WorldWideScience

Sample records for laser ranging workshop

  1. 2nd Topical Workshop on Laser Technology and Optics Design

    CERN Document Server

    2013-01-01

    Lasers have a variety of applications in particle accelerator operation and will play a key role in the development of future particle accelerators by improving the generation of high brightness electron and exotic ion beams and through increasing the acceleration gradient. Lasers will also make an increasingly important contribution to the characterization of many complex particle beams by means of laser-based beam diagnostics methods. The second LANET topical workshop will address the key aspects of laser technology and optics design relevant to laser application to accelerators. The workshop will cover general optics design, provide an overview of different laser sources and discuss methods to characterize beams in details. Participants will be able to choose from a range of topical areas that go deeper in more specific aspects including tuneable lasers, design of transfer lines, noise sources and their elimination and non-linear optics effects. The format of the workshop will be mainly training-based wit...

  2. Laser Range Sensors

    Directory of Open Access Journals (Sweden)

    K.C. Bahuguna

    2007-11-01

    Full Text Available This paper presents the design aspects of laser range finders and proximity sensors being developed at IRDE for different applications. The principle used in most of the laser range finders is pulse echo or time-of-flight measurement. Optical triangulation is used in proximity sensors while techniques like phase detection and interferometry are employed in instruments for surveying and motion controllers where high accuracy is desired. Most of the laser range finders are designed for ranging non-cooperative targets.

  3. Reconfigurable laser ranging instrument

    Science.gov (United States)

    Schneiter, John

    1994-03-01

    This paper describes the design and operation of a fast, flexible, non-contact, eye-safe laser ranging instrument useful in a variety of industrial metrology situations, such as in-process machining control and part inspection. The system has variable computer-controlled standoff and depth of field, and can obtain 3-D images of surfaces within a range of from 1.5 ft to almost 10 ft from the final optical element. The minimum depth of field is about 3.5 in. at 1.5 ft and about 26 in. at the far range. The largest depth of field for which useful data are available is about 41 in. Resolution, with appropriate averaging, is about one part in 4000 of the depth of field, which implies a best case resolution for this prototype of 0.00075 in. System flexibility is achieved by computer controlled relative positioning of optical components.

  4. Mobile Lunar Laser Ranging Station

    Science.gov (United States)

    Intellect, 1977

    1977-01-01

    Harlan Smith, chairman of the University of Texas's Astronomy Department, discusses a mobile lunar laser ranging station which could help determine the exact rates of movement between continents and help geophysicists understand earthquakes. He also discusses its application for studying fundamental concepts of cosmology and physics. (Editor/RK)

  5. Laser ranging ground station development

    Science.gov (United States)

    Faller, J. E.

    1973-01-01

    The employment of ground to conduct radar range measurements of the lunar distance is discussed. The advantages of additional ground stations for this purpose are analyzed. The goals which are desirable for any new type of ranging station are: (1) full time availability of the station for laser ranging, (2) optimization for signal strength, (3) automation to the greatest extent possible, (4) the capability for blind pointing, (5) reasonable initial and modest operational costs, and (6) transportability to enhance the value of the station for geophysical purposes.

  6. EDITORIAL: Laser and Plasma Accelerators Workshop, Kardamyli, Greece, 2009 Laser and Plasma Accelerators Workshop, Kardamyli, Greece, 2009

    Science.gov (United States)

    Bingham, Bob; Muggli, Patric

    2011-01-01

    The Laser and Plasma Accelerators Workshop 2009 was part of a very successful series of international workshops which were conceived at the 1985 Laser Acceleration of Particles Workshop in Malibu, California. Since its inception, the workshop has been held in Asia and in Europe (Kardamyli, Kyoto, Presqu'ile de Giens, Portovenere, Taipei and the Azores). The purpose of the workshops is to bring together the most recent results in laser wakefield acceleration, plasma wakefield acceleration, laser-driven ion acceleration, and radiation generation produced by plasma-based accelerator beams. The 2009 workshop was held on 22-26 June in Kardamyli, Greece, and brought together over 80 participants. (http://cfp.ist.utl.pt/lpaw09/). The workshop involved five main themes: • Laser plasma electron acceleration (experiment/theory/simulation) • Computational methods • Plasma wakefield acceleration (experiment/theory/simulation) • Laser-driven ion acceleration • Radiation generation and application. All of these themes are covered in this special issue of Plasma Physics and Controlled Fusion. The topic and application of plasma accelerators is one of the success stories in plasma physics, with laser wakefield acceleration of mono-energetic electrons to GeV energies, of ions to hundreds of MeV, and electron-beam-driven wakefield acceleration to 85 GeV. The accelerating electric field in the wake is of the order 1 GeV cm-1, or an accelerating gradient 1000 times greater than in conventional accelerators, possibly leading to an accelerator 1000 times smaller (and much more affordable) for the same energy. At the same time, the electron beams generated by laser wakefield accelerators have very good emittance with a correspondingly good energy spread of about a few percent. They also have the unique feature in being ultra-short in the femtosecond scale. This makes them attractive for a variety of applications, ranging from material science to ultra-fast time

  7. Workshop on scientific and industrial applications of free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Difilippo, F.C. (Oak Ridge National Lab., TN (USA)); Perez, R.B. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA))

    1990-05-01

    A Workshop on Scientific and Industrial Applications of Free Electron Lasers was organized to address potential uses of a Free Electron Laser in the infrared wavelength region. A total of 13 speakers from national laboratories, universities, and the industry gave seminars to an average audience of 30 persons during June 12 and 13, 1989. The areas covered were: Free Electron Laser Technology, Chemistry and Surface Science, Atomic and Molecular Physics, Condensed Matter, and Biomedical Applications, Optical Damage, and Optoelectronics.

  8. The Sixth Omega Laser Facility Users Group Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Petrasso, R. D.

    2014-10-01

    A capacity gathering of over 100 researchers from 25 universities and laboratories met at the Laboratory for Laser Energetics (LLE) for the Sixth Omega Laser Facility Users Group (OLUG) workshop. The purpose of the 2.5-day workshop was to facilitate communications and exchanges among individual OMEGA users, and between users and the LLE management; to present ongoing and proposed research; to encourage research opportunities and collaborations that could be undertaken at the Omega Laser Facility and in a complementary fashion at other facilities [such as the National Ignition Facility (NIF) or the Laboratoire pour l’Utilisation des Lasers Intenses (LULI)]; to provide an opportunity for students, postdoctoral fellows, and young researchers to present their research in an informal setting; and to provide feedback from the users to LLE management about ways to improve and keep the facility and future experimental campaigns at the cutting edge.

  9. The Fifth Omega Laser Facility Users Group Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Petrasso, R. D.

    2015-10-01

    A capacity gathering of over 100 researchers from 25 universities and laboratories met at the Laboratory for Laser Energetics (LLE) for the Fifth Omega Laser Facility Users Group (OLUG) workshop. The purpose of the 2.5-day workshop was to facilitate communications and exchanges among individual Omega users and between users and the LLE management; to present ongoing and proposed research; to encourage research opportunities and collaborations that could be undertaken at the Omega Laser Facility and in a complementary fashion at other facilities [such as the National Ignition Facility (NIF) or the Laboratoire pour l’Utilisation des Lasers Intenses (LULI)]; to provide an opportunity for students, postdoctoral fellows, and young researchers to present their research in an informal setting; and to provide feedback to LLE management from the users about ways to improve the facility and future experimental campaigns.

  10. Theoretical analysis and numerical solution of laser pulse transformation for satellite laser ranging

    Institute of Scientific and Technical Information of China (English)

    FAN; Jianxing

    2001-01-01

    [1]Yang Fumin,Xiao Chikun,Chen Wanzhen et al.,Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory,Science in China,Series A,1999,42(2):198-206.[2]Degnan,J.,Effects of detection threshold and signal strength on lageos range bias,Proceedings of Ninth International Workshop on Laser Ranging Instrumentation,1994,3:920-925.[3]Degnan,J.,Satellite laser ranging:current status and future prospects,IEEE Transactions on Geoscience and Remote Sensing,1985,GE-23(4):398-413.[4]Degnan,J.,Millimeter accuracy satellites for two color ranging,Proceedings of Eighth International Workshop on Laser Ranging Instrumentation,1992,7:36-51.[5]Neubert,R.,An analytical model of satellite signature effects,Proceedings of Ninth International Workshop on Laser Ranging Instrumentation,1994,1:82-91.[6]Si Yu,Li Yaowu,Application of Probability and Math-Physics Statistics (in Chinese),Xi'an:Xi'an Jiaotong University Press,1997,48-49.[7]Li Huxi,Jiang Hong,Matlab Step by Step[M](in Chinese),Shanghai:Shanghai Jiaotong University Press,1997,91-93[8]Si Suo,Mathcad 7.0 Practice Course (in Chinese),Beijing:The People's Post & Communication Press,1998,126-127.[9]Xi Meicheng,Methods of Numerical Analysis (in Chinese),Hefei:University of Science and Technology of China Press,1995,123-134.[10]Fan Jianxing,Yang Fumin,Chen Qixiu,The CoM model of satellite signature for laser ranging,Acta Photonica Sinica (in Chinese),2000,29(11):1012-1016.[11]Lu Dajin,Random Process & Its Application (in Chinese),Beijing:Tsinghua University Press,1986,133-137.

  11. Short-Pulse Laser-Matter Computational Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Town, R; Tabak, M

    2004-11-02

    For three days at the end of August 2004, 55 plasma scientists met at the Four Points by Sheraton in Pleasanton to discuss some of the critical issues associated with the computational aspects of the interaction of short-pulse high-intensity lasers with matter. The workshop was organized around the following six key areas: (1) Laser propagation/interaction through various density plasmas: micro scale; (2) Anomalous electron transport effects: From micro to meso scale; (3) Electron transport through plasmas: From meso to macro scale; (4) Ion beam generation, transport, and focusing; (5) ''Atomic-scale'' electron and proton stopping powers; and (6) K{alpha} diagnostics.

  12. 2nd Workshop on Laser Interaction and Related Plasma Phenomena

    CERN Document Server

    Hora, Heinrich

    1972-01-01

    Paul Harteck Rensselaer Polytechnic Institute Troy, New York When the Maser and the Laser Were discovered, people were speculating if this was the beginning of a new page, or even a new chapter, in the Book of Physics. The Second Workshop on "Laser Interaction and Related Plasma Phenomena" held in Hartford made it clear that the perspective had changed, that people now question if the consequences of these discoveries constitute a new chapter, or possibly a new era in Physics. While the papers presented were all stimulating and of out­ standing quality, of special interest were the experiments which demonstrated that triggering of thermonuclear fusion by Laser techniques is indeed in the realm of the possible. Along these lines, I enjoy recalling an anecdote concerning the late F. G. Houtermans. I think that all who knew him will agree that he was an unusual genius and at the same time a very amusing colleague.

  13. Ranging performance of active laser detection

    Science.gov (United States)

    Sun, Huayan; Xiong, Fei; Gu, Suolin

    2006-06-01

    Ranging performance is described for photoelectric equipment reconnaissance using an active laser detection system that is based on the 'cat's eyes' effect of optical windows. Active laser detection systems have an advantage over passive systems because they can measure target velocity and spatial coordinates. However, there are several challenging problems here because of the great distances involved, the low returned power of the uncooperative target, and the optical aberrations induced by the atmosphere. In the design of this system, the principle of detection is based on the 'cat's eyes' effect according to which the optical windows of photoelectric equipments have a strong reflect character towards incident laser beam. With 'cat's eyes' effect, the detection of uncooperative target can be translated into one of a cooperative target, so the ratio of returned laser can be increased. In this paper, the ranging performance presented here takes into account all the various elements of the system, from the laser emission, target, atmospheric propagation to the detector. The characteristics of back-reflected laser and an estimate of the laser Cross Section (LCS) from 'cat's eyes target' are investigated in theory and simulation. The Signal-to-Noise Ratio (SNR) is calculated by combining the probability of detection of the system for given electronic characteristics of the system and for a given probability of false alarms. On the basis of analysis of SNR, minimum detectable signal power, operating distance of the system and factors affecting the ranging performance is analyzed. Results indicate that system has characters of long range, and high sensitivity. It can be used to detect the aerial targets such as reconnaissance drone, navigate missile, reconnaissance satellite etc.

  14. Long-range laser-illuminated imaging

    Science.gov (United States)

    Dayton, David C.; Browne, Stephen L.; Sandven, Steven C.; Gonglewski, John D.; Gallegos, Joe; Shilko, Michael L., Sr.

    2000-11-01

    We demonstrate the utility of laser illuminated imaging for clandestine night time surveillance from a simulated airborne platform at standoff ranges in excess 20 km. In order to reduce the necessary laser per pulse energy required for illumination at such long ranges, and to mitigate atmospheric turbulence effects on image resolution, we have investigated a unique multi-frame post-processing technique. It is shown that in the presence of atmospheric turbulence and coherent speckle effects, this approach can produce superior results to conventional scene flood illumination.

  15. Tests of Gravity Using Lunar Laser Ranging

    Directory of Open Access Journals (Sweden)

    Stephen M. Merkowitz

    2010-11-01

    Full Text Available Lunar laser ranging (LLR has been a workhorse for testing general relativity over the past four decades. The three retroreflector arrays put on the Moon by the Apollo astronauts and the French built arrays on the Soviet Lunokhod rovers continue to be useful targets, and have provided the most stringent tests of the Strong Equivalence Principle and the time variation of Newton’s gravitational constant. The relatively new ranging system at the Apache Point 3.5 meter telescope now routinely makes millimeter level range measurements. Incredibly, it has taken 40 years for ground station technology to advance to the point where characteristics of the lunar retroreflectors are limiting the precision of the range measurements. In this article, we review the gravitational science and technology of lunar laser ranging and discuss prospects for the future.

  16. Satellite and lunar laser ranging in infrared

    Science.gov (United States)

    Courde, Clement; Torre, Jean-Marie; Samain, Etienne; Martinot-Lagarde, Gregoire; Aimar, Mourad; Albanese, Dominique; Maurice, Nicolas; Mariey, Hervé; Viot, Hervé; Exertier, Pierre; Fienga, Agnes; Viswanathan, Vishnu

    2017-05-01

    We report on the implementation of a new infrared detection at the Grasse lunar laser ranging station and describe how infrared telemetry improves the situation. We present our first results on the lunar reflectors and show that infrared detection permits us to densify the observations and allows measurements during the new and the full moon periods. We also present the benefit obtained on the ranging of Global Navigation Satellite System (GNSS) satellites and on RadioAstron which have a very elliptic orbit.

  17. Clock comparison based on laser ranging technologies

    Science.gov (United States)

    Samain, Etienne

    2015-06-01

    Recent progress in the domain of time and frequency standards has required some important improvements of existing time transfer links. Several time transfer by laser link (T2L2) projects have been carried out since 1972 with numerous scientific or technological objectives. There are two projects currently under exploitation: T2L2 and Lunar Reconnaissance Orbiter (LRO). The former is a dedicated two-way time transfer experiment embedded on the satellite Jason-2 allowing for the synchronization of remote clocks with an uncertainty of 100 ps and the latter is a one-way link devoted for ranging a spacecraft orbiting around the Moon. There is also the Laser Time Transfer (LTT) project, exploited until 2012 and designed in the frame of the Chinese navigation constellation. In the context of future space missions for fundamental physics, solar system science or navigation, laser links are of prime importance and many missions based on that technology have been proposed for these purposes.

  18. Multi-target compressive laser ranging

    Science.gov (United States)

    Pandit, Pushkar P.; Dahl, Jason R.; Barber, Zeb W.; Babbitt, W. Randall

    2014-05-01

    Compressive laser ranging (CLR) is a method that exploits the sparsity available in the range domain using compressive sensing methods to directly obtain range domain information. Conventional ranging methods are marred by requirements of high bandwidth analog detection which includes severe SNR fall off with bandwidth in analog-to-digital conversion (ADC). Compressive laser ranging solves this problem by obtaining sub-centimeter resolution while using low bandwidth detection. High rate digital pulse pattern generators and off the shelf photonic devices are used to modulate the transmitted and received light from a superluminescent diode. CLR detection is demonstrated using low bandwidth, high dynamic range detectors along with photon counting techniques. The use of an incoherent source eliminates speckle issues and enables simplified CLR methods to get multi-target range profiles with 1-3cm resolution. Using compressive sensing methods CLR allows direct range measurements in the sub-Nyquist regime while reducing system resources, in particular the need for high bandwidth ADC.

  19. Lunar laser ranging in infrared at the Grasse laser station

    Science.gov (United States)

    Courde, C.; Torre, J. M.; Samain, E.; Martinot-Lagarde, G.; Aimar, M.; Albanese, D.; Exertier, P.; Fienga, A.; Mariey, H.; Metris, G.; Viot, H.; Viswanathan, V.

    2017-06-01

    For many years, lunar laser ranging (LLR) observations using a green wavelength have suffered an inhomogeneity problem both temporally and spatially. This paper reports on the implementation of a new infrared detection at the Grasse LLR station and describes how infrared telemetry improves this situation. Our first results show that infrared detection permits us to densify the observations and allows measurements during the new and the full Moon periods. The link budget improvement leads to homogeneous telemetric measurements on each lunar retro-reflector. Finally, a surprising result is obtained on the Lunokhod 2 array which attains the same efficiency as Lunokhod 1 with an infrared laser link, although those two targets exhibit a differential efficiency of six with a green laser link.

  20. Matera Laser Ranging Observatory (MLRO): An overview

    Science.gov (United States)

    Varghese, Thomas K.; Decker, Winfield M.; Crooks, Henry A.; Bianco, Giuseppe

    1993-01-01

    The Agenzia Spaziale Italiana (ASI) is currently under negotiation with the Bendix Field Engineering Corporation (BFEC) of the Allied Signal Aerospace Company (ASAC) to build a state-of-the-art laser ranging observatory for the Centro di Geodesia Spaziale, in Matera, Italy. The contract calls for the delivery of a system based on a 1.5 meter afocal Cassegrain astronomical quality telescope with multiple ports to support a variety of experiments for the future, with primary emphasis on laser ranging. Three focal planes, viz. Cassegrain, Coude, and Nasmyth will be available for these experiments. The open telescope system will be protected from dust and turbulence using a specialized dome which will be part of the building facilities to be provided by ASI. The fixed observatory facility will be partitioned into four areas for locating the following: laser, transmit/receive optics, telescope/dome enclosure, and the operations console. The optical tables and mount rest on a common concrete pad for added mechanical stability. Provisions will be in place for minimizing the effects of EMI, for obtaining maximum cleanliness for high power laser and transmit optics, and for providing an ergonomic environment fitting to a state-of-the-art multipurpose laboratory. The system is currently designed to be highly modular and adaptable for scaling or changes in technology. It is conceived to be a highly automated system with superior performance specifications to any currently operational system. Provisions are also made to adapt and accommodate changes that are of significance during the course of design and integration.

  1. Lunar laser ranging: the millimeter challenge

    CERN Document Server

    Murphy, T W

    2013-01-01

    Lunar laser ranging has provided many of the best tests of gravitation since the first Apollo astronauts landed on the Moon. The march to higher precision continues to this day, now entering the millimeter regime, and promising continued improvement in scientific results. This review introduces key aspects of the technique, details the motivations, observables, and results for a variety of science objectives, summarizes the current state of the art, highlights new developments in the field, describes the modeling challenges, and looks to the future of the enterprise.

  2. Satellite Laser Ranging and General Relativity

    CERN Document Server

    Iorio, L

    2001-01-01

    In this work some aspects of the detection of certain general relativistic effects in the weak gravitational field of the Earth via laser-ranged data to some existing or proposed geodetic satellites are examined. The focus is on the Lense-Thirring drag of the orbit of a test body, the gravitomagnetic clock effect and the gravitoelectric perigee shift. The impact of some sources of systematic errors is investigated. An experiment whose goal is the measurement of the PPN parameters beta and gamma in the terrestrial field with LAGEOS satellites at a level of 10^(-3)is presented. A modified version of the proposed LARES mission is examined.

  3. Improved pulse laser ranging algorithm based on high speed sampling

    Science.gov (United States)

    Gao, Xuan-yi; Qian, Rui-hai; Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; He, Shi-jie; Guo, Xiao-kang

    2016-10-01

    Narrow pulse laser ranging achieves long-range target detection using laser pulse with low divergent beams. Pulse laser ranging is widely used in military, industrial, civil, engineering and transportation field. In this paper, an improved narrow pulse laser ranging algorithm is studied based on the high speed sampling. Firstly, theoretical simulation models have been built and analyzed including the laser emission and pulse laser ranging algorithm. An improved pulse ranging algorithm is developed. This new algorithm combines the matched filter algorithm and the constant fraction discrimination (CFD) algorithm. After the algorithm simulation, a laser ranging hardware system is set up to implement the improved algorithm. The laser ranging hardware system includes a laser diode, a laser detector and a high sample rate data logging circuit. Subsequently, using Verilog HDL language, the improved algorithm is implemented in the FPGA chip based on fusion of the matched filter algorithm and the CFD algorithm. Finally, the laser ranging experiment is carried out to test the improved algorithm ranging performance comparing to the matched filter algorithm and the CFD algorithm using the laser ranging hardware system. The test analysis result demonstrates that the laser ranging hardware system realized the high speed processing and high speed sampling data transmission. The algorithm analysis result presents that the improved algorithm achieves 0.3m distance ranging precision. The improved algorithm analysis result meets the expected effect, which is consistent with the theoretical simulation.

  4. Picosecond sources for sub-centimeter laser ranging

    Science.gov (United States)

    Krebs, Danny J.; Dallas, Joseph; Seery, Bernard D.

    1992-01-01

    Some of the tradeoffs involved in selecting a laser source for space-based laser ranging are outlined, and some of the recent developments in the laser field most relevant to space-based lasers for ranging and altimetry are surveyed. Laser pulse width and laser design are discussed. It is argued that, while doubled/tripled ND-host lasers are currently the best choice for laser ranging in two colors, they have the shortcoming that the atmospheric transmission at 355 nm is significantly poorer than it is at longer wavelengths which still have sufficient dispersion for two-color laser ranging. The life requirement appears to demand that laser diode pumping be used for space applications.

  5. High speed sampling circuit design for pulse laser ranging

    Science.gov (United States)

    Qian, Rui-hai; Gao, Xuan-yi; Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; Guo, Xiao-kang; He, Shi-jie

    2016-10-01

    In recent years, with the rapid development of digital chip, high speed sampling rate analog to digital conversion chip can be used to sample narrow laser pulse echo. Moreover, high speed processor is widely applied to achieve digital laser echo signal processing algorithm. The development of digital chip greatly improved the laser ranging detection accuracy. High speed sampling and processing circuit used in the laser ranging detection system has gradually been a research hotspot. In this paper, a pulse laser echo data logging and digital signal processing circuit system is studied based on the high speed sampling. This circuit consists of two parts: the pulse laser echo data processing circuit and the data transmission circuit. The pulse laser echo data processing circuit includes a laser diode, a laser detector and a high sample rate data logging circuit. The data transmission circuit receives the processed data from the pulse laser echo data processing circuit. The sample data is transmitted to the computer through USB2.0 interface. Finally, a PC interface is designed using C# language, in which the sampling laser pulse echo signal is demonstrated and the processed laser pulse is plotted. Finally, the laser ranging experiment is carried out to test the pulse laser echo data logging and digital signal processing circuit system. The experiment result demonstrates that the laser ranging hardware system achieved high speed data logging, high speed processing and high speed sampling data transmission.

  6. Calibration of Short Range 2D Laser Range Finder for 3D SLAM Usage

    OpenAIRE

    Petr Olivka; Michal Krumnikl; Pavel Moravec; David Seidl

    2016-01-01

    The laser range finder is one of the most essential sensors in the field of robotics. The laser range finder provides an accurate range measurement with high angular resolution. However, the short range scanners require an additional calibration to achieve the abovementioned accuracy. The calibration procedure described in this work provides an estimation of the internal parameters of the laser range finder without requiring any special three-dimensional targets. This work presents the use of...

  7. Testing Lorentz symmetry with Lunar Laser Ranging

    CERN Document Server

    Bourgoin, A; Bouquillon, S; Poncin-Lafitte, C Le; Francou, G; Angonin, M -C

    2016-01-01

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both General Relativity (GR) and the Standard Model of particle physics called the Standard-Model Extension (SME). We present new constraints on pure gravity SME coefficients obtained by analyzing Lunar Laser Ranging (LLR) observations. We use a new numerical lunar ephemeris computed in the SME framework and we perform a LLR data analysis using a set of 20721 normal points covering the period August 1969 to December 2013. We emphasize that linear combination of SME coefficients to which LLR data are sensitive are not the same as those fitted in previous post-fit residuals analysis using LLR observations and based on theoretical grounds. We found no evidence for Lorentz violation at the level of $10^{-8}$ for $\\bar{s}^{TX}$, $10^{-12}$ for $\\bar{s}^{XY}$ and $\\bar{s}^{XZ}$, $10^{-11}$ for $\\bar{s}^{XX}-\\bar{s}^{YY}$ and $\\bar{s}^{XX}+\\bar{s}^{YY}-2\\bar{s}^{ZZ}-0.045\\bar{s}^{YZ}$ and $10^{-9}$ for $\\bar{s}^{TY}+...

  8. Testing Lorentz Symmetry with Lunar Laser Ranging

    Science.gov (United States)

    Bourgoin, A.; Hees, A.; Bouquillon, S.; Le Poncin-Lafitte, C.; Francou, G.; Angonin, M.-C.

    2016-12-01

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both general relativity and the standard model of particle physics called the standard-model extension (SME). We present new constraints on pure gravity SME coefficients obtained by analyzing lunar laser ranging (LLR) observations. We use a new numerical lunar ephemeris computed in the SME framework and we perform a LLR data analysis using a set of 20 721 normal points covering the period of August, 1969 to December, 2013. We emphasize that linear combination of SME coefficients to which LLR data are sensitive and not the same as those fitted in previous postfit residuals analysis using LLR observations and based on theoretical grounds. We found no evidence for Lorentz violation at the level of 10-8 for s¯T X, 10-12 for s¯X Y and s¯X Z, 10-11 for s¯X X-s¯Y Y and s¯X X+s¯Y Y-2 s¯Z Z-4.5 s¯Y Z, and 10-9 for s¯T Y+0.43 s¯T Z. We improve previous constraints on SME coefficient by a factor up to 5 and 800 compared to postfit residuals analysis of respectively binary pulsars and LLR observations.

  9. Relativity Parameters Determined from Lunar Laser Ranging

    Science.gov (United States)

    Williams, J. G.; Newhall, X. X.; Dickey, J. O.

    1996-01-01

    Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5 x 10(exp -13) . This limit, combined with an independent determination of y from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8(beta) + 1.4(gamma) can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both 6 and y match the values of general relativity to within 0.005, and the linear combination beta+ gamma matches to within 0,003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with absolute value of G/G less than or equal to 8 x lO(exp -12)/yr. There is significant sensitivity to G/G through solar perturbations on the lunar orbit.

  10. Relativity Parameters Determined from Lunar Laser Ranging

    Science.gov (United States)

    Williams, J. G.; Newhall, X. X.; Dickey, J. O.

    1996-01-01

    Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5 x 10(exp -13) . This limit, combined with an independent determination of y from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8(beta) + 1.4(gamma) can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both 6 and y match the values of general relativity to within 0.005, and the linear combination beta+ gamma matches to within 0,003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with absolute value of G/G less than or equal to 8 x lO(exp -12)/yr. There is significant sensitivity to G/G through solar perturbations on the lunar orbit.

  11. Experimental Validation of Ship Identification with a Laser Range Profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Pace, P.; Bekman, H.H.P.T.; Putten, F.J.M. van; Schleijpen, H.M.A.

    2008-01-01

    Naval operations in the littoral have to deal with threats at short range in cluttered environments with both neutral and hostile targets. There is a need for fast identification, which is possible with a laser range profiler. Additionally, in a coastal-surveillance scenario a laser range profiler

  12. Design of high-precision ranging system for laser fuze

    Science.gov (United States)

    Chen, Shanshan; Zhang, He; Xu, Xiaobin

    2016-10-01

    According to the problem of the high-precision ranging in the circumferential scanning probe laser proximity fuze, a new type of pulsed laser ranging system has been designed. The laser transmitting module, laser receiving module and ranging processing module have been designed respectively. The factors affecting the ranging accuracy are discussed. And the method of improving the ranging accuracy is studied. The high-precision ranging system adopts the general high performance microprocessor C8051FXXX as the core. And the time interval measurement chip TDC-GP21 was used to implement the system. A PCB circuit board was processed to carry on the experiment. The results of the experiment prove that a centimeter level accuracy ranging system has been achieved. The works can offer reference for ranging system design of the circumferential scanning probe laser proximity fuze.

  13. Proceedings of the first JAERI-Kansai international workshop on ultrashort-pulse ultrahigh-power lasers and simulation for laser-plasma interactions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Records of the First JAERI-Kansai International Workshop, which focused on the subject of `Ultrashort-Pulse Ultrahigh-Power Lasers and Simulation for Laser-Plasma Interactions`, are contained in this issue. The First JAERI-Kansai International Workshop was held as Joint ICFA/JAERI-Kansai International Workshop `97 with International Committee for Future Accelerators (ICFA). This report consists of 24 contributed papers. (J.P.N.)

  14. The solid state detector technology for picosecond laser ranging

    Science.gov (United States)

    Prochazka, Ivan

    1993-01-01

    We developed an all solid state laser ranging detector technology, which makes the goal of millimeter accuracy achievable. Our design and construction philosophy is to combine the techniques of single photon ranging, ultrashort laser pulses, and fast fixed threshold discrimination while avoiding any analog signal processing within the laser ranging chain. The all solid state laser ranging detector package consists of the START detector and the STOP solid state photon counting module. Both the detectors are working in an optically triggered avalanche switching regime. The optical signal is triggering an avalanche current buildup which results in the generation of a uniform, fast risetime output pulse.

  15. 6th International Workshop on Application of Lasers in Atomic Nuclei Research

    CERN Document Server

    Błaszczak, Z; Marinova, K; LASER 2004

    2006-01-01

    6th International Workshop on Application of Lasers in Atomic Nuclei Research, LASER 2004, held in Poznan, Poland, 24-27 May, 2004 Researchers and graduate students interested in the Mössbauer Effect and its applications will find this volume indispensable. The volume presents the most recent developments in the methodology of Mössbauer spectroscopy. Reprinted from Hyperfine Interactions (HYPE) Volume 162, 1-4

  16. Range-Gated Laser Stroboscopic Imaging for Night Remote Surveillance

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-Wei; ZHOU Yan; FAN Song-Tao; HE Jun; LIU Yu-Liang

    2010-01-01

    @@ For night remote surveillance,we present a method,the range-gated laser stroboscopic imaging(RGLSI),which uses a new kind of time delay integration mode to integrate target signals so that night remote surveillance can be realized by a low-energy illuminated laser.The time delay integration in this method has no influence on the video frame rate.

  17. Threshold Determination and Analysis of Laser Pulse Range Finder

    Institute of Scientific and Technical Information of China (English)

    殷聪; 韩绍坤; 刘巽亮; 张化朋; 赵跃进

    2003-01-01

    Under different conditions, the highest detection probability should be acquired while receiving laser echo during laser pulse range finding. The threshold voltage of the signal detection can be set corresponding to different conditions by using resistor network. As a feedback loop, automatic noise threshold circuit could change the threshold voltage following the noise level. The threshold can track the noise closely, rapidly and accurately by adopting this combination. Therefore, the receiving capability of laser echo receiving system will be maximized, and it can detect weaker laser pulse from noise.

  18. Atmospheric Error Correction of the Laser Beam Ranging

    Directory of Open Access Journals (Sweden)

    J. Saydi

    2014-01-01

    Full Text Available Atmospheric models based on surface measurements of pressure, temperature, and relative humidity have been used to increase the laser ranging accuracy by ray tracing. Atmospheric refraction can cause significant errors in laser ranging systems. Through the present research, the atmospheric effects on the laser beam were investigated by using the principles of laser ranging. Atmospheric correction was calculated for 0.532, 1.3, and 10.6 micron wavelengths through the weather conditions of Tehran, Isfahan, and Bushehr in Iran since March 2012 to March 2013. Through the present research the atmospheric correction was computed for meteorological data in base of monthly mean. Of course, the meteorological data were received from meteorological stations in Tehran, Isfahan, and Bushehr. Atmospheric correction was calculated for 11, 100, and 200 kilometers laser beam propagations under 30°, 60°, and 90° rising angles for each propagation. The results of the study showed that in the same months and beam emission angles, the atmospheric correction was most accurate for 10.6 micron wavelength. The laser ranging error was decreased by increasing the laser emission angle. The atmospheric correction with two Marini-Murray and Mendes-Pavlis models for 0.532 nm was compared.

  19. Detection performance of laser range-gated imaging system

    Science.gov (United States)

    Xu, Jun; Li, Xiaofeng; Luo, Jijun; Zhang, Shengxiu; Xu, Yibin

    2010-10-01

    Laser radar is rapidly developing towards very capable sensors for number of applications such as military sensing and guidance, auto collision avoidance, robotic vision and atmospheric sensing. In this paper, the detection performance of non-scanned Laser Rang-gated (LRG) imaging system is studied. In order to compute the detection range of laser active imaging system, the range equation is derived by using laser illuminating model and considering factors which affect system imaging quality. According to the principle of laser radar and the characters of objects and the detectors in special applied setting, it mainly deduced the non-scanned laser radar range equation of the range-gated system, meanwhile, the SNR model of non-scanned LRG imaging system is set up. Then, relationship of the detection probability, the false alarm probability and the signal-to-noise ratio in the non-scanned LRG imaging system are analyzed, the influence factors of system's performance are pointed out, and the solution is proposed. The detection performance simulation software of non-scanned LRG imaging system is designed with MATLAB and the performance of the imaging system is simulated.

  20. Calibration of Short Range 2D Laser Range Finder for 3D SLAM Usage

    Directory of Open Access Journals (Sweden)

    Petr Olivka

    2016-01-01

    Full Text Available The laser range finder is one of the most essential sensors in the field of robotics. The laser range finder provides an accurate range measurement with high angular resolution. However, the short range scanners require an additional calibration to achieve the abovementioned accuracy. The calibration procedure described in this work provides an estimation of the internal parameters of the laser range finder without requiring any special three-dimensional targets. This work presents the use of a short range URG-04LX scanner for mapping purposes and describes its calibration. The precision of the calibration was checked in an environment with known ground truth values and the results were statistically evaluated. The benefits of the calibration are also demonstrated in the practical applications involving the segmentation of the environment. The proposed calibration method is complex and detects all major manufacturing inaccuracies. The procedure is suitable for easy integration into the current manufacturing process.

  1. Satellite laser ranging experiment with sub-centimeter single-shot ranging precision at Shanghai Observatory

    Institute of Scientific and Technical Information of China (English)

    YANG; Fumin(杨福民); CHEN; Wanzhen(陈婉珍); ZHANG; Zhongping(张忠萍); CHEN; Juping(陈菊平); HU; Jingfu(扈荆夫); LI; Xin(李鑫); I.; Prochazka; K.; Hamal

    2003-01-01

    The Shanghai Astronomical Observatory, Chinese Academy of Sciences, incollaboration with the Czech Technical University, carried out the experiment of satellite laser ranging with sub-centimeter precision in Shanghai in August 2001. A pico-second event timer was used for the measurement of the time interval between the transmitted and returned laser pulses for Lageos 1, 2, Starlette, Stella, Topex/Poseiden and ERS-2 in coordination with the existing laser transmitting and receiving system at the Shanghai Observatory. The analysis of the measurement showed that the single-shot ranging precision with these satellites is 7-8 mm. In order to compare ranging precision, the existing ranging system has tracked simultaneously these satellites and obtained the ranging precision of 12-15 mm. It means that the ranging precision with the new system is 80% better thanthe existing system. The systematic biases with the existing system have also been checked in the experiment.

  2. Identification of Littoral Targets with a Laser Range Profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Bekman, H.H.P.T.; Putten, F.J.M. van; Cohen, L.H.

    2007-01-01

    Naval operations in the littoral have to deal with threats at short range in cluttered environments with both neutral and hostile targets. On board naval vessels there is a need for fast identification, which is possible with a laser range profiler. Additionally, in a coast-surveillance scenario a

  3. RESEARCH ON LASER RANGE SCANNING AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper the development of the technology of the laserscanning is summarized.The principles of laser range scanning are introduced.Based on the laser scanning technology and methods,which are investigated by the authors to survey deposit volume,a surveying system is developed and a practical application is performed.It is shown that the laser-scanning technology has obvious advantages such as measurement precision,automation and visualization of observed data in comparison with the traditional methods.As a result,labor intensity is relieved obviously and work efficiency is promoted.

  4. Compact-range coordinate system established using a laser tracker.

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, Floyd H.; Bryce, Edwin Anthony

    2006-12-01

    Establishing a Cartesian coordinate reference system for an existing Compact Antenna Range using the parabolic reflector is presented. A SMX (Spatial Metrix Corporation) M/N 4000 laser-based coordinate measuring system established absolute coordinates for the facility. Electric field characteristics with positional movement correction are evaluated. Feed Horn relocation for alignment with the reflector axis is also described. Reference points are established for follow-on non-laser alignments utilizing a theodolite.

  5. Use of laser range finders and range image analysis in automated assembly tasks

    Science.gov (United States)

    Alvertos, Nicolas; Dcunha, Ivan

    1990-01-01

    A proposition to study the effect of filtering processes on range images and to evaluate the performance of two different laser range mappers is made. Median filtering was utilized to remove noise from the range images. First and second order derivatives are then utilized to locate the similarities and dissimilarities between the processed and the original images. Range depth information is converted into spatial coordinates, and a set of coefficients which describe 3-D objects is generated using the algorithm developed in the second phase of this research. Range images of spheres and cylinders are used for experimental purposes. An algorithm was developed to compare the performance of two different laser range mappers based upon the range depth information of surfaces generated by each of the mappers. Furthermore, an approach based on 2-D analytic geometry is also proposed which serves as a basis for the recognition of regular 3-D geometric objects.

  6. International Laser Ranging Service (ILRS): Terms of Reference

    Science.gov (United States)

    Husson, Van; Noll, Carey

    2000-01-01

    The International Laser Ranging Service (ILRS) is an established Service within Section II , Advanced Space Technology, of the International Association of Geodesy (IAG). The primary objective of the ILRS is to provide a service to support, through Satellite and Lunar Laser Ranging data and related products, geodetic and geophysical research activities as well as International Earth Rotation Service (IERS) products important to the maintenance of an accurate International Terrestrial Reference Frame (ITRF). The service also develops the necessary standards/specifications and encourages international adherence to its conventions.

  7. Laser-Ranging Long Baseline Differential Atom Interferometers for Space

    CERN Document Server

    Chiow, Sheng-wey; Yu, Nan

    2015-01-01

    High sensitivity differential atom interferometers are promising for precision measurements in science frontiers in space, including gravity field mapping for Earth science studies and gravitational wave detection. We propose a new configuration of twin atom interferometers connected by a laser ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and a means to phase-lock the two independent interferometer lasers over long distances, thereby further enhancing the feasibility of long baseline differential atom interferometers. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential atom interferometer measurement system. LRI-AI isolates the laser requirements for atom interferometers and for optical phase readout between distant locations, thus enabling optimized allocation of available laser power within a limited physical size and resource budget. A unique aspect of LRI-AI also enables...

  8. Laser Meter of Atmospheric Inhomogeneity Properties in UV Spectral Range

    Directory of Open Access Journals (Sweden)

    S. E. Ivanov

    2015-01-01

    Full Text Available Development of laser systems designed to operate in conditions of the terrestrial atmosphere demands reliable information about the atmosphere condition. The aerosol lidars for operational monitoring of the atmosphere allow us to define remotely characteristics of atmospheric aerosol and cloudy formations in the atmosphere.Today the majority of aerosol lidars run in the visible range. However, in terms of safety (first of all to eyes also ultra-violet (UF range is of interest. A range of the wavelengths of the harmful effect on the eye retina is from 0.38 to 1.4 mμ. Laser radiation with the wavelengths less than 0.38 mμ and over 1.4 mμ influences the anterior ambient of an eye and is safer, than laser radiation with the wavelengths of 0.38 – 1.4 mμ.The paper describes a laser meter to measure characteristics of atmospheric inhomogeneity propertis in UF spectral range at the wavelength of 0.355 mμ.As a radiation source, the meter uses a semiconductor-pumped pulse solid-state Nd:YAG laser. As a receiving lens, Kassegren's scheme-implemented mirror lens with a socket to connect optical fibre is used in the laser meter. Radiation from the receiving lens is transported through the optical fibre to the optical block. The optical block provides spectral selection of useful signal and conversion of optical radiation into electric signal.To ensure a possibility for alignment of the optical axes of receiving lens and laser radiator the lens is set on the alignment platform that enables changing lens inclination and turn with respect to the laser.The software of the laser meter model is developed in the NI LabVIEW 2012 graphic programming environment.The paper gives the following examples: a typical laser echo signal, which is back scattered by the atmosphere and spatiotemporal distribution of variation coefficient of the volumetric factor of the back scattered atmosphere. Results of multi-day measurements show that an extent of the recorded aerosol

  9. Observing tectonic plate motions and deformations from satellite laser ranging

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

    1985-01-01

    The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

  10. Laser-guide-stars used for cophasing broad capture ranges

    CERN Document Server

    Martinez,

    2016-01-01

    Segmented primary mirrors are indispensable to master the steady increase in spatial resolution. Phasing optics systems must reduce segment misalignments to guarantee the high optical quality required for astronomical science programs. Modern telescopes routinely use adaptive optics systems to compensate for the atmosphere and use laser-guide-stars to create artificial stars as bright references in the field of observation. Because multiple laser-guide-star adaptive optics are being implemented in all major observatories, we propose to use man-made stars not only for adaptive optics, but for phasing optics. We propose a method called the doublet-wavelength coherence technique (DWCT), exploiting the D lines of sodium in the mesosphere using laser guide-stars. The signal coherence properties are then used. The DWCT capture range exceeds current abilities by a factor of 100. It represents a change in paradigm by improving the phasing optics capture range from micrometric to millimetric. It thereby potentially el...

  11. Observing tectonic plate motions and deformations from satellite laser ranging

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

    1985-01-01

    The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

  12. 7th International Workshop on Application of Lasers in Atomic Nuclei Research “Nuclear Ground and Isometric State Properties”

    CERN Document Server

    Błaszczak, Z; Marinova, K; LASER 2006

    2007-01-01

    7th International Workshop on Application of Lasers in Atomic Nuclei Research, LASER 2004, held in Poznan, Poland, May 29-June 01, 2006 Researchers and PhD students interested in recent results in the nuclear structure investigation by laser spectroscopy, the progress of the experimental technique and the future developments in the field will find this volume indispensable. Reprinted from Hyperfine Interactions (HYPE) Volume ???

  13. A Comparison of Close-Range Photogrammetry to Terrestrial Laser ...

    African Journals Online (AJOL)

    Julian Smit

    In a separate process a laser scanner was used to scan the ... image photography is widely accepted as the optimal method in close-range .... Once the interest points have been determined by convolution in the x- and y- directions, they.

  14. Location Of A Vehicle With A Laser Range Finder

    Science.gov (United States)

    Zhao, C. J.; Monchaud, S.; Marce, L.; Julliere, M.

    1984-02-01

    Absolute location of a mobile robot is necessary to improve the autonomy of vehicle built for hostile environments. We are developing a scanning laser range finder based on triangulation to get range data about the edges of a cylindrical polyhedral world. From the matching between the measurements and data computed from a model of the a priori known environment, the position of the robot is deduced accurately.

  15. Speckle phase noise in coherent laser ranging: fundamental precision limitations.

    Science.gov (United States)

    Baumann, Esther; Deschênes, Jean-Daniel; Giorgetta, Fabrizio R; Swann, William C; Coddington, Ian; Newbury, Nathan R

    2014-08-15

    Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR, or any coherent LADAR, to a diffusely scattering surface will be determined by the unavoidable speckle phase noise. Here, we demonstrate the two main manifestations of this limit. First, frequency-dependent speckle phase noise leads to a non-Gaussian range distribution having outliers that approach the system range resolution, regardless of the signal-to-noise ratio. These outliers are reduced only through improved range resolution (i.e., higher optical bandwidths). Second, if the range is measured during a continuous lateral scan across a surface, the spatial pattern of speckle phase is converted to frequency noise, which leads to additional excess range uncertainty. We explore these two effects and show that laboratory results agree with analytical expressions and numerical simulations. We also show that at 1 THz optical bandwidth, range precisions below 10 μm are achievable regardless of these effects.

  16. Study of pseudo noise CW diode laser for ranging applications

    Science.gov (United States)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-11-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  17. Lunar Laser Ranging Experiment for Japanese SELENE-2 landing mission

    Science.gov (United States)

    Noda, H.; Kunimori, H.; Araki, H.; Fuse, T.; Hanada, H.; Katayama, M.; Otsubo, T.; Sasaki, S.; Tazawa, S.; Tsuruta, S.; Funazaki, K.; Taniguchi, H.; Murata, K.

    2012-04-01

    We present the development status of the Lunar Laser Ranging experiment proposed to Japanese SELENE-2 lunar landing mission. The Lunar Laser Ranging measures the distance between laser link stations on the Earth and retroreflectors on the Moon, by detecting the time of flight of photons of high-powered laser emitted from the ground station. Since the Earth-Moon distance contains information of lunar orbit, lunar solid tides, and lunar orientation and rotation, we can estimate the inner structure of the Moon through orientation, rotation and tide. Retroreflectors put by the Apollo and Luna missions in 1970's are arrays of many small Corner Cube Prisms (CCP). Because of the tilt of these arrays from the Earth direction due to the optical libration, the returned laser pulse is broaden, causing the main range error of more than 1.5 cm ([1]). Therefore retroreflectors with larger single aperture are necessary for more accurate ranging, and we propose a large single retroreflector of hollow-type with 15 cm aperture. Larger aperture up to 20 cm might be favorable if more mass is permitted for payloads. To cancel the velocity aberration, a large, single aperture retroreflector needs small amount of offset angle between the reflecting planes to spoil the return beam pattern. This angle offset, called Dihedral Angle Offset (DAO) must be optimized to be less than 1 second of arc with 0.1 seconds of arc accuracy to accumulate more photons [2, 3]. The realization of such small DAO is challenging with current technology, therefore the development of fabrication method is important. As for the mirror material, some ceramic products (ZPF: Zero-expansion Pore-free ceramics or SiC: silicon carbide) are under consideration in terms of weight, hardness and handling. The thermal quality of the material can be evaluated by both the thermal conductivity and the coefficient of thermal expansion. The method to fasten three planes each other with precise DAO must be developed.

  18. Note: Digital laser frequency auto-locking for inter-satellite laser ranging.

    Science.gov (United States)

    Luo, Yingxin; Li, Hongyin; Yeh, Hsien-Chi

    2016-05-01

    We present a prototype of a laser frequency auto-locking and re-locking control system designed for laser frequency stabilization in inter-satellite laser ranging system. The controller has been implemented on field programmable gate arrays and programmed with LabVIEW software. The controller allows initial frequency calibrating and lock-in of a free-running laser to a Fabry-Pérot cavity. Since it allows automatic recovery from unlocked conditions, benefit derives to automated in-orbit operations. Program design and experimental results are demonstrated.

  19. The proceedings of the 1st international workshop on laboratory astrophysics experiments with large lasers

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B.A.; Goldstein, W.H. [eds.

    1996-08-09

    The world has stood witness to the development of a number of highly sophisticated and flexible, high power laser facilities (energies up to 50 kJ and powers up to 50 TW), driven largely by the world-wide effort in inertial confinement fusion (ICF). The charter of diagnosing implosions with detailed, quantitative measurements has driven the ICF laser facilities to be exceedingly versatile and well equipped with diagnostics. Interestingly, there is considerable overlap in the physics of ICF and astrophysics. Both typically involve compressible radiative hydrodynamics, radiation transport, complex opacities, and equations of state of dense matter. Surprisingly, however, there has been little communication between these two communities to date. With the recent declassification of ICF in the USA, and the approval to commence with construction of the next generation ``superlasers``, the 2 MJ National Ignition Facility in the US, and its equivalent, the LMJ laser in France, the situation is ripe for change. . Given the physics similarities that exist between ICF and astrophysics, one strongly suspects that there should exist regions of overlap where supporting research on the large lasers could be beneficial to the astrophysics community. As a catalyst for discussions to this end, Lawrence Livermore National Laboratory sponsored this workshop. Approximately 100 scientists attended from around the world, representing eight countries: the USA, Canada, UK, France, Germany, Russia, Japan, and Israel. A total of 30 technical papers were presented. The two day workshop was divided into four sessions, focusing on nonlinear hydrodynamics, radiative hydrodynamics, radiation transport, and atomic physics-opacities. Copies of the presentations are contained in these proceedings.

  20. Laser beaming demonstrations at the Starfire Optical Range

    Energy Technology Data Exchange (ETDEWEB)

    Lipinski, R.J.; Meister, D.C.; Tucker, S. [Sandia National Labs., Albuquerque, NM (United States); Leatherman, P.; Fugate, R.Q.; Maes, C.; Lange, W.J.; Cowan, W. [Air Force Phillips Lab./LIG, Kirtland Air Force Base, NM (United States). Starfire Optical Range; Cleis, R.A.; Spinhirne, J.M. [Rockwell Power Systems, Albuquerque, NM (United States). Starfire Optical Range] [and others

    1995-03-01

    The ability to acquire, track, and accurately direct a laser beam to a satellite is crucial for power-beaming and laser-communications. To assess the state of the art in this area, a team consisting of Air Force Phillips Laboratory, Sandia National Laboratories, and COMSAT Corporation personnel performed some laser beaming demonstrations to various satellites. A ruby laser and a frequency-doubled YAG laser were used with the Phillips Lab Starfire Optical Range (SOR) beam director for this activity. The ruby laser projected 20 J in 6 ms out the telescope with a beam divergence that increased from 1.4 to 4 times the diffraction limit during that time. The doubled YAG projected 0.09 J in 10 ns at 20 Hz. The SOR team demonstrated the ability to move rapidly to a satellite, center it in the telescope, then lock onto it with the tracker, and establish illumination. Several low-earth-orbit satellites with corner-cube retro-reflectors were illuminated at ranges from 1000 to 6000 km with a beam divergence estimated to be about 20 {mu}radians. The return signal from the ruby laser was collected in a 15-cm telescope, detected by a photomultiplier tube, and recorded at 400 kHz. Rapid variations in intensity (as short at 15 {mu}s) were noted, which may be due to speckles caused by phase interference from light reflected from different retro-reflectors on the satellite. The return light from the YAG was collected by a 35-cm telescope and detected by an intensified CCD camera. The satellite brightened by about a factor of 30 in the sunlight when the laser was turned on, and dimmed back to normal when the 50-{mu}radian point-ahead was turned off. The satellite was illuminated at 1 Hz as it entered the earth`s shadow and followed for about 10 seconds in the shadow. In another demonstration, four neighboring GEO satellites were located and centered in succession with a 3.5-m telescope at a rate of about 16 seconds per satellite.

  1. Ranging with frequency-shifted feedback lasers: from μm-range accuracy to MHz-range measurement rate

    Science.gov (United States)

    Kim, J. I.; Ogurtsov, V. V.; Bonnet, G.; Yatsenko, L. P.; Bergmann, K.

    2016-12-01

    We report results on ranging based on frequency-shifted feedback (FSF) lasers with two different implementations: (1) An Ytterbium-fiber system for measurements in an industrial environment with accuracy of the order of 1 μm, achievable over a distance of the order of meters with potential to reach an accuracy of better than 100 nm; (2) A semiconductor laser system for a high rate of measurements with an accuracy of 2 mm @ 1 MHz or 75 μm @ 1 kHz and a limit of the accuracy of ≥10 μm. In both implementations, the distances information is derived from a frequency measurement. The method is therefore insensitive to detrimental influence of ambient light. For the Ytterbium-fiber system, a key feature is the injection of a single-frequency laser, phase modulated at variable frequency Ω, into the FSF-laser cavity. The frequency Ω_{max} at which the detector signal is maximal yields the distance. The semiconductor FSF-laser system operates without external injection seeding. In this case, the key feature is frequency counting that allows convenient choice of either accuracy or speed of measurements simply by changing the duration of the interval during which the frequency is measured by counting.

  2. Ranging with frequency-shifted feedback lasers: from $\\mu$m-range accuracy to MHz-range measurement rate

    CERN Document Server

    Kim, J I; Bonnet, G; Yatsenko, L P; Bergmann, K

    2016-01-01

    We report results on ranging based on frequency shifted feedback (FSF) lasers with two different implementations: (1) An Ytterbium-fiber system for measurements in an industrial environment with accuracy of the order of 1 $\\mu$m, achievable over a distance of the order of meters with potential to reach an accuracy of better than 100 nm; (2) A semiconductor laser system for a high rate of measurements with an accuracy of 2 mm @ 1 MHz or 75 $\\mu$m @ 1 kHz and a limit of the accuracy of $\\geq $ 10 $\\mu$m. In both implementations, the distances information is derived from a frequency measurement. The method is therefore insensitive to detrimental influence of ambient light. For the Ytterbium-fiber system a key feature is the injection of a single frequency laser, phase modulated at variable frequency $\\Omega$, into the FSF-laser cavity. The frequency $\\Omega_{max}$ at which the detector signal is maximal yields the distance. The semiconductor FSF laser system operates without external injection seeding. In this c...

  3. Current Trends and Challenges in Satellite Laser Ranging

    Science.gov (United States)

    Appleby, Graham M.; Bianco, Giuseppe; Noll, Carey E.; Pavlis, Erricos C.; Pearlman, Michael R.

    2016-12-01

    Satellite Laser Ranging (SLR) is used to measure accurately the distance from ground stations to retro-reflectors on satellites and on the Moon. SLR is one of the fundamental space-geodetic techniques that define the International Terrestrial Reference Frame (ITRF), which is the basis upon which many aspects of global change over space, time, and evolving technology are measured; with VLBI the two techniques define the scale of the ITRF; alone the SLR technique defines its origin (geocenter). The importance of the reference frame has recently been recognized at the inter-governmental level through the United Nations, which adopted in February 2015 the Resolution "Global Geodetic Reference Frame for Sustainable Development." Laser Ranging provides precision orbit determination and instrument calibration and validation for satellite-borne altimeters for the better understanding of sea level change, ocean dynamics, ice mass-balance, and terrestrial topography. It is also a tool to study the dynamics of the Moon and fundamental constants and theories. With the exception of the currently in-orbit GPS constellation, all GNSS satellites now carry retro-reflectors for improved orbit determination, harmonization of reference frames, and in-orbit co-location and system performance validation; the next generation of GPS satellites due for launch from 2019 onwards will also carry retro-reflectors. The ILRS delivers weekly realizations that are accumulated sequentially to extend the ITRF and the Earth Orientation Parameter series with a daily resolution. SLR technology continues to evolve towards the next-generation laser ranging systems and it is expected to successfully meet the challenges of the GGOS2020 program for a future Global Space Geodetic Network. Ranging precision is improving as higher repetition rate, narrower pulse lasers, and faster detectors are implemented within the network. Automation and pass interleaving at some stations is expanding temporal coverage and

  4. A picosecond resolution Time Digitizer for laser ranging

    Science.gov (United States)

    Turko, B.

    1978-01-01

    The Time Digitizer capable of covering a range of 0.34 sec in 9.76 psec increments is described. The time interval between a pair of start-stop pulses is digitized coarsely in 20 nsec periods by a very accurate 50 MHz reference clock. The residual fractions of a clock period at the start and the stop end of the measured interval are stretched in two interpolators and digitized in 9.76 psec increments. An equivalent digitizing frequency of 102.4 GHz is thus achieved. The digitizer is built in a minicrate and communicates via a standard crate controller. It is intended for use in the laser ranging between ground stations and the Laser Geodetic Satellite (LAGEOS). It is shown that the distribution in any two adjacent 9.76 psec channels of a small number of identical test time intervals is essentially binomial. The performance of the digitizer and test results are given.

  5. Modeling and Analysis of the APOLLO Lunar Laser Ranging Data

    CERN Document Server

    Reasenberg, R D; Colmenares, N R; Johnson, N H; Murphy, T W; Shapiro, I I

    2016-01-01

    The Earth-Moon-Sun system has traditionally provided the best laboratory for testing the strong equivalence principle. For a decade, the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) has been producing the world's best lunar laser ranging data. At present, a single observing session of about an hour yields a distance measurement with uncertainty of about 2~mm, an order of magnitude advance over the best pre-APOLLO lunar laser ranging data. However, these superb data have not yet yielded scientific results commensurate with their accuracy, number, and temporal distribution. There are two reasons for this. First, even in the relatively clean environment of the Earth-Moon system, a large number of effects modify the measured distance importantly and thus need to be included in the analysis model. The second reason is more complicated. The traditional problem with the analysis of solar-system metric data is that the physical model must be truncated to avoid extra parameters that would increase t...

