WorldWideScience

Sample records for laser beam characterization

  1. Laser Diode Beam Basics, Manipulations and Characterizations

    CERN Document Server

    Sun, Haiyin

    2012-01-01

    Many optical design technical books are available for many years which mainly deal with image optics design based on geometric optics and using sequential raytracing technique. Some books slightly touched laser beam manipulation optics design. On the other hand many books on laser diodes have been published that extensively deal with laser diode physics with little touching on laser diode beam manipulations and characterizations. There are some internet resources dealing with laser diode beams. However, these internet resources have not covered enough materials with enough details on laser diode beam manipulations and characterizations. A technical book concentrated on laser diode beam manipulations and characterizations can fit in to the open and provide useful information to laser diode users. Laser Diode Beam Basics, Manipulations and  Characterizations is concentrated on the very practical side of the subject, it only discusses the basic physics and mathematics that are necessary for the readers in order...

  2. Laser beam characterization with digital holograms

    CSIR Research Space (South Africa)

    Forbes, A

    2013-04-01

    Full Text Available We show how laser beam characterization may be done in real-time with digital holograms. We illustrate the power of the techniques by applying them to a variety of laser sources, from fibers to solid-state....

  3. Synchronous Characterization of Semiconductor Microcavity Laser Beam

    CERN Document Server

    Wang, Tao

    2015-01-01

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross-section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center and the defects-related spectrum can also be extracted from these high-resolution pictures.

  4. Precision atomic beam density characterization by diode laser absorption spectroscopy

    Science.gov (United States)

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10-5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 104 atoms cm-3. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  5. Characterizing and Optimizing Photocathode Laser Distributions for Ultra-low Emittance Electron Beam Operations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Bohler, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ding, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gilevich, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Huang, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Loos, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ratner, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Vetter, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-12-07

    Photocathode RF gun has been widely used for generation of high-brightness electron beams for many different applications. We found that the drive laser distributions in such RF guns play important roles in minimizing the electron beam emittance. Characterizing the laser distributions with measurable parameters and optimizing beam emittance versus the laser distribution parameters in both spatial and temporal directions are highly desired for high-brightness electron beam operation. In this paper, we report systematic measurements and simulations of emittance dependence on the measurable parameters represented for spatial and temporal laser distributions at the photocathode RF gun systems of Linac Coherent Light Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.

  6. Laser beam welding of Waspaloy: Characterization and corrosion behavior evaluation

    Science.gov (United States)

    Shoja Razavi, Reza

    2016-08-01

    In this work, a study on Nd:YAG laser welding of Waspaloy sheets has been made. Microstructures, phase changes and hardness of the laser joint were investigated using optical microscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and vickers microhardness (HV0.3). Corrosion behavior of the weldment at low temperature in 3.5%wt NaCl solution at room temperature was also investigated using open circuit potential and cyclic potentiodynamic polarization tests. Hot corrosion studies were conducted on samples in the molten salt environment (Na2SO4-60%V2O5) at 900 °C for 50 h. Results indicated that the microstructure of weld zone was mainly dendritic grown epitaxially in the direction perpendicular to the weld boundary and heat transfer. Moreover, the Ti-Mo carbide particles were observed in the structure of the weld zone and base metal. The average size of carbides formed in the base metal (2.97±0.5 μm) was larger than that of the weld zone (0.95±0.2 μm). XRD patterns of the weld zone and base metal showed that the laser welding did not alter the phase structure of the weld zone, being in γ-Ni(Cr) single phase. Microhardness profile showed that the hardness values of the weld zone (210-261 HV) were lower than that of the base metal (323-330 HV). Electrochemical and hot corrosion tests indicated that the corrosion resistance of the weld metal was greater than the base metal in both room and high temperatures.

  7. Functional characterization of planar sensors with active edges using laser and X-ray beam scans

    Energy Technology Data Exchange (ETDEWEB)

    Povoli, M., E-mail: povoli@disi.unitn.it [Dipartimento di Ingegneria e Scienza dell' Informazione, Università di Trento, Via Sommarive, 14, I-38123 Povo di Trento (Italy); INFN, Sezione di Padova (Gruppo Collegato di Trento),Via Sommarive, 14, I-38123 Povo di Trento (Italy); Bagolini, A.; Boscardin, M. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy); Dalla Betta, G.-F. [Dipartimento di Ingegneria e Scienza dell' Informazione, Università di Trento, Via Sommarive, 14, I-38123 Povo di Trento (Italy); INFN, Sezione di Padova (Gruppo Collegato di Trento),Via Sommarive, 14, I-38123 Povo di Trento (Italy); Giacomini, G. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy); Hasi, J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025-7015 (United States); Oh, A. [The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Zorzi, N. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy)

    2013-08-01

    We report on the functional characterization of planar sensors with active edges fabricated at Fondazione Bruno Kessler (FBK), Trento, Italy. The measurements here reported were performed by means of laser and X-ray beam scans mainly focusing on the signal efficiency of the edge region of the devices. Results are very encouraging and show very good sensitivity up to few microns away from the device physical edge.

  8. Characterization and control of femtosecond electron and X-ray beams at free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Christopher

    2012-11-15

    X-ray free-electron lasers (FELs) open up new frontiers in photon science, and in order to take full advantage of these unique accelerator-based light sources, the characterization and control of the femtosecond electron and X-ray beams is essential. Within this cumulative thesis, recent results achieved within the active research field of femtosecond electron and X-ray beams at FELs are reported.The basic principles of X-ray FELs are described, and concepts of longitudinal electron beam diagnostics with femtosecond accuracy are covered. Experimental results obtained with a transverse deflecting structure (TDS) and spectroscopy of coherent terahertz radiation are presented, and the suppression of coherent optical radiation effects, required for diagnostics utilizing a TDS, is demonstrated. Control of the longitudinal phase space by using multiple radio frequencies for longitudinal electron beam tailoring is presented, and a new technique of reversible electron beam heating with two TDSs is described. For the characterization of femtosecond X-ray pulses, a novel method based on dedicated longitudinal phase space diagnostics for electron beams is introduced, and recent measurements with a streaking technique using external terahertz fields are presented.

  9. Characterization Of Real Laser Beam Profiles With Few Parameters For Metallurgical Applications

    Science.gov (United States)

    Merlin, Jacques; Dietz, Jean; Oliveira, Carlos

    1989-01-01

    In first approximation the material induced effects after laser beam interaction are function of the whole transmitted energy and of the local "irradiance" (in W.cm-2) levels and gradients. Consequently 3 informations may be able to describe this beam : carried power, shape and dimensions in the interaction zone. Thus shape and dimensions of a real beam would be simply and universaly described. If we are interested by the induced effects in the straight of the beam axis, 3 parameters are sufficient to describe the beam : the incident power P, an equivalent radius r+, and an axial "spread" factor of energy distribution g(E). These parameters have been mathematically defined but they are also experimentally measurable (in particular from transmitted power through a small aperture or a slit localised in the vicinity of the work zone). The experimental characterization of a 4 kW c.w. CO2 laser (CILAS CI 4000) has been carried out for several powers (between 200 W and 3 kW). When the power increases it has been find that r+ increases and g(E) stays nearly constant in spite of mode evolution. Presently the real-time evaluation of these parameters is investigating. Moreover these 3 parameters can be directly introduced in simplified analytical tridimensional thermal model, and so the behaviour expectation and the working parameters fluctuations effects (for example "mode" changes) become easier. At last this approach may be able to carry out "objective" comparison between the various high power lasers in different laboratories.

  10. Online characterization of laser beam welds by NIR-camera observation

    Science.gov (United States)

    Dorsch, Friedhelm; Braun, Holger; Keßler, Steffen; Pfitzner, Dieter; Rominger, Volker

    2013-02-01

    We have investigated process monitoring of laser beam welding with a TruDisk disk laser to detect process faults. Additionally to monitoring laser beam welding processes by a conventional VIS camera an NIR (near-infrared) camera reveals new information. Our sensor detects thermal radiation between 1100 and 1700 nm from the weld zone, which represents surface temperatures above 1000 K. Using the thermal radiation from the process we can observe all major weld defects without auxiliary illumination. The camera is integrated in a standard TRUMPF welding optics for on-axis observation. A real-time image processing system analyzes the camera images regarding welding irregularities and delivers information to characterize the weld process and its result. Actually, we perform an online passive heat-flow thermography that uses the process itself as the heat source and that probes the thermal attributes of the seam. By this means we can detect regions of bad fusion ("false friends") virtually during the welding process. In addition to conventional thermography we have investigated the use of ratio pyrometry by using to NIR-cameras that observe the process in two different spectral bands. By considering the pixel-per-pixel ratio the influence of surface effects it greatly reduces and we obtain images of the weld zone with an absolute temperature scale. We have compared ratio pyrometry measurements with conventional thermography.

  11. Laser Beam Focus Analyser

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

    2007-01-01

    The quantitative and qualitative description of laser beam characteristics is important for process implementation and optimisation. In particular, a need for quantitative characterisation of beam diameter was identified when using fibre lasers for micro manufacturing. Here the beam diameter limits...... the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...

  12. Characterization of the 46.9-nm soft X-ray laser beam from a capillary discharge

    Science.gov (United States)

    Barnwal, S.; Prasad, Y. B. S. R.; Nigam, S.; Aneesh, K.; Sharma, M. L.; Kushwaha, R. P.; Tripathi, P. K.; Naik, P. A.; Chakera, J. A.; Navathe, C. P.; Gupta, P. D.

    2014-10-01

    Intense lasing had been obtained from argon plasma in the soft X-ray region from a capillary discharge plasma system. Different diagnostics have been used to characterize the lasing properties by recording the temporal, spatial, and spectral profiles of the emission. The divergence measurement indicates that the soft X-ray laser beam has good directionality with a divergence of 3.5 mrad. The spectrum of the laser beam measured using a transmission grating showed intense lasing line at 46.9 nm. Diffraction orders as high as 10th orders were observed. The temporal profile recorded with a vacuum diode showed a distinct laser peak with a pulse width ~1.2 ns (FWHM). In addition, the coherence of the X-ray laser beam was also confirmed from the high-contrast interference fringes (visibility ~85 %) recorded using double slits.

  13. Coherent laser beam combining

    CERN Document Server

    Brignon, Arnaud

    2013-01-01

    Recently, the improvement of diode pumping in solid state lasers and the development of double clad fiber lasers have allowed to maintain excellent laser beam quality with single mode fibers. However, the fiber output power if often limited below a power damage threshold. Coherent laser beam combining (CLBC) brings a solution to these limitations by identifying the most efficient architectures and allowing for excellent spectral and spatial quality. This knowledge will become critical for the design of the next generation high-power lasers and is of major interest to many industrial, environme

  14. Absorption spectroscopy characterization measurements of a laser-produced Na atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Ching, C.H.; Bailey, J.E.; Lake, P.W.; Filuk, A.B.; Adams, R.G.; McKenney, J.

    1996-06-01

    This work describes a pulsed Na atomic beam source developed for spectroscopic diagnosis of a high-power ion diode on the Particle Beam Fusion Accelerator II. The goal is to produce a {approximately} 10{sup 12}-cm{sup {minus}3}-density Na atomic beam that can be injected into the diode acceleration gap to measure electric and magnetic fields from the Stark and Zeeman effects through laser-induced-fluorescence or absorption spectroscopy. A {approximately} 10 ns fwhm, 1.06 {micro}m, 0.6 J/cm{sup 2} laser incident through a glass slide heats a Na-bearing thin film, creating a plasma that generates a sodium vapor plume. A {approximately} 1 {micro}sec fwhm dye laser beam tuned to 5,890 {angstrom} is used for absorption measurement of the Na I resonant doublet by viewing parallel to the film surface. The dye laser light is coupled through a fiber to a spectrograph with a time-integrated CCD camera. A two-dimensional mapping of the Na vapor density is obtained through absorption measurements at different spatial locations. Time-of-flight and Doppler broadening of the absorption with {approximately} 0.1 {angstrom} spectral resolution indicate that the Na neutral vapor temperature is about 0.5 to 2 eV. Laser-induced-fluorescence from {approximately} 1 {times} 10{sup 12}-cm{sup {minus}3} Na I 3s-3p lines observed with a streaked spectrograph provides a signal level sufficient for {approximately} 0.06 {angstrom} wavelength shift measurements in a mock-up of an ion diode experiment.

  15. Characterization of the ELIMED Permanent Magnets Quadrupole system prototype with laser-driven proton beams

    Science.gov (United States)

    Schillaci, F.; Pommarel, L.; Romano, F.; Cuttone, G.; Costa, M.; Giove, D.; Maggiore, M.; Russo, A. D.; Scuderi, V.; Malka, V.; Vauzour, B.; Flacco, A.; Cirrone, G. A. P.

    2016-07-01

    Laser-based accelerators are gaining interest in recent years as an alternative to conventional machines [1]. In the actual ion acceleration scheme, energy and angular spread of the laser-driven beams are the main limiting factors for beam applications and different solutions for dedicated beam-transport lines have been proposed [2,3]. In this context a system of Permanent Magnet Quadrupoles (PMQs) has been realized [2] by INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) researchers, in collaboration with SIGMAPHI company in France, to be used as a collection and pre-selection system for laser driven proton beams. This system is meant to be a prototype to a more performing one [3] to be installed at ELI-Beamlines for the collection of ions. The final system is designed for protons and carbons up to 60 MeV/u. In order to validate the design and the performances of this large bore, compact, high gradient magnetic system prototype an experimental campaign have been carried out, in collaboration with the group of the SAPHIR experimental facility at LOA (Laboratoire d'Optique Appliquée) in Paris using a 200 TW Ti:Sapphire laser system. During this campaign a deep study of the quadrupole system optics has been performed, comparing the results with the simulation codes used to determine the setup of the PMQ system and to track protons with realistic TNSA-like divergence and spectrum. Experimental and simulation results are good agreement, demonstrating the possibility to have a good control on the magnet optics. The procedure used during the experimental campaign and the most relevant results are reported here.

  16. Electron beam properties and impedance characterization for storage rings used for free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dattoli, G.; Mezi, L.; Renieri, A. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Frascati, RM (Italy); Migliorati, M. [Rome Univ. La Sapienza, Rome (Italy). Dipt. di Energetica; Couprie, M.E.; Garzella, D.; Nutarelli, D.; Thomas, C.; De Ninno, G. [Service de Photons, Atomes et Molecules DSM/DRECAM, Gif Sur Yvette (France); Walker, R. [Sincrotrone, Basorizza, TS (Italy)

    2000-07-01

    Good electron beam qualities and stability are the crucial features of Storage Rings dedicated to synchrotron radiation sources or to Free Electron Laser. Most of these characteristics depends on the coupling of the e-beam with the machine environment, which can be in turn modelled in terms of a characteristic impedance, whose absolute value and structure can be used to specify both the stability (longitudinal and transverse) of the beam and its qualities (energy spread, bunch length, peak current ...). In this paper are considered two specific examples of Storage Rings used for FEL operation and analyze their performances by means of semi analytical and numerical methods. The analysis is aimed at clarifying the dependence of beam energy spread and bunch length on beam current and at providing a set of parameters useful for the optimization of Free Electron Laser or synchrotron radiation sources. [Italian] La qualita' di fascio di un anello di accumulazione e la sua stabilita' sono le caratteristiche cruciali di un anello di accumulazione dedicato a sorgenti di Luce di Sincrotrone o al Laser ad Elettroni Liberi. La gran parte di tali caratteristiche dipende dall'accoppiamento del fascio di elettroni con la macchina stessa, tale accoppiamento puo' essere descritto in termini di una impedenza caratteristica, il cui valore assoluto e struttura possono essere utilizzati per specificarne sia la stabilita' del fascio (longitudinale e trasversale) e le sue qualita' (dispersione di energia, lunghezza del pacchetto, corrente di picco ...). In questo articolo si considerano due esempi specifici di anelli di accumulazione utilizzati per l'operazione Laser ed Elettroni Liberi e si analizzano le loro caratteristiche per mezzo di metodi semianalitici e numerici. L'analisi e' essenzialmente dedicata a chiarire la dipendenza della dispersione di energia e della lunghezza del pacchetto dalla corrente media e a fornire un insieme di

  17. Detailed characterization of electron sources yielding first demonstration of European X-ray Free-Electron Laser beam quality

    Directory of Open Access Journals (Sweden)

    F. Stephan

    2010-02-01

    Full Text Available The photoinjector test facility at DESY, Zeuthen site (PITZ, was built to develop and optimize photoelectron sources for superconducting linacs for high-brilliance, short-wavelength free-electron laser (FEL applications like the free-electron laser in Hamburg (FLASH and the European x-ray free-electron laser (XFEL. In this paper, the detailed characterization of two laser-driven rf guns with different operating conditions is described. One experimental optimization of the beam parameters was performed at an accelerating gradient of about 43  MV/m at the photocathode and the other at about 60  MV/m. In both cases, electron beams with very high phase-space density have been demonstrated at a bunch charge of 1 nC and are compared with corresponding simulations. The rf gun optimized for the lower gradient has surpassed all the FLASH requirements on beam quality and rf parameters (gradient, rf pulse length, repetition rate and serves as a spare gun for this facility. The rf gun studied with increased accelerating gradient at the cathode produced beams with even higher brightness, yielding the first demonstration of the beam quality required for driving the European XFEL: The geometric mean of the normalized projected rms emittance in the two transverse directions was measured to be 1.26±0.13  mm mrad for a 1-nC electron bunch. When a 10% charge cut is applied excluding electrons from those phase-space regions where the measured phase-space density is below a certain level and which are not expected to contribute to the lasing process, the normalized projected rms emittance is about 0.9 mm mrad.

  18. Low temperature laser molecular beam epitaxy and characterization of AlGaN epitaxial layers

    Science.gov (United States)

    Tyagi, Prashant; Ch., Ramesh; Kushvaha, S. S.; Kumar, M. Senthil

    2017-05-01

    We have grown AlGaN (0001) epitaxial layers on sapphire (0001) by using laser molecular beam epitaxy (LMBE) technique. The growth was carried out using laser ablation of AlxGa1-x liquid metal alloy under r.f. nitrogen plasma ambient. Before epilayer growth, the sapphire nitradation was performed at 700 °C using r.f nitrogen plasma followed by AlGaN layer growth. The in-situ reflection high energy electron diffraction (RHEED) was employed to monitor the substrate nitridation and AlGaN epitaxial growth. High resolution x-ray diffraction showed wurtzite hexagonal growth of AlGaN layer along c-axis. An absorption bandgap of 3.97 eV is obtained for the grown AlGaN layer indicating an Al composition of more than 20 %. Using ellipsometry, a refractive index (n) value of about 2.19 is obtained in the visible region.

  19. Characterization of Bragg gratings in Al2O3 waveguides fabricated by focused ion beam milling and laser interference lithography

    NARCIS (Netherlands)

    Ay, F.; Bernhardi, Edward; Agazzi, L.; Bradley, J.; Worhoff, Kerstin; Pollnau, Markus; de Ridder, R.M.

    Optical grating cavities in Al2O3 channel waveguides were successfully defined by focused ion beam milling and laser interference lithography. Both methods are shown to be suitable for realizing resonant structures for on-chip waveguide lasers.

  20. Molecular beam epitaxial growth and characterization of Al(Ga)N nanowire deep ultraviolet light emitting diodes and lasers

    Science.gov (United States)

    Mi, Z.; Zhao, S.; Woo, S. Y.; Bugnet, M.; Djavid, M.; Liu, X.; Kang, J.; Kong, X.; Ji, W.; Guo, H.; Liu, Z.; Botton, G. A.

    2016-09-01

    We report on the detailed molecular beam epitaxial growth and characterization of Al(Ga)N nanowire heterostructures on Si and their applications for deep ultraviolet light emitting diodes and lasers. The nanowires are formed under nitrogen-rich conditions without using any metal catalyst. Compared to conventional epilayers, Mg-dopant incorporation is significantly enhanced in nearly strain- and defect-free Al(Ga)N nanowire structures, leading to efficient p-type conduction. The resulting Al(Ga)N nanowire LEDs exhibit excellent performance, including a turn-on voltage of ∼5.5 V for an AlN nanowire LED operating at 207 nm. The design, fabrication, and performance of an electrically injected AlGaN nanowire laser operating in the UV-B band is also presented.

  1. Atomic laser-beam finder.

    Science.gov (United States)

    Viering, Kirsten; Medellin, David; Mo, Jianyong; Raizen, Mark G

    2012-11-05

    We report on an experimental method to align a laser beam to a cloud of atoms trapped in a magneto-optical trap (MOT). We show how balanced lock-in detection leads to a very sensitive method to align the laser beam to the atoms in the plane perpendicular to the propagation direction. This provides a very reliable and fast way of aligning laser beams to atoms trapped in a MOT.

  2. Chromatic energy filter and characterization of laser-accelerated proton beams for particle therapy

    Science.gov (United States)

    Hofmann, Ingo; Meyer-ter-Vehn, Jürgen; Yan, Xueqing; Al-Omari, Husam

    2012-07-01

    The application of laser accelerated protons or ions for particle therapy has to cope with relatively large energy and angular spreads as well as possibly significant random fluctuations. We suggest a method for combined focusing and energy selection, which is an effective alternative to the commonly considered dispersive energy selection by magnetic dipoles. Our method is based on the chromatic effect of a magnetic solenoid (or any other energy dependent focusing device) in combination with an aperture to select a certain energy width defined by the aperture radius. It is applied to an initial 6D phase space distribution of protons following the simulation output from a Radiation Pressure Acceleration model. Analytical formula for the selection aperture and chromatic emittance are confirmed by simulation results using the TRACEWIN code. The energy selection is supported by properly placed scattering targets to remove the imprint of the chromatic effect on the beam and to enable well-controlled and shot-to-shot reproducible energy and transverse density profiles.

  3. Refractive beam shapers for focused laser beams

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2016-09-01

    Focusing of laser radiation is most often used approach in various industrial micromachining applications like scribing, PCB drilling, and is important in scientific researches like laser heating in geophysics experiments with diamond anvil cells (DAC). Control of intensity distribution in focal spot is important task since optimum intensity profiles are rather flat-top, doughnut or "inverse-Gauss" than typical for lasers Gaussian profile. Because of high intensity of modern CW and pulsed lasers it is advisable to use refractive beam shaping optics with smooth optical surfaces providing high radiation resistance. Workable optical solutions can be built on the base of diffraction theory conclusion that flat-top intensity profile in focal plane of a lens is created when input beam has Airy-disk intensity distribution. It is suggested to apply refractive beam shapers converting, with minimum wavefront deformation, Gaussian profile of TEM00 beam to a beam with Airy disk intensity distribution, thereby optimizing conditions of interference near the focal plane of a lens after the beam shaper and providing flat-top, doughnut, "inverse-Gauss" profiles. This approach allows operation with CW and ultra-short pulse lasers, using F-theta lenses and objectives, mirror scanners, provides extended depth of field similar to Rayleigh length of comparable TEM00 beam, easy integration in industrial equipment, simple adjustment procedure and switching between profiles, telescope and collimator implementations. There will be considered design basics of beam shapers, analysis of profile behaviour near focal plane, examples of implementations in micromachining systems and experimental DAC setups, results of profile measurements and material processing.

  4. Spatial-spectral characterization of focused spatially chirped broadband laser beams.

    Science.gov (United States)

    Greco, Michael J; Block, Erica; Meier, Amanda K; Beaman, Alex; Cooper, Samuel; Iliev, Marin; Squier, Jeff A; Durfee, Charles G

    2015-11-20

    Proper alignment is critical to obtain the desired performance from focused spatially chirped beams, for example in simultaneous spatial and temporal focusing (SSTF). We present a simple technique for inspecting the beam paths and focusing conditions for the spectral components of a broadband beam. We spectrally resolve the light transmitted past a knife edge as it was scanned across the beam at several axial positions. The measurement yields information about spot size, M2, and the propagation paths of different frequency components. We also present calculations to illustrate the effects of defocus aberration on SSTF beams.

  5. Beam uniformity of flat top lasers

    Science.gov (United States)

    Chang, Chao; Cramer, Larry; Danielson, Don; Norby, James

    2015-03-01

    Many beams that output from standard commercial lasers are multi-mode, with each mode having a different shape and width. They show an overall non-homogeneous energy distribution across the spot size. There may be satellite structures, halos and other deviations from beam uniformity. However, many scientific, industrial and medical applications require flat top spatial energy distribution, high uniformity in the plateau region, and complete absence of hot spots. Reliable standard methods for the evaluation of beam quality are of great importance. Standard methods are required for correct characterization of the laser for its intended application and for tight quality control in laser manufacturing. The International Organization for Standardization (ISO) has published standard procedures and definitions for this purpose. These procedures have not been widely adopted by commercial laser manufacturers. This is due to the fact that they are unreliable because an unrepresentative single-pixel value can seriously distort the result. We hereby propose a metric of beam uniformity, a way of beam profile visualization, procedures to automatically detect hot spots and beam structures, and application examples in our high energy laser production.

  6. Microstructure fabrication with a CO2 laser system: characterization and fabrication of cavities produced by raster scanning of the laser beam.

    Science.gov (United States)

    Jensen, Martin F; Noerholm, Mikkel; Christensen, Leif Højslet; Geschke, Oliver

    2003-11-01

    In this paper we describe the use of a CO(2) laser for production of cavities and microstructures in poly(methyl methacrylate) (PMMA) by moving the laser beam over the PMMA surface in a raster pattern. The topography of the cavities thus produced is studied using stylus and optical profilometry and scanning electron microscopy (SEM). The microstructures display artifacts from the laser ablation process and we describe how the laser ablation parameters can be optimized in order to minimize these artifacts. Using this technique it is possible to generate structures with a depth from 50 microm and a minimum width of approximately 200 microm up to depth and widths of several mm, governed by the beam size and the laser settings.

  7. Laser beam shaping theory and techniques

    CERN Document Server

    Dickey, Fred M

    2000-01-01

    The mathematical and physical theory of lossless beam shaping; Gaussian beam shaping - diffraction theory and design; geometrical methods; optimization-based techniques for laser shaping optics; beam shaping with diffractive diffusers; multi-aperture beam integration systems; classical (non-laser) methods; current technology of beam profile measurements.

  8. Laser processing with specially designed laser beam

    Science.gov (United States)

    Asratyan, A. A.; Bulychev, N. A.; Feofanov, I. N.; Kazaryan, M. A.; Krasovskii, V. I.; Lyabin, N. A.; Pogosyan, L. A.; Sachkov, V. I.; Zakharyan, R. A.

    2016-04-01

    The possibility of using laser systems to form beams with special spatial configurations has been studied. The laser systems applied had a self-conjugate cavity based on the elements of copper vapor lasers (LT-5Cu, LT-10Cu, LT-30Cu) with an average power of 5, 10, or 30 W. The active elements were pumped by current pulses of duration 80-100 ns. The duration of laser generation pulses was up to 25 ns. The generator unit included an unstable cavity, where one reflector was a special mirror with a reflecting coating. Various original optical schemes used were capable of exploring spatial configurations and energy characteristics of output laser beams in their interaction with micro- and nanoparticles fabricated from various materials. In these experiments, the beam dimensions of the obtained zones varied from 0.3 to 5 µm, which is comparable with the minimum permissible dimensions determined by the optical elements applied. This method is useful in transforming a large amount of information at the laser pulse repetition rate of 10-30 kHz. It was possible to realize the high-precision micromachining and microfabrication of microscale details by direct writing, cutting and drilling (with the cutting width and through-hole diameters ranging from 3 to 100 µm) and produce microscale, deep, intricate and narrow grooves on substrate surfaces of metals and nonmetal materials. This system is used for producing high-quality microscale details without moving the object under treatment. It can also be used for microcutting and microdrilling in a variety of metals such as molybdenum, copper and stainless steel, with a thickness of up to 300 µm, and in nonmetals such as silicon, sapphire and diamond with a thickness ranging from 10 µm to 1 mm with different thermal parameters and specially designed laser beam.

  9. A practical guide to handling laser diode beams

    CERN Document Server

    Sun, Haiyin

    2015-01-01

    This book offers the reader a practical guide to the control and characterization of laser diode beamsLaser diodes are the most widely used lasers, accounting for 50% of the global laser market.  Correct handling of laser diode beams is the key to the successful use of laser diodes, and this requires an in-depth understanding of their unique properties. Following a short introduction to the working principles of laser diodes, the book describes the basics of laser diode beams and beam propagation, including Zemax modeling of a Gaussian beam propagating through a lens.  The core of the book is concerned with laser diode beam manipulations: collimating and focusing, circularization and astigmatism correction, coupling into a single mode optical fiber, diffractive optics and beam shaping, and manipulation of multi transverse mode beams.  The final chapter of the book covers beam characterization methods, describing the measurement of spatial and spectral properties, including wavelength and linewidth meas...

  10. Characterization of laser beam transmission through a High Density Polyethylene (HDPE) plate

    Science.gov (United States)

    Genna, S.; Leone, C.; Tagliaferri, V.

    2017-02-01

    Infrared (IR) light propagation in semicrystalline polymers involves mechanisms such as reflection, transmission, absorption and internal scattering. These different rates determine either the interaction mechanism, either the temperatures reached in the IR heating processes. Consequently, the knowledge of these rates is fundamental in the development of IR heating processes in order to avoid the polymer's damage and to increase the process energy efficiency. Aim of this work is to assess a simple procedure to determine the rates of absorbed, reflected, transmitted and scattered energy in the case of an unfilled High Density Polyethylene (HDPE) plate. Experimental tests were performed by exposing a HDPE plate, 3 mm in thickness, to a diode laser source, working at the fundamental wavelength of 975 nm. The transmitted power was measured by power meter, the reflected one by applying the Beer-Lambert law to sample of different thickness. IR thermal images were adopted to measure the absorbed ratio. The scattered ratio was measured by energetic balance, as difference between the incoming power and the other ratios. Finally, IR thermal images were adopted to measure the scattered ratio and to validate the procedure.

  11. Improvement and characterization of high-reflective and anti-reflective nanostructured mirrors by ion beam assisted deposition for 944 nm high power diode laser

    Science.gov (United States)

    Ghadimi-Mahani, A.; Farsad, E.; Goodarzi, A.; Tahamtan, S.; Abbasi, S. P.; Zabihi, M. S.

    2015-11-01

    Single-layer and multi-layer coatings were applied on the surface of diode laser facets as mirrors. This thin film mirrors were designed, deposited, optimized and characterized. The effects of mirrors on facet passivation and optical properties of InGaAs/AlGaAs/GaAs diode lasers were investigated. High-Reflective (HR) and Anti-Reflective (AR) mirrors comprising of four double-layers of Al2O3/Si and a single layer of Al2O3, respectively, were designed and optimized by Macleod software for 944 nm diode lasers. Optimization of Argon flow rate was studied through Alumina thin film deposition by Ion Beam Assisted Deposition (IBAD) for mirror improvement. The nanostructured HR and AR mirrors were deposited on the front and back facet of the laser respectively, by IBAD system under optimum condition. Atomic Force Microscope (AFM), Vis-IR Spectrophotometer, Field Emission Scanning Electron Microscopy (FESEM) and laser characterization Test (P-I) were used to characterize various properties of mirrors and lasers. AFM images show mirror's root mean square roughness is nearly 1 nm. The Spectrophotometer results of the front facet transmission and the back facet reflection are in good agreement with the simulation results. Optical output power (P) versus driving current (I) characteristics, measured before and after coating the facet, revealed a significant output power enhancement due to optimized AR and HR optical coatings on facets.

  12. A beam branching method for timing and spectral characterization of hard X-ray free-electron lasers

    Directory of Open Access Journals (Sweden)

    Tetsuo Katayama

    2016-05-01

    Full Text Available We report a method for achieving advanced photon diagnostics of x-ray free-electron lasers (XFELs under a quasi-noninvasive condition by using a beam-splitting scheme. Here, we used a transmission grating to generate multiple branches of x-ray beams. One of the two primary diffracted branches (+1st-order is utilized for spectral measurement in a dispersive scheme, while the other (−1st-order is dedicated for arrival timing diagnostics between the XFEL and the optical laser pulses. The transmitted x-ray beam (0th-order is guided to an experimental station. To confirm the validity of this timing-monitoring scheme, we measured the correlation between the arrival timings of the −1st and 0th branches. The observed error was as small as 7.0 fs in root-mean-square. Our result showed the applicability of the beam branching scheme to advanced photon diagnostics, which will further enhance experimental capabilities of XFEL.

  13. Compression of Ultrafast Laser Beams

    Science.gov (United States)

    2016-03-01

    Copyright 2003, AIP Publishing LLC. DOI: http://dx.doi.org/10.1063/1.1611998.) When designing the pulse shaper, the laser beam must completely fill the...Zhang J. Study on the phase modulation characteristics of liquid crystal spatial light modulator. Journal of Physics: Conference Series. 2006;48(1

  14. High energy laser beam dump

    Science.gov (United States)

    Halpin, John

    2004-09-14

    The laser beam dump is positioned in a housing. An absorbing glass plate means is operatively connected to the housing. A heat sync means for extracting heat from the absorbing glass plate means is operatively connected to the housing and operatively connected to the absorbing glass plate means.

  15. Electron beam pumped semiconductor laser

    Science.gov (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  16. Low Energy High Brilliance Beam Characterization

    CERN Document Server

    Bähr, J

    2005-01-01

    Low energy high brilliance beam characterization plays an important role for electron sources and injectors of Free Electron Lasers (FELs) and electron linear accelerators as for example the future ILC project. The topic is discussed basing on solutions of the PITZ facility (PhotoInjector Test facility Zeuthen) which are compared with methods applied at other facilities. The properties of an electron beam produced at a laser-driven rf-gun is mainly influenced also by characteristics of the laser beam and the electron gun itself. Therefore aspects of diagnostics will be also discussed for the laser, laser beam line and gun as well. The main properties of the electron beam are transverse and longitudinal phase space and charge as well. The measurement of transverse beam size and position, transverse emittance, charge, beam current, and longitudinal phase space will be discussed in detail. The measurements of the transverse emittance at PITZ is based on a single slit method. The measurement of the longitudinal p...

  17. Quality factor of aberrated gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2010-09-01

    Full Text Available A model is used to calculate the beam quality factor of a laser beam from Zernike coefficients. It is tested by programming aberration coefficients on a laser beam and measuring the beam quality using a Shack-Hartmann wavefront sensor. The two show...

  18. Experimental Characterization Of The Saturating, Near Infrared, Self-amplified Spontaneous Emission Free Electron Laser Analysis Of Radiation Properties And Electron Beam Dynamics

    CERN Document Server

    Murokh, A

    2002-01-01

    In this work, the main results of the VISA experiment (Visible to Infrared SASE Amplifier) are presented and analyzed. The purpose of the experiment was to build a state-of-the-art single pass self-amplified spontaneous emission (SASE) free electron laser (FEL) based on a high brightness electron beam, and characterize its operation, including saturation, in the near infrared spectral region. This experiment was hosted by Accelerator Test Facility (ATF) at Brookhaven National Laboratory, which is a users facility that provides high brightness relativistic electron beams generated with the photoinjector. During the experiment, SASE FEL performance was studied in two regimes: a long bunch, lower gain operation; and a short bunch high gain regime. The transition between the two conditions was possible due to a novel bunch compression mechanism, which was discovered in the course of the experiment. This compression allowed the variation of peak current in the electron beam before it was launched into the 4-m VISA...

  19. Adhesion strength characterization of PVDF/HA coating on cp Ti surface modified by laser beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, A.A., E-mail: aantunesr@yahoo.com.br [Department of Polymer Technology, School of Chemical Engineering, State University of Campinas, UNICAMP, P.O. Box 6066, Campinas, SP 13083-970 (Brazil); Vaz, L.G. [Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP, P.O. Box 331, Araraquara, SP 14801-903 (Brazil); Guastaldi, A.C. [Department of Physical Chemistry, Institute of Chemistry, UNESP, P.O. Box 331, Araraquara, SP 14801-970 (Brazil); Campos, J.S.C. [Department of Polymer Technology, School of Chemical Engineering, State University of Campinas, UNICAMP, P.O. Box 6066, Campinas, SP 13083-970 (Brazil)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Titanium substrates are superficially treated by laser beam irradiation. Black-Right-Pointing-Pointer Treated titanium substrates are coated with {alpha}-PVDF and {alpha}-PVDF/HA films. Black-Right-Pointing-Pointer Three-point bending test is used to assess the adhesion strength of coatings. Black-Right-Pointing-Pointer The coatings show good physical adhesion on treated titanium substrates. Black-Right-Pointing-Pointer Three-point bending test appears as an alternative for measuring adhesion strength. - Abstract: Up to the moment, there is no standardized test for measuring the adhesion strength of polymeric coatings on titanium substrate modified by laser beam irradiation. The present work aimed to assess the adhesion strength of polyvinylidene fluoride ({alpha}-PVDF)/hydroxyapatite (HA) composite coating on commercially pure titanium ({alpha}-cp Ti) substrate surface modified by laser beam irradiation, using the three-point bending test. The preparation of coating was carried out by mixing {alpha}-PVDF pellets dissolved in dimethylacetamide (DMA) with HA/DMA emulsion. The mixture was poured onto the {alpha}-cp Ti sample and left to dry in an oven. Commercially pure titanium plates were coated with {alpha}-PVDF/HA composite film, in proportions of 100/00 (PVDF) and 60/40 (PVDF/HA) in weight. The Ti-PVDF/HA samples were subjected to the three-point bending test and analyzed by scanning electron microscopy. According to the results, PVDF and PVDF/HA coatings showed a good adhesion strength on {alpha}-cp Ti surface, since no detachment was observed.

  20. Ion beam and complementary SEM and XRD characterization of YBa{sub 2}Cu{sub 3}O{sub 7-x} films obtained by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Branescu, Maria [National Institute for R and D of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania)]. E-mail: maria_branescu@yahoo.com; Thome, L. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, 91406 Orsay Cedex (France); Pantelica, D. [' Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest (Romania); Ward, I. [CEA, 810 Kifer Road, Sunnyvale, CA 94086 (United States); Vailionis, A. [Stanford University, Stanford, CA 94305 (United States); Ionescu, P. [' Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest (Romania)

    2006-08-15

    We report two ion beam analysis techniques, elastic recoil detection analysis (ERDA) and Rutherford backscattering (RBS), to characterize YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films, obtained in situ by pulsed laser deposition (PLD). Initially, ERDA measurements were performed on a thin film to evaluate the PLD rate. RBS measurements correlated with complementary scanning electron microscopy and X-ray diffraction measurements were performed afterwards on a good quality thick YBCO film to determine its stoichiometry, thickness, crystalline structure and surface morphology.

  1. Coaxial combination of coherent laser beams

    Institute of Scientific and Technical Information of China (English)

    Hongcheng Dong; Xiao Li; Chaoyang Wei; Hongbo He; Yuanan Zhao; Jianda Shao; Zhengxiu Fan

    2009-01-01

    @@ Based on polarization state conversion, a technique for coaxially coherent combination of laser beams is introduced.Laser beams can be coaxially coupled into one beam with high combination efficiency and perfect beam quality.A polarized laser beam combination system based on master oscillator power amplifier (MOPA) configuration is developed and the efficiencies of both unit combination and the whole system are investigated.In the experiment of combining four beams with single longitudinal mode, a combination efficiency of 85.3% is achieved.It can be further enhanced by improving the stability of experimental environment and the quality of optical and mechanical components.

  2. Full characterization of a high-power semiconductor disk laser beam with simultaneous capture of optimally sized focus and farfield.

    Science.gov (United States)

    Borgentun, Carl; Bengtsson, Jörgen; Larsson, Anders

    2011-04-20

    We report on a beam characterization method that is based on the simultaneous measurement of the focus field and the farfield, thus avoiding problems with beam fluctuations during the measurement. By using reflections from both sides of a planoconvex lens, the method implements two branches of an optical system working simultaneously. Also, by letting the planoconvex lens be antireflection treated, and by allowing for both of the reflected fields to fill large and approximately equal areas on a camera detector array, the method significantly lowers the intensity onto the detector array, thus minimizing the need for additional disturbing attenuation filters to avoid camera saturation. In the numerical retrieval of the phase distribution, based on the measured intensity distributions of the focus and farfield, iterative propagation between the two branches is performed. The phase retrieval uses the two-step algorithm for the numerical field propagation conveniently providing an arbitrary choice of sampling distance in each plane.

  3. Difraction spectrometry by laser beams

    Directory of Open Access Journals (Sweden)

    Frías, M.

    1988-12-01

    Full Text Available The advances in laser technology have permitted the development of numerous applications, in particular diffraction spectrometry by laser beams for the determination of the distribution curve of the particle sizes of different materials; this permits one to obtain the distribution of particle size in both wet and dry materials. In the present paper a brief description of the technique and its principles is offered. The results obtained with different materials-limestone clay, gypsum, Portland cement and siliceous materials are given.

    Los avances en la tecnología laser han permitido el desarrollo de múltiples aplicaciones, en concreto la espectrometría de difracción de rayos laser para la determinación de la curva de distribución del tamaño de partícula de diferentes materiales, y que permite la obtención de la misma tanto en seco como en húmedo. En este trabajo se hace una descripción breve de la técnica y de sus fundamentos. Se presentan resultados con diferentes materiales: caliza, arcilla, yeso, cemento Portland y materiales silíceos.

  4. Experimental investigation and metallographic characterization of fiber laser beam welding of Ti-6Al-4V alloy using response surface method

    Science.gov (United States)

    Kumar, Chandan; Das, Manas; Paul, C. P.; Singh, B.

    2017-08-01

    In the present study, experimental investigations of fiber-laser-beam-welding of 5 mm thick Ti-6Al-4V alloy are carried out based on statistical design of experiments. The relationship between the process parameters such as welding power, welding speed, and defocused position of the laser beam with the output responses such as width of the fusion zone, size of the heat affected zone, and fusion zone area are established in terms of regression models. Also, the most significant process parameters and their optimum ranges are identified and their percentage contributions on output responses are calculated. It is observed that welding power and speed plays the major role for full penetration welding. Also, welding power shows direct effect whereas welding speed shows the inverse effect on the output responses. The bead geometry is influenced by the defocused position of the laser beam due to the change in power density on the workpiece surface. However, overall fusion zone area is unaffected. Mechanical characterization of the welded samples such as microstructural analysis, hardness, and tensile tests are conducted. It is noticed that the hardness value of the FZ is higher than the HAZ and BM zone due to the difference in cooling rate during welding which promotes the formation of α‧ martensitic phase in the FZ. Also, an average hardness value in the FZ is compared for two different defocusing positions (i.e. 1 and 2 mm). It is found that hardness value is higher for 1 mm defocused position than 2 mm due the decrement in grain size below a critical range at 2 mm defocused position. The ultimate tensile strength and % elongation of the welded samples are degraded as compared to BM which can be further improved by post heat treatment.

  5. Laser Beam Duct Pressure Controller System.

    Science.gov (United States)

    the axial flow of a conditioning gas within the laser beam duct, by matching the time rate of change of the pressure of the flowing conditioning gas...to the time rate of change of the pressure in the cavity of an operably associated laser beam turret.

  6. Beam profile analyzer for CO2 lasers

    Directory of Open Access Journals (Sweden)

    Rubén López

    2015-12-01

    Full Text Available The development of an optoelectronic system to analyze the beam intensity profile of CO2 lasers is presented herein. The device collects the beam profile with a LiTaO3 pyroelectric detector and uses a sampling technique based on the acquisition of horizontal sections at different levels. The digital signal processing includes subroutines that drop down two dimensional and three dimensional beam profile displays to determine the laser beam parameters of optical power, peak pixel location, centroid location and width of the laser beam, with algorithms based on the ISO 11146 standard. With the systematic calibration of the analyzer was obtained in the measurement of power an error under 5%, for a 20–200 W range and an error under 1.6% for spatial measurements of a TEM00 laser. By design, the analyzer can be used during the laser process.

  7. Generation of a hollow laser beam by a multimode fiber

    Institute of Scientific and Technical Information of China (English)

    Hongyu Ma; Huadong Cheng; Wenzhuo Zhang; Liang Liu; Yuzhu Wang

    2007-01-01

    A simple method to generate a hollow laser beam by multimode fiber is reported. A dark hollow laser beam is generated from a multimode fiber and the dependence of the output beam profile on the incident angle of laser beam is analyzed. The results show that this hollow laser beam can be used to trap and guide cold atoms.

  8. Coherence delay augmented laser beam homogenizer

    Science.gov (United States)

    Rasmussen, P.; Bernhardt, A.

    1993-06-29

    The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

  9. Beam combining of quantum cascade laser arrays.

    Science.gov (United States)

    Lee, Benjamin G; Kansky, Jan; Goyal, Anish K; Pflügl, Christian; Diehl, Laurent; Belkin, Mikhail A; Sanchez, Antonio; Capasso, Federico A

    2009-08-31

    Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, we obtained the absorption spectrum of isopropanol at a distance of 6 m from the laser array.

  10. Modeling beam propagation and frequency conversion for the beamlet laser

    Energy Technology Data Exchange (ETDEWEB)

    Auerbach, J.M.

    1996-06-01

    The development of the Beamlet laser has involved extensive and detailed modeling of laser performance and beam propagation to: (1) predict the performance limits of the laser, (2) select system configurations with higher performance, (3) analyze experiments and provide guidance for subsequent laser shots, and (4) design optical components and establish component manufacturing specifications. In contrast to modeling efforts of previous laser systems such as Nova, those for Beamlet include as much measured optical characterization data as possible. This article concentrates on modeling of beam propagation in the Beamlet laser system, including the frequency converter, and compares modeling predictions with experimental results for several Beamlet shots. It briefly describes the workstation-based propagation and frequency conversion codes used to accomplish modeling of the Beamlet.

  11. Space Optical Communications Using Laser Beam Amplification

    Science.gov (United States)

    Agrawal, Govind

    2015-01-01

    The Space Optical Communications Using Laser Beam Amplification (SOCLBA) project will provide a capability to amplify a laser beam that is received in a modulating retro-reflector (MRR) located in a satellite in low Earth orbit. It will also improve the pointing procedure between Earth and spacecraft terminals. The technology uses laser arrays to strengthen the reflected laser beam from the spacecraft. The results of first year's work (2014) show amplification factors of 60 times the power of the signal beam. MMRs are mirrors that reflect light beams back to the source. In space optical communications, a high-powered laser interrogator beam is directed from the ground to a satellite. Within the satellite, the beam is redirected back to ground using the MMR. In the MMR, the beam passes through modulators, which encode a data signal onto the returning beam. MMRs can be used in small spacecraft for optical communications. The SOCLBA project is significant to NASA and small spacecraft due to its application to CubeSats for optical data transmission to ground stations, as well as possible application to spacecraft for optical data transmission.

  12. Micro-beam XRF localization by a laser beam

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A new method for micro-beam XRF localization is presented. A laserbeam along with an incident X-ray hits on the surface of a sample. The micro region onthe sample that reached by X-ray beam can be localized by means of thevisible spot of the laser beam. This method is suitable for X-ray microprobesusing anX-ray tube or synchrotron radiation as excitation sources.

  13. Dual-Beam Atom Laser Driven by Spinor Dynamics

    Science.gov (United States)

    Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David

    2007-01-01

    An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.

  14. Fractional laser photothermolysis using Bessel beams.

    Science.gov (United States)

    Mignon, Charles; Rodriguez, Aura Higuera; Palero, Jonathan A; Varghese, Babu; Jurna, Martin

    2016-12-01

    Fractional photothermolysis uses lasers to generate a pattern of microscopic columnar thermal lesions within the skin stimulating collagen remodeling. In this paper we investigate the use of Bessel beams as an alternative to conventional Gaussian beams in creating laser photothermal lesions of different aspect ratios in skin. We show for the first time the improved photothermal lesion depth-to-diameter aspect ratio using Bessel beams in ex vivo human skin as well as in numerical simulations using electric field Monte Carlo photon transport, finite difference methods and Arrhenius model. Bessel beams allow the creation of deep and narrow thermal lesions necessary for improved efficacy in fractional photothermolysis.

  15. Generalized beam quality factor of aberrated truncated Gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2011-07-01

    Full Text Available factor of aberrated truncated Gaussian laser beams Cosmas Mafusire1,2 and Andrew Forbes1,2,* 1Council for Scientific and Industrial Research National Laser Centre, P.O. Box 395, Pretoria, South Africa 2School of Physics, University of Kwa... is verified experimentally by implementing aberrations as digital holograms in the laboratory. ? 2011 Optical Society of America OCIS codes: 140.3295, 080.1005, 120.5050. 1. INTRODUCTION The laser beam quality factor (M2) is a useful parameter...

  16. 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.

  17. Laser cooling of a stored ion beam: A first step towards crystalline beams

    Energy Technology Data Exchange (ETDEWEB)

    Hangst, J.S.

    1992-09-01

    This report discusses: a brief introduction to storage rings; crystalline beams; laser cooling of ion beams; description of astrid-the experimental setup; first experiments with lithium 7 ion beam; experiments with erbium 166 ion beams; further experiments with lithium 7 ion beams; beam dynamics, laser cooling,and crystalline beams in astrid; possibilities for further study in astrid.

  18. Wavelength-independent laser beam shaping

    CSIR Research Space (South Africa)

    Degama, MP

    2010-07-01

    Full Text Available , (2002). [10] Romero, L., A. and Dickey, F., M., “Lossless laser beam shaping,” J. Opt. Soc. Am. A, 13, 751-760, (1996). [11] Dickey, F., M. and Holswade, S., C., “Gaussian laser beam profile shaping.” Opt. Eng., 35(11), 3285-3295, (1996). [12] www.cvilaser.com/Common/PDFs/Index_of_Refraction.pdf. ...

  19. Laser wakefield acceleration of polarized electron beams

    Science.gov (United States)

    Pugacheva, D. V.; Andreev, N. E.; Cros, B.

    2016-11-01

    The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

  20. Multimode laser beam analyzer instrument using electrically programmable optics.

    Science.gov (United States)

    Marraccini, Philip J; Riza, Nabeel A

    2011-12-01

    Presented is a novel design of a multimode laser beam analyzer using a digital micromirror device (DMD) and an electronically controlled variable focus lens (ECVFL) that serve as the digital and analog agile optics, respectively. The proposed analyzer is a broadband laser characterization instrument that uses the agile optics to smartly direct light to the required point photodetectors to enable beam measurements of minimum beam waist size, minimum waist location, divergence, and the beam propagation parameter M(2). Experimental results successfully demonstrate these measurements for a 500 mW multimode test laser beam with a wavelength of 532 nm. The minimum beam waist, divergence, and M(2) experimental results for the test laser are found to be 257.61 μm, 2.103 mrad, 1.600 and 326.67 μm, 2.682 mrad, 2.587 for the vertical and horizontal directions, respectively. These measurements are compared to a traditional scan method and the results of the beam waist are found to be within error tolerance of the demonstrated instrument.

  1. Controlling Second Harmonic Efficiency of Laser Beam Interactions

    Science.gov (United States)

    Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

    2011-01-01

    A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

  2. Vertical laser beam propagation through the troposphere

    Science.gov (United States)

    Minott, P. O.; Bufton, J. L.; Schaefer, W. H.; Grolemund, D. A.

    1974-01-01

    The characteristics of the earth's atmosphere and its effects upon laser beams was investigated in a series of balloon borne, optical propagation experiments. These experiments were designed to simulate the space to ground laser link. An experiment to determine the amplitude fluctuation, commonly called scintillation, caused by the atmosphere was described.

  3. Airy beams from a microchip laser

    CERN Document Server

    Longhi, Stefano

    2011-01-01

    It is theoretically shown that an end-pumped microchip laser formed by a thin laser crystal with plane-plane but slightly tilted facets can emit, under appropriate pumping conditions and near a crystal edge, a truncated self-accelerating Airy output beam.

  4. Investigations in CO2 laser beam caustics measuring techniques

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Bagger, Claus

    2004-01-01

    The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 which are describing test methods for laser beam parameters have been approved.......The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 which are describing test methods for laser beam parameters have been approved....

  5. Investigations in CO2 laser beam caustics measuring techniques

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Bagger, Claus

    2004-01-01

    The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 which are describing test methods for laser beam parameters have been approved.......The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 which are describing test methods for laser beam parameters have been approved....

  6. Flat profile laser beam shaper

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Todd R.

    2017-09-12

    A system for shaping a beam comprises an emitter for emitting coherent electromagnetic radiation. Birefringent displacers are configured between the emitter and a target wherein the at least two birefringent displacers split the coherent electromagnetic radiation into a plurality of coherent parallel beams of electromagnetic radiation thereby producing a shaped wave front of the coherent parallel beams of electromagnetic radiation.

