision is increasingly used in Micro Air Vehicles for navigation. In particular, optical flow, inspired by flying insects, is used to perceive vehicles’ movement with respect to the surroundings or sense changes in the environment. However, optical flow does not directly provide us the

  17. Distance and velocity estimation using optical flow from a monocular camera

    NARCIS (Netherlands)

    Ho, H.W.; de Croon, G.C.H.E.; Chu, Q.

    2017-01-01

    Monocular vision is increasingly used in micro air vehicles for navigation. In particular, optical flow, inspired by flying insects, is used to perceive vehicle movement with respect to the surroundings or sense changes in the environment. However, optical flow does not directly provide us the

  18. Flexible long-range surface plasmon polariton single-mode waveguide for optical interconnects

    DEFF Research Database (Denmark)

    Vernoux, Christian; Chen, Yiting; Markey, Laurent

    2018-01-01

    We present the design, fabrication and characterization of long-range surface plasmon polariton waveguide arrays with materials, mainly silicones, carefully selected with the aim to be used as mechanically flexible single-mode optical interconnections, the socalled "plasmonic arc" working at 1.55μm...

  19. Remote artificial eyes using micro-optical circuit for long-distance 3D imaging perception.

    Science.gov (United States)

    Thammawongsa, Nopparat; Yupapin, Preecha P

    2016-01-01

    A small-scale optical device incorporated with an optical nano-antenna is designed to operate as the remote artificial eye using a tiny conjugate mirror. A basic device known as a conjugate mirror can be formed using the artificial eye device, the partially reflected light intensities from input source are interfered and the 3D whispering gallery modes formed within the ring centers, which can be modulated and propagated to the object. The image pixel is obtained at the center ring and linked with the optic nerve in the remote area via the nano-antenna, which is useful for blind people.

  20. Optical haze of randomly arranged silver nanowire transparent conductive films with wide range of nanowire diameters

    Directory of Open Access Journals (Sweden)

    M. Marus

    2018-03-01

    Full Text Available The effect of the diameter of randomly arranged silver nanowires on the optical haze of silver nanowire transparent conductive films was studied. Proposed simulation model behaved similarly with the experimental results, and was used to theoretically study the optical haze of silver nanowires with diameters in the broad range from 30 nm and above. Our results show that a thickening of silver nanowires from 30 to 100 nm results in the increase of the optical haze up to 8 times, while from 100 to 500 nm the optical haze increases only up to 1.38. Moreover, silver nanowires with diameter of 500 nm possess up to 5% lower optical haze and 5% higher transmittance than 100 nm thick silver nanowires for the same 10-100 Ohm/sq sheet resistance range. Further thickening of AgNWs can match the low haze of 30 nm thick AgNWs, but at higher transmittance. The results obtained from this work allow deeper analysis of the silver nanowire transparent conductive films from the perspective of the diameter of nanowires for various optoelectronic devices.

  1. CMOS Receiver Front-ends for Gigabit Short-Range Optical Communications

    CERN Document Server

    Aznar, Francisco; Calvo Lopez, Belén

    2013-01-01

    This book describes optical receiver solutions integrated in standard CMOS technology, attaining high-speed short-range transmission within cost-effective constraints.  These techniques support short reach applications, such as local area networks, fiber-to-the-home and multimedia systems in cars and homes. The authors show how to implement the optical front-end in the same technology as the subsequent digital circuitry, leading to integration of the entire receiver system in the same chip.  The presentation focuses on CMOS receiver design targeting gigabit transmission along a low-cost, standardized plastic optical fiber up to 50m in length.  This book includes a detailed study of CMOS optical receiver design – from building blocks to the system level. Reviews optical communications, including long-haul transmission systems and emerging applications focused on short-range; Explains necessary fundamentals, such as characteristics of a data signal, system requirements affecting receiver design and key par...

  2. Alfalfa discovery of the nearby gas-rich dwarf galaxy Leo P. IV. Distance measurement from LBT optical imaging

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J.; Rhode, Katherine L. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Dolphin, Andrew, E-mail: kmcquinn@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: berg@astro.umn.edu, E-mail: jcannon@macalester.edu, E-mail: rhode@astro.indiana.edu, E-mail: slaz@astro.indiana.edu, E-mail: betsey@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States)

    2013-12-01

    Leo P is a low-luminosity dwarf galaxy discovered through the blind H I Arecibo Legacy Fast ALFA survey. The H I and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with both active star formation and an underlying older population, as well as an extremely low oxygen abundance. Here, we measure the distance to Leo P by applying the tip of the red giant branch (TRGB) distance method to photometry of the resolved stellar population from new Large Binocular Telescope V and I band imaging. We measure a distance modulus of 26.19{sub −0.50}{sup +0.17} mag corresponding to a distance of 1.72{sub −0.40}{sup +0.14} Mpc. Although our photometry reaches 3 mag below the TRGB, the sparseness of the red giant branch yields higher uncertainties on the lower limit of the distance. Leo P is outside the Local Group with a distance and velocity consistent with the local Hubble flow. While located in a very low-density environment, Leo P lies within ∼0.5 Mpc of a loose association of dwarf galaxies which include NGC 3109, Antlia, Sextans A, and Sextans B, and 1.1 Mpc away from its next nearest neighbor, Leo A. Leo P is one of the lowest metallicity star-forming galaxies known in the nearby universe, comparable in metallicity to I Zw 18 and DDO 68, but with stellar characteristics similar to dwarf spheriodals (dSphs) in the Local Volume such as Carina, Sextans, and Leo II. Given its physical properties and isolation, Leo P may provide an evolutionary link between gas-rich dwarf irregular galaxies and dSphs that have fallen into a Local Group environment and been stripped of their gas.

  3. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range

    Science.gov (United States)

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154

  4. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range.

    Science.gov (United States)

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-04-13

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications.

  5. Long distance high power optical laser fiber break detection and continuity monitoring systems and methods

    Science.gov (United States)

    Rinzler, Charles C.; Gray, William C.; Faircloth, Brian O.; Zediker, Mark S.

    2016-02-23

    A monitoring and detection system for use on high power laser systems, long distance high power laser systems and tools for performing high power laser operations. In particular, the monitoring and detection systems provide break detection and continuity protection for performing high power laser operations on, and in, remote and difficult to access locations.

  6. Measurement of the cosmic optical background using the long range reconnaissance imager on New Horizons.

    Science.gov (United States)

    Zemcov, Michael; Immel, Poppy; Nguyen, Chi; Cooray, Asantha; Lisse, Carey M; Poppe, Andrew R

    2017-04-11

    The cosmic optical background is an important observable that constrains energy production in stars and more exotic physical processes in the universe, and provides a crucial cosmological benchmark against which to judge theories of structure formation. Measurement of the absolute brightness of this background is complicated by local foregrounds like the Earth's atmosphere and sunlight reflected from local interplanetary dust, and large discrepancies in the inferred brightness of the optical background have resulted. Observations from probes far from the Earth are not affected by these bright foregrounds. Here we analyse the data from the Long Range Reconnaissance Imager (LORRI) instrument on NASA's New Horizons mission acquired during cruise phase outside the orbit of Jupiter, and find a statistical upper limit on the optical background's brightness similar to the integrated light from galaxies. We conclude that a carefully performed survey with LORRI could yield uncertainties comparable to those from galaxy counting measurements.

  7. Scanning laser topography and scanning laser polarimetry: comparing both imaging methods at same distances from the optic nerve head.

    Science.gov (United States)

    Kremmer, Stephan; Keienburg, Marcus; Anastassiou, Gerasimos; Schallenberg, Maurice; Steuhl, Klaus-Peter; Selbach, J Michael

    2012-01-01

    To compare the performance of scanning laser topography (SLT) and scanning laser polarimetry (SLP) on the rim of the optic nerve head and its surrounding area and thereby to evaluate whether these imaging technologies are influenced by other factors beyond the thickness of the retinal nerve fiber layer (RNFL). A total of 154 eyes from 5 different groups were examined: young healthy subjects (YNorm), old healthy subjects (ONorm), patients with normal tension glaucoma (NTG), patients with open-angle glaucoma and early glaucomatous damage (OAGE) and patients with open-angle glaucoma and advanced glaucomatous damage (OAGA). SLT and SLP measurements were taken. Four concentric circles were superimposed on each of the images: the first one measuring at the rim of the optic nerve head (1.0 ONHD), the next measuring at 1.25 optic nerve head diameters (ONHD), at 1.5 ONHD and at 1.75 ONHD. The aligned images were analyzed using GDx/NFA software. Both methods showed peaks of RNFL thickness in the superior and inferior segments of the ONH. The maximum thickness, registered by the SLT device was at the ONH rim where the SLP device tended to measure the lowest values. SLT measurements at the ONH were influenced by other tissues besides the RNFL like blood vessels and glial tissues. SLT and SLP were most strongly correlated at distances of 1.25 and 1.5 ONHD. While both imaging technologies are valuable tools in detecting glaucoma, measurements at the ONH rim should be interpreted critically since both methods might provide misleading results. For the assessment of the retinal nerve fiber layer we would like to recommend for both imaging technologies, SLT and SLP, measurements in 1.25 and 1.5 ONHD distance of the rim of the optic nerve head.

  8. Cost-effective up to 40 Gbit/s transmission performance of 1310 nm directly modulated lasers for short to medium range distances

    NARCIS (Netherlands)

    Huiszoon, B.; Jonker, R.J.W.; Bennekom, van P.K.; Khoe, G.D.; Waardt, de H.

    2005-01-01

    This paper presents successful 20 and 40 Gb/s potentially low-cost transmission experiments using 1310 nm directly modulated distributed feedback lasers (DMLs) in the very-short- to medium-range distances. This paper will recommend operating conditions for error-free transmission at these bit rates

  9. Optical timing receiver for the NASA laser ranging system. Part I. Constant-fraction discriminator

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1975-01-01

    Position-resolution capabilities of the NASA laser ranging system are essentially determined by time-resolution capabilities of its optical timing receiver. The optical timing receiver consists of a fast photoelectric device, primarily a standard of microchannel-plate-type photomultiplier or an avalanche photodiode detector, a timing discriminator, a high-precision time-interval digitizer, and a signal-processing system. The time-resolution capabilities of the receiver are determined by the photoelectron time spread of the photoelectric device, the time walk and resolution characteristics of the timing discriminator, and the time-interval digitizer. It is thus necessary to evaluate available fast photoelectronic devices with respect to their time-resolution capabilities, and to design a very low time walk timing discriminator and a high-precision time digitizer which will be used in the laser ranging system receiver. (auth)

  10. Tunable femtosecond laser in the visible range with an intracavity frequency-doubled optical parametric oscillator

    International Nuclear Information System (INIS)

    Zhu Jiang-Feng; Xu Liang; Lin Qing-Feng; Zhong Xin; Han Hai-Nian; Wei Zhi-Yi

    2013-01-01

    We demonstrated experimentally a synchronously pumped intracavity frequency-doubled femtosecond optical parametric oscillator (OPO) using a periodically-poled lithium niobate (PPLN) as the nonlinear material in combination with a lithium triborate (LBO) as the doubling crystal. A Kerr-lens-mode-locked (KLM) Ti:sapphire oscillator at the wavelength of 790 nm was used as the pump source, which was capable of generating pulses with a duration as short as 117 fs. A tunable femtosecond laser covering the 624–672 nm range was realized by conveniently adjusting the OPO cavity length. A maximum average output power of 260 mW in the visible range was obtained at the pump power of 2.2 W, with a typical pulse duration of 205 fs assuming a sech 2 pulse profile. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  11. Static and Dynamic Accuracy of an Innovative Miniaturized Wearable Platform for Short Range Distance Measurements for Human Movement Applications

    Directory of Open Access Journals (Sweden)

    Stefano Bertuletti

    2017-06-01

    Full Text Available Magneto-inertial measurement units (MIMU are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. To overcome this limitation, we developed a wearable platform specifically designed for human movement analysis applications, which integrates a MIMU and an Infrared Time-of-Flight proximity sensor (IR-ToF, allowing for the estimate of inter-object distance. We proposed a thorough testing protocol for evaluating the IR-ToF sensor performances under experimental conditions resembling those encountered during gait. In particular, we tested the sensor performance for different (i target colors; (ii sensor-target distances (up to 200 mm and (iii sensor-target angles of incidence (AoI (up to 60 ∘ . Both static and dynamic conditions were analyzed. A pendulum, simulating the oscillation of a human leg, was used to generate highly repeatable oscillations with a maximum angular velocity of 6 rad/s. Results showed that the IR-ToF proximity sensor was not sensitive to variations of both distance and target color (except for black. Conversely, a relationship between error magnitude and AoI values was found. For AoI equal to 0 ∘ , the IR-ToF sensor performed equally well both in static and dynamic acquisitions with a distance mean absolute error <1.5 mm. Errors increased up to 3.6 mm (static and 11.9 mm (dynamic for AoI equal to ± 30 ∘ , and up to 7.8 mm (static and 25.6 mm (dynamic for AoI equal to ± 60 ∘ . In addition, the wearable platform was used during a preliminary experiment for the estimation of the inter-foot distance on a single healthy subject while walking. In conclusion, the combination of magneto-inertial unit and IR-ToF technology represents a valuable alternative solution in terms of accuracy, sampling frequency, dimension and power consumption

  12. Generating a stationary infinite range tractor force via a multimode optical fibre

    Science.gov (United States)

    Ebongue, C. A.; Holzmann, D.; Ostermann, S.; Ritsch, H.

    2017-06-01

    Optical fibres confine and guide light almost unattenuated and thus convey light forces to polarizable nano-particles over very long distances. Radiation pressure forces arise from scattering of guided photons into free space while gradient forces are based on coherent scattering between different fibre modes or propagation directions. Interestingly, even scattering between co-propagating modes induces longitudinal forces as the transverse confinement of the light modes creates mode dependent longitudinal wave-vectors and photon momenta. We generalize a proven scattering matrix based approach to calculate single as well as inter-particle forces to include several forward and backward propagating modes. We show that an injection of the higher order mode only in a two mode fibre will induce a stationary tractor force against the injection direction, when the mode coupling to the lower order mode dominates against backscattering and free space losses. Generically this arises for non-absorbing particles at the centre of a waveguide. The model also gives improved predictions for inter-particle forces in evanescent nanofibre fields as experimentally observed recently. Surprisingly strong tractor forces can also act on whole optically bound arrays.

  13. Isolation by environmental distance in mobile marine species: molecular ecology of franciscana dolphins at their southern range.

    Science.gov (United States)

    Mendez, Martin; Rosenbaum, Howard C; Subramaniam, Ajit; Yackulic, Charles; Bordino, Pablo

    2010-06-01

    The assessment of population structure is a valuable tool for studying the ecology of endangered species and drafting conservation strategies. As we enhance our understanding about the structuring of natural populations, it becomes important that we also understand the processes behind these patterns. However, there are few rigorous assessments of the influence of environmental factors on genetic patterns in mobile marine species. Given their dispersal capabilities and localized habitat preferences, coastal cetaceans are adequate study species for evaluating environmental effects on marine population structure. The franciscana dolphin, a rare coastal cetacean endemic to the Western South Atlantic, was studied to examine these issues. We analysed genetic data from the mitochondrial DNA and 12 microsatellite markers for 275 franciscana samples utilizing frequency-based, maximum-likelihood and Bayesian algorithms to assess population structure and migration patterns. This information was combined with 10 years of remote sensing environmental data (chlorophyll concentration, water turbidity and surface temperature). Our analyses show the occurrence of genetically isolated populations within Argentina, in areas that are environmentally distinct. Combined evidence of genetic and environmental structure suggests that isolation by distance and a process here termed isolation by environmental distance can explain the observed correlations. Our approach elucidated important ecological and conservation aspects of franciscana dolphins, and has the potential to increase our understanding of ecological processes influencing genetic patterns in other marine species.

  14. Optical levitation and long-working-distance trapping: From spherical up to high aspect ratio ellipsoidal particles

    International Nuclear Information System (INIS)

    Mihiretie, Besira; Loudet, Jean-Christophe; Pouligny, Bernard

    2013-01-01

    Radiation pressure forces from a moderately focused vertical laser beam are used to levitate transparent particles, a few micrometers in size. Having recalled basic results about levitation of spheres, and applications to long-working distance trapping, we turn to ellipsoid-shaped particles. Experiments are carried out with polystyrene particles, inside a glass chamber filled with water. The particles are lifted up to contact with the chamber top surface. We examine particle equilibrium in such conditions and show that the system “bifurcates” between static on-axis equilibrium with short ellipsoids, to sustained oscillations with longer ones. A similar Hopf bifurcation is found using a simple ray-optics model of the laser-ellipsoid interaction, providing a qualitative account of the observed oscillations. -- Highlights: ► We study optical levitation of non-spherical micrometer-sized particles. ► Short ellipsoids get trapped on laser beam axis, similarly to spheres. ► Long ellipsoids oscillate, through coupled translation and tilt motions. ► We propose a simple ray-optics model of light interaction with an ellipsoid. ► From computed radiation pressure forces, we explain the observed oscillations

  15. Optical properties of InGaN thin films in the entire composition range

    Science.gov (United States)

    Kazazis, S. A.; Papadomanolaki, E.; Androulidaki, M.; Kayambaki, M.; Iliopoulos, E.

    2018-03-01

    The optical properties of thick InGaN epilayers, with compositions spanning the entire ternary range, are studied in detail. High structural quality, single phase InxGa1-xN (0001) films were grown heteroepitaxially by radio-frequency plasma assisted molecular-beam epitaxy on freestanding GaN substrates. Their emission characteristics were investigated by low temperature photoluminescence spectroscopy, whereas variable angle spectroscopic ellipsometry was applied to determine the complex dielectric function of the films, in the 0.55-4.0 eV photon range. Photoluminescence lines were intense and narrow, in the range of 100 meV for Ga-rich InGaN films (x 0.6). The composition dependence of the strain-free emission energy was expressed by a bowing parameter of b = 2.70 ± 0.12 eV. The films' optical dielectric function dispersion was obtained by the analysis of the ellipsometric data employing a Kramers-Kronig consistent parameterized optical model. The refractive index dispersion was obtained for alloys in the entire composition range, and the corresponding values at the band edge show a parabolic dependence on the InN mole fraction expressed by a bowing parameter of b = 0.81 ± 0.04. The bowing parameter describing the fundamental energy bandgap was deduced to be equal to 1.66 ± 0.07 eV, consistent with the ab initio calculations for statistically random (non-clustered) InGaN alloys.

  16. Variability in the range of inter-anterior superior iliac spine distance and its correlation with femoral head centre. A prospective computed tomography study of 200 adults

    International Nuclear Information System (INIS)

    Mullaji, Arun; Shetty, Gautam M.; Kanna, Raj; Sharma, Amit

    2010-01-01

    The anterior superior iliac spine (ASIS) is commonly used to estimate the centre of the femoral head and assess limb alignment during surgical procedures. This study aimed to determine the range of inter-anterior superior iliac spine distances (IADs) and inter-femoral head centre distances (IFDs) among individuals and ascertain whether there is correlation between the IFD and the IAD. We also sought to determine whether gender, height and body mass index (BMI) had any influence on IAD and IFD. We prospectively measured IAD and IFD in 200 adults, using transverse computed tomography (CT) scans done for medical causes. We also calculated the distance between the pelvic midline and the centre of the femoral head (XY distance) from the measured IFD. The influence of gender, height and body-mass index on IAD and IFD, and the correlation of IAD with IFD, were also studied. The overall mean IAD, IFD and XY distances were 22.7 ± 1.6 cm, 16.0 ± 0.8 cm and 8.0 ± 0.4 cm, respectively. There was wide variation within the IAD range with 50% (100/200) of the subjects having their IAD within ±10 mm of the mean compared to 75.5% (151/200) of the subjects with IFD within ±10 mm of the mean. The probability that the mean XY distance would fall within 10 mm of the true femoral head centre in all subjects was 100%. The gender difference in IAD and IFD was statistically significant (P = 0.03 and P < 0.001, respectively), height and BMI had no influence, and the correlation of IAD with IFD was weak (0.35). Although the range of IADs showed wide variation among subjects, this study clearly demonstrated the narrow range of the XY distance and IFD in the study population and provides a useful and accurate basis for a new method to determine the femoral head centre clinically and intraoperatively. (orig.)

  17. Novel method of optical image registration in wide wavelength range using matrix of piezoelectric crystals

    Science.gov (United States)

    Pigarev, Aleksey V.; Bazarov, Timur O.; Fedorov, Vladimir V.; Ryabushkin, Oleg A.

    2018-02-01

    Most modern systems of the optical image registration are based on the matrices of photosensitive semiconductor heterostructures. However, measurement of radiation intensities up to several MW/cm2 -level using such detectors is a great challenge because semiconductor elements have low optical damage threshold. Reflecting or absorbing filters that can be used for attenuation of radiation intensity, as a rule, distort beam profile. Furthermore, semiconductor based devices have relatively narrow measurement wavelength bandwidth. We introduce a novel matrix method of optical image registration. This approach doesn't require any attenuation when measuring high radiation intensities. A sensitive element is the matrix made of thin transparent piezoelectric crystals that absorb just a small part of incident optical power. Each crystal element has its own set of intrinsic (acoustic) vibration modes. These modes can be exited due to the inverse piezoelectric effect when the external electric field is applied to the crystal sample providing that the field frequency corresponds to one of the vibration mode frequencies. Such piezoelectric resonances (PR) can be observed by measuring the radiofrequency response spectrum of the crystal placed between the capacitor plates. PR frequencies strongly depend on the crystal temperature. Temperature calibration of PR frequencies is conducted in the uniform heating conditions. In the case a crystal matrix is exposed to the laser radiation the incident power can be obtained separately for each crystal element by measuring its PR frequency kinetics providing that the optical absorption coefficient is known. The operating wavelength range of such sensor is restricted by the transmission bandwidth of the applied crystals. A plane matrix constituting of LiNbO3 crystals was assembled in order to demonstrate the possibility of application of the proposed approach. The crystal elements were placed between two electrodes forming a capacitor which

  18. Single-shot parallel full range complex Fourier-domain optical coherence tomography

    International Nuclear Information System (INIS)

    Huang Bingjie; Bu Peng; Nan Nan; Wang Xiangzhao

    2011-01-01

    We present a method of parallel full range complex Fourier-domain optical coherence tomography (FDOCT) that is capable of acquiring an artifacts-free two-dimensional (2-D) cross-sectional image, i.e. a full range B-scan tomogram, by a single shot of 2-D CCD camera. This method is based on a spatial carrier technique, in which the spatial carrier-frequency is instantaneously introduced into the 2-D spectral interferogram registered in parallel FDOCT by using a grating-generated reference beam. The spatial-carrier-contained 2-D spectral interferogram is processed through Fourier transformation to obtain a complex 2-D spectral interferogram. From the 2-D complex spectral interferomgram, a full range B-scan tomogram is reconstructed. The principle of our method is confirmed by imaging an onion sample.

  19. Training and assessment of experimental competencies from a distance: Optical spectrometry via the Internet

    Science.gov (United States)

    Thoms, L.-J.; Girwidz, R.

    2016-05-01

    Assessment of experimental competencies is not yet well established. We just began an empirical pilot study, too. This study aims to examine if secondary school students may successfully use a predefined remote lab activity to introduce themselves to atomic physics. The analysis of spectra is a fundamental component for the understanding of wave optics and color perception. Hence, every student should have the opportunity to conduct own optical emission experiments. Since spectrometers are expensive and an accurate calibration is necessary to achieve energy distribution spectra of high quality, we developed a remotely controlled laboratory. We evaluated the experimental set-up and the accompanying worksheet with groups of two to four students in a laboratory condition. Additionally, the emerged learning material was brought to school and tested as a homework activity with 9th-graders replacing the regular introduction to atomic physics. The results show that the experiment presented here can be used by ninth grade students and is useful in connection with the created material for the self-regulated introduction to atomic physics in the context of homework.

  20. Training and assessment of experimental competencies from a distance: Optical spectrometry via the Internet

    International Nuclear Information System (INIS)

    Thoms, L-J.; Girwidz, R.

    2015-01-01

    Assessment of experimental competencies is not yet well established. We just began an empirical pilot study, too. This study aims to examine if secondary school students may successfully use a predefined remote lab activity to introduce themselves to atomic physics. The analysis of spectra is a fundamental component for the understanding of wave optics and color perception. Hence, every student should have the opportunity to conduct own optical emission experiments. Since spectrometers are expensive and an accurate calibration is necessary to achieve energy distribution spectra of high quality, we developed a remotely controlled laboratory. We evaluated the experimental set-up and the accompanying worksheet with groups of two to four students in a laboratory condition. Additionally, the emerged learning material was brought to school and tested as a homework activity with 9.-graders replacing the regular introduction to atomic physics. The results show that the experiment presented here can be used by ninth grade students and is useful in connection with the created material for the self-regulated introduction to atomic physics in the context of homework.

  1. Tunable optical coherence tomography in the infrared range using visible photons

    Science.gov (United States)

    Paterova, Anna V.; Yang, Hongzhi; An, Chengwu; Kalashnikov, Dmitry A.; Krivitsky, Leonid A.

    2018-04-01

    Optical coherence tomography (OCT) is an appealing technique for bio-imaging, medicine, and material analysis. For many applications, OCT in mid- and far-infrared (IR) leads to significantly more accurate results. Reported mid-IR OCT systems require light sources and photodetectors which operate in mid-IR range. These devices are expensive and need cryogenic cooling. Here, we report a proof-of-concept demonstration of a wavelength tunable IR OCT technique with detection of only visible range photons. Our method is based on the nonlinear interference of frequency correlated photon pairs. The nonlinear crystal, introduced in the Michelson-type interferometer, generates photon pairs with one photon in the visible and another in the IR range. The intensity of detected visible photons depends on the phase and loss of IR photons, which interact with the sample under study. This enables us to characterize sample properties and perform imaging in the IR range by detecting visible photons. The technique possesses broad wavelength tunability and yields a fair axial and lateral resolution, which can be tailored to the specific application. The work contributes to the development of versatile 3D imaging and material characterization systems working in a broad range of IR wavelengths, which do not require the use of IR-range light sources and photodetectors.

  2. Comparison of Heidelberg Retina Tomograph with disc-macula distance to disc diameter ratio in diagnosing optic nerve hypoplasia.

    Science.gov (United States)

    Pang, Yi; Frantz, Kelly A

    2016-05-01

    To evaluate whether Heidelberg Retinal Tomograph (HRT) is a valid test for diagnosing congenital optic nerve hypoplasia (CONH) compared to the ratio of the distance between the centre of the optic disc and the centre of the macula and the mean optic disc diameter (DM:DD ratio). Furthermore, to determine the optimal cut-off value of HRT disc area to differentiate a hypoplastic disc from a normal optic disc. A total of 33 subjects with CONH (4-67 years old) and 160 normal subjects (5-65 years old) were recruited and underwent comprehensive eye examinations, fundus photography and HRT. Receiver operating characteristic curves for DM:DD ratio and HRT disc area were constructed based on data from the 46 CONH eyes and 160 control eyes. Mean (±S.D.) HRT disc area was 1.94 (±0.54) mm(2) for the control eyes and 0.84 (±0.35) mm(2) for the CONH eyes (p < 0.0001). The area under the curve (AUC) for DM:DD ratio was 0.83 (95% confidence interval: 0.76-0.90). The AUC for HRT disc area was 0.96 (95% confidence interval: 0.94-0.99). A statistically significant difference was found between AUC for HRT disc area and that for DM:DD ratio (p = 0.0004). The optimal cut-off value for HRT disc area was 1.42 mm(2) with 95% sensitivity and 85% specificity. The optimal cut-off value for DM:DD ratio was 3.20 with 78% sensitivity and 78% specificity. Both HRT and the DM:DD ratio are valid tests to aid diagnosis of CONH. HRT is superior to DM:DD ratio in diagnosing CONH with higher sensitivity and specificity. We suggest the optimal cut-off value for HRT disc area as 1.42 mm(2) in order to discriminate a hypoplastic disc from a normal optic disc. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  3. Impedance measurements on a fast transition-edge sensor for optical and near-infrared range

    International Nuclear Information System (INIS)

    Taralli, E; Portesi, C; Lolli, L; Monticone, E; Rajteri, M; Novikov, I; Beyer, J

    2010-01-01

    Impedance measurements of superconducting transition-edge sensors (TESs) are a powerful tool to obtain information about the TES thermal and electrical properties. We apply this technique to a 20 μm x 20 μm Ti/Au TES, suitable for application in the optical and near-infrared range, and extend the measurements up to 250 kHz in order to obtain a complete frequency response in the complex plane. From these measurements we obtain important thermal and electrical device parameters such as heat capacity C, thermal conductance G and effective thermal time constant τ eff that will be compared with the corresponding values obtained from noise measurements.

  4. Integrated-Optics Components Utilizing Long-Range Surface Plasmon Polaritons

    DEFF Research Database (Denmark)

    Boltasseva, Alexandra

    2004-01-01

    This thesis describes a new class of components for integrated optics, based on the propagation of long-range surface plasmon polaritons (LR-SPPs) along metal stripes embedded in a dielectric. These novel components can provide guiding of light as well as coupling and splitting from/into a number...... with experimental results is obtained. The interaction of LR-SPPs with photonic crystals (PCs) is also studied. The PC structures are formed by periodic arrays of gold bumps that are arranged in a triangular lattice and placed symmetrically on both sides of a thin gold film. The LR-SPP transmission through...... of channels with good performance. Guiding of LR-SPPs along nm-thin and µm-wide gold stripes embedded in polymer is investigated in the wavelength range of 1250 – 1650 nm. LR-SPP guiding properties, such as the propagation loss and mode field diameter, are studied for different stripe widths and thicknesses...

  5. Exploring procedures for the rapid assessment of optically stimulated luminescence range-finder ages

    International Nuclear Information System (INIS)

    Roberts, Helen M.; Durcan, Julie A.; Duller, Geoff A.T.

    2009-01-01

    Optically stimulated luminescence (OSL) dating of sediments is a lengthy, labour-intensive, and time-consuming procedure. However, in some situations a rough approximation of the OSL age is all that is necessary e.g. for a pilot field campaign, to plan a sampling strategy, or to determine the resolution required for a dating campaign. Thus, it would be useful to establish an approximate OSL age without the lengthy and involved processes normally used. This paper explores how the standard procedures involved in OSL age determinations can be simplified to yield range-finder ages. Three areas are examined, namely, laboratory preparation, D e estimation, and dose-rate determination. The consequences of circumventing some of the preparation and measurement steps of conventional OSL dating are examined for a variety of sediments, by comparing the OSL range-finder ages to those obtained using full quartz OSL preparation and measurement procedures.

  6. An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation

    CERN Document Server

    AUTHOR|(CDS)2070952; Valishev, Aleksander; Shatilov, Dmitry

    2015-01-01

    In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical β∗ values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.

  7. An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Fartoukh, Stephane [CERN; Valishev, Alexander [Fermilab; Shatilov, Dmitry [BINP, Novosibirsk

    2015-06-01

    In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical $\\beta^{\\ast}$values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.

  8. High accuracy subwavelength distance measurements: A variable-angle standing-wave total-internal-reflection optical microscope

    International Nuclear Information System (INIS)

    Haynie, A.; Min, T.-J.; Luan, L.; Mu, W.; Ketterson, J. B.

    2009-01-01

    We describe an extension of the total-internal-reflection microscopy technique that permits direct in-plane distance measurements with high accuracy (<10 nm) over a wide range of separations. This high position accuracy arises from the creation of a standing evanescent wave and the ability to sweep the nodal positions (intensity minima of the standing wave) in a controlled manner via both the incident angle and the relative phase of the incoming laser beams. Some control over the vertical resolution is available through the ability to scan the incoming angle and with it the evanescent penetration depth.

  9. Full-range k-domain linearization in spectral-domain optical coherence tomography.

    Science.gov (United States)

    Jeon, Mansik; Kim, Jeehyun; Jung, Unsang; Lee, Changho; Jung, Woonggyu; Boppart, Stephen A

    2011-03-10

    A full-bandwidth k-domain linearization method for spectral-domain optical coherence tomography (SD-OCT) is demonstrated. The method uses information of the wavenumber-pixel-position provided by a translating-slit-based wavelength filter. For calibration purposes, the filter is placed either after a broadband source or at the end of the sample path, and the filtered spectrum with a narrowed line width (∼0.5 nm) is incident on a line-scan camera in the detection path. The wavelength-swept spectra are co-registered with the pixel positions according to their central wavelengths, which can be automatically measured with an optical spectrum analyzer. For imaging, the method does not require a filter or a software recalibration algorithm; it simply resamples the OCT signal from the detector array without employing rescaling or interpolation methods. The accuracy of k-linearization is maximized by increasing the k-linearization order, which is known to be a crucial parameter for maintaining a narrow point-spread function (PSF) width at increasing depths. The broadening effect is studied by changing the k-linearization order by undersampling to search for the optimal value. The system provides more position information, surpassing the optimum without compromising the imaging speed. The proposed full-range k-domain linearization method can be applied to SD-OCT systems to simplify their hardware/software, increase their speed, and improve the axial image resolution. The experimentally measured width of PSF in air has an FWHM of 8 μm at the edge of the axial measurement range. At an imaging depth of 2.5 mm, the sensitivity of the full-range calibration case drops less than 10 dB compared with the uncompensated case.

  10. Histogram Matching Extends Acceptable Signal Strength Range on Optical Coherence Tomography Images

    Science.gov (United States)

    Chen, Chieh-Li; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A.; Sigal, Ian A.; Kagemann, Larry; Schuman, Joel S.

    2015-01-01

    Purpose. We minimized the influence of image quality variability, as measured by signal strength (SS), on optical coherence tomography (OCT) thickness measurements using the histogram matching (HM) method. Methods. We scanned 12 eyes from 12 healthy subjects with the Cirrus HD-OCT device to obtain a series of OCT images with a wide range of SS (maximal range, 1–10) at the same visit. For each eye, the histogram of an image with the highest SS (best image quality) was set as the reference. We applied HM to the images with lower SS by shaping the input histogram into the reference histogram. Retinal nerve fiber layer (RNFL) thickness was automatically measured before and after HM processing (defined as original and HM measurements), and compared to the device output (device measurements). Nonlinear mixed effects models were used to analyze the relationship between RNFL thickness and SS. In addition, the lowest tolerable SSs, which gave the RNFL thickness within the variability margin of manufacturer recommended SS range (6–10), were determined for device, original, and HM measurements. Results. The HM measurements showed less variability across a wide range of image quality than the original and device measurements (slope = 1.17 vs. 4.89 and 1.72 μm/SS, respectively). The lowest tolerable SS was successfully reduced to 4.5 after HM processing. Conclusions. The HM method successfully extended the acceptable SS range on OCT images. This would qualify more OCT images with low SS for clinical assessment, broadening the OCT application to a wider range of subjects. PMID:26066749

  11. Measurement of vortex velocities over a wide range of vortex age, downstream distance and free stream velocity

    Science.gov (United States)

    Rorke, J. B.; Moffett, R. C.

    1977-01-01

    A wind tunnel test was conducted to obtain vortex velocity signatures over a wide parameter range encompassing the data conditions of several previous researchers while maintaining a common instrumentation and test facility. The generating wing panel was configured with both a revolved airfoil tip shape and a square tip shape and had a semispan aspect of 4.05/1.0 with a 121.9 cm span. Free stream velocity was varied from 6.1 m/sec to 76.2 m/sec and the vortex core velocities were measured at locations 3, 6, 12, 24 and 48 chordlengths downstream of the wing trailing edge, yielding vortex ages up to 2.0 seconds. Wing pitch angles of 6, 8, 9 and 12 deg were investigated. Detailed surface pressure distributions and wing force measurements were obtained for each wing tip configuration. Correlation with vortex velocity data taken in previous experiments is good. During the rollup process, vortex core parameters appear to be dependent primarily on vortex age. Trending in the plateau and decay regions is more complex and the machanisms appear to be more unstable.

  12. Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, E V; Il' chenko, S N; Lobintsov, A A; Shramenko, M V [Superlum Diodes Ltd., Moscow (Russian Federation); Ladugin, M A [' Sigm Plyus' Ltd, Moscow (Russian Federation); Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2013-11-30

    A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

  13. Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

    International Nuclear Information System (INIS)

    Andreeva, E V; Il'chenko, S N; Lobintsov, A A; Shramenko, M V; Ladugin, M A; Marmalyuk, A A; Yakubovich, S D

    2013-01-01

    A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

  14. Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

    OpenAIRE

    Md. Rajibur Rahaman Khan; Shin-Won Kang

    2016-01-01

    In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal?s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The...

  15. Representing distance, consuming distance

    DEFF Research Database (Denmark)

    Larsen, Gunvor Riber

    Title: Representing Distance, Consuming Distance Abstract: Distance is a condition for corporeal and virtual mobilities, for desired and actual travel, but yet it has received relatively little attention as a theoretical entity in its own right. Understandings of and assumptions about distance...... are being consumed in the contemporary society, in the same way as places, media, cultures and status are being consumed (Urry 1995, Featherstone 2007). An exploration of distance and its representations through contemporary consumption theory could expose what role distance plays in forming...

  16. Low-cost and high-capacity short-range optical interconnects using graded-index plastic optical fiber

    NARCIS (Netherlands)

    Tangdiongga, E.; Yang, H.; Lee, S.C.J.; Okonkwo, C.M.; Boom, van den H.P.A.; Randel, S.; Koonen, A.M.J.

    2010-01-01

    We demonstrate a transmission rate of 51.8 Gb/s over 100-meters of perfluorinated multimode graded-index plastic optical fiber using discrete multitone modulation. The results prove suitability of plastic fibers for low-cost high-capacity optical interconnects.

  17. Response of optically stimulated luminescence dosimeters subjected to X-rays in diagnostic energy range

    International Nuclear Information System (INIS)

    Musa, Y; Hashim, S; Karim, M K A; Ang, W C; Salehhon, N; Bakar, K A

    2017-01-01

    The use of optically stimulated luminescence (OSL) for dosimetry applications has recently increased considerably due to availability of commercial OSL dosimeters (nanoDots) for clinical use. The OSL dosimeter has a great potential to be used in clinical dosimetry because of its prevailing advantages in both handling and application. However, utilising nanoDot OSLDs for dose measurement in diagnostic radiology can only be guaranteed when the performance and characteristics of the dosimeters are apposite. In the present work, we examined the response of commercially available nanoDot OSLD (Al 2 O 3 :C) subjected to X-rays in general radiography. The nanoDots response with respect to reproducibility, dose linearity and signal depletion were analysed using microStar reader (Landauer, Inc., Glenwood, IL). Irradiations were performed free-in-air using 70, 80 and 120 kV tube voltages and tube currents ranging from 10 – 100 mAs. The results showed that the nanoDots exhibit good linearity and reproducibility when subjected to diagnostic X-rays, with coefficient of variations (CV) ranging between 2.3% to 3.5% representing a good reproducibility. The results also indicated average of 1% signal reduction per readout. Hence, the nanoDots showed a promising potential for dose measurement in general X-ray procedure. (paper)

  18. A High-Dynamic-Range Optical Remote Sensing Imaging Method for Digital TDI CMOS

    Directory of Open Access Journals (Sweden)

    Taiji Lan

    2017-10-01

    Full Text Available The digital time delay integration (digital TDI technology of the complementary metal-oxide-semiconductor (CMOS image sensor has been widely adopted and developed in the optical remote sensing field. However, the details of targets that have low illumination or low contrast in scenarios of high contrast are often drowned out because of the superposition of multi-stage images in digital domain multiplies the read noise and the dark noise, thus limiting the imaging dynamic range. Through an in-depth analysis of the information transfer model of digital TDI, this paper attempts to explore effective ways to overcome this issue. Based on the evaluation and analysis of multi-stage images, the entropy-maximized adaptive histogram equalization (EMAHE algorithm is proposed to improve the ability of images to express the details of dark or low-contrast targets. Furthermore, in this paper, an image fusion method is utilized based on gradient pyramid decomposition and entropy weighting of different TDI stage images, which can improve the detection ability of the digital TDI CMOS for complex scenes with high contrast, and obtain images that are suitable for recognition by the human eye. The experimental results show that the proposed methods can effectively improve the high-dynamic-range imaging (HDRI capability of the digital TDI CMOS. The obtained images have greater entropy and average gradients.

  19. A Newly Designed Fiber-Optic Based Earth Pressure Transducer with Adjustable Measurement Range

    Directory of Open Access Journals (Sweden)

    Hou-Zhen Wei

    2018-03-01

    Full Text Available A novel fiber-optic based earth pressure sensor (FPS with an adjustable measurement range and high sensitivity is developed to measure earth pressures for civil infrastructures. The new FPS combines a cantilever beam with fiber Bragg grating (FBG sensors and a flexible membrane. Compared with a traditional pressure transducer with a dual diaphragm design, the proposed FPS has a larger measurement range and shows high accuracy. The working principles, parameter design, fabrication methods, and laboratory calibration tests are explained in this paper. A theoretical solution is derived to obtain the relationship between the applied pressure and strain of the FBG sensors. In addition, a finite element model is established to analyze the mechanical behavior of the membrane and the cantilever beam and thereby obtain optimal parameters. The cantilever beam is 40 mm long, 15 mm wide, and 1 mm thick. The whole FPS has a diameter of 100 mm and a thickness of 30 mm. The sensitivity of the FPS is 0.104 kPa/με. In addition, automatic temperature compensation can be achieved. The FPS’s sensitivity, physical properties, and response to applied pressure are extensively examined through modeling and experiments. The results show that the proposed FPS has numerous potential applications in soil pressure measurement.

  20. Optical constants of silicon monocrystals in the range of 70-400 eV

    International Nuclear Information System (INIS)

    Filatova, E.O.; Vinogradov, A.S.; Sorokin, I.A.; Zimkina, T.M.

    1983-01-01

    Optical constants (refractive index n and the linear absorption coefficient μ) of monocrystalline silicon in the quantum energy range of 70-400 eV are calculated from experimental reflection spectra using the dispersion Kramers-Kronig correlation. It is found that the general type of spectral dependences μ and n in the number of details of the structure and their energetic position depends but weakty on the fact which of the reflection spectra (4, 8 or 12 deg) is used in the calculation. A noticeable increase of calculated absorption coefficients μ in the case of increasing sliding drop angle from 4 to 12 deg is connected with the growth of the depth of radiation penetration in silicon and the corresponding increase of the medium density of the substance in the reflecting near-surface layer. When comparing the absorption spectra the identity of the fine structure and the presence of great differences in the intensity of structure details is observed. Possible reasons for such discrepancy are analyzed. A range of anomalous dispersion of the refractive index is shown to exist in the region of Lsub(2, 3) -edge of absorption (n > 1)

  1. A high gain wide dynamic range transimpedance amplifier for optical receivers

    International Nuclear Information System (INIS)

    Liu Lianxi; Zou Jiao; Liu Shubin; Niu Yue; Zhu Zhangming; Yang Yintang; En Yunfei

    2014-01-01

    As the front-end preamplifiers in optical receivers, transimpedance amplifiers (TIAs) are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range (DR) to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the −3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the −3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage. (semiconductor integrated circuits)

  2. Retrieval interval mapping, a tool to optimize the spectral retrieval range in differential optical absorption spectroscopy

    Science.gov (United States)

    Vogel, L.; Sihler, H.; Lampel, J.; Wagner, T.; Platt, U.

    2012-06-01

    Remote sensing via differential optical absorption spectroscopy (DOAS) has become a standard technique to identify and quantify trace gases in the atmosphere. The technique is applied in a variety of configurations, commonly classified into active and passive instruments using artificial and natural light sources, respectively. Platforms range from ground based to satellite instruments and trace-gases are studied in all kinds of different environments. Due to the wide range of measurement conditions, atmospheric compositions and instruments used, a specific challenge of a DOAS retrieval is to optimize the parameters for each specific case and particular trace gas of interest. This becomes especially important when measuring close to the detection limit. A well chosen evaluation wavelength range is crucial to the DOAS technique. It should encompass strong absorption bands of the trace gas of interest in order to maximize the sensitivity of the retrieval, while at the same time minimizing absorption structures of other trace gases and thus potential interferences. Also, instrumental limitations and wavelength depending sources of errors (e.g. insufficient corrections for the Ring effect and cross correlations between trace gas cross sections) need to be taken into account. Most often, not all of these requirements can be fulfilled simultaneously and a compromise needs to be found depending on the conditions at hand. Although for many trace gases the overall dependence of common DOAS retrieval on the evaluation wavelength interval is known, a systematic approach to find the optimal retrieval wavelength range and qualitative assessment is missing. Here we present a novel tool to determine the optimal evaluation wavelength range. It is based on mapping retrieved values in the retrieval wavelength space and thus visualize the consequence of different choices of retrieval spectral ranges, e.g. caused by slightly erroneous absorption cross sections, cross correlations and

  3. Direction, site and the muzzle target distance of bullet in the head and neck at close range as an indication of suicide or homicide.

    Science.gov (United States)

    Suwanjutha, T

    1988-05-01

    Direction, site and muzzle target distance can indicate suicide or homicide. This conclusion can be drawn from autopsies of 57 cases of suicide and 68 cases of homicide by handgun fired at close range to the head and neck together with going to the crimescene in some cases. This study was carried out in Bangkok during the period from January 1983 to January 1986. In order to determine whether it was suicide or homicide, the path of the bullet, the site, the muzzle target distance must be considered. The angle of the bullet would be either elevated (from below upward), horizontal or an angle of depression (from above downward). For suicide, the direction of the bullet should be at an angle of elevation in the majority of cases. The position of the handgun in relation to the head in suicide was most often in tight contact and near contact. For homicide, the direction of the bullet should be horizontal in most cases. The bullet was at close range in the majority of the cases. There are 8 common sites for suicide and homicide and 10 different sites in the case of homicide which are at neck, left cheek, left aural region, lip, left occipital area orbit, chin, left eyebrow, submental and nose.

  4. Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique.

    Science.gov (United States)

    Khan, Md Rajibur Rahaman; Kang, Shin-Won

    2016-11-09

    In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal's pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R² is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry-Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors.

  5. New methods for optical distance indicator and gantry angle quality control tests in medical linear accelerators: image processing by using a 3D phantom

    Energy Technology Data Exchange (ETDEWEB)

    Shandiz, Mahdi Heravian; Khalilzadeh, Mohammadmahdi; Anvari, Kazem [Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Layen, Ghorban Safaeian [Mashhad University of Medical Science, Mashhad (Iran, Islamic Republic of)

    2015-03-15

    In order to keep the acceptable level of the radiation oncology linear accelerators, it is necessary to apply a reliable quality assurance (QA) program. The QA protocols, published by authoritative organizations, such as the American Association of Physicists in Medicine (AAPM), determine the quality control (QC) tests which should be performed on the medical linear accelerators and the threshold levels for each test. The purpose of this study is to increase the accuracy and precision of the selected QC tests in order to increase the quality of treatment and also increase the speed of the tests to convince the crowded centers to start a reliable QA program. A new method has been developed for two of the QC tests; optical distance indicator (ODI) QC test as a daily test and gantry angle QC test as a monthly test. This method uses an image processing approach utilizing the snapshots taken by the CCD camera to measure the source to surface distance (SSD) and gantry angle. The new method of ODI QC test has an accuracy of 99.95% with a standard deviation of 0.061 cm and the new method for gantry angle QC has a precision of 0.43 degrees. The automated proposed method which is used for both ODI and gantry angle QC tests, contains highly accurate and precise results which are objective and the human-caused errors have no effect on the results. The results show that they are in the acceptable range for both of the QC tests, according to AAPM task group 142.

  6. New methods for optical distance indicator and gantry angle quality control tests in medical linear accelerators: image processing by using a 3D phantom

    International Nuclear Information System (INIS)

    Shandiz, Mahdi Heravian; Khalilzadeh, Mohammadmahdi; Anvari, Kazem; Layen, Ghorban Safaeian

    2015-01-01

    In order to keep the acceptable level of the radiation oncology linear accelerators, it is necessary to apply a reliable quality assurance (QA) program. The QA protocols, published by authoritative organizations, such as the American Association of Physicists in Medicine (AAPM), determine the quality control (QC) tests which should be performed on the medical linear accelerators and the threshold levels for each test. The purpose of this study is to increase the accuracy and precision of the selected QC tests in order to increase the quality of treatment and also increase the speed of the tests to convince the crowded centers to start a reliable QA program. A new method has been developed for two of the QC tests; optical distance indicator (ODI) QC test as a daily test and gantry angle QC test as a monthly test. This method uses an image processing approach utilizing the snapshots taken by the CCD camera to measure the source to surface distance (SSD) and gantry angle. The new method of ODI QC test has an accuracy of 99.95% with a standard deviation of 0.061 cm and the new method for gantry angle QC has a precision of 0.43 degrees. The automated proposed method which is used for both ODI and gantry angle QC tests, contains highly accurate and precise results which are objective and the human-caused errors have no effect on the results. The results show that they are in the acceptable range for both of the QC tests, according to AAPM task group 142.