  6. Probing General Relativity and New Physics with Lunar Laser Ranging

    Science.gov (United States)

    Dell'Agnello, S.; Maiello, M.; Currie, D. G.; Boni, A.; Berardi, S.; Cantone, C.; Delle Monache, G. O.; Intaglietta, N.; Lops, C.; Garattini, M.; Martini, M.; Patrizi, G.; Porcelli, L.; Tibuzzi, M.; Vittori, R.; Bianco, G.; Coradini, A.; Dionisio, C.; March, R.; Bellettini, G.; Tauraso, R.; Chandler, J.

    2012-11-01

    Over the past 40 years, Lunar Laser Ranging (LLR, developed by the Univ. of Maryland (PI) and INFN-LNF (Co-PI)) to the Apollo Cube Corner Retroreflector (CCR) arrays have supplied almost all the significant tests of General Relativity (Currie et al., 2009 [12]). LLR can evaluate the PPN (Post Newtonian Parameters), addressing this way both the possible changes in the gravitational constant and the self-energy properties of the gravitational field. In addition, the LLR has provided significant information on the composition and origin of the Moon. This is the only Apollo experiment that is still in operation. Initially the Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Over the decades, the ranging capabilities of the ground stations have improved by more than two orders of magnitude. Now, because of the lunar librations, the existing Apollo retroreflector arrays contribute a significant fraction of the limiting errors in the range measurements. We built a new experimental apparatus (the ‘Satellite/Lunar Laser Ranging Characterization Facility', SCF) and created a new test procedure (the SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of cube corner laser retroreflectors in space for industrial and scientific applications (Dell'Agnello et al., 2011 [13]). Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of the SLR retroreflector payload under thermal conditions produced with a close-match solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time movement of the payload to experimentally simulate satellite orientation on orbit with respect to both solar illumination and laser interrogation beams. These unique capabilities provide experimental validation of the space segment for SLR and Lunar Laser Ranging (LLR). The

  7. Probing General Relativity and New Physics with Lunar Laser Ranging

    Energy Technology Data Exchange (ETDEWEB)

    Dell' Agnello, S. [Laboratori Nazionali di Frascati (LNF) dell' INFN, Frascati, Rome (Italy); Maiello, M., E-mail: mauro.maiello@lnf.infn.it [Laboratori Nazionali di Frascati (LNF) dell' INFN, Frascati, Rome (Italy); Currie, D.G. [University of Maryland (UMD), College Park, MD (United States); Boni, A.; Berardi, S.; Cantone, C.; Delle Monache, G.O.; Intaglietta, N.; Lops, C.; Garattini, M.; Martini, M.; Patrizi, G.; Porcelli, L.; Tibuzzi, M. [Laboratori Nazionali di Frascati (LNF) dell' INFN, Frascati, Rome (Italy); Vittori, R. [Aeronautica Militare Italiana (AMI), Rome (Italy); Agenzia Spaziale Italiana (ASI), Rome (Italy); Bianco, G. [ASI-Centro di Geodesia Spaziale, Matera (Italy); Coradini, A. [INAF-Istituto di Fisica dello Spazio Interplanetario (IFSI), Via Fosso del Cavaliere 100, 00133 Rome (Italy); Dionisio, C. [Rheinmetall Italia S.p.A., Via Affile 102, 00131 Rome (Italy); March, R. [INFN-LNF and CNR-Istituto per le Applicazioni del Calcolo (IAC), Viale del Policlinico 137, 00161 Rome (Italy); Bellettini, G. [INFN-LNF and Department of Mathematics, University of Rome ' Tor Vergata' , Via della Ricerca Scientifica, 00133 Rome (Italy); and others

    2012-11-11

    Over the past 40 years, Lunar Laser Ranging (LLR, developed by the Univ. of Maryland (PI) and INFN-LNF (Co-PI)) to the Apollo Cube Corner Retroreflector (CCR) arrays have supplied almost all the significant tests of General Relativity (Currie et al., 2009 [12]). LLR can evaluate the PPN (Post Newtonian Parameters), addressing this way both the possible changes in the gravitational constant and the self-energy properties of the gravitational field. In addition, the LLR has provided significant information on the composition and origin of the Moon. This is the only Apollo experiment that is still in operation. Initially the Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Over the decades, the ranging capabilities of the ground stations have improved by more than two orders of magnitude. Now, because of the lunar librations, the existing Apollo retroreflector arrays contribute a significant fraction of the limiting errors in the range measurements. We built a new experimental apparatus (the 'Satellite/Lunar Laser Ranging Characterization Facility', SCF) and created a new test procedure (the SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of cube corner laser retroreflectors in space for industrial and scientific applications (Dell'Agnello et al., 2011 [13]). Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of the SLR retroreflector payload under thermal conditions produced with a close-match solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time movement of the payload to experimentally simulate satellite orientation on orbit with respect to both solar illumination and laser interrogation beams. These unique capabilities provide experimental validation of the space segment for SLR and Lunar Laser Ranging

  8. MOONLIGHT: A NEW LUNAR LASER RANGING RETROREFLECTOR INSTRUMENT

    Directory of Open Access Journals (Sweden)

    M. Garattini

    2013-12-01

    Full Text Available Since 1969 Lunar Laser Ranging (LLR to the Apollo Cube Corner Reflector (CCR arrays has supplied several significant tests of gravity: Geodetic Precession, the Strong and Weak Equivalence Principle (SEP, WEP, the Parametrized Post Newtonian (PPN parameter , the time change of the Gravitational constant (G, 1/r2 deviations and new gravitational theories beyond General Relativity (GR, like the unified braneworld theory (G. Dvali et al., 2003. Now a new generation of LLR can do better using evolved laser retroreflectors, developed from tight collaboration between my institution, INFN–LNF (Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali di Frascati, and Douglas Currie (University of Maryland, USA, one of the fathers of LLR. The new lunar CCR is developing and characterizing at the “Satellite/Lunar laser ranging Characterization Facility” (SCF, in Frascati, performing our new industry standard space test procedure, the “SCF-Test”; this work contains the experimental results of the SCF-Test applied to the new lunar CCR, and all the new payload developments, including the future SCF tests. The International Lunar Network (ILN research project considers our new retroreflector as one of the possible “Core Instruments”

  9. Laser Ranging to the Lost Lunokhod~1 Reflector

    CERN Document Server

    Murphy, T W; Battat, J B R; Hoyle, C D; Johnson, N H; McMillan, R J; Michelsen, E L; Stubbs, C W; Swanson, H E

    2011-01-01

    In 1970, the Soviet Lunokhod 1 rover delivered a French-built laser reflector to the Moon. Although a few range measurements were made within three months of its landing, these measurements---and any that may have followed---are unpublished and unavailable. The Lunokhod 1 reflector was, therefore, effectively lost until March of 2010 when images from the Lunar Reconnaissance Orbiter (LRO) provided a positive identification of the rover and determined its coordinates with uncertainties of about 100 m. This allowed the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) to quickly acquire a laser signal. The reflector appears to be in excellent condition, delivering a signal roughly four times stronger than its twin reflector on the Lunokhod 2 rover. The Lunokhod 1 reflector is especially valuable for science because it is closer to the Moon's limb than any of the other reflectors and, unlike the Lunokhod 2 reflector, we find that it is usable during the lunar day. We report the selenographic positi...

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

    Science.gov (United States)

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

    2016-07-08

    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.

  11. 3D sensor for indirect ranging with pulsed laser source

    Science.gov (United States)

    Bronzi, D.; Bellisai, S.; Villa, F.; Scarcella, C.; Bahgat Shehata, A.; Tosi, A.; Padovini, G.; Zappa, F.; Tisa, S.; Durini, D.; Weyers, S.; Brockherde, W.

    2012-10-01

    The growing interest for fast, compact and cost-effective 3D ranging imagers for automotive applications has prompted to explore many different techniques for 3D imaging and to develop new system for this propose. CMOS imagers that exploit phase-resolved techniques provide accurate 3D ranging with no complex optics and are rugged and costeffective. Phase-resolved techniques indirectly measure the round-trip return of the light emitted by a laser and backscattered from a distant target, computing the phase delay between the modulated light and the detected signal. Singlephoton detectors, with their high sensitivity, allow to actively illuminate the scene with a low power excitation (less than 10W with diffused daylight illumination). We report on a 4x4 array of CMOS SPAD (Single Photon Avalanche Diodes) designed in a high-voltage 0.35 μm CMOS technology, for pulsed modulation, in which each pixel computes the phase difference between the laser and the reflected pulse. Each pixel comprises a high-performance 30 μm diameter SPAD, an analog quenching circuit, two 9 bit up-down counters and memories to store data during the readout. The first counter counts the photons detected by the SPAD in a time window synchronous with the laser pulse and integrates the whole echoed signal. The second counter accumulates the number of photon detected in a window shifted with respect to the laser pulse, and acquires only a portion of the reflected signal. The array is readout with a global shutter architecture, using a 100 MHz clock; the maximal frame rate is 3 Mframe/s.

  12. Coherent Laser Instrument Would Measure Range and Velocity

    Science.gov (United States)

    Chang, Daniel; Cardell, Greg; San Martin, Alejandro; Spiers, Gary

    2005-01-01

    A proposed instrument would project a narrow laser beam that would be frequency-modulated with a pseudorandom noise (PN) code for simultaneous measurement of range and velocity along the beam. The instrument performs these functions in a low mass, power, and volume package using a novel combination of established techniques. Originally intended as a low resource- footprint guidance sensor for descent and landing of small spacecraft onto Mars or small bodies (e.g., asteroids), the basic instrument concept also lends itself well to a similar application guiding aircraft (especially, small unmanned aircraft), and to such other applications as ranging of topographical features and measuring velocities of airborne light-scattering particles as wind indicators. Several key features of the instrument s design contribute to its favorable performance and resource-consumption characteristics. A laser beam is intrinsically much narrower (for the same exit aperture telescope or antenna) than a radar beam, eliminating the need to correct for the effect of sloping terrain over the beam width, as is the case with radar. Furthermore, the use of continuous-wave (CW), erbium-doped fiber lasers with excellent spectral purity (narrow line width) permits greater velocity resolution, while reducing the laser s power requirement compared to a more typical pulsed solid-state laser. The use of CW also takes proper advantage of the increased sensitivity of coherent detection, necessary in the first place for direct measurement of velocity using the Doppler effect. However, measuring range with a CW beam requires modulation to "tag" portions of it for time-of-flight determination; typically, the modulation consists of a PN code. A novel element of the instrument s design is the use of frequency modulation (FM) to accomplish both the PN-modulation and the Doppler-bias frequency shift necessary for signed velocity measurements. This permits the use of a single low-power waveguide electrooptic

  13. Advanced computer graphic techniques for laser range finder (LRF) simulation

    Science.gov (United States)

    Bedkowski, Janusz; Jankowski, Stanislaw

    2008-11-01

    This paper show an advanced computer graphic techniques for laser range finder (LRF) simulation. The LRF is the common sensor for unmanned ground vehicle, autonomous mobile robot and security applications. The cost of the measurement system is extremely high, therefore the simulation tool is designed. The simulation gives an opportunity to execute algorithm such as the obstacle avoidance[1], slam for robot localization[2], detection of vegetation and water obstacles in surroundings of the robot chassis[3], LRF measurement in crowd of people[1]. The Axis Aligned Bounding Box (AABB) and alternative technique based on CUDA (NVIDIA Compute Unified Device Architecture) is presented.

  14. Reservoir shore development in long range terrestrial laser scanning monitoring.

    Science.gov (United States)

    Kaczmarek, Halina

    2016-04-01

    Shore zones of reservoirs are in most cases very active, getting transformed as a result of coastal processes and mass movements initiated on the slopes surrounding the reservoir. From the point of view of the users of water reservoirs shore recession strongly undesirable as it causes destruction to infrastructure and buildings located in the immediate vicinity of the reservoir. For this reason, reservoir shores require continuous geodetic monitoring. Fast and accurate geodetic measurements covering shore sections several kilometers long, often in poorly accessible areas, are available using long range terrestrial laser scanning (TLS). The possibilities of using long range terrestrial laser scanning are shown on the example of the reservoir Jeziorsko on the Warta River (Central Poland). This reservoir, created in the years 1986-1992, is a typical retention reservoir, the annual fluctuations of which reach 5 m. Depending on the water level its surface area ranges from 42.3 to 19.6 km2. The width of the reservoir is 2.5 km. The total shore length of the reservoir, developed in Quaternary till and sand-till sediments, is 44.3 km, including 30.1 km of the unreinforced shore. Out of the unreinforced shore 27% is subject to coastal erosion. The cliff heights vary from a few cm to 12.5 meters, and the current rate of the cliff recession ranges from 0 to 1.12 m/y. The study used a terrestrial long range laser scanner Riegl VZ-4000 of a range of up to 4000 m. It enabled conducting the measurements of the cliff recession from the opposite shore of the reservoir, with an angular resolution of 0.002°, which gives about 50 measurement points per 1 m2. The measurements were carried out in the years 2014-2015, twice a year, in early spring before high water level, and in late autumn at a dropping water level. This allowed the separation of the impact of coastal processes and frost weathering on the cliff recession and their quantitative determination. The size and nature of

  15. Impact of Infrared Lunar Laser Ranging on Lunar Dynamics

    Science.gov (United States)

    Viswanathan, Vishnu; Fienga, Agnès; Manche, Hervé; Gastineau, Mickael; Courde, Clément; Torre, Jean-Marie; Exertier, Pierre; Laskar, Jacques; LLR Observers : Astrogeo-OCA, Apache Point, McDonald Laser Ranging Station, Haleakala Observatory, Matera Laser Ranging Observatory

    2016-10-01

    Since 2015, in addition to the traditional green (532nm), infrared (1064nm) has been the preferred wavelength for lunar laser ranging at the Calern lunar laser ranging (LLR) site in France. Due to the better atmospheric transmission of IR with respect to Green, nearly 3 times the number of normal points have been obtained in IR than in Green [ C.Courde et al 2016 ]. In our study, in addition to the historical data obtained from various other LLR sites, we include the recent IR normal points obtained from Calern over the 1 year time span (2015-2016), constituting about 4.2% of data spread over 46 years of LLR. Near even distribution of data provided by IR on both the spatial and temporal domain, helps us to improve constraints on the internal structure of the Moon modeled within the planetary ephemeris : INPOP [ Fienga et al 2015 ]. IERS recommended models have been used in the data reduction software GINS (GRGS,CNES) [ V.Viswanathan et al 2015 ]. Constraints provided by GRAIL, on the Lunar gravitational potential and Love numbers have been taken into account in the least-square fit procedure. New estimates on the dynamical parameters of the lunar core will be presented.

  16. Broadband laser ranging development at the DOE Labs

    Science.gov (United States)

    Bennett, Corey V.; La Lone, Brandon M.; Younk, Patrick W.; Daykin, Ed P.; Rhodes, Michelle A.

    2017-02-01

    Broadband Laser Ranging (BLR) is a new diagnostic being developed in collaboration across multiple USA Dept. of Energy (DOE) facilities. Its purpose is to measure the precise position of surfaces and particle clouds moving at speeds of a few kilometers per second. The diagnostic uses spectral interferometry to encode distance into a modulation in the spectrum of pulses from a mode-locked fiber laser and uses a dispersive Fourier transformation to map the spectral modulation into time. This combination enables recording of range information in the time domain on a fast oscilloscope every 25-80 ns. Discussed here are some of the hardware design issues, system tradeoffs, calibration issues, and experimental results. BLR is being developed as an add-on to conventional Photonic Doppler Velocimetry (PDV) systems because PDV often yields incomplete information when lateral velocity components are present, or when there are drop-outs in the signal amplitude. In these cases, integration of the velocity from PDV can give incorrect displacement results. Experiments are now regularly fielded with over 100 channels of PDV, and BLR is being developed in a modular way to enable high channel counts of BLR and PDV recorded from the same probes pointed at the same target location. In this way instruments, will independently record surface velocity and distance information along the exact same path.

  17. Theoretical analysis and numerical solution of laser pulse transformation for satellite laser ranging

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The processes of the pulse transformation in satellite laser ranging (SLR) are analyzed,the analytical expressions of the transformation are deduced,and the effects of the transformation on Center-of-Mass corrections of satellite and ranging precision are discussed.The numerical solution of the transformation and its effects are also given.The results reveal the rules of pulse transformation affected by different kinds of factors.These are significant for designing the SLR system with millimeter accuracy.

  18. Infrared Lunar Laser Ranging at Calern : Impact on Lunar Dynamics

    Science.gov (United States)

    Viswanathan, Vishnu; Fienga, Agnes; Manche, Herve; Gastineau, Mickael; Courde, Clement; Torre, Jean Marie; Exertier, Pierre; Laskar, Jacques

    2017-04-01

    Introduction: Since 2015, in addition to the traditional green (532nm), infrared (1064nm) has been the preferred wavelength for lunar laser ranging at the Calern lunar laser ranging (LLR) site in France. Due to the better atmospheric transmission of IR with respect to Green, nearly 3 times the number of normal points have been obtained in IR than in Green [1]. Dataset: In our study, in addition to the historical data obtained from various other LLR sites, we include the recent IR normal points obtained from Calern over the 1 year time span (2015-2016), constituting about 4.2% of data spread over 46 years of LLR. Near even distribution of data provided by IR on both the spatial and temporal domain, helps us to improve constraints on the internal structure of the Moon modeled within the planetary ephemeris : INPOP [2]. Data reduction: IERS recommended models have been used in the data reduction software GINS (GRGS,CNES) [3]. Constraints provided by GRAIL [4], on the Lunar gravitational potential and Love numbers have been taken into account in the least-square fit procedure. Earth orientation parameters from KEOF series have been used as per a recent study [5]. Results: New estimates on the dynamical parameters of the lunar core will be presented. Acknowledgements: We thank the lunar laser ranging observers at Observatoire de la Côte d'Azur, France, McDonald Observatory, Texas, Haleakala Observatory, Hawaii, and Apache Point Observatory in New Mexico for providing LLR observations that made this study possible. The research described in this abstract was carried out at Geoazur-CNRS, France, as a part of a PhD thesis funded by Observatoire de Paris and French Ministry of Education and Research. References: [1] Clement C. et al. (2016) submitted to A&A [2] Fienga A. et al. (2015) Celest Mech Dyn Astr, 123: 325. doi:10.1007/s10569-015-9639-y [3] Viswanathan V. et al. (2015) EGU, Abstract 18, 13995 [4] Konopliv A. S. et al. (2013) J. Geophys. Res. Planets, 118, 1415

  19. Probing Gravity with Next Generation Lunar Laser Ranging

    Science.gov (United States)

    Martini, Manuele; Dell'Agnello, Simone

    Lunar and satellite laser ranging (LLR/SLR) are consolidated techniques which provide a precise, and at the same time, cost-effective method to determine the orbits of the Moon and of satellites equipped with laser retroreflectors with respect to the International Celestial Reference System. We describe the precision tests of general relativity and of new theories of gravity that can be performed with second-generation LLR payloads on the surface of the Moon (NASA/ASI MoonLIGHT project), and with SLR/LLR payloads deployed on spacecraft in the Earth-Moon system. A new wave of lunar exploration and lunar science started in 2007-2008 with the launch of three missions (Chang'e by China, Kaguya by Japan, Chandrayaan by India), missions in preparation (LCROSS, LRO, GRAIL/LADEE by NASA) and other proposed missions (like MAGIA in Italy). This research activity will be greatly enhanced by the future robotic deployment of a lunar geophysics network (LGN) on the surface of the Moon. A scientific concept of the latter is the International Lunar Network (ILN, see http://iln.arc.nasa.gov/). The LLR retroreflector payload developed by a US-Italy team described here and under space qualification at the National Laboratories of Frascati (LNF) is the optimum candidate for the LGN, which will be populated in the future by any lunar landing mission.

  20. Nuclear Gamma-Ray Laser of Optical Range

    CERN Document Server

    Tkalya, E V

    2010-01-01

    A possibility of amplification of the 7.6 eV (3.5 eV) $\\gamma$-radiation by the stimulated $\\gamma$-emission of the ensemble of the $^{229m}$Th isomeric nuclei in a host dielectric crystal with a large band gap is proved theoretically. This amplification is a result of the following three factors: 1) the excitation of a great number of the $^{229m}$Th isomers by laser radiation; 2) the creation of the inverse population of nuclear levels in a cooled sample placed in magnetic field; 3) the emissions/absorption of the optical photons by thorium nuclei in the crystal without recoil (the M\\"{o}ssbauer effect in the optical range).

  1. Upgrading NASA/DOSE laser ranging system control computers

    Science.gov (United States)

    Ricklefs, Randall L.; Cheek, Jack; Seery, Paul J.; Emenheiser, Kenneth S.; Hanrahan, William P., III; Mcgarry, Jan F.

    1993-01-01

    Laser ranging systems now managed by the NASA Dynamics of the Solid Earth (DOSE) and operated by the Bendix Field Engineering Corporation, the University of Hawaii, and the University of Texas have produced a wealth on interdisciplinary scientific data over the last three decades. Despite upgrades to the most of the ranging station subsystems, the control computers remain a mix of 1970's vintage minicomputers. These encompass a wide range of vendors, operating systems, and languages, making hardware and software support increasingly difficult. Current technology allows replacement of controller computers at a relatively low cost while maintaining excellent processing power and a friendly operating environment. The new controller systems are now being designed using IBM-PC-compatible 80486-based microcomputers, a real-time Unix operating system (LynxOS), and X-windows/Motif IB, and serial interfaces have been chosen. This design supports minimizing short and long term costs by relying on proven standards for both hardware and software components. Currently, the project is in the design and prototyping stage with the first systems targeted for production in mid-1993.

  2. Testing Gravity via Lunar Laser Ranging: Maximizing Data Quality

    Science.gov (United States)

    Murphy, Thomas

    We propose to continue leading-edge observations with the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO), in an effort to subject gravity to the most stringent tests yet. APOLLO has delivered a dramatic improvement in the measurement of the lunar orbit: now at the millimeter level. Yet incomplete models are thus far unable to confirm the accuracy. We therefore seek to build a calibration system to ensure that APOLLO meets its millimeter measurement goal. Gravity--the most evident force of nature--is in fact the weakest of the fundamental forces, and consequently the most poorly tested. Einstein’s general relativity, which is currently our best description of gravity, is fundamentally incompatible with quantum mechanics and is likely to be replaced by a more complete theory in the future. A modified theory would predict small deviations in the solar system that could have profound consequences for our understanding of the Universe as a whole. Lunar laser ranging (LLR), in which short laser pulses launched from a telescope are bounced off of reflectors placed on the Moon by U.S. astronauts and Soviet landers, has for decades produced some of the leading tests of gravity by mapping the shape of the lunar orbit to high precision. These include tests of the strong equivalence principle, the time-rate-ofchange of Newton’s gravitational constant, gravitomagnetism, the inverse-square law, and many others. Among the attributes that contribute to APOLLO’s superior observations, routine ranging to all five lunar reflectors on timescales of minutes dramatically improves our ability to gauge lunar orientation and body distortion. This information produces insights into the interior structure and dynamics of the Moon, allowing a more precise determination of the path for the Moon’s center of mass, lending to tests of fundamental gravity. Simultaneously, higher precision range measurements, together with data from a superconducting gravimeter at the

  3. Tectonic motion and deformation from satellite laser ranging to Lageos

    Science.gov (United States)

    Smith, David E.; Kolenkiewicz, Ronald; Dunn, Peter J.; Robbins, John W.; Torrence, Mark H.; Klosko, Steve M.; Williamson, Ronald G.; Pavlis, Erricos C.; Douglas, Nancy B.

    1990-01-01

    Data on satellite laser ranging (SLR) to Lageos aquired during the period 1978-1988 are analyzed on the basis of the precise modeling of the orbit dynamics of Lageos, producing estimates of tectonic motion for 22 sites located on seven major plates. It was estimated that intraplate motion within northern Europe is below the 2 mm/yr level in absolute rate, in agreement with conclusions of Zoback et al. (1989) regarding the stress across the region. A comparison of SLR geodesic rates with those from NUVEL-1 and AMO-2 models showed high correlations between tracking sites that are well within plate interiors, but displayed small but significant departures from unity in slope which are attributed to the possibility of recent changes in relative velocities or geologic time scale uncertainties. For lines crossing the Nnorth Atlantic, the San Andreas fault, and within the Basin and Range province, the geodesic rates determined by SLR are in good agreement with those determined by VLBI.

  4. Determination of crustal motions using satellite laser ranging

    Science.gov (United States)

    1991-01-01

    Satellite laser ranging has matured over the last decade into one of the essential space geodesy techniques. It has demonstrated centimeter site positioning and millimeter per year velocity determinations in a frame tied dynamically to the mass center of the solid Earth hydrosphere atmosphere system. Such a coordinate system is a requirement for studying long term eustatic sea level rise and other global change phenomena. Earth orientation parameters determined with the coordinate system have been produced in near real time operationally since 1983, at a relatively modest cost. The SLR ranging to Lageos has also provided a rich spectrum of results based upon the analysis of Lageos orbital dynamics. These include significant improvements in the knowledge of the mean and variable components of the Earth's gravity field and the Earth's gravitational parameter. The ability to measure the time variations of the Earth's gravity field has opened as exciting area of study in relating global processes, including meteorologically derived mass transport through changes in the satellite dynamics. New confirmation of general relativity was obtained using the Lageos SLR data.

  5. Laser speckle reduction by phase range limited computer generated hologram in laser projection display system.

    Science.gov (United States)

    Chang, Yan-Shuo; Lin, Chia-Hsin; Hsu, Ku-Hui; Hsu, Wei-Feng; Hsiao, Li-Jen; Lin, Hoang Yan

    2014-09-20

    The speckle phenomenon is an annoyance in laser projection display systems. We propose a novel speckle suppression method that utilizes the interference concept on a pixel point, which reduces the speckle contrast (SC) of the project image by limiting the phase distribution range in the optical field. The SC formula is derived in the uniform interval phase range for partially developed speckle conditions, showing that the SC can be lowered by lessening the phase range limitation. In the ideal simulation model, the SC can be reduced from 98.77% to 0% as the phase range limitation varies from 2π to 0. The phase range limitation model is a novel method using a computer generated hologram to provide beam shaping and phase limitation. In a more realistic simulation model, the SC is reduced from 99.18% to 16.68%.

  6. Short-Range Sensor for Underwater Robot Navigation using Line-lasers and Vision

    DEFF Research Database (Denmark)

    Hansen, Peter Nicholas; Nielsen, Mikkel Cornelius; Christensen, David Johan

    2015-01-01

    This paper investigates a minimalistic laser-based range sensor, used for underwater inspection by Autonomous Underwater Vehicles (AUV). This range detection system system comprise two lasers projecting vertical lines, parallel to a camera’s viewing axis, into the environment. Using both lasers...

  7. Short-Range Sensor for Underwater Robot Navigation using Line-lasers and Vision

    DEFF Research Database (Denmark)

    Hansen, Peter Nicholas; Nielsen, Mikkel Cornelius; Christensen, David Johan;

    2015-01-01

    This paper investigates a minimalistic laser-based range sensor, used for underwater inspection by Autonomous Underwater Vehicles (AUV). This range detection system system comprise two lasers projecting vertical lines, parallel to a camera’s viewing axis, into the environment. Using both lasers f...

  8. A Lunar Laser Ranging Retroreflector for the 21st Century

    Science.gov (United States)

    Currie, D.; Dell-Agnello, S.; Delle Monache, G.

    Over the past forty years, Lunar Laser Ranging (LLR) to the Apollo Cube Corner (CCR) Retroreflector arrays has supplied almost all of the significant tests of General Relativity. The LLR program has evaluated the PPN parameters and addressed, for example, the possible change in the gravitational constant and the properties of the self-energy of the gravitational field. In addition, LLR has provided significant information on the composition and origin of the moon. These arrays are the only experiment of the Apollo program that are still in operation. Initially the Apollo Lunar Arrays contributed a negligible portion of the error budget used to achieve these results. Over the decades, the performance of ground stations has greatly upgraded so that the ranging accuracy has improved by more than two orders of magnitude, i.e., a factor of 140. Now, after forty years, because of the lunar librations the existing Apollo retroreflector arrays contribute significant fraction of the limiting errors in the range measurements. The University of Maryland, as the Principal Investigator for the original Apollo arrays, is now proposing a new approach to the Lunar Laser CCR array technology. The investigation of this new technology, with Professor Currie as Principal Investigator, is currently being supported by two NASA programs and, in part, also by INFN/LNF. Thus after the proposed installation on the next Lunar landing, the new arrays will support ranging observations that are a factor 100 more accurate than the current Apollo LLRRAs, from the centimeter level to the micron level. The new fundamental physics and the lunar physics that this new LLRRA can provide will be described. In the design of the new array, there are three major challenges: 1) Validate that the specifications of the CCR required for the new array, with are significantly beyond the properties of current CCRs, can indeed be achieved. 2) Address the thermal and optical effects of the absorption of solar

  9. MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment (PRA) Techniques

    Science.gov (United States)

    2014-08-01

    AFRL-RH-FS-TR-2014-0035 MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment (PRA) Techniques Paul...the Government’s approval or disapproval of its ideas or findings. MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment... Probabilistic Risk Assessment (PRA) techniques to perform laser safety and hazard analysis for high output lasers in outdoor environments has become

  10. Contribution of satellite laser ranging to combined gravity field models

    Science.gov (United States)

    Maier, A.; Krauss, S.; Hausleitner, W.; Baur, O.

    2012-02-01

    In the framework of satellite-only gravity field modeling, satellite laser ranging (SLR) data is typically exploited to recover long-wavelength features. This contribution provides a detailed discussion of the SLR component of GOCO02S, the latest release of combined models within the GOCO series. Over a period of five years (January 2006 to December 2010), observations to LAGEOS-1, LAGEOS-2, Ajisai, Stella, and Starlette were analyzed. We conducted a series of closed-loop simulations and found that estimating monthly sets of spherical harmonic coefficients beyond degree five leads to exceedingly ill-posed normal equation systems. Therefore, we adopted degree five as the spectral resolution for real data analysis. We compared our monthly coefficient estimates of degree two with SLR and Gravity Recovery and Climate Experiment (GRACE) time series provided by the Center for Space Research (CSR) at Austin, Texas. Significant deviations in C20 were noted between SLR and GRACE; the agreement is better for the non-zonal coefficients. Fitting sinusoids together with a linear trend to our C20 time series yielded a rate of (-1.75 ± 0.6) × 10-11/yr; this drift is equivalent to a geoid change from pole to equator of 0.35 ± 0.12 mm/yr or an apparent Greenland mass loss of 178.5 ± 61.2 km3/yr. The mean of all monthly solutions, averaged over the five-year period, served as input for the satellite-only model GOCO02S. The contribution of SLR to the combined gravity field model is highest for C20, and hence is essential for the determination of the Earth's oblateness.

  11. Bore-Sight Calibration of Multiple Laser Range Finders for Kinematic 3D Laser Scanning Systems

    Directory of Open Access Journals (Sweden)

    Jaehoon Jung

    2015-05-01

    Full Text Available The Simultaneous Localization and Mapping (SLAM technique has been used for autonomous navigation of mobile systems; now, its applications have been extended to 3D data acquisition of indoor environments. In order to reconstruct 3D scenes of indoor space, the kinematic 3D laser scanning system, developed herein, carries three laser range finders (LRFs: one is mounted horizontally for system-position correction and the other two are mounted vertically to collect 3D point-cloud data of the surrounding environment along the system’s trajectory. However, the kinematic laser scanning results can be impaired by errors resulting from sensor misalignment. In the present study, the bore-sight calibration of multiple LRF sensors was performed using a specially designed double-deck calibration facility, which is composed of two half-circle-shaped aluminum frames. Moreover, in order to automatically achieve point-to-point correspondences between a scan point and the target center, a V-shaped target was designed as well. The bore-sight calibration parameters were estimated by a constrained least squares method, which iteratively minimizes the weighted sum of squares of residuals while constraining some highly-correlated parameters. The calibration performance was analyzed by means of a correlation matrix. After calibration, the visual inspection of mapped data and residual calculation confirmed the effectiveness of the proposed calibration approach.

  12. Test technology on divergence angle of laser range finder based on CCD imaging fusion

    Science.gov (United States)

    Shi, Sheng-bing; Chen, Zhen-xing; Lv, Yao

    2016-09-01

    Laser range finder has been equipped with all kinds of weapons, such as tank, ship, plane and so on, is important component of fire control system. Divergence angle is important performance and incarnation of horizontal resolving power for laser range finder, is necessary appraised test item in appraisal test. In this paper, based on high accuracy test on divergence angle of laser range finder, divergence angle test system is designed based on CCD imaging, divergence angle of laser range finder is acquired through fusion technology for different attenuation imaging, problem that CCD characteristic influences divergence angle test is solved.

  13. Receiver Design, Performance Analysis, and Evaluation for Space-Borne Laser Altimeters and Space-to-Space Laser Ranging Systems

    Science.gov (United States)

    Davidson, Frederic M.; Sun, Xiaoli; Field, Christopher T.

    1996-01-01

    This progress report consists of two separate reports. The first one describes our work on the use of variable gain amplifiers to increase the receiver dynamic range of space borne laser altimeters such as NASA's Geoscience Laser Altimeter Systems (GLAS). The requirement of the receiver dynamic range was first calculated. A breadboard variable gain amplifier circuit was made and the performance was fully characterized. The circuit will also be tested in flight on board the Shuttle Laser Altimeter (SLA-02) next year. The second report describes our research on the master clock oscillator frequency calibration for space borne laser altimeter systems using global positioning system (GPS) receivers.

  14. Simultaneous Laser Ranging and Communication from an Earth-Based Satellite Laser Ranging Station to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Neumann, Gregory A.; McIntire, Leva; Zellar, Ronald S.; Davidson, Frederic M.; Fong, Wai H.; Krainak, Michael A.; Zuber, Maria T.; Smith, David E.

    2013-01-01

    We report a free space laser communication experiment from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit through the on board one-way Laser Ranging (LR) receiver. Pseudo random data and sample image files were transmitted to LRO using a 4096-ary pulse position modulation (PPM) signal format. Reed-Solomon forward error correction codes were used to achieve error free data transmission at a moderate coding overhead rate. The signal fading due to the atmosphere effect was measured and the coding gain could be estimated.

  15. Constaints on Lorentz symmetry violations using lunar laser ranging observations

    Science.gov (United States)

    Bourgoin, Adrien

    2016-12-01

    General Relativity (GR) and the standard model of particle physics provide a comprehensive description of the four interactions of nature. A quantum gravity theory is expected to merge these two pillars of modern physics. From unification theories, such a combination would lead to a breaking of fundamental symmetry appearing in both GR and the standard model of particle physics as the Lorentz symmetry. Lorentz symmetry violations in all fields of physics can be parametrized by an effective field theory framework called the standard-model extension (SME). Local Lorentz Invariance violations in the gravitational sector should impact the orbital motion of bodies inside the solar system, such as the Moon. Thus, the accurate lunar laser ranging (LLR) data can be analyzed in order to study precisely the lunar motion to look for irregularities. For this purpose, ELPN (Ephéméride Lunaire Parisienne Numérique), a new lunar ephemeris has been integrated in the SME framework. This new numerical solution of the lunar motion provides time series dated in temps dynamique barycentrique (TDB). Among that series, we mention the barycentric position and velocity of the Earth-Moon vector, the lunar libration angles, the time scale difference between the terrestrial time and TDB and partial derivatives integrated from variational equations. ELPN predictions have been used to analyzed LLR observations. In the GR framework, the residuals standard deviations has turned out to be the same order of magnitude compare to those of INPOP13b and DE430 ephemerides. In the framework of the minimal SME, LLR data analysis provided constraints on local Lorentz invariance violations. Spetial attention was paid to analyze uncertainties to provide the most realistic constraints. Therefore, in a first place, linear combinations of SME coefficients have been derived and fitted to LLR observations. In a second time, realistic uncertainties have been determined with a resampling method. LLR data

  16. A Detailed Evaluation of a Laser Triangulation Ranging System for Mobile Robots

    Science.gov (United States)

    1983-08-01

    A RPI TECHNICAL REPORT MP-82 A DETAILED EVALUATION OF A LASER - TRIANGULATION RANGING SYSTEM FOR MOBILE ROBOTS by Thomas J. Clement Contract MDA-903...Polytechnic Institute Technical Report MP-79, Troy, N.Y., May 1982. 9. McNellis, T., "Evaluation of a Laser Triangulation Ranging System for Mobile Robots ." Rensselaer

  17. Photofragmentation of colloidal solutions of gold nanoparticles under femtosecond laser pulses in IR and visible ranges

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, P A; Zayarnyi, D A; Ionin, A A; Kudryashov, S I; Makarov, S V; Rudenko, A A; Saraeva, I N; Yurovskikh, V I [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Lednev, V N; Pershin, S M [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-05-31

    The specific features of photofragmentation of sols of gold nanoparticles under focused femtosecond laser pulses in IR (1030 nm) and visible (515 nm) ranges is experimentally investigated. A high photofragmentation efficiency of nanoparticles in the waist of a pulsed laser beam in the visible range (at moderate radiation scattering) is demonstrated; this efficiency is related to the excitation of plasmon resonance in nanoparticles on the blue shoulder of its spectrum, in contrast to the regime of very weak photofragmentation in an IR-laser field of comparable intensity. Possible mechanisms of femtosecond laser photofragmentation of gold nanoparticles are discussed. (extreme light fields and their applications)

  18. Benefits Derived From Laser Ranging Measurements for Orbit Determination of the GPS Satellite Orbit

    Science.gov (United States)

    Welch, Bryan W.

    2007-01-01

    While navigation systems for the determination of the orbit of the Global Position System (GPS) have proven to be very effective, the current research is examining methods to lower the error in the GPS satellite ephemerides below their current level. Two GPS satellites that are currently in orbit carry retro-reflectors onboard. One notion to reduce the error in the satellite ephemerides is to utilize the retro-reflectors via laser ranging measurements taken from multiple Earth ground stations. Analysis has been performed to determine the level of reduction in the semi-major axis covariance of the GPS satellites, when laser ranging measurements are supplemented to the radiometric station keeping, which the satellites undergo. Six ground tracking systems are studied to estimate the performance of the satellite. The first system is the baseline current system approach which provides pseudo-range and integrated Doppler measurements from six ground stations. The remaining five ground tracking systems utilize all measurements from the current system and laser ranging measurements from the additional ground stations utilized within those systems. Station locations for the additional ground sites were taken from a listing of laser ranging ground stations from the International Laser Ranging Service. Results show reductions in state covariance estimates when utilizing laser ranging measurements to solve for the satellite s position component of the state vector. Results also show dependency on the number of ground stations providing laser ranging measurements, orientation of the satellite to the ground stations, and the initial covariance of the satellite's state vector.

  19. A laser ranging system operating at 1036 nm with Geiger-mode silicon avalanche photodiode

    Science.gov (United States)

    Wu, Guang; Ren, Min; Liang, Yan; Wang, Zhiyuan; Pan, Haifeng; Zeng, Heping

    2012-09-01

    We demonstrated a laser ranging experiment obtained with a Geiger-mode silicon avalanche photodiode (Si GAPD). The Surface-to-surface resolution of 15 cm was achieved with the technique of time-correlated single-photon counting. In the experiment, a mode-locked Yb-doped fiber laser at 1036 nm was applied, as the detection efficiency at 1036 nm of Si GAPDs is much higher than that at 1064nm which was widely applied in remote sensing. Due to the single-photon detector, the laser ranging system was able to measure the reflected photon pulses at single-photon level. We realized 32- m laser ranging experiment with a 135-mm diameter Newtonian telescope in daylight. And the system could measure the non-cooperated object longer than 11.3 km far away, which was tested through inserting the optical loss. It presented a potential for hundreds-of-kilometer laser ranging at low-light level.

  20. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V [OOO ' Opton' , Moscow (Russian Federation); Ladugin, M A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Chamorovsky, A Yu [Superlum Ltd., Unit B3, Fota Point Enterprise Park, Carrigtwohill, Co Cork (Ireland); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  1. Improvement of range precision in laser detection and ranging system by using two Geiger mode avalanche photodiodes

    Science.gov (United States)

    Kim, Tae Hoon; Kong, Hong Jin; Jo, Sung Eun; Jeon, Byoung Goo; Oh, Min Seok; Heo, Ayoung; Park, Dong Jo

    2013-06-01

    In this paper, the improvement of range precision in a laser detection and ranging (LADAR) system by using two Geiger mode avalanche photodiodes (GmAPDs) is described. The LADAR system is implemented by using two GmAPDs with a beam splitter and applying comparative process to their ends. Then, the timing circuit receives the electrical signals only if each GmAPDs generates electrical signals simultaneously. Though this system decreases the energy of a laser-return pulse scattered from the target, it is effective in reducing the range precision. The experimental results showed that the average value of standard deviation of time of flights was improved from 61 mm to 37 mm when the pulse energy is 0.6 μJ. When the time bin width is 0.5 ns, the single-shot precision error of the LADAR system was also improved from 280 mm to 67 mm.

  2. Improvement of range precision in laser detection and ranging system by using two Geiger mode avalanche photodiodes.

    Science.gov (United States)

    Kim, Tae Hoon; Kong, Hong Jin; Jo, Sung Eun; Jeon, Byoung Goo; Oh, Min Seok; Heo, Ayoung; Park, Dong Jo

    2013-06-01

    In this paper, the improvement of range precision in a laser detection and ranging (LADAR) system by using two Geiger mode avalanche photodiodes (GmAPDs) is described. The LADAR system is implemented by using two GmAPDs with a beam splitter and applying comparative process to their ends. Then, the timing circuit receives the electrical signals only if each GmAPDs generates electrical signals simultaneously. Though this system decreases the energy of a laser-return pulse scattered from the target, it is effective in reducing the range precision. The experimental results showed that the average value of standard deviation of time of flights was improved from 61 mm to 37 mm when the pulse energy is 0.6 μJ. When the time bin width is 0.5 ns, the single-shot precision error of the LADAR system was also improved from 280 mm to 67 mm.

  3. Micron-Accurate Laser Fresnel-Diffraction Ranging System

    Science.gov (United States)

    Lehner, David; Campbell, Jonathan; Smith, Kelly; Sanders, Alvin; Allison, Stephen; Smaley, Larry

    2008-01-01

    Two versions of an optoelectronic system undergoing development are depicted. The system is expected to be capable of measuring a distance between 2 and 10 m with an error of no more than 1 micrometer. The system would be designed to exploit Fresnel diffraction of a laser beam. In particular, it would be designed to take advantage of the fact that a Fresnel diffraction pattern is ultrasensitive to distance. The two versions would differ in the following respects: In version 1, the focus of the telescope would be in the Fresnel region, and the telescope would have a small depth of focus. As a consequence, the Fresnel pattern would be imaged directly onto the photodetector array; in version 2, a multielement lens module would displace the Fresnel region from the vicinity of the pinhole to the vicinity of the optical receiver. As the distance to be measured varied, the location of the receiver relative to the displaced Fresnel-diffraction region would vary, thereby causing the Fresnel diffraction pattern on the focal plane to vary. The multielement lens module would also correct for aberrations. The processing of the digitized Fresnel diffraction pattern in the computer might be accelerated by using only parts of the pattern or even only one small part - the central pixel. As the distance from the pinhole increased, the central pixel would rapidly cycle between maximum and minimum light intensity. This in itself would not be sufficient to uniquely determine the distance. However, by varying the size of the pinhole or the wavelength of the laser, one could obtain a second cycle of variation of intensity that, in conjunction with the first cycle, could enable a unique determination of distance. Alternatively, for a single wavelength and a single pinhole size, it should suffice to consider the data from only two different key pixels in the Fresnel pattern.

  4. Application of Satellite Laser Ranging Techniques for Space Situational Awareness Efforts

    Science.gov (United States)

    Shappirio, M.; McGarry, J. F.; Bufton, J.; Cheek, J. W.; Coyle, D. B.; Hull, S. M.; Stysley, P. R.; Sun, X.; Young, R. P.; Zagwodzki, T.

    2016-09-01

    With the numbers of conjunction avoidance maneuvers for the International Space Station and other Low Earth Orbit satellites rising and likely to continue to increase, the need to develop methods to produce accurate 72+ hour orbital predictions is becoming critical. One emerging solution is to utilize satellite laser ranging techniques to range to debris and refine the initial positions to improve the orbital predictions for objects predicted to experience a close approach. Some stations in Europe have already demonstrated that this technique is possible, but it has not been employed to refine the likelihood of collision. We will present a notional architecture for laser ranging to debris utilizing existing satellite laser ranging or visual tracking facilities. We will also discuss the capabilities of laser ranging for Space Situational Awareness and provide a direct comparison to current visual and radar tracking methods.

  5. Design and simulation of a mixer and phase difference measuring circuitry for laser range finding systems

    Science.gov (United States)

    Liu, Guili; Wang, Yanlin; Liu, Gang

    2006-11-01

    This article focuses on the circuit implementation of a mixer and phase difference measurement for laser range finding systems. It will introduce simply the principle of the laser range finding system, which is the basis of the electronic circuitry design. The modulated laser lights of two different frequencies are mixed and the phase difference is detected in order to measure the range. The method of measuring the range is to use the mixer and the phase difference detector. The new and high precision IC that has a high quality makes the circuit simple and reliable. The circuit of the mixer and the phase difference detector for laser range finding systems is designed using AD608 and AD8302 chips.

  6. High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

    Science.gov (United States)

    Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

    2016-01-01

    We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

  7. Real-time high dynamic range laser scanning microscopy

    Science.gov (United States)

    Vinegoni, C.; Leon Swisher, C.; Fumene Feruglio, P.; Giedt, R. J.; Rousso, D. L.; Stapleton, S.; Weissleder, R.

    2016-04-01

    In conventional confocal/multiphoton fluorescence microscopy, images are typically acquired under ideal settings and after extensive optimization of parameters for a given structure or feature, often resulting in information loss from other image attributes. To overcome the problem of selective data display, we developed a new method that extends the imaging dynamic range in optical microscopy and improves the signal-to-noise ratio. Here we demonstrate how real-time and sequential high dynamic range microscopy facilitates automated three-dimensional neural segmentation. We address reconstruction and segmentation performance on samples with different size, anatomy and complexity. Finally, in vivo real-time high dynamic range imaging is also demonstrated, making the technique particularly relevant for longitudinal imaging in the presence of physiological motion and/or for quantification of in vivo fast tracer kinetics during functional imaging.

  8. Topographic laser ranging and scanning principles and processing

    CERN Document Server

    Shan, Jie

    2008-01-01

    A systematic, in-depth introduction to theories and principles of Light Detection and Ranging (LiDAR) technology is long overdue, as it is the most important geospatial data acquisition technology to be introduced in recent years. An advanced discussion, this text fills the void.Professionals in fields ranging from geology, geography and geoinformatics to physics, transportation, and law enforcement will benefit from this comprehensive discussion of topographic LiDAR principles, systems, data acquisition, and data processing techniques. The book covers ranging and scanning fundamentals, and broad, contemporary analysis of airborne LiDAR systems, as well as those situated on land and in space. The authors present data collection at the signal level in terms of waveforms and their properties; at the system level with regard to calibration and georeferencing; and at the data level to discuss error budget, quality control, and data organization. They devote the bulk of the book to LiDAR data processing and inform...

  9. Real-time high dynamic range laser scanning microscopy.

    Science.gov (United States)

    Vinegoni, C; Leon Swisher, C; Fumene Feruglio, P; Giedt, R J; Rousso, D L; Stapleton, S; Weissleder, R

    2016-04-01

    In conventional confocal/multiphoton fluorescence microscopy, images are typically acquired under ideal settings and after extensive optimization of parameters for a given structure or feature, often resulting in information loss from other image attributes. To overcome the problem of selective data display, we developed a new method that extends the imaging dynamic range in optical microscopy and improves the signal-to-noise ratio. Here we demonstrate how real-time and sequential high dynamic range microscopy facilitates automated three-dimensional neural segmentation. We address reconstruction and segmentation performance on samples with different size, anatomy and complexity. Finally, in vivo real-time high dynamic range imaging is also demonstrated, making the technique particularly relevant for longitudinal imaging in the presence of physiological motion and/or for quantification of in vivo fast tracer kinetics during functional imaging.

  10. Experiment of Diffuse Reflection Laser Ranging to Space Debris and Data Analysis

    CERN Document Server

    Sun, Hao; Zhang, ZhongPing; Wu, Bin

    2014-01-01

    Space debris has been posing a serious threat to human space activities and is needed to be measured and cataloged. As a new technology of space target surveillance, the measurement accuracy of DRLR (Diffuse Reflection Laser Ranging) is much higher than that of microwave radar and electro-optical measurement. Based on laser ranging data of space debris from DRLR system collected at SHAO (Shanghai Astronomical Observatory) in March-April 2013, the characteristics and precision of the laser ranging data are analyzed and its applications in OD (Orbit Determination) of space debris are discussed in this paper, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39cm-228cm. When the data is sufficient enough (4 arcs of 3 days), the orbit accuracy of space debris can be up to 50m.

  11. A new bismuth-doped fibre laser, emitting in the range 1625 – 1775 nm

    Energy Technology Data Exchange (ETDEWEB)

    Dianov, E M; Firstov, S V; Alyshev, S V; Riumkin, K E; Shubin, A V; Medvedkov, O I; Mel' kumov, M A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Khopin, V F; Gur' yanov, A N [G.G.Devyatykh Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2014-06-30

    CW lasing of a Bi-doped germanosilicate fibre in a wavelength range that covers the spectral region between the emission bands of Er and Tm fibre lasers has been demonstrated for the first time. (letters)

  12. Statistics of the residual refraction errors in laser ranging data

    Science.gov (United States)

    Gardner, C. S.

    1977-01-01

    A theoretical model for the range error covariance was derived by assuming that the residual refraction errors are due entirely to errors in the meteorological data which are used to calculate the atmospheric correction. The properties of the covariance function are illustrated by evaluating the theoretical model for the special case of a dense network of weather stations uniformly distributed within a circle.

  13. Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory

    Institute of Scientific and Technical Information of China (English)

    杨福民; 肖炽昆; 陈婉珍; 张忠萍; 谭德同; 龚向东; 陈菊平; 黄力; 章建华

    1999-01-01

    The first satellite laser ranging system for daylight tracking in China was set up at Shanghai Observatory, Chinese Academy of Sciences. Both false alarm probability due to strong background noises and detection probability of the laser returns with single photon level from satellite in daylight for our system are analysed. The system design and performance characteristics of subsystems, adopted techniques and satellite ranging observations are given.

  14. Generation of picosecond laser pulses at 1030 nm with gigahertz range continuously tunable repetition rate.

    Science.gov (United States)

    Aubourg, Adrien; Lhermite, Jérôme; Hocquet, Steve; Cormier, Eric; Santarelli, Giorgio

    2015-12-01

    We report on a watt range laser system generating picosecond pulses using electro-optical modulation of a 1030 nm single frequency low noise laser diode. Its repetition rate is continuously tunable between 11 and 18 GHz. Over this range, output spectra and pulse characteristics are measured and compared with a numerical simulation. Finally, amplitude and residual phase noise measurements of the source are also presented.

  15. Realistic simulation of laser range finder behavior in a smoky environment

    OpenAIRE

    Formsma, O.; Dijkshoorn, N.; van Noort, S.; de Visser, A.

    2011-01-01

    The Urban Search and Rescue Simulation used for RoboCup lacks realistic response of laser range finders on smoke. In this paper, the behavior of a Hokuyo and Sick laser range finder in a smoky environment is studied. The behavior of the lasers is among others a function of the visibility level, and in this article this function is quantified into an explicit model. This model is implemented in a simulation environment which is the basis of the Virtual Robot competition of the RoboCup Rescue L...

  16. A Lunar Laser Ranging Retroreflector Array for the 21{sup st} Century

    Energy Technology Data Exchange (ETDEWEB)

    Currie, Douglas G. [Department of Physics, University of Maryland, College Park, MD 20742 (United States); NASA Lunar Science Institute, Moffett Field, CA 94089 US (United States); Dell' Agnello, Simone; Delle Monache, Giovanni O. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati,I-00044 (Italy); Behr, Bradford [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Williams, James G. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2013-10-15

    To date, lunar laser ranging to the Apollo retroreflector arrays, which are still operational after four decades, has produced some of the best tests of General Relativity. Since the ground Observatories have improved their accuracy by a factor of 200, the lunar hardware, due to the lunar librations, now limits the ranging accuracy. The Lunar Laser Ranging Retroreflector Array for the 21{sup st} Century program plans to deploy new packages that will improve the ranging accuracy by a factor of ten to one hundred in the next few years.

  17. Laser-ranging scanning system to observe topographical deformations of volcanoes.

    Science.gov (United States)

    Aoki, T; Takabe, M; Mizutani, K; Itabe, T

    1997-02-20

    We have developed a laser-ranging system to observe the topographical structure of volcanoes. This system can be used to measure the distance to a target by a laser and shows the three-dimensional topographical structure of a volcano with an accuracy of 30 cm. This accuracy is greater than that of a typical laser-ranging system that uses a corner-cube reflector as a target because the reflected light jitters as a result of inclination and unevenness of the target ground surface. However, this laser-ranging system is useful for detecting deformations of topographical features in which placement of a reflector is difficult, such as in volcanic regions.

  18. Sixth International Workshop on Laser Physics (LPHYS 97) Volume 8, No. 1

    Science.gov (United States)

    1998-01-01

    Medical and Biological Appi, 62. 4. Hibst, R., Keller, U., and Steiner , R., 1988, Laser in Medicine and Surgery, 4, 163. 5. Jamjoul, H., Pearson...Solarz (Lawrence Livermore National Laboratory, Livermore, USA) R. Steiner (Institute of Laser Technologies in Medicine, Ulm, Germany) E.A...Japan), and Ivan A. Shcherbakov (Russia) Laser Methods in Medicine Co-Chairs: Sergey A. Gonchukov (Russia), Gerhard J. Müller (Germany), and Rudolf

  19. Fusing Range Measurements from Ultrasonic Beacons and a Laser Range Finder for Localization of a Mobile Robot

    Science.gov (United States)

    Ko, Nak Yong; Kuc, Tae-Yong

    2015-01-01

    This paper proposes a method for mobile robot localization in a partially unknown indoor environment. The method fuses two types of range measurements: the range from the robot to the beacons measured by ultrasonic sensors and the range from the robot to the walls surrounding the robot measured by a laser range finder (LRF). For the fusion, the unscented Kalman filter (UKF) is utilized. Because finding the Jacobian matrix is not feasible for range measurement using an LRF, UKF has an advantage in this situation over the extended KF. The locations of the beacons and range data from the beacons are available, whereas the correspondence of the range data to the beacon is not given. Therefore, the proposed method also deals with the problem of data association to determine which beacon corresponds to the given range data. The proposed approach is evaluated using different sets of design parameter values and is compared with the method that uses only an LRF or ultrasonic beacons. Comparative analysis shows that even though ultrasonic beacons are sparsely populated, have a large error and have a slow update rate, they improve the localization performance when fused with the LRF measurement. In addition, proper adjustment of the UKF design parameters is crucial for full utilization of the UKF approach for sensor fusion. This study contributes to the derivation of a UKF-based design methodology to fuse two exteroceptive measurements that are complementary to each other in localization. PMID:25970259

  20. Time-transfer experiments between satellite laser ranging ground stations via one-way laser ranging to the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Mao, D.; Sun, X.; Skillman, D. R.; Mcgarry, J.; Hoffman, E.; Neumann, G. A.; Torrence, M. H.; Smith, D. E.; Zuber, M. T.

    2014-12-01

    Satellite laser ranging (SLR) has long been used to measure the distance from a ground station to an Earth-orbiting satellite in order to determine the spacecraft position in orbit, and to conduct other geodetic measurements such as plate motions. This technique can also be used to transfer time between the station and satellite, and between remote SLR sites, as recently demonstrated by the Time Transfer by Laser Link (T2L2) project by the Centre National d'Etudes Spatiaes (CNES) and Observatorire de la Cote d'Azur (OCA) as well as the Laser Time Transfer (LTT) project by the Shanghai Astronomical Observatory, where two-way and one-way measurements were obtained at the same time. Here we report a new technique to transfer time between distant SLR stations via simultaneous one-way laser ranging (LR) to the Lunar Reconnaissance Orbiter (LRO) spacecraft at lunar distance. The major objectives are to establish accurate ground station times and to improve LRO orbit determination via these measurements. The results of these simultaneous LR measurements are used to compare the SLR station times or transfer time from one to the other using times-of-flight estimated from conventional radio frequency tracking of LRO. The accuracy of the time transfer depends only on the difference of the times-of-flight from each ground station to the spacecraft, and is expected to be at sub-nano second level. The technique has been validated by both a ground-based experiment and an experiment that utilized LRO. Here we present the results to show that sub-nanosecond precision and accuracy are achievable. Both experiments were carried out between the primary LRO-LR station, The Next Generation Satellite Laser Ranging (NGSLR) station, and its nearby station, Mobile Laser System (MOBLAS-7), both at Greenbelt, Maryland. The laser transmit time from both stations were recorded by the same event timer referenced to a Hydrogen maser. The results have been compared to data from a common All

  1. APOLLO: the Apache Point Observatory Lunar Laser-ranging Operation: Instrument Description and First Detections

    CERN Document Server

    Murphy, T W Jr; Battat, J B R; Carey, L N; Hoyle, C D; LeBlanc, P; Michelsen, E L; Nordtvedt, K; Orin, A E; Strasburg, J D; Stubbs, C W; Swanson, H E; Williams, E

    2007-01-01

    A next-generation lunar laser ranging apparatus using the 3.5 m telescope at the Apache Point Observatory in southern New Mexico has begun science operation. APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) has achieved one-millimeter range precision to the moon which should lead to approximately one-order-of-magnitude improvements in the precision of several tests of fundamental properties of gravity. We briefly motivate the scientific goals, and then give a detailed discussion of the APOLLO instrumentation.