  7. Laser Micro-beam Manipulation System for Cells

    Institute of Scientific and Technical Information of China (English)

    孟祥旺; 李岩; 张书练; 张志诚; 赵南明

    2002-01-01

    This paper introduces a laser micro-beam system for cells manipulation. The laser micro-beam system comprises a laser scissors and a laser tweezers, which are focused by a Nd∶YAG laser and a He-Ne laser through a microscope objective, respectively. Not only the overall design of the laser micro-beam system is discussed, but also the design and choice of the critical components. A laser micro-beam system was constructed and anticipated experiment results were gained. Yeast cells can be successfully manipulated with the laser tweezers. Chromosomes can be successfully incised with the laser scissors.

  8. An online, energy-resolving beam profile detector for laser-driven proton beams

    Science.gov (United States)

    Metzkes, J.; Zeil, K.; Kraft, S. D.; Karsch, L.; Sobiella, M.; Rehwald, M.; Obst, L.; Schlenvoigt, H.-P.; Schramm, U.

    2016-08-01

    In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ˜4 mm and the detector can resolve proton beam profiles for up to 9 proton threshold energies. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energy can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source, as well as the first detector application at a laser-driven proton source.

  9. Linear quadratic regulator for laser beam shaping

    Science.gov (United States)

    Escárate, Pedro; Agüero, Juan C.; Zúñiga, Sebastián; Castro, Mario; Garcés, Javier

    2017-07-01

    The performance of an adaptive optics system depends on multiple factors, including the quality of the laser beam before being projected to the mesosphere. In general, cumbersome procedures are required to optimize the laser beam in terms of amplitude and phase. However, aberrations produced by the optics of the laser beam system are still detected during the operations due to, for example, uncertainty in the utilized models. In this paper we propose the use of feedback to overcome the presence of model uncertainty and disturbances. In particular we use a Linear Quadratic Regulator (LQR) for closed loop laser beam shaping using a setup of two deformable mirrors. The proposed method is studied and simulated to provide an automatic optimization of the Amplitude of the laser beam. The performance of the LQR control algorithm is evaluated via numerical simulations using the root mean square error (RMSE). The results show an effective amplitude correction of the laser system aberrations after 20 iterations of the algorithm, a RMSE less than 0.7 was obtained, with about 140 actuators per mirror and a separation of z=3 [m] among the mirrors.

  10. Transmission Of Power Via Combined Laser Beams

    Science.gov (United States)

    Kwon, Jin H.; Lee, Ja H.

    1992-01-01

    Laser Diode Array (LDA) appears to be most efficient means of transferring power from Earth to satellites and between satellites, in terms of mass and size, of various laser configurations. To form large-scale-array amplifier (LSAA), element LDA's must generate well-defined diffraction-limited beams. Coherent matching of phases among LDA's enables system to generate good beam pattern in far field over thousands of kilometers. By passing beam from master laser through number of LDA amplifiers simultaneously, one realizes coherence among amplified output beams. LSAA used for transmission of power with efficiency of approximately 80 percent into receiver of moderate size at 5,000 km. Also transmits data at high rates by line-of-sight rather than fiber optics.

  11. Profiling of micrometer-sized laser beams in restricted volumes

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Nielsen, Otto; Thorsen, Aske

    2012-01-01

    We present a method for determining the three-dimensional intensity distribution of directed laser radiation with micrometer resolution in restricted volumes. Our method is based on the incoupling and guiding properties of optical fibers, with the current version requiring only a few hundred...... micrometers across the measuring volume. We characterize the performance of the method and experimentally demonstrate profiling of micrometer-sized laser beams. We discuss the limiting factors and routes toward a further increase of the resolution and beam profiling in even more restricted volumes. Finally...

  12. Synchronization and Characterization of an Ultra-Short Laser for Photoemission and Electron-Beam Diagnostics Studies at a Radio Frequency Photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Timothy; Ruan, Jinhao; Piot, Philippe; Lumpkin, Alex

    2012-03-01

    A commercially-available titanium-sapphire laser system has recently been installed at the Fermilab A0 photoinjector laboratory in support of photoemission and electron beam diagnostics studies. The laser system is synchronized to both the 1.3-GHz master oscillator and a 1-Hz signal use to trigger the radiofrequency system and instrumentation acquisition. The synchronization scheme and performance are detailed. Long-term temporal and intensity drifts are identified and actively suppressed to within 1 ps and 1.5%, respectively. Measurement and optimization of the laser's temporal profile are accomplished using frequency-resolved optical gating.

  13. Synchronization and Characterization of an Ultra-Short Laser for Photoemission and Electron-Beam Diagnostics Studies at a Radio Frequency Photoinjector

    CERN Document Server

    Maxwell, Timothy; Piot, Philippe; Lumpkin, Alex

    2012-01-01

    A commercially-available titanium-sapphire laser system has recently been installed at the Fermilab A0 photoinjector laboratory in support of photoemission and electron beam diagnostics studies. The laser system is synchronized to both the 1.3-GHz master oscillator and a 1-Hz signal use to trigger the radiofrequency system and instrumentation acquisition. The synchronization scheme and performance are detailed. Long-term temporal and intensity drifts are identified and actively suppressed to within 1 ps and 1.5%, respectively. Measurement and optimization of the laser's temporal profile are accomplished using frequency-resolved optical gating.

  14. Laser power beaming for satellite applications

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, H.W.

    1993-09-22

    A serious consideration of laser power beaming for satellite applications appears to have grown out of a NASA mission analysis for transmitting power to lunar bases during the two week dark period. System analyses showed that laser power beaming to the moon in conjunction with efficient, large area solar cell collection panels, were an attractive alternative to other schemes such as battery storage and nuclear generators, largely because of the high space transportation costs. The primary difficulty with this scheme is the need for very high average power visible lasers. One system study indicated that lasers in excess of 10 MW at a wavelength of approximately 850 nm were required. Although such lasers systems have received much attention for military applications, their realization is still a long term goal.

  15. Kagome fiber based industrial laser beam delivery

    Science.gov (United States)

    Maurel, M.; Gorse, A.; Beaudou, B.; Lekiefs, Q.; Chafer, M.; Debord, B.; Gérôme, F.; Benabid, F.

    2017-02-01

    We report on a Hollow Core-Photonic Crystal Fiber (HC-PCF) based high power ultra-short pulse laser beam delivery system (GLO-BDS) that combines ease-of-use, high laser-coupling efficiency, robustness and industrial compatible cabling. The GLO-BDS comprises a pre-aligned laser-injection head, a sheath cable protected HC-PCF and a modular fiber-output head. It enables fiber-core gas loading and evacuation in a hermetic fashion. 5 m long GLO-BDS were demonstrated for Yb USP laser, Ti:Sapphire laser and frequency-doubled Yb USP laser. They all exhibit a transmission coefficient larger than 80%, and a laser output profile close to single mode (M2 <1.3).

  16. Method and apparatus for laser-controlled proton beam radiology

    Science.gov (United States)

    Johnstone, Carol J.

    1998-01-01

    A proton beam radiology system provides cancer treatment and proton radiography. The system includes an accelerator for producing an H.sup.- beam and a laser source for generating a laser beam. A photodetachment module is located proximate the periphery of the accelerator. The photodetachment module combines the H.sup.- beam and laser beam to produce a neutral beam therefrom within a subsection of the H.sup.- beam. The photodetachment module emits the neutral beam along a trajectory defined by the laser beam. The photodetachment module includes a stripping foil which forms a proton beam from the neutral beam. The proton beam is delivered to a conveyance segment which transports the proton beam to a patient treatment station. The photodetachment module further includes a laser scanner which moves the laser beam along a path transverse to the cross-section of the H.sup.- beam in order to form the neutral beam in subsections of the H.sup.- beam. As the scanning laser moves across the H.sup.- beam, it similarly varies the trajectory of the proton beam emitted from the photodetachment module and in turn varies the target location of the proton beam upon the patient. Intensity modulation of the proton beam can also be achieved by controlling the output of the laser.

  17. Phoenix's Laser Beam in Action on Mars

    Science.gov (United States)

    2008-01-01

    [figure removed for brevity, see original site] Click on image to view the animation The Surface Stereo Imager camera aboard NASA's Phoenix Mars Lander acquired a series of images of the laser beam in the Martian night sky. Bright spots in the beam are reflections from ice crystals in the low level ice-fog. The brighter area at the top of the beam is due to enhanced scattering of the laser light in a cloud. The Canadian-built lidar instrument emits pulses of laser light and records what is scattered back. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  18. Laser beam shaping and packaging system

    Science.gov (United States)

    Luo, Daxin; Zhao, Baiqin

    2012-10-01

    This paper presents a semiconductor laser beam shaping system, that can collimate the irradiance profile effectively and package the laser diode(LD) at the same time. Due to the semiconductor LD is a kind of line source, a particular ellipsoidal lens is designed after both the fast-axis and the slow-axis of the laser beam analyzed. Geometrical optics analysis based on the ray tracing method is done and the formulas to calculate the shape of the lens are given. Both the theoretical and experimental result show that the laser beam system works effectively; the divergence angle is reduced to less than 0.5 degree in the fast-axial direction and 1.8 degree in the slow-axial direction. In addition, it is the same process that makes the laser beam shaper and packages the LD by using epoxy resin, which simplifies the manufacturing process and reduces the LD volume greatly. Because of the advantages of small volume, low-cost, high rigidity and easy fabrication, the shaper is of great value in the field of semiconductor LD applications.

  19. ELIMED, future hadrontherapy applications of laser-accelerated beams

    Energy Technology Data Exchange (ETDEWEB)

    Cirrone, Giuseppe A.P. [INFN-LNS, Catania (Italy); Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Carpinelli, Massimo [INFN Sezione di Caglari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Cuttone, Giacomo; Gammino, Santo [INFN-LNS, Catania (Italy); Bijan Jia, S. [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Korn, Georg [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Maggiore, Mario [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); INFN-LNL, Legnaro (Italy); Manti, Lorenzo [University Federico II of Naples, Dip.to di Scienze Fisiche, Naples (Italy); Margarone, Daniele; Prokupek, Jan [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Renis, Marcella [University of Catania, Catania (Italy); Romano, Francesco [INFN-LNS, Catania (Italy); Centro Studi e Ricerche “E. Fermi”, Roma (Italy); Schillaci, Francesco, E-mail: francesco.schillaci@eli-beams.eu [INFN-LNS, Catania (Italy); Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Tomasello, Barbara [University of Catania, Catania (Italy); Torrisi, Lorenzo [INFN-LNS, Catania (Italy); Dip. to di Fisica, University of Messina, Messina (Italy); Tramontana, Antonella [INFN-LNS, Catania (Italy); Velyhan, Andriy [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic)

    2013-12-01

    Laser-ion acceleration has recently gained a great interest as an alternative to conventional and more expensive acceleration techniques. These ion beams have desirable qualities such as small source size, high luminosity and small emittance to be used in different fields as Nuclear Physics, Medical Physics, etc. This is very promising specially for the future perspective of a new concept of hadrontherapy based on laser-based devices could be developed, replacing traditional accelerating machines. Before delivering laser-driven beams for treatments they have to be handled, cleaned from unwanted particles and characterized in order to have the clinical requirements. In fact ion energy spectra have exponential trend, almost 100% energy spread and a wide angular divergence which is the biggest issue in the beam transport and, hence, in a wider use of this technology. In order to demonstrate the clinical applicability of laser-driven beams new collaboration between ELI-Beamlines project researchers from Prague (Cz) and a INFN-LNS group from Catania (I) has been already launched and scientists from different countries have already express their will in joining the project. This cooperation has been named ELIMED (MEDical application at ELIBeamlines) and will take place inside the ELI-Beamlines infrastructure located in Prague. This work describes the schedule of the ELIMED project and the design of the energy selector which will be realized at INFN-LNS. The device is an important part of the whole transport beam line which will be realised in order to make the ion beams suitable for medical applications. -- Highlights: •We simulated the energy selection system, in order to optimize the device. •We simulated the experimental setup for the run at the TARANIS laser system. •We studied the efficiency of the devise for a proton beam with an uniform energy spectrum.

  20. Beam shaping for laser initiated optical primers

    Science.gov (United States)

    Lizotte, Todd E.

    2008-08-01

    Remington was one of the first firearm manufacturing companies to file a patent for laser initiated firearms, in 1969. Nearly 40 years later, the development of laser initiated firearms has not become a mainstream technology in the civilian market. Requiring a battery is definitely a short coming, so it is easy to see how such a concept would be problematic. Having a firearm operate reliably and the delivery of laser energy in an efficient manner to ignite the shock-sensitive explosive primer mixtures is a tall task indeed. There has been considerable research on optical element based methods of transferring or compressing laser energy to ignite primer charges, including windows, laser chip primers and various lens shaped windows to focus the laser energy. The focusing of laser light needs to achieve igniting temperatures upwards of >400°C. Many of the patent filings covering this type of technology discuss simple approaches where a single point of light might be sufficient to perform this task. Alternatively a multi-point method might provide better performance, especially for mission critical applications, such as precision military firearms. This paper covers initial design and performance test of the laser beam shaping optics to create simultaneous multiple point ignition locations and a circumferential intense ring for igniting primer charge compounds. A simple initial test of the ring beam shaping technique was evaluated on a standard large caliber primer to determine its effectiveness on igniting the primer material. Several tests were conducted to gauge the feasibility of laser beam shaping, including optic fabrication and mounting on a cartridge, optic durability and functional ignition performance. Initial data will be presented, including testing of optically elements and empirical primer ignition / burn analysis.

  1. CO2 lasers: beam patterns in relation to surgical use.

    Science.gov (United States)

    Fava, G; Emanuelli, H; Cascinelli, N; Bandieramonte, G; Canestri, F; Marchesini, R

    1983-01-01

    According to surgeons operating with a variety of CO2 lasers available at the National Cancer Institute of Milan (Coherent, Sharplan, Valfivre), these lasers have different cutting and coagulation properties. To identify what physical parameters might corroborate the subjective impression of the surgeons, a comparative study of the crater forms in perspex samples was performed. Perspex was chosen for its thermal properties (in fact, its thermal conductivity and diffusivity are similar to those of organic tissue) and because it allowed good visualization and measurement of crater characteristics. Depth of penetration, crater diameter, and extension of thermal damage were measured against power, focal length, and exposure time for each CO2 laser model. These results can be used as an index of behaviour of different surgical lasers. It appears that for fully characterizing the interaction of surgical lasers with the sample, it is necessary to specify either power, focal length, exposure time, or beam mode.

  2. Laser beam propagation in atmospheric turbulence

    Science.gov (United States)

    Murty, S. S. R.

    1979-01-01

    The optical effects of atmospheric turbulence on the propagation of low power laser beams are reviewed in this paper. The optical effects are produced by the temperature fluctuations which result in fluctuations of the refractive index of air. The commonly-used models of index-of-refraction fluctuations are presented. Laser beams experience fluctuations of beam size, beam position, and intensity distribution within the beam due to refractive turbulence. Some of the observed effects are qualitatively explained by treating the turbulent atmosphere as a collection of moving gaseous lenses of various sizes. Analytical results and experimental verifications of the variance, covariance and probability distribution of intensity fluctuations in weak turbulence are presented. For stronger turbulence, a saturation of the optical scintillations is observed. The saturation of scintillations involves a progressive break-up of the beam into multiple patches; the beam loses some of its lateral coherence. Heterodyne systems operating in a turbulent atmosphere experience a loss of heterodyne signal due to the destruction of coherence.

  3. Dynamics and transport of laser-accelerated particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Stefan

    2010-04-19

    The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects

  4. Growth of Y3Fe5O12/GaN layers by laser molecular-beam epitaxy and characterization of their structural and magnetic properties

    Science.gov (United States)

    Kaveev, A. K.; Bursian, V. E.; Gastev, S. V.; Krichevtsov, B. B.; Suturin, S. M.; Volkov, M. P.; Sokolov, N. S.

    2016-12-01

    Laser molecular-beam epitaxy has been employed to obtain layers of yttrium-iron garnet (YIG) Y3Fe5O12 on gallium nitride substrates. It was found that there exists a polycrystalline YIG phase without admixtures of other structural phases. A magnetic anisotropy of films of the "easy-magnetic plane" type was found. The gyromagnetic ratio and the demagnetizing field 4π M S were calculated.

  5. Laser synchrotron radiation and beam cooling

    Energy Technology Data Exchange (ETDEWEB)

    Esarey, E.; Sprangle, P.; Ting, A. [Naval Research Lab., Washington, DC (United States)] [and others

    1995-12-31

    The interaction of intense {approx_gt} 10{sup 18} W/cm{sup 2}, short pulse ({approx_lt} 1 ps) lasers with electron beams and plasmas can lead to the generation of harmonic radiation by several mechanisms. Laser synchrotron radiation may provide a practical method for generating tunable, near monochromatic, well collimated, short pulse x-rays in compact, relatively inexpensive source. The mechanism for the generation of laser synchrotron radiation is nonlinear Thomson scattering. Short wavelengths can be generated via Thomson scattering by two methods, (i) backscattering from relativistic electron beams, in which the radiation frequency is upshifted by the relativistic factor 4{gamma}{sup 2}, and (ii) harmonic scattering, in which a multitude of harmonics are generated with harmonic numbers extending out to the critical harmonic number nc{approx_equal}a{sub 0}{sup 3} {much_gt} 1, where a{sub 0} {approx_equal}10{sup -9}{lambda}I{sup 1/2}, {lambda} is the laser wavelength in {mu}m and I is the laser intensity in W/cm{sup 2}. Laser synchrotron sources are capable of generating short ({approx_lt} ps) x-ray pulses with high peak flux ({approx_gt} 10{sup 21} photons/s) and brightness ({approx_gt}{sup 19} photons/s-mm{sup 2}-mrad{sup 2} 0.1%BW. As the electron beam radiates via Thomson scattering, it can subsequently be cooled, i.e., the beam emittance and energy spread can be reduced. This cooling can occur on rapid ({approximately} ps) time scales. In addition, electron distributions with sufficiently small axial energy spreads can be used to generate coherent XUV radiation via a laser-pumped FEL mechanism.

  6. Illumination uniformity of capsules directly driven by a facility with thousands of laser beams

    Directory of Open Access Journals (Sweden)

    Temporal M.

    2013-11-01

    Full Text Available The uniformity of the illumination of a spherical capsule directly driven by laser beams has been assessed numerically. Different schemes characterized by ND = 12, 20, 32, 48 and 60 directions of irradiation associated to a single laser beam or a bundle of NB laser beams have been considered. The laser beams intensity profile is assumed super-Gaussian and the calculations take into account for beam imperfections as power imbalance and pointing errors. These facilities are characterized by a large number of laser beams Ntot = NDxNB. Assuming relatively small laser beams with an energy of a few hundred of J (200 J–500 J it turn out that a few thousand of beamlets (1000–5000 are needed in order to provide a total energy of 0.5–1 MJ. A large parametric study has been performed showing that the optimum laser intensity profile, which minimizes the root-mean-square deviation of the capsule illumination, depends on the values of the power imbalance and pointing error. Moreover, when beams imperfections are taken into account it is found that the uniformity of the illumination is almost the same for all facilities and only depends on the total number of laser beams Ntot.

  7. Microstructural characterization of Ti-C-N thin films prepared by reactive crossed beam pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Escobar-Alarcon, L., E-mail: luis.escobar@inin.gob.mx [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Medina, V.; Camps, Enrique; Romero, S. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Fernandez, M. [Departamento de Aceleradores, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Solis-Casados, D. [Centro Conjunto de Investigacion en Quimica Sustentable, Facultad de Quimica UAEMex, km. 14.5 carr. Toluca-Atlacomulco (Mexico)

    2011-08-15

    In this work, Raman spectroscopy has been used to characterize Ti-C-N thin films in order to obtain information about the microstructure of the deposited materials, and in particular to study the effects due to the carbon incorporation into the TiN lattice. Ti-C-N thin films were prepared using a crossed plasma configuration in which the ablation of two different targets, titanium and carbon, in a reactive atmosphere was performed. With this configuration, the carbon content in the films was varied in an easy way from 5.0 at% to 40.0 at%. Thin film composition was determined from Non-Rutherford Backscattering Spectroscopy (NRBS) measurements. X-ray photoelectron spectroscopy and X-Ray diffraction measurements were also carried out in order to characterize the films in more detail, with this being used to give support to the interpretation of the Raman spectra. The Raman results revealed that at lower carbon concentrations a solid solution Ti(C, N) is formed, whilst at higher carbon concentrations a nanocomposite, consisting of nanocrystalline TiCN and TiC immersed in an amorphous carbon matrix is obtained.

  8. Characterising laser beams with liquid crystal displays

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2016-09-01

    Full Text Available We show how one can determine the various properties of light, from the modal content of laser beams to decoding the information stored in optical fields carrying orbital angular momentum, by performing a modal decomposition. Although the modal...

  9. Coherent beam combiner for a high power laser

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd A.

    2002-01-01

    A phase conjugate laser mirror employing Brillouin-enhanced four wave mixing allows multiple independent laser apertures to be phase locked producing an array of diffraction-limited beams with no piston phase errors. The beam combiner has application in laser and optical systems requiring high average power, high pulse energy, and low beam divergence. A broad range of applications exist in laser systems for industrial processing, especially in the field of metal surface treatment and laser shot peening.

  10. Safe Laser Beam Propagation for Interplanetary Links

    Science.gov (United States)

    Wilson, Keith E.

    2011-01-01

    Ground-to-space laser uplinks to Earth–orbiting satellites and deep space probes serve both as a beacon and an uplink command channel for deep space probes and Earth-orbiting satellites. An acquisition and tracking point design to support a high bandwidth downlink from a 20-cm optical terminal on an orbiting Mars spacecraft typically calls for 2.5 kW of 1030-nm uplink optical power in 40 micro-radians divergent beams.2 The NOHD (nominal ocular hazard distance) of the 1030nm uplink is in excess of 2E5 km, approximately half the distance to the moon. Recognizing the possible threat of high power laser uplinks to the flying public and to sensitive Earth-orbiting satellites, JPL developed a three-tiered system at its Optical Communications Telescope Laboratory (OCTL) to ensure safe laser beam propagation through navigational and near-Earth space.

  11. Modelling, Design, Growth and Characterization of Strain Balanced Quantum Cascade Lasers (3-11mum), grown by Gas Source Molecular Beam Epitaxy

    Science.gov (United States)

    Bandyopadhyay, Neelanjan

    Quantum Cascade Laser (QCL) is a compact room temperature (RT) source of mid-infrared radiation, which can be used for spectroscopic detection of trace amount of chemicals. The mid-infrared spectral range between (3-11 microm), has a dense array of absorption lines of numerous molecules, due to the presence of fundamental vibrational modes. The goal of this thesis can be subdivided into two parts. Firstly, short wavelength QCLs, emitting below 4microm, perform poorly at RT, due to inter-valley Gamma --- L carrier scattering, carrier escape to the continuum, heat removal from the core region at high power density corresponding to short wavelength operation, and large interface scattering due to highly strained materials. Secondly, it is desirable to have a single QCL based source emitting between 6-10microm, which be used to detect multiple molecules having their peak absorptions far apart, inside this spectral range. However, gain bandwidth of a single core QCL is relatively small, so laser emission cannot be tuned over a wide spectral range. This thesis describes the working principle of a QCL based on superlattice transport, rate equations, scattering mechanism, and waveguide design. The choice of the material system for this work and the fundamentals of band structure engineering has been derived. Gas source molecular beam epitaxy - growth optimization and characterization is one of the most important features of this work, especially for short wavelength QCLs, and has been explained in depth. Different strategies for design of active region design of short wavelength QCL and heterogeneous broadband QCL has been explored. The major milestones, of this research was the world's first watt level continuous wave (CW), RT demonstration at 3.76 microm, which was followed by another milestone of the first CW, RT demonstration at 3.39microm and 3.55microm, and finally the elusive result of QCL emitting at CW, RT at a wavelength as short as lambda ~3microm, a record. In

  12. Coherent beam combining of high powerfiber lasers: Progress and prospect

    Institute of Scientific and Technical Information of China (English)

    LIU; ZeJin; ZHOU; Pu; XU; XiaoJun; WANG; XiaoLin; MA; YanXing

    2013-01-01

    The recent research progress of coherent beam combining of high power fiber lasers is reviewed. Key technologies like coherently combinable fiber laser, phase control of multiple beams and beam tilling are specially analyzed. Prospects for single coherently combinable high power fiber amplifier, beam tilling and target-in-the-loop control for propagation in real atmosphere are presented.

  13. Laser Wire and Beam Position Monitor tests

    CERN Document Server

    Boogert, S T; Lyapin, A; Nevay, L; Snuverink, J

    2013-01-01

    This subtask involved two main activities; Firstly the development and subsequent usage of high resolution beam position monitors (BPM) for the International Linear Collider (ILC) and Compact Linear Collider projects (CLIC); and secondly the development of a laser-wire (LW) transverse beam size measurement systems. This report describes the technical progress achieved at a large-scale test ILC compatible BPM system installed at the Accelerator Test Facility 2 (ATF2). The ATF2 is an energy-scaled demonstration system for the final focus systems required to deliver the particle beams to collision at the ILC and CLIC. The ATF2 cavity beam position monitor system is one of the largest of its kind and rivals systems used at free electron lasers. The ATF2 cavity beam position system has achieved a position resolutionof 250 nm (with signal attuenation) and 27 nm (without attenuation). The BPM system has been used routinely for lattice diagnostics, beam based alignment and wakefield measurements. Extensive experience...

  14. Laser-cooled bunched ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, J.P.; Hangst, J.S.; Nielsen, J.S. [and others

    1995-08-01

    In collaboration with the Arhus group, the laser cooling of a beam bunched by an rf electrode was investigated at the ASTRID storage ring. A single laser is used for unidirectional cooling, since the longitudinal velocity of the beam will undergo {open_quotes}synchrotron oscillations{close_quotes} and the ions are trapped in velocity space. As the cooling proceeds the velocity spread of the beam, as well as the bunch length is measured. The bunch length decreases to the point where it is limited only by the Coulomb repulsion between ions. The measured length is slightly (20-30%) smaller than the calculated limit for a cold beam. This may be the accuracy of the measurement, or may indicate that the beam still has a large transverse temperature so that the longitudinal repulsion is less than would be expected from an absolutely cold beam. Simulations suggest that the coupling between transverse and longitudinal degrees of freedom is strong -- but this issue will have to be resolved by further measurements.

  15. Characterization of LIL laser UV focal spot

    Energy Technology Data Exchange (ETDEWEB)

    Mangeant, M.; Dubois, J.L.; Behar, G.; Arroyo, P.; Durand, V.; Lahonde, C. [CEA - Centre d' Etudes Scientifiques et Techniques d' Aquitaine, CESTA/DLP, 33 - Le Barp (France)

    2006-06-15

    One way to get the fusion of hydrogen in laboratory consists in heating and compressing a DT fuel capsule by using a laser. To reach this aim requires a new generation of high power laser facility. Cea (French board for atomic energy) is developing for this purpose a new 240 laser line facility, the LMJ facility. The LIL which is the prototype of four LMJ laser lines is operational now. In order to confirm the technical choices, a systematic characterization of LIL was carried out. A particular effort has been provided to measure the 3{omega} high energy focal spot (1.5 kJ/700 ps and 5 ns for one beam) and the synchronization of laser beams onto the target, which are key issues for the plasma production. An experimental device, SAT-3{omega} (a 3{omega} laser focal spot analysis) has been designed to perform these measures. That diagnostic which is located at the end of the laser lines delivered its first results during the 2004 quadruplet qualification campaigns. The near field imaging showed no diaphony and vignetting. Low power spots allowed us to control we had no ghost. The energy measurement quality showed the photometric transfer function was perfectly known. Our caustic image are given with an average dynamic range of 800, a spatial resolution of 10 {mu}m and diameter accuracy about 1% for 50% and 3% for 90% of encircled energy. The high energy focal spot diameters are in agreement with low and very low energy diameters. The phase plate and 14 GHz effects are similar to what we had expected. For a laser shot completed with a continuous phase plate at 14 GHz, and for an energy level of 1.5 kJ per beam at 351 nm, the focal beam diameter at 3% of the peak level is (875 {+-} 45) {mu}m.

  16. Laser beam shaping theory and techniques, second edition

    CERN Document Server

    Dickey, Fred M

    2014-01-01

    Laser Beam Shaping: Theory and Techniques addresses the theory and practice of every important technique for lossless beam shaping. Complete with experimental results as well as guidance on when beam shaping is practical and when each technique is appropriate, the Second Edition is updated to reflect significant developments in the field. This authoritative text:Features new chapters on axicon light ring generation systems, laser-beam-splitting (fan-out) gratings, vortex beams, and microlens diffusersDescribes the latest advances in beam profile measurement technology and laser beam shaping using diffractive diffusersContains new material on wavelength dependence, channel integrators, geometrical optics, and optical softwareLaser Beam Shaping: Theory and Techniques, Second Edition not only provides a working understanding of the fundamentals, but also offers insight into the potential application of laser-beam-profile shaping in laser system design.

  17. Laser Beam Caustic Measurement with Focal Spot Analyser

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Gong, Hui; Bagger, Claus

    2005-01-01

    In industrial applications of high power CO2-lasers the caustic characteristics of the laser beam have great effects on the performance of the lasers. A welldefined high intense focused spot is essential for reliable production results. This paper presents a focal spot analyser that is developed...... for measuring the beam profiles of focused high power CO2-lasers....

  18. A novel laser beam generator in place at SGll

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ Researchers with the State Key Laboratory of High Field Laser Physics, the CAS Shanghai Institute of Optics and Fine Mechanics, have been successful in developing a multifunctional and high-energy laser beam system (also known as the ninth laser beam) at the Shenguang-II Laser Facility (SGII).

  19. Biostimulative Effect Of Laser Beams

    Science.gov (United States)

    Mester, E.

    1981-05-01

    We report on experiences gained in healing clinical cases treated with He-Ne and Argon-laser grouped according to etiology. In order to elucidate the action mechanism of the bioregulatory process, the following experiments were carried out: 1. Serial electron-microscopic and radioactivity studies of samples obtained from human ulcers; 2. Chemical transfer of stimulating substrate on human leukocyte population; 3. Enzyme histochemical studies in experiments on rats; 4. Study of vascularization with the "ear chamber" technique carried out on rabbit's ear; 5. The increase of tensile strength in rats; 6. Biochemical demonstration of the RNA, DNA, albumin synthesis on human fibrocyte-cultures; 7.a, 7.b, Immunological studies; 8. Prostaglandin producing effect. The discovery of laser opened up new prospects in the field of the biological research and medical use.

  20. Robust Collimation Control of Laser-Generated Ion Beam

    CERN Document Server

    Kawata, S; Kamiyama, D; Nagashima, T; Barada, D; Gu, Y J; Li, X; Yu, Q; Kong, Q; Wang, P X

    2015-01-01

    The robustness of a structured collimation device is discussed for an intense-laser-produced ion beam. In this paper the ion beam collimation is realized by the solid structured collimation device, which produces the transverse electric field; the electric field contributes to reduce the ion beam transverse velocity and collimate the ion beam. Our 2.5 dimensional particle-in cell simulations demonstrate that the collimation device is rather robust against the changes in the laser parameters and the collimation target sizes. The intense short-pulse lasers are now available, and are used to generate an ion beam. The issues in the laser ion acceleration include an ion beam collimation, ion energy spectrum control, ion production efficiency, ion energy control, ion beam bunching, etc. The laser-produced ion beam tends to expand in the transverse and longitudinal directions during the ion beam propagation. The ion beam collimation is focused in this paper.

  1. Hybrid laser-beam-shaping system for rotatable dual beams with long depth of focus

    Science.gov (United States)

    Chou, Fu-Lung; Chen, Cheng-Huan; Lin, Yu-Chung; Lin, Mao-Chi

    2016-08-01

    A laser processing system consisting of two diffractive elements and one refractive element is proposed enabling a Gaussian laser beam to be transformed into two beams with a depth of focus of up to 150 µm and focal spot smaller than 5 µm. For specific laser processing, the two beams are rotatable when the beam-splitting diffractive element is rotated. The overall system is versatile for laser cutting and drilling.

  2. Laser-cooled continuous ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, J.P.; Hangst, J.S.; Nielsen, J.S. [and others

    1995-08-01

    A collaboration with a group in Arhus, Denmark, using their storage ring ASTRID, brought about better understanding of ion beams cooled to very low temperatures. The longitudinal Schottky fluctuation noise signals from a cooled beam were studied. The fluctuation signals are distorted by the effects of space charge as was observed in earlier measurements at other facilities. However, the signal also exhibits previously unobserved coherent components. The ions` velocity distribution, measured by a laser fluorescence technique suggests that the coherence is due to suppression of Landau damping. The observed behavior has important implications for the eventual attainment of a crystalline ion beam in a storage ring. A significant issue is the transverse temperature of the beam -- where no direct diagnostics are available and where molecular dynamics simulations raise interesting questions about equilibrium.

  3. Radiative trapping in intense laser beams

    Science.gov (United States)

    Kirk, J. G.

    2016-08-01

    The dynamics of electrons in counter-propagating, circularly polarized laser beams are shown to exhibit attractors whose ability to trap particles depends on the ratio of the beam intensities and a single parameter describing radiation reaction. Analytical expressions are found for the underlying limit cycles and the parameter range in which they are stable. In high-intensity optical pulses, where radiation reaction strongly modifies the trajectories, the production of collimated gamma-rays and the initiation of non-linear cascades of electron-positron pairs can be optimized by a suitable choice of the intensity ratio.

  4. Free Electron Lasers using `Beam by Design'

    CERN Document Server

    Henderson, J R; McNeil, B W J

    2015-01-01

    Several methods have been proposed in the literature to improve Free Electron Laser output by transforming the electron phase-space before entering the FEL interaction region. By utilising `beam by design' with novel undulators and other beam changing elements, the operating capability of FELs may be further usefully extended. This paper introduces two new such methods to improve output from electron pulses with large energy spreads and the results of simulations of these methods in the 1D limit are presented. Both methods predict orders of magnitude improvements to output radiation powers.

  5. Radiative trapping in intense laser beams

    CERN Document Server

    Kirk, J G

    2016-01-01

    The dynamics of electrons in counter-propagating, circularly polarized laser beams are shown to exhibit attractors whose ability to trap particles depends on the ratio of the beam intensities and a single parameter describing radiation reaction. Analytical expressions are found for the underlying limit cycles and the parameter range in which they are stable. In high-intensity optical pulses, where radiation reaction strongly modifies the trajectories, the production of collimated gamma-rays and the initiation of non-linear cascades of electron-positron pairs can be optimized by a suitable choice of the intensity ratio.

  6. ELIMED, future hadrontherapy applications of laser-accelerated beams

    Science.gov (United States)

    Cirrone, Giuseppe A. P.; Carpinelli, Massimo; Cuttone, Giacomo; Gammino, Santo; Bijan Jia, S.; Korn, Georg; Maggiore, Mario; Manti, Lorenzo; Margarone, Daniele; Prokupek, Jan; Renis, Marcella; Romano, Francesco; Schillaci, Francesco; Tomasello, Barbara; Torrisi, Lorenzo; Tramontana, Antonella; Velyhan, Andriy

    2013-12-01

    Laser-ion acceleration has recently gained a great interest as an alternative to conventional and more expensive acceleration techniques. These ion beams have desirable qualities such as small source size, high luminosity and small emittance to be used in different fields as Nuclear Physics, Medical Physics, etc. This is very promising specially for the future perspective of a new concept of hadrontherapy based on laser-based devices could be developed, replacing traditional accelerating machines. Before delivering laser-driven beams for treatments they have to be handled, cleaned from unwanted particles and characterized in order to have the clinical requirements. In fact ion energy spectra have exponential trend, almost 100% energy spread and a wide angular divergence which is the biggest issue in the beam transport and, hence, in a wider use of this technology. In order to demonstrate the clinical applicability of laser-driven beams new collaboration between ELI-Beamlines project researchers from Prague (Cz) and a INFN-LNS group from Catania (I) has been already launched and scientists from different countries have already express their will in joining the project. This cooperation has been named ELIMED (MEDical application at ELIBeamlines) and will take place inside the ELI-Beamlines infrastructure located in Prague. This work describes the schedule of the ELIMED project and the design of the energy selector which will be realized at INFN-LNS. The device is an important part of the whole transport beam line which will be realised in order to make the ion beams suitable for medical applications.

  7. Freeform beam shaping for high-power multimode lasers

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim

    2014-03-01

    Widening of using high power multimode lasers in industrial laser material processing is accompanied by special requirements to irradiance profiles in such technologies like metal or plastics welding, cladding, hardening, brazing, annealing, laser pumping and amplification in MOPA lasers. Typical irradiance distribution of high power multimode lasers: free space solid state, fiber-coupled solid state and diodes lasers, fiber lasers, is similar to Gaussian. Laser technologies can be essentially improved when irradiance distribution on a workpiece is uniform (flattop) or inverse-Gauss; when building high-power pulsed lasers it is possible to enhance efficiency of pumping and amplification by applying super-Gauss irradiance distribution with controlled convexity. Therefore, "freeform" beam shaping of multimode laser beams is an important task. A proved solution is refractive field mapping beam shaper like Shaper capable to control resulting irradiance profile - with the same unit it is possible to get various beam profiles and choose optimum one for a particular application. Operational principle of these devices implies transformation of laser irradiance distribution by conserving beam consistency, high transmittance, providing collimated low divergent output beam. Using additional optics makes it possible to create resulting laser spots of necessary size and round, elliptical or linear shape. Operation out of focal plane and, hence, in field of lower wavefront curvature, allows extending depth of field. The refractive beam shapers are implemented as telescopes and collimating systems, which can be connected directly to fiber-coupled lasers or fiber lasers, thus combining functions of beam collimation and irradiance transformation.

  8. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    Science.gov (United States)

    Bonomo, F.; Ruf, B.; Barbisan, M.; Cristofaro, S.; Schiesko, L.; Fantz, U.; Franzen, P.; Pasqualotto, R.; Riedl, R.; Serianni, G.; Wünderlich, D.

    2015-04-01

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the Hα light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of Hα spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  9. Laser Beam Profile Influence on LIBS Analytical Capabilities: Single vs. Multimode Beam

    CERN Document Server

    Lednev, Vasily N; Bunkin, Alexey F

    2013-01-01

    Single vs. multimode laser beams have been compared for laser ablation on steel samples. Laser plasma properties and analytical capabilities (precision, limit of detection) were used as key parameters for comparison. Peak fluence at focal spot has been observed to be higher for Gaussian beam despite ~14-fold lower pulse energy. A comparison of Gaussian and multimode beams with equal energy was carried out in order to estimate influence of beam profile only. Single mode lasing (Gaussian beam) results in better reproducibility of analytical signals compared to multimode lasing while laser energy reproducibility was the same for both cases. Precision improvements were attributed to more stable laser ablation due to better reproducibility of beam profile fluence at laser spot. Plasma temperature and electron density were higher for Gaussian laser beam. Calibration curves were obtained for four elements under study (Cr, Mn, Si, Cu). Two sampling (drilling and scanning procedures) and two optical detection schemes ...

  10. Mechanically assisted laser forming of thin beams

    Science.gov (United States)

    Mucha, Zygmunt; Widłaszewski, Jacek; Kurp, Piotr; Mulczyk, Krystian

    2016-12-01

    Laser-assisted forming techniques have been developed in recent years to aid plastic working of materials, which are difficult in processing at normal temperatures due to a high brittleness, effects of high work-hardening or a high spring-back phenomenon. This paper reports initial experimental investigations and numerical simulations of a mechanically-assisted laser forming process. The research is aimed at facilitating plastic shaping of thin-walled parts made of high temperature resistant alloys. Stainless steel plate, 1 mm thick, 20 mm wide, was mounted in the cantilever arrangement and a gravitational load was applied to its free end. A CO2 laser beam with rectangular cross-section traversed along the plate, towards the fixed edge. Laser spot covered the whole width of the plate. Experiments and simulations using the finite element method were performed for different values of mechanical load and with constant laser processing parameters. Experimentally validated numerical model allowed analysis of plastic deformation mechanism under the hybrid thermo-mechanical processing. The revealed mechanism of deformation consists in intense material plastic flow near the laser heated surface. This behavior results mainly from the tension state close to the heated surface and the decrease of material yield stress at elevated temperature. Stress state near the side edges of the processed plate favored more intense plastic deformation and the involved residual stress in this region.

  11. Beam Emittance Measurement with Laser Wire Scanners in the ILC Beam Delivery System

    Energy Technology Data Exchange (ETDEWEB)

    Agapov, I.; /CERN; Blair, G.A.; /Royal Holloway, U. of London; Woodley, M.; /SLAC

    2008-02-01

    Accurate measurement of the beam phase-space is essential for the next generation of electron accelerators. A scheme for beam optics optimization and beam matrix reconstruction algorithms for the diagnostics section of the beam delivery system of the International Linear Collider based on laser-wire beam profile monitors are discussed. Possible modes of operation of the laser-wire system together with their corresponding performance are presented. Based on these results, prospects for reconstructing the ILC beam emittance from representative laser-wire beam size measurements are evaluated.

  12. Laser alignment measurement model with double beam

    Science.gov (United States)

    Mo, Changtao; Zhang, Lili; Hou, Xianglin; Wang, Ming; Lv, Jia; Du, Xin; He, Ping

    2012-10-01

    Double LD-Double PSD schedule.employ a symmetric structure and there are a laser and a PSD receiver on each axis. The Double LD-Double PSD is used, and the rectangular coordinate system is set up by use of the relationship of arbitrary two points coordinates, and then the parameter formula is deduced by the knowledge of solid geometry. Using the data acquisition system and the data processing model of laser alignment meter with double laser beam and two detector , basing on the installation parameter of the computer, we can have the state parameter between the two shafts by more complicated calculation and correction. The correcting data of the four under chassis of the adjusted apparatus moving on the level and the vertical plane can be calculated using the computer. This will instruct us to move the apparatus to align the shafts.

  13. 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.

  14. Repositioning and steering laser beam power via coherent combination of multiple Airy beams.

    Science.gov (United States)

    Zhang, Ze; Ye, Zhuoyi; Song, Daohong; Zhang, Peng; Chen, Zhigang

    2013-12-10

    We study numerically and experimentally laser coherent combination (LCC) with multiple one- or two-dimensional Airy beams. It is shown that the method of LCC using Airy beams leads to a higher combining efficiency and a better feature of propagation than that using conventional Gaussian beams. Based on such coherent Airy beams combination, we propose a laser steering approach that could achieve large-angle beam steering (over 0.6°) without the need of using any mechanical steering component.

  15. Definition and measurement of the beam propagation factor M2 for chromatic laser beams

    Institute of Scientific and Technical Information of China (English)

    Tao Fang; Xin Ye; Jinfu Niu; Jianqiu Xu

    2006-01-01

    The concept of the beam propagation factor M2 is extended for chromatic laser beams. The definition of the beam propagation factor can be generalized with the weighted effective wavelength. Using the new definition of factor M2, the propagation of chromatic beams can be analyzed by the beam propagation factor M2 as same as that of monochromatic beams. A simple method to measure the chromatic beam factor M2 is demonstrated. The chromatic factor M2 is found invariable while the laser beam propagates through the dispersion-free ABCD system.

  16. Laser beam riding guided system principle and design research

    Science.gov (United States)

    Qu, Zhou; Jin, Yi; Xu, Zhou; Xing, Hao

    2016-01-01

    With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

  17. Design of the prototype of a beam transport line for handling and selection of low energy laser-driven beams

    Science.gov (United States)

    Schillaci, F.; Maggiore, M.; Cirrone, G. A. P.; Cuttone, G.; Pisciotta, P.; Costa, M.; Rifuggiato, D.; Romano, F.; Scuderi, V.

    2016-11-01

    A first prototype of transport beam-line for laser-driven ion beams to be used for the handling of particles accelerated by high-power laser interacting with solid targets has been realized at INFN. The goal is the production of a controlled and stable beam in terms of energy and angular spread. The beam-line consists of two elements: an Energy Selection System (ESS), already realized and characterized with both conventional and laser-accelerated beams, and a Permanent Magnet Quadrupole system (PMQ) designed, in collaboration with SIGMAPHI (Fr), to improve the ESS performances. In this work a description of the ESS system and some results of its characterization with conventional beams are reported, in order to provide a complete explanation of the acceptance calculation. Then, the matching with the PMQ system is presented and, finally, the results of preliminary simulations with a realistic laser-driven energy spectrum are discussed demonstrating the possibility to provide a good quality beam downstream the systems.

  18. Mono Energetic Beams from Laser Plasma Interactions

    CERN Document Server

    Geddes, Cameron G; Esarey, Eric; Leemans, Wim; Nieter, Chet; Schröder, Carl B; Toth, Csaba; Van Tilborg, Jeroen

    2005-01-01

    A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the L’OASIS laser,* the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing >200pC charge above 80 MeV and with normalized emittance estimated at < 2 pi -mm-mrad were produced.** Data and simulations (VORPAL***) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was g...

  19. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Bonomo, F., E-mail: federica.bonomo@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Istituto Gas Ionizzati - CNR, Corso Stati Uniti 4, 35127 Padova (Italy); Ruf, B.; Schiesko, L.; Fantz, U.; Franzen, P.; Riedl, R.; Wünderlich, D. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Barbisan, M.; Pasqualotto, R.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Cristofaro, S. [Universitá degli Studi di Padova, Via 8 Febbraio 2, 35122 Padova (Italy)

    2015-04-08

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (< 0.4 °) together with a low source pressure (≤ 0.3 Pa) would permit to reduce the ion losses along the beamline, keeping the stripping particle losses below 30%. However, the attainment of such beam properties is not straightforward. At IPP, the negative ion source testbed BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the H{sub α} light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of H{sub α} spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  20. Reduction of the Influence of Laser Beam Directional Dithering in a Laser Triangulation Displacement Probe.

    Science.gov (United States)

    Yang, Hongwei; Tao, Wei; Zhang, Zhengqi; Zhao, Siwei; Yin, Xiaoqia; Zhao, Hui

    2017-05-15

    Directional dithering of a laser beam potentially limits the detection accuracy of a laser triangulation displacement probe. A theoretical analysis indicates that the measurement accuracy will linearly decrease as the laser dithering angle increases. To suppress laser dithering, a scheme for reduction of the influence of laser beam directional dithering in a laser triangulation displacement probe, which consists of a collimated red laser, a laser beam pointing control setup, a receiver lens, and a charge-coupled device, is proposed in this paper. The laser beam pointing control setup is inserted into the source laser beam and the measured object and can separate the source laser beam into two symmetrical laser beams. Hence, at the angle at which the source laser beam dithers, the positional averages of the two laser spots are equal and opposite. Moreover, a virtual linear function method is used to maintain a stable average of the positions of the two spots on the imaging side. Experimental results indicate that with laser beam pointing control, the estimated standard deviation of the fitting error decreases from 0.3531 mm to 0.0100 mm , the repeatability accuracy can be lowered from ±7 mm to ±5 μ m , and the nonlinear error can be reduced from ±6 % FS (full scale) to ±0.16 % FS.

  1. Laser systems configured to output a spectrally-consolidated laser beam and related methods

    Science.gov (United States)

    Koplow, Jeffrey P [San Ramon, CA

    2012-01-10

    A laser apparatus includes a plurality of pumps each of which is configured to emit a corresponding pump laser beam having a unique peak wavelength. The laser apparatus includes a spectral beam combiner configured to combine the corresponding pump laser beams into a substantially spatially-coherent pump laser beam having a pump spectrum that includes the unique peak wavelengths, and first and second selectively reflective elements spaced from each other to define a lasing cavity including a lasing medium therein. The lasing medium generates a plurality of gain spectra responsive to absorbing the pump laser beam. Each gain spectrum corresponds to a respective one of the unique peak wavelengths of the substantially spatially-coherent pump laser beam and partially overlaps with all other ones of the gain spectra. The reflective elements are configured to promote emission of a laser beam from the lasing medium with a peak wavelength common to each gain spectrum.

  2. Spectral beam combining of diode lasers with high efficiency

    DEFF Research Database (Denmark)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin;

    2012-01-01

    Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation.......Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation....

  3. Characterising laser beams with liquid crystal displays

    Science.gov (United States)

    Dudley, Angela; Naidoo, Darryl; Forbes, Andrew

    2016-02-01

    We show how one can determine the various properties of light, from the modal content of laser beams to decoding the information stored in optical fields carrying orbital angular momentum, by performing a modal decomposition. Although the modal decomposition of light has been known for a long time, applied mostly to pattern recognition, we illustrate how this technique can be implemented with the use of liquid-crystal displays. We show experimentally how liquid crystal displays can be used to infer the intensity, phase, wavefront, Poynting vector, and orbital angular momentum density of unknown optical fields. This measurement technique makes use of a single spatial light modulator (liquid crystal display), a Fourier transforming lens and detector (CCD or photo-diode). Such a diagnostic tool is extremely relevant to the real-time analysis of solid-state and fibre laser systems as well as mode division multiplexing as an emerging technology in optical communication.

  4. Study on the Beam Quality of Uncoupled Laser Diode Arrays

    Institute of Scientific and Technical Information of China (English)

    GAO Chunqing; WEI Guanghui

    2001-01-01

    The beam quality of uncoupled laser diode array is studied theoretically and experimentally. By calculating the second order moments of the beam emitted from the laser diode array, the dependence of the M2-factor of the laser diode array on the M2-factor of the single emitter, the ratio of the emitting region to the non-emitting space, and the number of emitters, has been deduced. From the measurement of the beam propagation the M2-factor of a laser diode bar is experimentally determined. The measured M2-factor of the laser diode bar agrees with the theoretical prediction.

  5. Laser beam active brazing of metal ceramic joints

    Science.gov (United States)

    Haferkamp, Heinz; Bach, Friedrich W.; von Alvensleben, Ferdinand; Kreutzburg, K.

    1996-04-01

    The use of engineering ceramics is becoming more and more important. Reasons for this are the specific properties of these materials, such as high strength, corrosion resistance and wear resistance. To apply the advantages of ceramics, joining techniques of metal ceramic parts are required. In this paper, joining of metal ceramic joints by laser beam brazing is presented. This joining technique is characterized by local heat input, and the minimal thermal stress of the brazed components. During the investigations, an Nd:YAG laser and a vacuum chamber were applied. The advantages of Nd:YAG lasers are the simple mechanical construction, and laser beam guidance via quartz glass fibers, which leads to high handling flexibility. In addition, most of the materials show a high absorption rate for this kind of radiation. As materials, ceramic Al2O3 with a purity of 99.4% and metals such as X5CrNi189 and Fe54Ni29Co17 were used. As a filler material, commercially available silver and silver- copper brazes with chemically active elements like titanium were employed. During this study, the brazing wetting behavior and the formation of diffusion layers in dependence on processing parameters were investigated. The results have shown that high brazing qualities can be achieved by means of the laser beam brazing process. Crack-free joining of metal ceramic parts is currently only possible by the use of metals such as Fe54Ni29Co17 because of its low thermal expansion coefficient, which reduces thermal stresses within the joining zone.

  6. External cavity beam combining of 21 semiconductor lasers using SPGD.

    Science.gov (United States)

    Montoya, Juan; Augst, Steven J; Creedon, Kevin; Kansky, Jan; Fan, Tso Yee; Sanchez-Rubio, Antonio

    2012-04-10

    Active coherent beam combining of laser oscillators is an attractive way to achieve high output power in a diffraction limited beam. Here we describe an active beam combining system used to coherently combine 21 semiconductor laser elements with an 81% beam combining efficiency in an external cavity configuration compared with an upper limit of 90% efficiency in the particular configuration of the experiment. Our beam combining system utilizes a stochastic parallel gradient descent (SPGD) algorithm for active phase control. This work demonstrates that active beam combining is not subject to the scaling limits imposed on passive-phasing systems.

  7. Laser Plasmas : Optical guiding of laser beam in nonuniform plasma

    Indian Academy of Sciences (India)

    Tarsem Singh Gill

    2000-11-01

    A plasma channel produced by a short ionising laser pulse is axially nonuniform resulting from the self-defocusing. Through such preformed plasma channel, when a delayed pulse propagates, the phenomena of diffraction, refraction and self-phase modulation come into play. We have solved the nonlinear parabolic partial differential equation governing the propagation characteristics for an approximate analytical solution using variational approach. Results are compared with the theoretical model of Liu and Tripathi (Phys. Plasmas 1, 3100 (1994)) based on paraxial ray approximation. Particular emphasis is on both beam width and longitudinal phase delay which are crucial to many applications.

  8. Beam splitting target reflector based compensation for angular drift of laser beam in laser autocollimation of measuring small angle deviations.