  7. Interlaced zone plate optics for hard X-ray imaging in the 10 nm range

    Science.gov (United States)

    Mohacsi, Istvan; Vartiainen, Ismo; Rösner, Benedikt; Guizar-Sicairos, Manuel; Guzenko, Vitaliy A.; McNulty, Ian; Winarski, Robert; Holt, Martin V.; David, Christian

    2017-03-01

    Multi-keV X-ray microscopy has been particularly successful in bridging the resolution gap between optical and electron microscopy. However, resolutions below 20 nm are still considered challenging, as high throughput direct imaging methods are limited by the availability of suitable optical elements. In order to bridge this gap, we present a new type of Fresnel zone plate lenses aimed at the sub-20 and the sub-10 nm resolution range. By extending the concept of double-sided zone plate stacking, we demonstrate the doubling of the effective line density and thus the resolution and provide large aperture, singlechip optical devices with 15 and 7 nm smallest zone widths. The detailed characterization of these lenses shows excellent optical properties with focal spots down to 7.8 nm. Beyond wave front characterization, the zone plates also excel in typical imaging scenarios, verifying their resolution close to their diffraction limited optical performance.

  8. Long axial imaging range using conventional swept source lasers in optical coherence tomography via re-circulation loops

    Science.gov (United States)

    Bradu, Adrian; Jackson, David A.; Podoleanu, Adrian

    2018-03-01

    Typically, swept source optical coherence tomography (SS-OCT) imaging instruments are capable of a longer axial range than their camera based (CB) counterpart. However, there are still various applications that would take advantage for an extended axial range. In this paper, we propose an interferometer configuration that can be used to extend the axial range of the OCT instruments equipped with conventional swept-source lasers up to a few cm. In this configuration, the two arms of the interferometer are equipped with adjustable optical path length rings. The use of semiconductor optical amplifiers in the two rings allows for compensating optical losses hence, multiple paths depth reflectivity profiles (Ascans) can be combined axially. In this way, extremely long overall axial ranges are possible. The use of the recirculation loops produces an effect equivalent to that of extending the coherence length of the swept source laser. Using this approach, the achievable axial imaging range in SS-OCT can reach values well beyond the limit imposed by the coherence length of the laser, to exceed in principle many centimeters. In the present work, we demonstrate axial ranges exceeding 4 cm using a commercial swept source laser and reaching 6 cm using an "in-house" swept source laser. When used in a conventional set-up alone, both these lasers can provide less than a few mm axial range.

  9. Optical Modulation of BST/STO Thin Films in the Terahertz Range

    Science.gov (United States)

    Zeng, Ying; Shi, Songjie; Zhou, Ling; Ling, Furi; Yao, Jianquan

    2018-04-01

    The {Ba}_{0.7} {Sr}_{0.3} {TiO}3 (BST) thin film (30.3 nm) deposited on a {SrTiO}3 (STO) film/silicon substrate sample was modulated by 532 nm continuous-wave laser in the range of 0.2-1 THz at room temperature. The refractive index variation was observed to linearly increase at the highest 3.48 for 0.5 THz with the pump power increasing to 400 mW. It was also found that the BST/STO sample had a larger refractive index variation and was more sensitive to the external optical field than a BST monolayer due to the epitaxial strain induced by the STO film. The electric displacement-electric field loops results revealed that the increasing spontaneous polarization with the STO film that was induced was responsible for the larger refractive index variation of the BST/STO sample. In addition, the real and imaginary part of the permittivity were observed increasing along with the external field increasing, due to the soft mode hardening.

  10. Photonic quantum digital signatures operating over kilometer ranges in installed optical fiber

    Science.gov (United States)

    Collins, Robert J.; Fujiwara, Mikio; Amiri, Ryan; Honjo, Toshimori; Shimizu, Kaoru; Tamaki, Kiyoshi; Takeoka, Masahiro; Andersson, Erika; Buller, Gerald S.; Sasaki, Masahide

    2016-10-01

    The security of electronic communications is a topic that has gained noteworthy public interest in recent years. As a result, there is an increasing public recognition of the existence and importance of mathematically based approaches to digital security. Many of these implement digital signatures to ensure that a malicious party has not tampered with the message in transit, that a legitimate receiver can validate the identity of the signer and that messages are transferable. The security of most digital signature schemes relies on the assumed computational difficulty of solving certain mathematical problems. However, reports in the media have shown that certain implementations of such signature schemes are vulnerable to algorithmic breakthroughs and emerging quantum processing technologies. Indeed, even without quantum processors, the possibility remains that classical algorithmic breakthroughs will render these schemes insecure. There is ongoing research into information-theoretically secure signature schemes, where the security is guaranteed against an attacker with arbitrary computational resources. One such approach is quantum digital signatures. Quantum signature schemes can be made information-theoretically secure based on the laws of quantum mechanics while comparable classical protocols require additional resources such as anonymous broadcast and/or a trusted authority. Previously, most early demonstrations of quantum digital signatures required dedicated single-purpose hardware and operated over restricted ranges in a laboratory environment. Here, for the first time, we present a demonstration of quantum digital signatures conducted over several kilometers of installed optical fiber. The system reported here operates at a higher signature generation rate than previous fiber systems.

  11. Cryo-optical testing of large aspheric reflectors operating in the sub mm range

    Science.gov (United States)

    Roose, S.; Houbrechts, Y.; Mazzoli, A.; Ninane, N.; Stockman, Y.; Daddato, R.; Kirschner, V.; Venacio, L.; de Chambure, D.

    2006-02-01

    The cryo-optical testing of the PLANCK primary reflector (elliptical off-axis CFRP reflector of 1550 mm x 1890 mm) is one of the major issue in the payload development program. It is requested to measure the changes of the Surface Figure Error (SFE) with respect to the best ellipsoid, between 293 K and 50 K, with a 1 μm RMS accuracy. To achieve this, Infra Red interferometry has been used and a dedicated thermo mechanical set-up has been constructed. This paper summarises the test activities, the test methods and results on the PLANCK Primary Reflector - Flight Model (PRFM) achieved in FOCAL 6.5 at Centre Spatial de Liege (CSL). Here, the Wave Front Error (WFE) will be considered, the SFE can be derived from the WFE measurement. After a brief introduction, the first part deals with the general test description. The thermo-elastic deformations will be addressed: the surface deformation in the medium frequency range (spatial wavelength down to 60 mm) and core-cell dimpling.

  12. Data transmission techniques for short-range optical fiber and wireless communication links

    DEFF Research Database (Denmark)

    Pham, Tien Thang

    The research work described in this thesis is devoted to experimental investigation of techniques for cost-effective high-speed optical communications supporting both wired and wireless services. The main contributions of this thesis have expanded the state-of-the-art in two main areas: high......-speed optical/wireless integration and advanced modulation formats for intensity modulation with direct detection (IM/DD) optical systems. Regarding optical/wireless integration, this thesis focuses on integration of broadband ultra-wide band (UWB) and 60-GHz band wireless systems into optical fiber access...... networks to distribute wireless services in personal area networks (PANs). Photonic technologies to generate and distribute gigabit UWB and 60-GHz-band signals are proposed and demonstrated. Two novel methods are proposed and demonstrated to optically generate Federal Communications Commission (FCC...

  13. High resolution kilometric range optical telemetry in air by radio frequency phase measurement

    Czech Academy of Sciences Publication Activity Database

    Guillory, J.; Šmíd, Radek; García-Márquez, J.; Truong, D.; Alexandre, CH.; Wallerand, J. P.

    2016-01-01

    Roč. 87, č. 7 (2016), 075105:1-6 ISSN 0034-6748 Institutional support: RVO:68081731 Keywords : distance-measuring instrument * index Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.515, year: 2016

  14. Demonstration of free-space optical communication for long-range data links between balloons on Project Loon

    Science.gov (United States)

    Moision, Bruce; Erkmen, Baris; Keyes, Edward; Belt, Todd; Bowen, Oliver; Brinkley, Devin; Csonka, Paul; Eglington, Michael; Kazmierski, Andrei; Kim, Nam-hyong; Moody, John; Tu, Thanh; Vermeer, William

    2017-02-01

    Internet connectivity is limited and in some cases non-existent for a significant part of the world's population. Project Loon aims to address this with a network of high-altitude balloons traveling in the stratosphere, at an altitude of approximately 20 km. The balloons navigate by using the stratified wind layers at different altitudes, adjusting the balloon's altitude to catch winds in a desired direction. Data transfer is achieved by 1) uplinking a signal from an Internet-connected ground station to a balloon terminal, 2) crosslinking the signal through the balloon network to reach the geographic area of the users, and 3) downlinking the signal directly to the end-users' phones or other LTE-enabled devices. We describe Loon's progress on utilizing free-space optical communications (FSOC) for the inter-balloon crosslinks. FSOC, offering high data rates and long communication ranges, is well-suited for communication between high-altitude platforms. A stratospheric link is sufficiently high to be above weather events (clouds, fog, rain, etc.), and the impact of atmospheric turbulence is significantly weaker than at ground level. In addition, being in the stratosphere as opposed to space helps avoid the typical challenges faced by space-based systems, namely operation in a vacuum environment with significant radiation. Finally, the angular pointing disturbances introduced by a floating balloon-based platform are notably less than any propelled platform, which simplifies the disturbance rejection requirements on the FSOC system. We summarize results from Project Loon's early-phase experimental inter-balloon links at 20 km altitude, demonstrating full duplex 130 Mbps throughput at distances in excess of 100 km over the course of several-day flights. The terminals utilize a monostatic design, with dual wavelengths for communication and a dedicated wide-angle beacon for pointing, acquisition, and tracking. We summarize the constraints on the terminal design, and the

  15. THE DISTANCE TO M51

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W. [University of Texas at Austin, McDonald Observatory, 2515 Speedway, Stop C1400 Austin, TX 78712 (United States); Skillman, Evan D. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Berg, Danielle [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Kennicutt, Robert, E-mail: kmcquinn@astro.as.utexas.edu [Institute for Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2016-07-20

    Great investments of observing time have been dedicated to the study of nearby spiral galaxies with diverse goals ranging from understanding the star formation process to characterizing their dark matter distributions. Accurate distances are fundamental to interpreting observations of these galaxies, yet many of the best studied nearby galaxies have distances based on methods with relatively large uncertainties. We have started a program to derive accurate distances to these galaxies. Here we measure the distance to M51—the Whirlpool galaxy—from newly obtained Hubble Space Telescope optical imaging using the tip of the red giant branch method. We measure the distance modulus to be 8.58 ± 0.10 Mpc (statistical), corresponding to a distance modulus of 29.67 ± 0.02 mag. Our distance is an improvement over previous results as we use a well-calibrated, stable distance indicator, precision photometry in a optimally selected field of view, and a Bayesian Maximum Likelihood technique that reduces measurement uncertainties.

  16. The Distance to M51

    Science.gov (United States)

    McQuinn, Kristen. B. W.; Skillman, Evan D.; Dolphin, Andrew E.; Berg, Danielle; Kennicutt, Robert

    2016-07-01

    Great investments of observing time have been dedicated to the study of nearby spiral galaxies with diverse goals ranging from understanding the star formation process to characterizing their dark matter distributions. Accurate distances are fundamental to interpreting observations of these galaxies, yet many of the best studied nearby galaxies have distances based on methods with relatively large uncertainties. We have started a program to derive accurate distances to these galaxies. Here we measure the distance to M51—the Whirlpool galaxy—from newly obtained Hubble Space Telescope optical imaging using the tip of the red giant branch method. We measure the distance modulus to be 8.58 ± 0.10 Mpc (statistical), corresponding to a distance modulus of 29.67 ± 0.02 mag. Our distance is an improvement over previous results as we use a well-calibrated, stable distance indicator, precision photometry in a optimally selected field of view, and a Bayesian Maximum Likelihood technique that reduces measurement uncertainties. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  17. Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

    Science.gov (United States)

    Khan, Md. Rajibur Rahaman; Kang, Shin-Won

    2016-01-01

    In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal’s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R2 is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry–Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors. PMID:27834865

  18. Universal dispersion model for characterization of optical thin films over wide spectral range: Application to magnesium fluoride

    Science.gov (United States)

    Franta, Daniel; Nečas, David; Giglia, Angelo; Franta, Pavel; Ohlídal, Ivan

    2017-11-01

    Optical characterization of magnesium fluoride thin films is performed in a wide spectral range from far infrared to extreme ultraviolet (0.01-45 eV) utilizing the universal dispersion model. Two film defects, i.e. random roughness of the upper boundaries and defect transition layer at lower boundary are taken into account. An extension of universal dispersion model consisting in expressing the excitonic contributions as linear combinations of Gaussian and truncated Lorentzian terms is introduced. The spectral dependencies of the optical constants are presented in a graphical form and by the complete set of dispersion parameters that allows generating tabulated optical constants with required range and step using a simple utility in the newAD2 software package.

  19. Nonlinear optical response of chalcogenide glassy semiconductors in the IR and THz ranges studied with the femtosecond resolution in time

    DEFF Research Database (Denmark)

    Romanova, E.; Guizard, S.; Wang, Tianwu

    2017-01-01

    Two time-resolved experimental methods have been used for characterization of the non-linear optical response of chalcogenide glasses of the system As-S-Se-Te in IR and THz ranges upon excitation by femtosecond laser pulses at 800 nm wavelength. Photoinduced conductivity and refractivity were stu...

  20. Direct milling and casting of polymer-based optical waveguides for improved transparency in the visible range

    DEFF Research Database (Denmark)

    Snakenborg, Detlef; Perozziello, Gerardo; Klank, Henning

    2006-01-01

    properties. Direct micromilling enabled us to fabricate 100 mu m wide optical waveguides. Propagation losses of less than 1 dB cm(-1) could be achieved throughout the entire visual range down to a wavelength of 400 nm. A casting process amenable to high number production of such devices was furthermore...

  1. Approaches to contactless optical thermometer in the NIR spectral range based on Nd{sup 3+} doped crystalline nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kaldvee, K.; Nefedova, A.V. [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Fedorenko, S.G. [Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Novosibirsk 630090 (Russian Federation); Vanetsev, A.S. [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation); Orlovskaya, E.O. [Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation); Puust, L.; Pärs, M.; Sildos, I. [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Ryabova, A.V. [Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation); National Research Nuclear University Moscow Engineering Physics Institute, Kashirskoe Highway, 31, Moscow 115409 (Russian Federation); Orlovskii, Yu.V., E-mail: orlovski@Lst.gpi.ru [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation)

    2017-03-15

    The fluorescence kinetics and spectral intensity ratio (FIR) methods for contactless optical temperature measurement in the NIR spectral range with Nd{sup 3+} doped YAG micro- and YPO{sub 4} nanocrystals are considered and the problems are revealed. The requirements for good temperature RE doped crystalline nanoparticles sensor are formulated.

  2. All-optical 1st- and 2nd-order differential equation solvers with large tuning ranges using Fabry-Pérot semiconductor optical amplifiers.

    Science.gov (United States)

    Chen, Kaisheng; Hou, Jie; Huang, Zhuyang; Cao, Tong; Zhang, Jihua; Yu, Yuan; Zhang, Xinliang

    2015-02-09

    We experimentally demonstrate an all-optical temporal computation scheme for solving 1st- and 2nd-order linear ordinary differential equations (ODEs) with tunable constant coefficients by using Fabry-Pérot semiconductor optical amplifiers (FP-SOAs). By changing the injection currents of FP-SOAs, the constant coefficients of the differential equations are practically tuned. A quite large constant coefficient tunable range from 0.0026/ps to 0.085/ps is achieved for the 1st-order differential equation. Moreover, the constant coefficient p of the 2nd-order ODE solver can be continuously tuned from 0.0216/ps to 0.158/ps, correspondingly with the constant coefficient q varying from 0.0000494/ps(2) to 0.006205/ps(2). Additionally, a theoretical model that combining the carrier density rate equation of the semiconductor optical amplifier (SOA) with the transfer function of the Fabry-Pérot (FP) cavity is exploited to analyze the solving processes. For both 1st- and 2nd-order solvers, excellent agreements between the numerical simulations and the experimental results are obtained. The FP-SOAs based all-optical differential-equation solvers can be easily integrated with other optical components based on InP/InGaAsP materials, such as laser, modulator, photodetector and waveguide, which can motivate the realization of the complicated optical computing on a single integrated chip.

  3. Variability in leaf optical properties among 26 species from a broad range of habitats

    International Nuclear Information System (INIS)

    Knapp, A.K.; Carter, G.A.

    1998-01-01

    Leaves from 26 species with growth forms from annual herbs to trees were collected from open, intermediate, and shaded understory habitats in Mississippi and Kansas, USA. Leaf optical properties including reflectance, transmittance, and absorptance in visible and near infrared (NIR) wavelengths were measured along with leaf thickness and specific leaf mass (SLM). These leaf properties and internal light scattering have been reported to vary with light availability in studies that have focused on a limited number of species. Our objective was to determine whether these patterns in leaf optics and light availability were consistent when a greater number of species were evaluated. Leaf thickness and SLM varied by tenfold among species sampled, but within-habitat variance was high. Although there was a strong trend toward thicker leaves in open habitats, only SLM was significantly greater in open vs. understory habitats. In contrast, leaf optical properties were strikingly similar among habitats. Reflectance and reflectance/transmittance in the NIR were used to estimate internal light scattering and there were strong relationships (r2 0.65) between these optical properties and leaf thickness. We concluded that leaf thickness, which did not vary consistently among habitats, was the best predictor of NIR reflectance and internal light scattering. However, because carbon allocation to leaves was lower in understory species (low SLM) yet gross optical properties were similar among all habitats, the energy investment by shade leaves required to achieve optical equivalence with sun leaves was lower. Differences in leaf longevity and growth form within a habitat may help explain the lack of consistent patterns in leaf optics as the number of species sampled increases

  4. Quantum-optical magnets with competing short- and long-range interactions: Rydberg-dressed spin lattice in an optical cavity

    Directory of Open Access Journals (Sweden)

    Jan Gelhausen, Michael Buchhold, Achim Rosch, Philipp Strack

    2016-10-01

    Full Text Available The fields of quantum simulation with cold atoms [1] and quantum optics [2] are currently being merged. In a set of recent pathbreaking experiments with atoms in optical cavities [3,4] lattice quantum many-body systems with both, a short-range interaction and a strong interaction potential of infinite range -mediated by a quantized optical light field- were realized. A theoretical modelling of these systems faces considerable complexity at the interface of: (i spontaneous symmetry-breaking and emergent phases of interacting many-body systems with a large number of atoms $N\\rightarrow\\infty$, (ii quantum optics and the dynamics of fluctuating light fields, and (iii non-equilibrium physics of driven, open quantum systems. Here we propose what is possibly the simplest, quantum-optical magnet with competing short- and long-range interactions, in which all three elements can be analyzed comprehensively: a Rydberg-dressed spin lattice [5] coherently coupled to a single photon mode. Solving a set of coupled even-odd sublattice Master equations for atomic spin and photon mean-field amplitudes, we find three key results. (R1: Superradiance and a coherent photon field can coexist with spontaneously broken magnetic translation symmetry. The latter is induced by the short-range nearest-neighbor interaction from weakly admixed Rydberg levels. (R2: This broken even-odd sublattice symmetry leaves its imprint in the light via a novel peak in the cavity spectrum beyond the conventional polariton modes. (R3: The combined effect of atomic spontaneous emission, drive, and interactions can lead to phases with anomalous photon number oscillations. Extensions of our work include nano-photonic crystals coupled to interacting atoms and multi-mode photon dynamics in Rydberg systems.

  5. Simple and versatile long range swept source for optical coherence tomography applications

    International Nuclear Information System (INIS)

    Bräuer, Bastian; Lippok, Norman; Murdoch, Stuart G; Vanholsbeeck, Frédérique

    2015-01-01

    We present a versatile long coherence length swept-source laser design for optical coherence tomography applications. This design consists of a polygonal spinning mirror and an optical gain chip in a modified Littman–Metcalf cavity. A narrowband intra-cavity filter is implemented through multiple passes off a diffraction grating set at grazing incidence. The key advantage of this design is that it can be readily adapted to any wavelength regions for which broadband gain chips are available. We demonstrate this by implementing sources at 1650 nm, 1550 nm, 1310 nm and 1050 nm. In particular, we present a 1310 nm swept source laser with 24 mm coherence length, 95 nm optical bandwidth, 2 kHz maximum sweep frequency and 7.5 mW average output power. These parameters make it a suitable source for the imaging of biological samples. (paper)

  6. Long-range distributed optical fiber hot-wire anemometer based on chirped-pulse ΦOTDR.

    Science.gov (United States)

    Garcia-Ruiz, Andres; Dominguez-Lopez, Alejandro; Pastor-Graells, Juan; Martins, Hugo F; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

    2018-01-08

    We demonstrate a technique allowing to develop a fully distributed optical fiber hot-wire anemometer capable of reaching a wind speed uncertainty of ≈ ±0.15m/s (±0.54km/h) at only 60 mW/m of dissipated power in the sensing fiber, and within only four minutes of measurement time. This corresponds to similar uncertainty values than previous papers on distributed optical fiber anemometry but requires two orders of magnitude smaller dissipated power and covers at least one order of magnitude longer distance. This breakthrough is possible thanks to the extreme temperature sensitivity and single-shot performance of chirped-pulse phase-sensitive optical time domain reflectometry (ΦOTDR), together with the availability of metal-coated fibers. To achieve these results, a modulated current is fed through the metal coating of the fiber, causing a modulated temperature variation of the fiber core due to Joule effect. The amplitude of this temperature modulation is strongly dependent on the wind speed at which the fiber is subject. Continuous monitoring of the temperature modulation along the fiber allows to determine the wind speed with singular low power injection requirements. Moreover, this procedure makes the system immune to temperature drifts of the fiber, potentially allowing for a simple field deployment. Being a much less power-hungry scheme, this method also allows for monitoring over much longer distances, in the orders of 10s of km. We expect that this system can have application in dynamic line rating and lateral wind monitoring in railway catenary wires.

  7. Optical transmission of low-level signals with high dynamic range using the optically-coupled current-mirror architecture

    Energy Technology Data Exchange (ETDEWEB)

    Camin, Daniel V. [Dipartimento di Fisica dell' Universita degli Studi di Milano and INFN, Milan (Italy)]. E-mail: Daniel.Victor.Camin@mi.infn.it; Grassi, Valerio [Dipartimento di Fisica dell' Universita degli Studi di Milano and INFN, Milan (Italy); De Donato, Cinzia [Dipartimento di Fisica dell' Universita degli Studi di Milano and INFN, Milan (Italy)

    2007-03-01

    In this paper we illustrate the application of a novel circuit architecture, the Optically-Coupled Current-Mirror (OCCM), conceived for the linear transmission of analogue signals via fibre optics. We installed 880 OCCMs in the PMTs of the first two telescopes of the cosmic-ray experiment Pierre Auger. The Pierre Auger Observatory (PAO) has been designed to increase the statistics of cosmic-rays with energies above 10{sup 18}eV. Two different techniques have been adopted: the Surface Detector (SD) modules that comprise 1600 tanks spaced each other by 1.5km within an area of 3000km{sup 2}. On the other side there are four buildings, the Optical Stations (OS), in which six telescopes are installed in each one of the four OS, at the periphery of the site, looking inwards. The telescopes are sensitive to the UV light created at the moment a high-energy shower develops in the atmosphere and is within the field-of-view (FOV) of the telescopes. The PAO is located in the Northern Patagonia, not far from the Cordillera de Los Andes, in Argentina. Both detector types, FD telescopes and SD modules, are sensitive to the UV light resulting from the interaction of high-energy particles and the nitrogen molecules in the atmosphere. The UV-sensitive telescopes operate only at night when the sky is completely dark. Otherwise, the light collected by the telescopes may give origin to severe damage in particular if those telescopes point at twilight or to artificial light sources. The duty cycle of the telescope's operation is therefore limited to about 10% or slightly more than that, if data are taken also when there is a partial presence of the Moon. The SD modules establish, independently of the telescopes, the geometry of the event. At the same time a shower reconstruction is performed using the telescope's data, independently of the SD modules. Use of both sets of data, taken by the FD telescopes and by the SD modules, allows the hybrid reconstruction that significantly

  8. Optical transmission of low-level signals with high dynamic range using the optically-coupled current-mirror architecture

    International Nuclear Information System (INIS)

    Camin, Daniel V.; Grassi, Valerio; De Donato, Cinzia

    2007-01-01

    In this paper we illustrate the application of a novel circuit architecture, the Optically-Coupled Current-Mirror (OCCM), conceived for the linear transmission of analogue signals via fibre optics. We installed 880 OCCMs in the PMTs of the first two telescopes of the cosmic-ray experiment Pierre Auger. The Pierre Auger Observatory (PAO) has been designed to increase the statistics of cosmic-rays with energies above 10 18 eV. Two different techniques have been adopted: the Surface Detector (SD) modules that comprise 1600 tanks spaced each other by 1.5km within an area of 3000km 2 . On the other side there are four buildings, the Optical Stations (OS), in which six telescopes are installed in each one of the four OS, at the periphery of the site, looking inwards. The telescopes are sensitive to the UV light created at the moment a high-energy shower develops in the atmosphere and is within the field-of-view (FOV) of the telescopes. The PAO is located in the Northern Patagonia, not far from the Cordillera de Los Andes, in Argentina. Both detector types, FD telescopes and SD modules, are sensitive to the UV light resulting from the interaction of high-energy particles and the nitrogen molecules in the atmosphere. The UV-sensitive telescopes operate only at night when the sky is completely dark. Otherwise, the light collected by the telescopes may give origin to severe damage in particular if those telescopes point at twilight or to artificial light sources. The duty cycle of the telescope's operation is therefore limited to about 10% or slightly more than that, if data are taken also when there is a partial presence of the Moon. The SD modules establish, independently of the telescopes, the geometry of the event. At the same time a shower reconstruction is performed using the telescope's data, independently of the SD modules. Use of both sets of data, taken by the FD telescopes and by the SD modules, allows the hybrid reconstruction that significantly improves the data

  9. Semiconductor optical amplifiers for the 1000-1100-nm spectral range

    International Nuclear Information System (INIS)

    Lobintsov, A A; Shramenko, M V; Yakubovich, S D

    2008-01-01

    Two types of semiconductor optical amplifiers (SOAs) based on a double-layer quantum-well (InGa)As/(GaAl)As/GaAs heterostructure are investigated. The optical gain of more than 30 dB and saturation output power of more than 30 mW are achived at 1060 nm in pigtailed SOA modules. These SOAs used as active elements of a tunable laser provide rapid continuous tuning within 85 nm and 45 nm at output powers of 0.5 mW and more than 30 mW, respectively. (active media, lasers, and amplifiers)

  10. Broadband superluminescent diodes and semiconductor optical amplifiers for the spectral range 750 - 800 nm

    International Nuclear Information System (INIS)

    Il'chenko, S N; Kostin, Yu O; Kukushkin, I A; Ladugin, M A; Lapin, P I; Lobintsov, A A; Marmalyuk, Aleksandr A; Yakubovich, S D

    2011-01-01

    We have studied superluminescent diodes (SLDs) and semiconductor optical amplifiers (SOAs) based on an (Al x Ga 1-x )As/GaAs single quantum well structure with an Al content x ∼ 0.1 in a 10-nm-thick active layer. Depending on the length of the active channel, the single-mode fibre coupled cw output power of the SLDs is 1 to 30 mW at a spectral width of about 50 nm. The width of the optical gain band in the active channel exceeds 40 nm. Preliminary operating life tests have demonstrated that the devices are sufficiently reliable. (lasers)

  11. Long-Range Channel Measurements on Small Terminal Antennas Using Optics

    DEFF Research Database (Denmark)

    Yanakiev, Boyan; Nielsen, Jesper Ødum; Christensen, Morten

    2012-01-01

    In this paper, details are given on a novel measurement device for radio propagation-channel measurements. To avoid measurement errors due to the conductive cables on small terminal antennas, as well as to improve the handling of the prototypes under investigation, an optical measurement device has...

  12. Frequency-swept Light Sources for Optical Coherence Tomography in the 1060nm range

    DEFF Research Database (Denmark)

    Marschall, Sebastian

    Optical coherence tomography (OCT) is a non-invasive imaging technique for visualizing the internal structure of scattering materials, such as biological tissues. It generates two- or three-dimensional images of the sample with cellular (micrometer) resolution. OCT has become an important instrum...

  13. Physics of reflective optics for the soft gamma-ray photon energy range

    DEFF Research Database (Denmark)

    Fernández-Perea, Mónica; Descalle, Marie-Anne; Soufli, Regina

    2013-01-01

    Traditional multilayer reflective optics that have been used in the past for imaging at x-ray photon energies as high as 200 keV are governed by classical wave phenomena. However, their behavior at higher energies is unknown, because of the increasing effect of incoherent scattering and the disag...

  14. Development of photonic-crystal-fiber-based optical coupler with a broad operating wavelength range of 800 nm

    International Nuclear Information System (INIS)

    Yoon, Min-Seok; Kwon, Oh-Jang; Kim, Hyun-Joo; Chu, Su-Ho; Kim, Gil-Hwan; Lee, Sang-Bae; Han, Young-Geun

    2010-01-01

    We developed a broadband optical coupler based on a photonic crystal fiber (PCF), which is very useful for applications to optical coherence tomography (OCT). The PCF-based coupler is fabricated by using a fused biconical tapering (FBT) method. The PCF has six hexagonally-stacked layers of air holes. The PCF-based coupler has a nearly-flat 50/50 coupling ratio in a broad bandwidth range of 800 nm, which is much wider than that previously reported for a PCF-based coupler and a singlemode-fiber-based coupler. The bandwidth and the bandedge wavelength of the broadband coupler are controlled by changing the elongation length. The fabricated broadband optical coupler has great potential for realizing a broadband interferogram with a high resolution in an OCT system.

  15. 2.5 Gbit/s Optical Receiver Front-End Circuit with High Sensitivity and Wide Dynamic Range

    Science.gov (United States)

    Zhu, Tiezhu; Mo, Taishan; Ye, Tianchun

    2017-12-01

    An optical receiver front-end circuit is designed for passive optical network and fabricated in a 0.18 um CMOS technology. The whole circuit consists of a transimpedance amplifier (TIA), a single-ended to differential amplifier and an output driver. The TIA employs a cascode stage as the input stage and auxiliary amplifier to reduce the miller effect. Current injecting technique is employed to enlarge the input transistor's transconductance, optimize the noise performance and overcome the lack of voltage headroom. To achieve a wide dynamic range, an automatic gain control circuit with self-adaptive function is proposed. Experiment results show an optical sensitivity of -28 dBm for a bit error rate of 10-10 at 2.5 Gbit/s and a maxim input optical power of 2 dBm using an external photodiode. The chip occupies an area of 1×0.9 mm2 and consumes around 30 mW from single 1.8 V supply. The front-end circuit can be used in various optical receivers.

  16. Confidence range estimate of extended source imagery acquisition algorithms via computer simulations. [in optical communication systems

    Science.gov (United States)

    Chen, CHIEN-C.; Hui, Elliot; Okamoto, Garret

    1992-01-01

    Spatial acquisition using the sun-lit Earth as a beacon source provides several advantages over active beacon-based systems for deep-space optical communication systems. However, since the angular extend of the Earth image is large compared to the laser beam divergence, the acquisition subsystem must be capable of resolving the image to derive the proper pointing orientation. The algorithms used must be capable of deducing the receiver location given the blurring introduced by the imaging optics and the large Earth albedo fluctuation. Furthermore, because of the complexity of modelling the Earth and the tracking algorithms, an accurate estimate of the algorithm accuracy can only be made via simulation using realistic Earth images. An image simulator was constructed for this purpose, and the results of the simulation runs are reported.

  17. Genetic Differentiation, Isolation-by-Distance, and Metapopulation Dynamics of the Arizona Treefrog (Hyla wrightorum in an Isolated Portion of Its Range.

    Directory of Open Access Journals (Sweden)

    Meryl C Mims

    Full Text Available Population attributes such as diversity, connectivity, and structure are important components of understanding species persistence and vulnerability to extinction. Hyla wrightorum, the Arizona treefrog, is native to the southwestern United States and Mexico, and an isolated group of populations exists in the Huachuca Mountains and Canelo Hills (HMCH of southeastern Arizona, USA. Due to concerns about declining observations of the species within the isolated HMCH portion of its range, the HMCH group is currently a candidate for federal protection under the U.S. Endangered Species Act. We present results of a genetic study examining population diversity, structure, and connectivity within the HMCH region. We sampled DNA from H. wrightorum larvae and adults from ten distinct locations, 8 of which were breeding sites and 4 of which were previously undescribed localities for the species. We developed and genotyped 17 polymorphic microsatellite loci and quantified genetic diversity, population differentiation, and landscape influences on population genetic structure. We found evidence of larger than expected effective population sizes, significant genetic differentiation between populations, and evidence of distance being the primary driver of genetic structure of populations with some influence of slope and canopy cover. We found little evidence of recent genetic bottlenecks, and individual-based analyses indicate admixture between populations despite significant genetic differentiation. These patterns may indicate that the breeding sites within the Huachuca Mountains constitute a metapopulation. We suggest that the HMCH region may contain larger and more connected breeding populations than previously understood, but the dynamics of this system and the limited geographic extent of the HMCH group justify current concern for the persistence of the species in this region. Efforts to ensure availability of high-quality breeding habitats and control for

  18. Giant magneto-optical faraday effect in HgTe thin films in the terahertz spectral range.

    Science.gov (United States)

    Shuvaev, A M; Astakhov, G V; Pimenov, A; Brüne, C; Buhmann, H; Molenkamp, L W

    2011-03-11

    We report the observation of a giant Faraday effect, using terahertz (THz) spectroscopy on epitaxial HgTe thin films at room temperature. The effect is caused by the combination of the unique band structure and the very high electron mobility of HgTe. Our observations suggest that HgTe is a high-potential material for applications as optical isolator and modulator in the THz spectral range.

  19. A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer

    Science.gov (United States)

    Marciniak, L.; Prorok, K.; Francés-Soriano, L.; Pérez-Prieto, J.; Bednarkiewicz, A.

    2016-02-01

    The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale.The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle

  20. Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

    DEFF Research Database (Denmark)

    Pankratov, V.; Osinniy, Viktor; Kotlov, A.

    2011-01-01

    done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescence properties of the embedded Si nanocrystals...... is discussed. Moreover, it is demonstrated that no energy transfer takes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO2....

  1. Optical nonlinearity and bistability in the bound exciton energy range of CdS

    International Nuclear Information System (INIS)

    Hoenig, T.; Gutowski, J.

    1988-01-01

    Under high excitation conditions thick CdS samples show pronounced broad-band nonlinear transmission in the bound exciton region and up to a wavelength of about 515 nm at cryo-temperatures. This behavior is only explainable in a model based on impurity neutralization and bound exciton creation. The suitability of these nonlinearities to yield optical bistability will be shown. Bistable operation is investigated in dependence of crystal thickness, impurity concentration, excitation density, wavelength, and temperature. A strong correlation to acceptor-bound exciton generation is obtained, and the explanation of this bistable operation fits well with that of the above mentioned transmission behavior. (author)

  2. Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

    Directory of Open Access Journals (Sweden)

    J. Jung

    2010-06-01

    Full Text Available As a part of the IGAC (International Global Atmospheric Chemistry Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57° N, 126.94° E in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (babs from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, σabs (=babs/EC at 550 nm was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m2 g−1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m2 g−1. Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP events. Satellite aerosol optical thickness (AOT and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

  3. Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing.

    Science.gov (United States)

    Guo, Nan; Wang, Liang; Wang, Jie; Jin, Chao; Tam, Hwa-Yaw; Zhang, A Ping; Lu, Chao

    2016-12-16

    We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes.

  4. Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing

    Science.gov (United States)

    Guo, Nan; Wang, Liang; Wang, Jie; Jin, Chao; Tam, Hwa-Yaw; Zhang, A. Ping; Lu, Chao

    2016-01-01

    We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes. PMID:27999250

  5. Dynamic range enhancement and amplitude regeneration in single pump fibre optic parametric amplifiers using DPSK modulation

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Lorenzen, Michael Rodas; Seoane, Jorge

    2008-01-01

    Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain.......Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain....

  6. Optical probing of long-range spatial correlation and symmetry in complex biophotonic architectures on transparent insect wings

    International Nuclear Information System (INIS)

    Kumar, Pramod; Shamoon, Danish; Singh, Dhirendra P; Singh, Kamal P; Mandal, Sudip

    2015-01-01

    We experimentally probe the structural organization of complex bio-photonic architecture on transparent insect wings by a simple, non-invasive, real-time optical technique. A stable and reproducible far-field diffraction pattern in transmission was observed using collimated cw and broadband fs laser pulses. A quantitative analysis of the observed diffraction pattern unveiled long-range quasi-periodic order in the arrangement of the microstructures over mm scale. These observations agree well with the Fourier analysis of SEM images of the wing taken at various length scales. We propose a simple quantitative model based on optical diffraction by an array of non overlapping microstructures with minimal disorder which supports our experimental observations. We observed a rotation of the original diffraction profile by scanning the laser beam across the wing sample which gives direct signature of organizational symmetry in microstructure arrangements at various length scales. In addition, we report the first optical detection of reorganization in the photonic architecture on the Drosophila wings by various genetic mutations. These results have potential for the design and development of diffractive optical components for applied photonics and may open up new opportunities in biomimetic device research. (letter)

  7. Ultra-compact and wide-spectrum-range thermo-optic switch based on silicon coupled photonic crystal microcavities

    International Nuclear Information System (INIS)

    Zhang, Xingyu; Chung, Chi-Jui; Pan, Zeyu; Yan, Hai; Chakravarty, Swapnajit; Chen, Ray T.

    2015-01-01

    We design, fabricate, and experimentally demonstrate a compact thermo-optic gate switch comprising a 3.78 μm-long coupled L0-type photonic crystal microcavities on a silicon-on-insulator substrate. A nanohole is inserted in the center of each individual L0 photonic crystal microcavity. Coupling between identical microcavities gives rise to bonding and anti-bonding states of the coupled photonic molecules. The coupled photonic crystal microcavities are numerically simulated and experimentally verified with a 6 nm-wide flat-bottom resonance in its transmission spectrum, which enables wider operational spectrum range than microring resonators. An integrated micro-heater is in direct contact with the silicon core to efficiently drive the device. The thermo-optic switch is measured with an optical extinction ratio of 20 dB, an on-off switching power of 18.2 mW, a thermo-optic tuning efficiency of 0.63 nm/mW, a rise time of 14.8 μs, and a fall time of 18.5 μs. The measured on-chip loss on the transmission band is as low as 1 dB

  8. Biophysical mechanisms of modification of skin optical properties in the UV wavelength range with nanoparticles

    Science.gov (United States)

    Popov, A. P.; Priezzhev, A. V.; Lademann, J.; Myllylä, R.

    2009-05-01

    In this paper, by means of the Mie theory and Monte Carlo simulations we investigate modification of optical properties of the superficial layer of human skin (stratum corneum) for 310- and 400-nm ultraviolet (UV) radiation by embedding of 35-200-nm-sized particles of titanium dioxide (TiO2) and silicon (Si). Problem of skin protection against UV light is of major importance due to increased frequency of skin cancer provoked by excessive doses of accepted UV radiation. For 310-nm light, the optimal sizes of the TiO2 and Si particles are found to be 62 and 55 nm, respectively, and for 400-nm radiation, 122 and 70 nm, respectively.

  9. Biophysical mechanisms of modification of skin optical properties in the UV wavelength range with nanoparticles

    International Nuclear Information System (INIS)

    Popov, A. P.; Priezzhev, A. V.; Lademann, J.; Myllylae, R.

    2009-01-01

    In this paper, by means of the Mie theory and Monte Carlo simulations we investigate modification of optical properties of the superficial layer of human skin (stratum corneum) for 310- and 400-nm ultraviolet (UV) radiation by embedding of 35-200-nm-sized particles of titanium dioxide (TiO 2 ) and silicon (Si). Problem of skin protection against UV light is of major importance due to increased frequency of skin cancer provoked by excessive doses of accepted UV radiation. For 310-nm light, the optimal sizes of the TiO 2 and Si particles are found to be 62 and 55 nm, respectively, and for 400-nm radiation, 122 and 70 nm, respectively.

  10. Stochastic calculus analysis of optical time-of-flight range imaging and estimation of radial motion.

    Science.gov (United States)

    Streeter, Lee

    2017-07-01

    Time-of-flight range imaging is analyzed using stochastic calculus. Through a series of interpretations and simplifications, the stochastic model leads to two methods for estimating linear radial velocity: maximum likelihood estimation on the transition probability distribution between measurements, and a new method based on analyzing the measured correlation waveform and its first derivative. The methods are tested in a simulated motion experiment from (-40)-(+40)  m/s, with data from a camera imaging an object on a translation stage. In tests maximum likelihood is slow and unreliable, but when it works it estimates the linear velocity with standard deviation of 1 m/s or better. In comparison the new method is fast and reliable but works in a reduced velocity range of (-20)-(+20)  m/s with standard deviation ranging from 3.5 m/s to 10 m/s.

  11. Quantitative, simultaneous, and collinear eye-tracked, high dynamic range optical coherence tomography at 850 and 1060 nm

    Science.gov (United States)

    Mooser, Matthias; Burri, Christian; Stoller, Markus; Luggen, David; Peyer, Michael; Arnold, Patrik; Meier, Christoph; Považay, Boris

    2017-07-01

    Ocular optical coherence tomography at the wavelengths ranges of 850 and 1060 nm have been integrated with a confocal scanning laser ophthalmoscope eye-tracker as a clinical commercial-class system. Collinear optics enables an exact overlap of the different channels to produce precisely overlapping depth-scans for evaluating the similarities and differences between the wavelengths to extract additional physiologic information. A reliable segmentation algorithm utilizing Graphcuts has been implemented and applied to automatically extract retinal and choroidal shape in cross-sections and volumes. The device has been tested in normals and pathologies including a cross-sectional and longitudinal study of myopia progress and control with a duplicate instrument in Asian children.

  12. Refractometers for different refractive index range by surface plasmon resonance sensors in multimode optical fibers with different metals

    Science.gov (United States)

    Zuppella, P.; Corso, Alain J.; Pelizzo, Maria G.; Cennamo, N.; Zeni, L.

    2016-09-01

    We have realized a plasmonic sensor based on Au/Pd metal bilayer in a multimode plastic optical fiber. This metal bilayer, based on a metal with high imaginary part of the refractive index and gold, shows interesting properties in terms of sensitivity and performances, in different refractive index ranges. The development of highly sensitive platforms for high refractive index detection (higher than 1.38) is interesting for chemical applications based on molecularly imprinted polymer as receptors, while the aqueous medium is the refractive index range of biosensors based on bio-receptors. In this work we have presented an Au/Pd metal bilayer optimized for 1.38-1.42 refractive index range.

  13. Double peak-induced distance error in short-time-Fourier-transform-Brillouin optical time domain reflectometers event detection and the recovery method.

    Science.gov (United States)

    Yu, Yifei; Luo, Linqing; Li, Bo; Guo, Linfeng; Yan, Jize; Soga, Kenichi

    2015-10-01

    The measured distance error caused by double peaks in the BOTDRs (Brillouin optical time domain reflectometers) system is a kind of Brillouin scattering spectrum (BSS) deformation, discussed and simulated for the first time in the paper, to the best of the authors' knowledge. Double peak, as a kind of Brillouin spectrum deformation, is important in the enhancement of spatial resolution, measurement accuracy, and crack detection. Due to the variances of the peak powers of the BSS along the fiber, the measured starting point of a step-shape frequency transition region is shifted and results in distance errors. Zero-padded short-time-Fourier-transform (STFT) can restore the transition-induced double peaks in the asymmetric and deformed BSS, thus offering more accurate and quicker measurements than the conventional Lorentz-fitting method. The recovering method based on the double-peak detection and corresponding BSS deformation can be applied to calculate the real starting point, which can improve the distance accuracy of the STFT-based BOTDR system.

  14. Distance Learning

    National Research Council Canada - National Science Library

    Braddock, Joseph

    1997-01-01

    A study reviewing the existing Army Distance Learning Plan (ADLP) and current Distance Learning practices, with a focus on the Army's training and educational challenges and the benefits of applying Distance Learning techniques...

  15. Design, calibration and application of broad-range optical nanosensors for determining intracellular pH

    DEFF Research Database (Denmark)

    Søndergaard, Rikke Vicki; Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2014-01-01

    Particle-based nanosensors offer a tool for determining the pH in the endosomal-lysosomal system of living cells. Measurements providing absolute values of pH have so far been restricted by the limited sensitivity range of nanosensors, calibration challenges and the complexity of image analysis....... This protocol describes the design and application of a polyacrylamide-based nanosensor (∼60 nm) that covalently incorporates two pH-sensitive fluorophores, fluorescein (FS) and Oregon Green (OG), to broaden the sensitivity range of the sensor (pH 3.1-7.0), and uses the pH-insensitive fluorophore rhodamine...... as a reference fluorophore. The nanosensors are spontaneously taken up via endocytosis and directed to the lysosomes where dynamic changes in pH can be measured with live-cell confocal microscopy. The most important focus areas of the protocol are the choice of pH-sensitive fluorophores, the design...

  16. Recording and Modelling of MONUMENTS' Interior Space Using Range and Optical Sensors

    Science.gov (United States)

    Georgiadis, Charalampos; Patias, Petros; Tsioukas, Vasilios

    2016-06-01

    Three dimensional modelling of artefacts and building interiors is a highly active research field in our days. Several techniques are being utilized to perform such a task, spanning from traditional surveying techniques and photogrammetry to structured light scanners, laser scanners and so on. New technological advancements in both hardware and software create new recording techniques, tools and approaches. In this paper we present a new recording and modelling approach based on the SwissRanger SR4000 range camera coupled with a Canon 400D dSLR camera. The hardware component of our approach consists of a fixed base, which encloses the range and SLR cameras. The two sensors are fully calibrated and registered to each other thus we were able to produce colorized point clouds acquired from the range camera. In this paper we present the initial design and calibration of the system along with experimental data regarding the accuracy of the proposed approach. We are also providing results regarding the modelling of interior spaces and artefacts accompanied with accuracy tests from other modelling approaches based on photogrammetry and laser scanning.

  17. Transverse magneto-optical anisotropy in bidisperse ferrofluids with long range particle correlations

    Energy Technology Data Exchange (ETDEWEB)

    Elfimova, E.A.; Ivanov, A.O. [Ural Federal University, ul. Lenina 51, Yekaterinburg 620000 (Russian Federation); Popescu, L.B. [Institute for Space Sciences, Atomistilor 409, Magurele RO-077125 (Romania); Socoliuc, V., E-mail: vsocoliuc@acad-tim.tm.edu.ro [Romanian Academy-Timisoara Branch, Center for Fundamental and Advanced Technical Research, Lab. Magnetic Fluids, Bv.M. Viteazu 24, Timisoara RO-300223 (Romania)

    2017-06-01

    A comparative study between experiment and the predictions of a theoretical model developed for the description of magnetically induced dichroism in ferrofluids with long range interacting bidisperse spherical nanoparticles is presented. Magnetically induced dichroism in dilution series of two ferrofluids with different surfactant thickness was measured. Both ferrofluids show a concave solid volume fraction dependence of the specific dichroism, whose characteristics are very well qualitatively explained by the theoretical model. The theory fails to satisfactorily explain the magnetic field dependence of the highly concentrated samples specific dichroism, due to inherent approximations in the virial expansion of the pair correlation function.

  18. Extended capture range for focus-diverse phase retrieval in segmented aperture systems using geometrical optics.

    Science.gov (United States)

    Jurling, Alden S; Fienup, James R

    2014-03-01

    Extending previous work by Thurman on wavefront sensing for segmented-aperture systems, we developed an algorithm for estimating segment tips and tilts from multiple point spread functions in different defocused planes. We also developed methods for overcoming two common modes for stagnation in nonlinear optimization-based phase retrieval algorithms for segmented systems. We showed that when used together, these methods largely solve the capture range problem in focus-diverse phase retrieval for segmented systems with large tips and tilts. Monte Carlo simulations produced a rate of success better than 98% for the combined approach.

  19. Characteristics of III-nitride based laser diode employed for short range underwater wireless optical communications

    Science.gov (United States)

    Xue, Bin; Liu, Zhe; Yang, Jie; Feng, Liangsen; Zhang, Ning; Wang, Junxi; Li, Jinmin

    2018-03-01

    An off-the-shelf green laser diode (LD) was measured to investigate its temperature dependent characteristics. Performance of the device was severely restricted by rising temperature in terms of increasing threshold current and decreasing modulation bandwidth. The observation reveals that dynamic characteristics of the LD is sensitive to temperature. Influence of light attenuation on the modulation bandwidth of the green LD was also studied. The impact of light attenuation on the modulation bandwidth of the LD in short and low turbid water channel was not obvious while slight difference in modulation bandwidth under same injection level was observed between water channel and free space even at short range.