  2. Identification of air and sea-surface targets with a laser range profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Schoemaker, R.M.; Schleijpen, H.M.A.

    2009-01-01

    Current coastal operations have to deal with threats at short range in complex environments with both neutral and hostile targets. There is a need for fast identification, which is possible with a laser range profiler. A number of field trials have been conducted to validate the concept of identific

  3. Identification of air and sea-surface targets with a laser range profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Schoemaker, R.M.; Schleijpen, H.M.A.

    2009-01-01

    Current coastal operations have to deal with threats at short range in complex environments with both neutral and hostile targets. There is a need for fast identification, which is possible with a laser range profiler. A number of field trials have been conducted to validate the concept of

  4. Characterisation of small targets in a maritime environment by means of laser range profiling

    NARCIS (Netherlands)

    Schoemaker, R.M.; Benoist, K.W.

    2011-01-01

    Potential asymmetric threats at short range in complex environments need to be identified quickly during coastal operations. Laser range profiling is a technology that has the potential to shorten the OODA loop (Orient, Observe, Detect, Act) by performing automatic characterisation of targets at

  5. Compensation for the distortion in satellite laser range predictions due to varying pulse travel times

    Science.gov (United States)

    Paunonen, Matti

    1993-01-01

    A method for compensating for the effect of the varying travel time of a transmitted laser pulse to a satellite is described. The 'observed minus predicted' range differences then appear to be linear, which makes data screening or use in range gating more effective.

  6. JENOPTIK diode lasers and bars optimized for high-power applications in the NIR range

    Science.gov (United States)

    Zorn, M.; Hülsewede, R.; Schulze, H.; Sebastian, J.; Hennig, P.; Schröder, D.

    2010-02-01

    Laser diodes and laser bars for the high-volume wavelength ranges at 808 nm and 940 nm are available in optimized design and high quality. However, a lot of other wavelengths in the NIR are needed for specialized applications also requiring high stability, reliability and a good efficiency with a good beam quality. An efficient adaptation of the laser diode design to optimize the laser performance at the customized wavelength is highly desirable. At JENOPTIK Diode Lab (JDL) we therefore focus on a flexible and competitive laser diode design resulting in a high output power and a high efficiency at reasonable production costs. Starting from excellent laser bars at 808 nm and 940 nm laser bars with emission wavelengths around 790 nm, 830 nm, 880nm (cw) and 940 nm (pulsed operation) are developed. For 792 nm a maximum output power of 90 W and an efficiency of 55 % has been achieved with an expected lifetime of more than 15000 hours. At 825 nm a maximum efficiency of 60 % and 60 W output power for more than 20.000 h with a high degree of polarization can be presented. Changing the quantum well material for 885 nm the output power reaches 125W with 63% efficiency also for more than 25.000 hours. Laser bars for pulsed applications (quasi-cw) at 940 nm result in an output power of 500 W with an efficiency of 60 %.

  7. Experiments with very high-power lasers. Report of a workshop, November 29-30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Leigh, J.; Rice, S. A.; Trainor, R. J.; Bass, M.; Hendricks, R. W.; Reader, J.

    1979-01-01

    Among possible experiments of general interest in physics are the study of the spectroscopy and cross section measurements of highly ionized species, the study of nuclear conversion processes, vacuum-ultraviolet lasers, multiphoton absorption, and the Kapitza-Dirac effect. Shock waves driven by ultrahigh-power lasers are capable of attaining pressures of the order of 1 to 4 TPa in material targets, providing a means of deriving equation-of-state data under such extreme conditions. Modifications observed in the structures of materials subjected to high-power laser radiation can lead to studies of damage and phase change processes. Classes of useful experiments in this area are given. The x rays produced when a pulse of ultrahigh-power laser radiation is focussed on a target are sufficiently intense to generate diffraction patterns and EXAFS spectra on a nanosecond time scale. A major application of ultrahigh-power lasers to chemistry and biology may consist in such time-resolved diffraction and EXAFS studies of dynamical systems. The laser systems at the National Laser User Facility at the University of Rochester are described. These systems are available to qualified investigators for user experiments.

  8. Proceedings of the workshop prospects for a 1 angstrom free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, J.C. (ed.)

    1990-01-01

    This report contains papers on the following topics free-electron laser theory, scaling relations and simulations; micro-wigglers; photocathode and switched power gun; applications; and summary of working groups.

  9. Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics

    Science.gov (United States)

    Quan, Wei; Hao, Xiaolei; Chen, Yongju; Yu, Shaogang; Xu, Songpo; Wang, Yanlan; Sun, Renping; Lai, Xuanyang; Wu, Chengyin; Gong, Qihuang; He, Xiantu; Liu, Xiaojun; Chen, Jing

    2016-06-01

    In strong field atomic physics community, long-range Coulomb interaction has for a long time been overlooked and its significant role in intense laser-driven photoelectron dynamics eluded experimental observations. Here we report an experimental investigation of the effect of long-range Coulomb potential on the dynamics of near-zero-momentum photoelectrons produced in photo-ionization process of noble gas atoms in intense midinfrared laser pulses. By exploring the dependence of photoelectron distributions near zero momentum on laser intensity and wavelength, we unambiguously demonstrate that the long-range tail of the Coulomb potential (i.e., up to several hundreds atomic units) plays an important role in determining the photoelectron dynamics after the pulse ends.

  10. Compact multispectral continuous zoom camera for color and SWIR vision with integrated laser range finder

    Science.gov (United States)

    Hübner, M.; Gerken, M.; Achtner, Bertram; Kraus, M.; Münzberg, M.

    2014-06-01

    In an electro-optical sensor suite for long range surveillance tasks the optics for the visible (450nm - 700nm) and the SWIR spectral wavelength range (900nm - 1700 nm) are combined with the receiver optics of an integrated laser range finder (LRF) .The incoming signal from the observed scene and the returned laser pulse are collected within the common entrance aperture of the optics. The common front part of the optics is a broadband corrected lens design from 450 - 1700nm wavelength range. The visible spectrum is split up by a dichroic beam splitter and focused on a HDTV CMOS camera. The returned laser pulse is spatially separated from the scene signal by a special prism and focused on the laser receiver diode of the integrated LRF. The achromatic lens design has a zoom factor 14 and F#2.6 in the visible path. In the SWIR path the F-number is adapted to the corresponding chip dimensions . The alignment of the LRF with respect to the SWIR camera line of sight can be controlled by adjustable integrated wedges. The two images in the visible and the SWIR spectral range match in focus and field of view (FOV) over the full zoom range between 2° and 22° HFOV. The SWIR camera has a resolution of 640×512 pixels. The HDTV camera provides a resolution of 1920×1080. The design and the performance parameters of the multispectral sensor suite is discussed.

  11. High-Precision Lunar Ranging and Gravitational Parameter Estimation With the Apache Point Observatory Lunar Laser-ranging Operation

    Science.gov (United States)

    Johnson, Nathan H.

    This dissertation is concerned with several problems of instrumentation and data analysis encountered by the Apache Point Observatory Lunar Laser-ranging Operation. Chapter 2 considers crosstalk between elements of a single-photon avalanche photodiode detector. Experimental and analytic methods were developed to determine crosstalk rates, and empirical findings are presented. Chapter 3 details electronics developments that have improved the quality of data collected by detectors of the same type. Chapter 4 explores the challenges of estimating gravitational parameters on the basis of ranging data collected by this and other experiments and presents resampling techniques for the derivation of standard errors for estimates of such parameters determined by the Planetary Ephemeris Program (PEP), a solar-system model and data-fitting code. Possible directions for future work are discussed in Chapter 5. A manual of instructions for working with PEP is presented as an appendix.

  12. New Laser Doppler Velocimetry with Wide Dynamic Range and Clear Directional Discrimination

    Institute of Scientific and Technical Information of China (English)

    GUI Hua-Qiao; L(U) Liang; HE De-Yong; XU Jun; XIE Jian-Ping; ZHAO Tian-Peng; WANG An-Ting; MING Hai

    2005-01-01

    @@ We present a new laser Doppler velocimetry based on self-mixing effect using a single longitudinal-mode verticalcavity surface-emitting laser modulated by a dynamic triangular current. It can indicate the direction of velocity without ambiguity in a wide dynamic range of 5.2-479.9mm/s. The accuracy of velocity measurement is better than 3.1% in the whole velocity range when a diffusing target is used for measurements. More interestingly, it works very well on different diffusing surfaces, even on a black glossy photographic paper.

  13. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    Science.gov (United States)

    Burris, John

    2011-01-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be greater than approximately 20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (less than approximately 0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels.

  14. Laser materials for the 0.67-microns to 2.5-microns range

    Science.gov (United States)

    Toda, Minoru; Zamerowski, Thomas J.; Ladany, Ivan; Martinelli, Ramon U.

    1987-01-01

    Basic requirements for obtaining injection laser action in III-V semiconductors are discussed briefly. A detailed review is presented of materials suitable for lasers emitting at 0.67, 1.44, 1.93, and 2.5 microns. A general approach to the problem is presented, based on curves of materials properties published by Sasaki et al. It is also shown that these curves, although useful, may need correction in certain ranges. It is deduced that certain materials combinations, either proposed in the literature or actually tried, are not appropriate for double heterostructure lasers, because the refractive index of the cladding material is higher than the index of the active material, thus resulting in no waveguiding, and high threshold currents. Recommendations are made about the most promising approach to the achievement of laser action in the four wavelengths mentioned above.

  15. Maximum detection range limitation of pulse laser radar with Geiger-mode avalanche photodiode array

    Science.gov (United States)

    Luo, Hanjun; Xu, Benlian; Xu, Huigang; Chen, Jingbo; Fu, Yadan

    2015-05-01

    When designing and evaluating the performance of laser radar system, maximum detection range achievable is an essential parameter. The purpose of this paper is to propose a theoretical model of maximum detection range for simulating the Geiger-mode laser radar's ranging performance. Based on the laser radar equation and the requirement of the minimum acceptable detection probability, and assuming the primary electrons triggered by the echo photons obey Poisson statistics, the maximum range theoretical model is established. By using the system design parameters, the influence of five main factors, namely emitted pulse energy, noise, echo position, atmospheric attenuation coefficient, and target reflectivity on the maximum detection range are investigated. The results show that stronger emitted pulse energy, lower noise level, more front echo position in the range gate, higher atmospheric attenuation coefficient, and higher target reflectivity can result in greater maximum detection range. It is also shown that it's important to select the minimum acceptable detection probability, which is equivalent to the system signal-to-noise ratio for producing greater maximum detection range and lower false-alarm probability.

  16. Technique Errors and Limiting Factors in Laser Ranging to Geodetic Satellites

    Science.gov (United States)

    Appleby, G. M.; Luceri, V.; Mueller, H.; Noll, C. E.; Otsubo, T.; Wilkinson, M.

    2012-12-01

    The tracking stations of the International Laser Ranging Service (ILRS) global network provide to the Data Centres a steady stream of very precise laser range normal points to the primary geodetic spherical satellites LAGEOS (-1 and -2) and Etalon (-1 and -2). Analysis of these observations to determine instantaneous site coordinates and Earth orientation parameters provides a major contribution to ongoing international efforts to define a precise terrestrial reference frame, which itself supports research into geophysical processes at the few mm level of precision. For example, the latest realization of the reference frame, ITRF2008, used weekly laser range solutions from 1983 to 2009, the origin of the Frame being determined solely by the SLR technique. However, in the ITRF2008 publication, Altamimi et al (2011, Journal of Geodesy) point out that further improvement in the ITRF is partly dependent upon improving an understanding of sources of technique error. In this study we look at SLR station hardware configuration that has been subject to major improvements over the last four decades, at models that strive to provide accurate translations of the laser range observations to the centres of mass of the small geodetic satellites and at the considerable body of work that has been carried out via orbital analyses to determine range corrections for some of the tracking stations. Through this study, with specific examples, we start to put together an inventory of system-dependent technique errors that will be important information for SLR re-analysis towards the next realization of the ITRF.

  17. Indetermination of particle sizing by laser diffraction in the anomalous size ranges

    Science.gov (United States)

    Pan, Linchao; Ge, Baozhen; Zhang, Fugen

    2017-09-01

    The laser diffraction method is widely used to measure particle size distributions. It is generally accepted that the scattering angle becomes smaller and the angles to the location of the main peak of scattered energy distributions in laser diffraction instruments shift to smaller values with increasing particle size. This specific principle forms the foundation of the laser diffraction method. However, this principle is not entirely correct for non-absorbing particles in certain size ranges and these particle size ranges are called anomalous size ranges. Here, we derive the analytical formulae for the bounds of the anomalous size ranges and discuss the influence of the width of the size segments on the signature of the Mie scattering kernel. This anomalous signature of the Mie scattering kernel will result in an indetermination of the particle size distribution when measured by laser diffraction instruments in the anomalous size ranges. By using the singular-value decomposition method we interpret the mechanism of occurrence of this indetermination in detail and then validate its existence by using inversion simulations.

  18. Analysis of one-way laser ranging data to LRO, time transfer and clock characterization

    Science.gov (United States)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2017-02-01

    We processed and analyzed one-way laser ranging data from International Laser Ranging Service ground stations to NASA's Lunar Reconnaissance Orbiter (LRO), obtained from June 13, 2009 until September 30, 2014. We pair and analyze the one-way range observables from station laser fire and spacecraft laser arrival times by using nominal LRO orbit models based on the GRAIL gravity field. We apply corrections for instrument range walk, as well as for atmospheric and relativistic effects. In total we derived a tracking data volume of ≈ 3000 hours featuring 64 million Full Rate and 1.5 million Normal Point observations. From a statistical analysis of the dataset we evaluate the experiment and the ground station performance. We observe a laser ranging measurement precision of 12.3 cm in case of the Full Rate data which surpasses the LOLA timestamp precision of 15 cm. The averaging to Normal Point data further reduces the measurement precision to 5.6 cm. We characterized the LRO clock with fits throughout the mission time and estimated the rate to 6.9 × 10-8, the aging to 1.6 × 10-12/day and the change of aging to 2.3 × 10-14 /day2over all mission phases. The fits also provide referencing of onboard time to the TDB time scale at a precision of 166 ns over two and 256 ns over all mission phases, representing ground to space time transfer. Furthermore we measure ground station clock differences from the fits as well as from simultaneous passes which we use for ground to ground time transfer from common view observations. We observed relative offsets ranging from 33 to 560 ns and relative rates ranging from 2 × 10-13 to 6 × 10-12 between the ground station clocks during selected mission phases. We study the results from the different methods and discuss their applicability for time transfer.

  19. Advanced technologies in the ASI MLRO towards a new generation laser ranging system

    Science.gov (United States)

    Varghese, Thomas; Bianco, Giuseppe

    1994-01-01

    Matera Laser Ranging Observatory (MLRO) is a high performance, highly automated optical and astronomical observatory currently under design and development by AlliedSignal for the Italian Space Agency (ASI). It is projected to become operational at the Centro Geodesia Spaziale in Matera, Italy, in 1997. MLRO, based on a 1.5-meter astronomical quality telescope, will perform ranging to spacecraft in earthbound orbits, lunar reflectors, and specially equipped deep space missions. The primary emphasis during design is to incorporate state-of-the-art technologies to produce an intelligent, automated, high accuracy ranging system that will mimic the characteristic features of a fifth generation laser ranging system. The telescope has multiple ports and foci to support future experiments in the areas of laser communications, lidar, astrometry, etc. The key features providing state-of-the-art ranging performance include: a diode-pumped picosecond (50 ps) laser, high speed (3-5 GHz) optoelectronic detection and signal processing, and a high accuracy (6 ps) high resolution (less than 2 ps) time measurement capability. The above combination of technologies is expected to yield millimeter laser ranging precision and accuracy on targets up to 300,000 km, surpassing the best operational instrument performance to date by a factor of five or more. Distributed processing and control using a state-of-the-art computing environment provides the framework for efficient operation, system optimization, and diagnostics. A computationally intelligent environment permits optimal planning, scheduling, tracking, and data processing. It also supports remote access, monitor, and control for joint experiments with other observatories.

  20. Dynamic Range of Vertical Cavity Surface Emitting Lasers in Multimode Links

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.L.T.; Dalal, R.V.; Ram, R.J.; Choquette, K.D.

    1999-07-07

    The authors report spurious free dynamic range measurements of 850nm vertical cavity surface emitting lasers in short multimode links for radio frequency communication. For a 27m fiber link, the dynamic range at optimal bias was greater than 95dB-Hz{sup 2/3} for modulation frequencies between 1 and 5.5 GHz, which exceeds the requirements for antenna remoting in microcellular networks. In a free space link, they have measured the highest dynamic range in an 850nm vertical cavity surface emitting laser of 113dB-Hz{sup 2/3} at 900MHz. We have also investigated the effects of modal noise and differential mode delay on the dynamic range for longer lengths of fiber.

  1. All-fiber broad-range self-sweeping Yb-doped fiber laser

    Science.gov (United States)

    Lobach, Ivan A.; Kablukov, Sergey A.; Podivilov, Evgeniy V.; Babin, Sergey A.

    2012-02-01

    The effect of broad-range self-sweeping in Yb-doped fiber laser has been demonstrated experimentally for the first time. The self-sweeping effect is observed in an all-fiber laser configuration with a double-clad Yb-doped fiber and a cavity formed by a broad-band fiber loop mirror and Fresnel reflection from one cleaved end. The sweep range is limited by the width of the broad-band reflector and reaches up to 16nm. It is found that the self-sweeping effect is related to selfpulsations. So the sweep rate is increased with an increase in pump power and is decreased with increasing cavity length. RF and optical spectra (linewidth is measured to be not more than 100 MHz) show that during the evolution of a single pulse a small number of longitudinal modes take a part in lasing. Based on these results we propose a model describing dynamics of the laser frequency. The model is based on the spatial hole burning effect and the gain saturation in Yb laser transition, and takes into account self-pulsations of the laser. Theoretical estimation for pulse to pulse change of lasing frequency is in good agreement with experimental data.

  2. The Moon as a Laser-ranged Test Body for General Relativity and New Gravitational Physics

    Science.gov (United States)

    Dell'Agnello, Simone; Currie, Douglas

    Since the 1970s Lunar Laser Ranging (LLR) to the Apollo/Lunokhod Cube Corner Retroreflector (CCR) Arrays supplied some of the best tests of General Relativity (GR): possible changes in the gravitational constant, gravitational self-energy (PPN parameter beta), weak equivalence principle, geodetic precession, inverse-square force-law. Secondly, LLR has provided significant information on the composition of the deep interior of the Moon. LLR physics analysis also allows to set constraints on extensions of GR (like spacetime torsion) and, possibly, on new gravitational physics which may explain the gravitational universe without Dark Matter and Dark Energy (like, for example, Non-Minimally Coupled gravity, NMC). LLR is the only Apollo/Lunokhod experiment still in operation, since 45 years. In the 1970s Apollo/Lunokohd LLR Arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo/Lunokhod CCR arrays dominate the error budget. With the US/Italy project "LLRRA21/MoonLIGHT (Lunar Laser Ranging Retroreflector Array for the 21st century / Moon Laser Instrumentation for General relativity High accuracy Tests)", University of Maryland and INFN-LNF developed and tested a next-generation LLR payload made by a single, large CCR (100 mm diameter), unaffected by the effect of librations. In fact, we will show that MoonLIGHT reflectors will improve the LLR accuracy by a factor of ten to one hundred in a few years. INFN-LNF also developed a laser retroreflector micropayload to be deployed on the lunar surface to be laser-ranged by lunar orbiters. The latter micropayload will further extend the physics reach of Apollo, Lunokhod and MoonLIGHT CCRs to improve all precision tests of GR and new gravitational physics using LLR data. As an added value for the LRR and SLR (Satellite Laser ranging) disciplines INFN-LNF built and is

  3. Compact short-pulse laser for near-field range-gated imaging

    Science.gov (United States)

    Zutavern, Fred J.; Helgeson, Wesley D.; Loubriel, Guillermo M.; Yates, George J.; Gallegos, Robert A.; McDonald, Thomas E., Jr.

    1997-05-01

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 100 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight, System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory and high gain, PCSS-driven LDAs developed at Sandia National Laboratories. The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

  4. A high resolution laser ranging system based on time-correlated single-photon counting technology

    Science.gov (United States)

    Yang, Yixin; Wang, Huanqin; Huang, Zhe; Cao, Yangyang; Gui, Huaqiao

    2014-12-01

    Laser ranging has become an important method for both distance measurements and acquisition of threedimensional (3D) images. In this paper, a laser ranging system based on Time-Correlated Single-Photon Counting technology (TCSPC) is developed. A Geiger-mode avalanche photodiode (G-APD), which has the ability of detecting single-photon events, is used to capture the weak light scattered from the long-range target. In order to improve the ranging resolution of TCSPC based measurement system, a high repetition frequency of subnanosecond narrow pulse generator circuit based on the avalanche effect of RF-BJT is designed and applied as the light source. Moreover, some optimized optical light designs have been done to improve the system signal to noise rate (SNR), including using a special aspherical lens as projecting lens, adopting a telephoto camera lens with small view angle and short depth of field before detector. Experimental tests for evaluation of the laser raging system performance are described. As a means of echo signal analysis, three different algorithms have been introduced, in which the cross-correlation algorithm was demonstrated to be the most effective algorithm to determining the round trip time to a target, even based on histograms with a significant amount of background noise photons. It was found that centimeter ranging resolution can be achieved thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and the Cross-Correlation algorithm. The proposed laser ranging system has advantages of high range resolution, short response time and simple structure, which was potential applications for 3D object recognition, computer vision, reverse engineering and virtual reality.

  5. Interspacecraft link simulator for the laser ranging interferometer onboard GRACE Follow-On.

    Science.gov (United States)

    Sanjuan, Josep; Gohlke, Martin; Rasch, Stefan; Abich, Klaus; Görth, Alexander; Heinzel, Gerhard; Braxmaier, Claus

    2015-08-01

    Link acquisition strategies are key aspects for interspacecraft laser interferometers. We present an optical fiber-based setup able to simulate the interspacecraft link for the laser ranging interferometer (LRI) on gravity recovery and climate experiment Follow-On. It allows one to accurately recreate the far-field intensity profile depending on the mispointing between the spacecraft, Doppler shifts, and spacecraft attitude jitter. Furthermore, it can be used in late integration stages of the mission, since no physical contact with the spacecraft is required. The setup can also be easily adapted to other similar missions and different acquisition algorithms.

  6. Earth rotation, station coordinates and orbit determination from satellite laser ranging

    Science.gov (United States)

    Murata, Masaaki

    The Project MERIT, a special program of international colaboration to Monitor Earth Rotation and Intercompare the Techniques of observation and analysis, has come to an end with great success. Its major objective was to evaluate the ultimate potential of space techniques such as VLBI and satellite laser ranging, in contrast with the other conventional techniques, in the determination of rotational dynamics of the earth. The National Aerospace Laboratory (NAL) has officially participated in the project as an associate analysis center for satellite laser technique for the period of the MERIT Main Campaign (September 1983-October 1984). In this paper, the NAL analysis center results are presented.

  7. FMCW laser range-finder with an avalanche photodiode working as an optoelectronic mixer

    Science.gov (United States)

    Dupuy, David; Lescure, Marc; Tap-Beteille, Helene

    2002-01-01

    A Frequency Modulation Continuous Wave (FMCW) laser range- finder has been designed for distances from 1 m to 20 m with cooperative or diffusing targets. This range-finder is compared to a phase shift laser range-finder. A heterodyne photoreception method is studied. In order to reduce noise, the nonlinear current-voltage characteristic of the APD is used to obtain an optoelectronic mixer. The photocurrent gain is modulated by the VCO signal working as a local oscillator (LO). The optical and electrical LO injection methods are studied. The theoretical analysis using the Miller model and thermal effects are compared with the first experimental results. The electrical LO injection gives a better ratio-to-noise than the optical LO injection. For electrical injection, it is shown that the heterodyne conversion gain can reach the maximal theoretical value 0.5.

  8. Hollow Retroreflectors for Lunar Laser Ranging at Goddard Space Flight Center

    Science.gov (United States)

    Preston, Alix M.; Merkowitz, Stephen M.

    2012-01-01

    Laser ranging to the retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions have dramatically increased our understanding of gravitational physics along with Earth and Moon geophysics, geodesy, and dynamics. Although the precision of the range measurements has historically been limited by the ground station capabilities, advances in the APOLLO instrument at the Apache Point facility in New Mexico is beginning to be limited by errors associated with the lunar arrays. At Goddard Space Flight Center, we have developed a facility where we can design, build, and test next-generation hollow retroreflectors for Lunar Laser Ranging. Here we will describe this facility as well as report on the bonding techniques used to assemble the retroreflectors. Results from investigations into different high reflectivity mirror coatings, as well as dust mitigation coatings will also be presented.

  9. Using mid-range laser scanners to digitize cultural-heritage sites.

    Science.gov (United States)

    Spring, Adam P; Peters, Caradoc; Minns, Tom

    2010-01-01

    Here, we explore new, more accessible ways of modeling 3D data sets that both professionals and amateurs can employ in areas such as architecture, forensics, geotechnics, cultural heritage, and even hobbyist modeling. To support our arguments, we present images from a recent case study in digital preservation of cultural heritage using a mid-range laser scanner. Our appreciation of the increasing variety of methods for capturing 3D spatial data inspired our research. Available methods include photogrammetry, airborne lidar, sonar, total stations (a combined electronic and optical survey instrument), and midand close-range scanning.1 They all can produce point clouds of varying density. In our case study, the point cloud produced by a mid-range scanner demonstrates how open source software can make modeling and disseminating data easier. Normally, researchers would model this data using expensive specialized software, and the data wouldn't extend beyond the laser-scanning community.

  10. Large field-of-view range-gated laser imaging based on image fusion

    Science.gov (United States)

    Ren, Pengdao; Wang, Xinwei; Sun, Liang; You, Ruirong; Lei, Pingshun; Zhou, Yan

    2016-11-01

    Laser range-gated imaging has great potentials in remote night surveillance with far detection distance and high resolution, even if under bad weather conditions such as fog, snow and rain. However, the field of view (FOV) is smaller than large objects like buildings, towers and mountains, thus only parts of targets are observed in one single frame, so that it is difficult for targets identification. Apparently, large FOV is beneficial to solve the problem, but the detection range is not available due to low illumination density in a large field of illumination matching with the FOV. Therefore, a large field-of-view range-gated laser imaging is proposed based on image fusion in this paper. Especially an image fusion algorithm has been developed for low contrast images. First of all, an infrared laser range-gated system is established to acquire gate images with small FOV for three different scenarios at night. Then the proposed image fusion algorithm is used for generating panoramas for the three groups of images respectively. Compared with raw images directly obtained by the imaging system, the fused images have a larger FOV with more detail target information. The experimental results demonstrate that the proposed image fusion algorithm is effective to expand the FOV of range-gated imaging.

  11. Laser Ranging to the Moon: How Evolving Technology Enables New Science

    Science.gov (United States)

    Faller, James

    2010-03-01

    Technological advances have long been the enabler of scientific progress. The invention of the laser is a prime example of this symbiotic relationship between technical progress and scientific advances. The laser, which today is omnipresent in each of our lives, made its first appearance during the time that I was a graduate student in Professor Dicke's group at Princeton. A major change occurring during that time period was that technology was transforming the study of gravitational physics from just a theoretical subject into also an experimental subject where one could hope to measure things using by-then-available laboratory technologies and techniques. During this same time, the idea for the lunar laser ranging experiment was born. The history and accomplishments of this experiment--a still ongoing experiment which is one of the real scientific triumphs of NASA's Apollo program--will be given.

  12. High-power pulsed laser diodes emitting in the range 1.5 – 1.6 μm

    Energy Technology Data Exchange (ETDEWEB)

    Gorlachuk, P V; Ryaboshtan, Yu L; Ladugin, M A; Padalitsa, A A; Marmalyuk, A A; Kurnosov, V D; Kurnosov, K V; Zhuravleva, O V; Romantsevich, V I; Chernov, R V; Ivanov, A V; Simakov, V A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2013-09-30

    This paper examines approaches for increasing the output pulse power of laser diodes based on MOVPE InGaAs/AlGaInAs/InP heterostructures and emitting in the range 1.5 – 1.6 μm. We demonstrate that optimising waveguide layer parameters may ensure an increase in the quantum efficiency of the laser diodes and a reduction in their internal optical loss. Characterisation results are presented for laser diodes based on the proposed heterostructures. (lasers)

  13. Compressed sensing for super-resolution spatial and temporal laser detection and ranging

    Science.gov (United States)

    Laurenzis, Martin; Schertzer, Stephane; Christnacher, Frank

    2016-10-01

    In the past decades, laser aided electro-optical sensing has reached high maturity and several commercial systems are available at the market for various but specific applications. These systems can be used for detection i.e. imaging as well as ranging. They cover laser scanning devices like LiDAR and staring full frame imaging systems like laser gated viewing or LADAR. The sensing capabilities of these systems is limited by physical parameter (like FPA array size, temporal band width, scanning rate, sampling rate) and is adapted to specific applications. Change of system parameter like an increase of spatial resolution implies the setup of a new sensing device with high development cost or the purchase and installation of a complete new sensor unit. Computational imaging approaches can help to setup sensor devices with flexible or adaptable sensing capabilities. Especially, compressed sensing is an emerging computational method which is a promising candidate to realize super-resolution sensing with the possibility to adapt its performance to various sensing tasks. It is possible to increase sensing capabilities with compressed sensing to gain either higher spatial and/or temporal resolution. Then, the sensing capabilities depend no longer only on the physical performance of the device but also on the computational effort and can be adapted to the application. In this paper, we demonstrate and discuss laser aided imaging using CS for super-resolution tempo-spatial imaging and ranging.

  14. Analyses of Valid Range for the Linear Approximation in a Single-Mode Laser

    Institute of Scientific and Technical Information of China (English)

    CHENGQing-Hua; CAOLi; WANGJun; WUDa-Jin

    2004-01-01

    Using the linear approximation method, we calculated the steady-state mean normalized intensity fluctuation for a loss-noise model of a single-mode laser driven by a pump noise and a quantum noise, whose real part and imaginary part are cross-correlated. We analyzed the valid range for the linear approximation method by studying the influences on the steady-state mean normalized intensity fluctuation by the cross-correlation coefficient, the intensities of the quantum and pump noise, the net gain, and the amplitude and frequency of the input signal, and we found that the valid range becomes wider when the cross-correlation between the real and imaginary part of quantum noise is weaker, the noise intensities of quantum and pump are weaker, the laser system is far from the threshold and the signal has smaller amplitude and higher frequency.

  15. Asymmetric dihedral angle offsets for large-size lunar laser ranging retroreflectors

    Science.gov (United States)

    Otsubo, Toshimichi; Kunimori, Hiroo; Noda, Hirotomo; Hanada, Hideo; Araki, Hiroshi; Katayama, Masato

    2011-08-01

    The distribution of two-dimensional velocity aberration is off-centered by 5 to 6 microradians in lunar laser ranging, due to the stable measurement geometry in the motion of the Earth and the Moon. The optical responses of hollow-type retroreflectors are investigated through numerical simulations, especially focusing on large-size, single-reflector targets that can ultimately minimize the systematic error in future lunar laser ranging. An asymmetric dihedral angle offset, i.e. setting unequal angles between the three back faces, is found to be effective for retroreflectors that are larger than 100 mm in diameter. Our numerical simulation results reveal that the optimized return energy increases approximately 3.5 times more than symmetric dihedral angle cases, and the optimized dihedral angle offsets are 0.65-0.8 arcseconds for one angle, and zeroes for the other two angles.

  16. Dichroic atomic vapor laser lock with multi-gigahertz stabilization range

    Energy Technology Data Exchange (ETDEWEB)

    Pustelny, S., E-mail: pustelny@uj.edu.pl [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Schultze, V.; Scholtes, T. [Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745 Jena (Germany); Budker, D. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Helmholtz-Institut Mainz, Johannes Gutenberg Universität Mainz, 55128 Mainz (Germany)

    2016-06-15

    A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the {sup 85}Rb ground state or as far as 16 GHz away from the closest optical transition.

  17. Molecular laser studies in the 7-16. mu. m range. Annual report, 1 June 1975-30 September 1976

    Energy Technology Data Exchange (ETDEWEB)

    Colemen, P.D.

    1976-10-01

    An exploratory research effort to find new molecular lasers in the 7-16 ..mu..m wavelength range, in particular lasers with wavelengths at 7.7, 8.6, and 16 ..mu..m wavelengths, is described. The specific initial objectives were: (1) to explore Raman scattering of CO/sub 2/ radiation in a liquid and molecular gas and (2) to explore chemically excited metal fluorides as laser candidates for the 12-16 ..mu..m wavelength range.

  18. Satellite Laser Ranging Photon-Budget Calculations for a Single Satellite Cornercube Retroreflector: Attitude Control Tolerance

    Science.gov (United States)

    2015-11-01

    UNCLASSIFIED Satellite Laser Ranging Photon-Budget Calculations for a Single Satellite Cornercube Retroreflector: Attitude Control Tolerance Philip C...the SLR station, and the direction of the satellite from the SLR station. The required attitude control tolerance is to within 17◦ of the optimal... attitude control strategy determined in the present work. A pre-launch measurement of the re- flectance (diffraction) pattern of each retroreflector is

  19. Constraints on SME Coefficients from Lunar Laser Ranging, Very Long Baseline Interferometry, and Asteroid Orbital Dynamics

    CERN Document Server

    Poncin-Lafitte, C Le; Hees, A; Bouquillon, S; Lambert, S; Francou, G; Angonin, M -C; Bailey, Q G; Hestroffer, D; David, P; Meynadier, F; Wolf, P

    2016-01-01

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both General Relativity and the Standard Model of particle physics, called the Standard-Model Extension or SME. We consider in this work only the pure gravitational sector of the minimal SME. We present new constraints on the SME coefficients obtained from lunar laser ranging, very long baseline interferometry, and planetary motions.

  20. Material processing with ultra-short pulse lasers working in 2μm wavelength range

    Science.gov (United States)

    Voisiat, B.; Gaponov, D.; Gečys, P.; Lavoute, L.; Silva, M.; Hideur, A.; Ducros, N.; Račiukaitis, G.

    2015-03-01

    New wavelengths of laser radiation are of interest for material processing. Results of application of the all-fiber ultrashort pulsed laser emitting in 2 µm range, manufactured by Novae, are presented. Average output power was 4.35 W in a single-spatial-mode beam centered at the 1950 nm wavelength. Pulses duration was 40 ps, and laser operated at 4.2 MHz pulse repetition rate. This performance corresponded to 25 kW of pulse peak power and almost 1 µJ in pulse energy. Material processing was performed using three different focusing lenses (100, 30 and 18 mm) and mechanical stages for the workpiece translation. 2 µm laser radiation is strongly absorbed by some polymers. Swelling of PMMA surface was observed for scanning speed above 5 mm/s using the average power of 3.45 W focused with the 30 mm lens. When scanning speed was reduced below 4 mm/s, ablation of PMMA took place. The swelling of PMMA is a consequence of its melting due to absorbed laser power. Therefore, experiments on butt welding of PMMA and overlapping welding of PMMA with other polymers were performed. Stable joint was achieved for the butt welding of two PMMA blocks with thickness of 5 mm. The laser was used to cut a Kapton film on a paper carrier with the same set-up as previous. The cut width depended on the cutting speed and focusing optics. A perfect cut with a width of 11 µm was achieved at the translation speed of 60 mm/s.

  1. Building block diode laser concept for high brightness laser output in the kW range and its applications

    Science.gov (United States)

    Ferrario, Fabio; Fritsche, Haro; Grohe, Andreas; Hagen, Thomas; Kern, Holger; Koch, Ralf; Kruschke, Bastian; Reich, Axel; Sanftleben, Dennis; Steger, Ronny; Wallendorf, Till; Gries, Wolfgang

    2016-03-01

    The modular concept of DirectPhotonics laser systems is a big advantage regarding its manufacturability, serviceability as well as reproducibility. By sticking to identical base components an economic production allows to serve as many applications as possible while keeping the product variations minimal. The modular laser design is based on single emitters and various combining technics. In a first step we accept a reduction of the very high brightness of the single emitters by vertical stacking several diodes in fast axis. This can be theoretically done until the combined fast axis beam quality is on a comparable level as the individual diodes slow axis beam quality without loosing overall beam performance after fiber coupling. Those stacked individual emitters can be wavelength stabilized by an external resonator, providing the very same feedback to each of those laser diodes which leads to an output power of about 100 W with BPP of stacking those building blocks using the very same dense spectral combing technique up to multi kW Systems without further reduction of the BPP. The 500 W building blocks are consequently designed in a way that they feature a high flexibility with regard to their emitting wavelength bandwidth. Therefore, new wavelengths can be implemented by only exchanging parts and without any additional change of the production process. This design principal theoretically offers the option to adapt the wavelength of those blocks to any applications, from UV, visible into the far IR as long as there are any diodes commercially available. This opens numerous additional applications like laser pumping, scientific applications, materials processing such as cutting and welding of copper aluminum or steel and also medical application. Typical operating at wavelengths in the 9XX nm range, these systems are designed for and mainly used in cutting and welding applications, but adapted wavelength ranges such as 793 nm and 1530 nm are also offered. Around 15

  2. Time biases in laser ranging observations: A concerning issue of Space Geodesy

    Science.gov (United States)

    Exertier, Pierre; Belli, A.; Lemoine, J. M.

    2017-09-01

    Time transfer by Laser Ranging (LR) recently demonstrated a remarkable stability (a few ps over ∼1000 s) and accuracy (service. The approach we investigate is to compute time synchronization between clocks used at LR stations using accurate data of the Time Transfer by Laser Link (T2L2) experiment onboard the satellite Jason-2 (Samain et al., 2014). Systematic time biases are estimated against the UTC time scale for a set of 22 observing stations in 2013, in the range of zero to a few μ s. Our results suggest that the ILRS network suffers from accuracy issues, due to time biases in the laser ranging observations. We discuss how these systematic effects impact the precise orbit determination of LAGEOS geodetic satellites over a 1-year analysis, and additionally give a measure of the local effect into station coordinates, regarding in particular the effect in the east-west component that is of 2-6 mm for a typical systematic time bias of one μ s.

  3. Reliability analysis of onboard laser ranging systems for control systems by movement of spacecraft

    Directory of Open Access Journals (Sweden)

    E. I. Starovoitov

    2014-01-01

    Full Text Available The purpose of this paper is to study and find the ways to improve the reliability of onboard laser ranging system (LRS used to control the spacecraft rendezvous and descent. The onboard LRS can be implemented with optical-mechanical scanner and without it. The paper analyses the key factors, which influence on the reliability of both LRS. Reliability of LRS is pretty much defined by the reliability of the laser source and its radiation mode. Solid-state diode-pumped lasers are primarily used as a radiation source. The radiation mode, which is defined by requirements for measurement errors of range and speed affect their reliability. The basic assumption is that the resource of solid state lasers is determined by the number pulses of pumping diodes. The paper investigates the influence of radiation mode of solid-state laser on the reliability function when measuring a passive spacecraft rendezvous dosing velocity using a differential method. With the measurement error, respectively, 10 m for range and 0.6 m/s for velocity a reliability function of 0.99 has been achieved. Reducing the measurement error of velocity to 0.5 m/s either results in reduced reliability function <0.99 or it is necessary to reduce the initial error of measurement range up to 3.5...5 m to correspond to the reliability function ≥ 0.995. For the optomechanical scanner-based LRS the maximum pulse repetition frequency versus the range has been obtained. This dependence has been used as a basis to define the reliability function. The paper investigates the influence of moving parts on the reliability of scanning LRS with sealed or unsealed optomechanical unit. As a result, it has been found that the exception of moving parts is justified provided that manufacturing the sealed optomechanical LRS unit is impossible. In this case, the reliability function increases from 0.99 to 0.9999. When sealing the opto-mechanical unit, the same increase in reliability is achieved through

  4. A Hybrid Fiber/Solid-State Regenerative Amplifier with Tunable Pulse Widths for Satellite Laser Ranging

    Science.gov (United States)

    Coyle, Barry; Poulios, Demetrios

    2013-01-01

    A fiber/solid-state hybrid seeded regenerative amplifier, capable of achieving high output energy with tunable pulse widths, has been developed for satellite laser ranging applications. The regenerative amplifier cavity uses a pair of Nd:YAG zigzag slabs oriented orthogonally to one another in order to make thermal lensing effects symmetrical and simplify optical correction schemes. The seed laser used is a fiber-coupled 1,064-nm narrowband (1 mJ) was measured. This corresponds to a nonlinear conversion efficiency of >60%. Furthermore, by pulse pumping this system, a single pulse per laser shot can be created for the SLR (satellite laser ranging) measurement, and this can be ejected into the instrument. This is operated at the precise frequency needed by the measurement, as opposed to commercial short-pulsed, mode-locked systems that need to operate in a continuous fashion, or CW (continuous wave), and create pulses at many MHz. Therefore, this design does not need to throw away or dump 99% of the laser energy to produce what is required; this system can be far smaller, more efficient, cheaper, and readily deployed in the field when packaged efficiently. Finally, by producing custom diode seed pulses electronically, two major advantages over commercial systems are realized: First, this pulse shape is customizable and not affected by the cavity length or gain of the amplifier cavity, and second, it can produce adjustable (selectable) pulse widths by simply adding multiple seed diodes and coupling each into commercial, low-cost fiber-optic combiners.

  5. Arm-Locking with the GRACE Follow-On Laser Ranging Interferometer

    CERN Document Server

    Thorpe, James Ira

    2015-01-01

    Arm-locking is a technique for stabilizing the frequency of a laser in an inter-spacecraft interferometer by using the spacecraft separation as the frequency reference. A candidate technique for future space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA), arm-locking has been extensive studied in this context through analytic models, time-domain simulations, and hardware-in-the-loop laboratory demonstrations. In this paper we show the Laser Ranging Interferometer instrument flying aboard the upcoming Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission provides an appropriate platform for an on-orbit demonstration of the arm-locking technique. We describe an arm-locking controller design for the GRACE-FO system and a series of time-domain simulations that demonstrate its feasibility. We conclude that it is possible to achieve laser frequency noise suppression of roughly two orders of magnitude around a Fourier frequency of 1Hz with conservative margins...

  6. Compact MEMS mirror based Q-switch module for pulse-on-demand laser range finders

    Science.gov (United States)

    Milanović, Veljko; Kasturi, Abhishek; Atwood, Bryan; Su, Yu; Limkrailassiri, Kevin; Nettleton, John E.; Goldberg, Lew; Cole, Brian J.; Hough, Nathaniel

    2015-02-01

    A highly compact and low power consuming Q-switch module was developed based on a fast single-axis MEMS mirror, for use in eye-safe battery-powered laser range finders The module's 1.6mm x 1.6mm mirror has cost than the traditional Electro-Optical Q-Switch. Because pulse-on-demand capability is required, resonant mirrors cannot be used to achieve the needed performance. Instead, a fast point-to-point analog single-axis tilt actuator was designed with a custom-coated high reflectance (HR) mirror to withstand the high intra-cavity laser fluence levels. The mirror is bonded on top of the MEMS actuator in final assembly. A compact MEMS controller was further implemented with the capability of autonomous on-demand operation based on user-provided digital trigger. The controller is designed to receive an external 3V power supply and a digital trigger and it consumes ~90mW during the short switching cycle and ~10mW in standby mode. Module prototypes were tested in a laser cavity and demonstrated high quality laser pulses with duration of ~20ns and energy of over 3mJ.

  7. Short Range Photoassociation of Rb2 by a high power fiber laser

    Science.gov (United States)

    Passagem, Henry; Rodriguez, Ricardo; Ventura, Paulo; Bouloufa, Nadia; Dulieu, Olivier; Marcassa, Luis

    2016-05-01

    Photoassociation has been studied using cold trapped atomic samples for the last 20 years. Due to poor Franck-Condon overlap, a free-to-bound transition followed by spontaneous decay results in a small production of electronic ground state molecules. If the photoassociation is done at short range, deeply bound ground state molecules can be formed. Optical pumping schemes can be used to populate a single state. In our experiment, we have performed trap loss spectroscopy on trapped 85 Rb atoms in a MOT using a high power fiber laser. Our single mode fiber laser (linewidth < 1 MHz) produces about 50 W, which can be tuned in the 1060-1070 nm range. Two vibrational bound states of the 0u+ potential were observed (ν = 137 and 138). The frequency positions as well as the rotational constants of these states are in good agreement with theoretical predictions. We have also measured the lifetime of a crossed optical dipole trap using such fiber laser. The lifetime on resonance is shorter than off resonance as expected. A simple theoretical model indicates that the molecules decay to deeply bound vibrational levels in the ground state. This work was supported by Fapesp and INCT-IQ.

  8. Influence of laser scanner range measurement noise on the quantification of rock surface roughness

    Science.gov (United States)

    Khoshelham, Kourosh; Altundag, Dogan

    2010-05-01

    The roughness of rock surfaces is traditionally measured by using manual tools such as carpenter's comp and compass and disc clinometers. The manual measurements are limited to small samples at accessible parts of the rock. Terrestrial laser scanning is an attractive alternative measurement technique, which offers large coverage, high resolution, and the ability to reach inaccessible high rock faces. The application of laser scanning to the study of rock surface roughness faces a major challenge: the inherent range imprecision hinders the quantification of roughness parameters. In practice, when roughness is in millimeter scale it is often lost in the range measurement noise. The parameters derived from the data, therefore, reflect noise rather than the actual roughness of the surface. In this paper, we investigate the influence of laser scanner range measurement noise on the quantification of rock surfaces roughness. We show that measurement noise leads to the overestimation of roughness parameters. We also demonstrate the application of wavelet de-noising method to eliminating noise from laser scanner data and deriving realistic roughness parameters. A slightly metamorphosed limestone rock in the east bank of the Meuse River in southern Belgium was scanned with a Faro LS880 terrestrial laser scanner. The scanner was positioned at approximately 5 meters distance to the rock surface, and operated at the highest possible angular resolution, i.e. 0.009 degrees. The resulting point cloud contained about 1.2 million points on the rock surface with a point-spacing of 1 mm on average. According to the technical specifications of the laser scanner, the nominal range precision at a perpendicular incidence angle, which was roughly the case in our scan, is between 0.7 mm and 5.2 mm respectively for objects of 90% and 10% reflectivity at a distance of 10 m. To serve as reference roughness data were also collected manually along three profiles on the rock surface by using a

  9. A new synchronization control circuit based on FPGA for the laser range-gated imaging system

    Science.gov (United States)

    He, Shan; Li, Li; Zhou, Yan

    2009-07-01

    Synchronization control is a kernel technique of the laser range-gated (LRG) imaging system which controls the synchronization of the pulsed laser and the ICCD camera directly. It can achieve range gating effectively and improve the resolution of image precisely. Conventional control circuits which are composed of discrete components have a poor performance of anti-interference, and the transmitting signal has a bad delay which affects the conventional circuit’s precision and stabilization seriously. To solve these problems, a range-gated synchronization control circuit is designed. This circuit, which takes the advantages of FPGA’s high compact and flexibility, uses the phase-locking-loop (PLL) to multiply the global clock frequency. This design improves the precision and stabilization greatly, makes the precision up to a nanosecond level and provides a real-time selection of the values of pulse width and delays. Experiments results indicate that this circuit has a high precise and stable range-gated pulse.

  10. Testing gravity with Lunar Laser Ranging: An update on the APOLLO experiment

    Science.gov (United States)

    Battat, James; Colmenares, Nick; Davis, Rodney; Ruixue, Louisa Huang; Murphy, Thomas W., Jr.; Apollo Collaboration

    2017-01-01

    The mystery of dark energy and the incompatibility of quantum mechanics and General Relativity indicate the need for precision experimental probes of gravitational physics. The Earth-Moon-Sun system is a fertile laboratory for such tests. The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) makes optical range measurements to retro-reflectors on the Moon with one millimeter precision. These measurements of the lunar orbit enable incisive constraints on gravitational phenomena such as the Strong Equivalence Principle and dG / dt (among others). Until now, the APOLLO team had not been able to assess the accuracy of our data, in large part because known limitations to lunar range models ensure data-model residuals at the centimeter scale. To directly measure the APOLLO system timing accuracy, we have built an Absolute timing Calibration System (ACS) that delivers photons to our detector at known, stable time intervals using a pulsed fiber laser locked to a cesium frequency standard. This scheme provides real-time calibration of the APOLLO system timing, synchronous with the range measurements. We installed the calibration system in August, 2016. In this talk, we will describe the ACS design, and present present preliminary results from the ACS calibration campaign. We acknowledge the support of both NSF and NASA

  11. A new synchronization control circuit based on FPGA for the laser range-gated imaging system

    Institute of Scientific and Technical Information of China (English)

    HE Shan; LI Li; ZHOU Yan

    2009-01-01

    Synchronization control is a kernel technique of the laser range-gated (LRG) imaging system which controls the synchro-nization of the pulsed laser and the ICCD camera directly. It can achieve range gating effectively and improve the resolution of image precisely. Conventional control circuits which are composed of discrete components have a poor performance of anti-interference, and the transmitting signal has a-bad delay which affects the conventional circuit's precision and stabili-zation seriously. To solve these problems, a range-gated synchronization control circuit is designed. This circuit, which takes the advantages of FPGA's high compact and flexibility, uses the phase-locking-loop (PLL) to multiply the global clock frequency. This design improves the precision and stabilization greatly, makes the precision up to a nanosecond level and provides a real-time selection of the values of pulse width and delays. Experiments results indicate that this circuit has a high precise and stable range-gated pulse.

  12. Estimation of intra-operative brain shift using a tracked laser range scanner.

    Science.gov (United States)

    Ding, Siyi; Miga, Michael I; Thompson, Reid C; Dumpuri, Prashanth; Cao, Aize; Dawant, Benoit M

    2007-01-01

    Intra-operative brain shift limits the usefulness of image-guided neurosurgery systems (IGNS), which are based on pre-operative images. Methods that are being developed to address this problem need intra-operative measurements as input. In this work, we present an intra-operative surface shift measurement technique that relies on a tracked 3D laser range scanner. This scanner acquires both 3D range data and 2D images, which are co-registered. We compare two methods to derive displacements at every point in the field of view. The first one relies on the registration of the 2D images; the second relies on the direct 3D registration of the 3D range data. Our results, based on five data sets, show that the 2D method is preferable.

  13. Small high-speed dynamic target at close range laser active imaging system

    Science.gov (United States)

    Yao, Jun; Wang, Du-yue; Zhang, Zheng; Zhang, Yue; Dai, Qin

    2016-11-01

    In the shooting range measuring, all-weather, high speed, unattended, the new concepts such as the remote control is gradually applied. In this paper, a new type of low cost range measurement system, using FPGA + MCU as electronic control system of laser active illumination and high-speed CMOS camera, data to the rear zone by using optical fiber communications, transmission and realizes the remote control of unmanned, due to the low cost of front-end equipment, can be used as consumables replacement at any time, combined with distributed layout principle, can maximum limit close to the measured with mutilate ability goal, thus to achieve the goal of small high-speed dynamic imaging from close range.

  14. 17th international free electron laser conference and 2nd international FEL users` workshop. Program and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-01

    This workshop and conference were held together to enhance the interaction between FEL builders and users. Current topics of interest in FEL research form the basis for the oral presentations. The program for the User`s workshop was developed in a similar manner. Storage rings, linear accelerators, materials research and applications are all considered topics. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  15. The laser ranging experiment of the Lunar Reconnaissance Orbiter: Five years of operations and data analysis

    Science.gov (United States)

    Mao, Dandan; McGarry, Jan F.; Mazarico, Erwan; Neumann, Gregory A.; Sun, Xiaoli; Torrence, Mark H.; Zagwodzki, Thomas W.; Rowlands, David D.; Hoffman, Evan D.; Horvath, Julie E.; Golder, James E.; Barker, Michael K.; Smith, David E.; Zuber, Maria T.

    2017-02-01

    We describe the results of the Laser Ranging (LR) experiment carried out from June 2009 to September 2014 in order to make one-way time-of-flight measurements of laser pulses between Earth-based laser ranging stations and the Lunar Reconnaissance Orbiter (LRO) orbiting the Moon. Over 4,000 h of successful LR data are obtained from 10 international ground stations. The 20-30 cm precision of the full-rate LR data is further improved to 5-10 cm after conversion into normal points. The main purpose of LR is to utilize the high accuracy normal point data to improve the quality of the LRO orbits, which are nominally determined by the radiometric S-band tracking data. When independently used in the LRO precision orbit determination process with the high-resolution GRAIL gravity model, LR data provide good orbit solutions, with an average difference of ∼50 m in total position, and ∼20 cm in radial direction, compared to the definitive LRO trajectory. When used in combination with the S-band tracking data, LR data help to improve the orbit accuracy in the radial direction to ∼15 cm. In order to obtain highly accurate LR range measurements for precise orbit determination results, it is critical to closely model the behavior of the clocks both at the ground stations and on the spacecraft. LR provides a unique data set to calibrate the spacecraft clock. The LRO spacecraft clock is characterized by the LR data to a timing knowledge of 0.015 ms over the entire 5 years of LR operation. We here present both the engineering setup of the LR experiments and the detailed analysis results of the LR data.

  16. Corner-cube retro-reflector instrument for advanced lunar laser ranging

    CERN Document Server

    Turyshev, Slava G; Folkner, William M; Gutt, Gary M; Baran, Richard T; Hein, Randall C; Somawardhana, Ruwan P; Lipa, John A; Wang, Suwen

    2012-01-01

    Lunar laser ranging (LLR) has made major contributions to our understanding of the Moon's internal structure and the dynamics of the Earth-Moon system. Because of the recent improvements of the ground-based laser ranging facilities, the present LLR measurement accuracy is limited by the retro-reflectors currently on the lunar surface, which are arrays of small corner-cubes. Because of lunar librations, the surfaces of these arrays do not, in general, point directly at the Earth. This effect results in a spread of arrival times, because each cube that comprises the retroreflector is at a slightly different distance from the Earth, leading to the reduced ranging accuracy. Thus, a single, wide aperture corner-cube could have a clear advantage. In addition, after nearly four decades of successful operations the retro-reflectors arrays currently on the Moon started to show performance degradation; as a result, they yield still useful, but much weaker return signals. Thus, fresh and bright instruments on the lunar ...

  17. A review of the lunar laser ranging technique and contribution of timing systems

    Directory of Open Access Journals (Sweden)

    Cilence Munghemezulu

    2016-03-01

    Full Text Available The lunar laser ranging (LLR technique is based on the two-way time-of-flight of laser pulses from an earth station to the retroreflectors that are located on the surface of the moon. We discuss the ranging technique and contribution of the timing systems and its significance in light of the new LLR station currently under development by the Hartebeesthoek Radio Astronomy Observatory (HartRAO. Firstly, developing the LLR station at HartRAO is an initiative that will improve the current geometrical network of the LLR stations which are presently concentrated in the northern hemisphere. Secondly, data products derived from the LLR experiments � such as accurate lunar orbit, tests of the general relativity theory, earth-moon dynamics, interior structure of the moon, reference frames, and station position and velocities � are important in better understanding the earth-moon system. We highlight factors affecting the measured range bias such as the effect of earth tides on station position and delays induced by timing systems, as these must be taken into account during the development of the LLR analysis software. HartRAO is collocated with other fundamental space geodetic techniques which makes it a true fiducial geodetic site in the southern hemisphere and a central point for further development of space-based techniques in Africa. Furthermore, the new LLR will complement the existing techniques by providing new niche areas of research both in Africa and internationally.

  18. Study on the backscattered light intensity to airborne laser range-gated imaging

    Science.gov (United States)

    Wang, Ling; Yu, Lei; Kou, Tian; Wu, Xueming

    2016-10-01

    Based on the range-gated technology in the application of airborne laser detection imaging system, sequence relations of the parameters in the model of range gating in detail was analyzed. The effective scope of atmospheric backscatter and the moment before or after pulsing of the unit section was obtained. Horizontal range-gated imaging model was established and the calculation method of backscattered light intensity was given. Then slant distance detection of airborne laser active imaging was revised. By the object-image relation of points on the scattering section, the light path diagram of imaging detection system was built and the corresponding relation of light intensity between scattering points and receiving points was given. The variation regularity and distribution of light intensity on the detector under horizontal and slant detection were gained. Under the idea, the outfield testing platform was set up, and the relative error of data between measured and simulated results was controlled within 5%. The two kinds of data achieved a good coincident, which demonstrated the effectiveness of the built model. The two kinds of data achieved a good coincident, which demonstrated the effectiveness of the built model.