    Science.gov (United States)

    Zhu, Fan; Tan, Jiubin; Cui, Jiwen

    2013-06-01

    Beam splitting target reflector based compensation for the angular drift of laser beam in laser autocollimation is proposed in this article to improve the measurement accuracy and stability of small angle deviations. A beam splitting target reflector is used to replace the plane mirror in laser autocollimation to generate a reference beam when returning the measurement beam. The reference beam and measurement beam have the same angular drift, but have different sensitivities to the rotation angle of the reflector due to the unique characteristics of the reflector. Thus, the angular drift of laser beam in laser autocollimation can be compensated in real time by using the drift of reference beam. Experimental results indicate that an output stability of 0.085 arc sec in 2 h can be achieved after compensation. And a measurement accuracy of ±0.032 arc sec can be obtained over the range of ±1190 arc sec with an effective resolution of 0.006 arc sec. It is confirmed that the compensation method for the angular drift of laser beam is necessary for improving the measurement accuracy and stability in laser autocollimation.

  9. Beam splitting target reflector based compensation for angular drift of laser beam in laser autocollimation of measuring small angle deviations

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Fan; Tan Jiubin; Cui Jiwen [Center of Ultra-precision Optoelectronic Instrument Engineering, Harbin Institute of Technology, Harbin 150080 (China)

    2013-06-15

    Beam splitting target reflector based compensation for the angular drift of laser beam in laser autocollimation is proposed in this article to improve the measurement accuracy and stability of small angle deviations. A beam splitting target reflector is used to replace the plane mirror in laser autocollimation to generate a reference beam when returning the measurement beam. The reference beam and measurement beam have the same angular drift, but have different sensitivities to the rotation angle of the reflector due to the unique characteristics of the reflector. Thus, the angular drift of laser beam in laser autocollimation can be compensated in real time by using the drift of reference beam. Experimental results indicate that an output stability of 0.085 arc sec in 2 h can be achieved after compensation. And a measurement accuracy of {+-}0.032 arc sec can be obtained over the range of {+-}1190 arc sec with an effective resolution of 0.006 arc sec. It is confirmed that the compensation method for the angular drift of laser beam is necessary for improving the measurement accuracy and stability in laser autocollimation.

  10. Characterisation of electron beams from laser-driven particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Brunetti, E.; Manahan, G. G.; Shanks, R. P.; Islam, M. R.; Ersfeld, B.; Anania, M. P.; Cipiccia, S.; Issac, R. C.; Vieux, G.; Welsh, G. H.; Wiggins, S. M.; Jaroszynski, D. A. [Physics Department, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2012-12-21

    The development, understanding and application of laser-driven particle accelerators require accurate measurements of the beam properties, in particular emittance, energy spread and bunch length. Here we report measurements and simulations showing that laser wakefield accelerators can produce beams of quality comparable to conventional linear accelerators.

  11. Advantages of ground-to-space laser power beaming

    Science.gov (United States)

    Rather, John D. G.

    1992-01-01

    NASA's current research activities to evaluate laser power beaming systems are reviewed. Applications of such systems are considered, including communications satellites, radar and direct broadcast satellites, space transfer vehicles lunar base operations and exploration, and optical technologies. The current laser power beaming program within the NASA Headquarters Office of Aeronautics and Space Technology is addressed.

  12. Laser cooling of electron beams for linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Telnov, V.

    1996-10-01

    A novel method of electron beam cooling is considered which can be used for linear colliders. The electron beam is cooled during collision with focused powerful laser pulse. With reasonable laser parameters (laser flash energy about 10 J) one can decrease transverse beam emittances by a factor about 10 per one stage. The ultimate transverse emittances are much below that given by other methods. Depolarization of a beam during the cooling is about 5--15% for one stage. This method is especially useful for photon colliders and open new possibilities for e{sup +}e{sup {minus}} colliders and x-ray FEL based on high energy linacs.

  13. Do twisted laser beams evoke nuclear hyperpolarization?

    Science.gov (United States)

    Schmidt, A. B.; Andrews, D. L.; Rohrbach, A.; Gohn-Kreuz, C.; Shatokhin, V. N.; Kiselev, V. G.; Hennig, J.; von Elverfeldt, D.; Hövener, J.-B.

    2016-07-01

    The hyperpolarization of nuclear spins promises great advances in chemical analysis and medical diagnosis by substantially increasing the sensitivity of nuclear magnetic resonance (NMR). Current methods to produce a hyperpolarized sample, however, are arduous, time-consuming or costly and require elaborate equipment. Recently, a much simpler approach was introduced that holds the potential, if harnessed appropriately, to revolutionize the production of hyperpolarized spins. It was reported that high levels of hyperpolarization in nuclear spins can be created by irradiation with a laser beam carrying orbital angular momentum (twisted light). Aside from these initial reports however, no further experimental verification has been presented. In addition, this effect has so far evaded a critical theoretical examination. In this contribution, we present the first independent attempt to reproduce the effect. We exposed a sample of immersion oil or a fluorocarbon liquid that was placed within a low-field NMR spectrometer to Laguerre-Gaussian and Bessel laser beams at a wavelength of 514.5 nm and various topological charges. We acquired 1H and 19F NMR free induction decay data, either during or alternating with the irradiation that was parallel to B0. We observed an irregular increase in NMR signal in experiments where the sample was exposed to beams with higher values of the topological charge. However, at no time did the effect reach statistical significance of 95%. Given the measured sensitivity of our setup, we estimate that a possible effect did not exceed a hyperpolarization (at 5 mT) of 0.14-6%, depending on the assumed hyperpolarized volume. It should be noted though, that there were some differences between our setup and the previous implementation of the experiment, which may have inhibited the full incidence of this effect. To approach a theoretical description of this effect, we considered the interaction of an electron with a plane wave, which is known to be

  14. Simulation of wavefront reconstruction in beam reshaping system for rectangular laser beam

    Science.gov (United States)

    Zhou, Qiong; Liu, Wenguang; Jiang, Zongfu

    2014-05-01

    A new method to calculating the wavefront of slap laser is studied in this paper. The method is based on the ray trace theory of geometrical optics. By using the Zemax simulation software and Matlab calculation software, the wavefront of rectangular beam in beam reshaping system is reconstructed. Firstly, with the x- and y-slope measurement of reshaping beam the direction cosine of wavefront can be calculated. Then, the inverse beam path of beam reshaping system is built by using Zemax simulation software and the direction cosine of rectangular beam can be given, too. Finally, Southwell zonal model is used to reconstruct the wavefront of rectangular beam in computer simulation. Once the wavefront is received, the aberration of laser can be eliminated by using the proper configuration of beam reshaping system. It is shown that this method to reconstruct the wavefront of rectangular beam can evidently reduce the negative influence of additional aberration induced by beam reshaping system.

  15. Editorial: Focus on Laser- and Beam-Driven Plasma Accelerators

    Science.gov (United States)

    Joshi, Chan; Malka, Victor

    2010-04-01

    , S Mangles, L O Silva, R Fonseca and P A Norreys Electro-optic shocks from blowout laser wakefields D F Gordon, A Ting, M H Helle, D Kaganovich and B Hafizi Onset of self-steepening of intense laser pulses in plasmas J Vieira, F Fiúza, L O Silva, M Tzoufras and W B Mori Analysis of laser wakefield dynamics in capillary tubes N E Andreev, K Cassou, F Wojda, G Genoud, M Burza, O Lundh, A Persson, B Cros, V E Fortov and C-G Wahlstrom Characterization of the beam loading effects in a laser plasma accelerator C Rechatin, J Faure, X Davoine, O Lundh, J Lim, A Ben-Ismaïl, F Burgy, A Tafzi, A Lifschitz, E Lefebvre and V Malka Energy gain scaling with plasma length and density in the plasma wakefield accelerator P Muggli, I Blumenfeld, C E Clayton, F J Decker, M J Hogan, C Huang, R Ischebeck, R H Iverson, C Joshi, T Katsouleas, N Kirby, W Lu, K A Marsh, W B Mori, E Oz, R H Siemann, D R Walz and M Zhou Generation of tens of GeV quasi-monoenergetic proton beams from a moving double layer formed by ultraintense lasers at intensity 1021-1023Wcm-2 Lu-Le Yu, Han Xu, Wei-Min Wang, Zheng-Ming Sheng, Bai-Fei Shen, Wei Yu and Jie Zhang Carbon ion acceleration from thin foil targets irradiated by ultrahigh-contrast, ultraintense laser pulses D C Carroll, O Tresca, R Prasad, L Romagnani, P S Foster, P Gallegos, S Ter-Avetisyan, J S Green, M J V Streeter, N Dover, C A J Palmer, C M Brenner, F H Cameron, K E Quinn, J Schreiber, A P L Robinson, T Baeva, M N Quinn, X H Yuan, Z Najmudin, M Zepf, D Neely, M Borghesi and P McKenna Numerical modelling of a 10-cm-long multi-GeV laser wakefield accelerator driven by a self-guided petawatt pulse S Y Kalmykov, S A Yi, A Beck, A F Lifschitz, X Davoine, E Lefebvre, A Pukhov, V Khudik, G Shvets, S A Reed, P Dong, X Wang, D Du, S Bedacht, R Zgadzaj, W Henderson, A Bernstein, G Dyer, M Martinez, E Gaul, T Ditmire and M C Downer Effects of laser prepulses on laser-induced proton generation D Batani, R Jafer, M Veltcheva, R Dezulian, O Lundh, F Lindau, A

  16. Mass Flow Characterization of Selective Deposition of Polymer Powders with Vibrating Nozzles for Laser Beam Melting of Multi-material Components

    Science.gov (United States)

    Stichel, Thomas; Laumer, Tobias; Linnenweber, Tim; Amend, Philipp; Roth, Stephan

    The generation of multi-material components by laser beam melting (LBM) is a challenge which requires the invention of new coating devices for preparation of arbitrary powder patterns. One solution is the usage of vibration-controlled nozzles for selective deposition of polymer powders. Powder flow can be initiated by vibration enabling a start-stop function without using any mechanical shutter. In this report, the delivery of polymer powder by vibrating nozzles is investigated with respect to their application in LBM machines. Therefore, a steel nozzle attached to a piezo actor and a weighing cell is used in order to measure the stability and time-dependence of the powder mass flow upon vibration excitation with the usage of different kind of powder formulations. The results show that precompression of the powder inside the nozzle by vibration excitation is essential to realize a reliable start-stop function with reproducible discharge cyles and to prevent a initial flush of powder flow. Moreover, the use of different powder materials showed that mass flow is even possible with powders which are not optimized regarding flowability, but is readily enhanced with a factor of 2 to 3 by admixing Aerosil® fumed silica.

  17. Comparison study of in vivo dose response to laser-driven versus conventional electron beam.

    Science.gov (United States)

    Oppelt, Melanie; Baumann, Michael; Bergmann, Ralf; Beyreuther, Elke; Brüchner, Kerstin; Hartmann, Josefin; Karsch, Leonhard; Krause, Mechthild; Laschinsky, Lydia; Leßmann, Elisabeth; Nicolai, Maria; Reuter, Maria; Richter, Christian; Sävert, Alexander; Schnell, Michael; Schürer, Michael; Woithe, Julia; Kaluza, Malte; Pawelke, Jörg

    2015-05-01

    The long-term goal to integrate laser-based particle accelerators into radiotherapy clinics not only requires technological development of high-intensity lasers and new techniques for beam detection and dose delivery, but also characterization of the biological consequences of this new particle beam quality, i.e. ultra-short, ultra-intense pulses. In the present work, we describe successful in vivo experiments with laser-driven electron pulses by utilization of a small tumour model on the mouse ear for the human squamous cell carcinoma model FaDu. The already established in vitro irradiation technology at the laser system JETI was further enhanced for 3D tumour irradiation in vivo in terms of beam transport, beam monitoring, dose delivery and dosimetry in order to precisely apply a prescribed dose to each tumour in full-scale radiobiological experiments. Tumour growth delay was determined after irradiation with doses of 3 and 6 Gy by laser-accelerated electrons. Reference irradiation was performed with continuous electron beams at a clinical linear accelerator in order to both validate the dedicated dosimetry employed for laser-accelerated JETI electrons and above all review the biological results. No significant difference in radiation-induced tumour growth delay was revealed for the two investigated electron beams. These data provide evidence that the ultra-high dose rate generated by laser acceleration does not impact the biological effectiveness of the particles.

  18. On-shot laser beam diagnostics for high-power laser facility with phase modulation imaging

    Science.gov (United States)

    Pan, X.; Veetil, S. P.; Liu, C.; Tao, H.; Jiang, Y.; Lin, Q.; Li, X.; Zhu, J.

    2016-05-01

    A coherent-modulation-imaging-based (CMI) algorithm has been employed for on-shot laser beam diagnostics in high-power laser facilities, where high-intensity short-pulsed lasers from terawatt to petawatt are designed to realize inertial confinement fusion (ICF). A single-shot intensity measurement is sufficient for wave-front reconstruction, both for the near-field and far-field at the same time. The iterative reconstruction process is computationally very efficient and was completed in dozens of seconds by the additional use of a GPU device to speed it up. The compact measurement unit—including a CCD and a piece of pre-characterized phase plate—makes it convenient for focal-spot intensity prediction in the target chamber. It can be placed almost anywhere in high-power laser facilities to achieve near-field wave-front diagnostics. The feasibility of the method has been demonstrated by conducting a series of experiments with diagnostic beams and seed pulses with deactivated amplifiers in our high-power laser system.

  19. The generation of high-quality, intense ion beams by ultra-intense lasers

    CERN Document Server

    Roth, M; Audebert, Patrick; Blazevic, A; Brambrink, E; Cowan, T E; Fuchs, J; Gauthier, J C; Geissel, M; Hegelich, M; Karsch, S; Meyer-Ter-Vehn, J; Ruhl, H; Schlegel, T; Stephens, R B

    2002-01-01

    Intense beams of protons and heavy ions have been observed in ultra-intense laser-solid interaction experiments. Thereby, a considerable fraction of the laser energy is transferred to collimated beams of energetic ions (e.g. up to 50 MeV protons; 100 MeV fluorine), which makes these beams highly interesting for various applications. Experimental results indicate a very short-pulse duration and an excellent beam quality, leading to beam intensities in the TW range. To characterize the beam quality and its dependence on laser parameters and target conditions we performed experiments using the 100 TW laser system at Laboratoire pour l'Utilisation des Lasers Intenses at the Ecole Polytechnique, France, with focused intensities exceeding 10 sup 1 sup 9 W cm sup - sup 2. We found a strong dependence on the target rear surface conditions allowing to tailor the ion beam by an appropriate target design. We also succeeded in the generation of heavy ion beams by suppressing the proton amount at the target surface. We wi...

  20. Laser frequency bandwidth narrowing by photorefractive two-beam coupling.

    Science.gov (United States)

    Chomsky, D; Sternklar, S; Zigler, A; Jackel, S

    1992-04-01

    We present a theoretical analysis and experimental demonstration of a new method for spectral narrowing of laser radiation. The bandwidth narrowing is experienced by a laser beam subjected to a photorefractive two-beam coupling process. Contrary to the conventional method of frequency filtering by a Fabry-Perot étalon, this technique has no intrinsic finesse limitation on its resolution. A factor of 2 in frequency bandwidth narrowing is achieved with an argon-ion laser.

  1. Simulation of Laser-Compton Cooling of Electron Beams

    OpenAIRE

    Ohgaki, T.

    2000-01-01

    We study a method of laser-Compton cooling of electron beams. Using a Monte Carlo code, we evaluate the effects of the laser-electron interaction for transverse cooling. The optics with and without chromatic correction for the cooling are examined. The laser-Compton cooling for JLC/NLC at E_0=2 GeV is considered.

  2. The study of laser beam riding guided system based on 980nm diode laser

    Science.gov (United States)

    Qu, Zhou; Xu, Haifeng; Sui, Xin; Yang, Kun

    2015-10-01

    With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

  3. Amplitude and phase characterization by diffracted beam interferometry: blind dbi

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Lago, E; Gonzalez Nunez, H; De la Fuente, R, E-mail: elena.lopez.lago@usc.es [Departamento de Fisica Aplicada, Escuela Universitaria de Optica y Optometria, Campus Vida, Universidade of Santiago de Compostela, E-15782 Santiago de Compostela, Galicia (Spain)

    2011-01-01

    Diffracted beam interferometry is a self referenced method characterization technique whose operation principle is based on the reconstruction of the phase of a beam starting from the interference data between the beam and its diffracted copy. The phase is recovered indirectly by means of an iterative algorithm that relates the irradiances of the interfering beams and its phase difference. The first experimental demonstration of DBI was implemented on a Mach-Zehnder interferometer which incorporated an afocal imaging system in each arm, in order to form an image of a common object in different planes at the output of the interferometer. The irradiance data as well as the phase difference data were picked up from one of the image planes and they were introduced in the iterative algorithm. In this work we discuss a modification of the algorithm that allows to reconstruct simultaneously the amplitude and phase of the wavefront starting from, exclusively, the phase difference between the two waves that interfere in one of the image planes. This new algorithm improves the reconstruction process because the data acquisition process is faster and consequently the method is less influenced by environment disturbances. The method has been applied successfully to the characterization of phase plates and laser beams as well as to the local characterization of ophthalmic lenses.

  4. Pengukuran Daya Laser CO2 Dan Laser DPSS Serta Pengamatan Beam Profiler Sinar Laser DPSS dan Laser He-Ne Menggunakan CCD

    OpenAIRE

    2015-01-01

    This research has done measuring the power by varying the current of laser CO2 and laser DPSS, observation the beam profiler of laser beam DPSS and laser beam He-Ne and observation the spectrum wavelength of laser DPSS and laser He-Ne. In this case of measuring the power by varying the current of laser CO2 and laser DPSS, the measuring has done more than once in order to concluded how the stability of the power that produced by each of the laser. The result of this measuring is laser DPSS ...

  5. Ion-beam assisted laser fabrication of sensing plasmonic nanostructures

    Science.gov (United States)

    Kuchmizhak, Aleksandr; Gurbatov, Stanislav; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

    2016-01-01

    Simple high-performance, two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique, a thin noble-metal film on a dielectric substrate is irradiated by a single tightly focused nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar+) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar+-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depend on the laser pulse energy and metal film thickness, while subsequent Ar+-ion polishing enables to vary height of the resulting nanostructures. Plasmonic properties of the fabricated nanostructures were characterized by dark-field micro-spectroscopy, Raman and photoluminescence measurements performed on single nanofeatures, as well as by supporting numerical calculations of the related electromagnetic near-fields and Purcell factors. The developed simple two-stage technique represents a new step towards direct large-scale laser-induced fabrication of highly ordered arrays of complex plasmonic nanostructures.

  6. Stability of a Light Sail Riding on a Laser Beam

    CERN Document Server

    Manchester, Zachary

    2016-01-01

    The stability of a light sail riding on a laser beam is analyzed both analytically and numerically. Conical sails on Gaussian beams, which have been studied in the past, are shown to be unstable in general. A new architecture for a passively stable sail and beam configuration is proposed. The novel spherical shell sail design is capable of "beam riding" without the need for active feedback control. Full three-dimensional ray-tracing simulations are performed to verify our analytical results.

  7. Mode correlation and coherent-mode decomposition of laser beams

    Institute of Scientific and Technical Information of China (English)

    张彬; 文侨; 楚晓亮

    2003-01-01

    Theory of the coherent-mode decomposition of laser beams is proposed.The new model for the flat-topped beams proposed by Li recently is taken as an example.The analytical expressions for the M2-factor and mode coherence coefficients of flat-topped beams have been derived in the rectangular coordinate system,by means of which the mode correlation,mode structure,and coherent-mode decomposition of flat-topped beams can be analysed.

  8. Laser beams as fiducial lines in bubble chambers

    CERN Document Server

    Leutz, H; Klamann, H; Muuss, H; Schmelzer, C

    1971-01-01

    It is proposed to base the fiduciary system of large volume bubble chambers on laser beams originating from theodolite-fixed positions and thus traversing the liquid at well defined space coordinates. From a series of experiments some important conditions for this proposal have been established: Rayleigh-scattering on molecular concentration fluctuations in the chamber liquid is responsible for the visibility of laser beams which can be photographed under angles up to 90 degrees within reasonable exposures. Small-angle random deflections of the laser beam were observed which are due to thermal turbulence in the chamber liquid.

  9. Evaluation of thermal effects on the beam quality of disk laser with unstable resonator

    Science.gov (United States)

    Shayganmanesh, Mahdi; Beirami, Reza

    2017-01-01

    In this paper thermal effects of the disk active medium and associated effects on the beam quality of laser are investigated. Using Collins integral and iterative method, transverse mode of an unstable resonator including a Yb:YAG active medium in disk geometry is calculated. After that the beam quality of the laser is calculated based on the generalized beam characterization method. Thermal lensing of the disk is calculated based on the OPD (Optical Path Difference) concept. Five factors influencing the OPD including temperature gradient, disk thermal expansion, photo-elastic effect, electronic lens and disk deformation are considered in our calculations. The calculations show that the effect of disk deformation factor on the quality of laser beam in the resonator is strong. However the total effect of all the thermal factors on the internal beam quality is fewer. Also it is shown that thermal effects degrade the output power, beam profile and beam quality of the output laser beam severely. As well the magnitude of each of affecting factors is evaluated distinctly.

  10. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    Science.gov (United States)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  11. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Scisciò, M.; Antici, P., E-mail: patrizio.antici@polytechnique.edu [INFN-RM1 and SBAI, Università di Roma “La Sapienza,” Via Scarpa 16, 00161 Roma (Italy); INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes, Québec J3X 1S2 (Canada); Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L. [INFN-RM1 and SBAI, Università di Roma “La Sapienza,” Via Scarpa 16, 00161 Roma (Italy); Papaphilippou, Y. [CERN, CH 1211 Geneva 23 (Switzerland)

    2016-03-07

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  12. Photothermal single particle microscopy using a single laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Selmke, Markus; Heber, André; Braun, Marco; Cichos, Frank, E-mail: cichos@physik.uni-leipzig.de [Molecular Nanophotonics Group, Institute of Experimental Physics I, Universität Leipzig, 04103 Leipzig (Germany)

    2014-07-07

    We introduce a single-laser-beam photothermal microscopy scheme for the detection of single absorbing nano-objects. Here, a modulated incident laser beam with a constant intensity offset serves as pump and probe beam at the same time. Using the out-of-phase scattering response of the retarded thermorefractive wave field, the method provides a selective contrast for absorbers over a possible background of scatterers. The use of a single wavelength and a single beam, considerably simplifies the setup and integration of photothermal detection in existing microscopy schemes.

  13. Relativistic electron vortex beams in a laser field

    CERN Document Server

    Bandyopadhyay, Pratul; Chowdhury, Debashree

    2015-01-01

    The orbital angular momentum Hall effect and spin Hall effect of electron vortex beams (EVB) have been studied for the EVBs interacting with laser field. In the scenario of paraxial beam, the cumulative effect of the orbit-orbit interaction of EVBs and laser fields drives the orbital Hall effect, which in turn produces a shift of the center of the beam from that of the field-free case towards the polarization axis of photons. Besides, for non-paraxial beams one can also perceive a similar shift of the center of the beam owing to spin Hall effect involving spin-orbit interaction. Our analysis suggests that the shift in the paraxial beams will always be larger than that in non-paraxial beams.

  14. Genomic Physics. Multiple Laser Beam Treatment of Alzheimer's Disease

    Science.gov (United States)

    Stefan, V. Alexander

    2014-03-01

    The synapses affected by Alzheimer's disease can be rejuvenated by the multiple ultrashort wavelength laser beams.[2] The guiding lasers scan the whole area to detect the amyloid plaques based on the laser scattering technique. The scanning lasers pinpoint the areas with plaques and eliminate them. Laser interaction is highly efficient, because of the focusing capabilities and possibility for the identification of the damaging proteins by matching the protein oscillation eigen-frequency with laser frequency.[3] Supported by Nikola Tesla Labs, La Jolla, California, USA.

  15. Laser ion source for high brightness heavy ion beam

    Science.gov (United States)

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. However we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. In 2014, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory. Now most of all the solid based heavy ions are being provided from the laser ion source for regular operation.

  16. Activation of cells using femtosecond laser beam (Conference Presentation)

    Science.gov (United States)

    Batabyal, Subrata; Satpathy, Sarmishtha; Kim, Young-tae; Mohanty, Samarendra K.

    2016-03-01

    Study of communication in cellular systems requires precise activation of targeted cell(s) in the network. In contrast to chemical, electrical, thermal, mechanical stimulation, optical stimulation is non-invasive and is better suited for stimulation of targeted cells. As compared to visible lasers, the near infrared (NIR) microsecond/nanosecond pulsed laser beams are being used as preferred stimulation tool as they provide higher penetration depth in tissues. Femotosecond (FS) laser beams in NIR are also being used for direct and indirect (i.e. via two-photon optogenetics) stimulation of cells. Here, we present a comparative evaluation of efficacy of NIR FS laser beam for direct (no optogenetic sensitization) and 2ph optogenetic stimulation of cells. Further, for the first time, we demonstrate the use of blue (~450 nm, obtained by second harmonic generation) FS laser beam for stimulation of cells with and without Channelrhodopisn-2 (ChR2) expression. Comparative analysis of photocurrent generated by blue FS laser beam and continuous wave blue light for optogenetics stimulation of ChR2 transfected HEK cells will be presented. The use of ultrafast laser micro-beam for focal, non-contact, and repeated stimulation of single cells in a cellular circuitry allowed us to study the communication between different cell types.

  17. Influence of laser array performance on spectrally combined beam

    Science.gov (United States)

    Wu, Zhen; Yang, Lei; Zhong, Zheqiang; Zhang, Bin

    2016-10-01

    Incoherent spectral beam combining (SBC) of multiple laser beams is accomplished along the emitters' arraying direction. Considering that the output beams from a laser array (LA) usually have deflection angles, positional displacements and divergence angles even after being collimated, a propagation model of SBC systems based on multilayer dielectric gratings has been built up. On the basis, properties of the spectrally combined beam affected by parameters of the LA have been discussed in detail. Simulation results show that with the increase in the deflection angle, both the power and the beam quality of the combined beam degrade dramatically. The positional displacement has little impact on the intensity distribution and the beam quality of combined beam but change the wavelength composition of the combined beam. The divergence angle strongly affects the intensity distribution and the beam quality of the combined beam. Additionally, the effect of the deflection angle on the output beam quality is more obvious and may shift the beam spot when comparing with that of the divergence angle.

  18. Laser Beam Welding with High-Frequency Beam Oscillation: Welding of Dissimilar Materials with Brilliant Fiber Lasers

    Science.gov (United States)

    Kraetzsch, Mathias; Standfuss, Jens; Klotzbach, Annett; Kaspar, Joerg; Brenner, Berndt; Beyer, Eckhard

    Brilliant laser beam sources in connection with a high frequent beam oscillation make it now possible to join metallic material combinations, which have been conventionally non-laser weldable up to now. It concerns especially such combinations like Al- Cu, where brittle intermetallic phases occur. Extreme small weld seam with high aspect ratio leads to very short meld pool life time. These allow an extensive reduction of the heat input. On the other side the melting behavior at metallic mixed joint, seam geometry, meld pool turbulence and solidification behavior can be influenced by a high frequent time-, position- and powercontrolled laser beam oscillation.

  19. DPSS Laser Beam Quality Optimization Through Pump Current Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Omohundro, Rob; /Newport Spectra-Physics, Santa Clara; Callen, Alice; /SLAC; Sukuta, Sydney; /San Jose City Coll.

    2012-03-30

    The goal of this study is to demonstrate how a DPSS laser beam's quality parameters can be simultaneously optimized through pump current tuning. Two DPSS lasers of the same make and model were used where the laser diode pump current was first varied to ascertain the lowest RMS noise region. The lowest noise was found to be 0.13% in this region and the best M{sup 2} value of 1.0 and highest laser output power were simultaneously attained at the same current point. The laser manufacturer reported a M{sup 2} value of 1.3 and RMS noise value of .14% for these lasers. This study therefore demonstrates that pump current tuning a DPSS laser can simultaneously optimize RMS Noise, Power and M{sup 2} values. Future studies will strive to broaden the scope of the beam quality parameters impacted by current tuning.

  20. Sorting and quantifying orbital angular momentum of laser beams

    CSIR Research Space (South Africa)

    Schulze, C

    2013-10-01

    Full Text Available We present a novel tool for sorting the orbital angular momentum and to determine the orbital angular momentum density of laser beams, which is based on the use of correlation filters....

  1. Dynamic photonic crystals dimensionality tuning by laser beams polarization changing

    Science.gov (United States)

    Golinskaya, Anastasia D.; Stebakova, Yulia V.; Valchuk, Yana V.; Smirnov, Aleksandr M.; Mantsevich, Vladimir N.

    2017-05-01

    A simple way to create dynamic photonic crystals with different lattice symmetry by interference of non-coplanar laser beams in colloidal solution of quantum dots was demonstrated. With the proposed technique we have made micro-periodic dynamic semiconductor structure with strong nonlinear changing of refraction and absorption and analyzed the self-diffraction processes of two, three and four non-coplanar laser beams at the dynamic photonic crystal (diffraction grating) with hexagonal lattice structure. To reach the best uniform contrast of the structure and for better understanding of the problems, specially raised by the interference of multiple laser beams theoretical calculation of the periodic intensity field in the QDs solution were performed. It was demonstrated that dynamic photonic crystal structure and even it's dimension can be easily tuned with a high speed by the laser beams polarization variation without changing the experimental setup geometry.

  2. Laser beam propagation generation and propagation of customized light

    CERN Document Server

    Forbes, Andrew

    2014-01-01

    ""The text is easy to read and is accompanied by beautiful illustrations. It is an excellent book for anyone working in laser beam propagation and an asset for any library.""-Optics & Photonics News, July 2014

  3. Intense high-quality medical proton beams via laser fields

    CERN Document Server

    Galow, Benjamin J; Keitel, Christoph H

    2010-01-01

    Simulations based on the coupled relativistic equations of motion show that protons stemming from laserplasma processes can be efficiently post-accelerated employing crossed pulsed laser beams focused to spot radii on the order of the laser wavelength. We demonstrate that the crossed beams produce quasi-monoenergetic accelerated protons with kinetic energies exceeding 200 MeV, small energy spreads of about 1% and high densities as required for hadron cancer therapy.

  4. Theoretical tools for atom-laser-beam propagation

    OpenAIRE

    Riou, Jean-Félix; Le Coq, Yann; Impens, François; Guerin, William; Bordé, Christian,; Aspect, Alain; Bouyer, Philippe

    2008-01-01

    We present a theoretical model for the propagation of non self-interacting atom laser beams. We start from a general propagation integral equation, and we use the same approximations as in photon optics to derive tools to calculate the atom laser beam propagation. We discuss the approximations that allow to reduce the general equation whether to a Fresnel-Kirchhoff integral calculated by using the stationary phase method, or to the eikonal. Within the paraxial approximation, we also introduce...

  5. Polarization/Spatial Combining of Laser-Diode Pump Beams

    Science.gov (United States)

    Gelsinger, Paul; Liu, Duncan

    2008-01-01

    A breadboard version of an optical beam combiner is depicted which make it possible to use the outputs of any or all of four multimode laser diodes to pump a non-planar ring oscillator (NPRO) laser. The output of each laser diode has a single-mode profile in the meridional plane containing an axis denoted the 'fast' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis. One of the purposes served by the beam-combining optics is to reduce the fast-axis numerical aperture (NA) of the laser-diode output to match the NA of the optical fiber. Along the slow axis, the unmodified laser-diode NA is already well matched to the fiber optic NA, so no further slow-axis beam shaping is needed. In this beam combiner, the laser-diode outputs are collimated by aspherical lenses, then half-wave plates and polarizing beam splitters are used to combine the four collimated beams into two beams. Spatial combination of the two beams and coupling into the optical fiber is effected by use of anamorphic prisms, mirrors, and a focusing lens. The anamorphic prisms are critical elements in the NA-matching scheme, in that they reduce the fast-axis beam width to 1/6 of its original values. Inasmuch as no slow-axis beam shaping is needed, the collimating and focusing lenses are matched for 1:1 iumaging. Because these lenses are well corrected for infinite conjugates the combiner offers diffraction-limited performance along both the fast and slow axes.

  6. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    Science.gov (United States)

    Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  7. Generation of monoenergetic ion beams with a laser accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Pfotenhauer, Sebastian M.

    2009-01-29

    A method for the generation of monoenergetic proton and ion beams from a laser-based particle accelerator is presented. This method utilizes the unique space-charge effects occurring during relativistic laser-plasma interactions on solid targets in combination with a dot-like particle source. Due to this unique interaction geometry, MeV proton beams with an intrinsically narrow energy spectrum were obtained, for the first time, from a micrometer-scale laser accelerator. Over the past three years, the acceleration scheme has been consistently improved to enhance both the maximum particle energy and the reliability of the setup. The achieved degree of reliability allowed to derive the first scaling laws specifically for monoenergetic proton beams. Furthermore, the acceleration scheme was expanded on other target materials, enabling the generation of monoenergetic carbon beams. The experimental work was strongly supported by the parallel development of a complex theoretical model, which fully accounts for the observations and is in excellent agreement with numerical simulations. The presented results have an extraordinarily broad scope way beyond the current thesis: The availability of monoenergetic ion beams from a compact laser-plasma beam source - in conjunction with the unique properties of laser-produced particle beams - addresses a number of outstanding applications in fundamental research, material science and medical physics, and will help to shape a new generation of accelerators. (orig.)

  8. Active beam integrator for high power coherent lasers

    Energy Technology Data Exchange (ETDEWEB)

    Laguarta, F.; Armengol, J.; Vega, F.; Lupon, N. [Univ. Politecnica de Catalunya, Terrassa (Spain). Dept. d`Optica i Optometria

    1996-12-31

    In laser materials processing applications it is often necessary to work with uniform intensity distributions. This goal is quite difficult to achieve when dealing with high power laser beams, and becomes critical for a successful application involving surface heat treatment of non-metallic materials. The authors have designed and tested a very simple beam shaper for transforming the initial intensity distribution of a CO{sub 2} laser beam mode into a more uniform intensity profile. The beam shaper is a two-faceted mirror for active integration of high power coherent laser beams. After reflection in the faceted mirror, a TEM00 or TEM01 CO{sub 2} laser beam is divided into two beamlets that overlap to give a more uniform intensity distribution. A sharp interference pattern due to the high spatial coherence of the incident beam appears. This interference pattern is actively integrated by a high-frequency longitudinal displacement of one of the facets. This provides a change in the relative phase of the two beamlets, and consequently the interference pattern vibrates and its contribution to the intensity distribution averages out. When sweeping this distribution over a sample, a uniform amount of energy is deposited at every point of its surface. It must be emphasized that unlike multifaceted mirrors, the two-facet integrator may provide uniform intensity profiles over any working distance. Finally, as in other integration devices an imaging system may be used to obtain a spot of the shape and the size desired for a particular application.

  9. Laser forming of a bowl shaped surface with a stationary laser beam

    Science.gov (United States)

    Chakraborty, Shitanshu Shekhar; More, Harshit; Nath, Ashish Kumar

    2016-02-01

    Despite a lot of research done in the field of laser forming, generation of a symmetric bowl shaped surface by this process is still a challenge mainly because only a portion of the sheet is momentarily deformed in this process, unlike conventional sheet metal forming like deep drawing where the entire blank undergoes forming simultaneously reducing asymmetry to a minimum. The motion of laser beam also makes the process asymmetric. To counter these limitations this work proposes a new approach for laser forming of a bowl shaped surface by irradiating the centre of a flat circular blank with a stationary laser beam. With high power lasers, power density sufficient for laser forming, can be availed at reasonably large spot sizes. This advantage is exploited in this technique. Effects of duration of laser irradiation and beam spot diameter on the amount of bending and asymmetry in the formed surface were investigated. Laser power was kept constant while varying irradiation time. While varying laser spot diameter laser power was chosen so as to keep the surface temperature nearly constant at just below melting. Experimental conditions promoted almost uniform heating through sheet thickness. The amount of bending increased with irradiation time and spot diameter. It was interesting to observe that blanks bent towards the laser beam for smaller laser beam diameters and the reverse happened for larger spot diameters (~10 times of the sheet thickness). Effect of spot diameter variation has been explained with the help of coupled thermal-structural finite element simulations.

  10. Design of Extended Depth-of-Focus Laser Beams Using Orthogonal Beam Expansions

    Directory of Open Access Journals (Sweden)

    Leonard Bergstein

    2005-06-01

    Full Text Available Laser beams with extended depth of focus have many practical applications, such as scanning printed bar codes. Previous work has concentrated on synthesizing such beams by approximating the nondiffracting Bessel beam solution to the wave equation. In this paper, we introduce an alternate novel synthesis method that is based on maintaining a minimum MTF value (contrast over the largest possible distance. To achieve this, the coefficients of an orthogonal beam expansion are sequentially optimized to this criterion. One of the main advantages of this method is that it can be easily generalized to noncircularly symmetrical beams by the appropriate choice of the beam expansion basis functions. This approach is found to be very useful for applications that involve scanning of the laser beam.

  11. Optimization of beam transformation system for laser-diode bars.

    Science.gov (United States)

    Yu, Junhong; Guo, Linhui; Wu, Hualing; Wang, Zhao; Gao, Songxin; Wu, Deyong

    2016-08-22

    An optimized beam transformation system (BTS) is proposed to improve the beam quality of laser-diode bars. Through this optimized design, the deterioration of beam quality after the BTS can be significantly reduced. Both the simulation and experimental results demonstrate that the optimized system enables the beam quality of a mini-bar (9 emitters) approximately equal to 5.0 mm × 3.6 mrad in the fast-axis and slow-axis. After beam shaping by the optimized BTS, the laser-diode beam can be coupled into a 100 μm core, 0.15 numerical aperture (NA) fiber with an output power of over 100 W and an electric-optical efficiency of 46.8%.

  12. Laser beam complex amplitude measurement by phase diversity.

    Science.gov (United States)

    Védrenne, Nicolas; Mugnier, Laurent M; Michau, Vincent; Velluet, Marie-Thérèse; Bierent, Rudolph

    2014-02-24

    The control of the optical quality of a laser beam requires a complex amplitude measurement able to deal with strong modulus variations and potentially highly perturbed wavefronts. The method proposed here consists in an extension of phase diversity to complex amplitude measurements that is effective for highly perturbed beams. Named camelot for Complex Amplitude MEasurement by a Likelihood Optimization Tool, it relies on the acquisition and processing of few images of the beam section taken along the optical path. The complex amplitude of the beam is retrieved from the images by the minimization of a Maximum a Posteriori error metric between the images and a model of the beam propagation. The analytical formalism of the method and its experimental validation are presented. The modulus of the beam is compared to a measurement of the beam profile, the phase of the beam is compared to a conventional phase diversity estimate. The precision of the experimental measurements is investigated by numerical simulations.

  13. Vectorial rotating vortex Hankel laser beams

    Science.gov (United States)

    Kotlyar, Victor V.; Kovalev, Alexey A.; Soifer, Victor A.

    2016-09-01

    We propose a generalization of spherical waves in the form of linearly polarized beams with embedded optical vortices. The source of these beams is an infinitely narrow light ring with an infinitely small radius. These vectorial beams are obtained based on scalar Hankel beams discovered by the authors recently. We have derived explicit relations for complex amplitudes of all six components of vectorial vortex Hankel beams. A closed analytical expression for the axial projection of the orbital angular momentum density in far field has been obtained. We also showed that the intensity distribution of the electric vector rotates by 90 degrees upon the beam propagation in near field.

  14. Optoelectronic materials for subwavelength imaging and laser beam maniupulation

    Science.gov (United States)

    Krishnamurthi, Mahesh

    2010-11-01

    Metamaterials are artificially engineered materials for providing properties which are not readily available in nature. In the last decade, research activity in the field of metamaterials has led to diverse applications including remote sensing, lithography, communication, and biological imaging. For instance, researchers have shown that a class of metamaterials exhibit negative refraction and have also utilized this phenomenon to enable a super lens for beating the diffraction limit of light. Other fascinating developments include optical cloaking devices which involves bending of the electromagnetic waves completely around the objects. Therefore, metamaterials have become an important subject for study. The central focus of this thesis is primarily on two applications of metamaterials: sub-wavelength imaging and laser beam manipulation. The proof-ofconcept of sub-wavelength imaging has been demonstrated in the mid-infrared regime. A tapered array of step-index cylindrical waveguides is the basis for the magnifying infrared fiberscope. Optimized designs have been presented for the proposed infrared fiberscope by numerical modeling. The fabrication of the fiberscope is based on a high pressure chemical fluid deposition technique to deposit precisely defined periodic arrays of semiconductor waveguides within the holes of a microstructured optical fiber made of silica. The optical properties of various waveguides (germanium, silicon, zinc selenide, silicon nitride) fabricated by this method have been characterized in the infrared regime. The basic essential features of an imaging fiber bundle such as isolation between adjacent pixels, magnification, optical throughput and near-field image transfer characteristics have been investigated. The imaging concept is demonstrated at 1.55 mum, 3.39 mum and 10.64 mum using appropriate materials for fabricating the tapered array of waveguides to maximize the optical throughput. Manipulation of the laser beam has been

  15. A study of laser-beam welding conducted at the Centre for Laser Technologies of Metals

    Science.gov (United States)

    Antoszewski, Bogdan; Gradoń, Ryszard; Trela, Paweł; Cendrowicz, Edward

    2013-01-01

    The study reported here is part of a larger research project on laser-beam welding conducted at the Centre for Laser Technologies of Metals. The primary objectives were to compare laser-beam welding with a conventional process when used for longitudinal seams in street lamp posts, to select the process parameters for girth welds in cylindrical high-strength steel machine elements, and to assess whether laser-beam welding can be used for magnesium alloys. The paper includes recommendations for the selection of welding parameters.

  16. Beam Characterization at the Neutron Radiography Facility

    Energy Technology Data Exchange (ETDEWEB)

    Sarah Morgan; Jeffrey King

    2013-01-01

    The quality of a neutron imaging beam directly impacts the quality of radiographic images produced using that beam. Fully characterizing a neutron beam, including determination of the beam’s effective length-to-diameter ratio, neutron flux profile, energy spectrum, image quality, and beam divergence, is vital for producing quality radiographic images. This project characterized the east neutron imaging beamline at the Idaho National Laboratory Neutron Radiography Reactor (NRAD). The experiments which measured the beam’s effective length-to-diameter ratio and image quality are based on American Society for Testing and Materials (ASTM) standards. An analysis of the image produced by a calibrated phantom measured the beam divergence. The energy spectrum measurements consist of a series of foil irradiations using a selection of activation foils, compared to the results produced by a Monte Carlo n-Particle (MCNP) model of the beamline. Improvement of the existing NRAD MCNP beamline model includes validation of the model’s energy spectrum and the development of enhanced image simulation methods. The image simulation methods predict the radiographic image of an object based on the foil reaction rate data obtained by placing a model of the object in front of the image plane in an MCNP beamline model.

  17. CERN's web application updates for electron and laser beam technologies

    CERN Document Server

    Sigas, Christos

    2017-01-01

    This report describes the modifications at CERN's web application for electron and laser beam technologies. There are updates at both the front and the back end of the application. New electron and laser machines were added and also old machines were updated. There is also a new feature for printing needed information.

  18. Cold atom dynamics in crossed laser beam waveguides

    CERN Document Server

    Torrontegui, E; Ruschhaupt, A; Guéry-Odelin, D; Muga, J G

    2010-01-01

    We study the dynamics of neutral cold atoms in an $L$-shaped crossed-beam optical waveguide formed by two perpendicular red-detuned lasers of different intensities and a blue-detuned laser at the corner. Complemented with a vibrational cooling process this setting works as a one-way device or "atom diode".

  19. A high brightness electron beam for Free Electron Lasers

    NARCIS (Netherlands)

    Oerle, van Bartholomeus Mathias

    1997-01-01

    In a free electron laser, coherent radiation is generated by letting an electron beam propagate through an alternating magnetic field. The magnetic field is created by a linear array of magnets, which is called an undulator or a wiggler. The wavelength of the laser radiation depends on the amplitude

  20. Optimization of Laser Beam Transformation Hardening by One Single Parameter

    NARCIS (Netherlands)

    Meijer, J.; Sprang, van I.

    1991-01-01

    The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth.

  1. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Chen, L. M., E-mail: lmchen@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, D. Z. [Institute of High Energy Physics, CAS, Beijing 100049 (China); Chen, Z. Y. [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621999 (China); Sheng, Z. M. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, J. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  2. Laser beam steering approaches for microstructuring of copper layers

    Science.gov (United States)

    Mur, Jaka; Podobnik, Boštjan; Poberaj, Igor

    2017-02-01

    We have investigated the process of copper layer ablation with a tightly focused Q-switched 532 nm laser. Focusing 40 ns long laser pulses to a micrometer-sized spot results in high energy density and gives rise to ablation phenomena not seen during laser processing with larger beam diameters. Use of acousto-optic deflectors (AODs) enabled us to test different laser beam steering approaches in terms of choosing the position for each laser pulse independently of the previous pulses. Random addressing of desired positions across a microstructure proved to be the most efficient method compared to various scanning approaches. Assigning a random order to the spatial sequence of laser pulses resulted in the fastest microstructuring process and featured lowest residual heating of the substrate.

  3. Helium-tight Laser Beam Welding of Aluminum with Brillant Laser Beam Radiation

    Science.gov (United States)

    Heinen, Paul; Wu, Hao; Olowinsky, Alexander; Gillner, Arnold

    The substitution of steel as base metal for casings and packaging applications has increased during the last years. Especially aluminum with advantages in weight and machining effort has become a versatile solution for applications in fine mechanics (e.g. sensor housings) and automotive applications. Joining of aluminum components is more critical due to possible crack formation in the joining seam and uneven seam geometry. With the high intensity of brillant laser beam sources the specific challenges of aluminum welding can be overcome. Due to its hydrogen affinity and high degree of reflection for laser radiation at a wavelength of 1 μm (95%) aluminum needs to be welded with proper shielding gas support and high beam quality in order to avoid seam defects. Cracks and pores can lead to non-sufficient tightness for sensor applications and early failure. Housing components have been joined to form a functioning unit in order to seal electrical or measuring components, which are helium-tight for these applications.

  4. Using submicron-resolution LiF crystal and film x-ray detectors for the near and far fields in-situ characterization of soft x-ray laser beams

    Science.gov (United States)

    Pikuz, Tatiana A.; Faenov, Anatoly Y.; Fukuda, Yuji; Kato, Yoshiaki; Kawachi, Tetsuya; Kando, Masaki

    2012-01-01

    Review of results, obtained by using recently proposed new imaging detector, based on formation of color centers in LiF crystal and LiF film, for in situ high performance measurements of near-field and far-field properties of soft X-ray lasers (SXRL) beams is presented. Experiments have been carried out with laser-driven transient-collision plasma SXRL and free electron SXRL beams. It was demonstrated that due to favorable combination of high spatial resolution, high dynamic range and wide field of view this technique allows measuring not only intensity distribution across the full beam and in local areas, but also permits to evaluate coherence and spectral distribution of radiation across the beam. Experimental diffraction patterns in the images of periodical structures are analyzed by comparison with the modeled ones in the last case. The estimated accuracy of measurements is between 10-20%.

  5. Laser beam splitting by polarization encoding.

    Science.gov (United States)

    Wan, Chenhao

    2015-03-20

    A scheme is proposed to design a polarization grating that splits an incident linearly polarized beam to an array of linearly polarized beams of identical intensity distribution and various azimuth angles of linear polarization. The grating is equivalent to a wave plate with space-variant azimuth angle and space-variant phase retardation. The linear polarization states of all split beams make the grating suitable for coherent beam combining architectures based on Dammann gratings.

  6. New method of beam bunching in free-ion lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bessonov, E.G. [Lebedev Physics Institute, Moscow (Russian Federation)

    1995-12-31

    An effective ion beam bunching method is suggested. This method is based on a selective interaction of line spectrum laser light (e.g. axial mode structure light) with non-fully stripped ion beam cooled in a storage rings, arranging the ion beam in layers in radial direction of an energy-longitudinal coordinate plane and following rotation of the beam at the right angle after switching on the RF cavity or undulator grouper/buncher. Laser cooling of the ion beam can be used at this position after switching off the resonator to decrease the energy spread caused by accelerating field of the resonator. A relativistic multilayer ion mirror will be produced this way. Both monochromatic laser beams and intermediate monochromaticity and bandwidth light sources of spontaneous incoherent radiation can be used for production of hard and high power electromagnetic radiation by reflection from this mirror. The reflectivity of the mirror is rather high because of the cross-section of the backward Rayleigh scattering of photon light by non-fully stripped relativistic ions ({approximately}{lambda}{sup 2}) is much greater ({approximately} 10{divided_by}15 orders) then Thompson one ({approximately} r{sub e}{sup 2}). This position is valid even in the case of non-monochromatic laser light ({Delta}{omega}/{omega} {approximately} 10{sup -4}). Ion cooling both in longitudinal plane and three-dimensional radiation ion cooling had been proposed based on this observation. The using of these cooling techniques will permit to store high current and low emittance relativistic ion beams in storage rings. The bunched ion beam can be used in ordinary Free-Ion Lasers as well. After bunching the ion beam can be extracted from the storage ring in this case. Storage rings with zero momentum compaction function will permit to keep bunching of the ion beam for a long time.

  7. Wavelength tuneable laser beam shaping optics

    CSIR Research Space (South Africa)

    Forbes, A

    2006-07-01

    Full Text Available -4 -2 0 2 4 6 8 10 I n t e n s i t y [ a r b u n i t s ] Ga us sia n w ais t o ffs et [m] Cross-section [cm] Phase, beam size and beam shape Beam Quality Page 12 © CSIR 2006 www...

  8. Fabrication of patterned mirror modules for generating laser line beams

    Science.gov (United States)

    Lee, Changyun; Kim, Taeggyum; Hong, Sangsu; Kim, Baekyun

    2008-02-01

    A method for fabricating Ag coated beam splitter is reported. This is showing specific patterned transmittance by immersing glass substrates in the mixture of H IISO 4 and H IIO II to make negatively charged oxygen sites at silica surface and then in ethanolic solutions of AgNO 3 and butylamine. We controlled the soaking time and molar ratios of the mixture of AgNO 3 and butylamine to pattern % transmittance of electroless coated glass surface. Finally, we made a functionalized beam splitters showing step function like transmittance and applied this to make multiple laser beams for display and laser machining.

  9. Beam quality requirements for the Ion-Channel Laser

    CERN Document Server

    Davoine, X; Fonseca, R A; Mori, W B; Silva, L O

    2014-01-01

    In this paper, we determine the electron beam quality requirements to obtain exponential radiation amplification in the ion-channel laser, where a relativistic electron beam wiggles in a focusing ion-channel that can be created in a wakefield accelerator. The beam energy and wiggler parameter spreads should be limited. Those spread limits are functions of the Pierce parameter, which is calculated here without neglecting the radiation diffraction. Two dimensional and three dimensional simulations of the self-consistent ion-channel laser confirm our theoretical predictions.

  10. Vortex beam characterization in terms of Hypergeometric- Gaussian modes

    CSIR Research Space (South Africa)

    Sephton, Bereneice C

    2016-10-01

    Full Text Available stream_source_info Sephton_18560_2016.pdf.txt stream_content_type text/plain stream_size 580 Content-Encoding ISO-8859-1 stream_name Sephton_18560_2016.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Frontiers... in Optics: The 100th OSA Annual Meeting and Exhibit/Laser Science XXXII , 17-21 October 2016, Rochester Riverside Convention Center, Rochester, New York United States Vortex beam characterization in terms of Hypergeometric- Gaussian modes Sephton...

  11. A multibeam atom laser: coherent atom beam splitting from a single far detuned laser

    OpenAIRE

    Dugué, J.; Dennis, G.; Jeppesen, M.; Johnsson, M. T.; Figl, C.; Robins, N. P.; Close, J. D.

    2007-01-01

    We report the experimental realisation of a multibeam atom laser. A single continuous atom laser is outcoupled from a Bose-Einstein condensate (BEC) via an optical Raman transition. The atom laser is subsequently split into up to five atomic beams with slightly different momenta, resulting in multiple, nearly co-propagating, coherent beams which could be of use in interferometric experiments. The splitting process itself is a novel realization of Bragg diffraction, driven by each of the optic...

  12. Vacuum laser acceleration using a radially polarized CO sub 2 laser beam

    CERN Document Server

    Liu, Y; He, P

    1999-01-01

    Utilizing the high-power, radially polarized CO sub 2 laser and high-quality electron beam at the Brookhaven Accelerator Test Facility, a vacuum laser acceleration scheme is proposed. In this scheme, optics configuration is simple, a small focused beam spot size can be easily maintained, and optical damage becomes less important. At least 0.5 GeV/m acceleration gradient is achievable by 1 TW laser power.

