WorldWideScience

Sample records for ultrastable lasers based

  1. An ultra-stable iodine-based frequency reference for space applications

    Science.gov (United States)

    Schuldt, Thilo; Braxmaier, Claus; Doeringshoff, Klaus; Keetman, Anja; Reggentin, Matthias; Kovalchuk, Evgeny; Peters, Achim

    2012-07-01

    Future space missions require for ultra-stable optical frequency references. Examples are the gravitational wave detector LISA/eLISA (Laser Interferometer Space Antenna), the SpaceTime Asymmetry Research (STAR) program, the aperture-synthesis telescope Darwin and the GRACE (Gravity Recovery and Climate Experiment) follow on mission exploring Earth's gravity. As high long-term frequency stability is required, lasers stabilized to atomic or molecular transitions are preferred, also offering an absolute frequency reference. Frequency stabilities in the 10 ^{-15} domains at longer integration times (up to several hours) are demonstrated in laboratory experiments using setups based on Doppler-free spectroscopy. Such setups with a frequency stability comparable to the hydrogen maser in the microwave domain, have the potential to be developed space compatible on a relatively short time scale. Here, we present the development of ultra-stable optical frequency references based on modulation-transfer spectroscopy of molecular iodine. Noise levels of 2\\cdot10 ^{-14} at an integration time of 1 s and below 3\\cdot10 ^{-15} at integration times between 100 s and 1000 s are demonstrated with a laboratory setup using an 80 cm long iodine cell in single-pass configuration in combination with a frequency-doubled Nd:YAG laser and standard optical components and optomechanic mounts. The frequency stability at longer integration times is (amongst other things) limited by the dimensional stability of the optical setup, i.e. by th pointing stability of the two counter-propagating beams overlapped in the iodine cell. With the goal of a future space compatible setup, a compact frequency standard on EBB (elegant breadboard) level was realized. The spectroscopy unit utilizes a baseplate made of Clearceram-HS, a glass ceramics with an ultra-low coefficient of thermal expansion of 2\\cdot10 ^{-8} K ^{-1}. The optical components are joint to the baseplate using adhesive bonding technology

  2. Light-Independent Ionic Transport in Inorganic Perovskite and Ultrastable Cs-Based Perovskite Solar Cells.

    Science.gov (United States)

    Zhou, Wenke; Zhao, Yicheng; Zhou, Xu; Fu, Rui; Li, Qi; Zhao, Yao; Liu, Kaihui; Yu, Dapeng; Zhao, Qing

    2017-09-07

    Due to light-induced effects in CH 3 NH 3 -based perovskites, such as ion migration, defects formation, and halide segregation, the degradation of CH 3 NH 3 -based perovskite solar cells under maximum power point is generally implicated. Here we demonstrated that the effect of light-enhanced ion migration in CH 3 NH 3 PbI 3 can be eliminated by inorganic Cs substitution, leading to an ultrastable perovskite solar cell. Quantitatively, the ion migration barrier for CH 3 NH 3 PbI 3 is 0.62 eV under dark conditions, larger than that of CsPbI 2 Br (0.45 eV); however, it reduces to 0.07 eV for CH 3 NH 3 PbI 3 under illumination, smaller than that for CsPbI 2 Br (0.43 eV). Meanwhile, photoinduced halide segregation is also suppressed in Cs-based perovskites. Cs-based perovskite solar cells retained >99% of the initial efficiency (10.3%) after 1500 h of maximum power point tracking under AM1.5G illumination, while CH 3 NH 3 PbI 3 solar cells degraded severely after 50 h of operation. Our work reveals an uncovered mechanism for stability improvement by inorganic cation substitution in perovskite-based optoelectronic devices.

  3. Scientific methods for developing ultrastable structures

    International Nuclear Information System (INIS)

    Gamble, M.; Thompson, T.; Miller, W.

    1990-01-01

    Scientific methods used by the Los Alamos National Laboratory for developing an ultrastable structure for study of silicon-based elementary particle tracking systems are addressed. In particular, the design, analysis, and monitoring of this system are explored. The development methodology was based on a triad of analytical, computational, and experimental techniques. These were used to achieve a significant degree of mechanical stability (alignment accuracy >1 μrad) and yet allow dynamic manipulation of the system. Estimates of system thermal and vibratory stability and component performance are compared with experimental data collected using laser interferometry and accelerometers. 8 refs., 5 figs., 4 tabs

  4. Ultra-Stable, New Generation Q-Switched Monolithic Laser Cleaners for Fine Art Conservation

    Science.gov (United States)

    Brioschi, F.; Salvadeo, P.

    The increasing use of laser cleaners in fine art conservation boosts the demand on improvements of the laser performances. More power and more wavelengths are required by the current applications, while laser should be more reliable, rugged and compact. The characteristics and performances of a new generation of laser cleaners are presented as a result of a dedicated research and development program.

  5. Long Term Ultrastable Laser System at 780 nm for Atomic Clocks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gener8 and AOSense team together to propose a novel new architecture for a low-phase noise, single-frequency electronically tunable laser at 780 nm. This laser...

  6. A compact, robust, and transportable ultra-stable laser with a fractional frequency instability of 1 × 10{sup −15}

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qun-Feng; Nevsky, Alexander; Cardace, Marco; Schiller, Stephan, E-mail: Step.Schiller@uni-duesseldorf.de [Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf (Germany); Legero, Thomas; Häfner, Sebastian; Uhde, Andre; Sterr, Uwe [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany)

    2014-11-15

    We present a compact and robust transportable ultra-stable laser system with minimum fractional frequency instability of 1 × 10{sup −15} at integration times between 1 and 10 s. The system was conceived as a prototype of a subsystem of a microwave-optical local oscillator to be used on the satellite mission Space-Time Explorer and QUantum Equivalence Principle Space Test (STE-QUEST) ( http://sci.esa.int/ste-quest/ ). It was therefore designed to be compact, to sustain accelerations occurring during rocket launch, to exhibit low vibration sensitivity, and to reach a low frequency instability. Overall dimensions of the optical system are 40 cm × 20 cm × 30 cm. The acceleration sensitivities of the optical frequency in the three directions were measured to be 1.7 × 10{sup −11}/g, 8.0 × 10{sup −11}/g, and 3.9 × 10{sup −10}/g, and the absolute frequency instability was determined via a three-cornered hat measurement. Two additional cavity-stabilized lasers were used for this purpose, one of which had an instability σ{sub y} < 4 × 10{sup −16} at 1 s integration time. The design is also appropriate and useful for terrestrial applications.

  7. Self-Powered Wireless Smart Sensor Node Enabled by an Ultrastable, Highly Efficient, and Superhydrophobic-Surface-Based Triboelectric Nanogenerator.

    Science.gov (United States)

    Zhao, Kun; Wang, Zhong Lin; Yang, Ya

    2016-09-27

    Wireless sensor networks will be responsible for a majority of the fast growth in intelligent systems in the next decade. However, most of the wireless smart sensor nodes require an external power source such as a Li-ion battery, where the labor cost and environmental waste issues of replacing batteries have largely limited the practical applications. Instead of using a Li-ion battery, we report an ultrastable, highly efficient, and superhydrophobic-surface-based triboelectric nanogenerator (TENG) to scavenge wind energy for sustainably powering a wireless smart temperature sensor node. There is no decrease in the output voltage and current of the TENG after continuous working for about 14 h at a wind speed of 12 m/s. Through a power management circuit, the TENG can deliver a constant output voltage of 3.3 V and a pulsed output current of about 100 mA to achieve highly efficient energy storage in a capacitor. A wireless smart temperature sensor node can be sustainably powered by the TENG for sending the real-time temperature data to an iPhone under a working distance of 26 m, demonstrating the feasibility of the self-powered wireless smart sensor networks.

  8. FROM STABLE LASERS TO OPTICAL-FREQUENCY CLOCKS:. Merging the UltraFast and the UltraStable, for a New Epoch of Optical Frequency Measurements, Standards, & Applications

    Science.gov (United States)

    Hall, J. L.; Ye, J.; Ma, L.-S.; Peng, J.-L.; Notcutt, M.; Jost, J. D.; Marian, A.

    2002-04-01

    This is a report on behalf of the World Team of Stable Laser and Optical Frequency Measurement Enthusiasts, even if most detailed illustrations draw mainly from our work at JILA. Specifically we trace some of the key ideas that have led from the first stabilized lasers, to frequency measurement up to 88 THz using frequency chains, revision of the Definition of the Metre, extension of coherent frequency chain technology into the visible, development of a vast array of stabilized lasers, and finally the recent explosive growth of direct frequency measurement capability in the visible using fs comb techniques. We present our recent work showing a Molecular Iodine-based Optical Clock which delivers, over a range of time scales, rf output at a stability level basically equivalent to the RF stability prototype, the Hydrogen Maser. We note the bifurcation between single-ion-based clocks - likely to be the stability/reproducibility ultimate winners in the next generation - and simpler systems based on gas cells, which can have impressive stabilities but may suffer from a variety of reproducibility-limiting processes. Active Phase-Lock synchronization of independent fs lasers allows sub-fs timing control. Copies of related works in our labs may be found/obtained at our website .

  9. Zwitterionic Silane Copolymer for Ultra-Stable and Bright Biomolecular Probes Based on Fluorescent Quantum Dot Nanoclusters.

    Science.gov (United States)

    Dembele, Fatimata; Tasso, Mariana; Trapiella-Alfonso, Laura; Xu, Xiangzhen; Hanafi, Mohamed; Lequeux, Nicolas; Pons, Thomas

    2017-05-31

    Fluorescent semiconductor quantum dots (QDs) exhibit several unique properties that make them suitable candidates for biomolecular sensing, including high brightness, photostability, broad excitation, and narrow emission spectra. Assembling these QDs into robust and functionalizable nanosized clusters (QD-NSCs) can provide fluorescent probes that are several orders of magnitude brighter than individual QDs, thus allowing an even greater sensitivity of detection with simplified instrumentation. However, the formation of compact, antifouling, functionalizable, and stable QD-NSCs remains a challenging task, especially for a use at ultralow concentrations for single-molecule detection. Here, we describe the development of fluorescent QD-NSCs envisioned as a tool for fast and sensitive biomolecular recognition. First, QDs were assembled into very compact 100-150 nm diameter spherical aggregates; the final QD-NSCs were obtained by growing a cross-linked silica shell around these aggregates. Hydrolytic stability in several concentration and pH conditions is a key requirement for a potential and efficient single-molecule detection tool. However, the hydrolysis of Si-O-Si bonds leads to desorption of monosilane-based surface groups at very low silica concentrations or in a slightly basic medium. Thus, we designed a novel multidentate copolymer composed of multiple silane as well as zwitterionic monomers. Coating silica beads with this multidentate copolymer provided a robust surface chemistry that was demonstrated to be stable against hydrolysis, even at low concentrations. Copolymer-coated silica beads also showed low fouling properties and high colloidal stability in saline solutions. Furthermore, incorporation of additional azido-monomers enabled easy functionalization of QD-NSCs using copper-free bio-orthogonal cyclooctyne-azide click chemistry, as demonstrated by a biotin-streptavidin affinity test.

  10. Arduino based laser control

    OpenAIRE

    Bernal Muñoz, Ferran

    2015-01-01

    ARDUINO is a vey usefull platform for prototypes. In this project ARDUINO will be used for controling a Semiconductor Tuneable Laser. [ANGLÈS] Diode laser for communications control based on an Arduino board. Temperature control implementation. Software and hardware protection for the laser implementation. [CASTELLÀ] Control de un láser de comunicaciones ópticas desde el ordenador utilizando una placa Arduino. Implementación de un control de temperatura y protección software y hardware ...

  11. A study of ultra-stable optical clocks, frequency sources and standards for space applications

    International Nuclear Information System (INIS)

    Klein, H.A.; Knight, D.J.E.

    1999-01-01

    Optical or laser-based communication systems are expected to supplement microwave based systems for satellite-to-satellite and spacecraft-to-satellite communications early in the next millennium. Optical systems can carry far more traffic than microwave and address the need to increase communication bandwidths to meet the demands of commerce and the entertainment industry. There is already significant research and commercial interest in this area (now driven particularly by the multi-media and Internet services delivery sector) and there is a strong need to establish which are the best choices of optical sources to develop for space based optical communications. In addition to communication requirements there are strong arguments for developing ultra-stable optical frequency sources and detectors in space for at least two other purposes. At present the microwave radiation that is used for communications is also used for other purposes, for example navigation or tracking, and 'space science' experiments. With the switch from the microwave to the optical for communications it may well be convenient to switch to the optical for these and other functions. This study has examined the potential stable laser requirements for a range of space applications. An interim report was presented in the form of a conference paper summarising our initial findings (see Appendix 5). This final report gives our conclusions in more detail and recommends areas for further study

  12. Exploring ultrastability in nanostructured glassy polymer films by fast-scanning calorimetry.

    Science.gov (United States)

    Chowdhury, Mithun; Wang, Yucheng; Jeong, Hyuncheol; Cangialosi, Daniele; Priestley, Rodney

    A decade ago ultra-stable small molecule glass formers were discovered. Since then a significant amount of research has been devoted to traverse down the energy landscape of such glass formers via physical vapor deposition (PVD). Matrix assisted pulsed laser evaporation (MAPLE) has the known ability to produce vapour deposited nanostructured polymer glass with exceptional kinetic stability. We explored the role of deposition temperature/ growth rate on thermodynamic and kinetic stabilities of poly (methyl methacrylate) (PMMA) films, deposited over a fast-scanning calorimetry sensor. We found in general any MAPLE deposited glass is kinetically more stable than bulk polymer and its spin-coated film. Moreover slow growth rate and optimum temperature during MAPLE deposition can additionally lead to thermodynamically stable (low-energy) glass. The role of interfaces formed through dramatic nanostructuring and packing of nanoglobules (removal of void space) may have additional role on such ultrastability. NSF-MRSEC through PCCM (Grant: DMR-1420541).

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

    Science.gov (United States)

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

    2012-10-08

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

  14. Ultrastable, high efficiency picosecond green light generation using K3B6O10Br series nonlinear optical crystals

    Science.gov (United States)

    Hou, Z. Y.; Xia, M. J.; Wang, L. R.; Xu, B.; Yan, D. X.; Meng, L. P.; Liu, L. J.; Xu, D. G.; Zhang, L.; Wang, X. Y.; Li, R. K.; Chen, C. T.

    2017-09-01

    Two perovskite-structure K3B6O10Br1-x Cl x (x  =  0 and 0.5) series nonlinear optical crystals were thoroughly investigated for their picosecond 532 nm laser pulses abilities and high power outputs were achieved via second harmonic generation (SHG) technique for the first time. SHG conversion efficiency of 57.3% with a 13.2 mm length K3B6O10Br (KBB) crystal was achieved using a laser source of pulse repetition rate of 10 Hz and pulse width of 25 ps, which is the highest conversion efficiency of ps visible laser based on KBB crystal. And by employing an 80 MHz, 10 ps fundamental laser beam, maximum power outputs of 12 W with K3B6O10Br0.5Cl0.5 (KBBC) and 11.86 W with KBB crystals were successfully demonstrated. Furthermore, the standard deviation jitters of the average power outputs are less than 0.6% and 1.17% by KBB and KBBC, respectively, showing ultrastable power stabilities favorable for practical applications. In addition, the other optical parameters including acceptance angle and temperature bandwidth were also investigated.

  15. Remote transfer of ultrastable frequency references via fiber networks

    International Nuclear Information System (INIS)

    Foreman, Seth M.; Holman, Kevin W.; Hudson, Darren D.; Jones, David J.; Ye, Jun

    2007-01-01

    Three distinct techniques exist for distributing an ultrastable frequency reference over optical fibers. For the distribution of a microwave frequency reference, an amplitude-modulated continuous wave (cw) laser can be used. Over kilometer-scale lengths this approach provides an instability at 1 s of ∼3x10 -14 without stabilization of the fiber-induced noise and ∼1x10 -14 with active noise cancellation. An optical frequency reference can be transferred by directly transmitting a stabilized cw laser over fiber and then disseminated to other optical and microwave regions using an optical frequency comb. This provides an instability at 1 s of 2x10 -14 without active noise cancellation and 3x10 -15 with active noise cancellation [Recent results reduce the instability at 1 s to 6x10 -18 .] Finally, microwave and optical frequency references can be simultaneously transmitted using an optical frequency comb, and we expect the optical transfer to be similar in performance to the cw optical frequency transfer. The instability at 1 s for transfer of a microwave frequency reference with the comb is ∼3x10 -14 without active noise cancellation and -15 with active stabilization. The comb can also distribute a microwave frequency reference with root-mean-square timing jitter below 16 fs integrated over the Nyquist bandwidth of the pulse train (∼50 MHz) when high-bandwidth active noise cancellation is employed, which is important for remote synchronization applications

  16. An ultrastable Michelson interferometer for high-resolution spectroscopy in the XUV.

    Science.gov (United States)

    Corsi, C; Liontos, I; Cavalieri, S; Bellini, M; Venturi, G; Eramo, R

    2015-02-23

    We developed an ultra-stable and accurately-controllable Michelson interferometer to be used in a deeply unbalanced arm configuration for split-pulse XUV Ramsey-type spectroscopy with high-order laser harmonics. The implemented active and passive stabilization systems allow one to reach instabilities in the nanometer range over meters of relative optical path differences. Producing precisely delayed pairs of pump pulses will generate XUV harmonic pulses that may significantly improve the achievable spectral resolution and the precision of absolute frequency measurements in the XUV.

  17. Laser-based additive manufacturing of metals

    CSIR Research Space (South Africa)

    Kumar, S

    2010-11-01

    Full Text Available For making metallic products through Additive Manufacturing (AM) processes, laser-based systems play very significant roles. Laser-based processes such as Selective Laser Melting (SLM) and Laser Engineered Net Shaping (LENS) are dominating processes...

  18. Laser-powered lunar base

    International Nuclear Information System (INIS)

    Costen, R.; Humes, D.H.; Walker, G.H.; Williams, M.D.; Deyoung, R.J.

    1989-01-01

    The objective was to compare a nuclear reactor-driven Sterling engine lunar base power source to a laser-to-electric converter with orbiting laser power station, each providing 1 MW of electricity to the lunar base. The comparison was made on the basis of total mass required in low-Earth-orbit for each system. This total mass includes transportation mass required to place systems in low-lunar orbit or on the lunar surface. The nuclear reactor with Sterling engines is considered the reference mission for lunar base power and is described first. The details of the laser-to-electric converter and mass are discussed. The next two solar-driven high-power laser concepts, the diode array laser or the iodine laser system, are discussed with associated masses in low-lunar-orbit. Finally, the payoff for laser-power beaming is summarized

  19. An Ultrastable and High-Performance Flexible Fiber-Shaped Ni-Zn Battery based on a Ni-NiO Heterostructured Nanosheet Cathode.

    Science.gov (United States)

    Zeng, Yinxiang; Meng, Yue; Lai, Zhengzhe; Zhang, Xiyue; Yu, Minghao; Fang, Pingping; Wu, Mingmei; Tong, Yexiang; Lu, Xihong

    2017-11-01

    Currently, the main bottleneck for the widespread application of Ni-Zn batteries is their poor cycling stability as a result of the irreversibility of the Ni-based cathode and dendrite formation of the Zn anode during the charging-discharging processes. Herein, a highly rechargeable, flexible, fiber-shaped Ni-Zn battery with impressive electrochemical performance is rationally demonstrated by employing Ni-NiO heterostructured nanosheets as the cathode. Benefiting from the improved conductivity and enhanced electroactivity of the Ni-NiO heterojunction nanosheet cathode, the as-fabricated fiber-shaped Ni-NiO//Zn battery displays high capacity and admirable rate capability. More importantly, this Ni-NiO//Zn battery shows unprecedented cyclic durability both in aqueous (96.6% capacity retention after 10 000 cycles) and polymer (almost no capacity attenuation after 10 000 cycles at 22.2 A g -1 ) electrolytes. Moreover, a peak energy density of 6.6 µWh cm -2 , together with a remarkable power density of 20.2 mW cm -2 , is achieved by the flexible quasi-solid-state fiber-shaped Ni-NiO//Zn battery, outperforming most reported fiber-shaped energy-storage devices. Such a novel concept of a fiber-shaped Ni-Zn battery with impressive stability will greatly enrich the flexible energy-storage technologies for future portable/wearable electronic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. CsPbBr3 Perovskite Quantum Dots-Based Monolithic Electrospun Fiber Membrane as an Ultrastable and Ultrasensitive Fluorescent Sensor in Aqueous Medium.

    Science.gov (United States)

    Wang, Yuanwei; Zhu, Yihua; Huang, Jianfei; Cai, Jin; Zhu, Jingrun; Yang, Xiaoling; Shen, Jianhua; Jiang, Hao; Li, Chunzhong

    2016-11-03

    Perovskite quantum dots with excellent optical properties and robust durability stand as an appealing and desirable candidate for fluorescence resonance energy transfer (FRET) based fluorescence detection, a powerful technique featuring excellent accuracy and convenience. In this work, a monolithic superhydrophobic polystyrene fiber membrane with CsPbBr 3 perovskite quantum dots encapsulated within (CPBQDs/PS FM) was prepared via one-step electrospinning. Coupling CPBQDs with PS matrix, this CPBQDs/PS FM composite exhibits high quantum yields (∼91%), narrow half-peak width (∼16 nm), nearly 100% fluorescence retention after being exposed to water for 10 days and 79.80% fluorescence retention after 365 nm UV-light (1 mW/cm 2 ) illumination for 60 h. Thanks to the outstanding optical property of CPBQDs, an ultralow detection limit of 0.01 ppm was obtained for Rhodamine 6G (R6G) detection, with the FRET efficiency calculated to be 18.80% in 1 ppm R6G aqueous solution. Electrospun as well-designed fiber membranes, CPBQDs/PS FM composite also possesses good tailorability and recyclability, showing exciting potential for future implementation into practical applications.

  1. An ultra-stable optical frequency reference for space

    Science.gov (United States)

    Schuldt, T.; Döringshoff, K.; Kovalchuk, E.; Pahl, J.; Gohlke, M.; Weise, D.; Johann, U.; Peters, A.; Braxmaier, C.

    2017-11-01

    We realized ultra-stable optical frequency references on elegant breadboard (EBB) and engineering model (EM) level utilizing Doppler-free spectroscopy of molecular iodine near 532nm. A frequency stability of about 1•10-14 at an integration time of 1 s and below 5•10-15 at integration times between 10 s and 100 s was achieved. These values are comparable to the currently best laboratory setups. Both setups use a baseplate made of glass material where the optical components are joint using a specific assembly-integration technology. Compared to the EBB setup, the EM setup is further developed with respect to compactness and mechanical and thermal stability. The EM setup uses a baseplate made of fused silica with dimensions of 380 x 180 x 40 mm3 and a specifically designed 100 x 100 x 30 mm3 rectangular iodine cell in nine-pass configuration with a specific robust cold finger design. The EM setup was subjected to thermal cycling and vibrational testing. Applications of such an optical frequency reference in space can be found in fundamental physics, geoscience, Earth observation, and navigation & ranging. One example is the proposed mSTAR (mini SpaceTime Asymmetry Research) mission, dedicated to perform a Kennedy-Thorndike experiment on a satellite in a sunsynchronous low-Earth orbit. By comparing an iodine standard to a cavity-based frequency reference and integration over 2 year mission lifetime, the Kennedy-Thorndike coefficient will be determined with up to two orders of magnitude higher accuracy than the current best ground experiment. In a current study, the compatibility of the payload with the SaudiSat-4 host vehicle is investigated.

  2. Design of ultra-stable insulin analogues for the developing world

    Directory of Open Access Journals (Sweden)

    Michael A Weiss

    2013-01-01

    Full Text Available The engineering of insulin analogues illustrates the application of structure-based protein design to clinical medicine. Such design has traditionally been based on structures of wild-type insulin hexamers in an effort to optimize the pharmacokinetic (PK and pharmacodynamic properties of the hormone. Rapid-acting insulin analogues (in chronological order of their clinical introduction, Humalog ® [Eli Lilly & Co.], Novolog ® [Novo-Nordisk], and Apidra ® [Sanofi-Aventis] exploit the targeted destabilization of subunit interfaces to facilitate capillary absorption. Conversely, long-acting insulin analogues exploit the stability of the insulin hexamer and its higher-order self-assembly within the subcutaneous depot to enhance basal glycemic control. Current products either operate through isoelectric precipitation (insulin glargine, the active component of Lantus ® ; Sanofi-Aventis or employ an albumin-binding acyl tether (insulin detemir, the active component of Levemir ® ; Novo-Nordisk. Such molecular engineering has often encountered a trade-off between PK goals and product stability. Given the global dimensions of the diabetes pandemic and complexity of an associated cold chain of insulin distribution, we envisage that concurrent engineering of ultra-stable protein analogue formulations would benefit the developing world, especially for patients exposed to high temperatures with inconsistent access to refrigeration. We review the principal mechanisms of insulin degradation above room temperature and novel molecular approaches toward the design of ultra-stable rapid-acting and basal formulations.

  3. Recent progress in the performances of ultrastable quartz resonators and oscillators

    Directory of Open Access Journals (Sweden)

    Salzenstein Patrice

    2016-01-01

    Full Text Available Stressed compensated (SC cut led recently to the best frequency stability ever obtained with a quartz oscillator, 2.5 × 10−14 for the flicker frequency modulation (FFM floor. This result is confirmed in this paper with a 3.2 × 10−14 ± 1.1 × 10−14. The quartz resonator is integrated in a 5 MHz enhanced aging box double oven controlled oscillator. After reminding a bit of history, this paper describes how the first significant development in terms of ultra-stable quartz state-of-the-art oscillators was performed in the last 20 years, how the resonators were chosen, and main information about the development of adequate electronics and how to mechanically and thermally stabilized such an ultra-stable oscillator. We also present how to characterize the expected performances, and hot topics in quartz based oscillators.

  4. Laser Spot Detection Based on Reaction Diffusion

    OpenAIRE

    Alejandro Vázquez-Otero; Danila Khikhlukha; J. M. Solano-Altamirano; Raquel Dormido; Natividad Duro

    2016-01-01

    Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presente...

  5. Waveguide based external cavity semiconductor lasers

    NARCIS (Netherlands)

    Oldenbeuving, Ruud; Klein, E.J.; Offerhaus, Herman L.; Lee, Christopher James; Verhaegen, M.; Boller, Klaus J.

    2012-01-01

    We report on progress of the project waveguide based external cavity semiconductor laser (WECSL) arrays. Here we present the latest results on our efforts to mode lock an array of tunable, external cavity semiconductor lasers.

  6. Laser-based coatings removal

    International Nuclear Information System (INIS)

    Freiwald, J.G.; Freiwald, D.A.

    1995-01-01

    Over the years as building and equipment surfaces became contaminated with low levels of uranium or plutonium dust, coats of paint were applied to stabilize the contaminants in place. Most of the earlier paint used was lead-based paint. More recently, various non-lead-based paints, such as two-part epoxy, are used. For D ampersand D (decontamination and decommissioning), it is desirable to remove the paints or other coatings rather than having to tear down and dispose of the entire building. This report describes the use of pulse-repetetion laser systems for the removal of paints and coatings

  7. Laser-based coatings removal

    Energy Technology Data Exchange (ETDEWEB)

    Freiwald, J.G.; Freiwald, D.A. [F2 Associates, Inc., Albuquerque, NM (United States)

    1995-10-01

    Over the years as building and equipment surfaces became contaminated with low levels of uranium or plutonium dust, coats of paint were applied to stabilize the contaminants in place. Most of the earlier paint used was lead-based paint. More recently, various non-lead-based paints, such as two-part epoxy, are used. For D&D (decontamination and decommissioning), it is desirable to remove the paints or other coatings rather than having to tear down and dispose of the entire building. This report describes the use of pulse-repetetion laser systems for the removal of paints and coatings.

  8. Compact laser-diode-based femtosecond sources

    International Nuclear Information System (INIS)

    Brown, C T A; Cataluna, M A; Lagatsky, A A; Rafailov, E U; Agate, M B; Leburn, C G; Sibbett, W

    2004-01-01

    This paper describes the development of compact femtosecond laser systems that are capable of being directly pumped by laser diodes or are based directly on laser diodes. The paper demonstrates the latest results in a highly efficient vibronic based gain medium and a diode-pumped Yb:KYW laser is reported that has a wall plug efficiency >14%. A Cr 4+ :YAG oscillator is described that generates transform-limited pulses of 81 fs duration at a pulse repetition frequency of >4 GHz. The development of Cr 3+ :LiSAF lasers that can be operated using power supplies based on batteries is briefly discussed. We also present a summary of work being carried out on the generation of fs-pulses from laser diodes and discuss the important issues in this area. Finally, we outline results obtained on the generation of pulses as short as 550 fs directly from a two-section quantum dot laser without any external pulse compression

  9. Laser-based optical detection of explosives

    CERN Document Server

    Pellegrino, Paul M; Farrell, Mikella E

    2015-01-01

    Laser-Based Optical Detection of Explosives offers a comprehensive review of past, present, and emerging laser-based methods for the detection of a variety of explosives. This book: Considers laser propagation safety and explains standard test material preparation for standoff optical-based detection system evaluation Explores explosives detection using deep ultraviolet native fluorescence, Raman spectroscopy, laser-induced breakdown spectroscopy, reflectometry, and hyperspectral imaging Examines photodissociation followed by laser-induced fluorescence, photothermal methods, cavity-enhanced absorption spectrometry, and short-pulse laser-based techniques Describes the detection and recognition of explosives using terahertz-frequency spectroscopic techniques Each chapter is authored by a leading expert on the respective technology, and is structured to supply historical perspective, address current advantages and challenges, and discuss novel research and applications. Readers are left with an in-depth understa...

  10. Laser Spot Detection Based on Reaction Diffusion.

    Science.gov (United States)

    Vázquez-Otero, Alejandro; Khikhlukha, Danila; Solano-Altamirano, J M; Dormido, Raquel; Duro, Natividad

    2016-03-01

    Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

  11. Laser Spot Detection Based on Reaction Diffusion

    Directory of Open Access Journals (Sweden)

    Alejandro Vázquez-Otero

    2016-03-01

    Full Text Available Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

  12. Satellite-based laser windsounder

    International Nuclear Information System (INIS)

    Schultz, J.F.; Czuchlewski, S.J.; Quick, C.R.

    1997-01-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project''s primary objective is to determine the technical feasibility of using satellite-based laser wind sensing systems for detailed study of winds, aerosols, and particulates around and downstream of suspected proliferation facilities. Extensive interactions with the relevant operational organization resulted in enthusiastic support and useful guidance with respect to measurement requirements and priorities. Four candidate wind sensing techniques were evaluated, and the incoherent Doppler technique was selected. A small satellite concept design study was completed to identify the technical issues inherent in a proof-of-concept small satellite mission. Use of a Mach-Zehnder interferometer instead of a Fabry-Perot would significantly simplify the optical train and could reduce weight, and possibly power, requirements with no loss of performance. A breadboard Mach-Zehnder interferometer-based system has been built to verify these predictions. Detailed plans were made for resolving other issues through construction and testing of a ground-based lidar system in collaboration with the University of Wisconsin, and through numerical lidar wind data assimilation studies

  13. Laser based refurbishment of steel mill components

    CSIR Research Space (South Africa)

    Kazadi, P

    2006-03-01

    Full Text Available Laser refurbishment capabilities were demonstrated and promising results were obtained for repair of distance sleeves, foot rolls, descaler cassette, idler rolls. Based on the cost projections and the results of the in-situ testing, components which...

  14. Frequency stabilization of an optically pumped far-infrared laser to the harmonic of a microwave synthesizer.

    Science.gov (United States)

    Danylov, A A; Light, A R; Waldman, J; Erickson, N

    2015-12-10

    Measurements of the frequency stability of a far-infrared molecular laser have been made by mixing the harmonic of an ultrastable microwave source with a portion of the laser output signal in a terahertz (THz) Schottky diode balanced mixer. A 3 GHz difference-frequency signal was used in a frequency discriminator circuit to lock the laser to the microwave source. Comparisons of the short- and long-term laser frequency stability under free-running and locked conditions show a significant improvement with locking. Short-term frequency jitter was reduced by an order of magnitude, from approximately 40 to 4 kHz, and long-term drift was reduced by more than three orders of magnitude, from approximately 250 kHz to 80 Hz. The results, enabled by the efficient Schottky diode balanced mixer downconverter, demonstrate that ultrastable microwave-based frequency stabilization of THz optically pumped lasers (OPLs) will now be possible at frequencies extending well above 4.0 THz.

  15. Laser apparatus for surgery and force therapy based on high-power semiconductor and fibre lasers

    International Nuclear Information System (INIS)

    Minaev, V P

    2005-01-01

    High-power semiconductor lasers and diode-pumped lasers are considered whose development qualitatively improved the characteristics of laser apparatus for surgery and force therapy, extended the scope of their applications in clinical practice, and enhanced the efficiency of medical treatment based on the use of these lasers. The characteristics of domestic apparatus are presented and their properties related to the laser emission wavelength used in them are discussed. Examples of modern medical technologies based on these lasers are considered. (invited paper)

  16. Process observation in fiber laser-based selective laser melting

    Science.gov (United States)

    Thombansen, Ulrich; Gatej, Alexander; Pereira, Milton

    2015-01-01

    The process observation in selective laser melting (SLM) focuses on observing the interaction point where the powder is processed. To provide process relevant information, signals have to be acquired that are resolved in both time and space. Especially in high-power SLM, where more than 1 kW of laser power is used, processing speeds of several meters per second are required for a high-quality processing results. Therefore, an implementation of a suitable process observation system has to acquire a large amount of spatially resolved data at low sampling speeds or it has to restrict the acquisition to a predefined area at a high sampling speed. In any case, it is vitally important to synchronously record the laser beam position and the acquired signal. This is a prerequisite that allows the recorded data become information. Today, most SLM systems employ f-theta lenses to focus the processing laser beam onto the powder bed. This report describes the drawbacks that result for process observation and suggests a variable retro-focus system which solves these issues. The beam quality of fiber lasers delivers the processing laser beam to the powder bed at relevant focus diameters, which is a key prerequisite for this solution to be viable. The optical train we present here couples the processing laser beam and the process observation coaxially, ensuring consistent alignment of interaction zone and observed area. With respect to signal processing, we have developed a solution that synchronously acquires signals from a pyrometer and the position of the laser beam by sampling the data with a field programmable gate array. The relevance of the acquired signals has been validated by the scanning of a sample filament. Experiments with grooved samples show a correlation between different powder thicknesses and the acquired signals at relevant processing parameters. This basic work takes a first step toward self-optimization of the manufacturing process in SLM. It enables the

  17. Graphene devices based on laser scribing technology

    Science.gov (United States)

    Qiao, Yan-Cong; Wei, Yu-Hong; Pang, Yu; Li, Yu-Xing; Wang, Dan-Yang; Li, Yu-Tao; Deng, Ning-Qin; Wang, Xue-Feng; Zhang, Hai-Nan; Wang, Qian; Yang, Zhen; Tao, Lu-Qi; Tian, He; Yang, Yi; Ren, Tian-Ling

    2018-04-01

    Graphene with excellent electronic, thermal, optical, and mechanical properties has great potential applications. The current devices based on graphene grown by micromechanical exfoliation, chemical vapor deposition (CVD), and thermal decomposition of silicon carbide are still expensive and inefficient. Laser scribing technology, a low-cost and time-efficient method of fabricating graphene, is introduced in this review. The patterning of graphene can be directly performed on solid and flexible substrates. Therefore, many novel devices such as strain sensors, acoustic devices, memory devices based on laser scribing graphene are fabricated. The outlook and challenges of laser scribing technology have also been discussed. Laser scribing may be a potential way of fabricating wearable and integrated graphene systems in the future.

  18. Laser-based agriculture system

    KAUST Repository

    Ooi, Boon S.

    2016-03-31

    A system and method are provided for indoor agriculture using at least one growth chamber illuminated by laser light. In an example embodiment of the agriculture system, a growth chamber is provided having one or more walls defining an interior portion of the growth chamber. The agriculture system may include a removable tray disposed within the interior portion of the growth chamber. The agriculture system also includes a light source, which may be disposed outside the growth chamber. The one or more walls may include at least one aperture. The light source is configured to illuminate at least a part of the interior portion of the growth chamber. In embodiments in which the light source is disposed outside the growth chamber, the light source is configured to transmit the laser light to the interior portion of the growth chamber via the at least one aperture.

  19. Laser-based agriculture system

    KAUST Repository

    Ooi, Boon S.; Wong, Aloysius Tze; Ng, Tien Khee

    2016-01-01

    A system and method are provided for indoor agriculture using at least one growth chamber illuminated by laser light. In an example embodiment of the agriculture system, a growth chamber is provided having one or more walls defining an interior portion of the growth chamber. The agriculture system may include a removable tray disposed within the interior portion of the growth chamber. The agriculture system also includes a light source, which may be disposed outside the growth chamber. The one or more walls may include at least one aperture. The light source is configured to illuminate at least a part of the interior portion of the growth chamber. In embodiments in which the light source is disposed outside the growth chamber, the light source is configured to transmit the laser light to the interior portion of the growth chamber via the at least one aperture.

  20. Laser based spot weld characterization

    Science.gov (United States)

    Jonietz, Florian; Myrach, Philipp; Rethmeier, Michael; Suwala, Hubert; Ziegler, Mathias

    2016-02-01

    Spot welding is one of the most important joining technologies, especially in the automotive industry. Hitherto, the quality of spot welded joints is tested mainly by random destructive tests. A nondestructive testing technique offers the benefit of cost reduction of the testing procedure and optimization of the fabrication process, because every joint could be examined. This would lead to a reduced number of spot welded joints, as redundancies could be avoided. In the procedure described here, the spot welded joint between two zinc-coated steel sheets (HX340LAD+Z100MB or HC340LA+ZE 50/50) is heated optically on one side. Laser radiation and flash light are used as heat sources. The melted zone, the so called "weld nugget" provides the mechanical stability of the connection, but also constitutes a thermal bridge between the sheets. Due to the better thermal contact, the spot welded joint reveals a thermal behavior different from the surrounding material, where the heat transfer between the two sheets is much lower. The difference in the transient thermal behavior is measured with time resolved thermography. Hence, the size of the thermal contact between the two sheets is determined, which is directly correlated to the size of the weld nugget, indicating the quality of the spot weld. The method performs well in transmission with laser radiation and flash light. With laser radiation, it works even in reflection geometry, thus offering the possibility of testing with just one-sided accessibility. By using heating with collimated laser radiation, not only contact-free, but also remote testing is feasible. A further convenience compared to similar thermographic approaches is the applicability on bare steel sheets without any optical coating for emissivity correction. For this purpose, a proper way of emissivity correction was established.

  1. Ultrastable cellulosome-adhesion complex tightens under load.

    Science.gov (United States)

    Schoeler, Constantin; Malinowska, Klara H; Bernardi, Rafael C; Milles, Lukas F; Jobst, Markus A; Durner, Ellis; Ott, Wolfgang; Fried, Daniel B; Bayer, Edward A; Schulten, Klaus; Gaub, Hermann E; Nash, Michael A

    2014-12-08

    Challenging environments have guided nature in the development of ultrastable protein complexes. Specialized bacteria produce discrete multi-component protein networks called cellulosomes to effectively digest lignocellulosic biomass. While network assembly is enabled by protein interactions with commonplace affinities, we show that certain cellulosomal ligand-receptor interactions exhibit extreme resistance to applied force. Here, we characterize the ligand-receptor complex responsible for substrate anchoring in the Ruminococcus flavefaciens cellulosome using single-molecule force spectroscopy and steered molecular dynamics simulations. The complex withstands forces of 600-750 pN, making it one of the strongest bimolecular interactions reported, equivalent to half the mechanical strength of a covalent bond. Our findings demonstrate force activation and inter-domain stabilization of the complex, and suggest that certain network components serve as mechanical effectors for maintaining network integrity. This detailed understanding of cellulosomal network components may help in the development of biocatalysts for production of fuels and chemicals from renewable plant-derived biomass.

  2. A compensated multi-pole linear ion trap mercury frequency standard for ultra-stable timekeeping.

    Science.gov (United States)

    Burt, Eric A; Diener, William A; Tjoelker, Robert L

    2008-12-01

    The multi-pole linear ion trap frequency standard (LITS) being developed at the Jet Propulsion Laboratory (JPL) has demonstrated excellent short- and long-term stability. The technology has now demonstrated long-term field operation providing a new capability for timekeeping standards. Recently implemented enhancements have resulted in a record line Q of 5 x 10(12) for a room temperature microwave atomic transition and a short-term fractional frequency stability of 5 x 10(-14)/tau(1/2). A scheme for compensating the second order Doppler shift has led to a reduction of the combined sensitivity to the primary LITS systematic effects below 5 x 10(-17) fractional frequency. Initial comparisons to JPL's cesium fountain clock show a systematic floor of less than 2 x 10(-16). The compensated multi-pole LITS at JPL was operated continuously and unattended for a 9-mo period from October 2006 to July 2007. During that time it was used as the frequency reference for the JPL geodetic receiver known as JPLT, enabling comparisons to any clock used as a reference for an International GNSS Service (IGS) site. Comparisons with the laser-cooled primary frequency standards that reported to the Bureau International des Poids et Mesures (BIPM) over this period show a frequency deviation less than 2.7 x 10(-17)/day. In the capacity of a stand-alone ultra-stable flywheel, such a standard could be invaluable for long-term timekeeping applications in metrology labs while its methodology and robustness make it ideal for space applications as well.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  4. Verification of a characterization method of the laser-induced selective activation based on industrial lasers

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Tang, Peter T.

    2013-01-01

    In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser......-machined surfaces, normalized bearing area curves and parameters are used to characterize the surface quantitatively. The range of normalized bearing area curve parameters for plate-able surface is suggested. PBT/PET with 40 % glass fiber was used as the substrate material. For all of the studied lasers......, the parameters were varied in a relatively large range, and matrixes of the laser-machined surface were obtained. The topography of those laser-machined surfaces was examined by scanning electronic microscope (SEM). For each sample examined by SEM, there was an identical workpiece plated by for 90 min...

  5. Laser-induced cavitation based micropump

    NARCIS (Netherlands)

    Dijkink, R.J.; Ohl, C.D.

    2008-01-01

    Lab-on-a-chip devices are in strong demand as versatile and robust pumping techniques. Here, we present a cavitation based technique, which is able to pump a volume of 4000 m3 within 75 s against an estimated pressure head of 3 bar. The single cavitation event is created by focusing a laser pulse in

  6. MBE System for Antimonide Based Semiconductor Lasers

    National Research Council Canada - National Science Library

    Lester, Luke

    1999-01-01

    .... SLR-770 inductively coupled plasma (ICP) processing system. The SLR-770 has been invaluable in the study of plasma etching of AlGaAsSb and GaSb-materials that form the backbone of antimonide-based semiconductor lasers...

  7. Influence of laser frequency noise on scanning Fabry-Perot interferometer based laser Doppler velocimetry

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2014-01-01

    n this work, we study the performance of a scanning Fabry-Perot interferometer based laser Doppler velocimeter (sFPILDV) and compare two candidate 1.5 um single-frequency laser sources for the system – a fiber laser (FL) and a semiconductor laser (SL). We describe a straightforward calibration...... procedure for the sFPI-LDV and investigate the effect of different degrees of laser frequency noise between the FL and the SL on the velocimeter’s performance...

  8. LIGHT: Towards a laser-based accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Busold, Simon; Deppert, Oliver; Roth, Markus [Technical University of Darmstadt, Institute for Nuclear Physics, Schlossgartenstrasse 9, 64289 Darmstadt (Germany); Brabetz, Christian [Goethe University Frankfurt am Main, Institute for Applied Physics, Max von Laue Strasse 1, 60438 Frankfurt (Germany); Burris-Mog, Trevor; Joost, Martin; Cowan, Tom [Helmholtz Center Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden (Germany); Blazevic, Abel; Bagnoud, Vincent [GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Zielbauer, Bernhard [GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Helmholtz Institute Jena, Helmholtzweg 4, 07743 Jena (Germany); Kester, Oliver [GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Goethe University Frankfurt am Main, Institute for Applied Physics, Max von Laue Strasse 1, 60438 Frankfurt (Germany)

    2012-07-01

    Proton acceleration by ultrashort, high intensity laser pulses has been a fast growing field of research during the last decade. The most intensely investigated acceleration mechanism is the TNSA mechanism (Target Normal Sheath Acceleration), providing protons in the multi-MeV-range. For many possible applications, however, the full energy spread and large beam divergence are major draw-backs. Therefore, a pulsed high-field solenoid was used for collimation and energy-selection and is now integrated in a full test stand for a laser-based accelerator at GSI Helmholtz Center, Darmstadt, namely the LIGHT project (Laser Ion Generation, Handling and Transport), which is a collaboration between TU Darmstadt, GSI, HZDR, JWGU Frankfurt and HI Jena. An overview of the new infrastructure, the goals of the LIGHT project, and first experimental results are presented.

  9. Infrared-laser-based fundus angiography

    Science.gov (United States)

    Klingbeil, Ulrich; Canter, Joseph M.; Lesiecki, Michael L.; Reichel, Elias

    1994-06-01

    Infrared fundus angiography, using the fluorescent dye indocyanine green (ICG), has shown great potential in delineating choroidal neovascularization (CNV) otherwise not detectable. A digital retinal imaging system containing a diode laser for illumination has been developed and optimized to perform high sensitivity ICG angiography. The system requires less power and generates less pseudo-fluorescence background than nonlaser devices. During clinical evaluation at three retinal centers more than 200 patients, the majority of which had age-related macular degeneration, were analyzed. Laser based ICG angiography was successful in outlining many of the ill-defined or obscure CNV as defined by fluorescein angiography. The procedure was not as successful with classic CNV. ICG angiograms were used to prepare and guide laser treatment.

  10. Distributed amplified ultra-stable signal quartz oscillator based

    Czech Academy of Sciences Publication Activity Database

    Salzenstein, P.; Cholley, N.; Kuna, Alexander; Abbé, P.; Lardet-Vieudrin, F.; Šojdr, Ludvík; Chauvin, J.

    2012-01-01

    Roč. 45, č. 7 (2012), s. 1937-1939 ISSN 0263-2241 Institutional support: RVO:67985882 Keywords : Time-frequency * Modulation * Flicker frequency Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.130, year: 2012

  11. Commercialization plan laser-based decoating systems

    International Nuclear Information System (INIS)

    Freiwald, J.; Freiwald, D.A.

    1998-01-01

    F2 Associates Inc. (F2) is a small, high-technology firm focused on developing and commercializing environmentally friendly laser ablation systems for industrial-rate removal of surface coatings from metals, concrete, and delicate substrates such as composites. F2 has a contract with the US Department of Energy Federal Energy Technology Center (FETC) to develop and test a laser-based technology for removing contaminated paint and other contaminants from concrete and metal surfaces. Task 4.1 in Phase 2 of the Statement of Work for this DOE contract requires that F2 ''document its plans for commercializing and marketing the stationary laser ablation system. This document shall include a discussion of prospects for commercial customers and partners and may require periodic update to reflect changing strategy. This document shall be submitted to the DOE for review.'' This report is being prepared and submitted in fulfillment of that requirement. This report describes the laser-based technology for cleaning and coatings removal, the types of laser-based systems that have been developed by F2 based on this technology, and the various markets that are emerging for this technology. F2's commercialization and marketing plans are described, including how F2's organization is structured to meet the needs of technology commercialization, F2's strategy and marketing approach, and the necessary steps to receive certification for removing paint from aircraft and DOE certification for D and D applications. The future use of the equipment built for the DOE contract is also discussed

  12. Laser Safety and Hazard Analysis for the Trailer (B70) Based AURA Laser System

    International Nuclear Information System (INIS)

    AUGUSTONI, ARNOLD L.

    2003-01-01

    A laser safety and hazard analysis was performed for the AURA laser system based on the 2000 version of the American National Standards Institute's (ANSI) Standard Z136.1, for ''Safe Use of Lasers'' and the 2000 version of the ANSI Standard Z136.6, for ''Safe Use of Lasers Outdoors''. The trailer based AURA laser system is a mobile platform, which is used to perform laser interaction experiments and tests at various national test sites. The trailer (B70) based AURA laser system is generally operated on the United State Air Force Starfire Optical Range (SOR) at Kirtland Air Force Base (KAFB), New Mexico. The laser is used to perform laser interaction testing inside the laser trailer as well as outside the trailer at target sites located at various distances from the exit telescope. In order to protect personnel, who work inside the Nominal Hazard Zone (NHZ), from hazardous laser emission exposures it was necessary to determine the Maximum Permissible Exposure (MPE) for each laser wavelength (wavelength bands) and calculate the appropriate minimum Optical Density (OD min ) of the laser safety eyewear used by authorized personnel and the Nominal Ocular Hazard Distance (NOHD) to protect unauthorized personnel who may have violated the boundaries of the control area and enter into the laser's NHZ

  13. Chemical sensors based on quantum cascade lasers

    Science.gov (United States)

    Tittel, Frank K.; Kosterev, Anatoliy A.; Rochat, Michel; Beck, Mattias; Faist, Jerome

    2002-09-01

    There is an increasing need in many chemical sensing applications ranging from industrial process control to environmental science and medical diagnostics for fast, sensitive, and selective gas detection based on laser spectroscopy. The recent availability of novel pulsed and cw quantum cascade distributed feedback (QC-DFB) lasers as mid-infrared spectroscopic sources address this need. A number of spectroscopic techniques have been demonstrated. For example, the authors have employed QC-DFB lasers for the monitoring and quantification of several trace gases and isotopic species in ambient air at ppmv and ppbv levels by means of direct absorption, wavelength modulation, cavity enhanced and cavity ringdown spectroscopy. In this work, pulsed thermoelectrically cooled QC-DFB lasers operating at ~15.6 μm were characterized for spectroscopic gas sensing applications. A new method for wavelength scanning based on the repetition rate modulation was developed. A non-wavelength-selective pyroelectric detector was incorporated in the gas sensor giving an advantage of room-temperature operation and low cost. Absorption lines of CO2 and H2O were observed in ambient air providing information about the concentration of these species.

  14. Laser-based coatings removal

    International Nuclear Information System (INIS)

    Freiwald, J.G.; Freiwald, D.

    1995-01-01

    Over the years as building and equipment surfaces became contaminated with low levels of uranium or plutonium dust, coats of paint were applied to stabilize the contaminants in place. Most of the earlier paint used was lead-based paint. More recently, various non-lead-based paints, such as two-part epoxy, are used. For D ampersand D (decontamination and decommissioning), it is desirable to remove the paints or other coatings rather than having to tear down and dispose of the entire building

  15. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the ...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser....

  16. Ultra-Stable Zero-CTE HoneySiC and H2CMN Mirror Support Structures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA MSFC, GSFC and JPL are interested in Ultra-Stable Mirror Support Structures for Exoplanet Missions. Telescopes with Apertures of 4-meters or larger and using an...

  17. LASER CLADDING ON ALUMINIUM BASE ALLOYS

    OpenAIRE

    Pilloz , M.; Pelletier , J.; Vannes , A.; Bignonnet , A.

    1991-01-01

    laser cladding is often performed on iron or titanium base alloys. In the present work, this method is employed on aluminum alloys ; nickel or silicon are added by powder injection. Addition of silicon leads to sound surface layers, but with moderated properties, while the presence of nickel induces the formation of hard intermetallic compounds and then to an attractive hardening phenomena ; however a recovery treatment has to be carried out, in order to eliminate porosity in the near surface...

  18. Problems in the development of autonomous mobile laser systems based on a cw chemical DF laser

    International Nuclear Information System (INIS)

    Aleksandrov, B P; Bashkin, A S; Beznozdrev, V N; Parfen'ev, M V; Pirogov, N A; Semenov, S N

    2003-01-01

    The problems involved in designing autonomous mobile laser systems based on high-power cw chemical DF lasers, whose mass and size parameters would make it possible to install them on various vehicles, are discussed. The need for mobility of such lasers necessitates special attention to be paid to the quest for ways and means of reducing the mass and size of the main laser systems. The optimisation of the parameters of such lasers is studied for various methods of scaling their systems. A complex approach to analysis of the optical scheme of the laser system is developed. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  19. Energy enhancer for mask based laser materials processing

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1996-01-01

    A device capable of drastically improving the energy efficiency of present mask based laser materials processing systems is presented. Good accordance between experiments and simulations for a TEA-CO2 laser system designed for laser marking has been demonstrated. The energy efficiency may...... be improved with a factor of 2 - 4 for typical mask transmittances between 10 - 40%....

  20. Recent results in mirror based high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Nielsen, Jakob Skov; Elvang, Mads

    2004-01-01

    In this paper, recent results in high power laser cutting, obtained in reseach and development projects are presented. Two types of mirror based focussing systems for laser cutting have been developed and applied in laser cutting studies on CO2-lasers up to 12 kW. In shipyard environment cutting...... speed increase relative to state-of-the-art cutting of over 100 % has been achieved....

  1. Increasing Laser Stability with Improved Electronic Instruments

    Science.gov (United States)

    Troxel, Daylin; Bennett, Aaron; Erickson, Christopher J.; Jones, Tyler; Durfee, Dallin S.

    2010-03-01

    We present several electronic instruments developed to implement an ultra-stable laser lock. These instruments include a high speed, low noise homodyne photo-detector; an ultrahigh stability, low noise current driver with high modulation bandwidth and digital control; a high-speed, low noise PID controller; a low-noise piezo driver; and a laser diode temperature controller. We will present the theory of operation for these instruments, design and construction techniques, and essential characteristics for each device.

  2. Laser Stabilization with Laser Cooled Strontium

    DEFF Research Database (Denmark)

    Christensen, Bjarke Takashi Røjle

    The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting the nonli......The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting...... the nonlinear effects from coupling of an optical cavity to laser cooled atoms having a narrow transition linewidth. Here, we have realized such a system where a thermal sample of laser cooled strontium-88 atoms are coupled to an optical cavity. The strontium-88 atoms were probed on the narrow 1S0-3P1 inter......-combination line at 689 nm in a strongly saturated regime. The dynamics of the atomic induced phase shift and absorption of the probe light were experimentally studied in details with the purpose of applications to laser stabilization. The atomic sample temperature was in the mK range which brought this system out...

  3. Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

    2004-01-01

    Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

  4. Laser-Based Additive Manufacturing of Zirconium

    Directory of Open Access Journals (Sweden)

    Himanshu Sahasrabudhe

    2018-03-01

    Full Text Available Additive manufacturing of zirconium is attempted using commercial Laser Engineered Net Shaping (LENSTM technique. A LENSTM-based approach towards processing coatings and bulk parts of zirconium, a reactive metal, aims to minimize the inconvenience of traditional metallurgical practices of handling and processing zirconium-based parts that are particularly suited to small volumes and one-of-a-kind parts. This is a single-step manufacturing approach for obtaining near net shape fabrication of components. In the current research, Zr metal powder was processed in the form of coating on Ti6Al4V alloy substrate. Scanning electron microscopy (SEM and energy dispersive spectroscopy (EDS as well as phase analysis via X-ray diffraction (XRD were studied on these coatings. In addition to coatings, bulk parts were also fabricated using LENS™ from Zr metal powders, and measured part accuracy.

  5. Key techniques for space-based solar pumped semiconductor lasers

    Science.gov (United States)

    He, Yang; Xiong, Sheng-jun; Liu, Xiao-long; Han, Wei-hua

    2014-12-01

    In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m2, and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.

  6. 77 FR 14838 - General Electric-Hitachi Global Laser Enrichment LLC, Commercial Laser-Based Uranium Enrichment...

    Science.gov (United States)

    2012-03-13

    ... Laser Enrichment LLC, Commercial Laser-Based Uranium Enrichment Facility, Wilmington, North Carolina... a license to General Electric-Hitachi Global Laser Enrichment LLC (GLE or the applicant) to authorize construction of a laser-based uranium enrichment facility and possession and use of byproduct...

  7. Bubble-Sheet-Like Interface Design with an Ultrastable Solid Electrolyte Layer for High-Performance Dual-Ion Batteries.

    Science.gov (United States)

    Qin, Panpan; Wang, Meng; Li, Na; Zhu, Haili; Ding, Xuan; Tang, Yongbing

    2017-05-01

    In this work, a bubble-sheet-like hollow interface design on Al foil anode to improve the cycling stability and rate performance of aluminum anode based dual-ion battery is reported, in which, a carbon-coated hollow aluminum anode is used as both anode materials and current collector. This anode structure can guide the alloying position inside the hollow nanospheres, and also confine the alloy sizes within the hollow nanospheres, resulting in significantly restricted volumetric expansion and ultrastable solid electrolyte interface (SEI). As a result, the battery demonstrates an excellent long-term cycling stability within 1500 cycles with ≈99% capacity retention at 2 C. Moreover, this cell displays an energy density of 169 Wh kg -1 even at high power density of 2113 W kg -1 (10 C, charge and discharge within 6 min), which is much higher than most of conventional lithium ion batteries. The interfacial engineering strategy shown in this work to stabilize SEI layer and control the alloy forming position could be generalized to promote the research development of metal anodes based battery systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Laser based micro forming and assembly.

