Sample records for aim laser beams

  1. Phased laser array for generating a powerful laser beam

    DOEpatents

    Holzrichter, John F.; Ruggiero, Anthony J.

    2004-02-17

    A first injection laser signal and a first part of a reference laser beam are injected into a first laser element. At least one additional injection laser signal and at least one additional part of a reference laser beam are injected into at least one additional laser element. The first part of a reference laser beam and the at least one additional part of a reference laser beam are amplified and phase conjugated producing a first amplified output laser beam emanating from the first laser element and an additional amplified output laser beam emanating from the at least one additional laser element. The first amplified output laser beam and the additional amplified output laser beam are combined into a powerful laser beam.

  2. Laser beam monitoring system

    DOEpatents

    Weil, Bradley S.; Wetherington, Jr., Grady R.

    1985-01-01

    Laser beam monitoring systems include laser-transparent plates set at an angle to the laser beam passing therethrough and light sensor for detecting light reflected from an object on which the laser beam impinges.

  3. Laser beam monitoring system

    DOEpatents

    Weil, B.S.; Wetherington, G.R. Jr.

    Laser beam monitoring systems include laser-transparent plates set at an angle to the laser beam passing therethrough and light sensor for detecting light reflected from an object on which the laser beam impinges.

  4. Double wedge prism based beam deflector for precise laser beam steering

    NASA Astrophysics Data System (ADS)

    Tyszka, Krzysztof; Dobosz, Marek; Bilaszewski, Tomasz

    2018-02-01

    Aiming to increase laser beam pointing stability required in interferometric measurements, we designed a laser beam deflector intended for active laser beam stabilization systems. The design is based on two wedge-prisms: the deflecting wedge driven by a tilting piezo-platform and the fixed wedge to compensate initial beam deflection. Our design allows linear beam steering, independently in the horizontal or vertical direction, with resolution of less than 1 μrad in a range of more than 100 μrad, and no initial deflection of the beam. Moreover, the ratio of the output beam deflection angle and the wedge tilt angle is less than 0.1; therefore, the noise influence is significantly reduced in comparison to standard mirror-based deflectors. The theoretical analyses support the designing process and can serve as a guide to wedge-prism selection. The experimental results are in agreement with theory and confirm the advantages of the presented double wedge system.

  5. Method and apparatus for timing of laser beams in a multiple laser beam fusion system

    DOEpatents

    Eastman, Jay M.; Miller, Theodore L.

    1981-01-01

    The optical path lengths of a plurality of comparison laser beams directed to impinge upon a common target from different directions are compared to that of a master laser beam by using an optical heterodyne interferometric detection technique. The technique consists of frequency shifting the master laser beam and combining the master beam with a first one of the comparison laser beams to produce a time-varying heterodyne interference pattern which is detected by a photo-detector to produce an AC electrical signal indicative of the difference in the optical path lengths of the two beams which were combined. The optical path length of this first comparison laser beam is adjusted to compensate for the detected difference in the optical path lengths of the two beams. The optical path lengths of all of the comparison laser beams are made equal to the optical path length of the master laser beam by repeating the optical path length adjustment process for each of the comparison laser beams. In this manner, the comparison laser beams are synchronized or timed to arrive at the target within .+-.1.times.10.sup.-12 second of each other.

  6. Precision laser aiming system

    DOEpatents

    Ahrens, Brandon R [Albuquerque, NM; Todd, Steven N [Rio Rancho, NM

    2009-04-28

    A precision laser aiming system comprises a disrupter tool, a reflector, and a laser fixture. The disrupter tool, the reflector and the laser fixture are configurable for iterative alignment and aiming toward an explosive device threat. The invention enables a disrupter to be quickly and accurately set up, aligned, and aimed in order to render safe or to disrupt a target from a standoff position.

  7. Shaping propagation invariant laser beams

    NASA Astrophysics Data System (ADS)

    Soskind, Michael; Soskind, Rose; Soskind, Yakov

    2015-11-01

    Propagation-invariant structured laser beams possess several unique properties and play an important role in various photonics applications. The majority of propagation invariant beams are produced in the form of laser modes emanating from stable laser cavities. Therefore, their spatial structure is limited by the intracavity mode formation. We show that several types of anamorphic optical systems (AOSs) can be effectively employed to shape laser beams into a variety of propagation invariant structured fields with different shapes and phase distributions. We present a propagation matrix approach for designing AOSs and defining mode-matching conditions required for preserving propagation invariance of the output shaped fields. The propagation matrix approach was selected, as it provides a more straightforward approach in designing AOSs for shaping propagation-invariant laser beams than the alternative technique based on the Gouy phase evolution, especially in the case of multielement AOSs. Several practical configurations of optical systems that are suitable for shaping input laser beams into a diverse variety of structured propagation invariant laser beams are also presented. The laser beam shaping approach was applied by modeling propagation characteristics of several input laser beam types, including Hermite-Gaussian, Laguerre-Gaussian, and Ince-Gaussian structured field distributions. The influence of the Ince-Gaussian beam semifocal separation parameter and the azimuthal orientation between the input laser beams and the AOSs onto the resulting shape of the propagation invariant laser beams is presented as well.

  8. Gaussian-Beam Laser-Resonator Program

    NASA Technical Reports Server (NTRS)

    Cross, Patricia L.; Bair, Clayton H.; Barnes, Norman

    1989-01-01

    Gaussian Beam Laser Resonator Program models laser resonators by use of Gaussian-beam-propagation techniques. Used to determine radii of beams as functions of position in laser resonators. Algorithm used in program has three major components. First, ray-transfer matrix for laser resonator must be calculated. Next, initial parameters of beam calculated. Finally, propagation of beam through optical elements computed. Written in Microsoft FORTRAN (Version 4.01).

  9. Modematic: a fast laser beam analyzing system for high power CO2-laser beams

    NASA Astrophysics Data System (ADS)

    Olsen, Flemming O.; Ulrich, Dan

    2003-03-01

    The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 describing test methods for laser beam parameters have been approved. To implement these methods in industry is difficult and especially for the infrared laser sources, such as the CO2-laser, the availabl analyzing systems are slow, difficult to apply and having limited reliability due to the nature of the detection methods. In an EUREKA-project the goal was defined to develop a laser beam analyzing system dedicated to high power CO2-lasers, which could fulfill the demands for an entire analyzing system, automating the time consuming pre-alignment and beam conditioning work required before a beam mode analyses, automating the analyzing sequences and data analysis required to determine the laser beam caustics and last but not least to deliver reliable close to real time data to the operator. The results of this project work will be described in this paper. The research project has led to the development of the Modematic laser beam analyzer, which is ready for the market.

  10. Method of laser beam coding for control systems

    NASA Astrophysics Data System (ADS)

    Pałys, Tomasz; Arciuch, Artur; Walczak, Andrzej; Murawski, Krzysztof

    2017-08-01

    The article presents the method of encoding a laser beam for control systems. The experiments were performed using a red laser emitting source with a wavelength of λ = 650 nm and a power of P ≍ 3 mW. The aim of the study was to develop methods of modulation and demodulation of the laser beam. Results of research, in which we determined the effect of selected camera parameters, such as image resolution, number of frames per second on the result of demodulation of optical signal, is also shown in the paper. The experiments showed that the adopted coding method provides sufficient information encoded in a single laser beam (36 codes with the effectiveness of decoding at 99.9%).

  11. Laser beam pulse formatting method

    DOEpatents

    Daly, T.P.; Moses, E.I.; Patterson, R.W.; Sawicki, R.H.

    1994-08-09

    A method for formatting a laser beam pulse using one or more delay loops is disclosed. The delay loops have a partially reflective beam splitter and a plurality of highly reflective mirrors arranged such that the laser beam pulse enters into the delay loop through the beam splitter and circulates therein along a delay loop length defined by the mirrors. As the laser beam pulse circulates within the delay loop a portion thereof is emitted upon each completed circuit when the laser beam pulse strikes the beam splitter. The laser beam pulse is thereby formatted into a plurality of sub-pulses. The delay loops are used in combination to produce complex waveforms by combining the sub-pulses using additive waveform synthesis. 8 figs.

  12. Protective laser beam viewing device

    DOEpatents

    Neil, George R.; Jordan, Kevin Carl

    2012-12-18

    A protective laser beam viewing system or device including a camera selectively sensitive to laser light wavelengths and a viewing screen receiving images from the laser sensitive camera. According to a preferred embodiment of the invention, the camera is worn on the head of the user or incorporated into a goggle-type viewing display so that it is always aimed at the area of viewing interest to the user and the viewing screen is incorporated into a video display worn as goggles over the eyes of the user.

  13. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P.; Moses, Edward I.; Patterson, Ralph W.; Sawicki, Richard H.

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  14. Single element laser beam shaper

    DOEpatents

    Zhang, Shukui [Yorktown, VA; Shinn, Michelle D [Newport News, VA

    2005-09-13

    A single lens laser beam shaper for converting laser beams from any spatial profile to a flat-top or uniform spatial profile. The laser beam shaper includes a lens having two aspheric surfaces. The beam shaper significantly simplifies the overall structure in comparison with conventional 2-element systems and therefore provides great ease in alignment and reduction of cost.

  15. GAUSSIAN BEAM LASER RESONATOR PROGRAM

    NASA Technical Reports Server (NTRS)

    Cross, P. L.

    1994-01-01

    In designing a laser cavity, the laser engineer is frequently concerned with more than the stability of the resonator. Other considerations include the size of the beam at various optical surfaces within the resonator or the performance of intracavity line-narrowing or other optical elements. Laser resonators obey the laws of Gaussian beam propagation, not geometric optics. The Gaussian Beam Laser Resonator Program models laser resonators using Gaussian ray trace techniques. It can be used to determine the propagation of radiation through laser resonators. The algorithm used in the Gaussian Beam Resonator program has three major components. First, the ray transfer matrix for the laser resonator must be calculated. Next calculations of the initial beam parameters, specifically, the beam stability, the beam waist size and location for the resonator input element, and the wavefront curvature and beam radius at the input surface to the first resonator element are performed. Finally the propagation of the beam through the optical elements is computed. The optical elements can be modeled as parallel plates, lenses, mirrors, dummy surfaces, or Gradient Index (GRIN) lenses. A Gradient Index lens is a good approximation of a laser rod operating under a thermal load. The optical system may contain up to 50 elements. In addition to the internal beam elements the optical system may contain elements external to the resonator. The Gaussian Beam Resonator program was written in Microsoft FORTRAN (Version 4.01). It was developed for the IBM PS/2 80-071 microcomputer and has been implemented on an IBM PC compatible under MS DOS 3.21. The program was developed in 1988 and requires approximately 95K bytes to operate.

  16. Compression of Ultrafast Laser Beams

    DTIC Science & Technology

    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...for the design of future versions of this device. The easiest way to align the pulse shaper is to use the laser beam that will be shaped, without...Afterward, an ultrafast thin beam splitter is placed into the system after the diameter of the laser beam is reduced; this is done to monitor the beam

  17. Laser beam alignment system

    DOEpatents

    Kasner, William H.; Racki, Daniel J.; Swenson, Clark E.

    1984-01-01

    A plurality of pivotal reflectors direct a high-power laser beam onto a workpiece, and a rotatable reflector is movable to a position wherein it intercepts the beam and deflects a major portion thereof away from its normal path, the remainder of the beam passing to the pivotal reflectors through an aperture in the rotating reflector. A plurality of targets are movable to positions intercepting the path of light traveling to the pivotal reflectors, and a preliminary adjustment of the latter is made by use of a low-power laser beam reflected from the rotating reflector, after which the same targets are used to make a final adjustment of the pivotal reflectors with the portion of the high-power laser beam passed through the rotating reflector.

  18. Multi-beam laser altimeter

    NASA Technical Reports Server (NTRS)

    Bufton, Jack L.; Harding, David J.; Ramos-Izquierdo, Luis

    1993-01-01

    Laser altimetry provides a high-resolution, high-accuracy method for measurement of the elevation and horizontal variability of Earth-surface topography. The basis of the measurement is the timing of the round-trip propagation of short-duration pulses of laser radiation between a spacecraft and the Earth's surface. Vertical resolution of the altimetry measurement is determined primarily by laser pulsewidth, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain-switched pulses from solid-state lasers and sub-nsec resolution electronics, sub-meter vertical range resolution is possible from orbital attitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface, while laser pulse repetition-rate, laser transmitter beam configuration, and altimeter platform velocity determine the space between successive laser pulses. Multiple laser transitters in a singlaltimeter instrument provide across-track and along-track coverage that can be used to construct a range image of the Earth's surface. Other aspects of the multi-beam laser altimeter are discussed.

  19. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, C.R.; Hammond, R.B.

    The disclosure related to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

  20. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, Charles R.; Hammond, Robert B.

    1981-01-01

    The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

  1. Coherent superposition of propagation-invariant laser beams

    NASA Astrophysics Data System (ADS)

    Soskind, R.; Soskind, M.; Soskind, Y. G.

    2012-10-01

    The coherent superposition of propagation-invariant laser beams represents an important beam-shaping technique, and results in new beam shapes which retain the unique property of propagation invariance. Propagation-invariant laser beam shapes depend on the order of the propagating beam, and include Hermite-Gaussian and Laguerre-Gaussian beams, as well as the recently introduced Ince-Gaussian beams which additionally depend on the beam ellipticity parameter. While the superposition of Hermite-Gaussian and Laguerre-Gaussian beams has been discussed in the past, the coherent superposition of Ince-Gaussian laser beams has not received significant attention in literature. In this paper, we present the formation of propagation-invariant laser beams based on the coherent superposition of Hermite-Gaussian, Laguerre-Gaussian, and Ince-Gaussian beams of different orders. We also show the resulting field distributions of the superimposed Ince-Gaussian laser beams as a function of the ellipticity parameter. By changing the beam ellipticity parameter, we compare the various shapes of the superimposed propagation-invariant laser beams transitioning from Laguerre-Gaussian beams at one ellipticity extreme to Hermite-Gaussian beams at the other extreme.

  2. Focusing elliptical laser beams

    NASA Astrophysics Data System (ADS)

    Marchant, A. B.

    1984-03-01

    The spot formed by focusing an elliptical laser beam through an ordinary objective lens can be optimized by properly filling the objective lens. Criteria are given for maximizing the central irradiance and the line-spread function. An optimized spot is much less elliptical than the incident laser beam. For beam ellipticities as high as 2:1, this spatial filtering reduces the central irradiance by less than 14 percent.

  3. Laser beam generating apparatus

    DOEpatents

    Warner, Bruce E.; Duncan, David B.

    1993-01-01

    Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect).

  4. Laser beam generating apparatus

    DOEpatents

    Warner, Bruce E.; Duncan, David B.

    1994-01-01

    Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect).

  5. Phasing surface emitting diode laser outputs into a coherent laser beam

    DOEpatents

    Holzrichter, John F [Berkeley, CA

    2006-10-10

    A system for generating a powerful laser beam includes a first laser element and at least one additional laser element having a rear laser mirror, an output mirror that is 100% reflective at normal incidence and <5% reflective at an input beam angle, and laser material between the rear laser mirror and the output mirror. The system includes an injector, a reference laser beam source, an amplifier and phase conjugater, and a combiner.

  6. Microwave accelerator E-beam pumped laser

    DOEpatents

    Brau, Charles A.; Stein, William E.; Rockwood, Stephen D.

    1980-01-01

    A device and method for pumping gaseous lasers by means of a microwave accelerator. The microwave accelerator produces a relativistic electron beam which is applied along the longitudinal axis of the laser through an electron beam window. The incident points of the electron beam on the electron beam window are varied by deflection coils to enhance the cooling characteristics of the foil. A thyratron is used to reliably modulate the microwave accelerator to produce electron beam pulses which excite the laser medium to produce laser pulse repetition frequencies not previously obtainable. An aerodynamic window is also disclosed which eliminates foil heating problems, as well as a magnetic bottle for reducing laser cavity length and pressures while maintaining efficient energy deposition.