  13. Real-time analysis of laser beams by simultaneous imaging on a single camera chip

    Science.gov (United States)

    Piehler, S.; Boley, M.; Abdou Ahmed, M.; Graf, T.

    2015-03-01

    The fundamental parameters of a laser beam, such as the exact position and size of the focus or the beam quality factor M² yield vital information both for laser developers and end-users. However, each of these parameters can significantly change on a short time scale due to thermally induced effects in the processing optics or in the laser source itself, leading to process instabilities and non-reproducible results. In order to monitor the transient behavior of these effects, we have developed a camera-based measurement system, which enables full laser beam characterization in online. A novel monolithic beam splitter has been designed which generates a 2D array of images on a single camera chip, each of which corresponds to an intensity cross section of the beam along the propagation axis separated by a well-defined spacing. Thus, using the full area of the camera chip, a large number of measurement planes is achieved, leading to a measurement range sufficient for a full beam characterization conforming to ISO 11146 for a broad range of beam parameters of the incoming beam. The exact beam diameters in each plane are derived by calculation of the 2nd order intensity moments of the individual intensity slices. The processing time needed to carry out both the background filtering and the image processing operations for the full analysis of a single camera image is in the range of a few milliseconds. Hence, the measurement frequency of our system is mainly limited by the frame-rate of the camera.

  14. Theoretical modeling on the laser induced effect of liquid crystal optical phased beam steering

    Science.gov (United States)

    He, Xiaoxian; Wang, Xiangru; Wu, Liang; Tan, Qinggui; Li, Man; Shang, Jiyang; Wu, Shuanghong; Huang, Ziqiang

    2017-01-01

    Non-mechanical laser beam steering has been reported previously in liquid crystal array devices. To be one of the most promising candidates to be practical non-mechanical laser deflector, its laser induced effect still has few theoretical model. In this paper, we propose a theoretical model to analyze this laser induced effect of LC-OPA to evaluate the deterioration on phased beam steering. The model has three parts: laser induced thermal distribution; temperature dependence of material parameters and beam steering deterioration. After these three steps, the far field of laser beam is obtained to demonstrate the steering performance with the respect to the incident laser beam power and beam waist.

  15. Laser-driven shock acceleration of monoenergetic ion beams

    CERN Document Server

    Fiuza, F; Boella, E; Fonseca, R A; Silva, L O; Haberberger, D; Tochitsky, S; Gong, C; Mori, W B; Joshi, C

    2012-01-01

    We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate $\\sim 200$ MeV proton beams with state-of-the-art 100 TW class laser systems.

  16. Design of titania nanotube structures by focused laser beam direct writing

    Energy Technology Data Exchange (ETDEWEB)

    Enachi, Mihai [National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, Chisinau, MD-2004 (Moldova, Republic of); Stevens-Kalceff, Marion A. [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Sarua, Andrei [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Ursaki, Veaceslav [Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, MD-2028 (Moldova, Republic of); Tiginyanu, Ion, E-mail: tiginyanu@asm.md [National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, Chisinau, MD-2004 (Moldova, Republic of); Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Chisinau, MD-2028 (Moldova, Republic of)

    2013-12-21

    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO{sub 2} NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes.

  17. Laser and optical system for laser assisted hydrogen ion beam stripping at SNS

    Science.gov (United States)

    Liu, Y.; Rakhman, A.; Menshov, A.; Webster, A.; Gorlov, T.; Aleksandrov, A.; Cousineau, S.

    2017-03-01

    Recently, a high-efficiency laser assisted hydrogen ion (H-) beam stripping was successfully carried out in the Spallation Neutron Source (SNS) accelerator. The experiment was not only an important step toward foil-less H- stripping for charge exchange injection, it also set up a first example of using megawatt ultraviolet (UV) laser source in an operational high power proton accelerator facility. This paper reports in detail the design, installation, and commissioning result of a macro-pulsed multi-megawatt UV laser system and laser beam transport line for the laser stripping experiment.

  18. Calibration of Laser Beam Direction for Inner Diameter Measuring Device

    Directory of Open Access Journals (Sweden)

    Tongyu Yang

    2017-02-01

    Full Text Available The laser triangulation method is one of the most advanced methods for large inner diameter measurement. Our research group proposed a kind of inner diameter measuring device that is principally composed of three laser displacement sensors known to be fixed in the same plane measurement position. It is necessary to calibrate the direction of the laser beams that are emitted by laser displacement sensors because they do not meet the theoretical model accurately. For the purpose of calibrating the direction of laser beams, a calibration method and mathematical model were proposed. The inner diameter measuring device is equipped with the spindle of the machine tool. The laser beams rotate and translate in the plane and constitute the rotary rays which are driven to scan the inner surface of the ring gauge. The direction calibration of the laser beams can be completed by the sensors’ distance information and corresponding data processing method. The corresponding error sources are analyzed and the validity of the method is verified. After the calibration, the measurement error of the inner diameter measuring device reduced from ± 25 μ m to ± 15 μ m and the relative error was not more than 0.011%.

  19. Vortex beam based more stable annular laser guide star

    Science.gov (United States)

    Luo, Ruiyao; Cui, Wenda; Li, Lei; Sun, Quan; He, Yulong; Wang, Hongyan; Ning, Yu; Xu, Xiaojun

    2016-11-01

    We present an annular laser guide star (LGS) concept for large ground-based telescopes in this paper. The more stable annular LGS is generated by turbulence-resisted vortex beam. In the uplink, a vortex beam tends to wander more slightly than a Gaussian beam does in atmospheric turbulence. This may enable an annular LGS to wander more slightly than a traditional Gaussian beam generated LGS does, which would ease the burden of uplink tip-tilt mirror and benefit a dynamical closed-loop adaptive optics system. We conducted numerical simulation to validate the feasibility of this concept. And we have gotten 31% reduced variance of spot wandering of annular LGS. Besides, we set up a spatial light modulator based laser guide star simulator for beam propagation in turbulent atmosphere to experimentally test the annular LGS concept. Preliminary experimental results are given. To the best of our knowledge, it is the first time this concept is formulated.

  20. Laser-accelerated proton beams as a new particle source

    Energy Technology Data Exchange (ETDEWEB)

    Nuernberg, Frank

    2010-11-15

    The framework of this thesis is the investigation of the generation of proton beams using high-intensity laser pulses. In this work, an experimental method to fully reconstruct laser-accelerated proton beam parameters, called radiochromic film imaging spectroscopy (RIS), was developed. Since the proton beam expansion is a plasma expansion with accompanying electrons, a low-energy electron spectrometer was developed, built and tested to study the electron distribution matching to the proton beam energy distribution. Two experiments were carried out at the VULCAN Petawatt laser with the aim of showing dynamic control and enhancement of proton acceleration using multiple or defocused laser pulses. Irradiating the target with a long pulse, low-intensity laser (10{sup 12} W/cm{sup 2}) prior to the main pulse ({proportional_to}ns), an optimum pre-plasma density scale length of 60 {mu}m is generated leading to an enhancement of the maximum proton energy ({proportional_to}25%), the proton flux (factor of 3) and the beam uniformity. Proton beams were generated more efficiently than previously by driving thinner target foils at a lower intensity over a large area. The optimum condition was a 2 {mu}m foil irradiated with an intensity of 10{sup 19} W/cm{sup 2} onto a 60 {mu}m spot. Laser to proton beam efficiencies of 7.8% have been achieved (2.2% before) - one of the highest conversion efficiencies ever achieved. In the frame of this work, two separate experiments at the TRIDENT laser system have shown that these laser-accelerated proton beams, with their high number of particles in a short pulse duration, are well-suited for creating isochorically heated matter in extreme conditions. Besides the manipulation of the proton beam parameters directly during the generation, the primary aim of this thesis was the capture, control and transport of laser-accelerated proton beams by a solenoidal magnetic field lense for further purpose. In a joint project proposal, the laser and

  1. Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films

    Energy Technology Data Exchange (ETDEWEB)

    Krumov, E., E-mail: emodk@clf.bas.bg [Central Laboratory of Photoprocesses ' Acad. Jordan Malinowski' , Bulgarian Academy of Sciences, Acad. Georgy Bonchev Str., bl. 109, 1113 Sofia (Bulgaria); Starbov, N.; Starbova, K. [Central Laboratory of Photoprocesses ' Acad. Jordan Malinowski' , Bulgarian Academy of Sciences, Acad. Georgy Bonchev Str., bl. 109, 1113 Sofia (Bulgaria); Perea, A.; Solis, J. [Instituto de Optica ' Daza de Valdes' , CSIC, 28006 Madrid (Spain)

    2009-11-15

    Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO{sub 2} ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO{sub 2} films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO{sub 2} based thin film catalysts is discussed.

  2. Full-Duplex Digital Communication on a Single Laser Beam

    Science.gov (United States)

    Hazzard, D. A.; MacCannell, J. A.; Lee, G.; Selves, E. R.; Moore, D.; Payne, J. A.; Garrett, C. D.; Dahlstrom, N.; Shay, T. M.

    2006-01-01

    A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

  3. Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

    Science.gov (United States)

    Alejo, A.; Green, A.; Ahmed, H.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; McKenna, P.; Mirfayzi, S. R.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.; Kar, S.

    2016-09-01

    The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.

  4. Direct design of laser-beam shapers, zoom-beam expanders, and combinations thereof

    Science.gov (United States)

    Duerr, Fabian; Thienpont, Hugo

    2016-10-01

    Laser sources have become indispensable for industrial materials processing applications like surface treatment, cutting or welding to name a few examples. Many of these applications pose different requirements on the delivered laser irradiance distribution. Some applications might not only favor a specific irradiance distribution (e.g. a at-top) but can additionally benefit from time-varying distributions. We present an overview of a recently developed design approach that allows direct calculation of virtually any refractive or reflective laser beam shaping system. The derived analytic solution is fully described by few initial parameters and does allow an increasingly accurate calculation of all optical surfaces. Unlike other existing direct design methods for laser beam shaping, there is almost no limitation in the number of surfaces that can be calculated with this approach. This is of particular importance for optical designs of dynamic systems such as variable optical beam expanders that require four (or more) optical surfaces. Besides conventional static beam shapers, we present direct designs of zoom beam expanders, and as a novelty, a class of dynamic systems that shape and expand the input beam simultaneously. Such dynamic zoom beam shapers consist of a minimal number of optical elements and provide a much more compact solution, yet achieving excellent overall optical performance throughout the full range of zoom positions.

  5. Laser sources for polarized electron beams in cw and pulsed accelerators

    CERN Document Server

    Hatziefremidis, A; Fraser, D; Avramopoulos, H

    1999-01-01

    We report the characterization of a high power, high repetition rate, mode-locked laser system to be used in continuous wave and pulsed electron accelerators for the generation of polarized electron beams. The system comprises of an external cavity diode laser and a harmonically mode-locked Ti:Sapphire oscillator and it can provide up to 3.4 W average power, with a corresponding pulse energy exceeding 1 nJ at 2856 MHz repetition rate. The system is tunable between 770-785 and 815-835 nm with two sets of diodes for the external cavity diode laser. (author)

  6. Characterizing Effects and Benefits of Beam Defocus on High Energy Laser Performance Under Thermal Blooming and Turbulence Conditions for Air-to-Ground Engagements

    Science.gov (United States)

    2008-04-29

    PIB ). Returning to the issue of modeling the laser propagation from the weapon to the target, there are two primary effects that must be...bucket perspective ( PIB ), as well as accurately accounting for the interaction effect mentioned above, would improve the accuracy of these studies...of air-to-ground HEL scenarios under thermal blooming and turbulence; and (2) development of PIB scaling law codes that allow prediction of power in

  7. Hydrodynamics of evaporating aerosols irradiated by intense laser beams

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, R.L.; Zardecki, A.; Gerstl, S.A.W.

    1985-01-01

    An analysis is presented describing the interactions of atmospheric aerosols with a high-intensity laser beam propagating along an atmospheric path. For the case of moderate beam irradiances, diffusive mass transport and conductive energy transport dominate the aerosol-beam interactions. In this regime, the coupled aerosol-beam equations are solved numerically to obtain the spatic-temporal behavior of the propagating beam, and of the irradiated aerosols. For higher beam irradiances, convective transport of mass, energy and momentum away from the irradiated aerosols must be considered. The hydrodynamic equations are solved in the surrounding medium for this regime subject to appropriate ''jump conditions'' at the surface of the irradiated aerosol. Numerical examples illustrative of both regimes are given for the case of irradiated water aerosol droplets. 11 refs., 6 figs.

  8. Single-laser, one beam, tetrahedral magneto-optical trap.

    Science.gov (United States)

    Vangeleyn, Matthieu; Griffin, Paul F; Riis, Erling; Arnold, Aidan S

    2009-08-03

    We have realized a 4-beam pyramidal magneto-optical trap ideally suited for future microfabrication. Three mirrors split and steer a single incoming beam into a tripod of reflected beams, allowing trapping in the four-beam overlap volume. We discuss the influence of mirror angle on cooling and trapping, finding optimum efficiency in a tetrahedral configuration. We demonstrate the technique using an ex-vacuo mirror system to illustrate the previously inaccessible supra-plane pyramid MOT configuration. Unlike standard pyramidal MOTs both the pyramid apex and its mirror angle are non-critical and our MOT offers improved molasses free from atomic shadows in the laser beams. The MOT scheme naturally extends to a 2-beam refractive version with high optical access. For quantum gas experiments, the mirror system could also be used for a stable 3D tetrahedral optical lattice.

  9. Atmospheric Error Correction of the Laser Beam Ranging

    Directory of Open Access Journals (Sweden)

    J. Saydi

    2014-01-01

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

  10. Excimer Laser Beam Analyzer Based on CVD Diamond

    Science.gov (United States)

    Girolami, Marco; Salvatori, Stefano; Conte, Gennaro

    2010-11-01

    1-D and 2-D detector arrays have been realized on CVD-diamond. The relatively high resistivity of diamond in the dark allowed the fabrication of photoconductive "sandwich" strip (1D) or pixel (2D) detectors: a semitransparent light-receiving back-side contact was used for detector biasing. Cross-talk between pixels was limited by using intermediate guard contacts connected at the same ground potential of the pixels. Each pixel photocurrent was conditioned by a read-out electronics composed by a high sensitive integrator and a Σ-Δ ADC converter. The overall 500 μs conversion time allowed a data acquisition rate up to 2 kSPS. The measured fast photoresponse of the samples in the ns time regime suggests to use the proposed devices for fine tuning feedback of high-power pulsed-laser cavities, whereas solar-blindness guarantees high performance in UV beam diagnostics also under high intensity background illumination. Offering unique properties in terms of thermal conductivity and visible-light transparency, diamond represents one of the most suitable candidate for the detection of high-power UV laser emission. The technology of laser beam profiling is evolving with the increase of excimer lasers applications that span from laser-cutting to VLSI and MEMS technologies. Indeed, to improve emission performances, fine tuning of the laser cavity is required. In such a view, the development of a beam-profiler, able to work in real-time between each laser pulse, is mandatory.

  11. Speckle-metric-optimization-based adaptive optics for laser beam projection and coherent beam combining.

    Science.gov (United States)

    Vorontsov, Mikhail; Weyrauch, Thomas; Lachinova, Svetlana; Gatz, Micah; Carhart, Gary

    2012-07-15

    Maximization of a projected laser beam's power density at a remotely located extended object (speckle target) can be achieved by using an adaptive optics (AO) technique based on sensing and optimization of the target-return speckle field's statistical characteristics, referred to here as speckle metrics (SM). SM AO was demonstrated in a target-in-the-loop coherent beam combining experiment using a bistatic laser beam projection system composed of a coherent fiber-array transmitter and a power-in-the-bucket receiver. SM sensing utilized a 50 MHz rate dithering of the projected beam that provided a stair-mode approximation of the outgoing combined beam's wavefront tip and tilt with subaperture piston phases. Fiber-integrated phase shifters were used for both the dithering and SM optimization with stochastic parallel gradient descent control.

  12. Propagation of coherently combined truncated laser beam arrays with beam distortions in non-Kolmogorov turbulence.

    Science.gov (United States)

    Tao, Rumao; Si, Lei; Ma, Yanxing; Zhou, Pu; Liu, Zejin

    2012-08-10

    The propagation properties of coherently combined truncated laser beam arrays with beam distortions through non-Kolmogorov turbulence are studied in detail both analytically and numerically. The analytical expressions for the average intensity and the beam width of coherently combined truncated laser beam arrays with beam distortions propagating through turbulence are derived based on the combination of statistical optics methods and the extended Huygens-Fresnel principle. The effect of beam distortions, such as amplitude modulation and phase fluctuation, is studied by numerical examples. The numerical results reveal that phase fluctuations have significant influence on the spreading of coherently combined truncated laser beam arrays in non-Kolmogorov turbulence, and the effects of the phase fluctuations can be negligible as long as the phase fluctuations are controlled under a certain level, i.e., a>0.05 for the situation considered in the paper. Furthermore, large phase fluctuations can convert the beam distribution rapidly to a Gaussian form, vary the spreading, weaken the optimum truncation effects, and suppress the dependence of spreading on the parameters of the non-Kolmogorov turbulence.

  13. Beam displacement as a function of temperature and turbulence length scale at two different laser radiation wavelengths.

    Science.gov (United States)

    Isterling, William M; Dally, Bassam B; Alwahabi, Zeyad T; Dubovinsky, Miro; Wright, Daniel

    2012-01-01

    Narrow laser beams directed from aircraft may at times pass through the exhaust plume of the engines and potentially degrade some of the laser beam characteristics. This paper reports on controlled studies of laser beam deviation arising from propagation through turbulent hot gases, in a well-characterized laboratory burner, with conditions of relevance to aircraft engine exhaust plumes. The impact of the temperature, laser wavelength, and turbulence length scale on the beam deviation has been investigated. It was found that the laser beam displacement increases with the turbulent integral length scale. The effect of temperature on the laser beam angular deviation, σ, using two different laser wavelengths, namely 4.67 μm and 632.8 nm, was recorded. It was found that the beam deviation for both wavelengths may be semiempirically modeled using a single function of the form, σ=a(b+(1/T)(2))(-1), with two parameters only, a and b, where σ is in microradians and T is the temperature in °C.

  14. Turbulence-induced persistence in laser beam wandering

    CERN Document Server

    Zunino, Luciano; Funes, Gustavo; Pérez, Darío G

    2015-01-01

    We have experimentally confirmed the presence of long-memory correlations in the wandering of a thin Gaussian laser beam over a screen after propagating through a turbulent medium. A laboratory-controlled experiment was conducted in which coordinate fluctuations of the laser beam were recorded at a sufficiently high sampling rate for a wide range of turbulent conditions. Horizontal and vertical displacements of the laser beam centroid were subsequently analyzed by implementing detrended fluctuation analysis. This is a very well-known and widely used methodology to unveil memory effects from time series. Results obtained from this experimental analysis allow us to confirm that both coordinates behave as highly persistent signals for strong turbulent intensities. This finding is relevant for a better comprehension and modeling of the turbulence effects in free-space optical communication systems and other applications related to propagation of optical signals in the atmosphere.

  15. Longitudinal dynamics of laser-cooled fast ion beams

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  16. Optimization and control of electron beams from laser wakefield accelerations using asymmetric laser pulses

    Science.gov (United States)

    Gopal, K.; Gupta, D. N.

    2017-10-01

    Optimization and control of electron beam quality in laser wakefield acceleration are explored by using a temporally asymmetric laser pulse of the sharp rising front portion. The temporally asymmetric laser pulse imparts stronger ponderomotive force on the ambient plasma electrons. The stronger ponderomotive force associated with the asymmetric pulse significantly affects the injection of electrons into the wakefield and consequently the quality of the injected bunch in terms of injected charge, mean energy, and emittance. Based on particle-in-cell simulations, we report to generate a monoenergetic electron beam with reduced emittance and enhanced charge in laser wakefield acceleration using an asymmetric pulse of duration 30 fs.

  17. Beam positioning stability analysis on large laser facilities

    Institute of Scientific and Technical Information of China (English)

    Fang; Liu; Zhigang; Liu; Liunian; Zheng; Hongbiao; Huang; Jianqiang; Zhu

    2013-01-01

    Beam positioning stability in a laser-driven inertial confinement fusion(ICF) facility is a vital problem that needs to be fixed. Each laser beam in the facility is transmitted in lots of optics for hundreds of meters, and then targeted in a micro-sized pellet to realize controllable fusion. Any turbulence in the environment in such long-distance propagation would affect the displacement of optics and further result in beam focusing and positioning errors. This study concluded that the errors on each of the optics contributed to the target, and it presents an efficient method of enhancing the beam stability by eliminating errors on error-sensitive optics. Optimizations of the optical system and mechanical supporting structures are also presented.

  18. Cutting of nonmetallic materials using Nd:YAG laser beam

    Institute of Scientific and Technical Information of China (English)

    Bashir Ahmed Tahir; Rashid Ahmed; M. G. B. Ashiq; Afaq Ahmed; M. A. Saeed

    2012-01-01

    This study deals with Nd:YAG laser cutting nonmetallic materials,which is one of the most important and popular industrial applications of laser.The main theme is to evaluate the effects of Nd:YAG laser beam power besides work piece scanning speed.For approximate cutting depth,a theoretical study is conducted in terms of material property and cutting speed.Results show a nonlinear relation between the cutting depth and input energy.There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s.An extra energy is utilized in the deep cutting.It is inferred that as the laser power increases,cutting depth increases.The experimental outcomes are in good agreement with theoretical results.This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting,scribing,trimming,engraving,and marking nonmetallic materials.

  19. Coherent beam combining architectures for high power tapered laser arrays

    Science.gov (United States)

    Schimmel, G.; Janicot, S.; Hanna, M.; Decker, J.; Crump, P.; Erbert, G.; Witte, U.; Traub, M.; Georges, P.; Lucas-Leclin, G.

    2017-02-01

    Coherent beam combining (CBC) aims at increasing the spatial brightness of lasers. It consists in maintaining a constant phase relationship between different emitters, in order to combine them constructively in one single beam. We have investigated the CBC of an array of five individually-addressable high-power tapered laser diodes at λ = 976 nm, in two architectures: the first one utilizes the self-organization of the lasers in an interferometric extended-cavity, which ensures their mutual coherence; the second one relies on the injection of the emitters by a single-frequency laser diode. In both cases, the coherent combining of the phase-locked beams is ensured on the front side of the array by a transmission diffractive grating with 98% efficiency. The passive phase-locking of the laser bar is obtained up to 5 A (per emitter). An optimization algorithm is implemented to find the proper currents in the five ridge sections that ensured the maximum combined power on the front side. Under these conditions we achieve a maximum combined power of 7.5 W. In the active MOPA configuration, we can increase the currents in the tapered sections up to 6 A and get a combined power of 11.5 W, corresponding to a combining efficiency of 76%. It is limited by the beam quality of the tapered emitters and by fast phase fluctuations between emitters. Still, these results confirm the potential of CBC approaches with tapered lasers to provide a high-power and high-brightness beam, and compare with the current state-of-the-art with laser diodes.

  20. Flexible printed circuit boards laser bonding using a laser beam homogenization process

    Science.gov (United States)

    Kim, Joohan; Choi, Haewoon

    2012-11-01

    A laser micro-bonding process using laser beam shaping is successfully demonstrated for flexible printed circuit boards. A CW Ytterbium fiber laser with a wavelength of 1070 nm and a laser power density of 1-7 W/mm2 is employed as a local heat source for bonding flexible printed circuit boards to rigid printed circuit boards. To improve the bonding quality, a micro-lens array is used to modify the Gaussian laser beam for the bonding process. An electromagnetic modeling and heat transfer simulation is conducted to verify the effect of the micro-lens array on the laser bonding process. The optimal bonding parameters are found experimentally. As the measured temperature ramp rate of the boards exceeds 1100 K/s, bonding occurs within 100-200 ms at a laser power density of 5 W/mm2. The bonding quality of the FPCB is verified with a shear strength test. Process characteristics are also discussed.

  1. Spacecraft Power Beaming Using High-Energy Lasers, Experimental Validation

    Science.gov (United States)

    Michael, Sherif

    2008-04-01

    The lifetime of many spacecrafts are often limited by degradation of their electrical power subsystem, e.g. radiation-damaged solar arrays or failed batteries. Being able to beam power from terrestrial sites using high energy lasers, could alleviate this limitation, extending the lifetime of billions of dollars of satellite assets, as well as providing additional energy for electric propulsion that can be used for stationkeeping and orbital changes. In addition, extensive research at the Naval Postgraduate School (NPS) has shown the potential for annealing damaged solar cells using lasers. This paper describes that research and a proposed experiment to demonstrate the relevant concepts of high energy laser power beaming to an NPS-built and operated satellite. Preliminary results of ground experiment of laser illuminations of some of the solar panels of one of the spacecrafts are also presented.

  2. Beam by design: laser manipulation of electrons in modern accelerators

    CERN Document Server

    Hemsing, Erik; Xiang, Dao; Zholents, Alexander

    2014-01-01

    Accelerator-based light sources such as storage rings and free-electron lasers use relativistic electron beams to produce intense radiation over a wide spectral range for fundamental research in physics, chemistry, materials science, biology and medicine. More than a dozen such sources operate worldwide, and new sources are being built to deliver radiation that meets with the ever increasing sophistication and depth of new research. Even so, conventional accelerator techniques often cannot keep pace with new demands and, thus, new approaches continue to emerge. In this article, we review a variety of recently developed and promising techniques that rely on lasers to manipulate and rearrange the electron distribution in order to tailor the properties of the radiation. Basic theories of electron-laser interactions, techniques to create micro- and nano-structures in electron beams, and techniques to produce radiation with customizable waveforms are reviewed. We overview laser-based techniques for the generation ...

  3. In vivo evaluation of cp Ti implants with modified surfaces by laser beam with and without hydroxyapatite chemical deposition and without and with thermal treatment: topographic characterization and histomorphometric analysis in rabbits.

    Science.gov (United States)

    Queiroz, Thallita Pereira; de Molon, Rafael Scaf; Souza, Francisley Ávila; Margonar, Rogério; Thomazini, Anahi Herrera Aparecida; Guastaldi, Antônio Carlos; Hochuli-Vieira, Eduardo

    2017-03-01

    We aimed to assess the surfaces of commercially pure titanium implants (cp Ti) with modified surfaces by laser beam (LS) with and without hydroxyapatite (HA) deposition, without (HAB) and with (HABT) thermal treatment. Furthermore, we have compared them with implants with surfaces modified by acid treatment (AS) and with machined surfaces (MS) utilizing histomorphometric and descriptive histologic analyses. Surface topography characterization was analyzed by scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDX), and surface roughness (Ra) before implant installation. Forty-five rabbits received seventy-five implants in their left and right tibias and were randomly divided into five groups (n = 5 implants per group): (1) cp Ti implant modified by LS, (2) cp Ti implant modified by laser beam associated with HA deposition without heat treatment (HAB), (3) cp Ti implant modified by laser beam associated with HA deposition with heat treatment (HABT), (4) cp Ti implant with modified surface by means of acid treatment (Master Porous) commercially available (AS), and (5) cp Ti implant with MS commercially available. After 30, 60, and 90 days, the animals were euthanized and the implants and surrounding bone were removed and prepared by a non-decalcified histological process. The percentage of bone-to-implant contact (BIC) and the bone area fraction occupancy (BAFO) between the first three threads was evaluated to the higher cortical region. BIC (%) was statistically superior (p < 0.001) on the LS (69.36 ± 7.91, 71.67 ± 8.79, and 79.69 ± 3.3), HAB (73.22 ± 3.75, 69.48 ± 1.89, and 75.7 ± 4.62), and HABT (65.41 ± 5.51, 71.3 ± 2.5, and 79.68 ± 5.01) compared with AS (49.15 ± 5.76, 41.94 ± 2.85, and 57.18 ± 7.81) and MS (36.69 ± 7.24, 52.52 ± 2.75, and 51.31 ± 6.96) in the 30, 60, and 90-day periods, respectively. BAFO (%) of HAB at 30 days (90.17 ± 6.24) was statistically superior (p < 0.01) to

  4. Distortion and residual stresses in laser beam weld shaft-hub joints

    Science.gov (United States)

    Buschenhenke, F.; Hofmann, M.; Seefeld, T.; Vollertsen, F.

    In laser beam welding, a serious challenge is to control the distortion during the process. Understanding the whole process chain in view of different distortion potentials applied in each processing step provides the ability to control the distortion of the welded components. Every manufacturing step induces residual stresses in the component which can be released by the heat of the welding process, while further residual stresses are introduced into the welded parts upon cooling. The laser beam sources of the new generation permit a high power welding process and high beam quality at the same time. These laser beams are capable of producing deep and narrow seams. Thus the thermal strains of the joined parts are expected to be minimized. Especially axial welded shaft-hub joints show an irregular distribution of bending deformation, which is caused by the self-influencing welding gap. This work deals with the investigation of different laser beam sources and their effect on the welding distortion in axial welded shafthub joints made of steel (20MnCr5). The aim of the work done was to achieve minimal distortion after the welding process. To characterize the influences on the distortion behaviour of the welded parts, residual stresses have been determined by neutron diffraction.

  5. Instability Versus Equilibrium Propagation of Laser Beam in Plasma

    OpenAIRE

    Lushnikov, Pavel M.; Rose, Harvey A.

    2003-01-01

    We obtain, for the first time, an analytic theory of the forward stimulated Brillouin scattering instability of a spatially and temporally incoherent laser beam, that controls the transition between statistical equilibrium and non-equilibrium (unstable) self-focusing regimes of beam propagation. The stability boundary may be used as a comprehensive guide for inertial confinement fusion designs. Well into the stable regime, an analytic expression for the angular diffusion coefficient is obtain...

  6. Scintillations of higher order laser beams in anisotropic atmospheric turbulence.

    Science.gov (United States)

    Baykal, Yahya; Luo, Yujuan; Ji, Xiaoling

    2016-11-20

    The scintillation index of higher order laser beams is examined when such beams propagate in anisotropic atmospheric turbulence. Anisotropy is introduced through non-Kolmogorov atmospheric turbulence. The scintillation index results are obtained by employing the Rytov method solution; thus the results are valid for weak anisotropic atmospheric turbulence and for horizontal links. Variations in the scintillations are shown for various higher order laser modes against the changes in the optical source size, power law exponent of anisotropic non-Kolmogorov spectrum, anisotropic factors, and link length. Our results can be used in the design of optical wireless communication systems used between airplanes.

  7. Laser and electron beam processing of silicon and gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, J.

    1979-10-01

    Laser (photon) and electron beams provide a controlled source of heat by which surface layers of silicon and gallium arsenide can be rapidly melted and cooled with rates exceeding 10/sup 80/C/sec. The melting process has been used to remove displacement damage in ion implanted Si and GaAs, to remove dislocations, loops and precipitates in silicon and to study impurity segregation and solubility limits. The mechanisms associated with various phenomena will be examined. The possible impact of laser and electron beam processing on device technology, particularly with respect to solar cells is discussed.

  8. Characteristic of laser diode beam propagation through a collimating lens.

    Science.gov (United States)

    Xu, Qiang; Han, Yiping; Cui, Zhiwei

    2010-01-20

    A mathematical model of a laser diode beam propagating through a collimating lens is presented. Wave propagation beyond the paraxial approximation is studied. The phase delay of the laser diode wave in passing through the lens is analyzed in detail. The propagation optical field after the lens is obtained from the diffraction integral by the stationary phase method. The model is employed to predict the light intensity at various beam cross sections, and the computed intensity distributions are in a good agreement with the corresponding measurements.

  9. Beam-shaping technique for improving the beam quality of a high-power laser-diode stack.

    Science.gov (United States)

    Gao, Xin; Ohashi, Hiroyuki; Okamoto, Hiroshi; Takasaka, Masaomi; Shinoda, Kazunori

    2006-06-01

    We report a beam-shaping technique that reconfigures the beams to improve the beam quality and enhance the power density for a ten-array high-power laser-diode stack by using two optical rectangular cubes and two stripe-mirror plates. The reshaped beam has threefold improvement in beam quality, and its power density is effectively enhanced. On the basis of this technique, we focus the beam of the high-power laser-diode stack to effectively end pump a high-power fiber laser.

  10. The effect of laser beam size in a zig-zag collimator on transverse cooling of a krypton atomic beam

    Indian Academy of Sciences (India)

    Vivek Singh; V B Tiwari; S Singh; S R Mishra; H S Rawat

    2014-07-01

    The effect of size of a cooling laser beam in a zig-zag atomic beam collimator on transverse cooling of a krypton atomic beam is investigated. The simulation results show that discreteness in the interaction between the cooling laser beam and atomic beam, arising due to finite size and incidence angle of the cooling laser beam, significantly reduces the value of transverse velocity capture range of the collimator. The experimental observations show the trend similar to that obtained from simulations. Our study can be particularly useful where a small zig-zag collimator is required.

  11. Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J.A.; Amado, J.M.; Tobar, M.J.; Mateo, M.P.; Yañez, A.; Nicolas, G., E-mail: gines@udc.es

    2015-05-01

    Highlights: • Chemical mapping and profiling by laser-induced breakdown spectroscopy (LIBS) of coatings produced by laser cladding. • Production of laser clads using tungsten carbide (WC) and nickel based matrix (NiCrBSi) powders. • Calibration by LIBS of hardfacing alloys with different WC concentrations. - Abstract: Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

  12. Dual-beam laser autofocusing system based on liquid lens

    Science.gov (United States)

    Zhang, Fumin; Yao, Yannan; Qu, Xinghua; Zhang, Tong; Pei, Bing

    2017-02-01

    A dual-beam laser autofocusing system is designed in this paper. The autofocusing system is based on a liquid lens with less moving parts and fast response time, which makes the system simple, reliable, compact and fast. A novel scheme "Time-sharing focus, fast conversion" is innovatively proposed. The scheme effectively solves the problem that the guiding laser and the working laser cannot focus at the same target point because of the existence of chromatic aberration. This scheme not only makes both guiding laser and working laser achieve optimal focusing in guiding stage and working stage respectively, but also greatly reduces the system complexity and simplifies the focusing process as well as makes autofocusing time of the working laser reduce to about 10 ms. In the distance range of 1 m to 30 m, the autofocusing spot size is kept under 4.3 mm at 30 m and just 0.18 mm at 1 m. The spot size is much less influenced by the target distance compared with the collimated laser with a micro divergence angle for its self-adaptivity. The dual-beam laser autofocusing system based on liquid lens is fully automatic, compact and efficient. It is fully meet the need of dynamicity and adaptivity and it will play an important role in a number of long-range control applications.

  13. Simulation of laser beam reflection at the sea surface

    Science.gov (United States)

    Schwenger, Frédéric; Repasi, Endre

    2011-05-01

    A 3D simulation of the reflection of a Gaussian shaped laser beam on the dynamic sea surface is presented. The simulation is suitable for both the calculation of images of SWIR (short wave infrared) imaging sensor and for determination of total detected power of reflected laser light for a bistatic configuration of laser source and receiver at different atmospheric conditions. Our computer simulation comprises the 3D simulation of a maritime scene (open sea/clear sky) and the simulation of laser light reflected at the sea surface. The basic sea surface geometry is modeled by a composition of smooth wind driven gravity waves. The propagation model for water waves is applied for sea surface animation. To predict the view of a camera in the spectral band SWIR the sea surface radiance must be calculated. This is done by considering the emitted sea surface radiance and the reflected sky radiance, calculated by MODTRAN. Additionally, the radiances of laser light specularly reflected at the wind-roughened sea surface are modeled in the SWIR band considering an analytical statistical sea surface BRDF (bidirectional reflectance distribution function). This BRDF model considers the statistical slope statistics of waves and accounts for slope-shadowing of waves that especially occurs at flat incident angles of the laser beam and near horizontal detection angles of reflected irradiance at rough seas. Simulation results are presented showing the variation of the detected laser power dependent on the geometric configuration of laser, sensor and wind characteristics.

  14. High quality electron beams from a laser wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, S M; Issac, R C; Welsh, G H; Brunetti, E; Shanks, R P; Anania, M P; Cipiccia, S; Manahan, G G; Aniculaesei, C; Ersfeld, B; Islam, M R; Burgess, R T L; Vieux, G; Jaroszynski, D A [SUPA, Department of Physics, University of Strathclyde, Glasgow (United Kingdom); Gillespie, W A [SUPA, Division of Electronic Engineering and Physics, University of Dundee, Dundee (United Kingdom); MacLeod, A M [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee (United Kingdom); Van der Geer, S B; De Loos, M J, E-mail: m.wiggins@phys.strath.ac.u [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2010-12-15

    High quality electron beams have been produced in a laser-plasma accelerator driven by femtosecond laser pulses with a peak power of 26 TW. Electrons are produced with an energy up to 150 MeV from the 2 mm gas jet accelerator and the measured rms relative energy spread is less than 1%. Shot-to-shot stability in the central energy is 3%. Pepper-pot measurements have shown that the normalized transverse emittance is {approx}1{pi} mm mrad while the beam charge is in the range 2-10 pC. The generation of high quality electron beams is understood from simulations accounting for beam loading of the wakefield accelerating structure. Experiments and self-consistent simulations indicate that the beam peak current is several kiloamperes. Efficient transportation of the beam through an undulator is simulated and progress is being made towards the realization of a compact, high peak brilliance free-electron laser operating in the vacuum ultraviolet and soft x-ray wavelength ranges.

  15. Scintillation reduction for laser beams propagating through turbulent atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Berman, G P; Gorshkov, V N [Theoretical Division, T-4 and CNLS MS B213, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Torous, S V, E-mail: gpb@lanl.gov [National Technical University of Ukraine ' KPI' , 37 Peremogy Avenue, Building 7, Kiev-56, 03056 (Ukraine)

    2011-03-14

    We numerically examine the spatial evolution of the structure of coherent and partially coherent laser beams, including the optical vortices, propagating in turbulent atmospheres. The influence of beam fragmentation and wandering relative to the axis of propagation (z-axis) on the value of the scintillation index (SI) of the signal at the detector is analysed. These studies were performed for different dimensions of the detector, distances of propagation, and strengths of the atmospheric turbulence. Methods for significantly reducing the SI are described. These methods utilize averaging of the signal at the detector over a set of partially coherent beams (PCBs). It is demonstrated that the most effective approach is using a set of PCBs with definite initial directions of propagation relative to the z-axis. This approach results in a significant compensation of the beam wandering which in many cases is the main contributor to the SI. A novel method is to generate the PCBs by combining two laser beams-Gaussian and vortex beams, with different frequencies (the difference between these two frequencies being significantly smaller than the frequencies themselves). In this case, the effective suppression of the SI does not require high-frequency modulators. This result is important for achieving gigabit data rates in long-distance laser communication through turbulent atmospheres.

  16. Concrete "Waffle" Provides Laser Beam Accuracy

    Science.gov (United States)

    Building Design and Construction, 1978

    1978-01-01

    A massive concrete "waffle," riding on a bed of specially treated gravel and sand inside another building, provides the structural rigidity needed by the University of Rochester's Laboratory for Laser Energetics. (Author)

  17. Performance of Laser Beam Wavefront Sensor.

    Science.gov (United States)

    1983-02-01

    13 IV. EXPERIENTAL REUT..... ................ 17 OtCEDflO PAE BLANK-NOT FILMD 3 1* Schematic of the Phase ................... .... 10 2...laser communications , lidar, and electro-optice; communication sciences, applied electronics, semiconductor crystal and device physics, radiometric

  18. Beam quality M 2 factor matrix for non-circular symmetric laser beams

    Science.gov (United States)

    Du, Yongzhao; Fu, Yuqing; Zheng, Chaoying

    2017-02-01

    It is standard to use Mx2 and My2 to characterize the beam quality of a non-circular symmetrical beam on its x-axis and y-axis orientation. However, we knew that the values of Mx2 and My2 are inconsistent if one selects a different coordinate system or measures beam quality with different experimental conditionals, even when analyzing the same beam. To overcome this, a new beam quality characterization method, the M 2 factor matrix, is developed. It not only contains the beam quality terms, Mx2 and My2 , to characterize the beam quality along x-axis and y-axis orientation for the non-symmetric beam, but also introduces two additional cross terms, M xy and M yx , which are used to characterize the location relationship between the principal axis of the test beam and coordinate system in experiment. Moreover, M 2 factor matrix can be measured with a similar procedure to the traditional M 2 factor whose measurement instructions are described in ISO11146 by adding some additional image and signal processing procedure. The measurement principle and method is present and the experiment system for beam quality M 2 factor matrix is built to demonstrate the performance of M 2 factor matrix with real experiments.

  19. Runaway electron beam control for longitudinally pumped metal vapor lasers

    Science.gov (United States)

    Kolbychev, G. V.; Kolbycheva, P. D.

    1995-08-01

    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  20. Instability versus equilibrium propagation of a laser beam in plasma.

    Science.gov (United States)

    Lushnikov, Pavel M; Rose, Harvey A

    2004-06-25

    We obtain, for the first time, an analytic theory of the forward stimulated Brillouin scattering instability of a spatially and temporally incoherent laser beam that controls the transition between statistical equilibrium and nonequilibrium (unstable) self-focusing regimes of beam propagation. The stability boundary may be used as a comprehensive guide for inertial confinement fusion designs. Well into the stable regime, an analytic expression for the angular diffusion coefficient is obtained, which provides an essential correction to a geometric optic approximation for beam propagation.

  1. 2.1 μm high-power laser diode beam combining(Conference Presentation)

    Science.gov (United States)

    Berrou, Antoine P. C.; Elder, Ian F.; Lamb, Robert A.; Esser, M. J. Daniel

    2016-10-01

    focal length 100 mm for fully collimating the slow axis. Using D-shaped gold-coated mirrors, multiple single emitter beams are stacked in the fast axis direction with the objective that the combined beam has a beam propagation factor in the stacking direction close to the beam propagation factor of the slow axis of a single emitter, e.g. M2 of 20 to 25 in both axes. We further found that the output beam of a single emitter is highly linearly polarized along the slow axis, making it feasible to implement polarization beam combining techniques to increase the beam power by a factor two while maintaining the same beam quality. Along with full beam characterization, a power scaling strategy towards a multi-watt output power beam combining laser system will be presented.

  2. Improving the intensity of a focused laser beam

    Science.gov (United States)

    Haddadi, Sofiane; Fromager, Michael; Louhibi, Djelloul; Hasnaoui, Abdelkrim; Harfouche, Ali; Cagniot, Emmanuel; ńit-Ameur, Kamel

    2015-03-01

    Let us consider the family of symmetrical Laguerre-Gaus modes of zero azimuthal order which will be denoted as LGp0 . The latter is made up of central lobe surrounded by p concentric rings of light. The fundamental mode LG00 is a Gaussian beam of width W. The focusing of a LGp0 beam of power P by a converging lens of focal length f produces a focal spot keeping the LGp0 -shape and having a central intensity I0= 2PW2/(λf)2 whatever the value of the radial order p. Many applications of lasers (laser marking, laser ablation, …) seek nowadays for a focal laser spot with the highest as possible intensity. For a given power P, increasing intensity I0 can be achieved by increasing W and reducing the focal length f. However, this way of doing is in fact limited because the ratio W/f cannot increase indefinitely at the risk of introducing a huge truncation upon the edge of the lens. In fact, it is possible to produce a single-lobed focal spot with a central intensity of about p times the intensity I0. This result has been obtained by reshaping (rectification) a LGp0 beam thanks to a proper Binary Diffractive Optical Element (BDOE). In addition, forcing a laser cavity to oscillate upon a LGp0 can improve the power extract due to a mode volume increasing with the mode order p. This could allow envisaging an economy of scale in term of laser pumping power for producing a given intensity I0. In addition, we have demonstrated that a rectified LGp0 beam better stand the lens spherical aberration than the usual Gaussian beam.

  3. Resurrection of beam conditioning for free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Ming

    2003-02-17

    Recently Emma and Stupakov identified a fatal flaw in a Free Electron Laser (FEL) beam conditioning scheme. They showed that the conditioning is always accompanied by a projected transverse emittance growth that is so large as to make the beam conditioning completely impractical for short wavelength FELs. Furthermore, they provided a general proof along with evidence of computer simulation and reached a conclusion that any beam conditioner, regardless of the method, would suffer from the same constraints and limitations. In this paper, the author proposes an easy surgical removal of the fatal flaw by making a critical yet simple modification to the very scheme analyzed, thus resurrect the beam conditioning for short wavelength FELs. More generally, the also explain why a general search for removing have failed, why the concept and definition of beam conditioning.

  4. Laser Plasmas : Effect of rippled laser beam on excitation of ion acoustic wave

    Indian Academy of Sciences (India)

    Nareshpal Singh Saini; Tarsem Singh Gill

    2000-11-01

    Growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam in collisional unmagnetised plasma is investigated. From numerical computation, it is observed that self-focusing of main beam as well as ripple determine the growth dynamics of ripple with the distance of propagation. The effect of growing ripple on excitation of ion acoustic wave (IAW) has also been studied

  5. Active coherent beam combining of diode lasers.

    Science.gov (United States)

    Redmond, Shawn M; Creedon, Kevin J; Kansky, Jan E; Augst, Steven J; Missaggia, Leo J; Connors, Michael K; Huang, Robin K; Chann, Bien; Fan, Tso Yee; Turner, George W; Sanchez-Rubio, Antonio

    2011-03-15

    We have demonstrated active coherent beam combination (CBC) of up to 218 semiconductor amplifiers with 38.5 W cw output using up to eleven one-dimensional 21-element individually addressable diode amplifier arrays operating at 960 nm. The amplifier array elements are slab-coupled-optical-waveguide semiconductor amplifiers (SCOWAs) set up in a master-oscillator-power-amplifier configuration. Diffractive optical elements divide the master-oscillator beam to seed multiple arrays of SCOWAs. A SCOWA was phase actuated by adjusting the drive current to each element and controlled using a stochastic-parallel-gradient-descent (SPGD) algorithm for the active CBC. The SPGD is a hill-climbing algorithm that maximizes on-axis intensity in the far field, providing phase locking without needing a reference beam.

  6. Laser-Accelerated Proton Beams as a New Particle Source

    OpenAIRE

    Nürnberg, Frank

    2010-01-01

    The framework of this thesis is the investigation of the generation of proton beams using high-intensity laser pulses. Today's high power, ultrashort pulse laser systems are capable of achieving laser intensities up to 10^21 W/cm^2. When focused onto thin foil targets, extremely high field gradients of the order of TV/m are produced on the rear side of the target resulting in the acceleration of protons to multi-MeV energies with an exponential spectrum including up to 10^13 particles. This a...

  7. Quantum radiation reaction in laser-electron-beam collisions.

    Science.gov (United States)

    Blackburn, T G; Ridgers, C P; Kirk, J G; Bell, A R

    2014-01-10

    It is possible using current high-intensity laser facilities to reach the quantum radiation reaction regime for energetic electrons. An experiment using a wakefield accelerator to drive GeV electrons into a counterpropagating laser pulse would demonstrate the increase in the yield of high-energy photons caused by the stochastic nature of quantum synchrotron emission: we show that a beam of 10(9) 1 GeV electrons colliding with a 30 fs laser pulse of intensity 10(22)  W cm(-2) will emit 6300 photons with energy greater than 700 MeV, 60× the number predicted by classical theory.

  8. Modeling of dynamic effects of a low power laser beam

    Science.gov (United States)

    Lawrence, George N.; Scholl, Marija S.; Khatib, AL

    1988-01-01

    Methods of modeling some of the dynamic effects involved in laser beam propagation through the atmosphere are addressed with emphasis on the development of simple but accurate models which are readily implemented in a physical optics code. A space relay system with a ground based laser facility is considered as an example. The modeling of such characteristic phenomena as laser output distribution, flat and curved mirrors, diffraction propagation, atmospheric effects (aberration and wind shear), adaptive mirrors, jitter, and time integration of power on target, is discussed.

  9. Two-photon flow cytometer with laser scanning Bessel beams

    Science.gov (United States)

    Wang, Yongdong; Ding, Yu; Ray, Supriyo; Paez, Aurelio; Xiao, Chuan; Li, Chunqiang

    2016-03-01

    Flow cytometry is an important technique in biomedical discovery for cell counting, cell sorting and biomarker detection. In vivo flow cytometers, based on one-photon or two-photon excited fluorescence, have been developed for more than a decade. One drawback of laser beam scanning two-photon flow cytometer is that the two-photon excitation volume is fairly small due to the short Rayleigh range of a focused Gaussian beam. Hence, the sampling volume is much smaller than one-photon flow cytometry, which makes it challenging to count or detect rare circulating cells in vivo. Bessel beams have narrow intensity profiles with an effective spot size (FWHM) as small as several wavelengths, making them comparable to Gaussian beams. More significantly, the theoretical depth of field (propagation distance without diffraction) can be infinite, making it an ideal solution as a light source for scanning beam flow cytometry. The trade-off of using Bessel beams rather than a Gaussian beam is the fact that Bessel beams have small concentric side rings that contribute to background noise. Two-photon excitation can reduce this noise, as the excitation efficiency is proportional to intensity squared. Therefore, we developed a two-photon flow cytometer using scanned Bessel beams to form a light sheet that intersects the micro fluidic channel.

  10. Laser-driven generation of ultra-intense proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Badziak, J.; Jablonski, S.; Kubkowska, M.; Parys, P.; Rosinski, M.; Wolowski, J. [EURATOM, Inst Plasma Phys and Laser Microfus, PL-00908 Warsaw (Poland); Antici, P.; Fuchs, J.; Mancic, A. [UPMC, LULI, Ecole Polytech, CNRS, CEA, F-91128 Palaiseau (France); Szydlowski, A. [Andrzej Soltan Inst Nucl Studies, Otwock (Poland)

    2010-07-01

    The results of experimental and numerical studies of high-intensity proton beam generation driven by a short laser pulse of relativistic intensity are reported. In the experiment, a 350 fs laser pulse of 1.06 or 0.53 m wavelength and intensity up to 2*10{sup 19} Wcm{sup -2} irradiated a thin (0.6-2{mu}m) plastic (PS) or Au/PS (plastic covered by 0.2{mu}m Au front layer) target along the target normal. The effect of laser intensity, the target structure and the laser wavelength on the proton beam parameters and laser-protons energy conversion efficiency were examined. Both the measurements and one-dimensional particle-in-cell simulations showed that MeV proton beams of intensity 10{sup 18}Wcm{sup -2} and current density 10{sup 12}Acm{sup -2} at the source can be produced when the laser intensity-wavelength squared product I{sub L{lambda}}{sup 2} is 10{sup 19}Wcm{sup -2}m{sup 2} and the laser-target interaction conditions approach the skin-layer ponderomotive acceleration (SLPA) requirements. The simulations also proved that at I{sub L{lambda}}{sup 2} {>=} 5*10{sup 19}Wcm{sup -2}m{sup 2} and {lambda} {<=} 0.53{mu}m, SLPA clearly prevails over other acceleration mechanisms and it can produce multi-MeV proton beams of extremely high intensities above 10{sup 20}Wcm{sup -2}. (authors)

  11. Evaluation of bone tissue reaction in laser beamed implants

    Energy Technology Data Exchange (ETDEWEB)

    Allegrini, Sergio, E-mail: sergiojr@usp.br [Graduate Program in Biodentistry, Ibirapuera University (UNIB), São Paulo, SP, 04661 100 (Brazil); Yoshimoto, Marcelo [Graduate Program in Biodentistry, Ibirapuera University (UNIB), São Paulo, SP, 04661 100 (Brazil); Salles, Marcos Barbosa [Department of Oral and Maxillofacial Surgery, Nove de Julho University (UNINOVE), São Paulo, SP, 02117 010 (Brazil); Allegrini, Marcia Rivellino Facci [São Paulo Fire Department (SPFD) of the Militar Police, Dentistry Section, São Paulo, SP, 01018 001 (Brazil); Pistarini, Luciana Crepaldi Yazawa; Braga, Francisco Jose Correa; Bressiani, Ana Helena de Almeida [Nuclear and Energy Research Institute – IPEN/USP, São Paulo, SP, 05508 900 (Brazil)

    2014-07-01

    The purpose of this study was to evaluate alterations and bone tissue response on laser treated implant surfaces (Nd:YAG – 100 W). Sixty grade II titanium (ASTM F67) mini-implants (1.5 mm × 4.0 mm) were installed in femurs of 30 Wistar rats. The animals were divided into two groups: thirty mini-implants were machined elements (Machined Group) and the other thirty had laser beamed surfaces (Laser Group). The animals were subdivided into three groups, according to bone healing periods of 15, 30 and 60 days. The samples were analyzed under light, scanning electron and confocal 3D microscopy as well as by EDS (energy dispersive spectroscopy) and Student's t test was used for statistical analyses. Light microscopy results showed new bone trabeculae formation toward laser-treated implants at 15 days’ bone repair as well as thin layers of osteoid matrix, indicating high biocompatibility. Similar features were observed in the Machined Group but only after 30 days. Bone/implant contact was better evidenced on laser-treated surfaces compared to that on simply machined implants. The only group that demonstrated change in level of significance was the laser-treated group at the 15-day-healing period (p < 0.05). Higher oxygen concentration possibly provides more efficient response of osteoblasts during new bone tissue deposition. Implant treated surfaces altered by laser beaming, their composition, surface topography and surface energy may be the future scene in implant dentistry.

