WorldWideScience

Sample records for fast offset laser

  1. Fast Offset Laser Phase-Locking System

    Science.gov (United States)

    Shaddock, Daniel; Ware, Brent

    2008-01-01

    Figure 1 shows a simplified block diagram of an improved optoelectronic system for locking the phase of one laser to that of another laser with an adjustable offset frequency specified by the user. In comparison with prior systems, this system exhibits higher performance (including higher stability) and is much easier to use. The system is based on a field-programmable gate array (FPGA) and operates almost entirely digitally; hence, it is easily adaptable to many different systems. The system achieves phase stability of less than a microcycle. It was developed to satisfy the phase-stability requirement for a planned spaceborne gravitational-wave-detecting heterodyne laser interferometer (LISA). The system has potential terrestrial utility in communications, lidar, and other applications. The present system includes a fast phasemeter that is a companion to the microcycle-accurate one described in High-Accuracy, High-Dynamic-Range Phase-Measurement System (NPO-41927), NASA Tech Briefs, Vol. 31, No. 6 (June 2007), page 22. In the present system (as in the previously reported one), beams from the two lasers (here denoted the master and slave lasers) interfere on a photodiode. The heterodyne photodiode output is digitized and fed to the fast phasemeter, which produces suitably conditioned, low-latency analog control signals which lock the phase of the slave laser to that of the master laser. These control signals are used to drive a thermal and a piezoelectric transducer that adjust the frequency and phase of the slave-laser output. The output of the photodiode is a heterodyne signal at the difference between the frequencies of the two lasers. (The difference is currently required to be less than 20 MHz due to the Nyquist limit of the current sampling rate. We foresee few problems in doubling this limit using current equipment.) Within the phasemeter, the photodiode-output signal is digitized to 15 bits at a sampling frequency of 40 MHz by use of the same analog

  2. Precision and Fast Wavelength Tuning of a Dynamically Phase-Locked Widely-Tunable Laser

    Science.gov (United States)

    Numata, Kenji; Chen, Jeffrey R.; Wu, Stewart T.

    2012-01-01

    We report a precision and fast wavelength tuning technique demonstrated for a digital-supermode distributed Bragg reflector laser. The laser was dynamically offset-locked to a frequency-stabilized master laser using an optical phase-locked loop, enabling precision fast tuning to and from any frequencies within a 40-GHz tuning range. The offset frequency noise was suppressed to the statically offset-locked level in less than 40 s upon each frequency switch, allowing the laser to retain the absolute frequency stability of the master laser. This technique satisfies stringent requirements for gas sensing lidars and enables other applications that require such well-controlled precision fast tuning.

  3. Crack Offset Measurement With the Projected Laser Target Device

    Science.gov (United States)

    2008-01-01

    The device and associated analysis methodology summarized in this report were developed for the purpose of estimating the size of discontinuities in the surface of the foam that covers the Space Shuttle External Tank. These surface offsets are thought to be due to subsurface cracks in the foam insulation. The mathematical analysis and procedure described here provide a method to quantity the dimensions of the crack offset in a direction perpendicular to the surface, making use of the projected laser target device (PLTD) tool and a laser line projector. The keys to the construction and use of the PLTD are the following geometrical design requirements: Laser dots are on a square grid: length on a side. Laser beams are perpendicular to projected surface. Beams are parallel out to the distance being projected. The PLTD can be used to (1) calibrate fixed cameras of unknown magnification and orientation (far-field solution); (2) provide equivalent calibration to multiple cameras, previously achieved only by the use of known target points, for example, in 3.D foreign-object debris tracking on a fixed launch platform; (3) compute scaling for conventional 2.D images, and depth of field for 3.D images (near-field solution); and (4) in conjunction with a laser line projector, achieve accurate measurements of surface discontinuity (cracks) in a direction perpendicular to the surface.

  4. Fast Frequency Offset Acquisition and Accurate Tracking in OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong-shan; ZHAO Ming; LIU Yuan-an

    2004-01-01

    A new carrier frequency offset estimation scheme for Orthogonal Frequency-Division Multiplexing (OFDM) systems is proposed. The carrier frequency offset estimation includes acquisition and tracking. The acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth. Comparison of the proposed scheme with Schmidl's algorithm by computer simulation illustrates the superior performance of the proposed scheme with regard to estimation accuracy in both AWGN channel and multipath channels.

  5. ROBUST AND FAST FREQUENCY OFFSET ESTIMATION FOR OFDM BASED SATELLITE COMMUNICATION

    Institute of Scientific and Technical Information of China (English)

    Wei Li; Xu Youyun; Cai Yueming

    2009-01-01

    A pilot-aided Orthogonal Frequency Division Multiplexing (OFDM) frequency offset estimator designed for satellite communication system is proposed in the paper. The estimator focuses on the acquisition of the integer part of carrier frequency offset and the acquisition range is as large as the whole signal bandwidth. Making full use of the phase difference between received pilot and local referential pilot, a fast estimation is obtained. Compared with existing method, our method can also work well even in SNR as low as 0dB. Simulations verify the good performance of our method.

  6. Laser frequency offset locking scheme for high-field imaging of cold atoms

    CERN Document Server

    Puentes, Graciana

    2011-01-01

    We present a simple and flexible frequency offset locking scheme developed for high-field imaging of ultra-cold atoms which relies on commercially available RF electronics only. The main new ingredient is the use of the sharp amplitude response of a home-made RF filter to provide an error signal for locking the lasers. We were able to offset lock two independent diode lasers within a capture range of 200 MHz, and with a tuning range of up to 1.4GHz. The beat-note residual fluctuations for offset locked lasers are bellow 2MHz for integration times of several hundreds of seconds.

  7. THE EFFECT OF OFFSET PRINTING INK ON LASER TONER INK AGGLOMERATION UNDER NEUTRAL PULPING CONDITIONS

    Directory of Open Access Journals (Sweden)

    Sujin Xie,

    2012-05-01

    Full Text Available 1-octadecanol is known to be a highly effective agglomerating agent for laser toner ink. However, the office waste paper used in the actual production often contains various types of inks. The effect of the offset ink and types of surfactants with different charge characteristics were studied relative to the agglomeration of the laser toner ink under neutral pulping conditions. It was found that the addition of a small amount of the offset ink printed waste paper was beneficial for the agglomeration of the laser toner ink. The optimal percentage of addition is 12.5% to 25%. The offset printed ink had a positive charge of 0.001±0.0005 mEq/g when the offset ink was treated by 70˚C water at neutral conditions. Addition of a proper amount of cationic surfactant was beneficial to improve the agglomeration at any ratio of the mixed laser printed and offset waste papers. When the percentage of offset waste paper was less than 50%, the addition of anionic surfactant and nonionic surfactant was harmful for agglomeration, and there was no significant effect at higher offset content.

  8. Offset quantum-well method for tunable distributed Bragg reflector lasers and electro-absorption modulated distributed feedback lasers

    Institute of Scientific and Technical Information of China (English)

    Qiang Kan; Ying Ding; Lingjuan Zhao; Hongliang Zhu; Fan Zhou; Lufeng Wang; Baojun Wang; Wei Wang

    2005-01-01

    @@ A two-section offset quantum-well structure tunable laser with a tuning range of 7 nm was fabricated using offset quantum-well method. The distributed Bragg reflector (DBR) was realized just by selectively wet etching the multiquantum-well (MQW) layer above the quaternary lower waveguide. A threshold current of 32 mA and an output power of 9 mW at 100 mA were achieved. Furthermore, with this offset structure method, a distributed feedback (DFB) laser was integrated with an electro-absorption modulator (EAM),which was capable of producing 20 dB of optical extinction.

  9. Ultra-fast laser system

    Science.gov (United States)

    Dantus, Marcos; Lozovoy, Vadim V

    2014-01-21

    A laser system is provided which selectively excites Raman active vibrations in molecules. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and remote sensing.

  10. Robust frequency stabilization of multiple spectroscopy lasers with large and tunable offset frequencies.

    Science.gov (United States)

    Nevsky, A; Alighanbari, S; Chen, Q-F; Ernsting, I; Vasilyev, S; Schiller, S; Barwood, G; Gill, P; Poli, N; Tino, G M

    2013-11-15

    We have demonstrated a compact, robust device for simultaneous absolute frequency stabilization of three diode lasers whose carrier frequencies can be chosen freely relative to the reference. A rigid ULE multicavity block is employed, and, for each laser, the sideband locking technique is applied. A small lock error, computer control of frequency offset, wide range of frequency offset, simple construction, and robust operation are the useful features of the system. One concrete application is as a stabilization unit for the cooling and trapping lasers of a neutral-atom lattice clock. The device significantly supports and improves the clock's operation. The laser with the most stringent requirements imposed by this application is stabilized to a line width of 70 Hz, and a residual frequency drift less than 0.5 Hz/s. The carrier optical frequency can be tuned over 350 MHz while in lock.

  11. Laser-plasma interactions for fast ignition

    CERN Document Server

    Kemp, A J; Debayle, A; Johzaki, T; Mori, W B; Patel, P K; Sentoku, Y; Silva, L O

    2013-01-01

    In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the compa...

  12. Laser frequency offset locking via tripod-type electromagnetically induced transparency

    CERN Document Server

    Ying, Kang; Chen, Dijun; Cai, Haiwen; Qu, Ronghui; Gong, Shangqing

    2014-01-01

    We have demonstrated the laser frequency offset locking via the Rb tripod-type double dark resonances electromagnetically induced transparency (EIT) system. The influence of coupling fields power and detuning on the tripod-type EIT profile is detailed studied. In a wide coupling fields detuning range, the narrower EIT dip has an ultranarrow linewidth of 590 KHz, which is about one order narrower than the natural linewidth of Rb. Without the additional frequency stabilization of the coupling lasers, we achieve the relative frequency fluctuation of 60 KHz in a long time of ~2000s, which is narrower than the short-time linewidth of each individual laser.

  13. Effects of laser intensity on the emission direction of fast electrons in laser-solid interactions

    Institute of Scientific and Technical Information of China (English)

    张军; 张杰; 邱阳; 盛政明; 李玉同; 金展; 滕浩

    2003-01-01

    The dependence of emission direction of fast electrons on the laser intensity has been investigated. The experimental results show that, at nonrelativistic laser intensities, the emission of fast electrons is mainly in the polarization plane. With the increase of the laser intensity, fast electrons emit towards the laser propagation direction from laser polarization direction. At relativistic laser intensities, fast electrons move away from the laser polarization plane, closely to the reflection direction of the incident laser beam.

  14. 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.

  15. Fast ion extraction in laser isotope separation

    Energy Technology Data Exchange (ETDEWEB)

    Hazak, G.; Gell, Y.; Boneh, Y.; Goshen, S.

    1980-10-01

    An analysis of the E x B scheme for fast ion extraction in laser isotope separation is presented. Using an analytically solvable model and a numerical simulation we have found that the scheme can meet the rather severe time and space restrictions imposed by the large cross section for charge exchange.

  16. Characteristics and performance of offset phase locked single frequency heterodyned laser systems

    Science.gov (United States)

    Tulchinsky, David A.; Hastings, Alexander S.; Williams, Keith J.

    2016-05-01

    We demonstrate and characterize the performance of two heterodyned optical phase locked loop (PLL) laser systems for use in characterizing photodetector RF frequency response and nonlinearities. Descriptions of PLL circuit parameters for Nd:YAG non-planar ring oscillator lasers at 1064 nm and 1319 nm, and Er ion fiber lasers from 1530 nm to 1565 nm are presented. Both laser systems have piezoelectric transducer wavelength control over the PLL voltage controlled oscillator circuit. Offset frequency phase locking from 1.5 kHz to 51+ GHz is demonstrated. Frequency stability at 10 MHz is measured to be ±50 μHz, limited by the stability of the Rb stabilized crystal oscillator. Phase noise of the phase-locked 1319 nm laser system is discussed where we find that the phase noise is dominated by the input source noise at frequency offsets below 100 Hz and by the laser's RIN noise at frequency offsets > 100 Hz. Comparing nonlinearity data from an InGaAs p-i-n photodiode using both 1319 nm and 1550 nm PLL nonlinearity measurement systems, we find two new separate photodetector nonlinearity mechanisms. Measurements of the harmonic components of a 11 MHz sinusoidal heterodyned optical beat note signal are found to be at or below 1 nW/mW for the second harmonic (at 22 MHz) and at or below 0.25 nW/mW for the 3rd harmonic (at 33 MHz), confirming the nearly pure sinusoidal nature of the optically generated microwave beat note.

  17. Laser Trimming for Adjustment of Grating Offset in Phase-Shifted Fiber Grating Coupler for All-Optical Switching Application

    Institute of Scientific and Technical Information of China (English)

    Hirohisa; Yokota; Yutaka; Sasaki

    2003-01-01

    We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.

  18. Offsets in fiber-coupled diode laser hygrometers caused by parasitic absorption effects and their prevention

    Science.gov (United States)

    Buchholz, B.; Ebert, V.

    2014-07-01

    Large systematic errors in absorption spectrometers (AS) can be caused by ‘parasitic’ optical absorption (parA) outside the measurement region. In particular, calibration-free direct tunable diode laser AS (dTDLAS) can take advantage of an effective parA-compensation to provide correct absolute values. However, parA also negatively affects calibrated AS in calibration frequency and stability. A common strategy to suppress parA in TDLAS systems is to fiber-couple the light source and even the detector. However, this can be a critical approach if the TDL spectrometer is validated/calibrated under laboratory conditions in ambient humidity and used afterwards in much drier and variable conditions, for example in aircrafts. This paper shows that, e.g., ‘hermetically sealed’ butterfly packages, despite fiber coupling, can possess fixed as well as variable parA sections. Two new methods for absolute parA-quantification in dTDLAS were developed, including a novel, fiber-coupled, parA-free I0-detector for permanent parA-monitoring. Their dependences on ambient humidity/pressure and temporal behavior were studied. For the example of a 1.4 µm dTDLAS hygrometer SEALDH-II with a commercial DFB-laser module and an extractive 1.5 m path cell, we quantified the parA-induced signal offsets and their dependence on cell pressure. The conversion of parA-uncertainty into H2O signal uncertainty was studied and an updated uncertainty budget including parA-uncertainty was derived. The studies showed that parA in commercial laser modules can cause substantial, systematic concentration offsets of ≈25 ppmv fixed and ≈100 ppmv variable offsets for one meter absorption path. Applying our parA-quantification techniques these offsets could be compensated by a factor of 20 to an overall offset uncertainty of 4.5 ppmv m-1. Finally, we developed an innovative, integrated, µ-pumped closed-loop air drying unit for the parA minimization and temporal stabilization in airborne laser

  19. Carrier-Envelope Offset Stabilized Ultrafast Diode-Pumped Solid-State Lasers

    Directory of Open Access Journals (Sweden)

    Stéphane Schilt

    2015-10-01

    Full Text Available Optical frequency combs have been revolutionizing many research areas and are finding a growing number of real-world applications. While initially dominated by Ti:Sapphire and fiber lasers, optical frequency combs from modelocked diode-pumped solid-state lasers (DPSSLs have become an attractive alternative with state-of-the-art performance. In this article, we review the main achievements in ultrafast DPSSLs for frequency combs. We present the current status of carrier-envelope offset (CEO frequency-stabilized DPSSLs based on various approaches and operating in different wavelength regimes. Feedback to the pump current provides a reliable scheme for frequency comb CEO stabilization, but also other methods with faster feedback not limited by the lifetime of the gain material have been applied. Pumping DPSSLs with high power multi-transverse-mode diodes enabled a new class of high power oscillators and gigahertz repetition rate lasers, which were initially not believed to be suitable for CEO stabilization due to the pump noise. However, this challenge has been overcome, and recently both high power and gigahertz DPSSL combs have been demonstrated. Thin disk lasers have demonstrated the highest pulse energy and average power emitted from any ultrafast oscillator and present a high potential for the future generation of stabilized frequency combs with hundreds of watts average output power.

  20. Offset phase locking of noisy diode lasers aided by frequency division

    Science.gov (United States)

    Ivanov, E. N.; Esnault, F.-X.; Donley, E. A.

    2011-08-01

    For heterodyne phase locking, frequency division of the beat note between two oscillators can improve the reliability of the phase lock and the quality of the phase synchronization. Frequency division can also reduce the size, weight, power, and cost of the instrument by excluding the microwave synthesizer from the control loop when the heterodyne offset frequency is large (5 to 10 GHz). We have experimentally tested the use of a frequency divider in an optical phase-lock loop and compared the achieved level of residual phase fluctuations between two diode lasers with that achieved without the use of a frequency divider. The two methods achieve comparable phase stability provided that sufficient loop gain is maintained after frequency division to preserve the required bandwidth. We have also numerically analyzed the noise properties and internal dynamics of phase-locked loops subjected to a high level of phase fluctuations, and our modeling confirms the expected benefits of having an in-loop frequency divider.

  1. Liquid level sensor based on fiber ring laser with single-mode-offset coreless-single-mode fiber structure

    Science.gov (United States)

    Wang, Zixiao; Tan, Zhongwei; Xing, Rui; Liang, Linjun; Qi, Yanhui; Jian, Shuisheng

    2016-10-01

    A novel reflective liquid level sensor based on single-mode-offset coreless-single-mode (SOCS) fiber structure is proposed and experimentally demonstrated. Theory analyses and experimental results indicate that offset fusion can remarkably enhance the sensitivity of sensor. Ending-reflecting structure makes the sensor compact and easy to deploy. Meanwhile, we propose a laser sensing system, and the SOCS structure is used as sensing head and laser filter simultaneously. Experimental results show that laser spectra with high optical signal-to-noise ratio (-30 dB) and narrow 3-dB bandwidth (<0.15 nm) are achieved. Various liquids with different indices are used for liquid level sensing, besides, the refractive index sensitivity is also investigated. In measurement range, the sensing system presents steady laser output.

  2. DURIP: Fast Oscilloscope and Detectors for Air Laser Research

    Science.gov (United States)

    2015-01-01

    Approved for public release; distribution is unlimited.       DURIP: Fast Oscilloscope and Detectors for Air Laser Research Office of...1. Type of equipment The equipment purchased under this DURIP provides the capability to detect in real time events on very fast time scales, as...low as 10 picoseconds. Fast real-time oscilloscopes and fast detectors were needed for this purpose. 2. Manufacturer of equipment and model number

  3. Impact of Fast Ignition on Laser Fusion Energy Development

    Science.gov (United States)

    Mirna, Kunioki

    2016-10-01

    Reviewed are the early history of Japanese laser fusion research and the recent achievement of fast ignition research at Institute of Laser Engineering (ILE), Osaka University. After the achievement of high density compression at Osaka University, LLE of University Rochester, and LLNL, the critical issue of Inertial Fusion Energy (IFE) research became the formation of hot spark in a compressed plasma. In this lecture, the history of the fast ignition research will be reviewed and future prospects are presented.

  4. Reduction of the Residual Porosity in Parts Manufactured by Selective Laser Melting Using Skywriting and High Focus Offset Strategies

    Science.gov (United States)

    Mancisidor, A. M.; Garciandia, F.; Sebastian, M. San; Álvarez, P.; Díaz, J.; Unanue, I.

    Residual porosity is observed in Inconel 718 samples manufactured by SLM within the optimum process window regardless the process parameters whose origin has been directly related to the starting and finishing of the laser scanning tracks. This porosity is concentrated preferentially in overlaps of fields (stripes and chessboard strategies) and borders. Location of pores has been demonstrated on long stripes, where laser stops only at borders, not in the hatch. It has been concluded that porosity is due to a high interaction time of the laser with powder which increases the energy in those points. Two different strategies have been validated to reduce this effect and thus diminish porosity. These strategies are the skywriting function, where the laser is switched off during the accelerating and decelerating portions and to increase the focus offset. The defocusing strategy is not as effective as the skywriting reducing the residual porosity.

  5. Patterning of OPV modules by ultra-fast laser

    Science.gov (United States)

    Kubiš, Peter; Lucera, Luca; Guo, Fei; Spyropolous, George; Voigt, Monika M.; Brabec, Christoph J.

    2014-10-01

    A novel production process combining slot-die coating, transparent flexible IMI (ITO-Metal-ITO) electrodes and ultra-fast laser ablation can be used for the realization of P3HT:PCBM based thin film flexible OPV modules. The fast and precise laser ablation allows an overall efficiency over 3 % and a device geometric fill factor (GFF) over 95 %. Three functional layers can be ablated using the same wavelength only with varying the laser fluence and overlap. Different OPV device architectures with multilayers utilizing various materials are challenging for ablation but can be structured by using a systematical approach.

  6. Fast magnetic reconnection in laser-produced plasma bubbles

    OpenAIRE

    Fox, W.; Bhattacharjee, A.; Germaschewski, K.

    2011-01-01

    Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles, with reconnection rates observed to be much higher than can be explained by classical theory. Based on fully kinetic particle simulations we find that fast reconnection in these strongly driven systems can be explained by magnetic flux pile-up at the shoulder of the current sheet and subsequent fast reconnection via two-fluid, collisionless mechanisms. In the strong drive regime with ...

  7. Fast photography of plasma formed by laser ablation of aluminum

    Science.gov (United States)

    Nedanovska, E.; Ivkovic, M.

    2008-07-01

    In this paper we present results of the temporal and spatial analysis of laser induced plasma performed by use of ICCD fast photography. The plasma is formed by excimer laser ablation of aluminum target in vacuum, air or different pressures of argon and helium. It is shown how the plasma luminous intensity and duration depends on gas pressure. The obtained time dependence of wave propagation distance is also compared with predictions given by the blast wave and drag-force theory also.

  8. Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets

    Science.gov (United States)

    Jarrott, L. C.; Wei, M. S.; McGuffey, C.; Solodov, A. A.; Theobald, W.; Qiao, B.; Stoeckl, C.; Betti, R.; Chen, H.; Delettrez, J.; Döppner, T.; Giraldez, E. M.; Glebov, V. Y.; Habara, H.; Iwawaki, T.; Key, M. H.; Luo, R. W.; Marshall, F. J.; McLean, H. S.; Mileham, C.; Patel, P. K.; Santos, J. J.; Sawada, H.; Stephens, R. B.; Yabuuchi, T.; Beg, F. N.

    2016-05-01

    Recent progress in kilojoule-scale high-intensity lasers has opened up new areas of research in radiography, laboratory astrophysics, high-energy-density physics, and fast-ignition (FI) laser fusion. FI requires efficient heating of pre-compressed high-density fuel by an intense relativistic electron beam produced from laser-matter interaction. Understanding the details of electron beam generation and transport is crucial for FI. Here we report on the first visualization of fast electron spatial energy deposition in a laser-compressed cone-in-shell FI target, facilitated by doping the shell with copper and imaging the K-shell radiation. Multi-scale simulations accompanying the experiments clearly show the location of fast electrons and reveal key parameters affecting energy coupling. The approach provides a more direct way to infer energy coupling and guide experimental designs that significantly improve the laser-to-core coupling to 7%. Our findings lay the groundwork for further improving efficiency, with 15% energy coupling predicted in FI experiments using an existing megajoule-scale laser driver.

  9. Fast Tunable Wavelength Sources Based on the Laser Diode Array

    Institute of Scientific and Technical Information of China (English)

    Sung-Chan; Cho; Hyun; Ha; Hong; Byoung-Whi; Kim

    2003-01-01

    We report a demonstration of a fast wavelength tunable source (TWS) based on the laser diode array coupled to the arrayed waveguide grating (AWG) multiplexer. The switching and optical characteristics of TWS make it a candidate for implementing the wavelength-division space switch fabric for an optical packet/burst switching.

  10. Effect of laser beam offset on microstructure and mechanical properties of pulsed laser welded BTi-6431S/TA15 dissimilar titanium alloys

    Science.gov (United States)

    Zhang, Hao; Hu, Shengsun; Shen, Junqi; Li, Dalong; Bu, Xianzheng

    2015-11-01

    Laser beam welding was used to weld dissimilar joints in BTi-6431S/TA15 titanium alloys. The effect of laser beam offset on microstructural characterizations and mechanical properties of the joints were investigated. Microstructural evolution of the joints was characterized by optical microscopy (OM) and X-ray diffraction (XRD). Tensile testing was conducted at room temperature and at 550 °C. The results demonstrated that with the exception of some porosity, a good quality joint could be achieved. Martensite α' and acicular α structures were present in the fusion zone (FZ). The amount of martensite α' present with the -0.2 mm beam offset was less than that with the 0.2 mm beam offset. Acicular α and martensite α' transformations occurred in the high temperature heat-affected zone (HT-HAZ) of both the BTi-6431S and TA15 alloys. In the low-temperature heat-affected zone (LT-HAZ), the BTi-6431S and TA15 alloy microstructures exhibited a mixture of secondary α, primary α, and prior β phases. The microhardness values in the FZ followed the order: -0.2 mm> 0 mm> 0.2 mm. Tensile testing at room temperature and at 550 °C resulted in fracture of the TA15 alloy base metal. The fracture morphology exhibited a ductile dimple feature.

  11. Fast magnetic reconnection in laser-produced plasma bubbles.

    Science.gov (United States)

    Fox, W; Bhattacharjee, A; Germaschewski, K

    2011-05-27

    Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles, with reconnection rates observed to be much higher than can be explained by classical theory. Based on fully kinetic particle simulations we find that fast reconnection in these strongly driven systems can be explained by magnetic flux pileup at the shoulder of the current sheet and subsequent fast reconnection via two-fluid, collisionless mechanisms. In the strong drive regime with two-fluid effects, we find that the ultimate reconnection time is insensitive to the nominal system Alfvén time.

  12. Laser ablation initiated fast discharge for spectrochemical applications

    Directory of Open Access Journals (Sweden)

    Vinić Milica L.

    2014-01-01

    Full Text Available The results of an experimental study of the optical emission enhancement possibilities during the single pulse laser induced breakdown spectroscopy of the aluminum alloy are presented. This study is performed in air, argon and helium at different pressures with and without the additional fast electric discharge. The discharge was initiated by plasma plume created by laser ablation of target. The influences of various capacitors and discharge voltages on enhancement of the studied spectral line intensities were also studied. The application of the fast discharge through optical emission enhancement enables lowering of detection limits thus making this spectrochemical method comparable with the other analytical techniques. [Projekat Ministarstva nauke Republike Srbije, br. 171014

  13. The use of airborne laser scanning to develop a pixel-based stratification for a verified carbon offset project

    Science.gov (United States)

    2011-01-01

    Background The voluntary carbon market is a new and growing market that is increasingly important to consider in managing forestland. Monitoring, reporting, and verifying carbon stocks and fluxes at a project level is the single largest direct cost of a forest carbon offset project. There are now many methods for estimating forest stocks with high accuracy that use both Airborne Laser Scanning (ALS) and high-resolution optical remote sensing data. However, many of these methods are not appropriate for use under existing carbon offset standards and most have not been field tested. Results This paper presents a pixel-based forest stratification method that uses both ALS and optical remote sensing data to optimally partition the variability across an ~10,000 ha forest ownership in Mendocino County, CA, USA. This new stratification approach improved the accuracy of the forest inventory, reduced the cost of field-based inventory, and provides a powerful tool for future management planning. This approach also details a method of determining the optimum pixel size to best partition a forest. Conclusions The use of ALS and optical remote sensing data can help reduce the cost of field inventory and can help to locate areas that need the most intensive inventory effort. This pixel-based stratification method may provide a cost-effective approach to reducing inventory costs over larger areas when the remote sensing data acquisition costs can be kept low on a per acre basis. PMID:22004847

  14. Frequency-Stable Offset-Locked Lasers for ASCENDS and 3D Winds Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the potential to develop significant improvements to size, weight, and prime power requirements of front-end cw lasers and associated frequency...

  15. Longitudinal dynamics of laser-cooled fast ion beams

    DEFF Research Database (Denmark)

    Weidemüller, M.; Eike, B.; Eisenbarth, U.

    1999-01-01

    We present recent results of our experiments on laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. The longitudinal motion of the ions is directly cooled by the light pressure force, whereas efficient transverse cooling is obtained indirectly by longitudinal......-transverse coupling mechanisms. Laser cooling in novel bunch forms consisting of square-well buckets leads to longitudinally space-charge dominated beams. The observed longitudinal ion density distributions can be well described by a self-consistent mean-field model based on a thermodynamic Debye-Huckel approach....... When applying laser cooling in square-well buckets over long time intervals, hard Coulomb collisions suddenly disappear and the longitudinal temperature drops by about a factor of three. The observed longitudinal behaviour of the beam shows strong resemblance with the transition to an Coulomb...

  16. 2-μm Switchable dual-wavelength single-longitudinal-mode fiber laser based on a core-offset structure and carbon nanotube

    Science.gov (United States)

    Chen, Enci; Lu, Ping; Yang, Wei; Liu, Deming; Zhang, Jiangshan

    2016-11-01

    In this paper, we demonstrate a switchable single-longitudinal-mode (SLM) dual-wavelength fiber laser in 2-μm region based on a core-offset structure and carbon nanotube (CNT). The switchability of the fiber laser is based on a core-offset structure which acts as a tunable filter, so that the laser can work in stable dual-wavelength operation or switch between two wavelengths by adjusting the curvature of the core-offset structure. 3.68 nm (1919.44-1923.12 nm) and 6.32 nm (1890.64-1896.96 nm) tuning range can be obtained by tuning FBGs, respectively. The wavelength shift is less than 0.08 nm, and the power variation is smaller than 0.5 and 1 dB at 1923 and 1897 nm, respectively. The SLM oscillation is guaranteed by the CNT, which works as the loss factor to realize SLM oscillation. Absorption of the CNT increases the lasing threshold of the laser, therefore only the stronger mode can get lasing and SLM emission can be obtained. The proposed fiber laser offers a convenient and low-cost design for switchable dual-wavelength fiber laser in 2-μm region which has potential application in fields of gas sensing, lidar, and so on.

  17. Injection-locking of two frequency-doubled lasers with 3.2 GHz offset for driving Raman transitions with low photon scattering in $^{43}$Ca$^+$

    CERN Document Server

    Linke, N M; Lucas, D M

    2013-01-01

    We describe the injection locking of two infrared (794 nm) laser diodes which are each part of a frequency doubled laser system. An acousto-optic modulator (AOM) in the injection path gives an offset of 1.6 GHz between the lasers for driving Raman transitions between states in the hyperfine split (by 3.2 GHz) ground level of $^{43}$Ca$^+$. The offset can be disabled for use in $^{40}$Ca$^+$. We measure the relative linewidth of the frequency-doubled beams to be 42 mHz in an optical heterodyne measurement. The use of both injection locking and frequency doubling combines spectral purity with high optical power. Our scheme is applicable for providing Raman beams across other ion species and neutral atoms where coherent optical manipulation is required.

  18. Fast automotive diesel exhaust measurement using quantum cascade lasers

    Science.gov (United States)

    Herbst, J.; Brunner, R.; Lambrecht, A.

    2013-12-01

    Step by step, US and European legislations enforce the further reduction of atmospheric pollution caused by automotive exhaust emissions. This is pushing automotive development worldwide. Fuel efficient diesel engines with SCRtechnology can impede NO2-emission by reduction with NH3 down to the ppm range. To meet the very low emission limits of the Euro6 resp. US NLEV (National Low Emission Vehicle) regulations, automotive manufacturers have to optimize continuously all phases of engine operation and corresponding catalytic converters. Especially nonstationary operation holds a high potential for optimizing gasoline consumption and further reducing of pollutant emissions. Test equipment has to cope with demanding sensitivity and speed requirements. In the past Fraunhofer IPM has developed a fast emission analyzer called DEGAS (Dynamic Exhaust Gas Analyzer System), based on cryogenically cooled lead salt lasers. These systems have been used at Volkswagen AG`s test benches for a decade. Recently, IPM has developed DEGAS-Next which is based on cw quantum cascade lasers and thermoelectrically cooled detectors. The system is capable to measure three gas components (i.e. NO, NO2, NH3) in two channels with a time resolution of 20 ms and 1 ppm detection limits. We shall present test data and a comparison with fast FTIR measurements.

  19. Fast rate fracture of aluminum using high intensity lasers

    Science.gov (United States)

    Dalton, Douglas Allen

    Laser induced shock experiments were performed to study the dynamics of various solid state material processes, including shock-induced melt, fast rate fracture, and elastic to plastic response. Fast rate fracture and dynamic yielding are greatly influenced by microstructural features such as grain boundaries, impurity particles and alloying atoms. Fast fracture experiments using lasers are aimed at studying how material microstructure affects the tensile fracture characteristics at strain rates above 106 s-1. We used the Z-Beamlet Laser at Sandia National Laboratories to drive shocks via ablation and we measured the maximum tensile stress of aluminum targets with various microstructures. Using a velocity interferometer and sample recovery, we are able to measure the maximum tensile stress and determine the source of fracture initiation in these targets. We have explored the role that grain size, impurity particles and alloying in aluminum play in dynamic yielding and spall fracture at tensile strain rates of ˜3x106 s-1. Preliminary results and analysis indicated that material grain size plays a vital role in the fracture morphology and spall strength results. In a study with single crystal aluminum specimens, velocity measurements and fracture analysis revealed that a smaller amplitude tensile stress was initiated by impurity particles; however, these particles served no purpose in dynamic yielding. An aluminum-magnesium alloy with various grain sizes presented the lowest spall strength, but the greatest dynamic yield strength. Fracture mode in this alloy was initiated by both grain boundaries and impurity particles. With respect to dynamic yielding, alloying elements such as magnesium serve to decrease the onset of plastic response. The fracture stress and yield stress showed no evidence of grain size dependence. Hydrodynamic simulations with material strength models are used to compare with our experiments. In order to study the strain rate dependence of spall

  20. Pulsed laser deposition of HfO2 thin films on indium zinc oxide: Band offsets measurements

    Science.gov (United States)

    Craciun, D.; Craciun, V.

    2017-04-01

    One of the most used dielectric films for amorphous indium zinc oxide (IZO) based thin films transistor is HfO2. The estimation of the valence band discontinuity (ΔEV) of HfO2/IZO heterostructure grown using the pulsed laser deposition technique, with In/(In + Zn) = 0.79, was obtained from X-ray photoelectron spectroscopy (XPS) measurements. The binding energies of Hf 4d5, Zn 2p3 and In 3d5 core levels and valence band maxima were measured for thick pure films and for a very thin HfO2 film deposited on a thick IZO film. A value of ΔEV = 1.75 ± 0.05 eV was estimated for the heterostructure. Taking into account the measured HfO2 and IZO optical bandgap values of 5.50 eV and 3.10 eV, respectively, a conduction band offset ΔEC = 0.65 ± 0.05 eV in HfO2/IZO heterostructure was then obtained.

  1. Phase-stabilization of the carrier-envelope-offset frequency of a SESAM modelocked thin disk laser.

    Science.gov (United States)

    Klenner, Alexander; Emaury, Florian; Schriber, Cinia; Diebold, Andreas; Saraceno, Clara J; Schilt, Stéphane; Keller, Ursula; Südmeyer, Thomas

    2013-10-21

    We phase-stabilized the carrier-envelope-offset (CEO) frequency of a SESAM modelocked Yb:CaGdAlO₄ (CALGO) thin disk laser (TDL) generating 90-fs pulses at a center wavelength of 1051.6 nm and a repetition rate of 65 MHz. By launching only 2% of its output power into a photonic crystal fiber, we generated a coherent octave-spanning supercontinuum spectrum. Using a standard f-to-2f interferometer for CEO detection, we measured CEO beats with 33 dB signal-to-noise ratio in 100 kHz resolution bandwidth. We achieved a tight lock of the CEO frequency at 26.18 MHz by active feedback to the pump current. The residual in-loop integrated phase noise is 120 mrad (1 Hz-1 MHz). This is, to our knowledge, the first CEO-stabilized SESAM modelocked TDL. Our results show that a reliable lock of the CEO frequency can be achieved using standard techniques in spite of the strongly spatially multimode pumping scheme of TDLs. This opens the door towards fully-stabilized low-noise frequency combs with hundreds of watts of average power from table-top SESAM modelocked thin disk oscillators.

  2. Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors

    CERN Document Server

    Scott, R H H; Perez, F; Streeter, M J V; Davies, J R; Schlenvoigt, H -P; Santos, J J; Hulin, S; Lancaster, K L; Baton, S D; Rose, S J; Norreys, P A

    2013-01-01

    A photon detector suitable for the measurement of bremsstrahlung spectra generated in relativistically-intense laser-solid interactions is described. The Monte Carlo techniques used to back-out the fast electron spectrum and laser energy absorbed into fast electrons are detailed. A relativistically-intense laser-solid experiment using frequency doubled laser light is used to demonstrate the effective operation of the detector. The experimental data was interpreted using the 3-spatial-dimension Monte Carlo code MCNPX (Pelowitz 2008), and the fast electron temperature found to be 125 keV.

  3. Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors.

    Science.gov (United States)

    Scott, R H H; Clark, E L; Pérez, F; Streeter, M J V; Davies, J R; Schlenvoigt, H-P; Santos, J J; Hulin, S; Lancaster, K L; Baton, S D; Rose, S J; Norreys, P A

    2013-08-01

    A photon detector suitable for the measurement of bremsstrahlung spectra generated in relativistically intense laser-solid interactions is described. The Monte Carlo techniques used to extract the fast electron spectrum and laser energy absorbed into forward-going fast electrons are detailed. A relativistically intense laser-solid experiment using frequency doubled laser light is used to demonstrate the effective operation of the detector. The experimental data were interpreted using the 3-spatial-dimension Monte Carlo code MCNPX [D. Pelowitz, MCNPX User's Manual Version 2.6.0, Los Alamos National Laboratory, 2008], and the fast electron temperature found to be 125 keV.

  4. KINETIC MODEL OF ELECTRIC-DISCHARGE СО2-LASER WITH FAST FLOW

    Directory of Open Access Journals (Sweden)

    V. Nevdakh

    2013-01-01

    Full Text Available The paper presents a kinetic model of CW electric-discharge CO2-laser with fast flow. Expressions linking a non-saturated gain ratio, saturation intensity and output power of the fast-flow laser with excitation rates and relaxation times of laser levels have been obtained in the paper. The paper demonstrates that the higher excitation and flow rates or higher saturation intensity provide considerably higher specific output power of the fast-flow CO2-laser in comparison with a sealed-off CO2-laser. While maintaining a steady discharge the same output power of the fast-flow CO2-laser may be obtained under various discharge conditions and combinations of fast flow rate, gas mixture composition and active media temperature.

  5. Fast and precise algorithms for calculating offset correction in single photon counting ASICs built in deep sub-micron technologies

    Science.gov (United States)

    Maj, P.

    2014-07-01

    An important trend in the design of readout electronics working in the single photon counting mode for hybrid pixel detectors is to minimize the single pixel area without sacrificing its functionality. This is the reason why many digital and analog blocks are made with the smallest, or next to smallest, transistors possible. This causes a problem with matching among the whole pixel matrix which is acceptable by designers and, of course, it should be corrected with the use of dedicated circuitry, which, by the same rule of minimizing devices, suffers from the mismatch. Therefore, the output of such a correction circuit, controlled by an ultra-small area DAC, is not only a non-linear function, but it is also often non-monotonic. As long as it can be used for proper correction of the DC operation points inside each pixel, it is acceptable, but the time required for correction plays an important role for both chip verification and the design of a big, multi-chip system. Therefore, we present two algorithms: a precise one and a fast one. The first algorithm is based on the noise hits profiles obtained during so called threshold scan procedures. The fast correction procedure is based on the trim DACs scan and it takes less than a minute in a SPC detector systems consisting of several thousands of pixels.

  6. Fast analysis of wood preservers using laser induced breakdown spectroscopy

    Science.gov (United States)

    Uhl, A.; Loebe, K.; Kreuchwig, L.

    2001-06-01

    Laser-induced breakdown spectroscopy (LIBS) is used for the investigation of wood preservers in timber and in furniture. Both experiments in laboratory and practical applications in recycling facilities and on a building site prove the new possibilities for the fast detection of harmful agents in wood. A commercial system was developed for mobile laser-plasma-analysis as well as for industrial use in sorting plants. The universal measuring principle in combination with an Echelle optics permits real simultaneous multi-element-analysis in the range of 200-780 nm with a resolution of a few picometers. It enables the user to detect main and trace elements in wood within a few seconds, nearly independent of the matrix, knowing that different kinds of wood show an equal elemental composition. Sample preparation is not required. The quantitative analysis of inorganic wood preservers (containing, e.g. Cu, Cr, B, As, Pb, Hg) has been performed exactly using carbon as reference element. It can be shown that the detection limits for heavy metals in wood are in the ppm-range. Additional information is given concerning the quantitative analysis. Statistical data, e.g. the standard deviation (S.D.), were determined and calibration curves were used for each particular element. A comparison between ICP-AES and LIBS is given using depth profile correction factors regarding the different penetration depths with respect to the different volumes in wood analyzed by both analytical methods.

  7. Effect of laser wavelength and intensity on the divergence of hot electrons in fast ignition

    Science.gov (United States)

    Li, Boyuan; Tian, Chao; Zhang, Zhimeng; Zhang, Feng; Shan, Lianqiang; Zhang, Bo; Zhou, Weimin; Zhang, Baohan; Gu, Yuqiu

    2016-09-01

    Recently, the short wavelength laser is believed to have a promising prospect in fast ignition for reducing the conflict between laser energy requirement and electron stopping range. Here we investigate the influence of laser wavelength and intensity in the angular dispersion of hot electrons. Both our theoretical model and numerical simulations show that the angular dispersion would increase rapidly with the shortening of laser wavelength due to the Weibel instability, while the laser intensity has little effect on it. These results have important implications for fast ignition.

  8. Effects of Laser Parameters on Fast Electron Generation in a Multihole Array Target

    Institute of Scientific and Technical Information of China (English)

    JI Yan-Ling; DUAN Tao; JIANG Gang; WU Wei-Doug; TANG Yong-Jian

    2011-01-01

    The effects of laser parameters on the production of fast electrons from laser-multihole array target interaction are investigated theoretically via two-dimensional particle-in-cell simulations. The results show that the fast electron temperature is scaled by I1/2(λ)2 with I and(λ) being the laser intensity and wavelength. When the laser intensity reaches 2.14 × 10(20) W.cm-2, a typical bi-Maxwellian energy distribution is observed. The slope temperature of the low-energy component fits the linear scaling Th~I1/2 well. The high-energy component has an increased slope temperature comparable to ponderomotive potential scaling law. In addition, the electron temperature rises linearly with the pulse duration, Th~△t. The divergence angle of the fast electrons increases with laser intensity and pulse duration, but is independent of laser wavelength.

  9. Generation of fast electrons by breaking of a laser-induced plasma wave

    NARCIS (Netherlands)

    Trines, Rmgm; Goloviznin, V. V.; Kamp, L. P. J.; Schep, T. J.

    2001-01-01

    A one-dimensional model for fast electron generation by an intense, nonevolving laser pulse propagating through an underdense plasma has been developed. Plasma wave breaking is considered to be the dominant mechanism behind this process, and wave breaking both in front of and behind the laser pulse

  10. Fast- and ultra-fast laser pulse induced reactions between carbon dioxide and methane

    CSIR Research Space (South Africa)

    Kotze, FJ

    2010-03-01

    Full Text Available (Mira oscillator) emits pulses of approximately 120 fs at a repetition rate of 76 MHz. This laser is optically pumped by a Verdi pump laser, a 5 W Nd:YVO4 continuous laser. 2.3. Experimental set-up Figure 1 illustrates the experimental setup. A gas...

  11. Fast Polarization Switching Demonstration Using Crossed-Planar Undulator in a Seeded Free Electron Laser

    CERN Document Server

    Deng, Haixiao; Feng, Lie; Feng, Chao; Chen, Jianhui; Liu, Bo; Wang, Xingtao; Lan, Taihe; Wang, Guanglei; Zhang, Wenyan; Liu, Xiaoqing; Zhang, Meng; Lin, Guoqiang; Zhang, Miao; Wang, Dong; Zhao, Zhentang

    2013-01-01

    Fast polarization switching of light sources is required over a wide spectral range to investigate the symmetry of matter. In this Letter, we report the first experimental demonstration of the crossed-planar undulator technique at a seeded free-electron laser, which holds great promise for the full control and fast switching of the polarization of short-wavelength radiation. In the experiment, the polarization state of the coherent radiation at the 2nd harmonic of the seed laser is switched successfully. The experiment results confirm the theory, and pave the way for applying the crossed-planar undulator technique for the seeded X-ray free electron lasers.

  12. Electron Generation and Transport in Intense Relativistic Laser-Plasma Interactions Relevant to Fast Ignition ICF

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tammy Yee Wing [Univ. of California, San Diego, CA (United States)

    2010-01-01

    The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.

  13. Impedance matching in RF excited fast axial flow CO2 laser: The role of the capacitance due to laser head

    Science.gov (United States)

    Bhagat, M. S.; Biswas, A. K.; Rana, L. B.; Kukreja, L. M.

    2012-10-01

    Impedance matching in an indigenously developed 2 kW RF-excited fast axial flow (RF-FAF) CO2 laser was seen to be significantly influenced by the capacitance formed between the laser head and the electrodes. We find in the published literature that this capacitance is generally assumed to be negligible while designing the matching network in the RF-FAF CO2 lasers. It is shown that this capacitance could have a significant value and consequently would modify the design of the matching network remarkably for a specific laser design studied in the present case. The widely used discharge load model for capacitively coupled RF (CCRF) discharge excited CO2 laser plasma is extended to include this capacitance. The method of measurement of this capacitance using a bridge and the ANSYS software based simulation of its formation due to the laser head structure are discussed.

  14. Ablation experiment and threshold calculation of titanium alloy irradiated by ultra-fast pulse laser

    Directory of Open Access Journals (Sweden)

    Buxiang Zheng

    2014-02-01

    Full Text Available The interaction between an ultra-fast pulse laser and a material's surface has become a research hotspot in recent years. Micromachining of titanium alloy with an ultra-fast pulse laser is a very important research direction, and it has very important theoretical significance and application value in investigating the ablation threshold of titanium alloy irradiated by ultra-fast pulse lasers. Irradiated by a picosecond pulse laser with wavelengths of 1064 nm and 532 nm, the surface morphology and feature sizes, including ablation crater width (i.e. diameter, ablation depth, ablation area, ablation volume, single pulse ablation rate, and so forth, of the titanium alloy were studied, and their ablation distributions were obtained. The experimental results show that titanium alloy irradiated by a picosecond pulse infrared laser with a 1064 nm wavelength has better ablation morphology than that of the green picosecond pulse laser with a 532 nm wavelength. The feature sizes are approximately linearly dependent on the laser pulse energy density at low energy density and the monotonic increase in laser pulse energy density. With the increase in energy density, the ablation feature sizes are increased. The rate of increase in the feature sizes slows down gradually once the energy density reaches a certain value, and gradually saturated trends occur at a relatively high energy density. Based on the linear relation between the laser pulse energy density and the crater area of the titanium alloy surface, and the Gaussian distribution of the laser intensity on the cross section, the ablation threshold of titanium alloy irradiated by an ultra-fast pulse laser was calculated to be about 0.109 J/cm2.

  15. Generation of fast highly charged ions in laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Wolowski, J [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Badziak, J [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Boody, F P [Ion Light Technologies GmbH, Bad Abbach (Germany); Czarnecka, A [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Gammino, S [INFN-Laboratori Nazionali del Sud, Catania (Italy); Jablonski, S [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Krasa, J [Institute of Physics, ASCR (Czech Republic); Laska, L [Institute of Physics, ASCR (Czech Republic); Parys, P [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Rohlena, K [Institute of Physics, ASCR (Czech Republic); Rosinski, M [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Ryc, L [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Torrisi, L [INFN-Laboratori Nazionali del Sud, Catania (Italy); Ullschmied, J [IPALS Research Centre ASCR, Prague (Czech Republic)

    2006-12-15

    The nonthermal and nonlinear coupling of strong laser light wave with plasma transfers a part of laser energy into hot electrons and fast ions. The efficiency of these effects depends on the characteristics of a laser pulse, target properties and irradiation geometry. The reported studies were performed with the use of a high-power and high-energy iodine PALS laser system (energy up to 1 kJ in a 0.4 ns pulse at wavelength of 1315 nm and energy up to 250 J at wavelength of 438 nm). The properties of the laser-produced ion streams were determined with the use of ion diagnostics based on the time-of-flight method. The characteristics of x-rays were measured using various semiconductor detectors. The main ion stream characteristics as well as the ion acceleration processes in plasmas of different Z numbers were studied in dependence on laser pulse parameters. The parameters of a fast ion group depend evidently on Z number of the ions. The influence of the electron density scale length on fast ion generation was investigated using a low intensity laser pre-pulses to generate preformed plasmas (pre-plasmas) with which the main laser pulse interacted. The obtained results suggest that ion acceleration processes were most effective at a specific electron density gradient scale length of pre-plasma determined by the pre-pulse parameters.

  16. Laser frequency locking with 46 GHz offset using an electro-optic modulator for magneto-optical trapping of francium atoms

    CERN Document Server

    Harada, K; Ezure, S; Kato, K; Hayamizu, T; Kawamura, H; Inoue, T; Arikawa, H; Ishikawa, T; Aoki, T; Uchiyama, A; Sakamoto, K; Ito, S; Itoh, M; Ando, S; Hatakeyama, A; Hatanaka, K; Imai, K; Murakami, T; Nataraj, H S; Shimizu, Y; Sato, T; Wakasa, T; Yoshida, H P; Sakemi, Y

    2016-01-01

    We demonstrated a frequency offset locking between two laser sources using a waveguide-type electro-optic modulator (EOM) with 10th-order sidebands for magneto-optical trapping of Fr atoms. The frequency locking error signal was successfully obtained by performing delayed self-homodyne detection of the beat signal between the repumping frequency and the 10th-order sideband component of the trapping light. Sweeping the trapping-light and repumping-light frequencies with keeping its frequency difference of 46 GHz was confirmed over 1 GHz by monitoring the Doppler absorption profile of I2. This technique enables us to search for a resonance frequency of magneto-optical trapping of Fr.

  17. Enhanced hole boring with two-color relativistic laser pulses in the fast ignition scheme

    Science.gov (United States)

    Yu, Changhai; Deng, Aihua; Tian, Ye; Li, Wentao; Wang, Wentao; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Liu, Jiansheng

    2016-08-01

    A scheme of using two-color laser pulses for hole boring into overdense plasma as well as energy transfer into electron and ion beams has been studied using particle-in-cell simulations. Following an ultra-short ultra-intense hole-boring laser pulse with a short central wavelength in extreme ultra-violet range, the main infrared driving laser pulse can be guided in the hollow channel preformed by the former laser and propagate much deeper into an overdense plasma, as compared to the case using the infrared laser only. In addition to efficiently transferring the main driving laser energy into energetic electrons and ions generation deep inside the overdense plasma, the ion beam divergence can be greatly reduced. The results might be beneficial for the fast ignition concept of inertial confinement fusion.

  18. Locking Lasers to RF in an Ultra Fast FEL

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, R.; Huang, G.; Doolittle, L.; White, W.; Frisch, J.; Coffee, R.

    2010-01-02

    Using a novel, phase-stabilized RF-over-fiber scheme, they transmit 3GHz over 300m with 27fs RMS error in 250kHz bandwidth over 12 hours, and phase lock a laser to enable ultrafast pump-probe experiments. Free-electron lasers (FELs) are capable of producing short-duration (< 10fs), high-energy X-ray pulses for a range of scientific applications. The recently activated Linac Coherent Light Source (LCLS) FEL facility at SLAC will support experiments which require synchronized light pulses for pump-probe schemes. They developed and operated a fiber optic RF transmission system to synchronize lasers to the emitted X-ray pulses, which was used to enable the first pump-probe experiments at the LCLS.