    Energy Technology Data Exchange (ETDEWEB)

    MacCallum, Danny O' Neill; Wong, Chung-Nin Channy; Knorovsky, Gerald Albert; Steyskal, Michele D.; Lehecka, Tom (Pennsylvania State University, Freeport, PA); Scherzinger, William Mark; Palmer, Jeremy Andrew

    2006-11-01

    It has been shown that thermal energy imparted to a metallic substrate by laser heating induces a transient temperature gradient through the thickness of the sample. In favorable conditions of laser fluence and absorptivity, the resulting inhomogeneous thermal strain leads to a measurable permanent deflection. This project established parameters for laser micro forming of thin materials that are relevant to MESA generation weapon system components and confirmed methods for producing micrometer displacements with repeatable bend direction and magnitude. Precise micro forming vectors were realized through computational finite element analysis (FEA) of laser-induced transient heating that indicated the optimal combination of laser heat input relative to the material being heated and its thermal mass. Precise laser micro forming was demonstrated in two practical manufacturing operations of importance to the DOE complex: micrometer gap adjustments of precious metal alloy contacts and forming of meso scale cones.

  9. Planar Laser-Based QEPAS Trace Gas Sensor

    Directory of Open Access Journals (Sweden)

    Yufei Ma

    2016-06-01

    Full Text Available A novel quartz enhanced photoacoustic spectroscopy (QEPAS trace gas detection scheme is reported in this paper. A cylindrical lens was employed for near-infrared laser focusing. The laser beam was shaped as a planar line laser between the gap of the quartz tuning fork (QTF prongs. Compared with a spherical lens-based QEPAS sensor, the cylindrical lens-based QEPAS sensor has the advantages of easier laser beam alignment and a reduction of stringent stability requirements. Therefore, the reported approach is useful in long-term and continuous sensor operation.

  10. Pulsed Laser Cladding of Ni Based Powder

    Science.gov (United States)

    Pascu, A.; Stanciu, E. M.; Croitoru, C.; Roata, I. C.; Tierean, M. H.

    2017-06-01

    The aim of this paper is to optimize the operational parameters and quality of one step Metco Inconel 718 atomized powder laser cladded tracks, deposited on AISI 316 stainless steel substrate by means of a 1064 nm high power pulsed laser, together with a Precitec cladding head manipulated by a CLOOS 7 axes robot. The optimization of parameters and cladding quality has been assessed through Taguchi interaction matrix and graphical output. The study demonstrates that very good cladded layers with low dilution and increased mechanical proprieties could be fabricated using low laser energy density by involving a pulsed laser.

  11. GaN-based blue laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Takao; Yanashima, Katsunori; Funato, Kenji; Asatsuma, Tsunenori; Kobayashi, Toshimasa [CT Development Centre, CNC, Sony Corporation, Atsugi, Kanagawa (Japan); Tojyo, Tsuyoshi; Asano, Takeharu; Kijima, Satoru; Hino, Tomonori; Takeya, Motonobu; Uchida, Shiro; Ikeda, Masao [Sony Shiroishi Semiconductor Inc., Shiroishi, Miyagi (Japan); Tomiya, Shigetaka [Environment and Analyhsis Technology Department, Sony Corporation, Hodogaya, Yokohama (Japan)

    2001-08-13

    We report our recent progress on GaN-based high-power laser diodes (LDs), which will be applied as a light source in high-density optical storage systems. We have developed raised-pressure metal-organic chemical vapour deposition (RP-MOCVD), which can reduce the threading-dislocation density in the GaN layer to several times 10{sup 8} cm{sup -2}, and demonstrated continuous-wave (cw) operation of GaN-based LD grown by RP-MOCVD. Furthermore, we found that the epitaxial lateral overgrowth (ELO) technique is useful for further reducing threading-dislocation density to 10{sup 6} cm{sup -2} and reducing the roughness of the cleaved facet. By using this growth technique and optimizing device parameters, the lifetime of LDs was improved to more than 1000 hours under 30 mW cw operation at 60 deg. C. Our results proved that reducing both threading-dislocation density and consumption power is a valid approach to realizing a practical GaN-based LD. On the other hand, the practical GaN-based LD was obtained when threading-dislocation density in ELO-GaN was only reduced to 10{sup 6} cm{sup -2}, which is a relatively small reduction as compared with threading-dislocation density in GaAs- and InP-based LDs. We believe that the multiplication of non-radiative centres is very slow in GaN-based LDs, possibly due to the innate character of the GaN-based semiconductor itself. (author)

  12. TiO2 hierarchical porous film constructed by ultrastable foams as photoanode for quantum dot-sensitized solar cells

    Science.gov (United States)

    Du, Xing; He, Xuan; Zhao, Lei; Chen, Hui; Li, Weixin; Fang, Wei; Zhang, Wanqiu; Wang, Junjie; Chen, Huan

    2016-11-01

    It reported a novel and simple method for the first time to prepare TiO2 hierarchical porous film (THPF) using ultrastable foams as a soft template to construct porous structures. Moreover, dodecanol as one foam component was creatively used as solvent during the synthesis of CdSe quantum dots (QDs) to decrease reaction temperature and simplify precipitation process. The result showed that hierarchical pores in scale of microns introduced by foams were regarded to benefit for high coverage and unimodal distribution of QDs on the surface of THPF to increase the efficiencies of light-harvesting, charge-collection and charge-transfer. The increased efficiencies caused an enhancement in quantum efficiency of the cell and thus remarkably increased the short circuit current density (Jsc). In addition, the decrease of charge recombination resulted in the increase of the open circuit voltage (Voc) as well. The QDSSC based on THPF exhibited about 2-fold higher power conversion efficiency (η = 2.20%, Jsc = 13.82 mA cm-2, Voc = 0.572 V) than that of TiO2 nanoparticles film (TNF) (η = 1.06%, Jsc = 6.70 mA cm-2, Voc = 0.505 V). It provided a basis to use foams both as soft template and carrier to realize simultaneously construction and in-situ sensitization of photoanode in further work.

  13. Excimer laser beam profile recording based on electrochemical etched polycarbonate

    International Nuclear Information System (INIS)

    Parvin, P.; Jaleh, B.; Zangeneh, H.R.; Zamanipour, Z.; Davoud-Abadi, Gh.R.

    2008-01-01

    There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler

  14. Excimer laser beam profile recording based on electrochemical etched polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Parvin, P. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of)], E-mail: parvin@aut.ac.ir; Jaleh, B. [Physics Department, Bu-Ali Sina University, Postal Code 65174, Hamedan (Iran, Islamic Republic of); Zangeneh, H.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of); Davoud-Abadi, Gh.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of)

    2008-08-15

    There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler.

  15. Simulation based analysis of laser beam brazing

    Science.gov (United States)

    Dobler, Michael; Wiethop, Philipp; Schmid, Daniel; Schmidt, Michael

    2016-03-01

    Laser beam brazing is a well-established joining technology in car body manufacturing with main applications in the joining of divided tailgates and the joining of roof and side panels. A key advantage of laser brazed joints is the seam's visual quality which satisfies highest requirements. However, the laser beam brazing process is very complex and process dynamics are only partially understood. In order to gain deeper knowledge of the laser beam brazing process, to determine optimal process parameters and to test process variants, a transient three-dimensional simulation model of laser beam brazing is developed. This model takes into account energy input, heat transfer as well as fluid and wetting dynamics that lead to the formation of the brazing seam. A validation of the simulation model is performed by metallographic analysis and thermocouple measurements for different parameter sets of the brazing process. These results show that the multi-physical simulation model not only can be used to gain insight into the laser brazing process but also offers the possibility of process optimization in industrial applications. The model's capabilities in determining optimal process parameters are exemplarily shown for the laser power. Small deviations in the energy input can affect the brazing results significantly. Therefore, the simulation model is used to analyze the effect of the lateral laser beam position on the energy input and the resulting brazing seam.

  16. Laser wakefield accelerator based light sources: potential applications and requirements

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). NIF and Photon Sciences; Thomas, A. G. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Mangles, S. P.D. [Imperial College, London (United Kingdom). Blackett Lab.; Banerjee, S. [Univ. of Nebraska, Lincoln, NE (United States); Corde, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Flacco, A. [ENSTA, CNRS, Ecole Polytechnique, Palaiseau (France); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neely, D. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Viera, J. [Univ. of Lisbon (Portugal). GoLP-Inst. de Plasmas e Fusao Nuclear-Lab. Associado; Najmudin, Z. [Imperial College, London (United Kingdom). Blackett Lab.; Bingham, R. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Joshi, C. [Univ. of California, Los Angeles, CA (United States). Dept. of Electrical Engineering; Katsouleas, T. [Duke Univ., Durham, NC (United States). Platt School of Engineering

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  17. Plasma Channel Diagnostic Based on Laser Centroid Oscillations

    International Nuclear Information System (INIS)

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Osterhoff, Jens; Shiraishi, Satomi; Schroeder, Carl; Geddes, Cameron; Toth, Csaba; Esarey, Eric; Leemans, Wim

    2010-01-01

    A technique has been developed for measuring the properties of discharge-based plasma channels by monitoring the centroid location of a laser beam exiting the channel as a function of input alignment offset between the laser and the channel. The centroid position of low-intensity ( 14 Wcm -2 ) laser pulses focused at the input of a hydrogen-filled capillary discharge waveguide was scanned and the exit positions recorded to determine the channel shape and depth with an accuracy of a few %. In addition, accurate alignment of the laser beam through the plasma channel can be provided by minimizing laser centroid motion at the channel exit as the channel depth is scanned either by scanning the plasma density or the discharge timing. The improvement in alignment accuracy provided by this technique will be crucial for minimizing electron beam pointing errors in laser plasma accelerators.

  18. Potential for GPC-based laser direct writing

    DEFF Research Database (Denmark)

    Bañas, Andrew; Glückstad, Jesper

    2016-01-01

    lasers for such applications by using phase modulation as opposed to amplitude truncating masks. Here, we explore GPC’s potential for increasing the yield of micropscopic 3D printing also known as direct laser writing. Many light based additive manufacturing techniques, adopt a point scanning approach...

  19. New photonuclear methods based on femtosecond lasers

    International Nuclear Information System (INIS)

    Ivanov, K.A.; Shulyapov, S.A.; Savel'ev, A.B.; Uryupina, D.S.; Volkov, R.V.; Rusakov, A.V.; Turinge, A.A.; Dzhilkibaev, R.M.; Nedorezov, V.G.; Brantov, A.V.; Bychenkov, V.Yu.

    2014-01-01

    Results of X-ray diagnostics of plasma created on the surface of matter by laser pulse with an intensity of 2.5 · 10 18 W/cm 2 are presented in the paper. Comparison of experimental data with the results of numerical simulation of laser-plasma interaction is made taking into account the response functions of the detector. Examples of possible nuclear tasks realizable with the use of laser plasma as a source of charged particles and X rays are given

  20. Methodology for assessing laser-based equipment

    Science.gov (United States)

    Pelegrina-Bonilla, Gabriel; Hermsdorf, Jörg; Thombansen, Ulrich; Abels, Peter; Kaierle, Stefan; Neumann, Jörg

    2017-10-01

    Methodologies for the assessment of technology's maturity are widely used in industry and research. Probably the best known are technology readiness levels (TRLs), initially pioneered by the National Aeronautics and Space Administration (NASA). At the beginning, only descriptively defined TRLs existed, but over time, automated assessment techniques in the form of questionnaires emerged in order to determine TRLs. Originally TRLs targeted equipment for space applications, but the demands on industrial relevant equipment are partly different in terms of, for example, overall costs, product quantities, or the presence of competitors. Therefore, we present a commonly valid assessment methodology with the aim of assessing laser-based equipment for industrial use, in general. The assessment is carried out with the help of a questionnaire, which allows for a user-friendly and easy accessible way to monitor the progress from the lab-proven state to the application-ready product throughout the complete development period. The assessment result is presented in a multidimensional metric in order to reveal the current specific strengths and weaknesses of the equipment development process, which can be used to direct the remaining development process of the equipment in the right direction.

  1. Single event upset threshold estimation based on local laser irradiation

    International Nuclear Information System (INIS)

    Chumakov, A.I.; Egorov, A.N.; Mavritsky, O.B.; Yanenko, A.V.

    1999-01-01

    An approach for estimation of ion-induced SEU threshold based on local laser irradiation is presented. Comparative experiment and software simulation research were performed at various pulse duration and spot size. Correlation of single event threshold LET to upset threshold laser energy under local irradiation was found. The computer analysis of local laser irradiation of IC structures was developed for SEU threshold LET estimation. The correlation of local laser threshold energy with SEU threshold LET was shown. Two estimation techniques were suggested. The first one is based on the determination of local laser threshold dose taking into account the relation of sensitive area to local irradiated area. The second technique uses the photocurrent peak value instead of this relation. The agreement between the predicted and experimental results demonstrates the applicability of this approach. (authors)

  2. Nanodiamonds and silicon quantum dots: ultrastable and biocompatible luminescent nanoprobes for long-term bioimaging.

    Science.gov (United States)

    Montalti, M; Cantelli, A; Battistelli, G

    2015-07-21

    Fluorescence bioimaging is a powerful, versatile, method for investigating, both in vivo and in vitro, the complex structures and functions of living organisms in real time and space, also using super-resolution techniques. Being poorly invasive, fluorescence bioimaging is suitable for long-term observation of biological processes. Long-term detection is partially prevented by photobleaching of organic fluorescent probes. Semiconductor quantum dots, in contrast, are ultrastable, fluorescent contrast agents detectable even at the single nanoparticle level. Emission color of quantum dots is size dependent and nanoprobes emitting in the near infrared (NIR) region are ideal for low back-ground in vivo imaging. Biocompatibility of nanoparticles, containing toxic elements, is debated. Recent safety concerns enforced the search for alternative ultrastable luminescent nanoprobes. Most recent results demonstrated that optimized silicon quantum dots (Si QDs) and fluorescent nanodiamonds (FNDs) show almost no photobleaching in a physiological environment. Moreover in vitro and in vivo toxicity studies demonstrated their unique biocompatibility. Si QDs and FNDs are hence ideal diagnostic tools and promising non-toxic vectors for the delivery of therapeutic cargos. Most relevant examples of applications of Si QDs and FNDs to long-term bioimaging are discussed in this review comparing the toxicity and the stability of different nanoprobes.

  3. High-performance organic light-emitting diodes comprising ultrastable glass layers

    Science.gov (United States)

    Rodríguez-Viejo, Javier

    2018-01-01

    Organic light-emitting diodes (OLEDs) are one of the key solid-state light sources for various applications including small and large displays, automotive lighting, solid-state lighting, and signage. For any given commercial application, OLEDs need to perform at their best, which is judged by their device efficiency and operational stability. We present OLEDs that comprise functional layers fabricated as ultrastable glasses, which represent the thermodynamically most favorable and, thus, stable molecular conformation achievable nowadays in disordered solids. For both external quantum efficiencies and LT70 lifetimes, OLEDs with four different phosphorescent emitters show >15% enhancements over their respective reference devices. The only difference to the latter is the growth condition used for ultrastable glass layers that is optimal at about 85% of the materials’ glass transition temperature. These improvements are achieved through neither material refinements nor device architecture optimization, suggesting a general applicability of this concept to maximize the OLED performance, no matter which specific materials are used. PMID:29806029

  4. AlOx Coating of Ultrastable Zeolite Y: A Possible Method for Vanadium Passivation of FCC Catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Catana, Gabriela; Grünert, W.; Voort, P. van der; Vansant, E.F.; Schoonheydt, R.A.

    2000-01-01

    AlOx coating is proposed as a possible method for vanadium passivation of the ultrastable zeolite Y (USY). Two coating methods are discussed: (i) the deposition of the [Al13O4(OH)24(H2O)12]7+ ([Al13]) complex from aqueous solutions and (ii) the anchoring of alumoxane by in situ triisobutylaluminum

  5. Laser-based measuring equipment controlled by microcomputer

    International Nuclear Information System (INIS)

    Miron, N.; Sporea, D.; Velculescu, V.G.; Petre, M.

    1988-03-01

    Some laser-based measuring equipment controlled by microcomputer developed for industrial and scientific purposes are described. These equipments are intended for dial indicators verification, graduated rules measurement, and for very accurate measurement of the gravitational constant. (authors)

  6. Electrically pumped graphene-based Landau-level laser

    Science.gov (United States)

    Brem, Samuel; Wendler, Florian; Winnerl, Stephan; Malic, Ermin

    2018-03-01

    Graphene exhibits a nonequidistant Landau quantization with tunable Landau-level (LL) transitions in the technologically desired terahertz spectral range. Here, we present a strategy for an electrically driven terahertz laser based on Landau-quantized graphene as the gain medium. Performing microscopic modeling of the coupled electron, phonon, and photon dynamics in such a laser, we reveal that an inter-LL population inversion can be achieved resulting in the emission of coherent terahertz radiation. The presented paper provides a concrete recipe for the experimental realization of tunable graphene-based terahertz laser systems.

  7. Laser-based instrumentation for the detection of chemical agents

    International Nuclear Information System (INIS)

    Hartford, A. Jr.; Sander, R.K.; Quigley, G.P.; Radziemski, L.J.; Cremers, D.A.

    1982-01-01

    Several laser-based techniques are being evaluated for the remote, point, and surface detection of chemical agents. Among the methods under investigation are optoacoustic spectroscopy, laser-induced breakdown spectroscopy (LIBS), and synchronous detection of laser-induced fluorescence (SDLIF). Optoacoustic detection has already been shown to be capable of extremely sensitive point detection. Its application to remote sensing of chemical agents is currently being evaluated. Atomic emission from the region of a laser-generated plasma has been used to identify the characteristic elements contained in nerve (P and F) and blister (S and Cl) agents. Employing this LIBS approach, detection of chemical agent simulants dispersed in air and adsorbed on a variety of surfaces has been achieved. Synchronous detection of laser-induced fluorescence provides an attractive alternative to conventional LIF, in that an artificial narrowing of the fluorescence emission is obtained. The application of this technique to chemical agent simulants has been successfully demonstrated. 19 figures

  8. Research on laser cladding control system based on fuzzy PID

    Science.gov (United States)

    Zhang, Chuanwei; Yu, Zhengyang

    2017-12-01

    Laser cladding technology has a high demand for control system, and the domestic laser cladding control system mostly uses the traditional PID control algorithm. Therefore, the laser cladding control system has a lot of room for improvement. This feature is suitable for laser cladding technology, Based on fuzzy PID three closed-loop control system, and compared with the conventional PID; At the same time, the laser cladding experiment and friction and wear experiment were carried out under the premise of ensuring the reasonable control system. Experiments show that compared with the conventional PID algorithm in fuzzy the PID algorithm under the surface of the cladding layer is more smooth, the surface roughness increases, and the wear resistance of the cladding layer is also enhanced.

  9. Catalytic Transformation of Ethylbenzene over Y-Zeolite-based Catalysts

    KAUST Repository

    Al-Khattaf, Sulaiman

    2008-01-01

    Catalytic transformation of ethylbenzene (EB) has been investigated over ultrastable Y (USY)-zeolite-based catalysts in a novel riser simulator at different operating conditions. The effect of reaction conditions on EB conversion is reported

  10. Laser spot detection based on reaction diffusion

    Czech Academy of Sciences Publication Activity Database

    Vázquez-Otero, Alejandro; Khikhlukha, Danila; Solano-Altamirano, J. M.; Dormido, R.; Duro, N.

    2016-01-01

    Roč. 16, č. 3 (2016), s. 1-11, č. článku 315. ISSN 1424-8220 R&D Projects: GA MŠk EF15_008/0000162 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : laser spot detection * laser beam detection * reaction diffusion models * Fitzhugh-Nagumo model * reaction diffusion computation * Turing patterns Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.677, year: 2016

  11. Laser-Based Maintenance and Repair Technologies for Reactor Components

    International Nuclear Information System (INIS)

    Masaki Yoda; Naruhiko Mukai; Makoto Ochiai; Masataka Tamura; Satoshi Okada; Katsuhiko Sato; Motohiko Kimura; Yuji Sano; Noboru Saito; Seishi Shima; Tetsuo Yamamoto

    2004-01-01

    Toshiba has developed various laser-based maintenance and repair technologies and applied them to existing nuclear power plants. Laser-based technology is considered to be the best tool for remote processing in nuclear power plants, and particularly so for the maintenance and repair of reactor core components. Accessibility could be drastically improved by a simple handling system owing to the absence of reactive force against laser irradiation and the flexible optical fiber. For the preventive maintenance, laser peening (LP) technology was developed and applied to reactor components in operating BWR plants. LP is a novel process to improve residual stress from tensile to compressive on material surface layer by irradiating focused high-power laser pulses in water. We have developed a fiber-delivered LP system as a preventive maintenance measure against stress corrosion cracking (SCC). Laser ultrasonic testing (LUT) has a great potential to be applied to the remote inspection of reactor components. Laser-induced surface acoustic wave (SAW) inspection system was developed using a compact probe with a multi-mode optical fiber and an interferometer. The developed system successfully detected a micro slit of 0.5 mm depth on weld metal and heat-affected zone (HAZ). An artificial SCC was also detected by the system. We are developing a new LP system combined with LUT to treat the inner surface of bottom-mounted instruments (BMI) of PWR plants. Underwater laser seal welding (LSW) technology was also developed to apply surface crack. LSW is expected to isolate the crack tip from corrosive water environment and to stop the propagation of the crack. Rapid heating and cooling of the process minimize the heat effect, which extends the applicability to neutron-irradiated material. This paper describes recent advances in the development and application of such laser-based technologies. (authors)

  12. Laser-based techniques for combustion diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Georgiev, N.

    1997-04-01

    Two-photon-induced Degenerate Four-Wave Mixing, DFWM, was applied for the first time to the detection of CO, and NH{sub 3} molecules. Measurements were performed in a cell, and in atmospheric-pressure flames. In the cell measurements, the signal dependence on the pressure and on the laser beam intensity was studied. The possibility of simultaneous detection of NH{sub 3} and OH was investigated. Carbon monoxide and ammonia were also detected employing two-photon-induced Polarization Spectroscopy, PS. In the measurements performed in a cold gas flow, the signal strength dependence on the laser intensity, and on the polarization of the pump beam, was investigated. An approach to improve the spatial resolution of the Amplified Stimulated Emission, ASE, was developed. In this approach, two laser beams at different frequencies were crossed in the sample. If the sum of the frequencies of the two laser beams matches a two photon resonance of the investigated species, only the molecules in the intersection volume will be excited. NH{sub 3} molecules and C atoms were studied. The potential of using two-photon LIF for two-dimensional imaging of combustion species was investigated. Although LIF is species specific, several species can be detected simultaneously by utilizing spectral coincidences. Combining one- and two-photon process, OH, NO, and O were detected simultaneously, as well as OH, NO, and NH{sub 3}. Collisional quenching is the major source of uncertainty in quantitative applications of LIF. A technique for two-dimensional, absolute species concentration measurements, circumventing the problems associated with collisional quenching, was developed. By applying simple mathematics to the ratio of two LIF signals generated from two counterpropagating laser beams, the absolute species concentration could be obtained. 41 refs

  13. A laser based reusable microjet injector for transdermal drug delivery

    Science.gov (United States)

    Han, Tae-hee; Yoh, Jack J.

    2010-05-01

    A laser based needle-free liquid drug injection device has been developed. A laser beam is focused inside the liquid contained in the rubber chamber of microscale. The focused laser beam causes explosive bubble growth, and the sudden volume increase in a sealed chamber drives a microjet of liquid drug through the micronozzle. The exit diameter of a nozzle is 125 μm and the injected microjet reaches an average velocity of 264 m/s. This device adds the time-varying feature of microjet to the current state of liquid injection for drug delivery.

  14. Efficient TEA CO2 laser based coating removal system

    CSIR Research Space (South Africa)

    Prinsloo, FJ

    2007-04-01

    Full Text Available stream_source_info Prinsloo_2007.pdf.txt stream_content_type text/plain stream_size 11617 Content-Encoding UTF-8 stream_name Prinsloo_2007.pdf.txt Content-Type text/plain; charset=UTF-8 Efficient TEA CO2 laser based... by keeping energy density below the damage threshold. The advantage of a pulsed TEA CO2 laser system is that a laser frequency and temporal profile can be chosen to maximize paint removal and concurrently minimize substrate damage. To achieve...

  15. Laser spot welding of cobalt-based amorphous metal foils

    International Nuclear Information System (INIS)

    Runchev, Dobre; Dorn, Lutc; Jaferi, Seifolah; Purbst, Detler

    1997-01-01

    The results concerning weldability of amorphous alloy (VAC 6025F) in shape of foils and the quality of laser-spot welded joints are presented in this paper. The aim of the research was the production of a high quality welding joint, by preserving the amorphous structure. The quality of the joint was tested by shear strength analysis and microhardness measuring. The metallographic studies were made by using optical microscope and SEM. The results show that (1) overlapped Co based amorphous metals foils can be welded with high-quality by a pulsed Nd: YAG-Laser, but only within a very narrow laser parameter window; (2) the laser welded spots show comparably high strength as the basic material; (3) the structure of the welded spot remains amorphous, so that the same characteristics as the base material can be achieved. (author)

  16. Fiber laser welding of nickel based superalloy Inconel 625

    Science.gov (United States)

    Janicki, Damian M.

    2013-01-01

    The paper describes the application of single mode high power fiber laser (HPFL) for the welding of nickel based superalloy Inconel 625. Butt joints of Inconel 625 sheets 0,8 mm thick were laser welded without an additional material. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The quality and mechanical properties of the joints were determined by means of tensile and bending tests, and micro hardness tests, and also metallographic examinations. The results showed that a proper selection of laser welding parameters provides non-porous, fully-penetrated welds with the aspect ratio up to 2.0. The minimum heat input required to achieve full penetration butt welded joints with no defect was found to be 6 J/mm. The yield strength and ultimate tensile strength of the joints are essentially equivalent to that for the base material.

  17. Distributed Feedback Laser Based on Single Crystal Perovskite

    Science.gov (United States)

    Sun, Shang; Xiao, Shumin; Song, Qinghai

    2017-06-01

    We demonstrate a single crystal perovskite based, with grating-structured photoresist on top, highly polarized distributed feedback laser. A lower laser threshold than the Fabry-Perot mode lasers from the same single crystal CH3NH3PbBr3 microplate was obtained. Single crystal CH3NH3PbBr3 microplates was synthesized with one-step solution processed precipitation method. Once the photoresist on top of the microplate was patterned with electron beam, the device was realized. This one-step fabrication process utilized the advantage of single crystal to the greatest extend. The ultra-low defect density in single crystalline microplate offer an opportunity for lower threshold lasing action compare with poly-crystal perovskite films. In the experiment, the lasing action based on the distributed feedback grating design was found with lower threshold and higher intensity than the Fabry-Perot mode lasers supported by the flat facets of the same microplate.

  18. Compact silicon photonics-based multi laser module for sensing

    Science.gov (United States)

    Ayotte, S.; Costin, F.; Babin, A.; Paré-Olivier, G.; Morin, M.; Filion, B.; Bédard, K.; Chrétien, P.; Bilodeau, G.; Girard-Deschênes, E.; Perron, L.-P.; Davidson, C.-A.; D'Amato, D.; Laplante, M.; Blanchet-Létourneau, J.

    2018-02-01

    A compact three-laser source for optical sensing is presented. It is based on a low-noise implementation of the Pound Drever-Hall method and comprises high-bandwidth optical phase-locked loops. The outputs from three semiconductor distributed feedback lasers, mounted on thermo-electric coolers (TEC), are coupled with micro-lenses into a silicon photonics (SiP) chip that performs beat note detection and several other functions. The chip comprises phase modulators, variable optical attenuators, multi-mode-interference couplers, variable ratio tap couplers, integrated photodiodes and optical fiber butt-couplers. Electrical connections between a metallized ceramic and the TECs, lasers and SiP chip are achieved by wirebonds. All these components stand within a 35 mm by 35 mm package which is interfaced with 90 electrical pins and two fiber pigtails. One pigtail carries the signals from a master and slave lasers, while another carries that from a second slave laser. The pins are soldered to a printed circuit board featuring a micro-processor that controls and monitors the system to ensure stable operation over fluctuating environmental conditions. This highly adaptable multi-laser source can address various sensing applications requiring the tracking of up to three narrow spectral features with a high bandwidth. It is used to sense a fiber-based ring resonator emulating a resonant fiber optics gyroscope. The master laser is locked to the resonator with a loop bandwidth greater than 1 MHz. The slave lasers are offset frequency locked to the master laser with loop bandwidths greater than 100 MHz. This high performance source is compact, automated, robust, and remains locked for days.

  19. Innovative laser based solar cell scribing

    Science.gov (United States)

    Frei, Bruno; Schneeberger, Stefan; Witte, Reiner

    2011-03-01

    The solar photovoltaic market is continuously growing utilizing boths crystalline silicon (c-Si) as well as thin film technologies. This growth is directly dependant on the manufacturing costs for solar cells. Factors for cost reduction are innovative ideas for an optimization of precision and throughput. Lasers are excellent tools to provide highly efficient processes with impressive accuracy. They need to be used in combination with fast and precise motion systems for a maximum gain in the manufacturing process, yielding best cost of ownership. In this article such an innovative solution is presented for laser scribing in thin film Si modules. A combination of a new glass substrate holding system combined with a fast and precise motion system is the foundation for a cost effective scribing machine. In addition, the advantages of fiber lasers in beam delivery and beam quality guarantee not only shorter setup and down times but also high resolution and reproducibility for the scribing processes P1, P2 and P3. The precision of the whole system allows to reduce the dead zone to a minimum and therefore to improve the efficiency of the modules.

  20. Laser based analytical spectroscopy of uranium

    International Nuclear Information System (INIS)

    Argekar, A.A.; Kulkarni, M.J.; Godbole, S.V.; Page, A.G.; Samuel, J.K.; Paranjape, D.B.; Singh Mudher, K.D.

    1992-01-01

    Analytical spectroscopy of uranium has been studied using a XeCl excimer laser, using the fluorescence emission of U(VI) ions doped in a solid solution of sodium fluoride (NaF) and sodium chloride (NaCl) in 3:2 proportion. An electronic circuitry involving time-gating of the photomultiplier tube and facility to integrate the analytical signal over ten laser pulses has been developed to enable laser operation and signal detection with high S/N ratio. The matrix enhanced U(VI) fluorescence emission is free from chemical and spectral interferences due to the concomitant presence of ten metallic elements generally associated with uranium. The digital signal output is highly precise and does not saturate upto 5 ppm uranium concentration. X-ray diffraction patterns obtained for uranium doped compounds at 2.5% and 10% dopant concentrations are broadly similar to that of Na 2 U 2 O 7 . The detailed studies have, however, revealed fine structure for individual peaks, thereby, revealing the formation of sodium fluoro-uranate complex which is responsible for the enhanced intensity of fluorescence emission. (author). 10 refs., 6 figs., 2 tabs

  1. 77 FR 13367 - General Electric-Hitachi Global Laser Enrichment, LLC, Proposed Laser-Based Uranium Enrichment...

    Science.gov (United States)

    2012-03-06

    ... NUCLEAR REGULATORY COMMISSION [NRC-2009-0157] General Electric-Hitachi Global Laser Enrichment, LLC, Proposed Laser-Based Uranium Enrichment Facility, Wilmington, NC AGENCY: Nuclear Regulatory... Impact Statement (EIS) for the proposed General Electric- Hitachi Global Laser Enrichment, LLC (GLE...

  2. Conceptual fusion reactor designs based on the laser heat solenoid

    International Nuclear Information System (INIS)

    Steinhauer, L.C.

    1976-01-01

    The feasibility of the laser heated solenoid (LHS) as an approach to fusion and fusion-fission commercial power generation has been examined. The LHS concept is based on magnetic confinement of a long slender plasma column which is partly heated by the axially directed beam from a powerful long wavelength laser. As a pure fusion concept, the LHS configurations studied so far are characterized by fairly difficult engineering constraints, particularly on the magnet, a large laser, and a marginally acceptable system energy balance. As a fusion-fission system, however, the LHS is capable of a very attractive energy balance, has much more relaxed engineering constraints, requires a relatively modest laser, and as such holds great potential as a power generator and fissile fuel breeding scheme

  3. Numerical Model based Reliability Estimation of Selective Laser Melting Process

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2014-01-01

    Selective laser melting is developing into a standard manufacturing technology with applications in various sectors. However, the process is still far from being at par with conventional processes such as welding and casting, the primary reason of which is the unreliability of the process. While...... of the selective laser melting process. A validated 3D finite-volume alternating-direction-implicit numerical technique is used to model the selective laser melting process, and is calibrated against results from single track formation experiments. Correlation coefficients are determined for process input...... parameters such as laser power, speed, beam profile, etc. Subsequently, uncertainties in the processing parameters are utilized to predict a range for the various outputs, using a Monte Carlo method based uncertainty analysis methodology, and the reliability of the process is established....

  4. Laser-based direct-write techniques for cell printing

    Energy Technology Data Exchange (ETDEWEB)

    Schiele, Nathan R; Corr, David T [Biomedical Engineering Department, Rensselaer Polytechnic Institute, Troy, NY (United States); Huang Yong [Department of Mechanical Engineering, Clemson University, Clemson, SC (United States); Raof, Nurazhani Abdul; Xie Yubing [College of Nanoscale Science and Engineering, University at Albany, SUNY, Albany, NY (United States); Chrisey, Douglas B, E-mail: schien@rpi.ed, E-mail: chrisd@rpi.ed [Material Science and Engineering Department, Rensselaer Polytechnic Institute, Troy, NY (United States)

    2010-09-15

    Fabrication of cellular constructs with spatial control of cell location ({+-}5 {mu}m) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing. (topical review)

  5. Iterative Decoding for an Optical CDMA based Laser communication System

    International Nuclear Information System (INIS)

    Kim, Jin Young; Kim, Eun Cheol; Cha, Jae Sang

    2008-01-01

    An optical CDMA(code division multiple access)based Laser communication system has attracted much attention since it requires minimal optical Laser signal processing and it is virtually delay free, while from the theoretical point of view, its performance depends on the auto and cross correlation properties of employed sequences. Various kinds of channel coding schemes for optical CDMA based Laser communication systems have been proposed and analyzed to compensate nonideal channel and receiver conditions in impaired photon channels. In this paper, we propose and analyze an iterative decoding of optical CDMA based Laser communication signals for both shot noise limited and thermal noise limited systems. It is assumed that optical channel is an intensity modulated (IM)channel and direct detection scheme is employed to detect the received optical signal. The performance is evaluated in terms of bit error probability and throughput. It is demonstrated that the BER and throughput performance is substantially improved with interleaver length for a fixed code rate and with alphabet size of PPM (pulse position modulation). Also, the BER and throughput performance is significantly enhanced with the number of iterations for decoding process. The results in this paper can be applied to the optical CDMA based Laser communication network with multiple access applications

  6. Iterative Decoding for an Optical CDMA based Laser communication System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Young; Kim, Eun Cheol [Kwangwoon Univ., Seoul (Korea, Republic of); Cha, Jae Sang [Seoul National Univ. of Technology, Seoul (Korea, Republic of)

    2008-11-15

    An optical CDMA(code division multiple access)based Laser communication system has attracted much attention since it requires minimal optical Laser signal processing and it is virtually delay free, while from the theoretical point of view, its performance depends on the auto and cross correlation properties of employed sequences. Various kinds of channel coding schemes for optical CDMA based Laser communication systems have been proposed and analyzed to compensate nonideal channel and receiver conditions in impaired photon channels. In this paper, we propose and analyze an iterative decoding of optical CDMA based Laser communication signals for both shot noise limited and thermal noise limited systems. It is assumed that optical channel is an intensity modulated (IM)channel and direct detection scheme is employed to detect the received optical signal. The performance is evaluated in terms of bit error probability and throughput. It is demonstrated that the BER and throughput performance is substantially improved with interleaver length for a fixed code rate and with alphabet size of PPM (pulse position modulation). Also, the BER and throughput performance is significantly enhanced with the number of iterations for decoding process. The results in this paper can be applied to the optical CDMA based Laser communication network with multiple access applications.

  7. Laser-based direct-write techniques for cell printing

    International Nuclear Information System (INIS)

    Schiele, Nathan R; Corr, David T; Huang Yong; Raof, Nurazhani Abdul; Xie Yubing; Chrisey, Douglas B

    2010-01-01

    Fabrication of cellular constructs with spatial control of cell location (±5 μm) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing. (topical review)

  8. Control of Reproduced Colour Using Laser Based Tristimulus Colorimetry

    OpenAIRE

    Oulton, David

    1999-01-01

    Tristimulus colorimetry based laser line reflectance measurement is proposed and exemplified by the construction and testing of a prototype abridged spectrometer.The intent is to enable rugged on-line colour measurement and improve on the instrument to instrument variability that is characteristic of filter based spectrometry

  9. Rapid analysis of steels using laser-based techniques

    International Nuclear Information System (INIS)

    Cremers, D.A.; Archuleta, F.L.; Dilworth, H.C.

    1985-01-01

    Based on the data obtained by this study, we conclude that laser-based techniques can be used to provide at least semi-quantitative information about the elemental composition of molten steel. Of the two techniques investigated here, the Sample-Only method appears preferable to the LIBS (laser-induced breakdown spectroscopy) method because of its superior analytical performance. In addition, the Sample-Only method would probably be easier to incorporate into a steel plant environment. However, before either technique can be applied to steel monitoring, additional research is needed

  10. Surface alloying of nickel based superalloys by laser

    International Nuclear Information System (INIS)

    Rodriguez, G.P.; Garcia, I.; Damborenea, J.J. de

    1998-01-01

    Ni based superalloys present a high oxidation resistance at high temperature as well as good mechanical properties. But new technology developments force to research in this materials to improve their properties at high temperature. In this work, two Ni based superalloys (Nimonic 80A and Inconel 600) were surface alloyed with aluminium using a high power laser. SEM and EDX were used to study the microstructure of the obtained coatings. Alloyed specimens were tested at 1.273 K between 24 and 250 h. Results showed the generation of a protective and continuous coating of alumina on the laser treated specimens surface that can improve oxidation resistance. (Author) 8 refs

  11. Experimental demonstration of a Fano laser based on photonic crystals

    DEFF Research Database (Denmark)

    Yu, Yi; Semenova, Elizaveta; Yvind, Kresten

    2017-01-01

    Conventional semiconductor laser mirrors are based on Fresnel reflection [1], Bragg reflection [2, 3] or total internal reflection [4]. Here we demonstrate a new laser concept using photonic crystals (PhC), with a mirror based on Fano interference between a waveguide continuum and a discrete...... resonance of a nanocavity [5]. We show that the very narrowband feature of the Fano resonance [6] can lead to single mode lasing. In addition, when combined with optical nonlinearity, the highly dispersive feature of the Fano resonance can promote self-pulsations at gigahertz frequencies [7], which...

  12. Broadband pulsed difference frequency generation laser source centered 3326 nm based on ring fiber lasers

    Science.gov (United States)

    Chen, Guangwei; Li, Wenlei

    2018-03-01

    A broadband pulsed mid-infrared difference frequency generation (DFG) laser source based on MgO-doped congruent LiNbO3 bulk is experimentally demonstrated, which employs a homemade pulsed ytterbium-doped ring fiber laser and a continuous wave erbium-doped ring fiber laser to act as seed sources. The experimental results indicate that the perfect phase match crystal temperature is about 74.5∘C. The maximum spectrum bandwidth of idler is about 60 nm with suitable polarization states of fundamental lights. The central wavelength of idlers varies from 3293 nm to 3333 nm over the crystal temperature ranges of 70.4-76∘C. A jump of central wavelength exists around crystal temperature of 72∘C with variation of about 30 nm. The conversion efficiency of DFG can be tuned with the crystal temperature and polarization states of fundamental lights.

  13. The design of laser atmosphere transmission characteristic measurement system based on virtual instrument

    Science.gov (United States)

    Zhang, Laixian; Sun, Huayan; Xu, Jiawen

    2010-10-01

    The laser atmosphere transmission characteristic affects the use of laser in engineering greatly. This paper designed a laser atmosphere transmission characteristic measurement system based on LabVIEW software, a product of NI. The system acquires laser spacial distribution by means of controlling NI image acquisition card and CCD through PCI, controls oscillograph to acquire laser time domain distribution through Ethernet and controls power meter to acquire energy of laser through RS-232. It processes the data acquired and analyses the laser atmosphere transmission characteristic using Matlab, which is powerful in data processing, through software interface. It provided a new way to study the laser atmosphere transmission characteristic.

  14. Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J

    2009-12-16

    Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.

  15. Centralized computer-based controls of the Nova Laser Facility

    International Nuclear Information System (INIS)

    Krammen, J.

    1985-01-01

    This article introduces the overall architecture of the computer-based Nova Laser Control System and describes its basic components. Use of standard hardware and software components ensures that the system, while specialized and distributed throughout the facility, is adaptable. 9 references, 6 figures

  16. Contextual segment-based classification of airborne laser scanner data

    NARCIS (Netherlands)

    Vosselman, George; Coenen, Maximilian; Rottensteiner, Franz

    2017-01-01

    Classification of point clouds is needed as a first step in the extraction of various types of geo-information from point clouds. We present a new approach to contextual classification of segmented airborne laser scanning data. Potential advantages of segment-based classification are easily offset

  17. A laser printing based approach for printed electronics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T.; Hu, M.; Guo, Q.; Zhang, W.; Yang, J., E-mail: jyang@eng.uwo.ca [Department of Mechanical and Materials Engineering, Western University, London N6A 3K7 (Canada); Liu, Y.; Lau, W. [Chengdu Green Energy and Green Manufacturing Technology R& D Center, 355 Tengfei Road, 620107 Chengdu (China); Wang, X. [Department of Mechanical and Materials Engineering, Western University, London N6A 3K7 (Canada); Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2016-03-07

    Here we report a study of printing of electronics using an office use laser printer. The proposed method eliminates those critical disadvantages of solvent-based printing techniques by taking the advantages of electroless deposition and laser printing. The synthesized toner acts as a catalyst for the electroless copper deposition as well as an adhesion-promoting buffer layer between the substrate and deposited copper. The easy metallization of printed patterns and strong metal-substrate adhesion make it an especially effective method for massive production of flexible printed circuits. The proposed process is a high throughput, low cost, efficient, and environmentally benign method for flexible electronics manufacturing.

  18. A laser printing based approach for printed electronics

    International Nuclear Information System (INIS)

    Zhang, T.; Hu, M.; Guo, Q.; Zhang, W.; Yang, J.; Liu, Y.; Lau, W.; Wang, X.

    2016-01-01

    Here we report a study of printing of electronics using an office use laser printer. The proposed method eliminates those critical disadvantages of solvent-based printing techniques by taking the advantages of electroless deposition and laser printing. The synthesized toner acts as a catalyst for the electroless copper deposition as well as an adhesion-promoting buffer layer between the substrate and deposited copper. The easy metallization of printed patterns and strong metal-substrate adhesion make it an especially effective method for massive production of flexible printed circuits. The proposed process is a high throughput, low cost, efficient, and environmentally benign method for flexible electronics manufacturing.

  19. Laser-Based Diagnostic Measurements of Low Emissions Combustor Concepts

    Science.gov (United States)

    Hicks, Yolanda R.

    2011-01-01

    This presentation provides a summary of primarily laser-based measurement techniques we use at NASA Glenn Research Center to characterize fuel injection, fuel/air mixing, and combustion. The report highlights using Planar Laser-Induced Fluorescence, Particle Image Velocimetry, and Phase Doppler Interferometry to obtain fuel injector patternation, fuel and air velocities, and fuel drop sizes and turbulence intensities during combustion. We also present a brief comparison between combustors burning standard JP-8 Jet fuel and an alternative fuels. For this comparison, we used flame chemiluminescence and high speed imaging.

  20. Forecasting method in multilateration accuracy based on laser tracker measurement

    International Nuclear Information System (INIS)

    Aguado, Sergio; Santolaria, Jorge; Samper, David; José Aguilar, Juan

    2017-01-01

    Multilateration based on a laser tracker (LT) requires the measurement of a set of points from three or more positions. Although the LTs’ angular information is not used, multilateration produces a volume of measurement uncertainty. This paper presents two new coefficients from which to determine whether the measurement of a set of points, before performing the necessary measurements, will improve or worsen the accuracy of the multilateration results, avoiding unnecessary measurement, and reducing the time and economic cost required. The first specific coefficient measurement coefficient (MC LT ) is unique for each laser tracker. It determines the relationship between the radial and angular laser tracker measurement noise. Similarly, the second coefficient is related with specific conditions of measurement β . It is related with the spatial angle between the laser tracker positions α and its effect on error reduction. Both parameters MC LT and β are linked in error reduction limits. Beside these, a new methodology to determine the multilateration reduction limit according to the multilateration technique of an ideal laser tracker distribution and a random one are presented. It provides general rules and advice from synthetic tests that are validated through a real test carried out in a coordinate measurement machine. (paper)

  1. Non-Topographic Space-Based Laser Remote Sensing

    Science.gov (United States)

    Yu, Anthony W.; Abshire, James B.; Riris, Haris; Purucker, Michael; Janches, Diego; Getty, Stephanie; Krainak, Michael A.; Stephen, Mark A.; Chen, Jeffrey R.; Li, Steve X.; hide

    2016-01-01

    In the past 20+ years, NASA Goddard Space Flight Center (GSFC) has successfully developed and flown lidars for mapping of Mars, the Earth, Mercury and the Moon. As laser and electro-optics technologies expand and mature, more sophisticated instruments that once were thought to be too complicated for space are being considered and developed. We will present progress on several new, space-based laser instruments that are being developed at GSFC. These include lidars for remote sensing of carbon dioxide and methane on Earth for carbon cycle and global climate change; sodium resonance fluorescence lidar to measure environmental parameters of the middle and upper atmosphere on Earth and Mars and a wind lidar for Mars orbit; in situ laser instruments include remote and in-situ measurements of the magnetic fields; and a time-of-flight mass spectrometer to study the diversity and structure of nonvolatile organics in solid samples on missions to outer planetary satellites and small bodies.

  2. High-average-power laser medium based on silica glass

    Science.gov (United States)

    Fujimoto, Yasushi; Nakatsuka, Masahiro

    2000-01-01

    Silica glass is one of the most attractive materials for a high-average-power laser. We have developed a new laser material base don silica glass with zeolite method which is effective for uniform dispersion of rare earth ions in silica glass. High quality medium, which is bubbleless and quite low refractive index distortion, must be required for realization of laser action. As the main reason of bubbling is due to hydroxy species remained in the gelation same, we carefully choose colloidal silica particles, pH value of hydrochloric acid for hydrolysis of tetraethylorthosilicate on sol-gel process, and temperature and atmosphere control during sintering process, and then we get a bubble less transparent rare earth doped silica glass. The refractive index distortion of the sample also discussed.

  3. Fundamentals of metasurface lasers based on resonant dark states

    International Nuclear Information System (INIS)

    Droulias, Sotiris; Technology - Hellas; Jain, Aditya; Koschny, Thomas; Soukoulis, Costas M.; Technology - Hellas; Ames Laboratory and Iowa State University, Ames, IA

    2017-01-01

    Recently, our group proposed a metamaterial laser design based on explicitly coupled dark resonant states in low-loss dielectrics, which conceptually separates the gain-coupled resonant photonic state responsible for macroscopic stimulated emission from the coupling to specific free-space propagating modes, allowing independent adjustment of the lasing state and its coherent radiation output. Due to this functionality, it is now possible to make lasers that can overcome the trade-off between system dimensions and Q factor, especially for surface emitting lasers with deeply subwavelength thickness. In this paper, we give a detailed discussion of the key functionality and benefits of this design, such as radiation damping tunability, directionality, subwavelength integration, and simple layer-by-layer fabrication. Finally, we examine in detail the fundamental design tradeoffs that establish the principle of operation and must be taken into account and give guidance for realistic implementations.

  4. Nanographene-Based Saturable Absorbers for Ultrafast Fiber Lasers

    Directory of Open Access Journals (Sweden)

    Hsin-Hui Kuo

    2014-01-01

    Full Text Available The generation of femtosecond pulse laser in the erbium-doped fiber laser system is presented by integrating of the nanographene-based saturable absorbers (SAs. A simplified method of dispersed nanographene-based SAs side-polished fiber device with controllable polished length and depth was also developed. The dependence of geometry of a graphene-deposited side-polished fiber device on optical nonlinear characteristics and on the performance of the MLFL was screened. We found that the 10 mm polished length with 1.68 dB insertion loss had the highest modulation depth (MD of 1.2%. A stable MLFL with graphene-based SAs employing the optimized side-polished fiber device showed a pulse width, a 3 dB bandwidth, a time-bandwidth product (TBP, a repetition rate, and pulse energy of 523 fs, 5.4 nm, 0.347, 16.7 MHz, and 0.18 nJ, respectively, at fundamental soliton-like operation. The femtosecond pulse laser is achieved by evanescent field coupling through graphene-deposited side-polished fiber devices in the laser cavity. This study demonstrates that the polished depth is the key fabrication geometric parameter affecting the overall optical performance and better results exist within the certain polished range.

  5. Fiber-based laser MOPA transmitter packaging for space environment

    Science.gov (United States)

    Stephen, Mark; Yu, Anthony; Chen, Jeffrey; Numata, Kenji; Wu, Stewart; Gonzales, Brayler; Han, Lawrence; Fahey, Molly; Plants, Michael; Rodriguez, Michael; Allan, Graham; Abshire, James; Nicholson, Jeffrey; Hariharan, Anand; Mamakos, William; Bean, Brian

    2018-02-01

    NASA's Goddard Space Flight Center has been developing lidar to remotely measure CO2 and CH4 in the Earth's atmosphere. The ultimate goal is to make space-based satellite measurements with global coverage. We are working on maturing the technology readiness of a fiber-based, 1.57-micron wavelength laser transmitter designed for use in atmospheric CO2 remote-sensing. To this end, we are building a ruggedized prototype to demonstrate the required power and performance and survive the required environment. We are building a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture. The laser is a wavelength-locked, single frequency, externally modulated DBR operating at 1.57-micron followed by erbium-doped fiber amplifiers. The last amplifier stage is a polarization-maintaining, very-large-mode-area fiber with 1000 μm2 effective area pumped by a Raman fiber laser. The optical output is single-frequency, one microsecond pulses with >450 μJ pulse energy, 7.5 KHz repetition rate, single spatial mode, and < 20 dB polarization extinction.

  6. Beam manipulation for compact laser wakefield accelerator based free-electron lasers

    International Nuclear Information System (INIS)

    Loulergue, A; Labat, M; Benabderrahmane, C; Couprie, M E; Evain, C; Malka, V

    2015-01-01

    Free-electron lasers (FELs) are a unique source of light, particularly in the x-ray domain. After the success of FELs based on conventional acceleration using radio-frequency cavities, an important challenge is the development of FELs based on electron bunching accelerated by a laser wakefield accelerator (LWFA). However, the present LWFA electron bunch properties do not permit use directly for a significant FEL amplification. It is known that longitudinal decompression of electron beams delivered by state-of-the-art LWFA eases the FEL process. We propose here a second order transverse beam manipulation turning the large inherent transverse chromatic emittances of LWFA beams into direct FEL gain advantage. Numerical simulations are presented showing that this beam manipulation can further enhance by orders of magnitude the peak power of the radiation. (paper)

  7. Velocimetry using scintillation of a laser beam for a laser-based gas-flux monitor

    Science.gov (United States)

    Kagawa, Naoki; Wada, Osami; Koga, Ryuji

    1999-05-01

    This paper describes a velocimetry system using scintillation of a laser-beam with spatial filters based on sensor arrays for a laser- based gas flux monitor. In the eddy correlation method, gas flux is obtained by mutual relation between the gas density and the flow velocity. The velocimetry system is developed to support the flow velocity monitor portion of the laser-based gas flux monitor with a long span for measurement. In order to sense not only the flow velocity but also the flow direction, two photo diode arrays are arranged with difference of a quarter period of the weighting function between them; the two output signals from the sensor arrays have phase difference of either (pi) /2 or -(pi) /2 depending on the sense of flow direction. In order to obtain the flow velocity and the flow direction instantly, an electronic apparatus built by the authors extracts frequency and phase from crude outputs of the pair of sensors. A feasibility of the velocimetry was confirmed indoors by measurement of the flow- velocity vector of the convection. Measured flow-velocity vector of the upward flow agreed comparatively with results of an ultrasonic anemometer.

  8. Nuclear based diagnostics in high-power laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Marc; Sonnabend, Kerstin; Harres, Knut; Otten, Anke; Roth, Markus [TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Vogt, Karsten; Bagnoud, Vincent [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)

    2010-07-01

    High-power lasers allow focused intensities of >10{sup 18} W/cm{sup 2}. During the laser-solid interaction, an intense relativistic electron current is injected from the plasma into the target. One challenge is to characterize the electron dynamic close to the interaction region. Moreover, next generation high-power laser proton acceleration leads to high proton fluxes, which require novel, nuclear diagnostic techniques. We present an activation-based nuclear pyrometry for the investigation of electrons generated in relativistic laser-solid interactions. We use novel activation targets consisting of several isotopes with different photo-neutron disintegration thresholds. The electrons are decelerated inside the target via bremsstrahlung processes. The high-energy bremsstrahlung induces photo-nuclear reactions. In this energy range no disturbing low energy effects are important. Via the pyrometry the Reconstruction of the absolute yield, spectral and spatial distribution of the electrons is possible. For the characterization of proton beams we present a nuclear activation imaging spectroscopy (NAIS). The diagnostic is based on proton-neutron disintegration reactions of copper stacked in consecutive layers. An autoradiography of copper layers leads to spectrally and spatially reconstruction of the beam profile.

  9. Random fiber laser based on artificially controlled backscattering fibers.

    Science.gov (United States)

    Wang, Xiaoliang; Chen, Daru; Li, Haitao; She, Lijuan; Wu, Qiong

    2018-01-10

    The random fiber laser (RFL), which is a milestone in laser physics and nonlinear optics, has attracted considerable attention recently. Most previously reported RFLs are based on distributed feedback of Rayleigh scattering amplified through the stimulated Raman-Brillouin scattering effect in single-mode fibers, which require long-distance (tens of kilometers) single-mode fibers and high threshold, up to watt level, due to the extremely small Rayleigh scattering coefficient of the fiber. We proposed and demonstrated a half-open-cavity RFL based on a segment of an artificially controlled backscattering single-mode fiber with a length of 210 m, 310 m, or 390 m. A fiber Bragg grating with a central wavelength of 1530 nm and a segment of artificially controlled backscattering single-mode fiber fabricated by using a femtosecond laser form the half-open cavity. The proposed RFL achieves thresholds of 25 mW, 30 mW, and 30 mW, respectively. Random lasing at a wavelength of 1530 nm and extinction ratio of 50 dB is achieved when a segment of 5 m erbium-doped fiber is pumped by a 980 nm laser diode in the RFL. A novel RFL with many short cavities has been achieved with low threshold.

  10. Research progress of laser welding process dynamic monitoring technology based on plasma characteristics signal

    Directory of Open Access Journals (Sweden)

    Teng WANG

    2017-02-01

    Full Text Available During the high-power laser welding process, plasmas are induced by the evaporation of metal under laser radiation, which can affect the coupling of laser energy and the workpiece, and ultimately impact on the reliability of laser welding quality and process directly. The research of laser-induced plasma is a focus in high-power deep penetration welding field, which provides a promising research area for realizing the automation of welding process quality inspection. In recent years, the research of laser welding process dynamic monitoring technology based on plasma characteristics is mainly in two aspects, namely the research of plasma signal detection and the research of laser welding process modeling. The laser-induced plasma in the laser welding is introduced, and the related research of laser welding process dynamic monitoring technology based on plasma characteristics at home and abroad is analyzed. The current problems in the field are summarized, and the future development trend is put forward.

  11. Isotope Enrichment Detection by Laser Ablation - Laser Absorption Spectrometry: Automated Environmental Sampling and Laser-Based Analysis for HEU Detection

    International Nuclear Information System (INIS)

    Anheier, Norman C.; Bushaw, Bruce A.