  20. Nanoimprint-defined, large-area meta-surfaces for unidirectional optical transmission with superior extinction in the visible-to-infrared range.

    Science.gov (United States)

    Yao, Yuhan; Liu, He; Wang, Yifei; Li, Yuanrui; Song, Boxiang; Wang, Richard P; Povinelli, Michelle L; Wu, Wei

    2016-07-11

    Optical devices with asymmetric transmission have important applications in optical systems, but optical isolators with the modal asymmetry can only be built using magneto-optical or nonlinear materials, as dictated by the Lorentz reciprocity theorem. However, optical devices with the power asymmetry can be achieved by linear materials such as metals and dielectrics. In this paper, we report a large-area, nanoimprint-defined meta-surface (stacked subwavelength gratings) with high-contrast asymmetric transmittance in the visible-to-infrared wavelength range for TM-polarized light. The physical origin of asymmetric transmission through the meta-surface is studied by analyzing the scattering matrix.

  1. Screening method for the detection of a range of nitrofurans in avian eyes by optical biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Colin S., E-mail: colin.thompson@afbini.gov.uk [Agri-Food and Biosciences Institute, Veterinary Sciences Division, Stormont, Belfast BT4 3SD, Northern Ireland (United Kingdom); Traynor, Imelda M.; Fodey, Terence L.; Crooks, Steven R.H.; Kennedy, D. Glenn [Agri-Food and Biosciences Institute, Veterinary Sciences Division, Stormont, Belfast BT4 3SD, Northern Ireland (United Kingdom)

    2011-08-26

    An immunobiosensor assay was developed for the multi-residue screening of a range of nitrofuran compounds in avian eyes. A polyclonal antibody which binds at least 5 of the major parent nitrofurans was raised in a rabbit after inoculation with a nitrofuran mimic-protein conjugate. Sample homogenates were extracted into 0.1 M hydrochloric acid and subjected to clean-up by solid phase extraction and micro-centrifugation prior to biosensor analysis. Validation data obtained from the analysis of 21 fortified samples has shown that the method has a detection capability (CC{beta}) of less than 1 ng eye{sup -1} for nitrofurazone (NFZ). In addition, cross-reactivity data and the analysis of a smaller number of fortified samples have shown that the method will also detect a range of other major parent nitrofurans including furazolidone (FZD), furaltadone (FTD), nitrofurantoin (NFA) and nifursol (NFS). Intra-assay variation (n = 10) was calculated at 12.9% and 10.1% at concentrations of 1 ng eye{sup -1} and 2 ng eye{sup -1} NFZ respectively. Inter-assay variation (n = 3) was determined to be 10.8% and 4.7% at the same NFZ concentrations respectively. The cross-reactivity profile and validation data for the detection of these nitrofurans are presented together with the results obtained following the analysis of a small number of incurred samples using the developed method.

  2. Electrical, optical, and electronic properties of Al:ZnO films in a wide doping range

    International Nuclear Information System (INIS)

    Valenti, Ilaria; Valeri, Sergio; Benedetti, Stefania; Bona, Alessandro di; Lollobrigida, Valerio; Perucchi, Andrea; Di Pietro, Paola; Lupi, Stefano; Torelli, Piero

    2015-01-01

    The combination of photoemission spectroscopies, infrared and UV-VIS absorption, and electric measurements has allowed to clarify the mechanisms governing the conductivity and the electronic properties of Al-doped ZnO (AZO) films in a wide doping range. The contribution of defect-related in-gap states to conduction has been excluded in optimally doped films (around 4 at. %). The appearance of gap states at high doping, the disappearance of occupied DOS at Fermi level, and the bands evolution complete the picture of electronic structure in AZO when doped above 4 at. %. In this situation, compensating defects deplete the conduction band and increase the electronic bandgap of the material. Electrical measurements and figure of merit determination confirm the high quality of the films obtained by magnetron sputtering, and thus allow to extend their properties to AZO films in general

  3. Electrical, optical, and electronic properties of Al:ZnO films in a wide doping range

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, Ilaria; Valeri, Sergio [CNR, Istituto Nanoscienze, S3, Via G. Campi 213/a, 41125 Modena (Italy); Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy); Benedetti, Stefania, E-mail: stefania.benedetti@unimore.it; Bona, Alessandro di [CNR, Istituto Nanoscienze, S3, Via G. Campi 213/a, 41125 Modena (Italy); Lollobrigida, Valerio [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome, Italy and Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Perucchi, Andrea; Di Pietro, Paola [INSTM Udr Trieste-ST and Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Trieste (Italy); Lupi, Stefano [CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, I-00185 Roma (Italy); Torelli, Piero [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy)

    2015-10-28

    The combination of photoemission spectroscopies, infrared and UV-VIS absorption, and electric measurements has allowed to clarify the mechanisms governing the conductivity and the electronic properties of Al-doped ZnO (AZO) films in a wide doping range. The contribution of defect-related in-gap states to conduction has been excluded in optimally doped films (around 4 at. %). The appearance of gap states at high doping, the disappearance of occupied DOS at Fermi level, and the bands evolution complete the picture of electronic structure in AZO when doped above 4 at. %. In this situation, compensating defects deplete the conduction band and increase the electronic bandgap of the material. Electrical measurements and figure of merit determination confirm the high quality of the films obtained by magnetron sputtering, and thus allow to extend their properties to AZO films in general.

  4. A wide range and highly sensitive optical fiber pH sensor using polyacrylamide hydrogel

    Science.gov (United States)

    Pathak, Akhilesh Kumar; Singh, Vinod Kumar

    2017-12-01

    In the present study we report the fabrication and characterization of no-core fiber sensor (NCFS) using smart hydrogel coating for pH measurement. The no-core fiber (NCF) is stubbed between two single-mode fibers with SMA connector before immobilizing of smart hydrogel. The wavelength interrogation technique is used to calculate the sensitivity of the proposed sensor. The result shows a high sensitivity of 1.94 nm/pH for a wide range of pH values varied from 3 to 10 with a good linear response. In addition to high sensitivity, the fabricated sensor provides a fast response time with a good stability, repeatability and reproducibility.

  5. Estimation of cardiac motion in cine-MRI sequences by correlation transform optical flow of monogenic features distance

    Science.gov (United States)

    Gao, Bin; Liu, Wanyu; Wang, Liang; Liu, Zhengjun; Croisille, Pierre; Delachartre, Philippe; Clarysse, Patrick

    2016-12-01

    Cine-MRI is widely used for the analysis of cardiac function in clinical routine, because of its high soft tissue contrast and relatively short acquisition time in comparison with other cardiac MRI techniques. The gray level distribution in cardiac cine-MRI is relatively homogenous within the myocardium, and can therefore make motion quantification difficult. To ensure that the motion estimation problem is well posed, more image features have to be considered. This work is inspired by a method previously developed for color image processing. The monogenic signal provides a framework to estimate the local phase, orientation, and amplitude, of an image, three features which locally characterize the 2D intensity profile. The independent monogenic features are combined into a 3D matrix for motion estimation. To improve motion estimation accuracy, we chose the zero-mean normalized cross-correlation as a matching measure, and implemented a bilateral filter for denoising and edge-preservation. The monogenic features distance is used in lieu of the color space distance in the bilateral filter. Results obtained from four realistic simulated sequences outperformed two other state of the art methods even in the presence of noise. The motion estimation errors (end point error) using our proposed method were reduced by about 20% in comparison with those obtained by the other tested methods. The new methodology was evaluated on four clinical sequences from patients presenting with cardiac motion dysfunctions and one healthy volunteer. The derived strain fields were analyzed favorably in their ability to identify myocardial regions with impaired motion.

  6. Design of optical switches by illusion optics

    International Nuclear Information System (INIS)

    Shoorian, H R; Abrishamian, M S

    2013-01-01

    In this paper, illusion optics theory is employed to form Bragg gratings in an optical waveguide in order to design an optical switch. By using an illusion device at a certain distance from the waveguide, the effective refractive index of the waveguide is remotely modulated, turning the waveguide into a distributed Bragg reflector (DBR) which blocks the waves at a stop band. By removing the illusion device, the waves propagate through the waveguide again. In addition, this method is used to remotely tune DBR optical properties such as resonant frequency and bandwidth in a wide range, which leads to a tunable filter for optical switching applications. Finally, using an illusion device at a distance, an optical cavity is created by inserting defects remotely in a DBR without any physical damage in the primary device. (paper)

  7. Design of optical switches by illusion optics

    Science.gov (United States)

    Shoorian, H. R.; Abrishamian, M. S.

    2013-05-01

    In this paper, illusion optics theory is employed to form Bragg gratings in an optical waveguide in order to design an optical switch. By using an illusion device at a certain distance from the waveguide, the effective refractive index of the waveguide is remotely modulated, turning the waveguide into a distributed Bragg reflector (DBR) which blocks the waves at a stop band. By removing the illusion device, the waves propagate through the waveguide again. In addition, this method is used to remotely tune DBR optical properties such as resonant frequency and bandwidth in a wide range, which leads to a tunable filter for optical switching applications. Finally, using an illusion device at a distance, an optical cavity is created by inserting defects remotely in a DBR without any physical damage in the primary device.

  8. Fourier domain optical coherence tomography achieves full range complex imaging in vivo by introducing a carrier frequency during scanning

    International Nuclear Information System (INIS)

    Wang, Ruikang K

    2007-01-01

    The author describes a Fourier domain optical coherence tomography (FDOCT) system that is capable of full range complex imaging in vivo. This is achieved by introducing a constant carrier frequency into the OCT spectral interferograms at the time when imaging is performed. The complex functions of the spatial interferograms formed by each single wavelength are constructed before performing the Fourier transformation to localize the scatters within a sample. Two algorithms, based on Fourier filtering and Hilbert transformation, respectively, are described to achieve the full range complex FDOCT imaging. It is shown that the Hilbert transformation approach delivers better performance than the Fourier filtering method does in terms of tolerating the sample movement in vivo. The author finally demonstrates experimentally the system and algorithms for true in vivo imaging at a rate of 20 000 axial scans per second

  9. Fabrication of thin ZnO films with wide-range tuned optical properties by reactive magnetron sputtering

    Science.gov (United States)

    Davydova, A.; Tselikov, G.; Dilone, D.; Rao, K. V.; Kabashin, A. V.; Belova, L.

    2018-02-01

    We report the manufacturing of thin zinc oxide films by reactive magnetron sputtering at room temperature, and examine their structural and optical properties. We show that the partial oxygen pressure in DC mode can have dramatic effect on absorption and refractive index (RI) of the films in a broad spectral range. In particular, the change of the oxygen pressure from 7% to 5% can lead to either conventional crystalline ZnO films having low absorption and characteristic descending dependence of RI from 2.4-2.7 RIU in the visible to 1.8-2 RIU in the near-infrared (1600 nm) range, or to untypical films, composed of ZnO nano-crystals embedded into amorphous matrix, exhibiting unexpectedly high absorption in the visible-infrared region and ascending dependence of RI with values varying from 1.5 RIU in the visible to 4 RIU in the IR (1600 nm), respectively. Untypical optical characteristics in the second case are explained by defects in ZnO structure arising due to under-oxidation of ZnO crystals. We also show that the observed defect-related film structure remains stable even after annealing of films under relatively high temperatures (30 min under 450 °C). We assume that both types of films can be of importance for photovoltaic (as contact or active layers, respectively), as well as for chemical or biological sensing, optoelectronics etc.

  10. Optically stabilized Erbium fiber frequency comb with hybrid mode-locking and a broad tunable range of repetition rate.

    Science.gov (United States)

    Yang, Honglei; Wu, Xuejian; Zhang, Hongyuan; Zhao, Shijie; Yang, Lijun; Wei, Haoyun; Li, Yan

    2016-12-01

    We present an optically stabilized Erbium fiber frequency comb with a broad repetition rate tuning range based on a hybrid mode-locked oscillator. We lock two comb modes to narrow-linewidth reference lasers in turn to investigate the best performance of control loops. The control bandwidth of fast and slow piezoelectric transducers reaches 70 kHz, while that of pump current modulation with phase-lead compensation is extended to 32 kHz, exceeding laser intrinsic response. Eventually, simultaneous lock of both loops is realized to totally phase-stabilize the comb, which will facilitate precision dual-comb spectroscopy, laser ranging, and timing distribution. In addition, a 1.8-MHz span of the repetition rate is achieved by an automatic optical delay line that is helpful in manufacturing a secondary comb with a similar repetition rate. The oscillator is housed in a homemade temperature-controlled box with an accuracy of ±0.02  K, which not only keeps high signal-to-noise ratio of the beat notes with reference lasers, but also guarantees self-starting at the same mode-locking every time.

  11. Optical timing receiver for the NASA Spaceborne Ranging System. Part II: high precision event-timing digitizer

    Energy Technology Data Exchange (ETDEWEB)

    Leskovar, Branko; Turko, Bojan

    1978-08-01

    Position-resolution capabilities of the NASA Spaceborne Laser Ranging System are essentially determined by the timeresolution capabilities of its optical timing receiver. The optical timing receiver consists of a fast photoelectric device; (e.g., photomultiplier or an avalanche photodiode detector), a timing discriminator, a high-precision event-timing digitizer, and a signal-processing system. The time-resolution capabilities of the receiver are determined by the photoelectron time spread of the photoelectric device, the time walk and resolution characteristics of the timing discriminator, and the resolution of the event-timing digitizer. It is thus necessary to evaluate available fast photoelectronic devices with respect to the time-resolution capabilities, and to develop a very low time walk timing discriminator and a high-resolution event-timing digitizer to be used in the high-resolution spaceborne laser ranging system receiver. This part of the report describes the development of a high precision event-timing digitizer. The event-timing digitizer is basically a combination of a very accurate high resolution real time digital clock and an interval timer. The timing digitizer is a high resolution multiple stop clock, counting the time up to 131 days in 19.5 ps increments.

  12. Phase-coded microwave signal generation based on a single electro-optical modulator and its application in accurate distance measurement.

    Science.gov (United States)

    Zhang, Fangzheng; Ge, Xiaozhong; Gao, Bindong; Pan, Shilong

    2015-08-24

    A novel scheme for photonic generation of a phase-coded microwave signal is proposed and its application in one-dimension distance measurement is demonstrated. The proposed signal generator has a simple and compact structure based on a single dual-polarization modulator. Besides, the generated phase-coded signal is stable and free from the DC and low-frequency backgrounds. An experiment is carried out. A 2 Gb/s phase-coded signal at 20 GHz is successfully generated, and the recovered phase information agrees well with the input 13-bit Barker code. To further investigate the performance of the proposed signal generator, its application in one-dimension distance measurement is demonstrated. The measurement accuracy is less than 1.7 centimeters within a measurement range of ~2 meters. The experimental results can verify the feasibility of the proposed phase-coded microwave signal generator and also provide strong evidence to support its practical applications.

  13. THE PULSATION OF χ CYGNI IMAGED BY OPTICAL INTERFEROMETRY: A NOVEL TECHNIQUE TO DERIVE DISTANCE AND MASS OF MIRA STARS

    International Nuclear Information System (INIS)

    Lacour, S.; Perrin, G.; Haubois, X.; Poncelet, A.; Thiebaut, E.; Meimon, S.; Pedretti, E.; Ridgway, S. T.; Monnier, J. D.; Berger, J. P.; Schuller, P. A.; Woodruff, H.; Le Coroller, H.; Millan-Gabet, R.; Lacasse, M.; Traub, W.

    2009-01-01

    We present infrared interferometric imaging of the S-type Mira star χ Cygni. The object was observed at four different epochs in 2005-2006 with the Infrared-Optical Telescope Array optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of the stellar diameter, and reveals presence and displacement of a warm molecular layer. The star radius, corrected for limb darkening, has a mean value of 12.1 mas and shows a 5.1 mas amplitude pulsation. Minimum diameter was observed at phase 0.94 ± 0.01. Maximum temperature was observed several days later at phase 1.02 ± 0.02. We also show that combining the angular acceleration of the molecular layer with CO (Δv = 3) radial velocity measurements yields a 5.9 ± 1.5 mas parallax. The constant acceleration of the CO molecules-during 80% of the pulsation cycle-lead us to argument for a free-falling layer. The acceleration is compatible with a gravitational field produced by a 2.1 +1.5 -0.7 solar mass star. This last value is in agreement with fundamental mode pulsator models. We foresee increased development of techniques consisting in combining radial velocity with interferometric angular measurements, ultimately allowing total mapping of the speed, density, and position of the diverse species in pulsation-driven atmospheres.

  14. Optical timing receiver for the NASA Spaceborne Ranging System. Part I. Dual peak-sensing timing discriminator

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.; Zizka, G.

    1978-01-01

    Position-resolution capabilities of the NASA Spaceborne Laser Ranging System are essentially determined by the time-resolution capabilities of its optical timing receiver. The optical timing receiver consists of a fast photoelectric device; (e.g., photomultiplier or an avalanche photodiode detector), a timing discriminator, a high-precision event-timing digitizer, and a signal-processing system. The time-resolution capabilities of the receiver are determined by the photoelectron time spread of the photoelectric device, the time walk and resolution characteristics of the timing discriminator, and the resolution of the event-timing digitizer. It is thus necessary to evaluate available fast photoelectronic devices with respect to their time-resolution capabilities, to design a very low time walk timing discriminator and to develop a high-resolution event-timing digitizer which will be used in the high-resolution spaceborne laser ranging system receiver. The development of a new dual-peak sensing timing discriminator is described. The amplitude dependent time walk is less than +-150 psec for a 100:1 dynamic range of Gaussian-shaped input signals having pulse widths between 11 and 17 nsec. The unit produces 800 mV negative output pulses, each 10 nsec wide, and 3V positive pulses with widths of 15 nsec. The time delay through the discriminator is approximately 37 nsec. In this discriminator the input signal is processed by a peak-crossing circuit which produces a bipolar pulse having its zero-crossing point at the peak of the input signal. All essential functions in the discriminator are performed by means of tunnel diodes with backward diodes as nonlinear loads. The discriminator is designed to be CAMAC compatible to a conventional time-interval unit or a high-precision event timing digitizer. The adjustment procedure for obtaining minimum time walk is also given

  15. MECHANISMS OF PRIMARY RECEPTION OF ELECTROMAGNETIC WAVES OF OPTICAL RANGE AS A BIOPHYSICAL BASIS OF POLARIZED LIGHT THERAPY

    Directory of Open Access Journals (Sweden)

    S. O. Hulyar

    2015-09-01

    Full Text Available An existence of separate functional system of electromagnetic balance regulation has been substantiated and a working conception of light puncture has been formulated. As a basis, there is a possibility to use the acupuncture points for input of biologically necessary electromagnetic waves into the system of their conductors in a body that might be considered as a transport facility for energy ofthe polarized electromagnetic waves. Zones-recipients are organs having an electromagnetic disbalance due to excess of biologically inadequate radiation and being the targets for peroxide oxidation, foremost, a body has the neurohormonal and immune regulatory systems. Electromagnetic stimulation or modification of functions of the zones-recipients determines achievement of therapeutic and useful effects, and their combination with local reparative processes allows attaining a clinical goal. We represent own and literary experimental data about development of physiological responses (analgesia, bronchospasm control, immune stimulation and inhibition of peroxide oxidation of lipids to BIOPTRON-light exposure on the acupuncture points or biologically active zones. We show the experimental facts in support of a hypothesis that a living organism can perceive an action of the electromagnetic waves of optical range not only via the visual system, but also through the off-nerve receptors (specific energy-sensitive proteins detecting critical changes of energy in cells and functioning as the "sensory" cell systems, as well as via the acupuncture points. This confirms an important role of the electromagnetic waves of optical range in providing normal vital functions of living organisms. A current approach to BIOPTRON light therapy consists in combined (local and system exposure of the electromagnetic waves within the biologically necessary range.

  16. High-dynamic-range microscope imaging based on exposure bracketing in full-field optical coherence tomography.

    Science.gov (United States)

    Leong-Hoi, Audrey; Montgomery, Paul C; Serio, Bruno; Twardowski, Patrice; Uhring, Wilfried

    2016-04-01

    By applying the proposed high-dynamic-range (HDR) technique based on exposure bracketing, we demonstrate a meaningful reduction in the spatial noise in image frames acquired with a CCD camera so as to improve the fringe contrast in full-field optical coherence tomography (FF-OCT). This new signal processing method thus allows improved probing within transparent or semitransparent samples. The proposed method is demonstrated on 3 μm thick transparent polymer films of Mylar, which, due to their transparency, produce low contrast fringe patterns in white-light interference microscopy. High-resolution tomographic analysis is performed using the technique. After performing appropriate signal processing, resulting XZ sections are observed. Submicrometer-sized defects can be lost in the noise that is present in the CCD images. With the proposed method, we show that by increasing the signal-to-noise ratio of the images, submicrometer-sized defect structures can thus be detected.

  17. Opto-electronic device for frequency standard generation and terahertz-range optical demodulation based on quantum interference

    Science.gov (United States)

    Georgiades, Nikos P.; Polzik, Eugene S.; Kimble, H. Jeff

    1999-02-02

    An opto-electronic system and technique for comparing laser frequencies with large frequency separations, establishing new frequency standards, and achieving phase-sensitive detection at ultra high frequencies. Light responsive materials with multiple energy levels suitable for multi-photon excitation are preferably used for nonlinear mixing via quantum interference of different excitation paths affecting a common energy level. Demodulation of a carrier with a demodulation frequency up to 100's THZ can be achieved for frequency comparison and phase-sensitive detection. A large number of materials can be used to cover a wide spectral range including the ultra violet, visible and near infrared regions. In particular, absolute frequency measurement in a spectrum from 1.25 .mu.m to 1.66 .mu.m for fiber optics can be accomplished with a nearly continuous frequency coverage.

  18. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    International Nuclear Information System (INIS)

    Soltani, A.; Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C.; Charrier, J.; Mattalah, M.; Barkad, H. A.; Mortet, V.; BenMoussa, A.

    2014-01-01

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films

  19. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr; Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C. [Institut d' Électronique, Microélectronique et Nanotechnologie, UMR-CNRS 8520, PRES Université Lille Nord de France, Cité Scientifique, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq Cedex (France); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON, UMR-CNRS 6082, ENSSAT 6, rue de Kerampont, CS 80518, 22305 Lannion Cedex (France); Mattalah, M. [Laboratoire de Microélectronique, Université Djilali Liabes, 22000 Sidi Bel Abbes (Algeria); Barkad, H. A. [Institut Universitaire Technologique Industriel, Université de Djibouti, Avenue Georges Clémenceau, BP 1904 Djibouti (Djibouti); Mortet, V. [Institute of Physics of Academy of Sciences of Czech Republic, Fyzikální ústav AV CR, v.v.i., Na Slovance 1999/2 (Czech Republic); BenMoussa, A. [Solar Terrestrial Center of Excellence, Royal Observatory of Belgium, Circular 3, B-1180 Brussels (Belgium)

    2014-04-28

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.

  20. High Precision Infrared Temperature Measurement System Based on Distance Compensation

    Directory of Open Access Journals (Sweden)

    Chen Jing

    2017-01-01

    Full Text Available To meet the need of real-time remote monitoring of human body surface temperature for optical rehabilitation therapy, a non-contact high-precision real-time temperature measurement method based on distance compensation was proposed, and the system design was carried out. The microcontroller controls the infrared temperature measurement module and the laser range module to collect temperature and distance data. The compensation formula of temperature with distance wass fitted according to the least square method. Testing had been performed on different individuals to verify the accuracy of the system. The results indicate that the designed non-contact infrared temperature measurement system has a residual error of less than 0.2°C and the response time isless than 0.1s in the range of 0 to 60cm. This provides a reference for developing long-distance temperature measurement equipment in optical rehabilitation therapy.

  1. Tourists consuming distance

    DEFF Research Database (Denmark)

    Larsen, Gunvor Riber

    The environmental impact of tourism mobility is linked to the distances travelled in order to reach a holiday destination, and with tourists travelling more and further than previously, an understanding of how the tourists view the distance they travel across becomes relevant. Based on interviews...... contribute to an understanding of how it is possible to change tourism travel behaviour towards becoming more sustainable. How tourists 'consume distance' is discussed, from the practical level of actually driving the car or sitting in the air plane, to the symbolic consumption of distance that occurs when...... travelling on holiday becomes part of a lifestyle and a social positioning game. Further, different types of tourist distance consumers are identified, ranging from the reluctant to the deliberate and nonchalant distance consumers, who display very differing attitudes towards the distance they all travel...

  2. Active thermal fine laser tuning in a broad spectral range and optical properties of cholesteric liquid crystal.

    Science.gov (United States)

    Jeong, Mi-Yun; Kwak, Keumcheol

    2016-11-20

    In this study, we achieved active fine laser tuning in a broad spectral range with dye-doped cholesteric liquid crystal wedge-type cells through temperature control. The spatial pitch gradient of each position of the wedge cell at room temperature was almost maintained after developing a temperature gradient. To achieve the maximum tuning range, the chiral dopant concentration, thickness, thickness gradient, and temperature gradient on the wedge cell should be matched properly. In order to understand the laser tuning mechanism for temperature change, we studied the temperature dependence of optical properties of the photonic bandgap of cholesteric liquid crystals. In our cholesteric liquid crystal samples, when temperature was increased, photonic bandgaps were shifted toward blue, while the width of the photonic bandgap was decreased, regardless of whether the helicity was left-handed or right-handed. This is mainly due to the combination of decreased refractive indices, higher molecular anisotropy of chiral molecules, and increased chiral molecular solubility. We envisage that this kind of study will prove useful in the development of practical active tunable CLC laser devices.

  3. Characterization of Articular Cartilage Recovery and Its Correlation with Optical Response in the Near-Infrared Spectral Range.

    Science.gov (United States)

    Afara, Isaac Oluwaseun; Singh, Sanjleena; Moody, Hayley; Zhang, Lihai; Oloyede, Adekunle

    2017-07-01

    In this study, we examine the capacity of a new parameter, based on the recovery response of articular cartilage, to distinguish between healthy and damaged tissues. We also investigate whether or not this new parameter correlates with the near-infrared (NIR) optical response of articular cartilage. Normal and artificially degenerated (proteoglycan-depleted) bovine cartilage samples were nondestructively probed using NIR spectroscopy. Subsequently they were subjected to a load and unloading protocol, and the recovery response was logged during unloading. The recovery parameter, elastic rebound ( E R ), is based on the strain energy released as the samples underwent instantaneous elastic recovery. Our results reveal positive relationship between the rebound parameter and cartilage proteoglycan content (normal samples: 2.20 ± 0.10 N mm; proteoglycan-depleted samples: 0.50 ± 0.04 N mm for 1 hour of enzymatic treatment and 0.13 ± 0.02 N mm for 4 hours of enzymatic treatment). In addition, multivariate analysis using partial least squares regression was employed to investigate the relationship between E R and NIR spectral data. The results reveal significantly high correlation ( R 2 cal = 98.35% and R 2 val = 79.87%; P cartilage in the combined NIR regions 5,450 to 6,100 cm -1 and 7,500 to 12,500 cm -1 . We conclude that E R can indicate the mechanical condition and state of health of articular cartilage. The correlation of E R with cartilage optical response in the NIR range could facilitate real-time evaluation of the tissue's integrity during arthroscopic surgery and could also provide an important tool for cartilage assessment in tissue engineering and regeneration research.

  4. Geometrical optics design of a compact range Gregorian subreflector system by the principle of the central ray

    Science.gov (United States)

    Clerici, Giancarlo; Burnside, Walter D.

    1989-01-01

    In recent years, the compact range has become very popular for measuring Radar Cross Section (RCS) and antenna patterns. The compact range, in fact, offers several advantages due to reduced size, a controlled environment, and privacy. On the other hand, it has some problems of its own, which must be solved properly in order to achieve high quality measurement results. For example, diffraction from the edges of the main reflector corrupts the plane wave in the target zone and creates spurious scattering centers in RCS measurements. While diffraction can be minimized by using rolled edges, the field of an offset single reflector compact range is corrupted by three other errors: the taper of the reflected field, the cross polarization introduced by the tilt of the feed and the aperture blockage introduced by the feed itself. These three errors can be eliminated by the use of a subreflector system. A properly designed subreflector system offers very little aperture blockage, no cross-polarization introduced and a minimization of the taper of the reflected field. A Gregorian configuration has been adopted in order to enclose the feed and the ellipsoidal subreflector in a lower chamber, which is isolated by absorbers from the upper chamber, where the main parabolic reflector and the target zone are enclosed. The coupling between the two rooms is performed through a coupling aperture. The first cut design for such a subreflector system is performed through Geometrical Optics ray tracing techniques (GO), and is greatly simplified by the use of the concept of the central ray introduced by Dragone. The purpose of the GO design is to establish the basic dimensions of the main reflector and subreflector, the size of the primary and secondary illuminating surfaces, the tilt angles of the subreflector and feed, and estimate the feed beamwidth. At the same time, the shape of the coupling aperture is initially determined.

  5. The 1979 convention on long range transfrontier air pollution; La convention sur la pollution atmospherique transfrontiere a longue distance de 1979

    Energy Technology Data Exchange (ETDEWEB)

    Jagusiewicz, A. [UNECE, Palais des Nations, Geneve (Switzerland)

    1997-12-31

    Applied in March 1983, the 1979 international Convention have induced five protocols related to sulfur, nitrogen oxide and VOC emissions. After 1994, three new protocols are under study, concerning the reduction of nitrogenous and related compounds, heavy metals and long-lasting organic pollutants. Works and organization of the European EMEP program for the continuous monitoring and evaluation of the long range air pollution transport in Europe, are presented

  6. Angular distribution of Pigment epithelium central limit-Inner limit of the retina Minimal Distance (PIMD), in the young not pathological optic nerve head imaged by OCT

    Science.gov (United States)

    Söderberg, Per G.; Sandberg-Melin, Camilla

    2018-02-01

    The present study aimed to elucidate the angular distribution of the Pigment epithelium central limit-Inner limit of the retina Minimal Distance measured over 2π radians in the frontal plane (PIMD-2π) in young healthy eyes. Both healthy eyes of 16 subjects aged [20;30[ years were included. In each eye, a volume of the optical nerve head (ONH) was captured three times with a TOPCON DRI OCT Triton (Japan). Each volume renders a representation of the ONH 2.8 mm along the sagittal axis resolved in 993 steps, 6 mm long the frontal axis resolved in 512 steps and 6 x mm along the longitudinal axis resolved in 256 steps. The captured volumes were transferred to a custom made software for semiautomatic segmentation of PIMD around the circumference of the ONH. The phases of iterated volumes were calibrated with cross correlation. It was found that PIMD-2π expresses a double hump with a small maximum superiorly, a larger maximum inferiorly, and minima in between. The measurements indicated that there is no difference of PIMD-2π between genders nor between dominant and not dominant eye within subject. The variation between eyes within subject is of the same order as the variation among subjects. The variation among volumes within eye is substantially lower.

  7. Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS in the red spectral range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2007-01-01

    Full Text Available A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm reflectance structures (i.e. "fingerprint" structures of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS, which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms. The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

  8. Correlation between short-range order, optical properties and UV-absorption ability in tellurate glasses; Poster M7

    Energy Technology Data Exchange (ETDEWEB)

    Burger, H; Tews, W; Vogel, W; Kozhukharov, V [Jena Univ. (Germany)

    1989-01-01

    Tellurate glasses, with as second components Al[sub 2]O[sub 3], PbO, PbF[sub 2], PbCl[sub 2], PbBr[sub 2], PbSO[sub 4], ZnO, B[sub 2]O[sub 3], P[sub 2]O[sub 5], Li[sub 2]O, Na[sub 2]O, K[sub 2]O, MgO and BaO as well as some glasses from ternary TeO[sub 2]-P[sub 2]O[sub 5]-RO systems (R is Pb, Ba and Zn ions), have been investigated. Transmittance spectra in UV and VIS region of some selected glasses have been measured. A correlation between optical properties and UV absorption edge of the transmittance have been done. Using p[sup 31]-NMR spectroscopy the structural changes on short-range level order are studied. A strong influence on the refraction and dispersion values as well as UV-absorption ability of the glasses is established. For p[sup 31] -NMR spectroscopy investigations of crystalline phosphotellurites and related phosphotellurite glasses the TeO[sub 2]-P[sub 2]O[sub 5B]aO ternary system have been chosen. (author).

  9. modelling distances

    Directory of Open Access Journals (Sweden)

    Robert F. Love

    2001-01-01

    Full Text Available Distance predicting functions may be used in a variety of applications for estimating travel distances between points. To evaluate the accuracy of a distance predicting function and to determine its parameters, a goodness-of-fit criteria is employed. AD (Absolute Deviations, SD (Squared Deviations and NAD (Normalized Absolute Deviations are the three criteria that are mostly employed in practice. In the literature some assumptions have been made about the properties of each criterion. In this paper, we present statistical analyses performed to compare the three criteria from different perspectives. For this purpose, we employ the ℓkpθ-norm as the distance predicting function, and statistically compare the three criteria by using normalized absolute prediction error distributions in seventeen geographical regions. We find that there exist no significant differences between the criteria. However, since the criterion SD has desirable properties in terms of distance modelling procedures, we suggest its use in practice.

  10. Development of a 3D optical scanning-based automatic quality assurance system for proton range compensators

    International Nuclear Information System (INIS)

    Kim, MinKyu; Ju, Sang Gyu; Chung, Kwangzoo; Hong, Chae-Seon; Kim, Jinsung; Ahn, Sung Hwan; Jung, Sang Hoon; Han, Youngyih; Chung, Yoonsun; Cho, Sungkoo; Choi, Doo Ho; Kim, Jungkuk; Shin, Dongho

    2015-01-01

    Purpose: A new automatic quality assurance (AutoRCQA) system using a three-dimensional scanner (3DS) with system automation was developed to improve the accuracy and efficiency of the quality assurance (QA) procedure for proton range compensators (RCs). The system performance was evaluated for clinical implementation. Methods: The AutoRCQA system consists of a three-dimensional measurement system (3DMS) based on 3DS and in-house developed verification software (3DVS). To verify the geometrical accuracy, the planned RC data (PRC), calculated with the treatment planning system (TPS), were reconstructed and coregistered with the measured RC data (MRC) based on the beam isocenter. The PRC and MRC inner surfaces were compared with composite analysis (CA) using 3DVS, using the CA pass rate for quantitative analysis. To evaluate the detection accuracy of the system, the authors designed a fake PRC by artificially adding small cubic islands with side lengths of 1.5, 2.5, and 3.5 mm on the inner surface of the PRC and performed CA with the depth difference and distance-to-agreement tolerances of [1 mm, 1 mm], [2 mm, 2 mm], and [3 mm, 3 mm]. In addition, the authors performed clinical tests using seven RCs [computerized milling machine (CMM)-RCs] manufactured by CMM, which were designed for treating various disease sites. The systematic offsets of the seven CMM-RCs were evaluated through the automatic registration function of AutoRCQA. For comparison with conventional technique, the authors measured the thickness at three points in each of the seven CMM-RCs using a manual depth measurement device and calculated thickness difference based on the TPS data (TPS-manual measurement). These results were compared with data obtained from 3DVS. The geometrical accuracy of each CMM-RC inner surface was investigated using the TPS data by performing CA with the same criteria. The authors also measured the net processing time, including the scan and analysis time. Results: The Auto

  11. Investigation of multilayer X-ray optics for 6 keV to 20 keV energy range

    Czech Academy of Sciences Publication Activity Database

    Oberta, Peter; Platonov, Y.; Flechsig, U.

    2012-01-01

    Roč. 19, č. 5 (2012), s. 675-681 ISSN 0909-0495 Institutional research plan: CEZ:AV0Z10100522 Keywords : X-ray optics * multilayer * energy resolution Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.186, year: 2012 http://journals.iucr.org/s/issues/2012/05/00/issconts.html

  12. White Rabbit Precision Time Protocol on Long-Distance Fiber Links

    NARCIS (Netherlands)

    Dierikx, E.F.; Dierikx, A.E.; Fordell, T.; Myyry, J.; Koponen, P.; Merimaa, M.; Pinkert, T.J.; Koelemeij, J.C.J.; Peek, H.Z.; Smets, R.

    2016-01-01

    The application of White Rabbit precision time protocol (WR-PTP) in long-distance optical fiber links has been investigated. WR-PTP is an implementation of PTP in synchronous Ethernet optical fiber networks, originally intended for synchronization of equipment within a range of 10 km. This paper

  13. Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders — from Optical Triangulation to the Automotive Field

    Directory of Open Access Journals (Sweden)

    Joe-Air Jiang

    2008-03-01

    Full Text Available With their significant features, the applications of complementary metal-oxidesemiconductor (CMOS image sensors covers a very extensive range, from industrialautomation to traffic applications such as aiming systems, blind guidance, active/passiverange finders, etc. In this paper CMOS image sensor-based active and passive rangefinders are presented. The measurement scheme of the proposed active/passive rangefinders is based on a simple triangulation method. The designed range finders chieflyconsist of a CMOS image sensor and some light sources such as lasers or LEDs. Theimplementation cost of our range finders is quite low. Image processing software to adjustthe exposure time (ET of the CMOS image sensor to enhance the performance oftriangulation-based range finders was also developed. An extensive series of experimentswere conducted to evaluate the performance of the designed range finders. From theexperimental results, the distance measurement resolutions achieved by the active rangefinder and the passive range finder can be better than 0.6% and 0.25% within themeasurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests onapplications of the developed CMOS image sensor-based range finders to the automotivefield were also conducted. The experimental results demonstrated that our range finders arewell-suited for distance measurements in this field.

  14. Distance Support In-Service Engineering for the High Energy Laser

    Science.gov (United States)

    2015-03-01

    FEL only) o Isoplanatic angle (if available) o Fried coherence length o Object distance o Dwell time o Laser spot size While many of the items...system and the HEL system. Acquisition Sensor Laser Subsystem Beam Shaping Sensor Suile . Range Finder -. Coarse Tracker . Fine Tracker Optical...distribution is unlimited DISTANCE SUPPORT IN-SERVICE ENGINEERING FOR THE HIGH ENERGY LASER by Team Raising HEL from a Distance Cohort 311-133O March

  15. Optics

    CERN Document Server

    Mathieu, Jean Paul

    1975-01-01

    Optics, Parts 1 and 2 covers electromagnetic optics and quantum optics. The first part of the book examines the various of the important properties common to all electromagnetic radiation. This part also studies electromagnetic waves; electromagnetic optics of transparent isotropic and anisotropic media; diffraction; and two-wave and multi-wave interference. The polarization states of light, the velocity of light, and the special theory of relativity are also examined in this part. The second part is devoted to quantum optics, specifically discussing the classical molecular theory of optical p

  16. Ultra-narrow bandpass filters for long range optical telecommunications at 1064nm and 1550nm, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Ultra-narrow bandpass filters with high off-band rejection are needed to maximize signal to noise for free space communications. Omega Optical is developing NIR...

  17. Wide range operation of regenerative optical parametric wavelength converter using ASE-degraded 43-Gb/s RZ-DPSK signals.

    Science.gov (United States)

    Gao, Mingyi; Kurumida, Junya; Namiki, Shu

    2011-11-07

    For sustainable growth of the Internet, wavelength-tunable optical regeneration is the key to scaling up high energy-efficiency dynamic optical path networks while keeping the flexibility of the network. Wavelength-tunable optical parametric regenerator (T-OPR) based on the gain saturation effect of parametric amplification in a highly nonlinear fiber is promising for noise reduction in phase-shift keying signals. In this paper, we experimentally evaluated the T-OPR performance for ASE-degraded 43-Gb/s RZ-DPSK signals over a 20-nm input wavelength range between 1527 nm and 1547 nm. As a result, we achieved improved power penalty performance for the regenerated idler with a proper pump power range.

  18. Simulation of beam-splitter made of metamaterials with angle spatial distribution of constitutive parameters based on transformation optics for THz frequency range

    International Nuclear Information System (INIS)

    Gurvitz, E A; Vozianova, A V; Khodzitsky, M K

    2014-01-01

    New approach to design beam splitter on basis of the transformation optics using angle constitutive parameters distribution of medium was proposed. The beam splitter was numerically simulated by COMSOL Multiphysics for terahertz frequency range. The numerical simulations were carried out for ideal and reduced constitutive parameters of medium for the case of TM plane wave

  19. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  20. Thermal coagulation-induced changes of the optical properties of normal and adenomatous human colon tissues in vitro in the spectral range 400-1100 nm

    International Nuclear Information System (INIS)

    Ao Huilan; Xing Da; Wei Huajiang; Gu Huaimin; Wu Guoyong; Lu Jianjun

    2008-01-01

    The absorption coefficients, the reduced scattering coefficients and the optical penetration depths for native and coagulated human normal and adenomatous colon tissues in vitro were determined over the range of 400-1100 nm using a spectrophotometer with an internal integrating sphere system, and the inverse adding-doubling method was applied to calculate the tissue optical properties from diffuse reflectance and total transmittance measurements. The experimental results showed that in the range of 400-1100 nm there were larger absorption coefficients (P < 0.01) and smaller reduced scattering coefficients (P < 0.01) for adenomatous colon tissues than for normal colon tissues, and there were smaller optical penetration depths for adenomatous colon tissues than for normal colon tissues, especially in the near-infrared wavelength. Thermal coagulation induced significant increase of the absorption coefficients and reduced scattering coefficients for the normal and adenomatous colon tissues, and significantly reduced decrease of the optical penetration depths for the normal and adenomatous colon tissues. The smaller optical penetration depth for coagulated adenomatous colon tissues is a disadvantage for laser-induced thermotherapy (LITT) and photodynamic therapy (PDT). It is necessary to adjust the application parameters of lasers to achieve optimal therapy

  1. Einstein at a distance

    Energy Technology Data Exchange (ETDEWEB)

    Lambourne, Robert [Department of Physics and Astronomy, Open University, Milton Keynes (United Kingdom)

    2005-11-01

    This paper examines the challenges and rewards that can arise when the teaching of Einsteinian physics has to be accomplished by means of distance education. The discussion is mainly based on experiences gathered over the past 35 years at the UK Open University, where special and general relativity, relativistic cosmology and other aspects of Einsteinian physics, have been taught at a variety of levels, and using a range of techniques, to students studying at a distance.

  2. Porous silicon-VO{sub 2} based hybrids as possible optical temperature sensor: Wavelength-dependent optical switching from visible to near-infrared range

    Energy Technology Data Exchange (ETDEWEB)

    Antunez, E. E.; Salazar-Kuri, U.; Estevez, J. O.; Basurto, M. A.; Agarwal, V., E-mail: vagarwal@uaem.mx [Centro de Investigación en Ingeniería y Ciencias Aplicadas, Instituto de Investigación en Ciencias Básicas y Aplicadas, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Mor. 62209 (Mexico); Campos, J. [Instituto de Energías Renovables, UNAM, Priv. Xochicalco S/N, Temixco, Mor. 62580 (Mexico); Jiménez Sandoval, S. [Laboratorio de Investigación en Materiales, Centro de Investigación y estudios Avanzados del Instituto Politécnico Nacional, Unidad Querétaro, Qro. 76001 (Mexico)

    2015-10-07

    Morphological properties of thermochromic VO{sub 2}—porous silicon based hybrids reveal the growth of well-crystalized nanometer-scale features of VO{sub 2} as compared with typical submicron granular structure obtained in thin films deposited on flat substrates. Structural characterization performed as a function of temperature via grazing incidence X-ray diffraction and micro-Raman demonstrate reversible semiconductor-metal transition of the hybrid, changing from a low-temperature monoclinic VO{sub 2}(M) to a high-temperature tetragonal rutile VO{sub 2}(R) crystalline structure, coupled with a decrease in phase transition temperature. Effective optical response studied in terms of red/blue shift of the reflectance spectra results in a wavelength-dependent optical switching with temperature. As compared to VO{sub 2} film over crystalline silicon substrate, the hybrid structure is found to demonstrate up to 3-fold increase in the change of reflectivity with temperature, an enlarged hysteresis loop and a wider operational window for its potential application as an optical temperature sensor. Such silicon based hybrids represent an exciting class of functional materials to display thermally triggered optical switching culminated by the characteristics of each of the constituent blocks as well as device compatibility with standard integrated circuit technology.

  3. Interactive Distance Learning in Connecticut.

    Science.gov (United States)

    Pietras, Jesse John; Murphy, Robert J.

    This paper provides an overview of distance learning activities in Connecticut and addresses the feasibility of such activities. Distance education programs have evolved from the one dimensional electronic mail systems to the use of sophisticated digital fiber networks. The Middlesex Distance Learning Consortium has developed a long-range plan to…

  4. Fluorescence based fibre optic pH sensor for the pH 10-13 range suitable for corrosion monitoring in concrete structures

    OpenAIRE

    Nguyen, T.H.; Venugopala, T.; Chen, S.; Sun, T.; Grattan, K. T. V.; Taylor, S.E.; Basheer, P.A.M.; Long, A.E.

    2014-01-01

    The design, development and evaluation of an optical fibre pH sensor for monitoring pH in the alkaline region are discussed in detail in this paper. The design of this specific pH sensor is based on the pH induced change in fluorescence intensity of a coumarin imidazole dye which is covalently attached to a polymer network and then fixed to the distal end of an optical fibre. The sensor provides a response over a pH range of 10.0 – 13.2 with an acceptable response rate of around 50 minutes, h...

  5. Adjustment of a goniometer for X-rays optics calibration in the spectral range 1.5-20 KeV

    International Nuclear Information System (INIS)

    Legistre, S.

    1992-10-01

    The aim of this memoir is the adjustment of a (θ, 2θ) goniometer coupled to X-rays source to calibrate mirrors (single layers like C, Ni, Au, etc... and multilayers like C/W, Si/W, etc...) in the spectral range 1.5 - 20 keV. For each kind of tested optics the adjustment of the goniometer include the procedure alignment of the different components (X-ray source, collimation slits, optics, detectors) and the first reflectivity measurements. Those measurements are compared those realized at LURE, using synchrotron radiation provided by SUPER ACO storage ring, and to a theoretical simulation

  6. Optical and Magneto-Optical Properties of Gd22Fe78 Thin Films in the Photon Energy Range From 1.5 to 5.5 eV

    Directory of Open Access Journals (Sweden)

    Eva Jesenská

    2016-01-01

    Full Text Available Optical and magneto-optical properties of amorphous Gd22Fe78 (GdFe thin films prepared by direct current (DC sputtering on thermally oxidized substrates were characterized by the combination of spectroscopic ellipsometry and magneto-optical spectroscopy in the photon energy range from 1.5 to 5.5 eV. Thin SiNx and Ru coatings were used to prevent the GdFe surface oxidation and contamination. Using advanced theoretical models spectral dependence of the complete permittivity tensor and spectral dependence of the absorption coefficient were deduced from experimental data. No significant changes in the optical properties upon different coatings were observed, indicating reliability of used analysis.

  7. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  8. Distance learning

    Directory of Open Access Journals (Sweden)

    Katarina Pucelj

    2006-12-01

    Full Text Available I would like to underline the role and importance of knowledge, which is acquired by individuals as a result of a learning process and experience. I have established that a form of learning, such as distance learning definitely contributes to a higher learning quality and leads to innovative, dynamic and knowledgebased society. Knowledge and skills enable individuals to cope with and manage changes, solve problems and also create new knowledge. Traditional learning practices face new circumstances, new and modern technologies appear, which enable quick and quality-oriented knowledge implementation. The centre of learning process at distance learning is to increase the quality of life of citizens, their competitiveness on the workforce market and ensure higher economic growth. Intellectual capital is the one, which represents the biggest capital of each society and knowledge is the key factor for succes of everybody, who are fully aware of this. Flexibility, openness and willingness of people to follow new IT solutions form suitable environment for developing and deciding to take up distance learning.

  9. Evaluation of white-to-white distance and anterior chamber depth measurements using the IOL Master, slit-lamp adapted optical coherence tomography and digital photographs in phakic eyes.