  19. Measurement of fast electrons spectra generated by interaction between solid target and peta watt laser

    Energy Technology Data Exchange (ETDEWEB)

    Tanimoto, T; Habara, H; Tanaka, K A; Kodama, R [Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nakatsutsumi, M [Laboratoire pour l' Utilisation des Laser Intenses (LULI), CNRS, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau, Cedex F 91128 (France); Lancaster, K L; Green, J S; Scott, R H H; Sherlock, M; Norreys, P A [STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Evans, R G; Haines, M G [Department of Physics, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2BZ (United Kingdom); Kar, S; Zepf, M [Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, University Road, Belfast BT7 1NN (United Kingdom); King, J; Ma, T; Wei, M S; Yabuuchi, T; Beg, F N [Department of Mechanical and Aerospace Engineering, UC San Diego, 9500 Gillman Drive 0411, La Jolla, California 92093-0411, United States of America (United States); Key, M H, E-mail: tanimoto@ile.osaka-u.ac.j [Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94550, United States of America (United States)

    2010-08-01

    Fast electron energy spectra have been measured for a range of intensities between 10{sup 18} Wcm{sup -2} and 10{sup 21} Wcm{sup -2} and for different target materials using electron spectrometers. Several experimental campaigns were conducted on peta watt laser facilities at the Rutherford Appleton Laboratory and Osaka University. In these experimental campaigns, the pulse duration was varied from 0.5 ps to 5 ps. The laser incident angle was also changed from normal incidence to 40{sup 0} in p-polarized. The results show a reduction from the ponderomotive scaling on fast electrons over 10{sup 20} Wcm{sup -2}.

  20. Controlling the fast electron divergence in a solid target with multiple laser pulses

    Science.gov (United States)

    Volpe, L.; Feugeas, J.-L.; Nicolai, Ph.; Santos, J. J.; Touati, M.; Breil, J.; Batani, D.; Tikhonchuk, V.

    2014-12-01

    Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.

  1. Ultra fast imaging of a laser wake field accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Saevert, Alexander; Schnell, Michael; Nicolai, Maria; Reuter, Maria; Schwab, Matthew B.; Moeller, Max [Friedrich-Schiller-Universitaet, Jena (Germany); Mangles, Stuart P.D.; Cole, Jason M.; Poder, Kristjan; Najmudin, Zulfikar [The John Adams Institute Imperial College, London (United Kingdom); Jaeckel, Oliver; Paulus, Gerhard G.; Spielmann, Christian; Kaluza, Malte C. [Friedrich-Schiller-Universitaet, Jena (Germany); Helmholtz Institut Jena, Jena (Germany)

    2014-07-01

    Ultra intense laser pulses are known to excite plasma waves with a relativistic phase velocity. By harnessing these waves it is possible to generate quasi-monoenergetic, ultra-short electron pulses with kinetic energies from 0.1 to 2 GeV by guiding the laser pulse over several Rayleigh lengths. To further improve the stability of these particle pulses and ultimately to be able to tailor the energy spectrum toward their suitability for various applications, the physics underlying the different acceleration scenarios need to be understood as completely as possible. To be able to resolve the acceleration process diagnostics well-suited for this plasma environment need to be designed and realized. By using sub-10 fs probe pulses we were able to freeze the transient accelerating structure in the plasma. We will present the first results of an experiment which was carried out with the 30 TW JETi Laser and a few cycle probe pulse at the Institute of Optics and Quantum Electronics Jena. The resulting snapshots show unprecedented details from the laser plasma interaction and allow a direct comparison to computer simulations.

  2. A focusable, convergent fast-electron beam from ultra-high-intensity laser-solid interactions

    CERN Document Server

    Scott, R H H

    2015-01-01

    A novel scheme for the creation of a convergent, or focussing, fast-electron beam generated from ultra-high-intensity laser-solid interactions is described. Self-consistent particle-in-cell simulations are used to demonstrate the efficacy of this scheme in two dimensions. It is shown that a beam of fast-electrons of energy 500 keV - 3 MeV propagates within a solid-density plasma, focussing at depth. The depth of focus of the fast-electron beam is controlled via the target dimensions and focussing optics.

  3. Fast modulation scheme for a two laterally coupled laser diode array

    Energy Technology Data Exchange (ETDEWEB)

    Carpintero, G.; Lamela, H.; Leones, M.; Simmendinger, C.; Hess, O.

    2001-06-25

    The present letter reports a modulation scheme that takes advantage of the unique characteristics of a two laterally coupled laser diode (also known as twin stripe array) to overcome the limit on the modulation imposed by the laser{close_quote}s relaxation oscillation frequency. Through the use of the rate equation description of the device we uncover the device dynamics behind the modulation scheme generating 35 ps (full width at half maximum) laser pulses at 8 Gb/s modulation rate. Our scheme relies on the fast dynamics of the phase difference, controlled by means of the current injection on each stripe. {copyright} 2001 American Institute of Physics.

  4. Fast magnetic field annihilation driven by two laser pulses in underdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y. J.; Kumar, D.; Weber, S.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); Klimo, O. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); FNSPE, Czech Technical University in Prague, 11519 Prague (Czech Republic); Bulanov, S. V.; Esirkepov, T. Zh. [Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan)

    2015-10-15

    Fast magnetic annihilation is investigated by using 2.5-dimensional particle-in-cell simulations of two parallel ultra-short petawatt laser pulses co-propagating in underdense plasma. The magnetic field generated by the laser pulses annihilates in a current sheet formed between the pulses. Magnetic field energy is converted to an inductive longitudinal electric field, which efficiently accelerates the electrons of the current sheet. This new regime of collisionless relativistic magnetic field annihilation with a timescale of tens of femtoseconds can be extended to near-critical and overdense plasma with the ultra-high intensity femtosecond laser pulses.

  5. A fast method for morphological analysis of laser drilling holes

    OpenAIRE

    Schneider, Matthieu; Berthe, Laurent; Muller, Maryse; Fabbro, Rémy

    2010-01-01

    International audience; This paper presents an original method for analyzing laser drilled holes. The so-called Direct Observation of Drilled hOle (DODO) method is introduced and its applications. The hole characterization that's been made is compared with x-ray radiography and cross-section analysis. Direct Observation of Drilled hole provides instantaneously surface state, geometric shape, as well as recast layer structure, without additional operation. Since no mounting resin is used to em...

  6. Fast Automatic Precision Tree Models from Terrestrial Laser Scanner Data

    Directory of Open Access Journals (Sweden)

    Mathias Disney

    2013-01-01

    Full Text Available This paper presents a new method for constructing quickly and automatically precision tree models from point clouds of the trunk and branches obtained by terrestrial laser scanning. The input of the method is a point cloud of a single tree scanned from multiple positions. The surface of the visible parts of the tree is robustly reconstructed by making a flexible cylinder model of the tree. The thorough quantitative model records also the topological branching structure. In this paper, every major step of the whole model reconstruction process, from the input to the finished model, is presented in detail. The model is constructed by a local approach in which the point cloud is covered with small sets corresponding to connected surface patches in the tree surface. The neighbor-relations and geometrical properties of these cover sets are used to reconstruct the details of the tree and, step by step, the whole tree. The point cloud and the sets are segmented into branches, after which the branches are modeled as collections of cylinders. From the model, the branching structure and size properties, such as volume and branch size distributions, for the whole tree or some of its parts, can be approximated. The approach is validated using both measured and modeled terrestrial laser scanner data from real trees and detailed 3D models. The results show that the method allows an easy extraction of various tree attributes from terrestrial or mobile laser scanning point clouds.

  7. Fast photocatalytic degradation of methylene blue dye using a low-power diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xianhua, E-mail: lxh@tju.edu.cn [School of Environmental Science and Engineering, Tianjin University, No. 92, Weijin Road, Nankai District, Tianjin 300072 (China); Yang, Yulou; Shi, Xiaoxuan [School of Environmental Science and Engineering, Tianjin University, No. 92, Weijin Road, Nankai District, Tianjin 300072 (China); Li, Kexun, E-mail: likx@nankai.edu.cn [School of Environmental Science and Engineering, Nankai University, Tianjin 300074 (China)

    2015-02-11

    Highlights: • Photocatalytic oxidation of methylene blue was studied under laser light irradiation. • Fast removal of methylene blue from aqueous solution was achieved. • The photocatalyst Ag/AgCl is efficient and stable under 443 nm laser light irritation. • Diode laser is a good light source for photocatalytic degradation of dyes. - Abstract: This study focused on the application of diode lasers as alternative light sources for the fast photocatalytic degradation of methylene blue. The photocatalytic decomposition of methylene blue in aqueous solution under 443 nm laser light irradiation was found to be technically feasible using Ag/AgCl nanoparticles as photocatalysts. The effects of various experimental parameters, such as irradiation time, light source, catalyst loading, initial dye concentration, pH, and laser energy on decolorization and degradation were investigated. The mineralization of methylene blue was confirmed by chemical oxygen demand analysis. The results demonstrate that the laser-induced photocatalytic process can effectively degrade methylene blue under the optimum conditions (pH 9.63, 4 mg/L MB concentration, and 1.4 g/L Ag/AgCl nanoparticles)

  8. Stable mode-locking in an Yb:YAG laser with a fast SESAM

    Institute of Scientific and Technical Information of China (English)

    Guifang Ju(居桂方); Lu Chai(柴路); Qingyue Wang(王清月); Zhigang Zhang(张志刚); Yonggang Wang(王勇刚); Xiaoyu Ma(马骁宇)

    2003-01-01

    Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.

  9. Controlling fast electron beam divergence via temporal shaping of the laser intensity envelope

    CERN Document Server

    Scott, R H H; Beaucourt, C; Markey, K; Lancaster, K L; Brenner, C M; Gray, R J; Musgrave, I O; Robinson, A P L; Li, K; Pasley, J; Notley, M M; Davies, J R; Baton, S D; Santos, J J; McKenna, P; Neely, D; Rose, S J; Norreys, P A

    2010-01-01

    A new experimental technique is described which uses two relativistically intense laser pulses to control and enhance the properties of the MeV electron beam generated during the interaction of an ultra-high-intensity laser pulse with a solid target. Both thermal and Cu K$_{\\alpha}$ x-ray imaging diagnostics show reduced emission size, increased peak emission, increased total emission, and reduced shot-to-shot variability with respect to a single high-contrast pulse. This evidences reduced fast electron divergence, increased fast electron current density and increased energy absorption into the target via fast electrons. The observed characteristics are attributed to magnetic field generation within the target and alterations to the plasma density scale length.

  10. Adaptable DC offset correction

    Science.gov (United States)

    Golusky, John M. (Inventor); Muldoon, Kelly P. (Inventor)

    2009-01-01

    Methods and systems for adaptable DC offset correction are provided. An exemplary adaptable DC offset correction system evaluates an incoming baseband signal to determine an appropriate DC offset removal scheme; removes a DC offset from the incoming baseband signal based on the appropriate DC offset scheme in response to the evaluated incoming baseband signal; and outputs a reduced DC baseband signal in response to the DC offset removed from the incoming baseband signal.

  11. Wide and Fast Wavelength-Swept Fiber Laser Based on Dispersion Tuning for Dynamic Sensing

    Directory of Open Access Journals (Sweden)

    Shinji Yamashita

    2009-01-01

    Full Text Available We have developed a unique wide and fast wavelength-swept fiber laser for dynamic and accurate fiber sensing. The wavelength tuning is based on the dispersion tuning technique, which simply modulates the loss/gain in the dispersive laser cavity. By using wideband semiconductor optical amplifiers (SOAs, the sweep range could be as wide as ∼180 nm. Since the cavity contains no mechanical components, such as tunable filters, we could achieve very high sweep rate, as high as ∼200 kHz. We have realized the swept lasers at three wavelength bands, 1550 nm, 1300 nm, and 800 nm, using SOAs along with erbium-doped fiber amplifiers (EDFAs, and in two laser configurations, ring and linear ones. We also succeeded in applying the swept laser for a dynamic fiber-Bragg grating (FBG sensor system. In this paper, we review our researches on the wide and fast wavelength-swept fiber lasers.

  12. A vision-based system for fast and accurate laser scanning in robot-assisted phonomicrosurgery.

    Science.gov (United States)

    Dagnino, Giulio; Mattos, Leonardo S; Caldwell, Darwin G

    2015-02-01

    Surgical quality in phonomicrosurgery can be improved by open-loop laser control (e.g., high-speed scanning capabilities) with a robust and accurate closed-loop visual servoing systems. A new vision-based system for laser scanning control during robot-assisted phonomicrosurgery was developed and tested. Laser scanning was accomplished with a dual control strategy, which adds a vision-based trajectory correction phase to a fast open-loop laser controller. The system is designed to eliminate open-loop aiming errors caused by system calibration limitations and by the unpredictable topology of real targets. Evaluation of the new system was performed using CO(2) laser cutting trials on artificial targets and ex-vivo tissue. This system produced accuracy values corresponding to pixel resolution even when smoke created by the laser-target interaction clutters the camera view. In realistic test scenarios, trajectory following RMS errors were reduced by almost 80 % with respect to open-loop system performances, reaching mean error values around 30 μ m and maximum observed errors in the order of 60 μ m. A new vision-based laser microsurgical control system was shown to be effective and promising with significant positive potential impact on the safety and quality of laser microsurgeries.

  13. Fast photocatalytic degradation of methylene blue dye using a low-power diode laser.

    Science.gov (United States)

    Liu, Xianhua; Yang, Yulou; Shi, Xiaoxuan; Li, Kexun

    2015-01-01

    This study focused on the application of diode lasers as alternative light sources for the fast photocatalytic degradation of methylene blue. The photocatalytic decomposition of methylene blue in aqueous solution under 443 nm laser light irradiation was found to be technically feasible using Ag/AgCl nanoparticles as photocatalysts. The effects of various experimental parameters, such as irradiation time, light source, catalyst loading, initial dye concentration, pH, and laser energy on decolorization and degradation were investigated. The mineralization of methylene blue was confirmed by chemical oxygen demand analysis. The results demonstrate that the laser-induced photocatalytic process can effectively degrade methylene blue under the optimum conditions (pH 9.63, 4 mg/L MB concentration, and 1.4 g/L Ag/AgCl nanoparticles). Copyright © 2014 Elsevier B.V. All rights reserved.

  14. FAST CARS Developing a Laser Spectroscopic Technique for Rapid Identification of Bacterial Spores

    CERN Document Server

    Scully, M O; Lucht, R P; Opatrny, T; Pilloff, H; Rebane, A; Sokolov, A V; Zubairy, M S

    2002-01-01

    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time consuming microscopic, chemical and biological assays. Current research into real time laser spectroscopic detectors of such contaminants is based on e.g. resonant Raman spectroscopy. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. The connection with previous studies based on "Coherent Anti-Stokes Raman Spectroscopy" (CARS) is to be noted. However generating and utilizing maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is much more challenging. This extension of the CARS technique is called FAST CARS (Femtosecond Adaptive Spectroscopic Techniques for Coherent Anti-Stokes Raman Spectroscopy), and the present paper proposes and analyses ways in which it could be used to rapidly identify pre-selected molecules in real time.

  15. Signal enhancement in laser-induced breakdown spectroscopy using fast square-pulse discharges

    Science.gov (United States)

    Sobral, H.; Robledo-Martinez, A.

    2016-10-01

    A fast, high voltage square-shaped electrical pulse initiated by laser ablation was investigated as a means to enhance the analytical capabilities of laser Induced breakdown spectroscopy (LIBS). The electrical pulse is generated by the discharge of a charged coaxial cable into a matching impedance. The pulse duration and the stored charge are determined by the length of the cable. The ablation plasma was produced by hitting an aluminum target with a nanosecond 532-nm Nd:YAG laser beam under variable fluence 1.8-900 J cm- 2. An enhancement of up to one order of magnitude on the emission signal-to-noise ratio can be achieved with the spark discharge assisted laser ablation. Besides, this increment is larger for ionized species than for neutrals. LIBS signal is also increased with the discharge voltage with a tendency to saturate for high laser fluences. Electron density and temperature evolutions were determined from time delays of 100 ns after laser ablation plasma onset. Results suggest that the spark discharge mainly re-excites the laser produced plume.

  16. Fast femtosecond laser ablation for efficient cutting of sintered alumina substrates

    Science.gov (United States)

    Oosterbeek, Reece N.; Ward, Thomas; Ashforth, Simon; Bodley, Owen; Rodda, Andrew E.; Simpson, M. Cather

    2016-09-01

    Fast, accurate cutting of technical ceramics is a significant technological challenge because of these materials' typical high mechanical strength and thermal resistance. Femtosecond pulsed lasers offer significant promise for meeting this challenge. Femtosecond pulses can machine nearly any material with small kerf and little to no collateral damage to the surrounding material. The main drawback to femtosecond laser machining of ceramics is slow processing speed. In this work we report on the improvement of femtosecond laser cutting of sintered alumina substrates through optimisation of laser processing parameters. The femtosecond laser ablation thresholds for sintered alumina were measured using the diagonal scan method. Incubation effects were found to fit a defect accumulation model, with Fth,1=6.0 J/cm2 (±0.3) and Fth,∞=2.5 J/cm2 (±0.2). The focal length and depth, laser power, number of passes, and material translation speed were optimised for ablation speed and high quality. Optimal conditions of 500 mW power, 100 mm focal length, 2000 μm/s material translation speed, with 14 passes, produced complete cutting of the alumina substrate at an overall processing speed of 143 μm/s - more than 4 times faster than the maximum reported overall processing speed previously achieved by Wang et al. [1]. This process significantly increases processing speeds of alumina substrates, thereby reducing costs, making femtosecond laser machining a more viable option for industrial users.

  17. Studying of Laser Plasma Physics Related With Fast Ignition of ICF

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fast ignition(FI) concept of ICF is one of the most attractive application of high intensity ultrashort laser. The UV light has some advantages for applying to fast ignition, the first, as the I λ2 scaling law of hot electron temperature, at the FI required intensity(1020 W/cm2), the long wavelength light will generate >10 MeV electron that can not deposit energy efficiently in the fuel region. Meanwhile the UV light can just generate the electron with the required energy of 1 MeV.

  18. Hollow nanoparticles of metal oxides and sulfides: fast preparation via laser ablation in liquid.

    Science.gov (United States)

    Niu, K Y; Yang, J; Kulinich, S A; Sun, J; Du, X W

    2010-11-16

    In this work, diverse hollow nanoparticles of metal oxides and sulfides were prepared by simply laser ablating metal targets in properly chosen liquids. The Kirkendall voiding and the selective heating with an infrared laser were shown to work as two independent mechanisms for the formation of such hollow nanoparticles in only one- or two-step synthesis approaches. One of the prepared materials, ZnS hollow nanoparticles, showed high performance in gas sensing. The simple, fast, inexpensive technique that is proposed demonstrates very promising perspectives.

  19. Ultra-fast fiber lasers principles and applications with Matlab models

    CERN Document Server

    Binh, Le Nguyen

    2010-01-01

    Ultrashort pulses in mode-locked lasers are receiving focused attention from researchers looking to apply them in a variety of fields, from optical clock technology to measurements of the fundamental constants of nature and ultrahigh-speed optical communications. Ultrashort pulses are especially important for the next generation of ultrahigh-speed optical systems and networks operating at 100 Gbps per carrier. Ultra Fast Fiber Lasers: Principles and Applications with MATLAB(R) Models is a self-contained reference for engineers and others in the fields of applied photonics and optical communica

  20. Neutral dissociation of methane in the ultra-fast laser pulse

    Institute of Scientific and Technical Information of China (English)

    SONG Di; LIU Kai; KONG FanAo; XIA AnDong

    2008-01-01

    Neutral fragments of methane were performed using femetoeecond laser at an intensity of 1013-14 W/cm2. A new mechanism of neutral dissociation is proposed in this work. The methane molecule is excited to super-excited states, in which it would dissociate into neutral fragments. We made Morse type potential energy surfaces for the super-excited molecules. Furthermore, we investigated the dissociation dy-namics of the super-excited states by using quasi-classical trajectory (QCT) method. The results thus interpret the neutral dissociation of the methane molecule in the ultra-fast laser pulse.

  1. Fast steel-cleanness characterization by means of laser-assisted plasma spectrometric methods.

    Science.gov (United States)

    Müller, Gregor; Stahnke, Frank; Bleiner, Davide

    2006-12-15

    Laser-assisted plasma spectrometry is a palette of analytical techniques (L-OES, LA-ICP-MS) capable of fast spatially-resolved elemental analysis in the micrometer range. For fast estimation of the occurrence in steel samples of non-metallic inclusions, which degrade the material's technical properties, simultaneous OES detection and sequential ICP-MS detection were compared. Histograms were obtained for the intensity distribution of the acquired signals (laser pulse statistics). The skewness coefficient of the histograms for Al (indicator of non-metallic inclusions) was found to be clearly dependent on the fraction of non-metallic inclusions in the case of scanning L-OES. For LA-ICP-MS less clear dependence was observed, which was influenced by the acquisition characteristics. In fact, less measurement throughput limited for LA-ICP-MS the counting statistics to an extent that overrides the benefit of higher detection power as compared to L-OES.

  2. Indigenous development of a 2 kW RF-excited fast axial flow CO2 laser

    Indian Academy of Sciences (India)

    A K Biswas; M S Bhagat; L B Rana; A Verma; L M Kukreja

    2010-11-01

    RF-excited fast axial flow CO2 lasers in kilowatt regime are presently being used for various new scientific applications in addition to laser material processing because of its versatility and superior beam quality. We have indigenously developed a compact 2 kW RF-excited fast axial flow CO2 laser with moderate beam quality. In this paper the key design features of the laser and the associated high power capacitively coupled RF excitation technique are discussed in detail. Operational characteristics of this system are described along with the experimental findings.

  3. Modeling of fast capillary discharge for collisionally excited soft x-ray lasers: comparison with experiments

    Science.gov (United States)

    Shlyaptsev, Vyacheslav N.; Gerusov, Alexey V.; Vinogradov, Alexander V.; Rocca, Jorge J. G.; Cortazar, O. D.; Tomasel, Fernando G.; Szapiro, Benito T.

    1994-02-01

    In this paper we report results of a model of a fast capillary discharge (FCD) and discuss them in comparison with experiments. The overall good coincidence between theory and experiment and the observation of stable reproducible compression are beneficial properties of FCD which open the possibility for achieving X-ray laser action in a compact discharge device. The required discharge parameters for lasing in different atomic elements have been calculated.

  4. Fast spectral coherent anti-Stokes Raman scattering microscopy with high-speed tunable picosecond laser.

    Science.gov (United States)

    Cahyadi, Harsono; Iwatsuka, Junichi; Minamikawa, Takeo; Niioka, Hirohiko; Araki, Tsutomu; Hashimoto, Mamoru

    2013-09-01

    We develop a coherent anti-Stokes Raman scattering (CARS) microscopy system equipped with a tunable picosecond laser for high-speed wavelength scanning. An acousto-optic tunable filter (AOTF) is integrated in the laser cavity to enable wavelength scanning by varying the radio frequency waves applied to the AOTF crystal. An end mirror attached on a piezoelectric actuator and a pair of parallel plates driven by galvanometer motors are also introduced into the cavity to compensate for changes in the cavity length during wavelength scanning to allow synchronization with another picosecond laser. We demonstrate fast spectral imaging of 3T3-L1 adipocytes every 5  cm-1 in the Raman spectral region around 2850  cm-1 with an image acquisition time of 120 ms. We also demonstrate fast switching of Raman shifts between 2100 and 2850  cm-1, corresponding to CD2 symmetric stretching and CH2 symmetric stretching vibrations, respectively. The fast-switching CARS images reveal different locations of recrystallized deuterated and nondeuterated stearic acid.

  5. Comparison of models of fast saturable absorption in passively modelocked lasers.

    Science.gov (United States)

    Wang, Shaokang; Marks, Brian S; Menyuk, Curtis R

    2016-09-01

    Fast saturable absorbers (FSAs) play a critical role in stabilizing many passively modelocked lasers. The most commonly used averaged model to study these lasers is the Haus modelocking equation (HME) that includes a third-order nonlinear FSA. However, it predicts a narrow region of stability that is inconsistent with experiments. To better replicate the laser physics, averaged laser models that include FSAs with higher-than-third-order nonlinearities have been introduced. Here, we compare three common FSA models to each other and to the HME using the recently-developed boundary tracking algorithms. The three FSA models are the cubic-quintic model, the sinusoidal model, and the algebraic model. We find that all three models predict the existence of a stable high-energy solution that is not present in the HME and have a much larger stable operating region. We also find that all three models predict qualitatively similar stability diagrams. We conclude that averaged laser models that include FSAs with higher-than-third-order nonlinearity should be used when studying the stability of passively modelocked lasers.

  6. Fast-tuning narrow-linewidth all polarization-maintaining fiber ring laser

    Science.gov (United States)

    Meng, Zhou; Hu, Zhengliang; Hu, Yongming; Xiong, Shuidong; Cao, Chunyan

    2007-04-01

    This paper describes the structure and operation of a stable, fast-tuning, narrow-linewidth, all polarization-maintaining fibre ring laser using erbium-doped fibre as a saturable absorber. The optimum pump power for single-mode operation in the laser is identified. Laser output power is ~4.0mW at 1536nm for a pump power of 80mW, the polarization extinction ratio is 25.0dB, the SNR is larger than 60dB, the relative intensity noise is below -118dB/Hz at frequencies above 90kHz. The phase noise achieves -107dB at 1kHz while the modulation frequency of lasing optical frequency is 12.5kHz.

  7. High-resolution X-ray imaging in fast ignition experiment using Gekko and LFEX lasers

    Directory of Open Access Journals (Sweden)

    Koga M.

    2013-11-01

    Full Text Available We improved diagnostic instruments to measure X-ray images in a hard X-ray harsh environment and succeeded in obtaining clear images with X-ray framing camera and X-ray streak camera in fast ignition experiment conducted in 2011 (FG-02 Experimental Campaign. We found that high-energy X-ray signals could be used as an indicator of the LFEX laser injection time relative to the imploded core. The LFEX laser injection time was estimated with better than 10 ps accuracy. Time-resolved 2D X-ray images suggested that shapes and motions of imploded core plasmas were improved by changing the configuration of the implosion lasers.

  8. FAST CARS: engineering a laser spectroscopic technique for rapid identification of bacterial spores.

    Science.gov (United States)

    Scully, M O; Kattawar, G W; Lucht, R P; Opatrny, T; Pilloff, H; Rebane, A; Sokolov, A V; Zubairy, M S

    2002-08-20

    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on e.g., resonance fluorescence. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. However, generating and using maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is challenging. In particular, the short dephasing times and rapid internal conversion rates are major obstacles. However, adiabatic fast passage techniques and the ability to generate combs of phase-coherent femtosecond pulses provide tools for the generation and utilization of maximal quantum coherence in large molecules and biopolymers. We call this technique FAST CARS (femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman spectroscopy), and the present article proposes and analyses ways in which it could be used to rapidly identify preselected molecules in real time.

  9. Fast plasmonic laser nanowelding for a Cu-nanowire percolation network for flexible transparent conductors and stretchable electronics.

    Science.gov (United States)

    Han, Seungyong; Hong, Sukjoon; Ham, Jooyeun; Yeo, Junyeob; Lee, Jinhwan; Kang, Bongchul; Lee, Phillip; Kwon, Jinhyeong; Lee, Seung S; Yang, Min-Yang; Ko, Seung Hwan

    2014-09-01

    A facile fast laser nanoscale welding process uses the plasmonic effect at a nanowire (NW) junction to suppress oxidation and successfully fabricate a Cu-NW-based percolation-network conductor. The "nanowelding" process does not require an inert or vacuum environment. Due to the low-temperature and fast-process nature, plasmonic laser nanowelding may form Cu-nanowire networks on heat-sensitive, flexible or even stretchable substrates.

  10. Investigation of fast-ion generation in a laser plasma according to X-ray line radiation

    Science.gov (United States)

    Basov, N. G.; Maksimchuk, A. M.; Mikhailov, Iu. A.; Rode, A. V.; Getz, K.

    1987-04-01

    The profile of the 1s2-1s2p resonance line of the P XIV phosphorous ion is studied in order to derive the energy spectrum and indicatrix of fast ions in a laser plasma. The energetic and angular characteristics of fast ions are examined. The spectrum and indicatrix are analyzed using a model in which it is assumed that the ions are accelerated as a result of the self-focusing of laser radiation in the plasma corona.

  11. Bremsstrahlung measurements for characterization of intense short-pulse, laser produced fast electrons with OMEGA EP

    Science.gov (United States)

    Daykin, Tyler; Sawada, Hiroshi; Sentoku, Yasuhiko; Pandit, Rishi; Chen, Cliff; Beg, Farhat; Chen, Hui; McLean, Harry; Patel, Pravesh; Tommasini, Riccardo

    2016-10-01

    Understanding relativistic fast electron generation and transport inside solids is important for applications such as generation of high energy x-ray sources and fast ignition. An experiment was carried out to study the scaling of the fast electron spectrum and bremsstrahlung generation in multi-pico second laser interactions using 1 ps and 10 ps OMEGA EP short-pulse beam to generate fast electrons at a similar peak intensity of 5x1018 W/cm2. The bremsstrahlung produced by collisions of the fast electrons with background ions was recorded using differential filter stacked spectrometers. A preliminary analysis with a Monte Carlo Code ITS shows that the electrons injection having an electron slope 1.8 MeV matched well with the high energy component of the 1 ps and 10 ps bremsstrahlung measurements. Details of the data analysis and modeling with Monte Carlo and a hybrid particle-in-cell codes will be presented at the conference. Work supported by the UNR Office of the Provost and by DOE/OFES under Contract No. DE-SC0008827. This collaborative work was partially supported under the auspices of the US DOE by LLNL under Contracts No. DE-AC52-07NA27344 and No. DE-FG-02-05ER54834.

  12. Advanced Laser Particle Accelerator Development at LANL: From Fast Ignition to Radiation Oncology

    Science.gov (United States)

    Flippo, K. A.; Gaillard, S. A.; Kluge, T.; Bussmann, M.; Offermann, D. T.; Cobble, J. A.; Schmitt, M. J.; Bartal, T.; Beg, F. N.; Cowan, T. E.; Gall, B.; Gautier, D. C.; Geissel, M.; Kwan, T. J.; Korgan, G.; Kovaleski, S.; Lockard, T.; Malekos, S.; Montgomery, D. S.; Schollmeier, M.; Sentoku, Y.

    2010-11-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, Special Nuclear Material (SNM) detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high-current and high-energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology. Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent efficiencies of >5% from flat foils, on Trident using only a 5th of the intensity [1] and energy of the Nova Petawatt laser [2]. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world [3]. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  13. Experimental Research of Fast Proton Generation From Ultra-short Intense Laser Pulses Interaction With Different Thickness Al Foils

    Institute of Scientific and Technical Information of China (English)

    LAN; Xiao-fei; LU; Jian-xin; HUANG; Yong-sheng; WANG; Lei-jian; XI; Xiao-feng; TANG; Xiu-zhang

    2012-01-01

    <正>With the development of laser technology, the generation of fast ions by the interaction of ultra-short ultra-intense laser pulses with matters has recently been attracting considerable attention, especially for acceleration of proton. Before performing experiment, we calibrated the CR39 detector using standard proton beams from conventional accelerator. In the field of proton acceleration driven by ultra-short ultra-intense laser pulses,

  14. SMALL VOLUME LONG PULSE X RAY PREIONISED XeCl LASER WITH DOUBLE DISCHARGE AND FAST FERRITE MAGNETIC SWITCH

    OpenAIRE

    J. Hueber; Kobhio, M.; Fontaine, B.; Delaporte, Ph.; Sentis, M.; Forestier, B.

    1991-01-01

    Experimental results obtained with a high efficiency small volume long pulse X-Ray preionised XeCl laser with double discharge and very fast ferrite magnetic switch are presented and compared with the results given by a new XeCl laser numerical self consistant model. The model takes into account most recent kinetic data and time variation of discharge impedence and switch inductance. There is a good agreement between experiment and model on electrical and laser parameters for typical conditions.

  15. Implosion and heating experiments of fast ignition targets by Gekko-XII and LFEX lasers

    Directory of Open Access Journals (Sweden)

    Shiraga H.

    2013-11-01

    Full Text Available The FIREX-1 project, the goal of which is to demonstrate fuel heating up to 5 keV by fast ignition scheme, has been carried out since 2003 including construction and tuning of LFEX laser and integrated experiments. Implosion and heating experiment of Fast Ignition targets have been performed since 2009 with Gekko-XII and LFEX lasers. A deuterated polystyrene shell target was imploded with the 0.53- μm Gekko-XII, and the 1.053- μm beam of the LFEX laser was injected through a gold cone attached to the shell to generate hot electrons to heat the imploded fuel plasma. Pulse contrast ratio of the LFEX beam was significantly improved. Also a variety of plasma diagnostic instruments were developed to be compatible with harsh environment of intense hard x-rays (γ rays and electromagnetic pulses due to the intense LFEX beam on the target. Large background signals around the DD neutron signal in time-of-flight record of neutron detector were found to consist of neutrons via (γ,n reactions and scattered gamma rays. Enhanced neutron yield was confirmed by carefully eliminating such backgrounds. Neutron enhancement up to 3.5 × 107 was observed. Heating efficiency was estimated to be 10–20% assuming a uniform temperature rise model.

  16. Characterization of intense laser-produced fast electrons using hard x-rays via bremsstrahlung

    Science.gov (United States)

    Sawada, H.; Sentoku, Y.; Bass, A.; Griffin, B.; Pandit, R.; Beg, F.; Chen, H.; McLean, H.; Link, A. J.; Patel, P. K.; Ping, Y.

    2015-11-01

    Energy distribution of high-power, short-pulse laser produced fast electrons was experimentally and numerically studied using high-energy bremsstrahlung x-rays. The hard x-ray photons and escaping electrons from various metal foils, irradiated by the 50 TW Leopard laser at Nevada Terawatt Facility, were recorded with a differential filter stack spectrometer that is sensitive to photons produced by mainly 0.5-2 MeV electrons and an electron spectrometer measuring >2 MeV electrons. The experimental bremsstrahlung and the slope of the measured escaped electrons were compared with an analytic calculation using an input electron spectrum estimated with the ponderomotive scaling. The result shows that the electron spectrum entering a Cu foil could be continuous single slope with the slope temperature of ˜1.5 MeV in the detector range. The experiment and analytic calculation were then compared with a 2D particle-in-cell code, PICLS, including a newly developed radiation transport module. The simulation shows that a two-temperature electron distribution is generated at the laser interaction region, but only the hot component of the fast electrons flow into the target during the interaction because the low energy electron component is trapped by self-generated magnetic field in the preformed plasma. A significant amount of the photons less than 100 keV observed in the experiment could be attributed to the low energy electrons entering the foil a few picoseconds later after the gating field disappears.

  17. Integrated simulation of magnetic-field-assist fast ignition laser fusion

    Science.gov (United States)

    Johzaki, T.; Nagatomo, H.; Sunahara, A.; Sentoku, Y.; Sakagami, H.; Hata, M.; Taguchi, T.; Mima, K.; Kai, Y.; Ajimi, D.; Isoda, T.; Endo, T.; Yogo, A.; Arikawa, Y.; Fujioka, S.; Shiraga, H.; Azechi, H.

    2017-01-01

    To enhance the core heating efficiency in fast ignition laser fusion, the concept of relativistic electron beam guiding by external magnetic fields was evaluated by integrated simulations for FIREX class targets. For the cone-attached shell target case, the core heating performance deteriorates by applying magnetic fields since the core is considerably deformed and most of the fast electrons are reflected due to the magnetic mirror formed through the implosion. On the other hand, in the case of a cone-attached solid ball target, the implosion is more stable under the kilo-tesla-class magnetic field. In addition, feasible magnetic field configuration is formed through the implosion. As a result, the core heating efficiency doubles by magnetic guiding. The dependence of core heating properties on the heating pulse shot timing was also investigated for the solid ball target.

  18. Integrated simulation of magnetic-field-assist fast ignition laser fusion

    CERN Document Server

    Johzaki, T; Sunahara, A; Sakagami, Y Sentoku H; Hata, M; Taguchi, T; Mima, K; Kai, Y; Ajimi, D; Endo, T; Yogo, A; Arikawa, Y; Fujioka, S; Shiraga, H; Azechi, H

    2016-01-01

    To enhance the core heating efficiency in fast ignition laser fusion, the concept of relativistic electron beam guiding by external magnetic fields was evaluated by integrated simulations for FIREX class targets. For the cone-attached shell target case, the core heating performance is deteriorated by applying magnetic fields since the core is considerably deformed and the most of the fast electrons are reflected due to the magnetic mirror formed through the implosion. On the other hand, in the case of cone-attached solid ball target, the implosion is more stable under the kilo-tesla-class magnetic field. In addition, feasible magnetic field configuration is formed through the implosion. As the results, the core heating efficiency becomes double by magnetic guiding. The dependence of core heating properties on the heating pulse shot timing was also investigated for the solid ball target.

  19. Three-dimensional fast magnetic reconnection driven by relativistic ultraintense femtosecond lasers.

    Science.gov (United States)

    Ping, Y L; Zhong, J Y; Sheng, Z M; Wang, X G; Liu, B; Li, Y T; Yan, X Q; He, X T; Zhang, J; Zhao, G

    2014-03-01

    Three-dimensional fast magnetic reconnection driven by two ultraintense femtosecond laser pulses is investigated by relativistic particle-in-cell simulation, where the two paralleled incident laser beams are shot into a near-critical plasma layer to form a magnetic reconnection configuration in self-generated magnetic fields. A reconnection X point and out-of-plane quadrupole field structures associated with magnetic reconnection are formed. The reconnection rate is found to be faster than that found in previous two-dimensional Hall magnetohydrodynamic simulations and electrostatic turbulence contribution to the reconnection electric field plays an essential role. Both in-plane and out-of-plane electron and ion accelerations up to a few MeV due to the magnetic reconnection process are also obtained.

  20. Hole boring in a DT Pellet and Fast-Ion Ignition with Ultraintense Laser Pulses.

    Science.gov (United States)

    Naumova, N; Schlegel, T; Tikhonchuk, V T; Labaune, C; Sokolov, I V; Mourou, G

    2009-01-16

    Recently achieved high intensities of short laser pulses open new prospects in their application to hole boring in inhomogeneous overdense plasmas and for ignition in precompressed DT fusion targets. A simple analytical model and numerical simulations demonstrate that pulses with intensities exceeding 10;{22} W/cm;{2} may penetrate deeply into the plasma as a result of efficient ponderomotive acceleration of ions in the forward direction. The penetration depth as big as hundreds of microns depends on the laser fluence, which has to exceed a few tens of GJ/cm;{2}. The fast ions, accelerated at the bottom of the channel with an efficiency of more than 20%, show a high directionality and may heat the precompressed target core to fusion conditions.

  1. Fast blood flow visualization of high-resolution laser speckle imaging data using graphics processing unit.

    Science.gov (United States)

    Liu, Shusen; Li, Pengcheng; Luo, Qingming

    2008-09-15

    Laser speckle contrast analysis (LASCA) is a non-invasive, full-field optical technique that produces two-dimensional map of blood flow in biological tissue by analyzing speckle images captured by CCD camera. Due to the heavy computation required for speckle contrast analysis, video frame rate visualization of blood flow which is essentially important for medical usage is hardly achieved for the high-resolution image data by using the CPU (Central Processing Unit) of an ordinary PC (Personal Computer). In this paper, we introduced GPU (Graphics Processing Unit) into our data processing framework of laser speckle contrast imaging to achieve fast and high-resolution blood flow visualization on PCs by exploiting the high floating-point processing power of commodity graphics hardware. By using GPU, a 12-60 fold performance enhancement is obtained in comparison to the optimized CPU implementations.

  2. Fast magnetic energy dissipation in relativistic plasma induced by high order laser modes

    Institute of Scientific and Technical Information of China (English)

    Y.J.Gu; Q.Yu; O.Klimo; T.Zh.Esirkepov; S.V.Bulanov; S.Weber; G.Korn

    2016-01-01

    Fast magnetic field annihilation in a collisionless plasma is induced by using TEM(1,0) laser pulse. The magnetic quadrupole structure formation, expansion and annihilation stages are demonstrated with 2.5-dimensional particle-in-cell simulations. The magnetic field energy is converted to the electric field and accelerate the particles inside the annihilation plane. A bunch of high energy electrons moving backwards is detected in the current sheet. The strong displacement current is the dominant contribution which induces the longitudinal inductive electric field.

  3. Performance testing of log pile photonic crystal fast-fabricated by direct femtosecond laser writing

    Institute of Scientific and Technical Information of China (English)

    Haifeng Yang; Ming Zhou; Juan Dai; Jianke Di; Enlan Zhao

    2008-01-01

    Great efforts has been made on fabricating photonic crystals (PCs) with photonic band gaps (PBGs) during the past decade. Three-dimensional (31)) log pile PC was fabricated fast by direct femtosecond laser writing in ORMOCER. Qualitative analysis of the errors of PC was investigated using the Image Pro Plus. Surface qualities such as bending, distortion, and surface roughness were shown, and the band gap in the infrared wavelength region was observed. Meanwhile, the theory was experimentally verified that the center of PBG diminishes as the crystal lattice period reduces. Therefore, it is possible to fabricate PCs whose band gap range is from the near-infrared to visible wave band.

  4. Advanced laser particle accelerator development at LANL: from fast ignition to radiation oncology

    Energy Technology Data Exchange (ETDEWEB)

    Flippo, Kirk A [Los Alamos National Laboratory; Gaillard, Sandrine A [Los Alamos National Laboratory; Offermann, D T [Los Alamos National Laboratory; Cobble, J A [Los Alamos National Laboratory; Schmitt, M J [Los Alamos National Laboratory; Gautier, D C [Los Alamos National Laboratory; Kwan, T J T [Los Alamos National Laboratory; Montgomery, D S [Los Alamos National Laboratory; Kluge, Thomas [FZD-GERMANY; Bussmann, Micheal [FZD-GERMANY; Bartal, T [UCSD; Beg, F N [UCSD; Gall, B [UNIV OF MISSOURI; Geissel, M [SNL; Korgan, G [NANOLABZ; Kovaleski, S [UNIV OF MISSOURI; Lockard, T [UNIV OF NEVADA; Malekos, S [NANOLABZ; Schollmeier, M [SNL; Sentoku, Y [UNIV OF NEVADA; Cowan, T E [FZD-GERMANY

    2010-01-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, SN M detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high current and high energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology in conjunction with our partners at the ForschungsZentrum Dresden-Rossendorf (FZD). Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent etliciencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  5. Dynamics of fast pattern formation in porous silicon by laser interference

    Energy Technology Data Exchange (ETDEWEB)

    Peláez, Ramón J.; Kuhn, Timo; Afonso, Carmen N. [Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid (Spain); Vega, Fidel [Departament d' Òptica i Optometria, UPC, Violinista Vellsolà 37, 08222 Terrasa (Spain)

    2014-10-20

    Patterns are fabricated on 290 nm thick nanostructured porous silicon layers by phase-mask laser interference using single pulses of an excimer laser (193 nm, 20 ns pulse duration). The dynamics of pattern formation is studied by measuring in real time the intensity of the diffraction orders 0 and 1 at 633 nm. The results show that a transient pattern is formed upon melting at intensity maxima sites within a time <30 ns leading to a permanent pattern in a time <100 ns upon solidification at these sites. This fast process is compared to the longer one (>1 μs) upon melting induced by homogeneous beam exposure and related to the different scenario for releasing the heat from hot regions. The diffraction efficiency of the pattern is finally controlled by a combination of laser fluence and initial thickness of the nanostructured porous silicon layer and the present results open perspectives on heat release management upon laser exposure as well as have potential for alternative routes for switching applications.

  6. Fast photonic information processing using semiconductor lasers with delayed optical feedback: role of phase dynamics.

    Science.gov (United States)

    Nguimdo, Romain Modeste; Verschaffelt, Guy; Danckaert, Jan; Van der Sande, Guy

    2014-04-01

    Semiconductor lasers subject to delayed optical feedback have recently shown great potential in solving computationally hard tasks. By optically implementing a neuro-inspired computational scheme, called reservoir computing, based on the transient response to optical data injection, high processing speeds have been demonstrated. While previous efforts have focused on signal bandwidths limited by the semiconductor laser's relaxation oscillation frequency, we demonstrate numerically that the much faster phase response makes significantly higher processing speeds attainable. Moreover, this also leads to shorter external cavity lengths facilitating future on-chip implementations. We numerically benchmark our system on a chaotic time-series prediction task considering two different feedback configurations. The results show that a prediction error below 4% can be obtained when the data is processed at 0.25 GSamples/s. In addition, our insight into the phase dynamics of optical injection in a semiconductor laser also provides a clear understanding of the system performance at different pump current levels, even below solitary laser threshold. Considering spontaneous emission noise and noise in the readout layer, we obtain good prediction performance at fast processing speeds for realistic values of the noise strength.

  7. Ultrafast, high repetition rate, ultraviolet, fiber based laser source: application towards Yb+ fast quantum-logic

    CERN Document Server

    Hussain, Mahmood Irtiza; Bentley, Christopher D B; Taylor, Richard L; Carvalho, Andre R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

    2016-01-01

    Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb$^+$ ions faster than the trap period and with fidelity above 99%.

  8. Microstructure and lubricating property of ultra-fast laser pulse textured silicon carbide seals

    Science.gov (United States)

    Chen, Chien-Yu; Chung, Chung-Jen; Wu, Bo-Hsiung; Li, Wang-Long; Chien, Chih-Wei; Wu, Ping-Han; Cheng, Chung-Wei

    2012-05-01

    Most previous studies have employed surface patterning to improve the performance of lubrication systems. However, few have experimentally analyzed improved effects on friction reduction in SiC mechanical seals by ultra-fast laser pulse texturing. This work applies surface texturing on a non-contact mechanical seal and analyzes the characteristics of the resultant surface morphology. A femtosecond laser system is employed to fabricate micro/nanostructures on the SiC mechanical seal, and generates microscale-depth stripes and induces nanostructures on the seal surface. This work examines the morphology and cross section of the SiC nanostructures that correspond to the different scanning speeds of the laser pulse. Results show that varying the scanning speed enables the application of nanostructures of different amplitudes and widths on the surface of the seal. The friction coefficient of the introduced SiC full-textured seal is about 20% smaller than that of a conventional SiC mechanical seal. Hence, femtosecond laser texturing is effective and enables direct fabrication of the surface micro/nanostructures of SiC seals. This technique also serves as a potential approach to lubricating applications.

  9. Design and Analysis of a Fast Steering Mirror for Precision Laser Beams Steering

    Directory of Open Access Journals (Sweden)

    Qingkun ZHOU

    2009-03-01

    Full Text Available Precision laser beam steering is critical in numerous applications. Also, precise pointing of laser beams is essential in challenging environments. The optical signal may be deflected, drift and wander due to environmental influences. The core problem of steering performances is to deal with the jitter disturbance. Based on the analysis of the beam angle steering system, some important factors to design the structure of a Fast Steering Mirror (FSM and the layout of laser optics steering system are presented. Flexure hinges with compliant mechanisms are used to build the FSM structure. A 4-quadrant detector is used as the sensor for the incoming light. A design of the developed control loop and concepts of the FSM model are discussed. A comparison between the measured gain response and the simulation model of the FSM reveals similarity between the theoretical simulation model and the real system, and offers a way to improve the model to better resemble the real system. A laser beam jitter control test bed is also introduced to improve jitter control techniques.

  10. Beam engineering for zero conicity cutting and drilling with ultra fast laser (Conference Presentation)

    Science.gov (United States)

    Letan, Amelie; Mishchik, Konstantin; Audouard, Eric; Hoenninger, Clemens; Mottay, Eric P.

    2017-03-01

    With the development of high average power, high repetition rate, industrial ultrafast lasers, it is now possible to achieve a high throughput with femtosecond laser processing, providing that the operating parameters are finely tuned to the application. Femtosecond lasers play a key role in these processes, due to their ability to high quality micro processing. They are able to drill high thickness holes (up to 1 mm) with arbitrary shapes, such as zero-conicity or even inversed taper, but can also perform zero-taper cutting. A clear understanding of all the processing steps necessary to optimize the processing speed is a main challenge for industrial developments. Indeed, the laser parameters are not independent of the beam steering devices. Pulses energy and repetition rate have to be precisely adjusted to the beam angle with the sample, and to the temporal and spatial sequences of pulses superposition. The purpose of the present work is to identify the role of these parameters for high aspect ratio drilling and cutting not only with experimental trials, but also with numerical estimations, using a simple engineering model based on the two temperature description of ultra-fast ablation. Assuming a nonlinear logarithmic response of the materials to ultrafast pulses, each material can be described by only two adjustable parameters. Simple assumptions allow to predict the effect of beam velocity and non-normal incident beams to estimate profile shapes and processing time.

  11. Fundamental Studies on the Use of Laser-Driven Proton Beams for Fast Ignition

    Science.gov (United States)

    McGuffey, C.; Kim, J.; Beg, F. N.; Wei, M. S.; Chen, S. N.; Fuchs, J.; Nilson, P. M.; Theobald, W.; Habara, H.; Tanaka, K.; Yabuuchi, T.; Foord, M. E.; Patel, P. K.; McLean, H. S.; Roth, M.; McKenna, P.

    2015-11-01

    A short-pulse-laser-driven intense proton beam remains a candidate for Fast Ignition heater due to its focusability and high current. However, the proton current density necessary for FI in practice has never been produced in the laboratory and there are many physics issues that should be addressed using current and near-term facilities. For example, the extraction of sufficient proton charge from the short-pulse laser target could be evaluated with the multi-kilojoule NIF ARC laser. Transport of the beam through matter, such as a cone tip, and deposition in the fuel must be considered carefully as it will isochorically heat any material it enters and produce a rapidly-evolving, warm dense matter state with uncertain transport and stopping properties. Here we share experimental measurements of the proton spectra after passing through metal cones and foils taken with the kilojoule-class, multi-picosecond OMEGA EP and LFEX lasers. We also present complementary PIC simulations of beam generation and transport to and in the foils. Upcoming experiments to further evaluate proton beam performance in proton FI will also be outlined. This work was supported by the DOE/NNSA NLUF program, Contract DE-NA0002034 and by the AFOSR under Contract FA9550-14-1-0346.

  12. Ultra Intense Laser Pulse Interactions with Planer and Spherical Plasmas for Fast Ignitor

    Science.gov (United States)

    Tanaka, Kazuo A.