    2010-01-01

    The global expansion of nuclear power, and consequently the uranium enrichment industry, requires the development of new safeguards technology to mitigate proliferation risks. Current enrichment monitoring instruments exist that provide only yes/no detection of highly enriched uranium (HEU) production. More accurate accountancy measurements are typically restricted to gamma-ray and weight measurements taken in cylinder storage yards. Analysis of environmental and cylinder content samples have much higher effectiveness, but this approach requires onsite sampling, shipping, and time-consuming laboratory analysis and reporting. Given that large modern gaseous centrifuge enrichment plants (GCEPs) can quickly produce a significant quantity (SQ ) of HEU, these limitations in verification suggest the need for more timely detection of potential facility misuse. The Pacific Northwest National Laboratory (PNNL) is developing an unattended safeguards instrument concept, combining continuous aerosol particulate collection with uranium isotope assay, to provide timely analysis of enrichment levels within low enriched uranium facilities. This approach is based on laser vaporization of aerosol particulate samples, followed by wavelength tuned laser diode spectroscopy to characterize the uranium isotopic ratio through subtle differences in atomic absorption wavelengths. Environmental sampling (ES) media from an integrated aerosol collector is introduced into a small, reduced pressure chamber, where a focused pulsed laser vaporizes material from a 10 to 20-(micro)m diameter spot of the surface of the sampling media. The plume of ejected material begins as high-temperature plasma that yields ions and atoms, as well as molecules and molecular ions. We concentrate on the plume of atomic vapor that remains after the plasma has expanded and then cooled by the surrounding cover gas. Tunable diode lasers are directed through this plume and each isotope is detected by monitoring absorbance

  12. Defects in degraded GaN-based laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Tomiya, Shigetaka [Materials Analysis Center, GPS, Sony Corporation, 2-1-1 Shin-sakuragaoka, Hodogaya, Yokohama, Kanagawa, 240-0036 (Japan); Goto, Shu; Takeya, Motonobu; Ikeda, Masao [Development Center, Sony Shiroishi Semiconductor, Inc., 3-53-2 Shiratori, Shiroishi, Miyagi, 989-0734 (Japan)

    2003-11-01

    We investigate degraded GaN-based laser diodes (LDs) fabricated on epitaxial lateral overgrown (ELO) GaN layers using transmission electron microscopy. The dislocation density in the wing region of the ELO is of the order of 10{sup 6}/cm{sup 2} and there are approximately ten threading dislocations in the laser stripe. Neither dislocation multiplication from the threading dislocations nor any structural changes of the threading dislocations were observed in the devices, which were degraded within approximately one hundred hours under 30 mW continuous operation at 25 C. We can, therefore, conclude that degradation in GaN-based LDs is not responsible for the recombination enhanced dislocation motion that is usually observed in zincblende structure-based LDs. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Kinetic analysis of isobutane/butene alkylation over ultrastable H-Y zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, M.F.; Wei, J.; Sundaresan, S. [Princeton Univ., NJ (United States). Dept. of Chemical Engineering

    1996-11-01

    The alkylation of isobutane with trans-2-butene over ultrastable Y-type zeolites has been studied. It is well-known that this reaction is accompanied by a rapid deactivation of the catalyst. The objective of this study is to elucidate the route to catalyst deactivation so that the means of mitigating this problem can be identified. Using the initial reaction rate data, evidence has been found for a Broensted acid mechanism. Under liquid-phase conditions, the reaction has been found to be severely diffusion limited. Using a kinetic model that accounts for the effect of diffusion, it was found that alkylation over this catalyst suffers from slow hydride transfer relative to olefin addition. This gives rise to a rapid formation of C{sub 12}{sup +} carbocations. The formation of these cations has been tied to catalyst deactivation, using a mathematical model for the reaction. On the basis of the insight gained from the experiments and modeling work, optimal reactor and catalyst design issues are examined. It is inferred from the reaction mechanism and confirmed experimentally that alkylation under pulsed flow conditions yields higher trimethylpentane/dimethylhexane ratios and slower rates of deactivation. It is suggested that the cause of the slow rate of hydride transfer is steric hindrance. Strategies for relieving this steric hindrance are proposed.

  14. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-30

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  15. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-01

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  16. Experimental and rendering-based investigation of laser radar cross sections of small unmanned aerial vehicles

    Science.gov (United States)

    Laurenzis, Martin; Bacher, Emmanuel; Christnacher, Frank

    2017-12-01

    Laser imaging systems are prominent candidates for detection and tracking of small unmanned aerial vehicles (UAVs) in current and future security scenarios. Laser reflection characteristics for laser imaging (e.g., laser gated viewing) of small UAVs are investigated to determine their laser radar cross section (LRCS) by analyzing the intensity distribution of laser reflection in high resolution images. For the first time, LRCSs are determined in a combined experimental and computational approaches by high resolution laser gated viewing and three-dimensional rendering. An optimized simple surface model is calculated taking into account diffuse and specular reflectance properties based on the Oren-Nayar and the Cook-Torrance reflectance models, respectively.

  17. Optically-Based Diagnostics for Gas-Phase Laser Development

    Science.gov (United States)

    2010-08-01

    Laser (COIL), Electric Oxygen Iodine Laser (EOIL), Diode-Pumped Alkali Laser (DPAL), and Exciplex Alkali Laser (XPAL). The papers at this Symposium... exciplex -assisted absorption and laser-induced fluorescence, and multi-photon excitation of infrared atomic alkali transitions.11,12 In this paper... EXCIPLEX LASER SYSTEMS Proper review and discussion of the DPAL and XPAL laser systems can be found elsewhere,11,12 and in the paper by Carroll and

  18. Laser-based gluing of diamond-tipped saw blades

    Science.gov (United States)

    Hennigs, Christian; Lahdo, Rabi; Springer, André; Kaierle, Stefan; Hustedt, Michael; Brand, Helmut; Wloka, Richard; Zobel, Frank; Dültgen, Peter

    2016-03-01

    To process natural stone such as marble or granite, saw blades equipped with wear-resistant diamond grinding segments are used, typically joined to the blade by brazing. In case of damage or wear, they must be exchanged. Due to the large energy input during thermal loosening and subsequent brazing, the repair causes extended heat-affected zones with serious microstructure changes, resulting in shape distortions and disadvantageous stress distributions. Consequently, axial run-out deviations and cutting losses increase. In this work, a new near-infrared laser-based process chain is presented to overcome the deficits of conventional brazing-based repair of diamond-tipped steel saw blades. Thus, additional tensioning and straightening steps can be avoided. The process chain starts with thermal debonding of the worn grinding segments, using a continuous-wave laser to heat the segments gently and to exceed the adhesive's decomposition temperature. Afterwards, short-pulsed laser radiation removes remaining adhesive from the blade in order to achieve clean joining surfaces. The third step is roughening and activation of the joining surfaces, again using short-pulsed laser radiation. Finally, the grinding segments are glued onto the blade with a defined adhesive layer, using continuous-wave laser radiation. Here, the adhesive is heated to its curing temperature by irradiating the respective grinding segment, ensuring minimal thermal influence on the blade. For demonstration, a prototype unit was constructed to perform the different steps of the process chain on-site at the saw-blade user's facilities. This unit was used to re-equip a saw blade with a complete set of grinding segments. This saw blade was used successfully to cut different materials, amongst others granite.

  19. Si-Based Germanium Tin Semiconductor Lasers for Optoelectronic Applications

    Science.gov (United States)

    Al-Kabi, Sattar H. Sweilim

    Silicon-based materials and optoelectronic devices are of great interest as they could be monolithically integrated in the current Si complementary metal-oxide-semiconductor (CMOS) processes. The integration of optoelectronic components on the CMOS platform has long been limited due to the unavailability of Si-based laser sources. A Si-based monolithic laser is highly desirable for full integration of Si photonics chip. In this work, Si-based germanium-tin (GeSn) lasers have been demonstrated as direct bandgap group-IV laser sources. This opens a completely new avenue from the traditional III-V integration approach. In this work, the material and optical properties of GeSn alloys were comprehensively studied. The GeSn films were grown on Ge-buffered Si substrates in a reduced pressure chemical vapor deposition system with low-cost SnCl4 and GeH4 precursors. A systematic study was done for thin GeSn films (thickness 400 nm) with Sn composition 5 to 17.5%. The room temperature photoluminescence (PL) spectra were measured that showed a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Strong PL intensity and low defect density indicated high material quality. Moreover, the PL study of n-doped samples showed bandgap narrowing compared to the unintentionally p-doped (boron) thin films with similar Sn compositions. Finally, optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 mum were demonstrated using high-quality GeSn films with Sn compositions up to 17.5%. The achieved maximum Sn composition of 17.5% broke the acknowledged Sn incorporation limit using similar deposition chemistry. The highest lasing temperature was measured at 180 K with an active layer thickness as thin as 270 nm. The unprecedented lasing performance is due to the achievement of high material quality and a robust fabrication process. The results reported in this work show a major advancement towards Si-based electrically pumped mid

  20. Laser-based gas sensors keep moisture out of pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2006-07-15

    Natural gas often contains contaminants that cause corrosion, and long-term deterioration, and must be cleaned and brought to pipeline standards before it can be delivered to high-pressure, long-distance pipelines. Many older sensors produce false data that can result in contaminated gas getting through. This article presented details of the SpectraSensor, a new laser-based sensor technology used by the El Paso Natural Gas Company (EPNG). The SpectraSensor is comprised of a tunable diode laser (TDL) based technology developed by the National American Space Agency (NASA). The gas analyzer provides non-contact measurement of moisture, carbon dioxide, and other corrosives in natural gas pipelines, and the tunable laser-based gas sensors are fast, accurate, and flexible. Producers can monitor El Paso's gas analyzer readings by capturing the electronic signal from El Paso's unit via a SCADA system and view the readings from control rooms. While initial purchase price is higher than more problematic surface-based gas sensors, an evaluation of the technology has indicated that maintenance savings alone may provide an almost immediate return on investments. Unlike electrochemical and crystal gas sensors, laser-based gas analyzers do not come into direct contact with any substances, a fact which practically eliminates maintenance and operational costs. Studies have shown that the cost of operating conventional electrochemical sensors can result in a cumulative annual expense exceeding $50,000 per unit including labour; recalibration and rebuilding; back-up sensor heads; and gas dehydration and tariffs. 1 fig.

  1. Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

    Science.gov (United States)

    Woodruff, Steven D.; Mcintyre, Dustin L.

    2016-03-29

    A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

  2. Research on laser detonation pulse circuit with low-power based on super capacitor

    Science.gov (United States)

    Wang, Hao-yu; Hong, Jin; He, Aifeng; Jing, Bo; Cao, Chun-qiang; Ma, Yue; Chu, En-yi; Hu, Ya-dong

    2018-03-01

    According to the demand of laser initiating device miniaturization and low power consumption of weapon system, research on the low power pulse laser detonation circuit with super capacitor. Established a dynamic model of laser output based on super capacitance storage capacity, discharge voltage and programmable output pulse width. The output performance of the super capacitor under different energy storage capacity and discharge voltage is obtained by simulation. The experimental test system was set up, and the laser diode of low power pulsed laser detonation circuit was tested and the laser output waveform of laser diode in different energy storage capacity and discharge voltage was collected. Experiments show that low power pulse laser detonation based on super capacitor energy storage circuit discharge with high efficiency, good transient performance, for a low power consumption requirement, for laser detonation system and low power consumption and provide reference light miniaturization of engineering practice.

  3. Diode laser based light sources for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André; Marschall, Sebastian; Jensen, Ole Bjarlin

    2013-01-01

    Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode...... imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications....

  4. Efficiency of crystalline laser materials based on lanthanides

    International Nuclear Information System (INIS)

    Synek, M.

    1990-01-01

    Lanthanide-based laser-crystal efficiency has been investigated, using the laser-active ions Dy 2+ and Nd 3+ as significant illustrations. Authors' calculations, and various approaches by other authors, are reviewed. In specific examples of treatment, the analytical self-consistent field(SCF) expansion method has been used to calculate accurate ab initio wave functions and energy levels for a number of excited states of Nd 3+ and Dy 2+ , which were investigated for the first time. General group-theoretical principles were considered and the formulae for crystal-field parameters were obtained. The Racah quantum numbers were included in these calculations, in fact showing sizeable energy effects. Oscillator strengths, calculated from the SCF wave functions, revealed which orbitals can be neglected without influencing the transition probability at the fourth significant figure. The relationship to the spectral character of the pumping device was considered. The efficiency parameters (mechanical, economic, and energetic) have to be considered as supplementing the related threshold energy parameter. It would be conceivable to predict the applicability of competing laser systems to a specific task, based on integrated energy pictures. (author). 32 refs., 2 tabs

  5. Fusion--fission hybrid reactors based on the laser solenoid

    International Nuclear Information System (INIS)

    Steinhauer, L.C.; Taussig, R.T.; Quimby, D.C.

    1976-01-01

    Fusion-fission reactors, based on the laser solenoid concept, can be much smaller in scale than their pure fusion counterparts, with moderate first-wall loading and rapid breeding capabilities (1 to 3 tonnes/yr), and can be designed successfully on the basis of classical plasma transport properties and free-streaming end-loss. Preliminary design information is presented for such systems, including the first wall, pulse coil, blanket, superconductors, laser optics, and power supplies, accounting for the desired reactor performance and other physics and engineering constraints. Self-consistent point designs for first and second generation reactors are discussed which illustrate the reactor size, performance, component parameters, and the level of technological development required

  6. EUS-Guided Needle-Based Confocal Laser Endomicroscopy

    DEFF Research Database (Denmark)

    Bhutani, Manoop S; Koduru, Pramoda; Joshi, Virendra

    2015-01-01

    Endoscopic ultrasound (EUS) has emerged as an excellent tool for imaging the gastrointestinal tract, as well as surrounding structures. EUS-guided fine-needle aspiration (EUS-FNA) has become the standard of care for the tissue sampling of a variety of masses and lymph nodes within and around...... the gut, providing further diagnostic and staging information. Confocal laser endomicroscopy (CLE) is a novel endoscopic method that enables imaging at a subcellular level of resolution during endoscopy, allowing up to 1000-fold magnification of tissue and providing an optical biopsy. A new procedure...... that has been developed in the past few years is needle-based confocal laser endomicroscopy (nCLE), which involves a mini-CLE probe that can be passed through a 1 9-gauge needle during EUS-FNA. This enables the real-time visualization of tissue at a microscopic level, with the potential to further improve...

  7. Designing and testing a laser-based vibratory sensor

    Science.gov (United States)

    Nath, G.

    2018-04-01

    Sensor technology has proved its importance, not only in the range of few-meter applications in different fields, but in micro, nano, atomic and sub-atomic-sized objects. The present work describes the designing of a laser-based vibratory sensor using a He-Ne laser as the signal source. The received characteristics of the signal are mainly the frequency and amplitude of the vibration from which the physical parameters such as energy, power and absorption coefficients of the material are determined, which enables us to provide information of the hidden target or object. This laboratory-designed sensor finds application in different local phenomena as well as laboratory practical activity for students.

  8. Modeling of photoluminescence in laser-based lighting systems

    Science.gov (United States)

    Chatzizyrli, Elisavet; Tinne, Nadine; Lachmayer, Roland; Neumann, Jörg; Kracht, Dietmar

    2017-12-01

    The development of laser-based lighting systems has been the latest step towards a revolution in illumination technology brought about by solid-state lighting. Laser-activated remote phosphor systems produce white light sources with significantly higher luminance than LEDs. The weak point of such systems is often considered to be the conversion element. The high-intensity exciting laser beam in combination with the limited thermal conductivity of ceramic phosphor materials leads to thermal quenching, the phenomenon in which the emission efficiency decreases as temperature rises. For this reason, the aim of the presented study is the modeling of remote phosphor systems in order to investigate their thermal limitations and to calculate the parameters for optimizing the efficiency of such systems. The common approach to simulate remote phosphor systems utilizes a combination of different tools such as ray tracing algorithms and wave optics tools for describing the incident and converted light, whereas the modeling of the conversion process itself, i.e. photoluminescence, in most cases is circumvented by using the absorption and emission spectra of the phosphor material. In this study, we describe the processes involved in luminescence quantum-mechanically using the single-configurational-coordinate diagram as well as the Franck-Condon principle and propose a simulation model that incorporates the temperature dependence of these processes. Following an increasing awareness of climate change and environmental issues, the development of ecologically friendly lighting systems featuring low power consumption and high luminous efficiency is imperative more than ever. The better understanding of laser-based lighting systems is an important step towards that aim as they may improve on LEDs in the near future.

  9. Lasers

    CERN Document Server

    Milonni, Peter W

    1988-01-01

    A comprehensive introduction to the operating principles and applications of lasers. Explains basic principles, including the necessary elements of classical and quantum physics. Provides concise discussions of various laser types including gas, solid state, semiconductor, and free electron lasers, as well as of laser resonators, diffraction, optical coherence, and many applications including holography, phase conjugation, wave mixing, and nonlinear optics. Incorporates many intuitive explanations and practical examples. Discussions are self-contained in a consistent notation and in a style that should appeal to physicists, chemists, optical scientists and engineers.

  10. Laser plant "Iguana" for transmyocardial revascularization based on kW-level waveguide CO2 laser

    Science.gov (United States)

    Panchenko, Vladislav Y.; Bockeria, L. A.; Berishvili, I. I.; Vasiltsov, Victor V.; Golubev, Vladimir S.; Ul'yanov, Valery A.

    2001-05-01

    For many years the Institute on Laser and Information Technologies RAN has been developing a concept of high-power industrial CO2 lasers with diffusion cooling of the working medium. The paper gives a description of the laser medical system Iguana for transmyocardial laser revascularization (TMLR) as an example of various applications of high-power waveguide CO2 lasers. The clinical results of the TMLR method application in surgical treatment are presented. The methods of determination of the time, when the laser beam passes through the demarcation line between myocardium tissue and blood, are discussed.

  11. Laser-plasma based electron acceleration studies planned at CAT, Indore

    International Nuclear Information System (INIS)

    Naik, P.A.; Gupta, P.D.

    2005-01-01

    The Laser Plasma Division at the Centre for Advanced Technology is engaged in a variety of R and D activities on laser-plasma interaction with special emphasis on laser-matter interaction at ultra-high intensities. An important aspect of our future work is studies in laser-plasma based acceleration using an elaborate infrastructural set-up of ultra-fast laser and plasma diagnostic systems and recently acquired 10 TW, 50 fs Ti: Sapphire laser system. This paper presents outline of the planned studies in this field. (author)

  12. Land-Based Mobile Laser Scanning Systems: a Review

    Science.gov (United States)

    Puente, I.; González-Jorge, H.; Arias, P.; Armesto, J.

    2011-09-01

    Mobile mapping has been using various photogrammetric techniques for many years. In recent years, there has been an increase in the number of mobile mapping systems using laser scanners available in the market, partially because of the improvement in GNSS/INS performance for direct georeferencing. In this article, some of the most important land-based mobile laser scanning (MLS) systems are reviewed. Firstly, the main characteristics of MLS systems vs. airborne (ALS) and terrestrial laser scanning (TLS) systems are compared. Secondly, a short overview of the mobile mapping technology is also provided so that the reader can fully grasp the complexity and operation of these devices. As we put forward in this paper, a comparison of different systems is briefly carried out regarding specifications provided by the manufacturers. Focuses on the current research are also addressed with emphasis on the practical applications of these systems. Most of them have been utilized for data collection on road infrastructures or building façades. This article shows that MLS technology is nowadays well established and proven, since the demand has grown to the point that there are several systems suppliers offering their products to satisfy this particular market.

  13. Detecting Molecular Properties by Various Laser-Based Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hsin, Tse-Ming [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Four different laser-based techniques were applied to study physical and chemical characteristics of biomolecules and dye molecules. These techniques are liole burning spectroscopy, single molecule spectroscopy, time-resolved coherent anti-Stokes Raman spectroscopy and laser-induced fluorescence microscopy. Results from hole burning and single molecule spectroscopy suggested that two antenna states (C708 & C714) of photosystem I from cyanobacterium Synechocystis PCC 6803 are connected by effective energy transfer and the corresponding energy transfer time is ~6 ps. In addition, results from hole burning spectroscopy indicated that the chlorophyll dimer of the C714 state has a large distribution of the dimer geometry. Direct observation of vibrational peaks and evolution of coumarin 153 in the electronic excited state was demonstrated by using the fs/ps CARS, a variation of time-resolved coherent anti-Stokes Raman spectroscopy. In three different solvents, methanol, acetonitrile, and butanol, a vibration peak related to the stretch of the carbonyl group exhibits different relaxation dynamics. Laser-induced fluorescence microscopy, along with the biomimetic containers-liposomes, allows the measurement of the enzymatic activity of individual alkaline phosphatase from bovine intestinal mucosa without potential interferences from glass surfaces. The result showed a wide distribution of the enzyme reactivity. Protein structural variation is one of the major reasons that are responsible for this highly heterogeneous behavior.

  14. Laser assisted anticancer activity of benzimidazole based metal organic nanoparticles.

    Science.gov (United States)

    Praveen, P A; Ramesh Babu, R; Balaji, P; Murugadas, A; Akbarsha, M A

    2018-03-01

    Recent studies showed that the photothermal therapy can be effectively used for the targeted cancerous cells destruction. Hence, in the present study, benzimidazole based metal organic complex nanoparticles, dichloro cobalt(II) bis-benzimidazole (Co-BMZ) and dichloro copper(II) bis-benzimidazole (Cu-BMZ), were synthesized by reprecipitation method and their anti-cancer activity by means of photothermal effect has been studied. Transmission electron microscopy analysis shows that the particle size of Cu-BMZ is ∼100 nm and Co-BMZ is in the range between 100 and 400 nm. Zeta potential analysis ensures the stability of the synthesized nanoparticles. It is found that the nonlinear absorption of the nanoparticles increases with increase in laser power intensity. Phototoxicity of human lung cancer (A549) and the normal mouse embryonic fibroblast (NIH-3T3) cells was studied using a 650 nm laser. Even though both the cell lines were affected by laser irradiation, A549 cells show higher cell destruction and lower IC 50 values than the normal cells. Docking studies were used to analyse the interaction site and the results showed that the Cu-BMZ molecules have higher dock score than the Co-BMZ molecules. The obtained results indicate that Cu-BMZ samples have lesser particle size, higher nonlinear absorption and higher interaction energy than the Co-BMZ samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Compact green-diode-based lasers for biophotonic bioimaging

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Petersen, Paul Michael

    2014-01-01

    Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers.......Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers....

  16. Cost of space-based laser ballistic missile defense.

    Science.gov (United States)

    Field, G; Spergel, D

    1986-03-21

    Orbiting platforms carrying infrared lasers have been proposed as weapons forming the first tier of a ballistic missile defense system under the President's Strategic Defense Initiative. As each laser platform can destroy a limited number of missiles, one of several methods of countering such a system is to increase the number of offensive missiles. Hence it is important to know whether the cost-exchange ratio, defined as the ratio of the cost to the defense of destroying a missile to the cost to the offense of deploying an additional missile, is greater or less than 1. Although the technology to be used in a ballistic missile defense system is still extremely uncertain, it is useful to examine methods for calculating the cost-exchange ratio. As an example, the cost of an orbiting infrared laser ballistic missile defense system employed against intercontinental ballistic missiles launched simultaneously from a small area is compared to the cost of additional offensive missiles. If one adopts lower limits to the costs for the defense and upper limits to the costs for the offense, the cost-exchange ratio comes out substantially greater than 1. If these estimates are confirmed, such a ballistic missile defense system would be unable to maintain its effectiveness at less cost than it would take to proliferate the ballistic missiles necessary to overcome it and would therefore not satisfy the President's requirements for an effective strategic defense. Although the method is illustrated by applying it to a space-based infrared laser system, it should be straightforward to apply it to other proposed systems.

  17. Seam gap bridging of laser based processes for the welding of aluminium sheets for industrial applications

    NARCIS (Netherlands)

    Aalderink, B.J.; Aalderink, Benno; Pathiraj, B.; Aarts, Ronald G.K.M.

    2010-01-01

    Laser welding has a large potential for the production of tailor welded blanks in the automotive industry, due to the low heat input and deep penetration. However, due to the small laser spot and melt pool, laser-based welding processes in general have a low tolerance for seam gaps. In this paper,

  18. Development of semiconductor laser based Doppler lidars for wind-sensing applications

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Hu, Qi; Pedersen, Christian

    2015-01-01

    We summarize the progress we have made in the development of semiconductor laser (SL) based Doppler lidar systems for remote wind speed and direction measurements. The SL emitter used in our wind-sensing lidar is an integrated diode laser with a tapered (semiconductor) amplifier. The laser source...

  19. Random fiber lasers based on artificially controlled backscattering fibers

    Science.gov (United States)

    Chen, Daru; Wang, Xiaoliang; She, Lijuan; Qiang, Zexuan; Yu, Zhangwei

    2017-10-01

    The random fiber laser (RFL) which is a milestone in laser physics and nonlinear optics, has attracted considerable attention recently. Most previous RFLs are based on distributed feedback of Rayleigh scattering amplified through stimulated Raman/Brillouin scattering effect in single mode fibers, which required long-distance (tens of kilometers) single mode fibers and high threshold up to watt-level due to the extremely small Rayleigh scattering coefficient of the fiber. We proposed and demonstrated a half-open cavity RFL based on a segment of a artificially controlled backscattering SMF(ACB-SMF) with a length of 210m, 310m or 390m. A fiber Bragg grating with the central wavelength of 1530nm and a segment of ACB-SMF forms the half-open cavity. The proposed RFL achieves the threshold of 25mW, 30mW and 30mW, respectively. Random lasing at the wavelength of 1530nm and the extinction ratio of 50dB is achieved when a segment of 5m EDF is pumped by a 980nm LD in the RFL. Another half-open cavity RFL based on a segment of a artificially controlled backscattering EDF(ACBS-EDF) is also demonstrated without an ACB-SMF. The 3m ACB-EDF is fabricated by using the femtosecond laser with pulse energy of 0.34mJ which introduces about 50 reflectors in the EDF. Random lasing at the wavelength of 1530nm is achieved with the output power of 7.5mW and the efficiency of 1.88%. Two novel RFLs with much short cavities have been achieved with low threshold and high efficiency.

  20. Optical Fiber Sensing Based on Reflection Laser Spectroscopy

    Directory of Open Access Journals (Sweden)

    Gianluca Gagliardi

    2010-03-01

    Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

  1. Laser-induced production of large carbon-based toroids

    International Nuclear Information System (INIS)

    Lyn, M. Elizabeth; He Jibao; Koplitz, Brent

    2005-01-01

    We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C 60 , 22% C 70 ). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2-0.3 μm with tubular diameters of ∼50-100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures

  2. Thermal crosstalk in arrays of III-N-based Lasers

    International Nuclear Information System (INIS)

    Kuc, Maciej; Sarzała, Robert P.; Nakwaski, Włodzimierz

    2013-01-01

    This paper presents a 3D comprehensive thermal-electrical self-consistent model of the continuous-wave (CW) operation of one-dimensional arrays of III-N-based laser diodes at room-temperature (RT). Their performance is mostly limited by thermal processes, in particular by thermal crosstalk between array emitters. Based on data collected from a range of secondary sources, the temperature dependence of the thermal and electrical conductivities of III-N materials used to manufacture nitride-based devices is shown to be a function of the thickness, aluminum mole fractions and Si- and Mg-doping levels of the nitride layers. The impact of substrate width and thickness on increasing the efficiency of heat-flux transport and reducing thermal crosstalk is investigated. As expected, the application of a top-mounted diamond heat spreader was found to have considerable influence on the thermal crosstalk between array emitters, enabling the RT CW operation of laser diode arrays with additional emitters

  3. A New Laser Based Approach for Measuring Atmospheric Greenhouse Gases

    Directory of Open Access Journals (Sweden)

    Jeremy Dobler

    2013-11-01

    Full Text Available In 2012, we developed a proof-of-concept system for a new open-path laser absorption spectrometer concept for measuring atmospheric CO2. The measurement approach utilizes high-reliability all-fiber-based, continuous-wave laser technology, along with a unique all-digital lock-in amplifier method that, together, enables simultaneous transmission and reception of multiple fixed wavelengths of light. This new technique, which utilizes very little transmitted energy relative to conventional lidar systems, provides high signal-to-noise (SNR measurements, even in the presence of a large background signal. This proof-of-concept system, tested in both a laboratory environment and a limited number of field experiments over path lengths of 680 m and 1,600 m, demonstrated SNR values >1,000 for received signals of ~18 picoWatts averaged over 60 s. A SNR of 1,000 is equivalent to a measurement precision of ±0.001 or ~0.4 ppmv. The measurement method is expected to provide new capability for automated monitoring of greenhouse gas at fixed sites, such as carbon sequestration facilities, volcanoes, the short- and long-term assessment of urban plumes, and other similar applications. In addition, this concept enables active measurements of column amounts from a geosynchronous orbit for a network of ground-based receivers/stations that would complement other current and planned space-based measurement capabilities.

  4. Compact blue laser devices based on nonlinear frequency upconversion

    International Nuclear Information System (INIS)

    Risk, W.P.

    1989-01-01

    This paper reports how miniature sources of coherent blue radiation can be produced by using nonlinear optical materials for frequency upconversion of the infrared radiation emitted by laser diodes. Direct upconversion of laser diode radiation is possible, but there are several advantages to using the diode laser to pump a solid-state laser which is then upconverted. In either case, the challenge is to find combinations of nonlinear materials and laser for efficient frequency upconversion. Several examples have been demonstrated. These include intracavity frequency doubling of a diode-pumped 946-nm Nd:YAG laser, intracavity frequency mixing of a 809-nm GaAlAs laser diode with a diode- pumped 1064-nm Nd:YAG laser, and direct frequency doubling of a 994-nm strained-layer InGaAs laser diode

  5. Qualification testing of fiber-based laser transmitters and on-orbit validation of a commercial laser system

    Science.gov (United States)

    Wright, M. W.; Wilkerson, M. W.; Tang, R. R.

    2017-11-01

    Qualification testing of fiber based laser transmitters is required for NASA's Deep Space Optical Communications program to mature the technology for space applications. In the absence of fully space qualified systems, commercial systems have been investigated in order to demonstrate the robustness of the technology. To this end, a 2.5 W fiber based laser source was developed as the transmitter for an optical communications experiment flown aboard the ISS as a part of a technology demonstration mission. The low cost system leveraged Mil Standard design principles and Telcordia certified components to the extent possible and was operated in a pressure vessel with active cooling. The laser was capable of high rate modulation but was limited by the mission requirements to 50 Mbps for downlinking stored video from the OPALS payload, externally mounted on the ISS. Environmental testing and space qualification of this unit will be discussed along with plans for a fully space qualified laser transmitter.

  6. High-level PC-based laser system modeling

    Science.gov (United States)

    Taylor, Michael S.

    1991-05-01

    Since the inception of the Strategic Defense Initiative (SDI) there have been a multitude of comparison studies done in an attempt to evaluate the effectiveness and relative sizes of complementary, and sometimes competitive, laser weapon systems. It became more and more apparent that what the systems analyst needed was not only a fast, but a cost effective way to perform high-level trade studies. In the present investigation, a general procedure is presented for the development of PC-based algorithmic systems models for laser systems. This procedure points out all of the major issues that should be addressed in the design and development of such a model. Issues addressed include defining the problem to be modeled, defining a strategy for development, and finally, effective use of the model once developed. Being a general procedure, it will allow a systems analyst to develop a model to meet specific needs. To illustrate this method of model development, a description of the Strategic Defense Simulation - Design To (SDS-DT) model developed and used by Science Applications International Corporation (SAIC) is presented. SDS-DT is a menu-driven, fast executing, PC-based program that can be used to either calculate performance, weight, volume, and cost values for a particular design or, alternatively, to run parametrics on particular system parameters to perhaps optimize a design.

  7. Non-Contact Laser Based Ultrasound Evaluation of Canned Foods

    Science.gov (United States)

    Shelton, David

    2005-03-01

    Laser-Based Ultrasound detection was used to measure the velocity of compression waves transmitted through canned foods. Condensed broth, canned pasta, and non-condensed soup were evaluated in these experiments. Homodyne adaptive optics resulted in measurements that were more accurate than the traditional heterodyne method, as well as yielding a 10 dB gain in signal to noise. A-Scans measured the velocity of ultrasound sent through the center of the can and were able to distinguish the quantity of food stuff in its path, as well as distinguish between meat and potato. B-Scans investigated the heterogeneity of the sample’s contents. The evaluation of canned foods was completely non-contact and would be suitable for continuous monitoring in production. These results were verified by conducting the same experiments with a contact piezo transducer. Although the contact method yields a higher signal to noise ratio than the non-contact method, Laser-Based Ultrasound was able to detect surface waves the contact transducer could not.

  8. Laser-based analytical monitoring in nuclear-fuel processing plants

    International Nuclear Information System (INIS)

    Hohimer, J.P.

    1978-09-01

    The use of laser-based analytical methods in nuclear-fuel processing plants is considered. The species and locations for accountability, process control, and effluent control measurements in the Coprocessing, Thorex, and reference Purex fuel processing operations are identified and the conventional analytical methods used for these measurements are summarized. The laser analytical methods based upon Raman, absorption, fluorescence, and nonlinear spectroscopy are reviewed and evaluated for their use in fuel processing plants. After a comparison of the capabilities of the laser-based and conventional analytical methods, the promising areas of application of the laser-based methods in fuel processing plants are identified

  9. Accurate Alignment of Plasma Channels Based on Laser Centroid Oscillations

    International Nuclear Information System (INIS)

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Osterhoff, Jens; Shiraishi, Satomi; Schroeder, Carl; Geddes, Cameron; Toth, Csaba; Esarey, Eric; Leemans, Wim

    2011-01-01

    A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the shift in laser centroid and angle at the channel outptut. If only the shift in centroid or angle is measured, then accurate alignment is provided by minimizing laser centroid motion at the channel exit as the channel properties are scanned. The improvement in alignment accuracy provided by this technique is important for minimizing electron beam pointing errors in laser plasma accelerators.

  10. Performance of RGB laser-based projection for video walls

    Science.gov (United States)

    Hickl, Peter

    2018-02-01

    The laser phosphor concept is currently the common approach for most applications to introduce laser as a projection light source. However, this concept bears quite some disadvantages for rear-projection video walls. Therefore, Barco has developed a RGB laser design for use in the control room market with tailor-made performance.

  11. COHERENT LIDAR SYSTEM BASED ON A SEMICONDUCTOR LASER AND AMPLIFIER

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to a compact, reliable and low-cost coherent LIDAR (Light Detection And Ranging) system for remote wind-speed determination, determination of particle concentration, and/or temperature based on an all semiconductor light source and related methods. The present...... invention provides a coherent LIDAR system comprising a semiconductor laser for emission of a measurement beam of electromagnetic radiation directed towards a measurement volume for illumination of particles in the measurement volume, a reference beam generator for generation of a reference beam, a detector...... for generation of a detector signal by mixing of the reference beam with light emitted from the particles in the measurement volume illuminated by the measurement beam, and a signal processor for generating a velocity signal corresponding to the velocity of the particles based on the detector signal....

  12. Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology.

    Science.gov (United States)

    Xie, Wen-Ge; Zhang, Ya-Nan; Wang, Peng-Zhao; Wang, Jian-Zhang

    2018-02-08

    A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach-Zehnder interferometer (MZI) typed sensors, Fabry-Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed.

  13. GaN-Based Laser Wireless Power Transfer System

    Directory of Open Access Journals (Sweden)

    Carlo De Santi

    2018-01-01

    Full Text Available The aim of this work is to present a potential application of gallium nitride-based optoelectronic devices. By using a laser diode and a photodetector, we designed and demonstrated a free-space compact and lightweight wireless power transfer system, whose efficiency is limited by the efficiency of the receiver. We analyzed the effect of the electrical load, temperature, partial absorption and optical excitation distribution on the efficiency, by identifying heating and band-filling as the most impactful processes. By comparing the final demonstrator with a commercial RF-based Qi system, we conclude that the efficiency is still low at close range, but is promising in medium to long range applications. Efficiency may not be a limiting factor, since this concept can enable entirely new possibilities and designs, especially relevant for space applications.

  14. Image Blocking Encryption Algorithm Based on Laser Chaos Synchronization

    Directory of Open Access Journals (Sweden)

    Shu-Ying Wang

    2016-01-01

    Full Text Available In view of the digital image transmission security, based on laser chaos synchronization and Arnold cat map, a novel image encryption scheme is proposed. Based on pixel values of plain image a parameter is generated to influence the secret key. Sequences of the drive system and response system are pretreated by the same method and make image blocking encryption scheme for plain image. Finally, pixels position are scrambled by general Arnold transformation. In decryption process, the chaotic synchronization accuracy is fully considered and the relationship between the effect of synchronization and decryption is analyzed, which has characteristics of high precision, higher efficiency, simplicity, flexibility, and better controllability. The experimental results show that the encryption algorithm image has high security and good antijamming performance.

  15. Circumvention of noise contributions in fiber laser based frequency combs.

    Science.gov (United States)

    Benkler, Erik; Telle, Harald; Zach, Armin; Tauser, Florian

    2005-07-25

    We investigate the performance of an Er:fiber laser based femtosecond frequency comb for precision metrological applications. Instead of an active stabilization of the comb, the fluctuations of the carrier-envelope offset phase, the repetition phase, and the phase of the beat from a comb line with an optical reference are synchronously detected. We show that these fluctuations can be effectively eliminated by exploiting their known correlation. In our experimental scheme, we utilize two identically constructed frequency combs for the measurement of the fluctuations, rejecting the influence of a shared optical reference. From measuring a white frequency noise level, we demonstrate that a fractional frequency instability better than 1.4 x 10(-14) for 1 s averaging time can be achieved in frequency metrology applications using the Er:fiber based frequency comb.

  16. Nature-Inspired 2D-Mosaic 3D-Gradient Mesoporous Framework: Bimetal Oxide Dual-Composite Strategy toward Ultrastable and High-Capacity Lithium Storage.

    Science.gov (United States)

    Yu, Jia; Wang, Yanlei; Mou, Lihui; Fang, Daliang; Chen, Shimou; Zhang, Suojiang

    2018-02-27

    In allusion to traditional transition-metal oxide (TMO) anodes for lithium-ion batteries, which face severe volume variation and poor conductivity, herein a bimetal oxide dual-composite strategy based on two-dimensional (2D)-mosaic three-dimensional (3D)-gradient design is proposed. Inspired by natural mosaic dominance phenomena, Zn 1-x Co x O/ZnCo 2 O 4 2D-mosaic-hybrid mesoporous ultrathin nanosheets serve as building blocks to assemble into a 3D Zn-Co hierarchical framework. Moreover, a series of derivative frameworks with high evolution are controllably synthesized, based on which a facile one-pot synthesis process can be developed. From a component-composite perspective, both Zn 1-x Co x O and ZnCo 2 O 4 provide superior conductivity due to bimetal doping effect, which is verified by density functional theory calculations. From a structure-composite perspective, 2D-mosaic-hybrid mode gives rise to ladder-type buffering and electrochemical synergistic effect, thus realizing mutual stabilization and activation between the mosaic pair, especially for Zn 1-x Co x O with higher capacity yet higher expansion. Moreover, the inside-out Zn-Co concentration gradient in 3D framework and rich oxygen vacancies further greatly enhance Li storage capability and stability. As a result, a high reversible capacity (1010 mA h g -1 ) and areal capacity (1.48 mA h cm -2 ) are attained, while ultrastable cyclability is obtained during high-rate and long-term cycles, rending great potential of our 2D-mosaic 3D-gradient design together with facile synthesis.

  17. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang [Keio University, Department of Mechanical Engineering, Faculty of Science and Technology, Yokohama (Japan)

    2016-10-15

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN. (orig.)

  18. Single-mode fiber laser based on core-cladding mode conversion.

    Science.gov (United States)

    Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

    2008-02-15

    A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

  19. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Science.gov (United States)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang

    2016-10-01

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN.

  20. Dental hard tissue characterization using laser-based ultrasonics

    Science.gov (United States)

    Blodgett, David W.; Massey, Ward L.

    2003-07-01

    Dental health care and research workers require a means of imaging the structures within teeth in vivo. One critical need is the detection of tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help re-mineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, non-destructive and non-contact in vitro measurements on extracted human molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements in accomplished with a path-stabilized Michelson-type interferometer. Results for bulk and surface in-vitro characterization of caries are presented on extracted molars with pre-existing caries.

  1. Beam Diagnostics for Laser Undulator Based on Compton Backward Scattering

    CERN Document Server

    Kuroda, R

    2005-01-01

    A compact soft X-ray source is required in various research fields such as material and biological science. The laser undulator based on Compton backward scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. It is performed in a water window region (250eV - 500 eV) using the interaction between 1047 nm Nd:YLF laser (10ps FWHM) and about 5 MeV high quality electron beam (10ps FWHM) generated from rf gun system. The range of X-ray energy in the water window region has K-shell absorption edges of Oxygen, Carbon and Nitrogen, which mainly constitute of living body. Since the absorption coefficient of water is much smaller than the protein's coefficient in this range, a dehydration of the specimens is not necessary. To generate the soft X-ray pulse stably, the electron beam diagnostics have been developed such as the emittance measurement using double slit scan technique, the bunch length measurement using two frequency analysis technique. In this confere...

  2. Virtual environment assessment for laser-based vision surface profiling

    Science.gov (United States)

    ElSoussi, Adnane; Al Alami, Abed ElRahman; Abu-Nabah, Bassam A.

    2015-03-01

    Oil and gas businesses have been raising the demand from original equipment manufacturers (OEMs) to implement a reliable metrology method in assessing surface profiles of welds before and after grinding. This certainly mandates the deviation from the commonly used surface measurement gauges, which are not only operator dependent, but also limited to discrete measurements along the weld. Due to its potential accuracy and speed, the use of laser-based vision surface profiling systems have been progressively rising as part of manufacturing quality control. This effort presents a virtual environment that lends itself for developing and evaluating existing laser vision sensor (LVS) calibration and measurement techniques. A combination of two known calibration techniques is implemented to deliver a calibrated LVS system. System calibration is implemented virtually and experimentally to scan simulated and 3D printed features of known profiles, respectively. Scanned data is inverted and compared with the input profiles to validate the virtual environment capability for LVS surface profiling and preliminary assess the measurement technique for weld profiling applications. Moreover, this effort brings 3D scanning capability a step closer towards robust quality control applications in a manufacturing environment.

  3. Auger coefficient in GaInN-based laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Draeger, Alexander Daniel; Netzel, Carsten; Brendel, Moritz; Joenen, Holger; Rossow, Uwe; Hangleiter, Andreas [Institut fuer Angewandte Physik, TU Braunschweig (Germany)

    2010-07-01

    Todays GaInN-based light emitting devices such as LEDs and laser diodes show excellent properties in terms of quantum efficiency or threshold current in the violet-blue spectral region. With increasing wavelength towards the green this performance decreases strongly. In particular at longer wavelengths, the quantum efficiency decreases for higher current densities, called the efficiency droop. This phenomenon is still subject to intensive research and different mechanisms such as Auger recombination, losses due to dislocations and carrier escape have been named as possible explanations. We combine optical gain measurements using the variable stripe length technique with model calculations of the optical gain spectra to derive the carrier lifetime. From the dependence of the inverse effective lifetime on carrier density we determine the recombination coefficients for radiative, nonradiative and Auger recombination. The Auger coefficients we obtained are about 1-2 x 10{sup -31} cm{sup 6}/s for GaInN quantum wells with 2.5eVlaser threshold.

  4. Precedent Research on Compact Laser-plasma based Gantry for Cancer Therapy

    International Nuclear Information System (INIS)

    Hee, Park Seong; Jeong, Young Uk; Lee, Ki Tae; Kim, Kyung Nam; Cha, Young Ho

    2012-03-01

    This is the precedent R and D to develop the technology of next generation compact particle cancer treatment system based on laser-plasma interaction and to deduce a big project. The subject of this project are the survey of application technology of laser-plasma based particle beam and the design of compact laser-plasma based gantry. The survey of characteristic of particle beam for cancer therapy and present status can be adapted to develop new system. The comparison between particle beams from the existing system and new one based on laser-plasma acceleration will be important to new design and design optimization. The project includes design of multi-dimensional laser transfer beamline, minimization of laser-plasma acceleration chamber, design of effective energy separation/selection system, and radiation safety and local shielding

  5. Sensor based robot laser welding - based on feed forward and gain sceduling algorithms

    DEFF Research Database (Denmark)

    Andersen, Henrik John

    2001-01-01

    A real-time control system forlaser welding of thick steel plates are developed and tested in a industrial environment. The robotic execution of the laser welding process is based on measure weld joint geometry and impirically established welding procedures. The influence of industrial production...

  6. Investigation into the accuracy of a proposed laser diode based multilateration machine tool calibration system

    International Nuclear Information System (INIS)

    Fletcher, S; Longstaff, A P; Myers, A

    2005-01-01

    Geometric and thermal calibration of CNC machine tools is required in modern machine shops with volumetric accuracy assessment becoming the standard machine tool qualification in many industries. Laser interferometry is a popular method of measuring the errors but this, and other alternatives, tend to be expensive, time consuming or both. This paper investigates the feasibility of using a laser diode based system that capitalises on the low cost nature of the diode to provide multiple laser sources for fast error measurement using multilateration. Laser diode module technology enables improved wavelength stability and spectral linewidth which are important factors for laser interferometry. With more than three laser sources, the set-up process can be greatly simplified while providing flexibility in the location of the laser sources improving the accuracy of the system

  7. Fabrication of Microhotplates Based on Laser Micromachining of Zirconium Oxide

    Science.gov (United States)

    Oblov, Konstantin; Ivanova, Anastasia; Soloviev, Sergey; Samotaev, Nikolay; Lipilin, Alexandr; Vasiliev, Alexey; Sokolov, Andrey

    We present a novel approach to the fabrication of MEMS devices, which can be used for gas sensors operating in harsh environment in wireless and autonomous information systems. MEMS platforms based on ZrO2/Y2O3 (YSZ) are applied in these devices. The methods of ceramic MEMS devices fabrication with laser micromachining are considered. It is shown that the application of YSZ membranes permits a decrease in MEMS power consumption at 4500C down to ∼75 mW at continuous heating and down to ∼ 1 mW at pulse heating mode. The application of the platforms is not restricted by gas sensors: they can be used for fast thermometers, bolometric matrices, flowmeteres and other MEMS devices working under harsh environmental conditions.

  8. Optofluidic laser scanner based on a rotating liquid prism.

    Science.gov (United States)

    Kopp, Daniel; Lehmann, Lukas; Zappe, Hans

    2016-03-20

    We demonstrate an electrowetting-actuated optofluidic system based on a rotatable liquid prism implemented as a two-dimensional laser scanner. The system is fabricated through a novel technology using a patterned flexible polymeric foil on which a high density of electrodes is structured and which is subsequently inserted into a cylindrical housing. The resulting radial electrode array is used for electrowetting actuation of two fluids filled into the cylinder, which allows a controllable tilt and orientation of the planar liquid interface and thus represents a tunable rotating prism. Finite element simulations and subsequent experimental verification show that this highly planar and precisely positionable liquid/liquid interface may be actuated to a deflection angle of ±6.4°, with a standard deviation of ±0.18°, and rotated 360° about the vertical axis. Power consumption is limited to several microwatts, and switching times of several hundred milliseconds were determined.

  9. Free-space communication based on quantum cascade laser

    International Nuclear Information System (INIS)

    Liu Chuanwei; Zhai Shenqiang; Zhang Jinchuan; Zhou Yuhong; Jia Zhiwei; Liu Fengqi; Wang Zhanguo

    2015-01-01

    A free-space communication based on a mid-infrared quantum cascade laser (QCL) is presented. A room-temperature continuous-wave distributed-feedback (DFB) QCL combined with a mid-infrared detector comprise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modulated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system. (paper)

  10. Speckle disturbance limit in laser-based cinema projection systems

    Science.gov (United States)

    Verschaffelt, Guy; Roelandt, Stijn; Meuret, Youri; van den Broeck, Wendy; Kilpi, Katriina; Lievens, Bram; Jacobs, An; Janssens, Peter; Thienpont, Hugo

    2015-09-01

    In a multi-disciplinary effort, we investigate the level of speckle that can be tolerated in a laser cinema projector based on a quality of experience experiment with movie clips shown to a test audience in a real-life movie theatre setting. We identify a speckle disturbance threshold by statistically analyzing the observers’ responses for different values of the amount of speckle, which was monitored using a well-defined speckle measurement method. The analysis shows that the speckle perception of a human observer is not only dependent on the objectively measured amount of speckle, but it is also strongly influenced by the image content. The speckle disturbance limit for movies turns out to be substantially larger than that for still images, and hence is easier to attain.

  11. Lanthanide-based laser-induced phosphorescence for spray diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Voort, D. D. van der, E-mail: d.d.v.d.voort@tue.nl; Water, W. van de; Kunnen, R. P. J.; Clercx, H. J. H.; Heijst, G. J. F. van [Applied Physics Department, Eindhoven University of Technology, 5612 AZ Eindhoven (Netherlands); Maes, N. C. J.; Sweep, A. M.; Dam, N. J. [Mechanical Engineering Department, Eindhoven University of Technology, 5612 AZ Eindhoven (Netherlands); Lamberts, T. [Institute of Theoretical Chemistry, University of Stuttgart, D-70569 Stuttgart (Germany)

    2016-03-15

    Laser-induced phosphorescence (LIP) is a relatively recent and versatile development for studying flow dynamics. This work investigates certain lanthanide-based molecular complexes for their use in LIP for high-speed sprays. Lanthanide complexes in solutions have been shown to possess long phosphorescence lifetimes (∼1-2 ms) and to emit light in the visible wavelength range. In particular, europium and terbium complexes are investigated using fluorescence/phosphorescence spectrometry, showing that europium-thenoyltrifluoracetone-trioctylphosphineoxide (Eu-TTA-TOPO) can be easily and efficiently excited using a standard frequency-tripled Nd:YAG laser. The emitted spectrum, with maximum intensity at a wavelength of 614 nm, is shown not to vary strongly with temperature (293-383 K). The decay constant of the phosphorescence, while independent of ambient pressure, decreases by approximately 12 μs/K between 323 and 373 K, with the base level of the decay constant dependent on the used solvent. The complex does not luminesce in the gas or solid state, meaning only the liquid phase is visualized, even in an evaporating spray. By using an internally excited spray containing the phosphorescent complex, the effect of vaporization is shown through the decrease in measured intensity over the length of the spray, together with droplet size measurements using interferometric particle imaging. This study shows that LIP, using the Eu-TTA-TOPO complex, can be used with different solvents, including diesel surrogates. Furthermore, it can be easily handled and used in sprays to investigate spray breakup and evaporation.

  12. Yb:YAG Lasers for Space Based Remote Sensing

    Science.gov (United States)

    Ewing, J.J.; Fan, T. Y.

    1998-01-01

    Diode pumped solid state lasers will play a prominent role in future remote sensing missions because of their intrinsic high efficiency and low mass. Applications including altimetry, cloud and aerosol measurement, wind velocity measurement by both coherent and incoherent methods, and species measurements, with appropriate frequency converters, all will benefit from a diode pumped primary laser. To date the "gold standard" diode pumped Nd laser has been the laser of choice for most of these concepts. This paper discusses an alternate 1 micron laser, the YB:YAG laser, and its potential relevance for lidar applications. Conceptual design analysis and, to the extent possible at the time of the conference, preliminary experimental data on the performance of a bread board YB:YAG oscillator will be presented. The paper centers on application of YB:YAG for altimetry, but extension to other applications will be discussed.

  13. Laser cutting of irregular shape object based on stereo vision laser galvanometric scanning system

    Science.gov (United States)

    Qi, Li; Zhang, Yixin; Wang, Shun; Tang, Zhiqiang; Yang, Huan; Zhang, Xuping

    2015-05-01

    Irregular shape objects with different 3-dimensional (3D) appearances are difficult to be shaped into customized uniform pattern by current laser machining approaches. A laser galvanometric scanning system (LGS) could be a potential candidate since it can easily achieve path-adjustable laser shaping. However, without knowing the actual 3D topography of the object, the processing result may still suffer from 3D shape distortion. It is desirable to have a versatile auxiliary tool that is capable of generating 3D-adjusted laser processing path by measuring the 3D geometry of those irregular shape objects. This paper proposed the stereo vision laser galvanometric scanning system (SLGS), which takes the advantages of both the stereo vision solution and conventional LGS system. The 3D geometry of the object obtained by the stereo cameras is used to guide the scanning galvanometers for 3D-shape-adjusted laser processing. In order to achieve precise visual-servoed laser fabrication, these two independent components are integrated through a system calibration method using plastic thin film target. The flexibility of SLGS has been experimentally demonstrated by cutting duck feathers for badminton shuttle manufacture.

  14. Arbitrary temporal shape pulsed fiber laser based on SPGD algorithm

    Science.gov (United States)

    Jiang, Min; Su, Rongtao; Zhang, Pengfei; Zhou, Pu

    2018-06-01

    A novel adaptive pulse shaping method for a pulsed master oscillator power amplifier fiber laser to deliver an arbitrary pulse shape is demonstrated. Numerical simulation has been performed to validate the feasibility of the scheme and provide meaningful guidance for the design of the algorithm control parameters. In the proof-of-concept experiment, information on the temporal property of the laser is exchanged and evaluated through a local area network, and the laser adjusted the parameters of the seed laser according to the monitored output of the system automatically. Various pulse shapes, including a rectangular shape, ‘M’ shape, and elliptical shape are achieved through experimental iterations.

  15. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets.

    Science.gov (United States)

    Gabriel, Tobias; Rommel, Daniel; Scherm, Florian; Gorywoda, Marek; Glatzel, Uwe

    2017-03-10

    Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co-28Cr-9W-1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE) study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM) and scanning electron microscopy (SEM), combined with electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDX). Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  16. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets

    Directory of Open Access Journals (Sweden)

    Tobias Gabriel

    2017-03-01

    Full Text Available Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co–28Cr–9W–1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM and scanning electron microscopy (SEM, combined with electron backscatter diffraction (EBSD and energy dispersive X-ray spectroscopy (EDX. Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  17. Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

    Science.gov (United States)

    Leahy-Hoppa, Megan R.; Miragliotta, Joseph; Osiander, Robert; Burnett, Jennifer; Dikmelik, Yamac; McEnnis, Caroline; Spicer, James B.

    2010-01-01

    Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications. PMID:22399883

  18. Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Megan R. Leahy-Hoppa

    2010-04-01

    Full Text Available Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS, coherent Raman spectroscopy, and terahertz (THz spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications.

  19. Image-guided, Laser-based Fabrication of Vascular-derived Microfluidic Networks

    OpenAIRE

    Heintz, Keely A.; Mayerich, David; Slater, John H.

    2017-01-01

    This detailed protocol outlines the implementation of image-guided, laser-based hydrogel degradation for the fabrication of vascular-derived microfluidic networks embedded in PEGDA hydrogels. Here, we describe the creation of virtual masks that allow for image-guided laser control; the photopolymerization of a micromolded PEGDA hydrogel, suitable for microfluidic network fabrication and pressure head-driven flow; the setup and use of a commercially available laser scanning confocal microscope...

  20. Current developments with TRIUMF’s titanium-sapphire laser based resonance ionization laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, J., E-mail: LASSEN@triumf.ca; Li, R. [TRIUMF (Canada); Raeder, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Zhao, X.; Dekker, T. [TRIUMF (Canada); Heggen, H. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Kunz, P.; Levy, C. D. P.; Mostanmand, M.; Teigelhöfer, A.; Ames, F. [TRIUMF (Canada)

    2017-11-15

    Developments at TRIUMF’s isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

  1. Simulaser, a graphical laser simulator based on Matlab Simulink

    CSIR Research Space (South Africa)

    Jacobs, Cobus

    2016-07-01

    Full Text Available We present a single-element plane-wave laser rate equation model and its implementation as a graphical laser simulation library using Matlab Simulink. Simulink’s graphical interface and vector capabilities provide a unique layer of abstraction...

  2. Radiation sources based on laser-plasma interactions

    NARCIS (Netherlands)

    Jaroszynski, D.A.; Bingham, R.; Brunetti, E.; Ersfeld, B.; Gallacher, J.G.; Geer, van der S.B.; Issac, R.; Jamison, S.P.; Jones, D.; Loos, de M.J.; Lyachev, A.; Pavlov, V.M.; Reitsma, A.J.W.; Saveliev, Y.M.; Vieux, G.; Wiggins, S.M.

    2006-01-01

    Plasma waves excited by intense laser beams can be harnessed to produce femtosecond duration bunches of electrons with relativistic energies. The very large electrostatic forces of plasma density wakes trailing behind an intense laser pulse provide field potentials capable of accelerating charged

  3. A laser-based FAIMS detector for detection of ultra-low concentrations of explosives

    Science.gov (United States)

    Akmalov, Artem E.; Chistyakov, Alexander A.; Kotkovskii, Gennadii E.; Sychev, Alexey V.; Tugaenko, Anton V.; Bogdanov, Artem S.; Perederiy, Anatoly N.; Spitsyn, Eugene M.