    Science.gov (United States)

    Wilczyński, Michał; Pośpiech-Zabierek, Aleksandra

    2015-01-01

    The accurate measurement of the anterior chamber internal diameter and depth is important in ophthalmic diagnosis and before some eye surgery procedures. The purpose of the study was to compare the white-to-white distance measurements performed using the IOL-Master and photography with internal anterior chamber diameter determined using slit lamp adapted optical coherence tomography in healthy eyes, and to compare anterior chamber depth measurements by IOL-Master and slit lamp adapted optical coherence tomography. The data were gathered prospectively from a non-randomized consecutive series of patients. The examined group consisted of 46 eyes of 39 patients. White-to-white was measured using IOL-Master and photographs of the eye were taken with a digital camera. Internal anterior chamber diameter was measured with slit-lamp adapted optical coherence tomography. Anterior chamber depth was measured using the IOL Master and slit-lamp adapted optical coherence tomography. Statistical analysis was performed using parametric tests. A Bland-Altman plot was drawn. White-to-white distance by the IOL Master was 11.8 +/- 0.40 mm, on photographs it was 11.29 +/- 0.58 mm and internal anterior chamber diameter by slit-lamp adapted optical coherence tomography was 11.34?0.54 mm. A significant difference was found between IOL-Master and slit-lamp adapted optical coherence tomography (pphotographs (pphotographs (p>0.05). All measurements were correlated (Spearman pphotographs. In order to obtain accurate measurements of the internal anterior chamber diameter and anterior chamber depth, a method involving direct visualization of intraocular structures should be used.

  10. Camera, handlens, and microscope optical system for imaging and coupled optical spectroscopy

    Science.gov (United States)

    Mungas, Greg S. (Inventor); Boynton, John (Inventor); Sepulveda, Cesar A. (Inventor); Nunes de Sepulveda, legal representative, Alicia (Inventor); Gursel, Yekta (Inventor)

    2012-01-01

    An optical system comprising two lens cells, each lens cell comprising multiple lens elements, to provide imaging over a very wide image distance and within a wide range of magnification by changing the distance between the two lens cells. An embodiment also provides scannable laser spectroscopic measurements within the field-of-view of the instrument.

  11. Rehearsal for Assessment of atmospheric optical Properties during biomass burning Events and Long-range transportation episodes at Metropolitan Area of São Paulo-Brazil (RAPEL)

    Science.gov (United States)

    Lopes, Fábio J. S.; Luis Guerrero-Rascado, Juan; Benavent-Oltra, Jose A.; Román, Roberto; Moreira, Gregori A.; Marques, Marcia T. A.; da Silva, Jonatan J.; Alados-Arboledas, Lucas; Artaxo, Paulo; Landulfo, Eduardo

    2018-04-01

    During the period of August-September 2016 an intensive campaign was carried out to assess aerosol properties in São Paulo-Brazil aiming to detect long-range aerosol transport events and to characterize the instrument regarding data quality. Aerosol optical properties retrieved by the GALION - LALINET SPU lidar station and collocated AERONET sunphotometer system are presented as extinction/ backscatter vertical profiles with microphysical products retrieved with GRASP inversion algorithm.

  12. Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. I. Experimental determination.

    Science.gov (United States)

    Dalstein, L; Revel, A; Humbert, C; Busson, B

    2018-04-07

    We experimentally determine the effective nonlinear second-order susceptibility of gold over the visible spectral range. To reach that goal, we probe by vibrational two-color sum-frequency generation spectroscopy the methyl stretching region of a dodecanethiol self-assembled monolayer adsorbed on a gold film. The sum-frequency generation spectra show a remarkable shape reversal when the visible probe wavelength is tuned from 435 to 705 nm. After correcting from Fresnel effects, the methyl stretching vibrations serve as an internal reference, allowing to extract the dispersion of the absolute phase and relative amplitude of the effective nonlinear optical response of gold in the visible range.

  13. Study of blood plasma optical properties in mice grafted with Ehrlich carcinoma in the frequency range 0.1-1.0 THz

    Science.gov (United States)

    Smolyanskaya, O. A.; Kravtsenyuk, O. V.; Panchenko, A. V.; Odlyanitskiy, E. L.; Guillet, J. P.; Cherkasova, O. P.; Khodzitsky, M. K.

    2017-12-01

    In the course of in vitro studies of blood of laboratory animals with progressing Ehrlich carcinoma, we have revealed the change of the blood plasma optical properties in the THz range, which can be used for developing the express diagnostics of the presence of oncological diseases. An applied software package is elaborated that allows the phantoms of biological samples having a complex structure to be numerically simulated and the parameters of the electromagnetic wave reflected from these samples in the THz frequency range to be calculated. Presented at the Fundamentals of Laser Micro- and Nanotechnologies (FLAMN-16) International Symposium (Pushkin, Leningrad oblast, 27 June to 1 July 2016).

  14. Range-Measuring Video Sensors

    Science.gov (United States)

    Howard, Richard T.; Briscoe, Jeri M.; Corder, Eric L.; Broderick, David

    2006-01-01

    Optoelectronic sensors of a proposed type would perform the functions of both electronic cameras and triangulation- type laser range finders. That is to say, these sensors would both (1) generate ordinary video or snapshot digital images and (2) measure the distances to selected spots in the images. These sensors would be well suited to use on robots that are required to measure distances to targets in their work spaces. In addition, these sensors could be used for all the purposes for which electronic cameras have been used heretofore. The simplest sensor of this type, illustrated schematically in the upper part of the figure, would include a laser, an electronic camera (either video or snapshot), a frame-grabber/image-capturing circuit, an image-data-storage memory circuit, and an image-data processor. There would be no moving parts. The laser would be positioned at a lateral distance d to one side of the camera and would be aimed parallel to the optical axis of the camera. When the range of a target in the field of view of the camera was required, the laser would be turned on and an image of the target would be stored and preprocessed to locate the angle (a) between the optical axis and the line of sight to the centroid of the laser spot.

  15. Fibre-tree network for water-surface ranging using an optical time-domain reflectometry technique

    Directory of Open Access Journals (Sweden)

    Yoshiaki Yamabayashi

    2014-10-01

    Full Text Available To monitor water level at long distance, a fibre-based time-domain reflectometry network is proposed. A collimator at each fibre end of a tree-type network retrieves 1.55 μm wavelength pulses that are reflected back from remote surfaces. Since this enables a power-supply-free sensor network with non-metal media, this system is expected to be less susceptible to lightning strikes and power cuts than conventional systems that use electrically powered sensors and metal cables. In the present Letter, a successful simultaneous monitoring experiment of two water levels in the laboratory, as well as a trial for detecting a disturbed surface by beam-expanding is reported.

  16. Short and long range gain monitoring of photomultipliers by means of a light pulser and an optical fibers bunch

    International Nuclear Information System (INIS)

    Besson, P.

    1989-01-01

    The gain monitoring of 8 XP3462 photomultipliers has been studied during a period of 3 months with a spark gap as a light pulser, an optical fibres bunch and 3 reference detectors. One of the reference PM is monitored thanks to a cristal of NaI irradiated by an 241 Am radioactive source, whereas the photodiode and its associated electronic is monitored thanks to a 57 Co source directly coupled to the junction. Two experimental methods have been tested. First the short term method consists in estimating several means of charge distributions and supposes the stability of different optical parameters like quantum efficiency or photoelectrons collection efficiency. The long term method consists in estimating several variances of charge distributions and supposes the validity, at first order, of photomultipliers' equations. In spite of unpropitious experimental conditions (tension switch off, no climatisation..), our results indicate that the short term method provides a precision of about 0.5% for the relative gain value but only during a short period which has been of 20 days. The long term method provides a precision of about 1.5% but is remained available during the 3 months of our experiment. This study has been developed for the new Neutrino oscillation program taking place near the Bugey nuclear plant and using 600 photomultipliers. The conclusions mentioned above are nevertheless valid for any particle detectors using photomultipliers [fr

  17. Ion-optical studies for a range adaptation method in ion beam therapy using a static wedge degrader combined with magnetic beam deflection

    International Nuclear Information System (INIS)

    Chaudhri, Naved; Saito, Nami; Bert, Christoph; Franczak, Bernhard; Steidl, Peter; Durante, Marco; Schardt, Dieter; Rietzel, Eike

    2010-01-01

    Fast radiological range adaptation of the ion beam is essential when target motion is mitigated by beam tracking using scanned ion beams for dose delivery. Electromagnetically controlled deflection of a well-focused ion beam on a small static wedge degrader positioned between two dipole magnets, inside the beam delivery system, has been considered as a fast range adaptation method. The principle of the range adaptation method was tested in experiments and Monte Carlo simulations for the therapy beam line at the GSI Helmholtz Centre for Heavy Ions Research. Based on the simulations, ion optical settings of beam deflection and realignment of the adapted beam were experimentally applied to the beam line, and additional tuning was manually performed. Different degrader shapes were employed for the energy adaptation. Measured and simulated beam profiles, i.e. lateral distribution and range in water at isocentre, were analysed and compared with the therapy beam values for beam scanning. Deflected beam positions of up to ±28 mm on degrader were performed which resulted in a range adaptation of up to ±15 mm water equivalence (WE). The maximum deviation between the measured adapted range from the nominal range adaptation was below 0.4 mm WE. In experiments, the width of the adapted beam at the isocentre was adjustable between 5 and 11 mm full width at half maximum. The results demonstrate the feasibility/proof of the proposed range adaptation method for beam tracking from the beam quality point of view.

  18. Lowest excited states and optical absorption spectra of donor–acceptor copolymers for organic photovoltaics: a new picture emerging from tuned long-range corrected density functionals

    KAUST Repository

    Pandey, Laxman; Doiron, Curtis; Sears, John S.; Bré das, Jean-Luc

    2012-01-01

    Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated. © 2012 the Owner Societies.

  19. Optical properties of InGaAs/InGaAlAs quantum wells for the 1520–1580 nm spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Gladyshev, A. G., E-mail: andrey.gladyshev@connector-optics.com; Novikov, I. I.; Karachinsky, L. Ya.; Denisov, D. V. [Connector Optics OOO (Russian Federation); Blokhin, S. A.; Blokhin, A. A.; Nadtochiy, A. M. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Kurochkin, A. S. [St. Petersburg National Research University of Information Technologies, Mechanics, and Optics (Russian Federation); Egorov, A. Yu. [Connector Optics OOO (Russian Federation)

    2016-09-15

    The optical properties of elastically strained semiconductor heterostructures with InGaAs/InGaAlAs quantum wells (QWs), intended for use in the formation of the active region of lasers emitting in the spectral range 1520–1580 nm, are studied. Active regions with varied lattice mismatch between the InGaAs QWs and the InP substrate are fabricated by molecular beam epitaxy. The maximum lattice mismatch for the InGaAs QWs is +2%. The optical properties of the elastically strained InGaAlAs/InGaAs/InP heterostructures are studied by the photoluminescence method in the temperature range from 20 to 140°C at various power densities of the excitation laser. Investigation of the optical properties of InGaAlAs/InGaAs/InP experimental samples confirms the feasibility of using the developed elastically strained heterostructures for the fabrication of active regions for laser diodes with high temperature stability.

  20. Optical model neutron cross sections calculations for Cu63, Cu65 and natural Cu in the energy range 1-15 Mev

    International Nuclear Information System (INIS)

    Iliescu, N.

    1975-01-01

    The theory of optical model and cross sections is developing. The neutron reactions considered in the high energy rate (0,1-15 MeV) were: total, elastic, elastic angular distributions, nonelastic, inelastic for resolved levels. This region was subdivided in two parts: in the first one, ranging from 0,1 to 1 MeV, the evaluation was mainly based on empirical fits of the experimental data, whereas in the second part the fits were carried out with theoretical models: optical and statistical. The potential parameters were obtained fitting the total, elastic, inelastic cross sections and elastic angular distributions. Using Hauser-Feshbach theory, angular distribution and cross sections for compound elastic scattering and inelastic scattering are calculated

  1. Optical performance of B-layer ultra-shallow-junction silicon photodiodes in the VUV spectral range

    NARCIS (Netherlands)

    Shi, L.; Sarubbi, F.; Nanver, L.K.; Kroth, U.; Gottwald, A.; Nihtianov, S.

    2010-01-01

    In recent work, a novel silicon-based photodiode technology was reported to be suitable for producing radiation detectors for 193 nm deep-ultraviolet light and for the extreme-ultraviolet (EUV) spectral range. The devices were developed and fabricated at the Delft Institute of Microsystems and

  2. Investigation into short-range order, electric conductivity and optical absorption edge of indium selenide thin amorphous films

    International Nuclear Information System (INIS)

    Bilyj, M.N.; Didyk, G.V.; Stetsiv, Ya.I.; Yurechko, R.Ya.

    1980-01-01

    Thin amorphous films of InSe have been obtained by the method of discrete vacuum evaporation of about 10 -2 Pa. The short-range order is investigated according to the radial distribution curves. The temperature and film thickness are shown to affect the character of conductivity. The width of the forbidden band determined by the fundamental absorption edge is found to depend on the time of film annealing

  3. Tracking frequency laser distance gauge

    International Nuclear Information System (INIS)

    Phillips, J.D.; Reasenberg, R.D.

    2005-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require laser distance gauges of substantially improved performance. We describe a laser gauge, based on Pound-Drever-Hall locking, in which the optical frequency is adjusted to maintain an interferometer's null condition. This technique has been demonstrated with pm performance. Automatic fringe hopping allows it to track arbitrary distance changes. The instrument is intrinsically free of the nm-scale cyclic bias present in traditional (heterodyne) high-precision laser gauges. The output is a radio frequency, readily measured to sufficient accuracy. The laser gauge has operated in a resonant cavity, which improves precision, can suppress the effects of misalignments, and makes possible precise automatic alignment. The measurement of absolute distance requires little or no additional hardware, and has also been demonstrated. The proof-of-concept version, based on a stabilized HeNe laser and operating on a 0.5 m path, has achieved 10 pm precision with 0.1 s integration time, and 0.1 mm absolute distance accuracy. This version has also followed substantial distance changes as fast as 16 mm/s. We show that, if the precision in optical frequency is a fixed fraction of the linewidth, both incremental and absolute distance precision are independent of the distance measured. We discuss systematic error sources, and present plans for a new version of the gauge based on semiconductor lasers and fiber-coupled components

  4. Photothermal modulation of the gap distance in scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Amer, N.M.; Skumanich, A.; Ripple, D.

    1986-01-01

    We have employed the photothermal effect to modulate the gap distance in a tunneling microscope. In this approach, optical heating induces the expansion and buckling of laser-illuminated sample surface. The surface displacement can be modulated over a wide frequency range, and its height (typically <1 A-circle) can be varied by changing the illumination intensity and modulation frequency. This novel method provides an alternative means for performing tunneling spectroscopy and microscopy, and for determining work functions of materials

  5. Highly sensitive digital optical sensor with large measurement range based on the dual-microring resonator with waveguide-coupled feedback

    International Nuclear Information System (INIS)

    Xiang Xing-Ye; Wang Kui-Ru; Yuan Jin-Hui; Jin Bo-Yuan; Sang Xin-Zhu; Yu Chong-Xiu

    2014-01-01

    We propose a novel high-performance digital optical sensor based on the Mach—Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of a conventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case

  6. Mean field for the p + 90Zr system in the energy range -60 MeV 90Zr from a dispersive optical-model analysis

    International Nuclear Information System (INIS)

    Romanovsky, E.A.; Bespalova, O.V.; Goncharov, S.A.; Pleshkov, D.V.; Spasskaya, T.I.

    2000-01-01

    Data on the scattering of protons with energies 5 MeV 90 Zr nuclei and data on the energies of proton particle and hole levels in the A + 1 and A - 1 systems with A = 90 are analyzed within the dispersive optical model. The parameters of the mean proton field for 90 Zr are determined in the energy range -60 MeV 3 He), ( 3 He, d), (n, d), and (d, n) reactions for levels near the Fermi surface and in (e, e'p) and (p, 2p) reactions for deep levels

  7. Detecting Topological Defect Dark Matter Using Coherent Laser Ranging System

    Science.gov (United States)

    Yang, Wanpeng; Leng, Jianxiao; Zhang, Shuangyou; Zhao, Jianye

    2016-01-01

    In the last few decades, optical frequency combs with high intensity, broad optical bandwidth, and directly traceable discrete wavelengths have triggered rapid developments in distance metrology. However, optical frequency combs to date have been limited to determine the absolute distance to an object (such as satellite missions). We propose a scheme for the detection of topological defect dark matter using a coherent laser ranging system composed of dual-combs and an optical clock via nongravitational signatures. The dark matter field, which comprises a defect, may interact with standard model particles, including quarks and photons, resulting in the alteration of their masses. Thus, a topological defect may function as a dielectric material with a distinctive frequency-depend index of refraction, which would cause the time delay of a periodic extraterrestrial or terrestrial light. When a topological defect passes through the Earth, the optical path of long-distance vacuum path is altered, this change in optical path can be detected through the coherent laser ranging system. Compared to continuous wavelength(cw) laser interferometry methods, dual-comb interferometry in our scheme excludes systematic misjudgement by measuring the absolute optical path length. PMID:27389642

  8. Long range surface plasmon resonance enhanced electro-optically tunable Goos-Hänchen shift and Imbert-Fedorov shift in ZnSe prism

    Science.gov (United States)

    Goswami, Nabamita; Kar, Aparupa; Saha, Ardhendu

    2014-11-01

    A new theoretical approach towards the tuning of Goos-Hänchen shift and Imbert-Fedorov shift for the reflected light beam is observed, designed and simulated in this paper through electro-optically tunable liquid crystal at an incident wavelength of 1550 nm within the communication window. Here the considered Kretschmann-Raether geometry comprises a ZnSe prism and a liquid crystal layer of E44 between two metal layers of silver, where with the application of electric field from (0-10) V electro-optically tuning of the Goos-Hänchen shift from 64.09 μm to -53.408 μm and the Imbert-Fedorov shift from 122.8 μm to -32.5 μm for a change in refractive index of the liquid crystal layer from 1.52-1.79 are envisaged. This idea expedites the scope of fine tuning in optical switching within the μm ranges.

  9. Enhanced optical transmission through a star-shaped bull's eye at dual resonant-bands in UV and the visible spectral range.

    Science.gov (United States)

    Nazari, Tavakol; Khazaeinezhad, Reza; Jung, Woohyun; Joo, Boram; Kong, Byung-Joo; Oh, Kyunghwan

    2015-07-13

    Dual resonant bands in UV and the visible range were simultaneously observed in the enhanced optical transmission (EOT) through star-shaped plasmonic structures. EOTs through four types of polygonal bull's eyes with a star aperture surrounded by the concentric star grooves were analyzed and compared for 3, 4, 5, and 6 corners, using finite difference time domain (FDTD) method. In contrast to plasmonic resonances in the visible range, the UV-band resonance intensity was found to scale with the number of corners, which is related with higher order multipole interactions. Spectral positions and relative intensities of the dual resonances were analyzed parametrically to find optimal conditions to maximize EOT in UV-visible dual bands.

  10. Room-temperature wide-range luminescence and structural, optical, and electrical properties of SILAR deposited Cu-Zn-S nano-structured thin films

    Science.gov (United States)

    Jose, Edwin; Kumar, M. C. Santhosh

    2016-09-01

    We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

  11. Ultra-stable long distance optical frequency distribution using the Internet fiber network and application to high-precision molecular spectroscopy

    International Nuclear Information System (INIS)

    Lopez, O; Chanteau, B; Bercy, A; Argence, B; Darquié, B; Chardonnet, C; Amy-Klein, A; Nicolodi, D; Zhang, W; Abgrall, M; Haboucha, A; Kanj, A; Rovera, D; Achkar, J; Pottie, P-E; Coq, Y Le; Santarelli, G

    2013-01-01

    We report an optical link of 540 km for ultrastable frequency distribution over the Internet fiber network. The phase-noise compensated link shows a fractional frequency instability in full bandwidth of 3×10 −14 at one second measurement time and 2×10 −18 at 30 000 s. This work is a significant step towards a sustainable wide area ultrastable optical frequency distribution and comparison network. Time transfer was demonstrated simultaneously on the same link and led to an absolute time accuracy (250 ps) and long-term timing stability (20 ps) which outperform the conventional satellite transfer methods by one order of magnitude. Current development addresses the question of multiple users distribution in the same metropolitan area. We demonstrate on-line extraction and first results show frequency stability at the same level as with conventional link. We also report an application to coherent frequency transfer to the mid-infrared. We demonstrate the frequency stabilisation of a mid-infrared laser to the near-infrared frequency reference transferred through the optical link. Fractional stability better than 4×10 −14 at 1 s averaging time was obtained, opening the way to ultrahigh resolution spectroscopy of molecular rovibrational transitions

  12. THE DISTANCE TO M104

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W. [University of Texas at Austin, McDonald Observatory, 2515 Speedway, Stop C1400 Austin, TX 78712 (United States); Skillman, Evan D. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, SE, University of Minnesota, Minneapolis, MN 55455 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Berg, Danielle [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Kennicutt, Robert, E-mail: kmcquinn@astro.as.utexas.edu [Institute for Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2016-11-01

    M104 (NGC 4594; the Sombrero galaxy) is a nearby, well-studied elliptical galaxy included in scores of surveys focused on understanding the details of galaxy evolution. Despite the importance of observations of M104, a consensus distance has not yet been established. Here, we use newly obtained Hubble Space Telescope optical imaging to measure the distance to M104 based on the tip of the red giant branch (TRGB) method. Our measurement yields the distance to M104 to be 9.55 ± 0.13 ± 0.31 Mpc equivalent to a distance modulus of 29.90 ± 0.03 ± 0.07 mag. Our distance is an improvement over previous results as we use a well-calibrated, stable distance indicator, precision photometry in a optimally selected field of view, and a Bayesian maximum likelihood technique that reduces measurement uncertainties. The most discrepant previous results are due to Tully–Fisher method distances, which are likely inappropriate for M104 given its peculiar morphology and structure. Our results are part of a larger program to measure accurate distances to a sample of well-known spiral galaxies (including M51, M74, and M63) using the TRGB method.

  13. Aerosol Optical Properties at the Lulin Atmospheric Background Station in Taiwan and the Influences of Long-Range Transport of Air Pollutants

    Science.gov (United States)

    Hsiao, Ta-Chih; Chen, Wei-Nai; Ye, Wei-Cheng; Lin, Neng-Huei; Tsay, Si-Chee; Lin, Tang-Huang; Lee, Chung-Te; Chuang, Ming-Tung; Pantina, Peter; Wang, Sheng-Hsiang

    2016-01-01

    The Lulin Atmospheric Background Station (LABS, 23.47 deg. N 120.87 deg. E, 2862 m ASL) in Central Taiwan was constructed in 2006 and is the only high-altitude background station in the western Pacific region for studying the influence of continental outflow. In this study, extensive optical properties of aerosols, including the aerosol light scattering coefficient [Sigma(sub s)] and light absorption coefficient [Sigma(sub a)], were collected from 2013 to 2014. The intensive optical properties, including mass scattering efficiency [Sigma(sub s)], mass absorption efficiency [Sigma(sub a)] single scattering albedo (Omega), scattering Angstrom exponent (A), and backscattering fraction (b), were determined and investigated, and the distinct seasonal cycle was observed. The value of [Alpha(sub a)] began to increase in January and reached a maximum in April; the mean in spring was 5.89 m(exp. 2) g(exp. -1) with a standard deviation (SD) of 4.54 m(exp. 2) g(exp. -1) and a 4.48 m(exp. 2) g(exp. -1) interquartile range (IQR: 2.95-7.43 m(exp. 2) g(exp. -1). The trend was similar in [Sigma(sub a)], with a maximum in March and a monthly mean of 0.84 m(exp. 2) g(exp. -1). The peak values of Omega (Mean = 0.92, SD = 0.03, IQR: 0.90 - 0.93) and A (Mean = 2.22, SD = 0.61, IQR: 2.12 = 2.47) occurred in autumn. These annual patterns of optical properties were associated with different long-range transport patterns of air pollutants such as biomass burning (BB) aerosol in spring and potential anthropogenic emissions in autumn. The optical measurements performed at LABS during spring in 2013 were compared with those simultaneously performed at the Doi Ang Kang Meteorology Station, Chiang Mai Province, Thailand (DAK, 19.93 deg. N, 99.05 deg. E, 1536 m a.s.l.), which is located in the Southeast Asia BB source region. Furthermore, the relationships among [Sigma(sub s)], [Sigma(sub a)], and (b) were used to characterize the potential aerosol types transported to LABS during different

  14. Aerosol optical properties at the Lulin Atmospheric Background Station in Taiwan and the influences of long-range transport of air pollutants

    Science.gov (United States)

    Hsiao, Ta-Chih; Chen, Wei-Nai; Ye, Wei-Cheng; Lin, Neng-Huei; Tsay, Si-Chee; Lin, Tang-Huang; Lee, Chung-Te; Chuang, Ming-Tung; Pantina, Peter; Wang, Sheng-Hsiang

    2017-02-01

    The Lulin Atmospheric Background Station (LABS, 23.47°N 120.87°E, 2862 m ASL) in Central Taiwan was constructed in 2006 and is the only high-altitude background station in the western Pacific region for studying the influence of continental outflow. In this study, extensive optical properties of aerosols, including the aerosol light scattering coefficient (σs) and light absorption coefficient (σa), were collected from 2013 to 2014. The intensive optical properties, including mass scattering efficiency (αs), mass absorption efficiency (αa), single scattering albedo (ω), scattering Ångstrӧm exponent (Å), and backscattering fraction (b), were determined and investigated, and the distinct seasonal cycle was observed. The value of αs began to increase in January and reached a maximum in April; the mean in spring was 5.89 m2 g-1 with a standard deviation (SD) of 4.54 m2 g-1 and a 4.48 m2 g-1 interquartile range (IQR: 2.95-7.43 m2 g-1). The trend was similar in αa, with a maximum in March and a monthly mean of 0.84 m2 g-1. The peak values of ω (Mean = 0.92, SD = 0.03, IQR: 0.90-0.93) and Å (Mean = 2.22, SD = 0.61, IQR: 2.12-2.47) occurred in autumn. These annual patterns of optical properties were associated with different long-range transport patterns of air pollutants such as biomass burning (BB) aerosol in spring and potential anthropogenic emissions in autumn. The optical measurements performed at LABS during spring in 2013 were compared with those simultaneously performed at the Doi Ang Kang Meteorology Station, Chiang Mai Province, Thailand (DAK, 19.93°N, 99.05°E, 1536 m a.s.l.), which is located in the Southeast Asia BB source region. Furthermore, the relationships among αs, αa, and b were used to characterize the potential aerosol types transported to LABS during different seasons, and the data were inspected according to the HYSPLIT 5-day backward trajectories, which differentiate between different regions of air mass origin.

  15. γ and fission-reactor radiation effects on the visible-range transparency of aluminum-jacketed, all-silica optical fibers

    Science.gov (United States)

    Griscom, David L.

    1996-08-01

    Four aluminum-jacketed, fluorine-doped silica clad optical fibers with silica core materials fabricated by differing technologies were subjected to sequential 60Co-γ ray and fission-reactor irradiations (at ˜20 and 40 °C, respectively), an intervening isothermal anneal (˜20 °C), and a final isochronal anneal (to 600 °C) while monitoring the radiation-induced absorption spectra in the range ˜400-1000 nm. The two low-OH/low-chloride core fibers (one of which was doped with 0.5 mass % fluorine) both developed bands at 660 and 760 nm which exceeded 10 000 dB/km for doses in the range ˜102-106 Gy(Si); however, these bands declined to irradiation phase [12 MGy(Si) at 5.6 Gy(Si)/s]. All fibers displayed an ``UV band tail,'' which was the strongest in the high-chloride core fiber, as well as bands in the range ˜600-630 nm generally attributed to nonbridging-oxygen hole centers (NBOHCs). During the γ-irradiation phase the strengths of the NBOHC bands proved to be strongly dependent on the method of core material manufacture. Contrary to previous results for acrylate-jacketed fibers, no substantial bleaching of the UV-tail or NBOHC bands took place during γ irradiation despite the continuous propagation of white light powers ˜5-50 μW. The incremental induced absorption spectra consequent to the reactor-irradiation [˜4 MGy(Si) γ-ray dose at 70 Gy(Si)/s, plus a fluence of ≳2.8-MeV neutrons ˜2×1016 cm-2] were much less sensitive to fiber core material. The prospects for developing rad hard optical fibers for fusion reactor diagnostics are discussed in light of these findings.

  16. Nonimaging optical illumination system

    Energy Technology Data Exchange (ETDEWEB)

    Winston, R.; Ries, H.

    2000-02-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source, a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t) = k(t) + Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  17. High-order nonlinear optical processes in ablated carbon-containing materials: Recent approaches in development of the nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range

    Science.gov (United States)

    Ganeev, R. A.

    2017-08-01

    The nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range became a versatile tool for the analysis of the optical, structural and morphological properties of matter. The carbon-contained materials have shown the advanced properties among other studied species, which allowed both the definition of the role of structural properties on the nonlinear optical response and the analysis of the fundamental features of carbon as the attractive material for generation of coherent short-wavelength radiation. We review the studies of the high-order harmonic generation by focusing ultrashort pulses into the plasmas produced during laser ablation of various organic compounds. We discuss the role of ionic transitions of ablated carbon-containing molecules on the harmonic yield. We also show the similarities and distinctions of the harmonic and plasma spectra of organic compounds and graphite. We discuss the studies of the generation of harmonics up to the 27th order (λ = 29.9 nm) of 806 nm radiation in the boron carbide plasma and analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by comparing plasma emission and harmonic spectra from three species. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic.

  18. INSIGHTS INTO THE CEPHEID DISTANCE SCALE

    International Nuclear Information System (INIS)

    Bono, G.; Caputo, F.; Marconi, M.; Musella, I.

    2010-01-01

    We present a detailed investigation of the Cepheid distance scale by using both theory and observations. Through the use of pulsation models for fundamental mode Cepheids, we found that the slope of the period-luminosity (P-L) relation covering the entire period range (0.40 ≤ log P ≤ 2.0) becomes steeper when moving from optical to near-infrared (NIR) bands, and that the metallicity dependence of the slope decreases from the B- to the K band. The sign of the metallicity dependence for the slopes of the P-L V and P-L I relation is at odds with some recent empirical estimates. We determined new homogeneous estimates of V- and I-band slopes for 87 independent Cepheid data sets belonging to 48 external galaxies with nebular oxygen abundance 7.5 ≤ 12 + log (O/H) ≤ 8.9. By using Cepheid samples including more than 20 Cepheids, the χ 2 test indicates that the hypothesis of a steepening of the P-L V,I relations with increased metal content can be discarded at the 99% level. On the contrary, the observed slopes agree with the metallicity trend predicted by pulsation models, i.e., the slope is roughly constant for galaxies with 12+log (O/H) 2 test concerning the hypothesis that the slope does not depend on metallicity gives confidence levels either similar (PL V , 62%) or smaller (PL I , 67%). We investigated the dependence of the period-Wesenheit (P-W) relations on the metal content and we found that the slopes of optical and NIR P-W relations in external galaxies are similar to the slopes of Large Magellanic Cloud (LMC) Cepheids. They also agree with the theoretical predictions suggesting that the slopes of the P-W relations are independent of the metal content. On this ground, the P-W relations provide a robust method to determine distance moduli relative to the LMC, but theory and observations indicate that the metallicity dependence of the zero point in the different passbands has to be taken into account. To constrain this effect, we compared the independent

  19. Depth Dose Measurement using a Scintillating Fiber Optic Dosimeter for Proton Therapy Beam of the Passive-Scattering Mode Having Range Modulator Wheel

    Science.gov (United States)

    Hwang, Ui-Jung; Shin, Dongho; Lee, Se Byeong; Lim, Young Kyung; Jeong, Jong Hwi; Kim, Hak Soo; Kim, Ki Hwan

    2018-05-01

    To apply a scintillating fiber dosimetry system to measure the range of a proton therapy beam, a new method was proposed to correct for the quenching effect on measuring an spread out Bragg peak (SOBP) proton beam whose range is modulated by a range modulator wheel. The scintillating fiber dosimetry system was composed of a plastic scintillating fiber (BCF-12), optical fiber (SH 2001), photo multiplier tube (H7546), and data acquisition system (PXI6221 and SCC68). The proton beam was generated by a cyclotron (Proteus-235) in the National Cancer Center in Korea. It operated in the double-scattering mode and the spread out of the Bragg peak was achieved by a spinning range modulation wheel. Bragg peak beams and SOBP beams of various ranges were measured, corrected, and compared to the ion chamber data. For the Bragg peak beam, quenching equation was used to correct the quenching effect. On the proposed process of correcting SOBP beams, the measured data using a scintillating fiber were separated by the Bragg peaks that the SOBP beam contained, and then recomposed again to reconstruct an SOBP after correcting for each Bragg peak. The measured depth-dose curve for the single Bragg peak beam was well corrected by using a simple quenching equation. Correction for SOBP beam was conducted with a newly proposed method. The corrected SOBP signal was in accordance with the results measured with an ion chamber. We propose a new method to correct for the SOBP beam from the quenching effect in a scintillating fiber dosimetry system. This method can be applied to other scintillator dosimetry for radiation beams in which the quenching effect is shown in the scintillator.

  20. Luminescence excitation characteristics of Ca-, Na- and K-aluminosilicates (feldspars), in the stimulation range 20-500 eV: optical detection of XAS

    CERN Document Server

    Poolton, N R J; Quinn, F M; Pantos, E; Andersen, C E; Bøtter-Jensen, L; Johnsen, O; Murray, A S

    2003-01-01

    We demonstrate that the visible/UV luminescence from common feldspar crystals (NaAlSi sub 3 O sub 8 , KAlSi sub 3 O sub 8 and CaAl sub 2 Si sub 2 O sub 8) can be used to detect detailed L-edge and associated near-edge absorption structure of the main constituent atoms (Ca, K, Na, Al, Si), when exciting in the energy range 20-500 eV. Comparisons of the spectral features are drawn with similar measurements made on the associated materials SiO sub 2 , Al sub 2 O sub 3 and CaCO sub 3. The potential for using optically detected x-ray absorption spectroscopy as a method for identifying the luminescent components of mixed mineral samples is considered.

  1. Laboratory reflectometer for the investigation of optical elements in a wavelength range of 5-50 nm: description and testing results

    Science.gov (United States)

    Garakhin, S. A.; Zabrodin, I. G.; Zuev, S. E.; Kas'kov, I. A.; Lopatin, A. Ya.; Nechay, A. N.; Polkovnikov, V. N.; Salashchenko, N. N.; Tsybin, N. N.; Chkhalo, N. I.; Svechnikov, M. V.

    2017-05-01

    We describe a laboratory reflectometer developed at the IPM RAS for precision measurements of spectral and angular dependences of the reflection and transmission coefficients of optical elements in a wavelength range of 5-50 nm. The radiation is monochromatised using a high-resolution Czerny-Turner spectrometer with a plane diffraction grating and two spherical collimating mirrors. A toroidal mirror focuses the probe monochromatic beam on a sample. The X-ray source is a highly ionised plasma produced in the interaction of a high-power laser beam with a solid target at an intensity of 1011-1012 W cm-2. To stabilise the emission characteristics, the target executes translatory and rotary motions in such a way that every pulse irradiates a new spot. The short-focus lens is protected from contamination by erosion products with the use of a specially designed electromagnetic system. The samples under study are mounted on a goniometer is accommodated in a dedicated chamber, which provides five degrees of freedom for samples up to 500 mm in diameter and two degrees of freedom for a detector. The sample mass may range up to 10 kg. The X-ray radiation is recorded with a detector composed of a CsI photocathode and two microchannel plates. A similar detector monitors the probe beam intensity. The spectral reflectometer resolution is equal to 0.030 nm with the use of ruled gratings with a density of 900 lines mm-1 (spectral range: 5-20 nm) and to 0.067 nm for holographic gratings with a density of 400 lines mm-1 (spectral range: 10-50 nm). We analyse the contribution of higher diffraction orders to the probe signal intensity and the ways of taking it into account in the measurements. Examples are given which serve to illustrate the reflectometer application to the study of multilayer mirrors and filters.

  2. Shear force distance control in a scanning near-field optical microscope: in resonance excitation of the fiber probe versus out of resonance excitation

    International Nuclear Information System (INIS)

    Lapshin, D.A.; Letokhov, V.S.; Shubeita, G.T.; Sekatskii, S.K.; Dietler, G.

    2004-01-01

    The experimental results of the direct measurement of the absolute value of interaction force between the fiber probe of a scanning near-field optical microscope (SNOM) operated in shear force mode and a sample, which were performed using combined SNOM-atomic force microscope setup, are discussed for the out-of-resonance fiber probe excitation mode. We demonstrate that the value of the tapping component of the total force for this mode at typical dither amplitudes is of the order of 10 nN and thus is quite comparable with the value of this force for in resonance fiber probe excitation mode. It is also shown that for all modes this force component is essentially smaller than the usually neglected static attraction force, which is of the order of 200 nN. The true contact nature of the tip-sample interaction during the out of resonance mode is proven. From this, we conclude that such a detection mode is very promising for operation in liquids, where other modes encounter great difficulties

  3. Long ranging swept-source optical coherence tomography-based angiography outperforms its spectral-domain counterpart in imaging human skin microcirculations

    Science.gov (United States)

    Xu, Jingjiang; Song, Shaozhen; Men, Shaojie; Wang, Ruikang K.

    2017-11-01

    There is an increasing demand for imaging tools in clinical dermatology that can perform in vivo wide-field morphological and functional examination from surface to deep tissue regions at various skin sites of the human body. The conventional spectral-domain optical coherence tomography-based angiography (SD-OCTA) system is difficult to meet these requirements due to its fundamental limitations of the sensitivity roll-off, imaging range as well as imaging speed. To mitigate these issues, we demonstrate a swept-source OCTA (SS-OCTA) system by employing a swept source based on a vertical cavity surface-emitting laser. A series of comparisons between SS-OCTA and SD-OCTA are conducted. Benefiting from the high system sensitivity, long imaging range, and superior roll-off performance, the SS-OCTA system is demonstrated with better performance in imaging human skin than the SD-OCTA system. We show that the SS-OCTA permits remarkable deep visualization of both structure and vasculature (up to ˜2 mm penetration) with wide field of view capability (up to 18×18 mm2), enabling a more comprehensive assessment of the morphological features as well as functional blood vessel networks from the superficial epidermal to deep dermal layers. It is expected that the advantages of the SS-OCTA system will provide a ground for clinical translation, benefiting the existing dermatological practice.

  4. Active Stand-off Detection of Gas Leaks Using a Short Range Hard-target Backscatter Differential Optical Absorption System Based on a Quantum Cascade Laser Transmitter

    Science.gov (United States)

    Diaz, Adrian; Thomas, Benjamin; Castillo, Paulo; Gross, Barry; Moshary, Fred

    2016-06-01

    Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they can contribute to the global increase of greenhouse gas concentration. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents gas concentration measurements using a quantum cascade laser open path system (QCLOPS). The system retrieves the pathaveraged concentration of N2O and CH4 by collecting the backscattered light from a scattering target. The gas concentration measurements have a high temporal resolution (68 ms) and are achieved at sufficient range (up to 40 m, ~ 130 feet) with a detection limit of 2.6 ppm CH4 and 0.4 ppm for N2O. Given these characteristics, this system is promising for mobile/multidirectional remote detection and evaluation of gas leaks. The instrument is monostatic with a tunable QCL emitting at ~ 7.7 μm wavelength range. The backscattered radiation is collected by a Newtonian telescope and focused on an infrared light detector. Puffs of N2O and CH4 are released along the optical path to simulate a gas leak. The measured absorption spectrum is obtained using the thermal intra-pulse frequency chirped DFB QCL and is analyzed to obtain path averaged gas concentrations.

  5. Optical properties of TiBe2 in the range from 0.5 to 3.3 eV

    NARCIS (Netherlands)

    Wijers, C.; Groot, R.A. de; Vroomen, A.R. de; Mueller, F.M.

    1984-01-01

    The optical properties of polycrystalline TiBe2 have been determined by ellipsometry in the visible and infrared region. The most predominant features of the spectra are in excellent agreement with a calculation of the optical conductivity.

  6. Optical networks and laboratory services

    International Nuclear Information System (INIS)

    Ciaffoni, O.; Ferrer, M.L.; Trasatti, L.

    1987-01-01

    Possible technical solutions to the problem of high speed data links between laboratories are presented. Long distance networks (WAN), ranging from tens to hundreds of kilometers, offer a variety of possibilities, from standard 64 Kbit/s connections to optical fiber links and radio or satellite Mbit channels. Short range (up to 2-3 km) communications are offered by many existing LAN (local area network) standards up to 10 Mbit/s. The medium distance range (around 10 km) can be covered by high performance fiber optic links and the now emerging MAN (metropolitan area network) protocols. A possible area of application is between the Gran Sasso Tunnel Laboratory, the outside installations and other Italien and foreign laboratories. (orig.)

  7. Preparation and analysis of anodic aluminum oxide films with continuously tunable interpore distances

    Science.gov (United States)

    Qin, Xiufang; Zhang, Jinqiong; Meng, Xiaojuan; Deng, Chenhua; Zhang, Lifang; Ding, Guqiao; Zeng, Hao; Xu, Xiaohong

    2015-02-01

    Nanoporous anodic aluminum oxides are often used as templates for preparation of nanostructures such as nanodot, nanowire and nanotube arrays. The interpore distance of anodic aluminum oxide is the most important parameter in controlling the periodicity of these nanostructures. Herein we demonstrate a simple and yet powerful method to fabricate ordered anodic aluminum oxides with continuously tunable interpore distances. By using mixed solution of citric and oxalic acids with different molar ratio, the range of anodizing voltages within which self-ordered films can be formed were extended to between 40 and 300 V, resulting in the interpore distances change from 100 to 750 nm. Our work realized very broad range of interpore distances in a continuously tunable fashion and the experiment processes are easily controllable and reproducible. The dependence of the interpore distances on acid ratios in mixed solutions was discussed through analysis of anodizing current and it was found that the effective dissociation constant of the mixed acids is of great importance. The interpore distances achieved are comparable to wavelengths ranging from UV to near IR, and may have potential applications in optical meta-materials for photovoltaics and optical sensing.

  8. Transmission system for distribution of video over long-haul optical point-to-point links using a microwave photonic filter in the frequency range of 0.01-10 GHz

    Science.gov (United States)

    Zaldívar Huerta, Ignacio E.; Pérez Montaña, Diego F.; Nava, Pablo Hernández; Juárez, Alejandro García; Asomoza, Jorge Rodríguez; Leal Cruz, Ana L.

    2013-12-01

    We experimentally demonstrate the use of an electro-optical transmission system for distribution of video over long-haul optical point-to-point links using a microwave photonic filter in the frequency range of 0.01-10 GHz. The frequency response of the microwave photonic filter consists of four band-pass windows centered at frequencies that can be tailored to the function of the spectral free range of the optical source, the chromatic dispersion parameter of the optical fiber used, as well as the length of the optical link. In particular, filtering effect is obtained by the interaction of an externally modulated multimode laser diode emitting at 1.5 μm associated to the length of a dispersive optical fiber. Filtered microwave signals are used as electrical carriers to transmit TV-signal over long-haul optical links point-to-point. Transmission of TV-signal coded on the microwave band-pass windows located at 4.62, 6.86, 4.0 and 6.0 GHz are achieved over optical links of 25.25 km and 28.25 km, respectively. Practical applications for this approach lie in the field of the FTTH access network for distribution of services as video, voice, and data.

  9. Analytic processing of distance.

    Science.gov (United States)

    Dopkins, Stephen; Galyer, Darin

    2018-01-01

    How does a human observer extract from the distance between two frontal points the component corresponding to an axis of a rectangular reference frame? To find out we had participants classify pairs of small circles, varying on the horizontal and vertical axes of a computer screen, in terms of the horizontal distance between them. A response signal controlled response time. The error rate depended on the irrelevant vertical as well as the relevant horizontal distance between the test circles with the relevant distance effect being larger than the irrelevant distance effect. The results implied that the horizontal distance between the test circles was imperfectly extracted from the overall distance between them. The results supported an account, derived from the Exemplar Based Random Walk model (Nosofsky & Palmieri, 1997), under which distance classification is based on the overall distance between the test circles, with relevant distance being extracted from overall distance to the extent that the relevant and irrelevant axes are differentially weighted so as to reduce the contribution of irrelevant distance to overall distance. The results did not support an account, derived from the General Recognition Theory (Ashby & Maddox, 1994), under which distance classification is based on the relevant distance between the test circles, with the irrelevant distance effect arising because a test circle's perceived location on the relevant axis depends on its location on the irrelevant axis, and with relevant distance being extracted from overall distance to the extent that this dependency is absent. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Encyclopedia of distances

    CERN Document Server

    Deza, Michel Marie

    2016-01-01

    This 4th edition of the leading reference volume on distance metrics is characterized by updated and rewritten sections on some items suggested by experts and readers, as well a general streamlining of content and the addition of essential new topics. Though the structure remains unchanged, the new edition also explores recent advances in the use of distances and metrics for e.g. generalized distances, probability theory, graph theory, coding theory, data analysis. New topics in the purely mathematical sections include e.g. the Vitanyi multiset-metric, algebraic point-conic distance, triangular ratio metric, Rossi-Hamming metric, Taneja distance, spectral semimetric between graphs, channel metrization, and Maryland bridge distance. The multidisciplinary sections have also been supplemented with new topics, including: dynamic time wrapping distance, memory distance, allometry, atmospheric depth, elliptic orbit distance, VLBI distance measurements, the astronomical system of units, and walkability distance. Lea...

  11. Hierarchical traits distances explain grassland Fabaceae species' ecological niches distances

    Science.gov (United States)

    Fort, Florian; Jouany, Claire; Cruz, Pablo

    2015-01-01

    Fabaceae species play a key role in ecosystem functioning through their capacity to fix atmospheric nitrogen via their symbiosis with Rhizobium bacteria. To increase benefits of using Fabaceae in agricultural systems, it is necessary to find ways to evaluate species or genotypes having potential adaptations to sub-optimal growth conditions. We evaluated the relevance of phylogenetic distance, absolute trait distance and hierarchical trait distance for comparing the adaptation of 13 grassland Fabaceae species to different habitats, i.e., ecological niches. We measured a wide range of functional traits (root traits, leaf traits, and whole plant traits) in these species. Species phylogenetic and ecological distances were assessed from a species-level phylogenetic tree and species' ecological indicator values, respectively. We demonstrated that differences in ecological niches between grassland Fabaceae species were related more to their hierarchical trait distances than to their phylogenetic distances. We showed that grassland Fabaceae functional traits tend to converge among species with the same ecological requirements. Species with acquisitive root strategies (thin roots, shallow root systems) are competitive species adapted to non-stressful meadows, while conservative ones (coarse roots, deep root systems) are able to tolerate stressful continental climates. In contrast, acquisitive species appeared to be able to tolerate low soil-P availability, while conservative ones need high P availability. Finally we highlight that traits converge along the ecological gradient, providing the assumption that species with similar root-trait values are better able to coexist, regardless of their phylogenetic distance. PMID:25741353

  12. Hierarchical traits distances explain grassland Fabaceae species’ ecological niches distances

    Directory of Open Access Journals (Sweden)

    Florian eFort

    2015-02-01

    Full Text Available Fabaceae species play a key role in ecosystem functioning through their capacity to fix atmospheric nitrogen via their symbiosis with Rhizobium bacteria. To increase benefits of using Fabaceae in agricultural systems, it is necessary to find ways to evaluate species or genotypes having potential adaptations to sub-optimal growth conditions. We evaluated the relevance of phylogenetic distance, absolute trait distance and hierarchical trait distance for comparing the adaptation of 13 grassland Fabaceae species to different habitats, i.e. ecological niches. We measured a wide range of functional traits (root traits, leaf traits and whole plant traits in these species. Species phylogenetic and ecological distances were assessed from a species-level phylogenetic tree and species’ ecological indicator values, respectively. We demonstrated that differences in ecological niches between grassland Fabaceae species were related more to their hierarchical trait distances than to their phylogenetic distances. We showed that grassland Fabaceae functional traits tend to converge among species with the same ecological requirements. Species with acquisitive root strategies (thin roots, shallow root systems are competitive species adapted to non-stressful meadows, while conservative ones (coarse roots, deep root systems are able to tolerate stressful continental climates. In contrast, acquisitive species appeared to be able to tolerate low soil-P availability, while conservative ones need high P availability. Finally we highlight that traits converge along the ecological gradient, providing the assumption that species with similar root-trait values are better able to coexist, regardless of their phylogenetic distance.

  13. Method of measuring distance between fuel element

    International Nuclear Information System (INIS)

    Urata, Megumu.

    1991-01-01

    The distance between fuel elements contained in a pool is measured in a contactless manner even for a narrow distance less than 1 mm. That is, the equipment for measuring the distance between spent fuel elements of a spent fuel assembly in a nuclear reactor comprises a optical fiber scope, a lens, an industrial TV camera and a monitor TV. The top end of the optical fiber scope is inserted between fuel elements to be measured. The state thereof is displayed on the TV screen to measure the distance between the fuel elements. The measured results are compared with a previously formed calibration curve to determine the value between the fuel elements. Then, the distance between the fuel elements can be determined in the pool of a power plant without dismantling the fuel assembly, to investigate the state of the bending and estimate the fuel working life. (I.S.)