    1999-11-01

    The fast ignitor concept requires the guiding or penetration of an ultra-intense laser close to a highly compressed (1000 times solid density) core and the generation of energetic electrons (MeV). Ultra-intense laser plasma interactions have been intensively studied using the Peta Watt Module (PWM) laser system synchronized with the GEKKO XII laser system. The ultra-intense laser pulse of 50J energy, 0.5-1 psec pulse width and 1053 nm laser wavelength could be focused onto a preformed plasma created on a solid target at an intensity of 1e19 W/cm2. The preformed plasma had a cut-off density surface at around 100 micron from the surface. Changing the focus position of this 100 TW laser pulse relative to the preformed plasma, we found an anomalous mode. Side view of x-ray pinhole camera showed that there was a local tiny spot almost at the surface of the solid target which indicates the propagation of the pulse in the long scale-length plasma into an over-dense region for over 100 micorn distance. The erergy spectrum and angular distribution of more than MeV electrons were measured. Its energy transport was studied with K-a spectroscopy. The backscattered light of the ultra-intense laser light was spectrally and spatially resolved. The backscattered light image showed several hot spots within the focused region. The spatilally resolved spectra of the backscattered light were totally different at the hot spots and surrounding regions. The details of neutron spectra were measured using ``MANDALA" neutron spectormeters with a total of 841 channel photo-multiplier detectors. The data indicates that deuterium ions were accelerated by the hot electrons up to 100 keV and created beam fusion reactions within solid CD targets. Guiding channels were created utilizing a ponderomotive self-focusing in preformed plasmas created on a solid target. The self-focus channel was measured by both UV and x-ray laser probes. The details of the experiment as well as the theoretical

  13. Detection of seam tracking offset based on infrared image during high-power fiber laser welding%大功率光纤激光焊焊缝跟踪偏差红外检测方法

    Institute of Scientific and Technical Information of China (English)

    高向东; 莫玲; 仲训杲; 游德勇; Katayama Seiji

    2011-01-01

    精确控制激光束使其始终对准并跟踪焊缝是保证激光焊接质量的前提.针对大功率(激光功率10kW)光纤激光焊接304型不锈钢紧密对接焊缝(间隙为0—0.1mm),研究一种基于红外热像的焊缝跟踪偏差检测新方法.采用红外传感高速摄像机摄取焊接区域熔池红外动态热像,分析激光束对准和偏离焊缝中心时的熔池温度分布和红外辐射特性,以熔池匙孔形变参数和热堆积效应参数作为激光束与焊缝中心偏差检测特征值,通过图像识别技术研究和分析特征值与焊缝偏差之间的关系.激光焊接试验结果表明,熔池匙孔形变参数和热堆积效应参数与焊缝偏差之间存在%Seam tracking is a significant precondition to obtain good welding quality.During the laser welding,the laser beam focus must be controlled to follow the welding seam accurately.A novel approach to detecting the offset between the laser beam focus and the welding seam based on infrared image processing is investigated during high-power fiber laser butt-joint welding of type 304 austenitic stainless steel plates at a continuous wave fiber laser power of 10 kW.The joint gap width is less than 0.1 mm.An infrared sensitive high speed camera arranged in off-axis direction of laser beam is used to capture the dynamic thermal images of a molten pool.The characteristics of thermal distribution and infrared radiation of the molten pool,when the laser beam focus is deviated from the welding seam center,are analyzed.Two parameters called the keyhole morphological parameter and the heat accumulation effect parameter are defined as the characteristic values of seam tracking offset to determine the offset between the laser beam focus and the desired welding seam.Also,the image processing technique is used to analyze the infrared images of the molten pool,which indicates the presence of mathematic correlation between the defined two parameters and the seam tracking

  14. FAST

    DEFF Research Database (Denmark)

    Zuidmeer-Jongejan, Laurian; Fernandez-Rivas, Montserrat; Poulsen, Lars K.

    2012-01-01

    ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections with aqu......ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections...... with aqueous food extracts may be effective but has proven to be accompanied by too many anaphylactic side-effects. FAST aims to develop a safe alternative by replacing food extracts with hypoallergenic recombinant major allergens as the active ingredients of SIT. Both severe fish and peach allergy are caused...... in depth serological and cellular immune analyses will be performed, allowing identification of novel biomarkers for monitoring treatment efficacy. FAST aims at improving the quality of life of food allergic patients by providing a safe and effective treatment that will significantly lower their threshold...

  15. Ion acceleration by petawatt class laser pulses and pellet compression in a fast ignition scenario

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C. [Dipartimento di Fisica, Universita di Bologna, INFN sezione di Bologna (Italy)], E-mail: benedetti@bo.infn.it; Londrillo, P. [Dipartimento di Astronomia, Universita di Bologna, INAF sezione di Bologna, INFN sezione di Bologna (Italy); Liseykina, T.V. [Institute for Computational Technologies, SD-RAS, Novosibirsk (Russian Federation); Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Macchi, A. [polyLAB, CNR-INFM, Pisa (Italy); Sgattoni, A.; Turchetti, G. [Dipartimento di Fisica, Universita di Bologna, INFN sezione di Bologna (Italy)

    2009-07-11

    Ion drivers based on standard acceleration techniques have faced up to now several difficulties. We consider here a conceptual alternative to more standard schemes, such as HIDIF (Heavy Ion Driven Inertial Fusion), which are still beyond the present state of the art of particle accelerators, even though the requirements on the total beam energy are lowered by fast ignition scenarios. The new generation of petawatt class lasers open new possibilities: acceleration of electrons or protons for the fast ignition and eventually light or heavy ions acceleration for compression. The pulses of chirped pulse amplification (CPA) lasers allow ions acceleration with very high efficiency at reachable intensities (I{approx}10{sup 21}W/cm{sup 2}), if circularly polarized light is used since we enter in the radiation pressure acceleration (RPA) regime. We analyze the possibility of accelerating carbon ion bunches by interaction of a circularly polarized pulses with an ultra-thin target. The advantage would be compactness and modularity, due to identical accelerating units. The laser efficiency required to have an acceptable net gain in the inertial fusion process is still far from the presently achievable values both for CPA short pulses and for long pulses used for direct illumination. Conversely the energy conversion efficiency from the laser pulse to the ion bunch is high and grows with the intensity. As a consequence the energy loss is not the major concern. For a preliminary investigation of the ions bunch production we have used the PIC code ALaDyn developed to analyze the results of the INFN-CNR PLASMONX experiment at Frascati National Laboratories (Rome, Italy) where the 0.3 PW laser FLAME will accelerate electrons and protons. We present the results of some 1D simulations and parametric scan concerning the acceleration of carbon ions that we suppose to be fully ionized. Circularly polarized laser pulses of 50 J and 50-100 fs duration, illuminating a 100{mu}m{sup 2} area

  16. Study of Nuclear Moments and Mean Square Charge Radii by Collinear Fast-Beam Laser Spectroscopy

    CERN Multimedia

    2002-01-01

    The collinear fast-beam laser technique is used to measure atomic hyperfine structures and isotope shifts of unstable nuclides produced at ISOLDE. This gives access to basic nuclear ground-state and isomeric-state properties such as spins, magnetic dipole and electric quadrupole moments, and the variation of the nuclear mean square charge radius within a sequence of isotopes. \\\\ \\\\ Among the various techniques used for this purpose, the present approach is of greatest versatility, due to the direct use of the beams from the isotope separator. Their phase-space properties are exploited to achieve high sensitivity and resolution. The optical spectra of neutral atoms are made accessible by converting the ion beams into fast atomic beams. This is accomplished in the charge-exchange cell which is kept at variable potential ($\\pm$10~kV) for Doppler-tuning of the effective laser wavelength. The basic optical resolution of 10$^{-8}$ requires a 10$^{-5}$ stability of the 60~kV main acceleration voltage and low energy ...

  17. Offset drilling obligations

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, K.D.; Kalmakoff, J.J. [Kanuka Thuringer, Regina, SK (Canada)

    1998-12-31

    A review of the `offset well` clause found in freehold and Crown natural gas and petroleum leases was presented. The objective was to provide lessors and lessees with a clear understanding of the rights and obligations associated with offset wells. It was noted that offset well obligations vary according to the form of lease used, the type of offsetting well, the regulatory regime and the geophysical characteristics of the producing formation. Some suggestions were made as to how current versions of the offset well clause can be amended to overcome some of the problems encountered in applying the clause to an offset horizontal well that has been drilled on adjoining lands. Failure to resolve the new issues presented by horizontal drilling technology in terms of documentation, which records respective rights and obligations on the basis of generally accepted principles, will result in large numbers of conflicts and unnecessary litigation. 144 refs., 1 fig.

  18. A fast single-pixel laser imager for VR/AR headset tracking

    Science.gov (United States)

    Milanović, Veljko; Kasturi, Abhishek; Yang, James; Hu, Frank

    2017-02-01

    In this work we demonstrate a highly flexible laser imaging system for 3D sensing applications such as in tracking of VR/AR headsets, hands and gestures. The system uses a MEMS mirror scan module to transmit low power laser pulses over programmable areas within a field of view and uses a single photodiode to measure the reflected light. User can arbitrarily select the number of pixels to scan over an area and can thus obtain images of target objects at arbitrarily fast rates. The work builds on the previously presented "MEMSEye" laser tracking technology which uses a fast steering MEMS scan module with a modulated laser, and a tuned photosensor to acquire and track a retroreflector-marked object. To track VR/AR headsets, hands and similar objects with multiple markers or no markers at all, a single-point tracking methodology is not sufficient. Cameras could be more appropriate in such multi-point imaging cases but suffer from low frame rates, dependence on ambient lighting, and relatively low resolution when without zooming and panning capability. A hybrid method can address the problem by providing a system with its own light source (laser beam), and with full programmability of the pixel locations and scans such that frame rates of >100 Hz are possible over specific areas of interest. With a modest 1 Mpixel rate of measurement, scanning a sub-region of the field of view with 64 x 64 pixels results in 200Hz update. Multiple such modules can be used to scan and image or track objects with multiple markers and fully obtain their position and attitude in a room with sub-5ms updates. Furthermore the room itself could be imaged and measured with wall markers or in conjunction with a camera for a total 3D scanning solution. Proof of concept demonstrator is presented here with pixel rates of only 30k-50k per second due to limitations of the present prototype electronics, resulting in refresh rates that are significantly lower than possible with the MEMS mirror scan

  19. Hybrid Simulation of Laser-Plasma Interactions and Fast Electron Transport in Inhomogeneous Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B I; Kemp, A; Divol, L

    2009-05-27

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogenous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  20. Planetary Surface Analysis Using Fast Laser Spectroscopic Techniques: Combined Microscopic Raman, LIBS, and Fluorescence Spectroscopy

    Science.gov (United States)

    Blacksberg, J.; Rossman, G. R.; Maruyama, Y.; Charbon, E.

    2011-12-01

    In situ exploration of planetary surfaces has to date required multiple techniques that, when used together, yield important information about their formation histories and evolution. We present a time-resolved laser spectroscopic technique that could potentially collect complementary sets of data providing information on mineral structure, composition, and hydration state. Using a picosecond-scale pulsed laser and a fast time-resolved detector we can simultaneously collect spectra from Raman, Laser Induced Breakdown Spectroscopy (LIBS), and fluorescence emissions that are separated in time due to the unique decay times of each process. The use of a laser with high rep rate (40 KHz) and low pulse energy (1 μJ/pulse) allows us to rapidly collect high signal to noise Raman spectra while minimizing sample damage. Increasing the pulse energy by about an order of magnitude creates a microscopic plasma near the surface and enables the collection of LIBS spectra at an unusually high rep rate and low pulse energy. Simultaneously, broader fluorescence peaks can be detected with lifetimes varying from nanosecond to microsecond. We will present Raman, LIBS, and fluorescence spectra obtained on natural mineral samples such as sulfates, clays, pyroxenes and carbonates that are of interest for Mars mineralogy. We demonstrate this technique using a photocathode-based streak camera detector as well as a newly-developed solid state Single Photon Avalanche Diode (SPAD) sensor array based on Complementary Metal-Oxide Semiconductor (CMOS) technology. We will discuss the impact of system design and detector choice on science return of a potential planetary surface mission, with a specific focus on size, weight, power, and complexity. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).

  1. Self-starting mode-locked picosecond Ti:sapphire laser by using of a fast SESAM

    Institute of Scientific and Technical Information of China (English)

    Zhu Jiang-Feng; Tian Jin-Rong; Wang Peng; Ling Wei-Jun; Li De-Hua; Wei Zhi-Yi

    2006-01-01

    A stable continuous wave mode-locked picosecond Ti:sapphire laser by using a fast semiconductor saturable absorber mirror (SESAM) is demonstrated. The laser delivers pulse width of 20 ps at a central wavelength of 813 nm and a repetition rate of 100 MHz. The maximum output power is 1.34 W with pump power of 7 W which corresponds to an optical-optical conversion efficiency of 19.1%.

  2. Offset Printing, Course Description.

    Science.gov (United States)

    Bly, Ervin; Anderson, Floyd L.

    Prepared by an instructor and a curriculum development specialist, this course of study was designed to meet the individual needs of the dropout and/or hard-core unemployed youth by providing skill training, related information, and supportive services knowledge about offset printing. The course provides training in offset printing and related…

  3. High-energy-density plasmas generation on GEKKO-LFEX laser facility for fast-ignition laser fusion studies and laboratory astrophysics

    Science.gov (United States)

    Fujioka, S.; Zhang, Z.; Yamamoto, N.; Ohira, S.; Fujii, Y.; Ishihara, K.; Johzaki, T.; Sunahara, A.; Arikawa, Y.; Shigemori, K.; Hironaka, Y.; Sakawa, Y.; Nakata, Y.; Kawanaka, J.; Nagatomo, H.; Shiraga, H.; Miyanaga, N.; Norimatsu, T.; Nishimura, H.; Azechi, H.

    2012-12-01

    The world's largest peta watt (PW) laser LFEX, which delivers energy up to 2 kJ in a 1.5 ps pulse, has been constructed beside the GEKKO XII laser at the Institute of Laser Engineering, Osaka University. The GEKKO-LFEX laser facility enables the creation of materials having high-energy-density which do not exist naturally on the Earth and have an energy density comparable to that of stars. High-energy-density plasma is a source of safe, secure, environmentally sustainable fusion energy. Direct-drive fast-ignition laser fusion has been intensively studied at this facility under the auspices of the Fast Ignition Realization Experiment (FIREX) project. In this paper, we describe improvement of the LFEX laser and investigations of advanced target design to increase the energy coupling efficiency of the fast-ignition scheme. The pedestal of the LFEX pulse, which produces a long preformed plasma and results in the generation of electrons too energetic to heat the fuel core, was reduced by introducing an amplified optical parametric fluorescence quencher and saturable absorbers in the front-end system of the LFEX laser. Since fast electrons are scattered and stopped by the strong electric field of highly ionized high-Z (i.e. gold) ions, a low-Z cone was studied for reducing the energy loss of fast electrons in the cone tip region. A diamond-like carbon cone was fabricated for the fast-ignition experiment. An external magnetic field, which is demonstrated to be generated by a laser-driven capacitor-coil target, will be applied to the compression of the fuel capsule to form a strong magnetic field to guide the fast electrons to the fuel core. In addition, the facility offers a powerful means to test and validate astronomical models and computations in the laboratory. As well as demonstrating the ability to recreate extreme astronomical conditions by the facilities, our theoretical description of the laboratory experiment was compared with the generally accepted explanation

  4. Evidence for ultra-fast heating in intense-laser irradiated reduced-mass targets

    Energy Technology Data Exchange (ETDEWEB)

    Neumayer, P.; Gumberidze, A.; Hochhaus, D. C. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt am Main (Germany); Aurand, B.; Stoehlker, T. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Costa Fraga, R. A.; Kalinin, A. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Ecker, B. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Grisenti, R. E. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Kaluza, M. C. [Helmholtz Institute Jena, 07743 Jena (Germany); IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Kuehl, T. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Polz, J. [IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Reuschl, R. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Winters, D.; Winters, N.; Yin, Z. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany)

    2012-12-15

    We report on an experiment irradiating individual argon droplets of 20 {mu}m diameter with laser pulses of several Joule energy at intensities of 10{sup 19} W/cm{sup 2}. K-shell emission spectroscopy was employed to determine the hot electron energy fraction and the time-integrated charge-state distribution. Spectral fitting indicates that bulk temperatures up to 160 eV are reached. Modelling of the hot-electron relaxation and generation of K-shell emission with collisional hot-electron stopping only is incompatible with the experimental results, and the data suggest an additional ultra-fast (sub-ps) heating contribution. For example, including resistive heating in the modelling yields a much better agreement with the observed final bulk temperature and qualitatively reproduces the observed charge state distribution.

  5. Analysis of Nickel Based Hardfacing Materials Manufactured by Laser Cladding for Sodium Fast Reactor

    Science.gov (United States)

    Aubry, P.; Blanc, C.; Demirci, I.; Dal, M.; Malot, T.; Maskrot, H.

    For improving the operational capacity, the maintenance and the decommissioning of the future French Sodium Fast Reactor ASTRID which is under study, it is asked to find or develop a cobalt free hardfacing alloy and the associated manufacturing process that will give satisfying wear performances. This article presents recent results obtained on some selected nickel-based hardfacing alloys manufactured by laser cladding, particularly on Tribaloy 700 alloy. A process parameter search is made and associated the microstructural analysis of the resulting clads. A particular attention is made on the solidification of the main precipitates (chromium carbides, boron carbides, Laves phases,…) that will mainly contribute to the wear properties of the material. Finally, the wear resistance of some samples is evaluated in simple wear conditions evidencing promising results on tribology behavior of Tribaloy 700.

  6. 640-Gbit/s fast physical random number generation using a broadband chaotic semiconductor laser

    Science.gov (United States)

    Zhang, Limeng; Pan, Biwei; Chen, Guangcan; Guo, Lu; Lu, Dan; Zhao, Lingjuan; Wang, Wei

    2017-01-01

    An ultra-fast physical random number generator is demonstrated utilizing a photonic integrated device based broadband chaotic source with a simple post data processing method. The compact chaotic source is implemented by using a monolithic integrated dual-mode amplified feedback laser (AFL) with self-injection, where a robust chaotic signal with RF frequency coverage of above 50 GHz and flatness of ±3.6 dB is generated. By using 4-least significant bits (LSBs) retaining from the 8-bit digitization of the chaotic waveform, random sequences with a bit-rate up to 640 Gbit/s (160 GS/s × 4 bits) are realized. The generated random bits have passed each of the fifteen NIST statistics tests (NIST SP800-22), indicating its randomness for practical applications. PMID:28374860

  7. Fast electron generation by Coulomb scattering on spatially correlated ions in a strong laser field

    CERN Document Server

    Bauch, S

    2009-01-01

    Electrons colliding with spatially fixed ions in strong laser fields are investigated by solving the time-dependent Schr\\"odinger equation. Considering first simple one-dimensional model systems, the mechanisms and energy spectra of fast electrons are analyzed, starting from collisions on a single ion. By using these electrons as projectiles for a second and third collision, the maximum possible energy obtained can be significantly increased. We then generalize the analysis to 2D systems where additional angular degrees of freedom lead to a drastic loss of efficiency. This problem can be overcome by introducing external confinements, which allow to focus the electrons and increase the intensity of high-energy electrons.

  8. Fast gated imaging of the collisionless interaction of a laser-produced and magnetized ambient plasma

    Science.gov (United States)

    Heuer, P. V.; Schaeffer, D. B.; Knall, E. N.; Constantin, C. G.; Hofer, L. R.; Vincena, S.; Tripathi, S.; Niemann, C.

    2017-03-01

    The collisionless interaction between a laser-produced carbon plasma (LPP) and an ambient hydrogen plasma in a background magnetic field was studied in a high shot rate experiment which allowed large planar data sets to be collected. Plasma fluorescence was imaged with a fast-gated camera with and without carbon line filters. The resulting images were compared to high-resolution two dimensional (2D) data planes of measured magnetic field and electric potential. Several features in the fluorescence images coincide with features in the field data. Relative intensity was used to determine the initial angular velocity distribution of the LPP and the growth rate of instabilities. These observations may be applied to understand fluorescence images from similar experiments where 2D planes of field data are not available.

  9. Evolution of the angular distribution of laser-generated fast electrons due to resistive self-collimation

    Science.gov (United States)

    Robinson, A. P. L.; Schmitz, H.

    2015-10-01

    The evolution of the angular distribution of laser-generated fast electrons propagating in dense plasmas is studied by 3D numerical simulations. As resistively generated magnetic fields can strongly influence and even pinch the fast electron beam, the question of the effect on the angular distribution is of considerable interest. It was conjectured that in the limit of strong collimation, there will only be minimal changes to the angular distribution, whereas the largest reduction in the angular distribution will occur where there is only modest pinching of the fast electron beam and the beam is able to expand considerably. The results of the numerical simulations indicate this conjecture.

  10. Rapid Embedded Wire Heating via Resistive Guiding of Laser-Generated Fast Electrons as a Hydrodynamic Driver

    CERN Document Server

    Robinson, A P L; Pasley, J

    2014-01-01

    Resistively guiding laser-generated fast electron beams in targets consisting of a resistive wire embedded in lower $Z$ material should allow one to rapidly heat the wire to over 100eV over a substantial distance without strongly heating the surrounding material. On the multi-ps timescale this can drive hydrodynamic motion in the surrounding material. Thus ultra-intense laser solid interactions have the potential as a controlled driver of radiation hydrodynamics in solid density material. In this paper we assess the laser and target parameters needed to achieve such rapid and controlled heating of the embedded wire.

  11. Fast Tuneable InGaAsP DBR Laser Using Quantum-Confined Stark-Effect-Induced Refractive Index Change

    OpenAIRE

    Pantouvaki, M.; Renaud, C. C.; Cannard, P; Robertson, M. J.; Gwilliam, R; Seeds, A. J.

    2007-01-01

    We report a monolithically integrated InGaAsP DBR ridge waveguide laser that uses the quantum-confined Stark effect (QCSE) to achieve fast tuning response. The laser incorporates three sections: a forward-biased gain section, a reverse-biased phase section, and a reverse-biased DBR tuning section. The laser behavior is modeled using transmission matrix equations and tuning over similar to 8 nm is predicted. Devices were fabricated using post-growth shallow ion implantation to reduce the loss ...

  12. 光束偏移量对钛/铝异种合金激光焊接接头组织和性能的影响%Influence of laser offset on microstructure and mechanical properties of Ti/Al dissimilar joint by laser welding

    Institute of Scientific and Technical Information of China (English)

    宋志华; 吴爱萍; 姚为; 邹贵生; 任家烈; 汪永阳

    2013-01-01

    Laser welding of TA15 and 5A06 alloys with 3 mm in thickness was conducted by focusing laser beam on titanium side, and the aluminum was melted through the heat conduction from titanium side. The effect of laser offset distance on microstructure and mechanical properties of the dissimilar butt joint was investigated. When the laser offset is 0. 1-0. 4 mm, fusion welded joint is formed. When the laser offset is 0.5 mm, fusion welded joint is formed on the upper side of the joint accompanying with Ti-Al intermetallic compounds. Welded-brazed joint is formed on the middle and bottom side of the joint accompanying with continuous Ti-Al intermetallic compounds layer with 1 μm thickness. The tensile strength of joints firstly increased and then decreased with the laser offset increasing. The highest average tensile strength of the joint reaches 181 MPa when the laser offset distance is 0. 5 mm. The joints partly fracture in Ti-Al intermetallic compounds at the interface, and partly fracture at the fusion zone of aluminum alloy.%采用激光进行3mm厚钛合金TA15和铝合金5A06的对接焊,激光束聚焦在钛合金上使钛合金熔化,通过热传导使铝合金熔化,得到了成形良好的接头,分析了光束偏移量对接头组织和性能的影响规律.偏移量为0.1 ~0.4 mm时,形成了熔焊接头.偏移量为0.5mm时,接头上部形成熔焊接头,并形成了Ti-Al金属间化合物.接头中部和下部形成了熔钎焊接头,并形成了一层连续的约1 μm厚的金属间化合物.接头抗拉强度随偏移量的增加先增大后减小,偏移量为0.5mm时,接头强度最大,平均抗拉强度可达到181 MPa,接头部分断裂于钛/铝界面的金属间化合物处,部分断裂于铝合金焊缝区.

  13. Fast Prototyping of Sensorized Cell Culture Chips and Microfluidic Systems with Ultrashort Laser Pulses

    Directory of Open Access Journals (Sweden)

    Sebastian M. Bonk

    2015-03-01

    Full Text Available We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO plating or were prepared from platinum sputtering (100 nm onto a 10-nm titanium adhesion layer. Direct processing of the sensor structures (approximately three minutes per chip by an ultrashort pulse laser facilitated the production of the prototypes. pH-sensitive areas were produced by the sputtering of 60-nm Si3N4 through a simple mask made from a circuit board material. The system body and polydimethylsiloxane (PDMS molding forms for the microfluidic structures were manufactured by micromilling using a printed circuit board (PCB milling machine for circuit boards. The microfluidic structure was finally imprinted in PDMS. Our approach avoided the use of photolithographic techniques and enabled fast and cost-efficient prototyping of the systems. Alternatively, the direct production of metallic, ceramic or polymeric molding tools was tested. The use of ultrashort pulse lasers improved the precision of the structures and avoided any contact of the final structures with toxic chemicals and possible adverse effects for the cell culture in lab-on-a-chip systems.

  14. A laser diode based system for calibration of fast time-of-flight detectors

    CERN Document Server

    Bonesini, M; deBari, A; Rossella, M

    2016-01-01

    A system based on commercially available items, such as a laser diode, emitting in the visible range $\\sim 400$ nm,and multimode fiber patches, fused fiber splitters and optical switches may be assembled,for time calibration of multi-channels time-of-flight (TOF) detectors with photomultipliers' (PMTs') readout. As available laser diode sources have unfortunately limited peak power, the main experimental problem is the tight light power budget of such a system. In addition, while the technology for fused fiber splitters is common in the Telecom wavelength range ($\\lambda \\sim 850, 1300-1500$ nm), it is not easily available in the visible one. Therefore, extensive laboratory tests had to be done on purpose, to qualify the used optical components, and a full scale timing calibration prototype was built. Obtained results show that with such a system, a calibration resolution ($\\sigma$) in the range 20-30 ps may be within reach. Therefore, fast multi-channels TOF detectors, with timing resolutions in the range 50...

  15. A laser diode based system for calibration of fast time-of-flight detectors

    Science.gov (United States)

    Bertoni, R.; Bonesini, M.; de Bari, A.; Rossella, M.

    2016-05-01

    A system based on commercially available items, such as a laser diode, emitting in the visible range ~ 400 nm, and multimode fiber patches, fused fiber splitters and optical switches may be assembled, for time calibration of multi-channels time-of-flight (TOF) detectors with photomultipliers' (PMTs') readout. As available laser diode sources have unfortunately limited peak power, the main experimental problem is the tight light power budget of such a system. In addition, while the technology for fused fiber splitters is common in the Telecom wavelength range (λ ~ 850, 1300-1500 nm), it is not easily available in the visible one. Therefore, extensive laboratory tests had to be done on purpose, to qualify the used optical components, and a full scale timing calibration prototype was built. Obtained results show that with such a system, a calibration resolution (σ) in the range 20-30 ps may be within reach. Therefore, fast multi-channels TOF detectors, with timing resolutions in the range 50-100 ps, may be easily calibrated in time. Results on tested optical components may be of interest also for time calibration of different light detection systems based on PMTs, as the ones used for detection of the vacuum ultraviolet scintillation light emitted by ionizing particles in large LAr TPCs.

  16. Hollow fiber based quantum cascade laser spectrometer for fast and sensitive drug identification

    Science.gov (United States)

    Herbst, J.; Scherer, B.; Ruf, A.; Erb, J.; Lambrecht, A.

    2012-01-01

    Sensitive and fast identification of drugs or drug precursors is important and necessary in scenarios like baggage or container check by customs or police. Fraunhofer IPM is developing a laser spectrometer using external cavity quantum cascade lasers (EC-QCL) to obtain mid-infrared (IR) absorption spectra in the wavelength range of the specific vibrational bands of amphetamines and their precursors. The commercial EC-QCL covers a tuning range of about 225 cm-1 within 1.4 s. The system could be used for different sample types like bulk samples or liquid solutions. A sampling unit evaporates the sample. Because of small sample amounts a 3 m long hollow fiber with an inner volume smaller than 1ml is used as gas cell and wave guide for the laser beam. This setup is suitable as a detector of a gas chromatograph instead of a standard detector (TCD or FID). The advantage is the selective identification of drugs by their IR spectra in addition to the retention time in the gas chromatographic column. In comparison to Fourier Transform IR systems the EC-QCL setup shows a good mechanical robustness and has the advantage of a point light source. Because of the good fiber incoupling performance of the EC-QCL it is possible to use hollow fibers. So, a good absorption signal is achieved because of the long optical path in the small cell volume without significant dilution. In first laboratory experiments a detection limit in the microgram range for pseudo ephedrine is achieved.

  17. Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

    Directory of Open Access Journals (Sweden)

    Hery Suyanto

    2016-08-01

    Full Text Available A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns and picosecond (ps lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS using He ambient gas.

  18. Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

    Science.gov (United States)

    Suyanto, Hery; Pardede, Marincan; Hedwig, Rinda; Marpaung, Alion Mangasi; Ramli, Muliadi; Lie, Tjung Jie; Abdulmadjid, Syahrun Nur; Kurniawan, Koo Hendrik; Tjia, May On; Kagawa, Kiichiro

    2016-08-01

    A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns) and picosecond (ps) lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE) mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS) using He ambient gas.

  19. Fast in situ phase and stress analysis during laser surface treatment: a synchrotron x-ray diffraction approach.

    Science.gov (United States)

    Kostov, V; Gibmeier, J; Wilde, F; Staron, P; Rössler, R; Wanner, A

    2012-11-01

    An in situ stress analysis by means of synchrotron x-ray diffraction was carried out during laser surface hardening of steel. A single exposure set-up that based on a special arrangement of two fast silicon strip line detectors was established, allowing for fast stress analysis according to the sin(2)ψ x-ray analysis method. For the in situ experiments a process chamber was designed and manufactured, which is described in detail. First measurements were carried out at the HZG undulator imaging beamline (IBL, beamline P05) at the synchrotron storage ring PETRA III, DESY, Hamburg (Germany). The laser processing was carried out using a 6 kW high power diode laser system. Two different laser optics were compared, a Gaussian optic with a focus spot of ø 3 mm and a homogenizing optic with a rectangular spot dimension of 8 × 8 mm(2). The laser processing was carried out using spot hardening at a heating-/cooling rate of 1000 K/s and was controlled via pyrometric temperature measurement using a control temperature of 1150 °C. The set-up being established during the measuring campaign allowed for this first realization data collection rates of 10Hz. The data evaluation procedure applied enables the separation of thermal from elastic strains and gains unprecedented insight into the laser hardening process.

  20. Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

    Energy Technology Data Exchange (ETDEWEB)

    Suyanto, Hery [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Hedwig, Rinda [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Marpaung, Alion Mangasi [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, Rawamangun, Jakarta 12440 (Indonesia); Ramli, Muliadi [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Lie, Tjung Jie; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Abdulmadjid, Syahrun Nur [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha,Bandung 40132 (Indonesia); Kagawa, Kiichiro [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Fukui Science Education Academy, Takagi Chuo 2 chome, Fukui 910-0804 (Japan)

    2016-08-15

    A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns) and picosecond (ps) lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE) mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS) using He ambient gas.

  1. Proton- and x-ray beams generated by ultra-fast CO2 lasers for medical applications

    Science.gov (United States)

    Pogorelsky, Igor; Polyanskiy, Mikhail; Yakimenko, Vitaly; Ben-Zvi, Ilan; Shkolnikov, Peter; Najmudin, Zulfikar; Palmer, Charlotte A. J.; Dover, Nicholas P.; Oliva, Piernicola; Carpinelli, Massimo

    2011-05-01

    Recent progress in using picosecond CO2 lasers for Thomson scattering and ion-acceleration experiments underlines their potentials for enabling secondary radiation- and particle- sources. These experiments capitalize on certain advantages of long-wavelength CO2 lasers, such as higher number of photons per energy unit, and favorable scaling of the electrons' ponderomotive energy and critical plasma density. The high-flux x-ray bursts produced by Thomson scattering of the CO2 laser off a counter-propagating electron beam enabled high-contrast, time-resolved imaging of biological objects in the picosecond time frame. In different experiments, the laser, focused on a hydrogen jet, generated monoenergetic proton beams via the radiation-pressure mechanism. The strong power-scaling of this regime promises realization of proton beams suitable for laser-driven proton cancer therapy after upgrading the CO2 laser to sub-PW peak power. This planned improvement includes optimizing the 10-μm ultra-short pulse generation, assuring higher amplification in the CO2 gas under combined isotopic- and power-broadening effects, and shortening the postamplification pulse to a few laser cycles (150-200 fs) via chirping and compression. These developments will move us closer to practical applications of ultra-fast CO2 lasers in medicine and other areas.

  2. Proton- and x-ray beams generated by ultra-fast CO(2) lasers for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelsky, I.; Polyanskiy, M.; Yakimenko, V.; Ben-Zvi, I.; Shkolnikov, P. Najmudin, Z.; Palmer, C.A.J.; Dover, N.P.; Oliva, P; Carpinelli, M.

    2011-07-01

    Recent progress in using picosecond CO{sub 2} lasers for Thomson scattering and ion-acceleration experiments underlines their potentials for enabling secondary radiation- and particle-sources. These experiments capitalize on certain advantages of long-wavelength CO{sub 2} lasers, such as higher number of photons per energy unit, and favorable scaling of the electrons ponderomotive energy and critical plasma density. The high-flux x-ray bursts produced by Thomson scattering of the CO{sub 2} laser off a counter-propagating electron beam enabled high-contrast, time-resolved imaging of biological objects in the picosecond time frame. In different experiments, the laser, focused on a hydrogen jet, generated monoenergetic proton beams via the radiation-pressure mechanism. The strong power-scaling of this regime promises realization of proton beams suitable for laser-driven proton cancer therapy after upgrading the CO{sub 2} laser to sub-PW peak power. This planned improvement includes optimizing the 10-{mu}m ultra-short pulse generation, assuring higher amplification in the CO{sub 2} gas under combined isotopic- and power-broadening effects, and shortening the postamplification pulse to a few laser cycles (150-200 fs) via chirping and compression. These developments will move us closer to practical applications of ultra-fast CO{sub 2} lasers in medicine and other areas.

  3. Policy development for biodiversity offsets: a review of offset frameworks.

    Science.gov (United States)

    McKenney, Bruce A; Kiesecker, Joseph M

    2010-01-01

    Biodiversity offsets seek to compensate for residual environmental impacts of planned developments after appropriate steps have been taken to avoid, minimize or restore impacts on site. Offsets are emerging as an increasingly employed mechanism for achieving net environmental benefits, with offset policies being advanced in a wide range of countries (i.e., United States, Australia, Brazil, Colombia, and South Africa). To support policy development for biodiversity offsets, we review a set of major offset policy frameworks-US wetlands mitigation, US conservation banking, EU Natura 2000, Australian offset policies in New South Wales, Victoria, and Western Australia, and Brazilian industrial and forest offsets. We compare how the frameworks define offset policy goals, approach the mitigation process, and address six key issues for implementing offsets: (1) equivalence of project impacts with offset gains; (2) location of the offset relative to the impact site; (3) "additionality" (a new contribution to conservation) and acceptable types of offsets; (4) timing of project impacts versus offset benefits; (5) offset duration and compliance; and (6) "currency" and mitigation replacement ratios. We find substantial policy commonalities that may serve as a sound basis for future development of biodiversity offsets policy. We also identify issues requiring further policy guidance, including how best to: (1) ensure conformance with the mitigation hierarchy; (2) identify the most environmentally preferable offsets within a landscape context; and (3) determine appropriate mitigation replacement ratios.

  4. Evaluation of algorithms for microperfusion assessment by fast simulations of laser Doppler power spectral density

    Science.gov (United States)

    Wojtkiewicz, S.; Liebert, A.; Rix, H.; Maniewski, R.

    2011-12-01

    In classical laser Doppler (LD) perfusion measurements, zeroth- and first-order moments of the power spectral density of the LD signal are utilized for the calculation of a signal corresponding to the concentration, speed and flow of red blood cells (RBCs). We have analysed the nonlinearities of the moments in relation to RBC speed distributions, parameters of filters utilized in LD instruments and the signal-to-noise ratio. We have developed a new method for fast simulation of the spectrum of the LD signal. The method is based on a superposition of analytically calculated Doppler shift probability distributions derived for the assumed light scattering phase function. We have validated the method by a comparison of the analytically calculated spectra with results of Monte Carlo (MC) simulations. For the semi-infinite, homogeneous medium and the single Doppler scattering regime, the analytical calculation describes LD spectra with the same accuracy as the MC simulation. The method allows for simulating the LD signal in time domain and furthermore analysing the index of perfusion for the assumed wavelength of the light, optical properties of the tissue and concentration of RBCs. Fast simulations of the LD signal in time domain and its frequency spectrum can be utilized in applications where knowledge of the LD photocurrent is required, e.g. in the development of detectors for tissue microperfusion monitoring or in measurements of the LD autocorrelation function for perfusion measurements. The presented fast method for LD spectra calculation can be used as a tool for evaluation of signal processing algorithms used in the LD method and/or for the development of new algorithms of the LD flowmetry and imaging. We analysed LD spectra obtained by analytical calculations using a classical algorithm applied in classical LD perfusion measurements. We observed nonlinearity of the first moment M1 for low and high speeds of particles (v 10 mm s-1). It was also noted that the

  5. Effect of helium-neon laser on fast excitatory postsynaptic potential of neurons in the isolated rat superior cervical ganglia

    Science.gov (United States)

    Mo, Hua; He, Ping; Mo, Ning

    2004-08-01

    The aim of this study is to further measure the effect of 632.8-nm helium-neon laser on fast excitatory postsynaptic potential (f-EPSP) of postganglionic neurons in isolated rat superior cervical ganglia by means of intracellular recording techniques. The neurons with f-EPSP were irradiated by different power densities (1-5 mW/cm2) laser. Irradiated by the 2-mW/cm2 laser, the amplitude of the f-EPSP could augment (PEPSP could descend and last for 3-8 minutes. But the amplitude of the f-EPSP of neurons irradiated by the 5-mW/cm2 laser could depress for the irradiating periods. The results show that: 1) the variation of the amplitude of f-EPSP caused by laser is power density-dependent and time-dependent; 2) there exist the second-order phases in the interaction of the helium-neon laser with neurons. These findings may provide certain evidence in explanation of the mechanisms of clinical helium-neon laser therapy.

  6. Effect of helium-neon laser on fast excitatory postsynaptic potential of neurons in the isolated rat superior cervical ganglia

    Institute of Scientific and Technical Information of China (English)

    Hua Mo(莫华); Ping He(何萍); Ning Mo(莫宁)

    2004-01-01

    The aim of this study is to further measure the effect of 632.8-nm helium-neon laser on fast excitatory postsynaptic potential(f-EPSP)of postganglionic neurons in isolated rat superior cervical ganglia by means of intracellular recording techniques.The neurons with f-EPSP were irradiated by different power densities(1 - 5 mW/cm2)laser.Irradiated by the 2-mW/cm2 laser,the amplitude of the f-EPSP could augment(P < 0.05,paired t test)and even cause action potential at the end of the first 1 - 2 minutes,the f-EPSP could descend and last for 3 - 8 minutes.But the amplitude of the f-EPSP of neurons irradiated by the 5-mW/cm2 laser could depress for the irradiating periods.The results show that:1)the variation of the amplitude of f-EPSP caused by laser is power density-dependent and time-dependent; 2)there exist the second-order phases in the interaction of the helium-neon laser with neurons.These findings may provide certain evidence in explanation of the mechanisms of clinical helium-neon laser therapy.

  7. A scheme for recording a fast process at nanosecond scale by using digital holographic interferometry with continuous wave laser

    Science.gov (United States)

    Wang, Jun; Zhao, Jianlin; Di, Jianglei; Jiang, Biqiang

    2015-04-01

    A scheme for recording fast process at nanosecond scale by using digital holographic interferometry with continuous wave (CW) laser is described and demonstrated experimentally, which employs delayed-time fibers and angular multiplexing technique and can realize the variable temporal resolution at nanosecond scale and different measured depths of object field at certain temporal resolution. The actual delay-time is controlled by two delayed-time fibers with different lengths. The object field information in two different states can be simultaneously recorded in a composite hologram. This scheme is also suitable for recording fast process at picosecond scale, by using an electro-optic modulator.

  8. Fast analysis of complex metallic alloys by double-pulse time-integrated Laser-Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sorrentino, F., E-mail: marwan@df.unipi.i [Marwan Technology s.r.l., Spin-off University of Pisa Largo Pontecorvo 3, 56127 Pisa (Italy); Carelli, G.; Francesconi, F.; Francesconi, M.; Marsili, P. [Marwan Technology s.r.l., Spin-off University of Pisa Largo Pontecorvo 3, 56127 Pisa (Italy); Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Tognoni, E. [Applied Laser Spectroscopy Laboratory, IPCF/CNR - Via G.Moruzzi 1, 56124 Pisa (Italy)

    2009-10-15

    Results are reported on the application of double-pulse Laser-Induced Breakdown Spectroscopy (LIBS) for fast analysis of complex metallic alloys. The approach followed for the determination of the composition of the alloys is based on the time-integrated acquisition of LIBS spectra emitted by plasmas induced by collinear double-pulse laser excitation. The spectra are analysed using the Partial Least Squares method, which allows the determination of sample composition even in the presence of strong spectral interferences. The results shown indicate the possibility of measuring the composition of complex metallic alloys in very short times and using relatively cheap LIBS instrumentation.

  9. Fast production of microfluidic devices by CO2 laser engraving of wax-coated glass slides.

    Science.gov (United States)

    da Costa, Eric T; Santos, Mauro F S; Jiao, Hong; do Lago, Claudimir L; Gutz, Ivano G R; Garcia, Carlos D

    2016-07-01

    Glass is one of the most convenient materials for the development of microfluidic devices. However, most fabrication protocols require long processing times and expensive facilities. As a convenient alternative, polymeric materials have been extensively used due their lower cost and versatility. Although CO2 laser ablation has been used for fast prototyping on polymeric materials, it cannot be applied to glass devices because the local heating causes thermal stress and results in extensive cracking. A few papers have shown the ablation of channels or thin holes (used as reservoirs) on glass but the process is still far away from yielding functional glass microfluidic devices. To address these shortcomings, this communication describes a simple method to engrave glass-based capillary electrophoresis devices using standard (1 mm-thick) microscope glass slides. The process uses a sacrificial layer of wax as heat sink and enables the development of both channels (with semicircular shape) and pass-through reservoirs. Although microscope images showed some small cracks around the channels (that became irrelevant after sealing the engraved glass layer to PDMS) the proposed strategy is a leap forward in the application of the technology to glass. In order to demonstrate the capabilities of the approach, the separation of dopamine, catechol and uric acid was accomplished in less than 100 s.

  10. Nuclear Ground State Properties in Strontium by Fast Beam Laser Spectroscopy

    CERN Multimedia

    2002-01-01

    Hyperfine structures and isotope shifts of strontium isotopes with A=78 to A=100 were measured by collinear fast beam laser spectroscopy. Nuclear spins, moments and changes in mean square charge radii are extracted from the data. The spins and moments of most of the odd isotopes are explained in the framework of the single particle model. The changes in mean square charge radii show a decrease with increasing neutron number below the N=50 shell closure. Above N=50 the charge radii increase regularly up to N=59 before revealing a strong discontinuity, indicating the onset of strong ground state deformation. A comparison of the droplet model shows that for the transitional isotopes below and above N=50, the zero point quadrupole motion describes part of the observed shell effect. Calculations carried out in the Hartree-Fock plus BCS model suggest an additional change in the surface region of the charge distribution at spherical shape. From these calculations it is furthermore proposed, that the isotopes $^7

  11. Fast detection of tobacco mosaic virus infected tobacco using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Peng, Jiyu; Song, Kunlin; Zhu, Hongyan; Kong, Wenwen; Liu, Fei; Shen, Tingting; He, Yong

    2017-03-01

    Tobacco mosaic virus (TMV) is one of the most devastating viruses to crops, which can cause severe production loss and affect the quality of products. In this study, we have proposed a novel approach to discriminate TMV-infected tobacco based on laser-induced breakdown spectroscopy (LIBS). Two different kinds of tobacco samples (fresh leaves and dried leaf pellets) were collected for spectral acquisition, and partial least squared discrimination analysis (PLS-DA) was used to establish classification models based on full spectrum and observed emission lines. The influences of moisture content on spectral profile, signal stability and plasma parameters (temperature and electron density) were also analysed. The results revealed that moisture content in fresh tobacco leaves would worsen the stability of analysis, and have a detrimental effect on the classification results. Good classification results were achieved based on the data from both full spectrum and observed emission lines of dried leaves, approaching 97.2% and 88.9% in the prediction set, respectively. In addition, support vector machine (SVM) could improve the classification results and eliminate influences of moisture content. The preliminary results indicate that LIBS coupled with chemometrics could provide a fast, efficient and low-cost approach for TMV-infected disease detection in tobacco leaves.

  12. Training SVMs without offset

    Energy Technology Data Exchange (ETDEWEB)

    Steinwart, Ingo [Los Alamos National Laboratory; Hush, Don [Los Alamos National Laboratory; Scovel, Clint [Los Alamos National Laboratory

    2009-01-01

    We develop, analyze, and test a training algorithm for support vector machine cla.'>sifiers without offset. Key features of this algorithm are a new stopping criterion and a set of working set selection strategies that, although inexpensive, do not lead to substantially more iterations than the optimal working set selection strategy. For these working set strategies, we establish convergence rates that coincide with the best known rates for SYMs with offset. We further conduct various experiments that investigate both the run time behavior and the performed iterations of the new training algorithm. It turns out, that the new algorithm needs less iterations and run-time than standard training algorithms for SYMs with offset.

  13. Processless offset printing plates

    Directory of Open Access Journals (Sweden)

    Sanja Mahović Poljaček

    2015-06-01

    Full Text Available With the implementation of platesetters in the offset printing plate making process, imaging of the printing plate became more stable and ensured increase of the printing plate quality. But as the chemical processing of the printing plates still highly influences the plate making process and the graphic reproduction workflow, development of printing plates that do not require chemical processing for offset printing technique has been one of the top interests in graphic technology in the last few years. The main reason for that came from the user experience, where majority of the problems with plate making process could be connected with the chemical processing of the printing plate. Furthermore, increased environmental standards lead to reducing of the chemicals used in the industrial processes. Considering these facts, different types of offset printing plates have been introduced to the market today. This paper presents some of the processless printing plates.

  14. Shot-to-shot reproducibility in the emission of fast highly charged metal ions from a laser ion source.

    Science.gov (United States)

    Krása, J; Velyhan, A; Margarone, D; Krouský, E; Krouský, L; Jungwirth, K; Rohlena, K; Ullschmied, J; Parys, P; Ryć, L; Wołowski, J

    2012-02-01

    The generation of fast highly charged metal ions with the use of the sub-nanosecond Prague Asterix Laser System, operated at a fundamental wavelength of 1315 nm, is reported. Particular attention is paid to shot-to-shot reproducibility in the ion emission. Au and Pd targets were exposed to intensities up to 5 × 10(16) W∕cm(2). Above the laser intensity threshold of ∼3 × 10(14) W∕cm(2) the plasma is generated in a form of irregular bursts. The maximum energy of protons constituting the leading edge of the fastest burst reaches a value up to 1 MeV. The fast ions in the following bursts have energy gradually decreasing with the increasing burst number, namely, from a value of about 0.5 MeV∕charge regardless of the atomic number and mass of the ionized species.

  15. Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon

    Science.gov (United States)

    Vaisseau, X.; Morace, A.; Touati, M.; Nakatsutsumi, M.; Baton, S. D.; Hulin, S.; Nicolaï, Ph.; Nuter, R.; Batani, D.; Beg, F. N.; Breil, J.; Fedosejevs, R.; Feugeas, J.-L.; Forestier-Colleoni, P.; Fourment, C.; Fujioka, S.; Giuffrida, L.; Kerr, S.; McLean, H. S.; Sawada, H.; Tikhonchuk, V. T.; Santos, J. J.

    2017-05-01

    Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism—observed only for times before the shock breakout at the inner cone tip—is due to self-generated resistive magnetic fields of ˜0.5 - 1 kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

  16. Fast electron propagation in Ti foils irradiated with sub-picosecond laser pulses at $I\\lambda^{2} > 10^{18}$ Wcm$^{-2} \\mu m^{2}$

    CERN Document Server

    Makita, M; McKeever, K; Dzelzainis, T; White, S; Kettle, B; Dromey, B; Doria, D; Zepf, M; Lewis, CLS; Riley, D; Hansen, S B; Robinson, A P L

    2014-01-01

    We have studied the propagation of fast electrons through laser irradiated Ti foils by monitoring the emission of hard X-rays and K-{\\alpha} radiation from bare foils and foils backed by a thick epoxy layer. Key observations include strong refluxing of electrons and divergence of the electron beam in the foil with evidence of magnetic field collimation. Our diagnostics have allowed us to estimate the fast electron temperature and fraction of laser energy converted to fast electrons. We have observed clear differences between the fast electron temperatures observed with bare and epoxy backed targets which may be due to the effects of refluxing.

  17. 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,

  18. 激光制导炸弹无偏置上仰投放战术机动规划%Tactic maneuver planning of loft delivery of laser-guided bomb with no offset

    Institute of Scientific and Technical Information of China (English)

    张滢; 杨任农; 左家亮; 景小宁

    2016-01-01

    Loft delivery of laser-guided bomb with no offset is a typical weapon delivery tactic during surface attack.The purpose of tactic maneuver planning of operational aircraft is to search for the best flying route and the operation location,time and parameters of certain equipment while satisfying the demand of certain tactic principles.According to the literal description of the tactic of loft delivery of laser-guided bomb with no offset, a tactic model based on the combination of maneuvers is set up.Considering the maneuver capability of the opera-tional aircraft and the operation conditions of the laser-guided bomb comprehensively,aiming at obtaining the maximal level of damage of the ground target and the minimal level of threat of the operational aircraft,a multi-objective optimization model on tactic maneuver planning is established.Then,the multi-objective evolutionary algorithm based on the decomposition algorithm is employed to solve the tactic maneuver planning model.Simu-lation experiments prove that the proposed model and algorithm are feasible and efficient.%无偏置上仰投弹是一种典型的激光制导炸弹投放战术,作战飞机战术机动规划的目的是在遵循战术要求的前提下寻找出最优飞行航路以及装备操作关键点、时机和参数。根据无偏置上仰投弹战术描述,建立了基于机动组合的战术模型。综合考虑战机机动性能和激光制导弹使用限制等约束条件,以地面目标毁伤程度最大化和战机受威胁程度最小化为目标,建立了战术机动多目标优化模型。采用基于分解的多目标优化算法求解模型。仿真实验验证了模型和算法的可行性、有效性。

  19. Ultra--fast carriers relaxation in bulk silicon following photo--excitation with a short and polarized laser pulse

    CERN Document Server

    Sangalli, Davide

    2014-01-01

    A novel approach based on the merging of the out--of--equilibrium Green's function method with the ab-initio, Density--Functional--Theory is used to describe the ultra--fast carriers relaxation in Silicon. The results are compared with recent two photon photo--emission measurements. We show that the interpretation of the carrier relaxation in terms of L -> X inter--valley scattering is not correct. The ultra--fast dynamics measured experimentally is, instead, due to the scattering between degenerate $L$ states that is activated by the non symmetric population of the conduction bands induced by the laser field. This ultra--fast relaxation is, then, entirely due to the specific experimental setup and it can be interpreted by introducing a novel definition of the quasi--particle lifetimes in an out--of--equilibrium context.

  20. Kinetic modeling of a high power fast-axial-flow CO2 laser with computational fluid dynamics method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new computational fluid dynamics (CFD) method for the simulation of fast-axial-flow CO2 laser is developed.The model which is solved by CFD software uses a set of dynamic differential equations to describe the dynamic process in one discharge tube.The velocity,temperature,pressure and turbulence energy distributions in discharge passage are presented.There is a good agreement between the theoretical prediction and the experimental results.This result indicates that the parameters of the laser have significant effect on the flow distribution in the discharge passage.It is helpful to optimize the output of high power CO2 laser by mastering its kinetic characteristics.

  1. Design and fabrication of hollow-core photonic crystal fibers for high power fast laser beam transportation and pulse compression

    Science.gov (United States)

    Wang, Y. Y.; Peng, Xiang; Alharbi, M.; Dutin, C. F.; Bradley, T. D.; Mielke, Michael; Booth, Timothy; Benabid, F.

    2012-03-01

    We report on recent design and fabrication of Kagome type hollow-core photonic crystal fiber (HC-PCF) for the purpose of high power fast laser beam transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all Kagome fibers) of 40dB/km over a broadband transmission centered at 1500nm. We show that the large core size, low attenuation, broadband transmission, single modedness, low dispersion and relatively low banding loss makes it an ideal host for high power laser beam transportation. By filling the fiber with helium gas, a 74μJ, 850fs and 40kHz repetition rate ultra-short pulse at 1550nm has been faithfully delivered with little propagation pulse distortion. Compression of a 105μJ laser pulse from 850fs to 300fs has been achieved by operating the fiber in ambient air.