    2014-06-01

    A non-contact method for analyzing of explosives traces from surfaces was developed. The method is based on the laser desorption of analyzed molecules from the surveyed surfaces followed by the laser ionization of air sample combined with the field asymmetric ion mobility spectrometry (FAIMS). The pulsed radiation of the fourth harmonic of a portable GSGG: Cr3+ :Nd3+ laser (λ = 266 nm) is used. The laser desorption FAIMS analyzer have been developed. The detection limit of the analyzer equals 40 pg for TNT. The results of detection of trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX) are presented. It is shown that laser desorption of nitro-compounds from metals is accompanied by their surface decomposition. A method for detecting and analyzing of small concentrations of explosives in air based on the laser ionization and the FAIMS was developed. The method includes a highly efficient multipass optical scheme of the intracavity fourthharmonic generation of pulsed laser radiation (λ = 266 nm) and the field asymmetric ion mobility (FAIM) spectrometer disposed within a resonator. The ions formation and detection proceed inside a resonant cavity. The laser ion source based on the multi-passage of radiation at λ = 266 nm through the ionization region was elaborated. On the basis of the method the laser FAIMS analyzer has been created. The analyzer provides efficient detection of low concentrations of nitro-compounds in air and shows a detection limit of 10-14 - 10-15 g/cm3 both for RDX and TNT.

  4. Laser Based Phosphor Converted Solid State White Light Emitters

    Science.gov (United States)

    Cantore, Michael

    Artificial lighting and as a consequence the ability to be productive when the sun does not shine may be a profound achievement in society that is largely taken for granted. As concerns arise due to our dependence on energy sources with finite lifespan or environmentally negative effects, efforts to reduce energy consumption and create clean renewable alternatives has become highly valued. In the scope of artificial lighting, the use of incandescent lamps has shifted to more efficient light sources. Fluorescent lighting made the first big gains in efficiency over incandescent lamps with peak efficiency for mature designs reaching luminous efficacy of approximately 90 lm/W; more than three times as efficient as an incandescent lamp. Lamps based on light emitting diodes (LEDs) which can produce light at even greater efficiency, color quality and without the potential for hazardous chemical release from lamp failure. There is a significant challenge with LED based light sources. Their peak efficiency occurs at low current densities and then droops as the current density increases. Laser diodes (LDs) do not suffer from decreasing efficiency due to increased current. An alternative solid state light source using LDs has potential to make further gains in efficiency as well as allow novel illuminant designs which may be impractical or even impossible even with LED or other conventional sources. While similar to LEDS, the use of LDs does present new challenges largely due to the increased optical power density which must be accommodated in optics and phosphor materials. Single crystal YAG:Ce has been shown to be capable of enduring this more extreme operating environment while retaining the optical and fluorescing qualities desired for use as a wavelength converter in phosphor converted LD based white emitting systems. The incorporation of this single crystal phosphor in a system with a commercial laser diode with peak wall plug efficiency of 31% resulted in emission of

  5. The Effect of Glare on Regan Contrast Letter Acuity Scores Using Dye-Based and Reflective Laser Eye Protection

    National Research Council Canada - National Science Library

    Ghani, Nadeem

    2001-01-01

    Current laser eye protection devices (LEPDs) are dye-based or reflective. While both technologies block the laser wavelengths, reflective LEPDs generally transmit more visible light than do dye-based LEPDs...

  6. Photoacoustic-based detector for infrared laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, L.; Palzer, S., E-mail: stefan.palzer@imtek.uni-freiburg.de [Department of Microsystems Engineering-IMTEK, Laboratory for Gas Sensors, University of Freiburg, Georges-Köhler-Allee 102, Freiburg 79110 (Germany)

    2016-07-25

    In this contribution, we present an alternative detector technology for use in direct absorption spectroscopy setups. Instead of a semiconductor based detector, we use the photoacoustic effect to gauge the light intensity. To this end, the target gas species is hermetically sealed under excess pressure inside a miniature cell along with a MEMS microphone. Optical access to the cell is provided by a quartz window. The approach is particularly suitable for tunable diode laser spectroscopy in the mid-infrared range, where numerous molecules exhibit large absorption cross sections. Moreover, a frequency standard is integrated into the method since the number density and pressure inside the cell are constant. We demonstrate that the information extracted by our method is at least equivalent to that achieved using a semiconductor-based photon detector. As exemplary and highly relevant target gas, we have performed direct spectroscopy of methane at the R3-line of the 2v{sub 3} band at 6046.95 cm{sup −1} using both detector technologies in parallel. The results may be transferred to other infrared-active transitions without loss of generality.

  7. Feasibility study of multipoint based laser alignment system for CLIC

    CERN Document Server

    Stern, G; Mainaud-Durand, H; Piedigrossi, D; Geiger, A

    2012-01-01

    CLIC (Compact LInear Collider) is a study for a future electron-positron collider that would allow physicists to explore a new energy region beyond the capabilities oftoday’s particle accelerators. Alignment is one of the major challenges within the CLIC study in order to achieve the high requirement of a multi-TeV center of mass colliding beam energy range (nominal 3 TeV). To reach this energy in a realistic and cost efficient scenario all accelerator components have to be aligned with an accuracy of 10 μm over a sliding window of 200 m. The demand for a straight line reference is so far based on stretched wires coupled with Wire Positioning Sensors (WPS). These solutions are currently further developed inorder to reduce the drawbacks which are mainly given by their costs and difficult implementation. However, it should be validated through inter-comparison with a solution ideally based on a different physical principle. Therefore, a new metrological approach is proposed using a laser beam as straight lin...

  8. High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

    Science.gov (United States)

    Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Nava, Enzo; Stucchi, Emanuele; Trespidi, Franco; Mariottini, Cristina; Wazen, Paul; Falletto, Nicolas; Fruit, Michel

    2017-11-01

    This paper describes the laser transmitter assembly used in the ALADIN instrument currently in C/D development phase for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The Laser Transmitter Assembly (TXA), based on a diode pumped tripled Nd:YAG laser, is used to generate tunable laser pulses of 150 mJ at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz. The TXA is composed of the following units: a diodepumped CW Nd:YAG Laser named Reference Laser Head (RLH), used to inject a diode-pumped, Q-switched, amplified and frequency tripled Nd:YAG Laser working in the third harmonic referred as Power Laser Head (PLH) and a Transmitter Laser Electronics (TLE) containing all the control and power electronics needed for PLH and RLH operation. The TXA is made by an European consortium under the leadership of Galileo Avionica (It), and including CESI (It), Quantel (Fr), TESAT (Ge) and Thales (Fr).

  9. Technique for long and absolute distance measurement based on laser pulse repetition frequency sweeping

    Science.gov (United States)

    Castro Alves, D.; Abreu, Manuel; Cabral, A.; Jost, Michael; Rebordão, J. M.

    2017-11-01

    In this work we present a technique to perform long and absolute distance measurements based on mode-locked diode lasers. Using a Michelson interferometer, it is possible to produce an optical cross-correlation between laser pulses of the reference arm with the pulses from the measurement arm, adjusting externally their degree of overlap either changing the pulse repetition frequency (PRF) or the position of the reference arm mirror for two (or more) fixed frequencies. The correlation of the travelling pulses for precision distance measurements relies on ultra-short pulse durations, as the uncertainty associated to the method is dependent on the laser pulse width as well as on a highly stable PRF. Mode-locked Diode lasers are a very appealing technology for its inherent characteristics, associated to compactness, size and efficiency, constituting a positive trade-off with regard to other mode-locked laser sources. Nevertheless, main current drawback is the non-availability of frequency-stable laser diodes. The laser used is a monolithic mode-locked semiconductor quantum-dot (QD) laser. The laser PRF is locked to an external stabilized RF reference. In this work we will present some of the preliminary results and discuss the importance of the requirements related to laser PRF stability in the final metrology system accuracy.

  10. An improved three-dimensional non-scanning laser imaging system based on digital micromirror device

    Science.gov (United States)

    Xia, Wenze; Han, Shaokun; Lei, Jieyu; Zhai, Yu; Timofeev, Alexander N.

    2018-01-01

    Nowadays, there are two main methods to realize three-dimensional non-scanning laser imaging detection, which are detection method based on APD and detection method based on Streak Tube. However, the detection method based on APD possesses some disadvantages, such as small number of pixels, big pixel interval and complex supporting circuit. The detection method based on Streak Tube possesses some disadvantages, such as big volume, bad reliability and high cost. In order to resolve the above questions, this paper proposes an improved three-dimensional non-scanning laser imaging system based on Digital Micromirror Device. In this imaging system, accurate control of laser beams and compact design of imaging structure are realized by several quarter-wave plates and a polarizing beam splitter. The remapping fiber optics is used to sample the image plane of receiving optical lens, and transform the image into line light resource, which can realize the non-scanning imaging principle. The Digital Micromirror Device is used to convert laser pulses from temporal domain to spatial domain. The CCD with strong sensitivity is used to detect the final reflected laser pulses. In this paper, we also use an algorithm which is used to simulate this improved laser imaging system. In the last, the simulated imaging experiment demonstrates that this improved laser imaging system can realize three-dimensional non-scanning laser imaging detection.

  11. TOPSIS based parametric optimization of laser micro-drilling of TBC coated nickel based superalloy

    Science.gov (United States)

    Parthiban, K.; Duraiselvam, Muthukannan; Manivannan, R.

    2018-06-01

    The technique for order of preference by similarity ideal solution (TOPSIS) approach was used for optimizing the process parameters of laser micro-drilling of nickel superalloy C263 with Thermal Barrier Coating (TBC). Plasma spraying was used to deposit the TBC and a pico-second Nd:YAG pulsed laser was used to drill the specimens. Drilling angle, laser scan speed and number of passes were considered as input parameters. Based on the machining conditions, Taguchi L8 orthogonal array was used for conducting the experimental runs. The surface roughness and surface crack density (SCD) were considered as the output measures. The surface roughness was measured using 3D White Light Interferometer (WLI) and the crack density was measured using Scanning Electron Microscope (SEM). The optimized result achieved from this approach suggests reduced surface roughness and surface crack density. The holes drilled at an inclination angle of 45°, laser scan speed of 3 mm/s and 400 number of passes found to be optimum. From the Analysis of variance (ANOVA), inclination angle and number of passes were identified as the major influencing parameter. The optimized parameter combination exhibited a 19% improvement in surface finish and 12% reduction in SCD.

  12. Laser-based diagnostics on NO in a diesel engine

    International Nuclear Information System (INIS)

    Brugman, T.M.

    1999-01-01

    The non-intrusive two-dimensional detection of nitric oxide (NO) in the cylinder of a diesel engine by means of laser-induced fluorescence (LIF) is the central theme of this thesis. Chapter 1 provides a general introduction including a brief discussion of the underlying environmental considerations as well as an overview of the laser-based imaging diagnostics in i.c. engines as reported in the literature. In the same chapter the LIF spectroscopy of NO is discussed in detail and the dependence of the LIF signal to several parameters is studied on the basis of a two-level rate equation model. This chapter concludes with an overview of the imaging techniques used in the experiments discussed in this thesis. The principal components of the experimental setup are described in great detail in chapter 2. Some of the issues discussed there have turned out to be crucial for the success of the experiments as reported in the subsequent chapters. In chapter 3 the results of the first imaging experiments in the idling engine are reported for two different fuels: n-heptane and standard diesel fuel. Besides the in-cylinder NO fluorescence distributions at various crank angles presented in this chapter, excitation spectra recorded from in-cylinder NO at atmospheric pressure using the respective fuels are also reported. In chapter 4 the detection method is further validated on the basis of a number of experiments in the standard-diesel -fuel -driven engine testing the various underlying assumptions. The sensitivity of the LIF signal to photo-chemically- induced effects possibly arising from the use of a high-power UV excimer laser, is investigated by means of a double-resonance experiment. The dependence of the LIF signal on the actual laser power is experimentally verified as well. The degree as to which saturation might occur at the in-cylinder laser intensities pertinent to this work, is estimated using data and relations found in the literature. Finally, in this chapter image

  13. Tunable ultraviolet solid-state dye laser based on MPMMA doped with pyrromethene 597

    International Nuclear Information System (INIS)

    Jiang, Y G; Fan, R W; Xia, Y Q; Chen, D Y

    2011-01-01

    Solid-state dye sample based on modified polymethyl methacrylate (MPMMA) co-doped with pyrromethene 597 (PM597), and coumarin 460 (C460) were prepared. A frequency-doubled pulsed Nd:YAG laser is used to pump solid-state dye sample, and the narrow linewidth dye laser of 94.4 mJ was obtained at 582 nm in an oscillator-amplifier configuration. Using a beta-BaB 2 O 4 (BBO) crystal to frequency double the dye laser into ultraviolet (UV), a tuning range from 279 to 305 nm was demonstrated from a single doped PM597 dye. To the best of our knowledge, the UV tuning range is the best under the same condition so far. The conversion slope efficiency from solid dye laser to UV laser was 8.9% and the highest UV laser output energy reached 6.94 mJ at 291 nm

  14. IGZO TFT-based circuit with tunable threshold voltage by laser annealing

    Science.gov (United States)

    Huang, Xiaoming; Yu, Guang; Wu, Chenfei

    2017-11-01

    In this work, a high-performance inverter based on amorphous indium-gallium-zinc oxide thin-film transistors (TFTs) has been fabricated, which consists of a driver TFT and a load TFT. The threshold voltage (Vth) of the load TFT can be tuned by applying an area-selective laser annealing. The transfer curve of the load TFT shows a parallel shift into the negative bias direction upon laser annealing. Based on x-ray photoelectron spectroscopy analyses, the negative Vth shift can be attributed to the increase of oxygen vacancy concentration within the device channel upon laser irradiation. Compared to the untreated inverter, the laser annealed inverter shows much improved switching characteristics, including a large output swing range which is close to full swing, as well as an enhanced output voltage gain. Furthermore, the dynamic performance of ring oscillator based on the laser-annealed inverter is improved.

  15. Power Scaling of Laser Oscillators and Amplifiers Based on Nd:YVO4

    OpenAIRE

    Yarrow, Michael James

    2006-01-01

    This thesis presents a strategy for power and brightness scaling in diode-end-pumped, master-oscillator-power-amplifier laser systems, based on Nd:YVOIssues relating to further power and brightness scaling are discussed as well as the potential applications of these laser sources as pump sources for frequency conversion in optical parametric devices.

  16. Competency-Based Curriculum Guide for Laser Technology. September 1980-June 1981.

    Science.gov (United States)

    Fioroni, John J.

    This document contains materials developed by a project to provide a competency-based curriculum guide for laser technology at the community college level. An abstract of the final report is included. Next, the 17 job competencies determined as necessary to meet the job description of laser technician are listed. A career ladder and qualifications…

  17. Widely tunable quantum cascade laser-based terahertz source.

    Science.gov (United States)

    Danylov, Andriy A; Light, Alexander R; Waldman, Jerry; Erickson, Neal; Qian, Xifeng

    2014-07-10

    A compact, tunable, ultranarrowband terahertz source, Δν∼1  MHz, is demonstrated by upconversion of a 2.324 THz, free-running quantum cascade laser with a THz Schottky-diode-balanced mixer using a swept, synthesized microwave source to drive the nonlinearity. Continuously tunable radiation of 1 μW power is demonstrated in two frequency regions: ν(Laser) ± 0 to 50 GHz and ν(Laser) ± 70 to 115 GHz. The sideband spectra were characterized with a Fourier-transform spectrometer, and the radiation was tuned through CO, HDO, and D2O rotational transitions.

  18. A Lightweight Structure Redesign Method Based on Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Li Tang

    2016-11-01

    Full Text Available The purpose of this paper is to present a new design method of lightweight parts fabricated by selective laser melting (SLM based on the “Skin-Frame” and to explore the influence of fabrication defects on SLM parts with different sizes. Some standard lattice parts were designed according to the Chinese GB/T 1452-2005 standard and manufactured by SLM. Then these samples were tested in an MTS Insight 30 compression testing machine to study the trends of the yield process with different structure sizes. A set of standard cylinder samples were also designed according to the Chinese GB/T 228-2010 standard. These samples, which were made of iron-nickel alloy (IN718, were also processed by SLM, and then tested in the universal material testing machine INSTRON 1346 to obtain their tensile strength. Furthermore, a lightweight redesigned method was researched. Then some common parts such as a stopper and connecting plate were redesigned using this method. These redesigned parts were fabricated and some application tests have already been performed. The compression testing results show that when the minimum structure size is larger than 1.5 mm, the mechanical characteristics will hardly be affected by process defects. The cylinder parts were fractured by the universal material testing machine at about 1069.6 MPa. These redesigned parts worked well in application tests, with both the weight and fabrication time of these parts reduced more than 20%.

  19. Ultrafast laser based coherent control methods for explosives detection

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David Steven [Los Alamos National Laboratory

    2010-12-06

    The detection of explosives is a notoriously difficult problem, especially at stand-off, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring Optimal Dynamic Detection of Explosives (ODD-Ex), which exploits the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity to explosives signatures while dramatically improving specificity, particularly against matrix materials and background interferences. These goals are being addressed by operating in an optimal non-linear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe subpulses. Recent results will be presented.

  20. Tunable Laser Plasma Accelerator based on Longitudinal Density Tailoring

    Energy Technology Data Exchange (ETDEWEB)

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Panasenko, Dmitriy; Shiraishi, Satomi; Sokollik, Thomas; Benedetti, Carlo; Schroeder, Carl; Geddes, Cameron; Tilborg, Jeroen van; Osterhoff, Jens; Esarey, Eric; Toth, Csaba; Leemans, Wim

    2011-07-15

    Laser plasma accelerators have produced high-quality electron beams with GeV energies from cm-scale devices and are being investigated as hyperspectral fs light sources producing THz to {gamma}-ray radiation and as drivers for future high-energy colliders. These applications require a high degree of stability, beam quality and tunability. Here we report on a technique to inject electrons into the accelerating field of a laser-driven plasma wave and coupling of this injector to a lower-density, separately tunable plasma for further acceleration. The technique relies on a single laser pulse powering a plasma structure with a tailored longitudinal density profile, to produce beams that can be tuned in the range of 100-400 MeV with percent-level stability, using laser pulses of less than 40 TW. The resulting device is a simple stand-alone accelerator or the front end for a multistage higher-energy accelerator.

  1. Laser-Scribed Graphene Electrodes for Aptamer-Based Biosensing

    KAUST Repository

    Fenzl, Christoph; Nayak, Pranati; Hirsch, Thomas; Wolfbeis, Otto S.; Alshareef, Husam N.; Baeumner, Antje J.

    2017-01-01

    (LSG) electrodes are demonstrated here as highly sensitive and reliable biosensor transducers in blood serum analysis. These flexible electrodes with large electrochemical surface areas were fabricated using a direct-write laser process on polyimide foils. A

  2. Fiber-Based 589 nm Laser for Sodium Guide Star

    National Research Council Canada - National Science Library

    Nilsson, Lars J; Jeong, Yoonchan; Dupriez, Pascal

    2006-01-01

    ...: The work will entail the construction of the required sub-assemblies, their integration into the laser source, and the exploration and adjustment of parameters in order to obtain adequate performance...

  3. A laser beam quality definition based on induced temperature rise.

    Science.gov (United States)

    Miller, Harold C

    2012-12-17

    Laser beam quality metrics like M(2) can be used to describe the spot sizes and propagation behavior of a wide variety of non-ideal laser beams. However, for beams that have been diffracted by limiting apertures in the near-field, or those with unusual near-field profiles, the conventional metrics can lead to an inconsistent or incomplete description of far-field performance. This paper motivates an alternative laser beam quality definition that can be used with any beam. The approach uses a consideration of the intrinsic ability of a laser beam profile to heat a material. Comparisons are made with conventional beam quality metrics. An analysis on an asymmetric Gaussian beam is used to establish a connection with the invariant beam propagation ratio.

  4. Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering.

    Science.gov (United States)

    Ehn, Andreas; Zhu, Jiajian; Li, Xuesong; Kiefer, Johannes

    2017-03-01

    Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

  5. 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.

  6. Packaging consideration of two-dimensional polymer-based photonic crystals for laser beam steering

    Science.gov (United States)

    Dou, Xinyuan; Chen, Xiaonan; Chen, Maggie Yihong; Wang, Alan Xiaolong; Jiang, Wei; Chen, Ray T.

    2009-02-01

    In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results were also reported.

  7. Laser beam shaping design based on micromirror array

    Science.gov (United States)

    Fang, Han; Su, Bida; Liu, Jiaguo; Fan, Xiaoli; Jing, Wang

    2017-10-01

    In the practical application of the laser, it is necessary to use the laser beam shaping technology to shape the output beam of laser device to the uniform light intensity distribution. The shaping divergent optical system of compound eye integrator way is composed of beam expanding mirror group and lens array. Its working principle is to expand the output laser to a certain size of caliber, and then divide the beam with lens array into multiple sub beam, where the lens unit of lens array can control the divergence angle of sub beam through the design of focal length, with mutual superposition of the sub beam in far field, to make up for the nonuniformity of beam, so that the radiant exitance on the radiated surface may become uniform. In this paper, we use a reflective microlens array to realize the laser beam shaping. By through of the practical optical path model established, the ray tracing is carried out and the simulation results for single-mode Gaussian beam with noise circumstance is provided. The analysis results show that the laser beam shaping under different inputs can be effectively realized by use of microlens array. All the energy is within the signal window, with a high energy efficiency of more than 90%; The measured surface has a better uniformity, and the uniformity is better than 99.5% at 150m.

  8. Speckle reduction methods in laser-based picture projectors

    Science.gov (United States)

    Akram, M. Nadeem; Chen, Xuyuan

    2016-02-01

    Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.

  9. Fiber-Based Lasers as an Option for GRACE Follow-On Light Source

    Science.gov (United States)

    Camp, Jordan

    2010-01-01

    Fiber based lasers offer a number of attractive characteristics for space application: state of the art laser technology, leverage of design and reliability from the substantial investments of the telecon industry, and convenient redundancy of higher risk components through fiber splicing. At NASA/Goddard we are currently investigating three GFO fiber-based laser options: a fiber oscillator built in our laboratory; an effort to space qualify a commercial design that uses a proprietary high-gain fiber cavity; and the space qualification of a promising new commercial external cavity laser, notable for its low-mass, compact design. In my talk I will outline these efforts, and suggest that the GFO Project may soon have the option of a US laser vendor for its light source.

  10. Space debris removal using a high-power ground-based laser

    Energy Technology Data Exchange (ETDEWEB)

    Monroe, D.K.

    1993-12-31

    The feasibility and practicality of using a ground-based laser (GBL) to remove artificial space debris is examined. Physical constraints indicate that a reactor-pumped laser (RPL) may be best suited for this mission, because of its capabilities for multimegawatt output long run-times, and near-diffraction-limited initial beams. Simulations of a laser-powered debris removal system indicate that a 5-MW RPL with a 10-meter-diameter beam director and adaptive optics capabilities can deorbit 1-kg debris from space station altitudes. Larger debris can be deorbited or transferred to safer orbits after multiple laser engagements. A ground-based laser system may be the only realistic way to access and remove some 10,000 separate objects, having velocities in the neighborhood of 7 km/sec, and being spatially distributed over some 10{sup 10} km{sup 3} of space.

  11. Resonator design and performance estimation for a space-based laser transmitter

    Science.gov (United States)

    Agrawal, Lalita; Bhardwaj, Atul; Pal, Suranjan; Kamalakar, J. A.

    2006-12-01

    Development of a laser transmitter for space applications is a highly challenging task. The laser must be rugged, reliable, lightweight, compact and energy efficient. Most of these features are inherently achieved by diode pumping of solid state lasers. Overall system reliability can further be improved by appropriate optical design of the laser resonator besides selection of suitable electro-optical and opto-mechanical components. This paper presents the design details and the theoretically estimated performance of a crossed-porro prism based, folded Z-shaped laser resonator. A symmetrically pumped Nd: YAG laser rod of 3 mm diameter and 60 mm length is placed in the gain arm with total input peak power of 1800 W from laser diode arrays. Electro-optical Q-switching is achieved through a combination of a polarizer, a fractional waveplate and LiNbO 3 Q-switch crystal (9 x 9 x 25 mm) placed in the feedback arm. Polarization coupled output is obtained by optimizing azimuth angle of quarter wave plate placed in the gain arm. Theoretical estimation of laser output energy and pulse width has been carried out by varying input power levels and resonator length to analyse the performance tolerances. The designed system is capable of meeting the objective of generating laser pulses of 10 ns duration and 30 mJ energy @ 10 Hz.

  12. Laser-ablation-based ion source characterization and manipulation for laser-driven ion acceleration

    Science.gov (United States)

    Sommer, P.; Metzkes-Ng, J.; Brack, F.-E.; Cowan, T. E.; Kraft, S. D.; Obst, L.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

    2018-05-01

    For laser-driven ion acceleration from thin foils (∼10 μm–100 nm) in the target normal sheath acceleration regime, the hydro-carbon contaminant layer at the target surface generally serves as the ion source and hence determines the accelerated ion species, i.e. mainly protons, carbon and oxygen ions. The specific characteristics of the source layer—thickness and relevant lateral extent—as well as its manipulation have both been investigated since the first experiments on laser-driven ion acceleration using a variety of techniques from direct source imaging to knife-edge or mesh imaging. In this publication, we present an experimental study in which laser ablation in two fluence regimes (low: F ∼ 0.6 J cm‑2, high: F ∼ 4 J cm‑2) was applied to characterize and manipulate the hydro-carbon source layer. The high-fluence ablation in combination with a timed laser pulse for particle acceleration allowed for an estimation of the relevant source layer thickness for proton acceleration. Moreover, from these data and independently from the low-fluence regime, the lateral extent of the ion source layer became accessible.

  13. Measurements of DSD Second Moment Based on Laser Extinction

    Science.gov (United States)

    Lane, John E.; Jones, Linwood; Kasparis, Takis C.; Metzger, Philip

    2013-01-01

    Using a technique recently developed for estimating the density of surface dust dispersed during a rocket landing, measuring the extinction of a laser passing through rain (or dust in the rocket case) yields an estimate of the 2nd moment of the particle cloud, and rainfall drop size distribution (DSD) in the terrestrial meteorological case. With the exception of disdrometers, instruments that measure rainfall make in direct measurements of the DSD. Most common of these instruments are the rainfall rate gauge measuring the 1 1/3 th moment, (when using a D(exp 2/3) dependency on terminal velocity). Instruments that scatter microwaves off of hydrometeors, such as the WSR-880, vertical wind profilers, and microwave disdrometers, measure the 6th moment of the DSD. By projecting a laser onto a target, changes in brightness of the laser spot against the target background during rain, yield a measurement of the DSD 2nd moment, using the Beer-Lambert law. In order to detect the laser attenuation within the 8-bit resolution of most camera image arrays, a minimum path length is required, depending on the intensity of the rainfall rate. For moderate to heavy rainfall, a laser path length of 100 m is sufficient to measure variations in optical extinction using a digital camera. A photo-detector could replace the camera, for automated installations. In order to spatially correlate the 2nd moment measurements to a collocated disdrometer or tipping bucket, the laser's beam path can be reflected multiple times using mirrors to restrict the spatial extent of the measurement. In cases where a disdrometer is not available, complete DSD estimates can be produced by parametric fitting of DSD model to the 2nd moment data in conjunction with tipping bucket data. In cases where a disdrometer is collocated, the laser extinction technique may yield a significant improvement to insitu disdrometer validation and calibration strategies

  14. Photoacoustic Techniques for Trace Gas Sensing Based on Semiconductor Laser Sources

    Directory of Open Access Journals (Sweden)

    Vincenzo Spagnolo

    2009-12-01

    Full Text Available The paper provides an overview on the use of photoacoustic sensors based on semiconductor laser sources for the detection of trace gases. We review the results obtained using standard, differential and quartz enhanced photoacoustic techniques.

  15. Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gravity wave detection using space-based long-baseline laser interferometric sensors imposes stringent noise requirements on the system components, including the...

  16. New developments in laser-based photoemission spectroscopy and its scientific applications: a key issues review

    Science.gov (United States)

    Zhou, Xingjiang; He, Shaolong; Liu, Guodong; Zhao, Lin; Yu, Li; Zhang, Wentao

    2018-06-01

    The significant progress in angle-resolved photoemission spectroscopy (ARPES) in last three decades has elevated it from a traditional band mapping tool to a precise probe of many-body interactions and dynamics of quasiparticles in complex quantum systems. The recent developments of deep ultraviolet (DUV, including ultraviolet and vacuum ultraviolet) laser-based ARPES have further pushed this technique to a new level. In this paper, we review some latest developments in DUV laser-based photoemission systems, including the super-high energy and momentum resolution ARPES, the spin-resolved ARPES, the time-of-flight ARPES, and the time-resolved ARPES. We also highlight some scientific applications in the study of electronic structure in unconventional superconductors and topological materials using these state-of-the-art DUV laser-based ARPES. Finally we provide our perspectives on the future directions in the development of laser-based photoemission systems.

  17. A Laser-Based Diagnostic Suite for Hypersonic Test Facilities, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this SBIR effort, Los Gatos Research (LGR) proposes to develop a suite of laser-based diagnostics for the study of reactive and non-reactive hypersonic flows....

  18. DNA-based species detection capabilities using laser transmission spectroscopy.

    Science.gov (United States)

    Mahon, A R; Barnes, M A; Li, F; Egan, S P; Tanner, C E; Ruggiero, S T; Feder, J L; Lodge, D M

    2013-01-06

    Early detection of invasive species is critical for effective biocontrol to mitigate potential ecological and economic damage. Laser transmission spectroscopy (LTS) is a powerful solution offering real-time, DNA-based species detection in the field. LTS can measure the size, shape and number of nanoparticles in a solution and was used here to detect size shifts resulting from hybridization of the polymerase chain reaction product to nanoparticles functionalized with species-specific oligonucleotide probes or with the species-specific oligonucleotide probes alone. We carried out a series of DNA detection experiments using the invasive freshwater quagga mussel (Dreissena bugensis) to evaluate the capability of the LTS platform for invasive species detection. Specifically, we tested LTS sensitivity to (i) DNA concentrations of a single target species, (ii) the presence of a target species within a mixed sample of other closely related species, (iii) species-specific functionalized nanoparticles versus species-specific oligonucleotide probes alone, and (iv) amplified DNA fragments versus unamplified genomic DNA. We demonstrate that LTS is a highly sensitive technique for rapid target species detection, with detection limits in the picomolar range, capable of successful identification in multispecies samples containing target and non-target species DNA. These results indicate that the LTS DNA detection platform will be useful for field application of target species. Additionally, we find that LTS detection is effective with species-specific oligonucleotide tags alone or when they are attached to polystyrene nanobeads and with both amplified and unamplified DNA, indicating that the technique may also have versatility for broader applications.

  19. Advanced laser sensing receiver concepts based on FPA technology

    International Nuclear Information System (INIS)

    Jacobson, Phillip L.; Petrin, Roger R.; Jolin, John L.; Foy, Bernard R.; Lowrance, J.L.; Renda, George

    2002-01-01

    The ultimate performance of any remote sensor is ideally governed by the hardware signal-to-noise capability and allowed signal-averaging time. In real-world scenarios, this may not be realizable and the limiting factors may suggest the need for more advanced capabilities. Moving from passive to active remote sensors offers the advantage of control over the illumination source, the laser. Added capabilities may include polarization discrimination, instantaneous imaging, range resolution, simultaneous multi-spectral measurement, or coherent detection. However, most advanced detection technology has been engineered heavily towards the straightforward passive sensor requirements, measuring an integrated photon flux. The need for focal plane array technology designed specifically for laser sensing has been recognized for some time, but advances have only recently made the engineering possible. This paper will present a few concepts for laser sensing receiver architectures, the driving specifications behind those concepts, and test/modeling results of such designs.

  20. The laser-based calibration system of delta spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Malakhov, A.I. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Anisimov, Yu.S. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Gmuca, S. [Inst. of Physics, SAS, Bratislava (Slovakia); Kizka, V.A. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Kliman, J. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Inst. of Physics, SAS, Bratislava (Slovakia); Krasnov, V.A. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Kurepin, A.B. [Inst. for Nuclear Research RAS, Moscow (Russian Federation); Kuznetsov, S.N. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Livanov, A.N. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Matousek, V. [Inst. of Physics, SAS, Bratislava (Slovakia); Morhac, M. [Inst. of Physics, SAS, Bratislava (Slovakia)]. E-mail: Miroslav.Morhac@savba.sk; Turzo, I. [Inst. of Physics, SAS, Bratislava (Slovakia)

    2006-10-15

    We present a report on a laser calibration system of DELTA spectrometer that has been designed and developed in the Laboratory of High Energies, JINR, Dubna. The system is intended for monitoring and continuous stabilization of the outputs of the detectors of the spectrometer. The UV nitrogen pulse laser along with optical filters, collection of optical fibers and plastic scintillators serving for conversion of UV light pulses to longer wavelength and for diffusion of the light beam to illuminate 300 photomultipliers are used. We stabilize the positions of laser peaks by corrections of high voltages of the corresponding photomultipliers. The proposed system allows one to accomplish the stabilization during the experiment with the use of the same electronics. The control software together with the first results from test runs are described as well.

  1. Vendor-based laser damage metrology equipment supporting the National Ignition Facility

    International Nuclear Information System (INIS)

    Campbell, J. H; Jennings, R. T.; Kimmons, J. F.; Kozlowski, M. R.; Mouser, R. P.; Schwatz, S.; Stolz, C. J.; Weinzapfel, C. L.

    1998-01-01

    A sizable laser damage metrology effort is required as part of optics production and installation for the 192 beam National Ignition Facility (NIF) laser. The large quantities, high damage thresholds, and large apertures of polished and coated optics necessitates vendor-based metrology equipment to assure component quality during production. This equipment must be optimized to provide the required information as rapidly as possible with limited operator experience. The damage metrology tools include: (1) platinum inclusion damage test systems for laser amplifier slabs, (2) laser conditioning stations for mirrors and polarizers, and (3) mapping and damage testing stations for UV transmissive optics. Each system includes a commercial Nd:YAG laser, a translation stage for the optics, and diagnostics to evaluate damage. The scanning parameters, optical layout, and diagnostics vary with the test fluences required and the damage morphologies expected. This paper describes the technical objectives and milestones involved in fulfilling these metrology requirements

  2. Digital Communication System Based on Polarization Self-Modulation in Lasers

    Science.gov (United States)

    Tabarin, V. A.; Ikonnikov, V. P.; Shatalov, A. N.

    2014-09-01

    Polarization self-modulation in lasers can be used to create instruments for generating optical pulses at very high repetition rates without using high-speed electronics. Self-oscillation is observed when part of the output of a laser is returned to the laser after a 90° polarization change. A practical scheme based on polarization self-modulation in a 3.39-μm helium-neon laser is proposed for pulsed code data transmission with an yttrium-iron garnet magnetooptical Q-switch. Highly efficient transmission of digital signals is implemented with a repetition rate of 75 MHz, equivalent to half the free spectral range of the laser.

  3. Characterization of FBG sensor interrogation based on a FDML wavelength swept laser

    Science.gov (United States)

    Jung, Eun Joo; Kim, Chang-Seok; Jeong, Myung Yung; Kim, Moon Ki; Jeon, Min Yong; Jung, Woonggyu; Chen, Zhongping

    2012-01-01

    In this study, we develop an ultra-fast fiber Bragg grating sensor system that is based on the Fourier domain mode-locked (FDML) swept laser. A FDML wavelength swept laser has many advantages compared to the conventional wavelength swept laser source, such as high-speed interrogation, narrow spectral sensitivity, and high phase stability. The newly developed FDML wavelength swept laser shows a superior performance of a high scan rate of 31.3 kHz and a broad scan range of over 70 nm simultaneously. The performance of the grating sensor interrogating system using a FDML wavelength swept laser is characterized in both static and dynamic strain responses. PMID:18852764

  4. Diode laser based resonance ionization mass spectrometry for spectroscopy and trace analysis of uranium isotopes

    International Nuclear Information System (INIS)

    Hakimi, Amin

    2013-01-01

    In this doctoral thesis, the upgrade and optimization of a diode laser system for high-resolution resonance ionization mass spectrometry is described. A frequency-control system, based on a double-interferometric approach, allowing for absolute stabilization down to 1 MHz as well as frequency detunings of several GHz within a second for up to three lasers in parallel was optimized. This laser system was used for spectroscopic studies on uranium isotopes, yielding precise and unambiguous level energies, total angular momenta, hyperfine constants and isotope shifts. Furthermore, an efficient excitation scheme which can be operated with commercial diode lasers was developed. The performance of the complete laser mass spectrometer was optimized and characterized for the ultra-trace analysis of the uranium isotope 236 U, which serves as a neutron flux dosimeter and tracer for radioactive anthropogenic contaminations in the environment. Using synthetic samples, an isotope selectivity of ( 236 U)/( 238 U) = 4.5(1.5) . 10 -9 was demonstrated.

  5. A Laser-based Ultrasonic Inspection System to Detect Micro Fatigue Cracks

    International Nuclear Information System (INIS)

    Park, Seung Kyu; Baik, Sung Hoon; Park, Moon Cheol; Lim, Chang Hwan; Cha, Hyung Ki

    2005-01-01

    Laser-based ultrasonic techniques have been established as a viable non-contact alternative to piezoelectric transducers for generating and receiving ultrasound. Laser-based ultrasonic inspection system provides a number of advantages over the conventional generation by piezoelectric transducers, especially a non-contact generation and detection of ultrasonic waves, high spatial scanning resolution, controllable narrow-band and wide-band spectrum, absolute measurements of the moving distance, use of fiber optics, and an ability to operate on curved and rough surfaces and at hard-to-access locations like a nuclear power plant. Ochiai and Miura used the laser-based ultrasound to detect micro fatigue cracks for the inspection of a material degradation in nuclear power plants. This widely applicable laser-based ultrasonic inspection system is comparatively expensive and provides low signal-to-noise ratio to measure ultrasound by using the laser interferometer. Many studies have been carried out to improve the measuring efficiency of the laser interferometer. One of the widely used laser interferometer types to measure the ultrasound is the Confocal Fabry-Perot Interferometer(CFPI). The measurement gain of the CFPI is slightly and continually varied according to the small change of the cavity length and the fluctuations of the measuring laser beam frequency with time. If we continually adjust the voltage of a PZT which is fixed to one of the interferometer mirrors, the optimum working point of the CFPI can be fixed. Though a static stabilizer can fix the gain of the CFPI where the CW laser beam is targeted at one position, it can not be used when the CW laser beam is scanned like a scanning laser source(SLS) technique. A dynamic stabilizer can be used for the scanning ultrasonic inspection system. A robust dynamic stabilizer is needed for an application to the industrial inspection fields. Kromine showed that the SLS technique is effective to detect small fatigue cracks

  6. Study and Development of a Laser Based Alignment System

    CERN Multimedia

    Stern, G

    2014-01-01

    CLIC (Compact Linear Collider) has tight requirements regarding pre-alignment of beam related components: 10 µm accuracy over a sliding window of 200 m along the 20 km of linac. To perform such an alignment, a new system is proposed combining laser beam as straight line reference and camera/shutter assemblies as sensors. The poster describes the alignment system and shows results regarding laser pointing stability with respect to time, shutter type, distance and environment. These results give a frame for future building and calibrating of sensors.

  7. Reflectors and tuning elements for widely-tunable GaAs-based sampled grating DBR lasers

    Science.gov (United States)

    Brox, O.; Wenzel, H.; Della Case, P.; Tawfieq, M.; Sumpf, B.; Weyers, M.; Knigge, A.

    2018-02-01

    Widely-tunable lasers without moving parts are attractive light sources for sensors in industry and biomedicine. In contrast to InP based sampled grating (SG) distributed Bragg reflector (DBR) diode lasers which are commercially available, shorter wavelength GaAs SG-DBR lasers are still under development. One reason is the difficulty to integrate gratings with coupling coefficients that are high enough for functional grating bursts with lengths below 10 μm. Recently we have demonstrated > 20 nm wide quasi-continuous tuning with a GaAs based SG-DBR laser emitting around 975 nm. Wavelength selective reflectors are realized with SGs having different burst periods for the front and back mirrors. Thermal tuning elements (resistors) which are placed on top of the SG allow the control of the spectral positions of the SG reflector combs and hence to adjust the Vernier mode. In this work we characterize subsections of the developed SG-DBR laser to further improve its performance. We study the impact of two different vertical structures (with vertical far field FWHMs of 41° and 24°) and two grating orders on the coupling coefficient. Gratings with coupling coefficients above 350 cm-1 have been integrated into SG-DBR lasers. We also examine electronic tuning elements (a technique which is typically applied in InP based SG-DBR lasers and allows tuning within nanoseconds) and discuss the limitations in the GaAs material system

  8. Engineering fluidic delays in paper-based devices using laser direct-writing.

    Science.gov (United States)

    He, P J W; Katis, I N; Eason, R W; Sones, C L

    2015-10-21

    We report the use of a new laser-based direct-write technique that allows programmable and timed fluid delivery in channels within a paper substrate which enables implementation of multi-step analytical assays. The technique is based on laser-induced photo-polymerisation, and through adjustment of the laser writing parameters such as the laser power and scan speed we can control the depth and/or the porosity of hydrophobic barriers which, when fabricated in the fluid path, produce controllable fluid delay. We have patterned these flow delaying barriers at pre-defined locations in the fluidic channels using either a continuous wave laser at 405 nm, or a pulsed laser operating at 266 nm. Using this delay patterning protocol we generated flow delays spanning from a few minutes to over half an hour. Since the channels and flow delay barriers can be written via a common laser-writing process, this is a distinct improvement over other methods that require specialist operating environments, or custom-designed equipment. This technique can therefore be used for rapid fabrication of paper-based microfluidic devices that can perform single or multistep analytical assays.

  9. Repurposing mainstream CNC machine tools for laser-based additive manufacturing

    Science.gov (United States)

    Jones, Jason B.

    2016-04-01

    The advent of laser technology has been a key enabler for industrial 3D printing, known as Additive Manufacturing (AM). Despite its commercial success and unique technical capabilities, laser-based AM systems are not yet able to produce parts with the same accuracy and surface finish as CNC machining. To enable the geometry and material freedoms afforded by AM, yet achieve the precision and productivity of CNC machining, hybrid combinations of these two processes have started to gain traction. To achieve the benefits of combined processing, laser technology has been integrated into mainstream CNC machines - effectively repurposing them as hybrid manufacturing platforms. This paper reviews how this engineering challenge has prompted beam delivery innovations to allow automated changeover between laser processing and machining, using standard CNC tool changers. Handling laser-processing heads using the tool changer also enables automated change over between different types of laser processing heads, further expanding the breadth of laser processing flexibility in a hybrid CNC. This paper highlights the development, challenges and future impact of hybrid CNCs on laser processing.

  10. Analysis of laser remote fusion cutting based on a mathematical model

    Energy Technology Data Exchange (ETDEWEB)

    Matti, R. S. [Department of Engineering Sciences and Mathematics, Luleå University of Technology, S-971 87 Luleå (Sweden); Department of Mechanical Engineering, College of Engineering, University of Mosul, Mosul (Iraq); Ilar, T.; Kaplan, A. F. H. [Department of Engineering Sciences and Mathematics, Luleå University of Technology, S-971 87 Luleå (Sweden)

    2013-12-21

    Laser remote fusion cutting is analyzed by the aid of a semi-analytical mathematical model of the processing front. By local calculation of the energy balance between the absorbed laser beam and the heat losses, the three-dimensional vaporization front can be calculated. Based on an empirical model for the melt flow field, from a mass balance, the melt film and the melting front can be derived, however only in a simplified manner and for quasi-steady state conditions. Front waviness and multiple reflections are not modelled. The model enables to compare the similarities, differences, and limits between laser remote fusion cutting, laser remote ablation cutting, and even laser keyhole welding. In contrast to the upper part of the vaporization front, the major part only slightly varies with respect to heat flux, laser power density, absorptivity, and angle of front inclination. Statistical analysis shows that for high cutting speed, the domains of high laser power density contribute much more to the formation of the front than for low speed. The semi-analytical modelling approach offers flexibility to simplify part of the process physics while, for example, sophisticated modelling of the complex focused fibre-guided laser beam is taken into account to enable deeper analysis of the beam interaction. Mechanisms like recast layer generation, absorptivity at a wavy processing front, and melt film formation are studied too.

  11. Compact gain saturated plasma based X-ray lasers down to 6.9nm

    Science.gov (United States)

    Rocca, Jorge; Wang, Y.; Wang, S.; Rockwood, A.; Berrill, M.; Shlyaptsev, V.

    2017-10-01

    Plasma based soft x-ray amplifiers allow many experiments requiring bright, high energy soft x-ray laser pulses to be conducted in compact facilities. We have extended the wavelength of compact gain saturated x-ray lasers to 6.89 nm in a Ni-like Gd plasma generated by a Ti:Sa laser. Gain saturated laser operation was also obtained at 7.36 nm in Ni-like Sm. Isolectronic scaling and optimization of laser pre-pulse duration allowed us to also observe strong lasing at 6.6 nm and 6.1 nm in Ni-like Tb, and amplification at 6.4 nm and 5.89 nm in Ni-like Dy. The results were obtained by transient laser heating of solid targets with traveling wave excitation at progressively increased gracing incidence angles. We show that the optimum pump angle of incidence for collisional Ni-like lasers increases linearly with atomic number from Z =42 to Z =66, reaching 43 degrees for Ni-like Dy, in good agreement with hydrodynamic/atomic physics simulations. These results will enable single-shot nano-scale imaging and other application of sub-7 nm lasers to be performed at compact facilities. Work supported by Grant DE-FG02-4ER15592 of the Department of Energy, Office of Science, and by the National Science Foundation Grant ECCS 1509925.

  12. Analysis of laser remote fusion cutting based on a mathematical model

    International Nuclear Information System (INIS)

    Matti, R. S.; Ilar, T.; Kaplan, A. F. H.

    2013-01-01

    Laser remote fusion cutting is analyzed by the aid of a semi-analytical mathematical model of the processing front. By local calculation of the energy balance between the absorbed laser beam and the heat losses, the three-dimensional vaporization front can be calculated. Based on an empirical model for the melt flow field, from a mass balance, the melt film and the melting front can be derived, however only in a simplified manner and for quasi-steady state conditions. Front waviness and multiple reflections are not modelled. The model enables to compare the similarities, differences, and limits between laser remote fusion cutting, laser remote ablation cutting, and even laser keyhole welding. In contrast to the upper part of the vaporization front, the major part only slightly varies with respect to heat flux, laser power density, absorptivity, and angle of front inclination. Statistical analysis shows that for high cutting speed, the domains of high laser power density contribute much more to the formation of the front than for low speed. The semi-analytical modelling approach offers flexibility to simplify part of the process physics while, for example, sophisticated modelling of the complex focused fibre-guided laser beam is taken into account to enable deeper analysis of the beam interaction. Mechanisms like recast layer generation, absorptivity at a wavy processing front, and melt film formation are studied too

  13. Quantum dash based single section mode locked lasers for photonic integrated circuits.

    Science.gov (United States)

    Joshi, Siddharth; Calò, Cosimo; Chimot, Nicolas; Radziunas, Mindaugas; Arkhipov, Rostislav; Barbet, Sophie; Accard, Alain; Ramdane, Abderrahim; Lelarge, Francois

    2014-05-05

    We present the first demonstration of an InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits (PICs). The laser cavity is closed using a specifically designed Bragg reflector without compromising the mode-locking performance of the self pulsating laser. This enables the integration of single-section mode-locked laser in photonic integrated circuits as on-chip frequency comb generators. We also investigate the relations between cavity modes in such a device and demonstrate how the dispersion of the complex mode frequencies induced by the Bragg grating implies a violation of the equi-distance between the adjacent mode frequencies and, therefore, forbids the locking of the modes in a classical Bragg Device. Finally we integrate such a Bragg Mirror based laser with Semiconductor Optical Amplifier (SOA) to demonstrate the monolithic integration of QDash based low phase noise sources in PICs.

  14. Laser-based target tracking using principal component descriptors

    CSIR Research Space (South Africa)

    Burke, Michael G

    2010-11-01

    Full Text Available scans are pre-filtered using a median filter, in order to remove salt and pepper noise. Thereafter, scans are divided into segments through jump-distance classification. This in- volves a simple pass over the laser data, separating segments...

  15. Scanning laser beam displays based on a 2D MEMS

    Science.gov (United States)

    Niesten, Maarten; Masood, Taha; Miller, Josh; Tauscher, Jason

    2010-05-01

    The combination of laser light sources and MEMS technology enables a range of display systems such as ultra small projectors for mobile devices, head-up displays for vehicles, wearable near-eye displays and projection systems for 3D imaging. Images are created by scanning red, green and blue lasers horizontally and vertically with a single two-dimensional MEMS. Due to the excellent beam quality of laser beams, the optical designs are efficient and compact. In addition, the laser illumination enables saturated display colors that are desirable for augmented reality applications where a virtual image is used. With this technology, the smallest projector engine for high volume manufacturing to date has been developed. This projector module has a height of 7 mm and a volume of 5 cc. The resolution of this projector is WVGA. No additional projection optics is required, resulting in an infinite focus depth. Unlike with micro-display projection displays, an increase in resolution will not lead to an increase in size or a decrease in efficiency. Therefore future projectors can be developed that combine a higher resolution in an even smaller and thinner form factor with increased efficiencies that will lead to lower power consumption.

  16. Reconstruction of laser beam wavefronts based on mode analysis

    CSIR Research Space (South Africa)

    Schulze, C

    2013-07-01

    Full Text Available . Experimental setup for measuring the far field of differ- ently aberrated Gaussian beams. He–Ne, helium–neon laser; L 1–3 , lenses; M, mirror; SLM 1 , spatial light modulator; CCD, camera. Fig. 8. Theoretical and measured far fields FFth and FFm of a...

  17. Novel laser nanomaterials based on rare-earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Darayas N., E-mail: dpatel@oakwood.edu [Oakwood University, Department of Mathematics and Computer Science, 7000 Adventist Blvd. Huntsville, AL 35896 (United States); Hardy, Lauren A.; Smith, Tabatha J.; Smith, Eva S.; Wright, Donald M. [Oakwood University, Department of Mathematics and Computer Science, 7000 Adventist Blvd. Huntsville, AL 35896 (United States); Sarkisov, Sergey [SSS Optical Technologies, LLC, 515 Sparkman Drive, Suite 122, Huntsville, AL 35816 (United States)

    2013-01-15

    We report on the infrared-to-visible upconversion luminescence in microcrystalline powders and photonic crystal fibers filled with nanocolloids of trivalent rare-earth ion co-doped NaYF{sub 4} phosphor. The phosphor was prepared using a simple co-precipitation synthetic method. Nanocolloids of the phosphor were prepared by selective precipitation in methanol and laser ablation in water. Optical dynamic scatterometry determined average particle sizes of the nanocolloids of 1.5-1.9 nm in methanol and 83.8-86.4 nm in water. Nanocolloids of these phosphors were utilized as laser filling medium in photonic crystal fibers. - Highlights: Black-Right-Pointing-Pointer Synthesize highly efficient hexagonal-phase NaYF{sub 4}:Er{sup 3+}, Yb{sup 3+} powder and nanocolloid. Black-Right-Pointing-Pointer Laser/amplifier containing the NaYF{sub 4} nanocolloid were pumped with 980 nm diode laser. Black-Right-Pointing-Pointer Emission peaks were observed at 540 nm, 654 nm and 840.4 nm from the fiber arrangement.

  18. In situ TEM Raman spectroscopy and laser-based materials modification

    Energy Technology Data Exchange (ETDEWEB)

    Allen, F.I., E-mail: fiallen@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kim, E. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Andresen, N.C. [Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Grigoropoulos, C.P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Minor, A.M., E-mail: aminor@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2017-07-15

    We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS{sub 2} combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS{sub 2} are performed in situ.

  19. In situ TEM Raman spectroscopy and laser-based materials modification

    International Nuclear Information System (INIS)

    Allen, F.I.; Kim, E.; Andresen, N.C.; Grigoropoulos, C.P.; Minor, A.M.

    2017-01-01

    We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS_2 combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS_2 are performed in situ.

  20. Improved GPS-based Satellite Relative Navigation Using Femtosecond Laser Relative Distance Measurements

    Directory of Open Access Journals (Sweden)

    Hyungjik Oh

    2016-03-01

    Full Text Available This study developed an approach for improving Carrier-phase Differential Global Positioning System (CDGPS based realtime satellite relative navigation by applying laser baseline measurement data. The robustness against the space operational environment was considered, and a Synthetic Wavelength Interferometer (SWI algorithm based on a femtosecond laser measurement model was developed. The phase differences between two laser wavelengths were combined to measure precise distance. Generated laser data were used to improve estimation accuracy for the float ambiguity of CDGPS data. Relative navigation simulations in real-time were performed using the extended Kalman filter algorithm. The GPS and laser-combined relative navigation accuracy was compared with GPS-only relative navigation solutions to determine the impact of laser data on relative navigation. In numerical simulations, the success rate of integer ambiguity resolution increased when laser data was added to GPS data. The relative navigational errors also improved five-fold and two-fold, relative to the GPS-only error, for 250 m and 5 km initial relative distances, respectively. The methodology developed in this study is suitable for application to future satellite formation-flying missions.

  1. Transition between laser absorption dominated regimes in carbon-based plasma

    Directory of Open Access Journals (Sweden)

    K. Hajisharifi

    2017-09-01

    Full Text Available In this work, we investigate the energy absorption enhancement of a laser by adding a variety of light ion species to a primarily carbon-based plasma during the high-power laser interaction with the finite size targets. A developed Particle-In-Cell simulation code is used to study the reduction of laser reflectivity (stimulated backward scatterings in both Brillouin- and Raman-dominated regimes. The simulation is performed in various Carbon-light ion plasmas such as Carbon-Hydrogen, Carbon-Helium, Carbon-Deuterium, and Carbon-Tritium. The results show that, in the optimized condition, the inclusion of light Hydrogen ions into the Carbon-based plasma up to 50%-50% mixture enhances the laser absorption exceeding 20% in the Brillouin regime due to the suppression of laser reflectivity in contract to 4% in the Raman-dominated regime. Moreover, the absorption dominated regime switches from Raman to Brillouin regime by adding 50% of Hydrogen ions to a purely carbon target. The results of this investigation will be applicable to the laser-plasma experiments so long as the laser energy absorption in the Carbon plasma target, the most readily available material in laboratory, is concerned.

  2. Calibration method for a vision guiding-based laser-tracking measurement system

    International Nuclear Information System (INIS)

    Shao, Mingwei; Wei, Zhenzhong; Hu, Mengjie; Zhang, Guangjun

    2015-01-01

    Laser-tracking measurement systems (laser trackers) based on a vision-guiding device are widely used in industrial fields, and their calibration is important. As conventional methods typically have many disadvantages, such as difficult machining of the target and overdependence on the retroreflector, a novel calibration method is presented in this paper. The retroreflector, which is necessary in the normal calibration method, is unnecessary in our approach. As the laser beam is linear, points on the beam can be obtained with the help of a normal planar target. In this way, we can determine the function of a laser beam under the camera coordinate system, while its corresponding function under the laser-tracker coordinate system can be obtained from the encoder of the laser tracker. Clearly, when several groups of functions are confirmed, the rotation matrix can be solved from the direction vectors of the laser beams in different coordinate systems. As the intersection of the laser beams is the origin of the laser-tracker coordinate system, the translation matrix can also be determined. Our proposed method not only achieves the calibration of a single laser-tracking measurement system but also provides a reference for the calibration of a multistation system. Simulations to evaluate the effects of some critical factors were conducted. These simulations show the robustness and accuracy of our method. In real experiments, the root mean square error of the calibration result reached 1.46 mm within a range of 10 m, even though the vision-guiding device focuses on a point approximately 5 m away from the origin of its coordinate system, with a field of view of approximately 200 mm  ×  200 mm. (paper)

  3. A photonic ultra-wideband pulse generator based on relaxation oscillations of a semiconductor laser

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Pawlik, Michal

    2009-01-01

    A photonic ultra-wideband (UWB) pulse generator based on relaxation oscillations of a semiconductor laser is proposed and experimentally demonstrated. We numerically simulate the modulation response of a direct modulation laser (DML) and show that due to the relaxation oscillations of the laser......, the generated signals with complex shape in time domain match the Federal Communications Commission (FCC) mask in the frequency domain. Experimental results using a DML agree well with simulation predictions. Furthermore, we also experimentally demonstrate the generation of FCC compliant UWB signals...