  12. Laser-Bioplasma Interaction: The Blood Type Transmutation Induced by Multiple Ultrashort Wavelength Laser Beams

    Science.gov (United States)

    Stefan, V. Alexander

    2015-11-01

    The interaction of ultrashort wavelength multi laser beams with the flowing blood thin films leads to the transmutation of the blood types A, B, and AB into O type. This is a novel mechanism of importance for the transfusion medicine. Laser radiation is in resonance with the eigen-frequency modes of the antigen proteins and forces the proteins to parametrically oscillate until they get kicked out from the surface. The stripping away of antigens is done by the scanning-multiple-lasers of a high repetition rate in the blue-purple frequency domain. The guiding-lasers are in the red-green frequency domain. The laser force, (parametric interaction with the antigen eigen-oscillation), upon the antigen protein molecule must exceed its weight. The scanning laser beam is partially reflected as long as the antigen(s) is not eliminated. The process of the protein detachment can last a few minutes. Supported by Nikola Tesla Labs., Stefan University.

  13. Terahertz plasmonic laser radiating in an ultra-narrow beam

    CERN Document Server

    Wu, Chongzhao; Reno, John L; Kumar, Sushil

    2016-01-01

    Plasmonic lasers (spasers) generate coherent surface-plasmon-polaritons (SPPs) and could be realized at subwavelength dimensions in metallic cavities for applications in nanoscale optics. Plasmonic cavities are also utilized for terahertz quantum-cascade lasers (QCLs), which are the brightest available solid-state sources of terahertz radiation. A long standing challenge for spasers is their poor coupling to the far-field radiation. Unlike conventional lasers that could produce directional beams, spasers have highly divergent radiation patterns due to their subwavelength apertures. Here, we theoretically and experimentally demonstrate a new technique for implementing distributed-feedback (DFB) that is distinct from any other previously utilized DFB schemes for semiconductor lasers. The so-termed antenna-feedback scheme leads to single-mode operation in plasmonic lasers, couples the resonant SPP mode to a highly directional far-field radiation pattern, and integrates hybrid SPPs in surrounding medium into the ...

  14. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, K. M.; Schell, S.; Wilkens, J. J. [Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München (Germany)

    2013-07-26

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  15. Laser beam propagation in non-linearly absorbing media

    CSIR Research Space (South Africa)

    Forbes, A

    2006-08-01

    Full Text Available Many analytical techniques exist to explore the propagation of certain laser beams in free space, or in a linearly absorbing medium. When the medium is nonlinearly absorbing the propagation must be described by an iterative process using the well...

  16. Metal surface temperature induced by moving laser beams

    NARCIS (Netherlands)

    Römer, G.R.B.E.; Meijer, J.

    1995-01-01

    Whenever a metal is irradiated with a laser beam, electromagnetic energy is transformed into heat in a thin surface layer. The maximum surface temperature is the most important quantity which determines the processing result. Expressions for this maximum temperature are provided by the literature fo

  17. Image Processing In Laser-Beam-Steering Subsystem

    Science.gov (United States)

    Lesh, James R.; Ansari, Homayoon; Chen, Chien-Chung; Russell, Donald W.

    1996-01-01

    Conceptual design of image-processing circuitry developed for proposed tracking apparatus described in "Beam-Steering Subsystem For Laser Communication" (NPO-19069). In proposed system, desired frame rate achieved by "windowed" readout scheme in which only pixels containing and surrounding two spots read out and others skipped without being read. Image data processed rapidly and efficiently to achieve high frequency response.

  18. Laser Brazing with Beam Scanning: Experimental and Simulative Analysis

    Science.gov (United States)

    Heitmanek, M.; Dobler, M.; Graudenz, M.; Perret, W.; Göbel, G.; Schmidt, M.; Beyer, E.

    Laser beam brazing with copper based filler wire is a widely established technology for joining zinc-coated steel plates in the body-shop. Successful applications are the divided tailgate or the zero-gap joint, which represents the joint between the side panel and the roof-top of the body-in-white. These joints are in direct view to the customer, and therefore have to fulfil highest optical quality requirements. For this reason a stable and efficient laser brazing process is essential. In this paper the current results on quality improvement due to one dimensional laser beam deflections in feed direction are presented. Additionally to the experimental results a transient three-dimensional simulation model for the laser beam brazing process is taken into account. With this model the influence of scanning parameters on filler wire temperature and melt pool characteristics is analyzed. The theoretical predictions are in good accordance with the experimental results. They show that the beam scanning approach is a very promising method to increase process stability and seam quality.

  19. Atomic Beam Laser Spectrometer for In-field Isotopic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Alonso [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Actinide Analytical Chemistry Group

    2016-06-22

    This is a powerpoint presentation for the DTRA quarterly program review that goes into detail about the atomic beam laser spectrometer for in-field isotopic analysis. The project goals are the following: analysis of post-detonation debris, determination of U and Pu isotopic composition, and fieldable prototype: < 2ft3, < 1000W.

  20. Dynamics of a multi-beam photonic free electron laser

    NARCIS (Netherlands)

    Lee, J.H.H.; van Dijk, M.W.; Denis, T.; van der Slot, Petrus J.M.; Boller, Klaus J.

    2012-01-01

    A photonic free-electron laser (pFEL) uses free electrons streaming through a photonic crystal (PhC) to generate tunable coherent radiation. Here, we consider a pFEL driven by a set of three low energy (~ 10 keV), low perveance (< 0.1 μP) electron beams. Using a particle-in- cell code, we numericall

  1. Tuneable Gaussian to flat-top resonator by amplitude beam shaping using a digital laser

    CSIR Research Space (South Africa)

    Ngcobo, S

    2014-02-01

    Full Text Available In this paper we experimentally demonstrate a simple laser cavity that produces spatial tuneable laser modes from a Gaussian beam to a Flat-top beam and a Donut-beam. The laser cavity contains an opaque ring and an adjustable circular aperture...

  2. Energy gain and spectral tailoring of ion beams using ultra-high intensity laser beams

    Science.gov (United States)

    Prasad, Rajendra; Swantusch, Marco; Cerchez, Mirela; Spickermann, Sven; Auorand, Bastian; Wowra, Thomas; Boeker, Juergen; Willi, Oswald

    2015-11-01

    The field of laser driven ion acceleration over the past decade has produced a huge amount of research. Nowadays, several multi-beam facilities with high rep rate system, e.g. ELI, are being developed across the world for different kinds of experiments. The study of interaction dynamics of multiple beams possessing ultra-high intensity and ultra-short pulse duration is of vital importance. Here, we present the first experimental results on ion acceleration using two ultra-high intensity beams. Thanks to the unique capability of Arcturus laser at HHU Düsseldorf, two almost identical, independent beams in laser parameters such as intensity (>1020 W/cm2), pulse duration (30 fs) and contrast (>1010), could be accessed. Both beams are focused onto a 5 μm thin Ti target. While ensuring spatial overlap of the two beams, at relative temporal delay of ~ 50 ps (optimum delay), the proton and carbon ion energies were enhanced by factor of 1.5. Moreover, strong modulation in C4+ions near the high energy cut-off is observed later than the optimum delay for the proton enhancement. This offers controlled tailoring of the spectral content of heavy ions.

  3. Pixel diamond detectors for excimer laser beam diagnostics

    Science.gov (United States)

    Girolami, M.; Allegrini, P.; Conte, G.; Salvatori, S.

    2011-05-01

    Laser beam profiling technology in the UV spectrum of light is evolving with the increase of excimer lasers and lamps applications, that span from lithography for VLSI circuits to eye surgery. The development of a beam-profiler, able to capture the excimer laser single pulse and process the acquired pixel current signals in the time period between each pulse, is mandatory for such applications. 1D and 2D array detectors have been realized on polycrystalline CVD diamond specimens. The fast diamond photoresponse, in the ns time regime, suggests the suitability of such devices for fine tuning feedback of high-power pulsed-laser cavities, whereas solar-blindness guarantees high performance in UV beam diagnostics, also under high intensity background illumination. Offering unique properties in terms of thermal conductivity and visible-light transparency, diamond represents one of the most suitable candidate for the detection of high-power UV laser emission. The relatively high resistivity of diamond in the dark has allowed the fabrication of photoconductive vertical pixel-detectors. A semitransparent light-receiving back-side contact has been used for detector biasing. Each pixel signal has been conditioned by a multi-channel read-out electronics made up of a high-sensitive integrator and a Σ-Δ A/D converter. The 500 μs conversion time has allowed a data acquisition rate up to 2 kSPS (Sample Per Second).

  4. Laser beaming demonstrations at the Starfire Optical Range

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-03-01

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

  5. Theory of microdroplet and microbubble deformation by Gaussian laser beam

    CERN Document Server

    Ellingsen, Simen Å

    2012-01-01

    The theory for linear deformations of fluid microparticles in a laser beam of Gaussian profile is presented, when the beam focus is at the particle center as in optical trapping. Three different fluid systems are considered: water microdroplet in air, air microbubble in water, and a special oil-emulsion in water system used in experiments with optical deformation of fluid interfaces. We compare interface deformations of the three systems when illuminated by a wide (compared to particle radius) and narrow laser beams and analyse differences. Deformations of droplets are radically different from bubbles under otherwise identical conditions, due to the opposite lensing effect (converging and diverging, respectively) of the two; a droplet is deformed far more than a bubble, cetera paribus. Optical contrast is found to be of great importance to the shape obtained when comparing the relatively low-contrast oil-emulsion system to that of water droplets. We finally analyse the dynamics of particle motion when the las...

  6. On-line laser spectroscopy with thermal atomic beams

    CERN Document Server

    Thibault, C; De Saint-Simon, M; Duong, H T; Guimbal, P; Huber, G; Jacquinot, P; Juncar, P; Klapisch, Robert; Liberman, S; Pesnelle, A; Pillet, P; Pinard, J; Serre, J M; Touchard, F; Vialle, J L

    1981-01-01

    On-line high resolution laser spectroscopy experiments have been performed in which the light from a CW tunable dye laser interacts at right angles with a thermal atomic beam. /sup 76-98/Rb, /sup 118-145 /Cs and /sup 208-213/Fr have been studied using the ionic beam delivered by the ISOLDE on-line mass separator at CERN while /sup 30-31/Na and /sup 38-47/K have been studied by setting the apparatus directly on-line with the PS 20 GeV proton beam. The principle of the method is briefly explained and some results concerning nuclear structure are given. The hyperfine structure, spins and isotope shifts of the alkali isotopes and isomers are measured. (8 refs).

  7. Spectral and spatial characterisation of laser-driven positron beams

    Science.gov (United States)

    Sarri, G.; Warwick, J.; Schumaker, W.; Poder, K.; Cole, J.; Doria, D.; Dzelzainis, T.; Krushelnick, K.; Kuschel, S.; Mangles, S. P. D.; Najmudin, Z.; Romagnani, L.; Samarin, G. M.; Symes, D.; Thomas, A. G. R.; Yeung, M.; Zepf, M.

    2017-01-01

    The generation of high-quality relativistic positron beams is a central area of research in experimental physics, due to their potential relevance in a wide range of scientific and engineering areas, ranging from fundamental science to practical applications. There is now growing interest in developing hybrid machines that will combine plasma-based acceleration techniques with more conventional radio-frequency accelerators, in order to minimise the size and cost of these machines. Here we report on recent experiments on laser-driven generation of high-quality positron beams using a relatively low energy and potentially table-top laser system. The results obtained indicate that current technology allows to create, in a compact setup, positron beams suitable for injection in radio-frequency accelerators.

  8. Beam shaping to provide round and square-shaped beams in optical systems of high-power lasers

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim

    2016-05-01

    Optical systems of modern high-power lasers require control of irradiance distribution: round or square-shaped flat-top or super-Gaussian irradiance profiles are optimum for amplification in MOPA lasers and for thermal load management while pumping of crystals of solid-state ultra-short pulse lasers to control heat and minimize its impact on the laser power and beam quality while maximizing overall laser efficiency, variable profiles are also important in irradiating of photocathode of Free Electron lasers (FEL). It is suggested to solve the task of irradiance re-distribution using field mapping refractive beam shapers like piShaper. The operational principle of these devices presumes transformation of laser beam intensity from Gaussian to flat-top one with high flatness of output wavefront, saving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with ultra-short pulse lasers having broad spectrum. Using the same piShaper device it is possible to realize beams with flat-top, inverse Gauss or super Gauss irradiance distribution by simple variation of input beam diameter, and the beam shape can be round or square with soft edges. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in optical systems of high-power lasers. Examples of real implementations and experimental results will be presented as well.

  9. Laser Beam Oscillation Strategies for Fillet Welds in Lap Joints

    Science.gov (United States)

    Müller, Alexander; Goecke, Sven-F.; Sievi, Pravin; Albert, Florian; Rethmeier, Michael

    Laser beam oscillation opens up new possibilities of influencing the welding process in terms of compensation of tolerances and reduction of process emissions that occur in industrial applications, such as in body-in-white manufacturing. The approaches are to adapt the melt pool width in order to generate sufficient melt volume or to influence melt pool dynamics, e.g. for a better degassing. Welding results are highly dependent on the natural frequency of the melt pool, the used spot diameter and the oscillation speed of the laser beam. The conducted investigations with an oscillated 300 μm laser spot show that oscillation strategies, which are adjusted to the joining situation improve welding result for zero-gap welding as well as for bridging gaps to approximately 0.8 mm. However, a complex set of parameters has to be considered in order to generate proper welding results. This work puts emphasize on introducing them.

  10. Two-laser optical tweezers with a blinking beam

    Science.gov (United States)

    Lamperska, Weronika; Masajada, Jan; Drobczyński, Sławomir; Gusin, Paweł

    2017-07-01

    We report on a two-laser holographic optical tweezers setup and present its two major advantages over single-laser one. First, the trap stiffness of a weak trapping beam can be measured with a considerable accuracy. Second, a novel method of examining local viscosity of fluid is proposed. Both measurements are performed based on forcing the oscillations of a microscopic polystyrene bead placed between two optical traps. The two beams are generated by separate laser sources and therefore their trapping power can vary. Moreover, a stronger trap 'blinks', modulated by an electronic shutter. The blinking frequency can be precisely adjusted to the experimental conditions, which results in high accuracy of the measurements.

  11. High energy density physics with intense ion and laser beams. Annual report 2003

    Energy Technology Data Exchange (ETDEWEB)

    Weyrich, K. (comp.)

    2004-07-01

    The following topics are dealt with: Laser plasma physics, plasma spectroscopy, beam interaction experiments, atomic and radiation physics, pulsed power applications, beam transport and accelerator research and development, properties of dense plasma, instabilities in beam-plasma interaction, beam transport in dense plasmas, short-pulse laser-matter interaction. (HSI)

  12. ILC beam energy measurement by means of laser Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Muchnoi, N. [Budker Inst. for Nuclear Physics, Novosibirsk (Russian Federation); Schreiber, H.J.; Viti, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2008-10-15

    A novel, non-invasive method of measuring the beam energy at the International Linear Collider is proposed. Laser light collides head-on with beam particles and either the energy of the Compton scattered electrons near the kinematic end-point is measured or the positions of the Compton backscattered {gamma}-rays, the edge electrons and the unscattered beam particles are recorded. A compact layout for the Compton spectrometer is suggested. It consists of a bending magnet and position sensitive detectors operating in a large radiation environment. Several options for high spatial resolution detectors are discussed. Simulation studies support the use of an infrared or green laser and quartz fiber detectors to monitor the backscattered photons and edge electrons. Employing a cavity monitor, the beam particle position downstream of the magnet can be recorded with submicrometer precision. Such a scheme provides a feasible and promising method to access the incident beam energy with precisions of 10{sup -4} or better on a bunch-to-bunch basis while the electron and positron beams are in collision. (orig.)

  13. Laser beam drilling of metal-based composites

    Science.gov (United States)

    Riegel, H.; Merkel, M.; Ã-chsner, A.

    2014-02-01

    Laser drilling is a highly efficient technique to generate holes in almost any material. The relatively small amount of heat being involved during the process results in a small heat affected zone. This characteristic makes laser processing interesting for composite materials. The drilling process has to be adapted to the special characteristics of the composite material. In this paper investigations were performed with an advanced composite material, that is a metallic hollow sphere structure (MHSS). Numerical simulation was used to predict heat flux and temperature levels for different geometric parameters of the spheres (diameter, wall thickness) in order to optimize the drilling process. The numerical simulation allows a detailed analysis of the physical process in the zone that is influenced by the laser beam, which can hardly be analyzed by any measuring technique. The models for transient numerical analysis consider heat conduction and convection. The experimental work was done by a CO2-laser. The percussion drilling method has been used as drilling technique. The pulse duration was in the millisecond time regime. Investigations have been done with a mean power of 100 W, 200 W and 400 W. Two focal lenses have been used with focal lengths of 5.0´´ and 7.5´´. The laser beam melts the hollow sphere structure inside the beam leaving a hole in the structure as well as in individual hollow spheres. An image processing technique was developed to determine the circularity on the spheres and the drilled diameter in the structure. The circularity declines with increasing drill depth. The diameter as function of depth can be well described with lines of constant intensity of the focussed laser beam, the isophotes.

  14. Laser beam shaping profiles and propagation.

    Science.gov (United States)

    Shealy, David L; Hoffnagle, John A

    2006-07-20

    We consider four families of functions--the super-Gaussian, flattened Gaussian, Fermi-Dirac, and super-Lorentzian--that have been used to describe flattened irradiance profiles. We determine the shape and width parameters of the different distributions, when each flattened profile has the same radius and slope of the irradiance at its half-height point, and then we evaluate the implicit functional relationship between the shape and width parameters for matched profiles, which provides a quantitative way to compare profiles described by different families of functions. We conclude from an analysis of each profile with matched parameters using Kirchhoff-Fresnel diffraction theory and M2 analysis that the diffraction patterns as they propagate differ by small amounts, which may not be distinguished experimentally. Thus, beam shaping optics is designed to produce either of these four flattened output irradiance distributions with matched parameters will yield similar irradiance distributions as the beam propagates.

  15. Enhancement of resistance against high energy laser pulse injection with chevron beam dump

    Energy Technology Data Exchange (ETDEWEB)

    Yatsuka, Eiichi; Hatae, Takaki [Japan Atomic Energy Agency, Mukoyama, Naka, Ibaraki 311-0193 (Japan); Bassan, Michele; Vayakis, George; Walsh, Michael [ITER Organization, St Paul Lez Durance Cedex, Provence 13067 (France); Itami, Kiyoshi [Japan Atomic Energy Agency, Mukoyama, Naka, Ibaraki 311-0193 (Japan)

    2015-11-15

    Highlights: • The laser irradiation tests onto flat-mirror-molybdenum sample were carried out. • The absorbed energy density is the correct figure of the laser-induced damage. • Experiments validated the design of a new beam dump called chevron beam dump. • The chevron beam dump would have much longer lifetime than conventional beam dumps. - Abstract: The laser beam dump of the Edge Thomson scattering (ETS) in ITER is being developed and a new type of beam dump called the chevron beam dump was proposed recently. The laser-induced damage on the surface is one of the most severe issues to be overcome. The key concept of the chevron beam dump is to reduce the laser energy absorption per unit area and to absorb the laser beam gradually. The laser irradiation tests onto flat-mirror-molybdenum sample were carried out. It was clarified that the absorbed (rather than incident) energy density of the laser pulses should be the correct figure of merit for the laser-induced damage. Therefore, the concept of the chevron beam dump design, that minimizes the absorbed laser energy density per unit area, was validated experimentally. The chevron beam dump enables us to extend its lifetime drastically relative to conventional beam dumps. Potential methods to improve the laser-induced damage threshold (LIDT) are also discussed in this paper.

  16. Compact beam transport system for free-electron lasers driven by a laser plasma accelerator

    Science.gov (United States)

    Liu, Tao; Zhang, Tong; Wang, Dong; Huang, Zhirong

    2017-02-01

    Utilizing laser-driven plasma accelerators (LPAs) as a high-quality electron beam source is a promising approach to significantly downsize the x-ray free-electron laser (XFEL) facility. A multi-GeV LPA beam can be generated in several-centimeter acceleration distance, with a high peak current and a low transverse emittance, which will considerably benefit a compact FEL design. However, the large initial angular divergence and energy spread make it challenging to transport the beam and realize FEL radiation. In this paper, a novel design of beam transport system is proposed to maintain the superior features of the LPA beam and a transverse gradient undulator (TGU) is also adopted as an effective energy spread compensator to generate high-brilliance FEL radiation. Theoretical analysis and numerical simulations are presented based on a demonstration experiment with an electron energy of 380 MeV and a radiation wavelength of 30 nm.

  17. Photovoltaic cells for laser power beaming

    Science.gov (United States)

    Landis, Geoffrey A.; Jain, Raj K.

    1992-01-01

    To better understand cell response to pulsed illumination at high intensity, the PC-1DC finite-element computer model was used to analyze the response of solar cells to pulsed laser illumination. Over 50% efficiency was calculated for both InP and GaAs cells under steady-state illumination near the optimum wavelength. The time-dependent response of a high-efficiency GaAs concentrator cell to a laser pulse was modelled, and the effect of laser intensity, wavelength, and bias point was studied. Designing a cell to accommodate pulsed input can be done either by accepting the pulsed output and designing a cell to minimize adverse effects due to series resistance and inductance, or to design a cell with a long enough minority carrier lifetime, so that the output of the cell will not follow the pulse shape. Two such design possibilities are a monolithic, low-inductance voltage-adding GaAs cell, or a high-efficiency, light-trapping silicon cell. The advantages of each design will be discussed.

  18. Refractive beam shapers for material processing with high power single mode and multimode lasers

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim

    2013-02-01

    The high power multimode fiber-coupled laser sources, like solid state lasers or laser diodes as well as single mode and multimode fiber lasers, are now widely used in various industrial laser material processing technologies like metal or plastics welding, cladding, hardening, brazing, annealing. Performance of these technologies can be essentially improved by varying the irradiance profile of a laser beam with using beam shaping optics, for example, the field mapping refractive beam shapers like piShaper. Operational principle of these devices presumes transformation of laser beam irradiance distribution from Gaussian to flattop, super-Gauss, or inverse-Gauss profile with high flatness of output wave front, conserving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field. Important feature of piShaper is in capability to operate with TEM00 and multimode lasers, the beam shapers can be implemented not only as telescopic optics but also as collimating systems, which can be connected directly to fiber-coupled lasers or fiber lasers, thus combining functions of beam collimation and irradiance transformation. This paper will describe some features of beam shaping of high-power laser sources, including multimode fiber coupled lasers, and ways of adaptation of beam shaping optical systems design to meet requirements of modern laser technologies. Examples of real implementations will be presented as well.

  19. Scintillation Reduction for Laser Beams Propagating Through Turbulent Atmosphere

    CERN Document Server

    Berman, G P; Torous, S V

    2010-01-01

    We numerically examine the spatial evolution of the structure of coherent and partially coherent laser beams, including the optical vortices, propagating in turbulent atmospheres. The influence of beam fragmentation and wandering relative to the axis of propagation (z-axis) on the value of the scintillation index (SI) of the signal at the detector is analyzed. These studies were performed for different dimensions of the detector, distances of propagation, and strengths of the atmospheric turbulence. Methods for significantly reducing the scintillation index are described. These methods utilize averaging of the signal at the detector over a set of partially coherent beams (PCBs). It is demonstrated that the most effective approach is using a set of PCBs with definite initial directions of propagation relative to the z-axis. This approach results in a significant compensation of the beam wandering which in many cases is the main contributor to the SI. A novel method is to generate the PCBs by combining two lase...

  20. Intensity Moments of Hermite-Cosh-Gaussian Laser Beams

    Institute of Scientific and Technical Information of China (English)

    YU Song; GUO Hong; FU Xiquan

    2002-01-01

    In this paper,attention is focused on the intensity moments of the Hermite-Cosh-Gaussian (HChG) laser beams from the zero-order to the fourth-order.The frequently used parameters such as the power in bucket (PIB),the beam width,the curvature radius,the far field divergence,the M2-factor,the Rayleigh length and the kurtosis are calculated in terms of the intensity moments.Figures show the influence of the mode index and the decentered parameter,which are the critical parameters of the HChG beams.Moreover,the center of the gravity of the radiation field and the symmetry are discussed along with the propagation axis.Finally,the power fraction within the beam width defined by the second moments is illustrated with numerical method.

  1. Shipborne Laser Beam Weapon System for Defence against Cruise Missiles

    Directory of Open Access Journals (Sweden)

    J.P. Dudeja

    2000-04-01

    Full Text Available Sea-skim~ing cruise missiles pose the greatest threat to a surface ship in the present-day war scenario. The convenitional close-in-weapon-systems (CIWSs are becoming less reliable against these new challenges requiring extremely fast reaction time. Naval Forces see a high energy laser as a feasible andjeffective directed energy weapon against sea-skimming antiship cruise missiles becauseof its .ability to deliver destructive energy at the speed of light on to a distant target. The paper comparesthe technology and capability of deuterium fluoride (DF and chemical-oxygen-iodine laser (COIL in effectively performing the role of a shipborne CIWS altainst sea-skimming missiles. Out of these twolasers, it is argued that DF laser wo.uld be more effective a,s a shipborne weapon for defence against sea-skimmin,g cruise missiles. Besides the high energy laser as the primary (killing laser, othersub-systems required in the complete weapon system would be: A beacon laser to sense phase distor'ions in the primary laser, adaptive optics to compensate the atmospheric distortions, beam-directing optics, illuminating lasers, IRST sensors, surveillance and tracking radars, interfacing system, etc.

  2. Experimental Investigation of Multibunch, Multipass Beam Breakup in the Jefferson Laboratory Free Electron Laser Upgrade Driver

    Energy Technology Data Exchange (ETDEWEB)

    Christopher Tennant; David Douglas; Kevin Jordan; Nikolitsa Merminga; Eduard Pozdeyev; Haipeng Wang; Todd I. Smith; Stefan Simrock; Ivan Bazarov; Georg Hoffstaetter

    2006-03-24

    In recirculating accelerators, and in particular energy recovery linacs (ERLs), the maximum current can be limited by multipass, multibunch beam breakup (BBU), which occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on the accelerating pass and again on the energy recovering pass. This effect is of particular concern in the design of modern high average current energy recovery accelerators utilizing superconducting RF technology. Experimental characterization and observations of the instability at the Jefferson Laboratory 10 kW Free Electron Laser (FEL) are presented. Measurements of the threshold current for the instability are made under a variety of beam conditions and compared to the predictions of several BBU simulation codes. This represents the first time in which the codes have been experimentally benchmarked. With BBU posing a threat to high current beam operation in the FEL Driver, several suppression schemes were developed.

  3. Effects of underwater turbulence on laser beam propagation and coupling into single-mode optical fiber.

    Science.gov (United States)

    Hanson, Frank; Lasher, Mark

    2010-06-01

    We characterize and compare the effects of turbulence on underwater laser propagation with theory. Measurements of the coupling efficiency of the focused beam into a single-mode fiber are reported. A simple tip-tilt control system, based on the position of the image centroid in the focal plane, was shown to maintain good coupling efficiency for a beam radius equal to the transverse coherence length, r(0). These results are relevant to high bandwidth communication technology that requires good spatial mode quality.

  4. Doughnut laser beam as an incoherent superposition of two petal beams

    CSIR Research Space (South Africa)

    Litvin, IA

    2014-02-01

    Full Text Available evidence of the real electromagnetic field. In this Letter we revisit this question and show that an observed doughnut beam from a laser cavity may not be a pure Laguerre–Gaussian azimuthal mode but can be an incoherent sum of petal modes, which do...

  5. Cooling of relativistic electron beams in chirped laser pulses

    CERN Document Server

    Yoffe, Samuel R; Kravets, Yevgen; Jaroszynski, Dino A

    2015-01-01

    The next few years will see next-generation high-power laser facilities (such as the Extreme Light Infrastructure) become operational, for which it is important to understand how interaction with intense laser pulses affects the bulk properties of a relativistic electron beam. At such high field intensities, we expect both radiation reaction and quantum effects to play a significant role in the beam dynamics. The resulting reduction in relative energy spread (beam cooling) at the expense of mean beam energy predicted by classical theories of radiation reaction depends only on the energy of the laser pulse. Quantum effects suppress this cooling, with the dynamics additionally sensitive to the distribution of energy within the pulse. Since chirps occur in both the production of high-intensity pulses (CPA) and the propagation of pulses in media, the effect of using chirps to modify the pulse shape has been investigated using a semi-classical extension to the Landau--Lifshitz theory. Results indicate that even la...

  6. Beaconless operation for optimal laser beam propagation through turbulent atmosphere

    Science.gov (United States)

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-09-01

    Corruption of the wavefront, beam wondering and power density degradation at the receiving end are the effects typically observed at laser beam propagation through turbulent atmosphere. Compensation of these effects can be achieved if the reciprocal conditions for the propagating wave are satisfied along the propagation range. Practical realization of these conditions requires placing a localized beacon at the receiving end of the range and high-performance adaptive optics system (AOS). The key condition for an effective performance of AOS is a high value of the reciprocal component in the outgoing wave, since only this component is getting compensated after propagating turbulence perturbed path. The nonreciprocal components that is present in the wave directed toward the target is caused by three factors (detailed in this paper) that determine the partial restoration of the structure of the beacon beam. Thus solution of a complex problem of focusing the laser beam propagating through turbulent media can be achieved for the share of the outgoing wave that has a reciprocal component. This paper examines the ways and means that can be used in achieving the stated goal of effective laser power delivery on the distant image-resolved object.

  7. Diode laser power module for beamed power transmission

    Science.gov (United States)

    Choi, S. H.; Williams, M. D.; Lee, J. H.; Conway, E. J.

    1991-01-01

    Recent progress with powerful, efficient, and coherent monolithic diode master-oscillator/power-amplifier (M-MOPA) systems is promising for the development of a space-based diode laser power station. A conceptual design of a 50-kW diode laser power module was made for space-based power stations capable of beaming coherent power to the moon, Martian rovers, or other satellites. The laser diode power module consists of a solar photovoltaic array or nuclear power source, diode laser arrays (LDAs), a phase controller, beam-steering optics, a thermal management unit, and a radiator. Thermal load management and other relevant aspects of the system (such as power requirements and system mass) are considered. The 50-kW power module described includes the highest available efficiency of LD M-MOPA system to date. However, the overall efficiency of three amplifier stages, including the coupling efficiency, turns out to be 55.5 percent. Though a chain of PA stages generates a high-power coherent beam, there is a penalty due to the coupling loss between stages. The specific power of the 50-kW module using solar power is 6.58 W/kg.

  8. Distribution uniformity of laser-accelerated proton beams

    Science.gov (United States)

    Zhu, Jun-Gao; Zhu, Kun; Tao, Li; Xu, Xiao-Han; Lin, Chen; Ma, Wen-Jun; Lu, Hai-Yang; Zhao, Yan-Ying; Lu, Yuan-Rong; Chen, Jia-Er; Yan, Xue-Qing

    2017-09-01

    Compared with conventional accelerators, laser plasma accelerators can generate high energy ions at a greatly reduced scale, due to their TV/m acceleration gradient. A compact laser plasma accelerator (CLAPA) has been built at the Institute of Heavy Ion Physics at Peking University. It will be used for applied research like biological irradiation, astrophysics simulations, etc. A beamline system with multiple quadrupoles and an analyzing magnet for laser-accelerated ions is proposed here. Since laser-accelerated ion beams have broad energy spectra and large angular divergence, the parameters (beam waist position in the Y direction, beam line layout, drift distance, magnet angles etc.) of the beamline system are carefully designed and optimised to obtain a radially symmetric proton distribution at the irradiation platform. Requirements of energy selection and differences in focusing or defocusing in application systems greatly influence the evolution of proton distributions. With optimal parameters, radially symmetric proton distributions can be achieved and protons with different energy spread within ±5% have similar transverse areas at the experiment target. Supported by National Natural Science Foundation of China (11575011, 61631001) and National Grand Instrument Project (2012YQ030142)

  9. Evolution of a Gaussian laser beam in warm collisional magnetoplasma

    Science.gov (United States)

    Jafari, M. J.; Jafari Milani, M. R.; Niknam, A. R.

    2016-07-01

    In this paper, the spatial evolution of an intense circularly polarized Gaussian laser beam propagated through a warm plasma is investigated, taking into account the ponderomotive force, Ohmic heating, external magnetic field, and collisional effects. Using the momentum transfer and energy equations, both modified electron temperature and electron density in plasma are obtained. By introducing the complex dielectric permittivity of warm magnetized plasma and using the complex eikonal function, coupled differential equations for beam width parameter are established and solved numerically. The effects of polarization state of laser and magnetic field on the laser spot size evolution are studied. It is observed that in case of the right-handed polarization, an increase in the value of external magnetic field causes an increase in the strength of the self-focusing, especially in the higher values, and consequently, the self-focusing occurs in shorter distance of propagation. Moreover, the results demonstrate the existence of laser intensity and electron temperature ranges where self-focusing can occur, while the beam diverges outside of these regions; meanwhile, in these intervals, there exists a turning point for each of intensity and temperature in which the self-focusing process has its strongest strength. Finally, it is found that the self-focusing effect can be enhanced by increasing the plasma frequency (plasma density).

  10. Dense monoenergetic proton beams from chirped laser-plasma interaction

    CERN Document Server

    Galow, Benjamin J; Liseykina, Tatyana V; Harman, Zoltan; Keitel, Christoph H

    2011-01-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen plasma cell is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10^7 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1 %) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10^21 W/cm^2.

  11. Dense monoenergetic proton beams from chirped laser-plasma interaction.

    Science.gov (United States)

    Galow, Benjamin J; Salamin, Yousef I; Liseykina, Tatyana V; Harman, Zoltán; Keitel, Christoph H

    2011-10-28

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultraintense (10(7) particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10(21) W/cm(2).

  12. Dense monoenergetic proton beams from chirped laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Galow, Benjamin J.; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Department of Physics, American University of Sharjah, POB 26666, Sharjah (United Arab Emirates); Liseykina, Tatyana V. [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany); Harman, Zoltan [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); ExtreMe Matter Institute EMMI, Planckstrasse 1, 64291 Darmstadt (Germany)

    2012-07-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10{sup 7} particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10{sup 21} W/cm{sup 2}.

  13. Dense monoenergetic proton beams from chirped laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianxing; Galow, Benjamin J.; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Department of Physics, American University of Sharjah, POB 26666, Sharjah (United Arab Emirates); Harman, Zoltan [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); ExtreMe Matter Institute EMMI, Planckstrasse 1, 64291 Darmstadt (Germany)

    2013-07-01

    Interactions of linearly and radially polarized frequency-chirped laser pulses with single protons and hydrogen gas targets are studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultra-intense (10{sup 7} particles per bunch) and phase-space collimated beams of protons is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10{sup 21} W/cm{sup 2}.

  14. Challenges in plasma and laser wakefield accelerated beams diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Cianchi, A., E-mail: alessandro.cianchi@roma2.infn.it [University of Rome Tor Vergata and INFN, V. della Ricerca Scientifica 1, 00133 Rome (Italy); Anania, M.P.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Ferrario, M.; Gatti, G. [INFN-LNF - Via E. Fermi 40, 00044 Frascati (RM) (Italy); Marchetti, B. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Mostacci, A. [University of Rome La Sapienza, P.le Aldo Moro 5, 00185 Rome (Italy); Pompili, R. [INFN-LNF - Via E. Fermi 40, 00044 Frascati (RM) (Italy); Ronsivalle, C. [ENEA C.R. Frascati, Via E. Fermi,45 00044 Frascati (RM) (Italy); Rossi, A.R.; Serafini, L. [INFN-Mi, Via Celoria, 16 20133 Milano (Italy)

    2013-08-21

    The new frontier in the particle beam accelerator is the so called plasma acceleration. Using the strong electric field inside a plasma it is possible to achieve accelerating gradients in the order of magnitude larger with respect to the actual technologies. Different schemes have been proposed and several already tested, producing beams of energy of several GeV. Mainly two approaches are followed: either the beam is directly produced by the interaction of a TW/PW class laser with a gas jet or a preexisting particle beam is accelerated in a plasma channel. In both cases a precise determination of the emerging beam parameters is mandatory for the fine tuning of the devices. The measurement of these parameters, in particular the emittance, is not trivial, mainly due to the large energy spread and to the tight focusing of these beams or to the background noise produced in the plasma channel. We show the problems related to the diagnostic of this kind of beams and the proposed or already realized solutions.

  15. Challenges in plasma and laser wakefield accelerated beams diagnostic

    Science.gov (United States)

    Cianchi, A.; Anania, M. P.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Ferrario, M.; Gatti, G.; Marchetti, B.; Mostacci, A.; Pompili, R.; Ronsivalle, C.; Rossi, A. R.; Serafini, L.

    2013-08-01

    The new frontier in the particle beam accelerator is the so called plasma acceleration. Using the strong electric field inside a plasma it is possible to achieve accelerating gradients in the order of magnitude larger with respect to the actual technologies. Different schemes have been proposed and several already tested, producing beams of energy of several GeV. Mainly two approaches are followed: either the beam is directly produced by the interaction of a TW/PW class laser with a gas jet or a preexisting particle beam is accelerated in a plasma channel. In both cases a precise determination of the emerging beam parameters is mandatory for the fine tuning of the devices. The measurement of these parameters, in particular the emittance, is not trivial, mainly due to the large energy spread and to the tight focusing of these beams or to the background noise produced in the plasma channel. We show the problems related to the diagnostic of this kind of beams and the proposed or already realized solutions.

  16. Laser beaming demonstrations to high-orbit satellites

    Science.gov (United States)

    Lipinski, Ronald J.; Meister, Dorothy C.; Tucker, Steve D.; Fugate, Robert Q.; Leatherman, Phillip; Maes, Carl F.; Lange, W. Joseph; Cowan, William D.; Meulenberg, Andrew; Cleis, Richard A.; Spinhirne, James M.; Ruane, Raymond E.; Michie, Robert B.; Vonderhaar, Donald F.

    1994-05-01

    A team of Phillips Laboratory, COMSAT Laboratories, and Sandia National Laboratories plans to demonstrate state-of-the-art laser-beaming demonstrations to high-orbit satellites. The demonstrations will utilize the 1.5-m diameter telescope with adaptive optics at the AFPL Starfire Optical Range (SOR) and a ruby laser provided by the Air Force and Sandia (1 - 50 kW and 6 ms at 694.3 nm). The first targets will be corner-cube retro-reflectors left on the moon by the Apollo 11, 14, and 15 landings. We attempt to use adaptive optics for atmospheric compensation to demonstrate accurate and reliable beam projection with a series of shots over a span of time and shot angle. We utilize the return signal from the retro- reflectors to help determine the beam diameter on the moon and the variations in pointing accuracy caused by atmospheric tilt. This is especially challenging because the retro-reflectors need to be in the lunar shadow to allow detection over background light. If the results from this experiment are encouraging, we will at a later date direct the beam at a COMSAT satellite in geosynchronous orbit as it goes into the shadow of the earth. We utilize an onboard monitor to measure the current generated in the solar panels on the satellite while the beam is present. A threshold irradiance of about 4 W/m2 on orbit is needed for this demonstration.

  17. Laser characterization with advanced digital signal processing

    DEFF Research Database (Denmark)

    Piels, Molly; Tafur Monroy, Idelfonso; Zibar, Darko

    2015-01-01

    The use of machine learning techniques to characterize lasers with low output power is reviewed. Optimized phase tracking algorithms that can produce accurate noise spectra are discussed, and a method for inferring the amplitude noise spectrum and rate equation model of the laser under test is pr...

  18. Vortex array laser beam generation from a Dove prism-embedded unbalanced Mach-Zehnder interferometer.

    Science.gov (United States)

    Chu, Shu-Chun; Yang, Chao-Shun; Otsuka, Kenju

    2008-11-24

    This paper proposes a new scheme for generating vortex laser beams from a laser. The proposed system consists of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer configuration. This configuration allows controlled construction of p x p vortex array beams from Ince-Gaussian modes, IG(e) (p,p) modes. An incident IG(e)(p,p) laser beam of variety order p can easily be generated from an end-pumped solid-state laser system with an off-axis pumping mechanism. This study simulates this type of vortex array laser beam generation, analytically derives the vortex positions of the resulting vortex array laser beams, and discusses beam propagation effects. The resulting vortex array laser beam can be applied to optical tweezers and atom traps in the form of two-dimensional arrays, or used to study the transfer of angular momentum to micro particles or atoms (Bose-Einstein condensate).

  19. Asymmetrical prism for beam shaping of laser diode stacks.

    Science.gov (United States)

    Zeng, Xiaodong; Cao, Changqing; An, Yuying

    2005-09-10

    A beam-shaping scheme for a laser diode stack to obtain a flattop output intensity profile is proposed. The shaping element consists of an asymmetrical glass prism. The large divergence-angle compression in the direction perpendicular to the junction plane and the small divergence-angle expansion in the parallel direction are performed simultaneously by a single shaping element. The transformation characteristics are presented, and the optimization performance is investigated based on the ray-tracing method. Analysis shows that a flattop intensity profile can be obtained. This beam-shaping system can be fabricated easily and has a large alignment tolerance.

  20. Analysis of laser beam propagation in a turbulent atmosphere

    Science.gov (United States)

    Clarke, R. H.

    1985-09-01

    The beam propagation method, based on the parabolic approximation to the wave equation, is used in conjunction with Papoulis' redefinition for optical fields of Woodward's ambiguity function. A simple derivation is given of Tatarskii's formula for the lateral coherence function, and hence the mean intensity profile, of a laser beam propagating through a turbulent atmosphere. Statistics of the received signal and the effects of spatial nonstationarity of the turbulence can also be deduced using this technique, as can the effects of very large-scale variations in refractive index and receiver directivity.

  1. Upgrade of laser and electron beam welding database

    CERN Document Server

    Furman, Magdalena

    2014-01-01

    The main purpose of this project was to fix existing issues and update the existing database holding parameters of laser-beam and electron-beam welding machines. Moreover, the database had to be extended to hold the data for the new machines that arrived recently at the workshop. As a solution - the database had to be migrated to Oracle framework, the new user interface (using APEX) had to be designed and implemented with the integration with the CERN web services (EDMS, Phonebook, JMT, CDD and EDH).

  2. Beam instability in 980-nm power lasers: Experiment and analysis

    Science.gov (United States)

    Guthrie, James; Tan, G. L.; Ohkubo, M.; Fukushima, T.; Ikegami, Y.; Ijichi, T.; Irikawa, M.; Mand, R. S.; Xu, J. M.

    1994-12-01

    A theoretical analysis of beam instability (steering), commonly observed in high power ridge waveguide laser diodes is presented. A physical model of multiple interfering lateral modes is proposed and implemented in a two-dimensional self-consistent numerical code. It is shown that the dynamic evolution of the effective waveguide and the coherent lasing of emergent multiple lateral modes of the waveguide under high injection could lead to beam steering and knees in the fiber coupled L-I characteristics. The theory of simultaneous lasing and interaction between several lateral modes is found to be consistent with the observed back-plane radiation image.

  3. Propagation of a laser-driven relativistic electron beam inside a solid dielectric.

    Science.gov (United States)

    Sarkisov, G S; Ivanov, V V; Leblanc, P; Sentoku, Y; Yates, K; Wiewior, P; Chalyy, O; Astanovitskiy, A; Bychenkov, V Yu; Jobe, D; Spielman, R B

    2012-09-01

    Laser probe diagnostics: shadowgraphy, interferometry, and polarimetry were used for a comprehensive characterization of ionization wave dynamics inside a glass target induced by a laser-driven, relativistic electron beam. Experiments were done using the 50-TW Leopard laser at the University of Nevada, Reno. We show that for a laser flux of ∼2 × 10(18) W/cm2 a hemispherical ionization wave propagates at c/3 for 10 ps and has a smooth electron-density distribution. The maximum free-electron density inside the glass target is ∼2 × 10(19) cm-3, which corresponds to an ionization level of ∼0.1%. Magnetic fields and electric fields do not exceed ∼15 kG and ∼1 MV/cm, respectively. The electron temperature has a hot, ringlike structure with a maximum of ∼0.7 eV. The topology of the interference phase shift shows the signature of the "fountain effect", a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields driven by laser. The very low ionization observed after the laser heating pulse suggests a fast recombination on the sub-ps time scale.

  4. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    Science.gov (United States)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL Z target via bremsstrahlung into low-divergence (Z, the resulting Ne+ /Ne- ratio can approach unity, resulting in a near neutral density plasma jet. These quasi-neutral beams are presumed to retain the short-pulse (τL characteristic of the electron beam, resulting in a high peak density of ne- /e+ ~ 1016 cm-3 , making the source an excellent candidate for laboratory study of astrophysical leptonic jets. Alternatively, the electron beam can be interacted with a counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  5. Reconstruction of laser beam wavefronts based on mode analysis

    CSIR Research Space (South Africa)

    Schulze, C

    2013-07-01

    Full Text Available . Insets depict the shapes of the corresponding aberrations. Fig. 3. Schematic of the experimental setup to modally decom- pose differently aberrated Gaussian beams. He–Ne, helium–neon laser; L 1–5 , lenses; M, mirror; SLM 1;2, spatial light modulator... for Scientific and Industrial Research, National Laser Centre, P.O. Box 395, 0001 Pretoria, South Africa *Corresponding author: christian.schulze@uni‐jena.de Received 17 May 2013; revised 26 June 2013; accepted 26 June 2013; posted 27 June 2013 (Doc. ID 190739...

  6. A cold atom pyramidal gravimeter with a single laser beam

    Science.gov (United States)

    Bodart, Q.; Merlet, S.; Malossi, N.; Dos Santos, F. Pereira; Bouyer, P.; Landragin, A.

    2010-03-01

    We demonstrate a scheme for realizing a compact cold atom gravimeter. The use of a hollow pyramidal configuration allows to achieve all functions: trapping, interferometer and detection with a unique laser beam leading to a drastic reduction in complexity and volume. In particular, we demonstrate a relative sensitivity to acceleration of gravity (g) of 1.7×10-7 at one second, with a moderate laser power of 50 mW. This simple geometry combined to such a high sensitivity opens wide perspectives for practical applications.

  7. A cold atom pyramidal gravimeter with a single laser beam

    CERN Document Server

    Bodart, Quentin; Malossi, Nicola; Santos, Franck Pereira Dos; Bouyer, Philippe; Landragin, Arnaud

    2010-01-01

    We demonstrate a scheme for realizing a compact cold atom gravimeter. The use of a hollow pyramidal configuration allows to achieve all functions: trapping, interferometer and detection with a unique laser beam leading to a drastic reduction in complexity and volume. In particular, we demonstrate a relative sensitivity to acceleration of gravity (g) of 1.7 x 10-7 at one second, with a moderate laser power of 50 mW. This simple geometry combined to such a high sensitivity opens wide perspectives for practical applications (P. Bouyer and A. Landragin, patent number FR2009/000252, 2009).

  8. Model for Atmospheric Propagation of Spatially Combined Laser Beams

    Science.gov (United States)

    2016-09-01

    AGENCY USE ONLY (Leave Blank) 2. REPORT DATE Sept 2016 3. REPORT TYPE AND DATES COVERED Master’s Thesis 12-01-2015 to 09-23-2016 4. TITLE AND SUBTITLE...the thesis starts with an overview of DE weapons and end with the dierent types of available laser sources. In Chapter 3, the thesis discussed... fluoride to produce a 4 µm laser and was integrated with the SeaLite Beam director for operational testing. Due to MIRACL’s wavelength, it was prone to

  9. Characterizing and Controlling Beam Losses at the LANSCE Facility

    Energy Technology Data Exchange (ETDEWEB)

    Rybarcyk, Lawrence J. [Los Alamos National Laboratory

    2012-09-12

    The Los Alamos Neutron Science Center (LANSCE) currently provides 100-MeV H{sup +} and 800-MeV H{sup -} beams to several user facilities that have distinct beam requirements, e.g. intensity, micropulse pattern, duty factor, etc. Minimizing beam loss is critical to achieving good performance and reliable operation, but can be challenging in the context of simultaneous multi-beam delivery. This presentation will discuss various aspects related to the observation, characterization and minimization of beam loss associated with normal production beam operations in the linac.

  10. Characterization of Nonparaxial Truncated Cosine-Gaussian Beams and the Beam Quality in the Far Field

    Institute of Scientific and Technical Information of China (English)

    KANG Xiao-Ping; L(U) Bai-Da

    2006-01-01

    @@ The analytical expression characterizing the propagation of nonparaxial truncated cosine-Gaussian (CoG) beams in free space is derived, and some special cases are discussed. The extended power in the bucket (PIB) is proposed to characterize the beam quality of nonparaxial truncated beams in the far field. It is shown that the extended PIB is applicable to nonparaxial truncated beams, and the PIB of nonparaxial truncated CoG beams depends on the decentred parameter, waist-width-to-wavelength ratio, truncation parameter, and bucket size chosen.

  11. Gaussian laser beam transformation into an optical vortex beam by helical lens

    CERN Document Server

    Janicijevic, Ljiljana

    2015-01-01

    In this article we investigate the Fresnel diffraction characteristics of the hybrid optical element which is a combination of a spiral phase plate (SPP) with topological charge p and a thin lens with focal length f, named the helical lens (HL). As incident a Gaussian laser beam is treated, having its waist a distance from the HL plane and its axis passing through the centre of the HL. It is shown that the SPP introduces a phase singularity of p-th order to the incident beam, while the lens transforms the beam characteristic parameters. The output light beam is analyzed in detail: its characteristic parameters and focusing properties, amplitude and intensity distributions and the vortex rings profiles and radii, at any z distance behind the HL plane, as well as in the near and far field.

  12. Power transmission by laser beam from lunar-synchronous satellite

    Science.gov (United States)

    Williams, M. D.; Deyoung, R. J.; Schuster, G. L.; Choi, S. H.; Dagle, J. E.; Coomes, E. P.; Antoniak, Z. I.; Bamberger, J. A.; Bates, J. M.; Chiu, M. A.

    1993-01-01

    The possibility of beaming power from synchronous lunar orbits (the L1 and L2 Lagrange points) to a manned long-range lunar rover is addressed. The rover and two versions of a satellite system (one powered by a nuclear reactor, the other by photovoltaics) are described in terms of their masses, geometries, power needs, missions, and technological capabilities. Laser beam power is generated by a laser diode array in the satellite and converted to 30 kW of electrical power at the rover. Present technological capabilities, with some extrapolation to near future capabilities, are used in the descriptions. The advantages of the two satellite/rover systems over other such systems and over rovers with onboard power are discussed along with the possibility of enabling other missions.

  13. Advanced rapid prototyping by laser beam sintering of metal prototypes: design and development of an optimized laser beam delivery system

    Science.gov (United States)

    Geiger, Manfred; Coremans, A.; Neubauer, Norbert; Niebling, F.

    1996-08-01

    Fast technological advances and steadily increasing severe worldwide competition force industry to respond all the time faster to new and chanced customer wishes. Some of the recently emerged processes, commonly referred to as 'rapid prototyping' (RP), have proved to be powerful tools for accelerating product and process development. Early approaches aimed at the automated production of plastic models. These techniques achieved industrial maturity extremely fast and are meanwhile established as standard utilities in the field of development/design processes. So far, their applicability to metal working industry was limited to design studies because the mechanical properties of the prototypes, e.g. modulus of elasticity and mechanical strength were not comparable to the final products they represented. Therefore, RP-processes aimed at the direct production of metallic prototypes gained more and more importance during recent years. A technique belonging to this group is manufacturing of prototypes by using a laser beam sintering machine capable of directly processing metal powders. This so called laser beam sintering process showed a great potential for direct manufacturing of functional tools and prototypes in early feasibility studies. Detailed examinations were performed at several research centers to determine the attainable quality of the parts concerning roughness, dimensional accuracy and mechanical strength. These examinations showed, that there still is a considerable demand for quality improvements of the previously mentioned parameters. The practical application and the potential for improvement of the geometrical accuracy of laser beam sintered parts by using a dual beam concept was proven. An innovative beam guiding and forming concept, similar to the previously mentioned patented beam guiding system, was developed and built with the goal to improve the process parameters governing mechanical properties as well as geometrical accuracy. Further reaching

  14. Production of petawatt laser pulses of picosecond duration via Brillouin amplification of nanosecond laser beams

    CERN Document Server

    Humphrey, Kathryn; Alves, Paulo; Fiuza, Frederico; Speirs, David; Bingham, Robert; Cairns, Alan; Fonseca, Ricardo; Silva, Luis; Norreys, Peter

    2013-01-01

    Previous studies have shown that Raman amplification in plasma is a potential route for the production of petawatt pulses of picosecond duration at 351 nm [Trines et al., Phys. Rev. Lett. 107, 105002 (2011)]. In this paper we show, through analytic theory and particle-in-cell simulations, that similar results can also be obtained through Brillouin amplification of a short seed laser beam off a long pump beam at moderate intensity. Scaling laws governing the optimal parameter space for pump beam, seed beam and plasma will be derived using a self-similar model for Brillouin scattering, and verified via simulations. A comparison with Raman scattering will be made, to determine which scheme is most suitable for a range of laser-plasma configurations.