  2. Fast computation of radiation pressure force exerted by multiple laser beams on red blood cell-like particles

    Science.gov (United States)

    Gou, Ming-Jiang; Yang, Ming-Lin; Sheng, Xin-Qing

    2016-10-01

    Mature red blood cells (RBC) do not contain huge complex nuclei and organelles, makes them can be approximately regarded as homogeneous medium particles. To compute the radiation pressure force (RPF) exerted by multiple laser beams on this kind of arbitrary shaped homogenous nano-particles, a fast electromagnetic optics method is demonstrated. In general, based on the Maxwell's equations, the matrix equation formed by the method of moment (MOM) has many right hand sides (RHS's) corresponding to the different laser beams. In order to accelerate computing the matrix equation, the algorithm conducts low-rank decomposition on the excitation matrix consisting of all RHS's to figure out the so-called skeleton laser beams by interpolative decomposition (ID). After the solutions corresponding to the skeletons are obtained, the desired responses can be reconstructed efficiently. Some numerical results are performed to validate the developed method.

  3. A final report to the Laboratory Directed Research and Development committee on Project 93-ERP-075: ``X-ray laser propagation and coherence: Diagnosing fast-evolving, high-density laser plasmas using X-ray lasers``

    Energy Technology Data Exchange (ETDEWEB)

    Wan, A.S.; Cauble, R.; Da Silva, L.B.; Libby, S.B.; Moreno, J.C.

    1996-02-01

    This report summarizes the major accomplishments of this three-year Laboratory Directed Research and Development (LDRD) Exploratory Research Project (ERP) entitled ``X-ray Laser Propagation and Coherence: Diagnosing Fast-evolving, High-density Laser Plasmas Using X-ray Lasers,`` tracking code 93-ERP-075. The most significant accomplishment of this project is the demonstration of a new laser plasma diagnostic: a soft x-ray Mach-Zehnder interferometer using a neonlike yttrium x-ray laser at 155 {angstrom} as the probe source. Detailed comparisons of absolute two-dimensional electron density profiles obtained from soft x-ray laser interferograms and profiles obtained from radiation hydrodynamics codes, such as LASNEX, will allow us to validate and benchmark complex numerical models used to study the physics of laser-plasma interactions. Thus the development of soft x-ray interferometry technique provides a mechanism to probe the deficiencies of the numerical models and is an important tool for, the high-energy density physics and science-based stockpile stewardship programs. The authors have used the soft x-ray interferometer to study a number of high-density, fast evolving, laser-produced plasmas, such as the dynamics of exploding foils and colliding plasmas. They are pursuing the application of the soft x-ray interferometer to study ICF-relevant plasmas, such as capsules and hohlraums, on the Nova 10-beam facility. They have also studied the development of enhanced-coherence, shorter-pulse-duration, and high-brightness x-ray lasers. The utilization of improved x-ray laser sources can ultimately enable them to obtain three-dimensional holographic images of laser-produced plasmas.

  4. FAST CARS: Engineering a Laser Spectroscopic Technique for Rapid Identification of Bacterial Spores

    OpenAIRE

    Scully, M. O.; Kattawar, G. W.; Lucht, R. P.; Opatrný, T.; Pilloff, H.; Rebane, A.; Sokolov, A.V.(Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090, Russia); Zubairy, M. S.

    2002-01-01

    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on e.g., resonance fluorescence. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. However, generating and using maximally coherent oscillation in macromole...

  5. Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns

    Science.gov (United States)

    Zhang, Chentao; Zhang, Jianhuan; Lin, Kun; Huang, Yuanqing

    2017-05-01

    An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

  6. Offset trench isolation

    Science.gov (United States)

    Roth, S. S.; Cooper, K. J.; Ray, W.; Kirsch, H. C.; Grove, Charlotte

    1994-08-01

    Feasibility of a new, recessed isolation technique that utilizes an offset, shallow trench in combination with thermal oxidation for achieving near zero final encroachment with excellent planarity is demonstrated. Etch of the shallow trench is offset from the original hardmask by an oxide sidewall spacer. After trench etch, HF is used to remove the hardmask oxide and sidewall spacers and to form a cavity which is self-aligned to the nitride edge. Exposed silicon regions are then reoxidized and encapsulated with polysilicon. Field oxide is then grown. The final field oxide profile exhibits steep sidewall angles without inducing substrate defects as evidenced by low diode leakage. Other isolation sensitive device parametrics such as gate oxide quality and metal oxide semiconductor field effect transistor threshold voltage stability are presented and exhibit good characteristics.

  7. Fast scaling of energetic protons generated in the interaction of linearly polarized femtosecond petawatt laser pulses with ultrathin targets

    Science.gov (United States)

    Kim, I. Jong; Pae, Ki Hong; Kim, Chul Min; Kim, Hyung Taek; Choi, Il Woo; Lee, Chang-Lyoul; Singhal, Himanshu; Sung, Jae Hee; Lee, Seong Ku; Lee, Hwang Woon; Nickles, Peter V.; Jeong, Tae Moon; Nam, Chang Hee

    2015-12-01

    Laser-driven proton/ion acceleration is a rapidly developing research field attractive for both fundamental physics and applications such as hadron therapy, radiography, inertial confinement fusion, and nuclear/particle physics. Laser-driven proton/ion beams, compared to those obtained in conventional accelerators, have outstanding features such as low emittance, small source size, ultra-short duration and huge acceleration gradient of ∼1 MeV μm-1. We report proton acceleration from ultrathin polymer targets irradiated with linearly polarized, 30-fs, 1-PW Ti:sapphire laser pulses. A maximum proton energy of 45 MeV with a broad and modulated profile was obtained when a 10-nm-thick target was irradiated at a laser intensity of 3.3 × 1020 W/cm2. The transition from slow (I1/2) to fast scaling (I) of maximum proton energy with respect to laser intensity I was observed and explained by the hybrid acceleration mechanism including target normal sheath acceleration and radiation pressure acceleration in the acceleration stage and Coulomb-explosion-assisted free expansion in the post acceleration stage.

  8. Offset Compound Gear Drive

    Science.gov (United States)

    Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

    2010-01-01

    The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths. Low-speed operation is accomplished in two meshes. For the purpose of illustrating the low-speed output operation, the following example pitch diameters are given. A 5.0 pitch diameter (PD) input gear to 7.50 PD (internal tooth) intermediate gear (0.667 reduction mesh), and a 7.50 PD (external tooth) intermediate gear to a 10.00 PD output gear (0.750 reduction mesh). Note that it is not required that the intermediate gears on the offset axis be of the same diameter. For this example, the resultant low-speed ratio is 2:1 (output speed = 0.500; product of stage one 0.667 reduction and stage two 0.750 stage reduction). The design is not restricted to the example pitch diameters, or output ratio. From the output gear, power is transmitted through a hollow drive shaft, which, in turn, drives a sprag during which time the main clutch is disengaged.

  9. Green and Fast Laser Fusion Technique for Bulk Silicate Rock Analysis by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry.

    Science.gov (United States)

    Zhang, Chenxi; Hu, Zhaochu; Zhang, Wen; Liu, Yongsheng; Zong, Keqing; Li, Ming; Chen, Haihong; Hu, Shenghong

    2016-10-18

    Sample preparation of whole-rock powders is the major limitation for their accurate and precise elemental analysis by laser ablation inductively-coupled plasma mass spectrometry (ICPMS). In this study, a green, efficient, and simplified fusion technique using a high energy infrared laser was developed for major and trace elemental analysis. Fusion takes only tens of milliseconds for each sample. Compared to the pressed pellet sample preparation, the analytical precision of the developed laser fusion technique is higher by an order of magnitude for most elements in granodiorite GSP-2. Analytical results obtained for five USGS reference materials (ranging from mafic to intermediate to felsic) using the laser fusion technique generally agree with recommended values with discrepancies of less than 10% for most elements. However, high losses (20-70%) of highly volatile elements (Zn and Pb) and the transition metal Cu are observed. The achieved precision is within 5% for major elements and within 15% for most trace elements. Direct laser fusion of rock powders is a green and notably simple method to obtain homogeneous samples, which will significantly accelerate the application of laser ablation ICPMS for whole-rock sample analysis.

  10. Fast and sensitive trace metal analysis in aqueous solutions by laser-induced breakdown spectroscopy using wood slice substrates

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhijiang; Li Hongkun; Liu Ming [School of Physics, South China University of Technology, Guangzhou 510641 (China); Li Runhua [School of Physics, South China University of Technology, Guangzhou 510641 (China)], E-mail: rhli@scut.edu.cn

    2008-01-15

    To perform fast and sensitive trace metal analysis in aqueous solutions by laser-induced breakdown spectroscopy (LIBS) based on only one single-pulse laser system, a wood slice has been used as a liquid absorber to transform liquid sample analysis to solid sample analysis using LIBS. High detection sensitivity and good reproducibility can be achieved with this approach. Calibration curves for five metal elements, Cr, Mn, Cu, Cd, and Pb under trace concentrations, have been obtained, and the limits of their detection were determined to be in the range of 0.029-0.59 mg L{sup -1}, 2-3 orders better than those obtained by directly analyzing liquid samples where the laser was focused on a liquid surface. The wood slice was very easy to handle and thus, the whole analysis process took only 4-5 min for each sample. This approach provides a more practical approach for fast and sensitive metal element analysis in aqueous solutions using LIBS, which is especially useful for monitoring toxic heavy metals in water.

  11. Fast and sensitive trace metal analysis in aqueous solutions by laser-induced breakdown spectroscopy using wood slice substrates

    Science.gov (United States)

    Chen, Zhijiang; Li, Hongkun; Liu, Ming; Li, Runhua

    2008-01-01

    To perform fast and sensitive trace metal analysis in aqueous solutions by laser-induced breakdown spectroscopy (LIBS) based on only one single-pulse laser system, a wood slice has been used as a liquid absorber to transform liquid sample analysis to solid sample analysis using LIBS. High detection sensitivity and good reproducibility can be achieved with this approach. Calibration curves for five metal elements, Cr, Mn, Cu, Cd, and Pb under trace concentrations, have been obtained, and the limits of their detection were determined to be in the range of 0.029-0.59 mg L - 1 , 2-3 orders better than those obtained by directly analyzing liquid samples where the laser was focused on a liquid surface. The wood slice was very easy to handle and thus, the whole analysis process took only 4-5 min for each sample. This approach provides a more practical approach for fast and sensitive metal element analysis in aqueous solutions using LIBS, which is especially useful for monitoring toxic heavy metals in water.

  12. High performance diagnostics for Time-Of-Flight and X ray measurements in laser produced plasmas, based on fast diamond detectors

    Science.gov (United States)

    De Angelis, R.; Consoli, F.; Verona, C.; Di Giorgio, G.; Andreoli, P.; Cristofari, G.; Cipriani, M.; Ingenito, F.; Marinelli, M.; Verona-Rinati, G.

    2016-12-01

    The paper reports about the use of single-crystal Chemical Vapour Deposited (CVD) diamonds as radiation detectors in laser-matter interaction experiments on the ABC laser in ENEA - Frascati. The detectors have been designed and realized by University of Tor Vergata - Rome. The interdigital configuration and the new design of the bias-tee voltage supply units guarantee a fast time response. The detectors are sensitive to soft-X photons and to particles. A remarkable immunity to electromagnetic noise, associated with the laser-target interaction, makes them especially useful for the measurements of the time of flight of fast particles. A novel diamond assembly has been tested in plasmas generated by the ABC laser in the nanosecond regime at intensities I=1013÷ 14 W/cm2, where contributions from X rays, fast electrons and ions could be observed.

  13. Analysis of oxide inclusions in steel by fast laser-induced breakdown spectroscopy scanning: an approach to quantification.

    Science.gov (United States)

    Boué-Bigne, F

    2007-03-01

    Laser-induced breakdown spectroscopy (LIBS) measurements were performed on a steel sample to investigate the feasibility of obtaining fast information on cleanness. A calibration approach was considered to enable the quantification of the elemental composition of non-metallic inclusions; the same data was also used to estimate the size of the inclusions. For the first time, the quantified chemical composition data obtained by LIBS for non-metallic inclusions was compared to the corresponding results obtained from scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis, the conventional method used for steel cleanness assessment, and proved successful. Due to the speed of analysis and the systematic recording of the signal from the scanned area, LIBS enables the analysis of larger areas of sample and in significantly shorter time than with automated SEM-EDX. This paper summarizes the hitherto obtained results for the fast analysis of inclusions in steel by LIBS.

  14. Divergence-free transport of laser-produced fast electrons along a meter-long wire target.

    Science.gov (United States)

    Nakajima, Hiroaki; Tokita, Shigeki; Inoue, Shunsuke; Hashida, Masaki; Sakabe, Shuji

    2013-04-12

    We demonstrate that, from a 10-μm metal wire irradiated by a 10(19)  W/cm2 laser pulse, fast electrons form a nearly perfect circular beam around the wire and propagate along it. The total charge and diameter of the electron beam are maintained over a propagation distance of 1 m. Moreover, the electron beam can be guided along a slightly bent wire. Numerical simulations suggest that a relatively weak steady electric field, which does not decay for several nanoseconds, is generated around the wire and plays a key role in the long-distance guidance.

  15. Ultrafast, high repetition rate, ultraviolet, fiber-laser-based source: application towards Yb+ fast quantum-logic.

    Science.gov (United States)

    Hussain, Mahmood Irtiza; Petrasiunas, Matthew Joseph; Bentley, Christopher D B; Taylor, Richard L; Carvalho, André R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

    2016-07-25

    Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb+ ions faster than the trap period and with fidelity above 99%.

  16. Fast and reliable interrogation of USFBG sensors based on MG-Y laser discrete wavelength channels

    Science.gov (United States)

    Rohollahnejad, Jalal; Xia, Li; Cheng, Rui; Ran, Yanli; Su, Lei

    2017-01-01

    In this letter, we propose to use discrete wavelength channels of a single chip MG-Y laser to interrogate an ultra-short fiber Bragg grating with a wide Gaussian spectrum. The broadband Gaussian spectrum of USFBG is sampled by the wavelength channels of MG-Y laser, through which the center of the spectrum. The measurement inherits the important features of a common tunable laser interrogation technique, namely its high flexibility, natural insensitivity to intensity variations relative to common intensity-based approaches. While for traditional tunable laser methods, it requires to sweep the whole spectrum to obtain the center wavelength of the spectrum, for the proposed scheme, just a few discrete wavelength channels of laser are needed to be acquired, which leads to significant improvements of the efficiency and measurement speed. This reliable and low cost concept could offer the good foundation for USFBGs future applications in large scale distributed measurements, especially in time domain multiplexing scheme.

  17. New methods for high current fast ion beam production by laser-driven acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Margarone, D.; Krasa, J.; Prokupek, J.; Velyhan, A.; Laska, L.; Jungwirth, K.; Mocek, T.; Korn, G.; Rus, B. [Institute of Physics, ASCR, v.v.i., PALS Centre, Prague (Czech Republic); Torrisi, L.; Gammino, S.; Cirrone, P.; Cutroneo, M.; Romano, F. [INFN-Laboratori Nazionali del Sud, Catania, Messina University (Italy); Picciotto, A.; Serra, E. [Fondazione Bruno Kessler - IRST, Trento (Italy); Giuffrida, L. [CELIA, Centre Lasers Intenses et Applications (France); Mangione, A. [ITA - Istituto Tecnologie Avanzate, Trapani (Italy); Rosinski, M.; Parys, P. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); and others

    2012-02-15

    An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 10{sup 16}-10{sup 19} W/cm{sup 2}. The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generation ion sources to be employed in medicine, nuclear physics, matter physics, and industry.

  18. New methods for high current fast ion beam production by laser-driven accelerationa)

    Science.gov (United States)

    Margarone, D.; Krasa, J.; Prokupek, J.; Velyhan, A.; Torrisi, L.; Picciotto, A.; Giuffrida, L.; Gammino, S.; Cirrone, P.; Cutroneo, M.; Romano, F.; Serra, E.; Mangione, A.; Rosinski, M.; Parys, P.; Ryc, L.; Limpouch, J.; Laska, L.; Jungwirth, K.; Ullschmied, J.; Mocek, T.; Korn, G.; Rus, B.

    2012-02-01

    An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 1016-1019 W/cm2. The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generation ion sources to be employed in medicine, nuclear physics, matter physics, and industry.

  19. New methods for high current fast ion beam production by laser-driven acceleration.

    Science.gov (United States)

    Margarone, D; Krasa, J; Prokupek, J; Velyhan, A; Torrisi, L; Picciotto, A; Giuffrida, L; Gammino, S; Cirrone, P; Cutroneo, M; Romano, F; Serra, E; Mangione, A; Rosinski, M; Parys, P; Ryc, L; Limpouch, J; Laska, L; Jungwirth, K; Ullschmied, J; Mocek, T; Korn, G; Rus, B

    2012-02-01

    An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 10(16)-10(19) W∕cm(2). The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generation ion sources to be employed in medicine, nuclear physics, matter physics, and industry.

  20. BESTIA - The next generation ultra-fast CO2 laser for advanced accelerator research

    Science.gov (United States)

    Pogorelsky, Igor V.; Babzien, Markus; Ben-Zvi, Ilan; Skaritka, John; Polyanskiy, Mikhail N.

    2016-09-01

    Over the last two decades, BNL's ATF has pioneered the use of high-peak power CO2 lasers for research in advanced accelerators and radiation sources. Our recent developments in ion acceleration, Compton scattering, and IFELs have further underscored the benefits from expanding the landscape of strong-field laser interactions deeper into the mid-infrared (MIR) range of wavelengths. This extension validates our ongoing efforts in advancing CO2 laser technology, which we report here. Our next-generation, multi-terawatt, femtosecond CO2 laser will open new opportunities for studying ultra-relativistic laser interactions with plasma in the MIR spectral domain, including new regimes in the particle acceleration of ions and electrons.

  1. Fast spatial-resolved beam diagnostics for material processing by industrial CO2 lasers

    Science.gov (United States)

    Martinen, Dirk; Decker, Ingo; Wohlfahrt, Helmut

    1996-09-01

    Due to the increasing range of high-speed and high-accuracy applications in material processing, especially in laser beam welding and cutting, the temporal stability of the laser beam parameters becomes more and more important. In this paper a laser beam diagnostic device is presented, that allows the determination of the intensity-profiles of high- power CO2 lasers with high time-resolution. The detector of this device consists of two linear arrays of room- temperature HgCdTe-detectors, arranged perpendicularly to each other across the center of the beam. The data of the 70 detector elements is acquired simultaneously at rates up to 15 kS/sec for single shot events and several 100 kS/sec for repetitive laser pulses. Due to the use of a digital signal processor (DSP) and an especially adapted software, it is possible to analyze the fluctuations of the intensity distribution on-line. By help of a partially transmitting mirror in the beam delivery system, measurements can be performed during material processing. Therefore, the interaction of the laser beam source itself with the material processing due to beam reflection as well as influences of the industrial environment to the laser can be detected. The calculation of the local variance and mean values enables the dependence of the laser's short- and long-term stability to be investigated due to changes in the resonator alignment, the stability of the power supply, the gas composition etc., as well as to the influence of the processing. For the pulse-mode of a laser, its transient behavior like changes of the intensity distribution can be determined with high time-resolution. For the improvement of drilling processes, the calculation of further statistical functions by the DSP makes it possible to estimate the uniformity of the laser pulses on-line as well.

  2. A Quantitative Analysis of Modulation of the Fast Excitatory Postsynaptic Potential of Neurons in Rat Sympathetic Ganglia by a Low-Intensity Laser

    Institute of Scientific and Technical Information of China (English)

    MO Hua; YANG Li-Jian; JIA Ya

    2005-01-01

    @@ We propose a mathematical model which can quantitatively describe the kinetics of postsynaptic membrane potential modulated by a low intensity laser. By virtue of the numerical computation, it is found that the height of peak of fast excitatory postsynaptic potential (f-EPSP) for intermediate laser power density (around 2mW/cm2) is higher than that for both small and large laser power densities, that is, of the f-EPSP peak height changes with the increasing laser power density (up to 5mW/cm2) in non-monotonic behaviour. The theoretical results are qualitatively consistent with the previous experimental data.

  3. Modeling of fast phase transitions dynamics in metal target irradiated by pico- and femtosecond pulsed laser

    Energy Technology Data Exchange (ETDEWEB)

    Mazhukin, V.I. [Institute of Mathematical Modeling, Russian Academy of Sciences, Miusskaya sq. 4A, 125047 Moscow (Russian Federation); Lobok, M.G. [Institute of Mathematical Modeling, Russian Academy of Sciences, Miusskaya sq. 4A, 125047 Moscow (Russian Federation)], E-mail: immras@orc.ru; Chichkov, B. [Laser Zentrum Hannover e.V. Holleritallee 8, 30419 Hannover (Germany)], E-mail: b.chichkov@lhz.de

    2009-03-01

    We investigate laser pulse influence on aluminum target in irradiance range 10{sup 9} to 10{sup 16} W/cm{sup 2}, pulse duration between 10{sup -8} and 10{sup -15} s, Gaussian time profile with wavelength of 0.8 {mu}m. For all computations energy density was 10 J/cm{sup 2}. Plasma in the evaporated material is generated at the energy density above 10 J/cm{sup 2}as the modeling showed. Long and short laser pulses distinguish by the mechanisms of energy transformation. For short laser pulses there is volumetric energy absorption, together with rapid phase transitions it lead to overheating in solid and liquid states, overheated solid temperature rises up to (6-8)T{sub m}. Under influence of the energy saved in overheated solid, duration of the phase transitions becomes nanosecond, which is several orders of magnitude longer than laser pulse.

  4. Fast Optical Hazard Detection for Planetary Rovers Using Multiple Spot Laser Triangulation

    Science.gov (United States)

    Matthies, L.; Balch, T.; Wilcox, B.

    1997-01-01

    A new laser-based optical sensor system that provides hazard detection for planetary rovers is presented. It is anticipated that the sensor can support safe travel at speeds up to 6cm/second for large (1m) rovers in full sunlight on Earth or Mars. The system overcomes limitations in an older design that require image differencing ot detect a laser stripe in full sun.

  5. Ultra-fast pulse radiolysis system combined with a laser photocathode RF gun and a femtosecond laser

    CERN Document Server

    Muroya, Y; Watanabe, T; Wu, G; Kobayashi, T; Yoshii, K; Ueda, T; Uesaka, M; Katsumura, Y

    2002-01-01

    In order to study the early events in radiation physics and chemistry, two kinds of new pulse radiolysis systems with higher time resolution based on pump-and-probe method have been developed at the Nuclear Engineering Research Laboratory, the University of Tokyo. The first one, a few picosecond (2 ps at FWHM) electron beam (pump) from an 18 MeV S-band Linac using a laser photocathode RF gun (BNL/KEK/SHI type: GUN IV) was operated with a femtosecond laser pulse (100 fs at FWHM), which also acted as the analyzing light (probe). The synchronization precision between the pump and the probe was 1.7 ps (rms). In a 1.0 cm sample cell, a time resolution of 12 ps was achieved. The second one, a picosecond (4 ps at FWHM) electron pulse from a 35 MeV S-band Linac employing a conventional thermionic gun with a sub-harmonic buncher, was synchronized with the femtosecond laser pulse, with a synchronization jitter of 2.8 ps (rms). A time resolution of 22 ps was obtained with 2 cm cell. This makes it possible to do the puls...

  6. Design of a Piezoelectric-Driven Tilt Mirror for a Fast Laser Scanner

    Science.gov (United States)

    Park, Jung-Ho; Lee, Hu-Seung; Lee, Jae-Hoon; Yun, So-Nam; Ham, Young-Bog; Yun, Dong-Won

    2012-09-01

    Recently, laser scanners have been used for laser processing such as cutting, welding, and grooving, especially in the automotive industry. The laser scanners need a high-speed driving to minimize cracks caused by thermal shock of brittle materials. Therefore, a novel laser processing system that is composed of a laser source and a piezoelectric-driven tilt mirror to control the reflection angle of the laser beam, and a stage equipped with the tilt mirror has been investigated. In this study, a piezoelectric-driven tilt mirror is designed and analyzed for scanning performance to achieve a beam spot of 30 µm, a pattern width of 1 mm, an overlap ratio of 70% of the circle area, and a scanning speed of 1 m/s. Then, structural analysis of the tilt mirror with three piezoelectric actuators is performed to determine the maximum reflection angle and resonance frequency. Finally, a prototype tilt mirror is fabricated and its basic characteristics are experimentally investigated and discussed.

  7. Experimental Study on Fast Electrons Transport in Ultra-intense Laser Irradiated Solid Targets by Transition Radiation

    Science.gov (United States)

    Zhijian, Zheng; Guangcan, Wang; Yuqiu, Gu

    2008-11-01

    The experiment was performed with SILEX laser facility(Ti-saphhire) at LFRC in China. The SILEX parameter: wavelength 0.8μm, duration 35fs, output power 280TW, contrast 5*105, The focal spot φ10μm(F/1.7), intensity on target surface 1*10^19W/cm^2(F/3). The main diagnostic equipments are the electron spectrometer, OMA spectrometer, optical streak camera. Some experimental results are given: The spectrum of optical emission from rear surface is rather narrow around some particular frequencies(1φ, 2φ, 3φ), We ascribe and confirm that the spike-like spectral line that is coherent transition radiation; The coherent light is also seen on time-integrated image with ring-patter due to Weibel instability of the fast electron transport; Obtained experimental cure of target thickness vs OTR image intensity is relative to mean free path of fast electron; The measuring optical transition radiation(OTR) duration of 171ps much longer than 1ps duration of fast electron transport target, the possible explanation is that the OTR duration to be determined magnetic diffusion time.

  8. Comparison of Capillary Architecture between Slow and Fast Muscles in Rats Using a Confocal Laser Scanning Microscope

    Directory of Open Access Journals (Sweden)

    Kumagishi,Kanae

    2010-02-01

    Full Text Available The skeletal muscle is classified into 2 types, slow oxidative or fast glycolytic muscle. For further characterization, we investigated the capillary architecture in slow and fast muscles. The rat soleus and extensor digitorum longus (EDL muscles were used as representatives of slow and fast muscles, respectively. To investigate capillary density, sections of both types of muscle were stained with alkaline phosphatase;the soleus muscle showed more intense reactivity, indicating that it had a denser capillary structure than the EDL muscle. We then injected fluorescent contrast medium into samples of both muscle types for light and confocal-laser microscopic evaluation. The capillary density and capillary-to-fiber ratio were significantly higher, and the course of the capillaries was more tortuous, in the soleus muscle than in the EDL muscle. Capillary coursed more tortuously in the soleus than in the EDL muscle. Succinate dehydrogenase (SDH activity, an indicator of mitochondrial oxidative capacity, and vascular endothelial growth factor (VEGF expression were also significantly higher in the soleus muscle. Thus, we conclude that slow oxidative muscle possess a rich capillary structure to provide demanded oxygen, and VEGF might be involved in the formation and/or maintenance of this highly capillarized architecture.

  9. Fuzzy fast terminal sliding mode vibration control of a two-connected flexible plate using laser sensors

    Science.gov (United States)

    Qiu, Zhi-cheng; Zhang, Si-ma

    2016-10-01

    A kind of non-contact vibration measurement method for a two-connected flexible piezoelectric plate using laser sensors is proposed. Decoupling of the bending and torsional vibration on measurement and driving control is carried out via using two laser displacement sensors and piezoelectric actuators. The fuzzy fast terminal sliding mode controller (FFTSMC) is investigated to suppress both the larger and the smaller amplitude vibrations quickly. In order to alleviate the chattering phenomenon and enhance the control effect, the fuzzy logic adaptive algorithm is used to adjust the switching control gain for softening the signum function adaptively. To verify the non-contact measurement method and the designed controller, the experimental setup is built up. Experiments on active vibration control using the designed FFTSMC are conducted, compared with the classical proportional derivative (PD) control algorithm. The experimental identification results demonstrate that the laser displacement sensors can detect the low-frequency bending and torsional vibration effectively, after using the decoupling method. Furthermore, the designed FFTSMC can suppress both bending and torsional vibration more quickly than the designed PD controller owing to the adjustment of the switching control gains and the softening factors, especially for the small amplitude residual vibrations.

  10. Fast-light Enhanced Brillouin Laser Based Active Fiber Optics Sensor for Simultaneous Measurement of Rotation and Acceleration

    CERN Document Server

    Zhou, Minchuan; Fouda, Mohamed; Condon, Nicholas; Scheuer, Jacob; Shahriar, Selim M

    2016-01-01

    We have developed a conceptual design for an Active Fast Light Fiber Optic Sensor (AFLIFOS) that can perform simultaneously or separately as a gyroscope (differential mode effect) and a sensor for acceleration, strain, and other common mode effects. Two Brillouin lasers in opposite directions and separated in frequency by several free spectral ranges are used for this sensor. By coupling two auxiliary resonators to the primary fiber resonator, we produce superluminal effects for two laser modes. We develop a detailed theoretical model for optimizing the design of the AFLIFOS, and show that the enhancement factor of the sensitivity is $\\sim{187}$ and $\\sim{-187}$, respectively for the two Brillouin lasers under the optimized condition, when the effective change in perimeter of the primary fiber resonator is 0.1nm, corresponding to a rotation rate of 0.4 deg/sec for a ring resonator with radius 1m. It may be possible to get much higher enhancement by adjusting the parameters such as the perimeters and the coupl...

  11. Fast and intuitive programming of adaptive laser cutting of lace enabled by machine vision

    Science.gov (United States)

    Vaamonde, Iago; Souto-López, Álvaro; García-Díaz, Antón

    2015-07-01

    A machine vision system has been developed, validated, and integrated in a commercial laser robot cell. It permits an offline graphical programming of laser cutting of lace. The user interface allows loading CAD designs and aligning them with images of lace pieces. Different thread widths are discriminated to generate proper cutting program templates. During online operation, the system aligns CAD models of pieces and lace images, pre-checks quality of lace cuts and adapts laser parameters to thread widths. For pieces detected with the required quality, the program template is adjusted by transforming the coordinates of every trajectory point. A low-cost lace feeding system was also developed for demonstration of full process automation.

  12. Towards fast femtosecond laser micromachining of fused silica: The effect of deposited energy.

    Science.gov (United States)

    Rajesh, Sheeba; Bellouard, Yves

    2010-09-27

    Femtosecond laser micromachining of glass material using low-energy, sub-ablation threshold pulses find numerous applications in the fields of integrated optics, lab-on-a-chips and microsystems in general. In this paper, we study the influence of the laser-deposited energy on the performance of the micromachining process. In particular, we show that the energy deposited in the substrate affects its etching rate. Furthermore, we demonstrate the existence of an optimal energy deposition value. These results are not only important from an industrial point-of-view but also provide new evidences supporting the essential role of densification and consequently stress-generation as the main driving factor promoting enhanced etching rate following laser exposure.

  13. Ultra-fast laser microprocessing of medical polymers for cell engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, R. [Ultraprecision Processes Unit, Fundación IK4-TEKNIKER, Iñaki Goenaga 5, 20600, Eibar, Gipuzkoa (Spain); Moreno-Flores, S., E-mail: susana.moreno-flores@boku.ac.at [Biosurfaces Unit, CIC biomaGUNE, Po Miramón, 182, 20009, San Sebastián, Donostia (Spain); Quintana, I., E-mail: iban.quintana@tekniker.es [Ultraprecision Processes Unit, Fundación IK4-TEKNIKER, Iñaki Goenaga 5, 20600, Eibar, Gipuzkoa (Spain); Micro and Nanoengineering Unit, CIC microGUNE, Goiru Kalea 9, 20500, Arrasate-Mondragón, Gipuzkoa (Spain); Vivanco, MdM [Cell Biology and Stem Cells Unit, CIC bioGUNE, Technology Park of Bizkaia, Ed. 801A, 48160 Derio (Spain); Sarasua, J.R. [University of the Basque Country (EHU-UPV), School of Engineering, Department of Mining and Metallurgy Engineering and Materials Science, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Toca-Herrera, J.L. [Biosurfaces Unit, CIC biomaGUNE, Po Miramón, 182, 20009, San Sebastián, Donostia (Spain); Micro and Nanoengineering Unit, CIC microGUNE, Goiru Kalea 9, 20500, Arrasate-Mondragón, Gipuzkoa (Spain)

    2014-04-01

    Picosecond laser micromachining technology (PLM) has been employed as a tool for the fabrication of 3D structured substrates. These substrates have been used as supports in the in vitro study of the effect of substrate topography on cell behavior. Different micropatterns were PLM-generated on polystyrene (PS) and poly-L-lactide (PLLA) and employed to study cellular proliferation and morphology of breast cancer cells. The laser-induced microstructures included parallel lines of comparable width to that of a single cell (which in this case is roughly 20 μm), and the fabrication of square-like compartments of a much larger area than a single cell (250,000 μm{sup 2}). The results obtained from this in vitro study showed that though the laser treatment altered substrate roughness, it did not noticeably affect the adhesion and proliferation of the breast cancer cells. However, pattern direction directly affected cell proliferation, leading to a guided growth of cell clusters along the pattern direction. When cultured in square-like compartments, cells remained confined inside these for eleven incubation days. According to these results, laser micromachining with ultra-short laser pulses is a suitable method to directly modify the cell microenvironment in order to induce a predefined cellular behavior and to study the effect of the physical microenvironment on cell proliferation. - Highlights: • Microstructuring of biocompatible polymers by ultra-short pulsed laser technology. • Contact guidance effect on a supracellular scale along microgrooved substrates. • Cell confinement inside square compartments. • Fabrication of a 3D microenvironment that induces predefined behavior of cells.

  14. Fast random number generation with spontaneous emission noise of a single-mode semiconductor laser

    Science.gov (United States)

    Zhang, Jianzhong; Zhang, Mingjiang; Liu, Yi; Li, Pu; Yi, Xiaogang; Zhang, Mingtao; Wang, Yuncai

    2016-11-01

    We experimentally demonstrate a 12.5 Gb s-1 random number generator based on measuring the spontaneous emission noise of a single-mode semiconductor laser. The spontaneous emission of light is quantum mechanical in nature and is an inborn physical entropy source of true randomness. By combining a high-speed analog-to-digital converter and off-line processing, random numbers are extracted from the spontaneous emission with the verified randomness. The generator is simple, robust, and with no need of accurately tuning the comparison threshold. The use of semiconductor lasers makes it particularly compatible with the delivery of random numbers in optical networks.

  15. Fast continuous tuning of terahertz quantum-cascade lasers by rear-facet illumination

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Martin, E-mail: hempel@pdi-berlin.de; Röben, Benjamin; Schrottke, Lutz; Grahn, Holger T. [Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5–7, 10117 Berlin (Germany); Hübers, Heinz-Wilhelm [Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstr. 2, 12489 Berlin (Germany); Department of Physics, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany)

    2016-05-09

    GaAs-based terahertz quantum-cascade lasers (QCLs) are continuously tuned in their emission frequency by illuminating the rear facet with a near-infrared, high-power diode laser. For QCLs emitting around 3.1 THz, the maximum tuning range amounts to 2.8 GHz for continuous-wave operation at a heat sink temperature of 55 K, while in pulsed mode 9.1 and 8.0 GHz are achieved at 35 and 55 K, respectively.

  16. Capillary electrophoresis with laser-induced fluorescence detection for fast and reliable apolipoprotein E genotyping

    NARCIS (Netherlands)

    Somsen, GW; Welten, HTME; Mulder, FP; Swart, CW; Kema, IP; de Jong, GJ

    2002-01-01

    The use of capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection for the rapid determination of apolipoprotein E (apoE) genotypes was studied. High resolution and sensitive detection of the concerned DNA restriction fragments was achieved using CE buffers with hydroxypropylm

  17. Fast single-photon avalanche diode arrays for laser Raman spectroscopy

    NARCIS (Netherlands)

    Blacksberg, J.; Maruyama, Y.; Charbon, E.; Rossman, G.R.

    2011-01-01

    We incorporate newly developed solid-state detector technology into time-resolved laser Raman spectroscopy, demonstrating the ability to distinguish spectra from Raman and fluorescence processes. As a proof of concept, we show fluorescence rejection on highly fluorescent mineral samples willemite an

  18. Fast imaging of laser induced plasma emission of vanadium dioxide (VO2) target

    CSIR Research Space (South Africa)

    Masina, BN

    2013-10-01

    Full Text Available The main objective of this study is to fully optimise the synthesis of vanadium oxide nanostructures using pulsed laser deposition. We will attempt to realise this by studying the mechanism of the plasma formation and expansion during the pulsed...

  19. Optimization of ultra-fast interactions using laser pulse temporal shaping controlled by a deterministic algorithm

    Science.gov (United States)

    Galvan-Sosa, M.; Portilla, J.; Hernandez-Rueda, J.; Siegel, J.; Moreno, L.; Ruiz de la Cruz, A.; Solis, J.

    2014-02-01

    Femtosecond laser pulse temporal shaping techniques have led to important advances in different research fields like photochemistry, laser physics, non-linear optics, biology, or materials processing. This success is partly related to the use of optimal control algorithms. Due to the high dimensionality of the solution and control spaces, evolutionary algorithms are extensively applied and, among them, genetic ones have reached the status of a standard adaptive strategy. Still, their use is normally accompanied by a reduction of the problem complexity by different modalities of parameterization of the spectral phase. Exploiting Rabitz and co-authors' ideas about the topology of quantum landscapes, in this work we analyze the optimization of two different problems under a deterministic approach, using a multiple one-dimensional search (MODS) algorithm. In the first case we explore the determination of the optimal phase mask required for generating arbitrary temporal pulse shapes and compare the performance of the MODS algorithm to the standard iterative Gerchberg-Saxton algorithm. Based on the good performance achieved, the same method has been applied for optimizing two-photon absorption starting from temporally broadened laser pulses, or from laser pulses temporally and spectrally distorted by non-linear absorption in air, obtaining similarly good results which confirm the validity of the deterministic search approach.

  20. Fast single-photon avalanche diode arrays for laser Raman spectroscopy

    NARCIS (Netherlands)

    Blacksberg, J.; Maruyama, Y.; Charbon, E.; Rossman, G.R.

    2011-01-01

    We incorporate newly developed solid-state detector technology into time-resolved laser Raman spectroscopy, demonstrating the ability to distinguish spectra from Raman and fluorescence processes. As a proof of concept, we show fluorescence rejection on highly fluorescent mineral samples willemite an

  1. Kilohertz sources of hard x rays and fast ions with femtosecond laser plasmas

    Science.gov (United States)

    Thoss, A.; Richardson, M.; Korn, G.; Faubel, M.; Stiel, H.; Vogt, U.; Elsaesser, T.

    2003-01-01

    We demonstrate a new, stable, kilohertz femtosecond laser plasma source of hard-x-ray continuum and Kα emission that uses a microscopic liquid jet target that is continuous and debris free. Plasmas produced by ultrashort (50-fs) intense laser pulses from a fine (10-30-μm diameter) liquid Ga jet emit bright 9.3- and 10.3-keV Kα and Kβ lines superimposed on a multikilovolt bremmstrahlung continuum. Kilohertz femtosecond x-ray sources will find many applications in time-resolved x-ray diffraction and microscopy studies. As high-intensity lasers become more compact and operate at increasingly high repetition-rates, they require a target configuration that is both repeatable from shot to shot and debris free. Our target provides a pristine, unperturbed filament surface at rates >100 kHz. A number of liquid metal targets are considered. We show the hard-x-ray spectrum described above. The source was generated by a 50-fs-duration, 1-kHz, 2-W, high-intensity Ti:sapphire laser. Using the same technology, we also generate forward-going sub-mega-electron-volt (sub-MeV) protons from a 10-μm liquid water target at 1-kHz repetition rates. Kilohertz sources of high-energy ions will find many applications in time-resolved particle interaction studies and will lead to efficient generation of short-lived isotopes for use in nuclear medicine and other applications. The protons were detected with CR-39 track detectors in both the forward and the backward directions up to energies of ~500 keV. As the intensity of compact high-repetition-rate lasers sources increases, we can expect improvements in the energy, conversion efficiency, and directionality to occur. The effect of these developments is discussed. As compact, high-repetition-rate femtosecond laser technology reaches focused intensities of ~1019 W/cm2, many new applications of high-repetition-rate hard-x-ray and MeV ion sources will become practical.

  2. Measurement of Moments and Radii of Light Nuclei by Collinear Fast-Beam Laser Spectroscopy and $\\beta$-NMR Spectroscopy

    CERN Multimedia

    Marinova, K P

    2002-01-01

    Nuclear Moments and radii of light unstable isotopes are investigated by applying different high-sensitivity and high-resolution techniques based on collinear fast-beam laser spectroscopy. A study of nuclear structure in the sd shell is performed on neon isotopes in the extended chain of $^{17-28}$Ne, in particular on the proton-halo candidate $^{17}$Ne. Measurements of hyperfine structure and isotope shift have become possible by introducing an ultra-sensitive non-optical detection method which is based on optical pumping, state-selective collisional ionization and $\\beta$-activity counting. The small effect of nuclear radii on the optical isotope shifts of light elements requires very accurate measurements. The errors are dominated by uncertainties of the Doppler shifts which are conventionally determined from precisely measured acceleration voltages. These uncertainties are removed by measuring the beam energy with simultaneous excitation of two optical lines in parallel / antiparallel beam configuration. ...

  3. Experimental Study of a Pulsed Ytterbium-Doped Fibre Laser with Fast and Slow Saturable Absorbers in a Linear Cavity

    Institute of Scientific and Technical Information of China (English)

    GAN Yu; XIANG Wang-Hua; ZHOU Xiao-Fang; ZHANG Gui-Zhong; ZHANG Bing; WANG Yong-Gang; MA Xiao-Yu

    2006-01-01

    @@ We present a linear-cavity stretched-pulse fibre laser with mode locking by a nonlinear polarization rotation and by semiconductor saturable-absorber mirrors. A Q-switched mode-locking cw train and a mode-locking pulse train are obtained in the experiment. We investigate the effects of the equivalent fast saturable absorber and the slow saturable absorbers in experiment. It is found that neither the nonlinear polarization evolution effect nor a semiconductor saturable absorber mirror is enough to produce the stable cw mode-locking pulses in this experiment. A nonlinear polarization evolution effect controls the cavity loss to literally carve the pulses;semiconductor saturable absorber mirrors provide the self-restarting and maintain the stability of the modelocking operation.

  4. Simplified model for fast optimization of a free-electron laser oscillator

    Directory of Open Access Journals (Sweden)

    Kai Li

    2017-03-01

    Full Text Available A simplified one-dimensional theoretical model for free-electron laser oscillator (FELO calculation which reserves the main physics is proposed. Instead of using traditional macroparticles sampling method, the theoretical model takes advantage of low gain theory to calculate the optical power single-pass gain in the undulator analytically, and some reasonable approximations are made to simplify the calculation of power growth in the cavity. The theoretical analysis of single-pass gain, power growth, time-dependent laser profile evolution and cavity desynchronism are accomplished more efficiently. We present the results of infrared wavelength FELO and X-ray FELO with the new model. The results are validated by simulation with GENESIS and OPC.

  5. A Simplified Model for Fast Optimization of Free-Electron Laser Oscillator

    CERN Document Server

    Li, Kai; Deng, Haixiao

    2016-01-01

    A simplified theoretical model for free-electron laser oscillator (FELO) simulation which reserves the main physics is proposed. In stead of using traditional macro particles sampling method, the theoretical model takes advantages of low gain theory to calculate the optical power single-pass gain in the undulator analytically, and some reasonable approximations are made to simplify the calculation of power growth in the cavity. The theoretical analysis of single-pass gain, power growth, time-dependent laser profile evolution and cavity desynchronism are accomplished more efficiently. We present the results of infrared wavelength FELO and X-ray FELO with the new model. The results is checked by simulation with GENESIS and OPC which demonstrates the validity of the theoretical model.

  6. Probing of Fast Chemical Dynamics at High Pressures and Temperatures using Pulsed Laser Techniques

    Science.gov (United States)

    2014-12-17

    Goncharov. Hydrogen (deuterium) vibron frequency as a pressure comparison gauge at multi-Mbar pressures, Journal of Applied Physics, (08 2013): 73505...V. Struzhkin, Innokenty Kantor, Mark L. Rivers , D. Allen Dalton. X-ray diffraction in the pulsed laser heated diamond anvil cell, Review of...few-layered two-dimensional MoS2 in collaboration with Avinash Nayak and Professor Jung-Fu Lin at the University of Texas at Austin

  7. Measurement of time dilation by laser spectroscopy on fast stored Lithium ions

    OpenAIRE

    Reinhardt, S.

    2005-01-01

    In der hier vorgelegten Arbeit werden Frequenzmessungen an schnellen Lithium Ionen als Test der Zeitdilatation vorgestellt. Die Messungen sind am Speicherring TSR am Max-Planck-Institut für Kernphysik durchgeführt worden. Die Übergangsfrequenz eines Zwei-Niveau-Systems im Lithium Ion wird bestimmt, indem eine dopplerfreie Fluoreszens-Sättigungsspektroskopie verwendet wird. Die Spektroskopie wird durch zwei gegenläufige Laser verwirklicht, die kollinear zum Ionenstrahl sind. Zwei Messungen bei...

  8. 26 CFR 1.812-5 - Offset.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Offset. 1.812-5 Section 1.812-5 Internal Revenue... and Loss from Operations § 1.812-5 Offset. (a) Offset defined. Section 812(d) defines the term “offset... offset is only that portion of the increase in the operations loss deduction for the taxable year...

  9. Concept of a Staged FEL Enabled by Fast Synchrotron Radiation Cooling of Laser-Plasma Accelerated Beam by Solenoidal Magnetic Fields in Plasma Bubble

    CERN Document Server

    Seryi, Andrei; Andreev, Alexander; Konoplev, Ivan

    2016-01-01

    A novel method for generating GigaGauss solenoidal field in laser-plasma bubble, using screw-shaped laser pulses, has been recently presented in arXiv:1604.01259 [physics.plasm-ph]. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper we present an outline of how a staged plasma-acceleration FEL could look like and discuss further studies needed to investigate the feasibility of the concept in detail.

  10. kHz femtosecond laser-plasma hard X-ray and fast ion source

    Science.gov (United States)

    Thoss, A.; Korn, G.; Richardson, M. C.; Faubel, M.; Stiel, H.; Voigt, U.; Siders, C. W.; Elsaesser, T.

    2002-04-01

    We describe the first demonstration of a new stable, kHz femtosecond laser-plasma source of hard x-ray continuum and Kα emission using a thin liquid metallic jet target. kHz femtosecond x-ray sources will find many applications in time-resolved x-ray diffraction and microscopy studies. As high intensity lasers become more compact and operate at increasingly high repetition-rates, they require a target configuration that is both repeatable from shot-to-shot and is debris-free. We have solved this requirement with the use of a fine (10-30 μm diameter) liquid metal jet target that provides a pristine, unperturbed filament surface at rates >100 kHz. A number of liquid metal targets are considered. We will show hard x-ray spectra recorded from liquid Ga targets that show the generation of the 9.3 keV and 10.3 keV, Kα and Kβ lines superimposed on a multi-keV Bremsstrahlung continuum. This source was generated by a 50fs duration, 1 kHz, 2W, high intensity Ti:Sapphire laser. We will discuss the extension of this source to higher powers and higher repetition rates, providing harder x-ray emission, with the incorporation of pulse-shaping and other techniques to enhance the x-ray conversion efficiency. Using the same liquid target technology, we have also demonstrated the generation of forward-going sub-MeV protons from a 10 μm liquid water target at 1 kHz repetition rates. kHz sources of high energy ions will find many applications in time-resolved particle interaction studies, as well as lead to the efficient generation of short-lived isotopes for use in nuclear medicine and other applications. The protons were detected with CR-39 track detectors both in the forward and backward directions up to energies of ~500 keV. As the intensity of compact high repetition-rate lasers sources increase, we can expect improvements in the energy, conversion efficiency and directionality to occur. The impact of these developments on a number of fields will be discussed. As compact

  11. 二极管激光器快轴光束准直%Fast axis beam collimation of diode laser

    Institute of Scientific and Technical Information of China (English)

    郭林辉; 高松信; 吕文强; 武德勇; 唐淳

    2011-01-01

    二极管激光器泵浦模块输出光束发散角小、指向精度高,但其中的快轴准直(FAC)微透镜装调工艺不能满足大功率模块的应用要求,针对此问题,分析了快轴准直微透镜的光束准直原理,简述了应用FAC透镜时的参数选择和装调问题.通过光学成像方法实时监测二极管激光巴条(bar)的近场像和远场像,对FAC透镜分别进行粗调节和细调节,获得了20个巴条连续输出2kW垂直阵列二极管激光快轴准直光束远场发散角( 1/e2)4.4 mrad、巴条间准直光束指向精度不大于±1.7 mrad的准直效果.最后,结合垂直阵列二极管激光器的封装流程,对影响阵列快轴光束准直效果的因素进行了分析,指出了下一步工艺优化的重点.%The output beam of diode laser vertical stack has the characteristics of small divergence angle and high pointing accuracy, but the adjustment technology can not meet the requirement of diode laser vertical stack with high-power. Beam collimation mechanism of the fast axis collimation (FAC) microlens was described in this paper, and the parameters chosen for device and adjustments of lens were analyzed. The images of diode laser bar both in the near field and far field were real-time monitored through optical imaging methods to realize coarse and fine adjustments of FAC lens, respectively. The output power of the 20-bar vertical stack was 2 kW, and the far field divergence angle of fast axis collimated beam was 4.4 mrad, with the pointing accuracy among bars of less than ±1.7 mrad. Finally, the monitoring precision and the collimation influence factors were analyzed, and the key of optimization was pointed out.

  12. Fast algorithms for calculating laser wavefront phase compensation given noisy measurements of phase gradient

    Science.gov (United States)

    Gavel, Don

    1989-09-01

    Laser light propagating through atmosphere will become distorted as a result of the changing index of refraction along the light path. Wavefront distortions can be actively compensated using adaptive optic systems, which sense the wavefront aberations and compensate by changing the shape of a reflecting surface. Corrections must be done rapidly in order to keep up with the variations in the atmosphere. Numerically, the calculation of the correcting surface is a least-squares fit problem. However, since a typical adaptive optic system has a large number of actuators and sensors, the ordinary solution methods, such as Gaussian elimination, are infeasible for real time application. Instead, advantage must be taken of the structure and sparseness of the equations in order to speed up the calculation. The algorithm proposed requires only O(nq) calculation steps and uses only O(n) memory storage, where n is the total number of actuators and q is the influence width of a single actuator. The derivation of the proposed algorithm, proofs of convergence, and results of several test runs are presented. The algorithm was incorporated into Y division's ORACLE simulation code where it is used to calculate the phase conjugate surfaces necessary to precompensate a high powered laser beam for atmospheric propagation.

  13. Spatially offset Raman spectroscopy based on a line-scan hyperspectral Raman system

    Science.gov (United States)

    Spatially offset Raman spectroscopy (SORS) is a technique that can obtain subsurface layered information by collecting Raman spectra from a series of surface positions laterally offset from the excitation laser. The current methods of SORS measurement are typically either slow due to mechanical move...