  7. Beam shaping in high-power laser systems with using refractive beam shapers

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Laskin, Vadim

    2012-06-01

    Beam Shaping of the spatial (transverse) profile of laser beams is highly desirable by building optical systems of high-power lasers as well in various applications with these lasers. Pumping of the crystals of Ti:Sapphire lasers by the laser radiation with uniform (flattop) intensity profile improves performance of these ultrashort pulse high-power lasers in terms of achievable efficiency, peak-power and stability, output beam profile. Specifications of the solid-state lasers built according to MOPA configuration can be also improved when radiation of the master oscillator is homogenized and then is amplified by the power amplifier. Features of building these high power lasers require that a beam shaping solution should be capable to work with single mode and multimode beams, provide flattop and super-Gauss intensity distributions, the consistency and divergence of a beam after the intensity re-distribution should be conserved and low absorption provided. These specific conditions are perfectly fulfilled by the refractive field mapping beam shapers due to their unique features: almost lossless intensity profile transformation, low output divergence, high transmittance and flatness of output beam profile, extended depth of field, adaptability to real intensity profiles of TEM00 and multimode laser sources. Combining of the refractive field mapping beam shapers with other optical components, like beam-expanders, relay imaging lenses, anamorphic optics makes it possible to generate the laser spots of necessary shape, size and intensity distribution. There are plenty of applications of high-power lasers where beam shaping bring benefits: irradiating photocathode of Free Electron Lasers (FEL), material ablation, micromachining, annealing in display making techniques, cladding, heat treating and others. This paper will describe some design basics of refractive beam shapers of the field mapping type, with emphasis on the features important for building and applications

  8. Laser beam generating apparatus

    DOEpatents

    Warner, B.E.; Duncan, D.B.

    1993-12-28

    Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect). 11 figures.

  9. E-beam-pumped semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Rice, Robert R.; Shanley, James F.; Ruggieri, Neil F.

    1995-04-01

    The collapse of the Soviet Union opened many areas of laser technology to the West. E-beam- pumped semiconductor lasers (EBSL) were pursued for 25 years in several Soviet Institutes. Thin single crystal screens of II-VI alloys (ZnxCd1-xSe, CdSxSe1-x) were incorporated in laser CRTs to produce scanned visible laser beams at average powers greater than 10 W. Resolutions of 2500 lines were demonstrated. MDA-W is conducting a program for ARPA/ESTO to assess EBSL technology for high brightness, high resolution RGB laser projection application. Transfer of II-VI crystal growth and screen processing technology is underway, and initial results will be reported. Various techniques (cathodoluminescence, one- and two-photon laser pumping, etc.) have been used to assess material quality and screen processing damage. High voltage (75 kV) video electronics were procured in the U.S. to operate test EBSL tubes. Laser performance was documented as a function of screen temperature, beam voltage and current. The beam divergence, spectrum, efficiency and other characteristics of the laser output are being measured. An evaluation of the effect of laser operating conditions upon the degradation rate is being carried out by a design-of-experiments method. An initial assessment of the projected image quality will be performed.

  10. Laser beam delivery at ELI-NP

    DOE PAGES

    Ursescu, Daniel; Cheriaux, G.; Audebert, P.; ...

    2017-01-01

    The Laser Beam Delivery (LBD) system technical design report covers the interface between the High Power Laser System (HPLS) and the experiments, together with the pulse quality management. Here, the laser transport part of the LBD has a number of subsystems as follows: the beam transport lines for the six main outputs of HPLS, the additional short and long pulses and the synchronization system including the timing of the laser pulses with the Gamma Beam System (GBS) and the experiments on femtosecond timescale. Pulse quality management, discussed further here, consist in the generation and delivery of multiple HPLS pulses, coherentmore » combining of the HPLS arms, laser pulse diagnostics on target, laser beam dumps, shutters and output energy adaption.« less

  11. Laser beam generating apparatus

    DOEpatents

    Warner, B.E.; Duncan, D.B.

    1994-02-15

    Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus is described. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect). 7 figures.

  12. Remote steering of laser beams by radar- and laser-induced refractive-index gradients in the atmosphere Remote steering of laser beams

    NASA Astrophysics Data System (ADS)

    Zheltikov, A. M.; Shneider, M. N.; Voronin, A. A.; Sokolov, A. V.; Scully, M. O.

    2012-01-01

    Refractive-index gradients induced in the atmospheric air by properly tailored laser and microwave fields are shown to enable a remote steering of laser beams. Heating-assisted modulation of the refractive index of the air by microwave radiation is shown to support small-angle laser-beam bending with bending angles on the order of 10-2. Ionization of the atmospheric air by dyads of femto- and nanosecond laser pulses, on the other hand, can provide beam deflection angles in excess of π/5, offering an attractive strategy for radiation transfer, free-space communications, and laser-based standoff detection.

  13. Laser Beam Shaping

    NASA Astrophysics Data System (ADS)

    Aït-Ameur, Kamel; Passilly, Nicolas; de Saint Denis, R.; Fromager, Michaël

    2008-09-01

    We consider the promising properties of very simple Diffractive Optical Elements (DOE) for reshaping the intensity profile of a laser beam. The first type of DOE that we have considered is a phase aperture which consists in a transparent plate with a circular relief introducing a π phase shift in the central region of the incident beam. The phase aperture is able to convert a Gaussian beam into a super-Gaussian, a ring-shaped or a doughnut profile. The second DOE that has been considered is an adjustable axicon able to transform a Gaussian laser beam into a dark hollow beam or a Bessel-Gauss beam. The desired conical geometry is obtained from a deformable mirror formed by a 2 inches, 0.25mm thick silicon wafer supported by a standard 2 inches optical mount. To achieve the adequate deformation a small metallic ball pushes the back of the mirror wafer. The realized shape is monitored with a Shack-Hartmann wave-front sensor and it is shown that conical shape cannot be achieved. Nevertheless, recorded wave fronts exhibit important third order spherical aberration able to achieve beam profile transformation as conical lenses.

  14. Cascaded injection resonator for coherent beam combining of laser arrays

    DOEpatents

    Kireev, Vassili [Sunnyvale, CA; Liu, Yun; Protopopescu, Vladimir [Knoxville, TN; Braiman, Yehuda [Oak Ridge, TN

    2008-10-21

    The invention provides a cascaded injection resonator for coherent beam combining of laser arrays. The resonator comprises a plurality of laser emitters arranged along at least one plane and a beam sampler for reflecting at least a portion of each laser beam that impinges on the beam sampler, the portion of each laser beam from one of the laser emitters being reflected back to another one of the laser emitters to cause a beam to be generated from the other one of the laser emitters to the beam reflector. The beam sampler also transmits a portion of each laser beam to produce a laser output beam such that a plurality of laser output beams of the same frequency are produced. An injection laser beam is directed to a first laser emitter to begin a process of generating and reflecting a laser beam from one laser emitter to another laser emitter in the plurality. A method of practicing the invention is also disclosed.

  15. Straightness measurement using laser beam straight datum

    NASA Astrophysics Data System (ADS)

    Uchikoshi, Junichi; Shimada, Shoichi; Ikawa, Naoya; Komura, Akio

    1995-08-01

    Using the direction stabilized laser beam as a physical straight datum, instead of the tangible reference surface, a method is proposed for the measurement of an error motion of a slide table and/or surface profile of mechanical components. A specially designed 2D position sensor/compensator for laser beam center is developed combining a quadrant photo-diode (QPD) position sensor for beam center and the piezo-compensator which compensates the beam shift from the center of QPD. By the use the sensor/compensator proposed, the positional and angular fluctuations of laser beam path is evaluated with nanometric resolution. Combining the sensor with the piezo-driven mirror compensator, the directional stabilizer for the laser beam is also designed in the same manner as the sensor/compensator. The stabilized He-Ne laser beam can be used as the metrological datum of straightness within the accuracy of 2 X 10 -8 rad. By mounting the position sensor/compensator on a slide table, the carriage with working distance of 1 m is so designed and built as to move straight along the stabilized laser beam. The carriage can be used as a mechanical straight datum with the accuracy equivalent to the laser beam stability.

  16. Initial alignment method for free space optics laser beam

    NASA Astrophysics Data System (ADS)

    Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

    2016-08-01

    The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

  17. Laser beam riding artillery missiles guidance device is designed

    NASA Astrophysics Data System (ADS)

    Yan, Mingliang; Huo, Zhicheng; Chen, Wei

    2014-09-01

    Laser driving gun missile guidance type beam of laser information field formed by any link failure or reduced stability will directly lead to ballistic or miss out of control, and based on this, this paper designed the driving beam of laser guided missile guidance beam type forming device modulation and zoom mechanism, in order to make the missile can recognize its position in the laser beam, laser beam gun missile, by means of spatial encoding of the laser beam laser beam into information after forming device, a surface to achieve the purpose of precision guidance.

  18. Beam uniformity of flat top lasers

    NASA Astrophysics Data System (ADS)

    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.

  19. Laser-driven ultrafast antiproton beam

    NASA Astrophysics Data System (ADS)

    Li, Shun; Pei, Zhikun; Shen, Baifei; Xu, Jiancai; Zhang, Lingang; Zhang, Xiaomei; Xu, Tongjun; Yu, Yong; Bu, Zhigang

    2018-02-01

    Antiproton beam generation is investigated based on the ultra-intense femtosecond laser pulse by using two-dimensional particle-in-cell and Geant4 simulations. A high-flux proton beam with an energy of tens of GeV is generated in sequential radiation pressure and bubble regime and then shoots into a high-Z target for producing antiprotons. Both yield and energy of the antiproton beam increase almost linearly with the laser intensity. The generated antiproton beam has a short pulse duration of about 5 ps and its flux reaches 2 × 10 20 s - 1 at the laser intensity of 2.14 × 10 23 W / cm 2 . Compared to conventional methods, this new method based on the ultra-intense laser pulse is able to provide a compact, tunable, and ultrafast antiproton source, which is potentially useful for quark-gluon plasma study, all-optical antihydrogen generation, and so on.

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

    DOEpatents

    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.

  1. Controlling Second Harmonic Efficiency of Laser Beam Interactions

    NASA Technical Reports Server (NTRS)

    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. Raman beam combining for laser brightness enhancement

    DOEpatents

    Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

    2015-10-27

    An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

  3. Beam shaping for laser-based adaptive optics in astronomy.

    PubMed

    Béchet, Clémentine; Guesalaga, Andrés; Neichel, Benoit; Fesquet, Vincent; González-Núñez, Héctor; Zúñiga, Sebastián; Escarate, Pedro; Guzman, Dani

    2014-06-02

    The availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%.

  4. HUBBLE DISCOVERS POWERFUL LASER BEAMED FROM CHAOTIC STAR

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is an artist's concept of a gas cloud (left) that acts as a natural ultraviolet laser, near the huge, unstable star Eta Carinae (right) -- one of most massive and energetic stars in our Milky Way Galaxy. The super-laser was identified by a team led by Kris Davidson of the University of Minnesota, and including nine other collaborators in the U.S. and Sweden during spectroscpic observations made with the Goddard High Resolution spectrograph aboard NASA's Hubble Space Telescope. Since it's unlikely that a single beam from the cloud would happen to be precisely aimed in earth's driection, the astronomers conclude that numerous beams must be radiating from the cloud in all directions - beams from a dance hall mirror-ball. The interstellar laser may result from Eta Carinae's violently chaotic eruptions, illustrated here as a reddish (due to light scattering by dust) outflow from the bright star. A laser, (an acronym for Light Amplification by Stimulated Emission of Radiation) creates an intense coherent beam of light when atoms or molecules in a gas, liquid or solid medium, force an incoming mix of wavelengths (or colors) of light to work in phase, or, at the same wavelength. Though a natural infrared laser was identified in space in 1995, lasers are very rare in space and nothing like the UV laser has ever been seen before. Eta Carinae is several million times brighter than the Sun, and one hundred times as massive. The superstar, located 8,000 light-years away in the souther constellation Carina, underwent a colossal outburst 150 years ago. Illustration courtesy James Gitlin/STScI

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

    DOEpatents

    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.

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

    DOEpatents

    Johnstone, C.J.

    1998-06-02

    A proton beam radiology system provides cancer treatment and proton radiography. The system includes an accelerator for producing an H{sup {minus}} 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 {minus}} beam and laser beam to produce a neutral beam therefrom within a subsection of the H{sup {minus}} 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 {minus}} beam in order to form the neutral beam in subsections of the H{sup {minus}} beam. As the scanning laser moves across the H{sup {minus}} 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. 9 figs.

  7. Laser processing with specially designed laser beam

    NASA Astrophysics Data System (ADS)

    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.

  8. Fitting relationship between the beam quality β factor of high-energy laser and the wavefront aberration of laser beam

    NASA Astrophysics Data System (ADS)

    Ji, Zhong-Ye; Zhang, Xiao-Fang

    2018-01-01

    The mathematical relation between the beam quality β factor of high-energy laser and the wavefront aberration of laser beam is important in beam quality control theory of the high-energy laser weapon system. In order to obtain this mathematical relation, numerical simulation is used in the research. Firstly, the Zernike representations of typically distorted atmospheric wavefront aberrations caused by the Kolmogoroff turbulence are generated. And then, the corresponding beam quality β factors of the different distorted wavefronts are calculated numerically through fast Fourier transform. Thus, the statistical distribution rule between the beam quality β factors of high-energy laser and the wavefront aberrations of the beam can be established by the calculated results. Finally, curve fitting method is chosen to establish the mathematical fitting relationship of these two parameters. And the result of the curve fitting shows that there is a quadratic curve relation between the beam quality β factor of high-energy laser and the wavefront aberration of laser beam. And in this paper, 3 fitting curves, in which the wavefront aberrations are consisted of Zernike Polynomials of 20, 36, 60 orders individually, are established to express the relationship between the beam quality β factor and atmospheric wavefront aberrations with different spatial frequency.

  9. Excimer laser beam delivery systems for medical applications

    NASA Astrophysics Data System (ADS)

    Kubo, Uichi; Hashishin, Yuichi; Okada, Kazuyuki; Tanaka, Hiroyuki

    1993-05-01

    We have been doing the basic experiments of UV laser beams and biotissue interaction with both KrF and XeCl lasers. However, the conventional optical fiber can not be available for power UV beams. So we have been investigating about UV power beam delivery systems. These experiments carry on with the same elements doped quartz fibers and the hollow tube. The doped elements are OH ion, chlorine and fluorine. In our latest work, we have tried ArF excimer laser and biotissue interactions, and the beam delivery experiments. From our experimental results, we found that the ArF laser beam has high incision ability for hard biotissue. For example, in the case of the cow's bone incision, the incision depth by ArF laser was ca.15 times of KrF laser. Therefore, ArF laser would be expected to harden biotissue therapy as non-thermal method. However, its beam delivery is difficult to work in this time. We will develop ArF laser beam delivery systems.

  10. Space Optical Communications Using Laser Beam Amplification

    NASA Technical Reports Server (NTRS)

    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.

  11. Enhanced laser beam coupling to a plasma

    DOEpatents

    Steiger, Arno D.; Woods, Cornelius H.

    1976-01-01

    Density perturbations are induced in a heated plasma by means of a pair of oppositely directed, polarized laser beams of the same frequency. The wavelength of the density perturbations is equal to one half the wavelength of the laser beams. A third laser beam is linearly polarized and directed at the perturbed plasma along a line that is perpendicular to the direction of the two opposed beams. The electric field of the third beam is oriented to lie in the plane containing the three beams. The frequency of the third beam is chosen to cause it to interact resonantly with the plasma density perturbations, thereby efficiently coupling the energy of the third beam to the plasma.

  12. Electron beam pumped semiconductor laser

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Laser beam control device

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marshall, H.L.

    1976-01-06

    The shutter and beam expander for diverting the output of a high power laser into an absorption body comprises a onepiece metallic structure having a convex spherically shaped portion adapted to be moved into the beam path for simultaneously reflecting and expanding the beam into energy absorption material.

  15. Laser-Beam-Absorption Chemical-Species Monitor

    NASA Technical Reports Server (NTRS)

    Gersh, Michael; Goldstein, Neil; Lee, Jamine; Bien, Fritz; Richtsmeier, Steven

    1996-01-01

    Apparatus measures concentration of chemical species in fluid medium (e.g., gaseous industrial process stream). Directs laser beam through medium, and measures intensity of beam after passage through medium. Relative amount of beam power absorbed in medium indicative of concentration of chemical species; laser wavelength chosen to be one at which species of interest absorbs.