  14. Real-time processing for full-range Fourier-domain optical-coherence tomography with zero-filling interpolation using multiple graphic processing units.

    Science.gov (United States)

    Watanabe, Yuuki; Maeno, Seiya; Aoshima, Kenji; Hasegawa, Haruyuki; Koseki, Hitoshi

    2010-09-01

    The real-time display of full-range, 2048?axial pixelx1024?lateral pixel, Fourier-domain optical-coherence tomography (FD-OCT) images is demonstrated. The required speed was achieved by using dual graphic processing units (GPUs) with many stream processors to realize highly parallel processing. We used a zero-filling technique, including a forward Fourier transform, a zero padding to increase the axial data-array size to 8192, an inverse-Fourier transform back to the spectral domain, a linear interpolation from wavelength to wavenumber, a lateral Hilbert transform to obtain the complex spectrum, a Fourier transform to obtain the axial profiles, and a log scaling. The data-transfer time of the frame grabber was 15.73?ms, and the processing time, which includes the data transfer between the GPU memory and the host computer, was 14.75?ms, for a total time shorter than the 36.70?ms frame-interval time using a line-scan CCD camera operated at 27.9?kHz. That is, our OCT system achieved a processed-image display rate of 27.23 frames/s.

  15. Towards direct realisation of the SI unit of sound pressure in the audible hearing range based on optical free-field acoustic particle measurements

    Energy Technology Data Exchange (ETDEWEB)

    Koukoulas, Triantafillos, E-mail: triantafillos.koukoulas@npl.co.uk; Piper, Ben [Acoustics Group, National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom)

    2015-04-20

    Since the introduction of the International System of Units (the SI system) in 1960, weights, measures, standardised approaches, procedures, and protocols have been introduced, adapted, and extensively used. A major international effort and activity concentrate on the definition and traceability of the seven base SI units in terms of fundamental constants, and consequently those units that are derived from the base units. In airborne acoustical metrology and for the audible range of frequencies up to 20 kHz, the SI unit of sound pressure, the pascal, is realised indirectly and without any knowledge or measurement of the sound field. Though the principle of reciprocity was originally formulated by Lord Rayleigh nearly two centuries ago, it was devised in the 1940s and eventually became a calibration standard in the 1960s; however, it can only accommodate a limited number of acoustic sensors of specific types and dimensions. International standards determine the device sensitivity either through coupler or through free-field reciprocity but rely on the continuous availability of specific acoustical artefacts. Here, we show an optical method based on gated photon correlation spectroscopy that can measure sound pressures directly and absolutely in fully anechoic conditions, remotely, and without disturbing the propagating sound field. It neither relies on the availability or performance of any measurement artefact nor makes any assumptions of the device geometry and sound field characteristics. Most importantly, the required units of sound pressure and microphone sensitivity may now be experimentally realised, thus providing direct traceability to SI base units.

  16. VCSEL-based sensors for distance and velocity

    Science.gov (United States)

    Moench, Holger; Carpaij, Mark; Gerlach, Philipp; Gronenborn, Stephan; Gudde, Ralph; Hellmig, Jochen; Kolb, Johanna; van der Lee, Alexander

    2016-03-01

    VCSEL based sensors can measure distance and velocity in three dimensional space and are already produced in high quantities for professional and consumer applications. Several physical principles are used: VCSELs are applied as infrared illumination for surveillance cameras. High power arrays combined with imaging optics provide a uniform illumination of scenes up to a distance of several hundred meters. Time-of-flight methods use a pulsed VCSEL as light source, either with strong single pulses at low duty cycle or with pulse trains. Because of the sensitivity to background light and the strong decrease of the signal with distance several Watts of laser power are needed at a distance of up to 100m. VCSEL arrays enable power scaling and can provide very short pulses at higher power density. Applications range from extended functions in a smartphone over industrial sensors up to automotive LIDAR for driver assistance and autonomous driving. Self-mixing interference works with coherent laser photons scattered back into the cavity. It is therefore insensitive to environmental light. The method is used to measure target velocity and distance with very high accuracy at distances up to one meter. Single-mode VCSELs with integrated photodiode and grating stabilized polarization enable very compact and cost effective products. Besides the well know application as computer input device new applications with even higher accuracy or for speed over ground measurement in automobiles and up to 250km/h are investigated. All measurement methods exploit the known VCSEL properties like robustness, stability over temperature and the potential for packages with integrated optics and electronics. This makes VCSEL sensors ideally suited for new mass applications in consumer and automotive markets.

  17. Fault location in optical networks

    Science.gov (United States)

    Stevens, Rick C [Apple Valley, MN; Kryzak, Charles J [Mendota Heights, MN; Keeler, Gordon A [Albuquerque, NM; Serkland, Darwin K [Albuquerque, NM; Geib, Kent M [Tijeras, NM; Kornrumpf, William P [Schenectady, NY

    2008-07-01

    One apparatus embodiment includes an optical emitter and a photodetector. At least a portion of the optical emitter extends a radial distance from a center point. The photodetector provided around at least a portion of the optical emitter and positioned outside the radial distance of the portion of the optical emitter.

  18. Design of 3D eye-safe middle range vibrometer

    International Nuclear Information System (INIS)

    Polulyakh, Valeriy; Poutivski, Iouri

    2014-01-01

    Laser Doppler Vibrometer and Range Meter (3D-MRV) is designed for middle range distances [1–100 meters]. 3D-MRV combines more than one laser in one device for a simultaneous real time measuring the distance and movement of the targets. The first laser has a short pulse (t∼30psec) and low energy (E∼200nJ) for distance measurement and the second one is a CW (continuous wave) single frequency laser for the velocity measurement with output power (P∼30mW). Both lasers perform on the eye-safe wavelength 1.5 μm. 3D-MRV uses the same mono-static optical transmitting and receiving channel for both lasers including an output telescope and a scanning angular system. 3D-MRV has an optical polarization switch to combine linear polarized laser beams from two lasers into one optical channel. The laser beams from both lasers by turns illuminate the target and the scattered laser radiation is collected by the telescope on a photo detector. The electrical signal from photo detector is used for measuring the distance to the target and its movement. For distance measurement the time of flight method is employed. For targets movement the optical heterodyne method is employed. The received CW laser radiation is mixed on a photo detector with the frequency-shifted laser radiation that is taken from CW laser and passed through an acousto-optic cell. The electrical signal from a photo detector on the difference frequency and phase has information about movement of the scattered targets. 3D-MVR may be used for the real time picturing of vibration of the extensive targets like bridges or aircrafts

  19. Design of 3D eye-safe middle range vibrometer

    Energy Technology Data Exchange (ETDEWEB)

    Polulyakh, Valeriy [Advanced Data Security, 1933 O' Toole Way, San Jose, CA 95131 (United States); Poutivski, Iouri [Terimber Corporation, 2456 Homewood Drive, San Jose, CA 95128, USA and Facebook Inc, 1601 Willow Road, Menlo Park, CA 94025 (United States)

    2014-05-27

    Laser Doppler Vibrometer and Range Meter (3D-MRV) is designed for middle range distances [1–100 meters]. 3D-MRV combines more than one laser in one device for a simultaneous real time measuring the distance and movement of the targets. The first laser has a short pulse (t∼30psec) and low energy (E∼200nJ) for distance measurement and the second one is a CW (continuous wave) single frequency laser for the velocity measurement with output power (P∼30mW). Both lasers perform on the eye-safe wavelength 1.5 μm. 3D-MRV uses the same mono-static optical transmitting and receiving channel for both lasers including an output telescope and a scanning angular system. 3D-MRV has an optical polarization switch to combine linear polarized laser beams from two lasers into one optical channel. The laser beams from both lasers by turns illuminate the target and the scattered laser radiation is collected by the telescope on a photo detector. The electrical signal from photo detector is used for measuring the distance to the target and its movement. For distance measurement the time of flight method is employed. For targets movement the optical heterodyne method is employed. The received CW laser radiation is mixed on a photo detector with the frequency-shifted laser radiation that is taken from CW laser and passed through an acousto-optic cell. The electrical signal from a photo detector on the difference frequency and phase has information about movement of the scattered targets. 3D-MVR may be used for the real time picturing of vibration of the extensive targets like bridges or aircrafts.

  20. Training for Distance Teaching through Distance Learning.

    Science.gov (United States)

    Cadorath, Jill; Harris, Simon; Encinas, Fatima

    2002-01-01

    Describes a mixed-mode bachelor degree course in English language teaching at the Universidad Autonoma de Puebla (Mexico) that was designed to help practicing teachers write appropriate distance education materials by giving them the experience of being distance students. Includes a course outline and results of a course evaluation. (Author/LRW)

  1. The Distance Standard Deviation

    OpenAIRE

    Edelmann, Dominic; Richards, Donald; Vogel, Daniel

    2017-01-01

    The distance standard deviation, which arises in distance correlation analysis of multivariate data, is studied as a measure of spread. New representations for the distance standard deviation are obtained in terms of Gini's mean difference and in terms of the moments of spacings of order statistics. Inequalities for the distance variance are derived, proving that the distance standard deviation is bounded above by the classical standard deviation and by Gini's mean difference. Further, it is ...

  2. method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

    NARCIS (Netherlands)

    Boer, JF De; Tearney, G. J.; Bouma, BE

    2008-01-01

    Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and loW coher ence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split

  3. Effects of the gamma-ray irradiation on the optical absorption of pure silica core single-mode fibres in the visible and NIR range

    International Nuclear Information System (INIS)

    Calderon, A.; Calvo, E.; Figueroa, C.F.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A.L.; Arce, P.; Barcala, J.M.; Ferrando, A.; Josa, M.I.; Luque, J.M.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.

    2005-01-01

    Optical absorption induced by photon radiation was evaluated for several commercial pure silica core, single mode, optical fibres. The study was performed for three different wavelengths: 630, 670 and 785 nm. We have identified a fibre whose induced transmission loss stays below 1 dB/m after 300 kGy gamma-ray irradiation

  4. Fiber-Optic Pyrometer with Optically Powered Switch for Temperature Measurements.

    Science.gov (United States)

    Vázquez, Carmen; Pérez-Prieto, Sandra; López-Cardona, Juan D; Tapetado, Alberto; Blanco, Enrique; Moreno-López, Jorge; Montero, David S; Lallana, Pedro C

    2018-02-06

    We report the experimental results on a new infrared fiber-optic pyrometer for very localized and high-speed temperature measurements ranging from 170 to 530 °C using low-noise photodetectors and high-gain transimpedance amplifiers with a single gain mode in the whole temperature range. We also report a shutter based on an optical fiber switch which is optically powered to provide a reference signal in an optical fiber pyrometer measuring from 200 to 550 °C. The tests show the potential of remotely powering via optical means a 300 mW power-hungry optical switch at a distance of 100 m, avoiding any electromagnetic interference close to the measuring point.

  5. Fiber-Optic Pyrometer with Optically Powered Switch for Temperature Measurements

    Directory of Open Access Journals (Sweden)

    Carmen Vázquez

    2018-02-01

    Full Text Available We report the experimental results on a new infrared fiber-optic pyrometer for very localized and high-speed temperature measurements ranging from 170 to 530 °C using low-noise photodetectors and high-gain transimpedance amplifiers with a single gain mode in the whole temperature range. We also report a shutter based on an optical fiber switch which is optically powered to provide a reference signal in an optical fiber pyrometer measuring from 200 to 550 °C. The tests show the potential of remotely powering via optical means a 300 mW power-hungry optical switch at a distance of 100 m, avoiding any electromagnetic interference close to the measuring point.

  6. Encyclopedia of distances

    CERN Document Server

    Deza, Michel Marie

    2014-01-01

    This updated and revised third edition of the leading reference volume on distance metrics includes new items from very active research areas in the use of distances and metrics such as geometry, graph theory, probability theory and analysis. Among the new topics included are, for example, polyhedral metric space, nearness matrix problems, distances between belief assignments, distance-related animal settings, diamond-cutting distances, natural units of length, Heidegger’s de-severance distance, and brain distances. The publication of this volume coincides with intensifying research efforts into metric spaces and especially distance design for applications. Accurate metrics have become a crucial goal in computational biology, image analysis, speech recognition and information retrieval. Leaving aside the practical questions that arise during the selection of a ‘good’ distance function, this work focuses on providing the research community with an invaluable comprehensive listing of the main available di...

  7. Dosimetry in the multi kilo-Gray range using optically-stimulated luminescence (OSL) and thermally-transferred OSL from quartz

    International Nuclear Information System (INIS)

    Burbidge, C.I.; Cabo Verde, S.I.; Fernandes, A.C.; Prudencio, M.I.; Botelho, M.L.; Dias, M.I.; Cardoso, G.

    2011-01-01

    This study explores the potential for using photon-stimulated luminescence of quartz grains to retrospectively evaluate multi-kGy gamma radiation doses. Subsamples from two ceramic tiles were given 60 Co gamma doses of 1, 3, 5, 15 and 30 kGy (nominal), accompanied by PMMA dosimeters and quartz grains from a geological sample known to exhibit thermally-transferred optically-stimulated luminescence (TTOSL). Following gamma irradiation, quartz grains were prepared from each subsample. OSL and TTOSL signals were measured for different preheat temperatures, and following re-irradiation with beta doses designed to equal the nominal gamma doses. OSL responses to 10 Gy beta test doses were measured following each cycle of high dose irradiation. Gamma doses were predicted from the beta responses, to evaluate the effectiveness of retrospective dose evaluation for different signal integrals, preheat combinations, and dose intervals. The use of linear modulation limited maximum OSL signal levels to 1.5 x 10 6 cps without reducing detector sensitivity, for the measurement of smaller TTOSL signals. The dosimetric behaviour of the three samples differed significantly: the best results were obtained from the pre-prepared geological quartz. OSL signals evident at short stimulation times, which are conventionally used for dosimetry and dating, did not in general appear appropriate for dosimetry in the range of doses examined. They exhibited dose response characteristics that were highly preheat dependant and variable in form between samples, which contained rapidly saturating and/or non-monotonic components. Higher preheats, up to 300 o C, preferentially removed OSL and TTOSL signals evident at longer stimulation times: those that remained yielded growth in signal with dose to approximately 10 kGy, but the accuracy of retrospective dose determinations was variable. TTOSL signals evident at short stimulation times increased proportionally with dose when 300 o C preheats were used, up

  8. Thermochemical cycles for the heat and cold long-range transport. Final report of the PRI 9.2 Cold transport. Annual report of the PR 2-8; Cycles thermochimiques pour le transport de chaleur et de froid a longue distance. Rapport final du PRI 9.2. Transport de froid. Rapport annuel du PR 2-8

    Energy Technology Data Exchange (ETDEWEB)

    Luo, L.; Tondeur, D. [Laboratoire des Sciences du Genie Chimique (LSGC), 54 - Nancy (France); Mazet, N.; Neveu, P.; Stitou, D.; Spinner, B. [Institut de Science et de Genie des Materiaux et Procedes (IMP), 66 - Perpignan (France)

    2004-07-01

    This PRI deals with the use of thermochemical processes, based on solid-gas reversible transformation, to transfer heat of cold at long-range distance (> 10 km), in order to enhance the energy efficiency. Four main aspects have been studied to confirm the process feasibility: the process identification and the operating conditions, the selection of compatible reagents, the design of an auto-thermal reactor and the gas transport impact on the global performances. (A.L.B.)

  9. Multi-image acquisition-based distance sensor using agile laser spot beam.

    Science.gov (United States)

    Riza, Nabeel A; Amin, M Junaid

    2014-09-01

    We present a novel laser-based distance measurement technique that uses multiple-image-based spatial processing to enable distance measurements. Compared with the first-generation distance sensor using spatial processing, the modified sensor is no longer hindered by the classic Rayleigh axial resolution limit for the propagating laser beam at its minimum beam waist location. The proposed high-resolution distance sensor design uses an electronically controlled variable focus lens (ECVFL) in combination with an optical imaging device, such as a charged-coupled device (CCD), to produce and capture different laser spot size images on a target with these beam spot sizes different from the minimal spot size possible at this target distance. By exploiting the unique relationship of the target located spot sizes with the varying ECVFL focal length for each target distance, the proposed distance sensor can compute the target distance with a distance measurement resolution better than the axial resolution via the Rayleigh resolution criterion. Using a 30 mW 633 nm He-Ne laser coupled with an electromagnetically actuated liquid ECVFL, along with a 20 cm focal length bias lens, and using five spot images captured per target position by a CCD-based Nikon camera, a proof-of-concept proposed distance sensor is successfully implemented in the laboratory over target ranges from 10 to 100 cm with a demonstrated sub-cm axial resolution, which is better than the axial Rayleigh resolution limit at these target distances. Applications for the proposed potentially cost-effective distance sensor are diverse and include industrial inspection and measurement and 3D object shape mapping and imaging.

  10. Brownian distance covariance

    OpenAIRE

    Székely, Gábor J.; Rizzo, Maria L.

    2010-01-01

    Distance correlation is a new class of multivariate dependence coefficients applicable to random vectors of arbitrary and not necessarily equal dimension. Distance covariance and distance correlation are analogous to product-moment covariance and correlation, but generalize and extend these classical bivariate measures of dependence. Distance correlation characterizes independence: it is zero if and only if the random vectors are independent. The notion of covariance with...

  11. Tailored long range forces on polarizable particles by collective scattering of broadband radiation

    International Nuclear Information System (INIS)

    Holzmann, D; Ritsch, H

    2016-01-01

    Collective coherent light scattering by polarizable particles creates surprisingly strong, long range inter-particle forces originating from interference of the light scattered by different particles. While for monochromatic laser beams this interaction decays with the inverse distance, we show here that in general the effective interaction range and geometry can be controlled by the illumination bandwidth and geometry. As generic example we study the modifications inter-particle forces within a 1D chain of atoms trapped in the field of a confined optical nanofiber mode. For two particles we find short range attraction as well as optical binding at multiple distances. The range of stable distances shrinks with increasing light bandwidth and for a very large bandwidth field as e.g. blackbody radiation. We find a strongly attractive potential up to a critical distance beyond which the force gets repulsive. Including multiple scattering can even lead to the appearance of a stable configuration at a large distance. Such broadband scattering forces should be observable contributions in ultra-cold atom interferometers or atomic clocks setups. They could be studied in detail in 1D geometries with ultra-cold atoms trapped along or within an optical nanofiber. Broadband radiation force interactions might also contribute in astrophysical scenarios as illuminated cold dust clouds. (paper)

  12. TECHNIQUE OF ESTIMATION OF ERROR IN THE REFERENCE VALUE OF THE DOSE DURING THE LINEAR ACCELERATOR RADIATION OUTPUT CALIBRATION PROCEDURE. Part 2. Dependence on the characteristics of collimator, optical sourse-distance indicator, treatment field, lasers and treatment couch

    Directory of Open Access Journals (Sweden)

    Y. V. Tsitovich

    2016-01-01

    Full Text Available To ensure the safety of radiation oncology patients needed to provide consistent functional characteristics of the medical linear accelerators, which affect the accuracy of dose delivery. To this end, their quality control procedures, which include the calibration of radiation output of the linac, the error in determining the dose reference value during which must not exceed 2 %, is provided. The aim is to develop a methodology for determining the error (difference between a measured value of quantity and its true value in determining this value, depending on the characteristics of the collimator, the source to surface distance pointer, lasers, radiation field and treatment table. To achieve the objectives have been carried out dosimetric measurements of Trilogy S/N 3567 linac dose distributions, on the basis of which dose errors depending on the accuracy setting the zero position of the collimator, the deviation of the collimator rotation isocenter, the sourcesurface distance pointer accuracy, field size accuracy, the accuracy of lasers and treatment table positioning were obtained. It was found that the greatest impact on the value of the error has the error in the optical SSD indication and the error in the lasers position in the plane perpendicular to the plane of incidence of the radiation beam (up to 3.64 % for the energy of 6 MV. Dose errors caused by error in the field size were different for two photon energies, and reached 2.54 % for 6 MeV and 1.33% for 18 MeV. Errors caused by the rest of the characteristic do not exceed 1 %. Thus, it is possible to express the results of periodic quality control of these devices integrated in linac in terms of dose and use them to conduct a comprehensive assessment of the possibility of clinical use of a linear accelerator for oncology patients irradiation on the basis of the calibration of radiation output in case of development of techniques that allow to analyze the influence dosimetric

  13. Distance-regular graphs

    NARCIS (Netherlands)

    van Dam, Edwin R.; Koolen, Jack H.; Tanaka, Hajime

    2016-01-01

    This is a survey of distance-regular graphs. We present an introduction to distance-regular graphs for the reader who is unfamiliar with the subject, and then give an overview of some developments in the area of distance-regular graphs since the monograph 'BCN'[Brouwer, A.E., Cohen, A.M., Neumaier,

  14. A Fourier transform spectrometer without a beam splitter for the vacuum ultraviolet range: From the optical design to the first UV spectrum.

    Science.gov (United States)

    de Oliveira, N; Joyeux, D; Phalippou, D; Rodier, J C; Polack, F; Vervloet, M; Nahon, L

    2009-04-01

    We describe a Fourier transform (FT) spectrometer designed to operate down to 60 nm (20 eV) on a synchrotron radiation beamline for high resolution absorption spectrometry. As far as we know, such an instrument is not available below 140 nm mainly because manufacturing accurate and efficient beam splitters remains a major problem at these wavelengths, especially if a wide bandwidth operation is desired. In order to overcome this difficulty, we developed an interferometer based on wave front division instead of amplitude division. It relies on a modified Fresnel bimirror configuration that requires only flat mirrors. The instrument provides path difference scanning through the translation of one reflector. During the scanning, the moving reflector is controlled by an optical system that keeps its direction constant within a tolerable value and provides an accurate interferometric measurement of the path difference variation. Therefore, a regular interferogram sampling is obtained, producing a nominal spectral impulse response and an accurate spectral calibration. The first results presented in this paper show a measured spectral resolution of delta(sigma)=0.33 cm-1 (interval between spectral samples). This was obtained with a sampling interval of 29 nm (path difference) and 512 K samples from a one-sided interferogram using a cosine FT. Such a sampling interval should allow the recording of large bandwidth spectra down to lambda=58 nm with an ultimate resolving power of 500,000 at this wavelength. In order to check the instrument performances, we first recorded an interferogram from a He-Ne stabilized laser. This provided the actual spectral impulse function, which was found to be fully satisfactory. The determination of the impulse response distortion and of the noise on the vacuum ultraviolet (VUV) spectral range provided accurate information in the sampling error profile over a typical scan. Finally, the instrument has been moved to the SU5 undulator

  15. Characterization of atmospheric aerosols in Ile-de-France: Local contribution and Long range transport; Caracteisation des aeosols atmospheiques en Ile-de-France: contribution locale et transport a longues distances

    Energy Technology Data Exchange (ETDEWEB)

    Cuesta, J.E

    2006-06-15

    Atmospheric aerosols interact directly in a great number of processes related to climate change and public health, modifying the energy budget and partly determining the quality of the air we breathe. In my PhD, I chose to study the perturbation, if not the aggravation, of the living conditions in Ile-de-France associated to aerosol transport episodes in the free troposphere. This situation is rather frequent and still badly known. To achieve my study, I developed the observation platform 'TReSS' Transportable Remote Sensing Station, whose instruments were developed at the Laboratoire de Meteorology Dynamique by the LiMAG team. 'TReSS' consists of a new high-performance 'Mini-Lidar' and of two standard radiometers: a sun photometer and a thermal infrared radiometer. The principle of my experimental approach is the synergy of the vertical Lidar profiles and the particle size distributions over the column, obtained by the 'Almucantar' inversion of sun photometer data. The new 'Lidar and Almucantar' method characterizes the vertical distribution by layer and the optical micro-physical properties of the local and transported aerosols. Firstly, I undertook the characterization of the Paris aerosol, mainly of anthropogenic origin. Their radiative properties were analyzed in the daily and yearly scales. Then, I conducted a statistical multi-year study of transport episodes and a two-week study case, representative of a succession of desert dust intrusion in Ile-de-France. My PhD work concludes by a study on the impact of biomass burning aerosols during the heat wave on August 2003. I study the impact of the transported aerosols into the local radiative budget and the possible consequences on the diurnal cycle of the atmospheric boundary layer. (author)

  16. Determination of the refractive index of insoluble organic extracts from atmospheric aerosol over the visible wavelength range using optical tweezers

    Directory of Open Access Journals (Sweden)

    R. H. Shepherd

    2018-04-01

    Full Text Available Optical trapping combined with Mie spectroscopy is a new technique used to record the refractive index of insoluble organic material extracted from atmospheric aerosol samples over a wide wavelength range. The refractive index of the insoluble organic extracts was shown to follow a Cauchy equation between 460 and 700 nm for organic aerosol extracts collected from urban (London and remote (Antarctica locations. Cauchy coefficients for the remote sample were for the Austral summer and gave the Cauchy coefficients of A  =  1.467 and B  =  1000 nm2 with a real refractive index of 1.489 at a wavelength of 589 nm. Cauchy coefficients for the urban samples varied with season, with extracts collected during summer having Cauchy coefficients of A  =  1.465  ±  0.005 and B  =  4625  ±  1200 nm2 with a representative real refractive index of 1.478 at a wavelength of 589 nm, whilst samples extracted during autumn had larger Cauchy coefficients of A  =  1.505 and B  =  600 nm2 with a representative real refractive index of 1.522 at a wavelength of 589 nm. The refractive index of absorbing aerosol was also recorded. The absorption Ångström exponent was determined for woodsmoke and humic acid aerosol extract. Typical values of the Cauchy coefficient for the woodsmoke aerosol extract were A  =  1.541  ±  0.03 and B  =  14 800  ±  2900 nm2, resulting in a real refractive index of 1.584  ±  0.007 at a wavelength of 589 nm and an absorption Ångström exponent of 8.0. The measured values of refractive index compare well with previous monochromatic or very small wavelength range measurements of refractive index. In general, the real component of the refractive index increases from remote to urban to woodsmoke. A one-dimensional radiative-transfer calculation of the top-of-the-atmosphere albedo was applied to model an atmosphere

  17. Haptic Discrimination of Distance

    Science.gov (United States)

    van Beek, Femke E.; Bergmann Tiest, Wouter M.; Kappers, Astrid M. L.

    2014-01-01

    While quite some research has focussed on the accuracy of haptic perception of distance, information on the precision of haptic perception of distance is still scarce, particularly regarding distances perceived by making arm movements. In this study, eight conditions were measured to answer four main questions, which are: what is the influence of reference distance, movement axis, perceptual mode (active or passive) and stimulus type on the precision of this kind of distance perception? A discrimination experiment was performed with twelve participants. The participants were presented with two distances, using either a haptic device or a real stimulus. Participants compared the distances by moving their hand from a start to an end position. They were then asked to judge which of the distances was the longer, from which the discrimination threshold was determined for each participant and condition. The precision was influenced by reference distance. No effect of movement axis was found. The precision was higher for active than for passive movements and it was a bit lower for real stimuli than for rendered stimuli, but it was not affected by adding cutaneous information. Overall, the Weber fraction for the active perception of a distance of 25 or 35 cm was about 11% for all cardinal axes. The recorded position data suggest that participants, in order to be able to judge which distance was the longer, tried to produce similar speed profiles in both movements. This knowledge could be useful in the design of haptic devices. PMID:25116638

  18. Haptic discrimination of distance.

    Directory of Open Access Journals (Sweden)

    Femke E van Beek

    Full Text Available While quite some research has focussed on the accuracy of haptic perception of distance, information on the precision of haptic perception of distance is still scarce, particularly regarding distances perceived by making arm movements. In this study, eight conditions were measured to answer four main questions, which are: what is the influence of reference distance, movement axis, perceptual mode (active or passive and stimulus type on the precision of this kind of distance perception? A discrimination experiment was performed with twelve participants. The participants were presented with two distances, using either a haptic device or a real stimulus. Participants compared the distances by moving their hand from a start to an end position. They were then asked to judge which of the distances was the longer, from which the discrimination threshold was determined for each participant and condition. The precision was influenced by reference distance. No effect of movement axis was found. The precision was higher for active than for passive movements and it was a bit lower for real stimuli than for rendered stimuli, but it was not affected by adding cutaneous information. Overall, the Weber fraction for the active perception of a distance of 25 or 35 cm was about 11% for all cardinal axes. The recorded position data suggest that participants, in order to be able to judge which distance was the longer, tried to produce similar speed profiles in both movements. This knowledge could be useful in the design of haptic devices.

  19. Interface Simulation Distances

    Directory of Open Access Journals (Sweden)

    Pavol Černý

    2012-10-01

    Full Text Available The classical (boolean notion of refinement for behavioral interfaces of system components is the alternating refinement preorder. In this paper, we define a distance for interfaces, called interface simulation distance. It makes the alternating refinement preorder quantitative by, intuitively, tolerating errors (while counting them in the alternating simulation game. We show that the interface simulation distance satisfies the triangle inequality, that the distance between two interfaces does not increase under parallel composition with a third interface, and that the distance between two interfaces can be bounded from above and below by distances between abstractions of the two interfaces. We illustrate the framework, and the properties of the distances under composition of interfaces, with two case studies.

  20. Optical trigger: a Cherenkov effect discriminator for high energy physics. Realisation and characterisation of thin films whose refractive index allow discrimination over a wide spectral range

    International Nuclear Information System (INIS)

    Delbart, A.

    1996-01-01

    The first part of this thesis sets the physical principles, and properties of actual Optical Triggers. For each of them, the cupel is sapphire made, and the external medium is liquid because of refractive index. The theory of Cherenkov emitted light cone explain how sapphire birefringence affects discrimination conditions.The second parts of the thesis (the main one) is focussed on study and realization of thin films for Optical Trigger. A layer characterization method has been developed by spectrophotometry, based on Perkin-Elmer laboratory device. Computerized simulation helped us to determine characteristics and limits of the studied device. (D.L.)

  1. IM/DD vs. 4-PAM Using a 1550-nm VCSEL over Short-Range SMF/MMF Links for Optical Interconnects

    DEFF Research Database (Denmark)

    Karinou, Fotini; Rodes Lopez, Roberto; Prince, Kamau

    2013-01-01

    We experimentally compare the performance of 10.9-Gb/s IM/DD and 5-GBd 4-PAM modulation formats over 5-km SMF and 1-km MMF links, employing a commercially-available 1550-nm VCSEL as an enabling technology for use in optical interconnects.......We experimentally compare the performance of 10.9-Gb/s IM/DD and 5-GBd 4-PAM modulation formats over 5-km SMF and 1-km MMF links, employing a commercially-available 1550-nm VCSEL as an enabling technology for use in optical interconnects....

  2. Strong doping of the n-optical confinement layer for increasing output power of high- power pulsed laser diodes in the eye safe wavelength range

    Science.gov (United States)

    Ryvkin, Boris S.; Avrutin, Eugene A.; Kostamovaara, Juha T.

    2017-12-01

    An analytical model for internal optical losses at high power in a 1.5 μm laser diode with strong n-doping in the n-side of the optical confinement layer is created. The model includes intervalence band absorption by holes supplied by both current flow and two-photon absorption (TPA), as well as the direct TPA effect. The resulting losses are compared with those in an identical structure with a weakly doped waveguide, and shown to be substantially lower, resulting in a significant improvement in the output power and efficiency in the structure with a strongly doped waveguide.

  3. Inventories of atmospheric pollutants emissions in France under the convention framework on the long range transboundary air pollution; Inventaire des emissions de polluants atmospheriques en France au titre de la convention sur la pollution atmospherique tranfrontaliere a longue distance

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-12-01

    The present report supplies emission data, for France, concerning all the substances covered by the different protocols adopted under the Convention on Long Range Transboundary Air Pollution (LRTAP), on behalf of the United Nations Economic Commission for Europe (UNECE). The substances covered are sulphur dioxide (SO{sub 2}), nitrogen oxides (NO{sub x}), non methane volatile organic compounds (NMVOCs), ammonia (NH{sub 3}), carbon monoxide (CO), total suspended particles (TSP), fine particles (PM{sub 10} and PM{sub 2,5}), heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Zn) and persistent organic pollutants (POPs). Data are reported according to new specifications adopted in Autumn 2001 regarding substances and source coverage. Parties to the convention have to report annually emissions of these substances. (author)

  4. Cepheids Geometrical Distances Using Space Interferometry

    Science.gov (United States)

    Marengo, M.; Karovska, M.; Sasselov, D. D.; Sanchez, M.

    2004-05-01

    A space based interferometer with a sub-milliarcsecond resolution in the UV-optical will provide a new avenue for the calibration of primary distance indicators with unprecedented accuracy, by allowing very accurate and stable measurements of Cepheids pulsation amplitudes at wavelengths not accessible from the ground. Sasselov & Karovska (1994) have shown that interferometers allow very accurate measurements of Cepheids distances by using a ``geometric'' variant of the Baade-Wesselink method. This method has been succesfully applied to derive distances and radii of nearby Cepheids using ground-based near-IR and optical interferometers, within a 15% accuracy level. Our study shows that the main source of error in these measurements is due to the perturbing effects of the Earth atmosphere, which is the limiting factor in the interferometer stability. A space interferometer will not suffer from this intrinsic limitations, and can potentially lead to improve astronomical distance measurements by an order of magnitude in precision. We discuss here the technical requirements that a space based facility will need to carry out this project, allowing distance measurements within a few percent accuracy level. We will finally discuss how a sub-milliarcsecond resolution will allow the direct distance determination for hundreds of galactic sources, and provide a substantial improvement in the zero-point of the Cepheid distance scale.

  5. Soliton microcomb range measurement

    Science.gov (United States)

    Suh, Myoung-Gyun; Vahala, Kerry J.

    2018-02-01

    Laser-based range measurement systems are important in many application areas, including autonomous vehicles, robotics, manufacturing, formation flying of satellites, and basic science. Coherent laser ranging systems using dual-frequency combs provide an unprecedented combination of long range, high precision, and fast update rate. We report dual-comb distance measurement using chip-based soliton microcombs. A single pump laser was used to generate dual-frequency combs within a single microresonator as counterpropagating solitons. We demonstrated time-of-flight measurement with 200-nanometer precision at an averaging time of 500 milliseconds within a range ambiguity of 16 millimeters. Measurements at distances up to 25 meters with much lower precision were also performed. Our chip-based source is an important step toward miniature dual-comb laser ranging systems that are suitable for photonic integration.

  6. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Czech Academy of Sciences Publication Activity Database

    Soltani, A.; Stolz, A.; Charrier, J.; Mattalah, M.; Gerbedoen, J.-C.; Barkad, H.A.; Mortet, Vincent; Rousseau, M.; Bourzgui, N.; BenMoussa, A.; De Jaeger, J.-C.

    2014-01-01

    Roč. 115, č. 16 (2014), "163515-1"-"163515-6" ISSN 0021-8979 Institutional support: RVO:68378271 Keywords : III-V semiconductors * AlN films * surface scattering * refractive index * optical properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2014

  7. Chlorophyll-a concentration estimation with three bio-optical algorithms: correction for the low concentration range for the Yiam Reservoir, Korea

    Science.gov (United States)

    Bio-optical algorithms have been applied to monitor water quality in surface water systems. Empirical algorithms, such as Ritchie (2008), Gons (2008), and Gilerson (2010), have been applied to estimate the chlorophyll-a (chl-a) concentrations. However, the performance of each algorithm severely degr...

  8. Short-range fundamental forces

    International Nuclear Information System (INIS)

    Antoniadis, I.; Baessler, S.; Buchner, M.; Fedorov, V.V.; Hoedl, S.; Nesvizhevsky, V.V.; Pignol, G.; Protasov, K.V.; Lambrecht, A.; Reynaud, S.; Sobolev, Y.

    2010-01-01

    We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments

  9. Performance of an optical equalizer in a 10 G wavelength converting optical access network.

    Science.gov (United States)

    Mendinueta, José Manuel D; Cao, Bowen; Thomsen, Benn C; Mitchell, John E

    2011-12-12

    A centralized optical processing unit (COPU) that functions both as a wavelength converter (WC) and optical burst equaliser in a 10 Gb/s wavelength-converting optical access network is proposed and experimentally characterized. This COPU is designed to consolidate drifting wavelengths generated with an uncooled laser in the upstream direction into a stable wavelength channel for WDM backhaul transmission and to equalize the optical loud/soft burst power in order to relax the burst-mode receiver dynamic range requirement. The COPU consists of an optical power equaliser composed of two cascaded SOAs followed by a WC. Using an optical packet generator and a DC-coupled PIN-based digital burst-mode receiver, the COPU is characterized in terms of payload-BER for back-to-back and backhaul transmission distances of 22, 40, and 62 km. We show that there is a compromise between the receiver sensitivity and overload points that can be optimized tuning the WC operating point for a particular backhaul fiber transmission distance. Using the optimized settings, sensitivities of -30.94, -30.17, and -27.26 dBm with overloads of -9.3, -5, and >-5 dBm were demonstrated for backhaul transmission distances of 22, 40 and 62 km, respectively. © 2011 Optical Society of America

  10. Traversing psychological distance.

    Science.gov (United States)

    Liberman, Nira; Trope, Yaacov

    2014-07-01

    Traversing psychological distance involves going beyond direct experience, and includes planning, perspective taking, and contemplating counterfactuals. Consistent with this view, temporal, spatial, and social distances as well as hypotheticality are associated, affect each other, and are inferred from one another. Moreover, traversing all distances involves the use of abstraction, which we define as forming a belief about the substitutability for a specific purpose of subjectively distinct objects. Indeed, across many instances of both abstraction and psychological distancing, more abstract constructs are used for more distal objects. Here, we describe the implications of this relation for prediction, choice, communication, negotiation, and self-control. We ask whether traversing distance is a general mental ability and whether distance should replace expectancy in expected-utility theories. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Numerical distance protection

    CERN Document Server

    Ziegler, Gerhard

    2011-01-01

    Distance protection provides the basis for network protection in transmission systems and meshed distribution systems. This book covers the fundamentals of distance protection and the special features of numerical technology. The emphasis is placed on the application of numerical distance relays in distribution and transmission systems.This book is aimed at students and engineers who wish to familiarise themselves with the subject of power system protection, as well as the experienced user, entering the area of numerical distance protection. Furthermore it serves as a reference guide for s

  12. Donor impurity states and related terahertz range nonlinear optical response in GaN cylindrical quantum wires: Effects of external electric and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Correa, J. D. [Departamento de Ciencias Básicas, Universidad de Medellín, Medellín (Colombia); Mora-Ramos, M. E., E-mail: memora@uaem.mx [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Duque, C. A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-06-07

    We report a study on the optical absorption coefficient associated to hydrogenic impurity interstate transitions in zinc-blende GaN quantum wires of cylindrical shape taking into account the effects of externally applied static electric and magnetic fields. The electron states emerge within the effective mass approximation, via the exact diagonalization of the donor-impurity Hamiltonian with parabolic confinement and external field effects. The nonlinear optical absorption is calculated using a recently derived expression for the dielectric susceptibility, obtained via a nonperturbative solution of the density-matrix Bloch equation. Our results show that this treatment eliminates not only the intensity-dependent bleaching effect but also the change in sign of the nonlinear contribution due to the combined effect of asymmetric impurity location and the applied electric field.

  13. Nonimaging optical illumination system

    Science.gov (United States)

    Winston, Roland; Ries, Harald

    1996-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  14. Compressive laser ranging.

    Science.gov (United States)

    Babbitt, Wm Randall; Barber, Zeb W; Renner, Christoffer

    2011-12-15

    Compressive sampling has been previously proposed as a technique for sampling radar returns and determining sparse range profiles with a reduced number of measurements compared to conventional techniques. By employing modulation on both transmission and reception, compressive sensing in ranging is extended to the direct measurement of range profiles without intermediate measurement of the return waveform. This compressive ranging approach enables the use of pseudorandom binary transmit waveforms and return modulation, along with low-bandwidth optical detectors to yield high-resolution ranging information. A proof-of-concept experiment is presented. With currently available compact, off-the-shelf electronics and photonics, such as high data rate binary pattern generators and high-bandwidth digital optical modulators, compressive laser ranging can readily achieve subcentimeter resolution in a compact, lightweight package.

  15. Enhancing multi-view autostereoscopic displays by viewing distance control (VDC)

    Science.gov (United States)

    Jurk, Silvio; Duckstein, Bernd; Renault, Sylvain; Kuhlmey, Mathias; de la Barré, René; Ebner, Thomas

    2014-03-01

    Conventional multi-view displays spatially interlace various views of a 3D scene and form appropriate viewing channels. However, they only support sufficient stereo quality within a limited range around the nominal viewing distance (NVD). If this distance is maintained, two slightly divergent views are projected to the person's eyes, both covering the entire screen. With increasing deviations from the NVD the stereo image quality decreases. As a major drawback in usability, the manufacturer so far assigns this distance. We propose a software-based solution that corrects false view assignments depending on the distance of the viewer. Our novel approach enables continuous view adaptation based on the calculation of intermediate views and a column-bycolumn rendering method. The algorithm controls each individual subpixel and generates a new interleaving pattern from selected views. In addition, we use color-coded test content to verify its efficacy. This novel technology helps shifting the physically determined NVD to a user-defined distance thereby supporting stereopsis. The recent viewing positions can fall in front or behind the NVD of the original setup. Our algorithm can be applied to all multi-view autostereoscopic displays — independent of the ascent or the periodicity of the optical element. In general, the viewing distance can be corrected with a factor of more than 2.5. By creating a continuous viewing area the visualized 3D content is suitable even for persons with largely divergent intraocular distance — adults and children alike — without any deficiency in spatial perception.

  16. The Distance to Nova V959 Mon from VLA Imaging

    Science.gov (United States)

    Linford, J. D.; Ribeiro, V. A. R. M.; Chomiuk, L.; Nelson, T.; Sokoloski, J. L.; Rupen, M. P.; Mukai, K.; O'Brien, T. J.; Mioduszewski, A. J.; Weston, J.

    2015-06-01

    Determining reliable distances to classical novae is a challenging but crucial step in deriving their ejected masses and explosion energetics. Here we combine radio expansion measurements from the Karl G. Jansky Very Large Array with velocities derived from optical spectra to estimate an expansion parallax for nova V959 Mon, the first nova discovered through its γ-ray emission. We spatially resolve the nova at frequencies of 4.5-36.5 GHz in nine different imaging epochs. The first five epochs cover the expansion of the ejecta from 2012 October to 2013 January, while the final four epochs span 2014 February-May. These observations correspond to days 126 through 199 and days 615 through 703 after the first detection of the nova. The images clearly show a non-spherical ejecta geometry. Utilizing ejecta velocities derived from three-dimensional modeling of optical spectroscopy, the radio expansion implies a distance between 0.9 ± 0.2 and 2.2 ± 0.4 kpc, with a most probable distance of 1.4 ± 0.4 kpc. This distance implies a γ-ray luminosity of 0.6× {{10}35} erg s-1, which is much less than the prototype γ-ray-detected nova, V407 Cyg, possibly due to the lack of a red giant companion in the V959 Mon system. V959 Mon also has a much lower γ-ray luminosity than other classical novae detected in γ-rays to date, indicating a range of at least a factor of 10 in the γ-ray luminosities for these explosions.

  17. REPRESENTATIONS OF DISTANCE: DIFFERENCES IN UNDERSTANDING DISTANCE ACCORDING TO TRAVEL METHOD

    Directory of Open Access Journals (Sweden)

    Gunvor Riber Larsen

    2017-12-01

    Full Text Available This paper explores how Danish tourists represent distance in relation to their holiday mobility and how these representations of distance are a result of being aero-mobile as opposed to being land-mobile. Based on interviews with Danish tourists, whose holiday mobility ranges from the European continent to global destinations, the first part of this qualitative study identifies three categories of representations of distance that show how distance is being ‘translated’ by the tourists into non-geometric forms: distance as resources, distance as accessibility, and distance as knowledge. The representations of distance articulated by the Danish tourists show that distance is often not viewed in ‘just’ kilometres. Rather, it is understood in forms that express how transcending the physical distance through holiday mobility is dependent on individual social and economic contexts, and on whether the journey was undertaken by air or land. The analysis also shows that being aeromobile is the holiday transportation mode that removes the tourists the furthest away from physical distance, resulting in the distance travelled by air being represented in ways that have the least correlation, in the tourists’ minds, with physical distance measured in kilometres.

  18. Soft optics in intelligent optical networks

    Science.gov (United States)

    Shue, Chikong; Cao, Yang

    2001-10-01

    In addition to the recent advances in Hard-optics that pushes the optical transmission speed, distance, wave density and optical switching capacity, Soft-optics provides the necessary intelligence and control software that reduces operational costs, increase efficiency, and enhances revenue generating services by automating optimal optical circuit placement and restoration, and enabling value-added new services like Optical VPN. This paper describes the advances in 1) Overall Hard-optics and Soft-optics 2) Layered hierarchy of Soft-optics 3) Component of Soft-optics, including hard-optics drivers, Management Soft-optics, Routing Soft-optics and System Soft-optics 4) Key component of Routing and System Soft-optics, namely optical routing and signaling (including UNI/NNI and GMPLS signaling). In summary, the soft-optics on a new generation of OXC's enables Intelligent Optical Networks to provide just-in-time service delivery and fast restoration, and real-time capacity management that eliminates stranded bandwidth. It reduces operational costs and provides new revenue opportunities.

  19. ORDERED WEIGHTED DISTANCE MEASURE

    Institute of Scientific and Technical Information of China (English)

    Zeshui XU; Jian CHEN

    2008-01-01

    The aim of this paper is to develop an ordered weighted distance (OWD) measure, which is thegeneralization of some widely used distance measures, including the normalized Hamming distance, the normalized Euclidean distance, the normalized geometric distance, the max distance, the median distance and the min distance, etc. Moreover, the ordered weighted averaging operator, the generalized ordered weighted aggregation operator, the ordered weighted geometric operator, the averaging operator, the geometric mean operator, the ordered weighted square root operator, the square root operator, the max operator, the median operator and the min operator axe also the special cases of the OWD measure. Some methods depending on the input arguments are given to determine the weights associated with the OWD measure. The prominent characteristic of the OWD measure is that it can relieve (or intensify) the influence of unduly large or unduly small deviations on the aggregation results by assigning them low (or high) weights. This desirable characteristic makes the OWD measure very suitable to be used in many actual fields, including group decision making, medical diagnosis, data mining, and pattern recognition, etc. Finally, based on the OWD measure, we develop a group decision making approach, and illustrate it with a numerical example.

  20. Distance-transitive graphs

    NARCIS (Netherlands)

    Cohen, A.M.; Beineke, L.W.; Wilson, R.J.; Cameron, P.J.

    2004-01-01

    In this chapter we investigate the classification of distance-transitive graphs: these are graphs whose automorphism groups are transitive on each of the sets of pairs of vertices at distance i, for i = 0, 1,.... We provide an introduction into the field. By use of the classification of finite

  1. Distance Education in Entwicklungslandern.

    Science.gov (United States)

    German Foundation for International Development, Bonn (West Germany).

    Seminar and conference reports and working papers on distance education of adults, which reflect the experiences of many countries, are presented. Contents include the draft report of the 1979 International Seminar on Distance Education held in Addis Ababa, Ethiopia, which was jointly sponsored by the United Nations Economic Commission for Africa…

  2. Encyclopedia of distances

    CERN Document Server

    Deza, Michel Marie

    2009-01-01

    Distance metrics and distances have become an essential tool in many areas of pure and applied Mathematics. This title offers both independent introductions and definitions, while at the same time making cross-referencing easy through hyperlink-like boldfaced references to original definitions.

  3. Distance Education in Turkey

    Directory of Open Access Journals (Sweden)

    Dr. Nursel Selver RUZGAR,

    2004-04-01

    Full Text Available Distance Education in Turkey Assistant Professor Dr. Nursel Selver RUZGAR Technical Education Faculty Marmara University, TURKEY ABSTRACT Many countries of the world are using distance education with various ways, by internet, by post and by TV. In this work, development of distance education in Turkey has been presented from the beginning. After discussing types and applications for different levels of distance education in Turkey, the distance education was given in the cultural aspect of the view. Then, in order to create the tendencies and thoughts of graduates of Higher Education Institutions and Distance Education Institutions about being competitors in job markets, sufficiency of education level, advantages for education system, continuing education in different Institutions, a face-to-face survey was applied to 1284 graduates, 958 from Higher Education Institutions and 326 from Distance Education Institutions. The results were evaluated and discussed. In the last part of this work, suggestions to become widespread and improve the distance education in the country were made.