  14. Design concept and performance considerations for fast high power semiconductor switching for high repetition rate and high power excimer laser

    Science.gov (United States)

    Goto, Tatsumi; Kakizaki, Kouji; Takagi, Shigeyuki; Satoh, Saburoh; Shinohe, Takashi; Ohashi, Hiromichi; Endo, Fumihiko; Okamura, Katsuya; Ishii, Akira; Teranishi, Tsuneharu; Yasuoka, Koichi

    1997-07-01

    A semiconductor switching power supply has been developed, in which a novel structure semiconductor device, metal-oxide-semiconductor assisted gate-triggered thyristor (MAGT) was incorporated with a single stage magnetic pulse compression circuit (MPC). The MAGT was specially designed to directly replace thyratrons in a power supply for a high repetition rate laser. Compared with conventional high power semiconductor switching devices, it was designed to enable a fast switching, retaining a high blocking voltage and to extremely reduce the transient turn-on power losses, enduring a higher peak current. A maximum peak current density of 32 kA/cm2 and a current density risetime rate di/dt of 142 kA/(cm2×μs) were obtained at the chip area with an applied anode voltage of 1.5 kV. A MAGT switching unit connecting 32 MAGTs in series was capable of switching on more than 25 kV-300 A at a repetition rate of 5 kHz, which, coupled with the MPC, was equivalent to the capability of a high power thyratron. A high repetition rate and high power XeCl excimer laser was excited by the power supply. The results confirmed the stable laser operation of a repetition rate of up to 5 kHz, the world record to our knowledge. An average output power of 0.56 kW was obtained at 5 kHz where the shortage of the total discharge current was subjoined by a conventional power supply with seven parallel switching thyratrons, simultaneously working, for the MAGT power supply could not switch a greater current than that switched by one thyratron. It was confirmed by those excitations that the MAGT unit with the MPC could replace a high power commercial thyratron directly for excimer lasers. The switching stability was significantly superior to that of the thyratron in a high repetition rate region, judging from the discharge current wave forms. It should be possible for the MAGT unit, in the future, to directly switch the discharge current within a rise time of 0.1 μs with a magnetic assist.

  15. Note: Fast compact laser shutter using a direct current motor and three-dimensional printing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Grace H., E-mail: ghzhang0@mit.edu; Braverman, Boris; Kawasaki, Akio; Vuletić, Vladan [Department of Physics, MIT-Harvard Center for Ultracold Atoms and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-15

    We present a mechanical laser shutter design that utilizes a direct current electric motor to rotate a blade which blocks and unblocks a light beam. The blade and the main body of the shutter are modeled with computer aided design (CAD) and are produced by 3D printing. Rubber flaps are used to limit the blade’s range of motion, reducing vibrations and preventing undesirable blade oscillations. At its nominal operating voltage, the shutter achieves a switching speed of (1.22 ± 0.02) m/s with 1 ms activation delay and 10 μs jitter in its timing performance. The shutter design is simple, easy to replicate, and highly reliable, showing no failure or degradation in performance over more than 10{sup 8} cycles.

  16. Fast Compact Laser Shutter Using a Direct Current Motor and 3D Printing

    CERN Document Server

    Zhang, Grace H; Kawasaki, Akio; Vuletić, Vladan

    2015-01-01

    We present a mechanical laser shutter design that utilizes a DC electric motor to rotate a blade which blocks and unblocks a light beam. The blade and the main body of the shutter are modeled with computer aided design (CAD) and are produced by 3D printing. Rubber flaps are used to limit the blade's range of motion, reducing vibrations and preventing undesirable blade oscillations. At its nominal operating voltage, the shutter achieves a switching speed of (1.22 $\\pm$ 0.02) m/s with 1 ms activation delay and 10 $\\mu$s jitter in its timing performance. The shutter design is simple, easy to replicate, and highly reliable, showing no failure or degradation in performance over more than $10^8$ cycles.

  17. Fast phosphor picosecond streak tube for ultrafast laser diagnostics in repetitive mode

    Science.gov (United States)

    Ageeva, N. V.; Gornostaev, P. B.; Ivanova, S. R.; Kulechenkova, T. P.; Levina, G. P.; Lozovoi, V. I.; Makushina, V. A.; Schelev, M. Ya; Shashkov, E. V.; Scaballanovich, T. A.; Smirnov, A. V.; Vereschagin, A. K.; Vereschagin, K. A.; Vorobiev, N. S.

    2015-08-01

    The well-established PIF-01/S1/P43 picosecond streak tube, designed 30 years ago and still manufactured at the A.M. Prokhorov General Physics Institute, was modified by replacing its traditional P43 phosphor screen with a P47 one having approximately three orders of magnitude shorter decay time. The experimental measurements of this decay time were provided by PIF-01/S1/P47 image tube photocathode irradiation either with a single or a train of 8 ps laser pulses separated by 8 ns from each other at a 1.08 μm wavelength. The results of our preliminary measurements of P47-BH phosphor (manufactured by Phosphor Technology Ltd) indicate the possibility of employing the PIF-01/S1/P47 streak tube for synchrotron diagnostics at a units megahertz repetition rate without the negative influence of ‘ghost images’ from the previous streak records.

  18. Rarefaction after fast laser heating of a thin metal film on a glass mount

    Science.gov (United States)

    Inogamov, N. A.; Khokhov, V. A.; Petrov, Y. V.; Zhakhovsky, V. V.; Migdal, K. P.; Ilnitsky, D. K.; Hasegawa, N.; Nishikino, M.; Yamagiwa, M.; Ishino, M.; Kawachi, T.; Faenov, A. Y.; Pikuz, T. A.; Baba, M.; Minami, Y.; Suemoto, T.

    2017-01-01

    Understanding the physics of laser-matter interactions in ultrashort pulses is important for many well-acknowledged applications from material modifications to biology. We numerically and experimentally consider the effect of sub-picosecond Ti:sapp laser actions on 60-100 nm gold films mounted onto a fused silica substrate. The pulse energy is sufficient to ablate the films. For the first time, we show that there are different regimes of ablation, and the formation of the 3D structures depends on the value of the absorbed fluence Fabs and the adhesion strength padh between the film and the substrate. Namely, a delamination threshold Fdelam and an ablation threshold Fabl (Fdelam < Fabl) exist if adhesion is weak. Above the lower threshold Fdelam, the whole film delaminates from the substrate. Above the higher threshold Fabl, the thin film ruptures near its middle plane. The external half of the film flies away, while the internal half remains on the glass substrate. There are two thresholds Fdelam and Fabl for the Au/glass and Ag/glass targets, because pure gold and silver are weakly coupled to the glass. The lower threshold Fdelam disappears in the case of a strong adhesion stress padh. Consequently, delamination as a whole becomes impossible. Although the rupture of a film remains because the ablation threshold Fabl is independent of on adhesion. Adhesion is high when an intermediate thin layer of chromium is placed between the gold and the glass. The film velocity after it separates from the substrate is low for the range of fluences Fdelam < F < Fabl because the acoustic impedance Zglass of glass is small relative to the impedance Zfilm of a gold film. Therefore, during an evolution, the absolute values (positive or negative) of the contact pressures are few times smaller than the absolute pressures in a gold film. However, above the ablation threshold Fabl < F, the velocity of the external part of a film becomes few times larger because the velocity is

  19. Combining terrestrial laser scanning and UAV photogrammetry for fast and lightweight surveying

    Science.gov (United States)

    Conforti, Dario

    2015-04-01

    To create detailed and accurate 3D maps of small- to medium-sized areas surveyors often turn to a terrestrial laser scanner (TLS). A TLS can make thousands of lidar measurements per second with centimeter-level accuracy even at long ranges, using scanning mirrors to aim the laser up/down and left/right for full coverage of the target area. One limitation of using a TLS is that complex objects may require many more TLS survey positions than simpler ones. Since protrusions may block line of sight to certain areas that can only be seen from particular angles, surveyors must survey from several additional locations to make sure the entire area is covered. This is particularly true for setups where the scanner cannot be elevated to gain line of sight to all the areas that are required to be surveyed. To resolve this issue, surveyors often turn to aerial survey vehicles. An aerial vehicle's bird's-eye perspective resolves features easily and its mobility lets the surveyor quickly capture the whole survey region from multiple angles. To survey more efficiently, surveyors can combine the strengths of TLS and airborne systems, resulting in a cost-effective method of mapping small- to medium-sized sites with 3D data and imagery. This process uses a standard TLS to survey from a few points around the area of interest, particularly vertical faces that would be difficult to survey from the air. Simultaneously, the surveyor uses a lightweight UAV equipped with a camera, gimbal, and basic GPS receiver to collect photogrammetric imagery over the site. During post-processing, the aerial imagery is processed to create 3D data of its own using automated triangulation software. This aerial 3D data is then merged with the 3D data created by the TLS. The aerial 3D data is discarded where it conflicts with the more precise TLS data, but is used to fill in the gaps in the areas where the TLS could not collect any data at all. Finally, the resultant 3D data is merged with the original

  20. Effect of helium-neon laser on fast excitatory postsynaptic potential (f-EPSP) of neurons in the isolated rat superior cervical ganglia

    Science.gov (United States)

    Hua, Mo; Ping, He; Ning, Mo

    2002-06-01

    Single electrical stimulation of the cervical sympathetic trunk elicits in the ganglion cells an excitatory postsynaptic potential (EPSP) or multiple EPSPs of varying latencies, among which a fast excitatory postsynaptic potential (f-EPSP) is the main type of ganglionic transmission in the sympathetic neurons. In previous work, we studied the effects of Helium-Neon laser with wavelength 632.8 nm on membrane conductance of neurons with stable f- EPSP in isolated rat superior cervical ganglia. The aim of this study is to further measure the effect of Helium-Neon Laser with wavelength 632.8 nm on fast excitatory postsynaptic potential of postganglionic neurons in the isolated rate superior cervical ganglia by means of intracellular recording techniques. The neurons with fast excitatory postsynaptic potential were irradiated by different power densities (1 and 5 mW/cm2), pulse frequency of 1 Hz laser. Irradiated by the 2 mW/cm2 laser, the amplitude of the f-EPSP could augment (PEPSP could descend and lasted for 3- 8 minutes later.

  1. Fast and Robust STEM Reconstruction in Complex Environments Using Terrestrial Laser Scanning

    Science.gov (United States)

    Wang, D.; Hollaus, M.; Puttonen, E.; Pfeifer, N.

    2016-06-01

    Terrestrial Laser Scanning (TLS) is an effective tool in forest research and management. However, accurate estimation of tree parameters still remains challenging in complex forests. In this paper, we present a novel algorithm for stem modeling in complex environments. This method does not require accurate delineation of stem points from the original point cloud. The stem reconstruction features a self-adaptive cylinder growing scheme. This algorithm is tested for a landslide region in the federal state of Vorarlberg, Austria. The algorithm results are compared with field reference data, which show that our algorithm is able to accurately retrieve the diameter at breast height (DBH) with a root mean square error (RMSE) of ~1.9 cm. This algorithm is further facilitated by applying an advanced sampling technique. Different sampling rates are applied and tested. It is found that a sampling rate of 7.5% is already able to retain the stem fitting quality and simultaneously reduce the computation time significantly by ~88%.

  2. Identification of quantum dots labeled metallothionein by fast scanning laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Konecna, Marie [Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Novotny, Karel [Central European Institute of Technology, Masaryk University, Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Krizkova, Sona [Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Blazkova, Iva [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Kopel, Pavel [Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Kaiser, Jozef [Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Institute of Physical Engineering, Brno University of Technology, Technicka 2, CZ-616 69 Brno (Czech Republic); Hodek, Petr [Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, CZ-128 00 Prague,Czech Republic (Czech Republic); Kizek, Rene [Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno (Czech Republic); and others

    2014-11-01

    The technique described in this paper allows detection of quantum dots (QDs) specifically deposited on the polystyrene surface by laser-induced breakdown spectroscopy (LIBS). Using LIBS, the distribution of QDs or their conjugates with biomolecules deposited on the surface can be observed, regardless of the fact if they exhibit fluorescence or not. QDs deposited on the specific surface of polystyrene microplate in the form of spots are detected by determination of the metal included in the QDs structure. Cd-containing QDs (CdS, CdTe) stabilized with mercaptopropionic (MPA) or mercaptosuccinic (MSA) acid, respectively, alone or in the form of conjugates with metallothionein (MT) biomolecule are determined by using the 508.58 nm Cd emission line. The observed absolute detection limit for Cd in CdTe QDs conjugates with MT in one spot was 3 ng Cd. Due to the high sensitivity of this technique, the immunoanalysis in combination with LIBS was also investigated. Cd spatial distribution in sandwich immunoassay was detected. - Highlights: • We describe determination of biomolecules labeled with quantum dots by LIBS. • LIBS and immunoassay are applied for the determination of metallothionein. • Metallothionein amount detected by LIBS is 10-times lower compared to ELISA.

  3. Microfiber-based few-layer black phosphorus saturable absorber for ultra-fast fiber laser

    CERN Document Server

    Luo, Zhi-Chao; Guo, Zhi-Nan; Jiang, Xiao-Fang; Luo, Ai-Ping; Zhao, Chu-Jun; Yu, Xue-Feng; Xu, Wen-Cheng; Zhang, Han

    2015-01-01

    Few-layer black phosphorus (BP), as the most alluring graphene analogue owing to its similar structure as graphene and thickness dependent direct band-gap, has now triggered a new wave of research on two-dimensional (2D) materials based photonics and optoelectronics. However, a major obstacle of practical applications for few-layer BPs comes from their instabilities of laser-induced optical damage. Herein, we demonstrate that, few-layer BPs, fabricated through the liquid exfoliation approach, can be developed as a new and practical saturable absorber (SA) by depositing few-layer BPs with microfiber. The saturable absorption property of few-layer BPs had been verified through an open-aperture z-scan measurement at the telecommunication band and the microfiber-based BP device had been found to show a saturable average power of ~4.5 mW and a modulation depth of 10.9%, which is further confirmed through a balanced twin detection measurement. By further integrating this optical SA device into an erbium-doped fiber...

  4. 31 CFR 285.7 - Salary offset.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Salary offset. 285.7 Section 285.7... IMPROVEMENT ACT OF 1996 Disbursing Official Offset § 285.7 Salary offset. (a) Purpose and scope. (1) This section establishes FMS's procedures for the centralized offset of Federal salary payments to...

  5. 45 CFR 30.12 - Administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Administrative offset. 30.12 Section 30.12 Public... Administrative Collection of Debts § 30.12 Administrative offset. (a) Scope. (1) Administrative offset is the... made under, the Internal Revenue Code or the tariff laws of the United States; (iv) Offsets...

  6. 7 CFR 1951.111 - Salary offset.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true Salary offset. 1951.111 Section 1951.111 Agriculture... REGULATIONS (CONTINUED) SERVICING AND COLLECTIONS Offsets of Federal Payments to USDA Agency Borrowers § 1951.111 Salary offset. Salary offset may be used to collect debts arising from delinquent USDA...

  7. 45 CFR 608.3 - Administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Administrative offset. 608.3 Section 608.3 Public... AND ADMINISTRATIVE OFFSET § 608.3 Administrative offset. (a) If NSF is unable to collect a claim from... administrative offset subject to the procedures and limitations of 31 U.S.C. 3716 and the applicable...

  8. 19 CFR 201.204 - Salary offset.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Salary offset. 201.204 Section 201.204 Customs... § 201.204 Salary offset. (a) Notice requirements before offset where the Commission is the creditor... the employee with a written Notice of Intent to Offset a minimum of 30 calendar days before...

  9. 31 CFR 240.10 - Offset.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Offset. 240.10 Section 240.10 Money... STATES TREASURY General Provisions § 240.10 Offset. (a) If a reclamation debt remains unpaid for 120 days... centralized offset program (see 31 CFR part 285) or another Federal agency for offset in accordance with 31...

  10. Optimization of the operational parameters in a fast axial flow CW CO 2 laser using artificial neural networks and genetic algorithms

    Science.gov (United States)

    Adineh, V. R.; Aghanajafi, C.; Dehghan, G. H.; Jelvani, S.

    2008-11-01

    This paper presents an artificial intelligence approach for optimization of the operational parameters such as gas pressure ratio and discharge current in a fast-axial-flow CW CO 2 laser by coupling artificial neural networks and genetic algorithm. First, a series of experiments were used as the learning data for artificial neural networks. The best-trained network was connected to genetic algorithm as a fitness function to find the optimum parameters. After the optimization, the calculated laser power increases by 33% and the measured value increases by 21% in an experiment as compared to a non-optimized case.

  11. A Fast and in-Situ Measuring Method Using Laser Triangulation Sensors for the Parameters of the Connecting Rod.

    Science.gov (United States)

    Li, Xing-Qiang; Wang, Zhong; Fu, Lu-Hua

    2016-10-12

    The connecting rod is a critical part inside the marine engine. The inspection of its important parameters is directly related to the assembly and quality of the marine engine. A coordinate measuring machine (CMM) is a conventional choice to measure the parameters of a connecting rod. However, CMM requires significant resources in time and cost, which leads researchers into in-situ measurement. This article presents a fast and in-situ measuring method by using a laser-based measuring head. Two measuring strategies are adopted in the inspection process. For positional measurements (such as the hole-center distance), whose accuracy requirement is generally low, the coordinate system of the numerical control (NC) machine is combined with the measuring head to acquire the positional parameters. For dimensional measurements (such as inner diameters), whose accuracy requirement is rather high, the NC machine is used just as transportation. Note that the measuring head has the ability to perform the dimension inspection independently. The accuracy of the measuring head is high enough to meet the dimensional accuracy requirements. Experiments are performed to validate the proposed method. The measuring error of the inner diameters is from 5 μm to 7 μm. The measuring error of hole-center distance is within 15 μm. The measurement of all these parameters can be done within 1 min.

  12. Raster image correlation spectroscopy (RICS) for measuring fast protein dynamics and concentrations with a commercial laser scanning confocal microscope.

    Science.gov (United States)

    Brown, C M; Dalal, R B; Hebert, B; Digman, M A; Horwitz, A R; Gratton, E

    2008-01-01

    Raster image correlation spectroscopy (RICS) is a new and novel technique for measuring molecular dynamics and concentrations from fluorescence confocal images. The RICS technique extracts information about molecular dynamics and concentrations from images of living cells taken on commercial confocal systems. Here we develop guidelines for performing the RICS analysis on an analogue commercial laser scanning confocal microscope. Guidelines for typical instrument settings, image acquisition settings and analogue detector characterization are presented. Using appropriate instrument/acquisition parameters, diffusion coefficients and concentrations can be determined, even for highly dynamic dye molecules in solution. Standard curves presented herein demonstrate the ability to detect protein concentrations as low as approximately 2 nM. Additionally, cellular measurements give accurate values for the diffusion of paxillin-enhanced-green fluorescent protein (EGFP), an adhesion adaptor molecule, in the cytosol of the cell and also show slower paxillin dynamics near adhesions where paxillin interacts with immobile adhesion components. Methods are presented to account for bright immobile structures within the cell that dominate spatial correlation functions; allowing the extraction of fast protein dynamics within and near these structures. A running average algorithm is also presented to address slow cellular movement or movement of cellular features such as adhesions. Finally, methods to determine protein concentration in the presence of immobile structures within the cell are presented. A table is presented giving guidelines for instrument and imaging setting when performing RICS on the Olympus FV300 confocal and these guidelines are a starting point for performing the analysis on other commercial confocal systems.

  13. Intensity-Stabilized Fast-Scanned Direct Absorption Spectroscopy Instrumentation Based on a Distributed Feedback Laser with Detection Sensitivity down to 4 × 10−6

    Science.gov (United States)

    Zhao, Gang; Tan, Wei; Jia, Mengyuan; Hou, Jiajuan; Ma, Weiguang; Dong, Lei; Zhang, Lei; Feng, Xiaoxia; Wu, Xuechun; Yin, Wangbao; Xiao, Liantuan; Axner, Ove; Jia, Suotang

    2016-01-01

    A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS) instrumentation, based on a distributed feedback (DFB) diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN). The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz), followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS) can be swiftly performed down to a limit of detection (LOD) (1σ) of 4 × 10−6, which opens up a number of new applications. PMID:27657082

  14. Intensity-Stabilized Fast-Scanned Direct Absorption Spectroscopy Instrumentation Based on a Distributed Feedback Laser with Detection Sensitivity down to 4 × 10−6

    Directory of Open Access Journals (Sweden)

    Gang Zhao

    2016-09-01

    Full Text Available A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS instrumentation, based on a distributed feedback (DFB diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN. The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz, followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS can be swiftly performed down to a limit of detection (LOD (1σ of 4 × 10−6, which opens up a number of new applications.

  15. Spatially resolved measurement of the vibrational temperatures of the plasma in a DC-excited fast-axial-flow CO{sub 2} laser

    Energy Technology Data Exchange (ETDEWEB)

    Toebaert, D.; Desoppere, E. [Univ. of Gent (Belgium). Dept. of Applied Physics; Muys, P. [Radius Engineering NV, Gent (Belgium)

    1995-10-01

    Results of measurements of longitudinally-averaged vibrational and rotational temperatures of CO{sub 2} for different radial positions in the active medium of a fast-axial-flow, dc-excited CO{sub 2} laser are reported. The diagnostic technique which was implemented is high resolution absorption spectroscopy of the laser plasma, using a tunable diode laser (TDL). Two different gas inlet sections for the CO{sub 2} laser were tested: one with a single anode pin in front of a relatively large inlet nozzle, as still commonly used in industrial high-power lasers, and another with multiple anodes symmetrically spaced around the perimeter of the discharge tube, each in front of a small diameter inlet nozzle. It is shown that the latter design is capable of creating an essentially flat profile regarding rotational temperature T{sub R} and combined bending mode (T{sub 2}) and symmetric stretch mode (T{sub 1} {approx} T{sub 2}) temperature, while the asymmetric stretch temperature T{sub 3} exhibits a small central maximum. This type of gain pattern is considered to be beneficial for mode quality. The former, mostly used gas inlet design, fails to provide an adequate gain profile (i.e., flat or centered and symmetrical). The combination of the information provided by the spectroscopic technique and a previously developed theoretical model can prove to be a real design aid for developing compact, high-power, gaussian mode CO{sub 2} lasers for materials processing applications.

  16. Graphic Arts/Offset Lithography.

    Science.gov (United States)

    Hoisington, James; Metcalf, Joseph

    This revised curriculum for graphic arts is designed to provide secondary and postsecondary students with entry-level skills and an understanding of current printing technology. It contains lesson plans based on entry-level competencies for offset lithography as identified by educators and industry representatives. The guide is divided into 15…

  17. On Bimodal Offset Cauchy Distribution

    Directory of Open Access Journals (Sweden)

    Girija S.V.S.

    2013-05-01

    Full Text Available The bivariate Cauchy distribution has received applications in many areas, including biological analyses, clinical trials, stochastic modeling of decreasing failure rate life components, study of labour turnover, queuing theory and reliability (Nayak (1987 and Lee and Gross (1991. In the study of biological analyses, clinical trials and reliability circular distributions will yield suitable results. Circular data arises in a number of different areas such as geological, meteorological, biological and industrial sciences. It is not suggestive to use standard statistical techniques to model circular data, due to the circular geometry of the sample space (p.2 Jammalamadaka and Sen Gupta (2001. It is possible to construct a circular model by transforming a bivariate linear random variate to just its directional component and the resultant model is called ‘offset distribution’. In the literature most of the available circular models were constructed by wrapping a linear model. In recent years some wrapped models were constructed by Dattatreya Rao et al (2007. Here an attempt is made to exploit method of offsetting on Bivariate Cauchy distribution to construct a circular model named by us “OFFSET CAUCHY DISTRIBUTION (OC”. The characteristic function of the Offset Cauchy model is derived and its characteristics are discussed.

  18. Comparative mass spectrometric analyses of Photofrin oligomers by fast atom bombardment mass spectrometry, UV and IR matrix-assisted laser desorption/ionization mass spectrometry, electrospray ionization mass spectrometry and laser desorption/jet-cooling photoionization mass spectrometry.

    Science.gov (United States)

    Siegel, M M; Tabei, K; Tsao, R; Pastel, M J; Pandey, R K; Berkenkamp, S; Hillenkamp, F; de Vries, M S

    1999-06-01

    Photofrin (porfimer sodium) is a porphyrin derivative used in the treatment of a variety of cancers by photodynamic therapy. This oligomer complex and a variety of porphyrin monomers, dimers and trimers were analyzed with five different mass spectral ionization techniques: fast atom bombardment, UV and IR matrix-assisted laser desorption/ionization, electrospray ionization, and laser desorption/jet-cooling photoionization. All five approaches resulted in very similar oligomer distributions with an average oligomer length of 2.7 +/- 0.1 porphyrin units. In addition to the Photofrin analysis, this study provides a side-by-side comparison of the spectra for the five different mass spectrometric techniques.

  19. Fast Ignition Realization Experiment with High-Contrast Kilo-Joule Peta-Watt Laser ``LFEX'' and Strong External Magnetic Field

    Science.gov (United States)

    Fujioka, Shinsuke

    2015-11-01

    We report on progresses of the Fast Ignition Realization Experiment (FIREX) project that has been curried out at the Institute of Laser Engineering to assess the feasibility of high density core heating with a high-power, short-pulse laser including the construction of the Kilo-Joule, Petawatt class LFEX laser system. Our recent studies identify three scientific challenges to achieve high heating efficiency in the fast ignition (FI) scheme with the current GEKKO and LFEX laser systems: (i) control of energy distribution of relativistic electron beam (REB), (ii) guiding and focusing of REB to a fuel core, and (iii) formation of a high areal-density core. The control of the electron energy distribution has been experimentally confirmed by improving the intensity contrast of the LFEX laser up to >109 and an ultra-high contrast of 1011 with a plasma mirror. After the contrast improvement, 50% of the total REB energy is carried by a low energy component of the REB, which slope temperature is close to the ponderomotive scaling value (~ 1 MeV). To guide the electron beam, we apply strong external magnetic field to the REB transport region. Guiding of the REB by 0.6 kT field in a planar geometry has already been demonstrated at LULI 2000 laser facility in a collaborative experiment lead by CELIA-Univ. Bordeaux. Considering more realistic FI scenario, we have performed a similar experiment using the Kilo-Joule LFEX laser to study the effect of guiding and magnetic mirror on the electron beam. A high density core of a laser-imploded 200 μm-diameter solid CD ball was radiographed with picosecond LFEX-produced K-alpha backlighter. Comparisons of the experimental results and integrated simulations using hydrodynamic and electron transport codes suggest that 10% of the efficiency can be achievable with the current GEKKO and LFEX laser system with the success of the above challenges. This work is supported by NIFS (Japan), MEXT/JSPS KAKENHI (Japan), JSPS Fellowship (Japan), ANR

  20. A Novel OFDM Timing Offset Estimation Algorithm

    Institute of Scientific and Technical Information of China (English)

    QIU Yan; QIN Sheng-ping; YUE Guang-xin

    2004-01-01

    In this paper, a novel timing offset estimation algorithm of low complexity is presented, which needs a few pilots. The results of simulation prove that the system performance with timing offset correction is approximate to that over AWGN channel.

  1. Offset implementations for Turkey's International Defense Acquisitions

    OpenAIRE

    2008-01-01

    MBA Professional Report "Offsets" is the umbrella term for a broad range of industrial and commercial "compensatory" practices. Specifically, offset agreements in the defense environment are increasing globally as a percentage of exports. Developed countries with established defense industries use offsets to channel work or technology to their domestic defense companies. Countries with newly industrialized economies are utilizing both military and commercial related offsets that involv...

  2. 28 CFR 11.9 - Administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Administrative offset. 11.9 Section 11.9... Administrative offset. (a) Collection. The organization head may collect a claim pursuant to 31 U.S.C. 3716 from... administrative offset of monies other than salaries payable by the government. Collection by...

  3. 20 CFR 627.708 - Offset process.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Offset process. 627.708 Section 627.708... PROGRAMS UNDER TITLES I, II, AND III OF THE ACT Sanctions for Violations of the Act § 627.708 Offset... funds is repayment. (b) A recipient may request that a debt, or a portion thereof, be offset...

  4. 7 CFR 1951.102 - Administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true Administrative offset. 1951.102 Section 1951.102...) PROGRAM REGULATIONS (CONTINUED) SERVICING AND COLLECTIONS Offsets of Federal Payments to USDA Agency Borrowers § 1951.102 Administrative offset. (a) General. Collections of delinquent debts...

  5. 45 CFR 1177.8 - Administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Administrative offset. 1177.8 Section 1177.8... HUMANITIES NATIONAL ENDOWMENT FOR THE HUMANITIES CLAIMS COLLECTION § 1177.8 Administrative offset. (a) The Endowment may collect debts owed by administrative offset if: (1) The debt is certain in amount; (2)...

  6. 5 CFR 1215.28 - Administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Administrative offset. 1215.28 Section... MANAGEMENT Claims Collection § 1215.28 Administrative offset. (a) The MSPB may collect debts owed by administrative offset if: (1) The debt is certain in amount; (2) Efforts to obtain direct payment have been,...

  7. 46 CFR 505.7 - Administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 9 2010-10-01 2010-10-01 false Administrative offset. 505.7 Section 505.7 Shipping FEDERAL MARITIME COMMISSION GENERAL AND ADMINISTRATIVE PROVISIONS ADMINISTRATIVE OFFSET § 505.7 Administrative offset. (a) If the debtor does not exercise the right to request a review within the...

  8. 34 CFR 31.11 - Offset process.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Offset process. 31.11 Section 31.11 Education Office of the Secretary, Department of Education SALARY OFFSET FOR FEDERAL EMPLOYEES WHO ARE INDEBTED TO THE UNITED STATES UNDER PROGRAMS ADMINISTERED BY THE SECRETARY OF EDUCATION § 31.11 Offset process. (a)...

  9. 28 CFR 11.8 - Salary offset.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Salary offset. 11.8 Section 11.8 Judicial Administration DEPARTMENT OF JUSTICE DEBT COLLECTION Administration of Debt Collection § 11.8 Salary offset. (a) Notice requirements before offset. Deductions under the authority of 5 U.S.C. 5514 will not be...

  10. 5 CFR 837.303 - Annuity offset.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Annuity offset. 837.303 Section 837.303...) REEMPLOYMENT OF ANNUITANTS Coverage and Contributions § 837.303 Annuity offset. (a) Applicability. When the... been waived under 5 U.S.C. 8345(d) or 8465(a)), the pay of the reemployed annuitant shall be offset...

  11. 19 CFR 201.206 - Administrative offset.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Administrative offset. 201.206 Section 201.206... Collection § 201.206 Administrative offset. (a) Collection. The Director may collect a claim pursuant to 31 U... Government by administrative offset of monies payable by the Government. Collection by administrative...

  12. 5 CFR 179.307 - Administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Administrative offset. 179.307 Section 179.307 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CLAIMS COLLECTION STANDARDS Administrative Offset § 179.307 Administrative offset. (a) If the debtor does...

  13. Fast phase switching within the bunch train of the PHIN photo-injector at CERN using fiber-optic modulators on the drive laser

    CERN Document Server

    Divall Csatari, M; Bolzon, B; Bravin, E; Chevallay, E; Dobert, S; Drozdy, A; Fedosseev, V; Hessler, C; Lefevre, T; Livesley, S; Losito, R; Mete, O; Petrarca, M; Rabiller, A N

    2011-01-01

    The future Compact Linear Collider (CLIC) e^-/e^+ collider is based on the two-beam acceleration concept, whereby interleaving electron bunches of the drive beam through a delay loop and combiner rings as well as high peak RF power at 12GHz are created locally to accelerate a second beam, the main beam. One of the main objectives of the currently operational CLIC Test Facility (CTF3) is to demonstrate beam combination from 1.5GHz to 12GHz, which requires satellite-free fast phase-switching of the drive beam with sub-ns speed. The PHIN photo-injector, with the photo-injector laser, provides flexibility in the time structure of the electron bunches produced, by direct manipulation of the laser pulses. A novel fiber modulator-based phase-switching technique allows clean and fast phase-switch at 1.5GHz. This paper describes the switching system based on fiber-optic modulators, and the measurements carried out on both the laser and the electron beam to verify the scheme.

  14. Generation and transport of fast electrons in the interaction of high intensity laser with matter; Generation et transport des electrons rapides dans l'interaction laser-matiere a haut flux

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, H

    2005-10-15

    The general context of this study is the Inertial Confinement for thermonuclear controlled fusion and, more precisely, the Fast Igniter (FI). In this context the knowledge of the generation and transport of fast electrons is crucial. This thesis is an experimental study of the generation and transport of fast electrons in the interaction of a high intensity laser ({>=} 10{sup 19} W/cm{sup 2}) with a solid target. The main diagnostic used here is the transition radiation. This radiation depends on the electrons which produce it and thus it gives important information on the electrons: energy, temperature, propagation geometry, etc. The spectral, temporal and spatial analysis permitted to put in evidence the acceleration of periodic electron bunches which, in this case, emit a Coherent Transition Radiation (CTR). During this thesis we have developed some theoretical models in order to explain the experimental results. We find this way two kinds of electron bunches, emitted either at the laser frequency ({omega}{sub 0}), either at the double of this frequency (2{omega}{sub 0}), involving several acceleration mechanisms: vacuum heating / resonance absorption and Lorentz force, respectively. These bunches are also observed in the PIC (particle-in-cell) simulations. The electron temperature is of about 2 MeV in our experimental conditions. The electrons are emitted starting from a point source (which is the laser focal spot) and then propagate in a ballistic way through the target. In some cases they can be re-injected in the target by the electrostatic field from the target edges. This diagnostic is only sensitive to the coherent relativistic electrons, which explains the weak total energy that they contain (about a few mJ). The CTR signal emitted by those fast electrons is largely dominating the signal emitted by the less energetic electrons, even if they contain the major part of the energy (about 1 J). (author)

  15. Application of Gaussian beam ray-equivalent model and back-propagation artificial neural network in laser diode fast axis collimator assembly.

    Science.gov (United States)

    Yu, Hao; Rossi, Giammarco; Braglia, Andrea; Perrone, Guido

    2016-08-10

    The paper presents the development of a tool based on a back-propagation artificial neural network to assist in the accurate positioning of the lenses used to collimate the beam from semiconductor laser diodes along the so-called fast axis. After training using a Gaussian beam ray-equivalent model, the network is capable of indicating the tilt, decenter, and defocus of such lenses from the measured field distribution, so the operator can determine the errors with respect to the actual lens position and optimize the diode assembly procedure. An experimental validation using a typical configuration exploited in multi-emitter diode module assembly and fast axis collimating lenses with different focal lengths and numerical apertures is reported.

  16. Offset analgesia is reduced in older adults.

    Science.gov (United States)

    Naugle, Kelly M; Cruz-Almeida, Yenisel; Fillingim, Roger B; Riley, Joseph L

    2013-11-01

    Recent studies indicate that aging is associated with dysfunctional changes in pain modulatory capacity, potentially contributing to increased incidence of pain in older adults. However, age-related changes in offset analgesia (offset), a form of temporal pain inhibition, remain poorly characterized. The purpose of this study was to investigate age differences in offset analgesia of heat pain in healthy younger and older adults. To explore the peripheral mechanisms underlying offset, an additional aim of the study was to test offset at 2 anatomical sites with known differences in nociceptor innervation. A total of 25 younger adults and 20 older adults completed 6 offset trials in which the experimental heat stimulus was presented to the volar forearm and glabrous skin of the palm. Each trial consisted of 3 continuous phases: an initial 15-second painful stimulus (T1), a slight increase in temperature from T1 for 5 seconds (T2), and a slight decrease back to the initial testing temperature for 10 seconds (T3). During each trial, subjects rated pain intensity continuously using an electronic visual analogue scale (0-100). Older adults demonstrated reduced offset compared to younger adults when tested on the volar forearm. Interestingly, offset analgesia was nonexistent on the palm for all subjects. The reduced offset found in older adults may reflect an age-related decline in endogenous inhibitory systems. However, although the exact mechanisms underlying offset remain unknown, the absence of offset at the palm suggests that peripheral mechanisms may be involved in initiating this phenomenon.

  17. Transverse Dynamics and Energy Tuning of Fast Electrons Generated in Sub-Relativistic Intensity Laser Pulse Interaction with Plasmas

    CERN Document Server

    Mori, M; Daito, I; Kotaki, H; Hayashi, Y; Yamazaki, A; Ogura, K; Sagisaka, A; Koga, J; Nakajima, K; Daido, H; Bulanov, S V; Kimura, T

    2006-01-01

    The regimes of quasi-mono-energetic electron beam generation were experimentally studied in the sub-relativistic intensity laser plasma interaction. The observed electron acceleration regime is unfolded with two-dimensional-particle-in-cell simulations of laser-wakefield generation in the self-modulation regime.

  18. Fast ion energy flux enhancement from ultra thin foils irradiated by intense and high contrast short laser pulses

    NARCIS (Netherlands)

    Andreev, A.; Levy, A.; Ceccotti, T.; Thaury, C.; Platonov, K.; Loch, R.A.; Martin, Ph.

    2008-01-01

    Recent significant improvements of the contrast ratio of chirped pulse amplified pulses allows us to extend the applicability domain of laser accelerated protons to very thin targets. In this framework, we propose an analytical model particularly suitable to reproducing ion laser acceleration

  19. Efficient generation of highly ionized calcium and titanium plasma columns for collisionally excited soft-x-ray lasers in a fast capillary discharge

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, J.J.; Cortazar, O.D.; Tomasel, F.G.; Szapiro, B.T. (Department of Electrical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States))

    1993-10-01

    Fast discharges through 1.5-mm-diam capillaries have produced dense Ca and Ti plasma columns with an abundance of Ne-like ions, which are of interest for the development of small-scale, collisionally excited soft-x-ray lasers. Current pulses of 30 ns full width at half maximum and peak currents of less than 70 kA produced plasmas with line emission from ions with charge up to the F-like state. Line emission at the wavelengths of the 3[ital p]-3[ital s] and 3[ital d]-3[ital p] transitions of the Ne-like ions has been observed.

  20. BESTIA – The next generation ultra-fast CO{sub 2} laser for advanced accelerator research

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelsky, Igor V., E-mail: igor@bnl.gov; Babzien, Markus; Ben-Zvi, Ilan; Skaritka, John; Polyanskiy, Mikhail N.

    2016-09-01

    Over the last two decades, BNL's ATF has pioneered the use of high-peak power CO{sub 2} lasers for research in advanced accelerators and radiation sources. Our recent developments in ion acceleration, Compton scattering, and IFELs have further underscored the benefits from expanding the landscape of strong-field laser interactions deeper into the mid-infrared (MIR) range of wavelengths. This extension validates our ongoing efforts in advancing CO{sub 2} laser technology, which we report here. Our next-generation, multi-terawatt, femtosecond CO{sub 2} laser will open new opportunities for studying ultra-relativistic laser interactions with plasma in the MIR spectral domain, including new regimes in the particle acceleration of ions and electrons.

  1. Extending laser plasma accelerators into the mid-IR spectral domain with a next-generation ultra-fast CO2 laser

    Science.gov (United States)

    Pogorelsky, I. V.; Babzien, M.; Ben-Zvi, I.; Polyanskiy, M. N.; Skaritka, J.; Tresca, O.; Dover, N. P.; Najmudin, Z.; Lu, W.; Cook, N.; Ting, A.; Chen, Y.-H.

    2016-03-01

    Expanding the scope of relativistic plasma research to wavelengths longer than the λ/≈   0.8-1.1 μm range covered by conventional mode-locked solid-state lasers would offer attractive opportunities due to the quadratic scaling of the ponderomotive electron energy and critical plasma density with λ. Answering this quest, a next-generation mid-IR laser project is being advanced at the BNL ATF as a part of the user facility upgrade. We discuss the technical approach to this conceptually new 100 TW, 100 fs, λ  =   9-11 μm CO2 laser BESTIA (Brookhaven Experimental Supra-Terawatt Infrared at ATF) that encompasses several innovations applied for the first time to molecular gas lasers. BESTIA will enable new regimes of laser plasma accelerators. One example is shock-wave ion acceleration (SWA) from gas jets. We review ongoing efforts to achieve stable, monoenergetic proton acceleration by dynamically shaping the plasma density profile from a hydrogen gas target with laser-produced blast waves. At its full power, 100 TW BESTIA promises to achieve proton beams at an energy exceeding 200 MeV. In addition to ion acceleration in over-critical plasma, the ultra-intense mid-IR BESTIA will open up new opportunities in driving wakefields in tenuous plasmas, expanding the landscape of laser wakefield accelerator (LWFA) studies into the unexplored long-wavelength spectral domain. Simple wavelength scaling suggests that a 100 TW CO2 laser beam will be capable of efficiently generating plasma ‘bubbles’ a thousand times greater in volume compared with a near-IR solid state laser of an equivalent power. Combined with a femtosecond electron linac available at the ATF, this wavelength scaling will facilitate the study of external seeding and staging of LWFAs.

  2. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field

    Science.gov (United States)

    Fujioka, Shinsuke; Arikawa, Yasunobu; Kojima, Sadaoki; Johzaki, Tomoyuki; Nagatomo, Hideo; Sawada, Hiroshi; Lee, Seung Ho; Shiroto, Takashi; Ohnishi, Naofumi; Morace, Alessio; Vaisseau, Xavier; Sakata, Shohei; Abe, Yuki; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Shigemori, Keisuke; Hironaka, Yoichiro; Zhang, Zhe; Sunahara, Atsushi; Ozaki, Tetsuo; Sakagami, Hitoshi; Mima, Kunioki; Fujimoto, Yasushi; Yamanoi, Kohei; Norimatsu, Takayoshi; Tokita, Shigeki; Nakata, Yoshiki; Kawanaka, Junji; Jitsuno, Takahisa; Miyanaga, Noriaki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kondo, Kotaro; Bailly-Grandvaux, Mathieu; Bellei, Claudio; Santos, João Jorge; Azechi, Hiroshi

    2016-05-01

    A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKO-XII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >109. Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused by imploding

  3. A FREQUENCY OFFSET ESTIMATION ALGORITHM FOR OFDM SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new fine carrier frequency offset estimation algorithm in Orthogonal Frequency Division Multiplexing (OFDM) system is proposed. The correlation item is the training sequence instead of the received signal in the new algorithm. Simulation results show that the performance of the new algorithm is 4dB-9dB better than that of Schmidl's algorithm. Coarse frequency offset estimation is also discussed in this paper, which is the improvement of Zhang's method. The estimation range using the improvement method is twice as that using the Zhang's method. Based on the hardware of the receiver and the improved algorithm, a method using Fast Fourier Transform (FFT) is proposed to implement the coarse frequency estimation. The chip area of OFDM system can be reduced by using the proposed method.

  4. Ultra-Fast All-Optical Self-Aware Protection Switching Based on a Bistable Laser Diode

    DEFF Research Database (Denmark)

    An, Yi; Vukovic, Dragana; Lorences Riesgo, Abel;

    2014-01-01

    We propose a novel concept of all-optical protection switching with link failure automatic awareness based on AOWFF. The scheme is experimentally demonstrated using a single MG-Y laser diode with a record switching time ~200 ps.......We propose a novel concept of all-optical protection switching with link failure automatic awareness based on AOWFF. The scheme is experimentally demonstrated using a single MG-Y laser diode with a record switching time ~200 ps....

  5. 31 CFR 29.517 - Collection by offset.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Collection by offset. 29.517 Section... Collection of Overpayments § 29.517 Collection by offset. (a) Offset from retirement payments. An overpayment...) Offset from other payments—(1) Administrative offset. When offset under subsection (a) is not...

  6. More General Optimal Offset Assignment

    Directory of Open Access Journals (Sweden)

    Sven Mallach

    2015-06-01

    Full Text Available This manuscript presents exact approaches to the general offset assignment problem arising in the address code generation phase of compilers for application-specific processors. First, integer programming models for architecture-dependent and theoretically motivated special cases of the problem are established. Then, these models are extended to provide the first widely applicable formulations for the most general problem setting, supporting processors with several address registers and complex addressing capabilities. Existing heuristics are similarly extended and practical applicability of the proposed methods is demonstrated by experimental evaluation using an established and large benchmark set. The experiments allow us to study the impact of exploiting more complex memory addressing capabilities on the address computation costs of real-world programs. We also show how to integrate operand reordering techniques for commutative instructions into existing solution approaches.

  7. Antenna Axis Offset Estimation from VLBI

    Science.gov (United States)

    Kurdubov, Sergey; Skurikhina, Elena

    2010-01-01

    The antenna axis offsets were estimated from global solutions and single sessions. We have built a set of global solutions from R1 and R4 sessions and from the sets of sessions between SVETLOE repairs. We compared our estimates with local survey data for the stations of the QUASAR network. Svetloe station axis offset values have changed after repairs. For non-global networks, the axis offset value of a single station can significantly affect the EOP estimations.

  8. On FAST3D simulations of directly-driven inertial-fusion targets with high-Z layers for reducing laser imprint and surface non-uniformity growth

    Science.gov (United States)

    Bates, Jason; Schmitt, Andrew; Klapisch, Marcel; Karasik, Max; Obenschain, Steve

    2013-10-01

    Modifications to the FAST3D code have been made to enhance its ability to simulate the dynamics of plastic ICF targets with high-Z overcoats. This class of problems is challenging computationally due in part to plasma conditions that are not in a state of local thermodynamic equilibrium and to the presence of mixed computational cells containing more than one material. Recently, new opacity tables for gold, palladium and plastic have been generated with an improved version of the STA code. These improved tables provide smoother, higher-fidelity opacity data over a wider range of temperature and density states than before, and contribute to a more accurate treatment of radiative transfer processes in FAST3D simulations. Furthermore, a new, more efficient subroutine known as ``MMEOS'' has been installed in the FAST3D code for determining pressure and temperature equilibrium conditions within cells containing multiple materials. We will discuss these topics, and present new simulation results for high-Z planar-target experiments performed recently on the NIKE Laser Facility. Work supported by DOE/NNSA.

  9. Ultra-fast Movies Resolve Ultra-short Pulse Laser Ablation and Bump Formation on Thin Molybdenum Films

    Science.gov (United States)

    Domke, Matthias; Rapp, Stephan; Huber, Heinz

    For the monolithic serial interconnection of CIS thin film solar cells, 470 nm molybdenum films on glass substrates must be separated galvanically. The single pulse ablation with a 660 fs laser at a wavelength of 1053 nm is investigated in a fluence regime from 0.5 to 5.0 J/cm2. At fluences above 2.0 J/cm2 bump and jet formation can be observed that could be used for creating microstructures. For the investigation of the underlying mechanisms of the laser ablation process itself as well as of the bump or jet formation, pump probe microscopy is utilized to resolve the transient ablation behavior.

  10. High power lasers: Sources, laser-material interactions, high excitations, and fast dynamics in laser processing and industrial applications; Proceedings of the Meeting, The Hague, Netherlands, Mar. 31-Apr. 3, 1987

    Science.gov (United States)

    Kreutz, E. W. (Editor); Quenzer, Alain (Editor); Schuoecker, Dieter (Editor)

    1987-01-01

    The design and operation of high-power lasers for industrial applications are discussed in reviews and reports. Topics addressed include the status of optical technology in the Netherlands, laser design, the deposition of optical energy, laser diagnostics, nonmetal processing, and energy coupling and plasma formation. Consideration is given to laser-induced damage to materials, fluid and gas flow dynamics, metal processing, and manufacturing. Graphs, diagrams, micrographs, and photographs are provided.

  11. Offset Correction Techniques for Voltage Sense Amplifiers

    NARCIS (Netherlands)

    Groeneveld, S.

    2006-01-01

    This report deals with offset correction techniques for voltage sense amplifiers and is divided into two different parts: 1) mismatch and 2) offset correction techniques. First a literature study is done on the subject mismatch with specially focus on the future. Mismatch of a transistor is determin

  12. Effect of Fast Curing Lights, Argon Laser, and Plasma Arc on Bond Strengths of Orthodontic Brackets: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    M. Hashem-Hoseini

    2008-12-01

    Full Text Available Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland, the argon laser unit (Bo-5, Iran , and the plasma arc unit (Remecure 15, Belgium. The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek. After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany.Results: The mean bond strengths was 17.344 MPa (SD=4.567 for halogen 19.172 MPa(SD=6.328 for laser and 19.322 MPa (SD=4.036 for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light.

  13. Multiple One-Dimensional Search (MODS) algorithm for fast optimization of laser-matter interaction by phase-only fs-laser pulse shaping

    Science.gov (United States)

    Galvan-Sosa, M.; Portilla, J.; Hernandez-Rueda, J.; Siegel, J.; Moreno, L.; Solis, J.

    2014-09-01

    In this work, we have developed and implemented a powerful search strategy for optimization of nonlinear optical effects by means of femtosecond pulse shaping, based on topological concepts derived from quantum control theory. Our algorithm [Multiple One-Dimensional Search (MODS)] is based on deterministic optimization of a single solution rather than pseudo-random optimization of entire populations as done by commonly used evolutionary algorithms. We have tested MODS against a genetic algorithm in a nontrivial problem consisting in optimizing the Kerr gating signal (self-interaction) of a shaped laser pulse in a detuned Michelson interferometer configuration. The obtained results show that our search method (MODS) strongly outperforms the genetic algorithm in terms of both convergence speed and quality of the solution. These findings demonstrate the applicability of concepts of quantum control theory to nonlinear laser-matter interaction problems, even in the presence of significant experimental noise.

  14. Offset truss hex solar concentrator

    Science.gov (United States)

    White, John E. (Inventor); Sturgis, James D. (Inventor); Erikson, Raymond J. (Inventor); Waligroski, Gregg A. (Inventor); Scott, Michael A. (Inventor)

    1991-01-01

    A solar energy concentrator system comprises an offset reflector structure made up of a plurality of solar energy reflector panel sections interconnected with one another to form a piecewise approximation of a portion of a (parabolic) surface of revolution rotated about a prescribed focal axis. Each panel section is comprised of a plurality of reflector facets whose reflective surfaces effectively focus reflected light to preselected surface portions of the interior sidewall of a cylindrically shaped solar energy receiver. The longitudinal axis of the receiver is tilted at an acute angle with respect to the optical axis such that the distribution of focussed solar energy over the interior surface of the solar engine is optimized for dynamic solar energy conversion. Each reflector panel section comprises a flat, hexagonally shaped truss support framework and a plurality of beam members interconnecting diametrically opposed corners of the hexagonal framework recessed within which a plurality of (spherically) contoured reflector facets is disposed. The depth of the framework and the beam members is greater than the thickness of a reflector facet such that a reflector facet may be tilted (for controlling the effective focus of its reflected light through the receiver aperture) without protruding from the panel section.

  15. Sinterização ultra-rápida de materiais cerâmicos usando radiação laser Ultra-fast laser sintering of ceramic materials

    Directory of Open Access Journals (Sweden)

    Z. S. Macedo

    2000-12-01

    Full Text Available Nessa comunicação apresentamos nossos primeiros resultados de sinterização ultra-rápida em materiais cerâmicos óxidos usando a radiação de um laser de CO2 como fonte de aquecimento. Os compostos Bi4Ti3O12 (BIT e Bi4Ge3O12 (BGO foram sintetizados via reação do estado sólido, conformados em corpos cerâmicos cilíndricos de 12 mm de diâmetro e 2 mm de espessura e, posteriormente, levados ao laser para o processo de sinterização. A análise dos pós reagidos, efetuada por difratometria de raios X, confirmou a presença de fase cristalina única em cada um dos sistemas investigados. A potência máxima do laser necessária para a sinterização apresentou forte dependência com a estratégia usada na irradiação. A análise da microestrutura, realizada por microscopia eletrônica de varredura (MEV, revelou um alto grau de eficiência do processo desenvolvido. Em alguns casos, pudemos verificar que a sinterização ocorreu a uma profundidade de até 1 mm, apontando para a viabilidade de obtenção de corpos cerâmicos sinterizados como um todo.In this communication we present our first results on ultra-fast laser sintering of oxide ceramics employing a CO2 laser as the heating source. The Bi4Ti3O12 (BIT and Bi4Ge3O12 (BGO compounds were synthesized following a solid state route in air atmosphere. Cylindrical ceramic bodies with 12 mm in diameter and 2 mm in thickness were shaped and sintered under laser irradiation. The X-ray diffraction of the calcined powders confirmed the presence of single phase in each of the investigated systems. The maximum laser power required to the sintering process showed to have a strong dependency on the strategy used for irradiation. The microstructure analysis of the samples, performed by scanning electron microscopy (SEM, revealed the high efficiency of the process. In some cases we could verify that the sintering occurred until a depth of 1mm, indicating the feasibility of obtaining the ceramic bodies

  16. Application of laser scanning microscopy in the development of highly abrasion-resistant glazes for fast-fired hard paste porcelain

    Energy Technology Data Exchange (ETDEWEB)

    Pham-Gia, K.; Moertel, H. [Erlangen-Nuernberg Univ., Erlangen (Germany). Lehrstuhl fuer Glas und Keramik; Melchner, R.; Voit, K. [Porzellanfabrik Christian Seltmann GmbH, Weiden (Germany)

    2001-08-01

    To strengthen the competitiveness of porcelain manufacturers in national and international markets with their ever increasing quality requirements, the research presented was aimed at developing highly abrasion-resistant glazes for fast-fired hard paste porcelain. By increasing the degree of cross-linking in the glass structure, it was possible to improve the mechanical abrasion resistance of porcelain glazes. Uniform and defect-free glaze application is particularly important for achieving this improvement. To determine the abrasion resistance of the glazes, a new testing method was developed in which the glaze surface is analysed topographically with a laser scanning microscope before and after defined sand-blasting and the roughness parameters compared. The glaze development work could be minimized with the help of fractional factorial statistical test planning according to the Taguchi method. (orig.)