  15. Thermal response of photovoltaic cell to laser beam irradiation

    OpenAIRE

    Yuan, Yu-Chen; Wu, Chen-Wu

    2014-01-01

    This paper firstly presents the concept of using dual laser beam to irradiate the photovoltaic cell, so as to investigate the temperature dependency of the efficiency of long distance energy transmission. Next, the model on the multiple reflection and absorption of any monochromatic light in multilayer structure has been established, and the heat generation in photovoltaic cell has been interpreted in this work. Then, the finite element model has been set up to calculate the temperature of ph...

  16. Generating monoenergetic proton beam by using circularly polarlzed laser

    Institute of Scientific and Technical Information of China (English)

    LIU Bi-Cheng; YAN Xue-Qing; LIN Chen; Lu Yuan-Rong; GUO Zhi-Yu; FANG Jia-Xun; SHENG Zheng-Ming; LI Yu-Tong; CHEN Jia-Er

    2009-01-01

    The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model.It is found that with the balance between pondermotive force and electrostatic force,highly quasi-monoenergetic proton beam can be generated by Phase Stable Acceleration(PSA)process.As in conventional accelerators,ion will be accelerated and bunched up in the longitudinal direction at the same time.

  17. Study of tunable resonances in laser beam divergence and beam deflection

    CERN Document Server

    Kohazi-Kis, A; Gorbe, M; Nagy, P

    2012-01-01

    New, fundamental resonant properties of laser resonators are theoretically predicted and experimentally demonstrated. These resonances occur either in the time dependence of the beam width and that of beam radius of curvature of the wavefront or in the time dependent pointing and position stability of the output light beam of a laser resonator. The resonant frequency can be tuned continuously from zero to the round-trip frequency in the first case; and from zero to the half of the round-trip frequency in the second case, by for example, moving one of the mirrors of the resonator. In both cases besides a resonant frequency its complementary frequency to the round-trip frequency is also resonant, and their shifted frequencies by multiples of the round-trip frequency are also resonant. In our experimental demonstration we measured the radiofrequency noise spectrum of the output laser beam, that was partially blocked by a knife-edge. We observed increased noise at the theoretically predicted frequencies. Similar ...

  18. Development of laser beam injection system for the Edge Thomson Scattering (ETS) in ITER

    Science.gov (United States)

    Yatsuka, E.; Hatae, T.; Suitoh, S.; Ohara, M.; Hagita, K.; Inoue, K.; Bassan, M.; Walsh, M.; Itami, K.

    2016-01-01

    This paper focuses on the design and development of the laser injection system for the ITER Edge Thomson Scattering system (ETS). The ITER ETS achieves a temporal resolution of 100 Hz by firing two 50 Hz laser beams alternatively. The use of dual lasers enables us to perform the Thomson scattering measurements at a temporal resolution of 50 Hz in case that one of the laser systems stops functioning. A new type of beam combiner was developed to obtain a single beam that is collinear and fixed linearly polarized from two laser beams using a motor-driven rotating half-wave plate. The rotating half-wave plate method does not induce misalignment even if the rotating mechanism malfunctions. The combined beam is relayed from the diagnostic hall to the plasma using mirror optics and is absorbed at the beam dump integrated on the inner blanket. The beam alignment system was designed to direct the laser beam onto the center of the beam dump head. The beam position at the beam dump is monitored by four alignment laser beams which propagate parallel to the diagnostic Nd:YAG laser beam and imaging systems installed outside the diagnostic port.

  19. Thermal interaction of short-pulsed laser focused beams with skin tissues

    Energy Technology Data Exchange (ETDEWEB)

    Jiao Jian; Guo Zhixiong [Department of Mechanical and Aerospace Engineering, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)], E-mail: guo@jove.rutgers.edu

    2009-07-07

    Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

  20. Thermal interaction of short-pulsed laser focused beams with skin tissues

    Science.gov (United States)

    Jiao, Jian; Guo, Zhixiong

    2009-07-01

    Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

  1. Influence of laser power on deposition of the chromium atomic beam in laser standing wave

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    One-dimensional deposition of collimated Cr atomic beam focused by a near-resonant Gaussian standing-laser field with wavelength of 425.55 nm is examined from particle-optics approach by using an adaptive step size,fourth-order Runge-Kutta type algorithm.The influence of laser power on deposition of atoms in laser standing wave is discussed and the simulative result shows that the FWHM of nanometer stripe is 102 nm and contrast is 2:1 with laser power equal to 3 mW,the FWHM is 1.2 nm and contrast is 32:1 with laser power equal to 16 mW,but with laser power increase,equal to 50 mW,the nonmeter structure forms the multi-crests and exacerbates.

  2. Influence of laser power on deposition of the chromium atomic beam in laser standing wave

    Institute of Scientific and Technical Information of China (English)

    ZHANG WenTao; ZHU BaoHua; ZHANG BaoWu; LI TongBao

    2009-01-01

    One-dimensional deposition of collimated Cr atomic beam focused by a near-resonant Gaussian standing-laser field with wavelength of 425.55 nm is examined from particle-optics approach by using an adaptive step size, fourth-order Runge-Kutta type algorithm. The influence of laser power on depo-sition of atoms in laser standing wave is discussed and the simulative result shows that the FWHM of nanometer stripe is 102 nm and contrast is 2:1 with laser power equal to 3 mW, the FWHM is 1.2 nm and contrast is 32:1 with laser power equal to 16 mW, but with laser power increase, equal to 50 mW, the nonmeter structure forms the multi-crests and exacerbates.

  3. Biomimetic surface structuring using cylindrical vector femtosecond laser beams

    Science.gov (United States)

    Skoulas, Evangelos; Manousaki, Alexandra; Fotakis, Costas; Stratakis, Emmanuel

    2017-03-01

    We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams. Depending on the irradiation conditions, new complex multi-directional nanostructures, inspired by the Shark’s skin morphology, as well as superhydrophobic dual-scale structures mimicking the Lotus’ leaf water repellent properties can be attained. It is concluded that the versatility and features variations of structures formed is by far superior to those obtained via laser processing with linearly polarized beams. More important, by exploiting the capabilities offered by fs CV fields, the present technique can be further extended to fabricate even more complex and unconventional structures. We believe that our approach provides a new concept in laser materials processing, which can be further exploited for expanding the breadth and novelty of applications.

  4. Optical beam-shaping design based on aspherical lenses for circularization collimation, and expansion of elliptical laser beams

    Science.gov (United States)

    Serkan, Mert; Kirkici, Hulya

    2008-01-01

    We present two optical system designs using aspherical lenses for beam circularization, collimation, and expansion of semiconductor lasers for possible application in lidar systems. Two different optical lens systems are investigated; namely, two aspherical lens and single aspherical lens systems. Software package programs of ZEMAX and MATLAB to simulate the optical designs are used. The beam reshaping results are presented for one specific laser beam output.

  5. Transverse and longitudinal characterization of electron beams using interaction with optical near-fields

    CERN Document Server

    Kozák, Martin; Leedle, Kenneth J; Deng, Huiyang; Schönenberger, Norbert; Ruehl, Axel; Hartl, Ingmar; Hoogland, Heinar; Holzwarth, Ronald; Harris, James S; Byer, Robert L; Hommelhoff, Peter

    2016-01-01

    We demonstrate an experimental technique for both transverse and longitudinal characterization of bunched femtosecond free electron beams. The operation principle is based on monitoring of the current of electrons that obtained an energy gain during the interaction with the synchronized optical near-field wave excited by femtosecond laser pulses. The synchronous accelerating/decelerating fields confined to the surface of a silicon nanostructure are characterized using a highly focused sub-relativistic electron beam. Here the transverse spatial resolution of 450 nm and femtosecond temporal resolution achievable by this technique are demonstrated.

  6. Vanishing tilt-to-length coupling for a singular case in two-beam laser interferometers with Gaussian beams

    CERN Document Server

    Schuster, Sönke; Tröbs, Michael; Heinzel, Gerhard

    2014-01-01

    The omnipresent tilt-to-length coupling in two-beam laser interferometers, frequently a nuisance in precision measurements, vanishes for the singular case of two beams with identical parameters and complete detection of both beams without clipping. This effect has been observed numerically and is explained in this paper by the cancellation of two very different effects of equal magnitude and opposite sign.

  7. A Programmable Beam Shaping System for Tailoring the Profile of High Fluence Laser Beams

    Energy Technology Data Exchange (ETDEWEB)

    Heebner, J; Borden, M; Miller, P; Stolz, C; Suratwala, T; Wegner, P; Hermann, M; Henesian, M; Haynam, C; Hunter, S; Christensen, K; Wong, N; Seppala, L; Brunton, G; Tse, E; Awwal, A; Franks, M; Marley, E; Williams, K; Scanlan, M; Budge, T; Monticelli, M; Walmer, D; Dixit, S; Widmayer, C; Wolfe, J; Bude, J; McCarty, K; DiNicola, J

    2010-11-10

    Customized spatial light modulators have been designed and fabricated for use as precision beam shaping devices in fusion class laser systems. By inserting this device in a low-fluence relay plane upstream of the amplifier chain, 'blocker' obscurations can be programmed into the beam profile to shadow small isolated flaws on downstream optical components that might otherwise limit the system operating energy. In this two stage system, 1920 x 1080 bitmap images are first imprinted on incoherent, 470 nm address beams via pixilated liquid crystal on silicon (LCoS) modulators. To realize defined masking functions with smooth apodized shapes and no pixelization artifacts, address beam images are projected onto custom fabricated optically-addressable light valves. Each valve consists of a large, single pixel liquid cell in series with a photoconductive Bismuth silicon Oxide (BSO) crystal. The BSO crystal enables bright and dark regions of the address image to locally control the voltage supplied to the liquid crystal layer which in turn modulates the amplitude of the coherent beams at 1053 nm. Valves as large as 24 mm x 36 mm have been fabricated with low wavefront distortion (<0.5 waves) and antireflection coatings for high transmission (>90%) and etalon suppression to avoid spectral and temporal ripple. This device in combination with a flaw inspection system and optic registration strategy represents a new approach for extending the operational lifetime of high fluence laser optics.

  8. Research on beam splitting prism in laser heterodyne interferometer

    Science.gov (United States)

    Fu, Xiu-hua; Xiong, Shi-fu; Kou, Yang; Pan, Yong-gang; Chen, Heng; Li, Zeng-yu; Zhang, Chuan-xin

    2014-08-01

    With the rapid development of optical testing technology, laser heterodyne interferometer has been used more and more widely. As the testing precision requirements continue to increase, the technical prism is an important component of heterodyne interference. The research utilizing thin film technology to improve optical performance of interferometer has been a new focus. In the article, based on the use requirements of interferometer beam splitting prism, select Ta2O5 and SiO2 as high and low refractive index materials respectively, deposit on substrate K9. With the help of TFCalc design software and Needle method, adopting electron gun evaporation and ion assisted deposition, the beam splitting prism is prepared successfully and the ratio of transmittance and reflectance for this beam splitting prism in 500~850 nm band, incident angle 45 degree is 8:2. After repeated tests, solved the difference problem of film deposition process parameters ,controlled thickness monitoring precision effectively and finally prepared the ideal beam splitting prism which is high adhesion and stable optics properties. The film the laser induced damage threshold and it meet the requirements of heterodyne interferometer for use.

  9. Laser Beam MicroMachining (LBMM) - A review

    Science.gov (United States)

    Mishra, Sanjay; Yadava, Vinod

    2015-10-01

    The use of short and ultrashort laser pulses for micromachining application is an emerging technology. Laser Beam MicroMachining (LBMM) has revolutionized many industries by providing innovative solutions in numerous industrial micro-engineering applications. High-intensity short or ultrashort laser pulses are powerful thermal energy source for creating micro-features in wide range of materials. These lasers can precisely ablate various types of materials with little or no collateral damage. An overview of LBMM is given so that we can obtain a current view of capabilities and tradeoffs associated with LBMM of sub-micron size. The fundamental understanding of ultrafast laser ablation process has been elucidated and the various research activities performed with nanosecond, picosecond and femtosecond, lasers have been discussed to understand the physical mechanisms and the critical experimental parameters involved in the LBMM. The critical analysis of various theoretical and experimental models used to describe the performance analysis of LBMM has been elaborated so that we can identify the relevant principles underlying the process.

  10. 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.

  11. Ion-beam assisted laser fabrication of sensing plasmonic nanostructures

    CERN Document Server

    Kuchmizhak, Aleksandr; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

    2015-01-01

    Simple high-performance two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique a thin noble metal film on a dielectric substrate is irradiated by a tightly focused single nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar+) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar+-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depends on the laser pulse energy and metal film thickness, while subsequent Ar+-ion polishing enables to vary height of the resulting nanostructures. The plasmon...

  12. Laser and focused ion beam combined machining for micro dies.

    Science.gov (United States)

    Yoshida, Y; Okazaki, W; Uchida, T

    2012-02-01

    We have developed a laser and focused ion beam (FIB) compound process for press mold dies of a micro lens array (MLA) and a micro needle array (MNA) in a glassy carbon (GC). The press mold die of the MLA was roughly fabricated by UV-YAG laser. After this process, we finished this surface by scanning FIB. As a result, higher accuracy and good roughness of surface profile can be realized. An optical glass is used to confirm the shape of lens. Moreover, we fabricated 6 × 6 through-holes in the GC by the spiral drilling in addition to the focus position movement of the UV laser for press mold die of the MNA. After the FIB process, we were able to make the needle die of surface and hole wall roughness less than 0.9 μm. A silicon rubber is used to confirm the shape of the holes.

  13. Optimization of electron-beam pumped excimer laser

    Science.gov (United States)

    Lowum, T. F.; Swecker, J. L.

    The output energy of an electron-beam pumped xenon flouride laser has been enhanced by optimizing certain electron-gun and gas-mix parameters. The optimized e-gun parameters include anode-cathode spacing, magnetic field strength, and cathode voltage. The optimized laser gas parameters include NF3 concentration, Xe concentration, and total pressure. The shortest anode-cathode spacing (9 cm), the strongest magnetic guide field (1600 Gauss), and the highest cathode voltage (375 kV) gave the highest laser output. The optimum gas concentrations were 0.05 percent NF3, 0.3 percent Xe, with Ne added to bring the total gas pressure to 60 psia. The energy degraded by 2 percent per shot with this gas mix.

  14. Polarization measurement of Cs using the pump laser beam

    CERN Document Server

    Fang, Jiancheng; Duan, Lihong; Fan, Wenfeng; Jiang, Liwei

    2015-01-01

    In the optical pumping systems based on the pump-probe arrangement, the spin polarization of the atoms is generally monitored utilizing the probe laser beam, in which way an extra perturbation must be introduced and thus affects the normal operation of the sensors. By investigating the absorption rate of the circularly polarized pump laser, here we demonstrate the feasibility of extracting the electron-spin polarization from the transmitted pump laser intensity. We experimentally validate the method in a spin-exchange relaxation free (SERF) magnetometer and the results are in excellent agreement with the theory. The scheme operates in a silent mode and features a real-time observation. We also study the corresponding magnetic field response of the SERF magnetometer and a term arising from the diffusion effects has been added to the original model to explain the discrepancy of the response.

  15. Beam shaping for kilowatt fiber-coupled diode lasers by using one-step beam cutting-rotating of prisms.

    Science.gov (United States)

    Wu, Yulong; Dong, Zhiyong; Chen, Yongqi; Qi, Yaoyao; Yuan, Xiandan; Qi, Yunfei; Xu, Li; Lin, Xuechun; Zou, Yonggang; Zhao, Pengfei

    2016-12-01

    The beam quality mismatch of laser diode stacks in both axes limits many direct applications for fiber or solid laser pumping and material processing. In this paper, a one-step cutting-rotating beam shaping system has been designed to homogenize the beam quality of two polarization-multiplexing laser diode stacks. Coupling laser diode stacks consisting of eight bars into a standard fiber with a core diameter of 600 μm and an NA of 0.22 is achieved. The simulative result shows that the system will have an output power over 1056 W. By using the technique, the production of compact and high brightness fiber-coupling diode lasers can be directly used for laser cladding and laser surface hardening processes.

  16. Ponderomotive self-focusing of Gaussian laser beam in warm collisional plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jafari Milani, M. R., E-mail: mrj.milani@gmail.com [Plasma Physics Research School, Tehran (Iran, Islamic Republic of); Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Niknam, A. R., E-mail: a-niknam@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of); Farahbod, A. H. [Plasma Physics Research School, Tehran (Iran, Islamic Republic of)

    2014-06-15

    The propagation characteristics of a Gaussian laser beam through warm collisional plasma are investigated by considering the ponderomotive force nonlinearity and the complex eikonal function. By introducing the dielectric permittivity of warm unmagnetized plasma and using the WKB and paraxial ray approximations, the coupled differential equations defining the variations of laser beam parameters are obtained and solved numerically. Effects of laser and plasma parameters such as the collision frequency, the initial laser intensity and its spot size on the beam width parameter and the axis laser intensity distribution are analyzed. It is shown that, self-focusing of the laser beam takes place faster by increasing the collision frequency and initial laser spot size and then after some distance propagation the laser beam abruptly loses its initial diameter and vastly diverges. Furthermore, the modified electron density distribution is obtained and the collision frequency effect on this distribution is studied.

  17. Real-time determination of laser beam quality by modal decomposition

    CERN Document Server

    Schmidt, Oliver A; Flamm, Daniel; Brüning, Robert; Kaiser, Thomas; Schröter, Siegmund; Duparré, Michael

    2011-01-01

    We present a real-time method to determine the beam propagation ratio M^2 of laser beams. The all-optical measurement of modal amplitudes yields M^2 parameters conform to the ISO standard method. The experimental technique is simple and fast, which allows to investigate laser beams under conditions inaccessible to other methods.

  18. Electron-beam-controlled laser with a grid-controlled electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Avanesyan, V.S.; Dutov, A.I.; Lakhno, Y.V.; Malkhov, L.N.

    1977-08-01

    An experimental investigation was made of an electron-beam-controlled carbon dioxide laser with an electron gun in which the beam current was modulated by a control grid. The design features of the electron gun and laser are described and their performance is reported. Observations of instabilities of the electron beam in the gun are reported and methods for eliminating them are suggested.

  19. Real-time determination of laser beam quality by modal decomposition.

    Science.gov (United States)

    Schmidt, Oliver A; Schulze, Christian; Flamm, Daniel; Brüning, Robert; Kaiser, Thomas; Schröter, Siegmund; Duparré, Michael

    2011-03-28

    We present a real-time method to determine the beam propagation ratio M2 of laser beams. The all-optical measurement of modal amplitudes yields M2 parameters conform to the ISO standard method. The experimental technique is simple and fast, which allows to investigate laser beams under conditions inaccessible to other methods.

  20. Vacuum electron acceleration and bunch compression by a flat-top laser beam.

    Science.gov (United States)

    Wang, W; Wang, P X; Ho, Y K; Kong, Q; Gu, Y; Wang, S J

    2007-09-01

    The field intensity distribution and phase velocity characteristics of a flat-top laser beam are analyzed and discussed. The dynamics of electron acceleration in this kind of beam are investigated using three-dimensional test particle simulations. Compared with the standard (i.e., TEM(00) mode) Gaussian beam, a flat-top laser beam has a stronger longitudinal electric field and a larger diffraction angle. These characteristics make it easier for electrons to be trapped and accelerated by the beam. With a flat-top shape, the laser beam is also applicable to the acceleration of low energy electron and bunch compression.

  1. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

    2010-01-01

    High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality...

  2. Energy Spread Reduction of Electron Beams Produced via Laser Wake

    Energy Technology Data Exchange (ETDEWEB)

    Pollock, Bradley Bolt [Univ. of California, San Diego, CA (United States)

    2012-01-01

    Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis describes a series of experiments which investigates the physics of LWFA in the self-guided blowout regime. Beginning with high density gas jet experiments the scaling of the LWFA-produced electron beam energy with plasma electron density is found to be in excellent agreement with both phenomenological theory and with 3-D PIC simulations. It is also determined that self-trapping of background electrons into the wake exhibits a threshold as a function of the electron density, and at the densities required to produce electron beams with energies exceeding 1 GeV a different mechanism is required to trap charge into low density wakes. By introducing small concentrations of high-Z gas to the nominal He background the ionization-induced injection mechanism is enabled. Electron trapping is observed at densities as low as 1.3 x 1018 cm-3 in a gas cell target, and 1.45 GeV electrons are demonstrated for the first time from LWFA. This is currently the highest electron energy ever produced from LWFA. The ionization-induced trapping mechanism is also shown to generate quasi-continuous electron beam energies, which is undesirable for accelerator applications. By limiting the region over which ionization-induced trapping occurs, the energy spread of the electron beams can be controlled. The development of a novel two-stage gas cell target provides the capability to tailor the gas composition in the longitudinal direction, and confine the trapping process to occur only in a

  3. Studies on transmitted beam modulation effect from laser induced damage on fused silica optics.

    Science.gov (United States)

    Zheng, Yi; Ma, Ping; Li, Haibo; Liu, Zhichao; Chen, Songlin

    2013-07-15

    UV laser induced damage (LID) on exit surface of fused silica could cause modulation effect to transmitted beam and further influence downstream propagation properties. This paper presents our experimental and analytical studies on this topic. In experiment, a series of measurement instruments are applied, including beam profiler, interferometer, microscope, and optical coherent tomography (OCT). Creating and characterizing of LID on fused silica sample have been implemented. Morphological features are studied based on their particular modulation effects on transmitted beam. In theoretical investigation, analytical modeling and numerical simulation are performed. Modulation effects from amplitude, phase, and size factors are analyzed respectively. Furthermore, we have novelly designed a simplified polygon model to simulate actual damage site with multiform modulation features, and the simulation results demonstrate that the modeling is usable and representative.

  4. n_TOF New target commissioning and beam characterization

    CERN Multimedia

    Igashira, M

    A full characterization of the neutron beam and experimental conditions for measurement with the new spallation target installed at the n_TOF facility is proposed. In a first step, the behavior the target assembly under the proton beam irradiation will be investigated, in order to complete the target commissioning. Subsequently the neutron beam parameters required to analyze the physics measurements, i.e. neutron fluence, beam profile, energy resolution function and beam related backgrounds as a function of the neutron energy, will be determined.

  5. Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Geer, S. B. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2014-12-28

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

  6. Characterization of the Los Alamos IPG YLR-6000 fiber laser using multiple optical paths and laser focusing optics

    Energy Technology Data Exchange (ETDEWEB)

    Milewski, John O [Los Alamos National Laboratory; Bernal, John E [Los Alamos National Laboratory

    2009-01-01

    Fiber laser technology has been identified as the replacement power source for the existing Los Alamos TA-55 production laser welding system. An IPG YLR-6000 fiber laser was purchased, installed at SM-66 R3, and accepted in February 2008. No characterization of the laser and no welding was performed in the Feb 2008 to May 2009 interval. T. Lienert and J. Bernal (Ref. 1, July 2009) determined the existing 200 mm Rofin collimator and focus heads used with the Rofin diode pumped lasers were inadequate for use with the IPG laser due to clipping of the IPG laser beam. Further efforts in testing of the IPG laser with Optoskand fiber delivery optics and a Rofin 120 mm collimator proved problematic due to optical fiber damage. As a result, IPG design optical fibers were purchased as replacements for subsequent testing. Within the same interval, an IPG fiber-to-fiber (F2F) connector, custom built for LANL, (J. Milewski, S. Gravener, Ref.2) was demonstrated and accepted at IPG Oxford, MA in August 2009. An IPG service person was contracted to come to LANL to assist in the installation, training, troubleshooting and characterization of the multiple beam paths and help perform laser head optics characterization. The statement of work is provided below: In summary the laser system, optical fibers, F2F connector, Precitec head, and a modified Rofin type (w/120mm Optoskand collimator) IWindowIBoot system focus head (Figure 1) were shown to perform well at powers up to 6 kW CW. Power measurements, laser spot size measurements, and other characterization data and lessons learned are contained within this report. In addition, a number of issues were identified that will require future resolution.

  7. Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped

    Science.gov (United States)

    Yan, Boxia; Qi, Yan; Wang, Yanwei

    2016-10-01

    Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

  8. Laser-Accelerated Proton Beams as Diagnostics for Cultural Heritage

    Science.gov (United States)

    Barberio, M.; Veltri, S.; Scisciò, M.; Antici, P.

    2017-01-01

    This paper introduces the first use of laser-generated proton beams as diagnostic for materials of interest in the domain of Cultural Heritage. Using laser-accelerated protons, as generated by interaction of a high-power short-pulse laser with a solid target, we can produce proton-induced X-ray emission spectroscopies (PIXE). By correctly tuning the proton flux on the sample, we are able to perform the PIXE in a single shot without provoking more damage to the sample than conventional methodologies. We verify this by experimentally irradiating materials of interest in the Cultural Heritage with laser-accelerated protons and measuring the PIXE emission. The morphological and chemical analysis of the sample before and after irradiation are compared in order to assess the damage provoked to the artifact. Montecarlo simulations confirm that the temperature in the sample stays safely below the melting point. Compared to conventional diagnostic methodologies, laser-driven PIXE has the advantage of being potentially quicker and more efficient. PMID:28266496

  9. Characterization of CNRS Fizeau wedge laser tuner

    Science.gov (United States)

    A fringe detection and measurement system was constructed for use with the CNRS Fizeau wedge laser tuner, consisting of three circuit boards. The first board is a standard Reticon RC-100 B motherboard which is used to provide the timing, video processing, and housekeeping functions required by the Reticon RL-512 G photodiode array used in the system. The sampled and held video signal from the motherboard is processed by a second, custom fabricated circuit board which contains a high speed fringe detection and locating circuit. This board includes a dc level discriminator type fringe detector, a counter circuit to determine fringe center, a pulsed laser triggering circuit, and a control circuit to operate the shutter for the He-Ne reference laser beam. The fringe center information is supplied to the third board, a commercial single board computer, which governs the data collection process and interprets the results.

  10. Vertical blow-up in a low-current, stored, laser-cooled ion beam

    CERN Document Server

    Madsen, N; Siegfried, L E; Hangst, J S; Nielsen, J

    2003-01-01

    Using a novel technique for real-time transverse beam profile diagnostics of a stored ion beam, we have observed the transverse size of a stored, laser-cooled ion beam. Earlier we observed that the density of the beam is independent of the beam current. At very low currents we observe an abrupt change in this behavior: the vertical beam size increases suddenly by about an order of magnitude. This observation implies a sudden change in the indirect vertical cooling mediated by intrabeam scattering. Our results have serious implications for the ultimate beam quality attainable by laser- cooling. (12 refs).

  11. Random wandering of laser beams with orbital angular momentum during propagation through atmospheric turbulence.

    Science.gov (United States)

    Aksenov, Valerii P; Kolosov, Valeriy V; Pogutsa, Cheslav E

    2014-06-10

    The propagation of laser beams having orbital angular momenta (OAM) in the turbulent atmosphere is studied numerically. The variance of random wandering of these beams is investigated with the use of the Monte Carlo technique. It is found that, among various types of vortex laser beams, such as the Laguerre-Gaussian (LG) beam, modified Bessel-Gaussian beam, and hypergeometric Gaussian beam, having identical initial effective radii and OAM, the LG beam occupying the largest effective volume in space is the most stable one.

  12. Interaction of high power laser beams with plasma in ICF hohlraum using the FDTD method

    Science.gov (United States)

    Lin, Zhili

    2016-11-01

    In the indirect-drive Inertial confinement fusion (ICF) system, groups of laser beams are injected into a gold cylindrical hohlraum and plasma is stimulated with the ablation of the wall of hohlraum by the laser beams. In our work, the finite-difference time-domain (FDTD) method associated with the bilinear transform and Maclaurin series expansion approaches is utilized to examine the laser beam propagation in plasma described by the Drude model. The state-of-the-art approaches for generating the laser beams are presented and realized according to the full utilization of the TF/SF source condition. Base on the previous technologies, the quantitatively numerical analysis of the propagation characteristics of laser beams in the plasma is conducted. The obtained results are illustrated and discussed that are helpful for the parameter optimization of laser beams for an ICF system.

  13. Automated analysis for detecting beams in laser wakefield simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela M.; Rubel, Oliver; Prabhat, Mr.; Weber, Gunther H.; Bethel, E. Wes; Aragon, Cecilia R.; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Hamann, Bernd; Messmer, Peter; Hagen, Hans

    2008-07-03

    Laser wakefield particle accelerators have shown the potential to generate electric fields thousands of times higher than those of conventional accelerators. The resulting extremely short particle acceleration distance could yield a potential new compact source of energetic electrons and radiation, with wide applications from medicine to physics. Physicists investigate laser-plasma internal dynamics by running particle-in-cell simulations; however, this generates a large dataset that requires time-consuming, manual inspection by experts in order to detect key features such as beam formation. This paper describes a framework to automate the data analysis and classification of simulation data. First, we propose a new method to identify locations with high density of particles in the space-time domain, based on maximum extremum point detection on the particle distribution. We analyze high density electron regions using a lifetime diagram by organizing and pruning the maximum extrema as nodes in a minimum spanning tree. Second, we partition the multivariate data using fuzzy clustering to detect time steps in a experiment that may contain a high quality electron beam. Finally, we combine results from fuzzy clustering and bunch lifetime analysis to estimate spatially confined beams. We demonstrate our algorithms successfully on four different simulation datasets.

  14. Detection of transient reflections during laser beam welding of copper

    Science.gov (United States)

    Ganser, Andreas; Liebl, Stefan; Schmitz, Patrick; Zaeh, Michael F.

    2016-03-01

    The advantages of laser beam welding, such as its high flexibility, its high local energy input, and its fast processing speed, led to a substantial increase of industrial applications using this technology. However, only a portion of the laser energy is absorbed during welding due to reflections. These reflections can damage the system components and lead to a reduced process efficiency. Especially when welding copper materials with infrared laser beam sources, the reflections play a significant role, since the reflection coefficient of copper is very high at infrared wavelengths. Therefore, a formation of a keyhole is necessary for a stable and efficient welding process. A theoretical model for the calculation of the reflections on an arbitrary position above the process zone, as well as a radiation analyzer based on a modular set-up are presented. This device enables a time- and space-resolved measurement of the reflected radiation. Using the experimental results, characteristic positions on the hemisphere could be identified to calibrate the theoretical model. The calibrated model allows to analyze the reflected radiation during the welding process to determine the energy which is absorbed by the work piece.

  15. Using Stable Distributions to Characterize Proton Pencil Beams

    CERN Document Server

    Heuvel, Frank Van den; Schreuder, Niek; George, Ben

    2016-01-01

    Purpose: To introduce and evaluate the use of stable distributions as a means of describing the behavior of charged particle pencil beams in a medium, with specific emphasis on proton beam scanning (PBS). Methods: The proton pencil beams of a clinically commissioned proton treatment facility are replicated in a Monte Carlo simulation system (FLUKA). For each available energy the beam deposition in water medium is characterized by the dose deposition. Using an alpha--stable distribution methodology each beam with a nominal energy $E$ is characterized by the lateral spread at depth $z$: $S(z;\\alpha,\\gamma,E)$ and a total energy deposition $I_D(z)$. The beams are then described as a function of the variation of the parameters at depth. Finally, an implementation in a freely available open source dose calculation suite (matRad, DKFZ, Heidelberg, Germany) is proposed. Results: Quantitatively, the fit of the stable distributions, compared to those implemented in standard treatment planning systems, are equivalent. ...

  16. A Radio System for Avoiding Illuminating Aircraft with a Laser Beam

    CERN Document Server

    Coles, W A; Melser, J F; Tu, J K; White, G A; Kassabian, K H; Bales, K; Baumgartner, B B

    2009-01-01

    When scientific experiments require transmission of powerful laser or radio beams through the atmosphere the Federal Aviation Administration (FAA) requires that precautions be taken to avoid inadvertent illumination of aircraft. Here we describe a highly reliable system for detecting aircraft entering the vicinity of a laser beam by making use of the Air Traffic Control (ATC) transponders required on most aircraft. This system uses two antennas, both aligned with the laser beam. One antenna has a broad beam and the other has a narrow beam. The ratio of the transponder power received in the narrow beam to that received in the broad beam gives a measure of the angular distance of the aircraft from the axis that is independent of the range or the transmitter power. This ratio is easily measured and can be used to shutter the laser when the aircraft is too close to the beam. Prototype systems operating on astronomical telescopes have produced good results.

  17. A Modeling and Data Analysis of Laser Beam Propagation in the Maritime Domain

    Science.gov (United States)

    2015-05-18

    A TRIDENT SCHOLAR PROJECT REPORT NO. 433 A Modeling and Data Analysis of Laser Beam Propagation in the Maritime Domain by...433 (2015) A MODELING AND DATA ANALYSIS OF LASER BEAM PROPAGATION IN THE MARITIME DOMAIN by Midshipman 1/C Benjamin C. Etringer United States Naval...2. REPORT TYPE 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE A Modeling and Data Analysis of Laser Beam Propagation in the Maritime

  18. 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.

  19. Numerical analysis of the effects of non-conventional laser beam geometries during laser melting of metallic materials

    Science.gov (United States)

    Safdar, Shakeel; Li, Lin; Sheikh, M. A.

    2007-01-01

    Laser melting is an important industrial activity encountered in a variety of laser manufacturing processes, e.g. selective laser melting, welding, brazing, soldering, glazing, surface alloying, cladding etc. The majority of these processes are carried out by using either circular or rectangular beams. At present, the melt pool characteristics such as melt pool geometry, thermal gradients and cooling rate are controlled by the variation of laser power, spot size or scanning speed. However, the variations in these parameters are often limited by other processing conditions. Although different laser beam modes and intensity distributions have been studied to improve the process, no other laser beam geometries have been investigated. The effect of laser beam geometry on the laser melting process has received very little attention. This paper presents an investigation of the effects of different beam geometries including circular, rectangular and diamond shapes on laser melting of metallic materials. The finite volume method has been used to simulate the transient effects of a moving beam for laser melting of mild steel (EN-43A) taking into account Marangoni and buoyancy convection. The temperature distribution, melt pool geometry, fluid flow velocities and heating/cooling rates have been calculated. Some of the results have been compared with the experimental data.

  20. Polarization of a probe laser beam due to nonlinear QED effects

    Science.gov (United States)

    Shakeri, Soroush; Kalantari, Seyed Zafarollah; Xue, She-Sheng

    2017-01-01

    Nonlinear QED interactions induce different polarization properties on a given probe beam. We consider the polarization effects caused by the photon-photon interaction in laser experiments, when a laser beam propagates through a constant magnetic field or collides with another laser beam. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian for both time-dependent and constant background field to explore the time evolution of the Stokes parameters Q, U, and V describing polarization. Assuming an initially linearly polarized probe laser beam, we also calculate the induced ellipticity and rotation of the polarization plane.

  1. Effect of Power Losses on Self-Focusing of High Intensity Laser Beam in Gases

    CERN Document Server

    Semak, V V

    2013-01-01

    A theoretical study of power loss from periphery of an ultrashort pulse laser beam and temporally resolved defocussing produced by laser induced plasma are performed using paraxial approximation. Our analysis incorporate consideration of spatial distribution of the laser beam irradiance and the results show that substantial power losses (10%-80%) occur from the beam periphery limiting length of a filament. It was also shown that generally accepted concept of self-focusing critical power is inconsistent with consideration of self-induced refraction of spatially distributed laser beam. A new criterion for self-focusing and hypothesis for multiple filamentation are proposed.

  2. Generation of Homogeneous and Patterned Electron Beams using a Microlens Array Laser-Shaping Technique

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, Aliaksei [NICADD, DeKalb; Edstrom, Dean [Fermilab; Gai, Wei [Argonne, HEP; Ha, Gwanghui [Argonne, HEP; Piot, Philippe [NICADD, DeKalb; Power, John [Argonne, HEP; Qiang, Gao [Unlisted, CN; Ruan, Jinhao [Fermilab; Santucci, James [Fermilab; Wisniewski, Eric [Argonne, HEP

    2016-06-01

    In photocathodes the achievable electron-beam parameters are controlled by the laser used to trigger the photoemission process. Non-ideal laser distribution hampers the final beam quality. Laser inhomogeneities, for instance, can be "amplified" by space-charge force and result in fragmented electron beams. To overcome this limitation laser shaping methods are routinely employed. In the present paper we demonstrate the use of simple microlens arrays to dramatically improve the transverse uniformity. We also show that this arrangement can be used to produce transversely-patterned electron beams. Our experiments are carried out at the Argonne Wakefield Accelerator facility.

  3. Laser micromachining of transparent glass using ultrafast Bessel beams

    Science.gov (United States)

    Zambon, Véronique; McCarthy, Nathalie; Piché, Michel

    2009-06-01

    We fabricated optical waveguides in fused silica by focusing femtosecond laser pulses with an axicon. With this technique, we also produced microholes by using chemical etching. The axicon, which is a conical lens, generates an optical beam with a transverse intensity profile that follows a zero-order Bessel function. Bessel beams produced by axicon focusing have a narrow focal line of a few micron width which is invariant along a long distance (>1 cm). By focusing femtosecond pulses with an axicon into fused silica, we induced permanent modifications over the extented focal line of the axicon without scanning axially the glass sample. The waveguides so fabricated exhibit low losses and no detectable birefringence due their excellent circular symmetry. By translating the glass sample during the inscription process, we have fabricated planar waveguides. Microfluidic channels were obtained by soaking the exposed samples into a HF solution.

  4. Laser radiation pressure slowing of a molecular beam

    CERN Document Server

    Barry, J F; Norrgard, E B; DeMille, D

    2011-01-01

    There is substantial interest in producing samples of ultracold molecules for possible applications in quantum computation, quantum simulation of condensed matter systems, precision measurements, controlled chemistry, and high precision spectroscopy. A crucial step to obtaining large samples of ultracold, trapped molecules is developing a means to bridge the gap between typical molecular source velocities (~150-600 m/s) and velocities for which trap loading or confinement is possible (~5-20 m/s). Here we show deceleration of a beam of neutral strontium monofluoride (SrF) molecules using radiative force. Under certain conditions, the deceleration results in a substantial flux of molecules with velocities <50 m/s. The observed slowing, from ~140 m/s, corresponds to scattering ~10000 photons. We also observe longitudinal velocity compression under different conditions. Combined with molecular laser cooling techniques, this lays the groundwork to create slow and cold molecular beams suitable for trap loading.

  5. Limitations of electron beam conditioning for free-electron lasers

    Directory of Open Access Journals (Sweden)

    P. Emma

    2003-03-01

    Full Text Available Several ideas have been proposed to “condition” an electron beam prior to the undulator of a free-electron laser (FEL by increasing each particle’s energy in proportion to the square of its transverse betatron amplitude. This conditioning enhances FEL gain by reducing the axial velocity spread within the electron bunch. We demonstrate that for symplectic beam lines, and independent of the method, this conditioning is always accompanied by a large head-tail focusing variation which, for short-wavelength FELs, is so severe as to make conditioning completely impractical. We furthermore find that any system added to correct the head-tail focusing variation will also remove the conditioning. As an example, a new method for conditioning is presented and shown to generate exactly the same head-tail focusing problems as in previously published work.

  6. Free electron lasers with slowly varying beam and undulator parameters

    Directory of Open Access Journals (Sweden)

    Z. Huang

    2005-04-01

    Full Text Available A self-consistent theory of a free electron laser (FEL with slowly varying beam and undulator parameters is developed using the WKB approximation. The theory is applied to study the performance of a self-amplified spontaneous emission (SASE FEL when the electron beam energy varies along the undulator as would be caused by vacuum pipe wakefields and/or when the undulator strength parameter is tapered in the small signal regime before FEL saturation. We find that a small energy gain or an equivalent undulator taper slightly reduces the power gain length in the exponential growth regime and can increase the saturated SASE power by about a factor of 2. Power degradation away from the optimal performance can be estimated based upon knowledge of the SASE bandwidth. The analytical results, which agree with numerical simulations, are used to optimize the undulator taper and to evaluate wakefield effects.

  7. Adaptive slit beam shaping for direct laser written waveguides.

    Science.gov (United States)

    Salter, P S; Jesacher, A; Spring, J B; Metcalf, B J; Thomas-Peter, N; Simmonds, R D; Langford, N K; Walmsley, I A; Booth, M J

    2012-02-15

    We demonstrate an improved method for fabricating optical waveguides in bulk materials by means of femtosecond laser writing. We use an LC spatial light modulator (SLM) to shape the beam focus by generating adaptive slit illumination in the pupil of the objective lens. A diffraction grating is applied in a strip across the SLM to simulate a slit, with the first diffracted order mapped onto the pupil plane of the objective lens while the zeroth order is blocked. This technique enables real-time control of the beam-shaping parameters during writing, facilitating the fabrication of more complicated structures than is possible using nonadaptive methods. Waveguides are demonstrated in fused silica with a coupling loss to single-mode fibers in the range of 0.2 to 0.5 dB and propagation loss <0.4 dB/cm.

  8. Optical guiding and beam bending in free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Scharlemann, E.T.

    1987-01-01

    The electron beam in a free-electron laser (FEL) can act as an optical fiber, guiding or bending the optical beam. The refractive and gain effects of the bunched electron beam can compensate for diffraction, making possible wigglers that are many Rayleigh ranges (i.e., characteristic diffraction lengths) long. The origin of optical guiding can be understood by examining gain and refractive guiding in a fiber with a complex index of refraction, providing a mathematical description applicable also to the FEL, with some extensions. In the exponential gain regime of the FEL, the electron equations of motion must be included, but a self-consistent description of exponential gain with diffraction fully included becomes possible. The origin of the effective index of refraction of an FEL is illustrated with a simple example of bunched, radiating dipoles. Some of the properties of the index of refraction are described. The limited experimental evidence for optical beam bending is summarized. The evidence does not yet provide conclusive proof of the existence of optical guiding, but supports the idea. Finally, the importance of refractive guiding for the performance of a high-gain tapered-wiggler FEL amplifier is illustrated with numerical simulations.

  9. Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam.

    Science.gov (United States)

    Kline, J L; Montgomery, D S; Flippo, K A; Johnson, R P; Rose, H A; Shimada, T; Williams, E A

    2008-10-01

    A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 degree angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (approximately 2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

  10. Laser plasma acceleration of electrons with multi-PW laser beams in the frame of CILEX

    Energy Technology Data Exchange (ETDEWEB)

    Cros, B., E-mail: brigitte.cros@u-psud.fr [LPGP, CNRS and Université Paris Sud, Orsay (France); Paradkar, B.S. [LPGP, CNRS and Université Paris Sud, Orsay (France); Davoine, X. [CEA DAM DIF, Arpajon F-91297 (France); Chancé, A. [CEA IRFU-SACM, Gif-Sur-Yvette (France); Desforges, F.G. [LPGP, CNRS and Université Paris Sud, Orsay (France); Dobosz-Dufrénoy, S. [CEA DSM-IRAMIS-SPAM, Gif-sur-Yvette (France); Delerue, N. [LAL, CNRS and Universit Paris Sud, Orsay (France); Ju, J.; Audet, T.L.; Maynard, G. [LPGP, CNRS and Université Paris Sud, Orsay (France); Lobet, M.; Gremillet, L. [CEA DAM DIF, Arpajon F-91297 (France); Mora, P. [CPhT, CNRS and Ecole Polytechnique, Palaiseau (France); Schwindling, J.; Delferrière, O. [CEA IRFU-SACM, Gif-Sur-Yvette (France); Bruni, C.; Rimbault, C.; Vinatier, T. [LAL, CNRS and Universit Paris Sud, Orsay (France); Di Piazza, A. [Max-Planck-Institut für Kernphysik, Heidelberg (Germany); Grech, M. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Palaiseau (France); and others

    2014-03-11

    Laser plasma acceleration of electrons has progressed along with advances in laser technology. It is thus expected that the development in the near-future of multi-PW-class laser and facilities will enable a vast range of scientific opportunities for laser plasma acceleration research. On one hand, high peak powers can be used to explore the extremely high intensity regime of laser wakefield acceleration, producing for example large amounts of electrons in the GeV range or generating high energy photons. On the other hand, the available laser energy can be used in the quasi-linear regime to create accelerating fields in large volumes of plasma and study controlled acceleration in a plasma stage of externally injected relativistic particles, either electrons or positrons. In the frame of the Centre Interdisciplinaire de la Lumière EXtrême (CILEX), the Apollon-10P laser will deliver two beams at the 1 PW and 10 PW levels, in ultra-short (>15fs) pulses, to a target area dedicated to electron acceleration studies, such as the exploration of the non-linear regimes predicted theoretically, or multi-stage laser plasma acceleration.

  11. Laser plasma acceleration of electrons with multi-PW laser beams in the frame of CILEX

    Science.gov (United States)

    Cros, B.; Paradkar, B. S.; Davoine, X.; Chancé, A.; Desforges, F. G.; Dobosz-Dufrénoy, S.; Delerue, N.; Ju, J.; Audet, T. L.; Maynard, G.; Lobet, M.; Gremillet, L.; Mora, P.; Schwindling, J.; Delferrière, O.; Bruni, C.; Rimbault, C.; Vinatier, T.; Di Piazza, A.; Grech, M.; Riconda, C.; Marquès, J. R.; Beck, A.; Specka, A.; Martin, Ph.; Monot, P.; Normand, D.; Mathieu, F.; Audebert, P.; Amiranoff, F.

    2014-03-01

    Laser plasma acceleration of electrons has progressed along with advances in laser technology. It is thus expected that the development in the near-future of multi-PW-class laser and facilities will enable a vast range of scientific opportunities for laser plasma acceleration research. On one hand, high peak powers can be used to explore the extremely high intensity regime of laser wakefield acceleration, producing for example large amounts of electrons in the GeV range or generating high energy photons. On the other hand, the available laser energy can be used in the quasi-linear regime to create accelerating fields in large volumes of plasma and study controlled acceleration in a plasma stage of externally injected relativistic particles, either electrons or positrons. In the frame of the Centre Interdisciplinaire de la Lumière EXtrême (CILEX), the Apollon-10P laser will deliver two beams at the 1 PW and 10 PW levels, in ultra-short (> 15 fs) pulses, to a target area dedicated to electron acceleration studies, such as the exploration of the non-linear regimes predicted theoretically, or multi-stage laser plasma acceleration.

  12. Enhanced creation of high energy particles in colliding laser beams

    CERN Document Server

    Kuchiev, Michael

    2015-01-01

    The creation of particles by two colliding strong laser beams is considered. It is found that the electron-positron pairs created in the laser field via the Schwinger mechanism may recollide after one or several oscillations in the field. Their collision can take place at high energy, which the pair gains from the field. As a result, high energy gamma quanta can be created by inelastic scattering or annihilation of the pair. Moreover, heavy particles such as muon pairs may also be created via the annihilation $e^+ + e^-\\rightarrow \\mu^+ + \\mu^- $. The probability of $e^-e^+$ collision is greatly enhanced due to a strong alignment of the electron and positron momenta with the electric field. The found muon creation rate exponentially exceeds the rate predicted by the direct Schwinger mechanism for muons, while the photon creation rate exponentially exceeds photon emission due to the fermion oscillation.

  13. Semi-classical beam cooling in an intense laser pulse

    CERN Document Server

    Yoffe, Samuel R; Noble, Adam; Jaroszynski, Dino A

    2014-01-01

    We present a novel technique for studying the evolution of a particle distribution using single particle dynamics such that the distribution can be accurately reconstructed using fewer particles than existing approaches. To demonstrate this, the Landau-Lifshiftz description of radiation reaction is adapted into a semi-classical model, for which the Vlasov equation is intractable. Collision between an energetic electron bunch and high-intensity laser pulses are then compared using the two theories. Reduction in beam cooling is observed for the semi-classical case.

  14. Surface plasmon interference excited by tightly focused laser beams.

    Energy Technology Data Exchange (ETDEWEB)

    Bouhelier, A.; Ignatovich, F.; Bruyant, A.; Huang, C.; Colas des Francs, G.; Weeber, J.-C.; Dereux, A.; Wiederrecht, G. P.; Novotny, L.; Center for Nanoscale Materials; Univ de Bourgogne; Univ. of Rochester; Univ Technologique de Troyes

    2007-09-01

    We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.

  15. Development of a Piezoelectric Adaptive Mirror for Laser Beam Control

    CSIR Research Space (South Africa)

    Long, CS

    2008-06-01

    Full Text Available stream_source_info Long1_2008.pdf.txt stream_content_type text/plain stream_size 15110 Content-Encoding UTF-8 stream_name Long1_2008.pdf.txt Content-Type text/plain; charset=UTF-8 ACTUATOR 2008, 11th International... Conference on New Actuators, Bremen, Germany, 9 – 11 June 2008584 P 17 Development of a Piezoelectric Adaptive Mirror for Laser Beam Control Craig S. Long1, Philip W. Loveday1 and Andrew Forbes1,2 1Council for Scientific and Industrial Research, PO...

  16. Laser beam self-focusing in turbulent dissipative media.

    Science.gov (United States)

    Hafizi, B; Peñano, J R; Palastro, J P; Fischer, R P; DiComo, G

    2017-01-15

    A high-power laser beam propagating through a dielectric in the presence of fluctuations is subject to diffraction, dissipation, and optical Kerr nonlinearity. A method of moments was applied to a stochastic, nonlinear enveloped wave equation to analyze the evolution of the long-term spot radius. For propagation in atmospheric turbulence described by a Kolmogorov-von Kármán spectral density, the analysis was benchmarked against field experiments in the low-power limit and compared with simulation results in the high-power regime. Dissipation reduced the effect of self-focusing and led to chromatic aberration.

  17. Characterization of a homemade ionization chamber for radiotherapy beams.

    Science.gov (United States)

    Neves, Lucio P; Perini, Ana P; dos Santos, Gelson P; Xavier, Marcos; Khoury, Helen J; Caldas, Linda V E

    2012-07-01

    A homemade cylindrical ionization chamber was studied for routine use in therapy beams of (60)Co and X-rays. Several characterization tests were performed: leakage current, saturation, ion collection efficiency, polarity effect, stability, stabilization time, chamber orientation and energy dependence. All results obtained were within international recommendations. Therefore the homemade ionization chamber presents usefulness for routine dosimetric procedures in radiotherapy beams.

  18. Numerical Simulations on the Formation of Speckles in Nanofluids Illuminated by a TEM00 Laser Beam

    Institute of Scientific and Technical Information of China (English)

    YAN Qin; QIAN Ming; NI Xiao-Wu; LU Jian; LI Qiang; XUAN Yi-Min

    2009-01-01

    @@ On the basis of a Rayleigh scattering model for a single nanoparticle illuminated by a TEM00 laser beam, we theoretically and numerically study the speckle formation when nanofluids are illuminated by a TEMoo laser beam. The results show that the laser speckles possess a Gaussian distribution, which are in agreement with the experimental results. The results may be useful for using a laser speckle velocimetry to determine the velocitiies of nanoparticles in nanofluids.

  19. Effects of Beam Size and Pulse Duration on the Laser Drilling Process

    CERN Document Server

    Afrin, Nazia; Chen, J K; Zhang, Yuwen

    2016-01-01

    A two-dimensional axisymmetric transient laser drilling model is used to analyze the effects of laser beam diameter and laser pulse duration on the laser drilling process. The model includes conduction and convection heat transfer, melting, solidification and vaporization, as well as material removal resulting from the vaporization and melt ejection. The validated model is applied to study the effects of laser beam size and pulse duration on the geometry of the drilled hole. It is found that the ablation effect decrease with the increasing beam diameter due to the effect of increased vaporization rate, and deeper hole is observed for the larger pulse width due to the higher thermal ablation efficiency.