  4. Past, Present and Future Aspects of Laser-Based Synchronization at FLASH

    OpenAIRE

    Schulz, Sebastian; Bousonville, Michael; Steffen, Bernd; Sydlo, Cezary; Zummack, Falco; Kozak, Tomasz; Predki, Pawel; Kuhl, Alexander; Czwalinna, Marie Kristin; Felber, Matthias; Heuer, Michael; Lamb, Thorsten; Mueller, Jost; Peier, Peter; Ruzin, Sergej

    2013-01-01

    Free-electron lasers, like FLASH and the upcoming European XFEL, are capable of producing XUV and X-ray pulses of a few femtoseconds duration. For time-resolved pump-probe experiments and the externally seeded operation mode it is crucial not only to stabilize the arrival time of the electron bunches, but also to achieve a synchronization accuracy of external lasers on the same timescale. This can only be realized with a laser-based synchronization infrastructure. At FLASH, a periodic femtose...

  5. Laser Rate Equation Based Filtering for Carrier Recovery in Characterization and Communication

    DEFF Research Database (Denmark)

    Piels, Molly; Iglesias Olmedo, Miguel; Xue, Weiqi

    2015-01-01

    We formulate a semiconductor laser rate equationbased approach to carrier recovery in a Bayesian filtering framework. Filter stability and the effect of model inaccuracies (unknown or un-useable rate equation coefficients) are discussed. Two potential application areas are explored: laser...... characterization and carrier recovery in coherent communication. Two rate equation based Bayesian filters, the particle filter and extended Kalman filter, are used in conjunction with a coherent receiver to measure frequency noise spectrum of a photonic crystal cavity laser with less than 20 nW of fiber...

  6. Joint Calibration of 3d Laser Scanner and Digital Camera Based on Dlt Algorithm

    Science.gov (United States)

    Gao, X.; Li, M.; Xing, L.; Liu, Y.

    2018-04-01

    Design a calibration target that can be scanned by 3D laser scanner while shot by digital camera, achieving point cloud and photos of a same target. A method to joint calibrate 3D laser scanner and digital camera based on Direct Linear Transformation algorithm was proposed. This method adds a distortion model of digital camera to traditional DLT algorithm, after repeating iteration, it can solve the inner and external position element of the camera as well as the joint calibration of 3D laser scanner and digital camera. It comes to prove that this method is reliable.

  7. Algal Biomass Analysis by Laser-Based Analytical Techniques—A Review

    Directory of Open Access Journals (Sweden)

    Pavel Pořízka

    2014-09-01

    Full Text Available Algal biomass that is represented mainly by commercially grown algal strains has recently found many potential applications in various fields of interest. Its utilization has been found advantageous in the fields of bioremediation, biofuel production and the food industry. This paper reviews recent developments in the analysis of algal biomass with the main focus on the Laser-Induced Breakdown Spectroscopy, Raman spectroscopy, and partly Laser-Ablation Inductively Coupled Plasma techniques. The advantages of the selected laser-based analytical techniques are revealed and their fields of use are discussed in detail.

  8. Design and Performance Analysis of Laser Displacement Sensor Based on Position Sensitive Detector (PSD)

    International Nuclear Information System (INIS)

    Song, H X; Wang, X D; Ma, L Q; Cai, M Z; Cao, T Z

    2006-01-01

    By using PSD as sensitive element, and laser diode as emitting element, laser displacement sensor based on triangulation method has been widely used. From the point of view of design, sensor and its performance were studied. Two different sensor configurations were described. Determination of the dimension, sensing resolution and comparison of the two different configurations were presented. The factors affecting the performance of the laser displacement sensor were discussed and two methods, which can eliminate the affection of dark current and environment light, are proposed

  9. Persistent challenges and frontiers in laser-based chemical analysis - signed, sealed, and delivered?

    International Nuclear Information System (INIS)

    Latkoczy, C.; Guenther, D.; Kaegi, R.

    2009-01-01

    Full text: The last years have been dedicated to push the spatial resolution capabilities of laser - based analytical methods towards the nanometer range. Progress, not just in the detection part using enhanced spectrometers but also in the laser sampling process itself using lasers with shorter pulse durations, paved the way to reach such limits. Nevertheless, the understanding of fundamental processes at such dimensions has gained more importance in order to explain and to control the various phenomena involved in the ablation and excitation processes. We will talk about current expectations, challenges and limitations, and present selected instrumental approaches to e.g. determine nanometer-sized colloid particles in aqueous systems. (author)

  10. Laser-based structural sensing and surface damage detection

    Science.gov (United States)

    Guldur, Burcu

    Damage due to age or accumulated damage from hazards on existing structures poses a worldwide problem. In order to evaluate the current status of aging, deteriorating and damaged structures, it is vital to accurately assess the present conditions. It is possible to capture the in situ condition of structures by using laser scanners that create dense three-dimensional point clouds. This research investigates the use of high resolution three-dimensional terrestrial laser scanners with image capturing abilities as tools to capture geometric range data of complex scenes for structural engineering applications. Laser scanning technology is continuously improving, with commonly available scanners now capturing over 1,000,000 texture-mapped points per second with an accuracy of ~2 mm. However, automatically extracting meaningful information from point clouds remains a challenge, and the current state-of-the-art requires significant user interaction. The first objective of this research is to use widely accepted point cloud processing steps such as registration, feature extraction, segmentation, surface fitting and object detection to divide laser scanner data into meaningful object clusters and then apply several damage detection methods to these clusters. This required establishing a process for extracting important information from raw laser-scanned data sets such as the location, orientation and size of objects in a scanned region, and location of damaged regions on a structure. For this purpose, first a methodology for processing range data to identify objects in a scene is presented and then, once the objects from model library are correctly detected and fitted into the captured point cloud, these fitted objects are compared with the as-is point cloud of the investigated object to locate defects on the structure. The algorithms are demonstrated on synthetic scenes and validated on range data collected from test specimens and test-bed bridges. The second objective of

  11. En Route: next-generation laser-plasma-based electron accelerators

    International Nuclear Information System (INIS)

    Hidding, Bernhard

    2008-05-01

    Accelerating electrons to relativistic energies is of fundamental interest, especially in particle physics. Today's accelerator technology, however, is limited by the maximum electric fields which can be created. This thesis presents results on various mechanisms aiming at exploiting the fields in focussed laser pulses and plasma waves for electron acceleration, which can be orders of magnitude higher than with conventional accelerators. With relativistic, underdense laser-plasma-interaction, quasimonoenergetic electron bunches with energies up to ∼50 MeV and normalized emittances of the order of 5mmmrad have been generated. This was achieved by focussing the ∼80 fs, 1 J pulses of the JETI-laser at the FSU Jena to intensities of several 10 19 W=cm 2 into gas jets. The experimental observations could be explained via ''bubble acceleration'', which is based on self-injection and acceleration of electrons in a highly nonlinear breaking plasma wave. For the rst time, this bubble acceleration was achieved explicitly in the self-modulated laser wakefield regime (SMLWFA). This quasimonoenergetic SMLWFA-regime stands out by relaxing dramatically the requirements on the driving laser pulse necessary to trigger bubble acceleration. This is due to self-modulation of the laser pulse in high-density gas jets, leading to ultrashort laser pulse fragments capable of initiating bubble acceleration. Electron bunches with durations < or similar 5 fs can thus be created, which is at least an order of magnitude shorter than with conventional accelerator technology. In addition, more than one laser pulse fragment can be powerful enough to drive a bubble. Distinct double peaks have been observed in the electron spectra, indicating that two quasimonoenergetic electron bunches separated by only few tens of fs have formed. This is backed up by PIC-Simulations (Particle-in-Cell). These results underline the feasibility of the construction of small table-top accelerators, while at the

  12. Toward compact and ultra-intense laser-based soft x-ray lasers

    Science.gov (United States)

    Sebban, S.; Depresseux, A.; Oliva, E.; Gautier, J.; Tissandier, F.; Nejdl, J.; Kozlova, M.; Maynard, G.; Goddet, J. P.; Tafzi, A.; Lifschitz, A.; Kim, H. T.; Jacquemot, S.; Rousseau, P.; Zeitoun, P.; Rousse, A.

    2018-01-01

    We report here recent work on an optical field ionized (OFI), high-order harmonic-seeded EUV laser. The amplifying medium is a plasma of nickel-like krypton obtained by OFI when focusing a 1 J, 30 fs, circularly-polarized, infrared pulse into a krypton-filled gas cell or krypton gas jet. The lasing transition is the 3d94d (J = 0) → 3d94p (J = 1) transition of Ni-like krypton ions at 32.8 nm and is pumped by collisions with hot electrons. The gain dynamics was probed by seeding the amplifier with a high-order harmonic pulse at different delays. The gain duration monotonically decreased from 7 ps to an unprecedented shortness of 450 fs full width at half-maximum as the amplification peak rose from 150 to 1200 with an increase of the plasma density from 3 × 1018 to 1.2 × 1020 cm-3. The integrated energy of the EUV laser pulse was also measured, and found to be around 2 μJ. It is to be noted that in the ASE mode, longer amplifiers were achieved (up to 2 cm), yielding EUV outputs up to 14 μJ.

  13. Femtosecond laser based small incision lenticule extraction for moderate and high myopia

    DEFF Research Database (Denmark)

    Hjortdal, Jesper Østergaard; Asp, Sven; Ivarsen, Anders

    Femtosecond laser based small incision lenticule extraction for moderate and high myopia. Jesper Hjortdal, Sven Asp, Anders Ivarsen, Anders Vestergaard Department of Ophthalmology, Aarhus University Hospital, Denmark Purpose: ReLEx® smile is a new keratorefractive procedure whereby a stromal lent....... Refractive predictability, safety and patient satisfaction at 3 months seems equal to ReLEx flex and FS-LASIK. Optimizing laser energy settings and surgeon experience is important to minimize initial inferior results....

  14. Coherent anti-Stokes Raman scattering spectroscope/microscope based on a widely tunable laser source

    Science.gov (United States)

    Dementjev, A.; Gulbinas, V.; Serbenta, A.; Kaucikas, M.; Niaura, G.

    2010-03-01

    We present a coherent anti-Stokes Raman scattering (CARS) microscope based on a robust and simple laser source. A picosecond laser operating in a cavity dumping regime at the 1 MHz repetition rate was used to pump a traveling wave optical parametric generator, which serves as a two-color excitation light source for the CARS microscope. We demonstrate the ability of the presented CARS microscope to measure CARS spectra and images by using several detection schemes.

  15. 2.3 µm laser potential of TeO2 based glasses

    Science.gov (United States)

    Denker, B. I.; Dorofeev, V. V.; Galagan, B. I.; Motorin, S. E.; Sverchkov, S. E.

    2017-09-01

    Tm3+ doped TeO2-based well-dehydrated glasses were synthesized and investigated. The analysis of their spectral and relaxation properties have showed that these glasses can be a suitable host for bulk and fiber lasers emitting at ~2.3 µm wavelength (3H4-3H5 Tm3+ transition). Laser action in the bulk glass sample was demonstrated.

  16. Physics and engineering of compact quantum dot-based lasers for biophotonics

    CERN Document Server

    Rafailov, Edik U

    2013-01-01

    Written by a team of European experts in the field, this book addresses the physics, the principles, the engineering methods, and the latest developments of efficient and compact ultrafast lasers based on novel quantum-dot structures and devices, as well as their applications in biophotonics. Recommended reading for physicists, engineers, students and lecturers in the fields of photonics, optics, laser physics, optoelectronics, and biophotonics.

  17. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    Science.gov (United States)

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  18. Laser induced structural transformation in chalcogenide based superlattices

    International Nuclear Information System (INIS)

    Zallo, Eugenio; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella

    2016-01-01

    Superlattices made of alternating layers of nominal GeTe and Sb 2 Te 3 have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  19. Long distance measurement with a femtosecond laser based frequency comb

    Science.gov (United States)

    Bhattacharya, N.; Cui, M.; Zeitouny, M. G.; Urbach, H. P.; van den Berg, S. A.

    2017-11-01

    Recent advances in the field of ultra-short pulse lasers have led to the development of reliable sources of carrier envelope phase stabilized femtosecond pulses. The pulse train generated by such a source has a frequency spectrum that consists of discrete, regularly spaced lines known as a frequency comb. In this case both the frequency repetition and the carrier-envelope-offset frequency are referenced to a frequency standard, like an atomic clock. As a result the accuracy of the frequency standard is transferred to the optical domain, with the frequency comb as transfer oscillator. These unique properties allow the frequency comb to be applied as a versatile tool, not only for time and frequency metrology, but also in fundamental physics, high-precision spectroscopy, and laser noise characterization. The pulse-to-pulse phase relationship of the light emitted by the frequency comb has opened up new directions for long range highly accurate distance measurement.

  20. Laser induced structural transformation in chalcogenide based superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Zallo, Eugenio, E-mail: zallo@pdi-berlin.de; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2016-05-30

    Superlattices made of alternating layers of nominal GeTe and Sb{sub 2}Te{sub 3} have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  1. Laser-Scribed Graphene Electrodes for Aptamer-Based Biosensing

    KAUST Repository

    Fenzl, Christoph

    2017-04-25

    Graphene as a transducer material has produced some of the best performing sensing approaches to date opening the door toward integrated miniaturized all-carbon point-of-care devices. Addressing this opportunity, laser-scribed graphene(LSG) electrodes are demonstrated here as highly sensitive and reliable biosensor transducers in blood serum analysis. These flexible electrodes with large electrochemical surface areas were fabricated using a direct-write laser process on polyimide foils. A universal immobilization approach is established by anchoring 1-pyrenebutyric acid to the graphene and subsequently covalently attaching an aptamer against the coagulation factor thrombin as an exemplary bioreceptor to the carboxyl groups. The resulting biosensor displays extremely low detection limits of 1 pM in buffer and 5 pM in the complex matrix of serum.

  2. Multi-parameter sensor based on random fiber lasers

    Directory of Open Access Journals (Sweden)

    Yanping Xu

    2016-09-01

    Full Text Available We demonstrate a concept of utilizing random fiber lasers to achieve multi-parameter sensing. The proposed random fiber ring laser consists of an erbium-doped fiber as the gain medium and a random fiber grating as the feedback. The random feedback is effectively realized by a large number of reflections from around 50000 femtosecond laser induced refractive index modulation regions over a 10cm standard single mode fiber. Numerous polarization-dependent spectral filters are formed and superimposed to provide multiple lasing lines with high signal-to-noise ratio up to 40dB, which gives an access for a high-fidelity multi-parameter sensing scheme. The number of sensing parameters can be controlled by the number of the lasing lines via input polarizations and wavelength shifts of each peak can be explored for the simultaneous multi-parameter sensing with one sensing probe. In addition, the random grating induced coupling between core and cladding modes can be potentially used for liquid medical sample sensing in medical diagnostics, biology and remote sensing in hostile environments.

  3. Structural damage identification based on laser ultrasonic propagation imaging technology

    Science.gov (United States)

    Chia, Chen-Ciang; Jang, Si-Gwang; Lee, Jung-Ryul; Yoon, Dong-Jin

    2009-06-01

    An ultrasonic propagation imaging (UPI) system consisted of a Q-switched Nd-YAG pulsed laser and a galvanometer laser mirror scanner was developed. The system which requires neither reference data nor fixed focal length could be used for health monitoring of curved structures. If combined with a fiber acoustic wave PZT (FAWPZT) sensor, it could be used to inspect hot target structures that present formidable challenges to the usage of contact piezoelectric transducers mainly due to the operating temperature limitation of transducers and debonding problem due to the mismatch of coefficient of thermal expansion between the target, transducer and bonding material. The inspection of a stainless steel plate with a curvature radius of about 4 m, having 2mm×1mm open-crack was demonstrated at 150°C using a FAWPZT sensor welded on the plate. Highly-curved surfaces scanning capability and adaptivity of the system for large laser incident angle up to 70° was demonstrated on a stainless steel cylinder with 2mm×1mm open-crack. The imaging results were presented in ultrasonic propagation movie which was a moving wavefield emerged from an installed ultrasonic sensor. Damages were localized by the scattering wavefields. The result images enabled easy detection and interpretation of structural defects as anomalies during ultrasonic wave propagation.

  4. An analysis of transient thermal properties for high power GaN-based laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Min; Kim, Seungtaek; Kang, Sung Bok; Kim, Young Jin; Jeong, Hoon; Lee, Kyeongkyun; Kim, Jongseok [Korea Institute of Industrial Technology, 35-3 Hongcheon-Ri, Ipjang-Myeon, Cheonan, Chungnam 331-825 (Korea); Lee, Sangdon; Suh, Dongsik [QSI Co., Ltd., 315-9 Cheonheung-Ri, Sungger-Eup, Cheonan, Chungnam 330-836 (Korea); Yi, Jeong Hoon; Choi, Yoonho; Jung, Seok Gu; Noh, Minsoo [LG Electronics Advanced Research Institute, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea)

    2010-07-15

    Thermal properties of 405 nm GaN-based laser diodes were investigated by employing a transient heating response method based on the temperature dependence of diode forward voltage. Thermal resistances of materials consisting of packaged laser diodes were differentiated in transient thermal response curves at a current below threshold current. With a current above threshold current, no significant change in thermal resistances and difference between junction-up and junction-down laser diodes was observed at pulses shorter than 3 sec. From an analysis with long current injections, thermal resistance of a packaged laser diode with a junction-up bonding was {proportional_to}45 C/W which was higher than that of a junction-down bonded laser diode by {proportional_to}10 C/W. Further analyses based on parameters obtained from voltage recovery curves indicated that the time constant for cooling is directly related to the thermal resistance and thermal capacitance of a laser diode package. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Feasibility of computed tomography based thermometry during interstitial laser heating in bovine liver

    International Nuclear Information System (INIS)

    Pandeya, G.D.; Klaessens, J.H.G.M.; Greuter, M.J.W.; Oudkerk, M.; Schmidt, B.; Flohr, T.; Hillegersberg, R. van

    2011-01-01

    To assess the feasibility of computed tomography (CT) based thermometry during interstitial laser heating in the bovine liver. Four freshly exercised cylindrical blocks of bovine tissue were heated using a continuous laser of Nd:YAG (wavelength: 1064 nm, active length: 30 mm, power: 10-30 W). All tissues were imaged at least once before and 7 times during laser heating using CT and temperatures were simultaneously measured with 5 calibrated thermal sensors. The dependency of the average CT numbers as a function of temperature was analysed with regression analysis and a CT thermal sensitivity was derived. During laser heating, the growing hypodense area was observed around the laser source and that area showed an increase as a function of time. The formation of hypodense area was caused by declining in CT numbers at increasing temperatures. The regression analysis showed an inverse linear dependency between temperature and average CT number with -0.65 ± 0.048 HU/ C (R 2 = 0.75) for the range of 18-85 C in bovine liver. The non-invasive CT based thermometry during interstitial laser heating is feasible in the bovine liver. CT based thermometry could be further developed and may be of potential use during clinical LITT of the liver. (orig.)

  6. Large angle and high linearity two-dimensional laser scanner based on voice coil actuators

    Science.gov (United States)

    Wu, Xin; Chen, Sihai; Chen, Wei; Yang, Minghui; Fu, Wen

    2011-10-01

    A large angle and high linearity two-dimensional laser scanner with an in-house ingenious deflection angle detecting system is developed based on voice coil actuators direct driving mechanism. The specially designed voice coil actuators make the steering mirror moving at a sufficiently large angle. Frequency sweep method based on virtual instruments is employed to achieve the natural frequency of the laser scanner. The response shows that the performance of the laser scanner is limited by the mechanical resonances. The closed-loop controller based on mathematical model is used to reduce the oscillation of the laser scanner at resonance frequency. To design a qualified controller, the model of the laser scanner is set up. The transfer function of the model is identified with MATLAB according to the tested data. After introducing of the controller, the nonlinearity decreases from 13.75% to 2.67% at 50 Hz. The laser scanner also has other advantages such as large deflection mirror, small mechanical structure, and high scanning speed.

  7. Microscope self-calibration based on micro laser line imaging and soft computing algorithms

    Science.gov (United States)

    Apolinar Muñoz Rodríguez, J.

    2018-06-01

    A technique to perform microscope self-calibration via micro laser line and soft computing algorithms is presented. In this technique, the microscope vision parameters are computed by means of soft computing algorithms based on laser line projection. To implement the self-calibration, a microscope vision system is constructed by means of a CCD camera and a 38 μm laser line. From this arrangement, the microscope vision parameters are represented via Bezier approximation networks, which are accomplished through the laser line position. In this procedure, a genetic algorithm determines the microscope vision parameters by means of laser line imaging. Also, the approximation networks compute the three-dimensional vision by means of the laser line position. Additionally, the soft computing algorithms re-calibrate the vision parameters when the microscope vision system is modified during the vision task. The proposed self-calibration improves accuracy of the traditional microscope calibration, which is accomplished via external references to the microscope system. The capability of the self-calibration based on soft computing algorithms is determined by means of the calibration accuracy and the micro-scale measurement error. This contribution is corroborated by an evaluation based on the accuracy of the traditional microscope calibration.

  8. Cascade Type-I Quantum Well GaSb-Based Diode Lasers

    Directory of Open Access Journals (Sweden)

    Leon Shterengas

    2016-05-01

    Full Text Available Cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers operating in a spectral region from 1.9 to 3.3 μm. Carrier recycling between quantum well gain stages was realized using band-to-band tunneling in GaSb/AlSb/InAs heterostructure complemented with optimized electron and hole injector regions. Coated devices with an ~100-μm-wide aperture and a 3-mm-long cavity demonstrated continuous wave (CW output power of 1.96 W near 2 μm, 980 mW near 3 μm, 500 mW near 3.18 μm, and 360 mW near 3.25 μm at 17–20 °C—a nearly or more than twofold increase compared to previous state-of-the-art diode lasers. The utilization of the different quantum wells in the cascade laser heterostructure was demonstrated to yield wide gain lasers, as often desired for tunable laser spectroscopy. Double-step etching was utilized to minimize both the internal optical loss and the lateral current spreading penalties in narrow-ridge lasers. Narrow-ridge cascade diode lasers operate in a CW regime with ~100 mW of output power near and above 3 μm and above 150 mW near 2 μm.

  9. Endoscopic Laser-Based 3D Imaging for Functional Voice Diagnostics

    Directory of Open Access Journals (Sweden)

    Marion Semmler

    2017-06-01

    Full Text Available Recently, we reported on the in vivo application of a miniaturized measuring device for 3D visualization of the superior vocal fold vibrations from high-speed recordings in combination with a laser projection unit (LPU. As a long-term vision for this proof of principle, we strive to integrate the further developed laserendoscopy as a diagnostic method in daily clinical routine. The new LPU mainly comprises a Nd:YAG laser source (532 nm/CW/2 ω and a diffractive optical element (DOE generating a regular laser grid (31 × 31 laser points that is projected on the vocal folds. By means of stereo triangulation, the 3D coordinates of the laser points are reconstructed from the endoscopic high-speed footage. The new design of the laserendoscope constitutes a compromise between robust image processing and laser safety regulations. The algorithms for calibration and analysis are now optimized with respect to their overall duration and the number of required interactions, which is objectively assessed using binary classifiers. The sensitivity and specificity of the calibration procedure are increased by 40.1% and 22.3%, which is statistically significant. The overall duration for the laser point detection is reduced by 41.9%. The suggested semi-automatic reconstruction software represents an important stepping-stone towards potential real time processing and a comprehensive, objective diagnostic tool of evidence-based medicine.

  10. Characteristics of thin-film transistors based on silicon nitride passivation by excimer laser direct patterning

    International Nuclear Information System (INIS)

    Chen, Chao-Nan; Huang, Jung-Jie

    2013-01-01

    This study explored the removal of silicon nitride using KrF laser ablation technology with a high threshold fluence of 990 mJ/cm 2 . This technology was used for contact hole patterning to fabricate SiN x -passivation-based amorphous-silicon thin films in a transistor device. Compared to the photolithography process, laser direct patterning using KrF laser ablation technology can reduce the number of process steps by at least three. Experimental results showed that the mobility and threshold voltages of thin film transistors patterned using the laser process were 0.16 cm 2 /V-sec and 0.2 V, respectively. The device performance and the test results of gate voltage stress reliability demonstrated that laser direct patterning is a promising alternative to photolithography in the panel manufacturing of thin-film transistors for liquid crystal displays. - Highlights: ► KrF laser ablation technology is used to remove silicon nitride. ► A simple method for direct patterning contact-hole in thin-film-transistor device. ► Laser technology reduced processing by at least three steps

  11. Safe teleoperation based on flexible intraoperative planning for robot-assisted laser microsurgery.

    Science.gov (United States)

    Mattos, Leonardo S; Caldwell, Darwin G

    2012-01-01

    This paper describes a new intraoperative planning system created to improve precision and safety in teleoperated laser microsurgeries. It addresses major safety issues related to real-time control of a surgical laser during teleoperated procedures, which are related to the reliability and robustness of the telecommunication channels. Here, a safe solution is presented, consisting in a new planning system architecture that maintains the flexibility and benefits of real-time teleoperation and keeps the surgeon in control of all surgical actions. The developed system is based on our virtual scalpel system for robot-assisted laser microsurgery, and allows the intuitive use of stylus to create surgical plans directly over live video of the surgical field. In this case, surgical plans are defined as graphic objects overlaid on the live video, which can be easily modified or replaced as needed, and which are transmitted to the main surgical system controller for subsequent safe execution. In the process of improving safety, this new planning system also resulted in improved laser aiming precision and improved capability for higher quality laser procedures, both due to the new surgical plan execution module, which allows very fast and precise laser aiming control. Experimental results presented herein show that, in addition to the safety improvements, the new planning system resulted in a 48% improvement in laser aiming precision when compared to the previous virtual scalpel system.

  12. Review on recent Developments on Fabrication Techniques of Distributed Feedback (DFB) Based Organic Lasers

    Science.gov (United States)

    Azrina Talik, Noor; Boon Kar, Yap; Noradhlia Mohamad Tukijan, Siti; Wong, Chuan Ling

    2017-10-01

    To date, the state of art organic semiconductor distributed feedback (DFB) lasers gains tremendous interest in the organic device industry. This paper presents a short reviews on the fabrication techniques of DFB based laser by focusing on the fabrication method of DFB corrugated structure and the deposition of organic gain on the nano-patterned DFB resonator. The fabrication techniques such as Laser Direct Writing (LDW), ultrafast photo excitation dynamics, Laser Interference Lithography (LIL) and Nanoimprint Lithography (NIL) for DFB patterning are presented. In addition to that, the method for gain medium deposition method is also discussed. The technical procedures of the stated fabrication techniques are summarized together with their benefits and comparisons to the traditional fabrication techniques.

  13. Calibration-free absolute frequency response measurement of directly modulated lasers based on additional modulation.

    Science.gov (United States)

    Zhang, Shangjian; Zou, Xinhai; Wang, Heng; Zhang, Yali; Lu, Rongguo; Liu, Yong

    2015-10-15

    A calibration-free electrical method is proposed for measuring the absolute frequency response of directly modulated semiconductor lasers based on additional modulation. The method achieves the electrical domain measurement of the modulation index of directly modulated lasers without the need for correcting the responsivity fluctuation in the photodetection. Moreover, it doubles measuring frequency range by setting a specific frequency relationship between the direct and additional modulation. Both the absolute and relative frequency response of semiconductor lasers are experimentally measured from the electrical spectrum of the twice-modulated optical signal, and the measured results are compared to those obtained with conventional methods to check the consistency. The proposed method provides calibration-free and accurate measurement for high-speed semiconductor lasers with high-resolution electrical spectrum analysis.

  14. A New Remote Monitoring System Application in Laser Power Based on LabVIEW

    Directory of Open Access Journals (Sweden)

    Liu Gaoqiang

    2016-01-01

    Full Text Available In this paper, a new remote monitoring system based on LabVIEW was proposed to measure laser power automatically and remotely. This system consists of four basic components: an DH-JG2 optical power meter, a NI-USB 6008 data acquisition card, a personal computer (PC, and HP laserJet 1020 Plus printer. Since power output of laser is generally so unstable that abnormal work situation could not retroaction to inspectors right away, new system was designed to solve this problem. The detection system realized function of remote control by TCP protocol and mobile phone. Laser power curve that is measured by detection system demonstrated that the design has a good performance in real-time detection and operability.

  15. Characteristics of Ni-based coating layer formed by laser and plasma cladding processes

    International Nuclear Information System (INIS)

    Xu Guojian; Kutsuna, Muneharu; Liu Zhongjie; Zhang Hong

    2006-01-01

    The clad layers of Ni-based alloy were deposited on the SUS316L stainless plates by CO 2 laser and plasma cladding processes. The smooth clad bead was obtained by CO 2 laser cladding process. The phases of clad layer were investigated by an optical microscope, scanning electron microscopy (SEM), X-ray diffractometer (XRD), electron probe microanalysis (EPMA) and energy-dispersive spectrometer (EDS). The microstructures of clad layers belonged to a hypereutectic structure. Primary phases consist of boride CrB and carbide Cr 7 C 3 . The eutectic structure consists of Ni + CrB or Ni + Cr 7 C 3 . Compared with the plasma cladding, the fine microstructures, low dilutions, high Vickers hardness and excellent wear resistance were obtained by CO 2 laser cladding. All that show the laser cladding process has a higher efficiency and good cladding quality

  16. Fiber-Type Random Laser Based on a Cylindrical Waveguide with a Disordered Cladding Layer.

    Science.gov (United States)

    Zhang, Wei Li; Zheng, Meng Ya; Ma, Rui; Gong, Chao Yang; Yang, Zhao Ji; Peng, Gang Ding; Rao, Yun Jiang

    2016-05-25

    This letter reports a fiber-type random laser (RL) which is made from a capillary coated with a disordered layer at its internal surface and filled with a gain (laser dye) solution in the core region. This fiber-type optical structure, with the disordered layer providing randomly scattered light into the gain region and the cylindrical waveguide providing confinement of light, assists the formation of random lasing modes and enables a flexible and efficient way of making random lasers. We found that the RL is sensitive to laser dye concentration in the core region and there exists a fine exponential relationship between the lasing intensity and particle concentration in the gain solution. The proposed structure could be a fine platform of realizing random lasing and random lasing based sensing.

  17. Diode-pumped two-frequency lasers based on c-cut vanadate crystals

    International Nuclear Information System (INIS)

    Sirotkin, A A; Garnov, Sergei V; Zagumennyi, A I; Zavartsev, Yu D; Kutovoi, S A; Vlasov, V I; Shcherbakov, Ivan A

    2009-01-01

    The luminescent and lasing properties of the neo-dymium ion at the 4 F 3/2 - 4 I 11/2 transition in c-cut vanadate crystals (Nd:YVO 4 , Nd:GdVO 4 , and Nd:Gd 1-x Y x VO 4 ) are studied. Tuning of the laser radiation wavelength (Δλ = 5.4 nm) is demonstrated. Two-frequency laser schemes with the use of a Lyot filter, a Fabry-Perot etalon, and a Brewster prism as spectral selection elements are proposed and experimentally realised. Stable two-frequency lasing of a laser based on the c-cut Nd:GdVO 4 crystal was obtained in the cw, Q-switched (nanosecond pulses), and active acousto-optic mode-locked (picosecond pulses) regimes. (lasers)

  18. Theoretical study and simulation for a nanometer laser based on Gauss–Hermite source expansion

    International Nuclear Information System (INIS)

    Gu, Xiaowei

    2013-01-01

    Recently there has been worldwide interest in constructing a new generation of continuously tunable nanometer lasers for a wide range of scientific applications, including femtosecond science, biological molecules, nanoscience research fields, etc. The high brightness electron beam required by a short wavelength self-amplified spontaneous emission FEL can be reached only with accurate control of the beam dynamics in the facility. Numerical simulation codes are basic tools for designing new nanometer laser devices. We have developed a MATLAB quasi-one-dimensional code based on a reduced model for the FEL. The model uses an envelope description of the transverse dynamics of the laser beam and full longitudinal particle motion. We have optimized the LCLS facility parameters, then given the characteristics of the nanometer laser. (letter)

  19. Theoretical study and simulation for a nanometer laser based on Gauss-Hermite source expansion

    Science.gov (United States)

    Gu, Xiaowei

    2013-07-01

    Recently there has been worldwide interest in constructing a new generation of continuously tunable nanometer lasers for a wide range of scientific applications, including femtosecond science, biological molecules, nanoscience research fields, etc. The high brightness electron beam required by a short wavelength self-amplified spontaneous emission FEL can be reached only with accurate control of the beam dynamics in the facility. Numerical simulation codes are basic tools for designing new nanometer laser devices. We have developed a MATLAB quasi-one-dimensional code based on a reduced model for the FEL. The model uses an envelope description of the transverse dynamics of the laser beam and full longitudinal particle motion. We have optimized the LCLS facility parameters, then given the characteristics of the nanometer laser.

  20. A study on laser-based ultrasonic technique by the use of guided wave tomographic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junpil, E-mail: jpp@pusan.ac.kr; Lim, Juyoung, E-mail: jpp@pusan.ac.kr [Graduate school, School of Mechanical Engineering, Pusan National University (Korea, Republic of); Cho, Younho [School of Mechanical Engineering, Pusan National University (Korea, Republic of); Krishnaswamy, Sridhar [Center for Quality Engineering and Failure Prevention, Northwestern University, Evanston, IL (United States)

    2015-03-31

    Guided wave tests are impractical for investigating specimens with limited accessibility and coarse surfaces or geometrically complicated features. A non-contact setup with a laser ultrasonic transmitter and receiver is the classic attractive for guided wave inspection. The present work was done to develop a non-contact guided-wave tomography technique by laser ultrasonic technique in a plate-like structure. A method for Lam wave generation and detection in an aluminum plate with a pulse laser ultrasonic transmitter and a Michelson interferometer receiver has been developed. In the images obtained by laser scanning, the defect shape and area showed good agreement with the actual defect. The proposed approach can be used as a non-contact-based online inspection and monitoring technique.

  1. A laser-based beam profile monitor for the SLC/SLD interaction region

    International Nuclear Information System (INIS)

    Alley, R.; Arnett, D.; Bong, E.; Colocho, W.; Frisch, J.; Horton-Smith, S.; Inman, W.; Jobe, K.; Kotseroglou, T.; McCormick, D.; Nelson, J.; Scheeff, M.; Wagner, S.; Ross, M.C.

    1996-01-01

    Beam size estimates made using beam-beam deflections are used for optimization of the Stanford linear collider (SLC) electron-positron beam sizes. Typical beam sizes and intensities expected for 1996 operations are 2.1 x 0.6 μm (x, y) at 4.0.10 10 particles per pulse. Conventional profile monitors, such as scanning wires, fail at charge densities well below this. The laser-based profile monitor uses a finely-focused 350-nm wavelength tripled YLF laser pulse that traverses the particle beam path about 29 cm away from the e + /e - IP. Compton scattered photons and degraded e + /e - are detected as the beam is steered across the laser pulse. The laser pulse has a transverse size of 380 nm and a Rayleigh range of about 5 μm. (orig.)

  2. Indirect measurement of molten steel level in tundish based on laser triangulation

    Energy Technology Data Exchange (ETDEWEB)

    Su, Zhiqi; He, Qing, E-mail: heqing@ise.neu.edu.cn; Xie, Zhi [State Key Laboratory of Synthetical Automation for Process Industries, School of Information Science and Engineering, Northeastern University, Shenyang 110819 (China)

    2016-03-15

    For real-time and precise measurement of molten steel level in tundish during continuous casting, slag level and slag thickness are needed. Among which, the problem of slag thickness measurement has been solved in our previous work. In this paper, a systematic solution for slag level measurement based on laser triangulation is proposed. Being different from traditional laser triangulation, several aspects for measuring precision and robustness have been done. First, laser line is adopted for multi-position measurement to overcome the deficiency of single point laser range finder caused by the uneven surface of the slag. Second, the key parameters, such as installing angle and minimum requirement of the laser power, are analyzed and determined based on the gray-body radiation theory to fulfill the rigorous requirement of measurement accuracy. Third, two kinds of severe noises in the acquired images, which are, respectively, caused by heat radiation and Electro-Magnetic Interference (EMI), are cleaned via morphological characteristic of the liquid slag and color difference between EMI and the laser signals, respectively. Fourth, as false target created by stationary slag usually disorders the measurement, valid signals of the slag are distinguished from the false ones to calculate the slag level. Then, molten steel level is obtained by the slag level minus the slag thickness. The measuring error of this solution is verified by the applications in steel plants, which is ±2.5 mm during steady casting and ±3.2 mm at the end of casting.

  3. Indirect measurement of molten steel level in tundish based on laser triangulation

    Science.gov (United States)

    Su, Zhiqi; He, Qing; Xie, Zhi

    2016-03-01

    For real-time and precise measurement of molten steel level in tundish during continuous casting, slag level and slag thickness are needed. Among which, the problem of slag thickness measurement has been solved in our previous work. In this paper, a systematic solution for slag level measurement based on laser triangulation is proposed. Being different from traditional laser triangulation, several aspects for measuring precision and robustness have been done. First, laser line is adopted for multi-position measurement to overcome the deficiency of single point laser range finder caused by the uneven surface of the slag. Second, the key parameters, such as installing angle and minimum requirement of the laser power, are analyzed and determined based on the gray-body radiation theory to fulfill the rigorous requirement of measurement accuracy. Third, two kinds of severe noises in the acquired images, which are, respectively, caused by heat radiation and Electro-Magnetic Interference (EMI), are cleaned via morphological characteristic of the liquid slag and color difference between EMI and the laser signals, respectively. Fourth, as false target created by stationary slag usually disorders the measurement, valid signals of the slag are distinguished from the false ones to calculate the slag level. Then, molten steel level is obtained by the slag level minus the slag thickness. The measuring error of this solution is verified by the applications in steel plants, which is ±2.5 mm during steady casting and ±3.2 mm at the end of casting.

  4. A laser-based technology for fabricating a soda-lime glass based microfluidic device for circulating tumour cell capture.

    Science.gov (United States)

    Nieto, Daniel; Couceiro, Ramiro; Aymerich, Maria; Lopez-Lopez, Rafael; Abal, Miguel; Flores-Arias, María Teresa

    2015-10-01

    We developed a laser-based technique for fabricating microfluidic microchips on soda-lime glass substrates. The proposed methodology combines a laser direct writing, as a manufacturing tool for the fabrication of the microfluidics structures, followed by a post-thermal treatment with a CO2 laser. This treatment will allow reshaping and improving the morphological (roughness) and optical qualities (transparency) of the generated microfluidics structures. The use of lasers commonly implemented for material processing makes this technique highly competitive when compared with other glass microstructuring approaches. The manufactured chips were tested with tumour cells (Hec 1A) after being functionalized with an epithelial cell adhesion molecule (EpCAM) antibody coating. Cells were successfully arrested on the pillars after being flown through the device giving our technology a translational application in the field of cancer research. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Generation of 3D Virtual Geographic Environment Based on Laser Scanning Technique

    Institute of Scientific and Technical Information of China (English)

    DU Jie; CHEN Xiaoyong; FumioYamazaki

    2003-01-01

    This paper demonstrates an experiment on the generation of 3D virtual geographic environment on the basis of experimental flight laser scanning data by a set of algorithms and methods that were developed to automatically interpret range images for extracting geo-spatial features and then to reconstruct geo-objects. The algorithms and methods for the interpretation and modeling of laser scanner data include triangulated-irregular-network (TIN)-based range image interpolation ; mathematical-morphology(MM)-based range image filtering,feature extraction and range image segmentation, feature generalization and optimization, 3D objects reconstruction and modeling; computergraphics (CG)-based visualization and animation of geographic virtual reality environment.

  6. Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO{sub 2} laser

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Teaghee; Choi, Jong Woon [Department of Information and Communication, Honam University, Seobong-dong 59-1, Gwansan-gu, Gwangju 506-714 (Korea, Republic of); Kim, Yong Pyung [College of Electronics and Information, Kyunghee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

    2012-09-15

    We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO{sub 2} laser. A portion of a Doppler-shifted laser beam, produced by irradiating a single wavelength laser beam on a moving object, is mixed with an originally existing laser beam inside a laser cavity. The fine change of pressure in the laser cavity modulated by the Doppler-shifted frequency is detected by a condenser microphone in the laser tube. In our studies, the frequency of the Doppler signal due to the optoacoustic effect was detected as high as 50 kHz. Our measurements also confirmed that the signal varied linearly with the velocity of the external scatterer (the moving object) and the cosine of the angle between the laser beam and the velocity vector of the object.

  7. Speckle perception and disturbance limit in laser based projectors

    Science.gov (United States)

    Verschaffelt, Guy; Roelandt, Stijn; Meuret, Youri; Van den Broeck, Wendy; Kilpi, Katriina; Lievens, Bram; Jacobs, An; Janssens, Peter; Thienpont, Hugo

    2016-04-01

    We investigate the level of speckle that can be tolerated in a laser cinema projector. For this purpose, we equipped a movie theatre room with a prototype laser projector. A group of 186 participants was gathered to evaluate the speckle perception of several, short movie trailers in a subjective `Quality of Experience' experiment. This study is important as the introduction of lasers in projection systems has been hampered by the presence of speckle in projected images. We identify a speckle disturbance threshold by statistically analyzing the observers' responses for different values of the amount of speckle, which was monitored using a well-defined speckle measurement method. The analysis shows that the speckle perception of a human observer is not only dependent on the objectively measured amount of speckle, but it is also strongly influenced by the image content. As is also discussed in [Verschaffelt et al., Scientific Reports 5, art. nr. 14105, 2015] we find that, for moving images, the speckle becomes disturbing if the speckle contrast becomes larger than 6.9% for the red, 6.0% for the green, and 4.8% for the blue primary colors of the projector, whereas for still images the speckle detection threshold is about 3%. As we could not independently tune the speckle contrast of each of the primary colors, this speckle disturbance limit seems to be determined by the 6.9% speckle contrast of the red color as this primary color contains the largest amount of speckle. The speckle disturbance limit for movies thus turns out to be substantially larger than that for still images, and hence is easier to attain.

  8. A laser-based eye-tracking system.

    Science.gov (United States)

    Irie, Kenji; Wilson, Bruce A; Jones, Richard D; Bones, Philip J; Anderson, Tim J

    2002-11-01

    This paper reports on the development of a new eye-tracking system for noninvasive recording of eye movements. The eye tracker uses a flying-spot laser to selectively image landmarks on the eye and, subsequently, measure horizontal, vertical, and torsional eye movements. Considerable work was required to overcome the adverse effects of specular reflection of the flying-spot from the surface of the eye onto the sensing elements of the eye tracker. These effects have been largely overcome, and the eye-tracker has been used to document eye movement abnormalities, such as abnormal torsional pulsion of saccades, in the clinical setting.

  9. Two-phase flow measurement based on oblique laser scattering

    Science.gov (United States)

    Vendruscolo, Tiago P.; Fischer, Robert; Martelli, Cícero; Rodrigues, Rômulo L. P.; Morales, Rigoberto E. M.; da Silva, Marco J.

    2015-07-01

    Multiphase flow measurements play a crucial role in monitoring productions processes in many industries. To guarantee the safety of processes involving multiphase flows, it is important to detect changes in the flow conditions before they can cause damage, often in fractions of seconds. Here we demonstrate how the scattering pattern of a laser beam passing a two-phase flow under an oblique angle to the flow direction can be used to detect derivations from the desired flow conditions in microseconds. Applying machine-learning techniques to signals obtained from three photo-detectors we achieve a compact, versatile, low-cost sensor design for safety applications.

  10. Laser power meter based on the Peltier effect

    International Nuclear Information System (INIS)

    Goldschmid, H.J.; Miller, L.A.; Paul, G.L.

    1984-01-01

    An isothermal power meter, in which the incoming radiation is balanced by thermoelectric cooling, has two substantial advantages: there are no heat losses to the surroundings, and a short response time should result from the smallness of the temperature excursions before balance is achieved. Experiments on prototype devices consisting of thermoelectric modules, made from bismuth telluride alloys, with nominally black-body receivers are reported. Laser powers in the range 100 to 550 mW were measured. In the most favoured arrangement, multijunction modules were used both to provide cooling through the Peltier effect and to detect any temperature excursions through the Seebeck effect. The results justify further work on the system

  11. Surface modification by EUV laser beam based on capillary discharge

    Czech Academy of Sciences Publication Activity Database

    Frolov, Oleksandr; Koláček, Karel; Schmidt, Jiří; Štraus, Jaroslav; Prukner, Václav; Shukurov, A.

    -, č. 58 (2011), s. 484-487 ISSN 2010-376X. [International Conference on Fusion and Plasma Physics. Bali, Indonésie, 26.10.2011-28.10.2011] R&D Projects: GA AV ČR KAN300100702; GA MŠk LA08024; GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z20430508 Keywords : soft x-ray * EUV * laser * radiation * source * capillary * discharge * plasma * ablation * surface modification Subject RIV: BL - Plasma and Gas Discharge Physics http://www.waset.org/journals/waset/v58/v58-99.pdf

  12. Quality Assessment and Comparison of Smartphone and Leica C10 Laser Scanner Based Point Clouds

    Science.gov (United States)

    Sirmacek, Beril; Lindenbergh, Roderik; Wang, Jinhu

    2016-06-01

    3D urban models are valuable for urban map generation, environment monitoring, safety planning and educational purposes. For 3D measurement of urban structures, generally airborne laser scanning sensors or multi-view satellite images are used as a data source. However, close-range sensors (such as terrestrial laser scanners) and low cost cameras (which can generate point clouds based on photogrammetry) can provide denser sampling of 3D surface geometry. Unfortunately, terrestrial laser scanning sensors are expensive and trained persons are needed to use them for point cloud acquisition. A potential effective 3D modelling can be generated based on a low cost smartphone sensor. Herein, we show examples of using smartphone camera images to generate 3D models of urban structures. We compare a smartphone based 3D model of an example structure with a terrestrial laser scanning point cloud of the structure. This comparison gives us opportunity to discuss the differences in terms of geometrical correctness, as well as the advantages, disadvantages and limitations in data acquisition and processing. We also discuss how smartphone based point clouds can help to solve further problems with 3D urban model generation in a practical way. We show that terrestrial laser scanning point clouds which do not have color information can be colored using smartphones. The experiments, discussions and scientific findings might be insightful for the future studies in fast, easy and low-cost 3D urban model generation field.

  13. QUALITY ASSESSMENT AND COMPARISON OF SMARTPHONE AND LEICA C10 LASER SCANNER BASED POINT CLOUDS

    Directory of Open Access Journals (Sweden)

    B. Sirmacek

    2016-06-01

    Full Text Available 3D urban models are valuable for urban map generation, environment monitoring, safety planning and educational purposes. For 3D measurement of urban structures, generally airborne laser scanning sensors or multi-view satellite images are used as a data source. However, close-range sensors (such as terrestrial laser scanners and low cost cameras (which can generate point clouds based on photogrammetry can provide denser sampling of 3D surface geometry. Unfortunately, terrestrial laser scanning sensors are expensive and trained persons are needed to use them for point cloud acquisition. A potential effective 3D modelling can be generated based on a low cost smartphone sensor. Herein, we show examples of using smartphone camera images to generate 3D models of urban structures. We compare a smartphone based 3D model of an example structure with a terrestrial laser scanning point cloud of the structure. This comparison gives us opportunity to discuss the differences in terms of geometrical correctness, as well as the advantages, disadvantages and limitations in data acquisition and processing. We also discuss how smartphone based point clouds can help to solve further problems with 3D urban model generation in a practical way. We show that terrestrial laser scanning point clouds which do not have color information can be colored using smartphones. The experiments, discussions and scientific findings might be insightful for the future studies in fast, easy and low-cost 3D urban model generation field.

  14. New Mid-IR Lasers Based on Rare-Earth-Doped Sulfide and Chloride Materials

    International Nuclear Information System (INIS)

    Nostrand, M

    2000-01-01

    Applications in remote-sensing and military countermeasures have driven a need for compact, solid-state mid-IR lasers. Due to multi-phonon quenching, non-traditional hosts are needed to extend current solid-state, room-temperature lasing capabilities beyond ∼ 4 (micro)m. Traditional oxide and fluoride hosts have effective phonon energies in the neighborhood of 1000 cm -1 and 500 cm -1 , respectively. These phonons can effectively quench radiation above 2 and 4 (micro)m, respectively. Materials with lower effective phonon energies such as sulfides and chlorides are the logical candidates for mid-IR (4-10 (micro)m) operation. In this report, laser action is demonstrated in two such hosts, CaGa 2 S 4 and KPb 2 Cl 5 . The CaGa 2 S 4 :Dy 3+ laser operating at 4.3 (micro)m represents the first sulfide laser operating beyond 2 (micro)m. The KPb 2 Cl 5 :Dy 3+ laser operating at 2.4 (micro)m represents the first operation of a chloride-host laser in ambient conditions. Laser action is also reported for CaGa 2 S 4 :Dy 3+ at 2.4 (micro)m, CaGa 2 S 4 :Dy 3+ at 1.4 (micro)m, and KPb 2 Cl 5 :Nd 3+ at 1.06 (micro)m. Both host materials have been fully characterized, including lifetimes, absorption and emission cross sections, radiative branching ratios, and radiative quantum efficiencies. Radiative branching ratios and radiative quantum efficiencies have been determined both by the Judd-Ofelt method (which is based on absorption measurements), and by a novel method described herein which is based on emission measurements. Modeling has been performed to predict laser performance, and a new method to determine emission cross section from slope efficiency and threshold data is developed. With the introduction and laser demonstration of rare-earth-doped CaGa 2 S 4 and KPb 2 Cl 5 , direct generation of mid-IR laser radiation in a solid-state host has been demonstrated. In KPb 2 Cl 5 , predictions indicate that laser operation to 9 (micro)m may be possible, a wavelength previously

  15. Quantum cascade laser-based photoacoustic sulfuryl fluoride sensing

    Science.gov (United States)

    Minini, Kariza Mayra Silva; Bueno, Sâmylla Cristina Espécie; da Silva, Marcelo Gomes; Sthel, Marcelo Silva; Vargas, Helion; Angster, Judit; Miklós, András

    2017-02-01

    Although sulfuryl fluoride (SO2F2) is an efficient fumigant that does not react with the surface of indoor materials and does not reduce the stratospheric ozone shield, there are some concerns about its use. It is a toxic gas that attacks the central nervous system, and its global warming potential (GWP) value is 4780 for 100 years' time. Therefore, it is a clear necessity of implementing detection methods for tracing such a molecule. In this work a sensitive photoacoustic setup was built to detect SO2F2 at concentrations of parts per billion by volume (ppbv). The symmetric S-O stretching mode was excited by a continuous-wave quantum cascade laser with radiation wavenumber ranging from 1275.7 to 1269.3 cm-1. The photoacoustic signal was generated by modulating the laser wavenumber at the first longitudinal mode of the photoacoustic cell with amplitude depth of 5 × 10-3 cm-1. The detection of a minimum SO2F2 concentration of 20 ppbv was achieved.

  16. Topographic Correction of GPR Profiles Based on Laser Data

    International Nuclear Information System (INIS)

    Zhang, Di; Zhong, Ruofei; Li, Jia Cun; Zeng, Fanyang

    2014-01-01

    Data obtained by GPR (Ground Penetrating Radar) are displayed as a continuous cross-sectional profile. Surface, generally, is not flat. As a result, the image becomes distorted and the depth calculated from the surface no longer represents the true and exact position of electrically distinctive layers and objects in materials. In order to get real geologic cross section, GPR data must be corrected. This is paper discusses a new method using the color point cloud data obtained by a Vehicle-borne laser scanning system to compensate for elevation fluctuate. Elevation profile can be extracted from topographic data of survey site acquired using laser scanner, which can then be used to offset the error of GPR data. Through the discrete points in the survey line, each trace of the profile has its own elevation value showing a vertical difference from the reference profile with maximum elevation, then time shifts value of traces vertical offset versus the reference trace of profile can be obtained. At last, the results of topographic correction for radargrams that look extremely like the real geologic cross section are presented, which allows us to get a better profile interpretation and position of the objects and layers in the subsurface

  17. CO2 Laser-Based Rapid Prototyping of Micropumps

    Directory of Open Access Journals (Sweden)

    Zachary Strike

    2018-05-01

    Full Text Available The fabrication of microdevices for fluidic control often requires the use of flexible diaphragms in a way that requires cleanroom equipment and compromises performance. We use a CO 2 laser to perform the standard ablative techniques of cutting and engraving materials, but we also apply a method that we call laser placement. This allows us to fabricate precisely-positioned and precisely-sized, isolated diaphragms. This in turn enables the rapid prototyping of integrated multilayer microfluidic devices to form complex structures without the need for manual positioning or cleanroom equipment. The fabrication process is also remarkably rapid and capable of being scaled to manufacturing levels of production. We explore the use of these devices to construct a compact system of peristaltic pumps that can form water in oil droplets without the use of the non-pulsatile pumping systems typically required. Many devices can be fabricated at a time on a sheet by sheet basis with a fabrication process that, to our knowledge, is the fastest reported to date for devices of this type (requiring only 3 h. Moreover, this system is unusually compact and self-contained.

  18. Laser backlight unit based on a leaky optical fiber

    Science.gov (United States)

    Okuda, Yuuto; Onoda, Kousuke; Fujieda, Ichiro

    2012-07-01

    A backlight unit is constructed by laying out an optical fiber on a two-dimensional plane and letting the light leak out in a controlled manner. In experiment, we formed multiple grooves on the surface of a plastic optical fiber by pressing a heated knife edge. The depth of the groove determined the percentage of the optical power leaking out. The optical fiber with multiple grooves was embedded in an acrylic plate with a spiral trench, and a diffuser sheet was placed over it. When we injected laser light into the end of the optical fiber, this configuration successfully worked as an area illuminator. However, the coherent nature of the laser light caused severe speckle noise. We evaluated the speckle contrast under darkness, and it varied from 80% to 23%, depending on the lens aperture used to capture the images of the illuminator. We glued an ultrasound generator to the optical fiber to introduce phase modulation for the light propagating inside the optical fiber. In this way, the speckle contrast was reduced by a factor of seven to four. Under room lighting, the speckle noise was made barely noticeable by turning on the ultrasound generator.

  19. Laser created thin films sensors based on Sn- and indium compounds

    Czech Academy of Sciences Publication Activity Database

    Myslík, V.; Vysloužil, F.; Vrňata, M.; Fryček, R.; Jelínek, Miroslav; Lančok, Ján

    2002-01-01

    Roč. 12, č. 2 (2002), s. 329-333 ISSN 1054-660X Institutional research plan: CEZ:AV0Z1010921 Keywords : PLD * Sn-based thin films * In-based thin films Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.798, year: 2002

  20. Training the Masses ? Web-based Laser Safety Training at LLNL

    Energy Technology Data Exchange (ETDEWEB)

    Sprague, D D

    2004-12-17

    The LLNL work smart standard requires us to provide ongoing laser safety training for a large number of persons on a three-year cycle. In order to meet the standard, it was necessary to find a cost and performance effective method to perform this training. This paper discusses the scope of the training problem, specific LLNL training needs, various training methods used at LLNL, the advantages and disadvantages of these methods and the rationale for selecting web-based laser safety training. The tools and costs involved in developing web-based training courses are also discussed, in addition to conclusions drawn from our training operating experience. The ILSC lecture presentation contains a short demonstration of the LLNL web-based laser safety-training course.

  1. Dispersive heterodyne probing method for laser frequency stabilization based on spectral hole burning in rare-earth doped crystals

    DEFF Research Database (Denmark)

    Gobron, Olivier; Jung, K.; Galland, N.

    2017-01-01

    Frequency-locking a laser to a spectral hole in rare-earth doped crystals at cryogenic temperature has been shown to be a promising alternative to the use of high finesse Fabry-Perot cavities when seeking a very high short term stability laser (M. J. Thorpe et al., Nature Photonics 5, 688 (2011......)). We demonstrate here a novel technique for achieving such stabilization, based on generating a heterodyne beat-note between a master laser and a slave laser whose dephasing caused by propagation near a spectral hole generate the error signal of the frequency lock. The master laser is far detuned from...