  19. Method to simulate the object tracking with photon-counting laser ranging system

    Science.gov (United States)

    Du, Xian; Xing, JiChuan; Huang, Hao

    2015-11-01

    We provide a new method to simulate the process of tracking the noncooperative object that moves beyond visual range with a photon-counting laser ranging system. Based on fundamentals of photon-counting laser ranging techniques and parameters of the experimental prototype, we generate echo events according to their probability. Then, we accumulate the echo data in a certain period of time and accurately extract the object's trajectory with mean-shift and random sample consensus algorithms. Depending on the trajectory during the accumulation period, we predict the relative movement of the object in succeeding cycles by using self-tuning α-β filtering and carefully pick out photon echo signals and apply the polynomial fitting to them to compute the trajectory of the object. The simulation shows that the error between the theoretical trajectory and the extracted trajectory is decreasing all the time, which suggests that we can track the object precisely as the time goes by. The simulation in this paper provides a new way for applications like satellite orientation, identification, troubleshooting, etc.

  20. Application of Laser Ranging and VLBI Data to a Study of Plate Tectonic Driving Forces

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The conditions under which changes in plate driving or resistive forces associated with plate boundary earthquakes are measurable with laser ranging or very long base interferometry were investigated. Aspects of plate forces that can be characterized by such measurements were identified. Analytic solutions for two dimensional stress diffusion in a viscoelastic plate following earthquake faulting on a finite fault, finite element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting, and quantitative constraints from modeling of global intraplate stress on the magnitude of deviatoric stress in the lithosphere are among the topics discussed.

  1. Testing fundamental physics with laser ranged satellites: perspectives and goals of the LARASE experiment

    Science.gov (United States)

    Lucchesi, David; Anselmo, Luciano; Pardini, Carmen; Peron, Roberto; Pucacco, Giuseppe; Visco, Massimo

    Passive laser-ranged satellites, launched for geodynamics and geophysics purposes, not only have contributed to significant measurements in space geodesy that enabled, among several aspects, a deeper knowledge of the Earth's geopotential (both in its static and dynamic behavior), as well as of the geocenter motion and GM value up to the definition of the terrestrial reference frame, but they also provided an outstanding test bench to fundamental physics, as in the case of the first measurement of the Lense-Thirring precession on the combined nodes of the two LAGEOS satellites, or in the case of the total relativistic precession of the argument of pericenter of LAGEOS II. Indeed, the physical characteristics of such satellites -- such as their low area-to-mass ratio -- as well as those of their orbits, and the availability of high-quality tracking data provided by the International Laser Ranging Service (ILRS), allow for precise tests of gravitational theories. The aim of LARASE (LAser RAnged Satellites Experiment) is to go a step further in the tests of the gravitational interaction in the field of Earth, i.e. in the weak-field and-slow motion limit of general relativity, by the joint analysis of the orbits of the two LAGEOS satellites and that of the most recent LARES satellite. One of the key ingredients to reach such a goal is to provide high-quality updated models for the perturbing non-gravitational forces acting on the surface of such satellites. A large amount of Satellite Laser Ranging (SLR) data of LAGEOS and LAGEOS II has been analyzed using a set of dedicated models for satellite dynamics, and the related post-fit residuals have been analyzed. A parallel work is on-going in the case of LARES that, due to its much lower altitude, is subject to larger gravitational and non-gravitational effects; the latter are mitigated in part by its much lower area-to-mass ratio. Recent work on the data analysis of the orbit of such satellites will be presented together

  2. Multidiagnostics analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    Energy Technology Data Exchange (ETDEWEB)

    Anoop, K. K.; Polek, M. P.; Bruzzese, R.; Amoruso, S.; Harilal, Sivanandan S.

    2015-02-28

    The ions dynamics in ultrafast laser ablation of metals is studied over a fluence range spanning from the ablation threshold up to ~75 J/cm2 by means of three established diagnostic techniques. Langmuir probe, Faraday cup and spectrally resolved ICCD imaging simultaneously monitor the laser-produced plasma ions produced during ultrafast laser ablation of a copper target. The fluence dependence of ion yield is analyzed observing the occurrence of three different regimes. Moreover, the specific ion yield shows a maximum at about 4-5 J/cm2, followed by a gradual reduction and a transition to a high-fluence regime above ~50 J/cm2. The fluence variation of the copper ions angular distribution is also analyzed, observing a gradual increase of forward peaking of Cu ions for fluences up to ~10 J/cm2. Then, a broader ion component is observed at larger angles for fluences larger than ~10 J/cm2. Finally, an experimental characterization of the ions angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ~66 J/cm2. Interestingly, the ion emission from the volatile metals show a narrow forward peaked distribution and a high peak ion yield compared to the refractory metals. Moreover, the width of ion angular distributions presents a striking correlation with the peak ion yield.

  3. Centimeter Accuracy for the French Transportable Laser Ranging Station (FTLRS) through Sub-System Controls

    Science.gov (United States)

    Nicolas, J.; Pierron, F.; Samain, E.; Barlier, F.

    The French Transportable Laser Ranging Station (FTLRS)is a highly mobile satellite laserranging (SLR) system dedicated to the trackingof geodetic satellites equipped withretroreflectors. This station weighs only 300kg witha 13-cm diameter telescope and is housedin eight containers.The reliability of such a station and its accuracy of 2 cmin real field experiment conditionswere demonstrated during a first field campaign carried outfrom October 1996 to February1997 near Ajaccio on Corsica Island, France. The results ofthis probatory experiment suggestedthat several technical improvements and some modificationswere necessary for JASON-1validation and calibration phase and for new applicationssuch as the Time Transfer by LaserLink (T2L2) experiment. A first change concerns theuse of a new laser wavelength (green instead ofinfrared) and of a new avalanche photodiode with atime walk compensation system. Anotherchange is the installation of a coaxial cabletransmitting directly the signal coming from thereturn detector. Finally, a new calibration systemwas developed with several other changes.A short description of the system is first given.Then, the major changes and the main resultsof ground accuracy tests are summarized and presented.

  4. Workshop Proceedings of the Conference on Solid State Tunable Lasers Held at Hampton, Virginia on 13-15 June 1984.

    Science.gov (United States)

    1985-07-01

    3d TM in AMeF 3host crystals with cubic symmetry like KMgF3 or KZnF 3 3 Spectral Range of the Laser Transitions First the question is discussed which...in AMeX 3 (Fig.4) when only fluorides and chlorides are considered (101 C, energy [eVI 0.5 1.0 1.5 2,0 I I I emission of TM. in AMeF 3 Ni2* Cr 3 Co 2...V2- Mn 2 + C I I I I 4 3 2 .1 0,9 08 0.7 0.6 0.5 .wavelength [g]. Fig!2 Spectral range of emission for different transition metal ions in cubic AMeF

  5. Narrow-line external cavity diode laser micro-packaging in the NIR and MIR spectral range

    Science.gov (United States)

    Jiménez, A.; Milde, T.; Staacke, N.; Aßmann, C.; Carpintero, G.; Sacher, J.

    2017-07-01

    Narrow-linewidth tunable diode lasers are an important tool for spectroscopic instrumentation. Conventional external cavity diode lasers offer high output power and narrow linewidth. However, most external cavity diode lasers are designed as laboratory instrument and do not allow portability. In comparison, other commonly used lasers, like distributed feedback lasers (DFB) that are capable of driving a handheld device, are limited in power and show linewidths which are not sufficiently narrow for certain applications. We present new miniaturized types of tunable external cavity diode laser which overcome the drawbacks of conventional external cavity diode lasers and which preserve the advantages of this laser concept. Three different configurations are discussed in this article. The three types of miniaturized external cavity diode laser systems achieve power values of more than 50 mW within the 1.4 μm water vapor absorption band with excellent side-mode suppression and linewidth below 100 kHz. Typical features outstand with respect to other type of laser systems which are of extended use such as DFB laser diodes. The higher output power and the lower linewidth will enable a higher sensitivity and resolution for a wide range of applications.

  6. Application of a long-range terrestrial laser scanner in research on lowland geodynamic processes

    Science.gov (United States)

    Wiśniewska, Daria; Kramkowski, Mateusz; Tyszkowski, Sebastian

    2015-04-01

    Progress in the LIDAR technology allows collection of data over a longer range and with a higher precision than most of geodetic measurement methods. It is particularly useful in areas that are inaccessible, dangerous, or with a highly variable morphology. These include mountains, steep slopes of river valleys, and edges of water bodies. Because of a high variation in altitude, they are particularly prone to geodynamic processes. In recent years, such areas have been surveyed more and more often with the use of Airborne Laser Scanning, but the high costs and low frequency of surveys make it difficult to trace the dynamics of phenomena and recorded processes. A few years ago, a new method for imaging of land surfaces started to be used: Terrestrial Laser Scanning. The latest scanners make long-distance scanning possible, up to several kilometres), which until recently had been reserved exclusively for Airborne Laser Scanning. The ease and mobility of scanning allows recording of geodynamic processes immediately after their initiation and their constant monitoring, with a high frequency of data collection. The usefulness of long-distance Terrestrial Laser Scanning is presented here on the basis of mass movements on slopes of a large river valley (the lower Vistula valley) and edges of artificial water bodies. These areas were selected because of a high dynamics of geodynamic processes. The scanning was performed at a distance of 2-4 km from the objects, with a resolution of 0.002°. Such parameters of the equipment and the broad scope and long range enable researchers simultaneous scanning of wide belts of the marginal zone. They also allow precise imaging of slopes, including the microforms that cannot be recorded with any other method. Thanks to the characteristics of laser beam reflection, it is also possible to perform analyses that allow identification of landslide initiation, as well as initial stages of erosion of river banks and edges of water bodies. In this

  7. Assessment of long-range kinematic GPS positioning errors by comparison with airborne laser altimetry and satellite altimetry

    DEFF Research Database (Denmark)

    Zhang, X.H.; Forsberg, René

    2007-01-01

    Long-range airborne laser altimetry and laser scanning (LIDAR) or airborne gravity surveys in, for example, polar or oceanic areas require airborne kinematic GPS baselines of many hundreds of kilometers in length. In such instances, with the complications of ionospheric biases, it can be a real c...

  8. Laser parameters of a Fe : ZnSe crystal in the 85-255-K temperature range

    NARCIS (Netherlands)

    Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Frolov, MP

    The temperature dependence of the efficiency of a laser based on a Fe:ZnSe crystal grown from the vapour phase by the free-growth method is studied in the 85-255-K temperature range. As the temperature was increased, the slope efficiency of the laser with respect to absorbed energy decreased from

  9. MOONLIGHT: A NEW LUNAR LASER RANGING RETROREFLECTOR AND THE LUNAR GEODETIC PRECESSION

    Directory of Open Access Journals (Sweden)

    M. Martini

    2013-12-01

    Full Text Available Since the 1970s Lunar Laser Ranging (LLR to the Apollo Cube Corner Retroreflector (CCR arrays (developed by the University of Maryland, UMD supplied almost all significant tests of General Relativity (Alley et al., 1970; Chang et al., 1971; Bender et al.,1973: possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. The LNF group, in fact, has just completed a new measurement of the lunar geodetic precession with Apollo array, with accuracy of 9 × 10−3, comparable to the best measurement to date. LLR has also provided significant information on the composition and origin of the moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests, in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100mm diameter unaffected by the effect of librations. With MoonLIGHT CCRs the accuracy of the measurement of the lunar geodetic precession can be improved up to a factor 100 compared to Apollo arrays. From a technological point of view, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF and created a new industry-standard test procedure (SCF-Test to characterize and model the detailed thermal behavior and the optical performance of CCRs in accurately laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP and the

  10. Feasibility Study of Interstellar Missions Using Laser Sail Probes Ranging in Size from the Nano to the Macro

    Science.gov (United States)

    Malroy, Eric T.

    2010-01-01

    This paper presents the analysis examining the feasibility of interstellar travel using laser sail probes ranging in size from the nano to the macro. The relativistic differential equations of motion for a laser sail are set up and solved using the Pasic Method. The limitations of the analysis are presented and discussed. The requirements for the laser system are examined, including the thermal analysis of the laser sails. Black holes, plasma fields, atmospheric collisions and sun light are several methods discussed to enable the deceleration of the interstellar probe. A number of novel mission scenarios are presented including the embryonic transport of plant life as a precursor to the arrival of space colonies

  11. Broad-range self-sweeping of a narrow-line self-pulsing Yb-doped fiber laser

    Science.gov (United States)

    Lobach, Ivan A.; Kablukov, Sergey I.; Podivilov, Evgeniy V.; Babin, Sergey A.

    2011-08-01

    The effect of broad-range (16 nm) self-sweeping of a narrow-line (less than 1 pm) Yb-doped fiber laser has been demonstrated experimentally. It is found that the effect arises from the self-sustained relaxation oscillations. As a result, the sweeping rate increases as square root of the laser power and decreases with increasing cavity length. Based on these results we propose a model describing dynamics of the laser frequency. The model takes into account the effects of gain saturation at the laser transition and spatial hole burning in the self-pulsing regime.

  12. Surveillance strategies for detecting chronic wasting disease in free-ranging deer and elk: results of a CWD surveillance workshop

    Science.gov (United States)

    Samuel, Michael D.; Joly, Damien O.; Wild, Margaret A.; Wright, Scott D.; Otis, David L.; Werge, Rob W.; Miller, Michael W.

    2003-01-01

    Chronic Wasting Disease (CWD), a fatal brain disease of North American deer and elk, has recently emerged as an important wildlife management issue. Interest and concern over the spread of this disease and its potential impact on free-ranging cervid populations has increased with discovery of the disease in numerous states and provinces. Current studies suggest that CWD may adversely affect of these highly visible, socially desirable, and economically valuable species. Despite the lack of evidence that CWD affects humans or livestock, a significant concern has been the perceived risk to humans and livestock. Uncertainty about whether CWD poses a health risk to hunters and their families who consume venison has resulted in testing of free-ranging cervids for CWD. In response to many of these concerns, wildlife management agencies across the nation have undertaken surveillance programs to detect CWD in their cervid populations. The nation-wide costs for an extensive CWD surveillance program have been estimated at several million dollars. This document provides guidance on the development and conduct of scientifically sound surveillance programs to detect CWD in free-ranging deer and elk populations. These guidelines will not apply equally to all jurisdictions. In many cases local circumstances, resources, area(s) of concern, disease risk, animal and landscape ecology, political, social, and many other factors will influence the objectives, design, and conduct of CWD surveillance programs. Part I of this report discusses the importance of management goals, strategies, and disease risks in developing a surveillance program. Part II describes surveillance methods, steps in designing a sampling strategy to detect CWD, alternative collection methods, and statistical considerations. Part III describes costs (personnel, time, and money) associated with implementation of these plans that will influence program design. Part IV outlines research that is needed to further

  13. OBSTACLE DETECTION BY ALV USING TWO 2D LASER RANGE FINDERS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper describes an effective method of obstacle detection by ALV (Autonomous Land Vehi- cle) equipped with two 2D laser range finders (LRF) installed at different locations of the ALV to obtain eom- prehensive information on the environment. The data processing includes two main steps: ( 1 ) data-processing of the current sample; (2) fusion of the former range data and the current one. The rough description of the ALV's environnent via the four sub-steps ( Data Filter, Obstacle Extraction, Obstacle Merging, Distinguish- ing Obstacle from Road-Edge) was not reliable enough for our control system. To overcome the shortcoming of the 2D LRF and the motion noise of the ALV, a Kalman filter was used to estimate the position of the obsta- cles; then the data of the two LRFs were collated to obtain the height and width of the obstacles. Experiment results attested the feasibility of the detection system.

  14. Large-Scale Hollow Retroreflectors for Lunar Laser Ranging at Goddard Space Flight Center

    Science.gov (United States)

    Preston, Alix

    2012-01-01

    Laser ranging to the retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions have dramatically increased our understanding of gravitational physics along with Earth and Moon geophysics, geodesy, and dynamics. Although the precision of the range measurements has historically been limited by the ground station capabilities, advances in the APOLLO instrument at the Apache Point facility in New Mexico is beginning to be limited by errors associated with the lunar arrays. We report here on efforts at Goddard Space Flight Center to develop the next generation of lunar retroreflectors. We will describe a new facility that is being used to design, assemble, and test large-scale hollow retroreflectors. We will also describe results from investigations into various bonding techniques used to assemble the open comer cubes and mirror coatings that have dust mitigation properties.

  15. Large-Scale Hollow Retroreflectors for Lunar Laser Ranging at Goddard Space Flight Center

    Science.gov (United States)

    Preston, Alix M.

    2012-05-01

    Laser ranging to the retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions have dramatically increased our understanding of gravitational physics along with Earth and Moon geophysics, geodesy, and dynamics. Although the precision of the range measurements has historically been limited by the ground station capabilities, advances in the APOLLO instrument at the Apache Point facility in New Mexico is beginning to be limited by errors associated with the lunar arrays. We report here on efforts at Goddard Space Flight Center to develop the next generation of lunar retroreflectors. We will describe a new facility that is being used to design, assemble, and test large-scale hollow retroreflectors. We will also describe results from investigations into various bonding techniques used to assemble the open corner cubes and mirror coatings that have dust mitigation properties.

  16. Laser ranging by time-of-flight measurement of femtosecond light pulses

    Science.gov (United States)

    Kim, Young-Jin

    2014-04-01

    Time-of-flight (TOF) measurement of femtosecond light pulses was investigated for laser ranging of long distances with sub-micrometer precision in the air. The bandwidth limitation of the photo-detection electronics used in timing femtosecond pulses was overcome by adopting a type-II nonlinear second-harmonic crystal that permits producing the balanced optical cross-correlation signal between two overlapped light pulses. This method offered a sub-femtosecond timing resolution in determining the temporal offset between two pulses through lock-in control of the pulse repetition rate with reference to the atomic clock. The exceptional ranging capability was verified by measuring various distances from 1.5 m to 700 m. This method is found suited for terrestrial land surveying and space missions of formation-flying satellites.

  17. High precision laser ranging by time-of-flight measurement of femtosecond pulses

    Science.gov (United States)

    Lee, Joohyung; Lee, Keunwoo; Lee, Sanghyun; Kim, Seung-Woo; Kim, Young-Jin

    2012-06-01

    Time-of-flight (TOF) measurement of femtosecond light pulses was investigated for laser ranging of long distances with sub-micrometer precision in the air. The bandwidth limitation of the photo-detection electronics used in timing femtosecond pulses was overcome by adopting a type-II nonlinear second-harmonic crystal that permits the production of a balanced optical cross-correlation signal between two overlapping light pulses. This method offered a sub-femtosecond timing resolution in determining the temporal offset between two pulses through lock-in control of the pulse repetition rate with reference to the atomic clock. The exceptional ranging capability was verified by measuring various distances of 1.5, 60 and 700 m. This method is found well suited for future space missions based on formation-flying satellites as well as large-scale industrial applications for land surveying, aircraft manufacturing and shipbuilding.

  18. A high sensitive 66 dB linear dynamic range receiver for 3-D laser radar

    Science.gov (United States)

    Ma, Rui; Zheng, Hao; Zhu, Zhangming

    2017-08-01

    This study presents a CMOS receiver chip realized in 0.18 μm standard CMOS technology and intended for high precision 3-D laser radar. The chip includes an adjustable gain transimpedance pre-amplifier, a post-amplifier and two timing comparators. An additional feedback is employed in the regulated cascode transimpedance amplifier to decrease the input impedance, and a variable gain transimpedance amplifier controlled by digital switches and analog multiplexer is utilized to realize four gain modes, extending the input dynamic range. The measurement shows that the highest transimpedance of the channel is 50 k {{Ω }}, the uncompensated walk error is 1.44 ns in a wide linear dynamic range of 66 dB (1:2000), and the input referred noise current is 2.3 pA/\\sqrt{{Hz}} (rms), resulting in a very low detectable input current of 1 μA with SNR = 5.

  19. Satellite laser ranging measurements in South Africa: Contributions to earth system sciences

    Directory of Open Access Journals (Sweden)

    Christina M. Botai

    2015-03-01

    Full Text Available This contribution reassesses progress in the development of satellite laser ranging (SLR technology and its scientific and societal applications in South Africa. We first highlight the current global SLR tracking stations within the framework of the International Laser Ranging Service (ILRS and the artificial satellites currently being tracked by these stations. In particular, the present work focuses on analysing SLR measurements at Hartebeesthoek Radio Astronomy Observatory (HartRAO, South Africa, based on the MOBLAS-6 SLR configuration. Generally, there is a weak geometry of ILRS stations in the southern hemisphere and the SLR tracking station at HartRAO is the only active ILRS station operating on the African continent. The SLR-derived products such as station positions and velocities, satellite orbits, components of earth's gravity field and their temporal variations, earth orientation parameters are collected, merged, achieved and distributed by the ILRS under the Crustal Dynamic Data Information System. These products are used in various research fields such as detection and monitoring of tectonic plate motion, crustal deformation, earth rotation, polar motion, and the establishment and monitoring of International Terrestrial Reference Frames, as well as modelling of the spatio-temporal variations of the earth's gravity field. The MOBLAS-6 tracking station is collocated with other geodetic techniques such as very long baseline interferometry and Global Navigation Satellite Systems, thus making this observatory a fiducial geodetic location. Some applications of the SLR data products are described within the context of earth system science.

  20. First successful satellite laser ranging with a fibre-based transmitter

    Science.gov (United States)

    Hampf, D.; Sproll, F.; Wagner, P.; Humbert, L.; Hasenohr, T.; Riede, W.

    2016-08-01

    Satellite laser ranging (SLR) is an established technology used for geodesy, fundamental science and precise orbit determination. This paper reports on the first successful SLR measurement from the German Aerospace Center research observatory in Stuttgart. While many SLR stations are in operation, the experiment described here is unique in several ways: The modular system has been assembled completely from commercial off-the-shelf components, which increases flexibility and significantly reduces hardware costs. To our knowledge it has been the first time that an SLR measurement has been conducted using an optical fibre rather than a coudé path to direct the light from the laser source onto the telescope. The transmitter operates at an output power of about 75 mW and a repetition rate of 3 kHz, and at a wavelength of 1064 nm. Due to its rather small diameter of only 80 μm, the receiver detector features a low noise rate of less than 2 kHz and can be operated without gating in many cases. With this set-up, clear return signals have been received from several orbital objects equipped with retroreflectors. In its current configuration, the system does not yet achieve the same performance as other SLR systems in terms of precision, maximum distance and the capability of daylight ranging; however, plans to overcome these limitations are outlined.

  1. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.D.; Hastings, J.B. [eds.

    1990-12-31

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.

  2. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.D.; Hastings, J.B. (eds.)

    1990-01-01

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.

  3. Corner-cube retro-reflector instrument for advanced lunar laser ranging

    Science.gov (United States)

    Turyshev, Slava G.; Williams, James G.; Folkner, William M.; Gutt, Gary M.; Baran, Richard T.; Hein, Randall C.; Somawardhana, Ruwan P.; Lipa, John A.; Wang, Suwen

    2013-08-01

    Lunar laser ranging (LLR) has made major contributions to our understanding of the Moon's internal structure and the dynamics of the Earth-Moon system. Because of the recent improvements of the ground-based laser ranging facilities, the present LLR measurement accuracy is limited by the retro-reflectors currently on the lunar surface, which are arrays of small corner-cubes. Because of lunar librations, the surfaces of these arrays do not, in general, point directly at the Earth. This effect results in a spread of arrival times, because each cube that comprises the retroreflector is at a slightly different distance from the Earth, leading to the reduced ranging accuracy. Thus, a single, wide aperture corner-cube could have a clear advantage. In addition, after nearly four decades of successful operations the retro-reflectors arrays currently on the Moon started to show performance degradation; as a result, they yield still useful, but much weaker return signals. Thus, fresh and bright instruments on the lunar surface are needed to continue precision LLR measurements. We have developed a new retro-reflector design to enable advanced LLR operations. It is based on a single, hollow corner cube with a large aperture for which preliminary thermal, mechanical, and optical design and analysis have been performed. The new instrument will be able to reach an Earth-Moon range precision of 1-mm in a single pulse while being subjected to significant thermal variations present on the lunar surface, and will have low mass to allow robotic deployment. Here we report on our design results and instrument development effort.

  4. Range accuracy of photon heterodyne detection with laser pulse based on Geiger-mode APD.

    Science.gov (United States)

    Luo, Hanjun; Yuan, XiuHua; Zeng, Yanan

    2013-08-12

    In this paper, we propose a combined system of heterodyne detection with laser pulse and photon counting based on Geiger-mode avalanche photodiode (GM-APD) that is designed to achieve the range of remote non-cooperative target. Based on the heterodyne principle and assuming that the creation of primary electrons in GM-APD is Poisson-distributed, the range accuracy model is established. The factors that influence the range accuracy, namely pulse width, echo intensity, local oscillator (LO) intensity, noise, echo position, and beat frequency, are discussed. The results show that these six factors have significant influence on the range accuracy when the echo intensity is extremely weak. In case that the primary electrons of the echo signal are beyond 4, the pulse width and echo intensity are the main influence factors. It is also shown that the stronger echo intensity, narrower pulse width, low noise, large echo position, and small beat frequency produce higher range accuracy in a pulsed photon heterodyne detection system based on GM-APD.

  5. Experiments and error analysis of laser ranging based on frequency-sweep polarization modulation

    Science.gov (United States)

    Gao, Shuyuan; Ji, Rongyi; Li, Yao; Cheng, Zhi; Zhou, Weihu

    2016-11-01

    Frequency-sweep polarization modulation ranging uses a polarization-modulated laser beam to determine the distance to the target, the modulation frequency is swept and frequency values are measured when transmitted and received signals are in phase, thus the distance can be calculated through these values. This method gets much higher theoretical measuring accuracy than phase difference method because of the prevention of phase measurement. However, actual accuracy of the system is limited since additional phase retardation occurs in the measuring optical path when optical elements are imperfectly processed and installed. In this paper, working principle of frequency sweep polarization modulation ranging method is analyzed, transmission model of polarization state in light path is built based on the theory of Jones Matrix, additional phase retardation of λ/4 wave plate and PBS, their impact on measuring performance is analyzed. Theoretical results show that wave plate's azimuth error dominates the limitation of ranging accuracy. According to the system design index, element tolerance and error correcting method of system is proposed, ranging system is built and ranging experiment is performed. Experiential results show that with proposed tolerance, the system can satisfy the accuracy requirement. The present work has a guide value for further research about system design and error distribution.

  6. Testing relativity again, laser, laser, laser, laser

    NARCIS (Netherlands)

    Einstein, A.

    2015-01-01

    laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser,

  7. Multidiagnostic analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    Energy Technology Data Exchange (ETDEWEB)

    Anoop, K. K., E-mail: anoop.kiliyanamkandy@unina.it; Bruzzese, R.; Amoruso, S. [CNR-SPIN and Dipartimento di Fisica, Universita degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, Napoli 80126 (Italy); Polek, M. P. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Harilal, S. S. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)

    2015-02-28

    The dynamics of ions in ultrafast laser ablation of metals is studied over fluences ranging from the ablation threshold up to ≈75 J/cm{sup 2} by means of three well-established diagnostic techniques. Langmuir probe, Faraday cup, and spectrally resolved intensified charge coupled device imaging simultaneously monitored the ions produced during ultrafast laser ablation of a pure copper target with 800 nm, ≈50 fs, Ti: Sapphire laser pulses. The fluence dependence of ion yield is analyzed, resulting in the observance of three different regimes. The specific ion yield shows a maximum at about 4–5 J/cm{sup 2}, followed by a gradual reduction and a transition to a high-fluence regime above ≈50 J/cm{sup 2}. The fluence dependence of the copper ions angular distribution is also analyzed, observing a gradual increase in forward-peaking of Cu ions for fluences up to ≈10 J/cm{sup 2}. A broader ion component is observed at larger angles for fluences larger than ≈10 J/cm{sup 2}. Finally, an experimental characterization of the ionic angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ≈66 J/cm{sup 2}. Interestingly, the ion emission from the volatile metals shows a narrow, forward-peaked distribution, and a high peak ion yield compared to the refractory metals. Moreover, the width of ionic angular distributions presents a striking correlation with the peak ion yield.

  8. Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor

    Directory of Open Access Journals (Sweden)

    Krug Johannes W.

    2016-09-01

    Full Text Available During a magnetic resonance imaging (MRI exam, a respiratory signal can be required for different purposes, e.g. for patient monitoring, motion compensation or for research studies such as in functional MRI. In addition, respiratory information can be used as a biofeedback for the patient in order to control breath holds or shallow breathing. To reduce patient preparation time or distortions of the MR imaging system, we propose the use of a contactless approach for gathering information about the respiratory activity. An experimental setup based on a commercially available laser range sensor was used to detect respiratory induced motion of the chest or abdomen. This setup was tested using a motion phantom and different human subjects in an MRI scanner. A nasal airflow sensor served as a reference. For both, the phantom as well as the different human subjects, the motion frequency was precisely measured. These results show that a low cost, contactless, laser-based approach can be used to obtain information about the respiratory motion during an MRI exam.

  9. First successful satellite laser ranging with a fibre-based transmitter

    CERN Document Server

    Hampf, Daniel; Wagner, Paul; Humbert, Leif; Hasenohr, Thomas; Riede, Wolfgang

    2016-01-01

    Satellite Laser Ranging (SLR) is an established technology used for geodesy, fundamental science and precise orbit determination. This paper reports on the first successful SLR measurement from the German Aerospace Center research observatory in Stuttgart. While many SLR stations are in operation, the experiment described here is unique in several ways: The modular system has been assembled completely from commercial off-the-shelf components, which increases flexibility and significantly reduces hardware costs. To our knowledge it has been the first time that an SLR measurement has been conducted using an optical fibre rather than a coud\\'e path to direct the light from the laser source onto the telescope. The transmitter operates at an output power of about 75 mW and a repetition rate of 3 kHz, and at a wavelength of 1064 nm. Due to its rather small diameter of only 80 {\\mu}{\\mu}m, the receiver detector features a low noise rate of less than 2 kHz and can be operated without gating in many cases. With this s...

  10. Novel Single-Frequency Diode Pumped Solid-State Lasers and Their Applications in Laser Ranging and Velocimetry

    Institute of Scientific and Technical Information of China (English)

    杨苏辉; 吴克瑛; 魏光辉

    2001-01-01

    Two models of laser diode pumped unidirectional single-frequency ring lasers with maximum single-frequency output powers of 1 W and 780mW are investigated. The statistical linewidth of the free-run laser is measured to be 2.1 kHz within 5μs by using a single-mode fibre link. We use the monolithic laser to measure the angular speed of a spinning motor and simulate a linearly frequency modulated continuous-wave ladar system in the laboratory.

  11. High-precision gravimetric survey in support of lunar laser ranging at Haleakala, Maui, 1976 - 1978

    Science.gov (United States)

    Schenck, B. E.; Laurila, S. H.

    1978-01-01

    The planning, observations and adjustment of high-precision gravity survey networks established on the islands of Maui and Oahu as part of the geodetic-geophysical program in support of lunar laser ranging at Haleakala, Maui, Hawaii are described. The gravity survey networks include 43 independently measured gravity differences along the gravity calibration line from Kahului Airport to the summit of Mt. Haleakala, together with some key points close to tidal gauges on Maui, and 40 gravity differences within metropolitan Honolulu. The results of the 1976-1978 survey are compared with surveys made in 1961 and in 1964-1965. All final gravity values are given in the system of the international gravity standardization net 1971 (IGSN 71); values are obtained by subtracting 14.57 mgal from the Potsdam value at the gravity base station at the Hickam Air Force Base, Honolulu.

  12. Testing for Lorentz violation: constraints on standard-model-extension parameters via lunar laser ranging.

    Science.gov (United States)

    Battat, James B R; Chandler, John F; Stubbs, Christopher W

    2007-12-14

    We present constraints on violations of Lorentz invariance based on archival lunar laser-ranging (LLR) data. LLR measures the Earth-Moon separation by timing the round-trip travel of light between the two bodies and is currently accurate to the equivalent of a few centimeters (parts in 10(11) of the total distance). By analyzing this LLR data under the standard-model extension (SME) framework, we derived six observational constraints on dimensionless SME parameters that describe potential Lorentz violation. We found no evidence for Lorentz violation at the 10(-6) to 10(-11) level in these parameters. This work constitutes the first LLR constraints on SME parameters.

  13. Exploring the depth range for three-dimensional laser machining with aberration correction.

    Science.gov (United States)

    Salter, P S; Baum, M; Alexeev, I; Schmidt, M; Booth, M J

    2014-07-28

    The spherical aberration generated when focusing from air into another medium limits the depth at which ultrafast laser machining can be accurately maintained. We investigate how the depth range may be extended using aberration correction via a liquid crystal spatial light modulator (SLM), in both single point and parallel multi-point fabrication in fused silica. At a moderate numerical aperture (NA = 0.5), high fidelity fabrication with a significant level of parallelisation is demonstrated at the working distance of the objective lens, corresponding to a depth in the glass of 2.4 mm. With a higher numerical aperture (NA = 0.75) objective lens, single point fabrication is demonstrated to a depth of 1 mm utilising the full NA, and deeper with reduced NA, while maintaining high repeatability. We present a complementary theoretical model that enables prediction of the effectiveness of SLM based correction for different aberration magnitudes.

  14. Test environments for the GRACE follow-on laser ranging interferometer

    Science.gov (United States)

    Görth, A.; Sanjuan, J.; Gohlke, M.; Rasch, S.; Abich, K.; Braxmaier, C.; Heinzel, G.

    2016-05-01

    In the year 2017 a follow-on mission to the very successful joint German/US mission GRACE (Gravity Recovery And Climate Experiment) will be launched. As of this day the two GRACE satellites have successfully been mapping the spatial and temporal varitations of the gravitational field of the Earth by satellite-to-satellite tracking for over a decade. The main science instrument on GRACE and its successor mission GRACE Follow-On which is used to measure the inter-satellite distance changes is a microwave link sensor. However, an additional instrument, the laser ranging interferometer (LRI), will be implemented into the architecture of the GRACE Follow-On satellites as a technology demonstrator. In this paper we will give a brief overview of a fiber-based test environment which is currently used during the assembly, integration and test of the LRI flight hardware.

  15. High-power laser delocalization in plasmas leading to long-range beam merging

    Energy Technology Data Exchange (ETDEWEB)

    Nakatsutsumi, M.; Marques, J.R.; Antici, P.; Bourgeois, N.; Romagnani, L.; Audebert, P.; Fuchs, J. [UPMC, CEA, CNRS, LULI, Ecole Polytech, F-91128 Palaiseau (France); Nakatsutsumi, M.; Kodama, R. [Osaka Univ, Grad Sch Engn, Suita, Osaka 5650871 (Japan); Antici, P. [Univ Roma La Sapienza, Dipartimento SBAI, I-00161 Rome (Italy); Feugeas, J.L.; Nicolai, P. [Univ Bordeaux 1, CNRS, CEA, Ctr Lasers Intenses and Applicat, F-33405 Talence (France); Lin, T. [Fox Chase Canc Ctr, Philadelphia, PA 19111 (United States)

    2010-07-01

    Attraction and fusion between co-propagating light beams, mutually coherent or not, can take place in nonlinear media as a result of the beam power modifying the refractive index of the medium. In the context of high-power light beams, induced modifications of the beam patterns could potentially impact many topics, including long-range laser propagation, the study of astrophysical colliding blast waves and inertial confinement fusion. Here, through experiments and simulations, we show that in a fully ionized plasma, which is a nonlinear medium, beam merging can take place for high-power and mutually incoherent beams that are initially separated by several beam diameters. This is in contrast to the usual assumption that this type of interaction is limited to beams separated by only one beam diameter. This effect, which is orders of magnitude more significant than Kerr-like nonlinearity in gases, demonstrates the importance of potential cross-talk amongst multiple beams in plasma. (authors)

  16. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect pho- ton bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference — only in that frame is the speed of light isotropic, but also fluctuations / turbulence (gravitational waves in the flow of the dynamical 3-space rela- tive to local systems / observers. So the APOLLO facility can act as an e ective “gravi- tational wave” detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave / turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  17. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect photon bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference - only in that frame is the speed of light isotropic, but also fluctuations/turbulence (gravitational waves in the flow of the dynamical 3-space relative to local systems/observers. So the APOLLO facility can act as an effective "gravitational wave" detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave/turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  18. Selective ablation of WHHLMI rabbit atherosclerotic plaque by quantum cascade laser in the 5.7 μm wavelength range for less-invasive laser angioplasty

    Science.gov (United States)

    Hashimura, Keisuke; Ishii, Katsunori; Akikusa, Naota; Edamura, Tadataka; Yoshida, Harumasa; Awazu, Kunio

    2013-06-01

    We investigated the potential of a compact and high-power quantum cascade laser (QCL) in the 5.7 μm wavelength range for less-invasive laser angioplasty. Atherosclerotic plaques consist mainly of cholesteryl esters. Radiation at a wavelength of 5.75 μm is strongly absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a normal artery and an atherosclerotic lesions using nanosecond pulsed laser by difference-frequency generation (DFG laser) at the wavelength of 5.75 μm. For applying this technique to clinical treatment, a compact laser device is required. In this study, QCL irradiation effects to a porcine normal aorta were compared with DFG laser. Subsequently, QCL irradiation effects on an atherosclerotic aorta of myocardial infarction-prone Watanabe heritable hyperlipidemic rabbit (WHHLMI rabbit) and a normal rabbit aorta were observed. As a result, the QCL could make cutting differences between the rabbit atherosclerotic and normal aortas. On the other hand, the QCL induced more thermal damage to porcine normal aorta than the DFG laser at the irradiation condition of comparable ablation depths. In conclusion, the possibility of less-invasive and selective treatment of atherosclerotic plaques using the QCL in the 5.7 μm wavelength range was revealed, although improvement of QCL was required to prevent the thermal damage of a normal artery.

  19. Femtosecond laser nanostructuring of titanium metal towards fabrication of low-reflective surfaces over broad wavelength range

    Science.gov (United States)

    Dar, Mudasir H.; Kuladeep, R.; Saikiran, V.; Narayana Rao, D.

    2016-05-01

    We investigated experimentally the formation of laser induced periodic surface structures (LIPSS) on titanium (Ti) metal upon irradiation with linearly polarized Ti:Sapphire femtosecond (fs) laser pulses of ∼110 fs pulse width and 800 nm wavelength in air and water environments. It is observed that initially formed random and sparsely distributed nano-roughness (nanoholes, nanoparticles and nanoprotrusions) gets periodically structured with increase in number of laser pulses. In air at lower fluence, we observed the formation of high spatial frequency-LIPSS (HSFL) oriented parallel to the laser polarization direction, whereas at higher fluence formation of low spatial frequency-LIPSS (LSFL) were observed that are oriented perpendicular to the incident laser polarization. In water two types of subwavelength structures were observed, one with spatial periodicity of ∼λ/15 and oriented parallel to laser polarization, while the other oriented perpendicular to laser polarization with feature size of λ/4. The optimal conditions for fabricating periodic sub-wavelength structures are determined by controlling the fluence and pulse number. The fs laser induced surface modifications were found to suppress the specular reflection of the Ti surface over a wide wavelength range of 250-2000 nm to a great extent.

  20. An efficient flashlamp-pumped laser tunable in the IR range and using chromium-activated forsterite crystals

    Energy Technology Data Exchange (ETDEWEB)

    Baryshevskii, V.G.; Voloshin, V.A.; Demidovich, S.A.; Kimaev, A.E.; Korzhik, M.V. (Belorusskii Gosudarstvennyi Universitet, Minsk (Belorussian SSR))

    1990-11-01

    Efficient frequency-tunable lasing was obtained from Mg2SiO4:Cr single crystals under flashlamp pumping. The feasibility of using chromium ion absorption bands localized in the UV region for optical pumping is demonstrated. Wavelength tuning in the 1170-1330 nm range was obtained in a selective resonator for an output-mirror reflection coefficient of 86 percent. This laser may find application in fiber-optic communications and laser-radar systems.

  1. Demonstration of orbit determination for the Lunar Reconnaissance Orbiter using one-way laser ranging data

    Science.gov (United States)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2016-09-01

    We used one-way laser ranging data from International Laser Ranging Service (ILRS) ground stations to NASA's Lunar Reconnaissance Orbiter (LRO) for a demonstration of orbit determination. In the one-way setup, the state of LRO and the parameters of the spacecraft and all involved ground station clocks must be estimated simultaneously. This setup introduces many correlated parameters that are resolved by using a priori constraints. Moreover the observation data coverage and errors accumulating from the dynamical and the clock modeling limit the maximum arc length. The objective of this paper is to investigate the effect of the arc length, the dynamical and modeling accuracy and the observation data coverage on the accuracy of the results. We analyzed multiple arcs using lengths of 2 and 7 days during a one-week period in Science Mission phase 02 (SM02, November 2010) and compared the trajectories, the post-fit measurement residuals and the estimated clock parameters. We further incorporated simultaneous passes from multiple stations within the observation data to investigate the expected improvement in positioning. The estimated trajectories were compared to the nominal LRO trajectory and the clock parameters (offset, rate and aging) to the results found in the literature. Arcs estimated with one-way ranging data had differences of 5-30 m compared to the nominal LRO trajectory. While the estimated LRO clock rates agreed closely with the a priori constraints, the aging parameters absorbed clock modeling errors with increasing clock arc length. Because of high correlations between the different ground station clocks and due to limited clock modeling accuracy, their differences only agreed at the order of magnitude with the literature. We found that the incorporation of simultaneous passes requires improved modeling in particular to enable the expected improvement in positioning. We found that gaps in the observation data coverage over 12 h (≈6 successive LRO orbits

  2. Full Waveform Analysis for Long-Range 3D Imaging Laser Radar

    Directory of Open Access Journals (Sweden)

    Wallace AndrewM

    2010-01-01

    Full Text Available The new generation of 3D imaging systems based on laser radar (ladar offers significant advantages in defense and security applications. In particular, it is possible to retrieve 3D shape information directly from the scene and separate a target from background or foreground clutter by extracting a narrow depth range from the field of view by range gating, either in the sensor or by postprocessing. We discuss and demonstrate the applicability of full-waveform ladar to produce multilayer 3D imagery, in which each pixel produces a complex temporal response that describes the scene structure. Such complexity caused by multiple and distributed reflection arises in many relevant scenarios, for example in viewing partially occluded targets, through semitransparent materials (e.g., windows and through distributed reflective media such as foliage. We demonstrate our methodology on 3D image data acquired by a scanning time-of-flight system, developed in our own laboratories, which uses the time-correlated single-photon counting technique.

  3. Lunar Laser Ranging Tests of the Equivalence Principle with the Earth and Moon

    CERN Document Server

    Williams, J G; Boggs, D H; Williams, James G.; Turyshev, Slava G.; Boggs, Dale H.

    2005-01-01

    A primary objective of the Lunar Laser Ranging (LLR) experiment is to provide precise observations of the lunar orbit that contribute to a wide range of science investigations. Time series of the highly accurate measurements of the distance between the Earth and Moon provide unique information used to determine whether, in accordance with the Equivalence Principle (EP), both of these celestial bodies are falling towards the Sun at the same rate, despite their different masses, compositions, and gravitational self-energies. Current LLR solutions give $(-1.0 \\pm 1.4) \\times 10^{-13}$ for any possible inequality in the ratios of the gravitational and inertial masses for the Earth and Moon, $\\Delta(M_G/M_I)$. This result, in combination with laboratory experiments on the weak equivalence principle, yields a strong equivalence principle (SEP) test of $\\Delta(M_G/M_I)_{\\tt SEP} = (-2.0 \\pm 2.0) \\times 10^{-13}$. Such an accurate result allows other tests of gravitational theories. The result of the SEP test transla...

  4. Long-range pulselength scaling of 351nm laser damage thresholds

    Science.gov (United States)

    Foltyn, S. R.; Jolin, L. J.

    1986-12-01

    In a series of experiments incorporating 351nm pulselength of 9, 26, 54, and 625ns, it was found that laser damage thresholds increased as (pulselength)/sup x/, and that the exponent averaged 0.36 and ranged, for different samples, from 0.23 to 0.48. Similar results were obtained when only catastrophic damage was considered. Samples included Al2O3/SiO2 in both AR and HR multilayers, HR's of Sc2O3/SiO2 and HfO2/SiO2, and Al-on-pyrex mirror; 9ns thresholds were between 0.2 to 5.6 J/sq cm. When these data were compared with a wide range of other results - for wavelengths from 0.25 to 10.6 microns and pulselengths down to 4ps - a remarkably consistent picture emerged. Damage thresholds, on average, increase approximately as the cube-root of pulselength from picoseconds to nearly a microsecond, and do so regardless of wavelength or material under test.

  5. Normal point generation and first photon bias correction in APOLLO lunar laser ranging

    Science.gov (United States)

    Michelsen, Eric Leonard

    2010-11-01

    The APOLLO Lunar Laser Ranging (LLR) system studies gravity by tracing out the orbit of the moon to ~1 mm, over many years. LLR in general provides extensive tests of many aspects of gravity, including deviations from General Relativity (GR), and time rate-of-change of the gravitational constant, G. APOLLO's precision is approximately 10x better than previous LLR measurements, enabling about an order of magnitude improvement in tests of gravity over the coming years. APOLLO requires complex data reduction methods to extract the distance so precisely. There are currently three choices for determining the round-trip-time to the moon from the data: the correlation method, the Augmented Calculation method, and the PDF-fit method. The results here suggest the PDF-fit method as preferable, for minimum random uncertainty over the full operating range of conditions, and stable systematic error below ~1 mm. As a second topic, the APOLLO system includes a systematic error called "First Photon Bias," which causes time measurements to be skewed early. An algorithm is presented and simulated, showing that it is inherently capable of achieving < 1 mm systematic error under normal operating conditions. However, the final algorithm requires a correction table calibrated from a more accurate model of shot-to-shot intensity fluctuations. Such a table could be the subject of future investigations.

  6. Determination of the tectonic plate motion by satellite laser ranging in 1999-2003

    Science.gov (United States)

    Schillak, S.; Wnuk, E.

    The paper presents results of the tectonic plates motion determination from satellite laser ranging in the period 1999-2003 The SLR station velocities were calculated from station geocentric coordinates determined from one month orbital arcs of Lageos-1 and Lageos-2 satellites for the first day of each arc The mean orbital RMS-of-fit for 5 years was equal to 15 mm The station velocities were determined for 29 stations and points in 1999-2003 it means for all SLR stations with data time span longer than 20 months The accuracy of station velocities determination varied from 0 4 mm year to 3 mm year dependent on quality of data and data span The difference of station velocities between ITRF2000 and the presented results were in the range 0-5 mm year Only for four stations Riyad Maidanak-2 Beijng and Arequipa after earthquake in 2001 the differences were statistically significant For the most stations is a good agreement with the NUVEL1A model of tectonic plates motion The significant differences were detected for stations Arequipa Concepcion Shanghai and Simosato The results differs from the model NUVEL1A in the station velocities and azimuths for South America tectonic plate and Japan

  7. Geophysical interpretation of satellite laser ranging measurements of crustal movement in California

    Science.gov (United States)

    Cohen, Steven C.

    1985-12-01

    As determined by satellite laser ranging the rate of contraction of a 900 km baseline between sites located near Quincy in northern California and San Diego in southern California is about 61-65 mm/yr with a formal uncertainty of about 10 mm/yr (Christodoulidis et al., 1985). The measured changes in baseline length are a manifestation of the relative motion between the North America and Pacific tectonic plates. This long baseline result is compared to measurements made by more conventional means on shorter baselines. Additional information based on seismiscity, geology, and theoretical modelling is also analyzed. Deformation lying within a few tens of kilometers about the major faults in southern California accounts for most, but not all, of the observed motion. Further motion is attributable to a broader-scale deformation in southern California. Data suggesting crustal movements north of the Garlock fault, in and near the southern Sierra Nevada and local motion at an observatory are also critically reviewed. The best estimates of overall motion indicated by ground observations lie between 40 and 60 mm/yr. This lies within one or two standard deviations of that deduced from satellite ranging but the possibility of some unresolved deficit cannot be entirely dismissed. The long time scale RM2 plate tectonic model of Minster and Jordan (1978) predicts a contraction between 47 and 53 mm/yr depending on the extension rate of the Basin and Range. Thus the ground based observations, SLR results, and RM2 rates differ at about the 10 mm/yr level but are not inconsistent with one another within the data and model uncertainties.

  8. Optimization and control of the sweeping range in an Yb-doped self-sweeping fiber laser

    Science.gov (United States)

    Lobach, I. A.; Tkachenko, A. Yu; Kablukov, S. I.

    2016-04-01

    Influence of the laser cavity parameters (an active fiber length and output coupling losses) and the temperature of elements (active fiber and pump laser diode) on the sweeping range in an Yb-doped self-sweeping laser is investigated. The obtained results show that the sweeping spectral region is shifted to shorter wavelengths for shorter active fibers and with increasing absorbed power. This allows one to obtain self-sweeping operation in a broad range within a ytterbium gain bandwidth from 1028 to 1080 nm. At the same time, there are optimal cavity parameters at which the sweeping span is the broadest (>20 nm). Good agreement between the experimental sweeping range and the calculated maximum gain wavelength is demonstrated.

  9. MICCAI Workshops

    CERN Document Server

    Nedjati-Gilani, Gemma; Venkataraman, Archana; O'Donnell, Lauren; Panagiotaki, Eleftheria

    2014-01-01

    This volume contains the proceedings from two closely related workshops: Computational Diffusion MRI (CDMRI’13) and Mathematical Methods from Brain Connectivity (MMBC’13), held under the auspices of the 16th International Conference on Medical Image Computing and Computer Assisted Intervention, which took place in Nagoya, Japan, September 2013. Inside, readers will find contributions ranging from mathematical foundations and novel methods for the validation of inferring large-scale connectivity from neuroimaging data to the statistical analysis of the data, accelerated methods for data acquisition, and the most recent developments on mathematical diffusion modeling. This volume offers a valuable starting point for anyone interested in learning computational diffusion MRI and mathematical methods for brain connectivity as well as offers new perspectives and insights on current research challenges for those currently in the field. It will be of interest to researchers and practitioners in computer science, ...

  10. ESA activities on satellite laser ranging to non-cooperative objects

    Science.gov (United States)

    Flohrer, Tim; Krag, Holger; Funke, Quirin; Jilete, Beatriz; Mancas, Alexandru

    2016-07-01

    Satellite laser ranging (SLR) to non-cooperative objects is an emerging technology that can contribute significantly to operational, modelling and mitigation needs set by the space debris population. ESA is conducting various research and development activities in SLR to non-cooperative objects. ESA's Space Situational Awareness (SSA) program supports specific activities in the Space Surveillance and Tracking (SST) segment. Research and development activities with operational aspects are run by ESA's Space Debris Office. At ESA SSA/SST comprises detecting, cataloguing and predicting the objects orbiting the Earth, and the derived applications. SST aims at facilitating research and development of sensor and data processing technologies and of related common components while staying complementary with, and in support of, national and multi-national European initiatives. SST promotes standardisation and interoperability of the technology developments. For SLR these goals are implemented through researching, developing, and deploying an expert centre. This centre shall coordinate the contribution of system-external loosely connected SLR sensors, and shall provide back calibration and expert evaluation support to the sensors. The Space Debris Office at ESA is responsible for all aspects related to space debris in the Agency. It is in charge of providing operational support to ESA and third party missions. Currently, the office studies the potential benefits of laser ranging to space debris objects to resolve close approaches to active satellites, to improve re-entry predictions of time and locations, and the more general SLR support during contingency situations. The office studies the determination of attitude and attitude motion of uncooperative objects with special focus on the combination of SLR, light-curve, and radar imaging data. Generating sufficiently precise information to allow for the acquisition of debris objects by a SLR sensor in a stare

  11. Study of efficiency and optimization parameters of laser device for measuring the range rate of a spacecraft

    Directory of Open Access Journals (Sweden)

    E. I. Starovoitov

    2014-01-01

    Full Text Available To replace the hand-held laser rangefinders on board transport spacecraft (SC a laser rangefinder-speedometer (LRS is developed and installed in the unpressurized area of SC to determine automatically the range rate. Crew, turning the active spacecraft by the video image that is formed by a docking camera, manually provides guidance of LRS to the passive SC. Using a generalized function of efficiency was estimated LRS characteristics. Comparison with the results of existing analogues shows that the LRS has the highest efficiency. As a result of relationship analysis of measuring speed and reliability accuracy of LRS laser source, Pareto sets are obtained, which enable providing the optimal operation conditions of a device It is found that the reliability function of LRS, which is equal to 0.999, is ensured at 1.0 s averaging time of range measurement and 0.8...0.9 m range measurement error. Increasing the averaging time of range measurement up to 1.5 s allows reliability function equal to 0.999 with the range measurement error of 2.5...2.5 m. Energy calculations are performed for 5 km range measurements on space complex with a complicated configuration such as the International Space Station (ISS for the maximum and minimum value of the effective reflection area. When the laser pulse energy is 11.5 mJ for measurements of diffusely reflected signal at ranges of 5 km at least a signal/noise ratio is no less than 10. With LRS illuminating the angular reflector, a measurement range is of over 30 km. Because of a large number of the angular reflectors on the ISS body is considered the use of the geometric factor to protect the photo-detector overload when receiving a signal from the nearby angular reflector. It is found that when the length of the base between the receiving and transmitting optical apertures is equal to 39 mm, a photo-detector is protected from the overload at the pulse energies up to 11.5 mJ. The results of efficiency evaluation

  12. A method to calculate zero-signature satellite laser ranging normal points for millimeter geodesy - a case study with Ajisai

    Science.gov (United States)

    Kucharski, Daniel; Kirchner, Georg; Otsubo, Toshimichi; Koidl, Franz

    2015-03-01

    High repetition-rate satellite laser ranging (SLR) offers new possibilities for the post-processing of the range measurements. We analyze 11 years of kHz SLR passes of the geodetic satellite Ajisai delivered by Graz SLR station (Austria) in order to improve the accuracy and precision of the principal SLR data product - normal points. The normal points are calculated by three different methods: 1) the range residuals accepted by the standard 2.5 sigma filter, 2) the range residuals accepted by the leading edge filter and 3) the range residuals given by the single corner cube reflector (CCR) panels of Ajisai.

  13. 3D indoor modeling using a hand-held embedded system with multiple laser range scanners

    Science.gov (United States)

    Hu, Shaoxing; Wang, Duhu; Xu, Shike

    2016-10-01

    Accurate three-dimensional perception is a key technology for many engineering applications, including mobile mapping, obstacle detection and virtual reality. In this article, we present a hand-held embedded system designed for constructing 3D representation of structured indoor environments. Different from traditional vehicle-borne mobile mapping methods, the system presented here is capable of efficiently acquiring 3D data while an operator carrying the device traverses through the site. It consists of a simultaneous localization and mapping(SLAM) module, a 3D attitude estimate module and a point cloud processing module. The SLAM is based on a scan matching approach using a modern LIDAR system, and the 3D attitude estimate is generated by a navigation filter using inertial sensors. The hardware comprises three 2D time-flight laser range finders and an inertial measurement unit(IMU). All the sensors are rigidly mounted on a body frame. The algorithms are developed on the frame of robot operating system(ROS). The 3D model is constructed using the point cloud library(PCL). Multiple datasets have shown robust performance of the presented system in indoor scenarios.

  14. Investigating relativity using lunar laser ranging - Geodetic precession and the Nordtvedt effect

    Science.gov (United States)

    Dickey, J. O.; Newhall, X. X.; Williams, J. G.

    1989-01-01

    The emplacement of retroreflectors on the moon by Apollo astronauts and the Russian Lunakhod spacecraft marked the inception of lunar laser ranging (LLR) and provided a natural laboratory for the study of general relativity. Continuing acquisition of increasingly accurate LLR data has provided enhanced sensitivity to general relativity parameters. Two relativistic effects are investigated in this paper: (1) the Nordtvedt effect, yielding a test of the strong equivalence principle, would appear as a distortion of the geocentric lunar orbit in the direction of the sun. The inclusion of recent LLR data limits the size of any such effect to 3 + or - 4 cm. The sensitivities to the various PPN quantities are also highlighted. (2) the geodetic precession of the lunar perigee is predicted by general relativity as a consequence of the motion of the earth-moon system about the sun; its theoretical magnitude is 19.2 mas/yr. Analysis presented here confirms this value and determines this quality to a 2 percent level.