  20. Beam emittance investigation in high brightness injector using different driver laser profiles

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Beam emittance plays an important role in any accelerator, and it is a main parameter to judge the performance of an accelerator. Emittance optimization is an indispensable part in conditioning and operation of the facility. For a laser-driven high brightness injector, different time structure of the laser pulse has different effects on transverse emittance. In order to compare Gaussian and flat-top laser pulse, systematic simulations of 500 pC have been done. From the simulation results, one can see that flat-top pulse laser will yield smaller minimal transverse beam size and transverse beam emittance than Gaussian pulse laser.

  1. Laser-driven electron beam generation for secondary photon sources with few terawatt laser pulses

    Science.gov (United States)

    Bohacek, K.; Chaulagain, U.; Horny, V.; Kozlova, M.; Krus, M.; Nejdl, J.

    2017-05-01

    Relativistic electron beams accelerated by laser wakefield have the ability to serve as sources of collimated, point-like and femtosecond X-ray radiation. Experimental conditions for generation of stable quasi-monoenergetic electron bunches using a femtosecond few-terawatt laser pulse (600 mJ, 50 fs) were investigated as they are crucial for generation of stable betatron radiation and X-ray pulses from inverse Compton scattering. A mixture of helium with argon, and helium with an admixture of synthetic air were tested for this purpose using different backing pressures and the obtained results are compared. The approach to use synthetic air was previously proven to stabilize the energy and energy spread of the generated electron beams at the given laser power. The accelerator was operated in nonlinear regime with forced self-injection and resulted in the generation of stable relativistic electron beams with an energy of tens of MeV and betatron X-ray radiation was generated in the keV range. A razor blade was tested to create a steep density gradient in order to improve the stability of electron injection and to increase the total electron bunch charge. It was proven that the stable electron and X-ray source can be built at small-scale facilities, which readily opens possibilities for various applications due to availability of such few-terawatt laser systems in many laboratories around the world.

  2. Effects of laser beam propagation and saturation on the spatial shape of sodium laser guide stars.

    Science.gov (United States)

    Marc, Fabien; Guillet de Chatellus, Hugues; Pique, Jean-Paul

    2009-03-30

    The possibility to produce diffraction-limited images by large telescopes through Adaptive Optics is closely linked to the precision of measurement of the position of the guide star on the wavefront sensor. In the case of laser guide stars, many parameters can lead to a strong distortion on the shape of the LGS spot. Here we study the influence of both the saturation of the sodium layer excited by different types of lasers, the spatial quality of the laser mode at the ground and the influence of the atmospheric turbulence on the upward propagation of the laser beam. Both shape and intensity of the LGS spot are found to depend strongly on these three effects with important consequences on the precision on the wavefront analysis.

  3. Characterization of a seeded pulsed molecular beam using the velocity map imaging technique

    Science.gov (United States)

    Lietard, Aude; Poisson, Lionel; Mestdagh, Jean-Michel; Gaveau, Marc-André

    2016-11-01

    An experimental study has been performed to characterize the density and the velocity distribution in a pulsed molecular beam generated by a source associating a pulsed valve and an oven placed just downstream. In its operating mode, the flow is alternatively in a supersonic and effusive regime. The Velocity Map Imaging (VMI) technique associated with laser ionization allows measuring the velocity distribution and the density of molecules as a function of time during the expansion. It gives us a very precise insight into the structure of the molecule bunch, and therefore into the nature of the expansion from which the molecular beam is extracted.

  4. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    Science.gov (United States)

    Teng, J.; Gu, Y. Q.; Zhu, B.; Hong, W.; Zhao, Z. Q.; Zhou, W. M.; Cao, L. F.

    2013-11-01

    This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

  5. Second harmonic generation of Cosh-Gaussian laser beam in collisional plasma with nonlinear absorption

    Science.gov (United States)

    Singh, Navpreet; Gupta, Naveen; Singh, Arvinder

    2016-12-01

    This paper investigates second harmonic generation (SHG) of an intense Cosh-Gaussian (ChG) laser beam propagating through a preformed underdense collisional plasma with nonlinear absorption. Nonuniform heating of plasma electrons takes place due to the nonuniform irradiance of intensity along the wavefront of laser beam. This nonuniform heating of plasma leads to the self-focusing of the laser beam and thus produces strong density gradients in the transverse direction. The density gradients so generated excite an electron plasma wave (EPW) at pump frequency that interacts with the pump beam to produce its second harmonics. To envision the propagation dynamics of the ChG laser beam, moment theory in Wentzel-Kramers-Brillouin (W.K.B) approximation has been invoked. The effects of nonlinear absorption on self-focusing of the laser beam as well as on the conversion efficiency of its second harmonics have been theoretically investigated.

  6. Development of Raman-shifted probe laser beam for plasma diagnosis using polaro-interferometer

    Indian Academy of Sciences (India)

    M P Kamath; A P Kulkarni; S Jain; P K Tripathi; A S Joshi; P A Naik; P D Gupta

    2010-11-01

    Optical diagnostics of laser-produced plasma requires a coherent, polarized probe beam synchronized with the pump beam. The probe beam should have energy above the background emission of plasma. Though the second harmonic probe beam satisfies most of the requirements, the plasma emission is larger at the harmonic frequencies of the pump. Hence, at high intensities we need a probe beam at non-harmonic frequencies. We have set up a Raman frequency shifted probe beam using a pressurized hydrogen cell that is pumped by the second harmonic of the Nd glass laser that operates at only one Stokes line of 673.75 nm.

  7. Laser Beam Failure Mode Effects and Analysis (FMEA) of the Solid State Heat Capacity Laser (SSHCL)

    Energy Technology Data Exchange (ETDEWEB)

    King, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-07

    A laser beam related FMEA of the SSHCL was performed to determine potential personnel and equipment safety issues. As part of the FMEA, a request was made to test a sample of the drywall material used for walls in the room for burn-through. This material was tested with a full power beam for five seconds. The surface paper material burned off and the inner calcium carbonate turned from white to brown. The result of the test is shown in the photo below.

  8. Design process for NIF laser alignment and beam diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Grey, A., LLNL

    1998-06-09

    In a controller for an adaptive optic system designed to correct phase aberrations in a high power laser, the wavefront sensor is a discrete Hartmann-Shack design. It uses an army of lenslets (like a fly` s eye) to focus the laser into 77 spots on a CCD camera. Average local tilt of the wavefront across each lenslet changes the position of its focal spot. The system requires 0.1 pixel accuracy in determining the focal spot location. We determine a small area around each spot` s previous location. Within this area, we calculate the centroid of the light intensity in x and y. This calculation fails if the spot regions overlap. Especially during initial acquisition of a highly distorted beam, distinguishing overlapping spots is difficult. However, low resolution analysis of the overlapping spots allows the system to estimate their positions. With this estimate, it can use the deformable mirror to correct the beam enough so we can detect the spots using conventional image processing.

  9. 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...

  10. Beam Dynamics Studies for a Laser Acceleration Experiment

    CERN Document Server

    Spencer, James; Noble, Robert; Palmer, Dennis T; Siemann, Robert

    2005-01-01

    The NLC Test Accelerator at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun, originally proposed for the NLCTA, is being installed together with a large-angle extraction line at 60 MeV. This is followed by a matching section, final focus and buncher for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range, high resolution spectrometer (HES) for electron bunch analysis. The RF gun is discussed in another paper. We discuss only the beam dynamics and high resolution analysis system at 6 MeV based on using Parmela and high-order Transport for bunch charges from 50 pC to 1 nC. Beyond the diagnostics, this system uses the emittance compensating solenoids and a low energy, high resolution spectrometer (LES) to help tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5° extraction line provide 1:1 phase space transfer without linear dispersion or use of sextu...

  11. Laser-driven electron beam and radiation sources for basic, medical and industrial sciences.

    Science.gov (United States)

    Nakajima, Kazuhisa

    2015-01-01

    To date active research on laser-driven plasma-based accelerators have achieved great progress on production of high-energy, high-quality electron and photon beams in a compact scale. Such laser plasma accelerators have been envisaged bringing a wide range of applications in basic, medical and industrial sciences. Here inheriting the groundbreaker's review article on "Laser Acceleration and its future" [Toshiki Tajima, (2010)],(1)) we would like to review recent progress of producing such electron beams due to relativistic laser-plasma interactions followed by laser wakefield acceleration and lead to the scaling formulas that are useful to design laser plasma accelerators with controllability of beam energy and charge. Lastly specific examples of such laser-driven electron/photon beam sources are illustrated.

  12. Numerical simulation to study the transient self focusing of laser beam in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R. P.; Hussain, Saba, E-mail: sabahussain44@yahoo.com; Gaur, Nidhi [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2015-02-15

    In this paper, we present the numerical simulation for the coupled system of equations governing the dynamics of laser and Ion Acoustic Wave (IAW) in a collisionless plasma, when the coupling between the waves is through ponderomotive non-linearity. The nonlinear evolution of the laser beam is studied when the pump laser is perturbed by a periodic perturbation. By changing the perturbation wave number, we have studied its effect on the nonlinear evolution pattern of laser beam. In order to have a physical insight into the nonlinear dynamics of laser beam evolution in time and space, we have studied the laser and IAW spectra containing spatial harmonics. The magnitude of these harmonics changes with time and leads to time dependent localization of laser beam in spatial domain. The nonlinear dynamics of this localization is investigated in detail by using simulation and a semi-analytical model.

  13. Thin laser beam wandering and intensity fluctuations method for evapotranspiration measurement

    Science.gov (United States)

    Poisson, Antonin; Fernandez, Angel; Perez, Dario G.; Barille, Regis; Dupont, Jean-Charles

    2016-06-01

    We compare in this study two simple optical setups to measure the atmospheric turbulence characterized by the refractive index structure parameter Cn2. The corresponding heat flux values sensed by the laser beam propagation are calculated leading to the plant evapotranspiration. The results are discussed and compared to measurements obtained with a well-known and calibrated eddy-covariant instrument. A fine analysis gives a good insight of the accuracy of the optical devices proposed here to measure the crop evapotranspiration. Additional evapotranspiration values calculated with meteorological sensor data and the use of different models are also compared in parallel.

  14. Integrated software package for laser diodes characterization

    Science.gov (United States)

    Sporea, Dan G.; Sporea, Radu A.

    2003-10-01

    The characteristics of laser diodes (wavelength of the emitted radiation, output optical power, embedded photodiode photocurrent, threshold current, serial resistance, external quantum efficiency) are strongly influenced by their driving circumstances (forward current, case temperature). In order to handle such a complex investigation in an efficient and objective manner, the operation of several instruments (a laser diode driver, a temperature controller, a wavelength meter, a power meter, and a laser beam analyzer) is synchronously controlled by a PC, through serial and GPIB communication. For each equipment, instruments drivers were designed using the industry standards graphical programming environment - LabVIEW from National Instruments. All the developed virtual instruments operate under the supervision of a managing virtual instrument, which sets the driving parameters for each unit under test. The manager virtual instrument scans as appropriate the driving current and case temperature values for the selected laser diode. The software enables data saving in Excel compatible files. In this way, sets of curves can be produced according to the testing cycle needs.

  15. Agile beam laser radar using computational imaging for robotic perception

    Science.gov (United States)

    Powers, Michael A.; Stann, Barry L.; Giza, Mark M.

    2015-05-01

    This paper introduces a new concept that applies computational imaging techniques to laser radar for robotic perception. We observe that nearly all contemporary laser radars for robotic (i.e., autonomous) applications use pixel basis scanning where there is a one-to-one correspondence between world coordinates and the measurements directly produced by the instrument. In such systems this is accomplished through beam scanning and/or the imaging properties of focal-plane optics. While these pixel-basis measurements yield point clouds suitable for straightforward human interpretation, the purpose of robotic perception is the extraction of meaningful features from a scene, making human interpretability and its attendant constraints mostly unnecessary. The imposing size, weight, power and cost of contemporary systems is problematic, and relief from factors that increase these metrics is important to the practicality of robotic systems. We present a system concept free from pixel basis sampling constraints that promotes efficient and adaptable sensing modes. The cornerstone of our approach is agile and arbitrary beam formation that, when combined with a generalized mathematical framework for imaging, is suited to the particular challenges and opportunities of robotic perception systems. Our hardware concept looks toward future systems with optical device technology closely resembling modern electronically-scanned-array radar that may be years away from practicality. We present the design concept and results from a prototype system constructed and tested in a laboratory environment using a combination of developed hardware and surrogate devices for beam formation. The technological status and prognosis for key components in the system is discussed.

  16. Electron beam charge diagnostics for laser plasma accelerators

    Directory of Open Access Journals (Sweden)

    K. Nakamura

    2011-06-01

    Full Text Available A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs. First, a scintillating screen (Lanex was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160  pC/mm^{2} and 0.4  pC/(ps  mm^{2}, respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within ±8%, showing that they all can provide accurate charge measurements for LPAs.

  17. Electron Beam Charge Diagnostics for Laser Plasma Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Smith, Alan; Rodgers, David; Donahue, Rich; Byrne, Warren; Leemans, Wim

    2011-06-27

    A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). First, a scintillating screen (Lanex) was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT) for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160 pC/mm{sup 2} and 0.4 pC/(ps mm{sup 2}), respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within {+-}8%, showing that they all can provide accurate charge measurements for LPAs.

  18. Multiphoton Ionization Detection in Collinear Laser Spectroscopy of Isolde Beams

    CERN Multimedia

    2002-01-01

    The experiments using the multiphoton ionization technique have been continued in the beginning of 1990 with stable beam tests on the modified apparatus and with another radioactive beam time on Yb. Higher laser power and an increased vacuum in the ionization region (see figure) yielded a further gain in sensitivity, mainly due to the better suppression of the background ions produced in rest gas collisions. For even Yb isotopes we have now reached a detection efficiency of $\\epsilon$~=~1~x~10$^{-5}$ ions per incoming atom at a background count rate of 30~ions from a beam of 5~x~10$^9$. This sensitivity was high enough for spectroscopy on $^{157}$Yb, where the typical ISOLDE yield of 5~x~10$^7$Yb ions is covered by an isobaric contamination of more than 10$^{10}$ ions. Measurements have also been performed on $^{175}$Yb. These give the first precise value for the magnetic moment of this isotope, $\\mu$~=~0.766(8)$ mu _{N} $, which agrees rather well with the magnetic moment of the isotone $^{177}$Hf. The isoto...

  19. Scintillator diagnostics for the detection of laser accelerated ion beams

    Science.gov (United States)

    Cook, N.; Tresca, O.; Lefferts, R.

    2014-09-01

    Laser plasma interaction with ultraintense pulses present exciting schemes for accelerating ions. One of the advantages conferred by using a gaseous laser and target is the potential for a fast (several Hz) repetition rate. This requires diagnostics which are not only suited for a single shot configuration, but also for repeated use. We consider several scintillators as candidates for an imaging diagnostic for protons accelerated to MeV energies by a CO2 laser focused on a gas jet target. We have measured the response of chromium-doped alumina (chromox) and polyvinyl toluene (PVT) screens to protons in the 2-8 MeV range. We have calibrated the luminescent yield in terms of photons emitted per incident proton for each scintillator. We also discuss how light scattering and material properties affect detector resolution. Furthermore, we consider material damage and the presence of an afterglow under intense exposures. Our analysis reveals a near order of magnitude greater yield from chromox in response to proton beams at > 8 MeV energies, while scattering effects favor PVT-based scintillators at lower energies.

  20. Joint performance of CO2 laser beam welding 5083-H321 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Qi Junfeng; Zhang Dongyun; Xiao Rongshi; Chen Kai; Zuo Tiechuan

    2007-01-01

    Laser beam welding of aluminum alloys is expected to offer good mechanical properties of welded joints. In this experimental work reported, CO2 laser beam autogenous welding and wire feed welding are conducted on 4mm thick 5083-H321 aluminum alloy sheets at different welding variables. The mechanical properties and microstructure characteristics of the welds are evaluated through tensile tests, micro-hardness tests, optical microscopy and scanning electron microscopy (SEM). Experimental results indicate that both the tensile strength and hardness of laser beam welds are affected by the constitution of filler material, except the yield strength. The soften region of laser beam welds is not in the heat-affected zone (HAZ). The tensile fracture of laser beam welded specimens takes place in the weld zone and close to the weld boundary because of different filler materials. Some pores are found on the fracture face, including hydrogen porosities and blow holes, but these pores have no influence on the tensile strength of laser beam welds. Tensile strength values of laser beam welds with filler wire are up to 345.57MPa, 93% of base material values, and yield strengths of laser beam welds are equivalent to those of base metal (264.50MPa).

  1. Numerical modelling of a thin deformable mirror for laser beam control

    CSIR Research Space (South Africa)

    Long, CS

    2010-01-01

    Full Text Available For intra-cavity laser beam control, a small, low-cost deformable mirror is required. This mirror can be used to correct for time- dependent phase aberrations to the laser beam, such as those caused by thermal expansion of materials. A piezoelectric...

  2. DEVICE FOR MEASURING OF THERMAL LENS PARAMETERS IN LASER ACTIVE ELEMENTS WITH A PROBE BEAM METHOD

    Directory of Open Access Journals (Sweden)

    A. N. Zakharova

    2015-01-01

    Full Text Available We have developed a device for measuring of parameters of thermal lens (TL in laser active elements under longitudinal diode pumping. The measurements are based on the probe beam method. This device allows one to determine sign and optical power of the lens in the principal meridional planes, its sensitivity factor with respect to the absorbed pump power and astigmatism degree, fractional heat loading which make it possible to estimate integral impact of the photoelastic effect to the formation of TL in the laser element. The measurements are performed in a linearly polarized light at the wavelength of 532 nm. Pumping of the laser element is performed at 960 nm that makes it possible to study laser materials doped with Yb3+ and (Er3+, Yb3+ ions. The precision of measurements: for sensitivity factor of TL – 0,1 m-1/W, for astigmatism degree – 0,2 m-1/W, for fractional heat loading – 5 %, for the impact of the photoelastic effect – 0,5 × 10-6 K-1. This device is used for characterization of thermal lens in the laser active element from an yttrium vanadate crystal, Er3+,Yb3+:YVO .

  3. Industrial fiber beam delivery system for ultrafast lasers: applications and recent advances

    Science.gov (United States)

    Eilzer, Sebastian; Funck, Max C.; Wedel, Björn

    2016-03-01

    Fiber based laser beam delivery is the method of choice for high power laser applications whenever great flexibility is required. For cw-lasers fiber beam delivery has long been established but has recently also become available for ultrafast lasers. Using micro-structured hollow core fibers that guide the laser beam mostly inside a hollow core, nonlinear effects and catastrophic damage that arise in conventional glass fibers can be avoided. Today, ultrafast pulses with several 100 μJ and hundreds of MW can be transmitted in quasi single mode fashion. In addition, the technology opens new possibilities for beam delivery systems as the pulse propagation inside the fiber can be altered on purpose. For example to shorten the pulse duration of picosecond lasers down into the femtosecond regime. We present a modular fiber beam delivery system for micromachining applications with industrial pico- and femtosecond lasers that is flexibly integrated into existing applications. Micro-structured hollow core fibers inside the sealed laser light cable efficiently guide high-power laser pulses over distances of several meters with excellent beam quality, while power, pulse duration and polarization are maintained. Robust and stable beam transport during dynamic operation as in robot or gantry systems will be discussed together with optional pulse compression.

  4. Influence of beam wander on uplink of ground-to-satellite laser communication and optimization for transmitter beam radius.

    Science.gov (United States)

    Guo, Hong; Luo, Bin; Ren, Yongxiong; Zhao, Sinan; Dang, Anhong

    2010-06-15

    We restudy the influence of beam wander on the uplink of ground-to-satellite laser communication, using the effective pointing error method, for a collimated untracked Gaussian beam under a weak atmospheric turbulence condition. It shows that the beam wander may cause significant increase in bit error rate (BER), and there exists an optimal transmitter radius for minimizing the value of BER. Further studies manifest that this optimal radius only changes with the laser wavelength and zenith angle, while independent on the satellite altitude and the fade threshold at the receiver. These results can be used in system design and optimization for the transmitter.

  5. Micro-beam and pulsed laser beam techniques for the micro-fabrication of diamond surface and bulk structures

    Energy Technology Data Exchange (ETDEWEB)

    Sciortino, S. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Bellini, M. [European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Istituto Nazionale di Ottica (INO-CNR), Largo Enrico Fermi 6, 50125 Firenze (Italy); Bosia, F. [Physics Department and “Nanostructured Interfaces and Surfaces” Inter-departmental Centre, University of Torino, via P. Giuria 1, 10125 Torino (Italy); INFN Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Calusi, S. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Corsi, C. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Czelusniak, C. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Gelli, N. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); and others

    2015-04-01

    Micro-fabrication in diamond is applicable in a wide set of emerging technologies, exploiting the exceptional characteristics of diamond for application in bio-physics, photonics and radiation detection. Micro ion-beam irradiation and pulsed laser irradiation are complementary techniques, which permit the implementation of complex geometries, by modification and functionalization of surface and/or bulk material, modifying the optical, electrical and mechanical characteristics of the material. In this article we summarize the work done in Florence (Italy), concerning ion beam and pulsed laser beam micro-fabrication in diamond.

  6. Optical Sideband Generation: a Longitudinal Electron Beam Diagnostic Beyond the Laser Bandwidth Resolution Limit

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory; Tilborg, J. van; Matlis, N. H.; Plateau, G. R.; Leemans, W. P.

    2010-06-01

    Electro-optic sampling (EOS) is widely used as a technique to measure THz-domain electric field pulses such asthe self-fields of femtosecond electron beams. We present an EOS-based approach for single-shot spectral measurement that excels in simplicity (compatible with fiber integration) and bandwidth coverage (overcomes the laser bandwidth limitation), allowing few-fs electron beams or single-cycle THz pulses to be characterized with conventional picosecond probes. It is shown that the EOS-induced optical sidebands on the narrow-bandwidth optical probe are spectrally-shifted replicas of the THz pulse. An experimental demonstration on a 0-3 THz source is presented.

  7. Numerical analysis of cutting glass by dual CO II-laser beams

    Science.gov (United States)

    Jiao, Junke; Wang, Xinbing; Zhang, Xueling; Tang, Wenlong; Liu, Fujun; Lu, Yanzhao

    2008-03-01

    Cutting brittle materials such as ceramics and glass by lasers or traditional saw method, costly fractures and associated damage such as chips and cracks can result. In most cases, these problems were caused as a result of the stress was not controlled properly and exceeded the critical value of the fracture. In this study, a dual-laser-beam method was proposed to avoid fractures in glass laser cutting, where an off-focused CO II-laser beam was scanning on the top surface of glass periodically and repeatedly and a preheated-band which has a proper temperature was built. This preheated-band will reduce the temperature gradients when the glass is cut by the focused CO II-laser beam. Under these conditions, glass can be cut with melting method without any fractures. The process of cutting glass by dual CO II-laser beams was simulated numerically with FEA method and the distribution of temperature and thermal stress was investigated. The relationships between the cutting parameters, such as laser beam diameter, laser power, cutting speed, and the profile of the cutting groove were also discussed. The result showed that thermal stress decreased with the increasing width of preheated-banding, and the smaller the diameter of laser beam, the better the quality of the cutting groove was in the same laser power situation.

  8. National Ignition Facility, subsystem design requirements beam control {ampersand} laser diagnostics SSDR 1.7

    Energy Technology Data Exchange (ETDEWEB)

    Bliss, E.

    1996-11-01

    This Subsystem Design Requirement document is a development specification that establishes the performance, design, development, and test requirements for the Alignment subsystem (WBS 1.7.1), Beam Diagnostics (WBS 1.7.2), and the Wavefront Control subsystem (WBS 1.7. 3) of the NIF Laser System (WBS 1.3). These three subsystems are collectively referred to as the Beam Control & Laser Diagnostics Subsystem. The NIF is a multi-pass, 192-beam, high-power, neodymium-glass laser that meets requirements set forth in the NIF SDR 002 (Laser System). 3 figs., 3 tabs.

  9. First Demonstration of Laser-Assisted Charge Exchange for Microsecond Duration H- Beams

    Science.gov (United States)

    Cousineau, Sarah; Rakhman, Abdurahim; Kay, Martin; Aleksandrov, Alexander; Danilov, Viatcheslav; Gorlov, Timofey; Liu, Yun; Plum, Michael; Shishlo, Andrei; Johnson, David

    2017-02-01

    This Letter reports on the first demonstration of laser-assisted H- charge exchange for microsecond duration H- beam pulses. Laser-assisted charge exchange injection is a breakthrough technology that overcomes long-standing limitations associated with the traditional method of producing high intensity, time structured beams of protons in accelerators via the use of carbon foils for charge exchange injection. The central theme of this experiment is the demonstration of novel techniques that reduce the laser power requirement to allow high efficiency stripping of microsecond duration beams with commercial laser technology.

  10. Generation of electron beams from a laser-based advanced accelerator at Shanghai Jiao Tong University

    CERN Document Server

    Elsied, Ahmed M M; Li, Song; Mirzaie, Mohammad; Sokollik, Thomas; Zhang, Jie

    2014-01-01

    At Shanghai Jiao Tong University, we have established a research laboratory for advanced acceleration research based on high-power lasers and plasma technologies. In a primary experiment based on the laser wakefield acceleration (LWFA) scheme, multi-hundred MeV electron beams having a reasonable quality are generated using 20-40 TW, 30 femtosecond laser pulses interacting independently with helium, neon, nitrogen and argon gas jet targets. The laser-plasma interaction conditions are optimized for stabilizing the electron beam generation from each type of gas. The electron beam pointing angle stability and divergence angle as well as the energy spectra from each gas jet are measured and compared.

  11. ILIAS - Ion and laser beam interaction and application studies. Progress report no. 2 of the PHELIX theory group

    Energy Technology Data Exchange (ETDEWEB)

    Mulser, P.; Schlegel, T. (eds.)

    2007-02-15

    The following topics are dealt with:QED, nuclear and high energy processes in extremely strong laser pulses, waves with constant phase velocity in relativistic plasmas, the effective critical electron density and its relativistic increase in an intense laser field, acceleration of electrons by laser pulses in vacuum, electron capture acceleration in a slit laser beam, laser acceleration of ion beams, collisionless high-power laser beam absorption, vacuum heating vs skin layer absorption of intense fs laser pulses, timescales of laser-induced phase transitions, quasi-static electron equilibria of laser-heted clusters, correlations in multi-electronic satellite spectra, radiation transport in the CAVEAT code. (HSI)

  12. Study on laser welding of austenitic stainless steel by varying incident angle of pulsed laser beam

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-09-01

    In the present work, AISI 304 stainless steel sheets are laser welded in butt joint configuration using a robotic control 600 W pulsed Nd:YAG laser system. The objective of the work is of twofold. Firstly, the study aims to find out the effect of incident angle on the weld pool geometry, microstructure and tensile property of the welded joints. Secondly, a set of experiments are conducted, according to response surface design, to investigate the effects of process parameters, namely, incident angle of laser beam, laser power and welding speed, on ultimate tensile strength by developing a second order polynomial equation. Study with three different incident angle of laser beam 89.7 deg, 85.5 deg and 83 deg has been presented in this work. It is observed that the weld pool geometry has been significantly altered with the deviation in incident angle. The weld pool shape at the top surface has been altered from semispherical or nearly spherical shape to tear drop shape with decrease in incident angle. Simultaneously, planer, fine columnar dendritic and coarse columnar dendritic structures have been observed at 89.7 deg, 85.5 deg and 83 deg incident angle respectively. Weld metals with 85.5 deg incident angle has higher fraction of carbide and δ-ferrite precipitation in the austenitic matrix compared to other weld conditions. Hence, weld metal of 85.5 deg incident angle achieved higher micro-hardness of ∼280 HV and tensile strength of 579.26 MPa followed by 89.7 deg and 83 deg incident angle welds. Furthermore, the predicted maximum value of ultimate tensile strength of 580.50 MPa has been achieved for 85.95 deg incident angle using the developed equation where other two optimum parameter settings have been obtained as laser power of 455.52 W and welding speed of 4.95 mm/s. This observation has been satisfactorily validated by three confirmatory tests.

  13. Measurement of Velocity Distribution in Atomic Beam by Diode Laser with Narrow Line width

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; WANG Fengzhi; YANG Donghai; WANG YiQiu

    2001-01-01

    In this paper, by using the detecting laser beam interacts with the atomic beam at a sharp angle and the Doppler frequency shift effect, the velocity distribution in cesium atomic beam is measured with a diode laser of narrow linewidth of 1 MHz. The effects of the atomic natural line width and cycling transition detecting factor on the measured results have been analyzed. Finally, the measured results have been compared with the theoretical calculation.

  14. Multiple species beam production on laser ion source for electron beam ion source in Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Sekine, M., E-mail: sekine.m.ae@m.titech.ac.jp [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Meguro, Tokyo (Japan); Riken, Wako, Saitama (Japan); Ikeda, S. [Riken, Wako, Saitama (Japan); Department of Energy Science, Tokyo Institute of Technology, Yokohama, Kanagawa (Japan); Hayashizaki, N. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Meguro, Tokyo (Japan); Kanesue, T.; Okamura, M. [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2014-02-15

    Extracted ion beams from the test laser ion source (LIS) were transported through a test beam transport line which is almost identical to the actual primary beam transport in the current electron beam ion source apparatus. The tested species were C, Al, Si, Cr, Fe, Cu, Ag, Ta, and Au. The all measured beam currents fulfilled the requirements. However, in the case of light mass ions, the recorded emittance shapes have larger aberrations and the RMS values are higher than 0.06 π mm mrad, which is the design goal. Since we have margin to enhance the beam current, if we then allow some beam losses at the injection point, the number of the single charged ions within the acceptance can be supplied. For heaver ions like Ag, Ta, and Au, the LIS showed very good performance.

  15. Beam shaping design for coupling high power diode laser stack to fiber.

    Science.gov (United States)

    Ghasemi, Seyed Hamed; Hantehzadeh, Mohammad-Reza; Sabbaghzadeh, Jamshid; Dorranian, Davoud; Lafooti, Majid; Vatani, Vahid; Rezaei-Nasirabad, Reza; Hemmati, Atefeh; Amidian, Ali Asghar; Alavian, Seyed Ali

    2011-06-20

    A beam shaping technique that rearranges the beam for improving the beam symmetry and power density of a ten-bar high power diode laser stack is simulated considering a stripe mirror plate and a V-Stack mirror in the beam shaping system. In this technique, the beam of a high power diode laser stack is effectively coupled into a standard 550 μm core diameter and a NA=0.22 fiber. By this technique, compactness, higher efficiency, and lower cost production of the diode are possible.

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

    Science.gov (United States)

    Ross, M. C.; 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.

    1997-01-01

    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 2.1×0.6 μm (x,y) at 4.0×1010 particles per pulse. Conventional profile monitors, such as scanning wires, fail at charge densities well below this. Since the beam-beam deflection does not provide single beam size information, another method is needed for interaction point (IP) beam size optimization. The laser-based profile monitor uses a finely focused, 350-nm, wavelength-tripled yttrium-lithium-flouride (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. This is adequate for present or planned SLC beams. Design and preliminary results will be presented.

  17. A new criterion to describe crossed-beam energy transfer in laser-plasma interactions

    Science.gov (United States)

    Trines, R.; Schmitz, H.; Alves, E. P.; Fiuza, F.; Vieira, J.; Silva, L. O.; Bingham, R.

    2016-10-01

    Crossed-beam energy transfer (CBET) between laser beams in underdense plasma is ubiquitous in both direct-drive and indirect-drive inertial confinement fusion. To understand the impact of this process on the final shape of the laser beams involved, as well as their imprint on either hohlraum walls or target surface, a detailed spatial and temporal description of the crossing beams is needed. We have developed an analytical model and derived new criteria describing both the spatial structure and temporal evolution of the beams after crossing. Numerical simulations have been carried out justifying the analytical model and confirming the criteria. The impact of our results on present and future multi-beam experiments in laser fusion and high-energy-density physics, in particular the ``bursty'' nature of beams predicted to occur in NIF experiments, will be discussed.

  18. Molecular characterization of microbial mutations induced by ion beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ichida, Hiroyuki [Graduate School of Science and Technology, Chiba University, Matsudo, Chiba 271-8510 (Japan); Accelerator Applications Research Group, Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan)], E-mail: ichida@riken.jp; Matsuyama, Tomoki [Cellular Biochemistry Laboratory, Discovery Research Institute, RIKEN, Wako, Saitama 351-0198 (Japan); Ryuto, Hiromichi [Accelerator Operation Group, Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Hayashi, Yoriko [Accelerator Applications Research Group, Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Fukunishi, Nobuhisa [Accelerator Operation Group, Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Abe, Tomoko [Accelerator Applications Research Group, Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Koba, Takato [Graduate School of Science and Technology, Chiba University, Matsudo, Chiba 271-8510 (Japan)

    2008-03-01

    A positive selection system for gene disruption using a sucrose-sensitive transgenic rhizobium was established and used for the molecular characterization of mutations induced by ion beam irradiations. Single nucleotide substitutions, insertions, and deletions were found to occur in the sucrose sensitivity gene, sacB, when the reporter line was irradiated with highly accelerated carbon and iron ion beams. In all of the insertion lines, fragments of essentially the same sequence and of approximately 1188 bp in size were identified in the sacB regions. In the deletion lines, iron ions showed a tendency to induce larger deletions than carbon ions, suggesting that higher LET beams cause larger deletions. We found also that ion beams, particularly 'heavier' ion beams, can produce single gene disruptions and may present an effective alternative to transgenic approaches.

  19. Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

    Science.gov (United States)

    Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

    2017-08-01

    At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on

  20. Using Si-doped diamond plate of sandwich type for spatial profiling of laser beam

    Science.gov (United States)

    Shershulin, V. A.; Samoylenko, S. R.; Sedov, V. S.; Kudryavtsev, O. S.; Ralchenko, V. G.; Nozhkina, A. V.; Vlasov, I. I.; Konov, V. I.

    2017-02-01

    We demonstrated a laser beam profiling method based on imaging of the laser induced photoluminescence of a transparent single-crystal diamond plate. The luminescence at 738 nm is caused by silicon-vacancy color centers formed in the epitaxial diamond film by its doping with Si during CVD growth of the film. The on-line beam monitor was tested for a cw laser emitting at 660 nm wavelength.

  1. Commissioning of a compact laser-based proton beam line for high intensity bunches around 10Â MeV

    Science.gov (United States)

    Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Kroll, F.; Blažević, A.; Bagnoud, V.; Roth, M.

    2014-03-01

    We report on the first results of experiments with a new laser-based proton beam line at the GSI accelerator facility in Darmstadt. It delivers high current bunches at proton energies around 9.6 MeV, containing more than 109 particles in less than 10 ns and with tunable energy spread down to 2.7% (ΔE/E0 at FWHM). A target normal sheath acceleration stage serves as a proton source and a pulsed solenoid provides for beam collimation and energy selection. Finally a synchronous radio frequency (rf) field is applied via a rf cavity for energy compression at a synchronous phase of -90 deg. The proton bunch is characterized at the end of the very compact beam line, only 3 m behind the laser matter interaction point, which defines the particle source.

  2. Commissioning of a compact laser-based proton beam line for high intensity bunches around 10 MeV

    Directory of Open Access Journals (Sweden)

    S. Busold

    2014-03-01

    Full Text Available We report on the first results of experiments with a new laser-based proton beam line at the GSI accelerator facility in Darmstadt. It delivers high current bunches at proton energies around 9.6 MeV, containing more than 10^{9} particles in less than 10 ns and with tunable energy spread down to 2.7% (ΔE/E_{0} at FWHM. A target normal sheath acceleration stage serves as a proton source and a pulsed solenoid provides for beam collimation and energy selection. Finally a synchronous radio frequency (rf field is applied via a rf cavity for energy compression at a synchronous phase of -90  deg. The proton bunch is characterized at the end of the very compact beam line, only 3 m behind the laser matter interaction point, which defines the particle source.

  3. High quality electron beam acceleration by ionization injection in laser wakefields with mid-infrared dual-color lasers

    CERN Document Server

    Zeng, Ming; Chen, Min; Mori, Warren B; Sheng, Zheng-Ming; Hidding, Bernhard

    2016-01-01

    For the laser wakefield acceleration, suppression of beam energy spread while keeping sufficient charge is one of the key challenges. In order to achieve this, we propose bichromatic laser ionization injection with combined laser wavelengths of $2.4\\rm \\mu m$ and $0.8\\rm \\mu m$ for wakefield excitation and for triggering electron injection via field ionization, respectively. A laser pulse at $2.4\\rm \\mu m$ wavelength enables one to drive an intense acceleration structure with relatively low laser power. To further reduce the requirement of laser power, we also propose to use carbon dioxide as the working gas medium, where carbon acts as the injection element. Our full three dimensional particle-in-cell simulations show that electron beams at the GeV energy level with both low energy spreads (around one percent) and high charges (several tens of picocoulomb) can be obtained by this scheme with laser parameters achievable in the near future.

  4. FILAMENTATION INSTABILITY OF LASER BEAMS IN NONLOCAL NONLINEAR MEDIA

    Institute of Scientific and Technical Information of China (English)

    文双春; 范滇元

    2001-01-01

    The filamentation instability of laser beams propagating in nonlocal nonlinear media is investigated. It is shown that the filamentation instability can occur in weakly nonlocal self-focusing media for any degree of nonlocality, and in defocusing media for the input light intensity exceeding a threshold related to the degree of nonlocality. A linear stability analysis is used to predict the initial growth rate of the instability. It is found that the nonlocality tends to suppress filamentation instability in self-focusing media and to stimulate filamentation instability in self-defocusing media. Numerical simulations confirm the results of the linear stability analysis and disclose a recurrence phenomenon in nonlocal self-focusing media analogous to the Fermi-Pasta-Ulam problem.

  5. Influence of laser mode on splitting beam illumination effect of Dammann grating

    Institute of Scientific and Technical Information of China (English)

    Liping Liu; Ye Tian; Xiudong Sun; Yuan Zhao; Yong Zhang; Chenfei Jin

    2009-01-01

    The influences of various laser modes on the splitting beam effect of Dammann grating are studied in theory and by numerical simulation.The results show that fundamental mode laser resembles plane wave while high order mode laser differs from plane wave in the splitting beam effect by Dammann grating.Therefore,the fundamental mode laser is more suitable to be the light source to improve the energy efficiency in far-distance image detecting systems,such as laser image ladar,which use Dammann grating in the illumination system.

  6. Digital holographic microscopy characterization of superdirective beam by metamaterial.

    Science.gov (United States)

    Di Caprio, Giuseppe; Dardano, Principia; Coppola, Giuseppe; Cabrini, Stefano; Mocella, Vito

    2012-04-01

    Digital holographic microscopy (DHM) has been successfully applied for the first time to characterize the radiative out-of-plane emission properties of a superdirective device. Complementarily to near-field microscopy, DHM allows us to reconstruct the beam in the far-field region. The angular dispersion of the light beam radiated from a grating composed of air and anti-air metamaterial has been determined, and the proposed technique has highlighted a collimation degree higher than 0.04°, as already evaluated in a previous work. Further considerations on the retrieved phase map of the beam in the acquisition plane are presented.

  7. Beam Characterization at the KAERI UED Beamline

    CERN Document Server

    Setiniyaz, Sadiq; Baek, In-Hyung; Nam, Jinhee; Chae, MoonSik; Han, Byung-Heon; Gudkov, Boris; Jang, Kyu Ha; Park, Sunjeong; Miginsky, Sergey; Vinokurov, Nikolay; Jeong, Young Uk

    2016-01-01

    The UED (ultrafast electron diffraction) beamline of the KAERI's (the Korea Atomic Energy Research Institute's) WCI (World Class Institute) Center has been successfully commissioned. We have measured the beam emittance by using the quadrupole scan technique and the charge by using a novel measurement system we have developed. In the quadrupole scan, a larger drift distance between the quadrupole and the screen is preferred because it gives a better thin-lens approximation. A high bunch-charge beam, however, will undergo emittance growth in the long drift caused by the space-charge force. We present a method that mitigates this growth by introducing a quadrupole scan with a short drift and without using the thin-lens approximation. The quadrupole in this method is treated as a thick lens, and the emittance is extracted by using the thick-lens equations. Apart from being precise, our method can be readily applied without making any change to the beamline and has no need for a big drift space. For charge measure...

  8. Comparison of electron beam and laser beam powder bed fusion additive manufacturing process for high temperature turbine component materials

    Energy Technology Data Exchange (ETDEWEB)

    Dryepondt, Sebastien N [ORNL; Kirka, Michael M [ORNL; Pint, Bruce A [ORNL; Ryan, Daniel [Solar Turbines, Inc.

    2016-04-01

    The evolving 3D printer technology is now at the point where some turbine components could be additive manufactured (AM) for both development and production purposes. However, this will require a significant evaluation program to qualify the process and components to meet current design and quality standards. The goal of the project was to begin characterization of the microstructure and mechanical properties of Nickel Alloy X (Ni-22Cr-18Fe-9Mo) test bars fabricated by powder bed fusion (PBF) AM processes that use either an electron beam (EB) or laser beam (LB) power source. The AM materials produced with the EB and LB processes displayed significant differences in microstructure and resultant mechanical properties. Accordingly, during the design analysis of AM turbine components, the specific mechanical behavior of the material produced with the selected AM process should be considered. Comparison of the mechanical properties of both the EB and LB materials to those of conventionally processed Nickel Alloy X materials indicates the subject AM materials are viable alternatives for manufacture of some turbine components.

  9. Annular beam shaping system for advanced 3D laser brazing

    Science.gov (United States)

    Pütsch, Oliver; Stollenwerk, Jochen; Kogel-Hollacher, Markus; Traub, Martin

    2012-10-01

    As laser brazing benefits from advantages such as smooth joints and small heat-affected zones, it has become established as a joining technology that is widely used in the automotive industry. With the processing of complex-shaped geometries, recent developed brazing heads suffer, however, from the need for continuous reorientation of the optical system and/or limited accessibility due to lateral wire feeding. This motivates the development of a laser brazing head with coaxial wire feeding and enhanced functionality. An optical system is designed that allows to generate an annular intensity distribution in the working zone. The utilization of complex optical components avoids obscuration of the optical path by the wire feeding. The new design overcomes the disadvantages of the state-of-the-art brazing heads with lateral wire feeding and benefits from the independence of direction while processing complex geometries. To increase the robustness of the brazing process, the beam path also includes a seam tracking system, leading to a more challenging design of the whole optical train. This paper mainly discusses the concept and the optical design of the coaxial brazing head, and also presents the results obtained with a prototype and selected application results.

  10. Spreading and wandering of Gaussian-Schell model laser beams in an anisotropic turbulent ocean

    Science.gov (United States)

    Wu, Yuqian; Zhang, Yixin; Zhu, Yun; Hu, Zhengda

    2016-09-01

    The effect of anisotropic turbulence on the spreading and wandering of Gaussian-Schell model (GSM) laser beams propagating in an ocean is studied. The long-term spreading of a GSM beam propagating through the paraxial channel of a turbulent ocean is also developed. Expressions of random wander for such laser beams are derived in an anisotropic turbulent ocean based on the extended Huygens-Fresnel principle. We investigate the influence of parameters in a turbulent ocean on the beam wander and spreading. Our results indicate that beam spreading and random beam wandering are smaller without considering the anisotropy of turbulence in the oceanic channel. Salinity fluctuation has a greater contribution to both the beam spreading and beam wander than that of temperature fluctuations in a turbulent ocean. Our results could be helpful for designing a free-space optical wireless communication system in an oceanic environment.

  11. Ultrafast laser parallel microdrilling using multiple annular beams generated by a spatial light modulator

    Science.gov (United States)

    Kuang, Zheng; Perrie, Walter; Edwardson, Stuart P.; Fearon, Eamonn; Dearden, Geoff

    2014-03-01

    Ultrafast laser parallel microdrilling using diffractive multiple annular beam patterns is demonstrated in this paper. The annular beam was generated by diffractive axicon computer generated holograms (CGHs) using a spatial light modulator. The diameter of the annular beam can be easily adjusted by varying the radius of the smallest ring in the axicon. Multiple annular beams with arbitrary arrangement and multiple annular beam arrays were generated by superimposing an axicon CGH onto a grating and lenses algorithm calculated multi-beam CGH and a binary Dammann grating CGH, respectively. Microholes were drilled through a 0.03 mm thick stainless steel foil using the multiple annular beams. By avoiding huge laser output attenuation and mechanical annular scanning, the processing is ˜200 times faster than the normal single beam processing.

  12. The effects of transverse plasma flow on laser beam deflection and of ultra-intense laser beam filamentation on channel formation

    Science.gov (United States)

    Hinkel, D. E.

    1997-11-01

    Recent experiments conducted at Lawrence Livermore National Laboratory (LLNL) with the Nova and Janus lasers demonstrate deflection of the laser beam in plasma with flow transverse to the beam. In gas-filled hohlraum experiments(S. G. Glendinning et al.), the laser spot on the hohlraum wall is ~ 100 μm closer to the laser entrance hole (LEH) than in empty hohlraum experiments, which degrades drive symmetry. In a series of exploding foil experiments(J. D. Moody et al.), Phys. Rev. Lett. 77, 1294 (1996)., intensity dependent deflection of the transmitted beam is observed, and interferometric measurements of laser-produced channels in preformed plasma(P. E. Young et al.), to be submitted to Phys. Rev. Lett., 1997. show beam deflection in the presence of near-sonic transverse flow. Theoretical analysis(D. E. Hinkel et al.), Phys. Rev. Lett. 77, 1298 (1996). yields simple scaling laws for the formation of ponderomotively (or thermally) created density depressions downstream from the laser beam's high intensity regions, into which the light is refracted. An integrated approach that utilizes plasma parameters from the hydrocode Lasnex, detailed knowledge of the beam structure, and plasma physics analysis and modelling with F3D(R. L. Berger et al.), Phys. Fluids B 5, 2243 (1993)., has been used to develop a predictive capability that successfully quantifies the amount of beam deflection occurring in experiments. Related physics of beam self-focussing and filamentation is of relevance to the Fast Ignitor(M. Tabak et al.), Phys. Plasmas 1, 1626 (1994).. In channeling experiments performed on the 100 TW laser at LLNL, the f/3 laser beam, which has a 15 μm waist at best focus, has intensities in excess of IL = 1 × 10^17 W/cm^2. Modelling of these high intensity experiments indicates that channel formation occurs over a wide range of cone angles for an idealized (Gaussian) beam. However, when beam structure is taken into consideration, channel formation in the underdense

  13. Morphology Characterization of Uranium Particles From Laser Ablated Uranium Materials

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the study, metallic uranium and uranium dioxide material were ablated by laser beam in order to simulate the process of forming the uranium particles in pyrochemical process. The morphology characteristic of uranium particles and the surface of

  14. Characterization of Detectors for Beam Loss Measurements

    CERN Document Server

    Panniello, M; Finocchiaro, P; Mallows, S; Welsch, C P

    2012-01-01

    Silicon Photomultipliers (SiPMs) are a good candidate for use as beam loss detectors in an accelerator due to their insensitivity to magnetic fields, compactness and relatively low voltage working regime. Furthermore, when used in large numbers, they are significantly cheaper to be mass-produced than more conventional detectors, such as Ionization Chambers. To be able to evaluate the application potential of SiPMs in an accelerator, it is necessary to quantify their fundamental parameters as light detectors, as well as in combination with an optical fiber used for signal generation. In this contribution an experimental and analytical study to determine the time resolution, light sensitivity and dynamic range of a Cherenkov light detector, based on SiPMs, is presented.

  15. A feasibility study of H{sup -} beam extraction technique using YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Meigo, Shin-ichiro; Hasegawa, Kazuo; Ikeda, Yujiro; Oigawa, Hiroyuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Aoki, Nobutada [Toshiba Power System Co., Ltd. (Japan); Nakagawa, Satoshi [Toshiba Co., Tokyo (Japan)

    2002-12-01

    Under a framework of JAERI-KEK joint project of high intensity proton accelerator, as for research and develop of the accelerator driven nuclear transmutation of the long lived radioactive nuclide, it is planed to built the Transmutation Physics Experiment Facility (TEF-P) and the Transmutation Engineering Experiment Facility (TEF-E). The TEF-P is used for the experiments for subcritical system coupled with a spallation neutron target bombarded with 600-MeV proton beam accelerated by the LINAC. To limit the maximum thermal power less than 500 W at the TEF-P, an incident beam power should be less than 10 W. On the contrary, at the TEF-E, high power beam of 200 kW is requested. Both high and low power beams are demanded for the transmutation facilities. It is difficult to deliver a low power beam to the TEF-P. Conventional beam extraction technique with a thin foil, is not desirable because the scattering of the beam at the foil requires the massive shield. Therefore, we study a new technique to extract a small portion of the beam precisely from the high intensity beam by using a laser beam. By a laser beam, H{sup -} in the beam from LINAC is partially changed to H{sup 0} beam so that a low current H{sup 0} beam can be obtained. As the cross section of the charge exchange reaction for H{sup -} ions has a peak around at a wave length of 1 {mu}m for photons, YAG laser is suitable for this charge exchange because of its 1.06 {mu}m wave length. It is derived that 10 W beam for 600-MeV proton can be extracted by the YAG laser with power of 2 J for each pulse of 25 Hz. By this technique, the pulse width for the extracted beam can be controlled by changing the time width of laser irradiation. When a charge exchanger having the beam collide point existing in straight section, a background beam current of projectile, however, will be increased due to the interaction with the residual gas in the beam duct. Thus, a charge exchanger is devised having the beam collide point in a

  16. Self-Focusing/Defocusing of Chirped Gaussian Laser Beam in Collisional Plasma with Linear Absorption

    Science.gov (United States)

    Wani, Manzoor Ahmad; Kant, Niti

    2016-09-01

    This paper presents an investigation on the self-focusing/defocusing of chirped Gaussian laser beam in collisional plasma with linear absorption. We have derived the differential equation for the beam width parameter by using WKB and paraxial approximations and solved it numerically. The effect of chirp and other laser plasma parameters is seen on the behavior of beam width parameter with dimensionless distance of propagation. The results are discussed and presented graphically. Our simulation results show that the amplitude of oscillations decreases with the distance of propagation. Due to collisional frequency, the laser beam shows fast divergence which can be minimized by the introduction of chirp parameter. The chirp decreases the effect of defocusing and increases the ability of self-focusing of laser beam in collisional plasma. Supported by a financial grant from CSIR, New Delhi, India, under Project No. 03(1277)/13/EMR-II

  17. The characteristics of arc beam shaping in hybrid plasma and laser deposition manufacturing

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Hai'ou; QIAN; Yingping; WANG; Guilan; ZHENG; Qiguang

    2006-01-01

    As a new direct metal prototyping technology,the hybrid plasma and laser deposition manufacturing (PLDM) is proposed in this paper. In order to figure out the characteristics of plasma arc beam and mould in the PLDM process of high temperature alloy, the high speed CCD camera is used to obtain the picture around the plasma arc. Afterwards the sketch of picture is clearly obtained. And the effect of laser parameter, such as average power, pulse width, pulse repetition frequency and the angle between laser beam and plasma arc beam on the plasma arc appearance, is studied experimentally. The results show that the modality of plasma arc beam is markedly influenced by laser beam. And the improvements of shape precision and surface state of the layer deposited by PLDM are confirmed.

  18. Note: Laser beam scanning using a ferroelectric liquid crystal spatial light modulator

    Energy Technology Data Exchange (ETDEWEB)

    Das, Abhijit [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Department of Physics, Gauhati University, Guwahati 781014, Assam (India); Boruah, Bosanta R., E-mail: brboruah@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India)

    2014-04-15

    In this work we describe laser beam scanning using a ferroelectric liquid crystal spatial light modulator. Commercially available ferroelectric liquid crystal spatial light modulators are capable of displaying 85 colored images in 1 s using a time dithering technique. Each colored image, in fact, comprises 24 single bit (black and white) images displayed sequentially. We have used each single bit image to write a binary phase hologram. For a collimated laser beam incident on the hologram, one of the diffracted beams can be made to travel along a user defined direction. We have constructed a beam scanner employing the above arrangement and demonstrated its use to scan a single laser beam in a laser scanning optical sectioning microscope setup.