  4. Distance and Cable Length Measurement System

    Science.gov (United States)

    Hernández, Sergio Elias; Acosta, Leopoldo; Toledo, Jonay

    2009-01-01

    A simple, economic and successful design for distance and cable length detection is presented. The measurement system is based on the continuous repetition of a pulse that endlessly travels along the distance to be detected. There is a pulse repeater at both ends of the distance or cable to be measured. The endless repetition of the pulse generates a frequency that varies almost inversely with the distance to be measured. The resolution and distance or cable length range could be adjusted by varying the repetition time delay introduced at both ends and the measurement time. With this design a distance can be measured with centimeter resolution using electronic system with microsecond resolution, simplifying classical time of flight designs which require electronics with picosecond resolution. This design was also applied to position measurement. PMID:22303169

  5. Ultra-Long-Distance Hybrid BOTDA/Ф-OTDR

    Directory of Open Access Journals (Sweden)

    Yun Fu

    2018-03-01

    Full Text Available In the distributed optical fiber sensing (DOFS domain, simultaneous measurement of vibration and temperature/strain based on Rayleigh scattering and Brillouin scattering in fiber could have wide applications. However, there are certain challenges for the case of ultra-long sensing range, including the interplay of different scattering mechanisms, the interaction of two types of sensing signals, and the competition of pump power. In this paper, a hybrid DOFS system, which can simultaneously measure temperature/strain and vibration over 150 km, is elaborately designed via integrating the Brillouin optical time-domain analyzer (BOTDA and phase-sensitive optical time-domain reflectometry (Ф-OTDR. Distributed Raman and Brillouin amplifications, frequency division multiplexing (FDM, wavelength division multiplexing (WDM, and time division multiplexing (TDM are delicately fused to accommodate ultra-long-distance BOTDA and Ф-OTDR. Consequently, the sensing range of the hybrid system is 150.62 km, and the spatial resolution of BOTDA and Ф-OTDR are 9 m and 30 m, respectively. The measurement uncertainty of the BOTDA is ± 0.82 MHz. To the best of our knowledge, this is the first time that such hybrid DOFS is realized with a hundred-kilometer length scale.

  6. NEuclid: a long-range tilt-immune homodyne interferometer

    Science.gov (United States)

    Bradshaw, M. J.; Speake, C. C.

    2017-11-01

    The new Easy to Use Compact Laser Interferometric Device (nEUCLID) is a polarisation-based homodyne interferometer with substantially unequal arms that is tolerant to target mirror tilt. The design has no active components, uses standard optical components of 25 mm diameter, has a working distance of 706 mm and a reference arm-length of 21 mm. nEUCLID optics have a footprint of 210 x 190 x 180 mm, and has a tolerance to target mirror tilt of +/- 0.5 degrees, made possible by a novel new retro-reflector design [1]. nEUCLID was built to a set of specifications laid down by Airbus Defence and Space, who required a lowmass, low-power device to measure displacement with nanometre accuracy for space applications. At the University of Birmingham we have previously built a smaller, more compact tilt-insensitive homodyne interferometer - the EUCLID [2, 3, 4] - which has a working distance of 6 mm, a working range of +/- 3 mm, and a tilt range of +/- 1° [2]. We created a new optical design to allow a much larger working distance to be achieved (as discussed in Section II) and used this in a new interferometer - the nEUCLID. Section II describes the interferometer in detail; how nEUCLID is tilt insensitive, and the optical configuration. Section III states the design specifications from Airbus Defence and Space and the components used in the final design. The output interference pattern from nEUCLID, and how it has been corrected with a meniscus lens, is also discussed. In Section IV we discuss the results demonstrating the tilt immunity range, and the sensitivity of the device. Section V describes several potential applications of nEUCLID, and Section VI draws together our conclusions.

  7. Simultaneous broadband laser ranging and photonic Doppler velocimetry for dynamic compression experiments

    Energy Technology Data Exchange (ETDEWEB)

    La Lone, B. M., E-mail: lalonebm@nv.doe.gov; Marshall, B. R.; Miller, E. K.; Stevens, G. D.; Turley, W. D. [National Security Technologies, LLC, Special Technologies Laboratory, Santa Barbara, California 93111 (United States); Veeser, L. R. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

    2015-02-15

    A diagnostic was developed to simultaneously measure both the distance and velocity of rapidly moving surfaces in dynamic compression experiments, specifically non-planar experiments where integrating the velocity in one direction does not always give the material position accurately. The diagnostic is constructed mainly from fiber-optic telecommunications components. The distance measurement is based on a technique described by Xia and Zhang [Opt. Express 18, 4118 (2010)], which determines the target distance every 20 ns and is independent of the target speed. We have extended the full range of the diagnostic to several centimeters to allow its use in dynamic experiments, and we multiplexed it with a photonic Doppler velocimetry (PDV) system so that distance and velocity histories can be measured simultaneously using one fiber-optic probe. The diagnostic was demonstrated on a spinning square cylinder to show how integrating a PDV record can give an incorrect surface position and how the ranging diagnostic described here obtains it directly. The diagnostic was also tested on an explosive experiment where copper fragments and surface ejecta were identified in both the distance and velocity signals. We show how the distance measurements complement the velocity data. Potential applications are discussed.

  8. Motivation in Distance Leaming

    Directory of Open Access Journals (Sweden)

    Daniela Brečko

    1996-12-01

    Full Text Available It is estimated that motivation is one of the most important psychological functions making it possible for people to leam even in conditions that do not meet their needs. In distance learning, a form of autonomous learning, motivation is of outmost importance. When adopting this method in learning an individual has to stimulate himself and take learning decisions on his or her own. These specific characteristics of distance learning should be taken into account. This all different factors maintaining the motivation of partici­pants in distance learning are to be included. Moreover, motivation in distance learning can be stimulated with specific learning materials, clear instructions and guide-lines, an efficient feed back, personal contact between tutors and parti­cipants, stimulating learning letters, telephone calls, encouraging letters and through maintaining a positive relationship between tutor and participant.

  9. Overcoming the rate-distance limit of quantum key distribution without quantum repeaters.

    Science.gov (United States)

    Lucamarini, M; Yuan, Z L; Dynes, J F; Shields, A J

    2018-05-01

    Quantum key distribution (QKD) 1,2 allows two distant parties to share encryption keys with security based on physical laws. Experimentally, QKD has been implemented via optical means, achieving key rates of 1.26 megabits per second over 50 kilometres of standard optical fibre 3 and of 1.16 bits per hour over 404 kilometres of ultralow-loss fibre in a measurement-device-independent configuration 4 . Increasing the bit rate and range of QKD is a formidable, but important, challenge. A related target, which is currently considered to be unfeasible without quantum repeaters 5-7 , is overcoming the fundamental rate-distance limit of QKD 8 . This limit defines the maximum possible secret key rate that two parties can distil at a given distance using QKD and is quantified by the secret-key capacity of the quantum channel 9 that connects the parties. Here we introduce an alternative scheme for QKD whereby pairs of phase-randomized optical fields are first generated at two distant locations and then combined at a central measuring station. Fields imparted with the same random phase are 'twins' and can be used to distil a quantum key. The key rate of this twin-field QKD exhibits the same dependence on distance as does a quantum repeater, scaling with the square-root of the channel transmittance, irrespective of who (malicious or otherwise) is in control of the measuring station. However, unlike schemes that involve quantum repeaters, ours is feasible with current technology and presents manageable levels of noise even on 550 kilometres of standard optical fibre. This scheme is a promising step towards overcoming the rate-distance limit of QKD and greatly extending the range of secure quantum communications.

  10. Optical Orbit Determination of a Geosynchronous Earth Orbit Satellite Effected by Baseline Distances between Various Ground-based Tracking Stations Ⅱ: COMS Case with Analysis of Actual Observation Data

    Directory of Open Access Journals (Sweden)

    Ju Young Son

    2015-09-01

    Full Text Available We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS, a Geostationary Earth Orbit (GEO satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO of the Korea Astronomy and Space Science Institute (KASI, Optical Wide field Patrol (OWL at KASI, and the Chungbuk National University Observatory (CNUO from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

  11. Long distance quantum teleportation

    Science.gov (United States)

    Xia, Xiu-Xiu; Sun, Qi-Chao; Zhang, Qiang; Pan, Jian-Wei

    2018-01-01

    Quantum teleportation is a core protocol in quantum information science. Besides revealing the fascinating feature of quantum entanglement, quantum teleportation provides an ultimate way to distribute quantum state over extremely long distance, which is crucial for global quantum communication and future quantum networks. In this review, we focus on the long distance quantum teleportation experiments, especially those employing photonic qubits. From the viewpoint of real-world application, both the technical advantages and disadvantages of these experiments are discussed.

  12. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  13. A cognitively grounded measure of pronunciation distance.

    Directory of Open Access Journals (Sweden)

    Martijn Wieling

    Full Text Available In this study we develop pronunciation distances based on naive discriminative learning (NDL. Measures of pronunciation distance are used in several subfields of linguistics, including psycholinguistics, dialectology and typology. In contrast to the commonly used Levenshtein algorithm, NDL is grounded in cognitive theory of competitive reinforcement learning and is able to generate asymmetrical pronunciation distances. In a first study, we validated the NDL-based pronunciation distances by comparing them to a large set of native-likeness ratings given by native American English speakers when presented with accented English speech. In a second study, the NDL-based pronunciation distances were validated on the basis of perceptual dialect distances of Norwegian speakers. Results indicated that the NDL-based pronunciation distances matched perceptual distances reasonably well with correlations ranging between 0.7 and 0.8. While the correlations were comparable to those obtained using the Levenshtein distance, the NDL-based approach is more flexible as it is also able to incorporate acoustic information other than sound segments.

  14. A short working distance multiple crystal x-ray spectrometer

    Science.gov (United States)

    Dickinson, B.; Seidler, G.T.; Webb, Z.W.; Bradley, J.A.; Nagle, K.P.; Heald, S.M.; Gordon, R.A.; Chou, I.-Ming

    2008-01-01

    For x-ray spot sizes of a few tens of microns or smaller, a millimeter-sized flat analyzer crystal placed ???1 cm from the sample will exhibit high energy resolution while subtending a collection solid angle comparable to that of a typical spherically bent crystal analyzer (SBCA) at much larger working distances. Based on this observation and a nonfocusing geometry for the analyzer optic, we have constructed and tested a short working distance (SWD) multicrystal x-ray spectrometer. This prototype instrument has a maximum effective collection solid angle of 0.14 sr, comparable to that of 17 SBCA at 1 m working distance. We find good agreement with prior work for measurements of the Mn K?? x-ray emission and resonant inelastic x-ray scattering for MnO, and also for measurements of the x-ray absorption near-edge structure for Dy metal using L??2 partial-fluorescence yield detection. We discuss future applications at third- and fourth-generation light sources. For concentrated samples, the extremely large collection angle of SWD spectrometers will permit collection of high-resolution x-ray emission spectra with a single pulse of the Linac Coherent Light Source. The range of applications of SWD spectrometers and traditional multi-SBCA instruments has some overlap, but also is significantly complementary. ?? 2008 American Institute of Physics.

  15. Improvement of input power dynamic range for 20 Gbit/s optical WDM switch nodes using an integrated Michelson wavelength converter

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Hansen, Peter Bukhave; Jørgensen, Carsten

    1997-01-01

    be improved compared to switch blocks without IWCs. This is especially important at high bit rates where the cascadability of the SOA gates decreases. Here, more than 15 dB improvement of the input power dynamic range is achieved at 20 Gbit/s using a high-speed Michelson interferometer wavelength converter...

  16. Measurements using optic and RF waves

    CERN Document Server

    De Fornel, Frederique

    2013-01-01

    Scientific and technical knowledge for measurements in modern electromagnetism must be vast as our electromagnetic environment covers all frequencies and wavelengths. These measurements must be applied to fields as varied as nanotechnologies, telecommunications, meteorology, geolocalization, radioastronomy, health, biology, etc. In order to cover the multiple facets of the topic, this book sweeps the entire electromagnetic spectrum, from several hertz to terahertz; considers distances ranging from nanometers to light-years in optics; before extending towards the various measurement techniques

  17. Broad range tuning of structural and optical properties of Znx Mg1−x O nanostructures grown by vapor transport method

    International Nuclear Information System (INIS)

    Vanjaria, Jignesh V; Azhar, Ebraheem Ali; Yu, Hongbin

    2016-01-01

    One-dimensional (1D) Zn x Mg 1−x O nanomaterials have drawn global attention due to their remarkable chemical and physical properties, and their diverse current and future technological applications. In this work, 1D ZnMgO nanostructures with different magnesium concentrations and different morphologies were grown directly on zinc oxide-coated silicon substrates by thermal evaporation of zinc oxide, magnesium boride and graphite powders. Highly well-defined Mg-rich ZnMgO nanorods with a rock salt structure and Zn-rich ZnMgO nanostructures with a wurtzite structure have been deposited individually by careful optimization of the source mixture and process parameters. Structural and optical properties of the deposited products were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy. Cathodoluminescence measurements demonstrate strong dominant peaks at 3.3 eV in Mg poor ZnMgO nanostructures and 4.8 eV in Mg rich nanostructures implying that the ZnMgO nanostructures can be used for the fabrication of deep UV optoelectronic devices. A mechanism for the formation and achieved diverse morphology of the ZnMgO nanostructures was proposed based on the characterization results. (paper)

  18. Higher order modes of coupled optical fibres

    International Nuclear Information System (INIS)

    Alexeyev, C N; Yavorsky, M A; Boklag, N A

    2010-01-01

    The structure of hybrid higher order modes of two coupled weakly guiding identical optical fibres is studied. On the basis of perturbation theory with degeneracy for the vector wave equation expressions for modes with azimuthal angular number l ≥ 1 are obtained that allow for the spin–orbit interaction. The spectra of polarization corrections to the scalar propagation constants are calculated in a wide range of distances between the fibres. The limiting cases of widely and closely spaced fibres are studied. The obtained results can be used for studying the tunnelling of optical vortices in directional couplers and in matters concerned with information security

  19. The theory of the quasi-optical grill: A lower hybrid wave launcher in the 4 - 10 GHz range for high field tokamaks

    International Nuclear Information System (INIS)

    Preinhaelter, J.; Vahala, L.; Vahala, G.

    1996-01-01

    Lower hybrid (LH) waves have been utilized for plasma heating and current drive in tokamaks. LH current drive has good efficiency in low to moderate plasma temperatures and is an excellent tool for attaining the reversed shear regions of much interest in advanced steady state tokamak scenarios. For high field tokamaks, the waveguides of the standard multifunction grills would become very narrow and the walls separating the waveguides would need to be very thin. As a result, the cooling of such structures becomes very difficult. Moreover, there are concerns that the classical grill launcher could not withstand the conditions at the reactor first wall. The Quasi-Optical Grill (QOG) was first proposed by Petelin ampersand Suvorov to overcome some of these difficulties. QOG attempts to couple the RF power to the plasma slow wave by means of the diffraction of the incident wave on an array of rods. However, these original calculations are based on certain idealized assumptions and lead to poor coupling to the plasma. Preinhaelter has suggested a new QOG in which the rods are placed in one oversized waveguide (open-quotes hyperguideclose quotes) and irradiated obliquely by the wave emerging as a higher order mode from an auxiliary oversized waveguide. The confining walls are now an intrinsic part of the structure and thus one avoids the need for mirrors and the introduction of open-quote point-like close-quote structures. This new QOG is compact - with several orders of magnitude less construction elements than the classical LH launcher - and the problem of wave diffraction can be readily solved using the full wave method. Here we consider the optimization of a large scale QOG at a given frequency. The irradiation of either a single row or double set of rows of rods are considered as well as their optimal separation. One can achieve transmissivity and directivity comparable to those of the multifunction grill. Design of a QOG for TORE-SUPRA will also be discussed

  20. Wide-area remote-sensing system of pollution and gas dispersal by near-infrared absorption based on low-loss optical fiber network

    Science.gov (United States)

    Inaba, H.

    1986-01-01

    An all optical remote sensing system utilizing long distance, ultralow loss optical fiber networks is studied and discussed for near infrared absorption measurements of combustible and/or explosive gases such as CH4 and C3H8 in our environment, including experimental results achieved in a diameter more than 20 km. The use of a near infrared wavelength range is emphasized.

  1. Seed-Mediated Synthesis of Ag Nanocubes with Controllable Edge Lengths in the Range of 30–200 nm and Comparison of Their Optical Properties

    OpenAIRE

    Zhang, Qiang; Li, Weiyang; Moran, Christine; Zeng, Jie; Chen, Jingyi; Wen, Long-Ping; Xia, Younan

    2010-01-01

    Silver nanocubes with edge lengths controllable in the range of 30–200 nm were synthesized using an approach based on seeded growth. The key to the success of this synthesis is the use of single-crystal Ag seeds to direct the growth and the use of AgNO3 as a precursor to elemental Ag where the by-product HNO3 can block both the homogeneous nucleation and evolution of single-crystal seeds into twinned nanoparticles. Either spherical (in the shape of cubooctahedron) or cubic seeds could be empl...

  2. Distance Teaching on Bornholm

    DEFF Research Database (Denmark)

    Hansen, Finn J. S.; Clausen, Christian

    2001-01-01

    The case study represents an example of a top-down introduction of distance teaching as part of Danish trials with the introduction of multimedia in education. The study is concerned with the background, aim and context of the trial as well as the role and working of the technology and the organi......The case study represents an example of a top-down introduction of distance teaching as part of Danish trials with the introduction of multimedia in education. The study is concerned with the background, aim and context of the trial as well as the role and working of the technology...

  3. Seed-Mediated Synthesis of Ag Nanocubes with Controllable Edge Lengths in the Range of 30–200 nm and Comparison of Their Optical Properties

    Science.gov (United States)

    Zhang, Qiang; Li, Weiyang; Moran, Christine; Zeng, Jie; Chen, Jingyi; Wen, Long-Ping; Xia, Younan

    2010-01-01

    Silver nanocubes with edge lengths controllable in the range of 30–200 nm were synthesized using an approach based on seeded growth. The key to the success of this synthesis is the use of single-crystal Ag seeds to direct the growth and the use of AgNO3 as a precursor to elemental Ag where the by-product HNO3 can block both the homogeneous nucleation and evolution of single-crystal seeds into twinned nanoparticles. Either spherical (in the shape of cubooctahedron) or cubic seeds could be employed for this growth process. The edge length of resultant Ag nanocubes can be readily controlled by varying the amount of Ag seeds used, the amount of AgNO3 added, or both. For the first time, we could obtain Ag nanocubes with uniform edge lengths controllable in the range of 30–200 nm and then compare their localized surface plasmon resonance and surface-enhanced Raman scattering properties. PMID:20698704

  4. Seed-mediated synthesis of Ag nanocubes with controllable edge lengths in the range of 30-200 nm and comparison of their optical properties.

    Science.gov (United States)

    Zhang, Qiang; Li, Weiyang; Moran, Christine; Zeng, Jie; Chen, Jingyi; Wen, Long-Ping; Xia, Younan

    2010-08-18

    Silver nanocubes with edge lengths controllable in the range of 30-200 nm were synthesized using an approach based on seeded growth. The keys to the success of this synthesis are the use of single-crystal Ag seeds to direct the growth and the use of AgNO(3) as a precursor to elemental Ag, where the byproduct HNO(3) can block both the homogeneous nucleation and evolution of single-crystal seeds into twinned nanoparticles. Either spherical (in the shape of a cuboctahedron) or cubic seeds could be employed for this growth process. The edge length of the resultant Ag nanocubes can be readily controlled by varying the amount of Ag seeds used, the amount of AgNO(3) added, or both. For the first time, we could obtain Ag nanocubes with uniform edge lengths controllable in the range of 30-200 nm and then compare their localized surface plasmon resonance and surface-enhanced Raman scattering properties.

  5. The Rainwater Memorial Calibration Facility for X-Ray Optics

    DEFF Research Database (Denmark)

    Brejnholt, Nicolai; Christensen, Finn Erland; Hailey, Charles J.

    2011-01-01

    The Nuclear Spectroscopic Telescope ARray (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5–80 keV) telescope to orbit. The ground calibration of the optics posed a challenge as the need to suppress finite source distance effects over the full optic...... and the energy range of interest were unique requirements not met by any existing facility. In this paper we present the requirements for the NuSTAR optics ground calibration, and how the Rainwater Memorial Calibration Facility, RaMCaF, is designed to meet the calibration requirements. The nearly 175 m long...

  6. Establishing Age-Adjusted Reference Ranges for Iris-Related Parameters in Open Angle Eyes with Anterior Segment Optical Coherence Tomography.

    Directory of Open Access Journals (Sweden)

    Jeffrey R Peterson

    Full Text Available Define criteria for iris-related parameters in an adult open angle population as measured with swept source Fourier domain anterior segment optical coherence tomography (ASOCT.Ninety-eight eyes of 98 participants with open angles were included and stratified into 5 age groups (18-35, 36-45, 46-55, 56-65, and 66-79 years. ASOCT scans with 3D mode angle analysis were taken with the CASIA SS-1000 (Tomey Corporation, Nagoya, Japan and analyzed using the Anterior Chamber Analysis and Interpretation software. Anterior iris surface length (AISL, length of scleral spur landmark (SSL to pupillary margin (SSL-to-PM, iris contour ratio (ICR = AISL/SSL-to-PM, pupil radius, radius of iris centroid (RICe, and iris volume were measured. Outcome variables were summarized for all eyes and age groups, and mean values among age groups were compared using one-way analysis of variance. Stepwise regression analysis was used to investigate demographic and ocular characteristic factors that affected each iris-related parameter.Mean (±SD values were 2.24 mm (±0.46, 4.06 mm (±0.27, 3.65 mm (±0.48, 4.16 mm (±0.47, 1.14 (±0.04, 1.51 mm2 (±0.23, and 38.42 μL (±4.91 for pupillary radius, RICe, SSL-to-PM, AISL, ICR, iris cross-sectional area, and iris volume, respectively. Both pupillary radius (P = 0.002 and RICe (P = 0.027 decreased with age, while SSL-to-PM (P = 0.002 and AISL increased with age (P = 0.001. ICR (P = 0.54 and iris volume (P = 0.49 were not affected by age.This study establishes reference values for iris-related parameters in an adult open angle population, which will be useful for future studies examining the role of iris changes in pathologic states.

  7. Theoretical Principles of Distance Education.

    Science.gov (United States)

    Keegan, Desmond, Ed.

    This book contains the following papers examining the didactic, academic, analytic, philosophical, and technological underpinnings of distance education: "Introduction"; "Quality and Access in Distance Education: Theoretical Considerations" (D. Randy Garrison); "Theory of Transactional Distance" (Michael G. Moore);…

  8. Fast Computing for Distance Covariance

    OpenAIRE

    Huo, Xiaoming; Szekely, Gabor J.

    2014-01-01

    Distance covariance and distance correlation have been widely adopted in measuring dependence of a pair of random variables or random vectors. If the computation of distance covariance and distance correlation is implemented directly accordingly to its definition then its computational complexity is O($n^2$) which is a disadvantage compared to other faster methods. In this paper we show that the computation of distance covariance and distance correlation of real valued random variables can be...

  9. A wide range optical pH sensor for living cells using Au@Ag nanoparticles functionalized carbon nanotubes based on SERS signals.

    Science.gov (United States)

    Chen, Peng; Wang, Zhuyuan; Zong, Shenfei; Chen, Hui; Zhu, Dan; Zhong, Yuan; Cui, Yiping

    2014-10-01

    p-Aminothiophenol (pATP) functionalized multi-walled carbon nanotubes (MWCNTs) have been demonstrated as an efficient pH sensor for living cells. The proposed sensor employs gold/silver core-shell nanoparticles (Au@Ag NPs) functionalized MWCNTs hybrid structure as the surface-enhanced Raman scattering (SERS) substrate and pATP molecules as the SERS reporters, which possess a pH-dependent SERS performance. By using MWCNTs as the substrate to be in a state of aggregation, the pH sensing range could be extended to pH 3.0∼14.0, which is much wider than that using unaggregated Au@Ag NPs without MWCNTs. Furthermore, the pH-sensitive performance was well retained in living cells with a low cytotoxicity. The developed SERS-active MWCNTs-based nanocomposite is expected to be an efficient intracellular pH sensor for bio-applications.

  10. Multilayer optics for monochromatic high-resolution X-ray imaging diagnostic in a broad photon energy range from 2 keV to 22 keV

    International Nuclear Information System (INIS)

    Troussel, Ph.; Dennetiere, D.; Maroni, R.; Høghøj, P.; Hedacq, S.; Cibik, L.; Krumrey, M.

    2014-01-01

    The “Commissariat à l’énergie atomique et aux énergies alternatives” (CEA) studies and designs advanced X-ray diagnostics to probe dense plasmas produced at the future Laser MegaJoule (LMJ) facility. Mainly for X-ray imaging with high spatial resolution, different types of multilayer mirrors were developed to provide broadband X-ray reflectance at grazing incidence. These coatings are deposited on two toroidal mirror substrates that are then mounted into a Wolter-type geometry (working at a grazing angle of 0.45°) to realize an X-ray microscope. Non-periodic (depth graded) W/Si multilayer can be used in the broad photon energy range from 2 keV to 22 keV. A third flat mirror can be added for the spectral selection of the microscope. This mirror is coated with a Mo/Si multilayer for which the d-spacing varies in the longitudinal direction to satisfy the Bragg condition within the angular acceptance of the microscope and also to compensate the angular dispersion due to the field of the microscope. We present a study of such a so-called Göbel mirror which was optimized for photon energy of 10.35 keV. The three mirrors were coated using magnetron sputtering technology by Xenocs SA. The reflectance in the entire photon energy range was determined in the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the synchrotron radiation facility BESSY II in Berlin

  11. Multilayer optics for monochromatic high-resolution X-ray imaging diagnostic in a broad photon energy range from 2 keV to 22 keV

    Energy Technology Data Exchange (ETDEWEB)

    Troussel, Ph., E-mail: philippe.troussel@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Dennetiere, D. [Synchrotron Soleil, L’orme des Merisiers, 91190 Saint-Aubin (France); Maroni, R. [CEA, DAM, DIF, F-91297 Arpajon (France); Høghøj, P.; Hedacq, S. [Xenocs SA, 19, rue François Blumet, F-38360 Sassenage (France); Cibik, L.; Krumrey, M. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany)

    2014-12-11

    The “Commissariat à l’énergie atomique et aux énergies alternatives” (CEA) studies and designs advanced X-ray diagnostics to probe dense plasmas produced at the future Laser MegaJoule (LMJ) facility. Mainly for X-ray imaging with high spatial resolution, different types of multilayer mirrors were developed to provide broadband X-ray reflectance at grazing incidence. These coatings are deposited on two toroidal mirror substrates that are then mounted into a Wolter-type geometry (working at a grazing angle of 0.45°) to realize an X-ray microscope. Non-periodic (depth graded) W/Si multilayer can be used in the broad photon energy range from 2 keV to 22 keV. A third flat mirror can be added for the spectral selection of the microscope. This mirror is coated with a Mo/Si multilayer for which the d-spacing varies in the longitudinal direction to satisfy the Bragg condition within the angular acceptance of the microscope and also to compensate the angular dispersion due to the field of the microscope. We present a study of such a so-called Göbel mirror which was optimized for photon energy of 10.35 keV. The three mirrors were coated using magnetron sputtering technology by Xenocs SA. The reflectance in the entire photon energy range was determined in the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the synchrotron radiation facility BESSY II in Berlin.

  12. Multilayer optics for monochromatic high-resolution X-ray imaging diagnostic in a broad photon energy range from 2 keV to 22 keV

    Science.gov (United States)

    Troussel, Ph.; Dennetiere, D.; Maroni, R.; Høghøj, P.; Hedacq, S.; Cibik, L.; Krumrey, M.

    2014-12-01

    The "Commissariat à l'énergie atomique et aux énergies alternatives" (CEA) studies and designs advanced X-ray diagnostics to probe dense plasmas produced at the future Laser MegaJoule (LMJ) facility. Mainly for X-ray imaging with high spatial resolution, different types of multilayer mirrors were developed to provide broadband X-ray reflectance at grazing incidence. These coatings are deposited on two toroidal mirror substrates that are then mounted into a Wolter-type geometry (working at a grazing angle of 0.45°) to realize an X-ray microscope. Non-periodic (depth graded) W/Si multilayer can be used in the broad photon energy range from 2 keV to 22 keV. A third flat mirror can be added for the spectral selection of the microscope. This mirror is coated with a Mo/Si multilayer for which the d-spacing varies in the longitudinal direction to satisfy the Bragg condition within the angular acceptance of the microscope and also to compensate the angular dispersion due to the field of the microscope. We present a study of such a so-called Göbel mirror which was optimized for photon energy of 10.35 keV. The three mirrors were coated using magnetron sputtering technology by Xenocs SA. The reflectance in the entire photon energy range was determined in the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the synchrotron radiation facility BESSY II in Berlin.

  13. Hybrid Long-Distance Entanglement Distribution Protocol

    DEFF Research Database (Denmark)

    Brask, J.B.; Rigas, I.; Polzik, E.S.

    2010-01-01

    We propose a hybrid (continuous-discrete variable) quantum repeater protocol for long-distance entanglement distribution. Starting from states created by single-photon detection, we show how entangled coherent state superpositions can be generated by means of homodyne detection. We show that near......-deterministic entanglement swapping with such states is possible using only linear optics and homodyne detectors, and we evaluate the performance of our protocol combining these elements....

  14. Planning with Reachable Distances

    KAUST Repository

    Tang, Xinyu; Thomas, Shawna; Amato, Nancy M.

    2009-01-01

    reachable distance space (RD-space), in which all configurations lie in the set of constraint-satisfying subspaces. This enables us to directly sample the constrained subspaces with complexity linear in the robot's number of degrees of freedom. In addition

  15. De-severing distance

    DEFF Research Database (Denmark)

    Jensen, Hanne Louise; de Neergaard, Maja

    2016-01-01

    De-severing Distance This paper draws on the growing body of mobility literature that shows how mobility can be viewed as meaningful everyday practices (Freudendal –Pedersen 2007, Cresswell 2006) this paper examines how Heidegger’s term de-severing can help us understand the everyday coping with ...

  16. The Euclidean distance degree

    NARCIS (Netherlands)

    Draisma, J.; Horobet, E.; Ottaviani, G.; Sturmfels, B.; Thomas, R.R.; Zhi, L.; Watt, M.

    2014-01-01

    The nearest point map of a real algebraic variety with respect to Euclidean distance is an algebraic function. For instance, for varieties of low rank matrices, the Eckart-Young Theorem states that this map is given by the singular value decomposition. This article develops a theory of such nearest

  17. Electromagnetic distance measurement

    CERN Document Server

    1967-01-01

    This book brings together the work of forty-eight geodesists from twenty-five countries. They discuss various new electromagnetic distance measurement (EDM) instruments - among them the Tellurometer, Geodimeter, and air- and satellite-borne systems - and investigate the complex sources of error.

  18. Determining average yarding distance.

    Science.gov (United States)

    Roger H. Twito; Charles N. Mann

    1979-01-01

    Emphasis on environmental and esthetic quality in timber harvesting has brought about increased use of complex boundaries of cutting units and a consequent need for a rapid and accurate method of determining the average yarding distance and area of these units. These values, needed for evaluation of road and landing locations in planning timber harvests, are easily and...

  19. Prospect of Distance Learning

    Science.gov (United States)

    Rahman, Monsurur; Karim, Reza; Byramjee, Framarz

    2015-01-01

    Many educational institutions in the United States are currently offering programs through distance learning, and that trend is rising. In almost all spheres of education a developing country like Bangladesh needs to make available the expertise of the most qualified faculty to her distant people. But the fundamental question remains as to whether…

  20. 80537 based distance relay

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen

    1999-01-01

    A method for implementing a digital distance relay in the power system is described.Instructions are given on how to program this relay on a 80537 based microcomputer system.The problem is used as a practical case study in the course 53113: Micocomputer applications in the power system.The relay...

  1. Long distance measurement with a femtosecond laser based frequency comb

    Science.gov (United States)

    Bhattacharya, N.; Cui, M.; Zeitouny, M. G.; Urbach, H. P.; van den Berg, S. A.

    2017-11-01

    Recent advances in the field of ultra-short pulse lasers have led to the development of reliable sources of carrier envelope phase stabilized femtosecond pulses. The pulse train generated by such a source has a frequency spectrum that consists of discrete, regularly spaced lines known as a frequency comb. In this case both the frequency repetition and the carrier-envelope-offset frequency are referenced to a frequency standard, like an atomic clock. As a result the accuracy of the frequency standard is transferred to the optical domain, with the frequency comb as transfer oscillator. These unique properties allow the frequency comb to be applied as a versatile tool, not only for time and frequency metrology, but also in fundamental physics, high-precision spectroscopy, and laser noise characterization. The pulse-to-pulse phase relationship of the light emitted by the frequency comb has opened up new directions for long range highly accurate distance measurement.

  2. Underwater Ranging

    OpenAIRE

    S. P. Gaba

    1984-01-01

    The paper deals with underwater laser ranging system, its principle of operation and maximum depth capability. The sources of external noise and methods to improve signal-to-noise ratio are also discussed.

  3. A green and facile approach for synthesizing imine to develop optical biosensor for wide range detection of bilirubin in human biofluids.

    Science.gov (United States)

    Ellairaja, Sundaram; Shenbagavalli, Kathiravan; Ponmariappan, Sarkaraisamy; Vasantha, Vairathevar Sivasamy

    2017-05-15

    Bilirubin, a key biomarker for the jaundice and its clinical diagnosis needs a better analytical tool. A novel and simple fluorescent platform based on (2,2'-((1E,1'E)-((6-bromopyridine-2,3-diyl) bis(azanylylidene)) bis(methanylylidene diphenol) (BAMD) was designed. BAMD showed a remarkable fluorescent intensity with a very good quantum yield of 0.85 and lifetime of 870ps. Hence, it was applied for the determination of bilirubin using both colorimetric and fluorimetric techniques in physiological and basic pH. Under optimized experimental conditions, the probe detects bilirubin selectively in the presence of other interfering biomolecules and metal ions. The linear range of detection is 1pM-500µM at pH=7.4 and LOD is 2.8 and 3.3 pM at pH=7.4 and 9.0, respectively, which were reported so far. The probe detects the bilirubin through FRET mechanism. The practical application of the probe was successfully tested in the human blood and urine samples. Based on all above advantages, this simple idea can be applied to design a simple clinical diagnostic tool for jaundice. Copyright © 2016. Published by Elsevier B.V.

  4. Investigations of coal ignition in a short-range flame burner using optical measuring systems; Untersuchungen zur Kohlezuendung am Flachflammenbrenner unter Verwendung optischer Messtechnik

    Energy Technology Data Exchange (ETDEWEB)

    Hackert, G.; Kremer, H.; Wirtz, S. [Bochum Univ. (Germany). Lehrstuhl fuer Energieanlagentechnik

    1999-09-01

    The short-range flame burner and the KOALA reactor of DMT are experimental facilities for realistic simulation of coal conversion processes at high temperatures and pressures in atmospheric conditions. The TOSCA system enable measurements of temperatures, sizes, shapes and velocities of the fuel particles, which serve as a basis for a three-dimensional simulation model of coal combustion. In the future, further parameter studies will deepen the present knowledge of coal dust combustion under pressure and enable optimisation of the numerical models for simulation of industrial-scale systems for coal dust combustion under pressure. [Deutsch] Mit dem Flachflammenbrenner und dem KOALA-Reaktor der DMT stehen Versuchsapparaturen zur Verfuegung, mit deren Hilfe die Kohleumwandlungsprozesse bei hohen Temperaturen unter Druck und unter atmosphaerischen Bedingungen realistisch wiedergegeben werden. Das TOSCA-System erlaubt dabei die Bestimmung von Temperaturen, Groessen, Formen und Geschwindigkeiten der Brennstoffpartikel. Diese Daten liefern die Grundlage fuer die Erstellung eines dreidimensionalen Simulationsmodells zur Modellierung der Kohleverbrennung. In Zukunft werden weitere Parameterstudien das Verstaendnis der Kohlenstaubdruckverbrennung vertiefen und ein Optimierung der numerischen Modelle ermoeglichen, so dass die Simulation grosstechnischer Kohlenstaubdruckverbrennungsanlagen realisiert werden kann. (orig.)

  5. THE CHANGING Lyα OPTICAL DEPTH IN THE RANGE 6 < z < 9 FROM THE MOSFIRE SPECTROSCOPY OF Y-DROPOUTS

    International Nuclear Information System (INIS)

    Treu, Tommaso; Schmidt, Kasper B.; Trenti, Michele; Bradley, Larry D.; Stiavelli, Massimo

    2013-01-01

    We present the MOSFIRE spectroscopy of 13 candidate z ∼ 8 galaxies selected as Y-dropouts as part of the Brightest of Reionization Galaxies pure parallel survey. We detect no significant Lyα emission (our median 1σ rest-frame equivalent width sensitivity is in the range 2-16 Å). Using the Bayesian framework derived in a previous paper, we perform a rigorous analysis of a statistical subsample of non-detections for 10 Y-dropouts, including data from the literature, to study the cosmic evolution of the Lyα emission of Lyman break galaxies. We find that Lyα emission is suppressed at z ∼ 8 by at least a factor of three with respect to z ∼ 6 continuing the downward trend found by previous studies of z-dropouts at z ∼ 7. This finding suggests a dramatic evolution in the conditions of the intergalactic or circumgalactic media in just 300 Myr, consistent with the onset of reionization or changes in the physical conditions of the first generations of star-forming regions

  6. A stingless bee can use visual odometry to estimate both height and distance.

    Science.gov (United States)

    Eckles, M A; Roubik, D W; Nieh, J C

    2012-09-15

    Bees move and forage within three dimensions and rely heavily on vision for navigation. The use of vision-based odometry has been studied extensively in horizontal distance measurement, but not vertical distance measurement. The honey bee Apis mellifera and the stingless bee Melipona seminigra measure distance visually using optic flow-movement of images as they pass across the retina. The honey bees gauge height using image motion in the ventral visual field. The stingless bees forage at different tropical forest canopy levels, ranging up to 40 m at our site. Thus, estimating height would be advantageous. We provide the first evidence that the stingless bee Melipona panamica utilizes optic flow information to gauge not only distance traveled but also height above ground, by processing information primarily from the lateral visual field. After training bees to forage at a set height in a vertical tunnel lined with black and white stripes, we observed foragers that explored a new tunnel with no feeder. In a new tunnel, bees searched at the same height they were trained to. In a narrower tunnel, bees experienced more image motion and significantly lowered their search height. In a wider tunnel, bees experienced less image motion and searched at significantly greater heights. In a tunnel without optic cues, bees were disoriented and searched at random heights. A horizontal tunnel testing these variables similarly affected foraging, but bees exhibited less precision (greater variance in search positions). Accurately gauging flight height above ground may be crucial for this species and others that compete for resources located at heights ranging from ground level to the high tropical forest canopies.

  7. Time-of-flight range imaging for underwater applications

    Science.gov (United States)

    Merbold, Hannes; Catregn, Gion-Pol; Leutenegger, Tobias

    2018-02-01

    Precise and low-cost range imaging in underwater settings with object distances on the meter level is demonstrated. This is addressed through silicon-based time-of-flight (TOF) cameras operated with light emitting diodes (LEDs) at visible, rather than near-IR wavelengths. We find that the attainable performance depends on a variety of parameters, such as the wavelength dependent absorption of water, the emitted optical power and response times of the LEDs, or the spectral sensitivity of the TOF chip. An in-depth analysis of the interplay between the different parameters is given and the performance of underwater TOF imaging using different visible illumination wavelengths is analyzed.

  8. Censoring distances based on labeled cortical distance maps in cortical morphometry.

    Science.gov (United States)

    Ceyhan, Elvan; Nishino, Tomoyuki; Alexopolous, Dimitrios; Todd, Richard D; Botteron, Kelly N; Miller, Michael I; Ratnanather, J Tilak

    2013-01-01

    It has been demonstrated that shape differences in cortical structures may be manifested in neuropsychiatric disorders. Such morphometric differences can be measured by labeled cortical distance mapping (LCDM) which characterizes the morphometry of the laminar cortical mantle of cortical structures. LCDM data consist of signed/labeled distances of gray matter (GM) voxels with respect to GM/white matter (WM) surface. Volumes and other summary measures for each subject and the pooled distances can help determine the morphometric differences between diagnostic groups, however they do not reveal all the morphometric information contained in LCDM distances. To extract more information from LCDM data, censoring of the pooled distances is introduced for each diagnostic group where the range of LCDM distances is partitioned at a fixed increment size; and at each censoring step, the distances not exceeding the censoring distance are kept. Censored LCDM distances inherit the advantages of the pooled distances but also provide information about the location of morphometric differences which cannot be obtained from the pooled distances. However, at each step, the censored distances aggregate, which might confound the results. The influence of data aggregation is investigated with an extensive Monte Carlo simulation analysis and it is demonstrated that this influence is negligible. As an illustrative example, GM of ventral medial prefrontal cortices (VMPFCs) of subjects with major depressive disorder (MDD), subjects at high risk (HR) of MDD, and healthy control (Ctrl) subjects are used. A significant reduction in laminar thickness of the VMPFC in MDD and HR subjects is observed compared to Ctrl subjects. Moreover, the GM LCDM distances (i.e., locations with respect to the GM/WM surface) for which these differences start to occur are determined. The methodology is also applicable to LCDM-based morphometric measures of other cortical structures affected by disease.

  9. Censoring Distances Based on Labeled Cortical Distance Maps in Cortical Morphometry

    Directory of Open Access Journals (Sweden)

    Elvan eCeyhan

    2013-10-01

    Full Text Available It has been demonstrated that shape differences are manifested in cortical structures due to neuropsychiatric disorders. Such morphometric differences can be measured by labeled cortical distance mapping (LCDM which characterizes the morphometry of the laminar cortical mantle of cortical structures. LCDM data consist of signed/labeled distances of gray matter (GM voxels with respect to GM/white matter (WM surface. Volumes and other summary measures for each subject and the pooled distances can help determine the morphometric differences between diagnostic groups, however they do not reveal all the morphometric information con-tained in LCDM distances. To extract more information from LCDM data, censoring of the pooled distances is introduced for each diagnostic group where the range of LCDM distances is partitioned at a fixed increment size; and at each censoring step, the distances not exceeding the censoring distance are kept. Censored LCDM distances inherit the advantages of the pooled distances but also provide information about the location of morphometric differences which cannot be obtained from the pooled distances. However, at each step, the censored distances aggregate, which might confound the results. The influence of data aggregation is investigated with an extensive Monte Carlo simulation analysis and it is demonstrated that this influence is negligible. As an illustrative example, GM of ventral medial prefrontal cortices (VMPFCs of subjects with major depressive disorder (MDD, subjects at high risk (HR of MDD, and healthy control (Ctrl subjects are used. A significant reduction in laminar thickness of the VMPFC in MDD and HR subjects is observed compared to Ctrl subjects. Moreover, the GM LCDM distances (i.e., locations with respect to the GM/WM surface for which these differences start to occur are determined. The methodology is also applicable to LCDM-based morphometric measures of other cortical structures affected by disease.

  10. Optical CDMA components requirements

    Science.gov (United States)

    Chan, James K.

    1998-08-01

    Optical CDMA is a complementary multiple access technology to WDMA. Optical CDMA potentially provides a large number of virtual optical channels for IXC, LEC and CLEC or supports a large number of high-speed users in LAN. In a network, it provides asynchronous, multi-rate, multi-user communication with network scalability, re-configurability (bandwidth on demand), and network security (provided by inherent CDMA coding). However, optical CDMA technology is less mature in comparison to WDMA. The components requirements are also different from WDMA. We have demonstrated a video transport/switching system over a distance of 40 Km using discrete optical components in our laboratory. We are currently pursuing PIC implementation. In this paper, we will describe the optical CDMA concept/features, the demonstration system, and the requirements of some critical optical components such as broadband optical source, broadband optical amplifier, spectral spreading/de- spreading, and fixed/programmable mask.

  11. Home range and travels

    Science.gov (United States)

    Stickel, L.F.; King, John A.

    1968-01-01

    . Peromyscus generally used and maintained several or many different home sites and refuges in various parts of their home ranges, and frequently shifted about so that their principal activities centered on different sets of holes at different times. Once established, many Peromyscus remained in the same general area for a long time, perhaps for the duration of their lives. Extent of their travels in different directions and intensity of use of different portions of their home ranges varied within a general area in response to habitat changes, loss of neighbors, or other factors. Various authors have obtained both direct and indirect evidence of territoriality, in some degree, among certain species of Peromyscus. Young mice dispersed from their birth sites to establish home ranges of their own. Adults also sometimes left their home areas; some re-established elsewhere; others returned after exploratory travels. Most populations contained a certain proportion of transients; these may have been wanderers or individuals exploring out from established home ranges or seeking new ones. When areas were depopulated by removal trapping, other Peromyscus invaded. Invasion rates generally followed seasonal trends of reproduction and population density. Peromyscus removed from their home areas and released elsewhere returned home from various distances, but fewer returned from greater distances than from nearby; speed of return increased with successive trials. The consensus from present evidence is that ho-ming is made possible by a combination of random wandering and familiarity with a larger area than the day-to-day range. Records of juvenile wanderings during the dispersal phase and of adult explorations very nearly encompassed the distances over which any substantial amount of successful homing occurred. Methods of measuring sizes of home ranges and the limitations of these measurements were discussed in brief synopsis. It was co

  12. Tropospheric Vertical Profiles of Aerosol Optical, Microphysical and Concentration Properties in the Frame of the Hygra-CD Campaign (Athens, Greece 2014: A Case Study of Long-Range Transport of Mixed Aerosols

    Directory of Open Access Journals (Sweden)

    Papayannis Alexandros

    2016-01-01

    Full Text Available Combined multi-wavelength aerosol Raman lidar and sun photometry measurements were performed during the HYGRA-CD campaign over Athens, Greece during May-June 2014. The retrieved aerosol optical properties (3 aerosol backscatter at 355-532-1064 nm and 2 aerosol extinction profiles at 355-532 nm were used as input to an inversion code to retrieve the aerosol microphysical properties (effective radius reff and number concentration N using regularization techniques. Additionally, the volume concentration profile was derived for fine particles using the LIRIC code. In this paper we selected a complex case study of long-range transport of mixed aerosols (biomass burning particles mixed with dust arriving over Athens between 10-12 June 2014 in the 1.5-4 km height. Between 2-3 km height we measured mean lidar ratios (LR ranging from 45 to 58 sr (at 355 and 532 nm, while the Ångström exponent (AE aerosol extinction-related values (355nm/532nm ranged between 0.8-1.3. The retrieved values of reff and N ranged from 0.19±0.07 to 0.22±0.07 μm and 460±230 to 2200±2800 cm-3, respectively. The aerosol linear depolarization ratio (δ at 532 nm was lower than 5-7% (except for the Saharan dust cases, where δ~10-15%.

  13. Accurate Distances to Important Spiral Galaxies: M63, M74, NGC 1291, NGC 4559, NGC 4625, and NGC 5398

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W. [University of Texas at Austin, McDonald Observatory, 2515 Speedway, Stop C1400 Austin, TX 78712 (United States); Skillman, Evan D. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Berg, Danielle [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Kennicutt, Robert, E-mail: kmcquinn@astro.as.utexas.edu [Institute for Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2017-08-01

    Accurate distances are fundamental for interpreting various measured properties of galaxies. Surprisingly, many of the best-studied spiral galaxies in the Local Volume have distance uncertainties that are much larger than can be achieved with modern observation techniques. Using Hubble Space Telescope optical imaging, we use the tip of the red giant branch method to measure the distances to six galaxies that are included in the Spitzer Infrared Nearby Galaxies Survey program and its offspring surveys. The sample includes M63, M74, NGC 1291, NGC 4559, NGC 4625, and NGC 5398. We compare our results with distances reported to these galaxies based on a variety of methods. Depending on the technique, there can be a wide range in published distances, particularly from the Tully–Fisher relation. In addition, differences between the planetary nebular luminosity function and surface brightness fluctuation techniques can vary between galaxies, suggesting inaccuracies that cannot be explained by systematics in the calibrations. Our distances improve upon previous results, as we use a well-calibrated, stable distance indicator, precision photometry in an optimally selected field of view, and a Bayesian maximum likelihood technique that reduces measurement uncertainties.

  14. Optics/Optical Diagnostics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Optics/Optical Diagnostics Laboratory supports graduate instruction in optics, optical and laser diagnostics and electro-optics. The optics laboratory provides...

  15. Distance between images

    Science.gov (United States)

    Gualtieri, J. A.; Le Moigne, J.; Packer, C. V.

    1992-01-01

    Comparing two binary images and assigning a quantitative measure to this comparison finds its purpose in such tasks as image recognition, image compression, and image browsing. This quantitative measurement may be computed by utilizing the Hausdorff distance of the images represented as two-dimensional point sets. In this paper, we review two algorithms that have been proposed to compute this distance, and we present a parallel implementation of one of them on the MasPar parallel processor. We study their complexity and the results obtained by these algorithms for two different types of images: a set of displaced pairs of images of Gaussian densities, and a comparison of a Canny edge image with several edge images from a hierarchical region growing code.