  16. Ultraviolet laser beam monitor using radiation responsive crystals

    DOEpatents

    McCann, Michael P.; Chen, Chung H.

    1988-01-01

    An apparatus and method for monitoring an ultraviolet laser beam includes disposing in the path of an ultraviolet laser beam a substantially transparent crystal that will produce a color pattern in response to ultraviolet radiation. The crystal is exposed to the ultraviolet laser beam and a color pattern is produced within the crystal corresponding to the laser beam intensity distribution therein. The crystal is then exposed to visible light, and the color pattern is observed by means of the visible light to determine the characteristics of the laser beam that passed through crystal. In this manner, a perpendicular cross sectional intensity profile and a longitudinal intensity profile of the ultraviolet laser beam may be determined. The observation of the color pattern may be made with forward or back scattered light and may be made with the naked eye or with optical systems such as microscopes and television cameras.

  17. Detection of errant laser beams

    NASA Astrophysics Data System (ADS)

    Taylor, Arthur F. D. S.; Edwards, Stanley A.; Barrett, J. A.; Bandle, Anthony M.

    1990-10-01

    The new generation of automated laser machine tools poses problems for those responsible for setting safety standards. While traditional safeguarding will frustrate full exploitation of this hybrid technology, wholesale abandonment of effective containment in favour of safety monitoring and control systems is unlikely to be acceptable. Long term, quantitative risk assessment will resolve this dilemma. Short term, guide lines will have to be derived from practical considerations of the laser facility design, materials, primary safety devices and procedures. Earlier risk assessments are reviewed relative to the emerging perspective of high average power laser installations. Aspects of extended beam delivery systems and equipment utilization and maintenance are examined to assess possible interaction with operational safety and in particular the potential to adversely influence errant laser beam occurrances (ELBO). To satisfy international safety standards for a laser enclosure which offers flexibility and is cost effective a detection system is described which continuously surveys the inside of the enclosure. Extensive trials have been carried out with high average power lasers (up to 10kW) where a range of engineering materials has been exposed to a laser beam. It is shown that the ratio of detection and shut down time to the burn through time can be an acceptable risk and thus indicate which materials will prove adequate.

  18. Apparatus and method for laser beam diagnosis

    DOEpatents

    Salmon, Jr., Joseph T.

    1991-01-01

    An apparatus and method is disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam.

  19. Apparatus and method for laser beam diagnosis

    DOEpatents

    Salmon, J.T. Jr.

    1991-08-27

    An apparatus and method are disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam. 11 figures.

  20. Cross-Beam Energy Transfer Driven by Incoherent Laser Beams with Frequency Detuning

    NASA Astrophysics Data System (ADS)

    Maximov, A.; Myatt, J. F.; Short, R. W.; Igumenshchev, I. V.; Seka, W.

    2015-11-01

    In the direct-drive method of the inertial confinement fusion (ICF), the coupling of laser energy to target plasmas is strongly influenced by the effect of cross-beam energy transfer (CBET) between multiple driving laser beams. The laser -plasma interaction (LPI) model of CBET is based on the nonparaxial laser light propagation coupled with the low-frequency ion-acoustic-domain plasma response. Common ion waves driven by multiple laser beams play a very important role in CBET. The effect of the frequency detuning (colors) in the driving laser beams is studied and it is shown to significantly reduce the level of common ion waves and therefore the level of CBET. The differences between the LPI-based CBET model and the ray-based CBET model used in hydrocodes are discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. Laser beam shaping design based on micromirror array

    NASA Astrophysics Data System (ADS)

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

    2017-10-01

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

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

    NASA Astrophysics Data System (ADS)

    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. Diffractive beam shaping for enhanced laser polymer welding

    NASA Astrophysics Data System (ADS)

    Rauschenberger, J.; Vogler, D.; Raab, C.; Gubler, U.

    2015-03-01

    Laser welding of polymers increasingly finds application in a large number of industries such as medical technology, automotive, consumer electronics, textiles or packaging. More and more, it replaces other welding technologies for polymers, e. g. hot-plate, vibration or ultrasonic welding. At the same rate, demands on the quality of the weld, the flexibility of the production system and on processing speed have increased. Traditionally, diode lasers were employed for plastic welding with flat-top beam profiles. With the advent of fiber lasers with excellent beam quality, the possibility to modify and optimize the beam profile by beam-shaping elements has opened. Diffractive optical elements (DOE) can play a crucial role in optimizing the laser intensity profile towards the optimal M-shape beam for enhanced weld seam quality. We present results on significantly improved weld seam width constancy and enlarged process windows compared to Gaussian or flat-top beam profiles. Configurations in which the laser beam diameter and shape can be adapted and optimized without changing or aligning the laser, fiber-optic cable or optical head are shown.

  4. Coherent beam combiner for a high power laser

    DOEpatents

    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.

  5. Laser beam shaping for biomedical microscopy techniques

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Kaiser, Peter; Laskin, Vadim; Ostrun, Aleksei

    2016-04-01

    Uniform illumination of a working field is very important in optical systems of confocal microscopy and various implementations of fluorescence microscopy like TIR, SSIM, STORM, PALM to enhance performance of these laser-based research techniques. Widely used TEM00 laser sources are characterized by essentially non-uniform Gaussian intensity profile which leads usually to non-uniform intensity distribution in a microscope working field or in a field of microlenses array of a confocal microscope optical system, this non-uniform illumination results in instability of measuring procedure and reducing precision of quantitative measurements. Therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) profile is an actual technical task, it is solved by applying beam shaping optics. Due to high demands to optical image quality the mentioned techniques have specific requirements to a uniform laser beam: flatness of phase front and extended depth of field, - from this point of view the microscopy techniques are similar to holography and interferometry. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality required in discussed microscopy techniques. We suggest applying refractive field mapping beam shapers πShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. The main function of a beam shaper is transformation of laser intensity profile, further beam transformation to provide optimum for a particular technique spot size and shape has to

  6. Hankel-Bessel laser beams.

    PubMed

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

    2012-05-01

    An analytical solution of the scalar Helmholtz equation to describe the propagation of a laser light beam in the positive direction of the optical axis is derived. The complex amplitude of such a beam is found to be in direct proportion to the product of two linearly independent solutions of Kummer's differential equation. Relationships for a particular case of such beams-namely, the Hankel-Bessel (HB) beams-are deduced. The focusing of the HB beams is studied. © 2012 Optical Society of America

  7. Laser beam riding guided system principle and design research

    NASA Astrophysics Data System (ADS)

    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.

  8. Potential converter for laser-power beaming

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Williams, Michael D.; Schuster, Gregory L.; Iles, Peter A.

    1991-01-01

    Future space missions, such as those associated with the Space Exploration Initiative (SEI), will require large amounts of power for operation of bases, rovers, and orbit transfer vehicles. One method for supplying this power is to beam power from a spaced based or Earth based laser power station to a receiver where laser photons can be converted to electricity. Previous research has described such laser power stations orbiting the Moon and beaming power to a receiver on the surface of the Moon by using arrays of diode lasers. Photovoltaic converters that can be efficiently used with these diode lasers are described.

  9. Simulation based analysis of laser beam brazing

    NASA Astrophysics Data System (ADS)

    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.

  10. Effects of laser fluence on silicon modification by four-beam laser interference

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, Le; Li, Dayou; JR3CN and IRAC, University of Bedfordshire, Luton LU1 3JU

    2015-12-21

    This paper discusses the effects of laser fluence on silicon modification by four-beam laser interference. In this work, four-beam laser interference was used to pattern single crystal silicon wafers for the fabrication of surface structures, and the number of laser pulses was applied to the process in air. By controlling the parameters of laser irradiation, different shapes of silicon structures were fabricated. The results were obtained with the single laser fluence of 354 mJ/cm{sup 2}, 495 mJ/cm{sup 2}, and 637 mJ/cm{sup 2}, the pulse repetition rate of 10 Hz, the laser exposure pulses of 30, 100, and 300, the laser wavelength of 1064 nm, andmore » the pulse duration of 7–9 ns. The effects of the heat transfer and the radiation of laser interference plasma on silicon wafer surfaces were investigated. The equations of heat flow and radiation effects of laser plasma of interfering patterns in a four-beam laser interference distribution were proposed to describe their impacts on silicon wafer surfaces. The experimental results have shown that the laser fluence has to be properly selected for the fabrication of well-defined surface structures in a four-beam laser interference process. Laser interference patterns can directly fabricate different shape structures for their corresponding applications.« less

  11. Flat-top beam for laser-stimulated pain

    NASA Astrophysics Data System (ADS)

    McCaughey, Ryan; Nadeau, Valerie; Dickinson, Mark

    2005-04-01

    One of the main problems during laser stimulation in human pain research is the risk of tissue damage caused by excessive heating of the skin. This risk has been reduced by using a laser beam with a flattop (or superGaussian) intensity profile, instead of the conventional Gaussian beam. A finite difference approximation to the heat conduction equation has been applied to model the temperature distribution in skin as a result of irradiation by flattop and Gaussian profile CO2 laser beams. The model predicts that a 15 mm diameter, 15 W, 100 ms CO2 laser pulse with an order 6 superGaussian profile produces a maximum temperature 6 oC less than a Gaussian beam with the same energy density. A superGaussian profile was created by passing a Gaussian beam through a pair of zinc selenide aspheric lenses which refract the more intense central region of the beam towards the less intense periphery. The profiles of the lenses were determined by geometrical optics. In human pain trials the superGaussian beam required more power than the Gaussian beam to reach sensory and pain thresholds.

  12. Laser Transmitter Aims At Laser Beacon

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James R.

    1993-01-01

    Transmitter part of developmental optical communication system. Compact, lightweight, partially-self-aiming laser transmitter built to verify some capabilities of developmental free-space optical communication system. Design capable of providing 0.5 Mbps data return over range equal to Moon-Earth distance. Breadboard of transmitting terminal constructed and tested in laboratory. Prototype transmitter includes receiving circuitry that keeps it aimed at beacon, once brought into initial alignment within about 1.7 degrees of line of sight to beacon.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Scisciò, M.; Antici, P., E-mail: patrizio.antici@polytechnique.edu; INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes, Québec J3X 1S2

    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-frequencymore » (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.« less

  15. Dual-Beam Atom Laser Driven by Spinor Dynamics

    NASA Technical Reports Server (NTRS)

    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.

  16. Independent assessment of laser power beaming options

    NASA Technical Reports Server (NTRS)

    Ponikvar, Donald R.

    1992-01-01

    Technical and architectural issues facing a laser power beaming system are discussed. Issues regarding the laser device, optics, beam control, propagation, and lunar site are examined. Environmental and health physics aspects are considered.

  17. Towards ion beam therapy based on laser plasma accelerators.

    PubMed

    Karsch, Leonhard; Beyreuther, Elke; Enghardt, Wolfgang; Gotz, Malte; Masood, Umar; Schramm, Ulrich; Zeil, Karl; Pawelke, Jörg

    2017-11-01

    Only few ten radiotherapy facilities worldwide provide ion beams, in spite of their physical advantage of better achievable tumor conformity of the dose compared to conventional photon beams. Since, mainly the large size and high costs hinder their wider spread, great efforts are ongoing to develop more compact ion therapy facilities. One promising approach for smaller facilities is the acceleration of ions on micrometre scale by high intensity lasers. Laser accelerators deliver pulsed beams with a low pulse repetition rate, but a high number of ions per pulse, broad energy spectra and high divergences. A clinical use of a laser based ion beam facility requires not only a laser accelerator providing beams of therapeutic quality, but also new approaches for beam transport, dosimetric control and tumor conformal dose delivery procedure together with the knowledge of the radiobiological effectiveness of laser-driven beams. Over the last decade research was mainly focused on protons and progress was achieved in all important challenges. Although currently the maximum proton energy is not yet high enough for patient irradiation, suggestions and solutions have been reported for compact beam transport and dose delivery procedures, respectively, as well as for precise dosimetric control. Radiobiological in vitro and in vivo studies show no indications of an altered biological effectiveness of laser-driven beams. Laser based facilities will hardly improve the availability of ion beams for patient treatment in the next decade. Nevertheless, there are possibilities for a need of laser based therapy facilities in future.

  18. Transient beam oscillation with a highly dynamic scanner for laser beam fusion cutting

    NASA Astrophysics Data System (ADS)

    Goppold, Cindy; Pinder, Thomas; Herwig, Patrick

    2016-02-01

    Sheet metals with thicknesses >8 mm have a distinct cutting performance. The free choice of the optical configuration composed of fiber diameter, collimation, and focal length offers many opportunities to influence the static beam geometry. Previous analysis points out the limitations of this method in the thick section area. Within the present study, an experimental investigation of fiber laser fusion cutting of 12 mm stainless steel was performed by means of dynamical beam oscillation. Two standard optical setups are combined with a highly dynamic galvano-driven scanner that achieves frequencies up to 4 kHz. Dependencies of the scanner parameter, the optical circumstances, and the conventional cutting parameters are discussed. The aim is to characterize the capabilities and challenges of the dynamic beam shaping in comparison to the state-of-the-art static beam shaping. Thus, the trials are evaluated by quality criteria of the cut edge as surface roughness and burr height, the feed rate, and the cut kerf geometry. The investigation emphasizes promising procedural possibilities for improvements of the cutting performance in the case of fiber laser fusion cutting of thick stainless steel by means of the application of a highly dynamic scanner.

  19. Multi-focus beam shaping of high power multimode lasers

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Volpp, Joerg; Laskin, Vadim; Ostrun, Aleksei

    2017-08-01

    Beam shaping of powerful multimode fiber lasers, fiber-coupled solid-state and diode lasers is of great importance for improvements of industrial laser applications. Welding, cladding with millimetre scale working spots benefit from "inverseGauss" intensity profiles; performance of thick metal sheet cutting, deep penetration welding can be enhanced when distributing the laser energy along the optical axis as more efficient usage of laser energy, higher edge quality and reduction of the heat affected zone can be achieved. Building of beam shaping optics for multimode lasers encounters physical limitations due to the low beam spatial coherence of multimode fiber-coupled lasers resulting in big Beam Parameter Products (BPP) or M² values. The laser radiation emerging from a multimode fiber presents a mixture of wavefronts. The fiber end can be considered as a light source which optical properties are intermediate between a Lambertian source and a single mode laser beam. Imaging of the fiber end, using a collimator and a focusing objective, is a robust and widely used beam delivery approach. Beam shaping solutions are suggested in form of optics combining fiber end imaging and geometrical separation of focused spots either perpendicular to or along the optical axis. Thus, energy of high power lasers is distributed among multiple foci. In order to provide reliable operation with multi-kW lasers and avoid damages the optics are designed as refractive elements with smooth optical surfaces. The paper presents descriptions of multi-focus optics as well as examples of intensity profile measurements of beam caustics and application results.

  20. Laser-phased-array beam steering based on crystal fiber

    NASA Astrophysics Data System (ADS)

    Yang, Deng-cai; Zhao, Si-si; Wang, Da-yong; Wang, Zhi-yong; Zhang, Xiao-fei

    2011-06-01

    Laser-phased-array system provides an elegant means for achieving the inertial-free, high-resolution, rapid and random beam steering. In laser-phased-array system, phase controlling is the most important factor that impacts the system performance. A novel scheme is provided in this paper, the beam steering is accomplished by using crystal fiber array, the difference length between adjacent fiber is fixed. The phase difference between adjacent fiber decides the direction of the output beam. When the wavelength of the input fiber laser is tuned, the phase difference between the adjacent elements has changed. Therefore, the laser beam direction has changed and the beam steering has been accomplished. In this article, based on the proposed scheme, the steering angle of the laser beam is calculated and analyzed theoretically. Moreover, the far-field steering beam quality is discussed.

  1. Formation of propagation invariant laser beams with anamorphic optical systems

    NASA Astrophysics Data System (ADS)

    Soskind, Y. G.