  19. Development and characterization of advanced electron beam resists

    Science.gov (United States)

    Agrawal, Ankur

    Over the past twenty years, the amount of research and development work for electron beam resists has seriously lagged that performed for optical resists. This has been due mainly to the relatively low volume use of electron beam lithography for production purposes. However, as electron beam lithography is now becoming the primary solution for achieving future critical dimension requirements in mask making and appears to be a promising NGL technology, interest in electron beam resist development has increased in recent years. The primary issue in electron beam resist design centers around finding a single resist system that combines the required sensitivity and etch resistance that is needed to enable high volume production. In this work, the primary goal was to explore the development of a novel two-component non-chemically amplified electron beam resist material for high keV (>10 keV) patterning for mask-making with: (1) high contrast, (2) high sensitivity, (3) high resolution, and, (4) high etch resistance. Poly (2-methyl-1-pentene co 2-ethoxyethyl-methallyl ether sulfone) was used as a polymeric e-beam sensitive material conjunction with a series of commercial novolac resins to formulate electron beam resists. These two-component resists have been termed sulfone-novolac system (SNS) resists. The approach used in this project is to develop a suite of experimental tools and simulation models that can be used to aid in the rational design, formulation, and characterization of new electron beam resists. The main tasks that have been addressed are: (1) development of the electron beam resist characterization tool set, (2) understanding the fundamental material behavior of a non-chemically amplified polysulfone-novolac (SNS) e-beam resist for next generation mask making, (3) lithographic process development and optimization for the SNS resists, (4) evaluation of the lithographic performance of the SNS resists using the optimized processing conditions, and (5) develop

  20. Partially Coherent cosh-Gaussian Beams in Atmospheric Turbulence with the Same Directionality as a Laser

    Institute of Scientific and Technical Information of China (English)

    L(U) Su-Ye; JI Xiao-Ling; L(U) Bai-Da

    2007-01-01

    Directionality of a class of partially coherent cosh-Gaussian beams propagating in atmospheric turbulence is studied. It is shown that two partially coherent cosh-Gaussian beams may generate the same angular spread,and there exist equivalent partially coherent cosh-Gaussian beams which may have the same directionality as a fully coherent Gaussian laser beam in free space and also in atmospheric turbulence. The theoretical results are interpreted physically and illustrated numerically.

  1. Laser ablation of hard tissue: correlation between the laser beam parameters and the post-ablative tissue characteristics

    Science.gov (United States)

    Serafetinides, Alexandros A.; Makropoulou, Mersini I.; Khabbaz, Maruan

    2003-11-01

    Hard dental tissue laser applications, such as preventive treatment, laser diagnosis of caries, laser etching of enamel, laser decay removal and cavity preparation, and more recently use of the laser light to enlarge the root canal during the endodontic therapy, have been investigated for in vitro and in vivo applications. Post-ablative surface characteristics, e.g. degree of charring, cracks and other surface deformation, can be evaluated using scanning electron microscopy. The experimental data are discussed in relevance with the laser beam characteristics, e.g. pulse duration, beam profile, and the beam delivery systems employed. Techniques based on the laser illumination of the dental tissues and the subsequent evaluation of the scattered fluorescent light will be a valuable tool in early diagnosis of tooth diseases, as carious dentin or enamel. The laser induced autofluorescence signal of healthy dentin is much stronger than that of the carious dentin. However, a better understanding of the transmission patterns of laser light in teeth, for both diagnosis and therapy is needed, before the laser procedures can be used in a clinical environment.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

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

  3. Optical components for tailoring beam properties of multi-kW diode lasers

    Science.gov (United States)

    Könning, Tobias; Köhler, Bernd; Wolf, Paul; Bayer, Andreas; Hubrich, Ralf; Bodem, Christian; Plappert, Nora; Kindervater, Tobias; Faßbender, Wilhelm; Dürsch, Sascha; Küster, Matthias; Biesenbach, Jens

    2017-02-01

    One important aspect for the increasing use of diode lasers in industrial applications is the flexibility of diode lasers to tailor the beam properties to the specific needs demanded from the application. For fiber coupled solutions beam shaping with appropriate micro-optical elements is used for efficient fiber coupling of the highly asymmetric diode laser beam, whereas for direct applications optical elements are used to generate specific intensity distributions, like homogenized lines, areas and rings. Applications with diode lasers like solid state laser pump sources often require tailored spectral characteristics with narrow bandwidth, which is realized by using volume Bragg gratings for wavelength stabilization. In this paper we will summarize several concepts for adapting beam properties of diode lasers by using specific optical components. For building very compact laser modules of up to 2 kW we already presented a concept based on beam shaping of high fill factor bars. In this paper we will focus on further tailoring the beam properties of these very compact laser modules in the wavelength range from 808 nm up to 1020 nm. Fiber coupling of such modules into an 800 μm NA0.22 fiber yielded 1.6 kW without using polarization coupling. Another example is the generation of a 2.5 kW homogenized line with 40 mm length and a width of 4 mm.

  4. Ultrafast Diagnostics for Electron Beams from Laser Plasma Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Matlis, N. H.; Bakeman, M.; Geddes, C. G. R.; Gonsalves, T.; Lin, C.; Nakamura, K.; Osterhoff, J.; Plateau, G. R.; Schroeder, C. B.; Shiraishi, S.; Sokollik, T.; van Tilborg, J.; Toth, Cs.; Leemans, W. P.

    2010-06-01

    We present an overview of diagnostic techniques for measuring key parameters of electron bunches from Laser Plasma Accelerators (LPAs). The diagnostics presented here were chosen because they highlight the unique advantages (e.g., diverse forms of electromagnetic emission) and difficulties (e.g., shot-to-shot variability) associated with LPAs. Non destructiveness and high resolution (in space and time and energy) are key attributes that enable the formation of a comprehensive suite of simultaneous diagnostics which are necessary for the full characterization of the ultrashort, but highly-variable electron bunches from LPAs.

  5. An exact solution to paraxial propagation of laser beams in longitudinal inhomogeneous plasmas

    Institute of Scientific and Technical Information of China (English)

    Zhou Bing-Ju; Huang Zheng; Liu Ming-Wei; Liu Xiao-Juan

    2007-01-01

    An exact, general solution for laser beams propagating in longitudinally inhomogeneous plasmas is obtained in the form of the diffraction integral. The Gaussian beam and the Hermite-Gaussian beam are taken for example. In the case of an increasing plasma density along the propagation distance, natural diffraction of the Gaussian beam is retarded. This retardance has a less effect on the central part of the Hermite-Gaussian beam while a considerable rise of the power in bucket (PIB) occurs in the surrounding part of the beam.

  6. Observation of dynamic wavelength shifts of a four-beam laser diode and study of its adaptability to optical heads.

    Science.gov (United States)

    Shinoda, M; Kime, K

    1995-04-01

    Dynamic wavelength shifts for a four-beam laser diode were observed with a streak camera system. The wavelength shift does not exceed 2 nm for pulsed laser beam operation at a bottom power of 5 mW and a peak power of 40 mW. For a 5-mW continuous operation laser beam, the induced wavelength shift in the presence of another laser beam under the above pulse condition does not exceed 1 nm. The observed wavelength shifts are small enough for practical use, and this four-beam laser diode can be successfully applied to multibeam optical heads for parallel data processing.

  7. Flow speed of the ablation vapors generated during laser drilling of CFRP with a continuous-wave laser beam

    Science.gov (United States)

    Faas, S.; Freitag, C.; Boley, S.; Berger, P.; Weber, R.; Graf, T.

    2017-03-01

    The hot plume of ablation products generated during the laser drilling process of carbon fiber reinforced plastics (CFRP) with a continuous-wave laser beam was analyzed by means of high-speed imaging. The formation of compression shocks was observed within the flow of the evaporated material, which is an indication of flow speeds well above the local speed of sound. The flow speed of the hot ablation products can be estimated by analyzing the position of these compression shocks. We investigated the temporal evolution of the flow speed during the drilling process and the influence of the average laser power on the flow speed. The flow speed increases with increasing average laser powers. The moment of drilling through the material changes the conditions for the drilling process and was confirmed to influence the flow speed of the ablated material. Compression shocks can also be observed during laser cutting of CFRP with a moving laser beam.

  8. Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

    Science.gov (United States)

    Lawrence, J.

    2002-08-01

    Differences in the beam interaction characteristics of a CO2 laser, a Nd : YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilized zirconia bio-ceramic have been studied. A derivative of Beer-Lambert's law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55×10-3 cm for the CO2 laser, 18.22×10-3 cm for the Nd : YAG laser, 17.17×10-3 cm for the HPDL and 8.41×10-6 cm for the excimer laser. It was determined graphically that the fluence threshold values at which significant material removal was effected by the CO2 laser, the Nd : YAG laser, the HPDL and the excimer laser were 52 J cm-2, 97 J cm-2, 115 J cm-2 and 0.48 J cm-2, respectively. The thermal loading value for the CO2 laser, the Nd : YAG laser, the HPDL and the excimer laser were calculated as being 1.55 kJ cm-3, 5.32 kJ cm3, 6.69 kJ cm-3 and 57.04 kJ cm-3, respectively.

  9. Beam characterization for the field-emitter-array cathode-based low-emittance gun

    Directory of Open Access Journals (Sweden)

    S. C. Leemann

    2007-07-01

    Full Text Available A 1   Å x-ray free electron laser can be operated at 6 GeV provided a very high brightness electron beam. Therefore, Paul Scherrer Institute has initiated development of the low-emittance gun based on field emission. A field-emitter array (FEA is expected to deliver high peak current while reducing the source emittance to levels close to the thermal limit. A 100 keV gun test stand has been designed in order to gain experience with electron bunches emitted by pulsed FEAs, investigate emittance compensation, and develop diagnostic procedures to characterize the beam. First FEA samples have been installed and pulsed in the gun; the emitted bunches have been accelerated and characterized. We present results acquired with the first FEA samples.

  10. Surface characterization after subaperture reactive ion beam etching

    Energy Technology Data Exchange (ETDEWEB)

    Miessler, Andre; Arnold, Thomas; Rauschenbach, Bernd [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Leipzig (Germany)

    2010-07-01

    In usual ion beam etching processes using inert gas (Ar, Xe, Kr..) the material removal is determined by physical sputtering effects on the surface. The admixture of suitable gases (CF{sub 4}+O{sub 2}) into the glow discharge of the ion beam source leads to the generation of reactive particles, which are accelerated towards the substrate where they enhance the sputtering process by formation of volatile chemical reaction products. During the last two decades research in Reactive Ion Beam Etching (RIBE) has been done using a broad beam ion source which allows the treatment of smaller samples (diameter sample < diameter beam). Our goal was to apply a sub-aperture Kaufman-type ion source in combination with an applicative movement of the sample with respect to the source, which enables us to etch areas larger than the typical lateral dimensions of the ion beam. Concerning this matter, the etching behavior in the beam periphery plays a decisive role and has to be investigated. We use interferometry to characterize the final surface topography and XPS measurements to analyze the chemical composition of the samples after RIBE.

  11. Power Beaming, Orbital Debris Removal, and Other Space Applications of a Ground Based Free Electron Laser

    Science.gov (United States)

    2010-03-01

    successful interstellar propagation of a laser communications signal. A casual survey of the night’s sky indicates that light can travel across...laser illumination of objects within the solar system for scientific study, and interstellar laser illumination for communications. Power beaming...these ranges. FEL illumination at interstellar ranges is modeled and discussed to determine our ability to communicate or detect laser communications

  12. Correction of beam errors in high power laser diode bars and stacks.

    Science.gov (United States)

    Monjardin, J F; Nowak, K M; Baker, H J; Hall, D R

    2006-09-01

    The beam errors of an 11 bar laser diode stack fitted with fast-axis collimator lenses have been corrected by a single refractive plate, produced by laser cutting and polishing. The so-called smile effect is virtually eliminated and collimator aberration greatly reduced, improving the fast-axis beam quality of each bar by a factor of up to 5. The single corrector plate for the whole stack ensures that the radiation from all the laser emitters is parallel to a common axis. Beam-pointing errors of the bars have been reduced to below 0.7 mrad.

  13. Scaling laws for positron production in laser-electron-beam collisions

    Science.gov (United States)

    Blackburn, T. G.; Ilderton, A.; Murphy, C. D.; Marklund, M.

    2017-08-01

    Showers of γ rays and positrons are produced when a high-energy electron beam collides with a superintense laser pulse. We present scaling laws for the electron-beam energy loss, the γ -ray spectrum, and the positron yield and energy that are valid in the nonlinear, radiation-reaction-dominated regime. As an application we demonstrate that by employing the collision of a >GeV electron beam with a laser pulse of intensity >5 ×1021W cm-2 , today's high-intensity laser facilities are capable of producing O (104) positrons per shot via light-by-light scattering.

  14. Development of high damage threshold multilayer thin film beam combiner for laser application

    Science.gov (United States)

    Nand, Mangla; Babita, Jena, S.; Tokas, R. B.; Rajput, P.; Mukharjee, C.; Thakur, S.; Jha, S. N.; Sahoo, N. K.

    2016-05-01

    A polarized wavelength multiplexer with high laser induced damage threshold has been developed to combine two laser beam of high peak power in the visible region. The present wavelength multiplexer is a multilayer thin film device deposited by reactive electron beam evaporation. The developed device is capable of combining two p-polarized laser beams of peak power density of 1.7 GW/cm2 at an angle of incidence of 45°. High transmission (T> 90%) in high pass region and high reflection (R> 99%) in stop band region have been achieved.

  15. APPLICATION OF SPATIAL LIGHT MODULATORS FOR GENERATION OF LASER BEAMS WITH A SPIRAL PHASE DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    A. A. Zinchik

    2015-09-01

    Full Text Available Subject of Research. This paper discusses numerical simulation of spiral beams. Spiral beams have been experimentally obtained with the use of liquid crystal spatial light modulators (LCD SLM. The ability of dynamical change for the laser beam parameters has been studied. Method. Spiral beams are traditionally obtained by means of static masks defining the amplitude and phase distribution of the beam. The paper deals with modernized method with the use of two LCD SLMs. Modulators form separately the amplitude and phase distribution of the laser beam. Main Results. Numerical modeling of space spiral beams with different amplitude and phase characteristics has been carried out with the use of VirtualLab 5.0 software package manufactured by LightTrans GmbH. Simulation results are compared to the results of a natural experiment. Experimental results are in good agreement with computer simulation. It is shown that LCD SLMs application gives the possibility for dynamical change of the spiral beam parameters, their structure and the dependence of rotation angle on the distance. Distribution phase inversion leads to a change in the rotation direction of the laser beam and, therefore, to a change in the direction of its orbital angular momentum. Practical Relevance. The use of spatial modulators makes it possible to change dynamically the beam parameters, including rotation direction change. The results can be applied for solution of problems related to laser manipulating of microparticles, as well as the problems of determining the phase inhomogeneities of transparent objects.

  16. Propagation of high-power partially coherent fibre laser beams in a real environment

    Institute of Scientific and Technical Information of China (English)

    Tao Ru-Mao; Si Lei; Ma Yan-Xing; Zou Yong-Chao; Zhou Pu

    2011-01-01

    The propagation performance of high-power partially coherent fibre laser beams in a real environment is investigated and the theoretical model of a high-power fibre laser propagating in a real environment is established. The influence of a collimating system and thermal blooming is considered together with atmospheric turbulence and mechanical jitter. The laser energy concentration of partially coherent beams in the far field is calculated and analysed based on the theoretical model. It is shown that the propagation performance of partially coherent beams depends on the collimating system,atmospheric turbulence,mechanical jitter and thermal blooming. The propagation performance of partially coherent beams and fully coherent beams is studied and the results show that partially coherent beams are less sensitive to the influence of thermal blooming,which results in that the energy degeneration for partially coherent beams is only 50%a of that for fully coherent beams. Both partially coherent beams and fully coherent beams become less sensitive to thermal blooming when the average structural constant of the refraction index fluctuations increases to 1.7x10-14 m-2/3. The investigation presents a reference for applications of a high-power fibre laser system.

  17. Transport of electron beams and stability of optical windows in high-power e-beam-pumped krypton fluoride lasers

    Science.gov (United States)

    Zvorykin, V. D.; Arlantsev, S. V.; Bakaev, V. G.; Rantsev, O. V.; Sergeev, P. B.; Sychugov, G. V.; Tserkovnikov, A. Yu.

    2001-10-01

    Two of the key issues of a krypton fluoride (KrF) laser driver for inertial fusion energy are the development of long life, high transparency pressure foils (to isolate vacuum in the electron beam diode from a working gas in the laser chamber), and the development of durable, stable, optical windows. Both of these problems have been studied on the single-pulse e-beam-pumped KrF laser installation GARPUN. We have measured the transport of electron beams (300 keV, 50 kA, 100 ns, 10 × 100 cm) through aluminum-beryllium and titanium foils and compared them with Monte Carlo numerical calculations. It was shown that 50-[mu]m thickness Al-Be and 20-[mu]m Ti foils had equal transmittance. However, in contrast to Ti foil, whose surface was strongly etched by fluorine, no surface modification nor fatal damages were observed for Al-Be foils after [similar]1000 laser shots and protracted fluorine exposure. We also measured the 8% reduction in the transmission of CaF2 windows under irradiation by scattered electrons when they were set at 8.5 cm apart from the e-beam-pumped region. However an applied magnetic field of [similar]0.1 T significantly reduced electron scattering both across and along the laser cell at typical pumping conditions with 1.5 atm pressure working gas. Thus the e-beam-induced absorption of laser radiation in optical windows might be fully eliminated in an e-beam-pumping scheme with magnetic field guiding.

  18. High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation.

    Science.gov (United States)

    Navas, F J; Alcántara, R; Fernández-Lorenzo, C; Martín-Calleja, J

    2010-03-01

    A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

  19. Laser beam micro-milling of nickel alloy: dimensional variations and RSM optimization of laser parameters

    Science.gov (United States)

    Ahmed, Naveed; Alahmari, Abdulrahman M.; Darwish, Saied; Naveed, Madiha

    2016-12-01

    Micro-channels are considered as the integral part of several engineering devices such as micro-channel heat exchangers, micro-coolers, micro-pulsating heat pipes and micro-channels used in gas turbine blades for aerospace applications. In such applications, a fluid flow is required to pass through certain micro-passages such as micro-grooves and micro-channels. The fluid flow characteristics (flow rate, turbulence, pressure drop and fluid dynamics) are mainly established based on the size and accuracy of micro-passages. Variations (oversizing and undersizing) in micro-passage's geometry directly affect the fluid flow characteristics. In this study, the micro-channels of several sizes are fabricated in well-known aerospace nickel alloy (Inconel 718) through laser beam micro-milling. The variations in geometrical characteristics of different-sized micro-channels are studied under the influences of different parameters of Nd:YAG laser. In order to have a minimum variation in the machined geometries of each size of micro-channel, the multi-objective optimization of laser parameters has been carried out utilizing the response surface methodology approach. The objective was set to achieve the targeted top widths and depths of micro-channels with minimum degree of taperness associated with the micro-channel's sidewalls. The optimized sets of laser parameters proposed for each size of micro-channel can be used to fabricate the micro-channels in Inconel 718 with minimum amount of geometrical variations.

  20. Note: Lossless laser beam combiner employing a high-speed rotating half-wave plate

    Science.gov (United States)

    Yatsuka, E.; Yamamoto, T.; Hatae, T.; Torimoto, K.; Itami, K.

    2017-07-01

    We have developed a laser beam combiner employing a high-speed rotating half-wave plate based on the specific requirements of the Thomson scattering measurement systems in the ITER. The polarization extinction ratio of the output beam may exceed 1000 and was maintained for more than 1 h via feedback control of the half-wave plate rotation speed. The pointing fluctuations introduced by rotating the half-wave plate were in the order of microradians. The high-speed rotating half-wave plate provides a lossless means of combining laser beams together with stable beam pointing.

  1. Note: Lossless laser beam combiner employing a high-speed rotating half-wave plate.

    Science.gov (United States)

    Yatsuka, E; Yamamoto, T; Hatae, T; Torimoto, K; Itami, K

    2017-07-01

    We have developed a laser beam combiner employing a high-speed rotating half-wave plate based on the specific requirements of the Thomson scattering measurement systems in the ITER. The polarization extinction ratio of the output beam may exceed 1000 and was maintained for more than 1 h via feedback control of the half-wave plate rotation speed. The pointing fluctuations introduced by rotating the half-wave plate were in the order of microradians. The high-speed rotating half-wave plate provides a lossless means of combining laser beams together with stable beam pointing.

  2. Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Osterhoff, Jens; Sokollik, Thomas; Nakamura, Kei; Bakeman, Michael; Weingartner, R; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; vanTilborg, Jeroen; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Toth, Csaba; DeSantis, Stefano; Byrd, John; Gruner, F; Leemans, Wim

    2011-07-20

    The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.

  3. ZnSe-based laser structures for electron-beam pumping with graded index waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, S.V.; Sedova, I.V.; Ivanov, S.V. [Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Zdanova, E.V.; Zverev, M.M. [Moscow State Institute of Radio Engineering, Electronics and Automations, Moscow 117454 (Russian Federation); Gronin, S.V.

    2010-06-15

    Electron beam pumped (EBP) laser heterostructures with graded index waveguide (GIW) have been grown by molecular beam epitaxy and studied in detail. The maximum achieved output pulse power per facet is as high as 8.5 W at an electron beam energy of 16 kV. No saturation of output power with the increase of electron beam current as well as no suitable degradation of GIW EBP laser structures have been observed. The ways for further optimizations of GIW heterostructures are discussed. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Characterization of a homemade ionization chamber for radiotherapy beams

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Lucio P., E-mail: lpneves@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Perini, Ana P., E-mail: aperini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Santos, Gelson P. dos, E-mail: gpsantos@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Xavier, Marcos, E-mail: mxavier@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.br [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, 50740-540 Recife (Brazil); Caldas, Linda V.E., E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil)

    2012-07-15

    A homemade cylindrical ionization chamber was studied for routine use in therapy beams of {sup 60}Co and X-rays. Several characterization tests were performed: leakage current, saturation, ion collection efficiency, polarity effect, stability, stabilization time, chamber orientation and energy dependence. All results obtained were within international recommendations. Therefore the homemade ionization chamber presents usefulness for routine dosimetric procedures in radiotherapy beams. - Highlights: Black-Right-Pointing-Pointer A homemade ionization chamber was studied for routine use in radiotherapy. Black-Right-Pointing-Pointer Several characterization tests were performed and the results were satisfactory. Black-Right-Pointing-Pointer This chamber was compared to commercial ones and the results were similar. Black-Right-Pointing-Pointer This chamber is suitable for calibration procedures in {sup 60}Co beams.

  5. Highly efficient diode-stack, end-pumped Nd:YAG slab laser with symmetrized beam quality.

    Science.gov (United States)

    Liao, Y; Du, K; Falter, S; Zhang, J; Quade, M; Loosen, P; Poprawe, R

    1997-08-20

    An efficient high-power cw Nd:YAG slab laser, partially end pumped by diode-laser stacks, and a novel beam-shaping technique are reported. The optical efficiency amounted to 44 %, and the slope efficiency amounted to 55 %. Introducing an intracavity Brewster plate to polarize the laser beam, we obtained an optical efficiency of 35 % and a slope efficiency of 41 %. The output beam was rectangular and the beam quality asymmetric in two orthogonal directions. To equalize the beam quality, we introduced a step-mirror beam-shaping technique. The beam-shaping technique and the results obtained are discussed.

  6. RFQ beam cooler and buncher for collinear laser spectroscopy of rare isotopes

    Science.gov (United States)

    Barquest, B. R.; Bollen, G.; Mantica, P. F.; Minamisono, K.; Ringle, R.; Schwarz, S.; Sumithrarachchi, C. S.

    2017-09-01

    A radiofrequency quadrupole (RFQ) ion beam cooler and buncher has been developed to deliver bunched beams with low transverse emittance, energy spread, and time spread to the BECOLA collinear laser spectroscopy system at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The beam cooler and buncher contains new features which enhance performance, especially for high count rate beams, as well as simplifying construction, maintenance, and operation. The transverse emittance, energy spread, and time spread of the bunched beam, as well as buncher efficiency are reported, showcasing the capabilities of the BECOLA facility to perform collinear laser spectroscopy measurements with bunched rare isotope beams at NSCL and at the future Facility for Rare Isotope Beams (FRIB).

  7. Controlling laser beam irradiation area using an optical duplicate system to improve satellite-ground laser communications

    Science.gov (United States)

    Nakayama, Tomoko; Takayama, Yoshihisa; Fujikawa, Chiemi; Kodate, Kashiko

    2016-08-01

    To improve the quality of ground to satellite laser communications, we propose an optical duplicate system of the optical ground station. Our proposed approach can be used to control the beam irradiation area for a satellite position without changing the total power of the output beam and the mechanical drive unit; this is performed by controlling the input pattern of a liquid crystal filter inserted in the input plane of the optical duplicate system. Most of the power of the diffracted laser beam emitted from the ground is focused on the optical axis. By distributing the power to side lobes, it is possible to extend the coverage area for a satellite position. This system allows the laser beam irradiation area to be controlled by a sufficient degree by adjusting the threshold of the satellite reception level. We verify the efficacy of the system using wave optics numerical calculations.

  8. Diffractive-optics-based beam combination of a phase-locked fiber laser array.

    Science.gov (United States)

    Cheung, Eric C; Ho, James G; Goodno, Gregory D; Rice, Robert R; Rothenberg, Josh; Thielen, Peter; Weber, Mark; Wickham, Michael

    2008-02-15

    A diffractive optical element (DOE) is used as a beam combiner for an actively phase-locked array of fiber lasers. Use of a DOE eliminates the far-field sidelobes and the accompanying loss of beam quality typically observed in tiled coherent laser arrays. Using this technique, we demonstrated coherent combination of five fiber lasers with 91% efficiency and M2=1.04. Combination efficiency and phase locking is robust even with large amplitude and phase fluctuations on the input laser array elements. Calculations and power handling measurements suggest that this approach can scale to both high channel counts and high powers.

  9. All-optical time-resolved measurement of laser energy modulation in a relativistic electron beam

    Directory of Open Access Journals (Sweden)

    D. Xiang

    2011-11-01

    Full Text Available We propose and demonstrate an all-optical method to measure laser energy modulation in a relativistic electron beam. In this scheme the time-dependent energy modulation generated from the electron-laser interaction in an undulator is converted into time-dependent density modulation with a chicane, which is measured to infer the laser energy modulation. The method, in principle, is capable of simultaneously providing information on femtosecond time scale and 10^{-5} energy scale not accessible with conventional methods. We anticipate that this method may have wide applications in many laser-based advanced beam manipulation techniques.

  10. Butt weld of aluminum alloy plates 6063 and LY12 by laser beam

    Science.gov (United States)

    Xia, Jin'an; Cheng, Zhaogu; Xu, Guoliang; Li, Xianqin

    2000-02-01

    By means of a transverse flow 5 kW CO2 laser with low- order mode laser beam output, 1 - 4 mm thick aluminum alloy plates 6063 and LY12 were successfully butt welded. The result shows that the butt weldability and the weld quality of the aluminum alloy plates are mainly dependent on incident laser power density, laser beam defocused distance and shielding gas. The relationship between the weld quality of the aluminum alloy plates and the welding parameters is discussed. The macrostructure and microstructure of the welded seams are analyzed. The mechanical properties of the welded seams are discussed.

  11. Coherent combining of four slab laser amplifiers with high beam quality

    Science.gov (United States)

    Yan, Hong; Ye, Yidong; Tian, Fei; Li, Guohui; Pan, Xundong; Zhang, Wei; Gao, Qingsong; Zhou, Tangjian; Liao, Yuan; Chen, Li; Lu, Fei; Luo, Jia

    2014-10-01

    We report a coherent combining of four slab laser amplifiers with high beam quality. The long strip laser beam is reshaped into a square beam using adjustable beam expander which removes the enormous astigmatism aberration. A filling ratio of 90% is achieved by two-dimensional splicing. A compact optical system with high sampling frequency is designed to detect the pointing direction of lasers. Fast steering mirror (FSM) driven by piezoelectric ceramics is applied in laser stabilizing. Thanks to the closed loop pointing control, the root mean square error of the optical axis is significantly reduced to be less than 2 microradians. The piston phases of the lasers are locked by an active phase control system based on Field Programmable Gate Array (FPGA) using stochastic parallel gradient descent (SPGD) algorithm. When the total output power of four lasers is 400W, the in-phase peak intensity of the far field spot is increased by a factor of 3.8, reaching 95% of the ideal case. The beam quality of the combined beam is improved by CBC from 1.52x diffraction limit (DL) to 1.26x DL. When the output power is increased to 805W, the phase locking and pointing control still work stably. The results suggest that CBC of solid-state lasers with higher energy could be achieved by using the techniques presented here.

  12. Comparison of single-beam and dual-beam laser welding of Ti-22Al-25Nb/TA15 dissimilar titanium alloys

    Science.gov (United States)

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

    2017-08-01

    Laser beam welding (LBW) was used to join Ti-22Al-25Nb/TA15 dissimilar titanium alloys. The microstructure and mechanical properties of the welded joints under single and dual beam welding were analyzed and compared. In the mode of single laser beam, the fusion zone only consisted of B2 phase because of existence of β-phase stabilizer and rapid cooling rate of LBW. However, O phase was formed in the fusion zone while applying dual-beam laser welding due to decrease of the cooling rate. The microhardness distribution of the welded joint in dual-beam welding mode was consistent with that in single mode, but the hardness of the weld under dual laser beam was higher than that of single laser beam. In room-temperature tensile tests, the fractures all occurred in the weld, but the morphology exhibited a quasi-cleavage feature in single mode while the morphology was dimple fracture in the mode of dual laser beam. The tensile strength and elongation were both increased under dual-beam laser welding compared with those under single-beam laser welding.

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

    Science.gov (United States)

    Martinen, Dirk; Decker, Ingo; Wohlfahrt, Helmut

    1996-09-01

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

  14. Characterization and Performance of a High-Power Solid-State Laser for a High-Current Photocathode Injector

    CERN Document Server

    Zhang, S; Neil, G; Shinn, M D

    2005-01-01

    We report the characterization and performance of a diode-pumped, high-power, picosecond laser system designed for high-current photo-cathode accelerator injector at repetition rates of both 75MHz and 750MHz. Our characterization includes measurement of the system's amplitude stability, beam quality, pulsewidth, and phase noise for both frequencies.

  15. Laser beam shaping optical system design methods and their application in edge-emitting semiconductor laser-based LIDAR systems

    Science.gov (United States)

    Serkan, Mert

    LIDAR (Light Detection And Ranging) systems are employed for numerous applications such as remote sensing, military applications, optical data storage, display technology, and material processing. Furthermore, they are superior to other active remote sensing tools such as RADAR systems, considering their higher accuracy and more precise resolution due to their much shorter wavelengths and narrower beamwidth. Several types of lasers can be utilized as the radiation source of several LIDAR systems. Semiconductor laser-based LIDAR systems have several advantages such as low cost, compactness, broad range of wavelengths, and high PRFs (Pulse Repetition Frequency). However, semiconductor lasers have different origins and angles of divergence in the two transverse directions, resulting in the inherent astigmatism and elliptical beam shape. Specifically, elliptical beam shape is not desirable for several laser-based applications including LIDAR systems specifically designed to operate in the far-field region. In this dissertation, two mirror-based and two lens-based beam shapers are designed to circularize, collimate, and expand an edge-emitting semiconductor laser beam to a desired beam diameter for possible application in LIDAR systems. Additionally, most laser beams including semiconductor laser beams have Gaussian irradiance distribution. For applications that require uniform illumination of an extended target area, Gaussian irradiance distribution is undesirable. Therefore, a specific beam shaper is designed to transform the irradiance distribution from Gaussian to uniform in addition to circularizing, collimating, and expanding the semiconductor laser beam. For the design of beam shapers, aperture sizes of the surfaces are preset for desired power transmission and allowed diffraction level, surface parameters of the optical components and the distances between these surfaces are determined. Design equations specific to these beam shaping optical systems are

  16. ILIAS. Ion and laser beam interaction and application studies. Progress report no. 3 of the PHELIX theory group

    Energy Technology Data Exchange (ETDEWEB)

    Mulser, P. (ed.)

    2008-04-15

    The following topics are dealt with: The PHELIX laser-plasma facility, coupling of nuclear matter to intense photon fields, QED effects in strong laser fields, relativistic critical density increase in a linearly polarized laser beam, absorption of ultrashort laser pulses in strongly overdense targets, Coulomb focusing in electron-ion collisions in a strong laser field, quasiperiodic waves in relativistic plasmas, high-energy-density physics studied by intense particle beams, heavy ions in a high-power laser beam, Monte-Carlo study of electron dynamics in silicon during irradiation with an ultrashort VUV laser pulse. (HSI)

  17. Transmission of solar radiation through optical fiber and application to solar beam excited laser

    Energy Technology Data Exchange (ETDEWEB)

    Arashi, Haruo; Kaimai, Atsushi; Ishigame, Mareo

    1987-12-01

    This paper describes the transmission of high density solar radiation through optical fiber and application to a solar beam excited laser. Input solar beam, rendered a high density through a solar collector, is transmitted through optical fiber, and is separated into several fluxes. The fluxes of light are introduced into the side of a cylindrical laser mirror, where the optical fibres are made up into a rectangular form. The transmitted beam, passing through a side slit, excites a rod positioned at the centre of the laser. The separation of a solar collecting and an oscillating portion serves to increase the degree of freedom. The core of the optical fiber is composed of quartz, and a polymer cladding type having a large number of apertures. The input end of the fiber is a heat resistant air-cladding type. The fibre has a transmission of 93%, which is satisfactory for use. The optical excitation system is composed of, in combination, an elliptically cylindrical laser mirror and a cylindrical laser mirror, both of which have an internal surface gold-plated throughout. The output beam from the fiber is multiple-refracted to excite the laser efficiently. When laser beam with low intensity excited by a lamp is made to pass through a crystal of the above excitation system, the intensity is amplified. It is planned that direct laser oscillation is realized by increase of solar radiation intensity. (9 figs, 5 refs)

  18. Laser marking on soda-lime glass by laser-induced backside wet etching with two-beam interference

    Science.gov (United States)

    Nakazumi, Tomoka; Sato, Tadatake; Narazaki, Aiko; Niino, Hiroyuki

    2016-09-01

    For crack-free marking of glass materials, a beam-scanning laser-induced backside wet etching (LIBWE) process by a beam spot with a fine periodic structure was examined. The fine periodic structure was produced within a beam spot by means of a Mach-Zehnder interferometer incorporated to the optical setup for the beam-scanning LIBWE. A fine structure with a period of 9 µm was observed within the microstructures with a diameter of ca. 40 µm fabricated by a laser shot under double-beam irradiation, and they could be homogeneously fabricated within an area of 800  ×  800 µm. The area filled with the microstructures, including fine periodic structures, could be observed in high contrast under a diffuse, on-axis illumination that was used in commercial QR code readers.

  19. Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

    Science.gov (United States)

    Liu, Duncan; Wilson, Daniel; Qiu, Yueming; Forouhar, Siamak

    2007-01-01

    An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) nonplanar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. Figure 1 schematically illustrates the principle of operation of a laser-diode-pumped Nd:YAG NPRO. The laser beam path is confined in a Nd:YAG crystal by means of total internal reflections on the three back facets and a partial-reflection coating on the front facet. The wavelength of the pump beam - 808 nm - is the wavelength most strongly absorbed by the Nd:YAG crystal. The crystal can lase at a wavelength of either 1,064 nm or 1,319 nm - which one depending on the optical coating on the front facet. A thermal lens effect induced by the pump beam enables stable lasing in the lowest-order transverse electromagnetic mode (the TEM00 mode). The frequency of this laser is very stable because of the mechanical stability of the laser crystal and the unidirectional nature of the lasing. The unidirectionality is a result of the combined effects of (1) a Faraday rotation induced by an externally applied magnetic field and (2) polarization associated with non-normal incidence and reflection on the front facet.

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

    Science.gov (United States)

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

    2015-11-01

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

  1. Characterization of a nondestructive beam profile monitor using luminescent emission

    Directory of Open Access Journals (Sweden)

    A. Variola

    2007-12-01

    Full Text Available The LHC (large hadron collider [LHC study group: LHC. The large hadron collider conceptual design; CERN/AC/95-05] is the future p-p collider under construction at CERN, Geneva. Over a circumference of 26.7 km a set of cryogenic dipoles and rf cavities will store and accelerate proton and ion beams up to energies of the order of 7 TeV. Injection in LHC will be performed by the CERN complex of accelerators, starting from the source and passing through the linac, the four booster rings, the proton synchrotron (PS, and super proton synchrotron (SPS accelerators. One of the main constraints on LHC performance is emittance preservation along the whole chain of CERN accelerators. The accepted relative normalized emittance blowup after filamentation is ±7%. To monitor the beam and the emittance blowup process, a study of different prototypes of nonintercepting beam profile monitors has been performed. In this context a monitor using the luminescent emission of gases excited by ultrarelativistic protons (450 GeV was developed and tested in the SPS ring. The results of beam size measurements and their evolution as a function of the machine parameters are presented. The image quality and resolution attainable in the LHC case have been assessed. A first full characterization of the luminescence cross section, spectrum, decay time, and afterglow effect for an ultrarelativistic proton beam is provided. Some significant results are also provided for lead ion beams.

  2. Adaptable beam profiles from a dual-cavity Nd:YAG laser.

    Science.gov (United States)

    Kim, D J; Mackenzie, J I; Kim, J W

    2016-04-15

    We report a technique to tailor a laser beam profile from a donut to quasi-top-hat intensity distribution, directly from the laser, simply achieved by simultaneous excitation and control of the relative contributions of the fundamental (TEM00) and first-order Laguerre-Gaussian (LG01) transverse modes. Exploiting a dual-cavity configuration with a single Nd:YAG gain element, adaptable continuous-wave laser beam profiles from the primary cavity could be obtained by varying the diffraction loss of an acousto-optic modulator in the secondary cavity. We investigate the resultant beam profiles as a function of pump power and the AOM diffraction loss, and discuss the prospects for tunable laser beams profiles.

  3. Estimation of propagation losses for infrared laser beam in turbulent atmosphere

    Science.gov (United States)

    Zaponov, A. E.; Sakharov, M. V.

    2016-11-01

    In present work, the radiation propagation in atmosphere from laser source to the receiver is considered by taking into account deviations of optical beam due to turbulence. The photon flux density on the receiver has been evaluated.

  4. Additive Manufacturing of Ti-6Al-4V Using a Pulsed Laser Beam

    Science.gov (United States)

    Nassar, Abdalla R.; Reutzel, Edward W.

    2015-06-01

    Microstructural development in directed-energy additive manufacturing of metal components is a complex process that produces parts with materials whose microstructure and properties are influenced by multiple heating and cooling cycles. Much work has been undertaken to correlate microstructural development with processing conditions, such as laser power and processing speed. Here, the microstructure and indentation hardness of a Ti-6Al-4V component processed with a pulsing laser beam and a continuous wave (CW) laser beam are investigated. It is found that the pulsed-beam build showed no statistically significant variation in lath width or indentation hardness with build height while the build deposited with the CW beam showed a statistically significant decrease in hardness and an increase in lath width near the middle of the build. The reduction in variability with beam pulsing is attributed to rapid cooling rates within the melt pool, a greater degree of melt pool stirring, and reduced aging during part build-up.

  5. Coherent beam combination of fiber lasers with a strongly confined waveguide: numerical model.

    Science.gov (United States)

    Tao, Rumao; Si, Lei; Ma, Yanxing; Zhou, Pu; Liu, Zejin

    2012-08-20

    Self-imaging properties of fiber lasers in a strongly confined waveguide (SCW) and their application in coherent beam combination (CBC) are studied theoretically. Analytical formulas are derived for the positions, amplitudes, and phases of the N images at the end of an SCW, which is important for quantitative analysis of waveguide CBC. The formulas are verified with experimental results and numerical simulation of a finite difference beam propagation method (BPM). The error of our analytical formulas is less than 6%, which can be reduced to less than 1.5% with Goos-Hahnchen penetration depth considered. Based on the theoretical model and BPM, we studied the combination of two laser beams based on an SCW. The effects of the waveguide refractive index and Gaussian beam waist are studied. We also simulated the CBC of nine and 16 fiber lasers, and a single beam without side lobes was achieved.

  6. Generation of high-energy electron-positron beams in the collision of a laser-accelerated electron beam and a multi-petawatt laser

    CERN Document Server

    Lobet, Mathieu; d'Humières, Emmanuel; Gremillet, Laurent

    2015-01-01

    Generation of antimatter via the multiphoton Breit-Wheeler process in an all-optical scheme will be made possible on forthcoming high-power laser facilities through the collision of wakefield-accelerated GeV electrons with a counter-propagating laser pulse with $10^{22}$-$10^{23}$ $\\mathrm{Wcm}^{-2}$ peak intensity. By means of integrated 3D particle-in-cell simulations, we show that the production of positron beams with 0.1-1 nC total charge, 100-400 MeV mean energy and 0.01-0.1 rad divergence is within the reach of soon-to-be-available laser systems. The variations of the positron beam's properties with respect to the laser parameters are also examined.

  7. Nanoscale Characterization with Laser Picosecond Acoustics

    Science.gov (United States)

    Wright, Oliver B.

    2007-11-01

    Nanophotonics—the manipulation of light with nanomaterials—is a booming subject, its success owing to the host of nanoscale fabrication techniques now at our disposal. However, for the characterization of such nanomaterials it is expedient to turn to other types of waves with a wavelength commensurate with the nanostructure in question. One such choice is acoustic waves of nanometre wavelength. The aim of this article is to provide an introduction to laser picosecond acoustics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can therefore be used to characterize materials with nanometre spatial resolution. In this article we review the theoretical background for opaque single-layer thin film isotropic samples with reference to key experiments. Solids including metals and semiconductors are discussed, although liquids and, conceivably, gases, are not excluded.

  8. Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data

    Energy Technology Data Exchange (ETDEWEB)

    Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Wu, Kesheng; Prabhat,; Weber, Gunther H.; Ushizima, Daniela M.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2009-10-19

    Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps, then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.

  9. COUNTER PROPAGATION OF ELECTRON AND CO2 LASER BEAMS IN A PLASMA CHANNEL.

    Energy Technology Data Exchange (ETDEWEB)

    HIROSE,T.; POGORELSKY,I.V.; BEN ZVI,I.; YAKIMENKO,V.; KUSCHE,K.; SIDDONS,P.; KUMITA,T.; KAMIYA,Y.; ZIGLER,A.; GREENBERG,B.; ET AL

    2002-11-12

    A high-energy CO{sub 2} laser is channeled in a capillary discharge. Occurrence of guiding conditions at a relatively low plasma density (<10{sup 18} cm{sup -3}) is confirmed by MHD simulations. Divergence of relativistic electron beam changes depending on the plasma density. Counter-propagation of the electron and laser beams inside the plasma channel results in intense x-ray generation.

  10. Characterization of femtosecond laser-induced breakdown spectroscopy (fsLIBS) and applications for biological samples.

    Science.gov (United States)

    Gill, Ruby K; Knorr, Florian; Smith, Zachary J; Kahraman, Mehmet; Madsen, Dorte; Larsen, Delmar S; Wachsmann-Hogiu, Sebastian

    2014-01-01

    We characterize the femtosecond laser-induced breakdown spectroscopy (fsLIBS) signal for biological tissues as a function of different excitation parameters with femtosecond laser systems. These parameters include laser energy, depth of focus, and number of pulses per focal volume. We used femtosecond laser pulses of 800 nm and energy between 25 and 123 μJ to generate LIBS signals in biological tissues. As expected, we observed a linear increase in the fsLIBS intensity as a function of the laser energy. In addition, we show that moving the beam out of focus and the presence of overlapping pulses on the same focal area leads to a decrease in fsLIBS intensity due to changes in focal spot size. We also demonstrate that fsLIBS can distinguish between different biological tissue samples.

  11. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas, E-mail: thomas.lippert@psi.ch [General Energy Research Department, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland)

    2015-10-28

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially {sup 18}O substituted La{sub 0.6}Sr{sub 0.4}MnO{sub 3} target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  12. Optical Frequency Optimization of a High Intensity Laser Power Beaming System Utilizing VMJ Photovoltaic Cells

    Science.gov (United States)

    Raible, Daniel E.; Dinca, Dragos; Nayfeh, Taysir H.

    2012-01-01

    An effective form of wireless power transmission (WPT) has been developed to enable extended mission durations, increased coverage and added capabilities for both space and terrestrial applications that may benefit from optically delivered electrical energy. The high intensity laser power beaming (HILPB) system enables long range optical 'refueling" of electric platforms such as micro unmanned aerial vehicles (MUAV), airships, robotic exploration missions and spacecraft platforms. To further advance the HILPB technology, the focus of this investigation is to determine the optimal laser wavelength to be used with the HILPB receiver, which utilizes vertical multi-junction (VMJ) photovoltaic cells. Frequency optimization of the laser system is necessary in order to maximize the conversion efficiency at continuous high intensities, and thus increase the delivered power density of the HILPB system. Initial spectral characterizations of the device performed at the NASA Glenn Research Center (GRC) indicate the approximate range of peak optical-to-electrical conversion efficiencies, but these data sets represent transient conditions under lower levels of illumination. Extending these results to high levels of steady state illumination, with attention given to the compatibility of available commercial off-the-shelf semiconductor laser sources and atmospheric transmission constraints is the primary focus of this paper. Experimental hardware results utilizing high power continuous wave (CW) semiconductor lasers at four different operational frequencies near the indicated band gap of the photovoltaic VMJ cells are presented and discussed. In addition, the highest receiver power density achieved to date is demonstrated using a single photovoltaic VMJ cell, which provided an exceptionally high electrical output of 13.6 W/sq cm at an optical-to-electrical conversion efficiency of 24 percent. These results are very promising and scalable, as a potential 1.0 sq m HILPB receiver of

  13. Enhancement of laser to X-ray conversion by counter-propagating laser beams irradiating thin gold targets

    Science.gov (United States)

    Zhao, Y.; Ge, Z. Y.; Ma, Y. Y.; Yang, X. H.; Xu, B. B.; Ramis, R.

    2017-03-01

    X-ray emission from laser irradiating solid target is an important X-ray source for various potential applications. Counter-propagating (C-P) laser beams configuration is proposed to enhance the laser to X-ray conversion efficiency (CE) from laser irradiating solid targets. One-dimensional radiation hydrodynamics simulations show that the total X-ray CE for the C-P lasers case is as high as 65%, which has a 13% improvement compared with the single laser case. The improvement is mainly caused by the enlarged radiation region, and the enhancement of X-ray emission is from soft X-ray. Detailed energy term distributions and influences of the foil thickness on the X-ray CEs for both cases are presented. It is found that the enhancement of radiation is attributed to lower thermal and kinetic energy of the C-P lasers scheme.

  14. Dynamics of laser-driven proton beam focusing and transport into solid density matter

    Science.gov (United States)

    Kim, J.; McGuffey, C.; Beg, F.; Wei, M.; Mariscal, D.; Chen, S.; Fuchs, J.

    2016-10-01

    Isochoric heating and local energy deposition capabilities make intense proton beams appealing for studying high energy density physics and the Fast Ignition of inertial confinement fusion. To study proton beam focusing that results in high beam density, experiments have been conducted using different target geometries irradiated by a kilojoule, 10 ps pulse of the OMEGA EP laser. The beam focus was measured by imaging beam-induced Cu K-alpha emission on a Cu foil that was positioned at a fixed distance. Compared to a free target, structured targets having shapes of wedge and cone show a brighter and narrower K-alpha radiation emission spot on a Cu foil indicating higher beam focusability. Experimentally observed images with proton radiography demonstrate the existence of transverse fields on the structures. Full-scale simulations including the contribution of a long pulse duration of the laser confirm that such fields can be caused by hot electrons moving through the structures. The simulated fields are strong enough to reflect the diverging main proton beam and pinch a transverse probe beam. Detailed simulation results including the beam focusing and transport of the focused intense proton beam in Cu foil will be presented. This work was supported by the National Laser User Facility Program through Award DE-NA0002034.

  15. MEMS characterization using Laser Doppler Vibrometry

    Science.gov (United States)

    Lawrence, Eric M.; Speller, Kevin E.; Yu, Duli

    2003-01-01

    The use of Laser Doppler Vibrometry (LDV) technology has been at the forefront of Micro-Electro-Mechanical Systems (MEMS) research since the early 1990"s. By its nature as a sensitive laser optical technique, it is well suited for non-contact dynamic response measurements of microscopic structures. The art of the technology has culminated into the latest micro-scanning vibrometer for automated scan measurement and display of deflection shapes with sub-nanometer resolution. To exemplify the use of this technology, Polytec PI presents characterization measurements in collaboration with Applied MEMS on two of their devices used in commercial applications. LDV characterization measurements are used for validating the design of the Applied MEMS two-axis micro mirror. Scan measurements reveal distinct, isolated rotation modes about x- and y- axes that can be used to promote the mirror motion in either direction. Settling time performance is evaluated from impulse response and optimized using Input Shaping techniques. Scan measurements of a low-noise accelerometer device from Applied MEMS reveals spurious high frequency modes of support spring causing unwanted response effects. Further use of a new time domain animation feature shows ringing response of the accelerometer to step motions.

  16. Characterization of laser ablation of copper in the irradiance regime of laser-induced breakdown spectroscopy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Picard, J., E-mail: jessica.picard@cea.fr [Commissariat à l' Energie Atomique, DAM, Valduc, F-21120 Is-sur-Tille (France); Sirven, J.-B.; Lacour, J.-L. [Commissariat à l' Energie Atomique, DEN/DANS/DPC/SEARS/LANIE, Saclay, F-91191 Gif-sur-Yvette (France); Musset, O. [Université de Bourgogne, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 5209, F-21000 Dijon (France); Cardona, D.; Hubinois, J.-C. [Commissariat à l' Energie Atomique, DAM, Valduc, F-21120 Is-sur-Tille (France); Mauchien, P. [Commissariat à l' Energie Atomique, DEN/DANS/DPC/SEARS/LANIE, Saclay, F-91191 Gif-sur-Yvette (France)

    2014-11-01

    The LIBS signal depends both on the ablated mass and on the plasma excitation temperature. These fundamental parameters depend in a complex manner on laser ablation and on laser–plasma coupling. As several works in the literature suggest that laser ablation processes play a predominant role compared to plasma heating phenomena in the LIBS signal variations, this paper focuses on the study of laser ablation. The objective was to determine an interaction regime enabling to maximally control the laser ablation. Nanosecond laser ablation of copper at 266 nm was characterized by scanning electron microscopy and optical profilometry analysis, in air at 1 bar and in the vacuum. The laser beam spatial profile at the sample surface was characterized in order to give realistic values of the irradiance. The effect of the number of accumulated laser shots on the crater volume was studied. Then, the ablation crater morphology, volume, depth and diameter were measured as a function of irradiance between 0.35 and 96 GW/cm². Results show that in the vacuum, a regular trend is observed over the whole irradiance range. In air at 1 bar, below a certain irradiance, laser ablation is very similar to the vacuum case, and the ablation efficiency of copper was estimated at 0.15 ± 0.03 atom/photon. Beyond this irradiance, the laser beam propagation is strongly disrupted by the expansion of the dense plasma, and plasma shielding appears. The fraction of laser energy used for laser ablation and for plasma heating is estimated in the different irradiance regimes. - Highlights: • The morphology of copper's craters was studied as a function of the pulse energy. • Correlation at low energy and two pressures between crater volume and pulse energy • The ablation efficiency of copper at 1 bar is equal to 0.15 atom/photon. • Ablation efficiency in the vacuum is not limited by laser–plasma interaction. • Physical mechanisms of laser ablation at both pressures are discussed.

  17. Propagation instabilities of high-intensity laser-produced electron beams.

    Science.gov (United States)

    Tatarakis, M; Beg, F N; Clark, E L; Dangor, A E; Edwards, R D; Evans, R G; Goldsack, T J; Ledingham, K W D; Norreys, P A; Sinclair, M A; Wei, M-S; Zepf, M; Krushelnick, K

    2003-05-01

    Measurements of energetic electron beams generated from ultrahigh intensity laser interactions (I>10(19) W/cm(2)) with dense plasmas are discussed. These interactions have been shown to produce very directional beams, although with a broad energy spectrum. In the regime where the beam density approaches the density of the background plasma, we show that these beams are unstable to filamentation and "hosing" instabilities. Particle-in-cell simulations also indicate the development of such instabilities. This is a regime of particular interest for inertial confinement fusion applications of these beams (i.e., "fast ignition").

  18. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question.

    Science.gov (United States)

    Yang, X; Brunetti, E; Gil, D Reboredo; Welsh, G H; Li, F Y; Cipiccia, S; Ersfeld, B; Grant, D W; Grant, P A; Islam, M R; Tooley, M P; Vieux, G; Wiggins, S M; Sheng, Z M; Jaroszynski, D A

    2017-03-10

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  19. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    Science.gov (United States)

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-01-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators. PMID:28281679

  20. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    CERN Document Server

    Yang, X; Reboredo Gil, David; Welsh, Gregor H; Li, Y.F; Cipiccia, Silvia; Ersfeld, Bernhard; Grant, D. W; Grant, P. A; Islam, Muhammad; Tooley, M.B; Vieux, Gregory; Wiggins, Sally; Sheng, Zheng-Ming; Jaroszynski, Dino

    2017-01-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lowerenergy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wake...