  16. THE EXTRAGALACTIC DISTANCE DATABASE

    International Nuclear Information System (INIS)

    Tully, R. Brent; Courtois, Helene M.; Jacobs, Bradley A.; Rizzi, Luca; Shaya, Edward J.; Makarov, Dmitry I.

    2009-01-01

    A database can be accessed on the Web at http://edd.ifa.hawaii.edu that was developed to promote access to information related to galaxy distances. The database has three functional components. First, tables from many literature sources have been gathered and enhanced with links through a distinct galaxy naming convention. Second, comparisons of results both at the levels of parameters and of techniques have begun and are continuing, leading to increasing homogeneity and consistency of distance measurements. Third, new material is presented arising from ongoing observational programs at the University of Hawaii 2.2 m telescope, radio telescopes at Green Bank, Arecibo, and Parkes and with the Hubble Space Telescope. This new observational material is made available in tandem with related material drawn from archives and passed through common analysis pipelines.

  17. Distance to Cure

    OpenAIRE

    Capachi, Casey

    2013-01-01

    Distance to Cure A three-part television series by Casey Capachi www.distancetocure.com   Abstract   How far would you go for health care? This three-part television series, featuring two introductory segments between each piece, focuses on the physical, cultural, and political obstacles facing rural Native American patients and the potential of health technology to break down those barriers to care.   Part one,Telemedici...

  18. Ultrametric Distance in Syntax

    Directory of Open Access Journals (Sweden)

    Roberts Mark D.

    2015-04-01

    Full Text Available Phrase structure trees have a hierarchical structure. In many subjects, most notably in taxonomy such tree structures have been studied using ultrametrics. Here syntactical hierarchical phrase trees are subject to a similar analysis, which is much simpler as the branching structure is more readily discernible and switched. The ambiguity of which branching height to choose, is resolved by postulating that branching occurs at the lowest height available. An ultrametric produces a measure of the complexity of sentences: presumably the complexity of sentences increases as a language is acquired so that this can be tested. All ultrametric triangles are equilateral or isosceles. Here it is shown that X̅ structure implies that there are no equilateral triangles. Restricting attention to simple syntax a minimum ultrametric distance between lexical categories is calculated. A matrix constructed from this ultrametric distance is shown to be different than the matrix obtained from features. It is shown that the definition of C-COMMAND can be replaced by an equivalent ultrametric definition. The new definition invokes a minimum distance between nodes and this is more aesthetically satisfying than previous varieties of definitions. From the new definition of C-COMMAND follows a new definition of of the central notion in syntax namely GOVERNMENT.

  19. CW all optical self switching in nonlinear chalcogenide nano plasmonic directional coupler

    Science.gov (United States)

    Motamed-Jahromi, Leila; Hatami, Mohsen

    2018-04-01

    In this paper we obtain the coupling coefficient of plasmonic directional coupler (PDC) made up of two parallel monolayer waveguides filled with high nonlinear chalcogenide material for TM mode in continues wave (CW) regime. In addition, we assume each waveguides acts as a perturbation to other waveguide. Four nonlinear-coupled equations are derived. Transfer distances are numerically calculated and used for deriving length of all optical switch. The length of designed switch is in the range of 10-1000 μm, and the switching power is in the range of 1-100 W/m. Obtained values are suitable for designing all optical elements in the integrated optical circuits.

  20. Optical Fibre Bundle

    CERN Multimedia

    These are sample fibre optic cables which are used for networking. Optical fibers are widely used in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. This is useful for somewhere like CERN where magnets with their highly powerful magnetic fields could pose a problem.

  1. An Improved Measurement Method for the Strength of Radiation of Reflective Beam in an Industrial Optical Sensor Based on Laser Displacement Meter

    OpenAIRE

    Youngchul Bae

    2016-01-01

    An optical sensor such as a laser range finder (LRF) or laser displacement meter (LDM) uses reflected and returned laser beam from a target. The optical sensor has been mainly used to measure the distance between a launch position and the target. However, optical sensor based LRF and LDM have numerous and various errors such as statistical errors, drift errors, cyclic errors, alignment errors and slope errors. Among these errors, an alignment error that contains measurement error for the stre...

  2. Optical biosensors.

    Science.gov (United States)

    Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

    2016-06-30

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  3. An overview of Broadband Laser Ranging Architecture and Measurement Considerations

    Science.gov (United States)

    Daykin, Edward; La Lone, Brandon; Miller, Edward; Younk, Patrick; Bennett, Corey; Catenacci, Jared; LLNL BLR Development Group Collaboration; LANL BLR Development Group Collaboration

    2017-06-01

    Broadband Laser Ranging (BLR) is a developmental diagnostic intended to measure the position of rapidly moving surfaces in combination with optical velocimetry. Design and employment of a BLR diagnostic on dynamic experiments requires consideration for both the inherent measurement system tradeoffs as well as architectural choices appropriate to the nature of investigation. The diagnostic uses spectral interferometry to measure distance by mapping femtosecond laser pulses to the time domain via chromatic dispersion within the fiber-optic architecture. The system parameters and governing equations that describe measurement range, resolution, and Doppler sensitivity will be discussed. We will also briefly review the impact of diagnostic architectural choices including: nature of interferometer, Interferometric dispersion matching, optical amplification, integration of optical velocimetry, BLR calibration, and field operability. To summarize we will present the architectural and operational approach currently being pursued by NSTec within an on-going collaboration between NSTec, Lawrence Livermore and Los Alamos National Labs. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.

  4. A VLBI resolution of the Pleiades distance controversy.

    Science.gov (United States)

    Melis, Carl; Reid, Mark J; Mioduszewski, Amy J; Stauffer, John R; Bower, Geoffrey C

    2014-08-29

    Because of its proximity and its youth, the Pleiades open cluster of stars has been extensively studied and serves as a cornerstone for our understanding of the physical properties of young stars. This role is called into question by the "Pleiades distance controversy," wherein the cluster distance of 120.2 ± 1.5 parsecs (pc) as measured by the optical space astrometry mission Hipparcos is significantly different from the distance of 133.5 ± 1.2 pc derived with other techniques. We present an absolute trigonometric parallax distance measurement to the Pleiades cluster that uses very long baseline radio interferometry (VLBI). This distance of 136.2 ± 1.2 pc is the most accurate and precise yet presented for the cluster and is incompatible with the Hipparcos distance determination. Our results cement existing astrophysical models for Pleiades-age stars. Copyright © 2014, American Association for the Advancement of Science.

  5. A simple multipurpose double-beam optical image analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Popowicz, A., E-mail: adam.popowicz@polsl.pl [Institute of Automatic Control, Silesian University of Technology, Akademicka Str. 16, 44-100 Gliwice (Poland); Blachowicz, T. [Institute of Physics - Center for Science and Education, Silesian University of Technology, S. Konarskiego 22B Str., 44-100 Gliwice (Poland)

    2016-07-15

    In the paper we present a low cost optical device which splits the light in the focal plane into two separate optical paths and collimates it back into a single image plane, and where a selective information processing can be carried out. The optical system is straightforward and easily implementable as it consists of only three lenses and two mirrors. The system is dedicated for imaging in low-light-level conditions in which widely used optical devices, based on beam splitters or dichroic mirrors, suffer from light loss. We expose examples of applications of our device, using a prototype model. The proposed optical system may be employed for: monitoring the objects located at different distances from observer (1), creating regions of different magnification within a single image plane (2), high dynamic range photometry (3), or imaging in two wavelength bands simultaneously (4).

  6. Relativistic distances, sizes, lengths

    International Nuclear Information System (INIS)

    Strel'tsov, V.N.

    1992-01-01

    Such notion as light or retarded distance, field size, formation way, visible size of a body, relativistic or radar length and wave length of light from a moving atom are considered. The relation between these notions is cleared up, their classification is given. It is stressed that the formation way is defined by the field size of a moving particle. In the case of the electromagnetic field, longitudinal sizes increase proportionally γ 2 with growing charge velocity (γ is the Lorentz-factor). 18 refs

  7. Distance Metric Tracking

    Science.gov (United States)

    2016-03-02

    whereBψ is any Bregman divergence and ηt is the learning rate parameter. From (Hall & Willett, 2015) we have: Theorem 1. G` = max θ∈Θ,`∈L ‖∇f(θ)‖ φmax = 1...Kullback-Liebler divergence between an initial guess of the matrix that parameterizes the Mahalanobis distance and a solution that satisfies a set of...Bregman divergence and ηt is the learning rate parameter. M̂0, µ̂0 are initialized to some initial value. In [18] a closed-form algorithm for solving

  8. Intra-operative application of optical coherence tomography with an operating microscope.

    Science.gov (United States)

    Just, T; Lankenau, E; Hüttmann, G; Pau, H W

    2009-09-01

    To introduce the use of optical coherence tomography with an operating microscope for intra-operative evaluation of the human larynx. A specially equipped operating microscope with integrated spectral domain optical coherence tomography apparatus was used during microlaryngoscopy. Technical improvements in optical coherence tomography equipment (e.g. pilot beam, variable focal distance, improved image quality and integration into an operating microscope) have enabled greater sensitivity and imaging speed and a non-contact approach. Spectral domain optical coherence tomography now enables a better correlation between optical coherence tomography images and histological findings. With this new technology, the precision of biopsy can be improved during microlaryngoscopy. Use of this new optical coherence tomography technology, integrated into an operating microscope, enables the surgeon to define the biopsy site location and resection plane precisely, while the optical zoom of the operating microscope can be used over the complete range.

  9. Vertical Profiles of Aerosol Optical and Microphysical Properties During a Rare Case of Long-range Transport of Mixed Biomass Burning-polluted Dust Aerosols from the Russian Federation-kazakhstan to Athens, Greece

    Directory of Open Access Journals (Sweden)

    Papayannis Alexandros

    2016-01-01

    Full Text Available Multi-wavelength aerosol Raman lidar measurements with elastic depolarization at 532 nm were combined with sun photometry during the HYGRA-CD campaign over Athens, Greece, on May-June 2014. We retrieved the aerosol optical [3 aerosol backscatter profiles (baer at 355-532-1064 nm, 2 aerosol extinction (aaer profiles at 355-532 nm and the aerosol linear depolarization ratio (δ at 532 nm] and microphysical properties [effective radius (reff, complex refractive index (m, single scattering albedo (ω]. We present a case study of a long distance transport (~3.500-4.000 km of biomass burning particles mixed with dust from the Russian Federation-Kazakhstan regions arriving over Athens on 21-23 May 2014 (1.7-3.5 km height. On 23 May, between 2-2.75 km we measured mean lidar ratios (LR of 35 sr (355 nm and 42 sr (532 nm, while the mean Ångström exponent (AE aerosol backscatter-related values (355nm/532nm and 532nm/1064nm were 2.05 and 1.22, respectively; the mean value of δ at 532 nm was measured to be 9%. For that day the retrieved mean aerosol microphysical properties at 2-2.75 km height were: reff=0.26 μm (fine mode, reff=2.15 μm (coarse mode, m=1.36+0.00024i, ω=0.999 (355 nm, fine mode, ω=0.992(355 nm, coarse mode, ω=0.997 (532 nm, fine mode, and ω=0.980 (532 nm, coarse mode.

  10. PERBANDINGAN EUCLIDEAN DISTANCE DENGAN CANBERRA DISTANCE PADA FACE RECOGNITION

    Directory of Open Access Journals (Sweden)

    Sendhy Rachmat Wurdianarto

    2014-08-01

    Full Text Available Perkembangan ilmu pada dunia komputer sangatlah pesat. Salah satu yang menandai hal ini adalah ilmu komputer telah merambah pada dunia biometrik. Arti biometrik sendiri adalah karakter-karakter manusia yang dapat digunakan untuk membedakan antara orang yang satu dengan yang lainnya. Salah satu pemanfaatan karakter / organ tubuh pada setiap manusia yang digunakan untuk identifikasi (pengenalan adalah dengan memanfaatkan wajah. Dari permasalahan diatas dalam pengenalan lebih tentang aplikasi Matlab pada Face Recognation menggunakan metode Euclidean Distance dan Canberra Distance. Model pengembangan aplikasi yang digunakan adalah model waterfall. Model waterfall beriisi rangkaian aktivitas proses yang disajikan dalam proses analisa kebutuhan, desain menggunakan UML (Unified Modeling Language, inputan objek gambar diproses menggunakan Euclidean Distance dan Canberra Distance. Kesimpulan yang dapat ditarik adalah aplikasi face Recognation menggunakan metode euclidean Distance dan Canverra Distance terdapat kelebihan dan kekurangan masing-masing. Untuk kedepannya aplikasi tersebut dapat dikembangkan dengan menggunakan objek berupa video ataupun objek lainnya.   Kata kunci : Euclidean Distance, Face Recognition, Biometrik, Canberra Distance

  11. Distance collaborations with industry

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, A.; Swyler, K.

    1998-06-01

    The college industry relationship has been identified as a key policy issue in Engineering Education. Collaborations between academic institutions and the industrial sector have a long history and a bright future. For Engineering and Engineering Technology programs in particular, industry has played a crucial role in many areas including advisement, financial support, and practical training of both faculty and students. Among the most important and intimate interactions are collaborative projects and formal cooperative education arrangements. Most recently, such collaborations have taken on a new dimension, as advances in technology have made possible meaningful technical collaboration at a distance. There are several obvious technology areas that have contributed significantly to this trend. Foremost is the ubiquitous presence of the Internet. Perhaps almost as important are advances in computer based imaging. Because visual images offer a compelling user experience, it affords greater knowledge transfer efficiency than other modes of delivery. Furthermore, the quality of the image appears to have a strongly correlated effect on insight. A good visualization facility offers both a means for communication and a shared information space for the subjects, which are among the essential features of both peer collaboration and distance learning.

  12. Distance Measurement Solves Astrophysical Mysteries

    Science.gov (United States)

    2003-08-01

    distance. "Our measurements showed that the pulsar is about 950 light-years from Earth, essentially the same distance as the supernova remnant," said Steve Thorsett, of the University of California, Santa Cruz. "That means that the two almost certainly were created by the same supernova blast," he added. With that problem solved. the astronomers then turned to studying the pulsar's neutron star itself. Using a variety of data from different telescopes and armed with the new distance measurement, they determined that the neutron star is between 16 and 25 miles in diameter. In such a small size, it packs a mass roughly equal to that of the Sun. The next result of learning the pulsar's actual distance was to provide a possible answer to a longstanding question about cosmic rays. Cosmic rays are subatomic particles or atomic nuclei accelerated to nearly the speed of light. Shock waves in supernova remnants are thought to be responsible for accelerating many of these particles. Scientists can measure the energy of cosmic rays, and had noted an excess of such rays in a specific energy range. Some researchers had suggested that the excess could come from a single supernova remnant about 1000 light-years away whose supernova explosion was about 100,000 years ago. The principal difficulty with this suggestion was that there was no accepted candidate for such a source. "Our measurement now puts PSR B0656+14 and the Monogem Ring at exactly the right place and at exactly the right age to be the source of this excess of cosmic rays," Brisken said. With the ability of the VLBA, one of the telescopes of the NRAO, to make extremely precise position measurements, the astronomers expect to improve the accuracy of their distance determination even more. "This pulsar is becoming a fascinating laboratory for studying astrophysics and nuclear physics," Thorsett said. In addition to Brisken and Thorsett, the team of astronomers includes Aaron Golden of the National University of Ireland, Robert

  13. Long-range hybrid ridge and trench plasmonic waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Yusheng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Gong, Qihuang, E-mail: qhgong@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China)

    2014-06-23

    We report a class of long-range hybrid plasmon polariton waveguides capable of simultaneously achieving low propagation loss and tight field localization at telecommunication wavelength. The symmetric (quasi-symmetric) hybrid configurations featuring high-refractive-index-contrast near the non-uniform metallic nanostructures enable significantly improved optical performance over conventional hybrid waveguides, exhibiting considerably longer propagation distances and dramatically enhanced figure of merits for similar degrees of confinement. Compared to their traditional long-range plasmonic counterparts, the proposed hybrid waveguides put much less stringent requirements on index-matching conditions, demonstrating nice performance under a wide range of physical dimensions and robust characteristics against certain fabrication imperfections. Studies concerning crosstalk between adjacent identical waveguides further reveal their potential for photonic integrations. In addition, alternative configurations with comparable guiding properties to the structures in our case studies are also proposed, which can potentially serve as attractive prototypes for numerous high-performance nanophotonic components.

  14. Distance covariance for stochastic processes

    DEFF Research Database (Denmark)

    Matsui, Muneya; Mikosch, Thomas Valentin; Samorodnitsky, Gennady

    2017-01-01

    The distance covariance of two random vectors is a measure of their dependence. The empirical distance covariance and correlation can be used as statistical tools for testing whether two random vectors are independent. We propose an analog of the distance covariance for two stochastic processes...

  15. DISTANCES TO DARK CLOUDS: COMPARING EXTINCTION DISTANCES TO MASER PARALLAX DISTANCES

    International Nuclear Information System (INIS)

    Foster, Jonathan B.; Jackson, James M.; Stead, Joseph J.; Hoare, Melvin G.; Benjamin, Robert A.

    2012-01-01

    We test two different methods of using near-infrared extinction to estimate distances to dark clouds in the first quadrant of the Galaxy using large near-infrared (Two Micron All Sky Survey and UKIRT Infrared Deep Sky Survey) surveys. Very long baseline interferometry parallax measurements of masers around massive young stars provide the most direct and bias-free measurement of the distance to these dark clouds. We compare the extinction distance estimates to these maser parallax distances. We also compare these distances to kinematic distances, including recent re-calibrations of the Galactic rotation curve. The extinction distance methods agree with the maser parallax distances (within the errors) between 66% and 100% of the time (depending on method and input survey) and between 85% and 100% of the time outside of the crowded Galactic center. Although the sample size is small, extinction distance methods reproduce maser parallax distances better than kinematic distances; furthermore, extinction distance methods do not suffer from the kinematic distance ambiguity. This validation gives us confidence that these extinction methods may be extended to additional dark clouds where maser parallaxes are not available.

  16. Coherent dual-frequency lidar system design for distance and speed measurements

    Science.gov (United States)

    Zheng, Xingyuan; Zhao, Changming; Zhang, Haiyang; Zheng, Zheng; Yang, Hongzhi

    2018-01-01

    Lidars have a wide range of applications in military detection and civilian remote sensing. Coherent Dual-Frequency Lidar (CDFL) is a new concept of laser radar that is using electrical coherence instead of optical coherence. It uses laser with two coherent frequency components as transmitting wave. The method is based on the use of an optically-carried radio frequency (RF) signal, which is the frequency difference between the two components, which is specially designed for distance and speed measurements. It not only ensures the system has the characteristics of high spatial resolution, high ranging and velocity precision of laser radar, but also can use mature signal processing technology of microwave radar, and it is a research direction that attracts more concern in recent years. A CDFL detection system is constructed and field experiment is carried out. In the system, a narrow linewidth fiber laser with a wavelength of 1064nm is adopted. The dual-frequency laser with frequency difference of 200MHz and 200.6MHz is obtained by acousto-optic frequency shift and recombination. The maximum output power of dual frequency laser is 200mW. The receiver consists of all-fiber balanced InGaAs photo-detector and homemade analog signal processing board. The experimental results show that the distance resolution and velocity resolution of the system are 0.1m and 0.1m/s separately when the working distance is greater than 200m, and the spatial resolution is 0.5mrad.

  17. Optical Axis Identification Technique for Free Space Optics Transmission

    Directory of Open Access Journals (Sweden)

    Yuki Tashiro

    2017-07-01

    Full Text Available This paper describes optical axis adjustment technique for an active free space optics transmission system. This system precisely controls the direction of a collimated thin laser beam using a motor driven laser emitting mechanism and positioning photodiodes. Before beginning laser beam feedback control, it is required to guide the laser beam within the range of the positioning photodiodes for initial laser beam alignment. This paper proposes an arrival position presumption method of laser beam traveling along the long distance from transmitter. A positioning sensor containing several photodiodes measures laser luminescence distribution, and analytically calculates the optical axis of laser beam according to the modified Gaussian beam optics based on four or five distributed local intensity of laser luminescence. Experiments are conducted to evaluate the accuracy of the presumption, and results reveal that the method is effective in leading the laser beam onto a distant receiver.

  18. Radio Astronomers Set New Standard for Accurate Cosmic Distance Measurement

    Science.gov (United States)

    1999-06-01

    calibrating the size of the Solar System. The first accurate distance to another star was determined trigonometrically by Friedrich Wilhelm Bessel in 1838. Traditional trigonometric methods of measuring celestial distances require extremely accurate measurement of an object's position in the sky. By measuring the apparent shift in an object's position, called parallax, caused by the Earth's journey around the Sun, the distance to the object can be calculated. Until recent years, such measurements were limited by the atmosphere's degrading effect on optical observations. Recently, the Hipparcos satellite has measured stellar distances accurate to within 10 percent out to about 300 light-years. Beyond the range of parallax measurements, astronomers were forced to use indirect methods of estimating distances. Many of these methods make presumptions about the intrinsic brightness of objects, then estimate the distance by measuring how much fainter they appear on Earth. The faintness is presumed to be caused by the distance, according to the inverse-square law (doubling of the distance reduces brightness by a factor of four). Thus, stars of a particular spectral class are all presumed to be of the same intrinsic brightness. Such techniques have been used to estimate distances of stars out to about 25,000 light-years, still not far enough to estimate distance beyond our own Milky Way Galaxy. Early in the 20th Century, Henrietta Leavitt, of Harvard College Observatory, discovered that variable-brightness stars known as Cepheid variables showed a useful property -- the longer their pulsation periods, the brighter they are intrinsically. Once the absolute distance to a few Cepheids was determined, these stars were used to measure distances beyond the Milky Way. In the 1920s, Edwin Hubble used Cepheid-variable distance determinations to show that, contrary to then-prevalent opinion, many "nebulae" were, in fact, other galaxies far distant from our own. Distances determined using

  19. Optical XOR gate

    Science.gov (United States)

    Vawter, G. Allen

    2013-11-12

    An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

  20. Optical-to-Tactile Translator

    Science.gov (United States)

    Langevin, Maurice L. (Inventor); Moynihan, Philip I. (Inventor)

    2000-01-01

    An optical-to-tactile translator provides an aid for the visually impaired by translating a near-field scene to a tactile signal corresponding to said near-field scene. An optical sensor using a plurality of active pixel sensors (APS) converts the optical image within the near-field scene to a digital signal. The digital signal is then processed by a microprocessor and a simple shape signal is generated based on the digital signal. The shape signal is then communicated to a tactile transmitter where the shape signal is converted into a tactile signal using a series of contacts. The shape signal may be an outline of the significant shapes determined in the near-field scene, or the shape signal may comprise a simple symbolic representation of common items encountered repeatedly. The user is thus made aware of the unseen near-field scene, including potential obstacles and dangers, through a series of tactile contacts. In a preferred embodiment, a range determining device such as those commonly found on auto-focusing cameras is included to limit the distance that the optical sensor interprets the near-field scene.

  1. Radiative charge transfer in He{sup +}+ H{sub 2} collisions in the milli- to nano-electron-volt range: A theoretical study within state-to-state and optical potential approaches

    Energy Technology Data Exchange (ETDEWEB)

    Mrugala, Felicja [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, PL 87-100 Torun (Poland); Kraemer, Wolfgang P. [Max-Planck-Institute of Astrophysics, Postfach 1317, D-85741 Garching (Germany)

    2013-03-14

    The paper presents a theoretical study of the low-energy dynamics of the radiative charge transfer (RCT) reaction He{sup +}({sup 2}S)+H{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}){yields}He({sup 1}S)+H{sub 2}{sup +}(X{sup 2}{Sigma}{sub g}{sup +})+h{nu} extending our previous studies on radiative association of HeH{sub 2}{sup +} [F. Mrugala, V. Spirko, and W. P. Kraemer, J. Chem. Phys. 118, 10547 (2003); F. Mrugala and W. P. Kraemer, ibid. 122, 224321 (2005)]. The calculations account for the vibrational and rotational motions of the H{sub 2}/H{sub 2}{sup +} diatomics and for the atom-diatom complex formation in the reactant and the product channels of the RCT reaction. Continuum states of He{sup +}+ H{sub 2}(v= 0, j= 0) in the collision energy range {approx}10{sup -7}-18.6 meV and all quasi-bound states of the He{sup +}- H{sub 2}(para;v= 0) complex formed in this range are taken into account. Close-coupling calculations are performed to determine rates of radiative transitions from these states to the continuum and quasi-bound states of the He +H{sub 2}{sup +} system in the energy range extending up to {approx}0.16 eV above the opening of the HeH{sup +}+ H arrangement channel. From the detailed state-to-state calculated characteristics global functions of the RCT reaction, such as cross-section {sigma}(E), emission intensity I({nu}, T), and rate constant k(T) are derived, and are presented together with their counterparts for the radiative association (RA) reaction He{sup +}({sup 2}S) +H{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}){yields} HeH{sub 2}{sup +}(X{sup 2}A{sup Prime })+h{nu}. The rate constant k{sup RCT} is approximately 20 times larger than k{sup RA} at the considered temperatures, 0.1 {mu}K-50 K. Formation of rotational Feshbach resonances in the reactant channel plays an important role in both reactions. Transitions mediated by these resonances contribute more than 70% to the respective rates. An extension of the one-dimensional optical potential model is

  2. Galaxies Gather at Great Distances

    Science.gov (United States)

    2006-01-01

    [figure removed for brevity, see original site] Distant Galaxy Cluster Infrared Survey Poster [figure removed for brevity, see original site] [figure removed for brevity, see original site] Bird's Eye View Mosaic Bird's Eye View Mosaic with Clusters [figure removed for brevity, see original site] [figure removed for brevity, see original site] [figure removed for brevity, see original site] 9.1 Billion Light-Years 8.7 Billion Light-Years 8.6 Billion Light-Years Astronomers have discovered nearly 300 galaxy clusters and groups, including almost 100 located 8 to 10 billion light-years away, using the space-based Spitzer Space Telescope and the ground-based Mayall 4-meter telescope at Kitt Peak National Observatory in Tucson, Ariz. The new sample represents a six-fold increase in the number of known galaxy clusters and groups at such extreme distances, and will allow astronomers to systematically study massive galaxies two-thirds of the way back to the Big Bang. A mosaic portraying a bird's eye view of the field in which the distant clusters were found is shown at upper left. It spans a region of sky 40 times larger than that covered by the full moon as seen from Earth. Thousands of individual images from Spitzer's infrared array camera instrument were stitched together to create this mosaic. The distant clusters are marked with orange dots. Close-up images of three of the distant galaxy clusters are shown in the adjoining panels. The clusters appear as a concentration of red dots near the center of each image. These images reveal the galaxies as they were over 8 billion years ago, since that's how long their light took to reach Earth and Spitzer's infrared eyes. These pictures are false-color composites, combining ground-based optical images captured by the Mosaic-I camera on the Mayall 4-meter telescope at Kitt Peak, with infrared pictures taken by Spitzer's infrared array camera. Blue and green represent visible light at wavelengths of 0.4 microns and 0.8 microns

  3. Planning with Reachable Distances

    KAUST Repository

    Tang, Xinyu

    2009-01-01

    Motion planning for spatially constrained robots is difficult due to additional constraints placed on the robot, such as closure constraints for closed chains or requirements on end effector placement for articulated linkages. It is usually computationally too expensive to apply sampling-based planners to these problems since it is difficult to generate valid configurations. We overcome this challenge by redefining the robot\\'s degrees of freedom and constraints into a new set of parameters, called reachable distance space (RD-space), in which all configurations lie in the set of constraint-satisfying subspaces. This enables us to directly sample the constrained subspaces with complexity linear in the robot\\'s number of degrees of freedom. In addition to supporting efficient sampling, we show that the RD-space formulation naturally supports planning, and in particular, we design a local planner suitable for use by sampling-based planners. We demonstrate the effectiveness and efficiency of our approach for several systems including closed chain planning with multiple loops, restricted end effector sampling, and on-line planning for drawing/sculpting. We can sample single-loop closed chain systems with 1000 links in time comparable to open chain sampling, and we can generate samples for 1000-link multi-loop systems of varying topology in less than a second. © 2009 Springer-Verlag.

  4. Femtosecond frequency comb based distance measurement in air.

    Science.gov (United States)

    Balling, Petr; Kren, Petr; Masika, Pavel; van den Berg, S A

    2009-05-25

    Interferometric measurement of distance using a femtosecond frequency comb is demonstrated and compared with a counting interferometer displacement measurement. A numerical model of pulse propagation in air is developed and the results are compared with experimental data for short distances. The relative agreement for distance measurement in known laboratory conditions is better than 10(-7). According to the model, similar precision seems feasible even for long-distance measurement in air if conditions are sufficiently known. It is demonstrated that the relative width of the interferogram envelope even decreases with the measured length, and a fringe contrast higher than 90% could be obtained for kilometer distances in air, if optimal spectral width for that length and wavelength is used. The possibility of comb radiation delivery to the interferometer by an optical fiber is shown by model and experiment, which is important from a practical point of view.

  5. Managing the distance equation

    NARCIS (Netherlands)

    Williams, C.

    2008-01-01

    Offshore outsourcing continues to gather pace. Offshore outsourcing vendors have matured over recent years in terms of sophistication in the range of services offered to clients, as well as in their ability to offer innovative solutions on top of cost savings. Christopher Williams looks at whether

  6. A 10 Mbyte/s fiber optic link

    International Nuclear Information System (INIS)

    Brodier-Yourstone, P.; McCulloch, L.; McLaren, R.A.

    1995-01-01

    This paper presents a fiber optic link (FOL) that has been developed for the NA48 experiment at CERN. About 15 FOLs will be used to transfer event data to the Data Merger (event builder) over a distance of 200 meters. The FOL has a very simple interface and is capable of transmitting data at a rate of over 10 Mbyte/s while performing error detection. The optical part of the FOL uses industry standard components. This, combined with its simplicity of use, makes the FOL suitable to be reused in a wide range of applications, which is shown by its use outside the NA48 experiment

  7. Optical materials

    International Nuclear Information System (INIS)

    Poker, D.B.; Ortiz, C.

    1989-01-01

    This book reports on: Diamond films, Synthesis of optical materials, Structure related optical properties, Radiation effects in optical materials, Characterization of optical materials, Deposition of optical thin films, and Optical fibers and waveguides

  8. Optical pH Sensor Covering the Range from pH 0-14 Compatible with Mobile-Device Readout and Based on a Set of Rationally Designed Indicator Dyes.

    Science.gov (United States)

    Gotor, Raúl; Ashokkumar, Pichandi; Hecht, Mandy; Keil, Karin; Rurack, Knut

    2017-08-15

    In this work, a family of pH-responsive fluorescent probes has been designed in a rational manner with the aid of quantum chemistry tools, covering the entire pH range from 0-14. Relying on the boron-dipyrromethene (BODIPY) core, all the probes as well as selected reference dyes display very similar spectroscopic properties with ON-OFF fluorescence switching responses, facilitating optical readout in simple devices used for detection and analysis. Embedding of the probes and reference dyes into hydrogel spots on a plastic strip yielded a test strip that reversibly indicates pH with a considerably small uncertainty of ∼0.1 pH units. These strips are not only reusable but, combined with a 3D-printed case that can be attached to a smartphone, the USB port of which drives the integrated LED used for excitation, allows for autonomous operation in on-site or in-the-field applications; the developed Android application software ("app") further simplifies operation for unskilled users.

  9. Are contemporary tourists consuming distance?

    DEFF Research Database (Denmark)

    Larsen, Gunvor Riber

    2012. Background The background for this research, which explores how tourists represent distance and whether or not distance can be said to be consumed by contemporary tourists, is the increasing leisure mobility of people. Travelling for the purpose of visiting friends and relatives is increasing...... of understanding mobility at a conceptual level, and distance matters to people's manifest mobility: how they travel and how far they travel are central elements of their movements. Therefore leisure mobility (indeed all mobility) is the activity of relating across distance, either through actual corporeal...... metric representation. These representations are the focus for this research. Research Aim and Questions The aim of this research is thus to explore how distance is being represented within the context of leisure mobility. Further the aim is to explore how or whether distance is being consumed...

  10. Distance : between deixis and perspectivity

    OpenAIRE

    Meermann, Anastasia; Sonnenhauser, Barbara

    2015-01-01

    Discussing exemplary applications of the notion of distance in linguistic analysis, this paper shows that very different phenomena are described in terms of this concept. It is argued that in order to overcome the problems arising from this mixup, deixis, distance and perspectivity have to be distinguished and their interrelations need to be described. Thereby, distance emerges as part of a recursive process mediating between situation-bound deixis and discourse-level perspectivity. This is i...

  11. Modeling and analysis of laser active interference optical path

    Science.gov (United States)

    Shan, Cong-miao; Sun, Hua-yan; Zhao, Yan-zhong; Chen, Jian-biao; Ren, Jian-ying

    2017-10-01

    By using the geometrical optics and physical optics method, the models of wedge plate interference optical path, Michelson interferometer and Mach Zehnder interferometer thus three different active interference pattern are built. The optical path difference (OPD) launched by different interference patterns, fringe spacing and contrast expression have been derived. The results show that far field interference peak intensity of the wedge plate interference is small, so the detection distance is limited, Michelson interferometer with low contrast affects the performance of detection system, Mach Zehnder interferometer has greater advantages in peak intensity, the variable range of interference fringe spacing and contrast ratio. The results of this study are useful for the theoretical research and practical application of laser active interference detection.

  12. High-energy nuclear optics of polarized particles

    CERN Document Server

    Baryshevsky, Vladimir G

    2012-01-01

    The various phenomena caused by refraction and diffraction of polarized elementary particles in matter have opened up a new research area in the particle physics: nuclear optics of polarized particles. Effects similar to the well-known optical phenomena such as birefringence and Faraday effects, exist also in particle physics, though the particle wavelength is much less than the distance between atoms of matter. Current knowledge of the quasi-optical effects, which exist for all particles in any wavelength range (and energies from low to extremely high), will enable us to investigate different properties of interacting particles (nuclei) in a new aspect. This pioneering book will provide detailed accounts of quasi-optical phenomena in the particle polarization, and will interest physicists and professionals in experimental particle physics.

  13. Distance to VY Canis Majoris with VERA

    Science.gov (United States)

    Choi, Yoon Kyung; Hirota, Tomoya; Honma, Mareki; Kobayashi, Hideyuki; Bushimata, Takeshi; Imai, Hiroshi; Iwadate, Kenzaburo; Jike, Takaaki; Kameno, Seiji; Kameya, Osamu; Kamohara, Ryuichi; Kan-Ya, Yukitoshi; Kawaguchi, Noriyuki; Kijima, Masachika; Kim, Mi Kyoung; Kuji, Seisuke; Kurayama, Tomoharu; Manabe, Seiji; Maruyama, Kenta; Matsui, Makoto; Matsumoto, Naoko; Miyaji, Takeshi; Nagayama, Takumi; Nakagawa, Akiharu; Nakamura, Kayoko; Oh, Chung Sik; Omodaka, Toshihiro; Oyama, Tomoaki; Sakai, Satoshi; Sasao, Tetsuo; Sato, Katsuhisa; Sato, Mayumi; Shibata, Katsunori M.; Tamura, Yoshiaki; Tsushima, Miyuki; Yamashita, Kazuyoshi

    2008-10-01

    We report on astrometric observations of H2O masers around the red supergiant VY Canis Majoris carried out with VLBI Exploration of Radio Astrometry (VERA). Based on astrometric monitoring for 13 months, we successfully measured a trigonometric parallax of 0.88±0.08 mas, corresponding to a distance of 1.14+0.11-0.09kpc. This is the most accurate determined distance to VY CMa and the first one based on an annual parallax measurement. The luminosity of VY CMa has been overestimated due to a previously accepted distance. With our result, we re-estimated the luminosity of VY CMa to be (3±0.5) × 105Lodot using the bolometric flux integrated over optical and IR wavelengths. This improved luminosity value makes the location of VY CMa on the Hertzsprung-Russell (HR) diagram much closer to the theoretically allowable zone (i.e. the left side of the Hayashi track) than previous ones, though the uncertainty in the effective temperature of the stellar surface still does not permit us to make a final conclusion.

  14. On Normalized Compression Distance and Large Malware

    OpenAIRE

    Borbely, Rebecca Schuller

    2015-01-01

    Normalized Compression Distance (NCD) is a popular tool that uses compression algorithms to cluster and classify data in a wide range of applications. Existing discussions of NCD's theoretical merit rely on certain theoretical properties of compression algorithms. However, we demonstrate that many popular compression algorithms don't seem to satisfy these theoretical properties. We explore the relationship between some of these properties and file size, demonstrating that this theoretical pro...

  15. Vergence, Vision, and Geometric Optics

    Science.gov (United States)

    Keating, Michael P.

    1975-01-01

    Provides a definition of vergence in terms of the curvature of the wave fronts, and gives examples to illustrate the advantages of this approach. The vergence treatment of geometrical optics provides both conceptual and algebraic advantages, particularly for the life science student, over the traditional object distance-image distance-focal length…

  16. Distance criterion for hydrogen bond

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Distance criterion for hydrogen bond. In a D-H ...A contact, the D...A distance must be less than the sum of van der Waals Radii of the D and A atoms, for it to be a hydrogen bond.

  17. Social Distance and Intergenerational Relations

    Science.gov (United States)

    Kidwell, I. Jane; Booth, Alan

    1977-01-01

    Questionnaires were administered to a sample of adults to assess the extent of social distance between people of different ages. The findings suggest that the greater the age difference (younger or older) between people, the greater the social distance they feel. (Author)

  18. Quality Content in Distance Education

    Science.gov (United States)

    Yildiz, Ezgi Pelin; Isman, Aytekin

    2016-01-01

    In parallel with technological advances in today's world of education activities can be conducted without the constraints of time and space. One of the most important of these activities is distance education. The success of the distance education is possible with content quality. The proliferation of e-learning environment has brought a need for…

  19. Virtual Bioinformatics Distance Learning Suite

    Science.gov (United States)

    Tolvanen, Martti; Vihinen, Mauno

    2004-01-01

    Distance learning as a computer-aided concept allows students to take courses from anywhere at any time. In bioinformatics, computers are needed to collect, store, process, and analyze massive amounts of biological and biomedical data. We have applied the concept of distance learning in virtual bioinformatics to provide university course material…

  20. The Psychology of Psychic Distance

    DEFF Research Database (Denmark)

    Håkanson, Lars; Ambos, Björn; Schuster, Anja

    2016-01-01

    and their theoretical underpinnings assume psychic distances to be symmetric. Building on insights from psychology and sociology, this paper demonstrates how national factors and cognitive processes interact in the formation of asymmetric distance perceptions. The results suggest that exposure to other countries...

  1. Cognitive Styles and Distance Education.

    Science.gov (United States)

    Liu, Yuliang; Ginther, Dean

    1999-01-01

    Considers how to adapt the design of distance education to students' cognitive styles. Discusses cognitive styles, including field dependence versus independence, holistic-analytic, sensory preference, hemispheric preferences, and Kolb's Learning Style Model; and the characteristics of distance education, including technology. (Contains 92…

  2. Distance Learning: Practice and Dilemmas

    Science.gov (United States)

    Tatkovic, Nevenka; Sehanovic, Jusuf; Ruzic, Maja

    2006-01-01

    In accordance with the European processes of integrated and homogeneous education, the paper presents the essential viewpoints and questions covering the establishment and development of "distance learning" (DL) in Republic of Croatia. It starts from the advantages of distance learning versus traditional education taking into account…

  3. Optical Performance Monitoring and Signal Optimization in Optical Networks

    DEFF Research Database (Denmark)

    Petersen, Martin Nordal

    2006-01-01

    The thesis studies performance monitoring for the next generation optical networks. The focus is on all-optical networks with bit-rates of 10 Gb/s or above. Next generation all-optical networks offer large challenges as the optical transmitted distance increases and the occurrence of electrical-optical......-electrical regeneration points decreases. This thesis evaluates the impact of signal degrading effects that are becoming of increasing concern in all-optical high-speed networks due to all-optical switching and higher bit-rates. Especially group-velocity-dispersion (GVD) and a number of nonlinear effects will require...... enhanced attention to avoid signal degradations. The requirements for optical performance monitoring features are discussed, and the thesis evaluates the advantages and necessity of increasing the level of performance monitoring parameters in the physical layer. In particular, methods for optical...

  4. TOPSIS with statistical distances: A new approach to MADM

    Directory of Open Access Journals (Sweden)

    Vijaya Babu Vommi

    2017-01-01

    Full Text Available Multiple attribute decision making (MADM methods are very useful in choosing the best alternative among the available finite but conflicting alternatives. TOPSIS is one of the MADM methods, which is simple in its methodology and logic. In TOPSIS, Euclidean distances of each alternative from the positive and negative ideal solutions are utilized to find the best alternative. In literature, apart from Euclidean distances, the city block distances have also been tried to find the separations measures. In general, the attribute data are distributed with unequal ranges and also possess moderate to high correlations. Hence, in the present paper, use of statistical distances is proposed in place of Euclidean distances. Procedures to find the best alternatives are developed using statistical and weighted statistical distances respectively. The proposed methods are illustrated with some industrial problems taken from literature. Results show that the proposed methods can be used as new alternatives in MADM for choosing the best solutions.

  5. Ranging Behaviour of Commercial Free-Range Laying Hens.

    Science.gov (United States)

    Chielo, Leonard Ikenna; Pike, Tom; Cooper, Jonathan

    2016-04-26

    In this study, the range use and behaviour of laying hens in commercial free-range flocks was explored. Six flocks were each visited on four separate days and data collected from their outdoor area (divided into zones based on distance from shed and available resources). These were: apron (0-10 m from shed normally without cover or other enrichments); enriched belt (10-50 m from shed where resources such as manmade cover, saplings and dust baths were provided); and outer range (beyond 50 m from shed with no cover and mainly grass pasture). Data collection consisted of counting the number of hens in each zone and recording behaviour, feather condition and nearest neighbour distance (NND) of 20 birds per zone on each visit day. In addition, we used techniques derived from ecological surveys to establish four transects perpendicular to the shed, running through the apron, enriched belt and outer range. Number of hens in each 10 m × 10 m quadrat was recorded four times per day as was the temperature and relative humidity of the outer range. On average, 12.5% of hens were found outside. Of these, 5.4% were found in the apron; 4.3% in the enriched zone; and 2.8% were in the outer range. This pattern was supported by data from quadrats, where the density of hens sharply dropped with increasing distance from shed. Consequently, NND was greatest in the outer range, least in the apron and intermediate in the enriched belt. Hens sampled in outer range and enriched belts had better feather condition than those from the apron. Standing, ground pecking, walking and foraging were the most commonly recorded activities with standing and pecking most likely to occur in the apron, and walking and foraging more common in the outer range. Use of the outer range declined with lower temperatures and increasing relative humidity, though use of apron and enriched belt was not affected by variation in these measures. These data support previous findings that outer range areas tend to be

  6. Ranging Behaviour of Commercial Free-Range Laying Hens

    Directory of Open Access Journals (Sweden)

    Leonard Ikenna Chielo

    2016-04-01

    Full Text Available In this study, the range use and behaviour of laying hens in commercial free-range flocks was explored. Six flocks were each visited on four separate days and data collected from their outdoor area (divided into zones based on distance from shed and available resources. These were: apron (0–10 m from shed normally without cover or other enrichments; enriched belt (10–50 m from shed where resources such as manmade cover, saplings and dust baths were provided; and outer range (beyond 50 m from shed with no cover and mainly grass pasture. Data collection consisted of counting the number of hens in each zone and recording behaviour, feather condition and nearest neighbour distance (NND of 20 birds per zone on each visit day. In addition, we used techniques derived from ecological surveys to establish four transects perpendicular to the shed, running through the apron, enriched belt and outer range. Number of hens in each 10 m × 10 m quadrat was recorded four times per day as was the temperature and relative humidity of the outer range. On average, 12.5% of hens were found outside. Of these, 5.4% were found in the apron; 4.3% in the enriched zone; and 2.8% were in the outer range. This pattern was supported by data from quadrats, where the density of hens sharply dropped with increasing distance from shed. Consequently, NND was greatest in the outer range, least in the apron and intermediate in the enriched belt. Hens sampled in outer range and enriched belts had better feather condition than those from the apron. Standing, ground pecking, walking and foraging were the most commonly recorded activities with standing and pecking most likely to occur in the apron, and walking and foraging more common in the outer range. Use of the outer range declined with lower temperatures and increasing relative humidity, though use of apron and enriched belt was not affected by variation in these measures. These data support previous findings that outer range

  7. Optical Spectroscopy

    DEFF Research Database (Denmark)

    Thyrhaug, Erling

    The work presented in this thesis is broadly concerned with how complexation reactions and molecular motion can be characterized with the standard techniques in optical spectroscopy. The thesis aims to show a relatively broad range of methods for probing physico-chemical properties in fluorophore...... information about chemical equilibria, kinetics and molecular motion by monitoring changes in optical properties of the system. The five presented research projects are largely unrelated to each other both in aim and in what property is probed, however they are all connected in that they are fluorophore...... reactions by optical spectroscopy. In project 1 simple steady-state absorption and fluorescence spectroscopy is used to determine the stoichiometries and equilibrium constants in the inclusion complex formation between cyclodextrins and derivatives of the water-insoluble oligo(phenylene vinylene) in aqueous...

  8. MEDOF - MINIMUM EUCLIDEAN DISTANCE OPTIMAL FILTER

    Science.gov (United States)

    Barton, R. S.

    1994-01-01

    The Minimum Euclidean Distance Optimal Filter program, MEDOF, generates filters for use in optical correlators. The algorithm implemented in MEDOF follows theory put forth by Richard D. Juday of NASA/JSC. This program analytically optimizes filters on arbitrary spatial light modulators such as coupled, binary, full complex, and fractional 2pi phase. MEDOF optimizes these modulators on a number of metrics including: correlation peak intensity at the origin for the centered appearance of the reference image in the input plane, signal to noise ratio including the correlation detector noise as well as the colored additive input noise, peak to correlation energy defined as the fraction of the signal energy passed by the filter that shows up in the correlation spot, and the peak to total energy which is a generalization of PCE that adds the passed colored input noise to the input image's passed energy. The user of MEDOF supplies the functions that describe the following quantities: 1) the reference signal, 2) the realizable complex encodings of both the input and filter SLM, 3) the noise model, possibly colored, as it adds at the reference image and at the correlation detection plane, and 4) the metric to analyze, here taken to be one of the analytical ones like SNR (signal to noise ratio) or PCE (peak to correlation energy) rather than peak to secondary ratio. MEDOF calculates filters for arbitrary modulators and a wide range of metrics as described above. MEDOF examines the statistics of the encoded input image's noise (if SNR or PCE is selected) and the filter SLM's (Spatial Light Modulator) available values. These statistics are used as the basis of a range for searching for the magnitude and phase of k, a pragmatically based complex constant for computing the filter transmittance from the electric field. The filter is produced for the mesh points in those ranges and the value of the metric that results from these points is computed. When the search is concluded, the

  9. Distance stereotest using a 3-dimensional monitor for adult subjects.

    Science.gov (United States)

    Kim, Jongshin; Yang, Hee Kyung; Kim, Youngmin; Lee, Byoungho; Hwang, Jeong-Min

    2011-06-01

    To evaluate the validity and test-retest reliability of a contour-based 3-dimensional (3-D) monitor distance stereotest (distance 3-D stereotest) and to measure the maximum horizontal disparity that can be fused with disparity vergence for determining the largest measurable disparity of true stereopsis. Observational case series. Sixty-four normal adult subjects (age range, 23 to 39 years) were recruited. Contour-based circles (crossed disparity, 5000 to 20 seconds of arc; Microsoft Visual Studio C(++) 6.0; Microsoft, Inc, Seattle, Washington, USA) were generated on a 3-D monitor (46-inch stereoscopic display) using polarization glasses and were presented to subjects with normal binocularity at 3 m. While the position of the stimulus changed among 4 possible locations, the subjects were instructed to press the corresponding position of the stimulus on a keypad. The results with the new distance 3-D stereotest were compared with those from the distance Randot stereotest. The results of the distance 3-D stereotest and the distance Randot stereotests were identical in 64% and within 1 disparity level in 97% of normal adults. Scores obtained with the 2 tests showed a statistically significant correlation (r = 0.324, P = .009). The half-width of the 95% limit of agreement was 0.47 log seconds of arc (1.55 octaves) using the distance 3-D stereotest--similar to or better than that obtained with conventional distance stereotests. The maximum binocular disparity that can be fused with vergence was 1828 ± 794 seconds of arc (range, 4000 to 500). The distance 3-D stereotest showed good concordance with the distance Randot stereotest and relatively good test-retest reliability, supporting the validity of the distance 3-D stereotest. The normative data set obtained from the present study can serve as a useful reference for quantitative assessment of a wide range of binocular sensory abnormalities. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Distance Learning For Mobile Internet Users

    Directory of Open Access Journals (Sweden)

    Beran NECAT

    2007-04-01

    Full Text Available This paper provides an overview on the current state of art in the field of Distance learning for mobile users. It mentions a large range of technologies, services and approaches that may be used to bring distance learning to mobile internet users. These technologies are supposed to considerably increase innovative e-learning solutions for the next generation. While this definitely appears to be true, I think what is not so clear are the implications for students, and lecturers etc. In this article I first evaluate distributed e-learning technologies. With some of the most vital topics, focusing on adaptive distributed e-learning for Mobile Internet Users (MIUs. I also provide a brief analysis of Broadband Network Services, Collaborative e-Learning Tools and Distributed Virtual Environments, Internet-Based Adaptive Learning Technologies and Personalised Distance Learning. I continue my discussion on to Internet Development Tools (IDTs for Distance Learning Solutions, Learning Technologies for MIUs, Semantic and Web-Based Services for Enriching Learning Interactivity, and Evaluations of Distributed Learning Technologies (DLTs.