  2. High-brightness electron beam evolution following laser-based cleaning of a photocathode

    Directory of Open Access Journals (Sweden)

    F. Zhou

    2012-09-01

    Full Text Available Laser-based techniques have been widely used for cleaning metal photocathodes to increase quantum efficiency (QE. However, the impact of laser cleaning on cathode uniformity and thereby on electron beam quality are less understood. We are evaluating whether this technique can be applied to revive photocathodes used for high-brightness electron sources in advanced x-ray free-electron laser (FEL facilities, such as the Linac Coherent Light Source (LCLS at the SLAC National Accelerator Laboratory. The laser-based cleaning was applied to two separate areas of the current LCLS photocathode on July 4 and July 26, 2011, respectively. The QE was increased by 8–10 times upon the laser cleaning. Since the cleaning, routine operation has exhibited a slow evolution of the QE improvement and comparatively rapid improvement of transverse emittance, with a factor of 3 QE enhancement over five months, and a significant emittance improvement over the initial 2–3 weeks following the cleaning. Currently, the QE of the LCLS photocathode is holding constant at about 1.2×10^{-4}, with a normalized injector emittance of about 0.3  μm for a 150-pC bunch charge. With the proper procedures, the laser-cleaning technique appears to be a viable tool to revive the LCLS photocathode. We present observations and analyses for the QE and emittance evolution in time following the laser-based cleaning of the LCLS photocathode, and comparison to the previous studies, the measured thermal emittance versus the QE and comparison to the theoretical model.

  3. High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

    Science.gov (United States)

    Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Gironi, Gianna; Suetta, Enrico

    2017-11-01

    This paper describes energetic, spatial, temporal and spectral characterization measurements of the Engineering Qualification Model (EQM) of the Laser Transmitter Assembly (TXA) used in the ALADIN instrument currently under development for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The EQM is equivalent to the Flight Model, with the exception of some engineering grade components. The Laser Transmitter Assembly, based on a diode pumped tripled Nd:YAG laser, is used to generate laser pulses at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz during bursts. It is capable to operate in Single Longitudinal Mode and to be tuned over 25 GHz range. An internal "network" of sensors has been implemented inside the laser architecture to allow "in flight" monitoring of transmitter. Energy in excess of 100 mJ, with a spatial beam quality factor (M2) lower than 3, a spectral linewidth less than 50 MHz with a frequency stability better than 4 MHz on short term period have been measured on the EQM. Most of the obtained results are well within the expected values and match the Instrument requirements. They constitute an important achievement, showing the absence of major critical areas in terms of performance and the capability to obtain them in a rugged and compact structure suitable for space applications. The EQM will be submitted in the near future to an Environmental test campaign.

  4. All-fiber radially/azimuthally polarized lasers based on mode coupling of tapered fibers.

    Science.gov (United States)

    Mao, Dong; He, Zhiwen; Lu, Hua; Li, Mingkun; Zhang, Wending; Cui, Xiaoqi; Jiang, Biqiang; Zhao, Jianlin

    2018-04-01

    We demonstrate a mode converter with an insertion loss of 0.36 dB based on mode coupling of tapered single-mode and two-mode fibers, and realize all-fiber flexible cylindrical vector lasers at 1550 nm. Attributing to the continuous distribution of a tangential electric field at taper boundaries, the laser is switchable between the radially and azimuthally polarized states by adjusting the input polarization. In the temporal domain, the operation is controllable among continuous-wave, Q-switched, and mode-locked statuses by changing the saturable absorber or pump strength. The duration of Q-switched radially/azimuthally polarized laser spans from 10.4/10.8 to 6/6.4 μs at the pump range of 38 to 58 mW, while that of the mode-locked pulse varies from 39.2/31.9 to 5.6/5.2 ps by controlling the laser bandwidth. The proposed laser combines the features of a cylindrical vector beam, a fiber laser, and an ultrafast pulse, providing a special and cost-effective source for practical applications.

  5. 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.

  6. Femtosecond laser-induced concentric ring microstructures on Zr-based metallic glass

    International Nuclear Information System (INIS)

    Ma Fengxu; Yang Jianjun; Xiaonong Zhu; Liang Chunyong; Wang Hongshui

    2010-01-01

    Surface morphological evolution of Zr-based metallic glass ablated by femtosecond lasers is investigated in atmosphere condition. Three types of permanent ring structures with micro-level spacing are observed for different laser shots and fluences. In the case of low laser fluences, the generation of annular patterns with nonthermal features is observed on the rippled structure with the subwavelength scale, and the ring spacing shows a decrease tendency from the center to the margin. While in the case of high laser fluences, the concentric rings formation within the laser spot is found to have evident molten traces and display the increasing ring spacing along the radial direction. Moreover, when the laser shots accumulation becomes large, the above two types of ring microstructures begin to develop into the common ablation craters. Analysis and discussion suggests that the stress-induced condensation of ablation vapors and the frozen thermocapillary waves on the molten surfaces should be responsible for the formation of two different types of concentric ring structures, respectively. Eventually, a processing window for each resulting surface microstructure type is obtained experimentally and indicates the possibility to control the morphological transitions among different types.

  7. A tesselation-based model for intensity estimation and laser plasma interactions calculations in three dimensions

    Science.gov (United States)

    Colaïtis, A.; Chapman, T.; Strozzi, D.; Divol, L.; Michel, P.

    2018-03-01

    A three-dimensional laser propagation model for computation of laser-plasma interactions is presented. It is focused on indirect drive geometries in inertial confinement fusion and formulated for use at large temporal and spatial scales. A modified tesselation-based estimator and a relaxation scheme are used to estimate the intensity distribution in plasma from geometrical optics rays. Comparisons with reference solutions show that this approach is well-suited to reproduce realistic 3D intensity field distributions of beams smoothed by phase plates. It is shown that the method requires a reduced number of rays compared to traditional rigid-scale intensity estimation. Using this field estimator, we have implemented laser refraction, inverse-bremsstrahlung absorption, and steady-state crossed-beam energy transfer with a linear kinetic model in the numerical code Vampire. Probe beam amplification and laser spot shapes are compared with experimental results and pf3d paraxial simulations. These results are promising for the efficient and accurate computation of laser intensity distributions in holhraums, which is of importance for determining the capsule implosion shape and risks of laser-plasma instabilities such as hot electron generation and backscatter in multi-beam configurations.

  8. A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

    Science.gov (United States)

    Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

    2015-10-01

    Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

  9. Quantitative analysis of chromium concentration in nickel based alloys by laser induced breakdown spectroscopy at atmospheric pressure using a nanosecond ultraviolet Nd:YAG laser

    International Nuclear Information System (INIS)

    Gupta, G.P.; Suri, B.M.; Verma, A.; Sundararaman, M.; Unnikrishnan, V.K.; Alti, K.; Kartha, V.B.; Santhosh, C.

    2010-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been well recognized as a simple, fast and direct analytical technique of elemental analysis of multi-element materials by a number of research groups all over the world. It is based on the focusing of a high-power pulsed laser beam with a power density > 100 MW/cm 2 onto a sample surface followed by optical emission spectroscopy of the plasma produced over the surface. In the present work, they have carried out the quantitative analysis of chromium in nickel-based-alloys using laser-induced breakdown spectroscopy (LIBS) in air at atmospheric pressure. In the present work the quantitative analysis of chromium in nickel-based-alloys using laser-induced break-down spectroscopy (LIBS) in air at atmospheric pressure has been carried out

  10. Single-frequency, fully integrated, miniature DPSS laser based on monolithic resonator

    Science.gov (United States)

    Dudzik, G.; Sotor, J.; Krzempek, K.; Soboń, G.; Abramski, K. M.

    2014-02-01

    We present a single frequency, stable, narrow linewidth, miniature laser sources operating at 532 nm (or 1064 nm) based on a monolithic resonators. Such resonators utilize birefringent filters formed by YVO4 beam displacer and KTP or YVO4 crystals to force single frequency operation at 532 nm or 1064 nm, respectively. In both configurations Nd:YVO4 gain crystal is used. The resonators dimensions are 1x1x10.5 mm3 and 1x1x8.5 mm3 for green and infrared configurations, respectively. Presented laser devices, with total dimensions of 40x52x120 mm3, are fully equipped with driving electronics, pump diode, optical and mechanical components. The highly integrated (36x15x65 mm3) low noise driving electronics with implemented digital PID controller was designed. It provides pump current and resonator temperature stability of ±30 μA@650 mA and ±0,003ºC, respectively. The laser parameters can be set and monitored via the USB interface by external application. The developed laser construction is universal. Hence, the other wavelengths can be obtained only by replacing the monolithic resonator. The optical output powers in single frequency regime was at the level of 42 mW@532 nm and 0.5 W@1064 nm with the long-term fluctuations of ±0.85 %. The linewidth and the passive frequency stability under the free running conditions were Δν < 100 kHz and 3ṡ10-9@1 s integration time, respectively. The total electrical power supply consumption of laser module was only 4 W. Presented compact, single frequency laser operating at 532 nm and 1064 nm may be used as an excellent source for laser vibrometry, interferometry or seed laser for fiber amplifiers.

  11. Laser-based sensor for a coolant leak detection in a nuclear reactor

    Science.gov (United States)

    Kim, T.-S.; Park, H.; Ko, K.; Lim, G.; Cha, Y.-H.; Han, J.; Jeong, D.-Y.

    2010-08-01

    Currently, the nuclear industry needs strongly a reliable detection system to continuously monitor a coolant leak during a normal operation of reactors for the ensurance of nuclear safety. In this work, we propose a new device for the coolant leak detection based on tunable diode laser spectroscopy (TDLS) by using a compact diode laser. For the feasibility experiment, we established an experimental setup consisted of a near-IR diode laser with a wavelength of about 1392 nm, a home-made multi-pass cell and a sample injection system. The feasibility test was performed for the detection of the heavy water (D2O) leaks which can happen in a pressurized heavy water reactor (PWHR). As a result, the device based on the TDLS is shown to be operated successfully in detecting a HDO molecule, which is generated from the leaked heavy water by an isotope exchange reaction between D2O and H2O. Additionally, it is suggested that the performance of the new device, such as sensitivity and stability, can be improved by adapting a cavity enhanced absorption spectroscopy and a compact DFB diode laser. We presume that this laser-based leak detector has several advantages over the conventional techniques currently employed in the nuclear power plant, such as radiation monitoring, humidity monitoring and FT-IR spectroscopy.

  12. Multi-kW single fiber laser based on an extra large mode area fiber design

    Science.gov (United States)

    Langner, Andreas; Such, Mario; Schötz, Gerhard; Just, Florian; Leich, Martin; Schwuchow, Anka; Grimm, Stephan; Zimer, Hagen; Kozak, Marcin; Wedel, Björn; Rehmann, Georg; Bachert, Charley; Krause, Volker

    2012-02-01

    The quality of Yb-doped fused bulk silica produced by sintering of Yb-doped fused silica granulates has improved greatly in the past five years [1 - 4]. In particular, the refractive index and doping level homogeneity of such materials are excellent and we achieved excellent background fiber attenuation of the active core material down to about 20 dB/km at 1200 nm. The improvement of the Yb-doped fused bulk silica has enabled the development of multi-kW fiber laser systems based on a single extra large multimode laser fiber (XLMA fiber). When a single active fiber is used in combination with the XLMA multimode fiber of 1200 μm diameter simple and robust high power fiber laser setups without complex fiber coupling and fiber combiner systems become possible. In this papper, we will discuss in detail the development of the core material based on Yb-doped bulk silica and the characterization of Yb-doped fibers with different core compositions. We will also report on the excellent performance of a 4 kW fiber laser based on a single XLMA-fiber and show the first experimental welding results of steel sheets achieved with such a laser.

  13. Metal monitoring for process control of laser-based coating removal

    Science.gov (United States)

    Fraser, Mark E.; Hunter, Amy J.; Panagiotou, Thomai; Davis, Steven J.; Freiwald, David A.

    1999-12-01

    Cost-effective and environmentally-sound means of paint and coatings removal is a problem spanning many government, commercial, industrial and municipal applications. For example, the Department of Energy is currently engaged in removing paint and other coatings from concrete and structural steel as part of decommissioning former nuclear processing facilities. Laser-based coatings removal is an attractive new technology for these applications as it promises to reduce the waste volume by up to 75 percent. To function more efficiently, however, the laser-based systems require some form of process control.

  14. Ultrafast, laser-based, x-ray science: the dawn of atomic-scale cinematography

    International Nuclear Information System (INIS)

    Barty, C.P.J.

    2000-01-01

    The characteristics of ultrafast chirped pulse amplification systems are reviewed. Application of ultrafast chirped pulse amplification to the generation of femtosecond, incoherent, 8-keV line radiation is outlined and the use of femtosecond laser-based, x-rays for novel time-resolved diffraction studies of crystalline dynamics with sub-picosecond temporal resolution and sub-picometer spatial resolution is reviewed in detail. Possible extensions of laser-based, x-ray technology and evaluation of alternative x-ray approaches for time-resolved studies of the atomic scale dynamics are given. (author)

  15. Stabilizing operation point technique based on the tunable distributed feedback laser for interferometric sensors

    Science.gov (United States)

    Mao, Xuefeng; Zhou, Xinlei; Yu, Qingxu

    2016-02-01

    We describe a stabilizing operation point technique based on the tunable Distributed Feedback (DFB) laser for quadrature demodulation of interferometric sensors. By introducing automatic lock quadrature point and wavelength periodically tuning compensation into an interferometric system, the operation point of interferometric system is stabilized when the system suffers various environmental perturbations. To demonstrate the feasibility of this stabilizing operation point technique, experiments have been performed using a tunable-DFB-laser as light source to interrogate an extrinsic Fabry-Perot interferometric vibration sensor and a diaphragm-based acoustic sensor. Experimental results show that good tracing of Q-point was effectively realized.

  16. A High Precision Laser-Based Autofocus Method Using Biased Image Plane for Microscopy

    Directory of Open Access Journals (Sweden)

    Chao-Chen Gu

    2018-01-01

    Full Text Available This study designs and accomplishes a high precision and robust laser-based autofocusing system, in which a biased image plane is applied. In accordance to the designed optics, a cluster-based circle fitting algorithm is proposed to calculate the radius of the detecting spot from the reflected laser beam as an essential factor to obtain the defocus value. The experiment conduct on the experiment device achieved novel performance of high precision and robustness. Furthermore, the low demand of assembly accuracy makes the proposed method a low-cost and realizable solution for autofocusing technique.

  17. A Low Cost 3D Acquiring System for Mushroom Robot Based on Webcam and Line Laser

    Directory of Open Access Journals (Sweden)

    Gang Sun

    2014-03-01

    Full Text Available This paper presents a low cost 3D acquiring system for mushroom robot based on webcam and line laser. The system comprises Webcam, semiconductor line laser, motion platform and data process unit. The system can get the 3D information of the Pleurotus eryngii in bottle based on structured light scanning theory. Field test shows the accuracy of the height is less than 2mm and it can be use to locate the buds in the bottle correctly. It has the potention to fulfill the requirement of the location of the mushroom for thinning bud robot.

  18. Status of advanced ground-based laser interferometers for gravitational-wave detection

    International Nuclear Information System (INIS)

    Dooley, K L; Akutsu, T; Dwyer, S; Puppo, P

    2015-01-01

    Ground-based laser interferometers for gravitational-wave (GW) detection were first constructed starting 20 years ago and as of 2010 collection of several years’ worth of science data at initial design sensitivities was completed. Upgrades to the initial detectors together with construction of brand new detectors are ongoing and feature advanced technologies to improve the sensitivity to GWs. This conference proceeding provides an overview of the common design features of ground-based laser interferometric GW detectors and establishes the context for the status updates of each of the four gravitational-wave detectors around the world: Advanced LIGO, Advanced Virgo, GEO 600 and KAGRA. (paper)

  19. Status of advanced ground-based laser interferometers for gravitational-wave detection

    Science.gov (United States)

    Dooley, K. L.; Akutsu, T.; Dwyer, S.; Puppo, P.

    2015-05-01

    Ground-based laser interferometers for gravitational-wave (GW) detection were first constructed starting 20 years ago and as of 2010 collection of several years’ worth of science data at initial design sensitivities was completed. Upgrades to the initial detectors together with construction of brand new detectors are ongoing and feature advanced technologies to improve the sensitivity to GWs. This conference proceeding provides an overview of the common design features of ground-based laser interferometric GW detectors and establishes the context for the status updates of each of the four gravitational-wave detectors around the world: Advanced LIGO, Advanced Virgo, GEO 600 and KAGRA.

  20. The laser calibration system for the STACEE ground-based gamma ray detector

    CERN Document Server

    Hanna, D

    2002-01-01

    We describe the design and performance of the laser system used for calibration monitoring of components of the STACEE detector. STACEE is a ground based gamma ray detector which uses the heliostats of a solar power facility to collect and focus Cherenkov light onto a system of secondary optics and photomultiplier tubes. To monitor the gain and check the linearity and timing properties of the phototubes and associated electronics, a system based on a dye laser, neutral density filters and optical fibres has been developed. In this paper we describe the system and present some results from initial tests made with it.

  1. Welding technology transfer task/laser based weld joint tracking system for compressor girth welds

    Science.gov (United States)

    Looney, Alan

    1991-01-01

    Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

  2. Ultrafast, laser-based, x-ray science: the dawn of atomic-scale cinematography

    Energy Technology Data Exchange (ETDEWEB)

    Barty, C.P.J. [University of California, Department of Applied Mechanics and Engineering Science, Urey Hall, Mali Code 0339, San Diego, La Jolla, CA (United States)

    2000-03-01

    The characteristics of ultrafast chirped pulse amplification systems are reviewed. Application of ultrafast chirped pulse amplification to the generation of femtosecond, incoherent, 8-keV line radiation is outlined and the use of femtosecond laser-based, x-rays for novel time-resolved diffraction studies of crystalline dynamics with sub-picosecond temporal resolution and sub-picometer spatial resolution is reviewed in detail. Possible extensions of laser-based, x-ray technology and evaluation of alternative x-ray approaches for time-resolved studies of the atomic scale dynamics are given. (author)

  3. XUV free-electron laser-based projection lithography systems

    Energy Technology Data Exchange (ETDEWEB)

    Newnam, B.E.

    1990-01-01

    Free-electron laser sources, driven by rf-linear accelerators, have the potential to operate in the extreme ultraviolet (XUV) spectral range with more than sufficient average power for high-volume projection lithography. For XUV wavelengths from 100 nm to 4 nm, such sources will enable the resolution limit of optical projection lithography to be extended from 0.25 {mu}m to 0.05{mu}m and with an adequate total depth of focus (1 to 2 {mu}m). Recent developments of a photoinjector of very bright electron beams, high-precision magnetic undulators, and ring-resonator cavities raise our confidence that FEL operation below 100 nm is ready for prototype demonstration. We address the motivation for an XUV FEL source for commercial microcircuit production and its integration into a lithographic system, include reflecting reduction masks, reflecting XUV projection optics and alignment systems, and surface-imaging photoresists. 52 refs., 7 figs.

  4. Multiphase flow parameter estimation based on laser scattering

    Science.gov (United States)

    Vendruscolo, Tiago P.; Fischer, Robert; Martelli, Cicero; Rodrigues, Rômulo L. P.; Morales, Rigoberto E. M.; da Silva, Marco J.

    2015-07-01

    The flow of multiple constituents inside a pipe or vessel, known as multiphase flow, is commonly found in many industry branches. The measurement of the individual flow rates in such flow is still a challenge, which usually requires a combination of several sensor types. However, in many applications, especially in industrial process control, it is not necessary to know the absolute flow rate of the respective phases, but rather to continuously monitor flow conditions in order to quickly detect deviations from the desired parameters. Here we show how a simple and low-cost sensor design can achieve this, by using machine-learning techniques to distinguishing the characteristic patterns of oblique laser light scattered at the phase interfaces. The sensor is capable of estimating individual phase fluxes (as well as their changes) in multiphase flows and may be applied to safety applications due to its quick response time.

  5. Laser speckle imaging based on photothermally driven convection

    Science.gov (United States)

    Regan, Caitlin; Choi, Bernard

    2016-02-01

    Laser speckle imaging (LSI) is an interferometric technique that provides information about the relative speed of moving scatterers in a sample. Photothermal LSI overcomes limitations in depth resolution faced by conventional LSI by incorporating an excitation pulse to target absorption by hemoglobin within the vascular network. Here we present results from experiments designed to determine the mechanism by which photothermal LSI decreases speckle contrast. We measured the impact of mechanical properties on speckle contrast, as well as the spatiotemporal temperature dynamics and bulk convective motion occurring during photothermal LSI. Our collective data strongly support the hypothesis that photothermal LSI achieves a transient reduction in speckle contrast due to bulk motion associated with thermally driven convection. The ability of photothermal LSI to image structures below a scattering medium may have important preclinical and clinical applications.

  6. Multiphase flow parameter estimation based on laser scattering

    International Nuclear Information System (INIS)

    Vendruscolo, Tiago P; Fischer, Robert; Martelli, Cicero; Da Silva, Marco J; Rodrigues, Rômulo L P; Morales, Rigoberto E M

    2015-01-01

    The flow of multiple constituents inside a pipe or vessel, known as multiphase flow, is commonly found in many industry branches. The measurement of the individual flow rates in such flow is still a challenge, which usually requires a combination of several sensor types. However, in many applications, especially in industrial process control, it is not necessary to know the absolute flow rate of the respective phases, but rather to continuously monitor flow conditions in order to quickly detect deviations from the desired parameters. Here we show how a simple and low-cost sensor design can achieve this, by using machine-learning techniques to distinguishing the characteristic patterns of oblique laser light scattered at the phase interfaces. The sensor is capable of estimating individual phase fluxes (as well as their changes) in multiphase flows and may be applied to safety applications due to its quick response time. (paper)

  7. Laser-based characterization and decontamination of contaminated facilities

    International Nuclear Information System (INIS)

    Leong, K.H.; Hunter, B.V.; Grace, J.E.; Pellin, M.J.; Leidich, H.F.; Kugler, T.R.

    1996-01-01

    This study examines the application of laser ablation to the characterization and decontamination of painted and unpainted concrete and metal surfaces that are typical of many facilities within the US Department of Energy complex. The utility of this promising technology is reviewed and the essential requirements for efficient ablation extracted. Recent data obtained on the ablation of painted steel surfaces and concrete are presented. The affects of beam irradiance, ablation speed and efficiency, and characteristics of the aerosol effluent are discussed. Characterization of the ablated components of the surface offers the ability of concurrent determination of the level of contamination. This concept can be applied online where the ablation endpoint can be determined. A conceptual system for the characterization and decontamination of surfaces is proposed

  8. Laser-based investigations in gas turbine model combustors

    Science.gov (United States)

    Meier, W.; Boxx, I.; Stöhr, M.; Carter, C. D.

    2010-10-01

    Dynamic processes in gas turbine (GT) combustors play a key role in flame stabilization and extinction, combustion instabilities and pollutant formation, and present a challenge for experimental as well as numerical investigations. These phenomena were investigated in two gas turbine model combustors for premixed and partially premixed CH4/air swirl flames at atmospheric pressure. Optical access through large quartz windows enabled the application of laser Raman scattering, planar laser-induced fluorescence (PLIF) of OH, particle image velocimetry (PIV) at repetition rates up to 10 kHz and the simultaneous application of OH PLIF and PIV at a repetition rate of 5 kHz. Effects of unmixedness and reaction progress in lean premixed GT flames were revealed and quantified by Raman scattering. In a thermo-acoustically unstable flame, the cyclic variation in mixture fraction and its role for the feedback mechanism of the instability are addressed. In a partially premixed oscillating swirl flame, the cyclic variations of the heat release and the flow field were characterized by chemiluminescence imaging and PIV, respectively. Using phase-correlated Raman scattering measurements, significant phase-dependent variations of the mixture fraction and fuel distributions were revealed. The flame structures and the shape of the reaction zones were visualized by planar imaging of OH distribution. The simultaneous OH PLIF/PIV high-speed measurements revealed the time history of the flow field-flame interaction and demonstrated the development of a local flame extinction event. Further, the influence of a precessing vortex core on the flame topology and its dynamics is discussed.

  9. Image-based tracking system for vibration measurement of a rotating object using a laser scanning vibrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongkyu, E-mail: akein@gist.ac.kr; Khalil, Hossam; Jo, Youngjoon; Park, Kyihwan, E-mail: khpark@gist.ac.kr [School of Mechatronics, Gwangju Institute of Science and Technology, Buk-gu, Gwangju, South Korea, 500-712 (Korea, Republic of)

    2016-06-28

    An image-based tracking system using laser scanning vibrometer is developed for vibration measurement of a rotating object. The proposed system unlike a conventional one can be used where the position or velocity sensor such as an encoder cannot be attached to an object. An image processing algorithm is introduced to detect a landmark and laser beam based on their colors. Then, through using feedback control system, the laser beam can track a rotating object.

  10. Research of high power and stable laser in portable Raman spectrometer based on SHINERS technology

    Science.gov (United States)

    Cui, Yongsheng; Yin, Yu; Wu, Yulin; Ni, Xuxiang; Zhang, Xiuda; Yan, Huimin

    2013-08-01

    The intensity of Raman light is very weak, which is only from 10-12 to 10-6 of the incident light. In order to obtain the required sensitivity, the traditional Raman spectrometer tends to be heavy weight and large volume, so it is often used as indoor test device. Based on the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) method, Raman optical spectrum signal can be enhanced significantly and the portable Raman spectrometer combined with SHINERS method will be widely used in various fields. The laser source must be stable enough and able to output monochromatic narrow band laser with stable power in the portable Raman spectrometer based on the SHINERS method. When the laser is working, the change of temperature can induce wavelength drift, thus the power stability of excitation light will be affected, so we need to strictly control the working temperature of the laser, In order to ensure the stability of laser power and output current, this paper adopts the WLD3343 laser constant current driver chip of Wavelength Electronics company and MCU P89LPC935 to drive LML - 785.0 BF - XX laser diode(LD). Using this scheme, the Raman spectrometer can be small in size and the drive current can be constant. At the same time, we can achieve functions such as slow start, over-current protection, over-voltage protection, etc. Continuous adjustable output can be realized under control, and the requirement of high power output can be satisfied. Max1968 chip is adopted to realize the accurate control of the laser's temperature. In this way, it can meet the demand of miniaturization. In term of temperature control, integral truncation effect of traditional PID algorithm is big, which is easy to cause static difference. Each output of incremental PID algorithm has nothing to do with the current position, and we can control the output coefficients to avoid full dose output and immoderate adjustment, then the speed of balance will be improved observably. Variable

  11. All-polarization maintaining erbium fiber laser based on carbon nanowalls saturable absorber

    Science.gov (United States)

    Kurata, Shintaro; Izawa, Jun; Kawaguchi, Norihito

    2018-02-01

    We report a soliton mode locked femtosecond oscillation with all-polarization maintaining erbuim doped fiber laser based on Carbon Nanowalls saturable absorber (CNWs SA). To improve the stability and the capability of the oscillator, the all-polarization maintaining(all-PM) fiber is generally used since PM fiber is tolerant of stretches and bends. The saturable absorber is an optical device that placed in a laser cavity to suppress continuous wave operation to promote cooperation between many modes to sustain ultrashort pulse operation. We apply CNWs for the material of SAs in our oscillator. CNWs are one of the nanocarbon materials, which are a high-aspect-ratio structure in the cross-section, where, although their width and height range in a few micrometers, the thickness is as small as ten nanometers or so. A sheet of CNWs is made up of nano-size graphite grain aggregates. Then CNWs structure is expected to have a high absorption to the incident light and large modulation depth due to a small number of carbon layers as well as CNT and Graphene. With this all-PM fiber laser oscillator based on CNWs SA, the soliton mode-locked laser oscillated with 66.3MHz repetition frequency and its spectrum width is 5.6nm in FWHM. Average output power is 8.1mW with 122.5mW laser diode pump power. In addition, the laser amplification system with erbium-doped fiber is constructed and amplifies the femtosecond pulse laser into 268.2mW and 3000mW pumping power.

  12. Design of optical axis jitter control system for multi beam lasers based on FPGA

    Science.gov (United States)

    Ou, Long; Li, Guohui; Xie, Chuanlin; Zhou, Zhiqiang

    2018-02-01

    A design of optical axis closed-loop control system for multi beam lasers coherent combining based on FPGA was introduced. The system uses piezoelectric ceramics Fast Steering Mirrors (FSM) as actuator, the Fairfield spot detection of multi beam lasers by the high speed CMOS camera for optical detecting, a control system based on FPGA for real-time optical axis jitter suppression. The algorithm for optical axis centroid detecting and PID of anti-Integral saturation were realized by FPGA. Optimize the structure of logic circuit by reuse resource and pipeline, as a result of reducing logic resource but reduced the delay time, and the closed-loop bandwidth increases to 100Hz. The jitter of laser less than 40Hz was reduced 40dB. The cost of the system is low but it works stably.

  13. Brownian motion properties of optoelectronic random bit generators based on laser chaos.

    Science.gov (United States)

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Wang, Yuncai; Wang, Yongge

    2016-07-11

    The nondeterministic property of the optoelectronic random bit generator (RBG) based on laser chaos are experimentally analyzed from two aspects of the central limit theorem and law of iterated logarithm. The random bits are extracted from an optical feedback chaotic laser diode using a multi-bit extraction technique in the electrical domain. Our experimental results demonstrate that the generated random bits have no statistical distance from the Brownian motion, besides that they can pass the state-of-the-art industry-benchmark statistical test suite (NIST SP800-22). All of them give a mathematically provable evidence that the ultrafast random bit generator based on laser chaos can be used as a nondeterministic random bit source.

  14. Enhancing Surface Finish of Additively Manufactured Titanium and Cobalt Chrome Elements Using Laser Based Finishing

    Science.gov (United States)

    Gora, Wojciech S.; Tian, Yingtao; Cabo, Aldara Pan; Ardron, Marcus; Maier, Robert R. J.; Prangnell, Philip; Weston, Nicholas J.; Hand, Duncan P.

    Additive manufacturing (AM) offers the possibility of creating a complex free form object as a single element, which is not possible using traditional mechanical machining. Unfortunately the typically rough surface finish of additively manufactured parts is unsuitable for many applications. As a result AM parts must be post-processed; typically mechanically machined and/or and polished using either chemical or mechanical techniques (both of which have their limitations). Laser based polishing is based on remelting of a very thin surface layer and it offers potential as a highly repeatable, higher speed process capable of selective area polishing, and without any waste problems (no abrasives or liquids). In this paper an in-depth investigation of CW laser polishing of titanium and cobalt chrome AM elements is presented. The impact of different scanning strategies, laser parameters and initial surface condition on the achieved surface finish is evaluated.

  15. Neural network approximation of nonlinearity in laser nano-metrology system based on TLMI

    Energy Technology Data Exchange (ETDEWEB)

    Olyaee, Saeed; Hamedi, Samaneh, E-mail: s_olyaee@srttu.edu [Nano-photonics and Optoelectronics Research Laboratory (NORLab), Faculty of Electrical and Computer Engineering, Shahid Rajaee Teacher Training University (SRTTU), Lavizan, 16788, Tehran (Iran, Islamic Republic of)

    2011-02-01

    In this paper, an approach based on neural network (NN) for nonlinearity modeling in a nano-metrology system using three-longitudinal-mode laser heterodyne interferometer (TLMI) for length and displacement measurements is presented. We model nonlinearity errors that arise from elliptically and non-orthogonally polarized laser beams, rotational error in the alignment of laser head with respect to the polarizing beam splitter, rotational error in the alignment of the mixing polarizer, and unequal transmission coefficients in the polarizing beam splitter. Here we use a neural network algorithm based on the multi-layer perceptron (MLP) network. The simulation results show that multi-layer feed forward perceptron network is successfully applicable to real noisy interferometer signals.

  16. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    Science.gov (United States)

    Baker, John; Thorpe, Ira

    2012-01-01

    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  17. Prototype of an energy enhancer for mask based laser materials processing

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general mask based laser material processing (MBLMP) is a process which suffers from a low energy efficiency, because the majority of the laser light is absorbed in or reflected by the mask. We have developed a device called an energy enhancer which is capable of improving the energy efficienc...... component reflectivity and alignment sensitivity are investigated in order to evaluate the possibility of making commercial use of the device. The obtainable image quality and how this is influenced by the focusing and imaging system is discussed in some detail....... by a factor of 2 - 4 for a typical TEA-CO2 system for mask based laser marking. A simple ray-tracing model has been built in order to design and optimise the energy enhancer. Thus we present experimental results as well as simulations and show fine accordance between the two. Important system parameters like...

  18. Neural network approximation of nonlinearity in laser nano-metrology system based on TLMI

    International Nuclear Information System (INIS)

    Olyaee, Saeed; Hamedi, Samaneh

    2011-01-01

    In this paper, an approach based on neural network (NN) for nonlinearity modeling in a nano-metrology system using three-longitudinal-mode laser heterodyne interferometer (TLMI) for length and displacement measurements is presented. We model nonlinearity errors that arise from elliptically and non-orthogonally polarized laser beams, rotational error in the alignment of laser head with respect to the polarizing beam splitter, rotational error in the alignment of the mixing polarizer, and unequal transmission coefficients in the polarizing beam splitter. Here we use a neural network algorithm based on the multi-layer perceptron (MLP) network. The simulation results show that multi-layer feed forward perceptron network is successfully applicable to real noisy interferometer signals.

  19. Ultra-stable, diode-pumped Nd-doped glass regenerative amplifier for the National Ignition Facility (NIF)

    International Nuclear Information System (INIS)

    Crane, J.K.; Martinez, M.; Beach, R.J.; Mitchell, S.; Pratt, G.; Christensen, J.J.

    1995-12-01

    We describe a diode laser-pumped Nd:glass regenerative amplifier that amplifies temporally shaped pulses with low distortion, high pulse-to- pulse stability, and high gain. This laser amplifier is a prototype subsystem for the National Ignition Facility (NIF) laser system. 2 refs., 1 fig

  20. [Laser-based quality assurance for robot-assisted milling at the base of the skull].

    Science.gov (United States)

    Maassen, M M; Malthan, D; Stallkamp, J; Schäfer, A; Dammann, F; Schwaderer, E; Zenner, H P

    2006-02-01

    Implanting active hearing devices in the lateral base of the skull requires high-precision, secure fixation of the electromagnetic transducer and long-life anchorage using osteosynthetic fixation plates referred to as mountain brackets. Nonlinear distortion in the acoustic signal path and consecutive implant loosening can only be avoided by exact osseous milling to create the necessary cavity bed while avoiding excessive milling. Robot technology is ideal for high-precision milling. However, safety measures are necessary in order to prevent errors from occurring during the reduction process. Ideally, a robot should be guided by a navigation system. However, robotic systems so far available do not yet have an integrated global navigation system. We used an animal model under laboratory conditions to examine the extent to which the semiautomatic ROBIN assistant system developed could be expected to increase osseous milling accuracy before implanting active electronic hearing devices into the recipient tissue in the cranium. An existing prototype system for robot-assisted skull base surgery was equipped with laser sensors for geometric measurement of the operation site. The three-dimensional measurement data was compared with CT simulation data before, during, and after the robot-assisted operation. The experiments were conducted on test objects as well as on animal models. Under ideal conditions, the operation site could be measured at a spatial resolution of better than 0.02 mm in each dimension. However, reflections and impurities in the operation site from bleeding and rinsing fluids did have a considerable effect on data collection, necessitating specialised registering procedures. Using an error-tolerant procedure specifically developed, the effective registering error could be kept under 0.3 mm. After milling, the resulting shape matched the intended form at an accuracy level of 0.8 mm. The results show that robot systems can reach the accuracy required for

  1. Microstructure and Corrosion Behavior of Laser Synthesized Cobalt Based Powder on Ti-6Al-4V

    Science.gov (United States)

    Adesina, O. S.; Popoola, A. P. I.; Pityana, S. L.; Oloruntoba, D. T.

    2018-05-01

    The corrosion behavior of titanium alloys when used for various dynamic offshore components has been a major concern of titanium drilling risers in deepwater energy extraction. A way of achieving specified requirement is the development of coatings suitable to protect the base material against corrosion. In this work, laser cladding technique which is known as a leading edge due to its distinctive properties and outcomes was used in synthesizing Co-based powder on titanium alloy. The processing parameters used were laser power of 900W; scan speed of 0.6 to 1.2 m/min; powderfeedrate1.0g/min;beamspotsize3mm;gasflowrate1.2L/min.The effects of cobalt addition and laser parameters on corrosion behavior of laser clad Ti6AL4V coating in 0.5M sulfuric medium were investigated using linear potentiodynamic polarization. The changes in microstructure and corrosion behavior were analyzed using scanning electron microscopy (SEM) while the X –ray diffraction (XRD) indicates the intermetallics in the coatings. Results showed that the coatings displayed good metallurgical bonding with dendritic formations between the coatings and the substrate. The anodic current density increased with lower scan speed. However, the corrosion current densities of laser-clad samples were lower than Ti6Al4V alloy.

  2. Simulation of Microstructure during Laser Rapid Forming Solidification Based on Cellular Automaton

    Directory of Open Access Journals (Sweden)

    Zhi-jian Wang

    2014-01-01

    Full Text Available The grain microstructure of molten pool during the solidification of TC4 titanium alloy in the single point laser cladding was investigated based on the CAFE model which is the cellular automaton (CA coupled with the finite element (FE method. The correct temperature field is the prerequisite for simulating the grain microstructure during the solidification of the molten pool. The model solves the energy equation by the FE method to simulate the temperature distribution in the molten pool of the single point laser cladding. Based on the temperature field, the solidification microstructure of the molten pool is also simulated with the CAFE method. The results show that the maximum temperature in the molten pool increases with the laser power and the scanning rate. The laser power has a larger influence on the temperature distribution of the molten pool than the scanning rate. During the solidification of the molten pool, the heat at the bottom of the molten pool transfers faster than that at the top of the molten pool. The grains rapidly grow into the molten pool, and then the columnar crystals are formed. This study has a very important significance for improving the quality of the structure parts manufactured through the laser cladding forming.

  3. Laser nanostructuring 3-D bioconstruction based on carbon nanotubes in a water matrix of albumin

    Science.gov (United States)

    Gerasimenko, Alexander Y.; Ichkitidze, Levan P.; Podgaetsky, Vitaly M.; Savelyev, Mikhail S.; Selishchev, Sergey V.

    2016-04-01

    3-D bioconstructions were created using the evaporation method of the water-albumin solution with carbon nanotubes (CNTs) by the continuous and pulsed femtosecond laser radiation. It is determined that the volume structure of the samples created by the femtosecond radiation has more cavities than the one created by the continuous radiation. The average diameter for multi-walled carbon nanotubes (MWCNTs) samples was almost two times higher (35-40 nm) than for single-walled carbon nanotubes (SWCNTs) samples (20-30 nm). The most homogenous 3-D bioconstruction was formed from MWCNTs by the continuous laser radiation. The hardness of such samples totaled up to 370 MPa at the nanoscale. High strength properties and the resistance of the 3-D bioconstructions produced by the laser irradiation depend on the volume nanotubes scaffold forming inside them. The scaffold was formed by the electric field of the directed laser irradiation. The covalent bond energy between the nanotube carbon molecule and the oxygen of the bovine serum albumin aminoacid residue amounts 580 kJ/mol. The 3-D bioconstructions based on MWCNTs and SWCNTs becomes overgrown with the cells (fibroblasts) over the course of 72 hours. The samples based on the both types of CNTs are not toxic for the cells and don't change its normal composition and structure. Thus the 3-D bioconstructions that are nanostructured by the pulsed and continuous laser radiation can be applied as implant materials for the recovery of the connecting tissues of the living body.

  4. Monitoring of pipelines in nuclear power plants by measuring laser-based mechanical impedance

    International Nuclear Information System (INIS)

    Lee, Hyeonseok; Sohn, Hoon; Yang, Suyoung; Yang, Jinyeol

    2014-01-01

    Using laser-based mechanical impedance (LMI) measurement, this study proposes a damage detection technique that enables structural health monitoring of pipelines under the high temperature and radioactive environments of nuclear power plants (NPPs). The applications of conventional electromechanical impedance (EMI) based techniques to NPPs have been limited, mainly due to the contact nature of piezoelectric transducers, which cannot survive under the high temperature and high radiation environments of NPPs. The proposed LMI measurement technique aims to tackle the limitations of the EMI techniques by utilizing noncontact laser beams for both ultrasound generation and sensing. An Nd:Yag pulse laser is used for ultrasound generation, and a laser Doppler vibrometer is employed for the measurement of the corresponding ultrasound responses. For the monitoring of pipes covered by insulation layers, this study utilizes optical fibers to guide the laser beams to specific target locations. Then, an outlier analysis is adopted for autonomous damage diagnosis. Validation of the proposed LMI technique is carried out on a carbon steel pipe elbow under varying temperatures. A corrosion defect chemically engraved in the specimen is successfully detected. (papers)

  5. Monitoring of pipelines in nuclear power plants by measuring laser-based mechanical impedance

    Science.gov (United States)

    Lee, Hyeonseok; Sohn, Hoon; Yang, Suyoung; Yang, Jinyeol

    2014-06-01

    Using laser-based mechanical impedance (LMI) measurement, this study proposes a damage detection technique that enables structural health monitoring of pipelines under the high temperature and radioactive environments of nuclear power plants (NPPs). The applications of conventional electromechanical impedance (EMI) based techniques to NPPs have been limited, mainly due to the contact nature of piezoelectric transducers, which cannot survive under the high temperature and high radiation environments of NPPs. The proposed LMI measurement technique aims to tackle the limitations of the EMI techniques by utilizing noncontact laser beams for both ultrasound generation and sensing. An Nd:Yag pulse laser is used for ultrasound generation, and a laser Doppler vibrometer is employed for the measurement of the corresponding ultrasound responses. For the monitoring of pipes covered by insulation layers, this study utilizes optical fibers to guide the laser beams to specific target locations. Then, an outlier analysis is adopted for autonomous damage diagnosis. Validation of the proposed LMI technique is carried out on a carbon steel pipe elbow under varying temperatures. A corrosion defect chemically engraved in the specimen is successfully detected.

  6. Final Report: Laser-Based Optical Trap for Remote Sampling of Interplanetary and Atmospheric Particulate Matter

    Science.gov (United States)

    Stysley, Paul

    2016-01-01

    Applicability to Early Stage Innovation NIAC Cutting edge and innovative technologies are needed to achieve the demanding requirements for NASA origin missions that require sample collection as laid out in the NRC Decadal Survey. This proposal focused on fully understanding the state of remote laser optical trapping techniques for capturing particles and returning them to a target site. In future missions, a laser-based optical trapping system could be deployed on a lander that would then target particles in the lower atmosphere and deliver them to the main instrument for analysis, providing remote access to otherwise inaccessible samples. Alternatively, for a planetary mission the laser could combine ablation and trapping capabilities on targets typically too far away or too hard for traditional drilling sampling systems. For an interstellar mission, a remote laser system could gather particles continuously at a safe distance; this would avoid the necessity of having a spacecraft fly through a target cloud such as a comet tail. If properly designed and implemented, a laser-based optical trapping system could fundamentally change the way scientists designand implement NASA missions that require mass spectroscopy and particle collection.

  7. A novel laser-based method for controlled crystallization in dental prosthesis materials

    Science.gov (United States)

    Cam, Peter; Neuenschwander, Beat; Schwaller, Patrick; Köhli, Benjamin; Lüscher, Beat; Senn, Florian; Kounga, Alain; Appert, Christoph

    2015-02-01

    Glass-ceramic materials are increasingly becoming the material of choice in the field of dental prosthetics, as they can feature both high strength and very good aesthetics. It is believed that their color, microstructure and mechanical properties can be tuned such as to achieve an optimal lifelike performance. In order to reach that ultimate perfection a controlled arrangement of amorphous and crystalline phases in the material is required. A phase transformation from amorphous to crystalline is achieved by a heat treatment at defined temperature levels. The traditional approach is to perform the heat treatment in a furnace. This, however, only allows a homogeneous degree of crystallization over the whole volume of the parent glass material. Here a novel approach using a local heat treatment by laser irradiation is presented. To investigate the potential of this approach the crystallization process of SiO2-Li2O-Al2O3-based glass has been studied with laser systems (pulsed and continuous wave) operating at different wavelengths. Our results show the feasibility of gradual and partial crystallization of the base material using continuous laser irradiation. A dental prosthesis machined from an amorphous glassy state can be effectively treated with laser irradiation and crystallized within a confined region of a few millimeters starting from the body surface. Very good aesthetics have been achieved. Preliminary investigation with pulsed nanosecond lasers of a few hundreds nanoseconds pulse width has enabled more refinement of crystallization and possibility to place start of phase change within the material bulk.

  8. Laser Brazing Characteristics of Al to Brass with Zn-Based Filler

    Science.gov (United States)

    Tan, Caiwang; Liu, Fuyun; Sun, Yiming; Chen, Bo; Song, Xiaoguo; Li, Liqun; Zhao, Hongyun; Feng, Jicai

    2018-05-01

    Laser brazing of Al to brass in lap configuration with Zn-based filler was performed in this work. The process parameters including laser power, defocused distance were found to have a significant influence on appearance, microstructure and mechanical properties. The process parameters were optimized to be laser power of 2700 W and defocusing distance of + 40 mm from brass surface. In addition, preheating exerted great influence on wetting and spreading ability of Zn filler on brass surface. The microstructure observation showed the thickness of reaction layer (CuZn phase) at the interface of the brass side would grow with the increase in laser power and the decrease in the laser defocusing distance. Moreover, preheating could increase the spreading area of the filler metal and induced the growth of the reaction layer. The highest tensile-shear load of the joint could reach 2100 N, which was 80% of that of Al alloy base metal. All the joints fractured along the CuZn reaction layer and brass interface. The fracture morphology displayed the characteristics of the cleavage fracture when without preheating before welding, while it displayed the characteristics of the quasi-cleavage fracture with preheating before welding.

  9. All-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers

    OpenAIRE

    Wienhold, T.; Kraemmer, S.; Wondimu, S.F.; Siegle, T.; Bog, U.; Weinzierl, U.; Schmidt, S.; Becker, H.; Kalt, H.; Mappes, T.; Koeber, S.; Koos, C.

    2015-01-01

    We present an all-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers integrated into a microfluidic chip. The chip is entirely made from polymers, enabling the use of the devices as low-cost disposables. The microgoblet cavities feature quality factors exceeding 105 and are fabricated from poly(methyl methacrylate) (PMMA) using spin-coating, mask-based optical lithography, wet chemical etching, and thermal reflow. In contrast to silica-based microtoroid reso...

  10. Laser-based terahertz-field-driven streak camera for the temporal characterization of ultrashort processes

    International Nuclear Information System (INIS)

    Schuette, Bernd

    2011-09-01

    In this work, a novel laser-based terahertz-field-driven streak camera is presented. It allows for a pulse length characterization of femtosecond (fs) extreme ultraviolet (XUV) pulses by a cross-correlation with terahertz (THz) pulses generated with a Ti:sapphire laser. The XUV pulses are emitted by a source of high-order harmonic generation (HHG) in which an intense near-infrared (NIR) fs laser pulse is focused into a gaseous medium. The design and characterization of a high-intensity THz source needed for the streak camera is also part of this thesis. The source is based on optical rectification of the same NIR laser pulse in a lithium niobate crystal. For this purpose, the pulse front of the NIR beam is tilted via a diffraction grating to achieve velocity matching between NIR and THz beams within the crystal. For the temporal characterization of the XUV pulses, both HHG and THz beams are focused onto a gas target. The harmonic radiation creates photoelectron wavepackets which are then accelerated by the THz field depending on its phase at the time of ionization. This principle adopted from a conventional streak camera and now widely used in attosecond metrology. The streak camera presented here is an advancement of a terahertz-field-driven streak camera implemented at the Free Electron Laser in Hamburg (FLASH). The advantages of the laser-based streak camera lie in its compactness, cost efficiency and accessibility, while providing the same good quality of measurements as obtained at FLASH. In addition, its flexibility allows for a systematic investigation of streaked Auger spectra which is presented in this thesis. With its fs time resolution, the terahertz-field-driven streak camera thereby bridges the gap between attosecond and conventional cameras. (orig.)

  11. GaSb-based single-mode distributed feedback lasers for sensing (Conference Presentation)

    Science.gov (United States)

    Gupta, James A.; Bezinger, Andrew; Lapointe, Jean; Poitras, Daniel; Aers, Geof C.

    2017-02-01

    GaSb-based tunable single-mode diode lasers can enable rapid, highly-selective and highly-sensitive absorption spectroscopy systems for gas sensing. In this work, single-mode distributed feedback (DFB) laser diodes were developed for the detection of various trace gases in the 2-3.3um range, including CO2, CO, HF, H2S, H2O and CH4. The lasers were fabricated using an index-coupled grating process without epitaxial regrowth, making the process significantly less expensive than conventional DFB fabrication. The devices are based on InGaAsSb/AlGaAsSb separate confinement heterostructures grown on GaSb by molecular beam epitaxy. DFB lasers were produced using a two step etch process. Narrow ridge waveguides were first defined by optical lithography and etched into the semiconductor. Lateral gratings were then defined on both sides of the ridge using electron-beam lithography and etched to produce the index-grating. Effective index modeling was used to optimize the ridge width, etch depths and the grating pitch to ensure single-lateral-mode operation and adequate coupling strength. The effective index method was further used to simulate the DFB laser emission spectrum, based on a transfer matrix model for light transmission through the periodic structure. The fabricated lasers exhibit single-mode operation which is tunable through the absorption features of the various target gases by adjustment of the drive current. In addition to the established open-path sensing applications, these devices have great potential for optoelectronic integrated gas sensors, making use of integrated photodetectors and possibly on-chip Si photonics waveguide structures.

  12. Laser-based terahertz-field-driven streak camera for the temporal characterization of ultrashort processes

    Energy Technology Data Exchange (ETDEWEB)

    Schuette, Bernd

    2011-09-15

    In this work, a novel laser-based terahertz-field-driven streak camera is presented. It allows for a pulse length characterization of femtosecond (fs) extreme ultraviolet (XUV) pulses by a cross-correlation with terahertz (THz) pulses generated with a Ti:sapphire laser. The XUV pulses are emitted by a source of high-order harmonic generation (HHG) in which an intense near-infrared (NIR) fs laser pulse is focused into a gaseous medium. The design and characterization of a high-intensity THz source needed for the streak camera is also part of this thesis. The source is based on optical rectification of the same NIR laser pulse in a lithium niobate crystal. For this purpose, the pulse front of the NIR beam is tilted via a diffraction grating to achieve velocity matching between NIR and THz beams within the crystal. For the temporal characterization of the XUV pulses, both HHG and THz beams are focused onto a gas target. The harmonic radiation creates photoelectron wavepackets which are then accelerated by the THz field depending on its phase at the time of ionization. This principle adopted from a conventional streak camera and now widely used in attosecond metrology. The streak camera presented here is an advancement of a terahertz-field-driven streak camera implemented at the Free Electron Laser in Hamburg (FLASH). The advantages of the laser-based streak camera lie in its compactness, cost efficiency and accessibility, while providing the same good quality of measurements as obtained at FLASH. In addition, its flexibility allows for a systematic investigation of streaked Auger spectra which is presented in this thesis. With its fs time resolution, the terahertz-field-driven streak camera thereby bridges the gap between attosecond and conventional cameras. (orig.)

  13. Nonablative Fractional Laser Resurfacing in Skin of Color: Evidence-based Review.

    Science.gov (United States)

    Kaushik, Shivani B; Alexis, Andrew F

    2017-06-01

    Background: Nonablative laser resurfacing represents one of the major advances in procedural dermatology over the past decade. However, its use in darker skin types is limited by safety concerns and a relative lack of available data. Aim: To provide evidence-based recommendations for the use of fractional lasers in darker skin types. Evidence review: A broad literature search of PubMed/Medline database was conducted in April 2016 using the term fractional lasers. A free text search of keywords including fractional resurfacing, nonablative lasers, skin type, skin of color, ethnic skin, Fitzpatrick skin type, Asian skin, African Americans, Afro-Caribbean, and Hispanics was also executed. An in-depth review of all the relevant articles fitting the authors' inclusion/exclusion criteria was performed. Thereafter, each study was assigned levels of evidence per the Modified Criteria by Oxford Center of Evidence Based Medicine. A recommendation was made for a specific treatment based on the presence of at least one Level 1 study or more than three Level 2 or 3 studies that had concordant results. Findings: The available evidence strongly suggests that fractional lasers are a favorable treatment option for a variety of dermatological diseases in Fitzpatrick skin phototypes IV to VI. Level 1 evidence was found for the use of fractional lasers for treating acne, striae and skin rejuvenation. Level 2 evidence was found for their use in acne scars, melasma, and surgical/traumatic scars. Conclusion: Fractional resurfacing is a safe and efficacious treatment option for various dermatological disorders in darker skin types; however, there is a paucity of high-quality studies involving skin types V and VI.

  14. Comparison of fiber delivered CO2 laser and electrocautery in transoral robot assisted tongue base surgery.

    Science.gov (United States)

    Karaman, Murat; Gün, Taylan; Temelkuran, Burak; Aynacı, Engin; Kaya, Cem; Tekin, Ahmet Mahmut

    2017-05-01

    To compare intra-operative and post-operative effectiveness of fiber delivered CO 2 laser to monopolar electrocautery in robot assisted tongue base surgery. Prospective non-randomized clinical study. Twenty moderate to severe obstructive sleep apnea (OSA) patients, non-compliant with Continuous Positive Airway Pressure (CPAP), underwent Transoral Robotic Surgery (TORS) using the Da Vinci surgical robot in our University Hospital. OSA was treated with monopolar electrocautery in 10 patients, and with flexible CO 2 laser fiber in another 10 patients. The following parameters in the two sets are analyzed: Intraoperative bleeding that required cauterization, robot operating time, need for tracheotomy, postoperative self-limiting bleeding, length of hospitalization, duration until start of oral intake, pre-operative and post-operative minimum arterial oxygen saturation, pre-operative and post-operative Epworth Sleepiness Scale score, postoperative airway complication and postoperative pain. Mean follow-up was 12 months. None of the patients required tracheotomy and there were no intraoperative complications related to the use of the robot or the CO 2 laser. The use of CO 2 laser in TORS-assisted tongue base surgery resulted in less intraoperative bleeding that required cauterization, shorter robot operating time, shorter length of hospitalization, shorter duration until start of oral intake and less postoperative pain, when compared to electrocautery. Postoperative apnea-hypopnea index scores showed better efficacy of CO 2 laser than electrocautery. Comparison of postoperative airway complication rates and Epworth sleepiness scale scores were found to be statistically insignificant between the two groups. The use of CO 2 laser in robot assisted tongue base surgery has various intraoperative and post-operative advantages when compared to monopolar electrocautery.

  15. The effectiveness of laser therapy in onychomycosis patients: An evidence-based case report

    Directory of Open Access Journals (Sweden)

    Rizky Lendl Prayogo

    2017-08-01

    Full Text Available Background: Onychomycosis may cause nail discoloration, thickening, nail bed separation, and other serious complications. For some cases, oral antifungal treatment is not tolerable because of its potential side effects and drug interactions. Laser therapy is considered as an alternative treatment, owing to the features of simple and effective, with only minor potential side effects. This EBCR was made to collect and appraise studies regarding the effectiveness of laser therapy for onychomycosis, and to suggest laser as an alternative treatment. Methods: Literature searching strategy was performed using Pubmed and Cochrane Library database to address the clinical problem. Keywords used were “laser” AND “onychomycosis”. Results: Seventy-nine articles were obtained from the search strategy procedure. After selection based on exclusion and inclusion criteria, and full-text availability, four relevant articles remained. Discussion: The study by Xu et al. was considered as the most valid study while compared to other three studies. This study used intention to treat analysis and had no loss of follow-up patients. Xu et al. compared mycological and clinical clearance rate between patients receiving laser, oral terbinafine, or combination of those two. It showed that laser therapy was less effective when compared to oral antifungal (Number Needed to Harm = 17. Conclusions: Laser has a lower level of effectiveness while compared to oral terbinafine as the current gold standard therapy for onychomycosis. However, laser therapy can still be used as an adjunctive therapy along with oral antifungal to achieve a better cure rate. More studies are needed to prove this hypothesis.

  16. Impairment analysis of WDM-PON based on low-cost tunable lasers

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael H.; Lawin, Mirko

    2016-01-01

    channel must be kept below 15%. Similar values result for the upstream pilot tones. In order to limit crosstalk, such systems require reduced launch power during wavelength tuning and can cover up to 40 km differential reach. These results confirm that WDM-PON based on low-cost lasers is a technically...

  17. Integrated photonic platform based on semipolar InGaN/GaN multiple section laser diodes

    KAUST Repository

    Shen, Chao

    2017-11-30

    The challenges to realizing III-nitride photonic integrated circuit (PIC) are discussed. Utilizing InGaN-based multi-section laser diode (LD) on semipolar GaN substrate, the seamless on-chip integration of III-nitride waveguide photodetector (WPD) in the visible regime has been demonstrated.

  18. Integrated photonic platform based on semipolar InGaN/GaN multiple section laser diodes

    KAUST Repository

    Shen, Chao; Lee, Changmin; Ng, Tien Khee; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.; Ooi, Boon S.