  15. A total station spatial positioning method based on rotary laser scanning and ultrasonic ranging

    Science.gov (United States)

    Wu, Jun; Zhu, Jigui; Yu, Zhijing; Zhuge, Jingchang; Xue, Bin

    2016-11-01

    Total station spatial coordinator measuring technology is extensively applied in the large-scale measurement of industrial assembly and manufacturing for its flexibility and adaptability. The existing total station technology has some principal limits such as poor efficiency and single tasking; in order to achieve the total station spatial coordinator measuring technology with the advantages of multi-task, real-time measurement, and high accuracy, this paper presents a novel total station measurement method by using multi-laser plane constraints established through rotating planar planes and distance information obtained with an ultrasonic ranging method. With the spatial divergence angles of the optoelectronic scanning and ultrasonic arrays, this method can measure the spatial coordinates in multi-task and real-time with a single station and a portable target bar. Experimental results show that the proposed method is feasible and valid with satisfactory accuracy. The maximum distance measurement error is less than 0.2 mm in a volume that is 5 m far away from the station.

  16. False alarm suppression of multipulsed laser ranging system with Geiger-mode detector.

    Science.gov (United States)

    Luo, Hanjun; Xu, Huigang; Xu, Benlian; Ouyang, Zhengbiao; Fu, Yadan

    2015-06-10

    The false alarm probability is of great concern when designing and evaluating the performance of a multipulsed laser ranging system with a Geiger-mode avalanche photodiode. In this paper, based on the statistical distribution difference of the arrival time of the echo photons and noise in the time histogram, a false alarm suppression algorithm is presented. According to the data-processing method of the algorithm, the theoretical model of target detection and false alarm probability with a Poisson statistic and the system working at long dead time is established. With typical system design parameters, the target detection probability under different echo intensity and detection number is analyzed, and the influence of four main factors, namely, detection number, echo intensity, noise, and echo position, on the false alarm probability is investigated. The results show that multipulsed detection can improve the target detection probability, and using this developed algorithm, the false alarm probability can be effectively suppressed, to obtain an appropriate false alarm probability; it is suitable that the detection number is selected as 8; and stronger echo intensity, lower noise level, and a more frontal echo position can result in a lower false alarm probability.

  17. Indoor radiation mapping using the Laser Assisted Ranging and Data System (LARADS). Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-01

    The US Department of Energy`s (DOE`s) nuclear facilities require characterization and documentation of the results as part of planning and decision-making for decontamination and decommissioning (D and D) projects and to release areas that have been cleaned up. Conducting radiation surveys of indoor and outdoor surfaces and generating accurate survey reports is an important component of the D and D program. The Laser Assisted Ranging and Data System (LARADS) is a characterization technology that provides real-time data on the location and concentration levels of radiological contamination. The system can be utilized with a number of available detection instruments and can be integrated with existing data analysis and mapping software technologies to generate superior quality survey data reports. This innovative technology is competitive with baseline technologies in terms of cost and survey times, but is much more flexible and provides more useful reports. The system also has the capability of electronically logging survey data, making it easy to store and retrieve. Such data are scientifically derived and not subject to interpretation. The LARADS is an extremely attractive alternative to manually generated survey data reports.

  18. Dynamic Track Management in MHT for Pedestrian Tracking Using Laser Range Finder

    Directory of Open Access Journals (Sweden)

    Abdul Hadi Abd Rahman

    2015-01-01

    Full Text Available Real time pedestrian tracking could be one of the important features for autonomous navigation. Laser Range Finder (LRF produces accurate pedestrian data but a problem occurs when a pedestrian is represented by multiple clusters which affect the overall tracking process. Multiple Hypothesis Tracking (MHT is a proven method to solve tracking problem but suffers a large computational cost. In this paper, a multilevel clustering of LRF data is proposed to improve the accuracy of a tracking system by adding another clustering level after the feature extraction process. A Dynamic Track Management (DTM is introduced in MHT with multiple motion models to perform a track creation, association, and deletion. The experimental results from real time implementation prove that the proposed multiclustering is capable of producing a better performance with less computational complexity for a track management process. The proposed Dynamic Track Management is able to solve the tracking problem with lower computation time when dealing with occlusion, crossed track, and track deletion.

  19. Next generation retroreflector for lunar laser ranging: science, design and flight status

    Science.gov (United States)

    Currie, Douglas; Richards, Robert; Delle Monache, Giovanni

    2016-07-01

    The retroreflectors deployed during the Apollo Mission are still operating after 45 years. Analysis of the ranging data has resulted in the discovery and measurement of the liquid core of the moon about 15 years ago. This lunar laser ranging (LLR) program has also produced most of the best tests of Gravitation and General Relativity. However, over the years the ground stations have improved by a factor of ~200 so today the limit in ranging accuracy is due to the combination of the libration of the moon and the design of the Cube Corner Reflector (CCR) arrays. To address this, the University of Maryland, College Park (UMCP) and the INFN-LNF are developing the Next Generation Retroreflectors (NGR. Recently the UMCP and the LNF have signed an agreement with Moon Express, Inc., a commercial company pursuing the Google Lunar X Prize and a space transport business, to deploy four NGRs on the lunar surface, the first of which is expected to fly in the second quarter of 2017. A brief discussion will address the expected improvements in the understanding of Gravitational and General Relativity and the impact this may have on the multiple theories that have been proposed to explain Dark Matter and Dark Energy. The basic objectives, requirements and design will be reviewed. In particular, in order to maintain a signal level similar to that of Apollo 15, thermal gradients within the CCR must be maintain to less than 0.2oK. Since during lunar morning the CCR is at about 70oK and the housing is more than 300oK, the thermal design is critical. The structure and results of the required simulation programs will be reviewed. Finally, the current design of the entire package will be addressed. Looking toward the future, two areas look particularly interesting in extending the coverage of the theories of Gravitation, General Relativity, Dark Matter and Dark Energy. They will support even greater ranging accuracy, additional ground stations and increased coverage. The first is to

  20. Calibration between a Laser Range Scanner and an Industrial Robot Manipulator

    DEFF Research Database (Denmark)

    Andersen, Thomas Timm; Andersen, Nils Axel; Ravn, Ole

    2014-01-01

    In this paper we present a method for findingthe transformation between a laser scanner and a robotmanipulator. We present the design of a flat calibration targetthat can easily fit between a laser scanner and a conveyor belt,making the method easily implementable in a manufacturingline.We prove...

  1. Processing and Application of ICESat Large Footprint Full Waveform Laser Range Data

    NARCIS (Netherlands)

    Duong, V.H.

    2010-01-01

    In the last two decades, laser scanning systems made the transition from scientific research to the commercial market. Laser scanning has a large variety of applications such as digital elevation models, forest inventory and man-made object reconstruction, and became the most required input data for

  2. Long-range laser scanning and 3D imaging for the Gneiss quarries survey

    Science.gov (United States)

    Schenker, Filippo Luca; Spataro, Alessio; Pozzoni, Maurizio; Ambrosi, Christian; Cannata, Massimiliano; Günther, Felix; Corboud, Federico

    2016-04-01

    In Canton Ticino (Southern Switzerland), the exploitation of natural stone, mostly gneisses, is an important activity of valley's economies. Nowadays, these economic activities are menaced by (i) the exploitation costs related to geological phenomena such as fractures, faults and heterogeneous rocks that hinder the processing of the stone product, (ii) continuously changing demand because of the evolving natural stone fashion and (iii) increasing administrative limits and rules acting to protect the environment. Therefore, the sustainable development of the sector for the next decades needs new and effective strategies to regulate and plan the quarries. A fundamental step in this process is the building of a 3D geological model of the quarries to constrain the volume of commercial natural stone and the volume of waste. In this context, we conducted Terrestrial Laser Scanning surveys of the quarries in the Maggia Valley to obtain a detailed 3D topography onto which the geological units were mapped. The topographic 3D model was obtained with a long-range laser scanning Riegl VZ4000 that can measure from up to 4 km of distance with a speed of 147,000 points per second. It operates with the new V-line technology, which defines the surface relief by sensing differentiated signals (echoes), even in the presence of obstacles such as vegetation. Depending on the esthetics of the gneisses, we defined seven types of natural stones that, together with faults and joints, were mapped onto the 3D models of the exploitation sites. According to the orientation of the geological limits and structures, we projected the different rock units and fractures into the excavation front. This way, we obtained a 3D geological model from which we can quantitatively estimate the volume of the seven different natural stones (with different commercial value) and waste (with low commercial value). To verify the 3D geological models and to quantify exploited rock and waste volumes the same

  3. International Conference: Fundamentals of Laser Assisted Micro- & Nanotechnologies (FLAMN-07). Workshop: Laser Cleaning and Artworks Conservation (LCAC). St. Petersburg, Russia, 25-28 June 2007. Abstracts

    Science.gov (United States)

    2007-06-28

    fungi, lichens and other biological growth. For removal of patinations from the surface of white marble a Nd:YAG free- running laser (model Smart...Expression plasmid DNA for a firefly luminescence enzyme, luciferase, was injected into tibial muscle and mousse, and then laser-induced shock wave was

  4. Selective treatment of carious dentin using a mid-infrared tunable pulsed laser at 6 μm wavelength range

    Science.gov (United States)

    Saiki, Masayuki; Ishii, Katsunori; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

    2011-03-01

    Optical technologies have good potential for caries detection, prevention, excavation, and the realization of minimal intervention dentistry. This study aimed to develop a selective excavation technique of carious tissue using the specific absorption in 6 μm wavelength range. Bovine dentin demineralized with lactic acid solution was used as a carious dentin model. A mid-infrared tunable pulsed laser was obtained by difference-frequency generation technique. The wavelength was tuned to 6.02 and 6.42 μm which correspond to absorption bands called amide I and amide II, respectively. The laser delivers 5 ns pulse width at a repetition rate of 10 Hz. The morphological change after irradiation was observed with a scanning electron microscope, and the measurement of ablation depth was performed with a confocal laser microscope. At λ = 6.02 μm and the average power density of 15 W/cm2, demineralized dentin was removed selectively with less-invasive effect on sound dentin. The wavelength of 6.42 μm also showed the possibility of selective removal. High ablation efficiency and low thermal side effect were observed using the nanosecond pulsed laser with λ = 6.02 μm. In the near future, development of compact laser device will open the minimal invasive laser treatment to the dental clinic.

  5. INDICO Workshop

    CERN Document Server

    CERN. Geneva; Fabbrichesi, Marco

    2004-01-01

    The INtegrated DIgital COnferencing EU project has finished building a complete software solution to facilitate the MANAGEMENT OF CONFERENCES, workshops, schools or simple meetings from their announcement to their archival. Everybody involved in the organization of events is welcome to join this workshop, in order to understand the scope of the project and to see demonstrations of the various features.

  6. Diode lasers with asymmetric barriers for 850 nm spectral range: experimental studies of power characteristics

    OpenAIRE

    Zubov, F. I.; Zhukov, A. E.; Shernyakov, Yu. M.; M. V. Maximov; Semenova, Elizaveta; Asryan, L. V.

    2015-01-01

    It is demonstrated that the use of asymmetric barrier layers in a waveguide of a diode laser suppress non-linearity of light-current characteristic and thus improve its power characteristics under high current injection. The results are presented for 850-nm AlGaAs/GaAs broad-area lasers with GaInP and AlInGaAs asymmetric barriers.

  7. A grating-coupled external cavity InAs/InP quantum dot laser with 85-nm tuning range

    Science.gov (United States)

    Wei, Heng; Jin, Peng; Luo, Shuai; Ji, Hai-Ming; Yang, Tao; Li, Xin-Kun; Wu, Jian; An, Qi; Wu, Yan-Hua; Chen, Hong-Mei; Wang, Fei-Fei; Wu, Ju; Wang, Zhan-Guo

    2013-09-01

    The optical performance of a grating-coupled external cavity laser based on InAs/InP quantum dots is investigated. Continuous tuning from 1391 nm to 1468 nm is realized at an injection current of 1900 mA. With the injection current increasing to 2300 mA, the tuning is blue shifted to some extent to the range from 1383 nm to 1461 nm. By combining the effect of the injection current with the grating tuning, the total tuning bandwidth of the external cavity quantum-dot laser can reach up to 85 nm. The dependence of the threshold current on the tuning wavelength is also presented.

  8. MoonLIGHT: A USA-Italy lunar laser ranging retroreflector array for the 21st century

    Science.gov (United States)

    Martini, M.; Dell'Agnello, S.; Currie, D.; Delle Monache, G.; Vittori, R.; Chandler, J. F.; Cantone, C.; Boni, A.; Berardi, S.; Patrizi, G.; Maiello, M.; Garattini, M.; Lops, C.; March, R.; Bellettini, G.; Tauraso, R.; Intaglietta, N.; Tibuzzi, M.; Murphy, T. W.; Bianco, G.; Ciocci, E.

    2012-12-01

    Since the 1970s Lunar Laser Ranging (LLR) to the Apollo Cube Corner Retroreflector (CCR) arrays (developed by the University of Maryland, UMD) have supplied significant tests of General Relativity: possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. LLR has also provided significant information on the composition and origin of the Moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests), in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100 mm diameter) unaffected by librations. In particular, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF) and created a new industry-standard test procedure (SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of CCRs in laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of retroreflector payloads under thermal conditions produced with a solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time payload movement to simulate satellite orientation on orbit with respect to solar illumination and laser interrogation beams. These capabilities provide: unique pre-launch performance validation of the space segment of LLR/SLR (Satellite Laser

  9. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    Science.gov (United States)

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  10. Extended femtosecond laser wavelength range to 330 nm in a high power LBO based optical parametric oscillator.

    Science.gov (United States)

    Fan, Jintao; Gu, Chenglin; Wang, Chingyue; Hu, Minglie

    2016-06-13

    We experimentally demonstrate a compact tunable, high average power femtosecond laser source in the ultraviolet (UV) regime. The laser source is based on intra-cavity frequency doubling of a temperature-tuned lithium tribotate (LBO) optical parametric oscillator (OPO), synchronously pumped at 520 nm by a frequency-doubled, Yb-fiber femtosecond laser amplifier system. By adjusting crystal temperature, the OPO can provide tunable visible to near-infrared (NIR) signal pulse, which have a wide spectral tuning range from 660 to 884 nm. Using a β-barium borate (BBO) crystal for intra-cavity frequency doubling, tunable femtosecond UV pulse are generated across 330~442 nm with up to 364 mW at 402 nm.

  11. Megahertz FDML Laser with up to 143nm Sweep Range for Ultrahigh Resolution OCT at 1050nm

    CERN Document Server

    Kolb, Jan Philip; Eibl, Mattias; Pfeiffer, Tom; Wieser, Wolfgang; Huber, Robert

    2016-01-01

    We present a new design of a Fourier Domain Mode Locked laser (FDML laser), which provides a new record in sweep range at ~1um center wavelength: At the fundamental sweep rate of 2x417 kHz we reach 143nm bandwidth and 120nm with 4x buffering at 1.67MHz sweep rate. The latter configuration of our system is characterized: The FWHM of the point spread function (PSF) of a mirror is 5.6um (in tissue). Human in vivo retinal imaging is performed with the MHz laser showing more details in vascular structures. Here we could measure an axial resolution of 6.0um by determining the FWHM of specular reflex in the image. Additionally, challenges related to such a high sweep bandwidth such as water absorption are investigated.

  12. Megahertz FDML laser with up to 143nm sweep range for ultrahigh resolution OCT at 1050nm

    Science.gov (United States)

    Kolb, Jan Philip; Klein, Thomas; Eibl, Matthias; Pfeiffer, Tom; Wieser, Wolfgang; Huber, Robert

    2016-03-01

    We present a new design of a Fourier Domain Mode Locked laser (FDML laser), which provides a new record in sweep range at ~1μm center wavelength: At the fundamental sweep rate of 2x417 kHz we reach 143nm bandwidth and 120nm with 4x buffering at 1.67MHz sweep rate. The latter configuration of our system is characterized: The FWHM of the point spread function (PSF) of a mirror is 5.6μm (in tissue). Human in vivo retinal imaging is performed with the MHz laser showing more details in vascular structures. Here we could measure an axial resolution of 6.0μm by determining the FWHM of specular reflex in the image. Additionally, challenges related to such a high sweep bandwidth such as water absorption are investigated.

  13. Investigation on the Ability of Antireflection Coating to Withstand the Destructive Effects of Laser Radiation in IR Range (10.6 Micrometers),

    Science.gov (United States)

    2014-09-26

    at the mid-IR, KCl and NaCl are commonly selected as substrates. But for the CO2 laser , a Ge substrate coated with a *i ZnS AR coating, is still widely...intensity of the laser increases, these microscopic damages interact with the laser , thus absorbing more energy from the light field, and the...FOREIGN TECHNOLOGY DIVISION INVESTIGATION ON THE ABILITY OF ANTIREFLECTION COATING TO WITHSTAND THE DESTRUCTIVE EFFECTS OF LASER RADIATION IN IR RANGE

  14. Optimized design of a TOF laser range finder based on time-correlated single-photon counting

    Science.gov (United States)

    Wang, Huanqin; Yang, Yixin; Huang, Zhe; Cao, YangYang; Gui, Huaqiao

    2014-11-01

    A time-of-flight (TOF) laser range finder based on time-correlated single photon counting (TCSPC) has been developed. By using a Geiger-mode avalanche photodiode (G-APD) with the ability of detecting single-photon events and Time-to-Digital Converter (TDC) with picosecond resolution, a good linearity with 4.5 cm range precision can be achieved in the range of 1-10 m. This paper highlights a significant advance in improving the key parameters of this system, including the range precision and measurement dynamic range. In our experiments, it was found that both of the precision and the measurement dynamic range were limited by the signal to noise rate (SNR) and the inherent jitter of system. The range precision can be improved by enhancing the SNR of system. However, when the SNR is high enough, the main factors affecting the range precision will turn into the inherent jitter, which makes the range precision can not be improved infinitely. Moreover, the inherent jitter generated by pulsed laser and the signal processing module has been measured, and its influence on the system performance has also been discussed. Taking all of these factors into account, some optimized designs have been proposed to improve range precision and dynamic range simultaneously. The final experiment results show that, after all of these optimization designs, the range precision of system is better than 1.2 cm and the measurement dynamic range is enlarged to 54 m when the sampling time is as short as 1 ms, which is sufficient for many applications of 3D object recognition, computer vision, reverse engineering and virtual reality.

  15. Theory, design, and performance of extended tuning range semiconductor lasers with sampled gratings

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraman, V.; Chuang, Zuon-Min; Coldren, L.A. (Univ. of California, Santa Barbara, CA (United States))

    1993-06-01

    The authors have recently demonstrated 57 nm of tuning in a monolithic semiconductor laser using conventional DBR technology with grating elements removed in a periodic fashion. This paper describes the theory and design of these sampled grating tunable lasers. They first calculate sampled grating reflectivity. They then present normalized design curves which quantify tradeoffs involved in a sampled grating DBR laser with two mismatched sampled grating mirrors. These results are applied to design example in the InP-InGaAsP system. The design example provides 70 nm tuning wile maintaining [gt]30 dB MSR, with fractional index change [Delta][mu]/[mu] [lt] 0.2% in the mirrors, and only 1 mm of total sampled grating length. Section 4 summarizes recent experimental results, and compares them to theory. They also analyze other device structures which make use of sampled gratings.

  16. African Otter Workshop

    Directory of Open Access Journals (Sweden)

    Jan Reed-Smith

    2016-04-01

    Full Text Available All concerned thought this was an excellent workshop with important progress made towards creating a viable beginning of an African Otter Network. There is a long road ahead but the 2015 African Otter Workshop is a start on developing range country partners, activists and researchers as well as collaborating on issue identification and resolution which will assist in preserving at least some refugia for Africa’s otters. A list of actions was agreed on, including the creation of an African Otter Network website and social media network, apublic Otter Awareness facebook page, encouraging online reporting of otter sightings, conducting otter awareness surveys, and emphasising the need for communication with the public, other members of the network and other professionals. information not shared or documented is information LOST. A Second African Otter Workshop should be held in 2017 elsewhere in Africa to encourage attendance from a wider range of countries.

  17. Reports of the AAAI 2010 Conference Workshops

    OpenAIRE

    2010-01-01

    The AAAI-10 Workshop program was held Sunday and Monday, July 11–12, 2010 at the Westin Peachtree Plaza in Atlanta, Georgia. The AAAI-10 workshop program included 13 workshops covering a wide range of topics in artificial intelligence. The titles of the workshops were AI and Fun, Bridging the Gap between Task and Motion Planning, Collaboratively-Built Knowledge Sources and Artificial Intelligence, Goal-Directed Autonomy, Intelligent Security, Interactive Decision Theory and Game Theory,...

  18. Comparison of simulated and experimental 3D laser images using a GmAPD array: application to long range detection

    Science.gov (United States)

    Coyac, Antoine; Riviere, Nicolas; Hespel, Laurent; Briottet, Xavier

    2016-05-01

    In this paper, we show the feasibility and the benefit to use a Geiger-mode Avalanche Photo-Diode (GmAPD) array for long range detection, up to several kilometers. A simulation of a Geiger detection sensor is described, which is a part of our end-to-end laser simulator, to generate simulated 3D laser images from synthetic scenes. Resulting 3D point clouds have been compared to experimental acquisitions, performed with our GmAPD 3D camera on similar scenarios. An operational case of long range detection is presented: a copper cable outstretched above the ground, 1 kilometer away the experimental system and with a horizontal line-of-sight (LOS). The detection of such a small object from long distance observation strongly suggests that GmAPD focal plane arrays could be easily used for real-time 3D mapping or surveillance applications from airborne platforms, with good spatial and temporal resolutions.

  19. Underwater Laser-illuminated Range-gated Imaging Scaled by 22.5 cm ns-1 with Serial Targets

    Institute of Scientific and Technical Information of China (English)

    HE Duo-Min

    2004-01-01

    We have developed a novel target set to scale our Underwater Laser-illuminated Range-gated Imaging(ULRI)video system in a 3 m-tank with turbid water(attenuation coefficient 1.0 m-1). As light speed in water is 22.5 cm ns-1, the target set consists of a series of 3-bar targets at 22.5 cm intervals along the laser illumination direction, with the targets separated vertically. As a result, a sequence of good gated images, in steps of 1 ns delay, is presented, which is a revelation of the' sliced-view' phenomenon for ns-level range-gating in such a limited water body. The Depth of Gating(DOG)and DOG-profile of the URLI system are measured for the first time, which can be used for evaluating gating-performance efficiently.

  20. Prospects in the orbital and rotational dynamics of the Moon with the advent of sub-centimeter lunar laser ranging

    CERN Document Server

    Kopeikin, S M; Pavlis, D; Brumberg, V A; Escapa, A; Getino, J; Gusev, A; Müller, J; Ni, W -T; Petrova, N

    2007-01-01

    Lunar Laser Ranging (LLR) measurements are crucial for advanced exploration of the laws of fundamental gravitational physics and geophysics. Current LLR technology allows us to measure distances to the Moon with a precision approaching 1 millimeter. As NASA pursues the vision of taking humans back to the Moon, new, more precise laser ranging applications will be demanded, including continuous tracking from more sites on Earth, placing new CCR arrays on the Moon, and possibly installing other devices such as transponders, etc. Successful achievement of this goal strongly demands further significant improvement of the theoretical model of the orbital and rotational dynamics of the Earth-Moon system. This model should inevitably be based on the theory of general relativity, fully incorporate the relevant geophysical processes, lunar librations, tides, and should rely upon the most recent standards and recommendations of the IAU for data analysis. This paper discusses methods and problems in developing such a mat...

  1. Rate of change of the Quincy-Monument Peak baseline from a translocation analysis of Lageos laser range data

    Science.gov (United States)

    Stolz, A.; Bender, P. L.; Vincent, M. A.; Eanes, R. J.; Watkins, M. M.

    1989-01-01

    Translocation studies of Lageos laser range data from Quincy and Monument Peak in California observed during 1984-1987 suggest that plate tectonic motion across the San Andreas fault system in the direction of the baseline between the two stations is uniform at a rate of -30(+ or - 3) mm/yr. Changes in the components of the baseline vector were inferred from repeat determinations using the solutions from successive 0.5-year intervals. The changes in the vertical and transverse components of the Quincy-Monument Peak baseline are -0.4(+ or - 5) mm/yr and +14(+ or -5) mm/yr, respectively. The vertical component determinations attest to the height stability of the laser ranging method. Lageos measurements made from Quincy and Monument Peak before 1984 are inaccurate enough to limit their usefulness for plate tectonic studies.

  2. Virtual Workshop

    DEFF Research Database (Denmark)

    Buus, Lillian; Bygholm, Ann

    In relation to the Tutor course in the Mediterranean Virtual University (MVU) project, a virtual workshop “Getting experiences with different synchronous communication media, collaboration, and group work” was held with all partner institutions in January 2006. More than 25 key-tutors within MVU...... participated from different institutions in the workshop. The result of the workshop was experiences with different communication tools and media. Facing the difficulties and possibilities in collaborateting virtually concerned around group work and development of a shared presentation. All based on getting...... experiences for the learning design of MVU courses. The workshop intented to give the participants the possibility to draw their own experiences with issues on computer supported collaboration, group work in a virtual environment, synchronous and asynchronous communication media, and different perspectives...

  3. Workshop Proceedings

    DEFF Research Database (Denmark)

    2012-01-01

    , the main focus there is on spoken languages in their written and spoken forms. This series of workshops, however, offers a forum for researchers focussing on sign languages. For the third time, the workshop had sign language corpora as its main topic. This time, the focus was on the interaction between......This collection of papers stems from the Fifth Workshop on the Representation and Processing of Sign Languages, held in May 2012 as a satellite to the Language Resources and Evaluation Conference in Istanbul. While there has been occasional attention for sign languages at the main LREC conference...... corpus and lexicon. More than half of the papers presented contribute to this topic. Once again, the papers at this workshop clearly identify the potentials of even closer cooperation between sign linguists and sign language engineers, and we think it is events like this that contribute a lot to a better...

  4. 4th International Workshop on Adaptive Optics for Industry and Medicine

    CERN Document Server

    Wittrock, Ulrich

    2005-01-01

    This book treats the development and application of adaptive optics for industry and medicine. The contributions describe recently developed components for adaptive-optics systems such as deformable mirrors, wavefront sensors, and mirror drivers as well as complete adaptive optical systems and their applications in industry and medicine. Applications range from laser-beam forming and adaptive aberration correction for high-power lasers to retinal imaging in ophthalmology. The contributions are based on presentations made at the 4th International Workshop on Adaptive Optics in Industry and Medicine which took place in Münster, Germany, in October 2003. This highly successful series of workshops on adaptive optics started in 1997 and continues with the 5th workshop in Beijing in 2005.

  5. Real-time displacement measurement with large range and high accuracy using sinusoidal phase modulating laser diode interferometer

    Institute of Scientific and Technical Information of China (English)

    Guotian He; Xiangzhao Wang; Aijun Zeng; Feng Tang; Bingjie Huang

    2007-01-01

    To resolve the conflict of large measurement range and high accuracy in the existing real-time displacement measurement laser diode (LD) interferometers, a novel real-time displacement measurement LD interferometry is proposed and its measurement principle is analyzed. By use of a new phase demodulation algorithm and a new phase compensation lgorithm of real-time phase unwrapping, the measurement accuracy is improved, and the measurement range is enlarged to a few wavelengths. In experiments, the peak-to-peak amplitude of the speaker vibration was 2361.7 nm, and the repeatability was 2.56 nm. The measurement time was less than 26μs.

  6. Active Laser and Raman Materials for 1.3-5 Micron Spectral Range

    Science.gov (United States)

    2006-03-01

    1989, pp. 270 (in Russian) 31. Handbook of lasers with selected data on optical technology, Ed. R.J. Pressley, Chemical Rubber Co, Cleveland, 1971 32...decreasing from surface to volume. Black surface has high electric conductivity . The results of electron microanalysis indicate that color is connected with...effective samples purification from tungsten without it destroying. The dipping of green yttria compact into crumb from yttria particles was

  7. Method of calculating retroreflector-array transfer functions. [laser range finders

    Science.gov (United States)

    Arnold, D. A.

    1978-01-01

    Techniques and equations used in calculating the transfer functions to relate the observed return laser pulses to the center of mass of the Lageos satellite retroflector array, and for most of the retroreflector-equipped satellites now in orbit are described. The methods derived include the effects of coherent interference, diffraction, polarization, and dihedral-angle offsets. Particular emphasis is given to deriving expressions for the diffraction pattern and active reflecting area of various cube-corner designs.

  8. Micro-joule pico-second range Yb3+-doped fibre laser for medical applications in acupuncture

    Science.gov (United States)

    Alvarez-Chavez, J. A.; Rivera-Manrique, S. I.; Jacques, S. L.

    2011-08-01

    The work described here is based on the optical design, simulation and on-going implementation of a pulsed (Q-switch) Yb3+-doped, 1-um diffraction-limited fibre laser with pico-second, 10 micro-Joule-range energy pulses for producing the right energy pulses which could be of benefit for patients who suffer chronic headache, photophobia, and even nausea which could is sometimes triggered by a series of factors. The specific therapeutic effect known as acupunctural analgesia is the main objective of this medium-term project. It is a simple design on which commercially available software was employed for laser cavity design. Monte Carlo technique for skin light-transport, thermal diffusion and the possible thermal de-naturalization optical study and prediction will also be included in the presentation. Full optical characterization will be included and a complete set of recent results on the laser-skin interaction and the so called moxi-bustion from the laser design will be extensively described.

  9. Lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Babichev, A. V.; Karachinsky, L. Ya.; Novikov, I. I. [Ioffe Institute (Russian Federation); Nikitina, E. V. [St. Petersburg Academic University (Russian Federation); Tchernycheva, M. [University Paris Sud XI, Institut d’Electronique Fondamentale (France); Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Pikhtin, N. A.; Tarasov, I. S. [Ioffe Institute (Russian Federation)

    2015-11-15

    The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm{sup 2} at 220 K with the characteristic temperature T{sub 0} = 123 K was demonstrated.

  10. Characterization of timing jitter spectra in free-running mode-locked lasers with 340 dB dynamic range over 10 decades of Fourier frequency

    CERN Document Server

    Jung, Kwangyun

    2014-01-01

    We demonstrate a method that enables accurate timing jitter spectral density characterization of free-running mode-locked laser oscillators over more than 10-decade of Fourier frequency from mHz to tens MHz range. The method is based on analyzing both the input voltage noise to the slave laser and the output voltage noise from the balanced optical cross- correlator (BOC), when two mode-locked lasers are synchronized in repetition rate by the BOC. As a demonstration experiment, timing jitter spectrum of a free-running mode-locked Er-fiber laser with a dynamic range of >340 dB is measured over Fourier frequency ranging from 1 mHz to 38.5 MHz (Nyquist frequency). The demonstrated method can resolve different noise mechanisms that cause specific jitter characteristics in free-running mode-locked laser oscillators for a vast range of time scales from 1000-s.

  11. Study of the Wavelength Dependence in Laser Ablation of Advanced Ceramics and Glass-Ceramic Materials in the Nanosecond Range.

    Science.gov (United States)

    Sola, Daniel; Peña, Jose I

    2013-11-19

    In this work, geometrical dimensions and ablation yields as a function of the machining method and reference position were studied when advanced ceramics and glass-ceramic materials were machined with pulsed lasers in the nanosecond range. Two laser systems, emitting at 1064 and 532 nm, were used. It was shown that the features obtained depend on whether the substrate is processed by means of pulse bursts or by grooves. In particular, when the samples were processed by grooves, machined depth, removed volume and ablation yields reached their maximum, placing the sample out of focus. It was shown that these characteristics do not depend on the processing conditions, the wavelength or the optical configuration, and that this is intrinsic behavior of the processing method. Furthermore, the existence of a close relation between material hardness and ablation yields was demonstrated.

  12. Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Gangyi, E-mail: gangyi.xu@mail.sitp.ac.cn [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Lianhe; Giles Davies, A.; Linfield, Edmund H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS9 2JT (United Kingdom); Isac, Nathalie; Halioua, Yacine; Colombelli, Raffaele, E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France)

    2014-03-03

    We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20–25 mW at 15 K and maximum operating temperatures of 80–85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonic heterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally single-mode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons.

  13. Selective excavation of human carious dentin using the nanosecond pulsed laser in 5.8-μm wavelength range

    Science.gov (United States)

    Kita, Tetsuya; Ishii, Katsunori; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

    Less-invasive treatment of caries has been needed in laser dentistry. Based on the absorption property of dentin substrates, 6 μm wavelength range shows specific absorptions and promising characteristics for the excavation. In our previous study, 5.8 μm wavelength range was found to be effective for selective excavation of carious dentin and restoration treatment using composite resin from the irradiation experiment with bovine sound and demineralized dentin. In this study, the availability of 5.8 μm wavelength range for selective excavation of human carious dentin was investigated for clinical application. A mid-infrared tunable nanosecond pulsed laser by difference-frequency generation was used for revealing the ablation property of human carious dentin. Irradiation experiments indicated that the wavelength of 5.85 μm and the average power density of 30 W/cm2 realized the selective excavation of human carious dentin, but ablation property was different with respect to each sample because of the different caries progression. In conclusion, 5.8 μm wavelength range was found to be effective for selective excavation of human carious dentin.

  14. Interpretation of laser/multi-sensor data for short range terrain modeling and hazard detection

    Science.gov (United States)

    Messing, B. S.

    1980-01-01

    A terrain modeling algorithm that would reconstruct the sensed ground images formed by the triangulation scheme, and classify as unsafe any terrain feature that would pose a hazard to a roving vehicle is described. This modeler greatly reduces quantization errors inherent in a laser/sensing system through the use of a thinning algorithm. Dual filters are employed to separate terrain steps from the general landscape, simplifying the analysis of terrain features. A crosspath analysis is utilized to detect and avoid obstacles that would adversely affect the roll of the vehicle. Computer simulations of the rover on various terrains examine the performance of the modeler.

  15. In-line process control for laser welding of titanium by high dynamic range ratio pyrometry and plasma spectroscopy

    Science.gov (United States)

    Lempe, B.; Taudt, C.; Baselt, T.; Rudek, F.; Maschke, R.; Basan, F.; Hartmann, P.

    2014-02-01

    The production of complex titanium components for various industries using laser welding processes has received growing attention in recent years. It is important to know whether the result of the cohesive joint meets the quality requirements of standardization and ultimately the customer requirements. Erroneous weld seams can have fatal consequences especially in the field of car manufacturing and medicine technology. To meet these requirements, a real-time process control system has been developed which determines the welding quality through a locally resolved temperature profile. By analyzing the resulting weld plasma received data is used to verify the stability of the laser welding process. The determination of the temperature profile is done by the detection of the emitted electromagnetic radiation from the material in a range of 500 nm to 1100 nm. As detectors, special high dynamic range CMOS cameras are used. As the emissivity of titanium depends on the wavelength, the surface and the angle of radiation, measuring the temperature is a problem. To solve these a special pyrometer setting with two cameras is used. That enables the compensation of these effects by calculating the difference between the respective pixels on simultaneously recorded images. Two spectral regions with the same emissivity are detected. Therefore the degree of emission and surface effects are compensated and canceled out of the calculation. Using the spatially resolved temperature distribution the weld geometry can be determined and the laser process can be controlled. The active readjustment of parameters such as laser power, feed rate and inert gas injection increases the quality of the welding process and decreases the number of defective goods.

  16. Network workshop

    DEFF Research Database (Denmark)

    Bruun, Jesper; Evans, Robert Harry

    2014-01-01

    research community. With this workshop, participants were offered a way into network science based on authentic educational research data. The workshop was constructed as an inquiry lesson with emphasis on user autonomy. Learning activities had participants choose to work with one of two cases of networks......This paper describes the background for, realisation of and author reflections on a network workshop held at ESERA2013. As a new research area in science education, networks offer a unique opportunity to visualise and find patterns and relationships in complicated social or academic network data....... These include student relations and interactions and epistemic and linguistic networks of words, concepts and actions. Network methodology has already found use in science education research. However, while networks hold the potential for new insights, they have not yet found wide use in the science education...

  17. Network workshop

    DEFF Research Database (Denmark)

    Bruun, Jesper; Evans, Robert Harry

    2014-01-01

    This paper describes the background for, realisation of and author reflections on a network workshop held at ESERA2013. As a new research area in science education, networks offer a unique opportunity to visualise and find patterns and relationships in complicated social or academic network data....... These include student relations and interactions and epistemic and linguistic networks of words, concepts and actions. Network methodology has already found use in science education research. However, while networks hold the potential for new insights, they have not yet found wide use in the science education...... research community. With this workshop, participants were offered a way into network science based on authentic educational research data. The workshop was constructed as an inquiry lesson with emphasis on user autonomy. Learning activities had participants choose to work with one of two cases of networks...

  18. Simulation of power – current characteristics of high-power semiconductor lasers emitting in the range 1.5 – 1.55 μm

    Energy Technology Data Exchange (ETDEWEB)

    Gorlachuk, P V; Ivanov, A V; Kurnosov, V D; Kurnosov, K V; Romantsevich, V I; Simakov, V A; Chernov, R V [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2014-02-28

    We report the simulation of power – current characteristics of high-power semiconductor lasers emitting in the range 1.5 – 1.55 μm. A technique is described which allows one to determine the thermal resistance and characteristic temperatures of a laser diode. The radiative and nonradiative carrier recombination rates are evaluated. Simulation results are shown to agree well with experimental data. (lasers)

  19. Double acousto-optic deflector system for increased scanning range of laser beams.

    Science.gov (United States)

    Kastelik, J-C; Dupont, S; Yushkov, K B; Molchanov, V Ya; Gazalet, J

    2017-09-01

    A new laser scanning system is presented based on two wide-band acousto-optic deflectors. The interaction medium is tellurium dioxide. Anisotropic interactions take place under two different tangential phase matching configurations in such a way that the acousto-optic bandwidths add up. We demonstrate the feasibility of such a cascade deflection system for the wavelength of λ=514nm. The total frequency bandwidth is Δf=100MHz, equally distributed between the two acousto-optic deflectors. The total angular scan at the output is Δθ=4.4° leading to 125 resolvable spots for a 1mm truncated Gaussian beam. Copyright © 2017. Published by Elsevier B.V.

  20. On the accuracy of lunar ephemerides using the data provided by the future Russian lunar laser ranging system

    Science.gov (United States)

    Vasilyev, M. V.; Yagudina, E. I.; Grishin, E. A.; Ivlev, O. A.; Grechukhin, I. A.

    2016-09-01

    The potential effect of the future Russian lunar laser ranging system (LLRS) on the accuracy of lunar ephemerides is discussed. In addition to the LLRS in Altai, several other observatories suitable for the LLRS installation are considered. The variation of accuracy of lunar ephemerides in the process of commissioning of new LLRS stations is estimated by mathematical modeling. It is demonstrated that the error in the determination of certain lunar ephemeris parameters may be reduced by up to 16% after seven years of operation of the Altai LLRS with a nearly optimal observational program.

  1. Development and analysis of a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system.

    Science.gov (United States)

    Oh, Min Seok; Kong, Hong Jin; Kim, Tae Hoon; Jo, Sung Eun; Kim, Byung Wook; Park, Dong Jo

    2011-05-01

    In this paper, a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system that uses a Geiger-mode avalanche photodiode (GAPD) of relatively short dead time (45 ns) is described. A passively Q-switched microchip laser is used as a laser source and a compact peripheral component interconnect system, which includes a time-to-digital converter (TDC), is set up for fast signal processing. The combination of a GAPD with short dead time and a TDC with a multistop function enables the system to operate in a single-hit or a multihit mode during the acquisition of time-of-flight data. The software for the three-dimensional visualization and an algorithm for the removal of noise are developed. For the photon-counting LADAR system, we establish a theoretical model of target-detection and false-alarm probabilities in both the single-hit and multihit modes with a Poisson statistic; this model provides the prediction of the performance of the system and a technique for the acquisition of a noise image with a GAPD. Both the noise image and the three-dimensional image of a scene acquired by the photon-counting LADAR system during the day are presented.

  2. Tuning range and output power optimization of an external-cavity GaN diode laser at 455  nm.

    Science.gov (United States)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-03-20

    In this paper we discuss how different feedback gratings affect the tuning range and the output power of external feedback diode laser systems. A tunable high-power narrow-spectrum external-cavity diode laser system around 455 nm is investigated. The laser system is based on a high-power GaN diode laser in a Littrow external-cavity. Both a holographic diffraction grating and a ruled diffraction grating are used as feedback elements in the external cavity. The output power, spectral bandwidth, and tunable range of the external cavity diode laser system are measured and compared with the two gratings at different injected currents. When the holographic grating is used, the laser system can be tuned over a range of 1.4 nm with an output power around 530 mW. When the ruled grating is used, the laser system can be tuned over a range of 6.0 nm with an output power around 80 mW. The results can be used as a guide for selecting gratings for external-cavity diode lasers for different requirements.

  3. Poetry Workshop.

    Science.gov (United States)

    Janeczko, Paul B.

    2000-01-01

    This workshop offers activities to teach students about poetry. After describing haiku as a brief snapshot rather than a story, it explains how to teach poetry using an attached reproducible and poster. The tear-out reproducible sheet teaches students how to write their own haiku, offering a sample one as a model. The poster presents three sample…

  4. Wireless Laser Range Finder System for Vertical Displacement Monitoring of Mega-Trusses during Construction

    Directory of Open Access Journals (Sweden)

    Hyo Seon Park

    2013-05-01

    Full Text Available As buildings become increasingly complex, construction monitoring using various sensors is urgently needed for both more systematic and accurate safety management and high-quality productivity in construction. In this study, a monitoring system that is composed of a laser displacement sensor (LDS and a wireless sensor node was proposed and applied to an irregular building under construction. The subject building consists of large cross-sectional members, such as mega-columns, mega-trusses, and edge truss, which secured the large spaces. The mega-trusses and edge truss that support this large space are of the cantilever type. The vertical displacement occurring at the free end of these members was directly measured using an LDS. To validate the accuracy and reliability of the deflection data measured from the LDS, a total station was also employed as a sensor for comparison with the LDS. In addition, the numerical simulation result was compared with the deflection obtained from the LDS and total station. Based on these investigations, the proposed wireless displacement monitoring system was able to improve the construction quality by monitoring the real-time behavior of the structure, and the applicability of the proposed system to buildings under construction for the evaluation of structural safety was confirmed.

  5. Exhaled air analysis using wideband wave number tuning range infrared laser photoacoustic spectroscopy

    Science.gov (United States)

    Kistenev, Yury V.; Borisov, Alexey V.; Kuzmin, Dmitry A.; Penkova, Olga V.; Kostyukova, Nadezhda Y.; Karapuzikov, Alexey A.

    2017-01-01

    The infrared laser photoacoustic spectroscopy (LPAS) and the pattern-recognition-based approach for noninvasive express diagnostics of pulmonary diseases on the basis of absorption spectra analysis of the patient's exhaled air are presented. The study involved lung cancer patients (N=9), patients with chronic obstructive pulmonary disease (N=12), and a control group of healthy, nonsmoking volunteers (N=11). The analysis of the measured absorption spectra was based at first on reduction of the dimension of the feature space using principal component analysis; thereafter, the dichotomous classification was carried out using the support vector machine. The gas chromatography-mass spectrometry method (GC-MS) was used as the reference. The estimated mean value of the sensitivity of exhaled air sample analysis by the LPAS in dichotomous classification was not less than 90% and specificity was not less than 69%; the analogous results of analysis by GC-MS were 68% and 60%, respectively. Also, the approach to differential diagnostics based on the set of SVM classifiers usage is presented.

  6. Ultra-broad range organic solid-state laser from a dye-doped holographic grating quasi-waveguide configuration

    Science.gov (United States)

    Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Mu, Quanquan; Cao, Zhaoliang; Lu, Xinghai; Ma, Ji; Xuan, Li

    2017-08-01

    This paper reports the ultra-broad 149.1 nm lasing emission from 573.2 to 722.3 nm using a simple [4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran] (DCM)-doped holographic polymer-dispersed liquid crystal (HPDLC) grating quasi-waveguide configuration by varying the grating period. The lasing emission beams show s-polarization property. The quasi-waveguide structure, which contained the cover glass, the DCM-doped HPDLC grating, the semiconducting polymer film poly[-methoxy-5-(2‧-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV), and the substrate were confirmed to decrease lasing threshold and broaden lasing wavelength. The operational lifetime of the device is 240 000 pulses, which corresponds to an overall laser duration of more than 6 h at a repetition rate of 10 Hz. In addition, the dual-wavelength lasing range from the 8th and 9th order is over 40 nm. The electrical tunability of the dual-wavelength lasing emission is over 1 nm. The experimental results facilitated the decreased lasing threshold and broadened lasing wavelength range of organic solid-state lasers.

  7. Documenting a Complex Modern Heritage Building Using Multi Image Close Range Photogrammetry and 3d Laser Scanned Point Clouds

    Science.gov (United States)

    Vianna Baptista, M. L.

    2013-07-01

    Integrating different technologies and expertises help fill gaps when optimizing documentation of complex buildings. Described below is the process used in the first part of a restoration project, the architectural survey of Theatre Guaira Cultural Centre in Curitiba, Brazil. To diminish time on fieldwork, the two-person-field-survey team had to juggle, during three days, the continuous artistic activities and performers' intense schedule. Both technologies (high definition laser scanning and close-range photogrammetry) were used to record all details in the least amount of time without disturbing the artists' rehearsals and performances. Laser Scanning was ideal to record the monumental stage structure with all of its existing platforms, light fixtures, scenery walls and curtains. Although scanned with high-definition, parts of the exterior façades were also recorded using Close Range Photogrammetry. Tiny cracks on the marble plaques and mosaic tiles, not visible in the point clouds, were then able to be precisely documented in order to create the exterior façades textures and damages mapping drawings. The combination of technologies and the expertise of service providers, knowing how and what to document, and what to deliver to the client, enabled maximum benefits to the following restoration project.

  8. Sampled grating tunable twin-guide laser diodes with wide tuning range (40 nm) and large output power (10 mW)

    Science.gov (United States)

    Todt, R.; Jacke, T.; Meyer, R.; Adler, J.; Laroy, R.; Morthier, G.; Amann, M.-C.

    2006-03-01

    The sampled grating tunable twin-guide (SG-TTG) laser diode is a DFB-like tunable laser that employs Vernier-effect tuning to achieve wide wavelength tuning. In contrast to most other monolithic widely tunable lasers (which are usually DBR-type lasers), a phase tuning section is not needed and, hence, the SG-TTG laser requires at least one tuning current less than comparable devices.The devices provide full wavelength coverage over a 40 nm-broad tuning range that is centered at 1.54 μm. Its tuning behavior is quasi-continuous with up to 8.2 nm broad continuous tuning regions. High side-mode suppression (SMSR 35 dB) as well as large output power (P 10 mW) are obtained over the whole wavelength range from 1520.5 to 1561.5 nm.

  9. Workshop on Molecular Evolution

    Science.gov (United States)

    Cummings, Michael P.

    2004-01-01

    Molecular evolution has become the nexus of many areas of biological research. It both brings together and enriches such areas as biochemistry, molecular biology, microbiology, population genetics, systematics, developmental biology, genomics, bioinformatics, in vitro evolution, and molecular ecology. The Workshop provides an important contribution to these fields in that it promotes interdisciplinary research and interaction, and thus provides a glue that sticks together disparate fields. Due to the wide range of fields addressed by the study of molecular evolution, it is difficult to offer a comprehensive course in a university setting. It is rare for a single institution to maintain expertise in all necessary areas. In contrast, the Workshop is uniquely able to provide necessary breadth and depth by utilizing a large number of faculty with appropriate expertise. Furthermore, the flexible nature of the Workshop allows for rapid adaptation to changes in the dynamic field of molecular evolution. For example, the 2003 Workshop included recently emergent research areas of molecular evolution of development and genomics.

  10. Ground Based Free Electron Laser Technology Integration Experiment, White Sands Missile Range, New Mexico

    Science.gov (United States)

    1987-01-01

    would preclude interference with televisions , radios and computer equipment operated in the area around WSMR. Warning signs will be posted at the...canadensis mexicana ); (2) black-tailed prairie dog (Cynonmys ludovicianus); (3) Colorado chipmunk (Eutamias quadrivittatus australis); (4) White Sands pupfish...by GBFEL TIE equipment, it could disturb local television and radio receivers. Since the GBFEL TIE will be located on White Sands Missile Range (WSMR

  11. Optimization of a Quantum Cascade Laser Operating in the Terahertz Frequency Range Using a Multiobjective Evolutionary Algorithm

    Science.gov (United States)

    2004-06-01

    laser fundamentals , semiconductors, quantum wells and finally ending with a discussion of generic QC lasers. With the a priori knowledge that...quantum cascade laser structure and operation. It begins, in Chapter 2, with a discussion of the atom, continus with laser fundamentals , semiconductors...Aerospace Engineering, Arizona State University. 102 15. Chow, W. W. and Koch, S. W. Semiconductor- Laser Fundamentals . New York: Springer-Verlag

  12. Note: Inter-satellite laser range-rate measurement by using digital phase locked loop.

    Science.gov (United States)

    Liang, Yu-Rong; Duan, Hui-Zong; Xiao, Xin-Long; Wei, Bing-Bing; Yeh, Hsien-Chi

    2015-01-01

    This note presents an improved high-resolution frequency measurement system dedicated for the inter-satellite range-rate monitoring that could be used in the future's gravity recovery mission. We set up a simplified common signal test instead of the three frequencies test. The experimental results show that the dominant noises are the sampling time jitter and the thermal drift of electronic components, which can be reduced by using the pilot-tone correction and passive thermal control. The improved noise level is about 10(-8) Hz/Hz(1/2)@0.01Hz, limited by the signal-to-noise ratio of the sampling circuit.

  13. Frequency tripled 1542 nm telecom laser diode stabilized to iodine hyperfine line in the 10-15 range

    CERN Document Server

    Philippe, Charles; Holleville, David; Lours, Michel; Minh-Pham, Tuam; Hrabina, Jan; Burck, Frederic Du; Wolf, Peter; Acef, Ouali

    2016-01-01

    We report on telecom laser frequency stabilization to narrow iodine hyperfine line in the green range of the optical domain, after a frequency tripling process using two nonlinear PPLN crystals. We have generated up to 300 mW optical power in the green (P3w), from 800 mW of infrared power (Pw). This result corresponds to an optical conversion efficiency eta= P3w/Pw ~ 36 %. To our knowledge, this is the best value ever demonstrated for a CW frequency tripling process. We have used a narrow linewidth iodine hyperfine line (component a1 of the 127I2 R 35 (44-0) line) to stabilize the IR laser yielding to frequency stability of 4.8x10-14 t-1/2 with a minimum of 6x10-15 reached after 50 s of integration time. The whole optical setup is very compact and mostly optically fibered. This approach opens the way for efficient and elegant architecture development for space applications as one of several potential uses.

  14. Development of Ultrashort Pulse Lasers and Their Applications to Ultrafast Spectroscopy in the Visible and NIR Ranges

    Science.gov (United States)

    Kobayashi, Takayoshi

    2016-07-01

    The use of ultrafast spectroscopy to gain detailed information about nonlinear processes can disclose the key physical mechanisms in the processes. The information promises to be a useful means to enhance the necessary nonlinearity for optical devices such as optical switches and optical manipulations of quantum states. Our group has generated stable visible to near-infrared laser pulses with a sub-5-fs duration using a non-collinear optical parametric amplifier. We also developed a detection system composed of 128 lock-in detectors, which provides an indispensable means of obtaining ultrafast nonlinear responses simultaneously in a very broad spectral range. The developed ultrashort pulse laser is used to study the electronic relaxation and molecular vibration dynamics in molecular systems through the interaction of the ultrashort pulses with the systems. Ultrashort pulses can stimulate Raman scattering in a molecular system. Observed time-resolved spectrum was analyzed to separate the electronic and vibrational contributions to the transient difference absorbance. The probe wavelength dependence of the vibrational amplitude is explained in terms of the coupling between the two pairing components among the pump field, Stokes field, anti-Stokes field, and coherent vibrational coordinates.

  15. Development of a Compton Camera for Online Range Monitoring of Laser-Accelerated Proton Beams via Prompt-Gamma Detection

    Directory of Open Access Journals (Sweden)

    Thirolf P.G.

    2014-03-01

    Full Text Available Presently large efforts are conducted in Munich towards the development of proton beams for bio-medical applications, generated via the technique of particle acceleration from high-power, short-pulse lasers. While so far mostly offline diagnostics tools are used in this context, we aim at developing a reliable and accurate online range monitoring technique, based on the position-sensitive detection of prompt γ rays emitted from nuclear reactions between the proton beam and the biological sample. For this purpose, we develop a Compton camera, designed to be able to track not only the Compton scattering of the primary photon, but also to detect the secondary Compton electron, thus reducing the Compton cone to an arc segment and by this increasing the source reconstruction efficiency. Design specifications and the status of the protype system are discussed.

  16. Design concepts of monolithic metamorphic vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Karachinsky, L. Ya.; Novikov, I. I.; Babichev, A. V.; Nevedomskiy, V. N. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Bugrov, V. E. [ITMO University (Russian Federation)

    2015-11-15

    Possible design concepts for long-wavelength vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range on GaAs substrates are suggested. It is shown that a metamorphic GaAs–InGaAs heterostructure with a thin buffer layer providing rapid transition from the lattice constant of GaAs to that of In{sub x}Ga{sub 1–x}As with an indium fraction of x < 0.3 can be formed by molecular-beam epitaxy. Analysis by transmission electron microscopy demonstrated the effective localization of mismatch dislocations in the thin buffer layer and full suppression of their penetration into the overlying InGaAs metamorphic layer.

  17. The 1.06 optical receiver. [avalanche photodiodes for laser range finders

    Science.gov (United States)

    Tomasetta, L. R.; Law, H. D.; Nakano, K.; Scholl, F. W.; Harris, J. S., Jr.

    1978-01-01

    High performance 1.06 micron m avalanche photodetectors (APDs), fabricated in the GaAlSb system, have high quantum efficiency (90 percent), high speed (risetime less than 60 ps) and low leakage currents (less than 50 na). The dark current represents more than an order of magnitude reduction compared to previously reported results. The high speed avalanche gain of these devices is between 20 and 50. The area uniformity is better than + or - 10 percent. GaAlAs APDs at 0.53 micron m have even faster speed, lower dark currents, and high speed gains of 100 to 200. Optical rangefinders based on measured APD performance parameters have far superior performance when compared to even ideal photomultiplier tubes in either a one color or two color rangefinder system. For a one color system, f factor of two lower time jitter can be achieved with identical transmitted power. The superiority of the APD based two color receiver is significant and exists in the entire range of desired time jitters (less than 100 ps) and received power levels.

  18. Multi-Range Conditional Random Field for Classifying Railway Electrification System Objects Using Mobile Laser Scanning Data

    Directory of Open Access Journals (Sweden)

    Jaewook Jung

    2016-12-01

    Full Text Available Railways have been used as one of the most crucial means of transportation in public mobility and economic development. For safe railway operation, the electrification system in the railway infrastructure, which supplies electric power to trains, is an essential facility for stable train operation. Due to its important role, the electrification system needs to be rigorously and regularly inspected and managed. This paper presents a supervised learning method to classify Mobile Laser Scanning (MLS data into ten target classes representing overhead wires, movable brackets and poles, which are key objects in the electrification system. In general, the layout of the railway electrification system shows strong spatial regularity relations among object classes. The proposed classifier is developed based on Conditional Random Field (CRF, which characterizes not only labeling homogeneity at short range, but also the layout compatibility between different object classes at long range in the probabilistic graphical model. This multi-range CRF model consists of a unary term and three pairwise contextual terms. In order to gain computational efficiency, MLS point clouds are converted into a set of line segments to which the labeling process is applied. Support Vector Machine (SVM is used as a local classifier considering only node features for producing the unary potentials of the CRF model. As the short-range pairwise contextual term, the Potts model is applied to enforce a local smoothness in the short-range graph; while long-range pairwise potentials are designed to enhance the spatial regularities of both horizontal and vertical layouts among railway objects. We formulate two long-range pairwise potentials as the log posterior probability obtained by the naive Bayes classifier. The directional layout compatibilities are characterized in probability look-up tables, which represent the co-occurrence rate of spatial relations in the horizontal and vertical

  19. Creating Fantastic PI Workshops

    Energy Technology Data Exchange (ETDEWEB)

    Biedermann, Laura B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Colbert, Rachel S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dagel, Amber Lynn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gupta, Vipin P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hibbs, Michael R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Perkins, David Nikolaus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); West, Roger Derek [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    The goal of this SAND report is to provide guidance for other groups hosting workshops and peerto-peer learning events at Sandia. Thus this SAND report provides detail about our team structure, how we brainstormed workshop topics and developed the workshop structure. A Workshop “Nuts and Bolts” section provides our timeline and check-list for workshop activities. The survey section provides examples of the questions we asked and how we adapted the workshop in response to the feedback.

  20. Laser-driven plasma wakefield electron acceleration and coherent femtosecond pulse generation in X-ray and gamma ranges

    Science.gov (United States)

    Trunov, V. I.; Lotov, K. V.; Gubin, K. V.; Pestryakov, E. V.; Bagayev, S. N.; Logachev, P. V.

    2017-01-01

    The laser wakefield acceleration (LWFA) of electrons in capillaries and gas jets followed by inverse Compton scattering of high intensity femtosecond laser pulses is discussed. The drive and scattered pulses will be produced by the two-channel multi-terawatt laser system developed in ILP SB RAS.