  11. Decreased accommodation during decompensation of distance exotropia.

    Science.gov (United States)

    Horwood, Anna M; Riddell, Patricia M

    2012-04-01

    Disparity cues can be a major drive to accommodation via the convergence accommodation to convergence (CA/C) linkage, but, on decompensation of exotropia, disparity cues are extinguished by suppression so this drive is lost. This study investigated accommodation and vergence responses to disparity, blur and proximal cues in a group of distance exotropes aged between 4 and 11 years both during decompensation and when exotropic. 19 participants with distance exotropia were tested using a PlusoptiXSO4 photo refractor set in a remote haploscopic device that assessed simultaneous vergence and accommodation to a range of targets incorporating different combinations of blur, disparity and proximal cues at four fixation distances between 2 m and 33 cm. Responses on decompensation were compared with those from the same children when their deviation was controlled. Manifest exotropia was more common in the more impoverished cue conditions. When decompensated for near, mean accommodation gain for the all-cue (naturalistic) target was significantly reduced (paccommodation of 2.33 D at 33 cm. The profile of near cues usage changed after decompensation, with blur and proximity driving residual responses, but these remaining cues did not compensate for loss of accommodation caused by the removal of disparity. Accommodation often reduces on decompensation of distance exotropia as the drive from convergence is extinguished, providing a further reason to try to prevent decompensation for near.

  12. Optic neuritis

    Science.gov (United States)

    Retro-bulbar neuritis; Multiple sclerosis - optic neuritis; Optic nerve - optic neuritis ... The exact cause of optic neuritis is unknown. The optic nerve carries visual information from your eye to the brain. The nerve can swell when ...

  13. Reducing the distance in distance-caregiving by technology innovation

    Directory of Open Access Journals (Sweden)

    Lazelle E Benefield

    2007-07-01

    Full Text Available Lazelle E Benefield1, Cornelia Beck21College of Nursing, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; 2Pat & Willard Walker Family Memory Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USAAbstract: Family caregivers are responsible for the home care of over 34 million older adults in the United States. For many, the elder family member lives more than an hour’s distance away. Distance caregiving is a growing alternative to more familiar models where: 1 the elder and the family caregiver(s may reside in the same household; or 2 the family caregiver may live nearby but not in the same household as the elder. The distance caregiving model involves elders and their family caregivers who live at some distance, defined as more than a 60-minute commute, from one another. Evidence suggests that distance caregiving is a distinct phenomenon, differs substantially from on-site family caregiving, and requires additional assistance to support the physical, social, and contextual dimensions of the caregiving process. Technology-based assists could virtually connect the caregiver and elder and provide strong support that addresses the elder’s physical, social, cognitive, and/or sensory impairments. Therefore, in today’s era of high technology, it is surprising that so few affordable innovations are being marketed for distance caregiving. This article addresses distance caregiving, proposes the use of technology innovation to support caregiving, and suggests a research agenda to better inform policy decisions related to the unique needs of this situation.Keywords: caregiving, family, distance, technology, elders

  14. Equivalence of massive propagator distance and mathematical distance on graphs

    International Nuclear Information System (INIS)

    Filk, T.

    1992-01-01

    It is shown in this paper that the assignment of distance according to the massive propagator method and according to the mathematical definition (length of minimal path) on arbitrary graphs with a bound on the degree leads to equivalent large scale properties of the graph. Especially, the internal scaling dimension is the same for both definitions. This result holds for any fixed, non-vanishing mass, so that a really inequivalent definition of distance requires the limit m → 0

  15. Language distance and tree reconstruction

    International Nuclear Information System (INIS)

    Petroni, Filippo; Serva, Maurizio

    2008-01-01

    Languages evolve over time according to a process in which reproduction, mutation and extinction are all possible. This is very similar to haploid evolution for asexual organisms and for the mitochondrial DNA of complex ones. Exploiting this similarity, it is possible, in principle, to verify hypotheses concerning the relationship among languages and to reconstruct their family tree. The key point is the definition of the distances among pairs of languages in analogy with the genetic distances among pairs of organisms. Distances can be evaluated by comparing grammar and/or vocabulary, but while it is difficult, if not impossible, to quantify grammar distance, it is possible to measure a distance from vocabulary differences. The method used by glottochronology computes distances from the percentage of shared 'cognates', which are words with a common historical origin. The weak point of this method is that subjective judgment plays a significant role. Here we define the distance of two languages by considering a renormalized edit distance among words with the same meaning and averaging over the two hundred words contained in a Swadesh list. In our approach the vocabulary of a language is the analogue of DNA for organisms. The advantage is that we avoid subjectivity and, furthermore, reproducibility of results is guaranteed. We apply our method to the Indo-European and the Austronesian groups, considering, in both cases, fifty different languages. The two trees obtained are, in many respects, similar to those found by glottochronologists, with some important differences as regards the positions of a few languages. In order to support these different results we separately analyze the structure of the distances of these languages with respect to all the others

  16. Language distance and tree reconstruction

    Science.gov (United States)

    Petroni, Filippo; Serva, Maurizio

    2008-08-01

    Languages evolve over time according to a process in which reproduction, mutation and extinction are all possible. This is very similar to haploid evolution for asexual organisms and for the mitochondrial DNA of complex ones. Exploiting this similarity, it is possible, in principle, to verify hypotheses concerning the relationship among languages and to reconstruct their family tree. The key point is the definition of the distances among pairs of languages in analogy with the genetic distances among pairs of organisms. Distances can be evaluated by comparing grammar and/or vocabulary, but while it is difficult, if not impossible, to quantify grammar distance, it is possible to measure a distance from vocabulary differences. The method used by glottochronology computes distances from the percentage of shared 'cognates', which are words with a common historical origin. The weak point of this method is that subjective judgment plays a significant role. Here we define the distance of two languages by considering a renormalized edit distance among words with the same meaning and averaging over the two hundred words contained in a Swadesh list. In our approach the vocabulary of a language is the analogue of DNA for organisms. The advantage is that we avoid subjectivity and, furthermore, reproducibility of results is guaranteed. We apply our method to the Indo-European and the Austronesian groups, considering, in both cases, fifty different languages. The two trees obtained are, in many respects, similar to those found by glottochronologists, with some important differences as regards the positions of a few languages. In order to support these different results we separately analyze the structure of the distances of these languages with respect to all the others.

  17. Study of probe-sample distance for biomedical spectra measurement

    Directory of Open Access Journals (Sweden)

    Li Lei

    2011-11-01

    Full Text Available Abstract Background Fiber-based optical spectroscopy has been widely used for biomedical applications. However, the effect of probe-sample distance on the collection efficiency has not been well investigated. Method In this paper, we presented a theoretical model to maximize the illumination and collection efficiency in designing fiber optic probes for biomedical spectra measurement. This model was in general applicable to probes with single or multiple fibers at an arbitrary incident angle. In order to demonstrate the theory, a fluorescence spectrometer was used to measure the fluorescence of human finger skin at various probe-sample distances. The fluorescence spectrum and the total fluorescence intensity were recorded. Results The theoretical results show that for single fiber probes, contact measurement always provides the best results. While for multi-fiber probes, there is an optimal probe distance. When a 400- μm excitation fiber is used to deliver the light to the skin and another six 400- μm fibers surrounding the excitation fiber are used to collect the fluorescence signal, the experimental results show that human finger skin has very strong fluorescence between 475 nm and 700 nm under 450 nm excitation. The fluorescence intensity is heavily dependent on the probe-sample distance and there is an optimal probe distance. Conclusions We investigated a number of probe-sample configurations and found that contact measurement could be the primary choice for single-fiber probes, but was very inefficient for multi-fiber probes. There was an optimal probe-sample distance for multi-fiber probes. By carefully choosing the probe-sample distance, the collection efficiency could be enhanced by 5-10 times. Our experiments demonstrated that the experimental results of the probe-sample distance dependence of collection efficiency in multi-fiber probes were in general agreement with our theory.

  18. Two-way laser ranging and time transfer experiments between LOLA and an Earth-based satellite laser ranging station

    Science.gov (United States)

    Mao, D.; Sun, X.; Neumann, G. A.; Barker, M. K.; Mazarico, E. M.; Hoffman, E.; Zagwodzki, T. W.; Torrence, M. H.; Mcgarry, J.; Smith, D. E.; Zuber, M. T.

    2017-12-01

    Satellite Laser Ranging (SLR) has established time-of-flight measurements with mm precision to targets orbiting the Earth and the Moon using single-ended round-trip laser ranging to passive optical retro-reflectors. These high-precision measurements enable advances in fundamental physics, solar system dynamics. However, the received signal strength suffers from a 1/R4 decay, which makes it impractical for measuring distances beyond the Moon's orbit. On the other hand, for a two-way laser transponder pair, where laser pulses are both transmitted to and received from each end of the laser links, the signal strength at both terminals only decreases by 1/R2, thus allowing a greater range of distances to be covered. The asynchronous transponder concept has been previously demonstrated by a test in 2005 between the Mercury Laser Altimeter (MLA) aboard the MESSENGER (MErcury Surface, Space ENvironment, Geochemistry, and Ranging) spacecraft and NASA's Goddard Geophysical and Astronomical Observatory (GGAO) at a distance of ˜0.16 AU. In October 2013, regular two-way transponder-type range measurements were obtained over 15 days between the Lunar Laser Communication Demonstration (LLCD) aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft and NASA's ground station at White Sands, NM. The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) provides us a unique capability to test time-transfer beyond near Earth orbit. Here we present results from two-way transponder-type experiments between LOLA and GGAO conducted in March 2014 and 2017. As in the time-transfer by laser link (T2L2) experiments between a ground station and an earth-orbiting satellite, LOLA and GGAO ranged to each other simultaneously in these two-way tests at lunar distance. We measured the time-of-flight while cross-referencing the spacecraft clock to the ground station time. On May 4th, 2017, about 20 minutes of two-way measurements were collected. The

  19. Optical Filter Assembly for Interplanetary Optical Communications

    Science.gov (United States)

    Chen, Yijiang; Hemmati, Hamid

    2013-01-01

    Ground-based, narrow-band, high throughput optical filters are required for optical links from deep space. We report on the development of a tunable filter assembly that operates at telecommunication window of 1550 nanometers. Low insertion loss of 0.5 decibels and bandwidth of 90 picometers over a 2000 nanometers operational range of detectors has been achieved.

  20. Long-Range Neutron Detection

    International Nuclear Information System (INIS)

    Peurrung, A.J.; Stromswold, D.C.; Hansen, R.R.; Reeder, P.L.; Barnett, D.S.

    1999-01-01

    A neutron detector designed for detecting neutron sources at distances of 50 to 100 m has been constructed and tested. This detector has a large surface area (1 m 2 ) to enhance detection efficiency, and it contains a collimator and shielding to achieve direction sensitivity and reduce background. An unusual feature of the detector is that it contains no added moderator, such as polyethylene, to moderate fast neutrons before they reach the 3 He detector. As a result, the detector is sensitive mainly to thermal neutrons. The moderator-free design reduces the weight of the detector, making it more portable, and it also aids in achieving directional sensitivity and background reduction. Test results show that moderated fission-neutron sources of strength about 3 x 10 5 n/s can be detected at a distance out to 70 m in a counting time of 1000 s. The best angular resolution of the detector is obtained at distances of 30 m or less. As the separation .distance between the source and detector increases, the contribution of scattered neutrons to the measured signal increases with a resultant decrease in the ability to detect the direction to a distant source. Applications for which the long-range detector appears to be suitable include detecting remote neutron sources (including sources in moving vehicles) and monitoring neutron storage vaults for the intrusion of humans and the effects they make on the detected neutron signal. Also, the detector can be used to measure waste for the presence of transuranic material in the presence of high gamma-ray background. A test with a neutron source (3 x 10 5 n/s) in a vehicle showed that the detector could readily measure an increase in count rate at a distance of 10 m for vehicle speeds up to 35 mph (the highest speed tested). These results. indicate that the source should be detectable at this distance at speeds up to 55 mph

  1. Academy Distance Learning Tools (IRIS) -

    Data.gov (United States)

    Department of Transportation — IRIS is a suite of front-end web applications utilizing a centralized back-end Oracle database. The system fully supports the FAA Academy's Distance Learning Program...

  2. Distance labeling schemes for trees

    DEFF Research Database (Denmark)

    Alstrup, Stephen; Gørtz, Inge Li; Bistrup Halvorsen, Esben

    2016-01-01

    We consider distance labeling schemes for trees: given a tree with n nodes, label the nodes with binary strings such that, given the labels of any two nodes, one can determine, by looking only at the labels, the distance in the tree between the two nodes. A lower bound by Gavoille et al. [Gavoille...... variants such as, for example, small distances in trees [Alstrup et al., SODA, 2003]. We improve the known upper and lower bounds of exact distance labeling by showing that 1/4 log2(n) bits are needed and that 1/2 log2(n) bits are sufficient. We also give (1 + ε)-stretch labeling schemes using Theta...

  3. Distance Education in Technological Age

    Directory of Open Access Journals (Sweden)

    R .C. SHARMA

    2005-04-01

    Full Text Available Distance Education in Technological AgeRomesh Verma (Editor, New Delhi: Anmol Publications, 2005, ISBN 81-261-2210-2, pp. 419 Reviewed by R C SHARMARegional DirectorIndira Gandhi National Open University-INDIA The advancements in information and communication technologies have brought significant changes in the way the open and distance learning are provided to the learners. The impact of such changes is quite visible in both developed and developing countries. Switching over to online mode, joining hands with private initiatives and making a presence in foreign waters, are some of the hallmarks of the open and distance education (ODE institutions in developing countries. The compilation of twenty six essays on themes as applicable to ODE has resulted in the book, “Distance Education in Technological Age”. These essays follow a progressive style of narration, starting from describing conceptual framework of distance education, how the distance education was emerged on the global scene and in India, and then goes on to discuss emergence of online distance education and research aspects in ODE. The initial four chapters provide a detailed account of historical development and growth of distance education in India and State Open University and National Open University Model in India . Student support services are pivot to any distance education and much of its success depends on how well the support services are provided. These are discussed from national and international perspective. The issues of collaborative learning, learning on demand, life long learning, learning-unlearning and re-learning model and strategic alliances have also given due space by the authors. An assortment of technologies like communication technology, domestic technology, information technology, mass media and entertainment technology, media technology and educational technology give an idea of how these technologies are being adopted in the open universities. The study

  4. Physical activity of the selected nearly isotropic comets with perihelia at large heliocentric distance

    Science.gov (United States)

    Kulyk, I.; Rousselot, P.; Korsun, P. P.; Afanasiev, V. L.; Sergeev, A. V.; Velichko, S. F.

    2018-03-01

    Context. The systematic investigation of comets in a wide range of heliocentric distances can contribute to a better understanding of the physical mechanisms that trigger activity at large distances from the Sun and reveals possible differences in the composition of outer solar system bodies belonging to various dynamical groups. Aims: We seek to analyze the dust environment of the selected nearly isotropic comets with a perihelion distance between 4.5 and 9.1 au, where sublimation of water ice is considered to be negligible. Methods: We present results of multicolor broadband photometric observations for 14 distant active objects conducted between 2008 and 2015 with various telescopes. Images obtained with broadband filters were used to investigate optical colors of the cometary comae and to quantify physical activity of the comet nuclei. Results: The activity level was estimated with Afρ parameters ranging between 95 ± 10 cm and 9600 ± 300 cm. Three returning comets were less active than the dynamically new comets. Dust production rates of the comet nuclei were estimated between 1 and 100 kg s-1 based on some assumptions about the physical properties of dust particles populating comae. The measured colors point out reddening of the continuum for all the comets. The mean values of a normalized reflectivity gradient within the group of the comets amount to 14 ± 2% per 1000 Å and 3 ± 2% per 1000 Å in the BV and VR spectral domains, respectively. The comae of the dynamically new comets, which were observed on their inbound legs, may be slightly redder in the blue spectral interval than comae of the comets observed after the perihelion passages. The dynamically new comets observed both pre- and post-perihelion, seem to have higher production rates post-perihelion than pre-perihelion for similar heliocentric distances.

  5. Novel concepts in near-field optics: from magnetic near-field to optical forces

    Science.gov (United States)

    Yang, Honghua

    Driven by the progress in nanotechnology, imaging and spectroscopy tools with nanometer spatial resolution are needed for in situ material characterizations. Near-field optics provides a unique way to selectively excite and detect elementary electronic and vibrational interactions at the nanometer scale, through interactions of light with matter in the near-field region. This dissertation discusses the development and applications of near-field optical imaging techniques, including plasmonic material characterization, optical spectral nano-imaging and magnetic field detection using scattering-type scanning near-field optical microscopy (s-SNOM), and exploring new modalities of optical spectroscopy based on optical gradient force detection. Firstly, the optical dielectric functions of one of the most common plasmonic materials---silver is measured with ellipsometry, and analyzed with the Drude model over a broad spectral range from visible to mid-infrared. This work was motivated by the conflicting results of previous measurements, and the need for accurate values for a wide range of applications of silver in plasmonics, optical antennas, and metamaterials. This measurement provides a reference for dielectric functions of silver used in metamaterials, plasmonics, and nanophotonics. Secondly, I implemented an infrared s-SNOM instrument for spectroscopic nano-imaging at both room temperature and low temperature. As one of the first cryogenic s-SNOM instruments, the novel design concept and key specifications are discussed. Initial low-temperature and high-temperature performances of the instrument are examined by imaging of optical conductivity of vanadium oxides (VO2 and V2O 3) across their phase transitions. The spectroscopic imaging capability is demonstrated on chemical vibrational resonances of Poly(methyl methacrylate) (PMMA) and other samples. The third part of this dissertation explores imaging of optical magnetic fields. As a proof-of-principle, the magnetic

  6. Distance Education in Technological Age

    OpenAIRE

    R .C. SHARMA

    2005-01-01

    Distance Education in Technological AgeRomesh Verma (Editor), New Delhi: Anmol Publications, 2005, ISBN 81-261-2210-2, pp. 419 Reviewed by R C SHARMARegional DirectorIndira Gandhi National Open University-INDIA The advancements in information and communication technologies have brought significant changes in the way the open and distance learning are provided to the learners. The impact of such changes is quite visible in both developed and developing countries. Switching over to online mode...

  7. Distance determination method of dust particles using Rosetta OSIRIS NAC and WAC data

    Science.gov (United States)

    Drolshagen, E.; Ott, T.; Koschny, D.; Güttler, C.; Tubiana, C.; Agarwal, J.; Sierks, H.; Barbieri, C.; Lamy, P. I.; Rodrigo, R.; Rickman, H.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Bertini, I.; Cremonese, G.; da Deppo, V.; Davidsson, B.; Debei, S.; de Cecco, M.; Deller, J.; Feller, C.; Fornasier, S.; Fulle, M.; Gicquel, A.; Groussin, O.; Gutiérrez, P. J.; Hofmann, M.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Keller, H. U.; Knollenberg, J.; Kramm, J. R.; Kührt, E.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Naletto, G.; Oklay, N.; Shi, X.; Thomas, N.; Poppe, B.

    2017-09-01

    The ESA Rosetta spacecraft has been tracking its target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, in close vicinity for over two years. It hosts the OSIRIS instruments: the Optical, Spectroscopic, and Infrared Remote Imaging System composed of two cameras, see e.g. Keller et al. (2007). In some imaging sequences dedicated to observe dust particles in the comet's coma, the two cameras took images at the same time. The aim of this work is to use these simultaneous double camera observations to calculate the dust particles' distance to the spacecraft. As the two cameras are mounted on the spacecraft with an offset of 70 cm, the distance of particles observed by both cameras can be determined by a shift of the particles' apparent trails on the images. This paper presents first results of the ongoing work, introducing the distance determination method for the OSIRIS instrument and the analysis of an example particle. We note that this method works for particles in the range of about 500-6000 m from the spacecraft.

  8. A distance of 133-137 parsecs to the Pleiades star cluster.

    Science.gov (United States)

    Pan, Xiaopei; Shao, M; Kulkarni, S R

    2004-01-22

    Nearby 'open' clusters of stars (those that are not gravitationally bound) have played a crucial role in the development of stellar astronomy because, as a consequence of the stars having a common age, they provide excellent natural laboratories to test theoretical stellar models. Clusters also play a fundamental part in determining distance scales. The satellite Hipparcos surprisingly found that an extensively studied open cluster--the Pleiades (also known as the Seven Sisters)--had a distance of D = 118 +/- 4 pc (refs 2, 3), about ten per cent smaller than the accepted value. The discrepancy generated a spirited debate because the implication was that either current stellar models were incorrect by a surprising amount or Hipparcos was giving incorrect distances. Here we report the orbital parameters of the bright double star Atlas in the Pleiades, using long-baseline optical/infrared interferometry. From the data we derive a firm lower bound of D > 127 pc, with the most likely range being 133 < D < 137 pc. Our result reaffirms the fidelity of current stellar models.

  9. Distance measurement using frequency-modulated continuous-wave ladar with calibration by a femtosecond frequency comb

    Science.gov (United States)

    Liu, Yang; Yang, Linghui; Lin, Jiarui; Zhu, Jigui

    2018-01-01

    Precise distance measurement is of interest for large-scale manufacturing, future space satellite missions, and other industrial applications. The ranging system with femtosecond optical frequency comb (FOFC) could offer high accuracy, stability and direct traceability to SI definition of the meter. Here, we propose a scheme for length measurement based on the frequency-modulated continuous-wave (FMCW) ladar with a FOFC. In this scheme, the reference interferometer in the FMCW ladar is calibrated by the intensity detection using the FOFC in the time domain within an optical wavelength resolution. With analysis of the theoretical model, this system has the potential to a high-speed, high-accuracy absolute distance measurement. Then, based on the experimental results, the evaluation of the performance of the calibration of the reference arm is discussed. In addition, the performance of this system is evaluated by a single position measurement with different tuning velocities of wavelength. The experimental results show that the reproducibility of the distance measurement is 10-5 level.

  10. THE ARAUCARIA PROJECT. A DISTANCE DETERMINATION TO THE LOCAL GROUP SPIRAL M33 FROM NEAR-INFRARED PHOTOMETRY OF CEPHEID VARIABLES

    Energy Technology Data Exchange (ETDEWEB)

    Gieren, Wolfgang; Pietrzynski, Grzegorz; Graczyk, Dariusz, E-mail: wgieren@astro-udec.cl, E-mail: pietrzyn@hubble.cfm.udec.cl [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw (Poland); and others

    2013-08-10

    Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO Very Large Telescope. From the data, we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of {+-}0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B - V) = 0.19 {+-} 0.02, in agreement with the value used by the Hubble Space Telescope Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1%-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.

  11. Neutron optical potentials

    International Nuclear Information System (INIS)

    Wilmore, D.; Hodgson, P.E.

    1976-01-01

    The purpose of this paper is to provide a guide to the use of optical model computer programs to analyse and calculate neutron data. After a brief discussion of the physical basis of the optical model a survey is given of the most widely used optical model and Hauser-Feshbach computer programs. The range of applicability and reliability of the major optical potentials proposed is assessed by comparison with available experimental data and some observations and suggestions are made for the optimum choice of optical potentials for given purposes of neutron data calculations. (author)

  12. Measuring distances between complex networks

    International Nuclear Information System (INIS)

    Andrade, Roberto F.S.; Miranda, Jose G.V.; Pinho, Suani T.R.; Lobao, Thierry Petit

    2008-01-01

    A previously introduced concept of higher order neighborhoods in complex networks, [R.F.S. Andrade, J.G.V. Miranda, T.P. Lobao, Phys. Rev. E 73 (2006) 046101] is used to define a distance between networks with the same number of nodes. With such measure, expressed in terms of the matrix elements of the neighborhood matrices of each network, it is possible to compare, in a quantitative way, how far apart in the space of neighborhood matrices two networks are. The distance between these matrices depends on both the network topologies and the adopted node numberings. While the numbering of one network is fixed, a Monte Carlo algorithm is used to find the best numbering of the other network, in the sense that it minimizes the distance between the matrices. The minimal value found for the distance reflects differences in the neighborhood structures of the two networks that arise only from distinct topologies. This procedure ends up by providing a projection of the first network on the pattern of the second one. Examples are worked out allowing for a quantitative comparison for distances among distinct networks, as well as among distinct realizations of random networks

  13. Computing Distances between Probabilistic Automata

    Directory of Open Access Journals (Sweden)

    Mathieu Tracol

    2011-07-01

    Full Text Available We present relaxed notions of simulation and bisimulation on Probabilistic Automata (PA, that allow some error epsilon. When epsilon is zero we retrieve the usual notions of bisimulation and simulation on PAs. We give logical characterisations of these notions by choosing suitable logics which differ from the elementary ones, L with negation and L without negation, by the modal operator. Using flow networks, we show how to compute the relations in PTIME. This allows the definition of an efficiently computable non-discounted distance between the states of a PA. A natural modification of this distance is introduced, to obtain a discounted distance, which weakens the influence of long term transitions. We compare our notions of distance to others previously defined and illustrate our approach on various examples. We also show that our distance is not expansive with respect to process algebra operators. Although L without negation is a suitable logic to characterise epsilon-(bisimulation on deterministic PAs, it is not for general PAs; interestingly, we prove that it does characterise weaker notions, called a priori epsilon-(bisimulation, which we prove to be NP-difficult to decide.

  14. Distance sampling methods and applications

    CERN Document Server

    Buckland, S T; Marques, T A; Oedekoven, C S

    2015-01-01

    In this book, the authors cover the basic methods and advances within distance sampling that are most valuable to practitioners and in ecology more broadly. This is the fourth book dedicated to distance sampling. In the decade since the last book published, there have been a number of new developments. The intervening years have also shown which advances are of most use. This self-contained book covers topics from the previous publications, while also including recent developments in method, software and application. Distance sampling refers to a suite of methods, including line and point transect sampling, in which animal density or abundance is estimated from a sample of distances to detected individuals. The book illustrates these methods through case studies; data sets and computer code are supplied to readers through the book’s accompanying website.  Some of the case studies use the software Distance, while others use R code. The book is in three parts.  The first part addresses basic methods, the ...

  15. Misalignment corrections in optical interconnects

    Science.gov (United States)

    Song, Deqiang

    Optical interconnects are considered a promising solution for long distance and high bitrate data transmissions, outperforming electrical interconnects in terms of loss and dispersion. Due to the bandwidth and distance advantage of optical interconnects, longer links have been implemented with optics. Recent studies show that optical interconnects have clear advantages even at very short distances---intra system interconnects. The biggest challenge for such optical interconnects is the alignment tolerance. Many free space optical components require very precise assembly and installation, and therefore the overall cost could be increased. This thesis studied the misalignment tolerance and possible alignment correction solutions for optical interconnects at backplane or board level. First the alignment tolerance for free space couplers was simulated and the result indicated the most critical alignments occur between the VCSEL, waveguide and microlens arrays. An in-situ microlens array fabrication method was designed and experimentally demonstrated, with no observable misalignment with the waveguide array. At the receiver side, conical lens arrays were proposed to replace simple microlens arrays for a larger angular alignment tolerance. Multilayer simulation models in CodeV were built to optimized the refractive index and shape profiles of the conical lens arrays. Conical lenses fabricated with micro injection molding machine and fiber etching were characterized. Active component VCSOA was used to correct misalignment in optical connectors between the board and backplane. The alignment correction capability were characterized for both DC and AC (1GHz) optical signal. The speed and bandwidth of the VCSOA was measured and compared with a same structure VCSEL. Based on the optical inverter being studied in our lab, an all-optical flip-flop was demonstrated using a pair of VCSOAs. This memory cell with random access ability can store one bit optical signal with set or

  16. Optical properties of ferroelectric epitaxial K.sub.0.5./sub.Na.sub.0.5./sub.NbO.sub.3./sub. films in visible to ultraviolet range

    Czech Academy of Sciences Publication Activity Database

    Chernova, Ekaterina; Pacherová, Oliva; Kocourek, Tomáš; Jelínek, Miroslav; Dejneka, Alexandr; Tyunina, Marina

    2016-01-01

    Roč. 11, č. 4 (2016), 1-9, č. článku e0153261. E-ISSN 1932-6203 R&D Projects: GA ČR GA15-13778S Institutional support: RVO:68378271 Keywords : optical properties * ferroelectric * epitaxial films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.806, year: 2016

  17. Euclidean distance geometry an introduction

    CERN Document Server

    Liberti, Leo

    2017-01-01

    This textbook, the first of its kind, presents the fundamentals of distance geometry:  theory, useful methodologies for obtaining solutions, and real world applications. Concise proofs are given and step-by-step algorithms for solving fundamental problems efficiently and precisely are presented in Mathematica®, enabling the reader to experiment with concepts and methods as they are introduced. Descriptive graphics, examples, and problems, accompany the real gems of the text, namely the applications in visualization of graphs, localization of sensor networks, protein conformation from distance data, clock synchronization protocols, robotics, and control of unmanned underwater vehicles, to name several.  Aimed at intermediate undergraduates, beginning graduate students, researchers, and practitioners, the reader with a basic knowledge of linear algebra will gain an understanding of the basic theories of distance geometry and why they work in real life.

  18. Geodesic distance in planar graphs

    International Nuclear Information System (INIS)

    Bouttier, J.; Di Francesco, P.; Guitter, E.

    2003-01-01

    We derive the exact generating function for planar maps (genus zero fatgraphs) with vertices of arbitrary even valence and with two marked points at a fixed geodesic distance. This is done in a purely combinatorial way based on a bijection with decorated trees, leading to a recursion relation on the geodesic distance. The latter is solved exactly in terms of discrete soliton-like expressions, suggesting an underlying integrable structure. We extract from this solution the fractal dimensions at the various (multi)-critical points, as well as the precise scaling forms of the continuum two-point functions and the probability distributions for the geodesic distance in (multi)-critical random surfaces. The two-point functions are shown to obey differential equations involving the residues of the KdV hierarchy

  19. New improvement of the combined optical fiber transducer for landslide monitoring

    Science.gov (United States)

    Zhu, Z.-W.; Yuan, Q.-Y.; Liu, D.-Y.; Liu, B.; Liu, J.-C.; Luo, H.

    2014-08-01

    Landslide monitoring is important in predicting the behavior of landslides, thereby ensuring environmental, life, and property safety. On the basis of our previous studies, we conducted the double shear test by using a third-generation optical fiber transducer that uses expandable polystyrene (EPS) as base material. However, the third-generation transducer has poor performance when cohesive force is present between the grout and capillary stainless steel pipe of the transducer. Thus, the fourth-generation optical fiber transducer was invented. Similar to the third-generation transducer, the fourth-generation transducer also used EPS as its base material. Single shear test was conducted on the fourth-generation transducer after being grouted with cement mortar (1 : 1 mix ratio). The micro-bend loss mechanism of the optical fiber was considered, and the optical time domain reflectometry instrument was used. The fact that the loss sequence of optical fibers subjected to loading is different at various locations is found. The relationship of the loading-point displacement vs. optical fiber sliding distance and optical loss were measured. Results show that the maximum initial measurement precision of the newly proposed device is 1 mm, the corresponding sliding distance is 21 mm, and the dynamic range is 0-20 mm. The fourth-generation transducer can measure the movement direction of loadings, thus making this transducer applicable for landslide monitoring.

  20. Deep-Focusing Time-Distance Helioseismology

    Science.gov (United States)

    Duvall, T. L., Jr.; Jensen, J. M.; Kosovichev, A. G.; Birch, A. C.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Much progress has been made by measuring the travel times of solar acoustic waves from a central surface location to points at equal arc distance away. Depth information is obtained from the range of arc distances examined, with the larger distances revealing the deeper layers. This method we will call surface-focusing, as the common point, or focus, is at the surface. To obtain a clearer picture of the subsurface region, it would, no doubt, be better to focus on points below the surface. Our first attempt to do this used the ray theory to pick surface location pairs that would focus on a particular subsurface point. This is not the ideal procedure, as Born approximation kernels suggest that this focus should have zero sensitivity to sound speed inhomogeneities. However, the sensitivity is concentrated below the surface in a much better way than the old surface-focusing method, and so we expect the deep-focusing method to be more sensitive. A large sunspot group was studied by both methods. Inversions based on both methods will be compared.

  1. Measurement of splanchnic photoplethysmographic signals using a new reflectance fiber optic sensor

    Science.gov (United States)

    Hickey, Michelle; Samuels, Neal; Randive, Nilesh; Langford, Richard M.; Kyriacou, Panayiotis A.

    2010-03-01

    Splanchnic organs are particularly vulnerable to hypoperfusion. Currently, there is no technique that allows for the continuous estimation of splanchnic blood oxygen saturation (SpO2). As a preliminary to developing a suitable splanchnic SpO2 sensor, a new reflectance fiber optic photoplethysmographic (PPG) sensor and processing system are developed. An experimental procedure to examine the effect of fiber source detector separation distance on acquired PPG signals is carried out before finalizing the sensor design. PPG signals are acquired from four volunteers for separation distances of 1 to 8 mm. The separation range of 3 to 6 mm provides the best quality PPG signals with large amplitudes and the highest signal-to-noise ratios (SNRs). Preliminary calculation of SpO2 shows that distances of 3 and 4 mm provide the most realistic values. Therefore, it is suggested that the separation distance in the design of a fiber optic reflectance pulse oximeter be in the range of 3 to 4 mm. Preliminary PPG signals from various splanchnic organs and the periphery are obtained from six anaesthetized patients. The normalized amplitudes of the splanchnic PPGs are, on average, approximately the same as those obtained simultaneously from the periphery. These observations suggest that fiber optic pulse oximetry may be a valid monitoring technique for splanchnic organs.

  2. Optical studies of boiling heat transfer: insights and limitations

    International Nuclear Information System (INIS)

    Kenning, David B.R.

    2004-01-01

    Optical studies provide valuable insights into the complex mechanisms of boiling heat transfer but the large gradients of temperature (and therefore of refractive index) deflect light and multiple reflections at interfaces limit the distance over which observations can be made. Optical measurements are thought of as non-intrusive but this is rarely true. Because they are difficult and time consuming, they constrain the design of boiling experiments and are applied to limited ranges of conditions. There is a risk that deductions from the observations will be applied (not necessarily by the authors) more generally than is justified. These characteristics of optical studies are illustrated by examples from forced convective film boiling on spheres and pool nucleate boiling

  3. Adaptive Distance Protection for Microgrids

    DEFF Research Database (Denmark)

    Lin, Hengwei; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2015-01-01

    is adopted to accelerate the tripping speed of the relays on the weak lines. The protection methodology is tested on a mid-voltage microgrid network in Aalborg, Denmark. The results show that the adaptive distance protection methodology has good selectivity and sensitivity. What is more, this system also has......Due to the increasing penetration of distributed generation resources, more and more microgrids can be found in distribution systems. This paper proposes a phasor measurement unit based distance protection strategy for microgrids in distribution system. At the same time, transfer tripping scheme...

  4. Long range trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Allen, P. W.; Jessup, E. A.; White, R. E. [Air Resources Field Research Office, Las Vegas, Nevada (United States)

    1967-07-01

    A single air molecule can have a trajectory that can be described with a line, but most meteorologists use single lines to represent the trajectories of air parcels. A single line trajectory has the disadvantage that it is a categorical description of position. Like categorized forecasts it provides no qualification, and no provision for dispersion in case the parcel contains two or more molecules which may take vastly different paths. Diffusion technology has amply demonstrated that an initial aerosol cloud or volume of gas in the atmosphere not only grows larger, but sometimes divides into puffs, each having a different path or swath. Yet, the average meteorologist, faced with the problem of predicting the future motion of a cloud, usually falls back on the line trajectory approach with the explanation that he had no better tool for long range application. In his more rational moments, he may use some arbitrary device to spread his cloud with distance. One such technique has been to separate the trajectory into two or more trajectories, spaced about the endpoint of the original trajectory after a short period of travel, repeating this every so often like a chain reaction. This has the obvious disadvantage of involving a large amount of labor without much assurance of improved accuracy. Another approach is to draw a circle about the trajectory endpoint, to represent either diffusion or error. The problem then is to know what radius to give the circle and also whether to call it diffusion or error. Meteorologists at the Nevada Test Site (NTS) are asked frequently to provide advice which involves trajectory technology, such as prediction of an aerosol cloud path, reconstruction of the motion of a volume of air, indication of the dilution, and the possible trajectory prediction error over great distances. Therefore, we set out, nearly three years ago, to provide some statistical knowledge about the status of our trajectory technology. This report contains some of the

  5. Paintball velocity as a function of distance traveled

    Directory of Open Access Journals (Sweden)

    Pat Chiarawongse

    2008-06-01

    Full Text Available The relationship between the distance a paintball travels through air and its velocity is investigated by firing a paintball into a ballistic pendulum from a range of distances. The motion of the pendulum was filmed and analyzed by using video analysis software. The velocity of the paintball on impact was calculated from the maximum horizontal displacement of the pendulum. It is shown that the velocity of a paintball decreases exponentially with distance traveled, as expected. The average muzzle velocity of the paint balls is found with an estimate of the drag coefficient.

  6. Paintball velocity as a function of distance traveled

    Directory of Open Access Journals (Sweden)

    Pat Chiarawongse

    2008-06-01

    Full Text Available The relationship between the distance a paintball travels through air and its velocity is investigated by firing a paintball into a ballistic pendulum from a range of distances. The motion of the pendulum was filmed and analyzed by using video analysis software. The velocity of the paintball on impact was calculated from the maximum horizontal displacement of the pendulum. It is shown that the velocity of a paintball decreases exponentially with distance traveled, as expected. The average muzzle velocity of the paint balls is found with an estimate of the drag coefficient

  7. Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.

    Directory of Open Access Journals (Sweden)

    Gilles Clément

    Full Text Available We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5-6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g, hypergravity (1.8 g, and normal gravity (1 g. Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.

  8. INTERPRETING THE DISTANCE CORRELATION RESULTS FOR THE COMBO-17 SURVEY

    International Nuclear Information System (INIS)

    Richards, Mercedes T.; Richards, Donald St. P.; Martínez-Gómez, Elizabeth

    2014-01-01

    The accurate classification of galaxies in large-sample astrophysical databases of galaxy clusters depends sensitively on the ability to distinguish between morphological types, especially at higher redshifts. This capability can be enhanced through a new statistical measure of association and correlation, called the distance correlation coefficient, which has more statistical power to detect associations than does the classical Pearson measure of linear relationships between two variables. The distance correlation measure offers a more precise alternative to the classical measure since it is capable of detecting nonlinear relationships that may appear in astrophysical applications. We showed recently that the comparison between the distance and Pearson correlation coefficients can be used effectively to isolate potential outliers in various galaxy data sets, and this comparison has the ability to confirm the level of accuracy associated with the data. In this work, we elucidate the advantages of distance correlation when applied to large databases. We illustrate how the distance correlation measure can be used effectively as a tool to confirm nonlinear relationships between various variables in the COMBO-17 database, including the lengths of the major and minor axes, and the alternative redshift distribution. For these outlier pairs, the distance correlation coefficient is routinely higher than the Pearson coefficient since it is easier to detect nonlinear relationships with distance correlation. The V-shaped scatter plots of Pearson versus distance correlation coefficients also reveal the patterns with increasing redshift and the contributions of different galaxy types within each redshift range

  9. Auditory/visual distance estimation: accuracy and variability

    Directory of Open Access Journals (Sweden)

    Paul Wallace Anderson

    2014-10-01

    Full Text Available Past research has shown that auditory distance estimation improves when listeners are given the opportunity to see all possible sound sources when compared to no visual input. It has also been established that distance estimation is more accurate in vision than in audition. The present study investigates the degree to which auditory distance estimation is improved when matched with a congruent visual stimulus. Virtual sound sources based on binaural room impulse response (BRIR measurements made from distances ranging from approximately 0.3 to 9.8 m in a concert hall were used as auditory stimuli. Visual stimuli were photographs taken from the listener’s perspective at each distance in the impulse response measurement setup presented on a large HDTV monitor. Listeners were asked to estimate egocentric distance to the sound source in each of three conditions: auditory only (A, visual only (V, and congruent auditory/visual stimuli (A+V. Each condition was presented within its own block. Sixty-two listeners were tested in order to quantify the response variability inherent in auditory distance perception. Distance estimates from both the V and A+V conditions were found to be considerably more accurate and less variable than estimates from the A condition.

  10. Fast Exact Euclidean Distance (FEED) Transformation

    NARCIS (Netherlands)

    Schouten, Theo; Kittler, J.; van den Broek, Egon; Petrou, M.; Nixon, M.

    2004-01-01

    Fast Exact Euclidean Distance (FEED) transformation is introduced, starting from the inverse of the distance transformation. The prohibitive computational cost of a naive implementation of traditional Euclidean Distance Transformation, is tackled by three operations: restriction of both the number

  11. Optical detection of ultrasound using an apertureless near-field scanning optical microscopy system

    Science.gov (United States)

    Ahn, Phillip; Zhang, Zhen; Sun, Cheng; Balogun, Oluwaseyi

    2013-01-01

    Laser ultrasonics techniques are power approaches for non-contact generation and detection of high frequency ultrasound on a local scale. In these techniques, optical diffraction limits the spatial information that can be accessed from a measurement. In order to improve the lateral spatial resolution, we incorporate an apertureless near-field scanning optical microscope (aNSOM) into laser ultrasonics setup for local detection of laser generated ultrasound. The aNSOM technique relies on the measurement of a weak backscattered near-field light intensity resulting from the oblique illumination of a nanoscale probe-tip positioned close to a sample surface. We enhance the optical near-field intensity by coupling light to surface plasmon polaritons (SPPs) on the shaft of an atomic force microscopy (AFM) cantilever. The SPPs propagate down the AFM shaft, localize at the tip apex, and are backscattered to the far-field when the separation distance between the probe tip and the sample surface is comparable to the probe-tip radius. The backscattered near-field intensity is dynamically modulated when an ultrasonic wave arrives at the sample surface leading to a transient change in the tip-sample separation distance. We present experimental results detailing measurement of broadband and narrowband laser generated ultrasound in solids with frequencies reaching up to 180 MHz range.

  12. Atmospheric free-space coherent optical communications with adaptive optics

    Science.gov (United States)

    Ting, Chueh; Zhang, Chengyu; Yang, Zikai

    2017-02-01

    Free-space coherent optical communications have a potential application to offer last mile bottleneck solution in future local area networks (LAN) because of their information carrier, information security and license-free status. Coherent optical communication systems using orthogonal frequency division multiplexing (OFDM) digital modulation are successfully demonstrated in a long-haul tens Giga bits via optical fiber, but they are not yet available in free space due to atmospheric turbulence-induced channel fading. Adaptive optics is recognized as a promising technology to mitigate the effects of atmospheric turbulence in free-space optics. In this paper, a free-space coherent optical communication system using an OFDM digital modulation scheme and adaptive optics (FSO OFDM AO) is proposed, a Gamma-Gamma distribution statistical channel fading model for the FSO OFDM AO system is examined, and FSO OFDM AO system performance is evaluated in terms of bit error rate (BER) versus various propagation distances.

  13. Tunable micro-optics

    CERN Document Server

    Duppé, Claudia

    2015-01-01

    Presenting state-of-the-art research into the dynamic field of tunable micro-optics, this is the first book to provide a comprehensive survey covering a varied range of topics including novel materials, actuation concepts and new imaging systems in optics. Internationally renowned researchers present a diverse range of chapters on cutting-edge materials, devices and subsystems, including soft matter, artificial muscles, tunable lenses and apertures, photonic crystals, and complete tunable imagers. Special contributions also provide in-depth treatment of micro-optical characterisation, scanners, and the use of natural eye models as inspiration for new concepts in advanced optics. With applications extending from medical diagnosis to fibre telecommunications, Tunable Micro-optics equips readers with a solid understanding of the broader technical context through its interdisciplinary approach to the realisation of new types of optical systems. This is an essential resource for engineers in industry and academia,...

  14. Cross-Border Electronic Commerce : Distance Effects and Express Delivery in European Union Markets

    NARCIS (Netherlands)

    T.Y. Kim (Thai Young); R. Dekker (Rommert); C. Heij (Christiaan)

    2017-01-01

    textabstractThis empirical study examines distance effects on cross-border electronic commerce and in particular the importance of express delivery in reducing the time dimension of distance. E-commerce provides suppliers with a range of opportunities to reduce distance as perceived by online

  15. Steiner Distance in Graphs--A Survey

    OpenAIRE

    Mao, Yaping

    2017-01-01

    For a connected graph $G$ of order at least $2$ and $S\\subseteq V(G)$, the \\emph{Steiner distance} $d_G(S)$ among the vertices of $S$ is the minimum size among all connected subgraphs whose vertex sets contain $S$. In this paper, we summarize the known results on the Steiner distance parameters, including Steiner distance, Steiner diameter, Steiner center, Steiner median, Steiner interval, Steiner distance hereditary graph, Steiner distance stable graph, average Steiner distance, and Steiner ...

  16. Partial distance correlation with methods for dissimilarities

    OpenAIRE

    Székely, Gábor J.; Rizzo, Maria L.

    2014-01-01

    Distance covariance and distance correlation are scalar coefficients that characterize independence of random vectors in arbitrary dimension. Properties, extensions, and applications of distance correlation have been discussed in the recent literature, but the problem of defining the partial distance correlation has remained an open question of considerable interest. The problem of partial distance correlation is more complex than partial correlation partly because the squared distance covari...

  17. Gesture Interaction at a Distance

    NARCIS (Netherlands)

    Fikkert, F.W.

    2010-01-01

    The aim of this work is to explore, from a perspective of human behavior, which gestures are suited to control large display surfaces from a short distance away; why that is so; and, equally important, how such an interface can be made a reality. A well-known example of the type of interface that is

  18. Communication Barriers in Distance Education

    Science.gov (United States)

    Isman, Aytekin; Dabaj, Fahme; Altinay, Fahriye; Altinay, Zehra

    2003-01-01

    Communication is a key concept as being the major tool for people in order to satisfy their needs. It is an activity which refers as process and effective communication requires qualified communication with the elimination of communication barriers. As it is known, distance education is a new trend by following contemporary facilities and tools…

  19. Distance Education Technologies in Asia

    International Development Research Centre (IDRC) Digital Library (Canada)

    17 schools ... Mobile Technology in Non-formal Distance Education 192 ..... in the design and application of e-learning strategies, the need to standardise and ...... library providing access to over 20,000 journals and thesis databases, and 6,000 ...

  20. Video surveillance using distance maps

    Science.gov (United States)

    Schouten, Theo E.; Kuppens, Harco C.; van den Broek, Egon L.

    2006-02-01

    Human vigilance is limited; hence, automatic motion and distance detection is one of the central issues in video surveillance. Hereby, many aspects are of importance, this paper specially addresses: efficiency, achieving real-time performance, accuracy, and robustness against various noise factors. To obtain fully controlled test environments, an artificial development center for robot navigation is introduced in which several parameters can be set (e.g., number of objects, trajectories and type and amount of noise). In the videos, for each following frame, movement of stationary objects is detected and pixels of moving objects are located from which moving objects are identified in a robust way. An Exact Euclidean Distance Map (E2DM) is utilized to determine accurately the distances between moving and stationary objects. Together with the determined distances between moving objects and the detected movement of stationary objects, this provides the input for detecting unwanted situations in the scene. Further, each intelligent object (e.g., a robot), is provided with its E2DM, allowing the object to plan its course of action. Timing results are specified for each program block of the processing chain for 20 different setups. So, the current paper presents extensive, experimentally controlled research on real-time, accurate, and robust motion detection for video surveillance, using E2DMs, which makes it a unique approach.