    2017-01-01

    The challenges to realizing III-nitride photonic integrated circuit (PIC) are discussed. Utilizing InGaN-based multi-section laser diode (LD) on semipolar GaN substrate, the seamless on-chip integration of III-nitride waveguide photodetector (WPD) in the visible regime has been demonstrated.

  19. Laser cladding of Zr-based coating on AZ91D magnesium alloy for ...

    Indian Academy of Sciences (India)

    based coating made of Zr powder was fabricated on AZ91D magnesium alloy by laser cladding. The microstructure of the coating was characterized by XRD, SEM and TEM techniques. The wear resistance of the coating was evaluated under dry ...

  20. Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems

    Science.gov (United States)

    Richards, Lance; Parker, Allen; Chan, Patrick

    2014-01-01

    The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles. This is the regular update of the Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems website.

  1. Hybrid Coupling of Laser Light sources to Silicon (Oxy)Nitride Based Waveguides

    NARCIS (Netherlands)

    Krijger, A.J.T. de; Bekman, H.H.P.T.

    1997-01-01

    An efficient method was developed to couple a diode laser to a high contrast waveguides. The laserdiodes were mounted with sub-micron precision using a thermocompression mounting technique. An AlGaAs (λ = 850 nm) laserdiode was coupled to a SiON based slab waveguide (efficiency η EQ 25 - 30%) and to

  2. InP based lasers and optical amplifiers with wire-/dot-like active regions

    DEFF Research Database (Denmark)

    Reithmaier, J. P.; Somers, A.; Deubert, S.

    2005-01-01

    Long wavelength lasers and semiconductor optical amplifiers based on InAs quantum wire/dot-like active regions were developed on InP substrates dedicated to cover the extended telecommunication wavelength range between 1.4 - 1.65 mm. In a brief overview different technological approaches will be ...

  3. Ultrawideband pulse generation based on overshooting effect in gain-switched semiconductor laser

    DEFF Research Database (Denmark)

    Torres-Company, V.; Prince, Kamau; Tafur Monroy, Idelfonso

    2008-01-01

    We demonstrate an alternative procedure to achieve ultrawideband (UWB) radio-frequency (RF) doublet impulses. It is based on the overshooting effect appearing by biasing a semiconductor laser close to the threshold with a large-amplitude signal. Specifically, with an optical bandpass filter...... a reliable, easy, and low-cost alternative for RF UWB impulse generation....

  4. Development of Articulated Competency-Based Curriculum in Laser/Electro-Optics Technology. Final Report.

    Science.gov (United States)

    Luzerne County Community Coll., Nanticoke, PA.

    A project was conducted at the Community College of Luzerne County (Pennsylvania) to develop, in cooperation with area vocational-technical schools, the first year of a competency-based curriculum in laser/electro-optics technology. Existing programs were reviewed and private sector input was sought in developing the curriculum and identifying…

  5. Lasers technology

    International Nuclear Information System (INIS)

    2014-01-01

    The Laser Technology Program of IPEN is developed by the Center for Lasers and Applications (CLA) and is committed to the development of new lasers based on the research of new optical materials and new resonator technologies. Laser applications and research occur within several areas such as Nuclear, Medicine, Dentistry, Industry, Environment and Advanced Research. Additional goals of the Program are human resource development and innovation, in association with Brazilian Universities and commercial partners

  6. Graphene Oxide-Based Q-Switched Erbium-Doped Fiber Laser

    International Nuclear Information System (INIS)

    Yap, Y. K.; Harun, S. W.; Ahmad, H.; Huang, N. M.

    2013-01-01

    We demonstrate a pulsed ring erbium-doped fiber laser based on graphene oxide (GO), employing a simplified Hummer's method to synthesize the GO via chemical oxidation of graphite flakes at room temperature. By dipping a fiber ferrule end face onto the GO suspension, GO is successfully coated onto the end face, making it a simple saturable absorption device. A stable Q-switched pulsed fiber laser is achieved with a low pump threshold of 9.5 mW at 980 nm. The pulse repetition rate ranges from 16.0 to 57.0 kHz. The pulse width and the pulse energy are studied and discussed

  7. Femtosecond laser ablation of single-wall carbon nanotube-based material

    International Nuclear Information System (INIS)

    Danilov, Pavel A; Ionin, Andrey A; Kudryashov, Sergey I; Makarov, Sergey V; Mel’nik, Nikolay N; Rudenko, Andrey A; Yurovskikh, Vladislav I; Zayarny, Dmitry V; Lednev, Vasily N; Obraztsova, Elena D; Pershin, Sergey M; Bunkin, Alexey F

    2014-01-01

    Single- and multi-shot femtosecond laser surface ablation of a single-wall carbon nanotube-based substrate at 515- and 1030 nm wavelengths was studied by scanning electron microscopy and micro-Raman spectroscopy. The laser ablation proceeds in two ways: as the low-fluence mesoscopic shallow disintegration of the surface nanotube packing, preserving the individual integrity and the semiconducting character of the nanotubes or as the high-fluence deep material removal apparently triggered by the strong intrinsic or impurity-mediated ablation of the individual carbon nanotubes on the substrate surface. (letter)

  8. Development of high-average-power-laser medium based on silica glass

    International Nuclear Information System (INIS)

    Fujimoto, Yasushi; Nakatsuka, Masahiro

    2000-01-01

    We have developed a high-average-power laser material based on silica glass. A new method using Zeolite X is effective for homogeneously dispersing rare earth ions in silica glass to get a high quantum yield. High quality medium, which is bubbleless and quite low refractive index distortion, must be required for realization of laser action, and therefore, we have carefully to treat the gelation and sintering processes, such as, selection of colloidal silica, pH value of for hydrolysis of tetraethylorthosilicate, and sintering history. The quality of the sintered sample and the applications are discussed. (author)

  9. Laser amplifier based on a neodymium glass rod 150 mm in diameter

    Energy Technology Data Exchange (ETDEWEB)

    Shaykin, A A; Fokin, A P; Soloviev, A A; Kuzmin, A A; Shaikin, I A; Burdonov, K F; Khazanov, E A [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Charukhchev, A V [Public Limited Company " Scientific research Institute for Optoelectronic Instrument Engineering" , Leningrad region (Russian Federation)

    2014-05-30

    A unique large-aperture neodymium glass rod amplifier is experimentally studied. The small-signal gain distribution is measured at different pump energies. The aperture-averaged gain is found to be 2.3. The stored energy (500 J), the maximum possible pump pulse repetition rate, and the depolarisation in a single pulse and in a series of pulses with a repetition rate of one pulse per five minutes are calculated based on the investigations performed. It is shown that the use of this amplifier at the exit of the existing laser can increase the output pulse energy from 300 to 600 J. (lasers)

  10. Laser-based secondary neutral mass spectroscopy: Useful yield and sensitivity

    International Nuclear Information System (INIS)

    Young, C.E.; Pellin, M.J.; Calaway, W.F.; Joergensen, B.; Schweitzer, E.L.; Gruen, D.M.

    1986-01-01

    A variety of problems exist in order to optimally apply resonance ionization spectroscopy (RIS) to the detection of sputtered neutral atoms, however. Several of these problems and their solutions are examined in this paper. First, the possible useful yields obtainable and the dependence of useful yield on various laser parameters for this type of sputtered neutral mass spectrometer (SNMS) are considered. Second, the choice of a mass spectrometer and its effect on the instrumental useful yield is explored in light of the unique ionization region for laser based SNMS. Finally a brief description of noise sources and their effect on the instrumental sensitivity is discussed. 33 refs., 12 figs

  11. Electroluminescence Analysis by Tilt Polish Technique of InP-Based Semiconductor Lasers

    Science.gov (United States)

    Ichikawa, Hiroyuki; Sasaki, Kouichi; Hamada, Kotaro; Yamaguchi, Akira

    2010-03-01

    We developed an effective electroluminescence (EL) analysis method to specify the degraded region of InP-based semiconductor lasers. The EL analysis method is one of the most important methods for failure analysis. However, EL observation was difficult because opaque electrodes surround an active layer. A portion of each electrode had to be left intact for wiring to inject the current. Thus, we developed a partial polish technique for the bottom electrode. Tilt polish equipment with a rotating table was introduced; a flat polished surface and a sufficiently wide remaining portion of the bottom electrode were obtained. As a result, clear EL from the back surface of the laser was observed.

  12. Laser-plasma accelerator-based single-cycle attosecond undulator source

    Science.gov (United States)

    Tibai, Z.; Tóth, Gy.; Nagyváradi, A.; Sharma, A.; Mechler, M. I.; Fülöp, J. A.; Almási, G.; Hebling, J.

    2018-06-01

    Laser-plasma accelerators (LPAs), producing high-quality electron beams, provide an opportunity to reduce the size of free-electron lasers (FELs) to only a few meters. A complete system is proposed here, which is based on FEL technology and consists of an LPA, two undulators, and other magnetic devices. The system is capable to generate carrier-envelope phase stable attosecond pulses with engineered waveform. Pulses with up to 60 nJ energy and 90-400 attosecond duration in the 30-120 nm wavelength range are predicted by numerical simulation. These pulses can be used to investigate ultrafast field-driven electron dynamics in matter.

  13. Tunable, multiwavelength-swept fiber laser based on nematic liquid crystal device for fiber-optic electric-field sensor

    Science.gov (United States)

    Lee, Hyun Ji; Kim, Sung-Jo; Ko, Myeong Ock; Kim, Jong-Hyun; Jeon, Min Yong

    2018-03-01

    We propose a tunable multiwavelength-swept laser based on a nematic liquid crystal (NLC) Fabry-Perot (FP) etalon, which is embedded in the resonator of a wavelength-swept laser. We achieve the continuous wavelength tuning of the multiwavelength-swept laser by applying the electric field to the NLC FP etalon. The free spectral range of the fabricated NLC FP etalon is approximately 7.9 nm. When the electric field applied to the NLC FP etalon exceeds the threshold value (Fréedericksz threshold voltage), the output of the multiwavelength-swept laser can be tuned continuously. The tuning range of the multiwavelength-swept laser can be achieved at a value greater than 75 nm, which has a considerably wider tunable range than a conventional multiwavelength laser based on an NLC FP etalon. The slope efficiencies in the spectral and temporal domains for the tunable multiwavelength-swept laser are 22.2 nm/(mVrms / μm) and 0.17 ms/(mVrms / μm), respectively in the linear region. Therefore, the developed multiwavelength-swept laser based on the NLC FP etalon can be applied to an electric-field sensor. Because the wavelength measurement and time measurement have a linear relationship, the electric-field sensor can detect a rapid change in the electric-field intensity by measuring the peak change of the pulse in the temporal domain using the NLC FP etalon-based multiwavelength-swept laser.

  14. Office-Based Transurethral Devascularisation of Low Grade Non-Invasive Urothelial Cancer Using Diode Laser. A Feasibility Study

    DEFF Research Database (Denmark)

    Hermann, Gregers G.; Mogensen, Karin; Lindvold, Lars René

    2015-01-01

    based setting, without the need for sedation and pain control and where the patient can leave immediately after treatment. An in vitro model was developed to examine the dose/response relationship between laser power, treatment time, and distance between laser fibre and target, using a 980 nm diode laser....... The width of tissue destruction was 2–3 mm independent of laser illumination time. The in vivo laser treatments devascularised the tumour, which was later shed from the mucosa and passed out with the urine in the days following treatment. Pain score was 0 on a visual log scale (0–10). The tumour had...... completely disappeared two weeks after treatment. This diode laser technique may provide almost pain‐free office‐based treatment of low grade urothelial cancer using flexible cystoscopes in conscious patients. A prospective randomised study will be scheduled to compare the technique with standard TUR...

  15. Three-dimensional graphene based passively mode-locked fiber laser.

    Science.gov (United States)

    Yang, Y; Loeblein, M; Tsang, S H; Chow, K K; Teo, E H T

    2014-12-15

    We present an all-fiber passively mode-locked fiber laser incorporating three-dimensional (3D) graphene as a saturable absorber (SA) for the first time to the best of our knowledge. The 3D graphene is synthesized by template-directed chemical vapor deposition (CVD). The SA is then simply formed by sandwiching the freestanding 3D graphene between two conventional fiber connectors without any deposition process. It is demonstrated that such 3D graphene based SA is capable to produce high quality mode-locked pulses. A passively mode-locked fiber laser is constructed and stable output pulses with a fundamental repetition rate of ~9.9 MHz and a pulse width of ~1 ps are generated from the fiber laser. The average output power of the laser is ~10.5 mW while the output pulse is operating at single pulse region. The results imply that the freestanding 3D graphene can be applied as an effective saturable absorption material for passively mode-locked lasers.

  16. Study on the propagation properties of laser in aerosol based on Monte Carlo simulation

    Science.gov (United States)

    Leng, Kun; Wu, Wenyuan; Zhang, Xi; Gong, Yanchun; Yang, Yuntao

    2018-02-01

    When laser propagate in the atmosphere, due to aerosol scattering and absorption, laser energy will continue to decline, affecting the effectiveness of the laser effect. Based on the Monte Carlo method, the relationship between the photon spatial energy distributions of the laser wavelengths of 10.6μm in marine, sand-type, water-soluble and soot aerosols ,and the propagation distance, visibility and the divergence angle were studied. The results show that for 10.6μm laser, the maximum number of attenuation of photons arriving at the receiving plane is sand-type aerosol, the minimal attenuation is water soluble aerosol; as the propagation distance increases, the number of photons arriving at the receiving plane decreases; as the visibility increases, the number of photons arriving at the receiving plane increases rapidly and then stabilizes; in the above cases, the photon energy distribution does not deviated from the Gaussian distribution; as the divergence angle increases, the number of photons arriving at the receiving plane is almost unchanged, but the photon energy distribution gradually deviates from the Gaussian distribution.

  17. LASER POINTER DETECTION BASED ON INTENSITY PROFILE ANALYSIS FOR APPLICATION IN TELECONSULTATION

    Directory of Open Access Journals (Sweden)

    NAIREEN IMTIAZ

    2017-08-01

    Full Text Available Telemedicine is application of electronic communication to deliver medical care remotely. An important aspect of telemedicine is teleconsultation which involves obtaining the professional opinion of a healthcare provider. One of the ways to improve eleconsultation is to equip the remote specialist via control of a laser pointer, located in the consultation area to provide a means of gesture. As such, accurate detection of laser spot is crucial in such systems as they rely on visual feedback, which enables the specialist in a remote site to control and point the laser in the active location using a standard mouse. The main issue in laser spot detection in a natural environment is the distinguishability of a laser point image from other bright regions and glare due to camera saturation. This problem remains unsolved without extensive computing and use of hardware filters. In this paper a hybrid algorithm is described which is aimed to work with natural indoor environment while limiting computation. This algorithm combines thresholding and blob evaluation methods with a novel image intensity profile comparison method based on linear regression. A comparison of the algorithm has been done with existing approaches. The developed algorithm shows a higher accuracy and faster execution time making it an ideal candidate for real time detection applications.

  18. Laser-based microstructuring of materials surfaces using low-cost microlens arrays

    Science.gov (United States)

    Nieto, Daniel; Vara, G.; Diez, J. A.; O`Connor, Gerard M.; Arines, Justo; Gómez-Reino, C.; Flores-Arias, M.

    2012-03-01

    Since frictional interactions in microscopically small components are becoming increasingly important for the development of new products for all modern technology, we present a laser-based technique for micro-patterning surfaces of materials using low-cost microlens arrays. The microlens used were fabricated on soda-lime glass using a laser direct-write technique, followed by a thermal treatment into an oven. By combining laser direct-write and the thermal treatment it was possible to obtain high quality elements using a low cost infrared laser widely implemented in industry which makes this technique attractive in comparison with other more expensive methods. The main advantage of using microlens arrays for micropatterning surfaces is the possibility of fabricating a large number of identical structures simultaneously, leading to a highly efficient process. In order to study the capabilities of the microlens fabricated for microstructuring materials, identical structures and arrays of holes were fabricated over a variety of materials, such us, stainless steel, polymer and ceramic. The minimum diameter of the individual microstructure generated at surface is 5 μm. Different nanosecond lasers operating at Infrared, Green and UV were used. The topography and morphology of the elements obtained were determined using a confocal microscope SENSOFAR 2300 Plμ.

  19. Development and characterization of a laser-based hard x-ray source

    International Nuclear Information System (INIS)

    Tillman, C.

    1996-11-01

    A laser-produced plasma was generated by focusing 100 fs laser pulses, with an energy of 150 mJ, onto metal targets. The laser intensity was expected to reach 10 17 W/cm -2 . Radiation was emitted from the created plasma, with photon energies up to the MeV region. The laser-based X-ray source was optimized, with the purpose of making it a realistic source of hard X-rays (>10 keV). Dedicated equipment was developed for efficient generation and utilization of the hard X-rays. The X-ray source was characterized with respect to its spatial extent and the X-ray yield. Measurements were made of the spectral distribution, by the use of single-photon-counting detectors in different geometries, crystal spectrometers and dose measurements in combination with absorption filters. Ablation of the target material in the laser produced plasma was investigated. Imaging applications have been demonstrated, including ultrafast (picosecond) X-ray imaging, magnification imaging of up to x80, differential imaging in the spectral domain, and imaging of various biological and technical objects. The biological response of ultra-intense X-ray pulses was assessed in cell-culture exposures. The results indicate that the biological response from ultra-intense X-ray exposures is similar to the response with conventional X-ray tubes. 82 refs., 14 figs

  20. Widely-duration-tunable nanosecond pulse Nd:YVO4 laser based on double Pockels cells

    Science.gov (United States)

    He, Li-Jiao; Liu, Ke; Bo, Yong; Wang, Xiao-Jun; Yang, Jing; Liu, Zhao; Zong, Qing-Shuang; Peng, Qin-Jun; Cui, Da-Fu; Xu, Zu-Yan

    2018-05-01

    The development of duration-tunable pulse lasers with constant output power is important for scientific research and materials processing. We present a widely-duration-tunable nanosecond (ns) pulse Nd:YVO4 laser based on double Pockels cells (PCs), i.e. inserting an extra PC into a conventional electro-optic Q-switched cavity dumped laser resonator. Under the absorbed pump power of 24.9 W, the pulse duration is adjustable from 31.9 ns to 5.9 ns by changing the amplitude of the high voltage on the inserted PC from 1100 V to 4400 V at the pulse repetition rate of 10 kHz. The corresponding average output power is almost entirely maintained in the range of 3.5–4.1 W. This represents more than three times increase in pulse duration tunable regime and average power compared to previously reported results for duration-tunable ns lasers. The laser beam quality factor was measured to be M 2  <  1.18.

  1. Laser Induced Breakdown Spectroscopy Based on Single Beam Splitting and Geometric Configuration for Effective Signal Enhancement

    Science.gov (United States)

    Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang

    2015-01-01

    A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS. PMID:25557721

  2. Development and characterization of a laser-based hard x-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Tillman, C.

    1996-11-01

    A laser-produced plasma was generated by focusing 100 fs laser pulses, with an energy of 150 mJ, onto metal targets. The laser intensity was expected to reach 10{sup 17} W/cm{sup -2}. Radiation was emitted from the created plasma, with photon energies up to the MeV region. The laser-based X-ray source was optimized, with the purpose of making it a realistic source of hard X-rays (>10 keV). Dedicated equipment was developed for efficient generation and utilization of the hard X-rays. The X-ray source was characterized with respect to its spatial extent and the X-ray yield. Measurements were made of the spectral distribution, by the use of single-photon-counting detectors in different geometries, crystal spectrometers and dose measurements in combination with absorption filters. Ablation of the target material in the laser produced plasma was investigated. Imaging applications have been demonstrated, including ultrafast (picosecond) X-ray imaging, magnification imaging of up to x80, differential imaging in the spectral domain, and imaging of various biological and technical objects. The biological response of ultra-intense X-ray pulses was assessed in cell-culture exposures. The results indicate that the biological response from ultra-intense X-ray exposures is similar to the response with conventional X-ray tubes. 82 refs., 14 figs.

  3. Time of Flight based diagnostics for high energy laser driven ion beams

    Science.gov (United States)

    Scuderi, V.; Milluzzo, G.; Alejo, A.; Amico, A. G.; Booth, N.; Cirrone, G. A. P.; Doria, D.; Green, J.; Kar, S.; Larosa, G.; Leanza, R.; Margarone, D.; McKenna, P.; Padda, H.; Petringa, G.; Pipek, J.; Romagnani, L.; Romano, F.; Schillaci, F.; Borghesi, M.; Cuttone, G.; Korn, G.

    2017-03-01

    Nowadays the innovative high power laser-based ion acceleration technique is one of the most interesting challenges in particle acceleration field, showing attractive characteristics for future multidisciplinary applications, including medical ones. Nevertheless, peculiarities of optically accelerated ion beams make mandatory the development of proper transport, selection and diagnostics devices in order to deliver stable and controlled ion beams for multidisciplinary applications. This is the main purpose of the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline that will be realized and installed within 2018 at the ELI-Beamlines research center in the Czech Republic, where laser driven high energy ions, up to 60 MeV/n, will be available for users. In particular, a crucial role will be played by the on-line diagnostics system, recently developed in collaboration with INFN-LNS (Italy), consisting of TOF detectors, placed along the beamline (at different detection distances) to provide online monitoring of key characteristics of delivered beams, such as energy, fluence and ion species. In this contribution an overview on the ELIMAIA available ion diagnostics will be briefly given along with the preliminary results obtained during a test performed with high energy laser-driven proton beams accelerated at the VULCAN PW-laser available at RAL facility (U.K.).

  4. Time of Flight based diagnostics for high energy laser driven ion beams

    International Nuclear Information System (INIS)

    Scuderi, V.; Margarone, D.; Schillaci, F.; Milluzzo, G.; Amico, A.G.; Cirrone, G.A.P.; Larosa, G.; Leanza, R.; Petringa, G.; Pipek, J.; Romano, F.; Alejo, A.; Doria, D.; Kar, S.; Borghesi, M.; Booth, N.; Green, J.; McKenna, P.; Padda, H.; Romagnani, L.

    2017-01-01

    Nowadays the innovative high power laser-based ion acceleration technique is one of the most interesting challenges in particle acceleration field, showing attractive characteristics for future multidisciplinary applications, including medical ones. Nevertheless, peculiarities of optically accelerated ion beams make mandatory the development of proper transport, selection and diagnostics devices in order to deliver stable and controlled ion beams for multidisciplinary applications. This is the main purpose of the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline that will be realized and installed within 2018 at the ELI-Beamlines research center in the Czech Republic, where laser driven high energy ions, up to 60 MeV/n, will be available for users. In particular, a crucial role will be played by the on-line diagnostics system, recently developed in collaboration with INFN-LNS (Italy), consisting of TOF detectors, placed along the beamline (at different detection distances) to provide online monitoring of key characteristics of delivered beams, such as energy, fluence and ion species. In this contribution an overview on the ELIMAIA available ion diagnostics will be briefly given along with the preliminary results obtained during a test performed with high energy laser-driven proton beams accelerated at the VULCAN PW-laser available at RAL facility (U.K.).

  5. Analysis of a wavelength selectable cascaded DFB laser based on the transfer matrix method

    International Nuclear Information System (INIS)

    Xie Hongyun; Chen Liang; Shen Pei; Sun Botao; Wang Renqing; Xiao Ying; You Yunxia; Zhang Wanrong

    2010-01-01

    A novel cascaded DFB laser, which consists of two serial gratings to provide selectable wavelengths, is presented and analyzed by the transfer matrix method. In this method, efficient facet reflectivity is derived from the transfer matrix built for each serial section and is then used to simulate the performance of the novel cascaded DFB laser through self-consistently solving the gain equation, the coupled wave equation and the current continuity equations. The simulations prove the feasibility of this kind of wavelength selectable laser and a corresponding designed device with two selectable wavelengths of 1.51 μm and 1.53 μm is realized by experiments on InP-based multiple quantum well structure. (semiconductor devices)

  6. Optical Characterization of SERS Substrates Based on Porous Au Films Prepared by Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    V. V. Strelchuk

    2015-01-01

    Full Text Available The SERS (surface enhanced Raman spectroscopy substrates based on nanocomposite porous films with gold nanoparticles (Au NPs arrays were formed using the method of the pulsed laser deposition from the back low-energy flux of erosion torch particles on the glass substrate fixed at the target plain. The dependencies of porosity, and morphology of the surface of the film regions located near and far from the torch axis on the laser ablation regime, laser pulses energy density, their number, and argon pressure in the vacuum chamber, were ascertained. The Au NPs arrays with the controllable extinction spectra caused by the local surface plasmon resonance were prepared. The possibility of the formation of SERS substrates for the detection of the Rhodamine 6G molecules with the concentration 10−10 Mol/L with the enhancement factor 4·107 was shown.

  7. A trap-based pulsed positron beam optimised for positronium laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, B. S., E-mail: ben.cooper.13@ucl.ac.uk; Alonso, A. M.; Deller, A.; Wall, T. E.; Cassidy, D. B. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-10-15

    We describe a pulsed positron beam that is optimised for positronium (Ps) laser-spectroscopy experiments. The system is based on a two-stage Surko-type buffer gas trap that produces 4 ns wide pulses containing up to 5 × 10{sup 5} positrons at a rate of 0.5-10 Hz. By implanting positrons from the trap into a suitable target material, a dilute positronium gas with an initial density of the order of 10{sup 7} cm{sup −3} is created in vacuum. This is then probed with pulsed (ns) laser systems, where various Ps-laser interactions have been observed via changes in Ps annihilation rates using a fast gamma ray detector. We demonstrate the capabilities of the apparatus and detection methodology via the observation of Rydberg positronium atoms with principal quantum numbers ranging from 11 to 22 and the Stark broadening of the n = 2 → 11 transition in electric fields.

  8. Laser Based In Situ Techniques: Novel Methods for Generating Extreme Conditions in TEM Samples

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, M; Lagrange, T; Reed, B; Armstrong, M; Campbell, G; DeHope, W; Kim, J; King, W; Masiel, D; Browning, N

    2008-02-25

    The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

  9. Experimental study of a quantum random-number generator based on two independent lasers

    Science.gov (United States)

    Sun, Shi-Hai; Xu, Feihu

    2017-12-01

    A quantum random-number generator (QRNG) can produce true randomness by utilizing the inherent probabilistic nature of quantum mechanics. Recently, the spontaneous-emission quantum phase noise of the laser has been widely deployed for quantum random-number generation, due to its high rate, its low cost, and the feasibility of chip-scale integration. Here, we perform a comprehensive experimental study of a phase-noise-based QRNG with two independent lasers, each of which operates in either continuous-wave (CW) or pulsed mode. We implement the QRNG by operating the two lasers in three configurations, namely, CW + CW, CW + pulsed, and pulsed + pulsed, and demonstrate their trade-offs, strengths, and weaknesses.

  10. Retrieval Algorithms for Road Surface Modelling Using Laser-Based Mobile Mapping

    Directory of Open Access Journals (Sweden)

    Antero Kukko

    2008-09-01

    Full Text Available Automated processing of the data provided by a laser-based mobile mapping system will be a necessity due to the huge amount of data produced. In the future, vehiclebased laser scanning, here called mobile mapping, should see considerable use for road environment modelling. Since the geometry of the scanning and point density is different from airborne laser scanning, new algorithms are needed for information extraction. In this paper, we propose automatic methods for classifying the road marking and kerbstone points and modelling the road surface as a triangulated irregular network. On the basis of experimental tests, the mean classification accuracies obtained using automatic method for lines, zebra crossings and kerbstones were 80.6%, 92.3% and 79.7%, respectively.

  11. Multipoint fiber-optic laser-ultrasonic actuator based on fiber core-opened tapers.

    Science.gov (United States)

    Tian, Jiajun; Dong, Xiaolong; Gao, Shimin; Yao, Yong

    2017-11-27

    In this study, a novel fiber-optic, multipoint, laser-ultrasonic actuator based on fiber core-opened tapers (COTs) is proposed and demonstrated. The COTs were fabricated by splicing single-mode fibers using a standard fiber splicer. A COT can effectively couple part of a core mode into cladding modes, and the coupling ratio can be controlled by adjusting the taper length. Such characteristics are used to obtain a multipoint, laser-ultrasonic actuator with balanced signal strength by reasonably controlling the taper lengths of the COTs. As a prototype, we constructed an actuator that generated ultrasound at four points with a balanced ultrasonic strength by connecting four COTs with coupling ratios of 24.5%, 33.01%, 49.51%, and 87.8% in a fiber link. This simple-to-fabricate, multipoint, laser-ultrasonic actuator with balanced ultrasound signal strength has potential applications in fiber-optic ultrasound testing technology.

  12. A review on laser and light-based therapies for alopecia areata.

    Science.gov (United States)

    Mlacker, Stephanie; Aldahan, Adam Souhail; Simmons, Brian James; Shah, Vidhi; McNamara, Colin Andrew; Samarkandy, Sahal; Nouri, Keyvan

    2017-04-01

    Alopecia areata is a form of non-scarring alopecia that results from a hyperactive immune response of T cells against hair follicles. Many patients with visible hair loss experience psychological and emotional distress, as a result of their cosmetic disfigurement, and frequently seek treatment. However, existing treatment methods, such as corticosteroids, topical irritants, sensitizing agents, immunosuppressants, and psoralen plus ultraviolet light A, may result in various adverse effects and often lack efficacy. Laser and light treatments offer a safe and effective alternative. This review aims to provide clinicians with a comprehensive summary of laser and light-based modalities used for the treatment of alopecia areata. Currently, the excimer laser is the most widely studied device and has shown positive results thus far. However, the development of future randomized controlled clinical trials will help determine the appropriate treatment protocols necessary, in order to achieve superior clinical outcomes.

  13. Biological bases of the maximum permissible exposure levels of the UK laser standard BS 4803 1983

    CERN Document Server

    MacKinlay, Alistair F

    1983-01-01

    The use of lasers has increased greatly over the past 15 years or so, to the extent that they are now used routinely in many occupational and public situations. There has been an increasing awareness of the potential hazards presented by lasers and substantial efforts have been made to formulate safety standards. In the UK the relevant Safety Standard is the British Standards Institution Standard BS 4803. This Standard was originally published in 1972 and a revision has recently been published (BS 4803: 1983). The revised standard has been developed using the American National Standards Institute Standard, ANSI Z136.1 (1973 onwards), as a model. In other countries, national standards have been similarly formulated, resulting in a large measure of international agreement through participation in the work of the International Electrotechnical Commission (IEC). The bases of laser safety standards are biophysical data on threshold injury effects, particularly on the retina, and the development of theoretical mode...

  14. Optical fibres sensor based in the intensity switch of a linear laser with two Bragg gratings

    International Nuclear Information System (INIS)

    Basurto P, M.A.; Kuzin, E.A.; Archundia B, C.; Marroquin, E.; May A, M.; Cerecedo N, H.H.; Sanchez M, J.J.; Tentori S, D.; Marquez B, I.; Shliagin, M.; Miridonov, S.

    2000-01-01

    In this work we propose a new configuration for an optical fiber temperature sensor, based on a linear type Er-doped fiber laser. The laser cavity consists of an Er-doped fiber and two identical Bragg gratings at the fiber ends (working as reflectors). Temperature changes are detected by measuring, through one of the gratings, the intensity variations at the system's output. When the temperature of one of the Bragg gratings is modified, a wavelength shift of its spectral reflectivity is observed. Hence, the laser emission intensity of the system is modified. We present experimental results of the intensity switch observed when the temperature difference between the gratings detunes their spectral reflectance. Making use of this effect it is possible to develop limit comparators to bound the temperature range for the object under supervision. This limiting work can be performed with a high sensitivity using a very simple interrogation procedure. (Author)

  15. A stabilized optical frequency comb based on an Er-doped fiber femtosecond laser

    Science.gov (United States)

    Xia, Chuanqing; Wu, Tengfei; Zhao, Chunbo; Xing, Shuai

    2018-03-01

    An optical frequency comb based on a 250 MHz home-made Er-doped fiber femtosecond laser is presented in this paper. The Er-doped fiber laser has a ring cavity and operates mode-locked in femtosecond regime with the technique of nonlinear polarization rotation. The pulse duration is 118 fs and the spectral width is 30 nm. A part of the femtosecond laser is amplified in Er-doped fiber amplifier before propagating through a piece of highly nonlinear fiber for expanding the spectrum. The carrier-envelope offset frequency of the comb which has a signal-to-noise ratio more than 35 dB is extracted by means of f-2f beating. It demonstrates that both carrier-envelope offset frequency and repetition frequency keep phase locked to a Rubidium atomic clock simultaneously for 2 hours. The frequency stabilized fiber combs will be increasingly applied in optical metrology, attosecond pulse generation, and absolute distance measurement.

  16. Modelling of a DBR laser based on Raman effect in a silicon-on-insulator rib waveguide

    International Nuclear Information System (INIS)

    De Leonardis, Francesco; Dimastrodonato, Valeria; Passaro, Vittorio M N

    2008-01-01

    In this paper, third-order nonlinearities in silicon-on-insulator rib waveguides are investigated to obtain complete modelling, describing the behaviour of a stimulated Raman scattering based laser. The simulations of a distributed Bragg reflector laser operation in a time domain allow for the first time to study in detail the dependence of threshold and output powers on different device parameters. Both continuous wave and pulsed laser operations are theoretically demonstrated, as well as their dependence on device parameters

  17. Laser-Based Surface Modification of Microstructure for Carbon Fiber-Reinforced Plastics

    Science.gov (United States)

    Yang, Wenfeng; Sun, Ting; Cao, Yu; Li, Shaolong; Liu, Chang; Tang, Qingru

    2018-05-01

    Bonding repair is a powerful feature of carbon fiber-reinforced plastics (CFRP). Based on the theory of interface bonding, the interface adhesion strength and reliability of the CFRP structure will be directly affected by the microscopic features of the CFRP surface, including the microstructure, physical, and chemical characteristics. In this paper, laser-based surface modification was compared to Peel-ply, grinding, and polishing to comparatively evaluate the surface microstructure of CFRP. The surface microstructure, morphology, fiber damage, height and space parameters were investigated by scanning electron microscopy (SEM) and laser confocal microscopy (LCM). Relative to the conventional grinding process, laser modification of the CFRP surface can result in more uniform resin removal and better processing control and repeatability. This decreases the adverse impact of surface fiber fractures and secondary damage. The surface properties were significantly optimized, which has been reflected such things as the obvious improvement of surface roughness, microstructure uniformity, and actual area. The improved surface microstructure based on laser modification is more conducive to interface bonding of CFRP structure repair. This can enhance the interfacial adhesion strength and reliability of repair.

  18. Fiber-Based, Trace-Gas, Laser Transmitter Technology Development for Space

    Science.gov (United States)

    Stephen, Mark; Yu, Anthony; Chen, Jeffrey; Nicholson, Jeffrey; Engin, Doruk; Mathason, Brian; Wu, Stewart; Allan, Graham; Hasselbrack, William; Gonzalez, Brayler; hide

    2015-01-01

    NASA’s Goddard Space Flight Center (GSFC) is working on maturing the technology readiness of a laser transmitter designed for use in atmospheric CO2 remote-sensing. GSFC has been developing an airplane-based CO2 lidar instrument over several years to demonstrate the efficacy of the instrumentation and measurement technique and to link the science models to the instrument performance. The ultimate goal is to make space-based satellite measurements with global coverage. In order to accomplish this, we must demonstrate the technology readiness and performance of the components as well as demonstrate the required power-scaling to make the link with the required signal-to-noise-ratio (SNR). To date, all the instrument components have been shown to have the required performance with the exception of the laser transmitter.In this program we are working on a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture where we will develop a ruggedized package and perform the relevant environmental tests to demonstrate TRL-6. In this paper we will review our transmitter architecture and progress on the performance and packaging of the laser transmitter.

  19. Local high precision 3D measurement based on line laser measuring instrument

    Science.gov (United States)

    Zhang, Renwei; Liu, Wei; Lu, Yongkang; Zhang, Yang; Ma, Jianwei; Jia, Zhenyuan

    2018-03-01

    In order to realize the precision machining and assembly of the parts, the geometrical dimensions of the surface of the local assembly surfaces need to be strictly guaranteed. In this paper, a local high-precision three-dimensional measurement method based on line laser measuring instrument is proposed to achieve a high degree of accuracy of the three-dimensional reconstruction of the surface. Aiming at the problem of two-dimensional line laser measuring instrument which lacks one-dimensional high-precision information, a local three-dimensional profile measuring system based on an accurate single-axis controller is proposed. First of all, a three-dimensional data compensation method based on spatial multi-angle line laser measuring instrument is proposed to achieve the high-precision measurement of the default axis. Through the pretreatment of the 3D point cloud information, the measurement points can be restored accurately. Finally, the target spherical surface is needed to make local three-dimensional scanning measurements for accuracy verification. The experimental results show that this scheme can get the local three-dimensional information of the target quickly and accurately, and achieves the purpose of gaining the information and compensating the error for laser scanner information, and improves the local measurement accuracy.

  20. Fiber laser cladding of nickel-based alloy on cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Arias-González, F., E-mail: felipeag@uvigo.es [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Val, J. del [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Comesaña, R. [Materials Engineering, Applied Mechanics and Construction Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J. [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain)

    2016-06-30

    Highlights: • Fiber laser cladding of Ni-based alloy on cast iron was experimentally studied. • Two different types of cast iron have been analyzed: gray and ductile cast iron. • Suitable processing parameters to generate a Ni-based coating were determined. • Dilution is higher in gray cast iron samples than in ductile cast iron. • Ni-based coating presents higher hardness than cast iron but similar Young's modulus. - Abstract: Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni-based

  1. Hole transport in c-plane InGaN-based green laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yang; Liu, Jianping, E-mail: jpliu2010@sinano.ac.cn; Tian, Aiqin; Zhang, Feng; Feng, Meixin; Hu, Weiwei; Zhang, Shuming; Ikeda, Masao; Li, Deyao; Zhang, Liqun; Yang, Hui [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); School of Nano Technology and Nano Bionics, University of Science and Technology of China, Suzhou 215123 (China)

    2016-08-29

    Hole transport in c-plane InGaN-based green laser diodes (LDs) has been investigated by both simulations and experiments. It is found that holes can overflow from the green double quantum wells (DQWs) at high current density, which reduces carrier injection efficiency of c-plane InGaN-based green LDs. A heavily silicon-doped layer right below the green DQWs can effectively suppress hole overflow from the green DQWs.

  2. Hydrating behavior of Mg-based nano-layers prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Wioniewski, Z; Bystrzycki, J; Mroz, W; Jastrzabski, C

    2009-01-01

    The hydriding behavior of Mg with TiO 2 and Si nanolayers prepared by the pulsed laser deposition (PLD) was studied. The phase structure, chemical composition and hydriding properties of the obtained Mg-based nanolayers were investigated by the XRD, TEM, AFM, RS, SIMS and the volumetric Sievert method. It was shown that PLD is an excellent technique for producing the complex structures based on Mg. Both, the kinetic and destabilization topics were investigated in this paper.

  3. Pyrolytic Carbon Nanosheets for Ultrafast and Ultrastable Sodium-Ion Storage.

    Science.gov (United States)

    Cho, Se Youn; Kang, Minjee; Choi, Jaewon; Lee, Min Eui; Yoon, Hyeon Ji; Kim, Hae Jin; Leal, Cecilia; Lee, Sungho; Jin, Hyoung-Joon; Yun, Young Soo

    2018-04-01

    Na-ion cointercalation in the graphite host structure in a glyme-based electrolyte represents a new possibility for using carbon-based materials (CMs) as anodes for Na-ion storage. However, local microstructures and nanoscale morphological features in CMs affect their electrochemical performances; they require intensive studies to achieve high levels of Na-ion storage performances. Here, pyrolytic carbon nanosheets (PCNs) composed of multitudinous graphitic nanocrystals are prepared from renewable bioresources by heating. In particular, PCN-2800 prepared by heating at 2800 °C has a distinctive sp 2 carbon bonding nature, crystalline domain size of ≈44.2 Å, and high electrical conductivity of ≈320 S cm -1 , presenting significantly high rate capability at 600 C (60 A g -1 ) and stable cycling behaviors over 40 000 cycles as an anode for Na-ion storage. The results of this study show the unusual graphitization behaviors of a char-type carbon precursor and exceptionally high rate and cycling performances of the resulting graphitic material, PCN-2800, even surpassing those of supercapacitors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Microstructures and tribological properties of laser cladded Ti-based metallic glass composite coatings

    International Nuclear Information System (INIS)

    Lan, Xiaodong; Wu, Hong; Liu, Yong; Zhang, Weidong; Li, Ruidi; Chen, Shiqi; Zai, Xiongfei; Hu, Te

    2016-01-01

    Metallic glass composite coatings Ti 45 Cu 41 Ni 9 Zr 5 and Ti 45 Cu 41 Ni 6 Zr 5 Sn 3 (at.%) on a Ti-30Nb-5Ta-7Zr (wt.%) (TNTZ) alloy were prepared by laser cladding. The microstructures of the coatings were characterized by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analyzer (EDXA), and transmission electron microscopy (TEM). Results indicated that the coatings have an amorphous structure embedded with a few nanocrystalline phases and dendrites. A partial substitution of Ni by Sn can improve the glass forming ability of Ti-base metallic glass system, and induce the formation of nano-sized Ni 2 SnTi phase during the cyclic laser heating. The tribological behavior of both the substrate and the coatings was investigated in detail. A significant improvement in both the hardness and the wear resistance of the coatings was achieved with the addition of Sn. The relationship between the wear resistance and the microstructures of the coatings was discussed. - Highlights: •Ti-based metallic glass composite coatings were prepared by laser cladding. •The wear resistance is greatly improved by laser cladding of composite coatings. •Substitution of Ni by Sn increases GFA and wear resistance of the coatings. •A good balance of crystalline/amorphous phases improves the wear resistance. •Adhesive wear serves as the dominant wear mechanism of the composite coatings.

  5. Laser Spot Tracking Based on Modified Circular Hough Transform and Motion Pattern Analysis

    Science.gov (United States)

    Krstinić, Damir; Skelin, Ana Kuzmanić; Milatić, Ivan

    2014-01-01

    Laser pointers are one of the most widely used interactive and pointing devices in different human-computer interaction systems. Existing approaches to vision-based laser spot tracking are designed for controlled indoor environments with the main assumption that the laser spot is very bright, if not the brightest, spot in images. In this work, we are interested in developing a method for an outdoor, open-space environment, which could be implemented on embedded devices with limited computational resources. Under these circumstances, none of the assumptions of existing methods for laser spot tracking can be applied, yet a novel and fast method with robust performance is required. Throughout the paper, we will propose and evaluate an efficient method based on modified circular Hough transform and Lucas–Kanade motion analysis. Encouraging results on a representative dataset demonstrate the potential of our method in an uncontrolled outdoor environment, while achieving maximal accuracy indoors. Our dataset and ground truth data are made publicly available for further development. PMID:25350502

  6. Laser spot tracking based on modified circular Hough transform and motion pattern analysis.

    Science.gov (United States)

    Krstinić, Damir; Skelin, Ana Kuzmanić; Milatić, Ivan

    2014-10-27

    Laser pointers are one of the most widely used interactive and pointing devices in different human-computer interaction systems. Existing approaches to vision-based laser spot tracking are designed for controlled indoor environments with the main assumption that the laser spot is very bright, if not the brightest, spot in images. In this work, we are interested in developing a method for an outdoor, open-space environment, which could be implemented on embedded devices with limited computational resources. Under these circumstances, none of the assumptions of existing methods for laser spot tracking can be applied, yet a novel and fast method with robust performance is required. Throughout the paper, we will propose and evaluate an efficient method based on modified circular Hough transform and Lucas-Kanade motion analysis. Encouraging results on a representative dataset demonstrate the potential of our method in an uncontrolled outdoor environment, while achieving maximal accuracy indoors. Our dataset and ground truth data are made publicly available for further development.

  7. Production and applications of quasi-monoenergetic electron bunches in laser-plasma based accelerators

    International Nuclear Information System (INIS)

    Glinec, Y.; Faure, J.; Ewald, F.; Lifschitz, A.; Malka, V.

    2006-01-01

    Plasmas are attractive media for the next generation of compact particle accelerators because they can sustain electric fields larger than those in conventional accelerators by three orders of magnitude. However, until now, plasma-based accelerators have produced relatively poor quality electron beams even though for most practical applications, high quality beams are required. In particular, beams from laser plasma-based accelerators tend to have a large divergence and very large energy spreads, meaning that different particles travel at different speeds. The combination of these two problems makes it difficult to utilize these beams. Here, we demonstrate the production of high quality and high energy electron beams from laser-plasma interaction: in a distance of 3 mm, a very collimated and quasi-monoenergetic electron beam is emitted with a 0.5 nanocoulomb charge at 170 ± 20 MeV. In this regime, we have observed very nonlinear phenomena, such as self-focusing and temporal self-shortenning down to 10 fs durations. Both phenomena increase the excitation of the wakefield. The laser pulse drives a highly nonlinear wakefield, able to trap and accelerate plasma background electrons to a single energy. We will review the different regimes of electron acceleration and we will show how enhanced performances can be reached with state-of-the-art ultrashort laser systems. Applications such as gamma radiography of such electron beams will also be discussed

  8. Fiber-ring laser-based intracavity photoacoustic spectroscopy for trace gas sensing.

    Science.gov (United States)

    Wang, Qiang; Wang, Zhen; Chang, Jun; Ren, Wei

    2017-06-01

    We demonstrated a novel trace gas sensing method based on fiber-ring laser intracavity photoacoustic spectroscopy. This spectroscopic technique is a merging of photoacoustic spectroscopy (PAS) with a fiber-ring cavity for sensitive and all-fiber gas detection. A transmission-type PAS gas cell (resonant frequency f0=2.68  kHz) was placed inside the fiber-ring laser to fully utilize the intracavity laser power. The PAS signal was excited by modulating the laser wavelength at f0/2 using a custom-made fiber Bragg grating-based modulator. We used this spectroscopic technique to detect acetylene (C2H2) at 1531.6 nm as a proof of principle. With a low Q-factor (4.9) of the PAS cell, our sensor achieved a good linear response (R2=0.996) to C2H2 concentration and a minimum detection limit of 390 ppbv at 2-s response time.

  9. Numerical simulation of residual stress in laser based additive manufacturing process

    Science.gov (United States)

    Kalyan Panda, Bibhu; Sahoo, Seshadev

    2018-03-01

    Minimizing the residual stress build-up in metal-based additive manufacturing plays a pivotal role in selecting a particular material and technique for making an industrial part. In beam-based additive manufacturing, although a great deal of effort has been made to minimize the residual stresses, it is still elusive how to do so by simply optimizing the processing parameters, such as beam size, beam power, and scan speed. Amid different types of additive manufacturing processes, Direct Metal Laser Sintering (DMLS) process uses a high-power laser to melt and sinter layers of metal powder. The rapid solidification and heat transfer on powder bed endows a high cooling rate which leads to the build-up of residual stresses, that will affect the mechanical properties of the build parts. In the present work, the authors develop a numerical thermo-mechanical model for the measurement of residual stress in the AlSi10Mg build samples by using finite element method. Transient temperature distribution in the powder bed was assessed using the coupled thermal to structural model. Subsequently, the residual stresses were estimated with varying laser power. From the simulation result, it found that the melt pool dimensions increase with increasing the laser power and the magnitude of residual stresses in the built part increases.

  10. High-spatial-resolution sub-surface imaging using a laser-based acoustic microscopy technique.

    Science.gov (United States)

    Balogun, Oluwaseyi; Cole, Garrett D; Huber, Robert; Chinn, Diane; Murray, Todd W; Spicer, James B

    2011-01-01

    Scanning acoustic microscopy techniques operating at frequencies in the gigahertz range are suitable for the elastic characterization and interior imaging of solid media with micrometer-scale spatial resolution. Acoustic wave propagation at these frequencies is strongly limited by energy losses, particularly from attenuation in the coupling media used to transmit ultrasound to a specimen, leading to a decrease in the depth in a specimen that can be interrogated. In this work, a laser-based acoustic microscopy technique is presented that uses a pulsed laser source for the generation of broadband acoustic waves and an optical interferometer for detection. The use of a 900-ps microchip pulsed laser facilitates the generation of acoustic waves with frequencies extending up to 1 GHz which allows for the resolution of micrometer-scale features in a specimen. Furthermore, the combination of optical generation and detection approaches eliminates the use of an ultrasonic coupling medium, and allows for elastic characterization and interior imaging at penetration depths on the order of several hundred micrometers. Experimental results illustrating the use of the laser-based acoustic microscopy technique for imaging micrometer-scale subsurface geometrical features in a 70-μm-thick single-crystal silicon wafer with a (100) orientation are presented.

  11. Moving Object Tracking and Avoidance Algorithm for Differential Driving AGV Based on Laser Measurement Technology

    Directory of Open Access Journals (Sweden)

    Pandu Sandi Pratama

    2012-12-01

    Full Text Available This paper proposed an algorithm to track the obstacle position and avoid the moving objects for differential driving Automatic Guided Vehicles (AGV system in industrial environment. This algorithm has several abilities such as: to detect the moving objects, to predict the velocity and direction of moving objects, to predict the collision possibility and to plan the avoidance maneuver. For sensing the local environment and positioning, the laser measurement system LMS-151 and laser navigation system NAV-200 are applied. Based on the measurement results of the sensors, the stationary and moving obstacles are detected and the collision possibility is calculated. The velocity and direction of the obstacle are predicted using Kalman filter algorithm. Collision possibility, time, and position can be calculated by comparing the AGV movement and obstacle prediction result obtained by Kalman filter. Finally the avoidance maneuver using the well known tangent Bug algorithm is decided based on the calculation data. The effectiveness of proposed algorithm is verified using simulation and experiment. Several examples of experiment conditions are presented using stationary obstacle, and moving obstacles. The simulation and experiment results show that the AGV can detect and avoid the obstacles successfully in all experimental condition. [Keywords— Obstacle avoidance, AGV, differential drive, laser measurement system, laser navigation system].

  12. High-precision pose measurement method in wind tunnels based on laser-aided vision technology

    Directory of Open Access Journals (Sweden)

    Liu Wei

    2015-08-01

    Full Text Available The measurement of position and attitude parameters for the isolated target from a high-speed aircraft is a great challenge in the field of wind tunnel simulation technology. In this paper, firstly, an image acquisition method for small high-speed targets with multi-dimensional movement in wind tunnel environment is proposed based on laser-aided vision technology. Combining with the trajectory simulation of the isolated model, the reasonably distributed laser stripes and self-luminous markers are utilized to capture clear images of the object. Then, after image processing, feature extraction, stereo correspondence and reconstruction, three-dimensional information of laser stripes and self-luminous markers are calculated. Besides, a pose solution method based on projected laser stripes and self-luminous markers is proposed. Finally, simulation experiments on measuring the position and attitude of high-speed rolling targets are conducted, as well as accuracy verification experiments. Experimental results indicate that the proposed method is feasible and efficient for measuring the pose parameters of rolling targets in wind tunnels.

  13. Experimental study of micro dimple fabrication based on laser shock processing

    Science.gov (United States)

    Li, Kangmei; Hu, Yongxiang; Yao, Zhenqiang

    2013-06-01

    Micro-dimple array has been generally considered as a valuable texture for sliding surfaces. It can improve lubrication and reduce wear by acting as reservoirs of lubricants and grinding debris. Laser shock processing (LSP) is an innovative process which can not only improve fatigue, corrosion and wearing resistance but also shape metallic parts accurately. In this study, a new process for the fabrication of micro dimples based on LSP was proposed, which was named as laser peen texturing (LPT). Experiments were performed on 2024 aluminum alloy, Oxygen-Free High Conductivity (OFHC) copper and SUS304 stainless steel to study the effects of processing parameters of LPT on surface integrity of the specimen. Surface morphology, micro hardness and microstructure of the micro dimples were investigated under various laser power densities, laser spot diameters and repeated shock numbers. It was found that the depth of the micro dimples induced by LPT is strongly dependent on material properties. The diameter, depth as well as aspect ratio of micro dimples were increased with the laser power density and the repeated shock number under the conditions in this study. But when the laser spot diameter changed, the variation laws of the diameter, depth and aspect ratio of the dimple were different from each other. The results of micro hardness measurements suggested that LPT is beneficial for the improvement of the micro hardness beneath the dimple. Grain refinement was found significantly on 2024 aluminum alloy and OFHC copper but not clearly on SUS304 stainless steel. Both the hardening effect and the grain refinement have close relationship with the depth of the micro dimple.

  14. Novel diode-based laser system for combined transcutaneous monitoring and computer-controlled intermittent treatment of jaundiced neonates

    Science.gov (United States)

    Hamza, Mostafa; El-Ahl, Mohammad H. S.; Hamza, Ahmad M.

    2001-06-01

    The high efficacy of laser phototherapy combined with transcutaneous monitoring of serum bilirubin provides optimum safety for jaundiced infants from the risk of bilirubin encephalopathy. In this paper the authors introduce the design and operating principles of a new laser system that can provide simultaneous monitoring and treatment of several jaundiced babies at one time. The new system incorporates diode-based laser sources oscillating at selected wavelengths to achieve both transcutaneous differential absorption measurements of bilirubin concentration in addition to the computer controlled intermittent laser therapy through a network of optical fibers. The detailed description and operating characteristics of this system are presented.

  15. Bidirectional current triggering in planar devices based on serially connected VO2 thin films using 965 nm laser diode.

    Science.gov (United States)

    Kim, Jihoon; Park, Kyongsoo; Kim, Bong-Jun; Lee, Yong Wook

    2016-08-08

    By incorporating a 965 nm laser diode, the bidirectional current triggering of up to 30 mA was demonstrated in a two-terminal planar device based on serially connected vanadium dioxide (VO2) thin films grown by pulsed laser deposition. The bidirectional current triggering was realized by using the focused beams of laser pulses through the photo-thermally induced phase transition of VO2. The transient responses of laser-triggered currents were also investigated when laser pulses excited the device at a variety of pulse widths and repetition rates of up to 4.0 Hz. A switching contrast between off- and on-state currents was obtained as ~8333, and rising and falling times were measured as ~39 and ~29 ms, respectively, for 50 ms laser pulses.

  16. Near-diffraction-limited segmented broad area diode laser based on off-axis spectral beam combining

    DEFF Research Database (Denmark)

    Jensen, O.B.; Thestrup Nielsen, Birgitte; Andersen, Peter E.

    2006-01-01

    -feedback scheme we are able to improve the beam quality of the laser by a factor of 23 from M-2 = 55 for the free-running diode laser to M-2 = 2.4 for the laser with feedback at a drive current of 2.2 A. The improved M-2 value is a factor of 3.4 below M-2 = 8.2 for a single free-running segment. This is the first......The beam quality of a 500-mu m-wide broad area diode laser with five active segments has been improved beyond the beam quality of the individual segments. The principle of this new laser system is based on off-axis feedback in combination with spectral beam combining. By using a double...... time that the beam quality of a segmented broad area diode laser has been improved beyond the beam quality of the individual segments....

  17. Non surgical laser and light in the treatment of chronic diseases: a review based on personal experiences

    Science.gov (United States)

    Longo, L.

    2010-11-01

    Since many years some effects of non surgical laser and light on biological tissue have been demonstrated, in vitro and in vivo. This review is based on the results obtained by me and my colleagues/follower in Italy. Aim of our study is to verify the anti-inflammatory and regenerative effects of non surgical laser and light therapy on patients with chronic diseases not good treatable with traditional therapies, as diabetes, and central nervous system injuries. In addition, many clinical data have emerged from double-blind trials on laser treatment of rheumatic diseases and in sports medicine. So, we would like to do a review on the state of the art of non surgical laser treatment in medicine, included aesthetic laser and light therapy field. We discuss the indications and limitations of aesthetic laser medicine, as concluded from the data analysis of the published literature and from over thirty years of personal experiences.

  18. Non surgical laser and light in the treatment of chronic diseases: a review based on personal experiences

    International Nuclear Information System (INIS)

    Longo, L

    2010-01-01

    Since many years some effects of non surgical laser and light on biological tissue have been demonstrated, in vitro and in vivo. This review is based on the results obtained by me and my colleagues/follower in Italy. Aim of our study is to verify the anti-inflammatory and regenerative effects of non surgical laser and light therapy on patients with chronic diseases not good treatable with traditional therapies, as diabetes, and central nervous system injuries. In addition, many clinical data have emerged from double-blind trials on laser treatment of rheumatic diseases and in sports medicine. So, we would like to do a review on the state of the art of non surgical laser treatment in medicine, included aesthetic laser and light therapy field. We discuss the indications and limitations of aesthetic laser medicine, as concluded from the data analysis of the published literature and from over thirty years of personal experiences

  19. Laser Guidestar Satellite for Ground-based Adaptive Optics Imaging of Geosynchronous Satellites and Astronomical Targets

    Science.gov (United States)

    Marlow, W. A.; Cahoy, K.; Males, J.; Carlton, A.; Yoon, H.