  1. Simulation of laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm

    Science.gov (United States)

    Nasouri, Babak; Murphy, Thomas E.; Berberoglu, Halil

    2014-07-01

    For understanding the mechanisms of low-level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. We present a three-dimensional, multilayer reduced-variance Monte Carlo simulation tool for studying light penetration and absorption in human skin. Local profiles of light penetration and volumetric absorption were calculated for uniform as well as Gaussian profile beams with different spreads over the spectral range from 1000 to 1900 nm. The results showed that lasers within this wavelength range could be used to effectively and safely deliver energy to specific skin layers as well as achieve large penetration depths for treating deep tissues, without causing skin damage. In addition, by changing the beam profile from uniform to Gaussian, the local volumetric dosage could increase as much as three times for otherwise similar lasers. We expect that this tool along with the results presented will aid researchers in selecting wavelength and laser power in LLLT.

  2. Simulation of laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm.

    Science.gov (United States)

    Nasouri, Babak; Murphy, Thomas E; Berberoglu, Halil

    2014-01-01

    For understanding the mechanisms of low-level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. We present a three-dimensional, multilayer reduced-variance Monte Carlo simulation tool for studying light penetration and absorption in human skin. Local profiles of light penetration and volumetric absorption were calculated for uniform as well as Gaussian profile beams with different spreads over the spectral range from 1000 to 1900 nm. The results showed that lasers within this wavelength range could be used to effectively and safely deliver energy to specific skin layers as well as achieve large penetration depths for treating deep tissues, without causing skin damage. In addition, by changing the beam profile from uniform to Gaussian, the local volumetric dosage could increase as much as three times for otherwise similar lasers. We expect that this tool along with the results presented will aid researchers in selecting wavelength and laser power in LLLT.

  3. Workshop experience

    Directory of Open Access Journals (Sweden)

    Georgina Holt

    2007-04-01

    Full Text Available The setting for the workshop was a heady mix of history, multiculturalism and picturesque riverscapes. Within the group there was, as in many food studies, a preponderance of female scientists (or ethnographers, but the group interacted on lively, non-gendered terms - focusing instead on an appreciation of locals food and enthusiasm for research shared by all, and points of theoretical variance within that.The food provided by our hosts was of the very highest eating and local food qualities...

  4. Compact fixed wavelength femtosecond oscillators as an add-on for tunable Ti:sapphire lasers extend the range of applications towards multimodal imaging and optogenetics

    Science.gov (United States)

    Hakulinen, T.; Klein, J.

    2016-03-01

    Two-photon (2P) microscopy based on tunable Ti:sapphire lasers has become a widespread tool for 3D imaging with sub-cellular resolution in living tissues. In recent years multi-photon microscopy with simpler fixed-wavelength femtosecond oscillators using Yb-doped tungstenates as gain material has raised increasing interest in life-sciences, because these lasers offer one order of magnitude more average power than Ti:sapphire lasers in the wavelength range around 1040 nm: Two-photon (2P) excitation of mainly red or yellow fluorescent dyes and proteins (e.g. YFP, mFruit series) simultaneously has been proven with a single IR laser wavelength. A new approach is to extend the usability of existing tunable Titanium sapphire lasers by adding a fixed IR wavelength with an Yb femtosecond oscillator. By that means a multitude of applications for multimodal imaging and optogenetics can be supported. Furthermore fs Yb-lasers are available with a repetition rate of typically 10 MHz and an average power of typically 5 W resulting in pulse energy of typically 500 nJ, which is comparably high for fs-oscillators. This makes them an ideal tool for two-photon spinning disk laser scanning microscopy and holographic patterning for simultaneous photoactivation of large cell populations. With this work we demonstrate that economical, small-footprint Yb fixed-wavelength lasers can present an interesting add-on to tunable lasers that are commonly used in multiphoton microscopy. The Yb fs-lasers hereby offer higher power for imaging of red fluorescent dyes and proteins, are ideally enhancing existing Ti:sapphire lasers with more power in the IR, and are supporting pulse energy and power hungry applications such as spinning disk microscopy and holographic patterning.

  5. Proceedings of the Annual Major Range and Test Facility Base (MRTFB) environmental Workshop (4th) Held in Alexandria, Virginia on 26-28 April 1994

    Science.gov (United States)

    1994-07-01

    Copy 0of 37 Copts$ | AD-A285 779 SIDA DOCUMENT D- 1537 I PROCEEDLNGS OF THE FOURTH ANNUAL MAJOR RANGE AND TEST FACILITY BASE (MRTFB...DEFENSE ANALYSES 񓜩 N. Beauregard Street, Alexandria, Virginia 22311-1772 SIDA Log No. HU 94-45640 * III i DEFINITIONS IDA publishes the follewing...woodpecker. The RCW is a good indicator of ecosystem health in VIH -36 I I the longleaf pine ecosystem. This survey identified Eglin as having the fourth

  6. Pulse width and energy influence on laser micromachining of metals in a range of 100 fs to 5 ps

    Energy Technology Data Exchange (ETDEWEB)

    Le Harzic, R. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany) and Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France)]. E-mail: leharzic@jenlab.de; Breitling, D. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Weikert, M. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Sommer, S. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Foehl, C. [Forschungsgesellschaft fuer Strahlwerkzeuge mbH (FGSW), Nobelstrasse 15, 70569 Stuttgart (Germany); Valette, S. [Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France); Donnet, C. [Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France); Audouard, E. [Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France); Dausinger, F. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany)

    2005-08-15

    Micromachining of steel, Cu and Al is studied. Ablation depths per pulse are deduced for laser pulse durations between 100 fs and 5 ps for fluences in the range of 150 mJ cm{sup -2} to 20 J cm{sup -2}. The evolution of ablation rates allows to evidence a low and a high fluence regime. Ablation thresholds and penetration depths are deduced as functions of pulse duration. While in the low fluence regime the penetration depth is close to the theoretical optical penetration depth, at higher fluences the effective heat penetration depth is 10-20 times bigger with also higher ablation thresholds. Even in the femtosecond range thermal ablation processes occur and reduce quality, accuracy and efficiency of micromachining. Additionally, the latter are influenced by strong beam distortions due to nonlinear interaction between the radiation and the atmospheric gas. In the case of steel and Cu, the pulse duration seems not to affect microprocessing, but it is demonstrated to play a role for Al for pulses between 1 and 5 ps.

  7. Ruby Emission in the Range 400-800 nm with Excitation by Continuous-Wave CO2 Laser Pulses

    Science.gov (United States)

    Marchenko, V. M.; Kiselev, V. V.

    2017-01-01

    Thermal emission spectra of ruby single crystals in the range 400-800 nm were studied experimentally as functions of the intensity at 10.6 μm of exciting pulses ( 0.5 s) from a continuous-wave electrical-discharge CO2 laser. Spectra at excitation intensity 1-20 kW/cm2 were superpositions of the thermal emission continuum of the sapphire crystal lattice in the range 600-800 nm and selective emission spectra of Cr3+ that were observed for the first time for ruby and consisted of R-lines at 695 nm; N-lines at 715 nm; 2 T 1, 4 T 2 → 4 A 2 transition bands at 672 and 643 nm; and 4 T 1, 2 T 2 → 4 A 2 transition bands at 530 and 490 nm that were not observed in the luminescence spectrum. Time dependences of the shapes of selective emission spectra, quenching and shifts of the R 1 line, and the temperature dependence of ruby luminescence spectra were investigated.

  8. Recent Workshops

    CERN Multimedia

    Wickens, F. J.

    Since the previous edition of ATLAS e-news, the NIKHEF Institute in Amsterdam has hosted not just one but two workshops related to ATLAS TDAQ activities. The first in October was dedicated to the Detector Control System (DCS). Just three institutes, CERN, NIKHEF and St Petersburg, provide the effort for the central DCS services, but each ATLAS sub-detector provides effort for their own controls. Some 30 people attended, including representatives for all of the ATLAS sub-detectors, representatives of the institutes working on the central services and the project leader of JCOP, which brings together common aspects of detector controls across the LHC experiments. During the three-day workshop the common components were discussed, and each sub-detector described their experiences and plans for their future systems. Whilst many of the components to be used are standard commercial components, a key custom item for ATLAS is the ELMB (Embedded Local Monitor Board). Prototypes for this have now been extensively test...

  9. Integration of a synthetic vision system with airborne laser range scanner-based terrain referenced navigation for precision approach guidance

    Science.gov (United States)

    Uijt de Haag, Maarten; Campbell, Jacob; van Graas, Frank

    2005-05-01

    Synthetic Vision Systems (SVS) provide pilots with a virtual visual depiction of the external environment. When using SVS for aircraft precision approach guidance systems accurate positioning relative to the runway with a high level of integrity is required. Precision approach guidance systems in use today require ground-based electronic navigation components with at least one installation at each airport, and in many cases multiple installations to service approaches to all qualifying runways. A terrain-referenced approach guidance system is envisioned to provide precision guidance to an aircraft without the use of ground-based electronic navigation components installed at the airport. This autonomy makes it a good candidate for integration with an SVS. At the Ohio University Avionics Engineering Center (AEC), work has been underway in the development of such a terrain referenced navigation system. When used in conjunction with an Inertial Measurement Unit (IMU) and a high accuracy/resolution terrain database, this terrain referenced navigation system can provide navigation and guidance information to the pilot on a SVS or conventional instruments. The terrain referenced navigation system, under development at AEC, operates on similar principles as other terrain navigation systems: a ground sensing sensor (in this case an airborne laser scanner) gathers range measurements to the terrain; this data is then matched in some fashion with an onboard terrain database to find the most likely position solution and used to update an inertial sensor-based navigator. AEC's system design differs from today's common terrain navigators in its use of a high resolution terrain database (~1 meter post spacing) in conjunction with an airborne laser scanner which is capable of providing tens of thousands independent terrain elevation measurements per second with centimeter-level accuracies. When combined with data from an inertial navigator the high resolution terrain database and

  10. Electronic sideband locking of 318.6nm UV laser to an ultrastable optical cavity with a wide continuously tunable range

    CERN Document Server

    Bai, Jiandong; He, Jun; Wang, Junmin

    2016-01-01

    We have demonstrated a frequency-stabilized tunable 318.6 nm ultraviolet (UV) laser system for the single-photon 6S1/2 - nP (n = 70 ~ 100) Rydberg excitation of cesium atoms. The 637.2 nm laser produced by single-pass sum frequency generation from two infrared fiber lasers is offset locked to a high-finesse ultra-low expansion (ULE) optical cavity placed in ultra-high vacuum using the electronic sideband locking technique. The generated 318.6 nm UV laser via cavity-enhanced second-harmonic generation can be continuously tuned over 4 GHz by indirectly changing modulation frequency on the electro-optic phase modulator while the whole laser system remains locked. We analyze the tuning range mainly depends on the modulator bandwidth and the tunable range of the seed laser. The locking scheme offers a method to compensate the frequency difference between the reference frequency and the goal frequency to a desired excited state, and has huge potential in precision spectroscopic experiments of cold atoms.

  11. Enlarging the linear response range of velocity with optimum imaging parameters and modified data processing in laser speckle imaging

    Science.gov (United States)

    Qiu, Jianjun; Li, Pengcheng; Ul'yanov, Sergey S.; Zeng, Shaoqun; Luo, Qingming

    2008-02-01

    Laser speckle imaging (LSI) technique is considered as a promising method of accessing cerebral blood flow (CBF) of animals for its high spatiotemporal resolution and simplicity. It is important in LSI that optimum imaging parameters and limited noises should be confirmed to promote the imaging precision. We investigated in this paper different factors which may affect the imaging results with a moving white plate model, and then proposed a method of enlarging the linear response range of velocity. Through experiment, we proposed in our LSI system the optimum imaging parameters, including the numerical aperture and magnification of microscopy, the integration time, the gain mode of CCD camera. The average intensity was found optimum at about 800 counts out of 4096 grey level, which permits the highest contrast in our experiment. To eliminate the influence of uneven illumination, a direct current weight of 27 counts was subtracted during data processing. The result indicated that the relationship between measured velocity and the real one remained linear with R2 equaling to 0.99 throughout the scale of 80 mm/s.

  12. Low-cost vehicle-mounted enhanced vision system comprised of a laser illuminator and range-gated camera

    Science.gov (United States)

    Pencikowski, Paul S.

    1996-05-01

    Considerable research has been done regarding the use of enhanced vision as a means to enable a vehicle operator to `see' through bad weather or obscuration such as smoke and dust. This research has generally emphasized Forward-looking infra-red (Flir) and millimeter-wave (radar) technologies. Flir is an acceptable approach if modest performance is all that is required. Millimeter wave radar has distinct advantages over Flir in certain cases, but generally requires operator training to interpret various display-screen presentations. The Northrop Grumman Corporation has begun a major sensor-development program to develop a prototype (eye-safe) laser-illuminator/range-gated camera system. The near-term goal is to field a system that would deliver a minimum of 3000 foot penetration of worst-case fog/obscurant. This image would appear on a display as a high resolution monochromatic image. This paper will explore the concept, the proposed automotive application, and the projected cost.

  13. Phantom-based comparison of the accuracy of point clouds extracted from stereo cameras and laser range scanner

    Science.gov (United States)

    Kumar, Ankur N.; Pheiffer, Thomas S.; Simpson, Amber L.; Thompson, Reid C.; Miga, Michael I.; Dawant, Benoit M.

    2013-03-01

    Using computational models, images acquired pre-operatively can be updated to account for intraoperative brain shift in image-guided surgical (IGS) systems. An optically tracked textured laser range scanner (tLRS) furnishes the 3D coordinates of cortical surface points (3D point clouds) over the surgical field of view and provides a correspondence between these and the pre-operative MR image. However, integration of the acquired tLRS data into a clinically acceptable system compatible throughout the clinical workflow of tumor resection has been challenging. This is because acquiring the tLRS data requires moving the scanner in and out of the surgical field, thus limiting the number of acquisitions. Large differences between acquisitions caused by tumor resection and tissue manipulation make it difficult to establish correspondence and estimate brain motion. An alternative to the tLRS is to use temporally dense feature-rich stereo surgical video data provided by the operating microscope. This allows for quick digitization of the cortical surface in 3D and can help continuously update the IGS system. In order to understand the tradeoffs between these approaches as input to an IGS system, we compare the accuracy of the 3D point clouds extracted from the stereo video system of the surgical microscope and the tLRS for phantom objects in this paper. We show that the stereovision system of the surgical microscope achieves accuracy in the 0.46-1.5mm range on our phantom objects and is a viable alternative to the tLRS for neurosurgical applications.

  14. 7TH International Workshop on Laser Physics (LPHYS󈨦) Berlin, Germany July 6-10, 1998 Program and Book of Abstracts: Volume 2.

    Science.gov (United States)

    1998-07-01

    Russia)"Laser refractometry of biological media" Tuesday, July 7 Chairs: S. Gonchukov (Russia) and D. Sliney (USA) A. Priezzhev (Moscow, Russia) 11.00...application to the evaluation of blood flow. Optics and Laser Technology, Vol.23, No.4, p.205, 1991. LASER REFRACTOMETRY OF BIOLOGICAL MEDIA S.A. Gonchukov...measuring (fast-action). Refractometry is a classical technique. The sensitivity of traditional measuring is usually 10-4-10-7. That’s no bad. But

  15. Craniofacial morphogenesis workshop report.

    Science.gov (United States)

    Solursh, M; Murray, J

    1994-05-01

    The following report highlights the discussions and interaction at the workshop on craniofacial morphogenesis, sponsored by The Human Frontier Science Program, held in April 1993 at the University of Iowa. A brief summary of selected sessions is included to exemplify the benefits of bringing together individuals from various disciplines and backgrounds in order to establish a unified theory of craniofacial morphogenesis. The synthesis of information and experience of a wide range of approaches made the 4-day period an invaluable experience for the participants from nine different countries.

  16. Computer Control of the Spectral Composition of the Powerful Laser System Irradiation with a Wide Range of Laser Transitions on Metal Vapors

    Directory of Open Access Journals (Sweden)

    Soldatov Anatoly

    2016-01-01

    Full Text Available The results of the experimental study cycle of the multiwave metal vapor laser system on the basis of the original configuration of the multimedia laser emitter. The spectral parameters of the setup have been controlled using a personal computer (PC. This allows carrying out their independent optimization according to excitation conditions, and, therefore, promptly allocating the output set of oscillating wavelengths and their relative distribution in power, which makes the system attractive for scientific and technological application.

  17. Range imaging pulsed laser sensor with two-dimensional scanning of transmitted beam and scanless receiver using high-aspect avalanche photodiode array for eye-safe wavelength

    Science.gov (United States)

    Tsuji, Hidenobu; Imaki, Masaharu; Kotake, Nobuki; Hirai, Akihito; Nakaji, Masaharu; Kameyama, Shumpei

    2017-03-01

    We demonstrate a range imaging pulsed laser sensor with two-dimensional scanning of a transmitted beam and a scanless receiver using a high-aspect avalanche photodiode (APD) array for the eye-safe wavelength. The system achieves a high frame rate and long-range imaging with a relatively simple sensor configuration. We developed a high-aspect APD array for the wavelength of 1.5 μm, a receiver integrated circuit, and a range and intensity detector. By combining these devices, we realized 160×120 pixels range imaging with a frame rate of 8 Hz at a distance of about 50 m.

  18. 2.3 µm range InP-based type-II quantum well Fabry-Perot lasers heterogeneously integrated on a silicon photonic integrated circuit.

    Science.gov (United States)

    Wang, Ruijun; Sprengel, Stephan; Boehm, Gerhard; Muneeb, Muhammad; Baets, Roel; Amann, Markus-Christian; Roelkens, Gunther

    2016-09-01

    Heterogeneously integrated InP-based type-II quantum well Fabry-Perot lasers on a silicon waveguide circuit emitting in the 2.3 µm wavelength range are demonstrated. The devices consist of a "W"-shaped InGaAs/GaAsSb multi-quantum-well gain section, III-V/silicon spot size converters and two silicon Bragg grating reflectors to form the laser cavity. In continuous-wave (CW) operation, we obtain a threshold current density of 2.7 kA/cm2 and output power of 1.3 mW at 5 °C for 2.35 μm lasers. The lasers emit over 3.7 mW of peak power with a threshold current density of 1.6 kA/cm2 in pulsed regime at room temperature. This demonstration of heterogeneously integrated lasers indicates that the material system and heterogeneous integration method are promising to realize fully integrated III-V/silicon photonics spectroscopic sensors in the 2 µm wavelength range.

  19. Pulse laser photolysis of aqueous ozone in the microsecond range studied by time-resolved far-ultraviolet absorption spectroscopy.

    Science.gov (United States)

    Goto, Takeyoshi; Morisawa, Yusuke; Higashi, Noboru; Ikehata, Akifumi; Ozaki, Yukihiro

    2013-05-01

    Chemical dynamics of an ozone (O3) pulse-photolytic reaction in aqueous solutions were studied with pump-probe transient far-ultraviolet (FUV) absorption spectroscopy. With a nanosecond pulse laser of 266 nm as pump light, transient spectra of O3 aqueous solutions (78-480 μM, pH 2.5-11.3) were acquired in the time range from -50 to 50 μs in the wavelength region from 190 to 225 nm. The measured transient spectra were linearly decomposed into the molar absorption coefficients and the concentration-time profiles of constituted chemical components with a multivariate curve resolution method. From the dependences of the time-averaged concentrations for 20 μs of the constituted chemicals on the initial concentration of O3, it was found that the transient spectra involve the decomposition of O3 and the formation of hydrogen peroxide (H2O2) and a third component that is assigned to hydroxyl radical (OH) or perhydroxyl radical (HO2). Furthermore, the pH dependence of the time-averaged concentration of the third components indicates that HO2 is more probable than OH as the third component. The time-averaged concentration ratio of each chemical component to the initial O3 concentration depends on the pH conditions from -0.95 to -0.60 for O3, 0.98 to 1.2 for H2O2, 0.002 to 0.29 for OH, and 0.012 to 0.069 for HO2.

  20. High precision gravity analysis and hydrological modeling from the Lunar Laser Ranging Observatory at Apache Point, New Mexico

    Science.gov (United States)

    Liang, Jiahao

    The NASA-supported Lunar Laser Ranging project (LLR) is located at Apache Point, New Mexico, which strives to precisely measure the orbital distance between the Earth and the Moon in an accuracy of a few millimeters. To archive this objective, LLR project requires precise data on local ground deformation, which is difficult to measure directly. However, the high precision gravity data is the reflection of vertical ground deformation of the Earth, therefore the gravity data is able to contribute to the LLR project. Gravity time series is affected by Earth tides, atmospheric pressure, polar motion, and the most critical effect, local hydrology. In order to isolate pure geodetic variation, these effects must be removed from the data. Thus, the goal of this research is to create models of above effects, especially local hydrology model, in order to isolate the vertical deformation signal. The Earth tides, atmospheric pressure and polar motion effects have been modeled and subtracted from gravity data (2009~2012). The local hydrological model has been created based on the in-situ data, which are rainfall, snowfall and temperature. The correlation coefficient and RMS misfit between the hydrological model and gravity residual (2010~2012) is 0.92 and 1.26 microGal. The instrument drift corrections in 2009 have been reanalyzed after comparing with some global hydrological models. The gravity residual from new corrections showed a correlation coefficient of 0.76 and RMS misfit of 1.25 microGal. The isolated deformation signal was obtained after we subtracted the hydrological effects, and the results can be used for further modeling.

  1. Multi-sensors multi-baseline mapping system for mobile robot using stereovision camera and laser-range device

    Directory of Open Access Journals (Sweden)

    Mohammed Faisal

    2016-06-01

    Full Text Available Countless applications today are using mobile robots, including autonomous navigation, security patrolling, housework, search-and-rescue operations, material handling, manufacturing, and automated transportation systems. Regardless of the application, a mobile robot must use a robust autonomous navigation system. Autonomous navigation remains one of the primary challenges in the mobile-robot industry; many control algorithms and techniques have been recently developed that aim to overcome this challenge. Among autonomous navigation methods, vision-based systems have been growing in recent years due to rapid gains in computational power and the reliability of visual sensors. The primary focus of research into vision-based navigation is to allow a mobile robot to navigate in an unstructured environment without collision. In recent years, several researchers have looked at methods for setting up autonomous mobile robots for navigational tasks. Among these methods, stereovision-based navigation is a promising approach for reliable and efficient navigation. In this article, we create and develop a novel mapping system for a robust autonomous navigation system. The main contribution of this article is the fuse of the multi-baseline stereovision (narrow and wide baselines and laser-range reading data to enhance the accuracy of the point cloud, to reduce the ambiguity of correspondence matching, and to extend the field of view of the proposed mapping system to 180°. Another contribution is the pruning the region of interest of the three-dimensional point clouds to reduce the computational burden involved in the stereo process. Therefore, we called the proposed system multi-sensors multi-baseline mapping system. The experimental results illustrate the robustness and accuracy of the proposed system.

  2. Proceedings of the workshop on polarized targets in storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Holt, R.J. (ed.)

    1984-08-01

    Polarization phenomena have played an increasingly important part in the study of nuclei and nucleons in recent years. Polarization studies have been hampered by the relatively few and rather fragile polarized targets which are presently available. The concept of polarized gas targets in storage rings opens a much wider range of possibilities than is available in the external target geometry. This novel method will represent a considerable advance in nuclear physics and will continue to receive much attention in plans for future facilities. An internal, polarized-target station is being planned for the cooler ring at the Indiana University Cyclotron Facility. Internal targets are compatible with recent designs of electron accelerators proposed by the Massachusetts Institute of Technology and the Southeastern Universities Research Association. The key to nuclear-science programs based on internal targets pivots on recent developments in polarized atomic beam methods, which include the more recent laser-driven polarized targets. The workshop drew together a unique group of physicists in the fields of high-energy, nuclear and atomic physics. The meeting was organized in a manner that stimulated discussion among the 58 participants and focused on developments in polarized target technology and the underlying atomic physics. An impressive array of future possibilities for polarized targets as well as current developments in polarized target technology were discussed at the workshop. Abstracts of individual items from the workshop were prepared separately for the data base.

  3. Single-shot high-dynamic range laser pulse contrast measurement using Fourth-Order-Crosscorrelation via Self-Referenced-Spectral-Interferometry (FOX-SRSI)

    CERN Document Server

    Palaniyappan, Sasi; Shimada, T; Shah, R C; Jung, D; Gautier, D C; Hegelich, B M; Fernandez, J C

    2012-01-01

    High-dynamic range isolation of the interference term and the non-interference term in the inverse Fourier-transformed spectral interferogram as required in Self-Referenced-Spectral-Interferometry (SRSI) for single-shot high-dynamic range laser pulse characterization is not always practically possible due to presence of the non-interference term over the entire temporal widow. Alternatively, we propose and demonstrate that one could directly obtain the single-shot Fourth-Order-Crosscorrelation (FOX) of the laser pulse to be characterized via SRSI (FOX-SRSI) from the interference term as the high-dynamic range laser contrast measurement, avoiding the need to isolate the interference and non-interference terms. As a consequence, the undesired contribution from the non-interference term limits the valid temporal window of the measurement. The single-shot FOX-SRSI result is consistent with the laser contrast measured independently using a multi-shot scanning third-order autocorrelator.

  4. Kinetics of gas phase OH radical reaction with thiophene in the 272-353 K temperature range: A laser induced fluorescence study

    Science.gov (United States)

    Kawade, Monali N.; Srinivas, D.; Upadhyaya, Hari P.

    2017-08-01

    Absolute rate coefficient for the gas phase reaction of OH radical with thiophene has been measured using the laser photolysis (LP) - laser induced fluorescence (LIF) technique. The kinetics measurements were done over the temperature range of 272-353 K and pressure range of 20-30 Torr. The bimolecular rate coefficients obtained were pressure independent in the above pressure range and showed Arrhenius type behaviour which were fitted to the expression k(T) = (4.53 ± 0.55) × 10-12 exp[(250 ± 30)/T] cm3 molecule-1 s-1. The reaction shows weak negative temperature dependence. These results were discussed with available literature and the tropospheric lifetime of thiophene was calculated.

  5. Absolute absorption and fluorescence measurements over a dynamic range of 10$^6$ with cavity-enhanced laser-induced fluorescence

    CERN Document Server

    Sanders, Scott E; Nahler, N Hendrik; Wrede, Eckart

    2013-01-01

    We describe a novel experimental setup that combines the advantages of both laser-induced fluorescence and cavity ring-down techniques. The simultaneous measurement of the ring-down and fluorescence signals from the same sample in a single laser beam delivers the calibration of the fluorescence measurement to gain absolute quantities: absorption cross section, sample density and fluorescence quantum yield. At the same time, the fluorescence measurement extends the dynamic range of a stand-alone cavity ring-down setup from typically three to at least six orders of magnitude. The methodology of this combined cavity-enhanced laser-induced fluorescence (CELIF) technique is developed and rigorously tested against the spectroscopy of 1,4-bis(phenylethynyl)benzene in a molecular beam and density measurements in a cell.

  6. Workshops as a Research Methodology

    Science.gov (United States)

    Ørngreen, Rikke; Levinsen, Karin

    2017-01-01

    This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice, and workshops as a research methodology. Focusing primarily on…

  7. IPHE Infrastructure Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-02-01

    This proceedings contains information from the IPHE Infrastructure Workshop, a two-day interactive workshop held on February 25-26, 2010, to explore the market implementation needs for hydrogen fueling station development.

  8. [Effects of low power laser radiation of blue, green and red ranges on free radical processes in rat blood in endotoxic shock].

    Science.gov (United States)

    Machneva, T V; Kosmacheva, N V; Vladimirov, Iu A; Osipov, A N

    2013-01-01

    This study was performed to investigate the effects of low power laser radiation in blue (441.2 nm), green (532.5 nm) and red (632.8 nm) wavelength ranges on free radical processes in experimental endotoxic shock in rats. The experimental model was produced by intraperitoneal injection of lipopolysacharide B (25 mg/kg) (LPS). The following parameters were assayed in the study: the chemiluminescent assay (to evaluate the free radical production by blood leukocytes), nitro blue tetrazolium assay (to monitor the superoxide dismutase activity of plasma) and cis-parinaric acid fluorescence (to estimate the intensity of lipid peroxidation in erythrocyte membranes). It was found that the low power laser radiation significantly influenced all investigated processes, in animals both treated and untreated without LPS injection. The most pronounced effects were observed in all groups of animals subjected to the low power laser radiation: at the dose of 0.75 J/cm2 green laser was most effective and at the dose of 1.5 J/cm2 green and red lasers provided maximal effects. The mechanisms of the observed phenomena are discussed.

  9. Validity of Dynamic Light Scattering Method to Analyze a Range of Gold and Copper Nanoparticle Sizes Attained by Solids Laser Ablation in Liquid

    Directory of Open Access Journals (Sweden)

    Yu. V. Golubenko

    2014-01-01

    Full Text Available Nanoparticles of metals possess a whole series of features, concerned with it’s sizes, this leads to appearing or unusual electromagnetic and optical properties, which are untypical for particulates.An extended method of receiving nanoparticles by means of laser radiation is pulse laser ablation of hard targets in liquid medium.Varying the parameters of laser radiation, such as wavelength of laser radiation, energy density, etc., we can operate the size and shape of the resultant particles.The greatest trend of application in medicine have the nanoparticles of iron, copper, silver, silicon, magnesium, gold and zinc.The subject matter in this work is nanoparticles of copper and gold, received by means of laser ablation of hard targets in liquid medium.The aim of exploration, represented in the article, is the estimation of application of the dynamic light scattering method for determination of the range of nanoparticles sizes in the colloidal solution.For studying of the laser ablation process was chosen the second harmonic of Nd:YAG laser with the wavelength of 532 nm. Special attention was spared for the description of the experiment technique of receiving of nanoparticles.As the liquid medium ethanol and distillation water were used.For exploration of the received colloidal system have been used the next methods: DLS, transmission electron microscopy (TEM and scanning electron microscopy (SEM.The results of measuring by DLS method showed that colloidal solution of the copper in the ethanol is the steady system. Copper nanoparticle’s size reaches 200 nm and is staying in the same size for some time.Received system from the gold’s nanoparticles is polydisperse, unsteady and has a big range of the nanoparticle’s sizes. This fact was confirmed by means of photos, got from the TEM FEI Tecnai G2F20 + GIF and SEM Helios NanoLab 660. The range of the gold nanoparticle’s sizes is from 5 to 60 nm. So, it has been proved that the DLS method is

  10. ICP-MS Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Carman, April J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Eiden, Gregory C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-11-01

    This is a short document that explains the materials that will be transmitted to LLNL and DNN HQ regarding the ICP-MS Workshop held at PNNL June 17-19th. The goal of the information is to pass on to LLNL information regarding the planning and preparations for the Workshop at PNNL in preparation of the SIMS workshop at LLNL.

  11. MOOC Design Workshop

    DEFF Research Database (Denmark)

    Nørgård, Rikke Toft; Mor, Yishay; Warburton, Steven

    2016-01-01

    For the last two years we have been running a series of successful MOOC design workshops. These workshops build on previous work in learning design and MOOC design patterns. The aim of these workshops is to aid practitioners in defining and conceptualising educational innovations (predominantly, ...

  12. Development of a Compton Camera for Online Range Monitoring of Laser-Accelerated Proton Beams via Prompt-Gamma Detection

    NARCIS (Netherlands)

    Thirolf, P.G.; Lang, C.; Aldawood, S.; Van der Kolff, H.G.; Maier, L.; Schaart, D.R.; Parodi, K.

    2014-01-01

    Presently large efforts are conducted in Munich towards the development of proton beams for bio-medical applications, generated via the technique of particle acceleration from high-power, short-pulse lasers. While so far mostly offline diagnostics tools are used in this context, we aim at developing

  13. A Study of the Radiant Ignition of a Range of Pyrotechnic Materials Using a CO2 Laser

    Science.gov (United States)

    1990-08-01

    tracers. Journal of Ballistics, 3 (4), 627. 10. Gebhard, T. (1988). Naval Ordnance Station, Indian Head, USA, private communicatin . 11. Culling, M.P...a C02 laser AUTHOR(S) CORPORATE AUTHOR DSTO Materials Research Laboratory L de Yong, B. Park and F. Valenta PO Box 50 Ascot Vale Victoria 3032 REPORT

  14. Measurement of angularly dependent spectra of betatron gamma-rays from a laser plasma accelerator with quadrant-sectored range filters

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Jong Ho, E-mail: jhjeon07@ibs.re.kr; Nakajima, Kazuhisa, E-mail: naka115@dia-net.ne.jp; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Jo, Sung Ha; Shin, Kang Woo [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Kim, Hyung Taek; Sung, Jae Hee; Lee, Seong Ku; Choi, Il Woo [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Advanced Photonics Research Institute, GIST, Gwangju 61005 (Korea, Republic of); Hojbota, Calin; Bae, Lee Jin; Jung, Jaehyung; Cho, Min Sang; Cho, Byoung Ick; Nam, Chang Hee [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Department of Physics and Photon Science, GIST, Gwangju 61005 (Korea, Republic of)

    2016-07-15

    Measurement of angularly dependent spectra of betatron gamma-rays radiated by GeV electron beams from laser wakefield accelerators (LWFAs) are presented. The angle-resolved spectrum of betatron radiation was deconvolved from the position dependent data measured for a single laser shot with a broadband gamma-ray spectrometer comprising four-quadrant sectored range filters and an unfolding algorithm, based on the Monte Carlo code GEANT4. The unfolded gamma-ray spectra in the photon energy range of 0.1–10 MeV revealed an approximately isotropic angular dependence of the peak photon energy and photon energy-integrated fluence. As expected by the analysis of betatron radiation from LWFAs, the results indicate that unpolarized gamma-rays are emitted by electrons undergoing betatron motion in isotropically distributed orbit planes.

  15. Investigation of the spectral characteristics of a pulsed F/sub 2/-center laser tunable in the range 1. 1--1. 26. mu

    Energy Technology Data Exchange (ETDEWEB)

    Gusev, Y.L.; Kirpichnikov, A.V.; Marennikov, S.I.

    1979-12-01

    A description is given of a simple resonator system in which single-frequency stimulated emission was achieved from a pulsed F-center laser. The average line width due to fluctuations of the lasing frequency was 0.01 cm/sup -1/ in the 1.1--1.26 ..mu.. spectral range. Investigations were made of the reasons for these fluctuations and numerical estimates were made of the different factors responsible for these fluctuations.

  16. Spectral emission properties of a laser-produced plasma light source in the sub-200 nm range for wafer inspection applications

    Science.gov (United States)

    Gambino, Nadia; Rollinger, Bob; Hudgins, Duane; Abhari, Reza S.

    2015-07-01

    The spectral emission properties of a droplet-based laser-produced plasma are investigated in the vacuum ultraviolet (VUV) range. Measurements are performed with a spectrograph that operates from 30 to 180 nm with a spectral resolution of 0.1 nm. The emission spectra are recorded for different metal droplet targets, namely tin, indium, and gallium. Measurements were performed at different pressure levels of the background gas. Several characteristic emission lines are observed. The spectra are also calibrated in intensity in terms of spectral radiance to allow absolute emission power estimations from the light source in the VUV region. The presented experimental results are relevant for alternative light sources that would be needed for future wafer inspection tools. In addition, the experimental results help to determine the out-of-band radiation emission of a tin-based extreme ultraviolet (EUV) source. By tuning the type of fuel, the laser energies, and the background gas, the laser-produced plasma light source shows good capabilities to be operated as a light source that covers a spectral emission range from the EUV to the sub-200 nm range.

  17. [Lasers].

    Science.gov (United States)

    Passeron, T

    2012-11-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  18. Lasers.

    Science.gov (United States)

    Passeron, T

    2012-12-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  19. A CW calibrated laser pulse energy meter for the range 1 pJ to 100 mJ

    Science.gov (United States)

    White, M. G.; Leonhardt, R.; Livigni, D.; Lehman, J. H.

    2014-06-01

    We describe the use of a silicon photodiode trap detector and digital storage oscilloscope as an absolute laser pulse energy meter, capable of repetition rates of 85 Hz and 5% uncertainty (k = 2). The maximum repetition rate is limited by the decay time of the output pulse of the detector. The technique relies on a straightforward oscilloscope-based integration of the voltage pulse generated by the photodiode trap detector. We highlight the versatility of the technique by comparing it at 1064 nm with our high and low-level calorimeter based pulse energy scales, to which our calibration services are traceable. The good agreement of the results, along with comprehensive uncertainty analysis, validates the approach we have taken. We have demonstrated a basis for establishing laser pulse energy measurement using continuous wave (CW) sources and standard detectors.

  20. Multi-Range Conditional Random Field for Classifying Railway Electrification System Objects Using Mobile Laser Scanning Data

    OpenAIRE

    Jaewook Jung; Leihan Chen; Gunho Sohn; Chao Luo; Jong-Un Won

    2016-01-01

    Railways have been used as one of the most crucial means of transportation in public mobility and economic development. For safe railway operation, the electrification system in the railway infrastructure, which supplies electric power to trains, is an essential facility for stable train operation. Due to its important role, the electrification system needs to be rigorously and regularly inspected and managed. This paper presents a supervised learning method to classify Mobile Laser Scanning ...

  1. mJ range all-fiber MOPA prototype with hollow-core fiber beam delivery designed for large scale laser facilities seeding (Conference Presentation)

    Science.gov (United States)

    Scol, Florent; Gouriou, Pierre; Perrin, Arnaud; Gleyze, Jean-François; Valentin, Constance; Bouwmans, Géraud; Hugonnot, Emmanuel

    2017-03-01

    The Laser megajoule (LMJ) is a French large scale laser facility dedicated to inertial fusion research. Its front-ends are based on fiber laser technology and generate highly controlled beams in the nanojoule range. Scaling the energy of those fiber seeders to the millijoule range is a way explored to upgrade LMJ's architecture. We report on a fully integrated narrow line-width all-fiber MOPA prototype at 1053 nm designed to meet stringent requirements of large-scale laser facilities seeding. We achieve 750 µJ temporally-shaped pulses of few nanoseconds at 1 kHz. Thanks to its original longitudinal geometry and its wide output core (26µm MFD), the Yb-doped tapered fiber used in the power amplifier stage ensures a single-mode operation and negligible spectro-temporal distortions. The transport of 30 kW peak power pulses (from tapered fiber) in a 17 m long large mode area (39µm) hollow-core (HC) fiber is presented and points out frequency modulation to amplitude modulation conversion management issues. A S² measurement of this fiber allows to attribute this conversion to a slightly multimode behavior (< 13dB of extinction between the fundamental mode and higher order modes). Other HC fibers exhibiting a really single-mode behavior (<20 dB) have been tested and the comparison will be presented in the conference. Finally, fiber spatial beam shaping from coherent Gaussian beam to coherent top-hat intensity profile beam in the mJ range with a specifically designed and fabricated fiber will also be presented.

  2. 2014 MICCAI Workshop

    CERN Document Server

    Nedjati-Gilani, Gemma; Rathi, Yogesh; Reisert, Marco; Schneider, Torben

    2014-01-01

    This book contains papers presented at the 2014 MICCAI Workshop on Computational Diffusion MRI, CDMRI’14. Detailing new computational methods applied to diffusion magnetic resonance imaging data, it offers readers a snapshot of the current state of the art and covers a wide range of topics from fundamental theoretical work on mathematical modeling to the development and evaluation of robust algorithms and applications in neuroscientific studies and clinical practice.   Inside, readers will find information on brain network analysis, mathematical modeling for clinical applications, tissue microstructure imaging, super-resolution methods, signal reconstruction, visualization, and more. Contributions include both careful mathematical derivations and a large number of rich full-color visualizations.   Computational techniques are key to the continued success and development of diffusion MRI and to its widespread transfer into the clinic. This volume will offer a valuable starting point for anyone interested i...

  3. Signal generator system of phase laser range finder%野外大长度量值传递稳定性与可靠性分析

    Institute of Scientific and Technical Information of China (English)

    郭赞峰; 庞尚益

    2011-01-01

    In order to get a better modulated signal sources in phase laser range finder, microcontroller unit controlling with DDS chip AD9851 to generate adjustable frequency and controllable phase signal source was adopted in the paper. DDS has the low noise and high frequency resolution. It is easy to program and so on. According to reality, different frequency by AD9851 programming could be gained. It can meet the different distance measurement. High noise frequency always comes along with the signal source. Elliptic filter which is close to ideal low filter was designed for the filter. The paper gave the specific design steps, and got the amplitude - frequency characteristic curve through simulation software Pspice8. 0. The simulation result chart extremely approached the idealized characteristic curves. It laid the good foundation on the laser modulation of phase laser range finder.%因瓦基线尺是国家野外大长度量值传递的法定标准器,本文通过对一组因瓦基线尺多年的检定资料、基线场的多次测量成果以及与维塞拉光波干涉仪测量成果的比较分析,论述我国野外大长度量值传递的稳定性与可靠性.

  4. Compact sources for the generation of high-peak power wavelength-stabilized laser pulses in the picoseconds and nanoseconds ranges

    Science.gov (United States)

    Wenzel, H.; Klehr, A.; Schwertfeger, S.; Liero, A.; Hoffmann, Th.; Brox, O.; Thomas, M.; Erbert, G.; Tränkle, G.

    2012-03-01

    Diode lasers are ideally suited for the generation of optical pulses in the nanoseconds and picoseconds ranges by gainswitching, Q-switching or mode-locking. We have developed diode-laser based light sources where the pulses are spectrally stabilized and nearly-diffraction limited as required by many applications. Diffraction limited emission is achieved by a several microns wide ridge waveguide (RW), so that only the fundamental lateral mode should lase. Spectral stabilization is realized with a Bragg grating integrated into the semiconductor chip, resulting in distributed feedback (DFB) or distributed Bragg reflector (DBR) lasers. We obtained a peak power of 3.8W for 4ns long pulses using a gain-switched DFB laser and a peak power of more than 4W for 65ps long pulses using a three-section DBR laser. Higher peak powers of several tens of Watts can be reached by an amplification of the pulses with semiconductor optical amplifiers, which can be either monolithically or hybrid integrated with the master oscillators. We developed compact modules with a footprint of 4×5cm2 combining master oscillator, tapered power amplifier, beam-shaping optical elements and high-frequency electronics. In order to diminish the generation of amplified spontaneous emission between the pulses, the amplifier is modulated with short-pulses of high amplitude, too. Beyond the amplifier, we obtained a peak power of more than 10W for 4ns long pulses, a peak power of about 35W for 80ps long pulses and a peak power of 70W for 10ps long pulses at emission wavelengths around 1064nm.

  5. 3D laser-written silica glass step-index high-contrast waveguides for the 3.5 μm mid-infrared range.

    Science.gov (United States)

    Martínez, Javier; Ródenas, Airán; Fernandez, Toney; Vázquez de Aldana, Javier R; Thomson, Robert R; Aguiló, Magdalena; Kar, Ajoy K; Solis, Javier; Díaz, Francesc

    2015-12-15

    We report on the direct laser fabrication of step-index waveguides in fused silica substrates for operation in the 3.5 μm mid-infrared wavelength range. We demonstrate core-cladding index contrasts of 0.7% at 3.39 μm and propagation losses of 1.3 (6.5) dB/cm at 3.39 (3.68) μm, close to the intrinsic losses of the glass. We also report on the existence of three different laser modified SiO₂ glass volumes, their different micro-Raman spectra, and their different temperature-dependent populations of color centers, tentatively clarifying the SiO₂ lattice changes that are related to the large index changes.

  6. (In,Ga,Al)P–GaP laser diodes grown on high-index GaAs surfaces emitting in the green, yellow and bright red spectral range

    Science.gov (United States)

    Ledentsov, N. N.; Shchukin, V. A.; Shernyakov, Yu M.; Kulagina, M. M.; Payusov, A. S.; Gordeev, N. Yu; Maximov, M. V.; Cherkashin, N. A.

    2017-02-01

    We report on low threshold current density (region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15° for (611)A substrates. The lasing at the wavelength of 569 nm is realized at 85 K. In an orange–red laser diode structure low threshold current density (190 A cm‑2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrated room temperature lasing at 628 nm at ∼2 kA cm‑2 and a total power above 3 W. The red laser diodes grown on (211)A substrates demonstrated a far field characteristic for vertically multimode lasing indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However, as expected from previous research, the temperature stability of the threshold current and the wavelength stability were significantly higher for (211)A-grown structures.

  7. Application of laser ranging and VLBI data to a study of plate tectonic driving forces. [finite element method

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The measurability of changes in plate driving or resistive forces associated with plate boundary earthquakes by laser rangefinding or VLBI is considered with emphasis on those aspects of plate forces that can be characterized by such measurements. Topics covered include: (1) analytic solutions for two dimensional stress diffusion in a plate following earthquake faulting on a finite fault; (2) two dimensional finite-element solutions for the global state of stress at the Earth's surface for possible plate driving forces; and (3) finite-element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting.

  8. The key role of Satellite Laser Ranging towards the integrated estimation of geometry, rotation and gravitational field of the Earth

    Science.gov (United States)

    Blossfeld, Mathis

    2015-01-01

    In 2007, the Global Geodetic Observing System (GGOS) was installed as a full component of the International Association of Geodesy (IAG). One primary goal of GGOS is the integration of geometric and gravimetric observation techniques to estimate consistent geodetic-geophysical parameters. Thereby, GGOS is based on the data and services of the IAG. Besides the combination of different geodetic techniques, also the common estimation of the station coordinates (TRF), Earth Orientation Parameters (EOP) and coefficients of the Earth's gravitational field (Stokes coefficients) is necessary in order to reach this goal. However, the combination of all geometric and gravimetric observation techniques is not yet fully realized. A major step towards the GGOS idea of parameter integration would be the understanding of the existing correlations between the above mentioned fundamental geodetic parameter groups. This topic is the major objective of this thesis. One possibility to study the interactions is the use of Satellite Laser Ranging (SLR) in an intertechnique combination with Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) or the intra-technique combination of multiple SLR-tracked satellites. SLR plays a key role in this thesis since it is the unique technique which is sensitive to all parameter groups and allows an integrated parameter estimation with very high accuracy. The present work is based on five first-author publications which are supplemented by four co-author publications. In this framework, for the first time an extensive discussion of a refined global Terrestrial Reference Frame (TRF) estimation procedure, the estimation of so-called Epoch Reference Frames (ERFs) is presented. In contrast to the conventional linear station motion model, the ERFs provide frequently estimated station coordinates and Earth Orientation Parameters (EOP) which allow to approximate not modeled non-linear station motions very accurately

  9. Proceedings of the 1976 ISABELLE workshops. [Thirty papers

    Energy Technology Data Exchange (ETDEWEB)

    None

    1976-01-01

    Seven ISABELLE-sponsored workshops were held from May through August, 1976, each workshop dealing with a specific subject concerning the design of storage rings. Technical matters ranging from the confinement of high intensity beams of protons and antiprotons to the design of experimental apparatus were addressed. The summary papers for the workshops as well as a number of contributed papers are presented. A separate abstract was prepared for ERDA Energy Research Abstracts (ERA) for each of the thirty papers.

  10. Meeting Report from the Genomic Standards Consortium (GSC) Workshop 9

    OpenAIRE

    Davidsen, Tanja; Madupu, Ramana; Sterk, Peter; Field, Dawn; Garrity, George; Gilbert, Jack; Glöckner, Frank Oliver; Hirschman, Lynette; Kolker, Eugene; Kottmann, Renzo; Kyrpides, Nikos; Meyer, Folker; Morrison, Norman; Schriml, Lynn; Tatusova, Tatiana

    2010-01-01

    This report summarizes the proceedings of the 9th workshop of the Genomic Standards Consortium (GSC), held at the J. Craig Venter Institute, Rockville, MD, USA. It was the first GSC workshop to have open registration and attracted over 90 participants. This workshop featured sessions that provided overviews of the full range of ongoing GSC projects. It included sessions on Standards in Genomic Sciences, the open access journal of the GSC, building standards for genome annotation, the M5 platf...

  11. Large-Mode-Area Double-Cladding Photonic Crystal Fiber Laser in the Watt Range at 980 nm

    Institute of Scientific and Technical Information of China (English)

    LI Ping-Xue; ZHANG Xue-Xia; LIU Zhi; CHI Jun-Jie

    2011-01-01

    @@ We report on a quasi-three-level large-mode-area double-clad Yb-doped fiber laser that adopts a linear cavity consisting of a 0°fiber end and a cavity mirror.Two kinds of Yb-doped photonic crystal fiber(PCF) with different inner-clads (170 μm and 200μm) and absorption coefficients (4.5 dB/m and 3 dB/m) are used as the gain media.By optimizing the structure and elements of the cavity, maximum output powers of 1.24 W and 1.1 W were yielded with optical conversion efficiencies of 7.8% and 6.8% when the fiber lengths were 25 cm and 40 cm with 170μm and 200 μm inner-claddings, respectively.

  12. PREFACE: Workshop Photograph and Program

    Science.gov (United States)

    2011-07-01

    : Bonnie Fleming (Yale U.))18:30 Supernovae neutrino detection (20') Ines Gil-Botella (CIEMAT)18:50 Neutrino cross-section in Liquid Argon in the GeV range (15') Flavio Cavanna (U. of L'Aquila)19:05 Analysis of the ArgoNeuT neutrino data (15') Carl Bromberg (Michigan State U.)19:20 Neutrino event reconstruction (15') Gary Barker (U. of Warwick) Tuesday 30 March 2010Ways to improve the Liquid Argon Charge Imaging technology I (Chair: Christos Touramanis (U. of Liverpool))09:00 Liquid Argon LEM TPC (30') Filippo Resnati (ETH Zurich)09:30 Micromegas for charge readout of double phase liquid Argon large TPCs (20') Alain Delbart (Saclay)09:50 Development of Thick-GEMs for GEM-TPC Tracker (20') Fuminori Sakuma (RIKEN)10:10 Optical readout of the ionization (20') Neil Spooner (U. of Sheffield)10:30 Scintillation light readout (20') Kostas Mavrokoridis (U. of Liverpool)10:50-11:10 Coffee break Ways to improve the Liquid Argon Charge Imaging technology II (Chair: Alberto Marchionni (ETH Zurich))11:10 Development of cold electronics (30') Veljko Radeka (BNL)11:40 Development of a frontend ASIC and DAQ system Dario Autiero (IPN Lyon)12:00 CAEN digitizers (20') Carlo Tintori (CAEN)12:20 Recent results from Liquid Argon R&D activity (20') Masashi Tanaka (KEK)12:40 Results from the materials test stand and status of LAPD (20') Brian Rebel (FNAL)13:00 Purging and purification: 6 m3 @CERN (20') Alessandro Curioni (ETH Zurich)13:20-14:30 Lunch break14:30-20:00 Trip to J-PARC to visit T2K Beam Facility and Near Detector20:00-22:00 Workshop dinner at Okura Frontier Hotel Tsukuba Wednesday 31 March 2010Ways to improve the Liquid Argon Charge Imaging technology III (Chair: Takasumi Maruyama (KEK))09:00 ArgonTube and UV laser ionization (25') Biagio Rossi (U. of Bern)09:25 Detector magnetization (15') Andreas Badertscher (ETH Zurich)09:40 HV system (25') Sosuke Horikawa (ETH Zurich) Localization studies (Chair: Takuya Hasegawa (KEK))10:05 Okinoshima site study (20') Masakazu Yoshioka (KEK)10

  13. Mobile robot self-localization in unstructured environments based on observation localizability estimation with low-cost laser range-finder and RGB-D sensors

    Directory of Open Access Journals (Sweden)

    Kun Qian

    2016-10-01

    Full Text Available When service robots work in human environments, unexpected and unknown moving people may deteriorate the convergence of robot localization or even cause failure localization if the environment is crowded. In this article, a multisensor observation localizability estimation method is proposed and implemented for supporting reliable robot localization in unstructured environments with low-cost sensors. The contribution of the approach is a strategy that combines noisy laser range-finder data and RGB-D data for estimating the dynamic localizability matrix in a probabilistic framework. By aligning two sensor frames, the unreliable part of the laser readings that hits unexpected moving people is fast extracted according to the output of a RGB-D-based human detector, so that the influence of unexpected moving people on laser observations can be explicitly factored out. The method is easy for implementation and is highly desirable to ensure robustness and real-time performance for long-term operation in populated environments. Comparative experiments are conducted and the results confirm the effectiveness and reliability of the proposed method in improving the localization accuracy and reliability in dynamic environments.

  14. High-Precision Surface Inspection: Uncertainty Evaluation within an Accuracy Range of 15μm with Triangulation-based Laser Line Scanners

    Science.gov (United States)

    Dupuis, Jan; Kuhlmann, Heiner

    2014-06-01

    Triangulation-based range sensors, e.g. laser line scanners, are used for high-precision geometrical acquisition of free-form surfaces, for reverse engineering tasks or quality management. In contrast to classical tactile measuring devices, these scanners generate a great amount of 3D-points in a short period of time and enable the inspection of soft materials. However, for accurate measurements, a number of aspects have to be considered to minimize measurement uncertainties. This study outlines possible sources of uncertainties during the measurement process regarding the scanner warm-up, the impact of laser power and exposure time as well as scanner’s reaction to areas of discontinuity, e.g. edges. All experiments were performed using a fixed scanner position to avoid effects resulting from imaging geometry. The results show a significant dependence of measurement accuracy on the correct adaption of exposure time as a function of surface reflectivity and laser power. Additionally, it is illustrated that surface structure as well as edges can cause significant systematic uncertainties.

  15. Assessment of the accuracy of global geodetic satellite laser ranging observations and estimated impact on ITRF scale: estimation of systematic errors in LAGEOS observations 1993-2014

    Science.gov (United States)

    Appleby, Graham; Rodríguez, José; Altamimi, Zuheir

    2016-12-01

    Satellite laser ranging (SLR) to the geodetic satellites LAGEOS and LAGEOS-2 uniquely determines the origin of the terrestrial reference frame and, jointly with very long baseline interferometry, its scale. Given such a fundamental role in satellite geodesy, it is crucial that any systematic errors in either technique are at an absolute minimum as efforts continue to realise the reference frame at millimetre levels of accuracy to meet the present and future science requirements. Here, we examine the intrinsic accuracy of SLR measurements made by tracking stations of the International Laser Ranging Service using normal point observations of the two LAGEOS satellites in the period 1993 to 2014. The approach we investigate in this paper is to compute weekly reference frame solutions solving for satellite initial state vectors, station coordinates and daily Earth orientation parameters, estimating along with these weekly average range errors for each and every one of the observing stations. Potential issues in any of the large number of SLR stations assumed to have been free of error in previous realisations of the ITRF may have been absorbed in the reference frame, primarily in station height. Likewise, systematic range errors estimated against a fixed frame that may itself suffer from accuracy issues will absorb network-wide problems into station-specific results. Our results suggest that in the past two decades, the scale of the ITRF derived from the SLR technique has been close to 0.7 ppb too small, due to systematic errors either or both in the range measurements and their treatment. We discuss these results in the context of preparations for ITRF2014 and additionally consider the impact of this work on the currently adopted value of the geocentric gravitational constant, GM.

  16. SPLASH'13 workshops summary

    DEFF Research Database (Denmark)

    Balzer, S.; Schultz, U. P.

    2013-01-01

    Following its long-standing tradition, SPLASH 2013 will host 19 high-quality workshops, allowing their participants to meet and discuss research questions with peers, to mature new and exciting ideas, and to build up communities and start new collaborations. SPLASH workshops complement the main t...

  17. Warehouse Sanitation Workshop Handbook.

    Science.gov (United States)

    Food and Drug Administration (DHHS/PHS), Washington, DC.

    This workshop handbook contains information and reference materials on proper food warehouse sanitation. The materials have been used at Food and Drug Administration (FDA) food warehouse sanitation workshops, and are selected by the FDA for use by food warehouse operators and for training warehouse sanitation employees. The handbook is divided…

  18. Risk Management Techniques and Practice Workshop Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, T; Zosel, M

    2008-12-02

    At the request of the Department of Energy (DOE) Office of Science (SC), Lawrence Livermore National Laboratory (LLNL) hosted a two-day Risk Management Techniques and Practice (RMTAP) workshop held September 18-19 at the Hotel Nikko in San Francisco. The purpose of the workshop, which was sponsored by the SC/Advanced Scientific Computing Research (ASCR) program and the National Nuclear Security Administration (NNSA)/Advanced Simulation and Computing (ASC) program, was to assess current and emerging techniques, practices, and lessons learned for effectively identifying, understanding, managing, and mitigating the risks associated with acquiring leading-edge computing systems at high-performance computing centers (HPCCs). Representatives from fifteen high-performance computing (HPC) organizations, four HPC vendor partners, and three government agencies attended the workshop. The overall workshop findings were: (1) Standard risk management techniques and tools are in the aggregate applicable to projects at HPCCs and are commonly employed by the HPC community; (2) HPC projects have characteristics that necessitate a tailoring of the standard risk management practices; (3) All HPCC acquisition projects can benefit by employing risk management, but the specific choice of risk management processes and tools is less important to the success of the project; (4) The special relationship between the HPCCs and HPC vendors must be reflected in the risk management strategy; (5) Best practices findings include developing a prioritized risk register with special attention to the top risks, establishing a practice of regular meetings and status updates with the platform partner, supporting regular and open reviews that engage the interests and expertise of a wide range of staff and stakeholders, and documenting and sharing the acquisition/build/deployment experience; and (6) Top risk categories include system scaling issues, request for proposal/contract and acceptance testing, and

  19. Workshops as a Research Methodology

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Levinsen, Karin Tweddell

    2017-01-01

    This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice, and worksh......This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice......, and workshops as a research methodology. Focusing primarily on the latter, this paper presents five studies on upper secondary and higher education teachers’ professional development and on teaching and learning through video conferencing. Through analysis and discussion of these studies’ findings, we argue...