    2015-03-01

    Propagation invariant structured laser beams play an important role in several photonics applications. A majority of propagation invariant beams are usually produced in the form of laser modes emanating from stable laser cavities. This work shows that anamorphic optical systems can be effectively employed to transform input propagation invariant laser beams and produce a variety of alternative propagation invariant structured laser beam distributions with different shapes and phase structures. This work also presents several types of anamorphic lens systems suitable for transforming the input laser modes into a variety of structured propagation invariant beams. The transformations are applied to different laser mode types, including Hermite-Gaussian, Laguerre-Gaussian, and Ince-Gaussian field distributions. The influence of the relative azimuthal orientation between the input laser modes and the anamorphic optical systems on the resulting transformed propagation invariant beams is presented as well.

  2. Fine Structure in Helium-like Fluorine by Fast-Beam Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Myers, E. G.; Thompson, J. K.; Silver, J. D.

    1998-05-01

    With the aim of providing an additional precise test of higher-order corrections to high precision calculations of fine structure in helium and helium-like ions(T. Zhang, Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 77), 1715 (1996)., a measurement of the 2^3P_2,F - 2^3P_1,F' fine structure in ^19F^7+ is in progress. The method involves doppler-tuned laser spectroscopy using a CO2 laser on a foil-stripped fluorine ion beam. We aim to achieve a higher precision, compared to an earlier measurement(E.G. Myers, P. Kuske, H.J. Andrae, I.A. Armour, H.A. Klein, J.D. Silver, and E. Traebert, Phys. Rev. Lett. 47), 87 (1981)., by using laser beams parallel and anti-parallel to the ion beam, to obtain partial cancellation of the doppler shift(J.K. Thompson, D.J.H. Howie and E.G. Myers, Phys. Rev. A 57), 180 (1998).. A calculation of the hyperfine structure, allowing for relativistic, QED and nuclear size effects, will be required to obtain the ``hyperfine-free'' fine structure interval from the measurements.

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

    NASA Technical Reports Server (NTRS)

    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.

  4. Nuclear Physics with 10 PW laser beams at Extreme Light Infrastructure - Nuclear Physics (ELI-NP)

    NASA Astrophysics Data System (ADS)

    Zamfir, N. V.

    2014-05-01

    The field of the uncharted territory of high-intensity laser interaction with matter is confronted with new exotic phenomena and, consequently, opens new research perspectives. The intense laser beams interacting with a gas or solid target generate beams of electrons, protons and ions. These beams can induce nuclear reactions. Electrons also generate ions high-energy photons via bremsstrahlung processes which can also induce nuclear reactions. In this context a new research domain began to form in the last decade or so, namely nuclear physics with high power lasers. The observation of high brilliance proton beams of tens of MeV energy from solid targets has stimulated an intense research activity. The laser-driven particle beams have to compete with conventional nuclear accelerator-generated beams. The ultimate goal is aiming at applications of the laser produced beams in research, technology and medicine. The mechanism responsible for ion acceleration are currently subject of intensive research in many laboratories in the world. The existing results, experimental and theoretical, and their perspectives are reviewed in this article in the context of IZEST and the scientific program of ELI-NP.

  5. High-precision laser microcutting and laser microdrilling using diffractive beam-splitting and high-precision flexible beam alignment

    NASA Astrophysics Data System (ADS)

    Zibner, F.; Fornaroli, C.; Holtkamp, J.; Shachaf, Lior; Kaplan, Natan; Gillner, A.

    2017-08-01

    High-precision laser micro machining gains more importance in industrial applications every month. Optical systems like the helical optics offer highest quality together with controllable and adjustable drilling geometry, thus as taper angle, aspect ratio and heat effected zone. The helical optics is based on a rotating Dove-prism which is mounted in a hollow shaft engine together with other optical elements like wedge prisms and plane plates. Although the achieved quality can be interpreted as extremely high the low process efficiency is a main reason that this manufacturing technology has only limited demand within the industrial market. The objective of the research studies presented in this paper is to dramatically increase process efficiency as well as process flexibility. During the last years, the average power of commercial ultra-short pulsed laser sources has increased significantly. The efficient utilization of the high average laser power in the field of material processing requires an effective distribution of the laser power onto the work piece. One approach to increase the efficiency is the application of beam splitting devices to enable parallel processing. Multi beam processing is used to parallelize the fabrication of periodic structures as most application only require a partial amount of the emitted ultra-short pulsed laser power. In order to achieve highest flexibility while using multi beam processing the single beams are diverted and re-guided in a way that enables the opportunity to process with each partial beam on locally apart probes or semimanufactures.

  6. Undersea Laser Communication with Narrow Beams

    DTIC Science & Technology

    2015-09-29

    Abstract Laser sources enable highly efficient optical communications links due to their ability to be focused into very directive beam profiles...Recent atmospheric and space optical links have demonstrated robust laser communications links at high rate with techniques that are applicable to the...undersea environment. These techniques contrast to the broad-angle beams utilized in most reported demonstrations of undersea optical communications

  7. Quality factor analysis for aberrated laser beam

    NASA Astrophysics Data System (ADS)

    Ghafary, B.; Alavynejad, M.; Kashani, F. D.

    2006-12-01

    The quality factor of laser beams has attracted considerable attention and some different approaches have been reported to treat the problem. In this paper we analyze quality factor of laser beam and compare the effect of different aberrations on beam quality by expanding pure phase term of wavefront in terms of Zernike polynomials. Also we analyze experimentally the change of beam quality for different Astigmatism aberrations, and compare theoretical results with experimentally results. The experimental and theoretical results are in good agreement.

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

    NASA Astrophysics Data System (ADS)

    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-plasma plume interaction during laser welding

    NASA Astrophysics Data System (ADS)

    Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

    2003-10-01

    Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

  10. Laser Beam Welding of Nitride Steel Components

    NASA Astrophysics Data System (ADS)

    Gu, Hongping; Yin, Guobin; Shulkin, Boris

    Laser beam welding is a joining technique that has many advantages over conventional GMAW welding, such as low heat input, short cycle time as well as good cosmetic welds. Laser beam welding has been widely used for welding powertrain components in automotive industry. When welding nitride steel components, however, laser beam welding faces a great challenge. The difficulty lies in the fact that the nitride layer in the joint releases the nitrogen into the weld pool, resulting in a porous weld. This research presents an industrial ready solution to prevent the nitrogen from forming gas bubbles in the weld.

  11. Beam uniformity analysis of infrared laser illuminators

    NASA Astrophysics Data System (ADS)

    Allik, Toomas H.; Dixon, Roberta E.; Proffitt, R. Patrick; Fung, Susan; Ramboyong, Len; Soyka, Thomas J.

    2015-02-01

    Uniform near-infrared (NIR) and short-wave infrared (SWIR) illuminators are desired in low ambient light detection, recognition, and identification of military applications. Factors that contribute to laser illumination image degradation are high frequency, coherent laser speckle and low frequency nonuniformities created by the laser or external laser cavity optics. Laser speckle analysis and beam uniformity improvements have been independently studied by numerous authors, but analysis to separate these two effects from a single measurement technique has not been published. In this study, profiles of compact, diode laser NIR and SWIR illuminators were measured and evaluated. Digital 12-bit images were recorded with a flat-field calibrated InGaAs camera with measurements at F/1.4 and F/16. Separating beam uniformity components from laser speckle was approximated by filtering the original image. The goal of this paper is to identify and quantify the beam quality variation of illumination prototypes, draw awareness to its impact on range performance modeling, and develop measurement techniques and methodologies for military, industry, and vendors of active sources.

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

    PubMed

    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.

  13. Tailored laser beam shaping for efficient and accurate microstructuring

    NASA Astrophysics Data System (ADS)

    Häfner, T.; Strauß, J.; Roider, C.; Heberle, J.; Schmidt, M.

    2018-02-01

    Large-area processing with high material removal rates by ultrashort pulsed (USP) lasers is coming into focus by the development of high-power USP laser systems. However, currently the bottleneck for high-rate production is given by slow and inefficient beam manipulation. On the one hand, slow beam deflection with regard to high pulse repetition rates leads to heat accumulation and shielding effects, on the other hand, a conventional focus cannot provide the optimum fluence due to the Gaussian intensity profile. In this paper, we emphasize on two approaches of dynamic laser beam shaping with liquid crystal on silicon spatial light modulation and acousto-optic beam shaping. Advantages and limitations of dynamic laser beam shaping with regard to USP laser material processing and methods for reducing the influence of speckle are discussed. Additionally, the influence of optics induced aberrations on speckle characteristics is evaluated. Laser material processing results are presented correlating the achieved structure quality with the simulated and measured beam quality. Experimental and analytical investigations show a certain fluence dependence of the necessary number of alternative holograms to realize homogeneous microstructures.

  14. Optimum Laser Beam Characteristics for Achieving Smoother Ablations in Laser Vision Correction.

    PubMed

    Verma, Shwetabh; Hesser, Juergen; Arba-Mosquera, Samuel

    2017-04-01

    Controversial opinions exist regarding optimum laser beam characteristics for achieving smoother ablations in laser-based vision correction. The purpose of the study was to outline a rigorous simulation model for simulating shot-by-shot ablation process. The impact of laser beam characteristics like super Gaussian order, truncation radius, spot geometry, spot overlap, and lattice geometry were tested on ablation smoothness. Given the super Gaussian order, the theoretical beam profile was determined following Lambert-Beer model. The intensity beam profile originating from an excimer laser was measured with a beam profiler camera. For both, the measured and theoretical beam profiles, two spot geometries (round and square spots) were considered, and two types of lattices (reticular and triangular) were simulated with varying spot overlaps and ablated material (cornea or polymethylmethacrylate [PMMA]). The roughness in ablation was determined by the root-mean-square per square root of layer depth. Truncating the beam profile increases the roughness in ablation, Gaussian profiles theoretically result in smoother ablations, round spot geometries produce lower roughness in ablation compared to square geometry, triangular lattices theoretically produce lower roughness in ablation compared to the reticular lattice, theoretically modeled beam profiles show lower roughness in ablation compared to the measured beam profile, and the simulated roughness in ablation on PMMA tends to be lower than on human cornea. For given input parameters, proper optimum parameters for minimizing the roughness have been found. Theoretically, the proposed model can be used for achieving smoothness with laser systems used for ablation processes at relatively low cost. This model may improve the quality of results and could be directly applied for improving postoperative surface quality.

  15. KrF laser pumping by electron beam discharge

    NASA Astrophysics Data System (ADS)

    Bonnet, J.; Fournier, G.; Pigache, D.

    1981-09-01

    The pumping of excimer lasers used in nuclear fusion and isotope separation is considered. Homogeneous ionization with an electron beam permitted discharge pumping of a KrF laser with a discharge-energy/beam-energy ratio 5. This high value is obtained to the detriment of an energy density and an efficiency which are about half the best values obtained under other conditions. This result does not modify a recent conclusion indicating that an electron beam controlled discharge has no significant advantage over a pure electron beam as regards pumping high energy KrF lasers at high repetition rate.

  16. Polarized millijoule fiber laser system with high beam quality and pulse shaping ability

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Tian, Xiaocheng; Xu, Dangpeng; Zhou, Dandan; Zong, Zhaoyu; Li, Hongxun; Fan, Mengqiu; Huang, Zhihua; Zhu, Na; Su, Jingqin; Zhu, Qihua; Jing, Feng

    2017-05-01

    The coherent amplification network (CAN) aims at developing a laser system based on the coherent combination of multiple laser beams, which are produced through a network of high beam quality optical fiber amplifiers. The scalability of the CAN laser facilitates the development of many novel applications, such as fiber-based acceleration, orbital debris removal and inertial confinement fusion energy. According to the requirements of CAN and the front end of high-power laser facilities, a millijoule polarized fiber laser system was studied in this paper. Using polarization maintaining Ytterbium-fiber laser system as the seed, and 10-μm core Yb-doped fiber amplifier as the first power amplifier and 40-μm core polarizing (PZ) photonic crystal fiber (PCF) as the second power amplifier, the all-fiber laser system outputs 1.06-mJ energy at 10 ns and diffraction limited mode quality. Using 85-μm rod-type PCF as the third power amplifiers, 2.5-mJ energy at 10-ns pulse width was obtained with better than 500:1 peak-to-foot pulse shaping ability and fundamental mode beam quality. The energy fluctuation of the system is 1.3% rms with 1-mJ output in one hour. When using phase-modulated pulse as the seed, the frequency modulation to amplitude modulation (FM-to-AM) conversion ratio of the system is better than 5%. This fiber laser system has the advantages of high beam quality, high beam shaping ability, good stability, small volume and free of maintenance, which can be used in many applications.

  17. Laser streaming: Turning a laser beam into a flow of liquid

    PubMed Central

    Wang, Yanan; Zhang, Qiuhui; Zhu, Zhuan; Lin, Feng; Deng, Jiangdong; Ku, Geng; Dong, Suchuan; Song, Shuo; Alam, Md Kamrul; Liu, Dong; Wang, Zhiming; Bao, Jiming

    2017-01-01

    Transforming a laser beam into a mass flow has been a challenge both scientifically and technologically. We report the discovery of a new optofluidic principle and demonstrate the generation of a steady-state water flow by a pulsed laser beam through a glass window. To generate a flow or stream in the same path as the refracted laser beam in pure water from an arbitrary spot on the window, we first fill a glass cuvette with an aqueous solution of Au nanoparticles. A flow will emerge from the focused laser spot on the window after the laser is turned on for a few to tens of minutes; the flow remains after the colloidal solution is completely replaced by pure water. Microscopically, this transformation is made possible by an underlying plasmonic nanoparticle-decorated cavity, which is self-fabricated on the glass by nanoparticle-assisted laser etching and exhibits size and shape uniquely tailored to the incident beam profile. Hydrophone signals indicate that the flow is driven via acoustic streaming by a long-lasting ultrasound wave that is resonantly generated by the laser and the cavity through the photoacoustic effect. The principle of this light-driven flow via ultrasound, that is, photoacoustic streaming by coupling photoacoustics to acoustic streaming, is general and can be applied to any liquid, opening up new research and applications in optofluidics as well as traditional photoacoustics and acoustic streaming. PMID:28959726

  18. Laser streaming: Turning a laser beam into a flow of liquid.

    PubMed

    Wang, Yanan; Zhang, Qiuhui; Zhu, Zhuan; Lin, Feng; Deng, Jiangdong; Ku, Geng; Dong, Suchuan; Song, Shuo; Alam, Md Kamrul; Liu, Dong; Wang, Zhiming; Bao, Jiming

    2017-09-01

    Transforming a laser beam into a mass flow has been a challenge both scientifically and technologically. We report the discovery of a new optofluidic principle and demonstrate the generation of a steady-state water flow by a pulsed laser beam through a glass window. To generate a flow or stream in the same path as the refracted laser beam in pure water from an arbitrary spot on the window, we first fill a glass cuvette with an aqueous solution of Au nanoparticles. A flow will emerge from the focused laser spot on the window after the laser is turned on for a few to tens of minutes; the flow remains after the colloidal solution is completely replaced by pure water. Microscopically, this transformation is made possible by an underlying plasmonic nanoparticle-decorated cavity, which is self-fabricated on the glass by nanoparticle-assisted laser etching and exhibits size and shape uniquely tailored to the incident beam profile. Hydrophone signals indicate that the flow is driven via acoustic streaming by a long-lasting ultrasound wave that is resonantly generated by the laser and the cavity through the photoacoustic effect. The principle of this light-driven flow via ultrasound, that is, photoacoustic streaming by coupling photoacoustics to acoustic streaming, is general and can be applied to any liquid, opening up new research and applications in optofluidics as well as traditional photoacoustics and acoustic streaming.

  19. Laser beam-profile impression and target thickness impact on laser-accelerated protons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schollmeier, M.; Harres, K.; Nuernberg, F.