  17. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry as a tool for fast identification of protein binders in color layers of paintings.

    Science.gov (United States)

    Hynek, Radovan; Kuckova, Stepanka; Hradilova, Janka; Kodicek, Milan

    2004-01-01

    Identification of materials in color layers of paintings is necessary for correct decisions concerning restoration procedures as well as proving the authenticity of the painting. The proteins are usually important components of the painting layers. In this paper it has been demonstrated that matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) can be used for fast and reliable identification of proteins in color layers even in old, highly aged matrices. The digestion can be easily performed directly on silica wafers which are routinely used for infrared analysis. The amount of material necessary for such an analysis is extremely small. Peptide mass mapping using digestion with trypsin followed by MALDI-TOFMS and identification of the protein was successfully used for determination of the binder from a painting of the 19th century.

  18. Fast Analysis for the Focusing of a Laser Beam with Amplitude Modulation and Phase Fluctuation Through an Aperture Lens

    Institute of Scientific and Technical Information of China (English)

    张彬; 楚晓亮; 李强

    2002-01-01

    Based on the treatment that a rectangular function can be expanded into an approximate sum of complex Gaussian functions with finite numbers, the analytical expression for the focusing intensity distribution of a laser beam with amplitude modulation (AM) and phase fluctuation (PF) through an aperture lens is derived. The typical numerical examples are given and compared with those obtained from numerically integral calculation. The results show that our method can significantly improve the numerical calculation efficiency.

  19. Fast wettability transition from hydrophilic to superhydrophobic laser-textured stainless steel surfaces under low-temperature annealing

    Science.gov (United States)

    Ngo, Chi-Vinh; Chun, Doo-Man

    2017-07-01

    Recently, the fabrication of superhydrophobic metallic surfaces by means of pulsed laser texturing has been developed. After laser texturing, samples are typically chemically coated or aged in ambient air for a relatively long time of several weeks to achieve superhydrophobicity. To accelerate the wettability transition from hydrophilicity to superhydrophobicity without the use of additional chemical treatment, a simple annealing post process has been developed. In the present work, grid patterns were first fabricated on stainless steel by a nanosecond pulsed laser, then an additional low-temperature annealing post process at 100 °C was applied. The effect of 100-500 μm step size of the textured grid upon the wettability transition time was also investigated. The proposed post process reduced the transition time from a couple of months to within several hours. All samples showed superhydrophobicity with contact angles greater than 160° and sliding angles smaller than 10° except samples with 500 μm step size, and could be applied in several potential applications such as self-cleaning and control of water adhesion.

  20. [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.

  1. 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.

  2. 29 CFR 20.85 - Notice of offset.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Notice of offset. 20.85 Section 20.85 Labor Office of the Secretary of Labor FEDERAL CLAIMS COLLECTION Salary Offset § 20.85 Notice of offset. Prior to effecting a salary offset, the paying DOL agency should advise the debtor of the impending offset. This notice...

  3. 22 CFR 34.13 - Notice requirements before offset.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Notice requirements before offset. 34.13... Offset § 34.13 Notice requirements before offset. Except as provided in § 34.16, salary offset deductions... to the Federal Government at least 30 calendar days before salary offset is to be initiated....

  4. Nanosecond-time-resolved infrared spectroscopic study of fast relaxation kinetics of protein folding by means of laser-induced temperature-jump

    Institute of Scientific and Technical Information of China (English)

    Zhang Qing-Li; Wang Li; Weng Yu-Xiang; Qiu Xiang-Gang; Wang Wei-Chi; Yan Ji-Xiang

    2005-01-01

    Elucidating the initial kinetics of folding pathways is critical to the understanding of the protein folding mechanism. Transient infrared spectroscopy has proved a powerful tool to probe the folding kinetics. Herein we report the construction of a nanosecond laser-induced temperature-jump (T-jump) technique coupled to a nanosecond timeresolved transient mid-infrared (mid-IR) spectrometer system capable of investigating the protein folding kinetics with a temporal resolution of 50 ns after deconvolution of the instrumental response function. The mid-IR source is a liquid N2 cooled CO laser covering a spectral range of 5.0μm (2000 cm-1) ~ 6.5μm (1540 cm-1). The heating pulse was generated by a high pressure H2 Raman shifter at wavelength of 1.9μm. The maximum temperature-jump could reach as high as 26±1℃. The fast folding/unfolding dynamics of cytochrome C was investigated by the constructed system,providing an example.

  5. Line-scan spatially offset Raman spectroscopy for inspecting subsurface food safety and quality

    Science.gov (United States)

    This paper presented a method for subsurface food inspection using a newly developed line-scan spatially offset Raman spectroscopy (SORS) technique. A 785 nm laser was used as a Raman excitation source. The line-shape SORS data was collected in a wavenumber range of 0–2815 cm-1 using a detection mod...

  6. Role of fast ignitor in fast-shock ignition concept

    Directory of Open Access Journals (Sweden)

    S. A. Ghasemi

    2014-03-01

    Full Text Available This paper deals with the role of fast ignitor in fast-shock ignition (FSI concept. The semi-analytical model indicates that the FSI target gain is a function of fast ignitor laser wavelength. If the energy of fast ignitor driver is and the laser wavelength is less than 0.53 micron, then with a fuel mass about 2 mg the FSI has a considerable advantage over pure shock ignition and the figure of merit is better than 1.2. When the wavelength of fast ignitor becomes shorter, the approaches , and for wavelengths shorter than 0.25 micron no additional is advantage is obtained.

  7. Measuring fast variations of δ^{18}O and δ^2H in atmospheric water vapour using laser spectroscopy: an instrument inter-comparison and characterisation study

    Science.gov (United States)

    Aemisegger, F.; Sturm, P.; Graf, P.; Sodemann, H.; Pfahl, S.; Knohl, A.; Wernli, H.

    2012-04-01

    Fast variations of stable water isotopes in water vapour have become measurable lately using novel laser spectroscopic techniques. This allows us to perform process-based investigations of the atmospheric water cycle at the time scales of significant weather events. An important prerequisite for such studies implying automatic field measurements lasting for several weeks or even months is a detailed knowledge about sources of uncertainty and instrument properties. We present a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Resarch). The old versions (L1115-i, WVIA) and the new versions (L2130-i, WVIA-EP) of both systems were tested. The uncertainty components of the measurements were assessed in laboratory experiments, focussing on effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Knowledge from our laboratory experiments was used to setup a one-week field campaign for comparing measurements of the ambient isotope signals from the L1115-i and WVIA systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. Using this field measurement data we address the question of how well the deuterium excess (d=δ2H-8δ18O) of atmospheric water vapour can be determined with laser spectroscopy. The deuterium excess is an interesting parameter for process-based atmospheric water cycle studies, which depends on humidity and temperature conditions at source location of water vapour. Up to now only very few high-time-resolution measurements of deuterium excess exist. Our concurrent measurements of atmospheric isotopes in water vapour

  8. Great apes and biodiversity offset projects in Africa: the case for national offset strategies.

    Directory of Open Access Journals (Sweden)

    Rebecca Kormos

    Full Text Available The development and private sectors are increasingly considering "biodiversity offsets" as a strategy to compensate for their negative impacts on biodiversity, including impacts on great apes and their habitats in Africa. In the absence of national offset policies in sub-Saharan Africa, offset design and implementation are guided by company internal standards, lending bank standards or international best practice principles. We examine four projects in Africa that are seeking to compensate for their negative impacts on great ape populations. Our assessment of these projects reveals that not all apply or implement best practices, and that there is little standardization in the methods used to measure losses and gains in species numbers. Even if they were to follow currently accepted best-practice principles, we find that these actions may still fail to contribute to conservation objectives over the long term. We advocate for an alternative approach in which biodiversity offset and compensation projects are designed and implemented as part of a National Offset Strategy that (1 takes into account the cumulative impacts of development in individual countries, (2 identifies priority offset sites, (3 promotes aggregated offsets, and (4 integrates biodiversity offset and compensation projects with national biodiversity conservation objectives. We also propose supplementary principles necessary for biodiversity offsets to contribute to great ape conservation in Africa. Caution should still be exercised, however, with regard to offsets until further field-based evidence of their effectiveness is available.

  9. Great apes and biodiversity offset projects in Africa: the case for national offset strategies.

    Science.gov (United States)

    Kormos, Rebecca; Kormos, Cyril F; Humle, Tatyana; Lanjouw, Annette; Rainer, Helga; Victurine, Ray; Mittermeier, Russell A; Diallo, Mamadou S; Rylands, Anthony B; Williamson, Elizabeth A

    2014-01-01

    The development and private sectors are increasingly considering "biodiversity offsets" as a strategy to compensate for their negative impacts on biodiversity, including impacts on great apes and their habitats in Africa. In the absence of national offset policies in sub-Saharan Africa, offset design and implementation are guided by company internal standards, lending bank standards or international best practice principles. We examine four projects in Africa that are seeking to compensate for their negative impacts on great ape populations. Our assessment of these projects reveals that not all apply or implement best practices, and that there is little standardization in the methods used to measure losses and gains in species numbers. Even if they were to follow currently accepted best-practice principles, we find that these actions may still fail to contribute to conservation objectives over the long term. We advocate for an alternative approach in which biodiversity offset and compensation projects are designed and implemented as part of a National Offset Strategy that (1) takes into account the cumulative impacts of development in individual countries, (2) identifies priority offset sites, (3) promotes aggregated offsets, and (4) integrates biodiversity offset and compensation projects with national biodiversity conservation objectives. We also propose supplementary principles necessary for biodiversity offsets to contribute to great ape conservation in Africa. Caution should still be exercised, however, with regard to offsets until further field-based evidence of their effectiveness is available.

  10. High speed photoacoustic imaging with fast OPO laser at 1.7 μm (Conference Presentation)

    Science.gov (United States)

    Piao, Zhonglie; Teng, Ma; Li, Jiawen; Qu, Yueqiao; Yu, Mingyue; Shung, K. Kirk; Zhou, Qifa; Kim, Chang-Seok; Chen, Zhongping

    2016-03-01

    Acute cardiovascular events are mostly due to a blood clot or thrombus induced by the sudden rupture of vulnerable atherosclerotic plaques within coronary artery walls. Based on the high optical absorption contrast of the lipid rich plaques within the vessel wall, intravascular photoacoustic (IVPA) imaging at 1.7 μm spectral band has shown promising capabilities for detecting of lipid composition, but the translation of the technology for in vivo application is limited by the slow imaging speed. In this work, we will present a high speed integrated IVPA/US imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm (5 nm linewidth). A miniature catheter with 1.0 mm outer diameter was designed with a polished 200 μm multimode fiber and an ultrasound transducer with 45 MHz center frequency. Two optical illumination methods by gradient-index (GRIN) lens and ball lens are introduced and compared for higher spatial resolution. At 1725 nm, atherosclerotic rabbit abdominal aorta was imaged at two frame per second, which is more than one order of magnitude faster than previous reported IVPA imaging. Furthermore, by wide tuning range of the laser wavelength from 1680 nm to 1770 nm, spectroscopic photoacoustic analysis of lipid-mimicking phantom and an human atherosclerotic artery was performed ex vivo.

  11. Frequency-offset separated oscillatory fields

    Science.gov (United States)

    Vutha, A. C.; Hessels, E. A.

    2015-11-01

    A frequency-offset separated-oscillatory-field technique is presented. The technique is a modification of the Ramsey method of separated oscillatory fields [Phys. Rev. 76, 996 (1949), 10.1103/PhysRev.76.996], in which the frequencies of the two separated oscillatory fields are slightly offset from each other, so that the relative phase of the two fields varies continuously with time. With this technique, the detection signal oscillates in time at the offset frequency, and the resonance frequency is obtained by using a simple straight-line fit of the phase of this signal. The technique has the advantages of being insensitive to the frequency response of the experimental system, of being sensitive only to noise at the offset frequency, and of allowing systematic effects to be more cleanly resolved due to the simple lineshape.

  12. Offset detection in GPS coordinate time series

    Science.gov (United States)

    Gazeaux, J.; King, M. A.; Williams, S. D.

    2013-12-01

    Global Positioning System (GPS) time series are commonly affected by offsets of unknown magnitude and the large volume of data globally warrants investigation of automated detection approaches. The Detection of Offsets in GPS Experiment (DOGEx) showed that accuracy of Global Positioning System (GPS) time series can be significantly improved by applying statistical offset detection methods (see Gazeaux et al. (2013)). However, the best of these approaches did not perform as well as manual detection by expert analysts. Many of the features of GPS coordinates time series have not yet been fully taken into account in existing methods. Here, we apply Bayesian theory in order to make use of prior knowledge of the site noise characteristics and metadata in an attempt to make the offset detection more accurate. In the past decades, Bayesian theory has shown relevant results for a widespread range of applications, but has not yet been applied to GPS coordinates time series. Such methods incorporate different inputs such as a dynamic model (linear trend, periodic signal..) and a-priori information in a process that provides the best estimate of parameters (velocity, phase and amplitude of periodic signals...) based on all the available information. We test the new method on the DOGEx simulated dataset and compare it to previous solutions, and to Monte-Carlo method to test the accuracy of the procedure. We make a preliminary extension of the DOGEx dataset to introduce metadata information, allowing us to test the value of this data type in detecting offsets. The flexibility, robustness and limitations of the new approach are discussed. Gazeaux, J. Williams, S., King, M., Bos, M., Dach, R., Deo, M.,Moore, A.W., Ostini, L., Petrie, E., Roggero, M., Teferle, F.N., Olivares, G.,Webb, F.H. 2013. Detecting offsets in GPS time series: First results from the detection of offsets in GPS experiment. Journal of Geophysical Research: Solid Earth 118. 5. pp:2169-9356. Keywords : GPS

  13. Offset Error Compensation in Roundness Measurement

    Institute of Scientific and Technical Information of China (English)

    朱喜林; 史俊; 李晓梅

    2004-01-01

    This paper analyses three causes of offset error in roundness measurement and presents corresponding compensation methods.The causes of offset error include excursion error resulting from the deflection of the sensor's line of measurement from the rotational center in measurement (datum center), eccentricity error resulting from the variance between the workpiece's geometrical center and the rotational center, and tilt error resulting from the tilt between the workpiece's geometrical axes and the rotational centerline.

  14. Offset rejection for PLL based synchronization in grid-connected converters

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Agelidis, Vassilios

    2008-01-01

    Grid-connected converters rely on fast and accurate detection of the phase angle, amplitude and frequency of the utility voltage to guarantee the correct generation of the reference signals. An important issue associated with accurate grid voltage monitoring is the presence of an offset in the me......Grid-connected converters rely on fast and accurate detection of the phase angle, amplitude and frequency of the utility voltage to guarantee the correct generation of the reference signals. An important issue associated with accurate grid voltage monitoring is the presence of an offset...... in the measured grid voltage. This voltage offset is typically introduced by the measurements and data conversion processes and causes errors for the estimated parameters of the grid voltage. Accordingly, this paper presents an offset rejection method for grid-connected converters based on a phase-lockedloop (PLL......) technique. The offset rejection method relies on the second order generalized integrator (SOGI) having the advantages of a simple implementation independent of the grid frequency and avoidance of filtering delays due to its resonance at the fundamental frequency. Selected experimental results validate...

  15. Axis Offset Estimation of VLBI Telescopes

    Science.gov (United States)

    Krásná, Hana; Nickola, Marisa; Böhm, Johannes

    2014-12-01

    Axis offset models have to be applied for VLBI telescopes with pointing axes which do not intersect. In this work, we estimated the axis offsets for VLBI antennas in a global adjustment of suitable IVS 24-hour sessions (1984.0-2014.0) with the Vienna VLBI Software (VieVS). In particular, we focused on the two radio telescopes of the Hartebeesthoek Radio Astronomy Observatory (HartRAO) in South Africa. For the older 26-m telescope we compared the estimated axis offset values before (6699.2 ± 0.5 mm) and after (6707.3 ± 0.8 mm) the bearing repair in 2010. A comparison with axis offset estimates from other geodetic techniques, such as GNSS or conventional local survey, was made. The estimated axis offset for the newer 15-m telescope (1495.0 ± 3.4 mm) agrees with the estimated value from the GPS survey in 2007. Furthermore, we assessed the influence of differences in the axis offsets on the estimated geodetic parameters, such as station coordinates or Earth Orientation Parameters.

  16. Spray- and laser-assisted biomaterial processing for fast and efficient autologous cell-plus-matrix tissue engineering.

    Science.gov (United States)

    Klopsch, Christian; Gäbel, Ralf; Kaminski, Alexander; Mark, Peter; Wang, Weiwei; Toelk, Anita; Delyagina, Evgenya; Kleiner, Gabriela; Koch, Lothar; Chichkov, Boris; Mela, Petra; Jockenhoevel, Stefan; Ma, Nan; Steinhoff, Gustav

    2015-12-01

    At present, intensive investigation aims at the creation of optimal valvular prostheses. We introduced and tested the applicability and functionality of two advanced cell-plus-matrix seeding technologies, spray-assisted bioprocessing (SaBP) and laser-assisted bioprocessing (LaBP), for autologous tissue engineering (TE) of bioresorbable artificial grafts. For SaBP, human mesenchymal stem cells (HMSCs), umbilical cord vein endothelial cells (HUVECs) and fibrin were simultaneously spray-administered on poly(ε-caprolactone) (PCL) substrates. For LaBP, HUVECs and HMSCs were separately laser-printed in stripes, followed by fibrin sealing. Three-leaflet valves were manufactured following TE of electrospun PCL tissue equivalents. Grafts were monitored in vitro under static and dynamic conditions in bioreactors. SaBP and LaBP resulted in TE of grafts with homogeneous cell distribution and accurate cell pattern, respectively. The engineered valves demonstrated immediate sufficient performance, complete cell coating, proliferation, engraftment, HUVEC-mediated invasion, HMSC differentiation and extracellular matrix deposition. SaBP revealed higher efficiency, with at least 12-fold shorter processing time than the applied LaBP set-up. LaBP realized coating with higher cell density and minimal cell-scaffold distance. Fibrin and PCL stability remain issues for improvement. The introduced TE technologies resulted in complete valvular cell-plus-matrix coating, excellent engraftment and HMSCs differentiation. SaBP might have potential for intraoperative table-side TE considering the procedural duration and ease of implementation. LaBP might accelerate engraftment with precise patterns.

  17. Mono-Exponential Fitting in T2-Relaxometry: Relevance of Offset and First Echo.

    Directory of Open Access Journals (Sweden)

    David Milford

    Full Text Available T2 relaxometry has become an important tool in quantitative MRI. Little focus has been put on the effect of the refocusing flip angle upon the offset parameter, which was introduced to account for a signal floor due to noise or to long T2 components. The aim of this study was to show that B1 imperfections contribute significantly to the offset. We further introduce a simple method to reduce the systematic error in T2 by discarding the first echo and using the offset fitting approach.Signal curves of T2 relaxometry were simulated based on extended phase graph theory and evaluated for 4 different methods (inclusion and exclusion of the first echo, while fitting with and without the offset. We further performed T2 relaxometry in a phantom at 9.4T magnetic resonance imaging scanner and used the same methods for post-processing as in the extended phase graph simulated data. Single spin echo sequences were used to determine the correct T2 time.The simulation data showed that the systematic error in T2 and the offset depends on the refocusing pulse, the echo spacing and the echo train length. The systematic error could be reduced by discarding the first echo. Further reduction of the systematic T2 error was reached by using the offset as fitting parameter. The phantom experiments confirmed these findings.The fitted offset parameter in T2 relaxometry is influenced by imperfect refocusing pulses. Using the offset as a fitting parameter and discarding the first echo is a fast and easy method to minimize the error in T2, particularly for low to intermediate echo train length.

  18. Divided-aperture differential confocal fast-imaging microscopy

    Science.gov (United States)

    Wang, Yun; Qiu, Lirong; Zhao, Xiangye; Zhao, Weiqian

    2017-03-01

    A new method, laser divided-aperture differential confocal microscopy (DDCM), is proposed to achieve high-resolution 3D imaging of microstructures of large-scale sample surfaces. This method uses a divided-aperture confocal structure to significantly improve the axial resolution of confocal microscopy and keep a long working distance simultaneously; uses two radically offset point detectors to achieve differential detection to further improve the axial response sensitivity and realize fast imaging of a large-scale sample surface with a big axial scan-step interval. Theoretical analyses and experimental results show that the DDCM can reach an axial resolution of 5 nm with a 3.1 mm working distance with a 3 times imaging speed of a confocal system with the same resolution.

  19. Fast reversible laser-induced crystallization of Sb-rich Zn-Sb-Se phase change material with excellent stability

    Directory of Open Access Journals (Sweden)

    Yimin Chen

    2015-07-01

    Full Text Available We present a new reversible phase-change medium Sb-rich Zn-Sb-Se film, which possesses a large difference in both optical and electrical constant. The doped-ZnSb, sub-formed Zn-Se, and exhausted Sb-Se3/2 co-influence the physical properties. Typically, there is ∼105 resistance ratio and ∼14% relative reflectivity change in Zn19Sb45.7Se35.3 film when switched by electricity or laser pulses between amorphous and crystalline states. The higher Tc (∼250°C, larger Ea (∼8.57eV, better 10-yr data retention (∼200.2°C, higher crystallization resistance (∼3 × 103Ω/□ at 300°C-annealled and relative lower melting temperature (∼550.2°C are exhibited in Zn19Sb45.7Se35.3 film. Importantly, a short crystalline time (∼80ns at 70mW of the ideal Zn19Sb45.7Se35.3 film can be obtained without sacrificing room-temperature stability.

  20. DELPHI - fast and adaptive computational laser point detection and visual footprint quantification for arbitrary underwater image collections

    Directory of Open Access Journals (Sweden)

    Timm eSchoening

    2015-04-01

    Full Text Available Marine researchers continue to create large quantities of benthic images e.g. using AUVs (Autonomous Underwater Vehicles. In order to quantify the size of sessile objects in the images, a pixel-to-centimetre ratio is required for each image, often indirectly provided through a geometric laser point (LP pattern, projected onto the seafloor. Manual annotation of these LPs in all images is too time-consuming and thus infeasible for nowadays data volumes. Because of the technical evolution of camera rigs, the LP's geometrical layout and colour features vary for different expeditions and projects. This makes the application of one algorithm, tuned to a strictly defined LP pattern, also ineffective.Here we present the web-tool DELPHI, that efficiently learns the LP layout for one image transect / collection from just a small number of hand labelled LPs and applies this layout model to the rest of the data. The efficiency in adapting to new data allows to compute the LPs and the pixel-to-centimetre ratio fully automatic and with high accuracy. DELPHI is applied to two real-world examples and shows clear improvements regarding reduction of tuning effort for new LP patterns as well as increasing detection performance.

  1. Job Analysis Schedule--Offset Press Operator (Multilith 1250 W) or Offset Duplicating Machine Operator.

    Science.gov (United States)

    Feyock, Anthony J.

    This paper presents an analysis of the job performed by an offset press operator (alternate title is offset duplicating machine operator) of a Multilith 1250 W. First covered is work performed, as follows: prepares dampening unit for printing run, prepares inking unit for printing, readies printing plate for printing, sets up press for running,…

  2. 10 CFR 13.44 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Right to administrative offset. 13.44 Section 13.44 Energy NUCLEAR REGULATORY COMMISSION PROGRAM FRAUD CIVIL REMEDIES § 13.44 Right to administrative offset. The... collected by administrative offset under 31 U.S.C. 3716, except that an administrative offset may not...

  3. 17 CFR 141.8 - Procedures for salary offset.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Procedures for salary offset... OFFSET § 141.8 Procedures for salary offset. (a) Deductions to liquidate an employee's debt will be by the method and in the amount stated in the Commission's notice of intention to offset as provided...

  4. 29 CFR 1450.10 - Collection by administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Collection by administrative offset. 1450.10 Section 1450... COLLECTIONS OF CLAIMS OWED THE UNITED STATES Administrative Offset-Consumer Reporting Agencies-Contracting for Collection § 1450.10 Collection by administrative offset. (a) Collection by administrative offset will...

  5. 45 CFR 33.4 - Notice requirements before offset.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Notice requirements before offset. 33.4 Section 33.4 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION SALARY OFFSET § 33.4 Notice requirements before offset. (a) At least 30 days before the initiation of salary offset under...

  6. 16 CFR 1027.4 - Notice requirements before offset.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Notice requirements before offset. 1027.4 Section 1027.4 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION GENERAL SALARY OFFSET § 1027.4 Notice requirements before offset. (a) Salary offset shall not be made against an employee's pay...

  7. 7 CFR 3.46 - Offset against tax refunds.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Offset against tax refunds. 3.46 Section 3.46 Agriculture Office of the Secretary of Agriculture DEBT MANAGEMENT Administrative Offset § 3.46 Offset against tax refunds. USDA will take action to effect administrative offset against tax refunds due to...

  8. 41 CFR 105-56.029 - Offset amount.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Offset amount. 105-56... Administration 56-SALARY OFFSET FOR INDEBTEDNESS OF FEDERAL EMPLOYEES TO THE UNITED STATES Centralized Salary Offset (CSO) Procedures-GSA as Paying Agency § 105-56.029 Offset amount. (a) The minimum dollar amount...

  9. 24 CFR 17.102 - Notice requirements before offset.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Notice requirements before offset... Administrative Offset Provisions § 17.102 Notice requirements before offset. Except as provided in § 17.103... Collect by Administrative Offset (Notice of Intent) will state: (a) The nature and amount of the debt:...

  10. 17 CFR 204.38 - Pre-offset hearing.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Pre-offset hearing. 204.38... DEBT COLLECTION Salary Offset § 204.38 Pre-offset hearing. (a) The hearing official shall determine the... of the hearing official. (f) Pre-offset “paper” hearing. If a hearing is to be held only upon...

  11. 24 CFR 17.128 - Notice requirements before offset.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Notice requirements before offset... Salary Offset Provisions § 17.128 Notice requirements before offset. Except as provided in § 17.125(d... days written notice. This Notice of Intent to Offset Salary (Notice of Intent) will state: (a) That...

  12. 14 CFR 1264.143 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Right to administrative offset. 1264.143... PROGRAM FRAUD CIVIL PENALTIES ACT OF 1986 § 1264.143 Right to administrative offset. The amount of any... administrative offset under 31 U.S.C. 3716, except that an administrative offset may not be made under...

  13. 31 CFR 16.44 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Right to administrative offset. 16.44... THE PROGRAM FRAUD CIVIL REMEDIES ACT OF 1986 § 16.44 Right to administrative offset. The amount of any... administrative offset under 31 U.S.C. 3716, except that an administrative offset may not be made under...

  14. 41 CFR 105-56.019 - Offset amount.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Offset amount. 105-56... Administration 56-SALARY OFFSET FOR INDEBTEDNESS OF FEDERAL EMPLOYEES TO THE UNITED STATES Centralized Salary Offset (CSO) Procedures-GSA as Creditor Agency § 105-56.019 Offset amount. (a) The minimum dollar...

  15. 32 CFR 1697.8 - Procedures for salary offset.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Procedures for salary offset. 1697.8 Section... OFFSET § 1697.8 Procedures for salary offset. (a) Deductions to liquidate an employee's debt will be by the method and in the amount stated in the Director's notice of intention to offset as provided...

  16. 49 CFR 80.21 - Use of administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Use of administrative offset. 80.21 Section 80.21... § 80.21 Use of administrative offset. The DOT will not apply an administrative offset to recover any... instrument. The DOT may, however, use an administrative offset in cases of fraud, misrepresentation,...

  17. 41 CFR 105-56.018 - Salary offset.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Salary offset. 105-56... Administration 56-SALARY OFFSET FOR INDEBTEDNESS OF FEDERAL EMPLOYEES TO THE UNITED STATES Centralized Salary Offset (CSO) Procedures-GSA as Creditor Agency § 105-56.018 Salary offset. When a match occurs and...

  18. 29 CFR 20.29 - Notice of offset.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Notice of offset. 20.29 Section 20.29 Labor Office of the Secretary of Labor FEDERAL CLAIMS COLLECTION Administrative Offset § 20.29 Notice of offset. Prior to effecting an administrative offset, the agency holding funds of a debtor should advise the debtor of...

  19. 41 CFR 105-56.004 - Pre-offset notice.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Pre-offset notice. 105... Administration 56-SALARY OFFSET FOR INDEBTEDNESS OF FEDERAL EMPLOYEES TO THE UNITED STATES Salary Offset of General Services Administration Employees § 105-56.004 Pre-offset notice. An employee must be...

  20. 17 CFR 204.33 - Pre-offset notice.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Pre-offset notice. 204.33... DEBT COLLECTION Salary Offset § 204.33 Pre-offset notice. A program official must provide an employee... of offset. The agreement must be in writing, signed by both the employee and the Commission,...

  1. 40 CFR 13.37 - Notice requirement before offset.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Notice requirement before offset. 13.37... STANDARDS Referral of Debts to IRS for Tax Refund Offset § 13.37 Notice requirement before offset. A request... collect by IRS tax refund offset (Notice of Intent) will state: (a) The amount of the debt; (b)...

  2. 12 CFR 313.142 - Request for administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Request for administrative offset. 313.142... PROCEDURES FOR CORPORATE DEBT COLLECTION Civil Service Retirement and Disability Fund Offset § 313.142 Request for administrative offset. The Director shall request administrative offset under § 313.140,...

  3. 41 CFR 105-56.028 - Salary offset.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Salary offset. 105-56... Administration 56-SALARY OFFSET FOR INDEBTEDNESS OF FEDERAL EMPLOYEES TO THE UNITED STATES Centralized Salary Offset (CSO) Procedures-GSA as Paying Agency § 105-56.028 Salary offset. When a match occurs and...

  4. 7 CFR 3.74 - Notice requirements before offset.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Notice requirements before offset. 3.74 Section 3.74 Agriculture Office of the Secretary of Agriculture DEBT MANAGEMENT Federal Salary Offset § 3.74 Notice requirements before offset. Except as provided in paragraph (b) of this section, salary offset will not be...

  5. 29 CFR 1650.110 - Implementation of salary offset.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Implementation of salary offset. 1650.110 Section 1650.110... Procedures for the Collection of Debts by Salary Offset § 1650.110 Implementation of salary offset. (a... by offset will be made in installments. Such installment deductions will be made over a period...

  6. 12 CFR 608.821 - Collection by offset.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Collection by offset. 608.821 Section 608.821... UNITED STATES Administrative Offset § 608.821 Collection by offset. (a) Collection of a debt by administrative offset shall be accomplished in accordance with the provisions of these regulations, of 4 CFR...

  7. 43 CFR 35.44 - Right to administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Right to administrative offset. 35.44... FRAUDULENT CLAIMS AND STATEMENTS § 35.44 Right to administrative offset. The amount of any penalty or... administrative offset under 31 U.S.C. 3716, except that an administrative offset may not be made under...

  8. 47 CFR 1.1912 - Collection by administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Collection by administrative offset. 1.1912... Collection of Claims Owed the United States Administrative Offset-Consumer Reporting Agencies-Contracting for Collection § 1.1912 Collection by administrative offset. (a) Scope. (1) The term administrative offset...

  9. 22 CFR 224.44 - Right to administrative offset.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Right to administrative offset. 224.44 Section... CIVIL REMEDIES ACT § 224.44 Right to administrative offset. The amount of any penalty or assessment... offset under 31 U.S.C. 3716, except that an administrative offset may not be made under the...

  10. 5 CFR 837.701 - Offset from supplemental annuity.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Offset from supplemental annuity. 837.701... REGULATIONS (CONTINUED) REEMPLOYMENT OF ANNUITANTS CSRS Offset § 837.701 Offset from supplemental annuity. (a) OPM will reduce the supplemental annuity of an individual who has performed CSRS-Offset service,...

  11. 49 CFR 89.41 - Notice requirement before offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Notice requirement before offset. 89.41 Section 89... COLLECTION ACT Referral of Debts to IRS for Tax Refund Offset § 89.41 Notice requirement before offset. A request for offset from an IRS tax refund will be made only after the Department has made a...

  12. Performance Analysis of OFDM with Frequency Offset and Correction Model

    Institute of Scientific and Technical Information of China (English)

    QIN Sheng-ping; YIN Chang-chuan; LUO Tao; YUE Guang-xin

    2003-01-01

    The performance of OFDM with frequency offset is analyzed and simulated in this paper. It is concluded that the SIR is very large and the BER of OFDM system with frequency offset is strongly affected. A BER calculating method is introduced and simulated. Assumed that the frequency offset is known, frequency offset correction model is discussed.

  13. Bundled Hybrid Offset Riser Global Strength Analysis

    Institute of Scientific and Technical Information of China (English)

    William C.Webster; Zhuang Kang; Wenzhou Liang; Youwei Kang; Liping Sun

    2011-01-01

    Bundled hybrid offset riser(BHOR)global strength analysis,which is more complex than single line offset riser global strength analysis,was carried out in this paper.At first,the equivalent theory is used to deal with BHOR,and then its global strength in manifold cases was analyzed,along with the use of a three-dimensional nonlinear time domain finite element program.So the max bending stress,max circumferential stress,and max axial stress in the BHOR bundle main section(BMS)were obtained,and the values of these three stresses in each riser were obtained through the "stress distribution method".Finally,the Max Von Mises stress in each riser was given and a check was made whether or not they met the demand.This paper provides a reference for strength analysis of the bundled hybrid offset riser and some other bundled pipelines.

  14. Spatially offset Raman spectroscopy (SORS) for liquid screening

    Science.gov (United States)

    Loeffen, Paul W.; Maskall, Guy; Bonthron, Stuart; Bloomfield, Matthew; Tombling, Craig; Matousek, Pavel

    2011-11-01

    Recently, Spatially Offset Raman Spectroscopy (SORS) has been discussed as a novel method for the screening of liquids, aerosols and gels (LAGs) at airports and for other security applications. SORS is an optical spectroscopic method which enables the precise chemical identification of substances from a reference list and, due to the rich spectral information, has an inherently high probability of detection and low false alarm rate. The method is generally capable of screening substances inside non-metallic containers such as plastic and glass bottles. SORS is typically successful through opaque plastic and coloured glass, which are often challenging for conventional backscatter Raman spectroscopy. SORS is performed in just a few seconds by shining a laser light onto the container and then measuring the Raman signal at the excitation point but also at one or more offset positions. Each measurement has different relative orthogonal contributions from the container and contents Raman spectra, so that, with no prior knowledge, the pure Raman spectra of both the container and contents can be extracted - either by scaled subtraction or via multivariate statistical methods in an automated process. In this paper, the latest results will be described from a prototype SORS device designed for aviation security and the advantages and limitations of SORS will be discussed.

  15. A low power mixed signal DC offset calibration circuit for direct conversion receiver applications

    Science.gov (United States)

    Lijun, Yang; Fang, Yuan; Zheng, Gong; Yin, Shi; Zhiming, Chen

    2011-12-01

    A low power mixed signal DC offset calibration (DCOC) circuit for direct conversion receiver applications is designed. The proposed DCOC circuit features low power consumption, fast settling time and a small die area by avoiding the trade-off between loop response time and the high pass frequency of the DCOC servo loop in conventional analog DCOC systems. By applying the proposed DC offset correction circuitry, the output residue DC offset voltages are reduced to less than 38 mV and the DCOC loop settling time is less than 100 μs. The DCOC chip is fabricated in a standard 0.13-μm CMOS technology and drains only 196 μA from a 1.2-V power supply with its chip area of only 0.372 × 0.419 mm2.

  16. Improved dichotomous search frequency offset estimator for burst-mode continuous phase modulation

    Institute of Scientific and Technical Information of China (English)

    翟文超; 李赞; 司江勃; 柏均

    2015-01-01

    A data-aided technique for carrier frequency offset estimation with continuous phase modulation (CPM) in burst-mode transmission is presented. The proposed technique first exploits a special pilot sequence, or training sequence, to form a sinusoidal waveform. Then, an improved dichotomous search frequency offset estimator is introduced to determine the frequency offset using the sinusoid. Theoretical analysis and simulation results indicate that our estimator is noteworthy in the following aspects. First, the estimator can operate independently of timing recovery. Second, it has relatively low outlier, i.e., the minimum signal-to-noise ratio (SNR) required to guarantee estimation accuracy. Finally, the most important property is that our estimator is complexity-reduced compared to the existing dichotomous search methods: it eliminates the need for fast Fourier transform (FFT) and modulation removal, and exhibits faster convergence rate without accuracy degradation.

  17. Gain and offset analysis of comparator using the bisection theorem and a balanced method

    Science.gov (United States)

    Nessir Zghoul, Fadi; Ay, Suat U.; Ababneh, Ahmad

    2016-12-01

    Gain and offset represent two important measures to determine the accuracy of a comparator. Thus, analysis on these parameters is very important as they offer designers better understanding of the circuit and allow exploring trade-offs during design. In this paper, two methods were presented to derive a set of design equations that describe the gain, sensitivity, offset, and systematic mismatches observed in typical comparator circuits. A three-stage, fast complementary metal-oxide semiconductor (CMOS) comparator structure is analysed and simulated in order to validate the proposed methods. A 0.13 μm CMOS technology is used for simulations with 1.5 V supply voltage. Bisection theorem was used for gain and sensitivity analysis. Simulation results show that high gain improvement can be possible by using the design equations. The input offset voltage, due to mismatch in the width of the metal oxide semiconductor field-effect transistors (MOSFET) (W) and mismatches in the threshold voltages of the N and P type MOSFETs (VTHN, VTHP), is analysed using a proposed balanced method. The same comparator structure is used for the input offset voltage analysis. Simulations show that an offset improvement can be achieved following the design equations found through the proposed method.

  18. Can Exercise Offset Alcohol's Damaging Effects?

    Science.gov (United States)

    ... Videos & Tools Español You Are Here: Home → Latest Health News → Article URL of this page: https://medlineplus.gov/news/fullstory_160853.html Can Exercise Offset Alcohol's Damaging Effects? Even gardening, brisk walking may reduce your risk ...

  19. A Novel Offset Fresnel Zone Plate Antenna

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel offset Fresnel Zone Plate reflector Antenna (FZPA) is proposed, the phase correcting zone of this FZPA is elliptic. Based on Physical Optics Method, the focusing characteristics of the reflector are analyzed. The comparison of this new FZPA with the circular FZPA and Mawzones FZPA is made.

  20. Efficient Fixed-Offset GPR Scattering Analysis

    DEFF Research Database (Denmark)

    Meincke, Peter; Chen, Xianyao

    2004-01-01

    in the scattering calculation the correct radiation patterns of the ground penetrating radar antennas by using their plane-wave transmitting and receiving spectra. Finally, we derive an efficient FFT-based method to analyze a fixed-offset configuration in which the location of the transmitting antenna is different...

  1. Metrics for Offset Printing Press Operation.

    Science.gov (United States)

    Cooper, Gloria S., Ed.; Magisos, Joel H., Ed.

    Designed to meet the job-related metric measurement needs of offset printing press operation students, this instructional package is one of six for the communication media occupations cluster, part of a set of 55 packages for metric instruction in different occupations. The package is intended for students who already know the occupational…

  2. Regenerative similariton laser

    Directory of Open Access Journals (Sweden)

    Thibault North

    2016-05-01

    Full Text Available Self-pulsating lasers based on cascaded reshaping and reamplification (2R are capable of initiating ultrashort pulses despite the accumulation of large amounts of nonlinearities in all-fiber resonators. The spectral properties of pulses in self-similar propagation are compatible with cascaded 2R regeneration by offset filtering, making parabolic pulses suitable for the design of a laser of this recently introduced class. A new type of regenerative laser giving birth to similaritons is numerically investigated and shows that this laser is the analog of regenerative sources based solely on self-phase modulation and offset filtering. The regenerative similariton laser does not suffer from instabilities due to excessive nonlinearities and enables ultrashort pulse generation in a simple cavity configuration.

  3. A Simple Joint Estimation Method of Residual Frequency Offset and Sampling Frequency Offset for DVB Systems

    Science.gov (United States)

    Kwon, Ki-Won; Cho, Yongsoo

    This letter presents a simple joint estimation method for residual frequency offset (RFO) and sampling frequency offset (STO) in OFDM-based digital video broadcasting (DVB) systems. The proposed method selects a continual pilot (CP) subset from an unsymmetrically and non-uniformly distributed CP set to obtain an unbiased estimator. Simulation results show that the proposed method using a properly selected CP subset is unbiased and performs robustly.

  4. On Offset Stream Measurements and Recent Coseismic Surface Rupture in the Carrizo Section of the San Andreas Fault

    Science.gov (United States)

    Brooks, B. A.; Hudnut, K. W.; Akciz, S. O.; Delano, J.; Glennie, C. L.; Prentice, C. S.; DeLong, S.

    2013-12-01

    Recent studies using airborne laser swath mapping (ALSM) topographic data have provoked debate about whether the Mw 7.9 Fort Tejon 1857 earthquake produced ~5m or ~10m of surface strike-slip displacement in the Carrizo section of the south-central San Andreas fault. Resolution of this discrepancy is important not only for understanding the proposed role of the Carrizo section in controlling repeated south-central San Andreas rupture but also for understanding the general utility of stream offset measurements for earthquake process studies. To explore if higher-resolution topographic data of the offset features would help reconcile the different interpretations, we used a mobile laser scanning (MLS) backpack-mounted system to survey 11 ~5m offset streams given 'high' quality rankings by previous studies. In our surveys, point density was on the order of 1000s pts/m^2 in comparison to 1-4 pts/m^2 for the ALSM data, enabling us to faithfully make digital elevation models with grid spacing smaller than 10cm. We adapt a geometric method that relies on a small number of user-dependent decisions to produce an offset estimate from a set of geomorphic markers (thalweg, channel margins, channel shoulders) from upstream and downstream locations. We typically derive an ensemble of at least 10 offset measurements per stream channel and from these calculate a mean and standard deviation. We also explore using gradient changes in long profiles of the offset stream reaches to diagnose the possibility of a ~10m channel experiencing 2 ~5m slip events. Preliminary results suggest a tendency towards the higher value offset estimates, although this does not necessarily preclude the possibility of two or more events causing the cumulative offset.

  5. Cap and trade offsets regulation - consultation paper

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    Due to increasing concerns about the environment, British Columbia has committed to reducing its 2007 greenhouse gas emissions levels by 33% in 2020 and 80% in 2050. To reach those objectives, emissions trading and offset regulations are being developed by the Climate Action Secretariat. The aim of this document is to present a first draft of the regulations to the various stakeholders, including First Nations and the general public, together with the proposed offset eligibility criteria and related process, and to get their feedback. This document is itself part of the 5-phase process of developing the regulations. Following the 45 days during which comments on the proposed regulation were sought, the climate action secretariat will complete legal drafting of the regulations, drawing on help from this stakeholder input, and the regulation will subsequently be implemented. An accompanying response form was attached to this consultation paper.

  6. On significance of VLBI/Gaia offsets

    CERN Document Server

    Petrov, L

    2016-01-01

    We have cross matched the Gaia Data Release 1 secondary dataset that contains positions of 1.14 billion objects against the most complete to date catalogue of VLBI positions of 11.4 thousand sources, almost exclusively active galactic nuclei. We found 6,064 matches, i.e. 53% radio objects. The median uncertainty of VLBI positions is a factor of 4 smaller than the median uncertainties of their optical counterparts. Our analysis shows that the distribution of normalized arc lengths significantly deviates from Rayleighian shape with an excess of objects with small normalized arc lengths and with a number of outliers. We found that 8% matches have radio optical offsets significant at 99% confidence level. Therefore, we conclude there exists a population of objects with genuine offsets between centroids of radio and optical emission.

  7. Offset Dither技术研究

    Institute of Scientific and Technical Information of China (English)

    解本钊

    2007-01-01

    并行交替式ADC系统中采样时间偏差、Offset失配、Gain失配三种系统误差,它们降低了系统的性能.然而,Offset失配误差可以作为Dither信号,通过一定的信号处理可以提高系统的性能.本文研究了这种Offset Dither信号对系统的影响,得出了提高系统分辨力的结论,为Offset Dither技术的应用提供了理论基础.

  8. Mechanism of reverse-offset printing

    Science.gov (United States)

    Choi, Young-Man; Lee, Eonseok; Lee, Taik-Min

    2015-07-01

    We propose a mechanism for reverse-offset printing based on a mathematical model. In reverse-offset printing, high resolution is achieved by patterning a coated, thin ink film with an intaglio-patterned cliché. By using the relationships among the ink blanket adhesion strength, the ink cliché adhesion strength, and the ink cohesion strength, a criterion for successful patterning is derived. We found that there is a printing window in the ink blanket adhesion strength that depends on the shear strength of the ink film and the dimensions of the pattern. The printing window diminishes as the line width decreases, resulting in a minimum printable line width. The proposed mechanism was verified by printing patterns with various shapes and dimensions.

  9. Surface reconstruction by offset surface filtering

    Institute of Scientific and Technical Information of China (English)

    DONG Chen-shi; WANG Guo-zhao

    2005-01-01

    The problem of computing a piecewise linear approximation to a surface from its sample has been a focus of research in geometry modeling and graphics due to its widespread applications in computer aided design. In this paper, we give a new algorithm, to be called offset surface filtering (OSF) algorithm, which computes a piecewise-linear approximation of a smooth surface from a finite set of cloud points. The algorithm has two main stages. First, the surface normal on every point is estimated by the least squares best fitting plane method. Second, we construct a restricted Delaunay triangulation, which is a tubular neighborhood of the surface defined by two offset surfaces. The algorithm is simple and robust. We describe an implementation of it and show example outputs.

  10. Ultrafast Laser Engraving Method to Fabricate Gravure Plate for Printed Metal-Mesh Touch Panel

    Directory of Open Access Journals (Sweden)

    Weiyuan Chen

    2015-10-01

    Full Text Available In order to engrave gravure plate with fine lines structures, conventional art used lithography with dry/wet etching. Lithography with dry/wet etching method allows to engrave lines with smooth concave shape, but its disadvantages include difficulty in controlling aspect ratio, high and uniform in large size process, substrate material limitation due to etching solution availability, and process complexity. We developed ultra-fast laser technology to directly engrave a stainless plate, a gravure plate, to be used for fabricating 23 in. metal-mesh touch panel by gravure offset printing process. The technology employs high energy pulse to ablate materials from a substrate. Because the ultra-fast laser pulse duration is shorter than the energy dissipation time between material lattices, there is no heating issue during the ablation process. Therefore, no volcano-type protrusion on the engraved line edges occurs, leading to good printing quality. After laser engraving, we then reduce surface roughness of the gravure plate using electro-polishing process. Diamond like carbon (DLC coating layer is then added onto the surface to increase scratch resistance. We show that this procedure can fabricate gravure plate for gravure offset printing process with minimum printing linewidth 10.7 μm. A 23 in. metal-mesh pattern was printed using such gravure plate and fully functional touch panel was demonstrated in this work.

  11. On Timing Offset Estimation of OFDM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, a new timing offset estimation method for Orthogonal Frequency Division Multiplexing (OFDM) systems are presented. Upon the receipt of just one training sequence, this presence of a signal and the start of the frame can be detected. The performances of the timing estimator in additive white Gaussian noise and the mobile multipath channel are evaluated by simulation. The results delivered by this algorithm are compared with those delivered by Schmidl and Cox.

  12. Environmental Data on Gravure and Offset Printing

    Directory of Open Access Journals (Sweden)

    Maria Enroth

    2006-12-01

    Full Text Available This paper presents environmental data relating to gravure and offset printing. It focuses on the printing steps in the production chain of publication printed products. The other steps in the life-cycle of printed products have also been studied but they are not the subjects of this paper.The study is based on case studies, where almost twenty gravure printers and ten offset printers from around Europe and the United States have been involved.The general, significant environmental aspects of publication printed products have been identified as the following; use of paper, use of energy, consumption (loss of volatile organic compounds (VOC, including toluene, hazardous waste and environmental management. Transport has also been identified as a significant environmental aspect for printed products but, to a great extent, its magnitude depends on the particular product. The data collected from printers in different parts of the world were compared to environmental data provided by offset printers in Sweden, which were mainly taken from coldset printers.This paper presents significant environmental data for a fairly large number of companies representing a considerable part of the printing capacity, not only in Europe but also worldwide. These data can provide guidance for both printers and buyers of printed products working to achieve continualimprovements and striving towards more environmentally adapted printed products. To some extent, the data can also be used as reference values, since there are few compilations of data providing a general coverage of printers in different parts of the world.

  13. Configurational asymmetry in vernier offset detection.

    Science.gov (United States)

    Karim, A K M Rezaul; Kojima, Haruyuki

    2010-10-06

    Two psychophysical experiments were conducted at the horizontal and vertical orientations respectively, demonstrating substantial main effect of configuration, but no effect of offset direction on vernier acuity. In Experiment 1, a pair of horizontal bars were arranged side by side with a large gap between them. The observers were, on average, significantly better at discriminating a vertical offset if the right-hand bar was below the left-hand bar than vice versa, regardless of which bar they experienced as displaced and which as constant. A similar asymmetry was evident in Experiment 2 where observers judged horizontal offset for a pair of vertically oriented bars, where one was placed above the other. In this case average performance was better if the upper bar was on the right of the lower bar rather than on its left. There were large individual variations in the asymmetrical trend, but the effect could not be explained by subjective response bias. Furthermore, vernier acuity improved significantly and the asymmetry decreased more or less as a function of training. The average asymmetrical trend was consistent across training days and across two orientations, which indicates that the processing of line vernier stimuli is possibly configuration-specific in the cardinal orientation.

  14. Offset Trace-Based Video Quality Evaluation Network Transport

    DEFF Research Database (Denmark)

    Seeling, P.; Reisslein, M.; Fitzek, Frank

    2006-01-01

    after networking transport that includes losses and delays. In this work, we provide (i) an overview of frame dependencies that have to be taken into consideration when working with video traces, (ii) an algorithmic approach to combine traditional video traces and offset distortion traces to determine...... the video quality or distortion after lossy network transport, (iii) offset distortion and quality characteristics and (iv) the offset distortion trace format and tools to create offset distortion traces....

  15. 6 CFR 13.44 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 6 Domestic Security 1 2010-01-01 2010-01-01 false Right to administrative offset. 13.44 Section 13... REMEDIES § 13.44 Right to administrative offset. The amount of any penalty or assessment that has become... compromise or settlement under § 13.46, may be collected by administrative offset under 31 U.S.C....

  16. 22 CFR 521.44 - Right to administrative offset.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Right to administrative offset. 521.44 Section... REMEDIES ACT § 521.44 Right to administrative offset. The amount of any penalty or assessment which has... upon in a compromise or settlement under § 521.46, may be collected by administrative offset under 31...

  17. 40 CFR 13.20 - Administrative offset of general debts.

    Science.gov (United States)

    2010-07-01

    ... deterrent value; (v) Offset does not substantially impair or defeat program objectives; and (vi) Offset is best suited to further and protect the Government's interest. (2) The Administrator may, in determining...) Multiple debts. Where moneys are available for offset against multiple debts of a debtor, it will...