    2015-12-01

    Real-time observation and monitoring of geostationary (GEO) satellites with ground-based imaging systems would be an attractive alternative to fielding high cost, long lead, space-based imagers, but ground-based observations are inherently limited by atmospheric turbulence. Adaptive optics (AO) systems are used to help ground telescopes achieve diffraction-limited seeing. AO systems have historically relied on the use of bright natural guide stars or laser guide stars projected on a layer of the upper atmosphere by ground laser systems. There are several challenges with this approach such as the sidereal motion of GEO objects relative to natural guide stars and limitations of ground-based laser guide stars; they cannot be used to correct tip-tilt, they are not point sources, and have finite angular sizes when detected at the receiver. There is a difference between the wavefront error measured using the guide star compared with the target due to cone effect, which also makes it difficult to use a distributed aperture system with a larger baseline to improve resolution. Inspired by previous concepts proposed by A.H. Greenaway, we present using a space-based laser guide starprojected from a satellite orbiting the Earth. We show that a nanosatellite-based guide star system meets the needs for imaging GEO objects using a low power laser even from 36,000 km altitude. Satellite guide star (SGS) systemswould be well above atmospheric turbulence and could provide a small angular size reference source. CubeSatsoffer inexpensive, frequent access to space at a fraction of the cost of traditional systems, and are now being deployed to geostationary orbits and on interplanetary trajectories. The fundamental CubeSat bus unit of 10 cm cubed can be combined in multiple units and offers a common form factor allowing for easy integration as secondary payloads on traditional launches and rapid testing of new technologies on-orbit. We describe a 6U CubeSat SGS measuring 10 cm x 20 cm x

  20. Implementation of the laser-based femtosecond precision synchronization system at FLASH

    International Nuclear Information System (INIS)

    Schulz, Sebastian

    2011-05-01

    FLASH, the high-gain free-electron laser (FEL) in Hamburg, enables the generation of light pulses with wavelengths in the soft X-ray region and durations down to a few femtoseconds. To fully exploit this capability in time-resolved pump-probe experiments, and for the projected externally seeded operation, the critical components of the accelerator and several external laser systems have to be synchronized with a temporal accuracy at least in the same order of magnitude. This can not be realized purely with established RF-based systems and therefore, an optical, laser-based synchronization system is required. In this thesis, the optical synchronization system of FLASH has been, based on previous successful proof-of-principle experiments, massively extended. One major topic is the comprehensive characterization of the timing reference of the system and a comparison of different types of such master laser oscillators, as well as studies on their short- and long-term stability. Similar investigations have been carried out for the upgraded and newly installed length-stabilized fiber links, which connect the remote locations at the accelerator to the optical timing reference. The successful demonstration of an all-optical synchronization of a Ti:sapphire oscillator with sub-10 femtosecond timing jitter and the connection of the photo injector laser system to the synchronization system mark further important key experiments of this thesis. The robustness of the actual implementations played a key role, as the synchronization system forms the basis for the future, operator-friendly arrival time feedback.

  1. Determining diabetic retinopathy screening interval based on time from no retinopathy to laser therapy.

    Science.gov (United States)

    Hughes, Daniel; Nair, Sunil; Harvey, John N

    2017-12-01

    Objectives To determine the necessary screening interval for retinopathy in diabetic patients with no retinopathy based on time to laser therapy and to assess long-term visual outcome following screening. Methods In a population-based community screening programme in North Wales, 2917 patients were followed until death or for approximately 12 years. At screening, 2493 had no retinopathy; 424 had mostly minor degrees of non-proliferative retinopathy. Data on timing of first laser therapy and visual outcome following screening were obtained from local hospitals and ophthalmology units. Results Survival analysis showed that very few of the no retinopathy at screening group required laser therapy in the early years compared with the non-proliferative retinopathy group ( p retinopathy at screening group required laser therapy, and at three years 0.2% (cumulative), lower rates of treatment than have been suggested by analyses of sight-threatening retinopathy determined photographically. At follow-up (mean 7.8 ± 4.6 years), mild to moderate visual impairment in one or both eyes due to diabetic retinopathy was more common in those with retinopathy at screening (26% vs. 5%, p diabetes occurred in only 1 in 1000. Conclusions Optimum screening intervals should be determined from time to active treatment. Based on requirement for laser therapy, the screening interval for diabetic patients with no retinopathy can be extended to two to three years. Patients who attend for retinal screening and treatment who have no or non-proliferative retinopathy now have a very low risk of eventual blindness from diabetes.

  2. THE STRUCTURE AND PROPERTIES OF COMPOSITE LASER CLAD COATINGS WITH Ni BASED MATRIX WITH WC PARTICLES

    Directory of Open Access Journals (Sweden)

    Zita Iždinská

    2010-09-01

    Full Text Available In this work, the influence of the processing conditions on the microstructure and abrasive wear behavior of composite laser clad coatings with Ni based matrix reinforced with 50% WC particles is analyzed. Composite powder was applied in the form of coatings onto a mild steel substrate (Fe–0.17% C by different laser powers and cladding speeds. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM. Tribological properties of coatings were evaluated by pin-on-disc wear test. It appeared that the hardness of the matrix of composite coatings decreases with increasing cladding speed. However, wear resistance of composite coatings with decreasing hardness of Ni based matrix increases. Significantly enhanced wear resistance of WC composite coatings in comparison with Ni based coatings is attributed to the hard phase structures in composite coatings.

  3. Microfiber-based gold nanorods as saturable absorber for femtosecond pulse generation in a fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu-De [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China); School of Physics and Electronic Information, Huaibei Normal University, Huaibei, Anhui 235000 (China); Luo, Zhi-Chao; Liu, Hao; Liu, Meng; Luo, Ai-Ping, E-mail: luoaiping@scnu.edu.cn; Xu, Wen-Cheng, E-mail: xuwch@scnu.edu.cn [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)

    2014-10-20

    We reported on the femtosecond pulse generation from an erbium-doped fiber (EDF) laser by using microfiber-based gold nanorods (GNRs) as saturable absorber (SA). By virtue of the geometric characteristic of microfiber-based GNRs, the optical damage threshold of GNRs-SA could be greatly enhanced. The microfiber-based GNRs-SA shows a modulation depth of 4.9% and a nonsaturable loss of 21.1%. With the proposed GNRs-SA, the fiber laser emitted a mode-locked pulse train with duration of ∼887 fs. The obtained results demonstrated that the GNRs deposited microfiber could indeed serve as a high-performance SA towards the practical applications in the field of ultrafast photonics.

  4. Hunting for dark matter with ultra-stable fibre as frequency delay system.

    Science.gov (United States)

    Yang, Wanpeng; Li, Dawei; Zhang, Shuangyou; Zhao, Jianye

    2015-07-10

    Many cosmological observations point towards the existence of dark-matter(DM) particles and consider them as the main component of the matter content of the universe. The goal of revealing the nature of dark-matter has triggered the development of new, extremely sensitive detectors. It has been demonstrated that the frequencies and phases of optical clock have a transient shift during the DMs' arrival due to the DM-SM(Standard Model) coupling. A simple, reliable and feasible experimental scheme is firstly proposed in this paper, based on "frequency-delay system" to search dark-matter by "self-frequency comparison" of an optical clock. During the arrival of a dark-matter, frequency discrepancy is expected between two signals with a short time difference(~ms) of the same optical clock to exhibit the interaction between atoms and dark-matter. Furthermore, this process can determine the exact position of dark-matter when it is crossing the optical clocks, therefore a network of detecting stations located in different places is recommended to reduce the misjudgment risk to an acceptable level.

  5. Tunable high-power narrow-spectrum external-cavity diode laser based on tapered amplifier at 668 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Erbert, G.; Sumpf, B.

    2010-01-01

    A 668 nm tunable high-power narrow-spectrum diode laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The laser system is tunable from 659 to 675 nm. As high as 1.38 W output power is obtained at 668.35 nm. The emission spectral bandwidth is less than...

  6. Creating compact and microscale features in paper-based devices by laser cutting.

    Science.gov (United States)

    Mahmud, Md Almostasim; Blondeel, Eric J M; Kaddoura, Moufeed; MacDonald, Brendan D

    2016-11-14

    In this work we describe a fabrication method to create compact and microscale features in paper-based microfluidic devices using a CO 2 laser cutting/engraving machine. Using this method we are able to produce the smallest features with the narrowest barriers yet reported for paper-based microfluidic devices. The method uses foil backed paper as the base material and yields inexpensive paper-based devices capable of using small fluid sample volumes and thus small reagent volumes, which is also suitable for mass production. The laser parameters (power and laser head speed) were adjusted to minimize the width of hydrophobic barriers and we were able to create barriers with a width of 39 ± 15 μm that were capable of preventing cross-barrier bleeding. We generated channels with a width of 128 ± 30 μm, which we found to be the physical limit for small features in the chromatography paper we used. We demonstrate how miniaturizing of paper-based microfluidic devices enables eight tests on a single bioassay device using only 2 μL of sample fluid volume.

  7. ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

    Science.gov (United States)

    Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Holben, B. N.; Schmid, B.; Flynn, C. J.; Fahey, L.; LeBlanc, S. E.; Liss, J.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Dahlgren, R. P.; Pistone, K.; Karol, Y.

    2017-12-01

    The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution and climate. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. Hyperspectral cloud-transmitted radiance measurements enable the retrieval of cloud properties from below clouds. These measurements tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with optical fiber signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical tracking head, and future detector evolution. 4STAR has supported a broad range of flight experiments since it was first flown in 2010. This experience provides the basis for a series of improvements directed toward reducing measurement uncertainty and calibration complexity, and expanding future measurement capabilities, to be incorporated into a new 5STAR instrument. A 9-channel photodiode radiometer with AERONET-matched bandpass filters will be incorporated to improve calibration stability. A wide dynamic range tracking camera will provide a high precision solar position tracking signal as well as an image of sky conditions around the solar axis. An ultrasonic window cleaning system design will be tested. A UV spectrometer tailored for formaldehyde and SO2 gas retrievals will be added to the spectrometer enclosure. Finally, expansion capability for a 4 channel polarized radiometer to measure the Stokes polarization vector of sky light will be incorporated. This paper presents initial progress on this next-generation 5STAR instrument. Keywords: atmosphere; climate; pollution; radiometry; technology; hyperspectral; fiber optic

  8. AlGaN-based laser diodes for the short-wavelength ultraviolet region

    International Nuclear Information System (INIS)

    Yoshida, Harumasa; Kuwabara, Masakazu; Yamashita, Yoji; Takagi, Yasufumi; Uchiyama, Kazuya; Kan, Hirofumi

    2009-01-01

    We have demonstrated the room-temperature operation of GaN/AlGaN and indium-free AlGaN multiple-quantum-well (MQW) laser diodes under the pulsed-current mode. We have successfully grown low-dislocation-density AlGaN films with AlN mole fractions of 20 and 30% on sapphire substrates using the hetero-facet-controlled epitaxial lateral overgrowth (hetero-FACELO) method. GaN/AlGaN and AlGaN MQW laser diodes have been fabricated on the low-dislocation-density Al 0.2 Ga 0.8 N and Al 0.3 Ga 0.7 N films, respectively. The GaN/AlGaN MQW laser diodes lased at a peak wavelength ranging between 359.6 and 354.4 nm. A threshold current density of 8 kA cm -2 , an output power as high as 80 mW and a differential external quantum efficiency (DEQE) of 17.4% have been achieved. The AlGaN MQW laser diodes lased at a peak wavelength down to 336.0 nm far beyond the GaN band gap. For the GaN/AlGaN MQW laser diodes, the modal gain coefficient and the optical internal loss are estimated to be 4.7±0.6 cm kA -1 and 10.6±2.7 cm -1 , respectively. We have observed that the characteristic temperature T 0 ranges from 132 to 89 K and DEQE shows an almost stable tendency with increase of temperature. A temperature coefficient of 0.049 nm K -1 is also found for the GaN/AlGaN MQW laser diode. The results for the AlGaN-based laser diodes grown on high-quality AlGaN films presented here will be essential for the future development of laser diodes emitting much shorter wavelengths.

  9. Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Erlei [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Kemin, E-mail: zhangkm@sues.edu.cn [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zou, Jianxin [National Engineering Research Center of Light Alloys Net Forming & School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2016-03-30

    Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10{sup −5} A cm{sup −2} to 1.64 × 10{sup −6} A cm{sup −2}. The results show that laser cladding is an efficient method to improve

  10. Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

    International Nuclear Information System (INIS)

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin

    2016-01-01

    Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10"−"5 A cm"−"2 to 1.64 × 10"−"6 A cm"−"2. The results show that laser cladding is an efficient method to improve surface properties of Mg–Rare earth alloys.

  11. YCOB lasers

    International Nuclear Information System (INIS)

    Richardson, Martin; Hammons, Dennis; Eichenholz, Jason; Chai, Bruce; Ye, Qing; Jang, Won; Shah, Lawrence

    1999-01-01

    We review new developments with a new laser host material, YCa 4 O(BO 3 ) 3 or YCOB. Lasers based on this host material will open new opportunities for the development of compact, high-power, frequency-agile visible and near IR laser sources, as well as sources for ultrashort pulses. Efficient diode-pumped laser action with both Nd-doped and Yb-doped YCOB has already been demonstrated. Moreover, since these materials are biaxial, and have high nonlinear optical coefficients, they have become the first laser materials available as efficient self-frequency-doubled lasers, capable of providing tunable laser emission in several regions of the visible spectrum. Self-frequency doubling eliminates the need for inclusion of a nonlinear optical element within or external to the laser resonator. These laser materials possess excellent thermal and optical properties, have high laser-damage thresholds, and can be grown to large sizes. In addition they are non-hygroscopic. They therefore possess all the characteristics necessary for laser materials required in rugged, compact systems. Here we summarize the rapid progress made in the development of this new class of lasers, and review their potential for a number of applications. (author)

  12. Knowledge-Based Object Detection in Laser Scanning Point Clouds

    Science.gov (United States)

    Boochs, F.; Karmacharya, A.; Marbs, A.

    2012-07-01

    Object identification and object processing in 3D point clouds have always posed challenges in terms of effectiveness and efficiency. In practice, this process is highly dependent on human interpretation of the scene represented by the point cloud data, as well as the set of modeling tools available for use. Such modeling algorithms are data-driven and concentrate on specific features of the objects, being accessible to numerical models. We present an approach that brings the human expert knowledge about the scene, the objects inside, and their representation by the data and the behavior of algorithms to the machine. This "understanding" enables the machine to assist human interpretation of the scene inside the point cloud. Furthermore, it allows the machine to understand possibilities and limitations of algorithms and to take this into account within the processing chain. This not only assists the researchers in defining optimal processing steps, but also provides suggestions when certain changes or new details emerge from the point cloud. Our approach benefits from the advancement in knowledge technologies within the Semantic Web framework. This advancement has provided a strong base for applications based on knowledge management. In the article we will present and describe the knowledge technologies used for our approach such as Web Ontology Language (OWL), used for formulating the knowledge base and the Semantic Web Rule Language (SWRL) with 3D processing and topologic built-ins, aiming to combine geometrical analysis of 3D point clouds, and specialists' knowledge of the scene and algorithmic processing.

  13. All-optical fiber anemometer based on laser heated fiber Bragg gratings.

    Science.gov (United States)

    Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

    2011-05-23

    A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

  14. Non-invasive diagnostics of the maxillary and frontal sinuses based on diode laser gas spectroscopy.

    Science.gov (United States)

    Lewander, Märta; Lindberg, Sven; Svensson, Tomas; Siemund, Roger; Svanberg, Katarina; Svanberg, Sune

    2012-03-01

    Suspected, but objectively absent, rhinosinusitis constitutes a major cause of visits to the doctor, high health care costs, and the over-prescription of antibiotics, contributing to the serious problem of resistant bacteria. This situation is largely due to a lack of reliable and widely applicable diagnostic methods. A novel method for the diagnosis of rhinosinusitis based on non-intrusive diode laser gas spectroscopy is presented. The technique is based on light absorption by free gas (oxygen and water vapour) inside the sinuses, and has the potential to be a complementary diagnostic tool in primary health care. The method was evaluated on 40 patients with suspected sinus problems, referred to the diagnostic radiology clinic for low-dose computed tomography (CT), which was used as the reference technique. The data obtained with the new laser-based method correlated well with the grading of opacification and ventilation using CT. The sensitivity and specificity were estimated to be 93% and 61%, respectively, for the maxillary sinuses, and 94% and 86%, respectively, for the frontal sinuses. Good reproducibility was shown. The laser-based technique presents real-time clinical data that correlate well to CT findings, while being non-intrusive and avoiding the use of ionizing radiation.

  15. Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

    Directory of Open Access Journals (Sweden)

    Andrea Angelastro

    2013-01-01

    Full Text Available As a surface coating technique, laser cladding (LC has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr composite coatings were fabricated by the multilayer laser cladding technique (MLC. An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

  16. Progress in 41Ca ultratrace determination by diode-laser-based RIMS

    International Nuclear Information System (INIS)

    Mueller, P.; Blaum, K.; Diel, S.; Geppert, Ch.; Wendt, K.; Bushaw, B.A.; Trautmann, N.

    2001-01-01

    We report on progress in development and application of 41 Ca ultratrace determination by diode-laser-based RIMS. Applications include biomedical isotope-tracer studies of human calcium kinetics, cosmochemical investigations of meteorites, environmental dosimetry and radiodating. Depending on the application, 41 Ca needs to be determined at isotopic abundance in the range of 10 -9 to 10 -15 relative to the major stable isotope 40 Ca. We use either a double- or triple-resonance excitation scheme and subsequent non-resonant photoionization of calcium atoms in a collimated atomic beam. All resonant steps are excited with narrow bandwidth extended cavity diode lasers, non-resonant photo-ionization is attained with either an argon ion laser or a CO 2 laser. The resulting photo-ions are detected with a quadrupole mass spectrometer. With double-resonance excitation, the optical isotopic selectivity for 41 Ca against 40 Ca is 2x10 4 , while the triple-resonance scheme provides optical selectivity of more than 10 9 . By adding the third resonant step, overall detection efficiency increases from 1x10 -6 to 5x10 -5 and the detection limit for relative 41 Ca abundance improves from 5x10 -10 to 2x10 -13 . Both schemes have been applied to various sample types and accuracy and reproducibility of the resulting 41 Ca/ 40 Ca isotope ratios have been determined to be better than 5%

  17. Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

    Directory of Open Access Journals (Sweden)

    Chao Hu

    2015-04-01

    Full Text Available Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak, cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laser-scanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation quality assessment with the laser scanning technology can be reduced by 70%–90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

  18. Recent advancements in system design for miniaturized MEMS-based laser projectors

    Science.gov (United States)

    Scholles, M.; Frommhagen, K.; Gerwig, Ch.; Knobbe, J.; Lakner, H.; Schlebusch, D.; Schwarzenberg, M.; Vogel, U.

    2008-02-01

    Laser projection systems that use the flying spot principle and which are based on a single MEMS micro scanning mirrors are a very promising way to build ultra-compact projectors that may fit into mobile devices. First demonstrators that show the feasibility of this approach and the applicability of the micro scanning mirror developed by Fraunhofer IPMS for these systems have already been presented. However, a number of items still have to be resolved until miniaturized laser projectors are ready for the market. This contribution describes progress on several different items, each of them of major importance for laser projection systems. First of all, the overall performance of the system has been increased from VGA resolution to SVGA (800×600 pixels) with easy connection to a PC via DVI interface or by using the projector as embedded system with direct camera interface. Secondly, the degree of integration of the electronics has been enhanced by design of an application specific analog front end IC for the micro scanning mirror. It has been fabricated in a special high voltage technology and does not only allow to generate driving signals for the scanning mirror with amplitudes of up to 200V but also integrates position detection of the mirror by several methods. Thirdly, first results concerning Speckle reduction have been achieved, which is necessary for generation of images with high quality. Other aspects include laser modulation and solutions regarding projection on tilted screens which is possible because of the unlimited depth of focus.

  19. Towards the generation of random bits at terahertz rates based on a chaotic semiconductor laser

    International Nuclear Information System (INIS)

    Kanter, Ido; Aviad, Yaara; Reidler, Igor; Cohen, Elad; Rosenbluh, Michael

    2010-01-01

    Random bit generators (RBGs) are important in many aspects of statistical physics and crucial in Monte-Carlo simulations, stochastic modeling and quantum cryptography. The quality of a RBG is measured by the unpredictability of the bit string it produces and the speed at which the truly random bits can be generated. Deterministic algorithms generate pseudo-random numbers at high data rates as they are only limited by electronic hardware speed, but their unpredictability is limited by the very nature of their deterministic origin. It is widely accepted that the core of any true RBG must be an intrinsically non-deterministic physical process, e.g. measuring thermal noise from a resistor. Owing to low signal levels, such systems are highly susceptible to bias, introduced by amplification, and to small nonrandom external perturbations resulting in a limited generation rate, typically less than 100M bit/s. We present a physical random bit generator, based on a chaotic semiconductor laser, having delayed optical feedback, which operates reliably at rates up to 300Gbit/s. The method uses a high derivative of the digitized chaotic laser intensity and generates the random sequence by retaining a number of the least significant bits of the high derivative value. The method is insensitive to laser operational parameters and eliminates the necessity for all external constraints such as incommensurate sampling rates and laser external cavity round trip time. The randomness of long bit strings is verified by standard statistical tests.

  20. Towards the generation of random bits at terahertz rates based on a chaotic semiconductor laser

    Science.gov (United States)

    Kanter, Ido; Aviad, Yaara; Reidler, Igor; Cohen, Elad; Rosenbluh, Michael

    2010-06-01

    Random bit generators (RBGs) are important in many aspects of statistical physics and crucial in Monte-Carlo simulations, stochastic modeling and quantum cryptography. The quality of a RBG is measured by the unpredictability of the bit string it produces and the speed at which the truly random bits can be generated. Deterministic algorithms generate pseudo-random numbers at high data rates as they are only limited by electronic hardware speed, but their unpredictability is limited by the very nature of their deterministic origin. It is widely accepted that the core of any true RBG must be an intrinsically non-deterministic physical process, e.g. measuring thermal noise from a resistor. Owing to low signal levels, such systems are highly susceptible to bias, introduced by amplification, and to small nonrandom external perturbations resulting in a limited generation rate, typically less than 100M bit/s. We present a physical random bit generator, based on a chaotic semiconductor laser, having delayed optical feedback, which operates reliably at rates up to 300Gbit/s. The method uses a high derivative of the digitized chaotic laser intensity and generates the random sequence by retaining a number of the least significant bits of the high derivative value. The method is insensitive to laser operational parameters and eliminates the necessity for all external constraints such as incommensurate sampling rates and laser external cavity round trip time. The randomness of long bit strings is verified by standard statistical tests.

  1. Gelatin-based laser direct-write technique for the precise spatial patterning of cells.

    Science.gov (United States)

    Schiele, Nathan R; Chrisey, Douglas B; Corr, David T

    2011-03-01

    Laser direct-writing provides a method to pattern living cells in vitro, to study various cell-cell interactions, and to build cellular constructs. However, the materials typically used may limit its long-term application. By utilizing gelatin coatings on the print ribbon and growth surface, we developed a new approach for laser cell printing that overcomes the limitations of Matrigel™. Gelatin is free of growth factors and extraneous matrix components that may interfere with cellular processes under investigation. Gelatin-based laser direct-write was able to successfully pattern human dermal fibroblasts with high post-transfer viability (91% ± 3%) and no observed double-strand DNA damage. As seen with atomic force microscopy, gelatin offers a unique benefit in that it is present temporarily to allow cell transfer, but melts and is removed with incubation to reveal the desired application-specific growth surface. This provides unobstructed cellular growth after printing. Monitoring cell location after transfer, we show that melting and removal of gelatin does not affect cellular placement; cells maintained registry within 5.6 ± 2.5 μm to the initial pattern. This study demonstrates the effectiveness of gelatin in laser direct-writing to create spatially precise cell patterns with the potential for applications in tissue engineering, stem cell, and cancer research.

  2. Effect of advanced nanowire-based targets in nanosecond laser-matter interaction (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Lanzalone, G., E-mail: Gaetano.Lanzalone@ct.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore,” Via delle Olimpiadi, 94100 Enna (Italy); Altana, C. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Mascali, D.; Tudisco, S. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Muoio, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Malferrari, L.; Odorici, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Viale B. Pichat 6/2, 40127 Bologna (Italy); Malandrino, G. [Dipartimento di Scienze Chimiche and INSTM UdR, Università degli Studi di Catania, Catania (Italy)

    2016-02-15

    An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ag nanowires on laser energy absorption in the ns time domain has been carried out at the Laser Energy for Nuclear Science laboratory of INFN-LNS in Catania. The tested targets were realized at INFN-Bologna by anodizing aluminium sheets in order to obtain layers of porous Al{sub 2}O{sub 3} of different thicknesses, on which nanowires of various metals are grown by electro-deposition with different heights. Targets were then irradiated by using a Nd:YAG laser at different pumping energies. Advanced diagnostic tools were used for characterizing the plasma plume and ion production. As compared with targets of pure Al, a huge enhancement (of almost two order of magnitude) of the X-ray flux emitted by the plasma has been observed when using the nanostructured targets, with a corresponding decrease of the “optical range” signal, pointing out that the energetic content of the laser produced plasma was remarkably increased. This analysis was furthermore confirmed from time-of-flight spectra.

  3. Effect of advanced nanowire-based targets in nanosecond laser-matter interaction (invited)

    Science.gov (United States)

    Lanzalone, G.; Altana, C.; Mascali, D.; Muoio, A.; Malferrari, L.; Odorici, F.; Malandrino, G.; Tudisco, S.

    2016-02-01

    An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ag nanowires on laser energy absorption in the ns time domain has been carried out at the Laser Energy for Nuclear Science laboratory of INFN-LNS in Catania. The tested targets were realized at INFN-Bologna by anodizing aluminium sheets in order to obtain layers of porous Al2O3 of different thicknesses, on which nanowires of various metals are grown by electro-deposition with different heights. Targets were then irradiated by using a Nd:YAG laser at different pumping energies. Advanced diagnostic tools were used for characterizing the plasma plume and ion production. As compared with targets of pure Al, a huge enhancement (of almost two order of magnitude) of the X-ray flux emitted by the plasma has been observed when using the nanostructured targets, with a corresponding decrease of the "optical range" signal, pointing out that the energetic content of the laser produced plasma was remarkably increased. This analysis was furthermore confirmed from time-of-flight spectra.

  4. Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

    Science.gov (United States)

    Besozzi, E.; Maffini, A.; Dellasega, D.; Russo, V.; Facibeni, A.; Pazzaglia, A.; Beghi, M. G.; Passoni, M.

    2018-03-01

    In this work, we exploit nanosecond laser irradiation as a compact solution for investigating the thermomechanical behavior of tungsten materials under extreme thermal loads at the laboratory scale. Heat flux factor thresholds for various thermal effects, such as melting, cracking and recrystallization, are determined under both single and multishot experiments. The use of nanosecond lasers for mimicking thermal effects induced on W by fusion-relevant thermal loads is thus validated by direct comparison of the thresholds obtained in this work and the ones reported in the literature for electron beams and millisecond laser irradiation. Numerical simulations of temperature and thermal stress performed on a 2D thermomechanical code are used to predict the heat flux factor thresholds of the different thermal effects. We also investigate the thermal effect thresholds of various nanostructured W coatings. These coatings are produced by pulsed laser deposition, mimicking W coatings in tokamaks and W redeposited layers. All the coatings show lower damage thresholds with respect to bulk W. In general, thresholds decrease as the porosity degree of the materials increases. We thus propose a model to predict these thresholds for coatings with various morphologies, simply based on their porosity degree, which can be directly estimated by measuring the variation of the coating mass density with respect to that of the bulk.

  5. Laser-based Relative Navigation Using GPS Measurements for Spacecraft Formation Flying

    Science.gov (United States)

    Lee, Kwangwon; Oh, Hyungjik; Park, Han-Earl; Park, Sang-Young; Park, Chandeok

    2015-12-01

    This study presents a precise relative navigation algorithm using both laser and Global Positioning System (GPS) measurements in real time. The measurement model of the navigation algorithm between two spacecraft is comprised of relative distances measured by laser instruments and single differences of GPS pseudo-range measurements in spherical coordinates. Based on the measurement model, the Extended Kalman Filter (EKF) is applied to smooth the pseudo-range measurements and to obtain the relative navigation solution. While the navigation algorithm using only laser measurements might become inaccurate because of the limited accuracy of spacecraft attitude estimation when the distance between spacecraft is rather large, the proposed approach is able to provide an accurate solution even in such cases by employing the smoothed GPS pseudo-range measurements. Numerical simulations demonstrate that the errors of the proposed algorithm are reduced by more than about 12% compared to those of an algorithm using only laser measurements, as the accuracy of angular measurements is greater than 0.001° at relative distances greater than 30 km.

  6. Characterization of Ti and Co based biomaterials processed via laser based additive manufacturing

    Science.gov (United States)

    Sahasrabudhe, Himanshu

    Titanium and Cobalt based metallic materials are currently the most ideal materials for load-bearing metallic bio medical applications. However, the long term tribological degradation of these materials still remains a problem that needs a solution. To improve the tribological performance of these two metallic systems, three different research approaches were adapted, stemming out four different research projects. First, the simplicity of laser gas nitriding was utilized with a modern LENS(TM) technology to form an in situ nitride rich later in titanium substrate material. This nitride rich composite coating improved the hardness by as much as fifteen times and reduced the wear rate by more than a magnitude. The leaching of metallic ions during wear was also reduced by four times. In the second research project, a mixture of titanium and silicon were processed on a titanium substrate in a nitrogen rich environment. The results of this reactive, in situ additive manufacturing process were Ti-Si-Nitride coatings that were harder than the titanium substrate by more than twenty times. These coatings also reduced the wear rate by more than two magnitudes. In the third research approach, composites of CoCrMo alloy and Calcium phosphate (CaP) bio ceramic were processed using LENS(TM) based additive manufacturing. These composites were effective in reducing the wear in the CoCrMo alloy by more than three times as well as reduce the leaching of cobalt and chromium ions during wear. The novel composite materials were found to develop a tribofilm during wear. In the final project, a combination of hard nitride coating and addition of CaP bioceramic was investigated by processing a mixture of Ti6Al4V alloy and CaP in a nitrogen rich environment using the LENS(TM) technology. The resultant Ti64-CaP-Nitride coatings significantly reduced the wear damage on the substrate. There was also a drastic reduction in the metal ions leached during wear. The results indicate that the three

  7. KNOWLEDGE-BASED OBJECT DETECTION IN LASER SCANNING POINT CLOUDS

    Directory of Open Access Journals (Sweden)

    F. Boochs

    2012-07-01

    Full Text Available Object identification and object processing in 3D point clouds have always posed challenges in terms of effectiveness and efficiency. In practice, this process is highly dependent on human interpretation of the scene represented by the point cloud data, as well as the set of modeling tools available for use. Such modeling algorithms are data-driven and concentrate on specific features of the objects, being accessible to numerical models. We present an approach that brings the human expert knowledge about the scene, the objects inside, and their representation by the data and the behavior of algorithms to the machine. This “understanding” enables the machine to assist human interpretation of the scene inside the point cloud. Furthermore, it allows the machine to understand possibilities and limitations of algorithms and to take this into account within the processing chain. This not only assists the researchers in defining optimal processing steps, but also provides suggestions when certain changes or new details emerge from the point cloud. Our approach benefits from the advancement in knowledge technologies within the Semantic Web framework. This advancement has provided a strong base for applications based on knowledge management. In the article we will present and describe the knowledge technologies used for our approach such as Web Ontology Language (OWL, used for formulating the knowledge base and the Semantic Web Rule Language (SWRL with 3D processing and topologic built-ins, aiming to combine geometrical analysis of 3D point clouds, and specialists’ knowledge of the scene and algorithmic processing.

  8. Status and trends of short pulse generation using mode-locked lasers based on advanced quantum-dot active media

    International Nuclear Information System (INIS)

    Shi, L W; Chen, Y H; Xu, B; Wang, Z C; Jiao, Y H; Wang, Z G

    2007-01-01

    In this review, the potential of mode-locked lasers based on advanced quantum-dot (QD) active media to generate short optical pulses is analysed. A comprehensive review of experimental and theoretical work on related aspects is provided, including monolithic-cavity mode-locked QD lasers and external-cavity mode-locked QD lasers, as well as mode-locked solid-state and fibre lasers based on QD semiconductor saturable absorber mirrors. Performance comparisons are made for state-of-the-art experiments. Various methods for improving important characteristics of mode-locked pulses such as pulse duration, repetition rate, pulse power, and timing jitter through optimization of device design parameters or mode-locking methods are addressed. In addition, gain switching and self-pulsation of QD lasers are also briefly reviewed, concluding with the summary and prospects. (topical review)

  9. Simultaneous distributed strain and temperature sensing based on combined Raman–Brillouin scattering using Fabry–Perot lasers

    International Nuclear Information System (INIS)

    Bolognini, Gabriele; Soto, Marcelo A; Di Pasquale, Fabrizio

    2010-01-01

    An investigation is performed of the possibility of achieving simultaneous distributed strain and temperature sensing based on hybrid Raman–Brillouin scattering with the use of multi-wavelength optical sources such as common Fabry–Perot (FP) lasers. By employing a self-heterodyne detection scheme based on a multi-wavelength optical local oscillator, the benefits of FP lasers are fully exploited, allowing for high-power Raman intensity measurements and a simultaneous high-accuracy detection of the Brillouin frequency shift parameter for each FP longitudinal mode. Experimental results point out a significant reduction of coherent Rayleigh noise, and highlight the enhanced performance in hybrid Raman–Brillouin sensing when using FP lasers; in particular using standard FP lasers at 1550 nm results in about 12 dB (7 dB) temperature (strain) accuracy improvement at 25 km sensing distance with respect to the use of standard distributed feedback lasers

  10. Vision-based weld pool boundary extraction and width measurement during keyhole fiber laser welding

    Science.gov (United States)

    Luo, Masiyang; Shin, Yung C.

    2015-01-01

    In keyhole fiber laser welding processes, the weld pool behavior is essential to determining welding quality. To better observe and control the welding process, the accurate extraction of the weld pool boundary as well as the width is required. This work presents a weld pool edge detection technique based on an off axial green illumination laser and a coaxial image capturing system that consists of a CMOS camera and optic filters. According to the difference of image quality, a complete developed edge detection algorithm is proposed based on the local maximum gradient of greyness searching approach and linear interpolation. The extracted weld pool geometry and the width are validated by the actual welding width measurement and predictions by a numerical multi-phase model.

  11. SENSOR-TOPOLOGY BASED SIMPLICIAL COMPLEX RECONSTRUCTION FROM MOBILE LASER SCANNING

    Directory of Open Access Journals (Sweden)

    S. Guinard

    2018-05-01

    Full Text Available We propose a new method for the reconstruction of simplicial complexes (combining points, edges and triangles from 3D point clouds from Mobile Laser Scanning (MLS. Our main goal is to produce a reconstruction of a scene that is adapted to the local geometry of objects. Our method uses the inherent topology of the MLS sensor to define a spatial adjacency relationship between points. We then investigate each possible connexion between adjacent points and filter them by searching collinear structures in the scene, or structures perpendicular to the laser beams. Next, we create triangles for each triplet of self-connected edges. Last, we improve this method with a regularization based on the co-planarity of triangles and collinearity of remaining edges. We compare our results to a naive simplicial complexes reconstruction based on edge length.

  12. Sensor-Topology Based Simplicial Complex Reconstruction from Mobile Laser Scanning

    Science.gov (United States)

    Guinard, S.; Vallet, B.

    2018-05-01

    We propose a new method for the reconstruction of simplicial complexes (combining points, edges and triangles) from 3D point clouds from Mobile Laser Scanning (MLS). Our main goal is to produce a reconstruction of a scene that is adapted to the local geometry of objects. Our method uses the inherent topology of the MLS sensor to define a spatial adjacency relationship between points. We then investigate each possible connexion between adjacent points and filter them by searching collinear structures in the scene, or structures perpendicular to the laser beams. Next, we create triangles for each triplet of self-connected edges. Last, we improve this method with a regularization based on the co-planarity of triangles and collinearity of remaining edges. We compare our results to a naive simplicial complexes reconstruction based on edge length.

  13. Development of Laser LEDs Based a Programmable Optical Sensor for Detection of Environmental Pollutants

    Directory of Open Access Journals (Sweden)

    Amit K. Sharma

    2009-01-01

    Full Text Available The laser LED based optical sensor and its multifunctional operation for detection of environmental pollutants are described. The work will provide the instructions to design of circuitry for optical sensor instrument with a program based on a microcontroller (8902051-24PI, and to allow this program to communicate via RS-232 with computer. An algorithm is outlined by which the sensor instrument can use three laser LEDs (blue, Green and red to quantify the composition of pollutant. The operation of measurement through optical sensor has been applied to the study of detection and rate of reaction of pollutant i.e. methyl parathion and the produced informative data were also correlated with UV-vis spectrophotometry for the validation of results. The purpose of designed optical sensor is that the sophisticated analytical techniques show costly impact, time taking process, high consumable solvents and not suit for field application purpose which focuses the merits of the optical sensor.

  14. Synchronization of random bit generators based on coupled chaotic lasers and application to cryptography.

    Science.gov (United States)

    Kanter, Ido; Butkovski, Maria; Peleg, Yitzhak; Zigzag, Meital; Aviad, Yaara; Reidler, Igor; Rosenbluh, Michael; Kinzel, Wolfgang

    2010-08-16

    Random bit generators (RBGs) constitute an important tool in cryptography, stochastic simulations and secure communications. The later in particular has some difficult requirements: high generation rate of unpredictable bit strings and secure key-exchange protocols over public channels. Deterministic algorithms generate pseudo-random number sequences at high rates, however, their unpredictability is limited by the very nature of their deterministic origin. Recently, physical RBGs based on chaotic semiconductor lasers were shown to exceed Gbit/s rates. Whether secure synchronization of two high rate physical RBGs is possible remains an open question. Here we propose a method, whereby two fast RBGs based on mutually coupled chaotic lasers, are synchronized. Using information theoretic analysis we demonstrate security against a powerful computational eavesdropper, capable of noiseless amplification, where all parameters are publicly known. The method is also extended to secure synchronization of a small network of three RBGs.

  15. Depth estimation of laser glass drilling based on optical differential measurements of acoustic response

    Science.gov (United States)

    Gorodesky, Niv; Ozana, Nisan; Berg, Yuval; Dolev, Omer; Danan, Yossef; Kotler, Zvi; Zalevsky, Zeev

    2016-09-01

    We present the first steps of a device suitable for characterization of complex 3D micro-structures. This method is based on an optical approach allowing extraction and separation of high frequency ultrasonic sound waves induced to the analyzed samples. Rapid, non-destructive characterization of 3D micro-structures are limited in terms of geometrical features and optical properties of the sample. We suggest a method which is based on temporal tracking of secondary speckle patterns generated when illuminating a sample with a laser probe while applying known periodic vibration using an ultrasound transmitter. In this paper we investigated lasers drilled through glass vias. The large aspect ratios of the vias possess a challenge for traditional microscopy techniques in analyzing depth and taper profiles of the vias. The correlation of the amplitude vibrations to the vias depths is experimentally demonstrated.

  16. Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers

    Science.gov (United States)

    Moura-Netto, Cacio; Mello-Moura, Anna Carolina Volpi; Palo, Renato Miotto; Prokopowitsch, Igor; Pameijer, Cornelis H.; Marques, Marcia Martins

    2015-03-01

    This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n=168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz) diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis' test (p<0.05). Both adaptation and sealer penetration in root canals were not affected by the laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p<0.05). It can be concluded that intracanal laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.

  17. Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers.

    Science.gov (United States)

    Moura-Netto, Cacio; Mello-Moura, Anna Carolina Volpi; Palo, Renato Miotto; Prokopowitsch, Igor; Pameijer, Cornelis H; Marques, Marcia Martins

    2015-03-01

    This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n = 168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz); diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis' test (p laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.

  18. A NASA high-power space-based laser research and applications program

    Science.gov (United States)

    Deyoung, R. J.; Walberg, G. D.; Conway, E. J.; Jones, L. W.

    1983-01-01

    Applications of high power lasers are discussed which might fulfill the needs of NASA missions, and the technology characteristics of laser research programs are outlined. The status of the NASA programs or lasers, laser receivers, and laser propulsion is discussed, and recommendations are presented for a proposed expanded NASA program in these areas. Program elements that are critical are discussed in detail.

  19. GaAs-based high temperature electrically pumped polariton laser

    Energy Technology Data Exchange (ETDEWEB)

    Baten, Md Zunaid; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu; Frost, Thomas; Deshpande, Saniya; Das, Ayan [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lubyshev, Dimitri; Fastenau, Joel M.; Liu, Amy W. K. [IQE, Inc., 119 Technology Drive, Bethlehem, Pennsylvania 18015 (United States)

    2014-06-09

    Strong coupling effects and polariton lasing are observed at 155 K with an edge-emitting GaAs-based microcavity diode with a single Al{sub 0.31}Ga{sub 0.69}As/Al{sub 0.41}Ga{sub 0.59}As quantum well as the emitter. The threshold for polariton lasing is observed at 90 A/cm{sup 2}, accompanied by a reduction of the emission linewidth to 0.85 meV and a blueshift of the emission wavelength by 0.89 meV. Polariton lasing is confirmed by the observation of a polariton population redistribution in momentum space and spatial coherence. Conventional photon lasing is recorded in the same device at higher pump powers.

  20. LUX - A design study for a linac/laser-based ultrafast X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Heimann, P.; Leone, S.; Lidia, S.; Li, D.; Penn, G.; Ratti, A.; Reinsch, M.; Schoenlein, R.; Staples, J.; Stover, G.; Virostek, S.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Wurtele, J.; Zholents, A.

    2004-08-06

    A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators.

  1. Six-beam homodyne laser Doppler vibrometry based on silicon photonics technology.

    Science.gov (United States)

    Li, Yanlu; Zhu, Jinghao; Duperron, Matthieu; O'Brien, Peter; Schüler, Ralf; Aasmul, Soren; de Melis, Mirko; Kersemans, Mathias; Baets, Roel

    2018-02-05

    This paper describes an integrated six-beam homodyne laser Doppler vibrometry (LDV) system based on a silicon-on-insulator (SOI) full platform technology, with on-chip photo-diodes and phase modulators. Electronics and optics are also implemented around the integrated photonic circuit (PIC) to enable a simultaneous six-beam measurement. Measurement of a propagating guided elastic wave in an aluminum plate (speed ≈ 909 m/s @ 61.5 kHz) is demonstrated.

  2. LUX - A design study for a linac/laser-based ultrafast X-ray source

    International Nuclear Information System (INIS)

    Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Heimann, P.; Leone, S.; Lidia, S.; Li, D.; Penn, G.; Ratti, A.; Reinsch, M.; Schoenlein, R.; Staples, J.; Stover, G.; Virostek, S.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Wurtele, J.; Zholents, A.

    2004-01-01

    A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators

  3. Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry

    OpenAIRE

    Crua, Cyril; Heikal, Morgan R.

    2015-01-01

    In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a three dimensional laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limitin...

  4. Analysis of an atom laser based on the spatial control of the scattering length

    International Nuclear Information System (INIS)

    Carpentier, Alicia V.; Michinel, Humberto; Rodas-Verde, Maria I.; Perez-Garcia, Victor M.

    2006-01-01

    In this paper we analyze atom lasers based on the spatial modulation of the scattering length of a Bose-Einstein condensate. We demonstrate, through numerical simulations and approximate analytical methods, the controllable emission of matter-wave bursts and study the dependence of the process on the spatial shape of the scattering length along the axis of emission. We also study the role of an additional modulation of the scattering length in time

  5. Laser Research Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Laser Research lab is thecenter for the development of new laser sources, nonlinear optical materials, frequency conversion processes and laser-based sensors for...

  6. Laser power supply

    International Nuclear Information System (INIS)

    Bernstein, D.

    1975-01-01

    The laser power supply includes a regulator which has a high voltage control loop based on a linear approximation of a laser tube negative resistance characteristic. The regulator has independent control loops for laser current and power supply high voltage

  7. Rapid prototyping of 2D glass microfluidic devices based on femtosecond laser assisted selective etching process

    Science.gov (United States)

    Kim, Sung-Il; Kim, Jeongtae; Koo, Chiwan; Joung, Yeun-Ho; Choi, Jiyeon

    2018-02-01

    Microfluidics technology which deals with small liquid samples and reagents within micro-scale channels has been widely applied in various aspects of biological, chemical, and life-scientific research. For fabricating microfluidic devices, a silicon-based polymer, PDMS (Polydimethylsiloxane), is widely used in soft lithography, but it has several drawbacks for microfluidic applications. Glass has many advantages over PDMS due to its excellent optical, chemical, and mechanical properties. However, difficulties in fabrication of glass microfluidic devices that requires multiple skilled steps such as MEMS technology taking several hours to days, impedes broad application of glass based devices. Here, we demonstrate a rapid and optical prototyping of a glass microfluidic device by using femtosecond laser assisted selective etching (LASE) and femtosecond laser welding. A microfluidic droplet generator was fabricated as a demonstration of a microfluidic device using our proposed prototyping. The fabrication time of a single glass chip containing few centimeter long and complex-shaped microfluidic channels was drastically reduced in an hour with the proposed laser based rapid and simple glass micromachining and hermetic packaging technique.

  8. Laser-based pedestrian tracking in outdoor environments by multiple mobile robots.

    Science.gov (United States)

    Ozaki, Masataka; Kakimuma, Kei; Hashimoto, Masafumi; Takahashi, Kazuhiko

    2012-10-29

    This paper presents an outdoors laser-based pedestrian tracking system using a group of mobile robots located near each other. Each robot detects pedestrians from its own laser scan image using an occupancy-grid-based method, and the robot tracks the detected pedestrians via Kalman filtering and global-nearest-neighbor (GNN)-based data association. The tracking data is broadcast to multiple robots through intercommunication and is combined using the covariance intersection (CI) method. For pedestrian tracking, each robot identifies its own posture using real-time-kinematic GPS (RTK-GPS) and laser scan matching. Using our cooperative tracking method, all the robots share the tracking data with each other; hence, individual robots can always recognize pedestrians that are invisible to any other robot. The simulation and experimental results show that cooperating tracking provides the tracking performance better than conventional individual tracking does. Our tracking system functions in a decentralized manner without any central server, and therefore, this provides a degree of scalability and robustness that cannot be achieved by conventional centralized architectures.

  9. Close-range laser scanning in forests: towards physically based semantics across scales.

    Science.gov (United States)

    Morsdorf, F; Kükenbrink, D; Schneider, F D; Abegg, M; Schaepman, M E

    2018-04-06

    Laser scanning with its unique measurement concept holds the potential to revolutionize the way we assess and quantify three-dimensional vegetation structure. Modern laser systems used at close range, be it on terrestrial, mobile or unmanned aerial platforms, provide dense and accurate three-dimensional data whose information just waits to be harvested. However, the transformation of such data to information is not as straightforward as for airborne and space-borne approaches, where typically empirical models are built using ground truth of target variables. Simpler variables, such as diameter at breast height, can be readily derived and validated. More complex variables, e.g. leaf area index, need a thorough understanding and consideration of the physical particularities of the measurement process and semantic labelling of the point cloud. Quantified structural models provide a framework for such labelling by deriving stem and branch architecture, a basis for many of the more complex structural variables. The physical information of the laser scanning process is still underused and we show how it could play a vital role in conjunction with three-dimensional radiative transfer models to shape the information retrieval methods of the future. Using such a combined forward and physically based approach will make methods robust and transferable. In addition, it avoids replacing observer bias from field inventories with instrument bias from different laser instruments. Still, an intensive dialogue with the users of the derived information is mandatory to potentially re-design structural concepts and variables so that they profit most of the rich data that close-range laser scanning provides.

  10. Tunable KTA Stokes laser based on stimulated polariton scattering and its intracavity frequency doubling.

    Science.gov (United States)

    Zang, Jie; Cong, Zhenhua; Chen, Xiaohan; Zhang, Xingyu; Qin, Zengguang; Liu, Zhaojun; Lu, Jianren; Wu, Dong; Fu, Qiang; Jiang, Shiqi; Zhang, Shaojun

    2016-04-04

    This paper presents the tunable Stokes laser characteristics of KTiOAsO4 (KTA) crystal based on stimulated polariton scattering (SPS). When the pumping laser wavelength is 1064.2 nm, the KTA Stokes wave can be discontinuously tuned from 1077.9 to 1088.4 nm with four gaps from 1079.0 to 1080.1 nm, from 1080.8 to 1082.8 nm, from 1083.6 to 1085.5 nm, and from 1085.8 to 1086.8 nm. When a frequency doubling crystal LiB3O5 (LBO) is inserted into the Stokes laser cavity, the frequency-doubled wave can be discontinuously tuned from 539.0 to 539.5 nm, from 540.1 to 540.4 nm, from 541.3 to 541.8 nm, from 542.7 to 542.9 nm and from 543.4 to 544.2 nm. With a pumping pulse energy of 130.0 mJ and an output coupler reflectivity of about 30%, the obtained maximum Stokes laser pulse energy at 1078.6 nm is 33.9 mJ and the obtained maximum frequency-doubled laser pulse energy at 543.8 nm is 15.7 mJ. By using the most probably coupled transverse optical modes obtained from the literature, the polariton refractive indexes, and the simplified polariton Sellmeier equations, the polariton dispersion curve is obtained. The formation of the Stokes frequency gaps is explained.

  11. Coordinate measuring system based on microchip lasers for reverse prototyping

    Science.gov (United States)

    Iakovlev, Alexey; Grishkanich, Alexsandr S.; Redka, Dmitriy; Tsvetkov, Konstantin

    2017-02-01

    According to the current great interest concerning Large-Scale Metrology applications in many different fields of manufacturing industry, technologies and techniques for dimensional measurement have recently shown a substantial improvement. Ease-of-use, logistic and economic issues, as well as metrological performance, are assuming a more and more important role among system requirements. The project is planned to conduct experimental studies aimed at identifying the impact of the application of the basic laws of chip and microlasers as radiators on the linear-angular characteristics of existing measurement systems. The project is planned to conduct experimental studies aimed at identifying the impact of the application of the basic laws of microlasers as radiators on the linear-angular characteristics of existing measurement systems. The system consists of a distributed network-based layout, whose modularity allows to fit differently sized and shaped working volumes by adequately increasing the number of sensing units. Differently from existing spatially distributed metrological instruments, the remote sensor devices are intended to provide embedded data elaboration capabilities, in order to share the overall computational load.

  12. Recent advances in ultrafast-laser-based spectroscopy and imaging for reacting plasmas and flames

    Science.gov (United States)

    Patnaik, Anil K.; Adamovich, Igor; Gord, James R.; Roy, Sukesh

    2017-10-01

    Reacting flows and plasmas are prevalent in a wide array of systems involving defense, commercial, space, energy, medical, and consumer products. Understanding the complex physical and chemical processes involving reacting flows and plasmas requires measurements of key parameters, such as temperature, pressure, electric field, velocity, and number densities of chemical species. Time-resolved measurements of key chemical species and temperature are required to determine kinetics related to the chemical reactions and transient phenomena. Laser-based, noninvasive linear and nonlinear spectroscopic approaches have proved to be very valuable in providing key insights into the physico-chemical processes governing reacting flows and plasmas as well as validating numerical models. The advent of kilohertz rate amplified femtosecond lasers has expanded the multidimensional imaging of key atomic species such as H, O, and N in a significant way, providing unprecedented insight into preferential diffusion and production of these species under chemical reactions or electric-field driven processes. These lasers not only provide 2D imaging of chemical species but have the ability to perform measurements free of various interferences. Moreover, these lasers allow 1D and 2D temperature-field measurements, which were quite unimaginable only a few years ago. The rapid growth of the ultrafast-laser-based spectroscopic measurements has been fueled by the need to achieve the following when measurements are performed in reacting flows and plasmas. They are: (1) interference-free measurements (collision broadening, photolytic dissociation, Stark broadening, etc), (2) time-resolved single-shot measurements at a rate of 1-10 kHz, (3) spatially-resolved measurements, (4) higher dimensionality (line, planar, or volumetric), and (5) simultaneous detection of multiple species. The overarching goal of this article is to review the current state-of-the-art ultrafast-laser-based spectroscopic

  13. ‘Green’-synthesized near-infrared PbS quantum dots with silica-PEG dual-layer coating: ultrastable and biocompatible optical probes for in vivo animal imaging

    Science.gov (United States)

    Wang, D.; Qian, J.; Cai, F.; He, S.; Han, S.; Mu, Y.

    2012-06-01

    In this paper, PbS semiconductor quantum dots (QDs) with near-infrared (NIR) photoluminescence were synthesized in oleic acid and paraffin liquid mixture by using an easily handled and ‘green’ approach. Surface functionalization of the QDs was accomplished with a silica and polyethylene glycol (PEG) phospholipid dual-layer coating and the excellent chemical stability of the nanoparticles is demonstrated. We then successfully applied the ultrastable PbS QDs to in vivo sentinel lymph node (SLN) mapping of mice. Histological analyses were also carried out to ensure that the intravenously injected nanoparticles did not produce any toxicity to the organism of mice. These experimental results suggested that our ultrastable NIR PbS QDs can serve as biocompatible and efficient probes for in vivo optical bioimaging and has great potentials for disease diagnosis and clinical therapies in the future.

  14. ‘Green’-synthesized near-infrared PbS quantum dots with silica–PEG dual-layer coating: ultrastable and biocompatible optical probes for in vivo animal imaging

    International Nuclear Information System (INIS)

    Wang, D; Qian, J; Cai, F; He, S; Han, S; Mu, Y

    2012-01-01

    In this paper, PbS semiconductor quantum dots (QDs) with near-infrared (NIR) photoluminescence were synthesized in oleic acid and paraffin liquid mixture by using an easily handled and ‘green’ approach. Surface functionalization of the QDs was accomplished with a silica and polyethylene glycol (PEG) phospholipid dual-layer coating and the excellent chemical stability of the nanoparticles is demonstrated. We then successfully applied the ultrastable PbS QDs to in vivo sentinel lymph node (SLN) mapping of mice. Histological analyses were also carried out to ensure that the intravenously injected nanoparticles did not produce any toxicity to the organism of mice. These experimental results suggested that our ultrastable NIR PbS QDs can serve as biocompatible and efficient probes for in vivo optical bioimaging and has great potentials for disease diagnosis and clinical therapies in the future. (paper)

  15. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    International Nuclear Information System (INIS)

    Gan, Li; Mousen, Cheng; Xiaokang, Li

    2014-01-01

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter

  16. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Li, E-mail: ligan0001@gmail.com; Mousen, Cheng; Xiaokang, Li [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha (China)

    2014-03-15

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

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

    Science.gov (United States)

    Riza, Nabeel A; Amin, M Junaid

    2014-09-01

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

  18. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

    2016-01-01

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a

  19. 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....

  20. The Dawn of Nuclear Photonics with Laser-based Gamma-rays

    International Nuclear Information System (INIS)

    Barty, C.J.

    2011-01-01

    A renaissance in nuclear physics is occurring around the world because of a new kind of incredibly bright, gamma-ray light source that can be created with short pulse lasers and energetic electron beams. These highly Mono-Energetic Gamma-ray (MEGa-ray) sources produce narrow, laser-like beams of incoherent, tunable gamma-rays and are enabling access and manipulation of the nucleus of the atom with photons or so called 'Nuclear Photonics'. Just as in the early days of the laser when photon manipulation of the valence electron structure of the atom became possible and enabling to new applications and science, nuclear photonics with laser-based gamma-ray sources promises both to open up wide areas of practical isotope-related, materials applications and to enable new discovery-class nuclear science. In the United States, the development of high brightness and high flux MEGa-ray sources is being actively pursued at the Lawrence Livermore National Laboratory in Livermore (LLNL), California near San Francisco. The LLNL work aims to create by 2013 a machine that will advance the state of the art with respect to source the peak brightness by 6 orders of magnitude. This machine will create beams of 1 to 2.3 MeV photons with color purity matching that of common lasers. In Europe a similar but higher photon energy gamma source has been included as part of the core capability that will be established at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility in Magurele, Romania outside of Bucharest. This machine is expected to have an end point gamma energy in the range of 13 MeV. The machine will be co-located with two world-class, 10 Petawatt laser systems thus allowing combined intense-laser and gamma-ray interaction experiments. Such capability will be unique in the world. In this talk, Dr. Chris Barty from LLNL will review the state of the art with respect to MEGa-ray source design, construction and experiments and will describe both the ongoing projects