    Experimental results on the influence of the laser focal spot shape onto the beam profile of laser-accelerated protons from gold foils are reported. The targets' microgrooved rear side, together with a stack of radiochromic films, allowed us to deduce the energy-dependent proton source-shape and size, respectively. The experiments show, that shape and size of the proton source depend only weakly on target thickness as well as shape of the laser focus, although they strongly influence the proton's intensity distribution. It was shown that the laser creates an electron beam that closely follows the laser beam topology, which is maintained duringmore » the propagation through the target. Protons are then accelerated from the rear side with an electron created electric field of a similar shape. Simulations with the Sheath-Accelerated Beam Ray-tracing for IoN Analysis code SABRINA, which calculates the proton distribution in the detector for a given laser-beam profile, show that the electron distribution during the transport through a thick target (50 {mu}m Au) is only modified due to multiple small angle scattering. Thin targets (10 {mu}m) show large source sizes of over 100 {mu}m diameter for 5 MeV protons, which cannot be explained by multiple scattering only and are most likely the result of refluxing electrons.« less

  20. Laser beam propagation in atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    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.

  1. Laser beam guard clamps

    DOEpatents

    Dickson, Richard K.

    2010-09-07

    A quick insert and release laser beam guard panel clamping apparatus having a base plate mountable on an optical table, a first jaw affixed to the base plate, and a spring-loaded second jaw slidably carried by the base plate to exert a clamping force. The first and second jaws each having a face acutely angled relative to the other face to form a V-shaped, open channel mouth, which enables wedge-action jaw separation by and subsequent clamping of a laser beam guard panel inserted through the open channel mouth. Preferably, the clamping apparatus also includes a support structure having an open slot aperture which is positioned over and parallel with the open channel mouth.

  2. ELIMED: a new hadron therapy concept based on laser driven ion beams

    NASA Astrophysics Data System (ADS)

    Cirrone, Giuseppe A. P.; Margarone, Daniele; Maggiore, Mario; Anzalone, Antonello; Borghesi, Marco; Jia, S. Bijan; Bulanov, Stepan S.; Bulanov, Sergei; Carpinelli, Massimo; Cavallaro, Salvatore; Cutroneo, Mariapompea; Cuttone, Giacomo; Favetta, Marco; Gammino, Santo; Klimo, Ondrej; Manti, Lorenzo; Korn, Georg; La Malfa, Giuseppe; Limpouch, Jiri; Musumarra, Agatino; Petrovic, Ivan; Prokupek, Jan; Psikal, Jan; Ristic-Fira, Aleksandra; Renis, Marcella; Romano, Francesco P.; Romano, Francesco; Schettino, Giuseppe; Schillaci, Francesco; Scuderi, Valentina; Stancampiano, Concetta; Tramontana, Antonella; Ter-Avetisyan, Sargis; Tomasello, Barbara; Torrisi, Lorenzo; Tudisco, Salvo; Velyhan, Andriy

    2013-05-01

    Laser accelerated proton beams have been proposed to be used in different research fields. A great interest has risen for the potential replacement of conventional accelerating machines with laser-based accelerators, and in particular for the development of new concepts of more compact and cheaper hadrontherapy centers. In this context the ELIMED (ELI MEDical applications) research project has been launched by INFN-LNS and ASCR-FZU researchers within the pan-European ELI-Beamlines facility framework. The ELIMED project aims to demonstrate the potential clinical applicability of optically accelerated proton beams and to realize a laser-accelerated ion transport beamline for multi-disciplinary user applications. In this framework the eye melanoma, as for instance the uveal melanoma normally treated with 62 MeV proton beams produced by standard accelerators, will be considered as a model system to demonstrate the potential clinical use of laser-driven protons in hadrontherapy, especially because of the limited constraints in terms of proton energy and irradiation geometry for this particular tumour treatment. Several challenges, starting from laser-target interaction and beam transport development up to dosimetry and radiobiology, need to be overcome in order to reach the ELIMED final goals. A crucial role will be played by the final design and realization of a transport beamline capable to provide ion beams with proper characteristics in terms of energy spectrum and angular distribution which will allow performing dosimetric tests and biological cell irradiation. A first prototype of the transport beamline has been already designed and other transport elements are under construction in order to perform a first experimental test with the TARANIS laser system by the end of 2013. A wide international collaboration among specialists of different disciplines like Physics, Biology, Chemistry, Medicine and medical doctors coming from Europe, Japan, and the US is growing up

  3. Laser beam distribution system for the HiLASE Center

    NASA Astrophysics Data System (ADS)

    Macúchová, Karolina; Heřmánek, Jan; Kaufman, Jan; Muresan, Mihai-George; Růžička, Jan; Řeháková, Martina; Divoký, Martin; Švandrlík, Luděk.; Mocek, Tomáś

    2017-12-01

    We report recent progress in design and testing of a distribution system for high-power laser beam delivery developed within the HiLASE project of the IOP in the Czech Republic. Laser beam distribution system is a technical system allowing safe and precise distribution of different laser beams from laboratories to several experimental stations. The unique nature of HiLASE lasers requires new approach, which makes design of the distribution system a state-of-the-art challenge.

  4. Beacon Beams for Deep Turbulence High Energy Laser Beam Directors

    DTIC Science & Technology

    2012-11-02

    variance and nC is the atmospheric refractive index structure constant. The effect of turbulence on the focused beacon beam on target, TR...complete phase conjugation of the beacon beam is accomplished by employing Brillouin enhanced optical four wave mixing. A beacon beam formed by...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6790--12-9445 Beacon Beams for Deep Turbulence High Energy Laser Beam Directors P

  5. Integrated Electro-optical Laser-Beam Scanners

    NASA Technical Reports Server (NTRS)

    Boord, Warren T.

    1990-01-01

    Scanners using solid-state devices compact, consume little power, and have no moving parts. Integrated electro-optical laser scanner, in conjunction with external lens, points outgoing beam of light in any number of different directions, depending on number of upper electrodes. Offers beam-deflection angles larger than those of acousto-optic scanners. Proposed for such diverse applications as nonimpact laser printing, color imaging, ranging, barcode reading, and robotic vision.

  6. Characteristics of laser beam focusing with single spherical mirrors during laser treatment

    NASA Astrophysics Data System (ADS)

    Borkin, A. G.; Drobyazko, S. V.; Kosheleva, G. A.; Pavlovich, Yu. V.; Senatorov, Yu. M.; Fromm, V. A.; Kurchatov, I. V.

    1988-04-01

    Focusing of a laser beam with a single spherical mirror is analyzed, such a mirror being combined with a rotatable annular plane mirror in a coaxial configuration. Its focal length must be sufficiently large to ensure adequately high power density and to avoid shielding. When the distance from mirror to laser cavity is too large, then the laser beam may degenerate into a nonannular one and its focusing without loss may become unattainable. Tilting the spherical mirror will make this possible, even when the laser beam is not annular, if astigmatism as well as spherical aberration are minimized. Such a focusing mirror made of metal is theoretically shown to be much more effective than a focusing lens made of KC1 crystal; this has been confirmed experimentally in a CO sub 2 laser facility for perforation of tubular seperator meshes.

  7. Laser beam alignment and profilometry using diagnostic fluorescent safety mirrors

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.

    2011-03-01

    There are a wide range of laser beam delivery systems in use for various purposes; including industrial and medical applications. Virtually all such beam delivery systems for practical purposes employ optical systems comprised of mirrors and lenses to shape, focus and guide the laser beam down to the material being processed. The goal of the laser beam delivery is to set the optimum parameters and to "fold" the beam path to reduce the mechanical length of the optical system, thereby allowing a physically compact system. In many cases, even a compact system can incorporate upwards of six mirrors and a comparable number of lenses all needing alignment so they are collinear. One of the major requirements for use of such systems in industry is a method of safe alignment. The alignment process requires that the aligner determine where the beam strikes each element. The aligner should also preferably be able to determine the shape or pattern of the laser beam at that point and its relative power. These alignments are further compounded in that the laser beams generated are not visible to the unaided human eye. Such beams are also often of relatively high power levels, and are thereby a significant hazard to the eyes of the aligner. Obvious an invisible beam makes it nearly impossible to align laser system without some form of optical assistance. The predominant method of visually aligning the laser beam delivery is the use of thermal paper, paper cards or fluorescing card material. The use of paper products which have limited power handling capability or coated plastics can produce significant debris and contaminants within the beam line that ultimately damage the optics. The use of the cards can also create significant laser light scatter jeopardizing the safety of the person aligning the system. This paper covers a new safety mirror design for use with at various UV and Near IR wavelengths (193 nm to 1064 nm) within laser beam delivery systems and how its use can

  8. Influence of turbulent atmosphere on laser beams from confocal unstable resonators

    NASA Astrophysics Data System (ADS)

    Peng, Yu-feng; Wang, Juan; Bi, Xiao-qun; Zhang, Ming-gao; Cheng, Zu-hai

    2009-07-01

    Based on the laser fields from a positive confocal unstable resonator (ab initio), the propagation characteristics of the beam through turbulent atmosphere are investigated by means of fast Fourier transform algorithm (FFT). To conveniently investigate the propagation characteristics of laser beam through the atmosphere, as far as known, in the previous many works, a mathematical expression was generally artificially predefined to represent the given laser beam, such as Gaussian beam, Hermite-cosh-Gaussian beam, flat topped beam, dark-hollow (annular) beam, etc. In this paper, by basing on the initial built in oscillation of a laser resonator, such as a positive confocal unstable resonator (CUR), we studied the intensity distributions of the output laser field to obtain the propagation characteristics of laser beam through the turbulent atmosphere as functions of different propagation distances. The results show that the turbulence will result in the degradation of the peak value of the laser intensity in the far field, the spread of the far field diagram patterns, and the beam quality characteristics greatly degraded.

  9. Scattering apodizer for laser beams

    DOEpatents

    Summers, Mark A.; Hagen, Wilhelm F.; Boyd, Robert D.

    1985-01-01

    A method is disclosed for apodizing a laser beam to smooth out the production of diffraction peaks due to optical discontinuities in the path of the laser beam, such method comprising introduction of a pattern of scattering elements for reducing the peak intensity in the region of such optical discontinuities, such pattern having smoothly tapering boundaries in which the distribution density of the scattering elements is tapered gradually to produce small gradients in the distribution density, such pattern of scattering elements being effective to reduce and smooth out the diffraction effects which would otherwise be produced. The apodizer pattern may be produced by selectively blasting a surface of a transparent member with fine abrasive particles to produce a multitude of minute pits. In one embodiment, a scattering apodizer pattern is employed to overcome diffraction patterns in a multiple element crystal array for harmonic conversion of a laser beam. The interstices and the supporting grid between the crystal elements are obscured by the gradually tapered apodizer pattern of scattering elements.

  10. Scattering apodizer for laser beams

    DOEpatents

    Summers, M.A.; Hagen, W.F.; Boyd, R.D.

    1984-01-01

    A method is disclosed for apodizing a laser beam to smooth out the production of diffraction peaks due to optical discontinuities in the path of the laser beam, such method comprising introduction of a pattern of scattering elements for reducing the peak intensity in the region of such optical discontinuities, such pattern having smoothly tapering boundaries in which the distribution density of the scattering elements is tapered gradually to produce small gradients in the distribution density, such pattern of scattering elements being effective to reduce and smooth out the diffraction effects which would otherwise be produced. The apodizer pattern may be produced by selectively blasting a surface of a transparent member with fine abrasive particles to produce a multitude of minute pits. In one embodiment, a scattering apodizer pattern is employed to overcome diffraction patterns in a multiple element crystal array for harmonic conversion of a laser beam. The interstices and the supporting grid between the crystal elements are obscured by the gradually tapered apodizer pattern of scattering elements.

  11. Apparatus Translates Crossed-Laser-Beam Probe Volume

    NASA Technical Reports Server (NTRS)

    Herring, Gregory C.; South, Bruce W.; Exton, Reginald J.

    1994-01-01

    Optomechanical apparatus translates probe volume of crossed-beam laser velocimeter or similar instrument while maintaining optical alignment of beams. Measures velocity, pressure, and temperature of flowing gas at several locations. Repeated tedious realignments no longer necessary. Designed to accommodate stimulated-Raman-gain spectrometer for noninvasive measurement of local conditions in flowing gas in supersonic wind tunnel. Applicable to other techniques like coherent anti-Stokes Raman spectroscopy involving use of laser beams crossed at small angles (10 degrees or less).

  12. High-power beam combining: a step to a future laser weapon system

    NASA Astrophysics Data System (ADS)

    Protz, Rudolf; Zoz, Jürgen; Geidek, Franz; Dietrich, Stephan; Fall, Michael

    2012-11-01

    Due to the enormous progress in the field of high-power fiber lasers during the last years commercial industrial fiber lasers are now available, which deliver a near-diffraction limited beam with power levels up to10kW. For the realization of a future laser weapon system, which can be used for Counter-RAM or similar air defence applications, a laser source with a beam power at the level of 100kW or more is required. At MBDA Germany the concept for a high-energy laser weapon system is investigated, which is based on such existing industrial laser sources as mentioned before. A number of individual high-power fiber laser beams are combined together, using one common beam director telescope. By this "geometric" beam coupling scheme, sufficient laser beam power for an operational laser weapon system can be achieved. The individual beams from the different lasers are steered by servo-loops, using fast tip-tilt mirrors. This principle enables the concentration of the total laser beam power at the common focal point on a distant target, also allowing fine tracking of target movements and first order compensation of turbulence effects on laser beam propagation. The proposed beam combination concept was demonstrated using several experimental set-ups. Different experiments were performed, to investigate laser beam target interaction and target fine tracking also at large distances. Content and results of these investigations are reported. An example for the lay-out of an Air Defence High Energy Laser Weapon (ADHELW ) is given. It can be concluded, that geometric high-power beam combining is an important step for the realization of a laser weapon system in the near future.

  13. Observation of laser beam profile progression inside an extended laser cavity

    NASA Astrophysics Data System (ADS)

    Wu, Frank F.; Farrell, Thomas C.

    2013-03-01

    This report presents the result of the laser beam profile progression in target-in-the-loop (TIL) system. This simulation experiment is to verify whether it is possible to form a tight hot spot similar to a single transversal mode in an extended laser cavity. Therefore, it is very important to observe the progression of the laser profile at a laser cavity mirror when a seeded high energy laser pulse is injected into the TIL system. The extended laser cavity is formed with a high reflectivity mirror on one end and an optical phase conjugated mirror as the second mirror, with potential disturbance media inside. The laser oscillation occurs only when it is triggered with a single frequency high energy laser pulse to overcome the threshold condition. With a laser cavity length of around 11 meters and a seeded laser pulse of 10 ns, we have been able to acquire and distinguish the laser beam profiles of each round-trip. Inserting a scattering media and other distortion elements can simulate atmospheric effects.

  14. Space Optical Communications Using Laser Beams

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M. (Inventor)

    2017-01-01

    A system for communicating between an object in space and a ground station, between objects in space, or between ground stations, includes a telecentric lens. Photodetectors positioned upon a focal plane of the telecentric lens detect an inbound light beam, received from a source, that has passed through the telecentric lens to the focal plane. Lasers positioned upon the focal plane transmit light beams from the focal plane through the telecentric lens to an area that includes the source of the inbound light beam. A processor detect signals from individual photodetectors corresponding to light detected, and selectively signals individual lasers that are close to those photodetectors, resulting in a returning beam that arrives close to the source, and which carries encoded data.

  15. Method and apparatus for monitoring the power of a laser beam

    DOEpatents

    Paris, R.D.; Hackel, R.P.

    1996-02-06

    A method for monitoring the power of a laser beam in real time is disclosed. At least one optical fiber is placed through the laser beam, where a portion of light from the laser beam is coupled into the optical fiber. The optical fiber may be maintained in a stationary position or moved periodically over a cross section of the laser beam to couple light from each area traversed. Light reaching both fiber ends is monitored according to frequency and processed to determine the power of the laser beam. 6 figs.

  16. Method and apparatus for monitoring the power of a laser beam

    DOEpatents

    Paris, Robert D.; Hackel, Richard P.

    1996-01-01

    A method for monitoring the power of a laser beam in real time is disclosed. At least one optical fiber is placed through the laser beam, where a portion of light from the laser beam is coupled into the optical fiber. The optical fiber may be maintained in a stationary position or moved periodically over a cross section of the laser beam to couple light from each area traversed. Light reaching both fiber ends is monitored according to frequency and processed to determine the power of the laser beam.