  20. Magnetizing NIF Sub-Scale Capsules For Reaching Ignition Using Laser Energy in the 1 MJ Range

    Science.gov (United States)

    Zimmerman, G.; Ho, D.; Perkins, J.; Kagan, G.; Logan, G.; Salmonson, J.; Rhodes, M.; Blackfield, D.

    2016-10-01

    Fusion yield for ICF can be amplified by imposing a seed B-field around 50 T to confine alphas and to reduce electron heat conduction. Achieving 58 T in offline lab tests in sample hohlraum coils driven by a pulsed-power supply was demonstrated by Rhodes. Three topics are addressed. (1) The derivation of a 0D energy balance equation that including the effect of B-field. The ignition boundary obtained from this equation shows that a strong compressed B-field substantially reduces the minimum hotspot ρR required for ignition by about 50%. (2) The design of a near-term experimental demonstration of the effect of B-field on yield improvement based on our sub-scale gas-filled Symcap design for the NIF experiment (non-magnetized) that gave 1D yield and showed good symmetry. (3) The quest and design of magnetized sub-scale capsule with DT ice layer that gives robust ignition and requires only about 1 MJ of laser energy. Our baseline non-magnetized sub-scale design, with a seed field of 50T, gives a robust ignition with 1 MJ yield. This work performed under auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  1. Soft x-ray free-electron laser imaging by LiF crystal and film detectors over a wide range of fluences.

    Science.gov (United States)

    Pikuz, Tatiana A; Faenov, Anatoly Ya; Fukuda, Yuji; Kando, Masaki; Bolton, Paul; Mitrofanov, Alexander; Vinogradov, Alexander V; Nagasono, Mitsuru; Ohashi, Haruhiko; Yabashi, Makina; Tono, Kensuke; Senba, Yasunori; Togashi, Tadashi; Ishikawa, Tetsuya

    2013-01-20

    LiF crystal and film detectors were used to measure the far-field fluence profile of a self-amplified spontaneous-emission free-electron laser beam and diffraction imaging with high spatial resolution. In these measurements the photoluminescence (PL) response of LiF crystal and film was compared over a wide range of soft x-ray fluences. It was found that the soft x-ray fluence dependences of LiF crystal and film differ. At low fluence, the LiF crystal shows higher PL response compared to LiF film, while this comparison is the opposite at higher fluence. Accurate measurement of LiF crystal and film PL response is important for precise characterization of the spatial, spectral, and coherence features of x-ray beams across the full profile and in localized areas. For such measurements, crucial LiF detector attributes are high spatial resolution and high dynamic range.

  2. Nine orders of magnitude dynamic range: picomolar to millimolar concentration measurement in capillary electrophoresis with laser induced fluorescence detection employing cascaded avalanche photodiode photon counters.

    Science.gov (United States)

    Dada, Oluwatosin O; Essaka, David C; Hindsgaul, Ole; Palcic, Monica M; Prendergast, Jillian; Schnaar, Ronald L; Dovichi, Norman J

    2011-04-01

    The dynamic range of capillary electrophoresis analysis is ultimately limited by molecular shot noise at low concentrations and by concentration-induced band broadening at high concentrations. We report a system that approaches these fundamental limits. A laser-induced fluorescence detector is reported that employs a cascade of four fiber-optic beam splitters connected in series to generate a primary signal and four attenuated signals, each monitored by a single-photon counting avalanche photodiode. Appropriate scaling of the signals from the five photodiodes produces a linear optical calibration curve for 5-carboxyl-tetramethylrhodamine from the concentration detection limit of 1 pM to the upper limit of 1 mM. Mass detection limits are 120 yoctomoles (70 molecules) injected into the instrument. The very-wide dynamic range instrument was used to study the metabolic products of the fluorescently labeled glycosphingolipid tetramethylrhodamine labeled GM1 (GM1-TMR) produced by single cells isolated from the rat cerebellum.

  3. Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes.

    Science.gov (United States)

    Xu, Fan; Wang, Yuanqing; Li, Fenfang

    2016-03-01

    The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m.

  4. Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Fan; Wang, Yuanqing, E-mail: yqwang@nju.edu.cn; Li, Fenfang [School of Electronic Science and Engineering, Nanjing University, Nanjing 210046 (China)

    2016-03-15

    The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m.

  5. Effects of laser frequency chirp on modal noise in short-range radio over multimode fiber links

    DEFF Research Database (Denmark)

    Visani, Davide; Tartarini, Giovanni; Petersen, Martin Nordal;

    2010-01-01

    An important effect of the frequency chirp of the optical transmitter in radio over multimode fiber links is put into evidence experimentally and modeled theoretically for the first time, to our knowledge. This effect can have an important impact in short-range connections, where, although...

  6. 2011 Alkaline Membrane Fuel Cell Workshop Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Pivovar, B.

    2012-02-01

    A workshop addressing the current state-of-the-art in alkaline membrane fuel cells (AMFCs) was held May 8-9, 2011, at the Crystal Gateway Marriott in Arlington, Virginia. This workshop was the second of its kind, with the first being held December 11-13, 2006, in Phoenix, Arizona. The 2011 workshop and associated workshop report were created to assess the current state of AMFC technology (taking into account recent advances), investigate the performance potential of AMFC systems across all possible power ranges and applications, and identify the key research needs for commercial competitiveness in a variety of areas.

  7. WooW-II: Workshop on open workflows

    Directory of Open Access Journals (Sweden)

    Daniel Arribas-Bel

    2015-07-01

    Full Text Available This resource describes WooW-II, a two-day workshop on open workflows for quantitative social scientists. The workshop is broken down in five main parts, where each of them typically consists of an introductionary tutorial and a hands-on assignment. The specific tools discussed in this workshop are Markdown, Pandoc, Git, Github, R, and Rstudio, but the theoretical approach applies to a wider range of tools (e.g., LATEX and Python. By the end of the workshop, participants should be able to reproduce a paper of their own and make it available in an open form applying the concepts and tools introduced.

  8. 75 FR 25281 - Food Protection Workshop; Public Workshop

    Science.gov (United States)

    2010-05-07

    ... about food safety, food defense, the regulations authorized by the Public Health Security and..., visit http://www.uark.edu/ua/foodpro/Workshops/Food_Safety_Defense_Workshop.html or contact Steven C... visit http://www.uark.edu/ua/foodpro/Workshops/Food_Safety_Defense_Workshop.html to register online...

  9. Genetic Engineering Workshop Report, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J; Slezak, T

    2010-11-03

    the art. We also consciously chose to not dwell on matters of policy (for example, screening of commercial gene or oligo synthesis orders), as multiple other forums for policy discussion have taken place in recent years. We acknowledge that other workshops on topics relevant to genetic engineering should be held, some of which may need to take place at higher classification levels. The workshop moderators would like to acknowledge the enthusiastic participation of the attendees in the discussions. Special thanks are given to Sofi Ibrahim, for his extensive assistance on helping this report reach its final form. The genetic engineering workshop brought together a diverse mix of genetic engineering pioneers and experts, Federal agency representatives concerned with abuses of genetic engineering, TMT performers, bioinformatics experts, and representatives from industry involved with large-scale genetic engineering and synthetic biology. Several talks established the current range of genetic engineering capabilities and the relative difficulties of identifying and characterizing the results of their use. Extensive discussions established a number of recommendations to DTRA of how to direct future research investments so that any mis-use of genetic engineering techniques can be promptly identified and characterized.

  10. Evaluation of the Career Planning Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, L.W.

    1986-04-01

    People who apply to participate in this workshop appear to be genuinely interested in personal development. Participants reported that they were not very happy with several aspects of their jobs prior to the workshop. Predominant personality characteristics of the participants were shyness, communication anxiety, reserved style, cautiousness, moodiness, energetic, hard-working and analytical minded. Participants were favorably impressed with the workshop. One of the most potent ways that the workshop impacts participants is through improved self understanding and enhanced self-esteem. Many people did change jobs following the workshop. Of those who did not actually change jobs, almost half reported that they had modified their present job to achieve a better person-job fit. Participants did not report many changes in their routine behavior although they kept the supervisor more informed of their job activity. Current job satisfaction is good among the participants. Although the workshop is fairly expensive to provide, the long range benefits in terms of enhanced levels of performance far outweigh the costs.

  11. Accurate displacement-measuring interferometer with wide range using an I2 frequency-stabilized laser diode based on sinusoidal frequency modulation

    Science.gov (United States)

    Vu, Thanh-Tung; Higuchi, Masato; Aketagawa, Masato

    2016-10-01

    We propose the use of the sinusoidal frequency modulation technique to improve both the frequency stability of an external cavity laser diode (ECLD) and the measurement accuracy and range of a displacement-measuring interferometer. The frequency of the ECLD was modulated at 300 kHz by modulating the injection current, and it was locked to the b21 hyperfine component of the transition 6-3, P(33), 127I2 (633 nm) by the null method. A relative frequency stability of 6.5  ×  10-11 was achieved at 100 s sampling time. The stabilized ECLD was then utilized as a light source for an unbalanced Michelson interferometer. In the interferometer, the displacement and direction of the target mirror can be determined using a Lissajous diagram based on two consecutive and quadrant-phase harmonics of the interference signal. Generally, the measurement range of the interferometer by the proposed method is limited by the modulation index and the signal-to-noise ratio of the harmonics. To overcome this drawback, suitable consecutive harmonic pairs were selected for the specific measurement ranges to measure the displacement. The displacements determined in the specific ranges by the proposed method were compared with those observed by a commercial capacitive sensor. From the comparison, the proposed method has high precision to determine the displacement. The measurement range was also extended up to 10 m by selecting a suitable modulation index and suitable consecutive pairs of harmonics.

  12. High dynamic range measurement of spectral responsivity and linearity of a radiation thermometer using a super-continuum laser and LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y. S.; Lee, D. H.; Park, C. W.; Park, S. N. [Korea Research Institute of Standards and Science 209 Gajeong-Ro, Yuseong-Gu, Daejon 305-340 (Korea, Republic of)

    2013-09-11

    To realize the temperature scale above the freezing point of silver according to the definition of ITS-90, the dynamic range of the spectral responsivity is one of the most important factors which limit its uncertainty. When the residual spectral response at both side bands of a spectral band is not negligible, a significant uncertainty can be caused by a low dynamic range of the spectral responsivity measurement. In general, incandescent lamps are used to measure the spectral responsivity and the linearity. The dynamic range of the spectral responsivity measurement is often limited by a trade-off with the desired spectral resolution, which is less than 6 decades. Nonlinearity is another limiting fact of uncertainties of the temperature scale. Tungsten lamps have disadvantage in the nonlinearity measurements in terms of adjustability of radiance level and spectral selectivity. We report spectral responsivity measurements of which the measurable dynamic range is enhanced 50 times after replacing a QTH lamp with a super continuum laser. We also present a spectrally selected linearity measurement over a wide dynamic range using high-brightness light emitting diode arrays to observe a slight saturation of linearity.

  13. Proceedings of the workshop on ion source issues relevant to a pulsed spallation neutron source: Part 2 workshop presentations

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, L.; Leung, Ka-Ngo; Alonso, J. [eds.

    1994-10-01

    As part of the Lawrence Berkeley Laboratory Pulsed Spallation Source study, this Workshop was convened to address ion-source technology`s present status with respect to the next-generation Pulsed Spallation Source in the 1-5 MW range for the neutron scattering community. Considerations of Low Energy Beam Transport (LEBT) parameters and designs were included in the discussions throughout the Workshop. Ion-source requirements and actually-achieved performances were assessed, resulting in a determination of research and development requirements to bridge the gap. Part 1 of these Proceedings summarizes the Workshop; Part 2 contains viewgraphs of Workshop presentations.

  14. Proceedings of the TOUGH workshop

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, K. [ed.

    1990-09-01

    A workshop on applications and enhancements of the TOUGH/MULKOM family of multiphase fluid and heat flow simulation programs was held at Lawrence Berkeley Laboratory on September 13--14, 1990. The workshop was attended by 62 scientists from seven countries with interests in geothermal reservoir engineering, nuclear waste isolation, unsaturated zone hydrology, environmental problems, and laboratory and field experimentation. The meeting featured 21 technical presentations, extended abstracts of which are reproduced in the present volume in unedited form. Simulator applications included processes on a broad range of space scales, from centimeters to kilometers, with transient times from seconds to geologic time scales. A number of code enhancements were reported that increased execution speeds for large 3-D problems by factors of order 20, reduced memory requirements, and improved user-friendliness. The workshop closed with an open discussion session that focussed on future needs and means for interaction in the TOUGH user community. Input from participants was gathered by means of a questionnaire that is reproduced in the appendix. 171 refs., 91 figs., 16 tabs.

  15. PROCEEDING OF WORKSHOP ON PHOTO-INJECTOR FOR ENERGY RECOVERY LINAC.

    Energy Technology Data Exchange (ETDEWEB)

    WANG,X.J.

    2001-01-22

    Workshop on Photo-injectors for Energy Recovery Linac was held at National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory (BNL) on January 22 and 23, 2001. Fifty people attended the workshop; they came from three countries, representing universities, industries and national laboratories. This is the first workshop ever held on photo-injectors for CW operation, and for the first time, both DC and RF photo-injectors were discussed at the workshop. Workshop covered almost all major issues of photo-injectors, photocathode, laser system, vacuum, DC, 433 MHz/B-factory cavities based RF gun, 1.3 GHz RF gun and beam instrumentation. High quantum efficiency and long live time photocathode is the issue discussed during the workshop. Four working group leaders have done great jobs summarizing the workshop discussion, and identifying the major issues for future R and D.

  16. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    OpenAIRE

    2016-01-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflec...

  17. Seeded free-electron and inverse free-electron laser techniques for radiation amplification and electron microbunching in the terahertz range

    Directory of Open Access Journals (Sweden)

    C. Sung

    2006-12-01

    Full Text Available A comprehensive analysis is presented that describes amplification of a seed THz pulse in a single-pass free-electron laser (FEL driven by a photoinjector. The dynamics of the radiation pulse and the modulated electron beam are modeled using the time-dependent FEL code, GENESIS 1.3. A 10-ps (FWHM electron beam with a peak current of 50–100 A allows amplification of a ∼1  kW seed pulse in the frequency range 0.5–3 THz up to 10–100 MW power in a relatively compact 2-m long planar undulator. The electron beam driving the FEL is strongly modulated, with some inhomogeneity due to the slippage effect. It is shown that THz microbunching of the electron beam is homogeneous over the entire electron pulse when saturated FEL amplification is utilized at the very entrance of an undulator. This requires seeding of a 30-cm long undulator buncher with a 1–3 MW of pump power with radiation at the resonant frequency. A narrow-band seed pulse in the THz range needed for these experiments can be generated by frequency mixing of CO_{2} laser lines in a GaAs nonlinear crystal. Two schemes for producing MW power pulses in seeded FELs are considered in some detail for the beam parameters achievable at the Neptune Laboratory at UCLA: the first uses a waveguide to transport radiation in the 0.5–3 THz range through a 2-m long FEL amplifier and the second employs high-gain third harmonic generation using the FEL process at 3–9 THz.

  18. Nuclear Innovation Workshops Report

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, John Howard [Idaho National Lab. (INL), Idaho Falls, ID (United States); Allen, Todd Randall [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hildebrandt, Philip Clay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Baker, Suzanne Hobbs [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    The Nuclear Innovation Workshops were held at six locations across the United States on March 3-5, 2015. The data collected during these workshops has been analyzed and sorted to bring out consistent themes toward enhancing innovation in nuclear energy. These themes include development of a test bed and demonstration platform, improved regulatory processes, improved communications, and increased public-private partnerships. This report contains a discussion of the workshops and resulting themes. Actionable steps are suggested at the end of the report. This revision has a small amount of the data in Appendix C removed in order to avoid potential confusion.

  19. Ocean margins workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-12-31

    The Department of Energy (DOE) is announcing the refocusing of its marine research program to emphasize the study of ocean margins and their role in modulating, controlling, and driving Global Change phenomena. This is a proposal to conduct a workshop that will establish priorities and an implementation plan for a new research initiative by the Department of Energy on the ocean margins. The workshop will be attended by about 70 scientists who specialize in ocean margin research. The workshop will be held in the Norfolk, Virginia area in late June 1990.

  20. Design of Laser Range Finder Based on TDC_GP21%基于TDC_GP21的激光测距仪设计

    Institute of Scientific and Technical Information of China (English)

    纪晓轮; 蒋钱; 陈江伟; 张旭野

    2015-01-01

    为提高激光测距仪测距精度,采用ACAM公司的时间数字转换芯片TDC_GP21,设计了高精度的时间间隔测量模块,采用数据拟合算法对测距系统进行了标定,并用多项测距算术平均值的方法提高系统测距精度.测量结果表明系统电路简单、精度较高、成本更低、具有量产可行性.%In order to improve the ranging accuracy of laser range finder,we used the time digital converter chip TDC_GP21 of ACAM,designing a high precision time interval measurement module,using data fitting algorithm to calibrate the ranging system,and the average value of multiple ranging arithmetic is used to improve the accuracy of the system.The measurement results show that the circuit is simple,the precision is high,the cost is lower,and it has the feasibility of mass production.

  1. Thermomechanical response of 3D laser-deposited Ti–6Al–4V alloy over a wide range of strain rates and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peng-Hui [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Guo, Wei-Guo, E-mail: weiguo@nwpu.edu.cn [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Huang, Wei-Dong [The State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Su, Yu [Department of Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Lin, Xin [The State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Yuan, Kang-Bo [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China)

    2015-10-28

    To understand and evaluate the thermomechanical property of Ti–6Al–4V alloy prepared by the 3D laser deposition technology, an uniaxial compression test was performed on cylindrical samples using an electronic universal testing machine and enhanced Hopkinson technique, over the range of strain rate from 0.001/s to 5000/s, and at initial temperatures from the room temperature to 1173 K. The microstructure of the undeformed and deformed samples was examined through optical microscopy and the use of scanning electron microscope (SEM). The experimental results show the followings: (1) the anisotropy of the mechanical property of this alloy is not significant despite the visible stratification at the exterior surfaces; (2) initial defects, such as the initial voids and lack of fusion, are found in the microstructure and in the crack surfaces of the deformed samples, and they are considered as a major source of crack initiation and propagation; (3) adiabatic shear bands and shearing can easily develop at all selected temperatures for samples under compression; (4) the yield and ultimate strengths of this laser-deposited Ti–6Al–4V alloy are both lower than those of the Ti–6Al–4V alloy prepared by forging and electron beam melting, whereas both of its strengths are higher than those of a conventional grade Ti–6Al–4V alloy at high strain rate only. In addition to compression tests we also conducted tensile loading tests on the laser-deposited alloy at both low and high strain rates (0.1/s and 1000/s). There is significant tension/compression asymmetry in the mechanical response under high-strain-rate loading. It was found that the quasi-static tensile fracturing exhibits typical composite fracture characteristic with quasi-cleavages and dimples, while the high-strain-rate fracturing is characterized by ductile fracture behavior.

  2. The Optoelectronic Swept-Frequency Laser and Its Applications in Ranging, Three-Dimensional Imaging, and Coherent Beam Combining of Chirped-Seed Amplifiers

    Science.gov (United States)

    Vasilyev, Arseny

    This thesis explores the design, construction, and applications of the optoelectronic swept-frequency laser (SFL). The optoelectronic SFL is a feedback loop designed around a swept-frequency (chirped) semiconductor laser (SCL) to control its instantaneous optical frequency, such that the chirp characteristics are determined solely by a reference electronic oscillator. The resultant system generates precisely controlled optical frequency sweeps. In particular, we focus on linear chirps because of their numerous applications. We demonstrate optoelectronic SFLs based on vertical-cavity surface-emitting lasers (VCSELs) and distributed-feedback lasers (DFBs) at wavelengths of 1550 nm and 1060 nm. We develop an iterative bias current predistortion procedure that enables SFL operation at very high chirp rates, up to 1016 Hz/sec. We describe commercialization efforts and implementation of the predistortion algorithm in a stand-alone embedded environment, undertaken as part of our collaboration with Telaris, Inc. We demonstrate frequency-modulated continuous-wave (FMCW) ranging and three-dimensional (3-D) imaging using a 1550 nm optoelectronic SFL. We develop the technique of multiple source FMCW (MS-FMCW) reflectometry, in which the frequency sweeps of multiple SFLs are "stitched" together in order to increase the optical bandwidth, and hence improve the axial resolution, of an FMCW ranging measurement. We demonstrate computer-aided stitching of DFB and VCSEL sweeps at 1550 nm. We also develop and demonstrate hardware stitching, which enables MS-FMCW ranging without additional signal processing. The culmination of this work is the hardware stitching of four VCSELs at 1550 nm for a total optical bandwidth of 2 THz, and a free-space axial resolution of 75 microns. We describe our work on the tomographic imaging camera (TomICam), a 3-D imaging system based on FMCW ranging that features non-mechanical acquisition of transverse pixels. Our approach uses a combination of

  3. Raman laser based on a KGd(WO4)2 crystal: generation of stokes components in the 1.7-1.8 μm range*

    Science.gov (United States)

    Dashkevich, V. I.; Orlovich, V. A.

    2013-01-01

    We have studied the lasing characteristics of a Raman laser based on an Nd:KGW crystal, converting multimode emission of a pulsed Nd:KGW laser with working transition 4F3/2-4I13/2 (1351 nm) to Stokes components with wavelengths in the 1700-1800 nm range. We show that when the pump polarization coincides with the N m axis of the optical indicatrix of KGW ( E || N m ), the conversion efficiency for converting the pump radiation to the single second Stokes component with λ ~ 1786 nm reaches 17.5%, which results in an ~6.6 mJ Raman pulse. For E || N g , the conversion efficiency increases up to 22.5% and generation of an ~15 ns pulse occurs on four Stokes components with wavelengths 1704, 1744, 1770, and 1786 nm due to involvement of 86 cm-1, 767 cm-1, and 901 cm-1 vibrational modes in the stimulated Raman (SRS) process. We have determined the spectral distribution of the pulse energy. A total of 11 Stokes components are generated with participation of the indicated vibrational modes.

  4. Cybernetics and Workshop Design.

    Science.gov (United States)

    Eckstein, Daniel G.

    1979-01-01

    Cybernetic sessions allow for the investigation of several variables concurrently, resulting in a large volume of input compacted into a concise time frame. Three session questions are reproduced to illustrate the variety of ideas generated relative to workshop design. (Author)

  5. Complex Flow Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-05-01

    This report documents findings from a workshop on the impacts of complex wind flows in and out of wind turbine environments, the research needs, and the challenges of meteorological and engineering modeling at regional, wind plant, and wind turbine scales.

  6. Workshop: Teaching Primitive Arts.

    Science.gov (United States)

    Jordison, Jerry

    1999-01-01

    Discusses the concrete and spiritual aspects of teaching workshops on survival skills or primitive arts. Gives details on lostproofing, or ways to teach a child not to get lost in the outdoors; building a survival shelter; and wilderness cooking. (CDS)

  7. Printed Spacecraft Workshop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objectives of this workshop are to engage the engineering community at JPL that is knowledgeable in this technology in guiding/developing/critiquing  its...

  8. Waterfowl identification workshops

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Summary of waterfowl identification workshops conducted by Upper Souris National Wildlife Refuge and J. Clark Salyer National Wildlife Refuge. Objectives of the...

  9. Urban Waters Workshop

    Science.gov (United States)

    This page will house information leading up to the 2017 Urban Waters National Training Workshop. The agenda, hotel and other quarterly updates will be posted to this page including information about how to register.

  10. Transportation Management Workshop: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-01

    This report is a compilation of discussions presented at the Transportation Management Workshop held in Gaithersburg, Maryland. Topics include waste packaging, personnel training, robotics, transportation routing, certification, containers, and waste classification.

  11. Deep-space laser-ranging missions ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I for astrodynamics and astrometry

    CERN Document Server

    Ni, Wei-Tou

    2007-01-01

    Deep-space laser ranging will be ideal for testing relativistic gravity, and mapping the solar-system to an unprecedented accuracy. ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I are such missions. ASTROD I is a mission with a single spacecraft; it is the first step of ASTROD with 3 spacecraft. In this talk, after a brief review of ASTROD and ASTROD I, we concentrate of the precision of solar astrodynamics that can be achieved together with implications on astrometry and reference frame transformations. The precision planetary ephemeris derived from these missions together with second post-Newtonian test of relativistic gravity will serve as a foundation for future precise astrometry observations. Relativistic frameworks are discussed from these considerations.

  12. Laser-optical measurements of the velocities of the plasma jets formed from different gases in a kilojoule-range plasma focus facility

    Energy Technology Data Exchange (ETDEWEB)

    Polukhin, S. N., E-mail: snpol@lebedev.ru; Dzhamankulov, A. M.; Gurei, A. E.; Nikulin, V. Ya., E-mail: vnik@lebedev.ru; Peregudova, E. N.; Silin, P. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2016-12-15

    The velocities of the plasma jets formed from Ne, N{sub 2}, Ar, and Xe gases in plasma focus facilities were determined by means of laser-optical shadowgraphy of the shock waves generated at the jet leading edge. In spite of the almost tenfold ratio between the atomic weights of these gases, the outflow velocities of the plasma jets formed in experiments with these gases differ by less than twice, in the range of (0.7–1.1) × 10{sup 7} cm/s under similar discharge conditions. The energies of the jet ions were found to vary from 0.7 keV for nitrogen to 4 keV for xenon.

  13. AAAI-07 Workshop Reports

    OpenAIRE

    Anand, Sarabjot Singh; Bahls, Daniel; Burghart, Catherina R.; Burstein, Mark; Chen, Huajun; Collins, John; Dietterich, Tom; Doyle, Jon; Drummond, Chris; Elazmeh, William; Geib, Christopher; Goldsmith, Judy; Guesgen, Hans W.; Hendler, Jim; Jannach, Dietmar

    2007-01-01

    The AAAI-07 workshop program was held Sunday and Monday, July 22-23, in Vancouver, British Columbia, Canada. The program included the following thirteen workshops: (1) Acquiring Planning Knowledge via Demonstration; (2) Configuration; (3) Evaluating Architectures for Intelligence; (4) Evaluation Methods for Machine Learning; (5) Explanation-Aware Computing; (6) Human Implications of Human-Robot Interaction; (7) Intelligent Techniques for Web Personalization; (8) Plan, Activity, and Intent Rec...

  14. A Workshop that Works

    CERN Document Server

    Yunes, Nicolas

    2014-01-01

    The main goal of a scientific workshop is to bring together experts in a specific field or related fields to collaborate, to discuss, and to creatively make progress in a particular area. The organizational aspects of such a meeting play a critical role in achieving these goals. We here present suggestions from scientists to scientists that hopefully help in organizing a successful scientific workshop that maximizes collaboration and creativity.

  15. Workshop I: Gender Studies

    Science.gov (United States)

    Hennessey, Eden; Kurup, Anitha; Meza-Montes, Lilia; Shastri, Prajval; Ghose, Shohini

    2015-12-01

    Participants in the Gender Studies workshop of the 5th IUPAP International Conference on Women in Physics discussed the gender question in science practice from a policy perspective, informed by investigations from the social science disciplines. The workshop's three sessions—"Equity and Education: Examining Gender Stigma in Science," "A Comparative Study of Women Scientists and Engineers: Experiences in India and the US," and "Toward Gender Equity Through Policy: Characterizing the Social Impact of Interventions—are summarized, and the resulting recommendations presented.

  16. Industrial Fuel Flexibility Workshop

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-09-01

    On September 28, 2006, in Washington, DC, ITP and Booz Allen Hamilton conducted a fuel flexibility workshop with attendance from various stakeholder groups. Workshop participants included representatives from the petrochemical, refining, food and beverage, steel and metals, pulp and paper, cement and glass manufacturing industries; as well as representatives from industrial boiler manufacturers, technology providers, energy and waste service providers, the federal government and national laboratories, and developers and financiers.

  17. Strategic Workshops on Cancer Nanotechnology

    Science.gov (United States)

    Nagahara, Larry A.; Lee, Jerry S H.; Molnar, Linda K.; Panaro, Nicholas J.; Farrell, Dorothy; Ptak, Krzysztof; Alper, Joseph; Grodzinski, Piotr

    2010-01-01

    Nanotechnology offers the potential for new approaches to detecting, treating and preventing cancer. To determine the current status of the cancer nanotechnology field and the optimal path forward, the National Cancer Institute’s Alliance for Nanotechnology in Cancer held three strategic workshops, covering the areas of in-vitro diagnostics and prevention, therapy and post-treatment, and in-vivo diagnosis and imaging. At each of these meetings, a wide range of experts from academia, industry, the non-profit sector, and the Federal government discussed opportunities in the field of cancer nanotechnology and barriers to its implementation. PMID:20460532

  18. Midwest Transmission Workshop I Summary

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Bryan

    2001-05-01

    OAK-B135 The meeting was opened with a review of the purposes of the workshop: (1) Present and discuss key studies and assessments of transmission upgrades, additions and related issues for the upper Midwest, including work that addresses the full range of views on these topics; (2) Understand the various transmission issues in the upper Midwest and discuss options for addressing the issues; and (3) Identify the decision makers and entities that need to play an active role if transmission issues are to be resolved, and agree on next steps for engaging these individuals and organizations through education, outreach, and information dissemination.

  19. Nineteenth Workshop Athens, GA, USA

    CERN Document Server

    Lewis, S P; Schöttler, H B; Computer Simulation Studies in Condensed-Matter Physics XIX

    2008-01-01

    This volume represents a "status report" emanating from presentations made during the 19th Annual Workshop on Computer Simulations Studies in Condensed Matter Physics at the Center for Simulational Physics at the University of Georgia in February, 2006. It provides a broad overview of the most recent advances in the field, spanning the range from equilibrium and non-equilibrium behavior in statistical physics to biological and soft condensed matter systems. Results on nanomagents and materials are included as are several descriptions of advances in methodology.

  20. Detection System of Ranging Precision for Laser Rangefinder%大量程激光测距仪精度检测系统

    Institute of Scientific and Technical Information of China (English)

    董洪舟; 杨若夫; 敖明武; 李绍荣; 严高师

    2013-01-01

    The ranging precision is an important indicator to measure the performance of laser rangefinder. A detection system of ranging precision for 1 064 nm, 1 540 nm, and 1 570 nm wavelength rangefinder was introduced. The system consists of distance simulator and laser radiation simulator. Radiation simulator can generate an echo pulse with width among 5∼250 ns and the maximum peak power 0.1 W. FPGA-based distance simulator can realize distance simulation during 50 m∼990 km. The closed-loop detection method between radiation simulator and distance simulator is proposed and realized. According to the method, the fixed error of detection system is measured and eliminated. The detection results show that the distance simulation error is less than 1 meter in full simulation scale.%  激光测距仪的测距精度是衡量其性能的重要指标.本文设计了测距精度检测系统,可实现1064 nm、1540 nm、1570 nm三个波长的测距仪精度检测.该系统由激光距离模拟器和激光辐射模拟器组成,辐射模拟器可产生脉宽5∼250 ns、最大峰值功率0.1 W的回波脉冲;基于FPGA的距离模拟器可以实现50 m∼990 km的大量程距离模拟.本文提出并实现辐射模拟器和距离模拟器的闭环检测,以此测量消除系统固定误差.经过检测该系统全量程内距离模拟误差都小于1 m.

  1. Signal generator system of phase laser range finder%相位法激光测距信号源系统研究

    Institute of Scientific and Technical Information of China (English)

    姜明富; 曾一凡; 杨艳

    2011-01-01

    In order to get a better modulated signal sources in phase laser range finder, microcontroller unit controlling with DDS chip AD9851 to generate adjustable frequency and controllable phase signal source was adopted in the paper. DDS has the low noise and high frequency resolution. It is easy to program and so on. According to reality, different frequency by AD9851 programming couldbe gained. It can meet the different distance measurement. High noise frequency always comes along with the signal source. Elliptic filter which is close to ideal low filter was designed for the filter. The paper gave the specific design steps, and got the amplitude - frequency characteristic curve through simulation software Pspice8. 0. The simulation result chart extremely approached the idealized characteristic curves. It laid the good foundation on the laser modulation of phase laser range finder.%为了使相位式激光测距获得更好的调制信号源,采用了基于单片机控制DDA芯片AD9851产生频率可调,相位可控的信号源,由于DDS具有噪声低,频率分辨率高,易于编程等优点,根据实际需要,通过给AD9851编程获得不同的频率,满足不同距离的测量.由于获得的信号源中存在着高频杂散信号,设计了最接近理想特性的椭圆低通滤波器,并给出具体的设计步骤,通过Pspice8.0仿真软件仿真出幅频特性曲线,仿真的结果图非常逼近理想特性,为相位法激光测距中调制部分需要高纯度信号源提供前提条件.

  2. Extended dynamic range of Doppler OCT by application of a new method to high density B-scans using a MHz FDML swept laser source (Conference Presentation)

    Science.gov (United States)

    Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

    2017-02-01

    The limited dynamic range of optical coherence tomography (OCT) Doppler velocity measurements makes it difficult to conduct experiments on samples requiring a large dynamic range without phase wrapping at high velocities or loss of sensitivity at slow velocities. Hemodynamics and wall motion undergo significant increases in velocity as the embryonic heart develops. Experimental studies indicate that altered hemodynamics in early-stage embryonic hearts can lead to congenital heart diseases (CHDs), motivating close monitoring of blood flow over several stages of development. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate (100 Hz). The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of millimeters per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where the presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow for calculating shear stress as well as estimating the cardiac output. In conclusion, high density B-scans acquired by our high-speed OCT system enable image enhancement and direct measurement of biological parameters in cohort studies.

  3. Laser-induced incandescence : recent trends and current questions

    NARCIS (Netherlands)

    Schulz, C.; Kock, B.F.; Hofmann, M.; Michelsen, H.; Will, S.; Bougie, B.; Suntz, R.; Smallwood, G.

    2006-01-01

    This paper provides an overview of a workshop focused on fundamental experimental and theoretical aspects of soot measurements by laser-induced incandescence (LII). This workshop was held in Duisburg, Germany in September 2005. The goal of the workshop was to review the current understanding of the

  4. Laser-induced incandescence : recent trends and current questions

    NARCIS (Netherlands)

    Schulz, C.; Kock, B.F.; Hofmann, M.; Michelsen, H.; Will, S.; Bougie, B.; Suntz, R.; Smallwood, G.

    2006-01-01

    This paper provides an overview of a workshop focused on fundamental experimental and theoretical aspects of soot measurements by laser-induced incandescence (LII). This workshop was held in Duisburg, Germany in September 2005. The goal of the workshop was to review the current understanding of the

  5. 3rd Annual Workshop on Inverse Problem

    CERN Document Server

    2015-01-01

    This proceeding volume is based on papers presented on the Third Annual Workshop on Inverse Problems which was organized by the Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, and took place in May 2013 in Stockholm. The purpose of this workshop was to present new analytical developments and numerical techniques for solution of inverse problems for a wide range of applications in acoustics, electromagnetics, optical fibers, medical imaging, geophysics, etc. The contributions in this volume reflect these themes and will be beneficial to researchers who are working in the area of applied inverse problems.

  6. Automated assessment of blood flow in developing embryonic hearts by extending dynamic range of Doppler OCT using a MHz FDML swept laser source (Conference Presentation)

    Science.gov (United States)

    Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

    2017-02-01

    Altered hemodynamics in developing embryonic hearts lead to congenital heart diseases, motivating close monitoring of blood flow over several stages of development. Doppler OCT can assess blood flow in tubular hearts, but the maximum velocity increases drastically during the period of cardiac cushion (valve precursors) formation. Therefore, the limited dynamic range of Doppler OCT velocity measurement makes it difficult to conduct longitudinal studies without phase wrapping at high velocities or loss of sensitivity to slow velocities. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate. The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of mm per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow and calculate shear stress. In conclusion, our high-speed OCT system will enable automated Doppler imaging of embryonic hearts in cohort studies.

  7. 脉冲激光测距的时间间隔测量方法%Method of Measurement on Time-Interval in Pulsed Laser Ranging

    Institute of Scientific and Technical Information of China (English)

    陈瑞强; 江月松

    2013-01-01

    The performance of pulsed laser ranging is directly influenced by the method how to measure the time-interval. Refer to the idea of interpolation time-interval measurement, the character of triangle reference signal is used to realize measurement on time-interval which has advantages of long measurement range and high precision. The principle how to use triangle reference signal to realize measurement on time-interval is described. The factors that affect the precision of time-interval measurement is quantitatively analyzed. It is pointed out that the frequency of triangle reference signal and the noise attached in triangle reference signal are the two main factors which affect the precision of time-interval measurement. Then, their affect on the precision of time-interval measurement is numerically simulated. A confirmatory experiment is designed to explain how the noise attached in triangle reference signal affects the precision of time-interval measurement. Both the numerical simulation and the experimental result show that the method of measurement on time-interval in pulsed laser ranging which uses low frequency triangle reference signal can achieve high precision. Besides, both improving the frequency of triangle reference signal and reducing the noise attached in triangle reference signal can effectively improve the precision of time-interval measurement. The numerical simulation and experimental results also confirm the feasibility of measurement on time-interval on pulsed laser ranging.%时间间隔测量方法的优劣直接影响脉冲激光测距的性能.借鉴插值法的思想,提出了利用三角波参考信号的特点实现时间间隔测量的方法,具有测量范围大、测量精度高的优点.阐述了利用三角波参考信号实现时间间隔测量的原理,定量分析了影响时间间隔测量精度的因素,指出三角波参考信号的频率和噪声是影响测量精度的主要原因,并进行了数值仿真;设计实验

  8. Boresight calibration of construction misalignments for 3D scanners built with a 2D laser range finder rotating on its optical center.

    Science.gov (United States)

    Morales, Jesús; Martínez, Jorge L; Mandow, Anthony; Reina, Antonio J; Pequeño-Boter, Alejandro; García-Cerezo, Alfonso

    2014-10-24

    Many applications, like mobile robotics, can profit from acquiring dense, wide-ranging and accurate 3D laser data. Off-the-shelf 2D scanners are commonly customized with an extra rotation as a low-cost, lightweight and low-power-demanding solution. Moreover, aligning the extra rotation axis with the optical center allows the 3D device to maintain the same minimum range as the 2D scanner and avoids offsets in computing Cartesian coordinates. The paper proposes a practical procedure to estimate construction misalignments based on a single scan taken from an arbitrary position in an unprepared environment that contains planar surfaces of unknown dimensions. Inherited measurement limitations from low-cost 2D devices prevent the estimation of very small translation misalignments, so the calibration problem reduces to obtaining boresight parameters. The distinctive approach with respect to previous plane-based intrinsic calibration techniques is the iterative maximization of both the flatness and the area of visible planes. Calibration results are presented for a case study. The method is currently being applied as the final stage in the production of a commercial 3D rangefinder.

  9. 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.

  10. Navigation of an Autonomous Tractor for a Row-Type Tree Plantation Using a Laser Range Finder—Development of a Point-to-Go Algorithm

    Directory of Open Access Journals (Sweden)

    Pawin Thanpattranon

    2015-09-01

    Full Text Available It is challenging to develop a control algorithm that uses only one sensor to guide an autonomous vehicle. The objective of this research was to develop a control algorithm with a single sensor for an autonomous agricultural vehicle that could identify landmarks in the row-type plantation environment and navigate a vehicle to a point-to-go target location through the plantation. To enable such a navigation system for the plantation system, a laser range finder (LRF was used as a single sensor to detect objects and navigate a full-size autonomous agricultural tractor. The LRF was used to control the tractor as it followed a path, and landmarks were detected “on-the-go” in real time. The landmarks were selected based on data for their distances calculated by comparison with the surrounding objects. Once the landmarks were selected, a target point was calculated from the landmarks, and the tractor was navigated toward the target. Navigation experiments were successfully conducted on the selected paths without colliding with the surrounding objects. A real time kinematic global positioning system (RTK GPS was used to compare the positioning between the autonomous control and manual control. The results of this study showed that this control system could navigate the autonomous tractor to follow the paths, and the vehicle position differed from the manually driven paths by 0.264, 0.370 and 0.542 m for the wide, tight, and U-turn paths, respectively, with directional accuracies of 3.139°, 4.394°, and 5.217°, respectively, which are satisfactory for the autonomous operation of tractors on rubber or palm plantations. Therefore, this laser-based landmark detection and navigation system can be adapted to an autonomous navigation system to reduce the vehicle`s sensor cost and improve the accuracy of the positioning.

  11. IPCC workshop on impacts of ocean acidification on marine biology and ecosystems. Workshop report

    Energy Technology Data Exchange (ETDEWEB)

    Field, C.B.; Barros, V.; Stocker, T.F.; Dahe, Q.; Mach, K.J.; Plattner, G.-K.; Mastrandrea, M.D.; Tignor, M.; Ebi, K.L.

    2011-09-15

    Understanding the effects of increasing atmospheric CO{sub 2} concentrations on ocean chemistry, commonly termed ocean acidification, as well as associated impacts on marine biology and ecosystems, is an important component of scientific knowledge about global change. The Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) will include comprehensive coverage of ocean acidification and its impacts, including potential feedbacks to the climate system. To support ongoing AR5 assessment efforts, Working Group II and Working Group I (WGII and WGI) of the IPCC held a joint Workshop on Impacts of Ocean Acidification on Marine Biology and Ecosystems in Okinawa, Japan, from 17 to 19 January 2011. The workshop convened experts from the scientific community, including WGII and WGI AR5 authors and review editors, to synthesise scientific understanding of changes in ocean chemistry due to increased CO{sub 2} and of impacts of this changing chemistry on marine organisms, ecosystems, and ecosystem services. This workshop report summarises the scientific content and perspectives presented and discussed during the workshop. It provides syntheses of these perspectives for the workshop's core topics: (i) the changing chemistry of the oceans, (ii) impacts of ocean acidification for individual organisms, and (iii) scaling up responses from individual organisms to ecosystems. It also presents summaries of workshop discussions of key cross-cutting themes, ranging from detection and attribution of ocean acidification and its impacts to understanding ocean acidification in the context of other stressors on marine systems. Additionally, the workshop report includes extended abstracts for keynote and poster presentations at the workshop. (Author)

  12. t4 Workshop Report*

    Science.gov (United States)

    Kleensang, Andre; Maertens, Alexandra; Rosenberg, Michael; Fitzpatrick, Suzanne; Lamb, Justin; Auerbach, Scott; Brennan, Richard; Crofton, Kevin M.; Gordon, Ben; Fornace, Albert J.; Gaido, Kevin; Gerhold, David; Haw, Robin; Henney, Adriano; Ma’ayan, Avi; McBride, Mary; Monti, Stefano; Ochs, Michael F.; Pandey, Akhilesh; Sharan, Roded; Stierum, Rob; Tugendreich, Stuart; Willett, Catherine; Wittwehr, Clemens; Xia, Jianguo; Patton, Geoffrey W.; Arvidson, Kirk; Bouhifd, Mounir; Hogberg, Helena T.; Luechtefeld, Thomas; Smirnova, Lena; Zhao, Liang; Adeleye, Yeyejide; Kanehisa, Minoru; Carmichael, Paul; Andersen, Melvin E.; Hartung, Thomas

    2014-01-01

    Summary Despite wide-spread consensus on the need to transform toxicology and risk assessment in order to keep pace with technological and computational changes that have revolutionized the life sciences, there remains much work to be done to achieve the vision of toxicology based on a mechanistic foundation. A workshop was organized to explore one key aspect of this transformation – the development of Pathways of Toxicity (PoT) as a key tool for hazard identification based on systems biology. Several issues were discussed in depth in the workshop: The first was the challenge of formally defining the concept of a PoT as distinct from, but complementary to, other toxicological pathway concepts such as mode of action (MoA). The workshop came up with a preliminary definition of PoT as “A molecular definition of cellular processes shown to mediate adverse outcomes of toxicants”. It is further recognized that normal physiological pathways exist that maintain homeostasis and these, sufficiently perturbed, can become PoT. Second, the workshop sought to define the adequate public and commercial resources for PoT information, including data, visualization, analyses, tools, and use-cases, as well as the kinds of efforts that will be necessary to enable the creation of such a resource. Third, the workshop explored ways in which systems biology approaches could inform pathway annotation, and which resources are needed and available that can provide relevant PoT information to the diverse user communities. PMID:24127042

  13. The QED Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, G.W.

    1994-07-01

    On May 18--20, 1994, Argonne National Laboratory hosted the QED Workshop. The workshop was supported by special funding from the Office of Naval Research. The purpose of the workshop was to assemble of a group of researchers to consider whether it is desirable and feasible to build a proof-checked encyclopedia of mathematics, with an associated facility for theorem proving and proof checking. Among the projects represented were Coq, Eves, HOL, ILF, Imps, MathPert, Mizar, NQTHM, NuPrl, OTTER, Proof Pad, Qu-Prolog, and RRL. Although the content of the QED project is highly technical rigorously proof-checked mathematics of all sorts the discussions at the workshop were rarely technical. No prepared talks or papers were given. Instead, the discussions focused primarily on such political, sociological, practical, and aesthetic questions, such as Why do it? Who are the customers? How can one get mathematicians interested? What sort of interfaces are desirable? The most important conclusion of the workshop was that QED is an idea worthy pursuing, a statement with which virtually all the participants agreed. In this document, the authors capture some of the discussions and outline suggestions for the start of a QED scientific community.

  14. Header For Laser Diode

    Science.gov (United States)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  15. Workshop on thin film thermal conductivity measurements

    Science.gov (United States)

    Feldman, Albert; Balzaretti, Naira M.; Guenther, Arthur H.

    1998-04-01

    On a subject of considerable import to the laser-induced damage community, a two day workshop on the topic, Thin Film Thermal Conductivity Measurement was held as part of the 13th Symposium on Thermophysical Properties at the University of Colorado in Boulder CO, June 25 and 26, 1997. The Workshop consisted of 4 sessions of 17 oral presentations and two discussion sessions. Two related subjects of interest were covered; 1) methods and problems associated with measuring thermal conductivity ((kappa) ) of thin films, and 2) measuring and (kappa) of chemical vapor deposited (CVD) diamond. On the subject of thin film (kappa) measurement, several recently developed imaginative techniques were reviewed. However, several authors disagreed on how much (kappa) in a film differs from (kappa) in a bulk material of the same nominal composition. A subject of controversy was the definition of an interface. In the first discussion session, several questions were addressed, a principal one being, how do we know that the values of (kappa) we obtain are correct and is there a role for standards in thin film (kappa) measurement. The second discussion session was devoted to a round-robin interlaboratory comparison of (kappa) measurements on a set of CVD diamond specimens and several other specimens of lower thermal conductivity. Large interlaboratory differences obtained in an earlier round robin had been attributed to specimen inhomogeneity. Unfortunately, large differences were also observed in the second round robin even though the specimens were more homogenous. There was good consistency among the DC measurements, however, the AC measurements showed much greater variability. There was positive feedback from most of the attenders regarding the Workshop with nearly all respondents recommending another Workshop in three or fewer years. There was general recognition that thin film thermal conductivity measurements are important for predicting the resistance of optical coating

  16. Measurement Control Workshop Instructional Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Crawford, Cary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGinnis, Brent [Pacific Northwest National Lab. (PNNL), Richland, WA (United States) and Insolves LLC

    2014-04-01

    A workshop to teach the essential elements of an effective nuclear materials control and accountability (MC&A) programs are outlined, along with the modes of Instruction, and the roles and responsibilities of participants in the workshop.

  17. Measurement control workshop instructional materials

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Crawford, Cary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGinnis, Brent [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Insolves LLC, Piketon, OH (United States)

    2014-04-01

    A workshop to teach the essential elements of an effective nuclear materials control and accountability (MC&A) programs are outlined, along with the modes of Instruction, and the roles and responsibilities of participants in the workshop.

  18. Workshop on moisture buffer capacity

    DEFF Research Database (Denmark)

    2003-01-01

    Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003......Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003...

  19. WALLTURB International Workshop

    CERN Document Server

    Jimenez, Javier; Marusic, Ivan

    2011-01-01

    This book brings together selected contributions from the WALLTURB workshop on ”Understanding and modelling of wall turbulence” held in Lille, France, on April 21st to 23rd 2009. This workshop was organized by the WALLTURB consortium, in order to present to the relevant scientific community the main results of the project and to stimulate scientific discussions around the subject of wall turbulence. The workshop reviewed the recent progress in theoretical, experimental and numerical approaches to wall turbulence. The problems of zero pressure gradient, adverse pressure gradient and separating turbulent boundary layers were addressed in detail with the three approaches, using the most advanced tools. This book is a milestone in the research field, thanks to the high level of the invited speakers and the involvement of the contributors and a testimony of the achievement of the WALLTURB project.

  20. Chromosome 19 International Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Pericak-Vance, M.A. (Duke Univ., Durham, NC (United States). Medical Center); Ropers, H.H. (Univ. Hospital Nijmegen, (The Netherlands). Dept. of Human Genetics); Carrano, A.J. (Lawrence Livermore National Lab., CA (United States))

    1993-01-04

    The Second International Workshop on Human Chromosome 19 was hosted on January 25 and 26, 1992, by the Department of Human Genetics, University Hospital Nijmegen, The Netherlands, at the 'Meerdal Conference Center'. The workshop was supported by a grant from the European Community obtained through HUGO, the Dutch Research Organization (NWO) and the Muscular Dystrophy Association (MDA). Travel support for American participants was provided by the Department of Energy. The goals of this workshop were to produce genetic, physical and integrated maps of chromosome 19, to identify inconsistencies and gaps, and to discuss and exchange resources and techniques available for the completion of these maps. The second day of the meeting was largely devoted to region or disease specific efforts. In particular, the meeting served as a platform for assessing and discussing the recent progress made into the molecular elucidation of myotonic dystrophy.

  1. Workshop on molecular animation.

    Science.gov (United States)

    Bromberg, Sarina; Chiu, Wah; Ferrin, Thomas E

    2010-10-13

    From February 25 to 26, 2010, in San Francisco, the Resource for Biocomputing, Visualization, and Informatics (RBVI) and the National Center for Macromolecular Imaging (NCMI) hosted a molecular animation workshop for 21 structural biologists, molecular animators, and creators of molecular visualization software. Molecular animation aims to visualize scientific understanding of biomolecular processes and structures. The primary goal of the workshop was to identify the necessary tools for producing high-quality molecular animations, understanding complex molecular and cellular structures, creating publication supplementary materials and conference presentations, and teaching science to students and the public. Another use of molecular animation emerged in the workshop: helping to focus scientific inquiry about the motions of molecules and enhancing informal communication within and between laboratories.

  2. QCD Evolution Workshop

    CERN Document Server

    2015-01-01

    These are the proceedings of the QCD Evolution 2015 Workshop which was held 26–30 May, 2015 at Jefferson Lab, Newport News, Virginia, USA. The workshop is a continuation of a series of workshops held during four consecutive years 2011, 2012, 2013 at Jefferson Lab, and in 2014 in Santa Fe, NM. With the rapid developments in our understanding of the evolution of parton distributions including low-x, TMDs, GPDs, higher-twist correlation functions, and the associated progress in perturbative QCD, lattice QCD and effective field theory techniques we look forward with great enthusiasm to the 2015 meeting. A special attention was also paid to participation of experimentalists as the topics discussed are of immediate importance for the JLab 12 experimental program and a future Electron Ion Collider.

  3. Vulcano Workshop 2016

    CERN Document Server

    2016-01-01

    We announce the XVI Vulcano Workshop, which will be held from May 22nd to May 28th, 2016 in the Vulcano Island (Sicily, Italy). As in the past editions, the workshop will aim to gather people from High Energy Astrophysics and Particle Physics to discuss the most recent highlights in these fields. The workshop will cover the following topics: Astrophysics/Cosmology, Astrophysics/Gravity, Dark Matter, Particle Physics, Cosmic Rays, Gamma/Neutrino Astronomy, Neutrinos and Future Prospects. The scientific program will include several 30-minute review talks, to introduce the current problems, and 20-minute talks, giving new experimental and theoretical results. The participation is by invitation and limited to 80 people.

  4. NX15 science workshop

    CERN Multimedia

    2015-01-01

    Science. For some of us, it's daunting or maybe even terrifying. How to tell a good science story? That's the question we will explore together in this workshop. Conceived and produced by journalist and Scientific News producer Claudio Rosmino of Euronews, and presented by Euronews' Jeremy Wilks, the workshop will look at actual case studies (from Euronews and beyond) where science news proved exciting, inspiring and accessible to audiences around the world. These might include the Rosetta mission and CERN's work on Science for Peace. Together, we'll share ideas and knowledge around how science journalism and science news can increase its visibility in the media and maybe save the planet...!

  5. 2015 Workshop on Continuations

    DEFF Research Database (Denmark)

    his volume contains the papers presented at WoC 2015, the Workshop on Continuations held at ETAPS 2015. There were four submissions. Each of them was reviewed by, on the average, three PC members. The committee decided to accept three papers. The program also includes one invited talk. It also...... documents the depth, variety, and richness of continuations with four distilled tutorials. Thanks are due to the local organizers of ETAPS 2015 for the infras- tructure and to the general chairman of WoC 2015, Ugo de'Liguoro, for initiating this workshop and making it happen...

  6. Diode-pumped Q-switched Nd{sup 3+} : YAG laser operating in a wide temperature range without thermal stabilisation of pump diodes

    Energy Technology Data Exchange (ETDEWEB)

    Vainshenker, A E; Vilenskiy, A V; Kazakov, A A; Lysoy, B G; Mikhailov, L K; Pashkov, V A [Open Joint-Stock Company ' M.F. Stel' makh Polyus Research and Development Institute' , Moscow (Russian Federation)

    2013-02-28

    A model sample of a compact low-power-consumption Nd{sup 3+} : YAG laser emitting 20-mJ pulses with a pulse repetition rate up to 20 Hz (in cyclic duty) at a wavelength of 1064 nm is developed and studied. The laser is designed for operating at external temperatures from -40 to +50 deg C. This was achieved by using quasi-end diode pumping without thermal stabilisation of pump diodes. (laser optics 2012)

  7. Workshops as a Research Methodology

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Levinsen, Karin Tweddell

    2017-01-01

    This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice, and worksh......This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice......, and workshops as a research methodology. Focusing primarily on the latter, this paper presents five studies on upper secondary and higher education teachers’ professional development and on teaching and learning through video conferencing. Through analysis and discussion of these studies’ findings, we argue...... that workshops provide a platform that can aid researchers in identifying and exploring relevant factors in a given domain by providing means for understanding complex work and knowledge processes that are supported by technology (for example, e-learning). The approach supports identifying factors...

  8. Report of the Orientation Workshop

    DEFF Research Database (Denmark)

    Nunez, Heilyn Camacho; Buus, Lillian; Ogange, Betty

    2014-01-01

    This Orientation Workshops is part of MAAGART project. The workshop is divided in three parts: 1) pre-Orientation Workshop stage, 2) Face-to-Face stage and 3) post-Orientation stage. Pre and post stages will be developed online. All the activities will take place in a virtual learning environment...... the third stage....

  9. Fifth national stakeholder workshop summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    On April 9--11, 1997, the Department of Energy`s Office of Worker and Community Transition convened its fifth National Stakeholder Workshop. The workshop addressed a wide range of work force restructuring and community transition issues critical to the future success of the Department. Two important elements of the meeting were: (1) reviewing progress made on the challenges identified during the March 1996f stakeholder`s meeting in Atlanta, Georgia; and (2) identifying areas that needed priority attention during the early months of the second Clinton Administration. The format of the Workshop included several plenary sessions and a number of small group discussion sessions. The small group sessions focused on topics related to labor issues, work force restructuring, work force planning, community transition, and employee concerns. The sessions provided a wide range of views on worker and community transition issues. The workshop included presentations on the following topics: Welcome and introductions; Opening remarks; Community reuse organizations: recent accomplishments; Privatization: policy, practice and potential pitfalls; Department of Energy`s integrated training initiatives; Congressional perspective on work force restructuring; and, Privatization and the Ten Year Plan.