  18. 7 CFR 3.43 - Non-centralized administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Non-centralized administrative offset. 3.43 Section 3.43 Agriculture Office of the Secretary of Agriculture DEBT MANAGEMENT Administrative Offset § 3.43 Non-centralized administrative offset. (a) Scope. In cooperation with the Federal agency certifying...

  19. 49 CFR 89.25 - Collection by administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Collection by administrative offset. 89.25 Section... COLLECTION ACT Collection of Claims § 89.25 Collection by administrative offset. (a) Whenever feasible, after... administrative offset against obligations of the United States to the debtor pursuant to 31 U.S.C. 3716 and 4...

  20. 49 CFR 1017.10 - Procedures for administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 8 2010-10-01 2010-10-01 false Procedures for administrative offset. 1017.10... OFFSET FROM INDEBTED GOVERNMENT AND FORMER GOVERNMENT EMPLOYEES § 1017.10 Procedures for administrative offset. (a) Debts will be collected in one lump sum where possible. If the employee is financially...

  1. 45 CFR 33.10 - Procedures for salary offset.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Procedures for salary offset. 33.10 Section 33.10 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION SALARY OFFSET § 33.10 Procedures for salary offset. (a) Method and source of deductions. Unless the employee and the Secretary...

  2. 7 CFR 3.44 - Centralized administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Centralized administrative offset. 3.44 Section 3.44 Agriculture Office of the Secretary of Agriculture DEBT MANAGEMENT Administrative Offset § 3.44 Centralized administrative offset. (a) Mandatory referral. After the notice and review opportunity requirements of § 3.41...

  3. 49 CFR 1018.28 - Collection by administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 8 2010-10-01 2010-10-01 false Collection by administrative offset. 1018.28... Collection of Claims § 1018.28 Collection by administrative offset. (a) The Board may administratively undertake collection by offset on each claim which is liquidated or certain in amount in accordance with...

  4. 7 CFR 1.343 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Right to administrative offset. 1.343 Section 1.343... Administrative Hearings Under the Program Fraud Civil Remedies Act of 1986 § 1.343 Right to administrative offset... this part, may be collected by administrative offset under 31 U.S.C. 3716, except that...

  5. 40 CFR 13.21 - Employee salary offset-general.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Employee salary offset-general. 13.21... STANDARDS Administrative Offset § 13.21 Employee salary offset—general. (a) Purpose. This section... collection by salary offset under 5 U.S.C. 5514 of debts owed EPA and debts owed to other Federal agencies...

  6. 38 CFR 42.44 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... offset. 42.44 Section 42.44 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... offset. The amount of any penalty or assessment which has become final, or for which a judgment has been... under § 42.46 of this part, may be collected by administrative offset under 31 U.S.C. 3716, except...

  7. 22 CFR 35.44 - Right to administrative offset.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Right to administrative offset. 35.44 Section... § 35.44 Right to administrative offset. The amount of any penalty or assessment which has become final... compromise or settlement under § 35.46, may be collected by administrative offset under 31 U.S.C....

  8. 22 CFR 34.16 - Procedures for salary offset.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Procedures for salary offset. 34.16 Section 34.16 Foreign Relations DEPARTMENT OF STATE CLAIMS AND STOLEN PROPERTY DEBT COLLECTION Salary Offset § 34.16 Procedures for salary offset. Unless otherwise provided by statute or contract, the...

  9. 49 CFR 1018.96 - Stay of offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 8 2010-10-01 2010-10-01 false Stay of offset. 1018.96 Section 1018.96... OF TRANSPORTATION GENERAL RULES AND REGULATIONS DEBT COLLECTION Tax Refund Offset § 1018.96 Stay of offset. If the debtor timely notifies the Board that the debtor is exercising the right described...

  10. 29 CFR 22.44 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Right to administrative offset. 22.44 Section 22.44 Labor... offset. The amount of any penalty or assessment which has become final, or for which a judgment has been..., may be collected by administrative offset under 31 U.S.C. 3716, except that an administrative...

  11. 24 CFR 17.107 - Stay of offset.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Stay of offset. 17.107 Section 17... ADMINISTRATIVE CLAIMS Procedures for the Collection of Claims by the Government Administrative Offset Provisions § 17.107 Stay of offset. If the debtor timely notifies the Secretary that he or she is exercising...

  12. 24 CFR 26.56 - Right to administrative offset.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Right to administrative offset. 26....56 Right to administrative offset. The amount of any penalty or assessment that has become final... offset under 31 U.S.C. 3716 or other applicable law. In Program Fraud Civil Remedies Act matters,...

  13. 40 CFR 13.40 - Stay of offset.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Stay of offset. 13.40 Section 13.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL CLAIMS COLLECTION STANDARDS Referral of Debts to IRS for Tax Refund Offset § 13.40 Stay of offset. If the debtor timely notifies the EPA that...

  14. 15 CFR 25.44 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Right to administrative offset. 25.44... § 25.44 Right to administrative offset. The amount of any penalty or assessment which has become final... compromise or settlement under § 25.46, may be collected by administrative offset under 31 U.S.C....

  15. 24 CFR 17.151 - Notice requirements before offset.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Notice requirements before offset... Irs Tax Refund and Federal Payment Offset Provisions and Administrative Wage Garnishment § 17.151 Notice requirements before offset. A request for deduction from a Federal payment will be made only...

  16. 16 CFR 1027.8 - Procedures for salary offset.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Procedures for salary offset. 1027.8 Section 1027.8 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION GENERAL SALARY OFFSET § 1027.8 Procedures for salary offset. (a) Deductions to liquidate an employee's debt will be by the method and in...

  17. 45 CFR 79.44 - Right to administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Right to administrative offset. 79.44 Section 79... REMEDIES § 79.44 Right to administrative offset. The amount of any penalty or assessment which has become... compromise or settlement under § 79.46, may be collected by administrative offset under 31 U.S.C....

  18. 28 CFR 71.44 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Right to administrative offset. 71.44... Department of Justice § 71.44 Right to administrative offset. The amount of any penalty or assessment which... agreed upon in a compromise or settlement under § 71.46, may be collected by administrative offset...

  19. 12 CFR 308.543 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Right to administrative offset. 308.543 Section... administrative offset. The amount of any penalty or assessment which has become final, or for which a judgment... compromise or settlement under § 308.545 of this subpart, may be collected by administrative offset under...

  20. 40 CFR 27.44 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Right to administrative offset. 27.44... REMEDIES § 27.44 Right to administrative offset. The amount of any penalty or assessment which has become... compromise or settlement under § 27.46, may be collected by administrative offset under 31 U.S.C....

  1. 49 CFR 89.47 - Stay of offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Stay of offset. 89.47 Section 89.47 Transportation Office of the Secretary of Transportation IMPLEMENTATION OF THE FEDERAL CLAIMS COLLECTION ACT Referral of Debts to IRS for Tax Refund Offset § 89.47 Stay of offset. If the debtor timely notifies the...

  2. 24 CFR 17.156 - Stay of offset.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Stay of offset. 17.156 Section 17.156 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development... Payment Offset Provisions and Administrative Wage Garnishment § 17.156 Stay of offset. If the...

  3. 5 CFR 831.1306 - Collection by administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Collection by administrative offset. 831... REGULATIONS (CONTINUED) RETIREMENT Collection of Debts § 831.1306 Collection by administrative offset. (a) Offset from retirement payments. A debt may be collected in whole or in part from lump-sum...

  4. An Algorithm to Estimate Time Offset between Measurement Devices

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhou-song; LEI Zhen-ming

    2004-01-01

    This paper analyzes the necessity of the measurement of one-way delay, and it also points out the errors caused by the time offset between measurement devices. Then we propose an algorithm to estimate time offset between measurement devices in network. With the estimated time offset, we can correct our measuring results. Simulation shows the effectiveness of our algorithm.

  5. 49 CFR 1018.93 - Notice requirement before offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 8 2010-10-01 2010-10-01 false Notice requirement before offset. 1018.93 Section... BOARD, DEPARTMENT OF TRANSPORTATION GENERAL RULES AND REGULATIONS DEBT COLLECTION Tax Refund Offset § 1018.93 Notice requirement before offset. A request for reduction of an IRS tax refund will be...

  6. 17 CFR 143.4 - Collection by offset.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Collection by offset. 143.4... § 143.4 Collection by offset. (a) Whenever feasible, the Commission will collect claims under this part by means of administrative offset against obligations of the United States to the debtor. (b)...

  7. 49 CFR 31.44 - Right to administrative offset.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Right to administrative offset. 31.44 Section 31... Right to administrative offset. The amount of any penalty or assessment which has become final, or for... settlement under § 31.46, may be collected by administrative offset under 31 U.S.C. 3716, except that...

  8. 47 CFR 1.1951 - Offset against tax refunds.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Offset against tax refunds. 1.1951 Section 1... Claims Owed the United States Cooperation with the Internal Revenue Service § 1.1951 Offset against tax refunds. The Commission will take action to effect administrative offset against tax refunds due...

  9. Research on Stress Neutral Layer Offset in the Straightening Process

    Directory of Open Access Journals (Sweden)

    Hailian Gui

    2015-01-01

    Full Text Available The stress neutral layer offset is analyzed by theoretical and numerical calculation methods. In traditional straightening theory, the stress neutral layer was consistent with the geometric central layer. However, there is a phenomenon that the stress neutral layer has some offset with the geometric neutral layer. This offset is a very important factor for improving the precision of the straightening force. The formula of the stress neutral layer offset is obtained by a theoretical method and the change law is given by numerical calculation method. The neutral layer offset theory provides the theoretical basis for establishing the model of straightening force precisely.

  10. THE ODD OFFSET BETWEEN THE GALACTIC DISK AND ITS BAR IN NGC 3906

    Energy Technology Data Exchange (ETDEWEB)

    Swardt, Bonita de [South African Astronomical Observatory, Observatory, 7935 Cape Town (South Africa); Sheth, Kartik; Kim, Taehyun; Muñoz-Mateos, Juan-Carlos [National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Stephen Pardy; Elena D’ Onghia; Eric Wilcots [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Hinz, Joannah [MMTO, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Regan, Michael W. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Athanassoula, E.; Bosma, Albert [Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Buta, Ronald J. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Cisternas, Mauricio; Erroz-Ferrer, Santiago [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Comerón, Sébastien [Division of Astronomy, Department of Physical Sciences, University of Oulu, Oulu, FI-90014 (Finland); Gadotti, Dimitri A. [European Southern Observatory, Casilla 19001, Santiago 19 (Chile); Paz, Armando Gil de [Departamento de Astrofísica, Universidad Complutense de Madrid, Madrid E-28040 (Spain); Jarrett, Thomas H. [Astronomy Department, University of Cape Town, Rondebosch 7701 (South Africa); Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, Yorktown Hts., NY 10598 (United States); Ho, Luis C. [The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

    2015-07-20

    We use mid-infrared 3.6 and 4.5 μm imaging of NGC 3906 from the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G) to understand the nature of an unusual offset between its stellar bar and the photometric center of an otherwise regular, circular outer stellar disk. We measure an offset of ∼910 pc between the center of the stellar bar and photometric center of the stellar disk; the bar center coincides with the kinematic center of the disk determined from previous HI observations. Although the undisturbed shape of the disk suggests that NGC 3906 has not undergone a significant merger event in its recent history, the most plausible explanation for the observed offset is an interaction. Given the relatively isolated nature of NGC 3906 this interaction could be with dark matter substructure in the galaxy's halo or from a recent interaction with a fast moving neighbor that remains to be identified. Simulations aimed at reproducing the observed offset between the stellar bar/kinematic center of the system and the photometric center of the disk are necessary to confirm this hypothesis and constrain the interaction history of the galaxy.

  11. Carrier Frequency Offset Estimation and I/Q Imbalance Compensation for OFDM Systems

    Directory of Open Access Journals (Sweden)

    M. Omair Ahmad

    2007-01-01

    Full Text Available Two types of radio-frequency front-end imperfections, that is, carrier frequency offset and the inphase/quadrature (I/Q imbalance are considered for orthogonal frequency division multiplexing (OFDM communication systems. A preamble-assisted carrier frequency estimator is proposed along with an I/Q imbalance compensation scheme. The new frequency estimator reveals the relationship between the inphase and the quadrature components of the received preamble and extracts the frequency offset from the phase shift caused by the frequency offset and the cross-talk interference due to the I/Q imbalance. The proposed frequency estimation algorithm is fast, efficient, and robust to I/Q imbalance. An I/Q imbalance estimation/compensation algorithm is also presented by solving a least-square problem formulated using the same preamble as employed for the frequency offset estimation. The computational complexity of the I/Q estimation scheme is further reduced by using part of the short symbols with a little sacrifice in the estimation accuracy. Computer simulation and comparison with some of the existing algorithms are conducted, showing the effectiveness of the proposed method.

  12. Emissions trading with offset markets and free quota allocations

    Energy Technology Data Exchange (ETDEWEB)

    Rosendahl, Knut Einar; Strand, Jon

    2012-07-01

    We study interactions between a 'policy bloc's' emissions quota market and an offset market where emissions offsets can be purchased from a non-policy 'fringe' of countries (such as for the CDM under the Kyoto Protocol). Policy-bloc firms are assumed to benefit from free quota allocations that are updated according to either past emissions or past outputs. We show that both overall abatement, and the allocation of given abatement between the policy bloc and the fringe, tend to be inefficient. When the policy-bloc quota market and offset markets are fully integrated (and firms buy offsets directly from the fringe), and all quotas and offsets must be traded at a single price, it is optimal for the policy bloc to either not constrain the offset market whatsoever, or to ban offsets completely. The former (latter) case occurs when free allocation of quotas is not too generous (very generous), and the offset market can profitably deliver large (only a small) quota amounts. Governments of policy countries would however instead prefer to buy offsets directly from the fringe at a price below the policy-bloc quota price. The offset price will then be below the marginal damage cost of emissions, and the quota price in the policy bloc above marginal damage cost. This solution is also inefficient as the policy bloc (acting as a monopsonist) purchases too few offsets from the fringe.(Author)

  13. Fast visual part inspection for bin picking

    DEFF Research Database (Denmark)

    Rofalis, Nikolaos; Olesen, Anders Sig; Jakobsen, Michael Linde

    2016-01-01

    In this paper we present a novel 3D sensing approach for industrial bin-picking applications that is low-cost, fast and precise. The system uses a simple laser-line emitter. While a robot arm moves the object through the laser light, a synchronized camera captures the laser line image on the object...

  14. Carrier frequency offset estimation for OFDM systems with time-varying DC Offset

    Science.gov (United States)

    Liu, Tao; Li, Hanzhang

    2012-12-01

    Orthogonal frequency division multiplexing (OFDM) systems with direct-conversion architecture suffer from both carrier frequency offset (CFO) and dc offset (DCO). In this paper, we study CFO estimation problem for OFDM systems with time-varying DCO (TV-DCO) caused by gain mode switch of low noise amplifier (LNA). Based on linear approximation of TV-DCO, a blind algorithm is proposed for CFO estimation by means of DCO compensation and power leakage minimization. Performance of the proposed algorithm is demonstrated by simulations.

  15. TOF PET offset calibration from clinical data

    Science.gov (United States)

    Werner, M. E.; Karp, J. S.

    2013-06-01

    In this paper, we present a timing calibration technique for time-of-flight positron emission tomography (TOF PET) that eliminates the need for a specialized data acquisition. By eliminating the acquisition, the process becomes fully automated, and can be performed with any clinical data set and whenever computing resources are available. It also can be applied retroactively to datasets for which a TOF offset calibration is missing or suboptimal. Since the method can use an arbitrary data set to perform a calibration prior to a TOF reconstruction, possibly of the same data set, one also can view this as reconstruction from uncalibrated data. We present a performance comparison with existing calibration techniques.

  16. THE PHASE-OFFSET OVERLAPPED WAVE TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Liang Dequn; Liang Weihua; Sun Changnian

    2003-01-01

    A new digital communication technology based on the Phase-Offset Overlapped Waves (POOW) has been introduced in this letter. The waves can be considered as a special multicarrier different from traditional ones. The sub-waves in a coded word's period of the POOW are sine waves and have the same frequencies, but different starting phases. The most important characteristic is that these sub-waves are the piecewise functions and not orthogonal in a code word period. The decoding can be implemented by solving a linear equation group.This code has very high efficiency and thus the data transmission rate is increased greatly.

  17. Offsets, one tool in the toolbox

    CSIR Research Space (South Africa)

    Garland, Rebecca M

    2014-01-01

    Full Text Available emissions inventory as we can  but this is largest stumbling block to provide policy support • How can a regulator be certain of the impact of an offset without being able to accurately model it? N a id o o, 2 0 1 2 7 What modelling... ambient air quality – Comprehensive, transparent, agreed upon modelling platform – Active regulator who decides on the interventions and policies in their airshed and has capacity required to decide on the needed suite of interventions, regulations...

  18. Reagan Defense Forum: The Third Offset Strategy

    Science.gov (United States)

    2015-11-07

    I’ve been a lifelong history of military strategy. And I’ve learned one of the most dangerous places a reporter can stand in the conflict zone is...it stick, regardless of who is the next occupant of the outer ring of the third deck at the Pentagon? SEC. WORK: Well, we won’t be able to go as...this offset, the young officers who have grown up in this "iCombat" world, they’re going to have ideas that our senior officers simply will not be

  19. Calculation for the fast axis beam quality of the laser diode stack%半导体激光器堆栈快轴光束质量计算的研究

    Institute of Scientific and Technical Information of China (English)

    李峙; 尧舜; 高祥宇; 潘飞; 贾冠男; 王智勇

    2015-01-01

    Based on the Gaussian beam propagation theory, and combined with the structure of the laser diode stack, the fast axis beam model of the laser diode stacks was established. And considered with the divergence angle and directional factor of each diode laser array, the calculation for the fast axis beam quality of the diode laser stacks was amended which was finally verified by the experiment. The result shows that compared with the experimental measurements, the calculation error of this model is only 2.14%. Compared with the ones before amending, which are 24.16% and 18.36%, the new calculation method is improved a lot in accuracy and can reflect the fast axis beam quality of diode laser stacks more exactitudly.%以高斯光束传输理论为基础,结合半导体激光器堆栈结构,建立了半导体激光器堆栈快轴方向光束传输理论模型,并引入单个半导体激光器阵列的发散角和指向性因子,对半导体激光器堆栈快轴方向光束质量计算方法进行了修正,最后通过实验对计算结果进行验证。结果显示,相对于实验测量值,该理论模型计算值的误差仅为2.14%,与修正前的计算误差24.16%和18.36%相比,在精度上有了很大程度的提高,因此,该方法可行,能更精确的反应堆栈快轴的光束质量。

  20. Rarefaction after fast laser heating of thin metal film on a glass mount: spallation and inflation from one-dimensional to three-dimensional ablation flow

    Science.gov (United States)

    Inogamov, Nail; Khokhlov, Viktor; Petrov, Yury; Zhakhovsky, Vasily; Migdal, Kirill; Ilnitsky, Denis; Hasegawa, Noboru; Nishikino, Masaharu; Yamagiwa, Mitsuru; Ishino, Masahiko; Kawachi, Tetsuya; Faenov, Anatoly; Pikuz, Tatiana; Takayoshi, Shintaro; Eyama, Takashi; Kakimoto, Naoya; Tomita, Takuro; Baba, Motoyoshi; Minami, Yasuo; Suemoto, Tohru

    2015-06-01

    We numerically and experimentally consider the effect of subpicosecond Ti:sapp laser pump pulse onto 60-100 nm silver and gold films mounted onto a silica substrate. Pump pulse spalls out the film from the substrate. Influence of diameter of a laser irradiated spot 1-100 microns on a film surface is studied. A cupola like spallation shell is flying from the substrate. For the large spot the soft X-ray probe laser is used for measuring the ablation process. The research (NAI, VVZh, VAKh, DKI, YVP, KPM, AYF, TAP) has been performed under financial support from Russian Science Foundation (RSCF) (Project No. 14-19-01599).

  1. Development by Design in Western Australia: Overcoming Offset Obstacles

    Directory of Open Access Journals (Sweden)

    James Fitzsimons

    2014-02-01

    Full Text Available Biodiversity offsets can be an important tool for maintaining or enhancing environmental values in situations where development is sought despite negative environmental impacts. There are now approximately 45 compensatory mitigation programs for biodiversity impacts worldwide, with another 27 programs in development. While offsets have great potential as a conservation tool, their establishment requires overcoming a number of conceptual and methodological hurdles. In Australia, new policy changes at the national and state (i.e., Western Australia level require that offsets follow a set of general principles: (1 Environmental offsets may not be appropriate for all projects and will only be considered after avoidance and mitigation options have been pursued; (2 Environmental offsets will be based on sound environmental information and knowledge; (3 Establishing goals for offsets requires an estimate of expected direct and indirect impacts; (4 Environmental offsets will be focused on longer term strategic outcomes; (5 Environmental offsets will be cost-effective, as well as relevant and proportionate to the significance of the environmental value being impacted. Here we focus on the challenges of determining and implementing offsets using a real world example from a voluntary offset process undertaken for Barrick Gold’s Kanowna Belle mine site in Western Australia to highlight those challenges and potential solutions.

  2. Biodiversity offsets and the challenge of achieving no net loss.

    Science.gov (United States)

    Gardner, Toby A; VON Hase, Amrei; Brownlie, Susie; Ekstrom, Jonathan M M; Pilgrim, John D; Savy, Conrad E; Stephens, R T Theo; Treweek, Jo; Ussher, Graham T; Ward, Gerri; Ten Kate, Kerry

    2013-12-01

    Businesses, governments, and financial institutions are increasingly adopting a policy of no net loss of biodiversity for development activities. The goal of no net loss is intended to help relieve tension between conservation and development by enabling economic gains to be achieved without concomitant biodiversity losses. biodiversity offsets represent a necessary component of a much broader mitigation strategy for achieving no net loss following prior application of avoidance, minimization, and remediation measures. However, doubts have been raised about the appropriate use of biodiversity offsets. We examined what no net loss means as a desirable conservation outcome and reviewed the conditions that determine whether, and under what circumstances, biodiversity offsets can help achieve such a goal. We propose a conceptual framework to substitute the often ad hoc approaches evident in many biodiversity offset initiatives. The relevance of biodiversity offsets to no net loss rests on 2 fundamental premises. First, offsets are rarely adequate for achieving no net loss of biodiversity alone. Second, some development effects may be too difficult or risky, or even impossible, to offset. To help to deliver no net loss through biodiversity offsets, biodiversity gains must be comparable to losses, be in addition to conservation gains that may have occurred in absence of the offset, and be lasting and protected from risk of failure. Adherence to these conditions requires consideration of the wider landscape context of development and offset activities, timing of offset delivery, measurement of biodiversity, accounting procedures and rule sets used to calculate biodiversity losses and gains and guide offset design, and approaches to managing risk. Adoption of this framework will strengthen the potential for offsets to provide an ecologically defensible mechanism that can help reconcile conservation and development. Balances de Biodiversidad y el Reto de No Obtener P

  3. How economic contexts shape calculations of yield in biodiversity offsetting.

    Science.gov (United States)

    Carver, L; Sullivan, S

    2017-10-01

    We examined and analyzed methods used to create numerical equivalence between sites affected by development and proposed conservation offset sites. Application of biodiversity offsetting metrics in development impact and mitigation assessments is thought to standardize biodiversity conservation outcomes, sometimes termed yield by those conducting these calculations. The youth of biodiversity offsetting in application, however, means little is known about how biodiversity valuations and offset contracts between development and offset sites are agreed on in practice or about long-term conservation outcomes. We examined how sites were made commensurable and how biodiversity gains or yields were calculated and negotiated for a specific offset contract in a government-led pilot study of biodiversity offsets in England. Over 24 months, we conducted participant observations of various stages in the negotiation of offset contracts through repeated visits to 3 (anonymized) biodiversity offset contract sites. We conducted 50 semistructured interviews of stakeholders in regional and local government, the private sector, and civil society. We used a qualitative data analysis software program (DEDOOSE) to textually analyze interview transcriptions. We also compared successive iterations of biodiversity-offsetting calculation spreadsheets and planning documents. A particular focus was the different iterations of a specific biodiversity impact assessment in which the biodiversity offsetting metric developed by the U.K.'s Department for Environment, Food and Rural Affairs was used. We highlight 3 main findings. First, biodiversity offsetting metrics were amended in creative ways as users adapted inputs to metric calculations to balance and negotiate conflicting requirements. Second, the practice of making different habitats equivalent to each other through the application of biodiversity offsetting metrics resulted in commensuration outcomes that may not provide projected

  4. OFFSET - RAY TRACING OPTICAL ANALYSIS OF OFFSET SOLAR COLLECTOR FOR SPACE STATION SOLAR DYNAMIC POWER SYSTEM

    Science.gov (United States)

    Jefferies, K.

    1994-01-01

    OFFSET is a ray tracing computer code for optical analysis of a solar collector. The code models the flux distributions within the receiver cavity produced by reflections from the solar collector. It was developed to model the offset solar collector of the solar dynamic electric power system being developed for Space Station Freedom. OFFSET has been used to improve the understanding of the collector-receiver interface and to guide the efforts of NASA contractors also researching the optical components of the power system. The collector for Space Station Freedom consists of 19 hexagonal panels each containing 24 triangular, reflective facets. Current research is geared toward optimizing flux distribution inside the receiver via changes in collector design and receiver orientation. OFFSET offers many options for experimenting with the design of the system. The offset parabolic collector model configuration is determined by an input file of facet corner coordinates. The user may choose other configurations by changing this file, but to simulate collectors that have other than 19 groups of 24 triangular facets would require modification of the FORTRAN code. Each of the roughly 500 facets in the assembled collector may be independently aimed to smooth out, or tailor, the flux distribution on the receiver's wall. OFFSET simulates the effects of design changes such as in receiver aperture location, tilt angle, and collector facet contour. Unique features of OFFSET include: 1) equations developed to pseudo-randomly select ray originating sources on the Sun which appear evenly distributed and include solar limb darkening; 2) Cone-optics technique used to add surface specular error to the ray originating sources to determine the apparent ray sources of the reflected sun; 3) choice of facet reflective surface contour -- spherical, ideal parabolic, or toroidal; 4) Gaussian distributions of radial and tangential components of surface slope error added to the surface normals at

  5. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter; Etude experimentale de la propagation et du depot d'energie d'electrons rapides dans une cible solide ou comprimee par choc laser: application a l'allumeur rapide

    Energy Technology Data Exchange (ETDEWEB)

    Pisani, F

    2000-02-15

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  6. Net present biodiversity value and the design of biodiversity offsets.

    Science.gov (United States)

    Overton, Jacob McC; Stephens, R T Theo; Ferrier, Simon

    2013-02-01

    There is an urgent need to develop sound theory and practice for biodiversity offsets to provide a better basis for offset multipliers, to improve accounting for time delays in offset repayments, and to develop a common framework for evaluating in-kind and out-of-kind offsets. Here, we apply concepts and measures from systematic conservation planning and financial accounting to provide a basis for determining equity across type (of biodiversity), space, and time. We introduce net present biodiversity value (NPBV) as a theoretical and practical measure for defining the offset required to achieve no-net-loss. For evaluating equity in type and space we use measures of biodiversity value from systematic conservation planning. Time discount rates are used to address risk of non-repayment, and loss of utility. We illustrate these concepts and measures with two examples of biodiversity impact-offset transactions. Considerable further work is required to understand the characteristics of these approaches.

  7. Orthogonal Frequency Division Multiplexing System with Frequency Offset Estimation

    Directory of Open Access Journals (Sweden)

    Meghashree D.Nimje

    2013-03-01

    Full Text Available Orthogonal Frequency Division Multiplexing (OFDM system, use a large number of parallel narrowband subcarriers instead of a single wide-band carrier to transport information. Orthogonal frequency division multiplexing is the modulation technique use in digital communication systems . Carrier frequency offset occurs due to Doppler effect or noise. Carrier frequency offsets (CFOs is the Offset between the transmitter and the receiver oscillators .CFO damages the orthogonality of the carries ,resulting in degradation of the systems performance. Carrier frequency offset estimation method is discussed in this paper. In this paper one complex training sequence use, which can effectively estimate carrier frequency offset in the time domain and frequency domain. Here fine and coarse frequency is estimated to improve the improve the system performance. This paper shows the estimation range for frequency offset can be improve to large extent..

  8. Formulation and Characterization of CuIn1-xGaxSe2 Ink for Gravure Offset Printing

    Science.gov (United States)

    Kim, Inyoung; Han, Hyun-Suk; Kwak, Sun-Woo; Yu, Jong-Su; Kim, Bongmin; Jang, Yunseok; Lee, Taik-Min

    2013-05-01

    CuIn1-xGaxSe2 (CIGS) paste for gravure offset printing was formulated by changing the amount of additives to determine the critical factor for gravure offset printing quality. With the addition of poly(vinyl pyrrolidone) (PVP), the viscosity and yield stress of CIGS ink decreased and shear thinning behavior disappeared. However, PVP effectively enhanced ink cohesion and elastic modulus, which critically affected the printability of the CIGS paste. Intense pulsed light (IPL) treatment in air made the microstructure of CIGS film denser without a phase change or oxidation. The gravure offset printing technique and IPL treatment were considered a good combination for a continuous and fast CIGS film growth process.

  9. Rational offset approximation of rational Bézier curves

    Institute of Scientific and Technical Information of China (English)

    CHENG Min; WANG Guo-jin

    2006-01-01

    The problem of parametric speed approximation of a rational curve is raised in this paper. Offset curves are widely used in various applications. As for the reason that in most cases the offset curves do not preserve the same polynomial or rational polynomial representations, it arouses difficulty in applications. Thus approximation methods have been introduced to solve this problem. In this paper, it has been pointed out that the crux of offset curve approximation lies in the approximation of parametric speed. Based on the Jacobi polynomial approximation theory with endpoints interpolation, an algebraic rational approximation algorithm of offset curve, which preserves the direction of normal, is presented.

  10. A large-strain, fast-response, and easy-to-manufacture electrothermal actuator based on laser-reduced graphene oxide

    Science.gov (United States)

    Zhang, Tian-Yu; Wang, Qian; Deng, Ning-Qin; Zhao, Hai-Ming; Wang, Dan-Yang; Yang, Zhen; Liu, Ying; Yang, Yi; Ren, Tian-Ling

    2017-09-01

    In this paper, we have developed a high-performance graphene electrothermal actuator (ETA). The fabrication method is easy, fast, environmentally friendly, and suitable for preparing both large-size and miniature graphene ETAs. When applied with the driving voltage of 65 V, the graphene ETA achieves a large bending angle of 270° with a fast response of 8 s and the recovery process costs 19 s. The large bending deformation is reversible and can be precisely controlled by the driving voltage. A simple robotic hand prepared by using a single graphene ETA can hold the object, which is more than ten times the weight of itself. By virtue of its large-strain, fast response, and easy-to-manufacture, we believe that the graphene ETA has tremendous potential in extensive applications involving biomimetic robotics, artificial muscles, switches, and microsensors in both macroscopic and microscopic fields.

  11. Blind estimation of carrier frequency offset, I/Q imbalance and DC offset for OFDM systems

    Science.gov (United States)

    Liu, Tao; Li, Hanzhang

    2012-12-01

    Sensitivity to carrier frequency offset (CFO) is one of the biggest drawbacks of orthogonal frequency division multiplexing (OFDM) system. A lot of CFO estimation algorithms had been studied for compensation of CFO in OFDM system. However, with the adoption of direct-conversion architecture (DCA), which introduces additional impairments such as dc offset (DCO) and in-phase/quadrature (I/Q) imbalance in OFDM system, the established CFO estimation algorithms suffer from performance degradation. In our previous study, we developed a blind CFO, I/Q imbalance and DCO estimation algorithm for OFDM systems with DCA. In this article, we propose an alternative algorithm with reduced computation complexity and better accuracy. Performance of the proposed algorithm is demonstrated by simulations.

  12. On the Estimation of Carrier Frequency Offset and DC Offset for OFDM Systems

    Science.gov (United States)

    Lin, Hai; Nakao, Takeshi; Lu, Weiming; Yamashita, Katsumi

    In an orthogonal frequency division multiplexing (OFDM) receiver with direct-conversion architecture, carrier frequency offset (CFO) and direct-current offset (DCO), which cause severe performance degradation, need to be estimated and compensated. Recently, by investigating the subspace of OFDM signal after coarse DCO cancellation using timedomain average, we have proposed a nullspace-based estimator (NSE), for blind CFO and DCO estimation. In this paper, based on an analysis of the cost function of the NSE, we propose a common nullspace based estimator (CNSE). It is shown that by matching the frequency occupation of the received OFDM signal with CFO and DCO, the CNSE can achieve the full performance potential of the NSE. Also, the performance analysis reveals that the CNSE can asymptotically approach the Cramer-Rao bound (CRB) of OFDM CFO estimation in the presence of DCO. Finally the analysis results are confirmed by simulations.

  13. Investigation of double-mode operation and fast fine tuning properties of a grating-coupled external cavity diode laser configuration

    Science.gov (United States)

    Bayrakli, Ismail

    2017-01-01

    Double-mode operation and fast piezo fine tuning properties of a gain chip on a thermoelectric cooler in an external cavity are investigated. A widely course double-mode tuning range of 120 nm for the spectral range between 1470 and 1590 nm is achieved by rotating the diffraction gratings forming a double Littrow-type configuration. A fast piezo fine tuning range over 7cm-1 (1.5 nm, 210 GHz) in a single-mode operation is obtained by scanning the external cavity length with scan rates up to 0.5 kHz.

  14. Damping Transversal Vibrations of the Offset Cylinder of the Offset Press

    Directory of Open Access Journals (Sweden)

    Eglė Šalvienė

    2012-01-01

    Full Text Available Investigation into the influence of a dynamic vibration damper on the intensity of the absolute forced transversal vibrations of the blanket cylinder of the web printing offset press was performed. The analytical and numerical examination of the dynamic model of the cylinder was done. The obtained results have disclosed that the application of the damper decreases the intensity of printing cylinder vibrations.Article in Lithuanian

  15. Attention-dependent sound offset-related brain potentials.

    Science.gov (United States)

    Horváth, János

    2016-05-01

    When performing sensory tasks, knowing the potentially occurring goal-relevant and irrelevant stimulus events allows the establishment of selective attention sets, which result in enhanced sensory processing of goal-relevant events. In the auditory modality, such enhancements are reflected in the increased amplitude of the N1 ERP elicited by the onsets of task-relevant sounds. It has been recently suggested that ERPs to task-relevant sound offsets are similarly enhanced in a tone-focused state in comparison to a distracted one. The goal of the present study was to explore the influence of attention on ERPs elicited by sound offsets. ERPs elicited by tones in a duration-discrimination task were compared to ERPs elicited by the same tones in not-tone-focused attentional setting. Tone offsets elicited a consistent, attention-dependent biphasic (positive-negative--P1-N1) ERP waveform for tone durations ranging from 150 to 450 ms. The evidence, however, did not support the notion that the offset-related ERPs reflected an offset-specific attention set: The offset-related ERPs elicited in a duration-discrimination condition (in which offsets were task relevant) did not significantly differ from those elicited in a pitch-discrimination condition (in which the offsets were task irrelevant). Although an N2 reflecting the processing of offsets in task-related terms contributed to the observed waveform, this contribution was separable from the offset-related P1 and N1. The results demonstrate that when tones are attended, offset-related ERPs may substantially overlap endogenous ERP activity in the postoffset interval irrespective of tone duration, and attention differences may cause ERP differences in such postoffset intervals.

  16. Economic and ecological outcomes of flexible biodiversity offset systems.

    Science.gov (United States)

    Habib, Thomas J; Farr, Daniel R; Schneider, Richard R; Boutin, Stan

    2013-12-01

    The commonly expressed goal of biodiversity offsets is to achieve no net loss of specific biological features affected by development. However, strict equivalency requirements may complicate trading of offset credits, increase costs due to restricted offset placement options, and force offset activities to focus on features that may not represent regional conservation priorities. Using the oil sands industry of Alberta, Canada, as a case study, we evaluated the economic and ecological performance of alternative offset systems targeting either ecologically equivalent areas (vegetation types) or regional conservation priorities (caribou and the Dry Mixedwood natural subregion). Exchanging dissimilar biodiversity elements requires assessment via a generalized metric; we used an empirically derived index of biodiversity intactness to link offsets with losses incurred by development. We considered 2 offset activities: land protection, with costs estimated as the net present value of profits of petroleum and timber resources to be paid as compensation to resource tenure holders, and restoration of anthropogenic footprint, with costs estimated from existing restoration projects. We used the spatial optimization tool MARXAN to develop hypothetical offset networks that met either the equivalent-vegetation or conservation-priority targets. Networks that required offsetting equivalent vegetation cost 2-17 times more than priority-focused networks. This finding calls into question the prudence of equivalency-based systems, particularly in relatively undeveloped jurisdictions, where conservation focuses on limiting and directing future losses. Priority-focused offsets may offer benefits to industry and environmental stakeholders by allowing for lower-cost conservation of valued ecological features and may invite discussion on what land-use trade-offs are acceptable when trading biodiversity via offsets. Resultados Económicos y Ecológicos de Sistemas de Compensación de

  17. Supercontinuum generation and carrier envelope offset frequency measurement in a tapered single-mode fiber

    CERN Document Server

    Zhang, Long; Zhao, Yanying; Hou, Lei; Yu, Zijiao; Wei, Zhiyi

    2014-01-01

    We report supercontinuum generation by launching femtosecond Yb fiber laser pulses into a tapered single-mode fiber of 3 um core diameter. A spectrum of more than one octave, from 550 to 1400 nm, has been obtained with an output power of 1.3 W at a repetition rate of 250 MHz, corresponding to a coupling efficiency of up to 60%. By using a typical f-2f interferometer, the carrier envelope offset frequency was measured and found to have a signal-to-noise ratio of nearly 30 dB.

  18. 3D printed 20/30-GHz dual-band offset stepped-reflector antenna

    DEFF Research Database (Denmark)

    Menendez, Laura G.; Kim, Oleksiy S.; Persson, Frank

    2015-01-01

    with a peak directivity of 36.7 dB and 40.4 dB at 20 and 30 GHz, respectively; this corresponds to an aperture efficiency of 61 % and 64 %, respectively. These results demonstrate that 3D printing is a viable manufacturing technology for medium-sized high-frequency antennas.......This paper documents the manufacturing by selective laser sintering of a 20/30 GHz dual-band circularly polarized offset stepped-reflector antenna for K- and Ka-band satellite communication. The manufactured antenna has been measured at the DTU-ESA Spherical Near-Field Antenna Test Facility...

  19. Magneto-optical polarization rotation in a ladder-type atomic system for tunable offset locking

    CERN Document Server

    Parniak, Michał; Wasilewski, Wojciech

    2016-01-01

    We demonstrate an easily tunable locking scheme for stabilizing frequency-sum of two lasers on a two-photon ladder transition based on polarization rotation in warm rubidium vapors induced by magnetic field and circularly polarized driving field. In principle unlimited tunability of the two-photon offset frequency is due to strong splitting and shifting of magnetic states in external field. We achieve two-photon detuning of 120 MHz with the single-photon detuning of up to 20 GHz, as well as strong rotation signal.

  20. IMPROVEMENT OF WEAR-RESISTANCE AND SERVICE LIFE OF MULTI-DISK BRAKE MECHANISMS OF «BELARUS» TRACTOR BY LASER THERMAL HARDENING OF FAST WEARING PARTS

    Directory of Open Access Journals (Sweden)

    O. S. Kobjakov

    2008-01-01

    Full Text Available Problems concerning wear resistance improvement of «Belarus» tractor brake mechanism parts are considered in the paper. Properties of ВЧ-50-pig iron are investigated as a result of laser thermal hardening by various technological methods.

  1. A new fiber-optic non-contact compact laser-ultrasound scanner for fast non-destructive testing and evaluation of aircraft composites.

    Science.gov (United States)

    Pelivanov, Ivan; Buma, Takashi; Xia, Jinjun; Wei, Chen-Wei; O'Donnell, Matthew

    2014-03-21

    Laser ultrasonic (LU) inspection represents an attractive, non-contact method to evaluate composite materials. Current non-contact systems, however, have relatively low sensitivity compared to contact piezoelectric detection. They are also difficult to adjust, very expensive, and strongly influenced by environmental noise. Here, we demonstrate that most of these drawbacks can be eliminated by combining a new generation of compact, inexpensive fiber lasers with new developments in fiber telecommunication optics and an optimally designed balanced probe scheme. In particular, a new type of a balanced fiber-optic Sagnac interferometer is presented as part of an all-optical LU pump-probe system for non-destructive testing and evaluation of aircraft composites. The performance of the LU system is demonstrated on a composite sample with known defects. Wide-band ultrasound probe signals are generated directly at the sample surface with a pulsed fiber laser delivering nanosecond laser pulses at a repetition rate up to 76 kHz rate with a pulse energy of 0.6 mJ. A balanced fiber-optic Sagnac interferometer is employed to detect pressure signals at the same point on the composite surface. A- and B-scans obtained with the Sagnac interferometer are compared to those made with a contact wide-band polyvinylidene fluoride transducer.

  2. Short-term regulation of the hypothalamic melanocortinergic system under fasting and defined glucose-refeeding conditions in rats: a laser capture microdissection (LMD)-based study.

    Science.gov (United States)

    Landmann, Emelie M; Schellong, Karen; Melchior, Kerstin; Rodekamp, Elke; Ziska, Thomas; Harder, Thomas; Plagemann, Andreas

    2012-04-25

    It is well established that under fasting conditions the expression of the orexigenic neuropeptide agouti-related peptide (AGRP) is up-regulated in the hypothalamic arcuate nucleus (ARC), while inconsistent data exist regarding fasting regulation of the anorexigenic neurohormone proopiomelanocortin (POMC). Inconsistencies might have methodological reasons, especially concerning neuromorphological and/or experimental (nutritional) specificity. We analyzed the expression of both neuropeptides in ARC neurons, using lasercapture microdissection (LMD) and real-time PCR in 12h fasted vs. fed Wistar rats as well as after a standardized glucose load, i.e., under clinically relevant conditions in terms of diagnosing glucose intolerance in the human. Under fasting conditions, clear up-regulation of AGRP was observed, with increasing magnitude in ARC single neurons (SNP) as compared to ARC cell layers (+125% vs. +23%, resp.), closely correlated to hypoinsulinemia and hypoleptinemia. Surprisingly, in the fasting state POMC was not found to be down-regulated, neither in ARC cell layers nor in ARC single neurons (+9% vs. +6%). However, glucose-refeeding under diagnostically relevant conditions led to strong neuronal up-regulation of POMC expression in ARC SNP (+128%), and AGRP down-regulation (-50%). In conclusion, experimentally, topographically, and analytically specific and standardized conditions confirmed AGRP in ARC neurons as being neuronally up- and down-regulated, resp., depending on the general nutritional state, while POMC was found to be (up-) regulated only after peripheral glucose load. Findings suggest that POMC in ARC neurons acts glucose-mediated as an "anti-orexigenic" neurohormone, specifically responding to hyperglycemia.

  3. 34 CFR 33.44 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Right to administrative offset. 33.44 Section 33.44 Education Office of the Secretary, Department of Education PROGRAM FRAUD CIVIL REMEDIES ACT § 33.44 Right to administrative offset. The amount of any penalty or assessment that has become final, or for which a judgment...

  4. 10 CFR 1013.44 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Right to administrative offset. 1013.44 Section 1013.44... Right to administrative offset. The amount of any penalty or assessment which has become final, or for... in a compromise or settlement under § 1013.46 of this part, may be collected by administrative...

  5. 5 CFR 1215.8 - Procedures for salary offset.

    Science.gov (United States)

    2010-01-01

    ... payment due to a separated employee including but not limited to final salary payment or leave in... Section 1215.8 Administrative Personnel MERIT SYSTEMS PROTECTION BOARD ORGANIZATION AND PROCEDURES DEBT MANAGEMENT Salary Offset § 1215.8 Procedures for salary offset. (a) Deductions to liquidate an...

  6. 5 CFR 837.702 - Offset from supplemental survivor annuity.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Offset from supplemental survivor annuity... survivor annuity. (a) OPM will reduce a supplemental survivor annuity (an annuity under 5 U.S.C. 8341) based on the service of an individual who performed CSRS-Offset service, if the survivor annuitant...

  7. 31 CFR 901.3 - Collection by administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Collection by administrative offset... ADMINISTRATIVE COLLECTION OF CLAIMS § 901.3 Collection by administrative offset. (a) Scope. (1) The term “administrative offset” has the meaning provided in 31 U.S.C. 3701(a)(1). (2) This section does not apply to:...

  8. PILOT-BASED FREQUENCY OFFSET DETECTION SCHEME IN OFDM SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Du Zheng; Zhu Jinkang

    2003-01-01

    The frequency offset information is extracted from local pilot amplitude characteristics, which suffer much less distortion in frequency-selective fading channels than those utilizing frequency domain correlation techniques. Simulation shows that the performance of this scheme has better performance than the existing frequency domain pilot-based frequency offset detection scheme.

  9. Onset and Offset as Determinants of the Simon Effect

    Science.gov (United States)

    Riggio, Lucia; Gherri, Elena; Lupianez, Juan

    2012-01-01

    We investigated the presence and the characteristics of the Simon effect for onset and offset targets when these stimuli are randomly intermixed. In Experiment 1, two possible target locations were occupied by an occluder. On onset trials, a target appeared above an occluder, while on offset trials one of the occluders disappeared, revealing the…

  10. 22 CFR 213.21 - Employee salary offset-general.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Employee salary offset-general. 213.21 Section 213.21 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT CLAIMS COLLECTION Administrative Offset § 213.21 Employee salary offset—general. (a) Purpose. This section establishes USAID's policies...

  11. 41 CFR 105-55.011 - Collection by administrative offset.

    Science.gov (United States)

    2010-07-01

    ... administrative offset. 105-55.011 Section 105-55.011 Public Contracts and Property Management Federal Property... Administration 55-COLLECTION OF CLAIMS OWED THE UNITED STATES § 105-55.011 Collection by administrative offset. (a) Scope. (1) The term “administrative offset” has the meaning provided in 31 U.S.C. 3701(a)(1)....

  12. 21 CFR 176.130 - Anti-offset substances.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Anti-offset substances. 176.130 Section 176.130... for Use Only as Components of Paper and Paperboard § 176.130 Anti-offset substances. Substances named... in printing and decorating paper and paperboard used for food packaging in accordance with...

  13. 5 CFR 185.144 - Right to administrative offset.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Right to administrative offset. 185.144 Section 185.144 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PROGRAM FRAUD CIVIL REMEDIES § 185.144 Right to administrative offset. The amount of any penalty or...

  14. Using hob offset to balance dynamic strength in spur gears

    Science.gov (United States)

    Liou, Chuen-Huei; Lin, Hsi Hsiang; Oswald, Fred B.; Townsend, Dennis P.

    1995-05-01

    This paper presents an analytical study on the effect of hob offset on the dynamic tooth strength of spur gears. The study was limited to equal and opposite offset values applied to the pinion and gear to maintain the standard operating center distance. The analysis presented in this paper was performed using a new version of the NASA gear dynamics code DANST. The operating speed of the transmission has a significant influence on the amount of hob offset required to equalize the dynamic stresses in the pinion and gear. In the transmission studied, at low speeds, the optimum hob offset value was found to fluctuate. At higher speeds, the optimum value was constrained by the minimum allowed thickness at the tip of the pinion tooth. For gears that must operate over a range of speeds, an average offset value may be used. Spur gears designed with the procedure presented here can have significant improvements in load capacity.

  15. Measuring coseismic displacements with point-like targets offset tracking

    KAUST Repository

    Hu, Xie

    2014-01-01

    Offset tracking is an important complement to measure large ground displacements in both azimuth and range dimensions where synthetic aperture radar (SAR) interferometry is unfeasible. Subpixel offsets can be obtained by searching for the cross-correlation peak calculated from the match patches uniformly distributed on two SAR images. However, it has its limitations, including redundant computation and incorrect estimations on decorrelated patches. In this letter, we propose a simple strategy that performs offset tracking on detected point-like targets (PT). We first detect image patches within bright PT by using a sinc-like template from a single SAR image and then perform offset tracking on them to obtain the pixel shifts. Compared with the standard method, the application on the 2010 M 7.2 El Mayor-Cucapah earthquake shows that the proposed PT offset tracking can significantly increase the cross-correlation and thus result in both efficiency and reliability improvements. © 2013 IEEE.

  16. Stereoscopic Offset Makes Objects Easier to Recognize.

    Science.gov (United States)

    Caziot, Baptiste; Backus, Benjamin T

    2015-01-01

    Binocular vision is obviously useful for depth perception, but it might also enhance other components of visual processing, such as image segmentation. We used naturalistic images to determine whether giving an object a stereoscopic offset of 15-120 arcmin of crossed disparity relative to its background would make the object easier to recognize in briefly presented (33-133 ms), temporally masked displays. Disparity had a beneficial effect across a wide range of disparities and display durations. Most of this benefit occurred whether or not the stereoscopic contour agreed with the object's luminance contour. We attribute this benefit to an orienting of spatial attention that selected the object and its local background for enhanced 2D pattern processing. At longer display durations, contour agreement provided an additional benefit, and a separate experiment using random-dot stimuli confirmed that stereoscopic contours plausibly contributed to recognition at the longer display durations in our experiment. We conclude that in real-world situations binocular vision confers an advantage not only for depth perception, but also for recognizing objects from their luminance patterns and bounding contours.

  17. Stereoscopic Offset Makes Objects Easier to Recognize.

    Directory of Open Access Journals (Sweden)

    Baptiste Caziot

    Full Text Available Binocular vision is obviously useful for depth perception, but it might also enhance other components of visual processing, such as image segmentation. We used naturalistic images to determine whether giving an object a stereoscopic offset of 15-120 arcmin of crossed disparity relative to its background would make the object easier to recognize in briefly presented (33-133 ms, temporally masked displays. Disparity had a beneficial effect across a wide range of disparities and display durations. Most of this benefit occurred whether or not the stereoscopic contour agreed with the object's luminance contour. We attribute this benefit to an orienting of spatial attention that selected the object and its local background for enhanced 2D pattern processing. At longer display durations, contour agreement provided an additional benefit, and a separate experiment using random-dot stimuli confirmed that stereoscopic contours plausibly contributed to recognition at the longer display durations in our experiment. We conclude that in real-world situations binocular vision confers an advantage not only for depth perception, but also for recognizing objects from their luminance patterns and bounding contours.

  18. Time-resolved spatially offset Raman spectroscopy for depth analysis of diffusely scattering layers.

    Science.gov (United States)

    Iping Petterson, Ingeborg E; Dvořák, Patrick; Buijs, Joost B; Gooijer, Cees; Ariese, Freek

    2010-12-01

    The objective of this study is to use time-resolved (TR) Raman spectroscopy, spatially offset Raman spectroscopy (SORS), and a combination of these approaches to obtain high quality Raman spectra from materials hidden underneath an opaque layer. Both TR Raman and SORS are advanced techniques that allow for an increased relative selectivity of photons from deeper layers within a sample. Time-resolved detection reduces fluorescence background, and the selectivity for the second layer is improved. By combining this with spatially offset excitation we additionally increased selectivity for deeper layers. Test samples were opaque white polymer blocks of several mm thicknesses. Excitation was carried out with a frequency-doubled Ti:sapphire laser at 460 nm, 3 ps pulse width and 76 MHz repetition rate. Detection was either with a continuous-wave CCD camera or in time-resolved mode using an intensified CCD camera with a 250 ps gate width. The Raman photons were collected in backscatter mode, with or without lateral offset. By measuring the delay of the Raman signal from the second layer (polyethylene terephthalate/PET/Arnite), the net photon migration speeds through Teflon, polythene, Delrin and Nylon were determined. Raman spectra could be obtained from a second layer of PET through Teflon layers up to 7 mm of thickness. The ability to obtain chemical information through layers of diffusely scattering materials has powerful potential for biomedical applications.