  17. The Beam Characteristics of High Power Diode Laser Stack

    NASA Astrophysics Data System (ADS)

    Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

    2018-03-01

    Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

  18. High-power direct diode laser output by spectral beam combining

    NASA Astrophysics Data System (ADS)

    Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

    2018-03-01

    We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

  19. Influence of laser beam profiles on received power fluctuation

    NASA Astrophysics Data System (ADS)

    Dordova, Lucie; Diblik, Jan

    2011-09-01

    Gaussian beam is very often used for the transmission of information in optical wireless links. The usage of this optical beam has its advantages and, of course, disadvantages. This work focuses on possibilities of using laser beams with different distribution of optical intensity - Top Hat beam. Creation of the optical beam with selected optical intensity profile will be briefly described. Optical beams will propagate through the "clear" and stationary atmosphere in the experimental part of this work. These results will be compared with the data obtained after a laser beam is passed through the turbulent and attenuated atmosphere. We will use an ultrasound fog generator for laser beam attenuation testing. To create the turbulence, infra radiators will be applied. Particular results obtained from different atmospheric conditions will be compared and using different types of optical beams will be assessed.

  20. Nanoparticles based laser-induced surface structures formation on mesoporous silicon by picosecond laser beam interaction

    NASA Astrophysics Data System (ADS)

    Talbi, A.; Petit, A.; Melhem, A.; Stolz, A.; Boulmer-Leborgne, C.; Gautier, G.; Defforge, T.; Semmar, N.

    2016-06-01

    In this study, laser induced periodic surface structures were formed on mesoporous silicon by irradiation of Nd:YAG picosecond pulsed laser beam at 266 nm wavelength at 1 Hz repetition rate and with 42 ps pulse duration. The effects of laser processing parameters as laser beam fluence and laser pulse number on the formation of ripples were investigated. Scanning electron microscopy and atomic force microscopy were used to image the surface morphologies and the cross section of samples after laser irradiation. At relatively low fluence ∼20 mJ/cm2, ripples with period close to the laser beam wavelength (266 nm) and with an always controlled orientation (perpendicular to the polarization of ps laser beam) appeared after a large laser pulse number of 12,000. It has been found that an initial random distribution of SiOx nanoparticles is periodically structured with an increase of the laser pulse number. Finally, it is experimentally demonstrated that we formed a 100 nm liquid phase under the protusion zones including the pores in the picosecond regime.

  1. Red and infrared gas laser beam for therapy

    NASA Astrophysics Data System (ADS)

    Pascu, Mihail-Lucian; Ristici, Marin; Ristici, E.; Tivarus, Madalina-Elena

    2000-06-01

    For the low power laser therapy, the experiments show that better results are obtained when the laser beam is an overlapping of two radiations: one in the visible region of the spectrum and the other in IR region. Also, some experiments show that for good results in biostimulation it is important to have a high coherence length of laser beam; this is not the case of the laser diodes The He-Ne laser has the best coherence, being able to generate laser radiations in visible and IR. It has tow strong laser lines: 633 nm and 1.15 micrometers . Although their gains are about the same, the available power of the red radiation is 3-4 times higher because of its larger width, when they oscillate separately. Using special dichroic mirrors for simultaneous reflection of the both liens, the laser beam will consist of the two radiations, each of them having good coherence . A 420 mm active length, 1.8 mm inner diameter He-Ne laser tube and a special designed resonator has been developed. The mirrors reflect both radiations as follows: one reflects 99.9 percent and the other, the output mirror, reflects 98 percent. There is a competition between them because these lines have a common lower level. The output power of the laser beam as 6 mW for 633 nm and 4 mW for 1.15 micrometers , respectively.

  2. Influence of laser beam incidence angle on laser lap welding quality of galvanized steels

    NASA Astrophysics Data System (ADS)

    Mei, Lifang; Yan, Dongbing; Chen, Genyu; Wang, Zhenhui; Chen, Shuixuan

    2017-11-01

    Based on the characteristics of laser welded structural parts of auto bodies, the influence of variation in laser beam incidence angle on the lap welding performance of galvanized auto-body sheets was studied. Lap welding tests were carried out on the galvanized sheets for auto-body application at different laser beam incidence angles by using the optimal welding parameters obtained through orthogonal experiment. The effects of incidence angle variation on seam appearance, cross-sectional shape, joint mechanical properties and microstructure of weldments were analyzed. In addition, the main factors influencing the value of incidence angle were investigated. According to the results, the weld seams had a good appearance as well as a fine, and uniform microstructure when the laser beam incidence angle was smaller than the critical incidence angle, and thus they could withstand great tensile and shear loads. Moreover, all tensile-shear specimens were fractured in the base material zone. When the laser beam incidence angle was larger than the critical incidence angle, defects like shrinkage and collapse tended to emerge, thereby resulting in the deteriorated weldability of specimens. Meanwhile, factors like the type and thickness of sheet, weld width as well as inter-sheet gap all had a certain effect on the value of laser beam incidence angle. When the sheet thickness was small and the weld width was narrow, the laser beam incidence angle could be increased appropriately. At the same time, small changes in the inter-sheet gap could greatly impact the value of incidence angle. When the inter-sheet gap was small, the laser beam incidence angle should not be too large.

  3. Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

    NASA Technical Reports Server (NTRS)

    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.

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

    DOE PAGES

    Liu, Y.; Rakhman, A.; Menshov, A.; ...

    2016-12-01

    A high-efficiency laser assisted hydrogen ion (H-) beam stripping was recently 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 study 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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Y.; Rakhman, A.; Menshov, A.

    A high-efficiency laser assisted hydrogen ion (H-) beam stripping was recently 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 study 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.

  6. Dual beam optical system for pulsed laser ablation film deposition

    DOEpatents

    Mashburn, Douglas N.

    1996-01-01

    A laser ablation apparatus having a laser source outputting a laser ablation beam includes an ablation chamber having a sidewall, a beam divider for dividing the laser ablation beam into two substantially equal halves, and a pair of mirrors for converging the two halves on a surface of the target from complementary angles relative to the target surface normal, thereby generating a plume of ablated material emanating from the target.

  7. Synchronous characterization of semiconductor microcavity laser beam.

    PubMed

    Wang, T; Lippi, G L

    2015-06-01

    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.

  8. Laser beam shaping for studying thermally induced damage

    NASA Astrophysics Data System (ADS)

    Masina, Bathusile N.; Bodkin, Richard; Mwakikunga, Bonex; Forbes, Andrew

    2011-10-01

    This paper presents an implementation of a laser beam shaping system for both heating a diamond tool and measuring the resulting temperature optically. The influence the initial laser parameters have on the resultant temperature profiles is shown experimentally and theoretically. A CO2 laser beam was used as the source to raise the temperature of the diamond tool and the resultant temperature was measured by using the blackbody principle. We have successfully transformed a Gaussian beam profile into a flat-top beam profile by using a diffractive optical element as a phase element in conjunction with a Fourier transforming lens. In this paper, we have successfully demonstrated temperature profiles across the diamond tool surface using two laser beam profiles and two optical setups, thus allowing a study of temperature influences with and without thermal stress. The generation of such temperature profiles on the diamond tool in the laboratory is important in the study of changes that occur in diamond tools, particularly the reduced efficiency of such tools in applications where extreme heating due to friction is expected.

  9. Rapid and efficient formation of propagation invariant shaped laser beams.

    PubMed

    Chriki, Ronen; Barach, Gilad; Tradosnky, Chene; Smartsev, Slava; Pal, Vishwa; Friesem, Asher A; Davidson, Nir

    2018-02-19

    A rapid and efficient all-optical method for forming propagation invariant shaped beams by exploiting the optical feedback of a laser cavity is presented. The method is based on the modified degenerate cavity laser (MDCL), which is a highly incoherent cavity laser. The MDCL has a very large number of degrees of freedom (320,000 modes in our system) that can be coupled and controlled, and allows direct access to both the real space and Fourier space of the laser beam. By inserting amplitude masks into the cavity, constraints can be imposed on the laser in order to obtain minimal loss solutions that would optimally lead to a superposition of Bessel-Gauss beams forming a desired shaped beam. The resulting beam maintains its transverse intensity distribution for relatively long propagation distances.

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

    PubMed

    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.

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

    PubMed

    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 × 10 4 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.

  12. Radiobiological effectiveness of laser accelerated electrons in comparison to electron beams from a conventional linear accelerator.

    PubMed

    Laschinsky, Lydia; Baumann, Michael; Beyreuther, Elke; Enghardt, Wolfgang; Kaluza, Malte; Karsch, Leonhard; Lessmann, Elisabeth; Naumburger, Doreen; Nicolai, Maria; Richter, Christian; Sauerbrey, Roland; Schlenvoigt, Hans-Peter; Pawelke, Jörg

    2012-01-01

    The notable progress in laser particle acceleration technology promises potential medical application in cancer therapy through compact and cost effective laser devices that are suitable for already existing clinics. Previously, consequences on the radiobiological response by laser driven particle beams characterised by an ultra high peak dose rate have to be investigated. Therefore, tumour and non-malignant cells were irradiated with pulsed laser accelerated electrons at the JETI facility for the comparison with continuous electrons of a conventional therapy LINAC. Dose response curves were measured for the biological endpoints clonogenic survival and residual DNA double strand breaks. The overall results show no significant differences in radiobiological response for in vitro cell experiments between laser accelerated pulsed and clinical used electron beams. These first systematic in vitro cell response studies with precise dosimetry to laser driven electron beams represent a first step toward the long term aim of the application of laser accelerated particles in radiotherapy.

  13. Variable ratio beam splitter for laser applications

    NASA Technical Reports Server (NTRS)

    Brown, R. M.

    1971-01-01

    Beam splitter employing birefringent optics provides either widely different or precisely equal beam ratios, it can be used with laser light source systems for interferometry of lossy media, holography, scattering measurements, and precise beam ratio applications.

  14. Gaussian content as a laser beam quality parameter.

    PubMed

    Ruschin, Shlomo; Yaakobi, Elad; Shekel, Eyal

    2011-08-01

    We propose the Gaussian content (GC) as an optional quality parameter for the characterization of laser beams. It is defined as the overlap integral of a given field with an optimally defined Gaussian. The definition is especially suited for applications where coherence properties are targeted. Mathematical definitions and basic calculation procedures are given along with results for basic beam profiles. The coherent combination of an array of laser beams and the optimal coupling between a diode laser and a single-mode fiber are elaborated as application examples. The measurement of the GC and its conservation upon propagation are experimentally confirmed.

  15. Dual beam optical system for pulsed laser ablation film deposition

    DOEpatents

    Mashburn, D.N.

    1996-09-24

    A laser ablation apparatus having a laser source outputting a laser ablation beam includes an ablation chamber having a sidewall, a beam divider for dividing the laser ablation beam into two substantially equal halves, and a pair of mirrors for converging the two halves on a surface of the target from complementary angles relative to the target surface normal, thereby generating a plume of ablated material emanating from the target. 3 figs.

  16. Binary phase plates cannot improve laser beam quality.

    PubMed

    Siegman, A E

    1993-05-01

    Binary phase plates are often suggested as a means for improving the far-field brightness of beams coming from antiphased laser arrays or waveguide lasers operating in higher-order modes. Somewhat surprisingly, however, binary phase plates actually cannot improve at all the second-moment-based beam quality factor M(2) as usually defined for such beams. Even from a power-in-the-bucket viewpoint, their usefulness is debatable.

  17. Handling And Safety Aspects Of Fiber Optic Laser Beam Delivery Systems

    NASA Astrophysics Data System (ADS)

    Schonborn, K.-H.; Wodrich, W.

    1988-06-01

    Using lasers for therapeutic applications is getting more and more accepted. In ophthalmology Ar-lasers for intraocular applications are quite common. The Nd:YAG-laser is used as a high power tool in connection with silica fibers for different extracorporal and intracorporal applications. The CO2-laser is the cutting laser, one problem being the beam transmission: The state of the art in fibers is not sufficient up to now. Because of the high power used safety against laser radiation hazard is of great importance. The safety in laser use is primarily dependent on the surgeons cautiousness, e.g. using laser protection goggels, observing that the spot of the aiming beam is present etc. On the other hand the laser and fiber system has to be inherently safe by appropriate technical means as far as possible. An additional aspect adding to safety is the handling: With easier system handling less attention of the surgeon is necessary for driving the apparatus. Thus he can concentrate on the patient and on the procedure. In considering the fiber system one important point in handling and safety is the coupling of the fiber to the laser head. The development philosophy in this coupling may be divided into two groups: - one is trying to use standard connectors which were initially developed for data transmission; - the other is using special connectors. One example of the first group is the guiding of the laser beam from the Ar-laser to the slit-lamp in ophtalmology. Here the well-known F-SMA connectors together with a special fiber with adapted numerical aperture are used. The advantage of such a system is the low price of the connector. For high power lasers such as the clinical Nd:YAG lasers with 40 to 150 W those connectors are not suitable. Up to now every laser manufacturer developed his own connector system in this field.

  18. Apparatus and method for increasing the bandwidth of a laser beam

    DOEpatents

    Wilcox, Russell B.

    1992-01-01

    A method and apparatus using sinusoidal cross-phase modulation, provides a laser pulse having a very broad bandwidth while substantially retaining the input laser's temporal shape. The modulator may be used in a master oscillator system for a laser having a master oscillator-power amplifier (MOPA) configration. The modulator utilizes a first laser providing an output wavelength .lambda. and a second laser providing an output wavelength shifted by a small amount to .lambda.+.DELTA..lambda.. Each beam has a single, linear polarization. Each beam is coupled into a length of polarization-preserving optical fiber. The first laser beam is coupled into the optical fiber with the beam's polarization aligned with the fiber's main axis, and the second beam is coupled into the fiber with its polarization rotated from the main axis by a predetermined angle. Within the fiber, the main axis' polarization defines an interference beam and the orthogonal axis' polarization defines a signal beam. In the interference beam, the first laser beam and the parallel polarized vector component of the other beam interfere to create areas of high and low intensity, which modulates the signal beam by cross phase modulation. Upon exit from the optical fiber, the beams are coupled out and the modulated signal beam is separated out by a polarization selector. The signal beam can be applied to coherence reducing systems to provide an output that is temporally and spatially incoherent. The U.S. Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

  19. Laser wakefield accelerated electron beam monitoring and control

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koga, J. K.; Mori, M.; Kotaki, H.

    2016-03-25

    We will discuss our participation in the ImPACT project, which has as one of its goals the development of an ultra-compact electron accelerator using lasers (< 1 GeV, < 10   m) and the generation of an x-ray beam from the accelerated electrons. Within this context we will discuss our investigation into electron beam monitoring and control. Since laser accelerated electrons will be used for x-ray beam generation combined with an undulator, we will present investigation into the possibilities of the improvement of electron beam emittance through cooling.

  20. Phoenix's Laser Beam in Action on Mars

    NASA Technical Reports Server (NTRS)

    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.

  1. Laser-Beam-Alignment Controller

    NASA Technical Reports Server (NTRS)

    Krasowski, M. J.; Dickens, D. E.

    1995-01-01

    In laser-beam-alignment controller, images from video camera compared to reference patterns by fuzzy-logic pattern comparator. Results processed by fuzzy-logic microcontroller, which sends control signals to motor driver adjusting lens and pinhole in spatial filter.