  10. A Robotic Indoor 3D Mapping System Using a 2D Laser Range Finder Mounted on a Rotating Four-Bar Linkage of a Mobile Platform

    Directory of Open Access Journals (Sweden)

    Yu-Shin Chou

    2013-01-01

    Full Text Available This paper describes our work in developing a 3D robotic mapping system composed by an experimental mobile platform equipped with a rotating laser range finder (LRF. For the purpose of obtaining more complete 3D scans of the environment, we design, construct and calibrate a crank‐rocker four‐bar linkage so that a LRF mounted on it could undergo repetitive rotational motion between two extreme positions, allowing both horizontal and vertical scans. To reduce the complexity of map representation suitable for optimization later, the local map from the LRF is a grid map represented by a distance‐transformed (DT matrix. We compare the DT‐transformed maps and find the transformation matrix of a robot pose by a linear simplex‐based map optimization method restricted to a local region allows efficient alignment of maps in scan matching. Several indoor 2D and 3D mapping experiments are presented to demonstrate the consistency, efficiency and accuracy of the 3D mapping system for a mobile robot that is stationary or in motion.

  11. Geohydrology of the High Energy Laser System Test Facility site, White Sands Missile Range, Tularosa Basin, south-central New Mexico

    Science.gov (United States)

    Basabilvazo, G.T.; Nickerson, E.L.; Myers, R.G.

    1994-01-01

    The Yesum-HoHoman and Gypsum land (hummocky) soils at the High Energy Laser System Test Facility (HELSTF) represent wind deposits from recently desiccated lacustrine deposits and deposits from the ancestral Lake Otero. The upper 15-20 feet of the subsurface consists of varved gypsiferous clay and silt. Below these surfidai deposits the lithology consists of interbedded clay units, silty-clay units, and fine- to medium-grained quartz arenite units in continuous and discontinuous horizons. Clay horizons can cause perched water above the water table. Analyses of selected clay samples indicate that clay units are composed chiefly of kaolinire and mixed-layer illite/ smectite. The main aquifer is representative of a leaky-confined aquifer. Estimated aquifer properties are: transmissivity (T) = 780 feet squared per day, storage coefficient (S) = 3.1 x 10-3, and hydraulic conductivity (K) = 6.0 feet per day. Ground water flows south and southwest; the estimated hydraulic gradient is 5.3 feet per mile. Analyses of water samples indicate that ground water at the HELSTF site is brackish to slightly saline at the top of the main aquifer. Dissolved-solids concentration near the top of the main aquifer ranges from 5,940 to 11,800 milligrams per liter. Predominant ions are sodium and sulfate. At 815 feet below land surface, the largest dissolved-solids concentration measured is 111,000 milligrams per liter, which indicates increasing salinity with depth. Predominant ions are sodium and chloride.

  12. Second Quaternary dating workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  13. Flywheel energy storage workshop

    Energy Technology Data Exchange (ETDEWEB)

    O`Kain, D.; Carmack, J. [comps.

    1995-12-31

    Since the November 1993 Flywheel Workshop, there has been a major surge of interest in Flywheel Energy Storage. Numerous flywheel programs have been funded by the Advanced Research Projects Agency (ARPA), by the Department of Energy (DOE) through the Hybrid Vehicle Program, and by private investment. Several new prototype systems have been built and are being tested. The operational performance characteristics of flywheel energy storage are being recognized as attractive for a number of potential applications. Programs are underway to develop flywheels for cars, buses, boats, trains, satellites, and for electric utility applications such as power quality, uninterruptible power supplies, and load leveling. With the tremendous amount of flywheel activity during the last two years, this workshop should again provide an excellent opportunity for presentation of new information. This workshop is jointly sponsored by ARPA and DOE to provide a review of the status of current flywheel programs and to provide a forum for presentation of new flywheel technology. Technology areas of interest include flywheel applications, flywheel systems, design, materials, fabrication, assembly, safety & containment, ball bearings, magnetic bearings, motor/generators, power electronics, mounting systems, test procedures, and systems integration. Information from the workshop will help guide ARPA & DOE planning for future flywheel programs. This document is comprised of detailed viewgraphs.

  14. FINPIE/97. Workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This publication contains the proceedings of 1997 Finnish Workshop on Power and Industrial Electronics, held in Espoo, Finland, on 26 August, 1997. The programme consisted of technical sessions on Advanced AC Motor Control, Electric Machines and Drives, Advanced Control and Measurement, Power Electronics Systems, Modelling and Simulation, and Power Converters

  15. International phosphorus workshop

    DEFF Research Database (Denmark)

    Kronvang, Brian; Rubæk, Gitte Holton; Heckrath, Goswin

    2009-01-01

    the main outcomes of the workshop and the special collection of eight papers. Moreover, we identify the main gaps in our knowledge and future research directions on P, which are linked to important issues such as addressing scale effects, improved P models with the ability to quantify uncertainty...

  16. Workshop on Mathematical Physics

    CERN Document Server

    2016-01-01

    This two-day workshop will include seminars by mathematicians and physicists on topics of mutual interest. It will precede the 31st International Colloquium on Group Theoretical Methods in Physics which will be held in Rio de Janeiro from June 19-25.

  17. Workshop on hybrid rice

    Institute of Scientific and Technical Information of China (English)

    TANZhijun

    1994-01-01

    FAO, in collaboration with FEDEARROZ in Colombia and EMBRAPA / CNPAF in Brail, organized a workshop on the Establishment of a Coorperative Research Network on Hybrid Rice in Latin America and the Caribbean held from Mar 16 to 18, 1994 at EMBRAPA/CNPAF in Brazil. Dr MAO Changxiang,

  18. Summary of cosmology workshop

    Indian Academy of Sciences (India)

    Tarun Sandeep

    2004-10-01

    Cosmology is passing through a golden phase of rapid advance. The cosmology workshop at ICGC-2004 attracted a large number of research contributions to diverse topics of cosmology. I attempt to classify and summarize the research work and results of the oral and poster presentations made at the meeting.

  19. Dynamic defense workshop :

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, Sean Michael; Doak, Justin E.; Haas, Jason Juedes.; Helinski, Ryan; Lamb, Christopher C.

    2013-02-01

    On September 5th and 6th, 2012, the Dynamic Defense Workshop: From Research to Practice brought together researchers from academia, industry, and Sandia with the goals of increasing collaboration between Sandia National Laboratories and external organizations, de ning and un- derstanding dynamic, or moving target, defense concepts and directions, and gaining a greater understanding of the state of the art for dynamic defense. Through the workshop, we broadened and re ned our de nition and understanding, identi ed new approaches to inherent challenges, and de ned principles of dynamic defense. Half of the workshop was devoted to presentations of current state-of-the-art work. Presentation topics included areas such as the failure of current defenses, threats, techniques, goals of dynamic defense, theory, foundations of dynamic defense, future directions and open research questions related to dynamic defense. The remainder of the workshop was discussion, which was broken down into sessions on de ning challenges, applications to host or mobile environments, applications to enterprise network environments, exploring research and operational taxonomies, and determining how to apply scienti c rigor to and investigating the eld of dynamic defense.

  20. Workshop on DNA repair.

    NARCIS (Netherlands)

    A.R. Lehmann (Alan); J.H.J. Hoeijmakers (Jan); A.A. van Zeeland (Albert); C.M.P. Backendorf (Claude); B.A. Bridges; A. Collins; R.P.D. Fuchs; G.P. Margison; R. Montesano; E. Moustacchi; A.T. Natarajan; M. Radman; A. Sarasin; E. Seeberg; C.A. Smith; M. Stefanini (Miria); L.H. Thompson; G.P. van der Schans; C.A. Weber (Christine); M.Z. Zdzienika

    1992-01-01

    textabstractA workshop on DNA repair with emphasis on eukaryotic systems was held, under the auspices of the EC Concerted Action on DNA Repair and Cancer, at Noordwijkerhout (The Netherlands) 14-19 April 1991. The local organization of the meeting was done under the auspices of the Medical Genetic C

  1. Beginnings Workshop: Mealtimes.

    Science.gov (United States)

    Gordon, Sarah A. Mulligan; And Others

    1997-01-01

    Contains four workshop presentations on meals in child care: (1) "Enjoying Family-Style Meals in Child Care" (Sarah A. Mulligan Gordon); (2) "The Making of a Healthy Eater: Winning the Finicky Eater Battle" (James M. Thomas and others); (3) "Food for Thought: Mealtimes can be Educational and Enjoyable, Too" (Karen…

  2. Radiation Source Replacement Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  3. Workshop One : Risk Analysis

    NARCIS (Netherlands)

    Carlson, T.J.; Jong, C.A.F. de; Dekeling, R.P.A.

    2012-01-01

    The workshop looked at the assessment of risk to aquatic animals exposed to anthropogenic sound. The discussion focused on marine mammals given the worldwide attention being paid to them at the present time, particularly in relationship to oil and gas exploration, ocean power, and increases in ship

  4. ATLAS TRT 2002 Workshop

    CERN Multimedia

    Capeans, M.

    Starting on 17th May, the ATLAS TRT 2002 Workshop was organised by Ken MacFarlane and his team at Hampton University, Virginia, USA. During a welcome break in the very dense workshop programme, the group enjoyed a half-day long boat trip along the waterways, offering a first-hand look at the history and heritage of this part of America. The attendance during the six-day workshop was about 50 people representing most of the collaborating institutes, although many Russian colleagues had stayed in their institutes to pursue the start-up of end-cap wheel production at PNPI and DUBNA. The meeting clearly showed that, during the year 2002, the TRT community is focusing on final design issues and module/wheel construction, while moving at the same time towards acceptance testing and integration, including the front-end electronics. The two main topics treated at the workshop were the preparation for beginning full production of the FE electronics, and the wire-joint problem that the US barrel colleagues have been fa...

  5. Canadian EdGEO National Workshop Program

    Science.gov (United States)

    Clinton, L. A.; Haidl, F. M.; Hymers, L. A.; van der Flier-Keller, E.

    2009-05-01

    Established in the early 1970s, EdGEO supports locally driven geosciences workshops for Canadian teachers. Workshops are organized by geoscientists and teachers, and typically have field, laboratory and classroom components. Grants of up to $3000 per workshop are available from the National EdGEO Program. By providing educational opportunities for today's teachers and, through them, their students, EdGEO seeks to cultivate a heightened awareness of our planet. EdGEO workshops provide teachers with potential fieldtrip sites for their students and the knowledge, enthusiasm and materials to inspire their students to engage in geoscience. Networking opportunities with local experts promote the importance of the geoscience profession. The expected result is an improved capacity on the part of Canadians to understand the Earth and to make informed decisions, especially with regard to the use of mineral and energy resources, the maintenance and remediation of the environment, and response to geological hazards. There exists a critical need to provide teachers with training and resources to tackle their Earth science curricula. In 2008, EdGEO supported fourteen workshops, with an unprecedented 521 teachers attending. These teachers then used our resources to reach an estimated 14,000 students during that single academic year. EdGEO workshops are locally driven and are therefore very diverse. Workshops are strongly tied to the provincial curriculum, focus on a specific geoscience topic, or may be largely field-based to demonstrate and practice how field activities could be incorporated into Earth science teaching. Many strive to include all of these important components. Geoscientists and teachers work collaboratively to develop and deliver EdGEO workshops to ensure that the activities can be effectively used in the classroom. The length of these professional development opportunities range from two-hour sessions to several days, and can generally accommodate up to twenty

  6. Proceedings of the switched power workshop

    Energy Technology Data Exchange (ETDEWEB)

    Fernow, R.C. (ed.)

    1988-01-01

    These proceedings contain most of the presentations given at a workshop on the current state of research in techniques for switched power acceleration. The proceedings are divided, as was the workshop itself, into two parts. Part 1, contains the latest results from a number of groups active in switched power research. The major topic here is a method for switching externally supplied power onto a transmission line. Advocates for vacuum photodiode switching, solid state switching, gas switching, and synthetic pulse generation are all presented. Other important areas of research described in this section concern: external electrical and laser pulsing systems; the properties of the created electromagnetic pulse; structures used for transporting the electromagnetic pulse to the region where the electron beam is located; and possible applications. Part 2 of the proceedings considers the problem of designing a high brightness electron gun using switched power as the power source. This is an important first step in demonstrating the usefulness of switched power techniques for accelerator physics. In addition such a gun could have immediate practical importance for advanced acceleration studies since the brightness could exceed that of present sources by several orders of magnitude. I would like to take this opportunity to thank Kathleen Tuohy and Patricia Tuttle for their assistance in organizing and running the workshop. Their tireless efforts contribute greatly to a very productive meeting.

  7. UVI Cyber-security Workshop Workshop Analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Kuykendall, Tommie G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Allsop, Jacob Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, Benjamin Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boumedine, Marc [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carter, Cedric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Galvin, Seanmichael Yurko [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Oscar [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Wellington K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lin, Han Wei [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Morris, Tyler Jake [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nauer, Kevin S.; Potts, Beth A.; Ta, Kim Thanh; Trasti, Jennifer; White, David R.

    2015-07-08

    The cybersecurity consortium, which was established by DOE/NNSA’s Minority Serving Institutions Partnerships Program (MSIPP), allows students from any of the partner schools (13 HBCUs, two national laboratories, and a public school district) to have all consortia options available to them, to create career paths and to open doors to DOE sites and facilities to student members of the consortium. As a part of this year consortium activities, Sandia National Laboratories and the University of Virgin Islands conducted a week long cyber workshop that consisted of three courses; Digital Forensics and Malware Analysis, Python Programming, and ThunderBird Cup. These courses are designed to enhance cyber defense skills and promote learning within STEM related fields.

  8. Excimer Laser Technology

    CERN Document Server

    Basting, Dirk

    2005-01-01

    This comprehensive survey on Excimer Lasers investigates the current range of the technology, applications and devices of this commonly used laser source, as well as the future of new technologies, such as F2 laser technology. Additional chapters on optics, devices and laser systems complete this compact handbook. A must read for laser technology students, process application researchers, engineers or anyone interested in excimer laser technology. An effective and understandable introduction to the current and future status of excimer laser technology.

  9. Polish and European SST Assets: the Solaris-Panoptes Global Network of Robotic Telescopes and the Borowiec Satellite Laser Ranging System

    Science.gov (United States)

    Konacki, M.; Lejba, P.; Sybilski, P.; Pawłaszek, R.; Kozłowski, S.; Suchodolski, T.; Litwicki, M.; Kolb, U.; Burwitz, V.; Baader, J.; Groot, P.; Bloemen, S.; Ratajczak, M.; Helminiak, K.; Borek, R.; Chodosiewicz, P.

    2016-09-01

    We present the assets of the Nicolaus Copernicus Astronomical Center, Space Research Center (both of the Polish Academy of Sciences), two Polish companies Sybilla Technologies, Cillium Engineering and a non-profit research foundation Baltic Institute of Technology. These assets are enhanced by telescopes belonging to The Open University (UK), the Max Planck Institute for Extraterrestrial Physics and in the future the Radboud University. They consist of the Solaris-Panoptes global network of optical robotic telescopes and the satellite laser ranging station in Borowiec, Poland. These assets will contribute to the Polish and European Space Surveillance and Tracking (SST) program. The Solaris component is composed of four autonomous observatories in the Southern Hemisphere. Solaris nodes are located at the South African Astronomical Observatory (Solaris-1 and Solaris-2), Siding Spring Observatory, Australia (Solaris-3) and Complejo Astronomico El Leoncito, Argentina (Solaris-4). They are equipped with 0.5-m telescopes on ASA DDM-160 direct drive mounts, Andor iKon-L cameras and housed in 3.5-m Baader Planetarium (BP) clamshell domes. The Panoptes component is a network of telescopes operated by software from Sybilla Technologies. It currently consists of 4 telescopes at three locations, all on GM4000 mounts. One 0.36-m (Panoptes-COAST, STL- 1001E camera, 3.5 BP clamshell dome) and one 0.43-m (Panoptes-PIRATE, FLI 16803 camera, 4.5-m BP clamshell dome, with planned exchange to 0.63-m) telescope are located at the Teide Observatory (Tenerfie, Canary Islands), one 0.6-m (Panoptes-COG, SBIG STX 16803 camera, 4.5-m BP clamshell dome) telescope in Garching, Germany and one 0.5-m (Panoptes-MAM, FLI 16803 camera, 4.5-m BP slit dome) in Mammendorf, Germany. Panoptes-COAST and Panoptes-PIRATE are owned by The Open University (UK). Panoptes-COG is owned by the Max Planck Institute

  10. Signal-to-noise ratio improvements in laser flow diagnostics using time-resolved image averaging and high dynamic range imaging

    Science.gov (United States)

    Giassi, Davide; Long, Marshall B.

    2016-08-01

    Two alternative image readout approaches are demonstrated to improve the signal-to-noise ratio (SNR) in temporally resolved laser-based imaging experiments of turbulent phenomena. The first method exploits the temporal decay characteristics of the phosphor screens of image intensifiers when coupled to an interline-transfer CCD camera operated in double-frame mode. Specifically, the light emitted by the phosphor screen, which has a finite decay constant, is equally distributed and recorded over the two sequential frames of the detector so that an averaged image can be reconstructed. The characterization of both detector and image intensifier showed that the technique preserves the correct quantitative information, and its applicability to reactive flows was verified using planar Rayleigh scattering and tested with the acquisition of images of both steady and turbulent partially premixed methane/air flames. The comparison between conventional Rayleigh results and the averaged ones showed that the SNR of the averaged image is higher than the conventional one; with the setup used in this work, the gain in SNR was seen to approach 30 %, for both the steady and turbulent cases. The second technique uses the two-frame readout of an interline-transfer CCD to increase the image SNR based on high dynamic range imaging, and it was tested in an unsteady non-reactive flow of Freon-12 injected in air. The result showed a 15 % increase in the SNR of the low-pixel-count regions of an image, when compared to the pixels of a conventionally averaged one.

  11. EPA Workshop on Epigenetics and Cumulative Risk ...

    Science.gov (United States)

    Agenda Download the Workshop Agenda (PDF) The workshop included presentations and discussions by scientific experts pertaining to three topics (i.e., epigenetic changes associated with diverse stressors, key science considerations in understanding epigenetic changes, and practical application of epigenetic tools to address cumulative risks from environmental stressors), to address several questions under each topic, and included an opportunity for attendees to participate in break-out groups, provide comments and ask questions. Workshop Goals The workshop seeks to examine the opportunity for use of aggregate epigenetic change as an indicator in cumulative risk assessment for populations exposed to multiple stressors that affect epigenetic status. Epigenetic changes are specific molecular changes around DNA that alter expression of genes. Epigenetic changes include DNA methylation, formation of histone adducts, and changes in micro RNAs. Research today indicates that epigenetic changes are involved in many chronic diseases (cancer, cardiovascular disease, obesity, diabetes, mental health disorders, and asthma). Research has also linked a wide range of stressors including pollution and social factors with occurrence of epigenetic alterations. Epigenetic changes have the potential to reflect impacts of risk factors across multiple stages of life. Only recently receiving attention is the nexus between the factors of cumulative exposure to environmental

  12. Application and validation of long-range terrestrial laser scanning to monitor the mass balance of very small glaciers in the Swiss Alps

    Science.gov (United States)

    Fischer, Mauro; Huss, Matthias; Kummert, Mario; Hoelzle, Martin

    2016-06-01

    Due to the relative lack of empirical field data, the response of very small glaciers (here defined as being smaller than 0.5 km2) to current atmospheric warming is not fully understood yet. Investigating their mass balance, e.g. using the direct glaciological method, is a prerequisite to fill this knowledge gap. Terrestrial laser scanning (TLS) techniques operating in the near infrared range can be applied for the creation of repeated high-resolution digital elevation models and consecutive derivation of annual geodetic mass balances of very small glaciers. This method is promising, as laborious and potentially dangerous field measurements as well as the inter- and extrapolation of point measurements can be circumvented. However, it still needs to be validated. Here, we present TLS-derived annual surface elevation and geodetic mass changes for five very small glaciers in Switzerland (Glacier de Prapio, Glacier du Sex Rouge, St. Annafirn, Schwarzbachfirn, and Pizolgletscher) and two consecutive years (2013/14-2014/15). The scans were acquired with a long-range Riegl -6000 especially designed for surveying snow- and ice-covered terrain. Zonally variable conversion factors for firn and bare ice surfaces were applied to convert geodetic volume to mass changes. We compare the geodetic results to direct glaciological mass balance measurements coinciding with the TLS surveys and assess the uncertainties and errors included in both methods. Average glacier-wide mass balances were negative in both years, showing stronger mass losses in 2014/15 (-1.65 m w.e.) compared to 2013/14 (-0.59 m w.e.). Geodetic mass balances were slightly less negative but in close agreement with the direct glaciological ones (R2 = 0.91). Due to the dense in situ measurements, the uncertainties in the direct glaciological mass balances were small compared to the majority of measured glaciers worldwide (±0.09 m w.e. yr-1 on average), and similar to uncertainties in the TLS-derived geodetic mass

  13. Range Compressed Holographic Aperture Ladar

    Science.gov (United States)

    2017-06-01

    digital holography, laser, active imaging, remote sensing, laser imaging 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT: SAR 8...slow speed tunable lasers, while relaxing the need to precisely track the transceiver or target motion. In the following section we describe a scenario...contrast targets. As shown in Figure 28, augmenting holographic ladar with range compression relaxes the dependence of image reconstruction on

  14. MATHEON Workshop 2013

    CERN Document Server

    Calderbank, Robert; Kutyniok, Gitta; Vybíral, Jan

    2015-01-01

    Since publication of the initial papers in 2006, compressed sensing has captured the imagination of the international signal processing community, and the mathematical foundations are nowadays quite well understood. Parallel to the progress in mathematics, the potential applications of compressed sensing have been explored by many international groups of, in particular, engineers and applied mathematicians, achieving very promising advances in various areas such as communication theory, imaging sciences, optics, radar technology, sensor networks, or tomography. Since many applications have reached a mature state, the research center MATHEON in Berlin focusing on "Mathematics for Key Technologies", invited leading researchers on applications of compressed sensing from mathematics, computer science, and engineering to the "MATHEON Workshop 2013: Compressed Sensing and its Applications” in December 2013. It was the first workshop specifically focusing on the applications of compressed sensing. This book featur...

  15. Accelerator reliability workshop

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, L.; Duru, Ph.; Koch, J.M.; Revol, J.L.; Van Vaerenbergh, P.; Volpe, A.M.; Clugnet, K.; Dely, A.; Goodhew, D

    2002-07-01

    About 80 experts attended this workshop, which brought together all accelerator communities: accelerator driven systems, X-ray sources, medical and industrial accelerators, spallation sources projects (American and European), nuclear physics, etc. With newly proposed accelerator applications such as nuclear waste transmutation, replacement of nuclear power plants and others. Reliability has now become a number one priority for accelerator designers. Every part of an accelerator facility from cryogenic systems to data storage via RF systems are concerned by reliability. This aspect is now taken into account in the design/budget phase, especially for projects whose goal is to reach no more than 10 interruptions per year. This document gathers the slides but not the proceedings of the workshop.

  16. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  17. PREFACE: Collapse Calderas Workshop

    Science.gov (United States)

    Gottsmann, Jo; Aguirre-Diaz, Gerardo

    2008-10-01

    Caldera-formation is one of the most awe-inspiring and powerful displays of nature's force. Resultant deposits may cover vast areas and significantly alter the immediate topography. Post-collapse activity may include resurgence, unrest, intra-caldera volcanism and potentially the start of a new magmatic cycle, perhaps eventually leading to renewed collapse. Since volcanoes and their eruptions are the surface manifestation of magmatic processes, calderas provide key insights into the generation and evolution of large-volume silicic magma bodies in the Earth's crust. Despite their potentially ferocious nature, calderas play a crucial role in modern society's life. Collapse calderas host essential economic deposits and supply power for many via the exploitation of geothermal reservoirs, and thus receive considerable scientific, economic and industrial attention. Calderas also attract millions of visitors world-wide with their spectacular scenic displays. To build on the outcomes of the 2005 calderas workshop in Tenerife (Spain) and to assess the most recent advances on caldera research, a follow-up meeting was proposed to be held in Mexico in 2008. This abstract volume presents contributions to the 2nd Calderas Workshop held at Hotel Misión La Muralla, Querétaro, Mexico, 19-25 October 2008. The title of the workshop `Reconstructing the evolution of collapse calderas: Magma storage, mobilisation and eruption' set the theme for five days of presentations and discussions, both at the venue as well as during visits to the surrounding calderas of Amealco, Amazcala and Huichapan. The multi-disciplinary workshop was attended by more than 40 scientist from North, Central and South America, Europe, Australia and Asia. Contributions covered five thematic topics: geology, geochemistry/petrology, structural analysis/modelling, geophysics, and hazards. The workshop was generously supported by the International Association of Volcanology and the Chemistry of The Earth's Interior

  18. Solar workshops financial incentives

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    Ten one-day workshops were held across the United States. Information in this workbook is compiled in conjunction with those workshops. The following discussions are included: solar as a fuel (history); why alternative fuels are being sought today; the need for conservation; advantages of solar energy; the potential of solar energy; why solar energy is not more widely used; a definition of solar; how solar can help meet energy demands; Federal policies and programs; what solar technologies exist today that can be effectively utilized (thermal applications, fuels from biomass, solar electric). Additional information is presented in three attachments: Energy-Conserving Methods; Domestic Policy Review of Solar Energy; and DOE Secretary's Annual Report to Congress-Solar Section. (MCW)

  19. Imaging Sciences Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Candy, J.V.

    1996-11-21

    This report contains the proceedings of the Imaging Sciences Workshop sponsored by C.A.S.LS., the Center for Advanced Signal & Image Sciences. The Center, established primarily to provide a forum where researchers can freely exchange ideas on the signal and image sciences in a comfortable intellectual environment, has grown over the last two years with the opening of a Reference Library (located in Building 272). The Technical Program for the 1996 Workshop include a variety of efforts in the Imaging Sciences including applications in the Microwave Imaging, highlighted by the Micro-Impulse Radar (MIR) system invented at LLNL, as well as other applications in this area. Special sessions organized by various individuals in Speech, Acoustic Ocean Imaging, Radar Ocean Imaging, Ultrasonic Imaging, and Optical Imaging discuss various applica- tions of real world problems. For the more theoretical, sessions on Imaging Algorithms and Computed Tomography were organized as well as for the more pragmatic featuring a session on Imaging Systems.

  20. Imaging sciences workshop

    Energy Technology Data Exchange (ETDEWEB)

    Candy, J.V.

    1994-11-15

    This workshop on the Imaging Sciences sponsored by Lawrence Livermore National Laboratory contains short abstracts/articles submitted by speakers. The topic areas covered include the following: Astronomical Imaging; biomedical imaging; vision/image display; imaging hardware; imaging software; Acoustic/oceanic imaging; microwave/acoustic imaging; computed tomography; physical imaging; imaging algorithms. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  1. Aims of the Workshop

    CERN Document Server

    Dornan, P J

    2010-01-01

    There are challenges and opportunities for the European particle physics community to engage with innovative and exciting developments which could lead to precision measurements in the neutrino sector. These have the potential to yield significant advances in the understanding of CP violation, the flavour riddle and theories beyond the Standard Model. This workshop aims to start the process of a dialogue in Europe so that informed decisions on the appropriate directions to pursue can be made in a few years time.

  2. Proceedings of the solar irrigation workshop

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-06-01

    The ERDA Solar Irrigation Workshop was structured to be a major vehicle for information dissemination and technology transfer. It covered a wide range of subject matter related to crop irrigation including current hardware, economics, experiments, and international requirements. Speakers represented manufacturers, ranchers, governmental entities, universities and research firms. The proceedings consist of one page abstracts for each presentation, a brief biographical sketch of each speaker and sources for further information on each subject.

  3. The ROS Workshop

    CERN Multimedia

    Francis, D.

    The first week of February saw the taking place of the ReadOut Subsystem (ROS) workshop. The ROS is the subsystem of the Trigger, DAQ & DCS project which receives and buffers data from the detector ReadOut Drivers (RODs). On request it then provides a subset of this buffered data, the so-called Regions of Interest (RoI), to the Level 2 trigger. Using the subsequent Level 2 trigger decision, the ROS either removes the buffered event data from its buffers or sends the full event data to the Event Filter for further processing. The workshop took place over a four-day period at a location in the Jura. The average daily attendance was twenty people, which mainly represented the five main ATLAS institutes currently engaged in this Trigger, DAQ & DCS activity. The aim of the workshop was to bring to an end the current prototyping activities in this area and launch the next, final, phase of prototyping. This new phase of prototyping will build on the successful activities of the previous phase and will focus...

  4. Grid and Entrepreneurship Workshop

    CERN Multimedia

    2006-01-01

    The CERN openlab is organising a special workshop about Grid opportunities for entrepreneurship. This one-day event will provide an overview of what is involved in spin-off technology, with a special reference to the context of computing and data Grids. Lectures by experienced entrepreneurs will introduce the key concepts of entrepreneurship and review, in particular, the industrial potential of EGEE (the EU co-funded Enabling Grids for E-sciencE project, led by CERN). Case studies will be given by CEOs of European start-ups already active in the Grid and computing cluster area, and regional experts will provide an overview of efforts in several European regions to stimulate entrepreneurship. This workshop is designed to encourage students and researchers involved or interested in Grid technology to consider the entrepreneurial opportunities that this technology may create in the coming years. This workshop is organized as part of the CERN openlab student programme, which is co-sponsored by CERN, HP, ...

  5. The Center for the Holographic Arts Begins a New Artist Workshop and Residency Program in Conjunction with Ohio State University

    Science.gov (United States)

    Mrongovius, Martina; Kagan, Harris; Moree, Sam

    2013-02-01

    This year the Center for the Holographic Arts (Holocenter) kicked off a new Artist Workshop and Residency Program in conjunction with Ohio State University. The newly renovated holography facility houses the Holocenter's pulse laser camera and two recording tables with continuous wave lasers. This facility is being utilized for undergraduate and postgraduate courses in Art and Technology as well as the Artist Workshop and Residency Program.

  6. 4. Workshop - Measurement techniques of stationary and transient multiphase flow

    Energy Technology Data Exchange (ETDEWEB)

    Prasser, H.M. (ed.)

    2001-05-01

    In November 2000, the 4th Workshop on Measurement Techniques for Stationary and Transient Multiphase Flows took place in Rossendorf. Three previous workshops of this series were national meetings; this time participants from different countries took part. The programme comprised 14 oral presentations, 9 of which are included in these proceedings in full length. A special highlight of the meeting was the main lecture ''Ultrasonic doppler method for bubbly flow measurement'' of Professor Masanori Aritomi, Dr. Hiroshige Kikura and Dr. Yumiko Suzuki. The workshop again dealt with high-resolution phase distribution and phase velocity measurement techniques based on electrical conductivity, ultrasound, laser light and high-speed cinematography. A number of presentations were dedicated to the application of wire-mesh sensors developed by FZR for different applications used by the Technical Universities of Delft and Munich and the Tokyo Institute of Technology. (orig.)

  7. 2014 Penn State Bioinorganic Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Golbeck, John [Pennsylvania State Univ., State College, PA (United States)

    2015-10-01

    The 3rd Penn State Bioinorganic Workshop took place in early June 2014 and was combined with the 3rd Penn State Frontiers in Metallobiochemistry Symposium. The workshop was even larger than the 2nd Penn State Bioinorganic Workshop we offered in 2012. It had even more participants (162 rather than 123 in 2012). Like the 2012 workshop, the 2014 workshop had three parts. The first part consisted of 16 90-minute lectures presented by faculty experts on the topic of their expertise (see below). Based on the suggestions from the 2012 workshop, we have recorded all 16 lectures professionally and make them available to the entire bioinorganic community via online streaming. In addition, hard copies of the recordings are available as backup.

  8. Optical Network Testbeds Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Joe Mambretti

    2007-06-01

    This is the summary report of the third annual Optical Networking Testbed Workshop (ONT3), which brought together leading members of the international advanced research community to address major challenges in creating next generation communication services and technologies. Networking research and development (R&D) communities throughout the world continue to discover new methods and technologies that are enabling breakthroughs in advanced communications. These discoveries are keystones for building the foundation of the future economy, which requires the sophisticated management of extremely large qualities of digital information through high performance communications. This innovation is made possible by basic research and experiments within laboratories and on specialized testbeds. Initial network research and development initiatives are driven by diverse motives, including attempts to solve existing complex problems, the desire to create powerful new technologies that do not exist using traditional methods, and the need to create tools to address specific challenges, including those mandated by large scale science or government agency mission agendas. Many new discoveries related to communications technologies transition to wide-spread deployment through standards organizations and commercialization. These transition paths allow for new communications capabilities that drive many sectors of the digital economy. In the last few years, networking R&D has increasingly focused on advancing multiple new capabilities enabled by next generation optical networking. Both US Federal networking R&D and other national R&D initiatives, such as those organized by the National Institute of Information and Communications Technology (NICT) of Japan are creating optical networking technologies that allow for new, powerful communication services. Among the most promising services are those based on new types of multi-service or hybrid networks, which use new optical networking

  9. Annual Workshop: Higgs Couplings 2016

    CERN Document Server

    2016-01-01

    Higgs Couplings 2016 is this year's installment of an annual workshop devoted to new experimental and theoretical results on the Higgs boson. The 2016 workshop will present the latest results from the LHC run 2 on the Higgs boson mass, spin/parity, and couplings and will present new theoretical work devoted to the measurement of Higgs parameters and possibilities for exotic Higgs decays. The workshop will provide an opportunity for critical discussion of the current strategies for studying the Higgs boson at the LHC and the next steps in the LHC program. The workshop will also include discussion of the longer-term Higgs boson program at future facilities.

  10. Association between mild cognitive impairment and trajectory-based spatial parameters during timed up and go test using a laser range sensor.

    Science.gov (United States)

    Nishiguchi, Shu; Yorozu, Ayanori; Adachi, Daiki; Takahashi, Masaki; Aoyama, Tomoki

    2017-08-08

    The Timed Up and Go (TUG) test may be a useful tool to detect not only mobility impairment but also possible cognitive impairment. In this cross-sectional study, we used the TUG test to investigate the associations between trajectory-based spatial parameters measured by laser range sensor (LRS) and cognitive impairment in community-dwelling older adults. The participants were 63 community-dwelling older adults (mean age, 73.0 ± 6.3 years). The trajectory-based spatial parameters during the TUG test were measured using an LRS. In each forward and backward phase, we calculated the minimum distance from the marker, the maximum distance from the x-axis (center line), the length of the trajectories, and the area of region surrounded by the trajectory of the center of gravity and the x-axis (center line). We measured mild cognitive impairment using the Mini-Mental State Examination score (26/27 was the cut-off score for defining mild cognitive impairment). Compared with participants with normal cognitive function, those with mild cognitive impairment exhibited the following trajectory-based spatial parameters: short minimum distance from the marker (p = 0.044), narrow area of center of gravity in the forward phase (p = 0.012), and a large forward/whole phase ratio of the area of the center of gravity (p = 0.026) during the TUG test. In multivariate logistic regression analyses, a short minimum distance from the marker (odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.69-0.98), narrow area of the center of gravity in the forward phase (OR: 0.01, 95% CI: 0.00-0.36), and large forward/whole phase ratio of the area of the center of gravity (OR: 0.94, 95% CI: 0.88-0.99) were independently associated with mild cognitive impairment. In conclusion, our results indicate that some of the trajectory-based spatial parameters measured by LRS during the TUG test were independently associated with cognitive impairment in older adults. In particular, older adults with

  11. 7th International Workshop on Advanced Optical Imaging and Metrology

    CERN Document Server

    2014-01-01

    In continuation of the FRINGE Workshop Series this Proceeding contains all contributions presented at the 7. International Workshop on Advanced Optical Imaging and Metrology. The FRINGE Workshop Series is dedicated to the presentation, discussion and dissemination of recent results in Optical Imaging and Metrology. Topics of particular interest for the 7. Workshop are: - New methods and tools for the generation, acquisition, processing, and evaluation of data in Optical Imaging and Metrology (digital wavefront engineering, computational imaging, model-based reconstruction, compressed sensing, inverse problems solution) - Application-driven technologies in Optical Imaging and Metrology (high-resolution, adaptive, active, robust, reliable, flexible, in-line, real-time) - High-dynamic range solutions in Optical Imaging and Metrology (from macro to nano) - Hybrid technologies in Optical Imaging and Metrology (hybrid optics, sensor and data fusion, model-based solutions, multimodality) - New optical sensors, imagi...

  12. 75 FR 29775 - Food Labeling Workshop; Public Workshop

    Science.gov (United States)

    2010-05-27

    ... and startups. Date and Time: This public workshop will be held on August 4 and 5, 2010, from 8 a.m. to 5 p.m. Location: The public workshop will be held at the Continuing Education Center, 2 East Center St., Fayetteville, AR (located downtown). Contact: David Arvelo, Food and Drug...

  13. 75 FR 74736 - Food Labeling Workshop; Public Workshop

    Science.gov (United States)

    2010-12-01

    ... required due to disability, along with a check or money order for $250 payable to ``Iowa State University..., in collaboration with Iowa State University, is announcing a public workshop entitled ``Food Labeling... public workshop will be held at the Scheman Conference Center, Lincoln Way and University Avenue,...

  14. Laser & Fiber Optics: Instructional Manual. The North Dakota High Technology Mobile Laboratory Project.

    Science.gov (United States)

    Eickhoff, Luvern R.

    This instructional manual contains 20 learning activity packets for use in a workshop on lasers and fiber optics. The lessons cover the following topics: what a laser; coherent light; setting up the laser; characteristics of the laser beam; scattering of light; laser beam divergence, intensity, color, ophthalmology, and reflections; directivity of…

  15. Laser & Fiber Optics: Instructional Manual. The North Dakota High Technology Mobile Laboratory Project.

    Science.gov (United States)

    Eickhoff, Luvern R.

    This instructional manual contains 20 learning activity packets for use in a workshop on lasers and fiber optics. The lessons cover the following topics: what a laser; coherent light; setting up the laser; characteristics of the laser beam; scattering of light; laser beam divergence, intensity, color, ophthalmology, and reflections; directivity of…

  16. Holography demonstrations and workshops for science and engineering outreach

    Science.gov (United States)

    Thomas, Weston; Kruse, Kevin; Middlebrook, Christopher

    2012-10-01

    The SPIE/OSA Student Chapter at Michigan Technological University have developed demonstrations and workshops for science and engineering outreach. The practical approach to holography promotes the study of photonic related sciences in high school and college-aged students. An introduction to laser safety, optical laboratory practices, and basic laser coherence theory is given in order to first introduce the participants to the science behind the holograms. The students are then able to create a hologram of an item of their choice, personalizing the experience. By engaging directly, the students are able to see how the theory is applied and also enforces a higher level of attention from them so no mistakes are made in their hologram. Throughout the course participants gain an appreciation for photonics by learning how holograms operate and are constructed through hands on creation of their own holograms. This paper reviews the procedures and methods used in the demonstrations and workshop while examining the overall student experience.

  17. Laser propulsion: a review

    CSIR Research Space (South Africa)

    Michaelis, MM

    2006-07-01

    Full Text Available Ablation (HPLA) conferences, numbered I to VI, held in New Mexico, where laser propulsion is but one topic, under the auspices of the Society for Photographic Instrumentation Engineers (SPIE). There is also a specialist conference on beamed energy... route to space. 1. Myrabo L.N. (1987). Air-breathing laser propulsion for trans-atmospheric vehicles. In Proc. SDIO Workshop on Laser Propulsion, Los Alamos, New Mexico, ed. J.T. Kare, pp. 173–208. Los Alamos. 2. Phipps C.R., Luke J.R., McDuff G...

  18. Sixth national stakeholder workshop summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    On June 17--18, 1998, the Department of Energy`s (DOE) Office of Worker and Community Transition convened its sixth National Stakeholder Workshop at the Ramada Plaza Hotel Old Town in Alexandria, Virginia. Approximately 325 stakeholders attended representing DOE headquarters and field offices, contractors, labor organizations, state and local government, education and community interest groups. The meeting addressed the progress made on the issues and challenges identified at the last stakeholder`s meeting in Oakland, California on April 9--11, 1997. Also discussed were the full range of the Department`s work force issues and creative solutions to the inherent challenges of simultaneously implementing the Department`s post Cold-War mission, work force restructuring guidance, contract reform objectives, asset disposition, performance-based management requirements, and business process improvement policies. The format of the Workshop included several plenary sessions and a number of small group discussion sessions. The small group sessions focused on topics related to labor issues, work force restructuring, work force planning, community transition, and employee concerns. The sessions provided a wide range of views on worker and community transition issues. The plenary sessions of the Workshop included presentations on the following topics: welcome and introductions; opening remarks; building a better labor-management relationship; keynote speech from Secretary of Energy Federico Pena; meeting tomorrow`s challenges (early site closures); harnessing the contracting process to encourage local growth; and, the British experience in economic conversion.

  19. RFI Mitigation Workshop

    Science.gov (United States)

    2010-05-01

    The increased sensitivity of passive instrumentation in radio astronomy and remote sensing and the intensifying active use of the spectrum have led to an increasing level of radio frequency interference (RFI) of the active services on the passive use of the spectrum. Advances in technology and computing have opened up new possibilities for mitigating the effects of certain classes of interference in the observing data. Interference in allocated bands always leads to data loss for the passive users of the spectrum even if interference mitigation is applied. However, interference mitigation in non-allocated spectral bands may facilitate the partial use of this spectrum for passive (non-interfering) observations. There is no generic method to mitigate all types of interference, so a multi-layered system approach may be advisable to reduce detrimental effects for a congested interference environment. Specific mitigation methods implemented at different points in the data acquisition chain will thus result in a cumulative mitigation effect on the data. This third RFI Mitigation Workshop considered RFI mitigation in radio astronomy in all its facets with the aim of facilitating the implementation of instrumental and data processing techniques. This workshop aimed to take a forward look at applications for the next generation of radio instruments, such as the SKA and its pathfinders and LOFAR, as well as considering their application to existing instruments. This workshop has been organized by ASTRON and NAIC, with support from the Engineering Forum of FP7 RadioNet, the SKA Project Development Office, and in collaboration with CRAF and IUCAF.

  20. CENDI Indexing Workshop

    Science.gov (United States)

    1994-01-01

    The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

  1. Melioidosis Diagnostic Workshop, 20131

    Science.gov (United States)

    AuCoin, David; Baccam, Prasith; Baggett, Henry C.; Baird, Rob; Bhengsri, Saithip; Blaney, David D.; Brett, Paul J.; Brooks, Timothy J.G.; Brown, Katherine A.; Chantratita, Narisara; Cheng, Allen C.; Dance, David A.B.; Decuypere, Saskia; Defenbaugh, Dawn; Gee, Jay E.; Houghton, Raymond; Jorakate, Possawat; Lertmemongkolchai, Ganjana; Limmathurotsakul, Direk; Merlin, Toby L.; Mukhopadhyay, Chiranjay; Norton, Robert; Peacock, Sharon J.; Rolim, Dionne B.; Simpson, Andrew J.; Steinmetz, Ivo; Stoddard, Robyn A.; Stokes, Martha M.; Sue, David; Tuanyok, Apichai; Whistler, Toni; Wuthiekanun, Vanaporn; Walke, Henry T.

    2015-01-01

    Melioidosis is a severe disease that can be difficult to diagnose because of its diverse clinical manifestations and a lack of adequate diagnostic capabilities for suspected cases. There is broad interest in improving detection and diagnosis of this disease not only in melioidosis-endemic regions but also outside these regions because melioidosis may be underreported and poses a potential bioterrorism challenge for public health authorities. Therefore, a workshop of academic, government, and private sector personnel from around the world was convened to discuss the current state of melioidosis diagnostics, diagnostic needs, and future directions. PMID:25626057

  2. SIMS applications workshop. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The first ANSTO/AINSE SIMS Workshop drew together a mixture of Surface Analysis experts and Surface Analysis users with the concept that SIMS analysis has to be enfolded within the spectrum of surface analysis techniques and that the user should select the technique most applicable to the problem. With this concept in mind the program was structured as sessions on SIMS Facilities; Applications to Mineral Surfaces; Applications to Biological Systems, Applications to Surfaces as Semi- conductors, Catalysts and Surface Coatings; and Applications to Ceramics

  3. ROOT User Workshop 2013

    CERN Document Server

    2013-01-01

    Since almost two decades, ROOT has established itself as the framework for HENP data processing and analysis. The LHC upgrade program and the new experiments being designed at CERN and elsewhere will pose even more formidable challenges in terms of data complexity and size. The new parallel and heterogeneous computing architectures that are either announced or already available will call for a deep rethinking of the code and the data structures to be exploited efficiently. This workshop, following from a successful series of such events, will allow you to learn in detail about the new ROOT 6 and will help shape the future evolution of ROOT.

  4. 15th Cluster workshop

    CERN Document Server

    Laakso, Harri; Escoubet, C. Philippe; The Cluster Active Archive : Studying the Earth’s Space Plasma Environment

    2010-01-01

    Since the year 2000 the ESA Cluster mission has been investigating the small-scale structures and processes of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. This book contains presentations made at the 15th Cluster workshop held in March 2008. It also presents several articles about the Cluster Active Archive and its datasets, a few overview papers on the Cluster mission, and articles reporting on scientific findings on the solar wind, the magnetosheath, the magnetopause and the magnetotail.

  5. Biopower Technical Strategy Workshop Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2010-12-01

    Biopower is electricity produced from a wide range of biomass (organic materials found in wood, plants, agricultural waste and other materials). Biomass is a base load renewable energy source with high availability for electricity production. To explore opportunities for biopower in the United States, the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy Biomass Program conducted the Biopower Technical Strategy Workshop in Denver, Colorado, on December 2–3, 2009. This report summarizes the results of the workshop, which focused on challenges to the expanded use of biopower and the possible solutions, including technology research, development, and demonstration (RD&D) as well as policies and other market transformation mechanisms.

  6. 11th International Workshop on Railway Noise

    CERN Document Server

    Anderson, David; Gautier, Pierre-Etienne; Iida, Masanobu; Nelson, James; Thompson, David; Tielkes, Thorsten; Towers, David; Vos, Paul

    2015-01-01

    The book reports on the 11th International Workshop on Railway Noise, held on 9 – 13 September, 2013, in Uddevalla, Sweden. The event, which was jointly organized by the Competence Centre Chalmers Railway Mechanics (CHARMEC) and the Departments of Applied Mechanics and Applied Acoustics at Chalmers University of Technology in Gothenburg, Sweden, covered a broad range of topics in the field of railway noise and vibration, including: prospects, legal regulations and perceptions; wheel and rail noise; prediction, measurements and monitoring; ground-borne vibration; squeal noise and structure-borne noise; and aerodynamic noise generated by high-speed trains. Further topics included: resilient track forms; grinding, corrugation and roughness; and interior noise and sound barriers. This book, which consists of a collection of peer-reviewed papers originally submitted to the workshop, not only provides readers with an overview of the latest developments in the field, but also offers scientists and engineers essent...

  7. Workshop Polli Talu Loomingulises Keskuses

    Index Scriptorium Estoniae

    2004-01-01

    MAP Intermedia Performance Collaboration'i (USA) workshop. Brendan McCall (liikumine), N. B. Aldrich (heli) ja Zach Poff (video) workshop tutvustab kolme kunstniku koostööd. Näidatakse ka multimeedia etendust, mis on külaliskunstnikel valminud Polli talus

  8. A Portable Computer Security Workshop

    Science.gov (United States)

    Wagner, Paul J.; Phillips, Andrew T.

    2006-01-01

    We have developed a computer security workshop designed to instruct post-secondary instructors who want to start a course or laboratory exercise sequence in computer security. This workshop has also been used to provide computer security education to IT professionals and students. It is effective in communicating basic computer security principles…

  9. New technology integration planning workshop

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    Purpose of the Workshop was to provide guidance, reflecting electric utility industry viewpoints, for developing and directing its research and development program structures to facilitate the integration of new energy technologies into electric utility systems. The Workshop was structured to directly elicit the positions and viewpoints representative of electric utility companies.

  10. Hydrogen Technology Education Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-12-01

    This document outlines activities for educating key target audiences, as suggested by workshop participants. Held December 4-5, 2002, the Hydrogen Technology Education Workshop kicked off a new education effort coordinated by the Hydrogen, Fuel Cells, & Infrastructure Technologies Program of the Office of Energy Efficiency and Renewable Energy.

  11. Beta Cell Workshop 2013 Kyoto

    DEFF Research Database (Denmark)

    Heller, R Scott; Madsen, Ole D; Nielsen, Jens Høiriis

    2013-01-01

    The very modern Kyoto International Conference Center provided the site for the 8th workshop on Beta cells on April 23-26, 2013. The preceding workshops were held in Boston, USA (1991); Kyoto, Japan (1994); Helsingør, Denmark (1997); Helsinki, Finland (2003); El Perello, Spain (2006); Peebles...

  12. Workshop Polli Talu Loomingulises Keskuses

    Index Scriptorium Estoniae

    2004-01-01

    MAP Intermedia Performance Collaboration'i (USA) workshop. Brendan McCall (liikumine), N. B. Aldrich (heli) ja Zach Poff (video) workshop tutvustab kolme kunstniku koostööd. Näidatakse ka multimeedia etendust, mis on külaliskunstnikel valminud Polli talus

  13. Presentation Skills Workshops for Nurses.

    Science.gov (United States)

    Kinn, S.; Kenyon, M.

    2002-01-01

    Workshops were held to prepare nurses (n=87) to present results of professional activities. One year after the course, 20 had made oral and 30 written presentations. The workshops increased their confidence and were considered practical, informal, and nonthreatening. (Contains 31 references.) (SK)

  14. Marketing Cooperative Education. A Workshop.

    Science.gov (United States)

    Mosser, John W.; Rea, Peter J.

    This document is a guide for a workshop on marketing college cooperative education programs. The guide takes the reader/workshop participant through the marketing process, from defining needs and resources to planning a marketing campaign, implementing it, and evaluating its success. Samples and sources also are provided. Topics covered in the…

  15. NATO Advanced Research Workshop on Applications of Picosecond Spectroscopy to Chemistry

    CERN Document Server

    1984-01-01

    With the development of lasers that can generate light 11 14 pulses ranging from 10- - 10- sec duration, and capable of 13 peak powers in excess of 10 watts scientists have been able to investigate the interactions of light with matter in a time and power domain not previously possible. These ultrashort laser pulses provide a powerful tool for the study of chemical phenomena at the most fundamental level. Many of the elementary processes of importance in chemistry including energy dissipa­ tion, molecular motions, structural and chemical changes occur on a very short time scale and thus require special approaches. Th~ use of ultrashort laser pulses to perturb and to probe systems of interest affords a direct approach to the time reso­ lution of very rapid chemical phenomena. It was recognition of the impact of these relatively new approaches to chemical phenomena that motivated NATO to sponsor a meeting on the applications of picosecond spectroscopy in chemistry. The primary aim of the NATO workshop was to ...

  16. Formation of a fine-dispersed liquid-metal target under the action of femto- and picosecond laser pulses for a laser-plasma radiation source in the extreme ultraviolet range

    Energy Technology Data Exchange (ETDEWEB)

    Vinokhodov, A Yu; Krivokorytov, M S [EUV Labs, Ltd., Troitsk, Moscow (Russian Federation); Koshelev, K N; Krivtsun, V M; Sidelnikov, Yu V; Medvedev, V V; Kompanets, V O; Melnikov, A A; Chekalin, S V [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow (Russian Federation)

    2016-01-31

    We report the results of studying the dynamics of deformation and fragmentation of liquid-metal droplets under the action of ultrashort laser pulses. The experiments have been performed to optimise the shape of the droplet target used in extreme ultraviolet (EUV) radiation sources based on the laser-produced plasma using the pre-pulse technology. The pre-pulse is generated by a system incorporating a master Ti : sapphire oscillator and a regenerative amplifier, allowing one to vary the pulse duration from 50 fs to 50 ps. The power density of laser radiation at the droplet target, averaged over the pulse duration and spatial coordinates, has reached 3 × 10{sup 15} W cm{sup -2}. The production of liquid-metal droplets has been implemented by means of a droplet generator based on a nozzle with a ring piezoceramic actuator. The droplet material is the eutectic indium – tin alloy. The droplet generator could operate in the droplet and jet regime with a maximal rate of stable operation 5 and 150 kHz, respectively. The spatial stability of droplet position σ = 1% – 2% of its diameter is achieved. The size of the droplets varied within 30 – 70 μm, their velocity was 2 – 8 m s{sup -1} depending on the operation regime. (interaction of laser radiation with matter. laser plasma)

  17. First JECSS Workshop

    Science.gov (United States)

    Ichiye, Takashi

    The first Japan and East China Seas Study (JECSS) workshop convened at Tsukuba University, about 60 km north of Tokyo, Japan, June 1-4, 1981, to assess hydrographic data, review descriptive and theoretical Work, and promote future cooperation for studying the Japan Sea and East China Sea and marginal seas of the Western North Pacific Ocean. The conveners were Takashi Ichiye of Texas A&M University and Kenzo Takano of Tsukuba University, and the workshop was funded by the Hidaka Foundation, which was founded by Koji Hidaka, patriarch of dynamic oceanography in Japan.There were 41 participants: seven from the United States, six from Korea, one from the Peoples Republic of China, and 27 from Japan. Twenty-four papers were presented, and topics included the Japan Sea, the East China Sea, and marginal seas in general. Subjects concerned descriptive physical oceanography; internal waves, tides, and shelf waves; circulation modeling; data assessment; remote sensing; and sedimentology and marine chemistry. The seasonal change of the Tsushima Current, a branch of the Kuroshio in the Japan Sea, was determined by the Tohoku University group; preliminary results of the NOAA R/V Oceanographer cruise in Spring 1980 were presented; and the numerical modeling of the Japan Sea circulation, the tides of the Yellow Sea, and the barotropic current of the East China Sea were discussed. The papers presented will be published in 1982 in La Mer, a journal of the Japanese-French Oceanographical Society.

  18. GammaWorkshops Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Ramebaeck, H. (ed.) (Swedish Defence Research Agency (Sweden)); Straalberg, E. (Institute for Energy Technology, Kjeller (Norway)); Klemola, S. (Radiation and Nuclear Safety Authority, STUK (Finland)); Nielsen, Sven P. (Technical Univ. of Denmark. Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Palsson, S.E. (Icelandic Radiation Safety Authority (Iceland))

    2012-01-15

    Due to a sparse interaction during the last years between practioners in gamma ray spectrometry in the Nordic countries, a NKS activity was started in 2009. This GammaSem was focused on seminars relevant to gamma spectrometry. A follow up seminar was held in 2010. As an outcome of these activities it was suggested that the 2011 meeting should be focused on practical issues, e.g. different corrections needed in gamma spectrometric measurements. This three day's meeting, GammaWorkshops, was held in September at Risoe-DTU. Experts on different topics relevant for gamma spectrometric measurements were invited to the GammaWorkshops. The topics included efficiency transfer, true coincidence summing corrections, self-attenuation corrections, measurement of natural radionuclides (natural decay series), combined measurement uncertainty calculations, and detection limits. These topics covered both lectures and practical sessions. The practical sessions included demonstrations of tools for e.g. corrections and calculations of the above meantioned topics. (Author)

  19. Varenna workshop report. Operational earthquake forecasting and decision making

    Directory of Open Access Journals (Sweden)

    Warner Marzocchi

    2015-09-01

    Full Text Available A workshop on Operational earthquake forecasting and decision making was convened in Varenna, Italy, on June 8-11, 2014, under the sponsorship of the EU FP 7 REAKT (Strategies and tools for Real-time EArthquake risK reducTion project, the Seismic Hazard Center at the Istituto Nazionale di Geofisica e Vulcanologia (INGV, and the Southern California Earthquake Center (SCEC. The main goal was to survey the interdisciplinary issues of operational earthquake forecasting (OEF, including the problems that OEF raises for decision making and risk communication. The workshop was attended by 64 researchers from universities, research centers, and governmental institutions in 11 countries. Participants and the workshop agenda are listed in the appendix.The workshop comprised six topical sessions structured around three main themes: the science of operational earthquake forecasting, decision making in a low-probability environment, and communicating hazard and risk. Each topic was introduced by a moderator and surveyed by a few invited speakers, who were then empaneled for an open discussion. The presentations were followed by poster sessions. During a wrap-up session on the last day, the reporters for each topical session summarized the main points that they had gleaned from the talks and open discussions. This report attempts to distill this workshop record into a brief overview of the workshop themes and to describe the range of opinions expressed during the discussions.

  20. Experimental demonstration of change of dynamical properties of a passively mode-locked semiconductor laser subject to dual optical feedback by dual full delay-range tuning.

    Science.gov (United States)

    Nikiforov, O; Jaurigue, L; Drzewietzki, L; Lüdge, K; Breuer, S

    2016-06-27

    In this contribution we experimentally demonstrate the change and improvement of dynamical properties of a passively mode-locked semiconductor laser subject to optical feedback from two external cavities by coupling the feedback pulses back into the gain segment. Hereby, we tune the full delay-phase of the pulse-to-pulse period of both external cavities separately and demonstrate the change of the repetition rate, timing jitter, multi-pulse formation and side-band suppression for the first time for such a dual feedback configuration. In addition, we thereby confirm modeling predictions by achieving both a good qualitative and quantitative agreement of experimental and simulated results. Our findings suggest a path towards the realization of side-band free all-optical photonic oscillators based on mode-locked lasers.