  19. Laser Refractography

    CERN Document Server

    Rinkevichyus, B.S; Raskovskaya, I.L

    2010-01-01

    This book describes the basic principles of laser refractography, a flexible new diagnostic tool for measuring optically inhomogeneous media and flows. Laser refractography is based on digital imaging and computer processing of structured laser beam refraction (SLR) in inhomogeneous transparent media. Laser refractograms provide both qualitative and quantitative measurements and can be used for the study of fast and transient processes. In this book, the theoretical basis of refractography is explored in some detail, and experimental setups are described for measurement of transparent media using either 2D (passed radiation) or 3D (scattered radiation) refractograms. Specific examples and applications are discussed, including visualization of the boundary layer near a hot or cold metallic ball in water, and observation of edge effects and microlayers in liquids and gases. As the first book to describe this new and exciting technique, this monograph has broad cross-disciplinary appeal and will be of interest t...

  20. Amazonian vegetable oils and fats: fast typification and quality control via triacylglycerol (TAG) profiles from dry matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry fingerprinting.

    Science.gov (United States)

    Saraiva, Sérgio A; Cabral, Elaine C; Eberlin, Marcos N; Catharino, Rodrigo R

    2009-05-27

    Amazonian oils and fats display unique triacylglycerol (TAG) profiles and, because of their economic importance as renewable raw materials and use by the cosmetic and food industries, are often subject to adulteration and forgery. Representative samples of these oils (andiroba, Brazil nut, buriti, and passion fruit) and fats (cupuaçu, murumuru, and ucuúba) were characterized without pre-separation or derivatization via dry (solvent-free) matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Characteristic profiles of TAG were obtained for each oil and fat. Dry MALDI-TOF MS provides typification and direct and detailed information, via TAG profiles, of their variable combinations of fatty acids. A database from spectra could be developed and may be used for their fast and reliable typification, application screening, and quality control.

  1. 15 CFR 19.10 - How will Commerce entities use administrative offset (offset of non-tax Federal payments) to...

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false How will Commerce entities use administrative offset (offset of non-tax Federal payments) to collect a Commerce debt? 19.10 Section 19.10 Commerce and Foreign Trade Office of the Secretary of Commerce COMMERCE DEBT COLLECTION Procedures...

  2. Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments.

    Science.gov (United States)

    Gaudin, J; Fourment, C; Cho, B I; Engelhorn, K; Galtier, E; Harmand, M; Leguay, P M; Lee, H J; Nagler, B; Nakatsutsumi, M; Ozkan, C; Störmer, M; Toleikis, S; Tschentscher, Th; Heimann, P A; Dorchies, F

    2014-04-17

    The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called "molecular movie" within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.

  3. Enhanced Model for Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Rodney J. [Research Applications Corporation, Los Alamos, NM (United States)

    2010-10-12

    Laser Fusion is a prime candidate for alternate energy production, capable of serving a major portion of the nation's energy needs, once fusion fuel can be readily ignited. Fast Ignition may well speed achievement of this goal, by reducing net demands on laser pulse energy and timing precision. However, Fast Ignition has presented a major challenge to modeling. This project has enhanced the computer code ePLAS for the simulation of the many specialized phenomena, which arise with Fast Ignition. The improved code has helped researchers to understand better the consequences of laser absorption, energy transport, and laser target hydrodynamics. ePLAS uses efficient implicit methods to acquire solutions for the electromagnetic fields that govern the accelerations of electrons and ions in targets. In many cases, the code implements fluid modeling for these components. These combined features, "implicitness and fluid modeling," can greatly facilitate calculations, permitting the rapid scoping and evaluation of experiments. ePLAS can be used on PCs, Macs and Linux machines, providing researchers and students with rapid results. This project has improved the treatment of electromagnetics, hydrodynamics, and atomic physics in the code. It has simplified output graphics, and provided new input that avoids the need for source code access by users. The improved code can now aid university, business and national laboratory users in pursuit of an early path to success with Fast Ignition.

  4. The Influence of Onsets and Offsets on Saccade Programming

    Directory of Open Access Journals (Sweden)

    Frouke Hermens

    2010-08-01

    Full Text Available When making a saccadic eye movement to a peripheral target, a simultaneous stimulus onset at central fixation generally increases saccadic latency, while offsets reduce latency (‘gap effect’. Visual onsets remote from fixation also increase latency (‘remote distractor effect’; however, the influence of remote visual offsets is less clear. Previous studies, which used a search task, found that remote offsets either facilitated, inhibited, or did nothing to saccade latencies towards a peripheral target. It cannot be excluded, however, that the target selection process in such search tasks influenced the results. We therefore simplified the task and asked participants to make eye movements to a predictable target. Simultaneously with target onset, either one or multiple remote stimulus onsets and offsets were presented. It was found that peripheral onsets increased saccade latencies, but offsets did not influence the initiation of a saccade to the target. Moreover, the number of onsets and offsets did not affect the results. These results suggest that earlier effects of remote stimulus offsets and of the number of remote distractor onsets reside in the target identification process of the visual search task rather than the competition between possible saccade goals. The results are discussed in the context of models of saccade target selection.

  5. DFT-based offset-QAM OFDM for optical communications.

    Science.gov (United States)

    Zhao, Jian

    2014-01-13

    We experimentally demonstrate and numerically investigate a discrete-Fourier-transform (DFT) based offset quadrature-amplitude-modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) system. We investigate the scheme using a set of square-root-raised-cosine functions and a set of super-Gaussian functions as signal spectra. It is shown that offset-QAM OFDM exhibits negligible penalty for all investigated spectra, in contrast to rectangular-function based Nyquist FDM (N-FDM) and sinc-function based conventional OFDM (C-OFDM). The required guard interval (GI) length for dispersion compensation in offset-QAM OFDM is analyzed and shown to scale with twice the subcarrier spacing rather than the full OFDM bandwidth. Experimental results show that 38-Gb/s offset-16QAM OFDM supports 600-km fiber transmission with negligible penalty in the absence of GI while a GI length of eight is required in C-OFDM. Further numerical simulations show that by avoiding the GI, 112-Gb/s polarization multiplexed offset-4QAM OFDM can achieve 23% increase in net data rate over C-OFDM under the same transmission reach. We also discuss the design of the pulse-shaping filter in the DFT-based implementation and show that when compared to N-FDM, the required memory length of the filter for pulse shaping can be reduced from 60 to 2 in offset-QAM OFDM regardless of the fiber length.

  6. Line-scan spatially offset Raman spectroscopy for inspecting subsurface food safety and quality

    Science.gov (United States)

    Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

    2016-05-01

    This paper presented a method for subsurface food inspection using a newly developed line-scan spatially offset Raman spectroscopy (SORS) technique. A 785 nm laser was used as a Raman excitation source. The line-shape SORS data was collected in a wavenumber range of 0-2815 cm-1 using a detection module consisting of an imaging spectrograph and a CCD camera. A layered sample, which was created by placing a plastic sheet cut from the original container on top of cane sugar, was used to test the capability for subsurface food inspection. A whole set of SORS data was acquired in an offset range of 0-36 mm (two sides of the laser) with a spatial interval of 0.07 mm. Raman spectrum from the cane sugar under the plastic sheet was resolved using self-modeling mixture analysis algorithms, demonstrating the potential of the technique for authenticating foods and ingredients through packaging. The line-scan SORS measurement technique provides a new method for subsurface inspection of food safety and quality.

  7. Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

    Science.gov (United States)

    Okojie, Robert S.; Lukco, Dorothy; Nguyen, Vu; Savrun, Ender

    2012-01-01

    We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C.

  8. Bayesian integer frequency offset estimator for MIMO-OFDM systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Carrier frequency offset (CFO) in MIMO-OFDM systems can be decoupled into two parts: fraction frequency offset (FFO) and integer frequency offset (IFO). The problem of IFO estimation is addressed and a new IFO estimator based on the Bayesian philosophy is proposed. Also, it is shown that the Bayesian IFO estimator is optimal among all the IFO estimators. Furthermore, the Bayesian estimator can take advantage of oversampling so that better performance can be obtained. Finally, numerical results show the optimality of the Bayesian estimator and validate the theoretical analysis.

  9. Genotoxicity study in lymphocytes of offset printing workers.

    Science.gov (United States)

    Aksoy, Hüseyin; Yilmaz, Serkan; Celik, Mustafa; Yüzbaşioglu, Deniz; Unal, Fatma

    2006-01-01

    The potential cytogenetic damage in offset printing workers was evaluated using sister chromatid exchanges (SCEs), chromosome aberrations (CAs) and micronuclei (MN) as biomarkers in peripheral lymphocytes of 26 volunteers (14 workers, 12 controls). The CA, SCE and MN frequency of offset printing workers was significantly higher than in their controls. The replication index (RI) was not affected while the mitotic index (MI) was affected most in the workers. It can be concluded from this study that chronic occupational exposure to printing dyes and thinner may lead to a slightly increased risk of genetic damage among offset printing workers.

  10. Micron-scale Fast Electron Filamentation and Recirculation determined from Rear Side Optical Emission in High Intensity Laser-Solid Interactions

    CERN Document Server

    Bellei, C; Kar, S; Henig, A; Kneip, S; Palmer, C; Sävert, A; Willingale, L; Carroll, D; Dromey, B; Green, J S; Markey, K; Simpson, P; Clarke, R J; Lowe, H; Neely, D; Spindloe, C; Tolley, M; Kaluza, M; Mangles, S P D; McKenna, P; Norreys, P A; Schreiber, J; Zepf, M; Davies, J R; Krushelnick, K; Najmudin, Z

    2010-01-01

    The transport of relativistic electrons generated in the interaction of petawatt class lasers with solid targets has been studied through measurements of the optical emission from their rear surface. The high degree of polarization of the emission indicates that it is predominantly optical transition radiation. A halo that surrounds the main region of emission is also polarized, and is attributed to the effect of electron recirculation. The variation of the amplitude of the transition radiation with respect to observation angle provides evidence for the presence of {$\\mu$m-size} filaments.

  11. Fast capillary electrophoresis-laser induced fluorescence analysis of ligase chain reaction products: human mitochondrial DNA point mutations causing Leber's hereditary optic neuropathy.

    Science.gov (United States)

    Muth, J; Williams, P M; Williams, S J; Brown, M D; Wallace, D C; Karger, B L

    1996-12-01

    High speed capillary electrophoresis-laser-induced fluorescence (CE-LIF) has been used to separate and detect point mutations using the ligase chain reaction (LCR). The method utilizes short capillary columns (7.5 cm effective length) and fields of 400 V/cm to analyze DNA-ethidium bromide complexes using an He/Ne laser. The method was first demonstrated with a commercially available kit for LCR based on a lacI gene fragment inserted in a Bluescript II phagemid. LCR-CE-LIF was then applied to detect point mutations in human mitochondrial DNA, resulting in Leber's hereditary optic neuropathy (LHON). Three severe mutations were analyzed in which the original base is substituted by a thymidine base at positions 3460, 11778 and 14459. Appropriate primers were designed with polyT tails for length discrimination of pooled samples. Successful detection of mutated samples was achieved, with appropriate correction for small amounts of nonspecific ligated product. The method is rapid, easy to implement, and automatable.

  12. Public Budget Database - Outlays and offsetting receipts 1962-Current

    Data.gov (United States)

    Executive Office of the President — This file contains historical outlays and offsetting receipts for 1962 through the current budget year, as well as four years of projections. It can be used to...

  13. 29 CFR 4903.22 - Administrative offset procedures.

    Science.gov (United States)

    2010-07-01

    ... (access under the Freedom of Information Act (5 U.S.C. 552) or the Privacy Act (5 U.S.C. 552a...) Failure to take the offset would substantially prejudice the government's ability to collect the debt;...

  14. Public Budget Database - Budget Authority and offsetting receipts 1976-Current

    Data.gov (United States)

    Executive Office of the President — This file contains historical budget authority and offsetting receipts for 1976 through the current budget year, as well as four years of projections. It can be used...

  15. Photoionization in alkali lasers.

    Science.gov (United States)

    Knize, R J; Zhdanov, B V; Shaffer, M K

    2011-04-11

    We have calculated photoionization rates in alkali lasers. The photoionization of alkali atoms in the gain medium of alkali lasers can significantly degrade the laser performance by reducing the neutral alkali density and with it the gain. For a ten atmosphere Rb laser and a Cs exciplex laser, the photoionization induced alkali atom loss rates are greater than 10(5) sec(-1). These high loss rates will quickly deplete the neutral alkali density, reducing gain, and may require fast, possibly, supersonic flow rates to sufficiently replenish the neutral medium for CW operation.

  16. A study of an effective offsets model for Korea

    OpenAIRE

    Kam, Mookun; Kang, Hyungphil

    2013-01-01

    Approved for public release; distribution is unlimited. One way of acquiring defense science technology is through offsets. When one country buys a weapon system from another country, it acquires critical technology and defense supplies as a return service. Korea has been using offsets since 1983 to develop a defense industry and to improve its defense science technology. Since the establishment of the Korean Defense Acquisition Program Administration (KDAPA), Korea has been trying to impr...

  17. Spatially Offset Active Galactic Nuclei. I. Selection and Spectroscopic Properties

    Science.gov (United States)

    Barrows, R. Scott; Comerford, Julia M.; Greene, Jenny E.; Pooley, David

    2016-09-01

    We present a sample of 18 optically selected and X-ray-detected spatially offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS). In nine systems, the X-ray active galactic nucleus (AGN) is spatially offset from the galactic stellar core that is located within the 3″ diameter SDSS spectroscopic fiber. In 11 systems, the X-ray AGN is spatially offset from a stellar core that is located outside the fiber, with an overlap of two. To build the sample, we cross-matched Type II AGNs selected from the SDSS galaxy catalog with archival Chandra imaging and employed our custom astrometric and registration procedure. The projected angular (physical) offsets span a range of 0.″6 (0.8 kpc) to 17.″4 (19.4 kpc), with a median value of 2.″7 (4.6 kpc). The offset nature of an AGN is an unambiguous signature of a galaxy merger, and these systems can be used to study the properties of AGNs in galaxy mergers without the biases introduced by morphological merger selection techniques. In this paper (Paper I), we use our sample to assess the kinematics of AGN photoionized gas in galaxy mergers. We find that spectroscopic offset AGN selection may be up to {89}-16+7% incomplete due to small projected velocity offsets. We also find that the magnitude of the velocity offsets are generally larger than expected if our spatial selection introduces a bias toward face-on orbits, suggesting the presence of complex kinematics in the emission line gas of AGNs in galaxy mergers.

  18. Carbon offsets, reversal risk and US climate policy

    Directory of Open Access Journals (Sweden)

    Chen Yihsu

    2009-06-01

    Full Text Available Abstract Background One controversial issue in the larger cap-and-trade debate is the proper use and certification of carbon offsets related to changes in land management. Advocates of an expanded offset supply claim that inclusion of such activities would expand the scope of the program and lower overall compliance costs, while opponents claim that it would weaken the environmental integrity of the program by crediting activities that yield either nonexistent or merely temporary carbon sequestration benefits. Our study starts from the premise that offsets are neither perfect mitigation instruments nor useless "hot air." Results We show that offsets provide a useful cost containment function, even when there is some threat of reversal, by injecting additional "when-flexibility" into the system. This allows market participants to shift their reduction requirements to periods of lower cost, thereby facilitating attainment of the least-cost time path without jeopardizing the cumulative environmental integrity of the system. By accounting for market conditions in conjunction with reversal risk, we develop a simple offset valuation methodology, taking into account the two most important factors that typically lead offsets to be overvalued or undervalued. Conclusion The result of this paper is a quantitative "model rule" that could be included in future legislation or used as a basis for active management by a future "carbon fed" or other regulatory authority with jurisdiction over the US carbon market to actively manage allowance prices.

  19. CDP mapping and image reconstruction by using offset VSP data

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Because zero-offset VSP (Vertical Seismic Profile) data can only provide the information of rock properties and structure in the area around the Fresnel zone within the well, the scheme of VSP with offset was developed to acquire the reflection information away from the borehole in order to widen the range of VSP survey and to improve the precision of imaging.In this paper, we present a new CDP (Common Depth Point) mapping approach to image the reflecting structure by using offset VSP data. For the processing of offset VSP data, we firstly separated the up-going and down-going wave-fields from VSP data by means of F-K filtering technique, and we can calculate the mapping conditions (position and reflecting traveltime for CDP point) in homogeneous media, and then reconstruct the inner structure of the earth.This method is tested by using the offset VSP data which are used to simulate the case of super-deep borehole by means of finite-difference method. The imaged structure matches the real model very well. The results show that the method present here could accurately image the inner structure of the earth if the deviation of initial velocity model from the true model is less than 10%. Finally, we presented the imaged results for the real offset data by using this method.

  20. FAST TRACK COMMUNICATION: Counterintuitive angular shifts in the photoelectron momentum distribution for atoms in strong few-cycle circularly polarized laser pulses

    Science.gov (United States)

    Martiny, C. P. J.; Abu-samha, M.; Madsen, L. B.

    2009-08-01

    We solve the three-dimensional time-dependent Schrödinger equation for a three-cycle circularly polarized laser pulse interacting with an atom. The photoelectron momentum distributions show counterintuitive shifts, similar to those observed in a recent experiment (Eckle et al 2008 Science 322 1525). The physical origin of the shifts is examined by a detailed investigation of the wave packet after the pulse. We show that the shifts arise as a consequence of an intimate interplay between the external field and the binding potential, and that the shifts occur also at lower intensities than used in the experiment, corresponding to the multiphoton regime. In contrast to the recent experiment we do not invoke the concept of a tunnelling time in our explanation of the shifts.

  1. Multipass optical absorption spectroscopy: a fast-scanning laser spectrometer for the in situ determination of atmospheric trace-gas components, in particular OH.

    Science.gov (United States)

    Armerding, W; Spiekermann, M; Walter, J; Comes, F J

    1996-07-20

    The optical design of an absorption spectrometer for in situ measurements of atmospheric trace gases is reported. The light source is a rapidly tuned and power-stabilized dye-ring laser, which is frequency doubled by an intracavity BBO crystal. The second harmonic and the fundamental are used simultaneously for measurement of OH, SO(2), CH(2)O, and naphthalene in the UV and of NO(2) in the visible. The 1.2-km absorption path is folded within a 6-m White-cell-type multiple-reflection system with an open-path setup. The absorption sensitivity of the spectrometer is better than 1 part in 10(-5) under tropospheric conditions (integration time 1 min., signal-to-noise ratio 1).

  2. Nuclear moments, spins and charge radii of copper isotopes from N=28 to N=50 by collinear fast-beam laser spectroscopy

    CERN Multimedia

    2002-01-01

    We aim at establishing an unambiguous spin determination of the ground and isomeric states in the neutron rich Cu-isotopes from A=72 up to A=78 and to measure the magnetic and quadrupole moments between the N=28 and N=50 shell closures. This study will provide information on the double-magicity of $^{56}$Ni and $^{78}$Ni, both at the extremes of nuclear stability. It will provide evidence on the suggested inversion of ground state spin around A$\\approx$74, due to the monopole migration of the $\\pi f_{5/2}$ level. The collinear laser spectroscopy technique will be used, which furthermore provides information on the changes in mean square charge radii between both neutron shell closures, probing a possible onset of deformation in this region.

  3. Slow and fast light via two-wave mixing in the rare-earth doped optical fibers (Conference Presentation)

    Science.gov (United States)

    Stepanov, Serguei I.; Plata Sánchez, Marcos; Hernández, Eliseo

    2017-02-01

    Dynamic population Bragg gratings can be recorded in the rare-earth-doped (e.g. doped with erbium or ytterbium) optical fibers with mWatt-scale cw laser power. Two-wave mixing (TWM) via such gratings is utilized in single-frequency fiber lasers and in adaptive interferometric fiber sensors with automatic stabilization of the operation point. Slow and fast light propagation can also be observed in the vicinity of narrow ( 20-200Hz) spectral profile of stationary no-degenerate TWM. In particular, slow light propagation is observed for the purely amplitude grating, recorded in the erbium-doped fiber in spectral range 1510-1550nm. In its turn, in ytterbium-doped fibers at 1064nm (or in erbium-doped fiber at the wavelength below 1500nm) the dynamic grating has significant contribution of the phase component, the TWM profile has essentially asymmetric form, and both slow and fast (superluminal) light propagation is possible at different frequency off-sets between the counter-propagating interacting waves.

  4. Common-image gathers in the offset domain from reverse-time migration

    KAUST Repository

    Zhan, Ge

    2014-04-01

    Kirchhoff migration is flexible to output common-image gathers (CIGs) in the offset domain by imaging data with different offsets separately. These CIGs supply important information for velocity model updates and amplitude-variation-with-offset (AVO) analysis. Reverse-time migration (RTM) offers more insights into complex geology than Kirchhoff migration by accurately describing wave propagation using the two-way wave equation. But, it has difficulty to produce offset domain CIGs like Kirchhoff migration. In this paper, we develop a method for obtaining offset domain CIGs from RTM. The method first computes the RTM operator of an offset gather, followed by a dot product of the operator and the offset data to form a common-offset RTM image. The offset domain CIGs are then achieved after separately migrating data with different offsets. We generate offset domain CIGs on both the Marmousi synthetic data and 2D Gulf of Mexico real data using this approach. © 2014.

  5. Ultra-fast cyclosporin A quantitation in whole blood by Laser Diode Thermal Desorption-tandem mass spectrometry; comparison with High Performance Liquid Chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Jourdil, Jean-François; Picard, Pierre; Meunier, Cécile; Auger, Serge; Stanke-Labesque, Françoise

    2013-12-17

    In the last decade the quantitation of immunosuppressive drugs has seen vast improvements in analytical methods, optimizing time, accuracy of analysis and cost. Laser Diode Thermal Desorption (LDTD) coupled to Atmospheric Pressure Chemical ionization-tandem mass spectrometry (APCI-MS/MS) represents a technological breakthrough that removes the chromatographic separation step and thereby significantly increases the analytical throughput for the quantitation of cyclosporin A (CsA) in whole blood for therapeutic drug monitoring (TDM). A simple protein precipitation step was used prior to depositing 5 μL of the extract on a 96-well LazWell™ plate and CsA was quantified by LDTD-APCI-MS/MS. The laser pattern was set to ramp from 0 to 45% laser power within 2 s. The APCI parameters were set to negative needle voltage (-2 μA), carrier gas temperature (30°C) and air flow rate (3 L min(-1)). The negative ion single reaction monitoring transitions for CsA and its internal standard cyclosporin D (CsD) were respectively m/z 1201.1/1088.9 and m/z 1214.8/1102.8; obtained with a collision energy of -40 V. The analysis was achieved within 9 s from sample to sample. The extraction procedure yielded high recovery (92%; RSD=9.4%, n=6). The lower limit of quantitation was fixed at the first level of calibration: 23.5 ng mL(-1) (accuracy=112.3%; RSD=9.6%; n=6) and a blank+6 point linear regression up to 965 ng mL(-1) was used. Using 4 levels of quality control (QC), intra-day assays (n=6) ranged from 93.5 to 95.7% (bias) and from 3.4 to 13.1% (RSD) while inter-day assays (n=6) ranged from 92.9 to 105.3% (bias) and from 4.9 to 7.5% (RSD). An inter-sample contamination of CsA of 2.3% was calculated that was considered negligible with respect to the range of CsA concentrations. Whole blood samples (120) from patients under CsA treatment were analyzed by LDTD-APCI-MS/MS and HPLC-ESI-MS/MS, the gold standard reference method for CsA quantification. Both methods agreed (P≥0.99), with a

  6. Upper-ocean-to-atmosphere radiocarbon offsets imply fast deglacial carbon dioxide release.

    Science.gov (United States)

    Rose, Kathryn A; Sikes, Elisabeth L; Guilderson, Thomas P; Shane, Phil; Hill, Tessa M; Zahn, Rainer; Spero, Howard J

    2010-08-26

    Radiocarbon in the atmosphere is regulated largely by ocean circulation, which controls the sequestration of carbon dioxide (CO(2)) in the deep sea through atmosphere-ocean carbon exchange. During the last glaciation, lower atmospheric CO(2) levels were accompanied by increased atmospheric radiocarbon concentrations that have been attributed to greater storage of CO(2) in a poorly ventilated abyssal ocean. The end of the ice age was marked by a rapid increase in atmospheric CO(2) concentrations that coincided with reduced (14)C/(12)C ratios (Delta(14)C) in the atmosphere, suggesting the release of very 'old' ((14)C-depleted) CO(2) from the deep ocean to the atmosphere. Here we present radiocarbon records of surface and intermediate-depth waters from two sediment cores in the southwest Pacific and Southern oceans. We find a steady 170 per mil decrease in Delta(14)C that precedes and roughly equals in magnitude the decrease in the atmospheric radiocarbon signal during the early stages of the glacial-interglacial climatic transition. The atmospheric decrease in the radiocarbon signal coincides with regionally intensified upwelling and marine biological productivity, suggesting that CO(2) released by means of deep water upwelling in the Southern Ocean lost most of its original depleted-(14)C imprint as a result of exchange and isotopic equilibration with the atmosphere. Our data imply that the deglacial (14)C depletion previously identified in the eastern tropical North Pacific must have involved contributions from sources other than the previously suggested carbon release by way of a deep Southern Ocean pathway, and may reflect the expanded influence of the (14)C-depleted North Pacific carbon reservoir across this interval. Accordingly, shallow water masses advecting north across the South Pacific in the early deglaciation had little or no residual (14)C-depleted signals owing to degassing of CO(2) and biological uptake in the Southern Ocean.

  7. Fast Light Optical Gyroscopes

    Science.gov (United States)

    Smith, David D.

    2015-01-01

    Next-generation space missions are currently constrained by existing spacecraft navigation systems which are not fully autonomous. These systems suffer from accumulated dead-reckoning errors and must therefore rely on periodic corrections provided by supplementary technologies that depend on line-of-sight signals from Earth, satellites, or other celestial bodies for absolute attitude and position determination, which can be spoofed, incorrectly identified, occluded, obscured, attenuated, or insufficiently available. These dead-reckoning errors originate in the ring laser gyros themselves, which constitute inertial measurement units. Increasing the time for standalone spacecraft navigation therefore requires fundamental improvements in gyroscope technologies. One promising solution to enhance gyro sensitivity is to place an anomalous dispersion or fast light material inside the gyro cavity. The fast light essentially provides a positive feedback to the gyro response, resulting in a larger measured beat frequency for a given rotation rate as shown in figure 1. Game Changing Development has been investing in this idea through the Fast Light Optical Gyros (FLOG) project, a collaborative effort which began in FY 2013 between NASA Marshall Space Flight Center (MSFC), the U.S. Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC), and Northwestern University. MSFC and AMRDEC are working on the development of a passive FLOG (PFLOG), while Northwestern is developing an active FLOG (AFLOG). The project has demonstrated new benchmarks in the state of the art for scale factor sensitivity enhancement. Recent results show cavity scale factor enhancements of approx.100 for passive cavities.

  8. Design of high speed and low offset dynamic latch comparator in 0.18 µm CMOS process.

    Science.gov (United States)

    Rahman, Labonnah Farzana; Reaz, Mamun Bin Ibne; Yin, Chia Chieu; Ali, Mohammad Alauddin Mohammad; Marufuzzaman, Mohammad

    2014-01-01

    The cross-coupled circuit mechanism based dynamic latch comparator is presented in this research. The comparator is designed using differential input stages with regenerative S-R latch to achieve lower offset, lower power, higher speed and higher resolution. In order to decrease circuit complexity, a comparator should maintain power, speed, resolution and offset-voltage properly. Simulations show that this novel dynamic latch comparator designed in 0.18 µm CMOS technology achieves 3.44 mV resolution with 8 bit precision at a frequency of 50 MHz while dissipating 158.5 µW from 1.8 V supply and 88.05 µA average current. Moreover, the proposed design propagates as fast as 4.2 nS with energy efficiency of 0.7 fJ/conversion-step. Additionally, the core circuit layout only occupies 0.008 mm2.

  9. Spatially Offset Active Galactic Nuclei I: Selection and Spectroscopic Properties

    CERN Document Server

    Barrows, R Scott; Greene, Jenny E; Pooley, David

    2016-01-01

    We present a sample of 18 optically-selected and X-ray detected spatially offset active galactic nuclei (AGN) from the Sloan Digital Sky Survey (SDSS). In 9 systems, the X-ray AGN is spatially offset from the galactic stellar core that is located within the 3'' diameter SDSS spectroscopic fiber. In 11 systems, the X-ray AGN is spatially offset from a stellar core that is located outside the fiber, with an overlap of 2. To build the sample, we cross-matched Type II AGN selected from the SDSS galaxy catalogue with archival Chandra imaging and employed our custom astrometric and registration procedure. The projected angular (physical) offsets span a range of 0."6 (0.8 kpc) to 17."4 (19.4 kpc), with a median value of 2."7 (4.6 kpc). The offset nature of an AGN is an unambiguous signature of a galaxy merger, and these systems can be used to study the properties of AGN in galaxy mergers without the biases introduced by morphological merger selection techniques. In this paper (Paper I), we use our sample to assess t...

  10. Estimation of satellite antenna phase center offsets for Galileo

    Science.gov (United States)

    Steigenberger, P.; Fritsche, M.; Dach, R.; Schmid, R.; Montenbruck, O.; Uhlemann, M.; Prange, L.

    2016-08-01

    Satellite antenna phase center offsets for the Galileo In-Orbit Validation (IOV) and Full Operational Capability (FOC) satellites are estimated by two different analysis centers based on tracking data of a global GNSS network. The mean x- and y-offsets could be determined with a precision of a few centimeters. However, daily estimates of the x-offsets of the IOV satellites show pronounced systematic effects with a peak-to-peak amplitude of up to 70 cm that depend on the orbit model and the elevation of the Sun above the orbital plane. For the IOV y-offsets, no dependence on the orbit model exists but the scatter strongly depends on the elevation of the Sun above the orbital plane. In general, these systematic effects are significantly smaller for the FOC satellites. The z-offsets of the two analysis centers agree within the 10-15 cm level, and the time series do not show systematic effects. The application of an averaged Galileo satellite antenna model obtained from the two solutions results in a reduction of orbit day boundary discontinuities by up to one third—even if an independent software package is used.

  11. Amateur Cleanrooms: Costs May Not Offset Benefits

    Science.gov (United States)

    Ramsey, W. Lawrence

    2005-01-01

    Contamination and Coatings Branch During my career at NASA, I have encountered a variety of cleanroom systems. With many projects, cost pressures and lack of adequate facilities have forced the managers to resort to amateur cleanrooms to manufacture spacecraft and instruments. These rooms are usually spaces that have been used for other purposes that are converted to cleanroom, usually without the assistance of a contamination control specialist. Often, scientists and engineers are successful in converting an area for experimental use. However, when the area is used for production, countless difficulties are encountered. This paper will document some of the disasters that I have personally witnessed and offer some guidelines for contamination professionals to follow if you are called upon to assist in the development of new cleanrooms. Cleanroom come in all shapes and sizes from special purpose mini-environments (such as flow benches) to large, expansive production facilities. These areas may require a variety of unit operations to be carried out within a short range of each other. The design of the cleanroom should account for compatibilities of these operations to protect the product and personnel. The level of cleanliness has traditionally been associated with the method of ventilation. However, just because and =ea has HEPA filters and greater that 20 air changes per hour does not mean that it is a cleanroom. Airflow is extremely complex; the only way to properly design a cleanroom is through the use of a computer based model. In the aerospace industry, few engineered cleanrooms are modeled. Modeling has been perceived as expensive; however, modern programs and fast computers are changing perception. It is the lack of appreciation for how air flow and location within a cleanroom affects the product that causes most of the problems I have experienced. Currently, the rules defining the best air flow design practices are based on simplistic historical data that

  12. Long-term laser frequency stabilization using fiber interferometers

    CERN Document Server

    Kong, Jia; Jimenez-Martinez, Ricardo; Mitchell, Morgan W

    2014-01-01

    We report long-term laser frequency stabilization using only the target laser and a pair of 5 m fiber interferometers, one as a frequency reference and the second as a sensitive thermometer. When used to stabilize a distributed feedback laser at 795 nm, the frequency Allan deviation at 1000 s drops from 5.6*10^{-8} to 6.9*10^{-10}. The performance equals that of an offset lock employing a second laser and an atomic reference.

  13. Flow and heat transfer in compact offset strip fin surfaces

    Institute of Scientific and Technical Information of China (English)

    Junqi DONG; Jiangping CHEN; Zhijiu CHEN

    2008-01-01

    Experimental studies of air-side heat transfer and pressure drop characteristics of offset strip fins and flat tube heat exchangers were performed. A series of tests were conducted for 9 heat exchangers with different fin space, fin height, fin strip length and flow length, at a constant tube-side water flow rate of 2.5 m3/h. The char-acteristics of the heat transfer and pressure drop of differ-ent fin space, fin height and fin length were analyzed and compared. The curves of the heat transfer coefficients vs. The pumping power per unit frontal area were then plot-ted. Moreover, the enhanced heat transfer mechanism of offset strip fins was analyzed using field synergy theory. The results showed that fin length and flow length have more obviously effect on the thermal hydraulic character-istics of offset strip fins.

  14. The seam offset identification based on support vector regression machines

    Institute of Scientific and Technical Information of China (English)

    Zeng Songsheng; Shi Yonghua; Wang Guorong; Huang Guoxing

    2009-01-01

    The principle of the support vector regression machine(SVR) is first analysed. Then the new data-dependent kernel function is constructed from information geometry perspective. The current waveforms change regularly in accordance with the different horizontal offset when the rotational frequency of the high speed rotational arc sensor is in the range from 15 Hz to 30 Hz. The welding current data is pretreated by wavelet filtering, mean filtering and normalization treatment. The SVR model is constructed by making use of the evolvement laws, the decision function can be achieved by training the SVR and the seam offset can be identified. The experimental results show that the precision of the offset identification can be greatly improved by modifying the SVR and applying mean filtering from the longitudinal direction.

  15. A NOVEL INTEGER FREQUENCY OFFSET ESTIMATOR FOR OFDM

    Institute of Scientific and Technical Information of China (English)

    Cai Xuelian; Li Jiandong; Li Changle; Chen Chen

    2005-01-01

    One of the principal disadvantages of Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency offset. The integer frequency offset has no effect on the orthogonality among the subcarriers, but it causes a circular shift and phase rotation of the received data symbols sequence, resulting in a Bit Error Rate(BER) of 0.5. In this paper,a novel integer frequency offset estimator for OFDM is derived based on maximum likelihood estimation technique and exploration of the differential relation between two consecutive OFDM data symbol sequences in frequency domain. Its performance is compared with the conventional method by computer simulations for the additive white Gaussian noise channel and a multipath fading channel. Simulation results show that the performance of the proposed estimator is better than the conventional estimator.

  16. Contact of surfaces and contact characteristics of offset surfaces

    Institute of Scientific and Technical Information of China (English)

    Lixin CAO; Hu GONG; Jian LIU

    2008-01-01

    Based on differential geometry, the contact problems of two surfaces are discussed in this paper. The relationship between the contact status of two sur-faces and that of offset surfaces are also analyzed. For a 5-axis NC machining, some research such as optimization of cutter location and calculation of the geometrical cusp height are important. The research results indicate that the relative normal curvature is an important geometrical invariant for describing the contact state of two surfaces. For point contact two surfaces, the calculation equation for the second order remained error is given. For line contact two surfaces, the condition of the second order line contact is that the principal directions and curvatures of the two surfaces are the same along the contact curve. If two surfaces keep the second order line contact, their two offset surfaces will also keep the second order line contact, and their third order remained errors are also uniform with that of the two offset surfaces.

  17. Flexible Laser Metal Cutting

    DEFF Research Database (Denmark)

    Villumsen, Sigurd; Jørgensen, Steffen Nordahl; Kristiansen, Morten

    2014-01-01

    This paper describes a new flexible and fast approach to laser cutting called ROBOCUT. Combined with CAD/CAM technology, laser cutting of metal provides the flexibility to perform one-of-a-kind cutting and hereby realises mass production of customised products. Today’s laser cutting techniques...... possess, despite their wide use in industry, limitations regarding speed and geometry. Research trends point towards remote laser cutting techniques which can improve speed and geometrical freedom and hereby the competitiveness of laser cutting compared to fixed-tool-based cutting technology...... such as punching. This paper presents the concepts and preliminary test results of the ROBOCUT laser cutting technology, a technology which potentially can revolutionise laser cutting....

  18. Three-dimensional study of turbulent flow characteristics of an offset plane jet with variable density

    Science.gov (United States)

    Assoudi, Ali; Habli, Sabra; Mahjoub Saïd, Nejla; Bournot, Hervé; Le Palec, Georges

    2016-11-01

    An experimental and numerical investigation of the flow field of variable density turbulent offset jet is presented. The velocity measurements are performed using a Velocimetry Laser Doppler technique for an offset height h. Three cases of variable-density turbulent plane jets discharging from a rectangular nozzle into a quiescent medium are studied. The variation density jets considered were revealed at different Reynolds numbers. In the second step of this work, a numerical three-dimensional model of the problem is simulated through the resolution of the Navier-Stokes equations by means of the finite volume method and the Reynolds stress model second-order turbulent closure model. A non-uniform mesh system tightened close to the emitting nozzle and both the vertical and horizontal walls is also adopted. A good level of agreement was achieved, between the experiments and the calculations. Once the model validated, our model allowed the evaluation of the influence of the variation density on the characterizing features of the resulting flow filed. It is found that the centerline velocity and concentration of the heavier jet decays much faster than in the two other jets, and a similar behavior for the vertical profiles in the three variable-density jets is well reproduced in the simulation.

  19. Pulsar Pair Cascades in Magnetic Fields with Offset Polar Caps

    Science.gov (United States)

    Harding, Alice K.; Muslimov, Alex G.

    2012-01-01

    Neutron star magnetic fields may have polar caps (PC) that are offset from the dipole axis, through field-line sweepback near the light cylinder or non-symmetric currents within the star. The effects of such offsets on electron-positron pair cascades are investigated, using simple models of dipole magnetic fields with small distortions that shift the PCs by different amounts or directions. Using a Monte Carlo pair cascade simulation, we explore the changes in the pair spectrum, multiplicity and energy flux across the PC, as well as the trends in pair flux and pair energy flux with spin-down luminosity, L(sub sd). We also give an estimate of the distribution of heating flux from returning positrons on the PC for different offsets. We find that even modest offsets can produce significant increases in pair multiplicity, especially for pulsars that are near or beyond the pair death lines for centered PCs, primarily because of higher accelerating fields. Pair spectra cover several decades in energy, with the spectral range of millisecond pulsars (MSPs) two orders of magnitude higher than for normal pulsars, and PC offsets allow significant extension of all spectra to lower pair energies. We find that the total PC pair luminosity L(sub pair) is proportional to L(sub sd), with L(sub pair) approximates 10(exp -3) L(sub sd) for normal pulsars and L(sub pair) approximates 10(exp -2) L(sub sd) for MSPs. Remarkably, the total PC heating luminosity for even large offsets increases by less than a factor of two, even though the PC area increases by much larger factors, because most of the heating occurs near the magnetic axis.

  20. Is there any empirical support for biodiversity offset policy?

    Science.gov (United States)

    Curran, Michael; Hellweg, Stefanie; Beck, Jan

    2014-06-01

    Biodiversity offsets are seen as a policy mechanism to balance development and conservation goals. Many offset schemes employ habitat restoration in one area to recreate biodiversity value that is destroyed elsewhere, assuming that recovery is timely and predictable. Recent research has challenged these assumptions on the grounds that restoration implies long time delays and a low certainty of success. To investigate these assertions, and to assess the strength of empirical support for offset policy, we used a meta-analytic approach to analyze data from 108 comparative studies of secondary growth (SG) and old-growth (OG) habitat (a total of 1228 SG sites and 716 OG reference sites). We extracted species checklists and calculated standardized response ratios for species richness, Fisher's alpha, Sorenson similarity, and Morisita-Horn similarity. We modeled diversity change with habitat age using generalized linear models and multi-model averaging, correcting for a number of potential explanatory variables. We tested whether (1) diversity of passively and actively restored habitat converges to OG values over time, (2) active restoration significantly accelerates this process, and (3) current offset policies are appropriate to the predicted uncertainties and time lags associated with restoration. The results indicate that in the best case, species richness converges to OG reference values within a century, species similarity (Sorenson) takes about twice as long, and assemblage composition (Morisita-Horn) up to an order of magnitude longer (hundreds to thousands of years). Active restoration significantly accelerates the process for all indices, but the inherently large time lags, uncertainty, and risk of restoration failure require offset ratios that far exceed what is currently applied in practice. Restoration offset policy therefore leads to a net loss of biodiversity, and represents an inappropriate use of the otherwise valuable tool of ecosystem restoration.

  1. Optimization based tuning approach for offset free MPC

    DEFF Research Database (Denmark)

    Olesen, Daniel Haugård; Huusom, Jakob Kjøbsted; Jørgensen, John Bagterp

    2012-01-01

    We present an optimization based tuning procedure with certain robustness properties for an offset free Model Predictive Controller (MPC). The MPC is designed for multivariate processes that can be represented by an ARX model. The advantage of ARX model representations is that standard system...... identifiation techniques using convex optimization can be used for identification of such models from input-output data. The stochastic model of the ARX model identified from input-output data is modified with an ARMA model designed as part of the MPC-design procedure to ensure offset-free control. The ARMAX...

  2. Improved Carrier Frequency Offset Estimation in OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-ming; LIU Yuan-an

    2004-01-01

    A new carrier frequency offset estimation algorithm in Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed. The proposed algorithm is an improvement of the Michele Morelli (M&M) algorithm. It also uses a training symbol which is divided into L>2 identical parts to estimate the carrier frequency offset, and the estimation range is ±L/2 the subcarrier spacing, but the performance of the proposed Maximum Likelihood (ML) algorithm is more robust and complex efficient than the M&M algorithm.

  3. Can scale-freeness offset delayed signal detection in neuronal networks?

    CERN Document Server

    Uzun, Rukiye; Perc, Matjaz

    2014-01-01

    First spike latency following stimulus onset is of significant physiological relevance. Neurons transmit information about their inputs by transforming them into spike trains, and the timing of these spike trains is in turn crucial for effectively encoding that information. Random processes and uncertainty that underly neuronal dynamics have been shown to prolong the time towards the first response in a phenomenon dubbed noise-delayed decay. Here we study whether Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise might have shorter response times to external stimuli just above threshold if placed on a scale-free network. We show that the heterogeneity of the interaction network may indeed eradicate slow responsiveness, but only if the coupling between individual neurons is sufficiently strong. Increasing the average degree also favors a fast response, but it is less effective than increasing the coupling strength. We also show that noise-delayed decay can be offset further by adjusting the fre...

  4. Measuring coalignment of retroreflectors with large lateral incoming-outgoing beam offset

    Energy Technology Data Exchange (ETDEWEB)

    Schütze, Daniel, E-mail: Daniel.Schuetze@aei.mpg.de; Sheard, Benjamin S.; Heinzel, Gerhard; Danzmann, Karsten [Max Planck Institute for Gravitational Physics (Albert Einstein Institute) and Institute for Gravitational Physics, Leibniz Universität Hannover, Callinstr. 38, 30167 Hanover (Germany); Farrant, David [Commonwealth Scientific and Industrial Research Organisation, Bradfield Road, Lindfield, NSW 2070 (Australia); Shaddock, Daniel A. [Centre for Gravitational Physics, Australian National University, Acton, ACT 0200 (Australia)

    2014-03-15

    A method based on phase-shifting Fizeau interferometry is presented with which retroreflectors with large incoming-outgoing beam separations can be tested. The method relies on a flat Reference Bar that is used to align two auxiliary mirrors parallel to each other to extend the aperture of the interferometer. The method is applied to measure the beam coalignment of a prototype Triple Mirror Assembly of the GRACE Follow-On Laser Ranging Interferometer, a future satellite-to-satellite tracking device for Earth gravimetry. The Triple Mirror Assembly features a lateral beam offset of incoming and outgoing beam of 600 mm, whereas the acceptance angle for the incoming beam is only about ±2 mrad. With the developed method, the beam coalignment of the prototype Triple Mirror Assembly was measured to be 9 μrad with a repeatability of below 1 μrad.

  5. Applications of spatially offset Raman spectroscopy to defense and security

    Science.gov (United States)

    Guicheteau, Jason; Hopkins, Rebecca

    2016-05-01

    Spatially offset Raman spectroscopy (SORS) allows for sub-surface and through barrier detection and has applications in drug analysis, cancer detection, forensic science, as well as defense and security. This paper reviews previous efforts in SORS and other through barrier Raman techniques and presents a discussion on current research in defense and security applications.

  6. 31 CFR 240.11 - Treasury Check Offset.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Treasury Check Offset. 240.11 Section 240.11 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE INDORSEMENT AND PAYMENT OF CHECKS...

  7. Subsurface offset behaviour in velocity analysis with extended reflectivity images

    NARCIS (Netherlands)

    Mulder, W.A.

    2012-01-01

    Migration velocity analysis with the wave equation can be accomplished by focusing of extended migration images, obtained by introducing a subsurface offset or shift. A reflector in the wrong velocity model will show up as a curve in the extended image. In the correct model, it should collapse to a

  8. Using Audio-Derived Affective Offset to Enhance TV Recommendation

    DEFF Research Database (Denmark)

    Shepstone, Sven Ewan; Tan, Zheng-Hua; Jensen, Søren Holdt

    2014-01-01

    , by navigating the emotion space to request an alternative match. The final match is then compared to the initial match, in terms of the difference in the items' affective parameterization . This offset is then utilized in future recommendation sessions. The system was evaluated by eliciting three different...

  9. 20 CFR 355.44 - Right to administrative offset.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Right to administrative offset. 355.44 Section 355.44 Employees' Benefits RAILROAD RETIREMENT BOARD ADMINISTRATIVE REMEDIES FOR FRAUDULENT CLAIMS OR STATEMENTS REGULATIONS UNDER THE PROGRAM FRAUD CIVIL REMEDIES ACT OF 1986 § 355.44 Right...

  10. 5 CFR 845.206 - Collection by administrative offset.

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Collection of Overpayment Debts... her designee will determine the cost effectiveness of leaving a claim unresolved for more than 6 years... likelihood of recovering the debt. (2) Salary offset. When the debtor is an employee, or a member of...

  11. Forest Carbon Offsets Revisited: Shedding Light on Darkwoods

    NARCIS (Netherlands)

    Kooten, van G.C.; Bogle, T.; Vries, de F.P.

    2015-01-01

    This paper investigates the viability of carbon offset credits created through forest conservation and preservation. A detailed forest management model based on a case study of a forest estate in southeastern British Columbia, owned by The Nature Conservancy of Canada (NCC) is used to demonstrate th

  12. Simulation of an offset crash for tibia index evaluation

    NARCIS (Netherlands)

    Mugnai, A.; Burke, G.

    2000-01-01

    In 1996, the European Community released new regulations relating to frontal impact vehicle crash. One of the tests, the European offset crash, consists of crashing the car on a deformable barrier at 56 km/h with 40% of the car impacting on the barrier. The regulations require the dummy injury param

  13. 14 CFR 1261.603 - Procedures for salary offset.

    Science.gov (United States)

    2010-01-01

    ..., proven incapacity, illness, or hospitalization), or that the agency did not give notice of the time limit... subsistence expenses for food, reasonable housing, clothing, transportation, and medical care. In determining whether an offset would prevent the employee from meeting the essential subsistence expenses, the employee...

  14. Performance and Vibration Analyses of Lift-Offset Helicopters

    Directory of Open Access Journals (Sweden)

    Jeong-In Go

    2017-01-01

    Full Text Available A validation study on the performance and vibration analyses of the XH-59A compound helicopter is conducted to establish techniques for the comprehensive analysis of lift-offset compound helicopters. This study considers the XH-59A lift-offset compound helicopter using a rigid coaxial rotor system as a verification model. CAMRAD II (Comprehensive Analytical Method of Rotorcraft Aerodynamics and Dynamics II, a comprehensive analysis code, is used as a tool for the performance, vibration, and loads analyses. A general free wake model, which is a more sophisticated wake model than other wake models, is used to obtain good results for the comprehensive analysis. Performance analyses of the XH-59A helicopter with and without auxiliary propulsion are conducted in various flight conditions. In addition, vibration analyses of the XH-59A compound helicopter configuration are conducted in the forward flight condition. The present comprehensive analysis results are in good agreement with the flight test and previous analyses. Therefore, techniques for the comprehensive analysis of lift-offset compound helicopters are appropriately established. Furthermore, the rotor lifts are calculated for the XH-59A lift-offset compound helicopter in the forward flight condition to investigate the airloads characteristics of the ABC™ (Advancing Blade Concept rotor.

  15. 41 CFR 105-70.044 - Right to administrative offset.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Right to administrative offset. 105-70.044 Section 105-70.044 Public Contracts and Property Management Federal Property Management Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General...

  16. A Meta-Regression Analysis of Forest Carbon Offset Costs

    NARCIS (Netherlands)

    Kooten, van G.C.; Laaksonen-Craig, S.; Wang, Y.

    2009-01-01

    The main focus of efforts to mitigate climate change is on the avoidance of fossil fuel emissions. However, the Kyoto Protocol rules permit the use of forestry activities that create carbon offset credits. These could obviate the need for lifestyle-changing reductions in fossil fuel use. Therefore,

  17. 76 FR 24406 - Collection by Offset From Indebted Government Employees

    Science.gov (United States)

    2011-05-02

    ... PERSONNEL MANAGEMENT 5 CFR Part 550 RIN 3206-AM14 Collection by Offset From Indebted Government Employees... and employees. Executive Order 13563 and Executive Order 12866 The Office of Management and Budget has... Administrative practice and procedure, Claims, Government employees, Wages. U.S. Office of Personnel...

  18. Anisotropic parameter estimation using velocity variation with offset analysis

    Energy Technology Data Exchange (ETDEWEB)

    Herawati, I.; Saladin, M.; Pranowo, W.; Winardhie, S.; Priyono, A. [Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung, 40132 (Indonesia)

    2013-09-09

    Seismic anisotropy is defined as velocity dependent upon angle or offset. Knowledge about anisotropy effect on seismic data is important in amplitude analysis, stacking process and time to depth conversion. Due to this anisotropic effect, reflector can not be flattened using single velocity based on hyperbolic moveout equation. Therefore, after normal moveout correction, there will still be residual moveout that relates to velocity information. This research aims to obtain anisotropic parameters, ε and δ, using two proposed methods. The first method is called velocity variation with offset (VVO) which is based on simplification of weak anisotropy equation. In VVO method, velocity at each offset is calculated and plotted to obtain vertical velocity and parameter δ. The second method is inversion method using linear approach where vertical velocity, δ, and ε is estimated simultaneously. Both methods are tested on synthetic models using ray-tracing forward modelling. Results show that δ value can be estimated appropriately using both methods. Meanwhile, inversion based method give better estimation for obtaining ε value. This study shows that estimation on anisotropic parameters rely on the accuracy of normal moveout velocity, residual moveout and offset to angle transformation.

  19. Occupational cobalt and chromium dermatitis in an offset printing factory.

    Science.gov (United States)

    Spruit, D; Malten, K E

    1975-01-01

    A case history of three offset printers and the atomic absorption analysis of their contact materials is described. Though the factory direction and personnel felt strongly about cooperating in order to combat the disease, it became apparent that the prescribed measures had not been effectively carried out. The chemical analysis of the materials proved to be a necessary supplement to the patch testing procedure.

  20. A Meta-Regression Analysis of Forest Carbon Offset Costs

    NARCIS (Netherlands)

    Kooten, van G.C.; Laaksonen-Craig, S.; Wang, Y.

    2009-01-01

    The main focus of efforts to mitigate climate change is on the avoidance of fossil fuel emissions. However, the Kyoto Protocol rules permit the use of forestry activities that create carbon offset credits. These could obviate the need for lifestyle-changing reductions in fossil fuel use. Therefore,