  2. Laser Beam and Resonator Calculations on Desktop Computers.

    NASA Astrophysics Data System (ADS)

    Doumont, Jean-Luc

    There is a continuing interest in the design and calculation of laser resonators and optical beam propagation. In particular, recently, interest has increased in developing concepts such as one-sided unstable resonators, supergaussian reflectivity profiles, diode laser modes, beam quality concepts, mode competition, excess noise factors, and nonlinear Kerr lenses. To meet these calculation needs, I developed a general-purpose software package named PARAXIA ^{rm TM}, aimed at providing optical scientists and engineers with a set of powerful design and analysis tools that provide rapid and accurate results and are extremely easy to use. PARAXIA can handle separable paraxial optical systems in cartesian or cylindrical coordinates, including complex-valued and misaligned ray matrices, with full diffraction effects between apertures. It includes the following programs:. ABCD provides complex-valued ray-matrix and gaussian -mode analyses for arbitrary paraxial resonators and optical systems, including astigmatism and misalignment in each element. This program required that I generalize the theory of gaussian beam propagation to the case of an off-axis gaussian beam propagating through a misaligned, complex -valued ray matrix. FRESNEL uses FFT and FHT methods to propagate an arbitrary wavefront through an arbitrary paraxial optical system using Huygens' integral in rectangular or radial coordinates. The wavefront can be multiplied by an arbitrary mirror profile and/or saturable gain sheet on each successive propagation through the system. I used FRESNEL to design a one-sided negative-branch unstable resonator for a free -electron laser, and to show how a variable internal aperture influences the mode competition and beam quality in a stable cavity. VSOURCE implements the virtual source analysis to calculate eigenvalues and eigenmodes for unstable resonators with both circular and rectangular hard-edged mirrors (including misaligned rectangular systems). I used VSOURCE to

  3. A numerical simulation of machining glass by dual CO 2-laser beams

    NASA Astrophysics Data System (ADS)

    Jiao, Junke; Wang, Xinbing

    2008-03-01

    In the flat panel display (FPD) industry, lasers may be used to cut glass plates. In order to reduce the possibility of fracture in the process of cutting glass by lasers, the thermal stress has to be less than the critical rupture strength. In this paper, a dual-laser-beam method is proposed, where an off-focus CO 2-laser beam was used to preheat the glass sample to reduce the thermal gradients and a focused CO 2-laser beam was used to machine the glass. The distribution of the thermal stress and the temperature was simulated by using finite element analysis software, Ansys. The thermal stress was studied both when the glass sample was machined by a single CO 2-laser beam and by dual CO 2-laser beams. It was concluded that the thermal stress can be reduced by means of the dual-laser-beam method.

  4. A Conceptual Design of Omni-Directional Receiving Dual-Beam Laser Engine

    NASA Astrophysics Data System (ADS)

    Tang, Zhiping; Zhang, Qinghong

    2010-05-01

    The laser engine design is one of the key issues for laser propulsion technology. A concept of Omni-Directional Receiving Dual-Beam Laser Engine (ODLE) together with its configuration design is proposed in this paper. The ODLE is noted for its features as follows: First, the optical system is completely separated from the thrust system, the incident laser beams are reflected into the thrust chamber by the optics only twice, so the beam energy loss is small. Second, the optical system can be adjusted in all direction to track the incident laser beams, ensuring its wide applications in various kinds of launching trajectories. Third, the adoption of the dual-beam single-or double-engine configuration can reduce 50% of the power requirement for each laser, and a smooth laser relay can be carried out if needed during the launching process. The paper has proposed 2 launch plans into the LEO with the ODLE: the plane trajectory and the conic spiral trajectory. The simulated results indicate that the transmission distance of laser beams for the conic spiral trajectory is far less than that of the plane trajectory. As a result, it can reduce significantly the divergence and energy loss of laser beams, and is also of advantage for the measurement and control operation during the launch process.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Automated beam monitoring and diagnosis for CO2 lasers

    NASA Astrophysics Data System (ADS)

    Mann, Stefan; Boeske, Lars; Kaierle, Stefan; Kreutz, Ernst-Wolfgang; Poprawe, Reinhart

    2002-06-01

    The usage of a quality management, in combination with a standard certification, is nearly inevitable for today's industrial manufacturing. In laser materials processing, a periodical beam diagnosis is to be executed as a quality-maintaining measure with any change of the workpiece geometry to guarantee an unambiguous allocation of the beam quality factors. Otherwise changes in the beam quality, caused by pollution, aging or defect of the optical components, remain unidentified for a long time, leading to impairments of the treatment quality or even costly down-times. As a solution a diagnosis system is integrated into a laser system. Data sources like measuring instruments, sensors and laser control transmit the diagnosis data to a diagnosis PC. A user-friendly software, based on Fuzzy algorithms, enables the operator to retrace changes in the beam quality to failures of the laser system. All diagnosis data are getting archived in a databank. The access to the archived data through the World Wide Web allows remote diagnoses. With the help of the beam diagnosis system failures can be discovered in advance, and losses of production can be avoided. The gained transparency of the beam characteristic values facilitates the integration of the laser system in the quality management. A prototype installation has been realized and latest results will be demonstrated.

  7. Generation of low-divergence laser beams

    DOEpatents

    Kronberg, James W.

    1993-01-01

    Apparatus for transforming a conventional beam of coherent light, having a Gaussian energy distribution and relatively high divergence, into a beam in which the energy distribution approximates a single, non-zero-order Bessel function and which therefore has much lower divergence. The apparatus comprises a zone plate having transmitting and reflecting zones defined by the pattern of light interference produced by the combination of a beam of coherent light with a Gaussian energy distribution and one having such a Bessel distribution. The interference pattern between the two beams is a concentric array of multiple annuli, and is preferably recorded as a hologram. The hologram is then used to form the transmitting and reflecting zones by photo-etching portions of a reflecting layer deposited on a plate made of a transmitting material. A Bessel beam, containing approximately 50% of the energy of the incident beam, is produced by passing a Gaussian beam through such a Bessel zone plate. The reflected beam, also containing approximately 50% of the incident beam energy and having a Bessel energy distribution, can be redirected in the same direction and parallel to the transmitted beam. Alternatively, a filter similar to the Bessel zone plate can be placed within the resonator cavity of a conventional laser system having a front mirror and a rear mirror, preferably axially aligned with the mirrors and just inside the front mirror to generate Bessel energy distribution light beams at the laser source.

  8. Generation of low-divergence laser beams

    DOEpatents

    Kronberg, J.W.

    1993-09-14

    Apparatus for transforming a conventional beam of coherent light, having a Gaussian energy distribution and relatively high divergence, into a beam in which the energy distribution approximates a single, non-zero-order Bessel function and which therefore has much lower divergence. The apparatus comprises a zone plate having transmitting and reflecting zones defined by the pattern of light interference produced by the combination of a beam of coherent light with a Gaussian energy distribution and one having such a Bessel distribution. The interference pattern between the two beams is a concentric array of multiple annuli, and is preferably recorded as a hologram. The hologram is then used to form the transmitting and reflecting zones by photo-etching portions of a reflecting layer deposited on a plate made of a transmitting material. A Bessel beam, containing approximately 50% of the energy of the incident beam, is produced by passing a Gaussian beam through such a Bessel zone plate. The reflected beam, also containing approximately 50% of the incident beam energy and having a Bessel energy distribution, can be redirected in the same direction and parallel to the transmitted beam. Alternatively, a filter similar to the Bessel zone plate can be placed within the resonator cavity of a conventional laser system having a front mirror and a rear mirror, preferably axially aligned with the mirrors and just inside the front mirror to generate Bessel energy distribution light beams at the laser source. 11 figures.

  9. Radiobiological study by using laser-driven proton beams

    NASA Astrophysics Data System (ADS)

    Yogo, A.; Sato, K.; Nishikino, M.; Mori, M.; Teshima, T.; Numasaki, H.; Murakami, M.; Demizu, Y.; Akagi, S.; Nagayama, S.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Oishi, Y.; Sugiyama, H.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Tanoue, M.; Sugiyama, H.; Sasao, H.; Wakai, D.; Kawachi, T.; Nishimura, H.; Bolton, P. R.; Daido, H.

    2009-07-01

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of γ-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  10. System for obtaining smooth laser beams where intensity variations are reduced by spectral dispersion of the laser light (SSD)

    DOEpatents

    Skupsky, S.; Kessler, T.J.; Short, R.W.; Craxton, S.; Letzring, S.A.; Soures, J.

    1991-09-10

    In an SSD (smoothing by spectral dispersion) system which reduces the time-averaged spatial variations in intensity of the laser light to provide uniform illumination of a laser fusion target, an electro-optic phase modulator through which a laser beam passes produces a broadband output beam by imposing a frequency modulated bandwidth on the laser beam. A grating provides spatial and angular spectral dispersion of the beam. Due to the phase modulation, the frequencies (''colors'') cycle across the beam. The dispersed beam may be amplified and frequency converted (e.g., tripled) in a plurality of beam lines. A distributed phase plate (DPP) in each line is irradiated by the spectrally dispersed beam and the beam is focused on the target where a smooth (uniform intensity) pattern is produced. The color cycling enhances smoothing and the use of a frequency modulated laser pulse prevents the formation of high intensity spikes which could damage the laser medium in the power amplifiers. 8 figures.

  11. System for obtaining smooth laser beams where intensity variations are reduced by spectral dispersion of the laser light (SSD)

    DOEpatents

    Skupsky, Stanley; Kessler, Terrance J.; Short, Robert W.; Craxton, Stephen; Letzring, Samuel A.; Soures, John

    1991-01-01

    In an SSD (smoothing by spectral dispersion) system which reduces the time-averaged spatial variations in intensity of the laser light to provide uniform illumination of a laser fusion target, an electro-optic phase modulator through which a laser beam passes produces a broadband output beam by imposing a frequency modulated bandwidth on the laser beam. A grating provides spatial and angular spectral dispersion of the beam. Due to the phase modulation, the frequencies ("colors") cycle across the beam. The dispersed beam may be amplified and frequency converted (e.g., tripled) in a plurality of beam lines. A distributed phase plate (DPP) in each line is irradiated by the spectrally dispersed beam and the beam is focused on the target where a smooth (uniform intensity) pattern is produced. The color cycling enhances smoothing and the use of a frequency modulated laser pulse prevents the formation of high intensity spikes which could damage the laser medium in the power amplifiers.

  12. Photovoltaic receivers for laser beamed power in space

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    1991-01-01

    There has recently been a resurgence of interest in the use of beamed power to support space exploration activities. One of the most promising beamed power concepts uses a laser beam to transmit power to a remote photovoltaic array. Large lasers can be located on cloud-free sites at one or more ground locations and illuminate solar arrays to a level sufficient to provide operating power. Issues involved in providing photovoltaic receivers for such applications are discussed.

  13. Hole-boring through clouds for laser power beaming

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lipinski, R.J.; Walter, R.F.

    Power beaming to satellites with a ground-based laser can be limited by clouds. Hole-boring through the clouds with a laser has been proposed as a way to overcome this obstacle. This paper reviews the past work on laser hole-boring and concludes that hole-boring for direct beaming to satellites is likely to require 10--100 MW. However, it may be possible to use an airborne relay mirror at 10--25 km altitude for some applications in order to extend the range of the laser (e.g., for beaming to satellites near the horizon). In these cases, use of the relay mirror also would allowmore » a narrow beam between the laser and the relay, as well as the possibility of reducing the crosswind if the plane matched speed with the cloud temporarily. Under these conditions, the power requirement to bore a hole through most cirrus and cirrostratus clouds might be only 500-kW if the hole is less than 1 m in diameter and if the crosswind speed is less than 10 m/s. Overcoming cirrus and cirrostratus clouds would reduce the downtime due to weather by a factor of 2. However, 500 kW is a large laser, and it may be more effective instead to establish a second power beaming site in a separate weather zone. An assessment of optimum wavelengths for hole boring also was made, and the best options were found to be 3.0--3.4 {mu}m and above 10 {mu}m.« less

  14. High power tube solid-state laser with zigzag propagation of pump and laser beam

    NASA Astrophysics Data System (ADS)

    Savich, Michael

    2015-02-01

    A novel resonator and pumping design with zigzag propagation of pumping and laser beams permits to design an improved tube Solid State Laser (SSL), solving the problem of short absorption path to produce a high power laser beam (100 - 1000kW). The novel design provides an amplifier module and laser oscillator. The tube-shaped SSL includes a gain element fiber-optically coupled to a pumping source. The fiber optic coupling facilitates light entry at compound Brewster's angle of incidence into the laser gain element and uses internal reflection to follow a "zigzag" path in a generally spiral direction along the length of the tube. Optics are arranged for zigzag propagation of the laser beam, while the cryogenic cooling system is traditional. The novel method of lasing uses advantages of cylindrical geometry to reach the high volume of gain medium with compactness and structural rigidity, attain high pump density and uniformity, and reach a low threshold without excessive increase of the temperature of the crystal. The design minimizes thermal lensing and stress effects, and provides high gain amplification, high power extraction from lasing medium, high pumping and lasing efficiency and a high beam quality.

  15. Spatial Combining of Laser-Diode Beams for Pumping an NPRO

    NASA Technical Reports Server (NTRS)

    Gelsinger, Paul; Liu, Duncan; Mulder, Jerry; Aguayo, Francisco

    2008-01-01

    A free-space optical beam combiner now undergoing development makes it possible to use the outputs of multiple multimode laser diodes to pump a neodymium-doped yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, a 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 in this article, 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. To minimize coupling loss, one must ensure that the NA (approximately equal to 0.3) of the combined laser-diode beams is less than the NA of the fiber. The A(Omega) of the laser-diode beam in the slow-axis plane is 1/1.3 as large as that of the fiber. This A(Omega) is small enough to enable efficient coupling of light into the optical fiber, but too large for combining of beams in the slow-axis plane. Therefore, a pair of cylindrical lenses is used to cancel the slow-axis plane magnification introduced by the on-cylindrical lenses used to effect magnification in the fast-axis plane.

  16. Beam-guidance optics for high-power fiber laser systems

    NASA Astrophysics Data System (ADS)

    Mohring, Bernd; Tassini, Leonardo; Protz, Rudolf; Zoz, Jürgen

    2013-05-01

    The realization of a high-energy laser weapon system by coupling a large number of industrial high-power fiber lasers is investigated. To perform the combination of the individual beams of the different fiber lasers within the optical path of the laser weapon, a special optical set-up is used. Each optical component is realized either as reflective component oras refractive optics. Both possibilities were investigated by simulations and experiments. From the results, the general aspects for the layout of the beam-guidance optics for a high-power fiber laser system are derived.

  17. Automated translating beam profiler for in situ laser beam spot-size and focal position measurements

    NASA Astrophysics Data System (ADS)

    Keaveney, James

    2018-03-01

    We present a simple and convenient, high-resolution solution for automated laser-beam profiling with axial translation. The device is based on a Raspberry Pi computer, Pi Noir CMOS camera, stepper motor, and commercial translation stage. We also provide software to run the device. The CMOS sensor is sensitive over a large wavelength range between 300 and 1100 nm and can be translated over 25 mm along the beam axis. The sensor head can be reversed without changing its axial position, allowing for a quantitative estimate of beam overlap with counter-propagating laser beams. Although not limited to this application, the intended use for this device is the automated measurement of the focal position and spot-size of a Gaussian laser beam. We present example data of one such measurement to illustrate device performance.

  18. Automated translating beam profiler for in situ laser beam spot-size and focal position measurements.

    PubMed

    Keaveney, James

    2018-03-01

    We present a simple and convenient, high-resolution solution for automated laser-beam profiling with axial translation. The device is based on a Raspberry Pi computer, Pi Noir CMOS camera, stepper motor, and commercial translation stage. We also provide software to run the device. The CMOS sensor is sensitive over a large wavelength range between 300 and 1100 nm and can be translated over 25 mm along the beam axis. The sensor head can be reversed without changing its axial position, allowing for a quantitative estimate of beam overlap with counter-propagating laser beams. Although not limited to this application, the intended use for this device is the automated measurement of the focal position and spot-size of a Gaussian laser beam. We present example data of one such measurement to illustrate device performance.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed

    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.

  1. Ground-Based and Space-Based Laser Beam Power Applications

    NASA Technical Reports Server (NTRS)

    Bozek, John M.

    1995-01-01

    A space power system based on laser beam power is sized to reduce mass, increase operational capabilities, and reduce complexity. The advantages of laser systems over solar-based systems are compared as a function of application. Power produced from the conversion of a laser beam that has been generated on the Earth's surface and beamed into cislunar space resulted in decreased round-trip time for Earth satellite electric propulsion tugs and a substantial landed mass savings for a lunar surface mission. The mass of a space-based laser system (generator in space and receiver near user) that beams down to an extraterrestrial airplane, orbiting spacecraft, surface outpost, or rover is calculated and compared to a solar system. In general, the advantage of low mass for these space-based laser systems is limited to high solar eclipse time missions at distances inside Jupiter. The power system mass is less in a continuously moving Mars rover or surface outpost using space-based laser technology than in a comparable solar-based power system, but only during dust storm conditions. Even at large distances for the Sun, the user-site portion of a space-based laser power system (e.g., the laser receiver component) is substantially less massive than a solar-based system with requisite on-board electrochemical energy storage.

  2. Differential correction system of laser beam directional dithering based on symmetrical beamsplitter

    NASA Astrophysics Data System (ADS)

    Hongwei, Yang; Wei, Tao; Xiaoqia, Yin; Hui, Zhao

    2018-02-01

    This paper proposes a differential correction system with a differential optical path and a symmetrical beamsplitter for correcting the directional dithering of the laser beams. This system can split a collimated laser beam into two laser beams with equal and opposite movements. Thus, the positional averages of the two split laser beams remain constant irrespective of the dithering angle. The symmetrical beamsplitter designed based on transfer matrix principle is to balance the optical paths and irradiances of the two laser beams. Experimental results show that the directional dithering is reduced to less than one-pixel value. Finally, two examples show that this system can be widely used in one-dimensional measurement.

  3. Reflective diffractive beam splitter for laser interferometers.

    PubMed

    Fahr, Stephan; Clausnitzer, Tina; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2007-08-20

    The first realization of a reflective 50/50 beam splitter based on a dielectric diffraction grating suitable for high-power laser interferometers is reported. The beam splitter is designed to operate at a wavelength of 1064 nm and in s polarization. To minimize the performance degradation of the device that is due to fabrication fluctuations, during the design process special attention was paid to achieve high fabrication tolerances especially of groove width and depth. Applying this beam splitter to high-power laser interferometers, such as future gravitational wave detectors, will avoid critical thermal lensing effects and allow for the free choice of substrate materials.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oxley, Paul; Wihbey, Joseph

    2016-09-15

    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 lasermore » 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{sup −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 × 10{sup 4} atoms cm{sup −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.« less

  5. Turbulence-induced persistence in laser beam wandering.

    PubMed

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

    2015-07-01

    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.

  6. Compact laser transmitter delivering a long-range infrared beam aligned with a monitoring visible beam.

    PubMed

    Lee, Hong-Shik; Kim, Haeng-In; Lee, Sang-Shin

    2012-06-10

    A compact laser transmitter, which takes advantage of an optical subassembly module, was proposed and demonstrated, providing precisely aligned collinear IR and visible beams. The collimated IR beam acts as a long-range projectile for simulated combat, carrying an optical pulsed signal, whereas the visible beam plays the role of tracking the IR beam. The proposed laser transmitter utilizes IR (λ(1)=905 nm) and visible (λ(2)=660 nm) light sources, a fiber-optic collimator, and a beam combiner, which includes a wavelength division multiplexing (WDM) filter in conjunction with optical fiber. The device was built via the laser welding technique and then evaluated by investigating the characteristics of the generated light beams. The IR collimated beam produced had a Gaussian profile and a divergence angle of ~1.3 mrad, and the visible monitoring beam was appropriately collimated to be readily discernible in the vicinity of the transmitter. The two beams were highly aligned within an angle of 0.004 deg as anticipated. Finally, we performed a practical outdoor field test to assess the IR beam with the help of a receiver. An effective trajectory was observed ranging up to 660 m with an overall detectable beam width of ~60 cm.

  7. Electron beam, laser beam and plasma arc welding studies

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

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

    PubMed

    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.

  9. Sodern development of a high LIDT laser beam expander for ATLID

    NASA Astrophysics Data System (ADS)

    Battarel, Denis C.; Barnasson, Elodie

    2017-11-01

    Sodern has been contracted for the development of the laser beam expander used on the lidar of the ATLID instrument developed by Airbus Defence & Space France and Germany (Formerly ASTRIUM) embarked on the EathCARE satellite, element of the ESA (European Space Agency) Living Planet Programme. The ATLID emission beam expander (E-BEX) has two functions: one is to reduce the divergence of the laser in order to achieve a high spatial resolution and the other is to enlarge the laser beam to reduce the power density and thus reduce Laser Induced Contamination (LIC) and Laser Induced Damage Threshold (LIDT) effects on the outer surface exposed to vacuum. This paper exposes the design drivers of the beam expander which are: having optical components withstanding very high laser fluence at a wavelength of 355nm and exhibiting a very low depolarization ratio., hermetically sealing the cavity with metallic gaskets in order to keep the pressure constant so that beam collimation is not affected, choosing housing material compatible with both hermiticity requirements and thermal control. To obtain a high spatial resolution on Earth, ATLID requires a means for controlling beam collimation. This is ensured by an active thermal control on the beam expander in order to change its Wavefront Error (WFE) by a few tens of nanometers.

  10. Fully utilizing high power diode lasers by synergizing diode laser light sources and beam shaping micro-optics

    NASA Astrophysics Data System (ADS)

    Fan, Yingmin; Wang, Jingwei; Cai, Lei; Mitra, Thomas; Hauschild, Dirk; Zah, Chung-En; Liu, Xingsheng

    2018-02-01

    High power diode lasers (HPDLs) offer the highest wall-plug efficiency, highest specific power (power-to-weight ratio), arguably the lowest cost and highest reliability among all laser types. However, the poor beam quality of commercially HPDLs is the main bottleneck limiting their direct applications requiring high brightness at least in one dimension. In order to expand the applications of HPDLs, beam shaping and optical design are essential. In this work, we report the recent progresses on maximizing applications of HPDLs by synergizing diode laser light source and beam shaping micro-optics. Successful examples of matching of diode laser light sources and beam shaping micro-optics driving new applications are presented.

  11. Beam shaping for laser initiated optical primers

    NASA Astrophysics Data System (ADS)

    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.

  12. Apparatus and method for increasing the bandwidth of a laser beam

    DOEpatents

    Chaffee, Paul H.

    1991-01-01

    A method and apparatus is disclosed that provides a laser output beam having a broad bandwidth and an intensity smooth over time. The bandwidth of the laser output can be varied easily by varying the intensity of a broadband source. The present invention includes an optical modulation apparatus comprising a narrowband laser that outputs a horizontally polarized beam (a "signal beam") and a broadband laser that outputs a vertically polarized beam (a "pump beam") whose intensity varies rapidly. The two beam are coupled into a birefringent laser material so that the respective polarizations coincide with the principal axes of the material. As the two beams travel through the material, the polarization preserving properties of the birefringent material maintain the respective polarizations of the two beam; however there is coupling between the two beams as a result of cross phase modulations, which induces a bandwidth change of the signal beam. The amount of bandwidth change is dependent upon the average intensity of the pump beam. The beams are coupled out from the birefringent material and the modulated signal beam is separated by a polarization selector. The modulated signal beam now has a wider bandwidth, and its shape remains smooth in time. This signal beam can be applied to incoherence inducing systems. The different bandwidths required by these different incoherence inducing systems can be obtained by varying the intensity of the pump beam. The United States Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

  13. Statistical spatial properties of speckle patterns generated by multiple laser beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Le Cain, A.; Sajer, J. M.; Riazuelo, G.

    2011-08-15

    This paper investigates hot spot characteristics generated by the superposition of multiple laser beams. First, properties of speckle statistics are studied in the context of only one laser beam by computing the autocorrelation function. The case of multiple laser beams is then considered. In certain conditions, it is shown that speckles have an ellipsoidal shape. Analytical expressions of hot spot radii generated by multiple laser beams are derived and compared to numerical estimates made from the autocorrelation function. They are also compared to numerical simulations performed within the paraxial approximation. Excellent agreement is found for the speckle width as wellmore » as for the speckle length. Application to the speckle patterns generated in the Laser MegaJoule configuration in the zone where all the beams overlap is presented. Influence of polarization on the size of the speckles as well as on their abundance is studied.« less

  14. Laser Beam Filtration for High Spatial Resolution MALDI Imaging Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zavalin, Andre; Yang, Junhai; Caprioli, Richard

    2013-07-01

    We describe an easy and inexpensive way to provide a highly defined Gaussian shaped laser spot on target of 5 μm diameter for imaging mass spectrometry using a commercial MALDI TOF instrument that is designed to produce a 20 μm diameter laser beam on target at its lowest setting. A 25 μm pinhole filter on a swivel arm was installed in the laser beam optics outside the vacuum ion source chamber so it is easily flipped into or out of the beam as desired by the operator. The resulting ion images at 5 μm spatial resolution are sharp since the satellite secondary laser beam maxima have been removed by the filter. Ion images are shown to demonstrate the performance and are compared with the method of oversampling to achieve higher spatial resolution when only a larger laser beam spot on target is available.

  15. Distribution uniformity of laser-accelerated proton beams

    NASA Astrophysics Data System (ADS)

    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)

  16. Electro-optic harmonic conversion to switch a laser beam out of a cavity

    DOEpatents

    Haas, R.A.; Henesian, M.A.

    1984-10-19

    The present invention relates to switching laser beams out of laser cavities, and more particularly, it relates to the use of generating harmonics of the laser beam to accomplish the switching. When laser light is generatd in a laser cavity the problem arises of how to switch the laser light out of the cavity in order to make use of the resulting laser beam in a well known multitude of ways. These uses include range finding, communication, remote sensing, medical surgery, laser fusion applications and many more. The switch-out problem becomes more difficult as the size of the laser aperture grows such as in laser fusion applications. The final amplifier stages of the Nova and Novette lasers at Lawrence Livermore National Laboratory are 46 centimeters with the laser beam expanded to 74 centimeters thereafter. Larger aperture lasers are planned.

  17. Improving the intensity of a focused laser beam

    NASA Astrophysics Data System (ADS)

    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.

  18. Higher-order vector beams produced by photonic-crystal lasers.

    PubMed

    Iwahashi, Seita; Kurosaka, Yoshitaka; Sakai, Kyosuke; Kitamura, Kyoko; Takayama, Naoki; Noda, Susumu

    2011-06-20

    We have successfully generated vector beams with higher-order polarization states using photonic-crystal lasers. We have analyzed and designed lattice structures that provide cavity modes with different symmetries. Fabricated devices based on these lattice structures produced doughnut-shaped vector beams, with symmetries corresponding to the cavity modes. Our study enables the systematic analysis of vector beams, which we expect will lead to applications such as high-resolution microscopy, laser processing, and optical trapping.

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

    PubMed

    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.

  20. Coupling efficiency of laser beam to multimode fiber

    NASA Astrophysics Data System (ADS)

    Niu, Jinfu; Xu, Jianqiu

    2007-06-01

    The coupling efficiency of laser beam to multimode fiber is given by geometrical optics, and the relation between the maximum coupling efficiency and the beam propagation factor M2 is analyzed. An equivalent factor MF2 for the multimode fiber is introduced to characterize the fiber coupling capability. The coupling efficiency of laser beam to multimode fiber is calculated in respect of the ratio M2/MF2 by the overlapping integral theory. The optimal coupling efficiency can be roughly estimated by the ratio of M2 to MF2 but with a large error range. The deviation comes from the lacks of information on the detail of phase and intensity profile in the beam factor M2.

  1. Aerosol beam-focus laser-induced plasma spectrometer device

    DOEpatents

    Cheng, Meng-Dawn

    2002-01-01

    An apparatus for detecting elements in an aerosol includes an aerosol beam focuser for concentrating aerosol into an aerosol beam; a laser for directing a laser beam into the aerosol beam to form a plasma; a detection device that detects a wavelength of a light emission caused by the formation of the plasma. The detection device can be a spectrometer having at least one grating and a gated intensified charge-coupled device. The apparatus may also include a processor that correlates the wavelength of the light emission caused by the formation of the plasma with an identity of an element that corresponds to the wavelength. Furthermore, the apparatus can also include an aerosol generator for forming an aerosol beam from bulk materials. A method for detecting elements in an aerosol is also disclosed.

  2. Full color laser projection display using Kr-Ar laser (white laser) beam-scanning technology

    NASA Astrophysics Data System (ADS)

    Kim, Yonghoon; Lee, Hang W.; Cha, Seungnam; Lee, Jin-Ho; Park, Youngjun; Park, Jungho; Hong, Sung S.; Hwang, Young M.

    1997-07-01

    Full color laser projection display is realized on the large screen using a krypton-argon laser (white laser) as a light source, and acousto-optic devices as light modulators. The main wavelengths of red, green and blue color are 647, 515, and 488 nm separated by dichroic mirrors which are designed to obtain the best performance for the s-polarized beam with the 45 degree incident angle. The separated beams are modulated by three acousto-optic modulators driven by rf drivers which has energy level of 1 watt at 144 MHz and recombined by dichroic mirrors again. Acousto-optic modulators (AOM) are fabricated to satisfy high diffraction efficiency over 80% and fast rising time less than 50 ns at the video bandwidth of 5 MHz. The recombined three beams (RGB) are scanned by polygonal mirrors for horizontal lines and a galvanometer for vertical lines. The photodiode detection for monitoring of rotary polygonal mirrors is adopted in this system for the compensation of the tolerance in the mechanical scanning to prevent the image joggling in the horizontal direction. The laser projection display system described in this paper is expected to apply HDTV from the exploitation of the acousto- optic modulator with the video bandwidth of 30 MHz.

  3. Property Investigation of Laser Cladded, Laser Melted and Electron Beam Melted Ti-Al6-V4

    DTIC Science & Technology

    2006-05-01

    UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Figure 3: Examples of electron beam melted net shape parts; powder bed [3]. 1.4 Laser Cladding ...description, www.arcam.com. [4] K.-H. Hermann, S. Orban, S. Nowotny, Laser Cladding of Titanium Alloy Ti6242 to Restore Damaged Blades, Proceedings...Property Investigation of Laser Cladded , Laser Melted and Electron Beam Melted Ti-Al6-V4 Johannes Vlcek EADS Deutschland GmbH Corporate Research

  4. Conceptual development of the Laser Beam Manifold (LBM)

    NASA Technical Reports Server (NTRS)

    Campbell, W.; Owen, R. B.

    1979-01-01

    The laser beam manifold, a device for transforming a single, narrow, collimated beam of light into several beams of desired intensity ratios is described. The device consists of a single optical substrate with a metallic coating on both optical surfaces. By changing the entry point, the number of outgoing beams can be varied.

  5. Phoenix Laser Beam in Action on Mars

    NASA Image and Video Library

    2008-09-30

    The Surface Stereo Imager camera aboard NASA 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.

  6. Advanced chemical oxygen iodine lasers for novel beam generation

    NASA Astrophysics Data System (ADS)

    Wu, Kenan; Zhao, Tianliang; Huai, Ying; Jin, Yuqi

    2018-03-01

    Chemical oxygen iodine laser, or COIL, is an impressive type of chemical laser that emits high power beam with good atmospheric transmissivity. Chemical oxygen iodine lasers with continuous-wave plane wave output are well-developed and are widely adopted in directed energy systems in the past several decades. Approaches of generating novel output beam based on chemical oxygen iodine lasers are explored in the current study. Since sophisticated physical processes including supersonic flowing of gaseous active media, chemical reacting of various species, optical power amplification, as well as thermal deformation and vibration of mirrors take place in the operation of COIL, a multi-disciplinary model is developed for tracing the interacting mechanisms and evaluating the performance of the proposed laser architectures. Pulsed output mode with repetition rate as high as hundreds of kHz, pulsed output mode with low repetition rate and high pulse energy, as well as novel beam with vector or vortex feature can be obtained. The results suggest potential approaches for expanding the applicability of chemical oxygen iodine lasers.

  7. Optical Device for Converting a Laser Beam into Two Co-aligned but Oppositely Directed Beams

    NASA Technical Reports Server (NTRS)

    Jennings, Donald

    2013-01-01

    Optical systems consisting of a series of optical elements require alignment from the input end to the output end. The optical elements can be mirrors, lenses, sources, detectors, or other devices. Complex optical systems are often difficult to align from end-to-end because the alignment beam must be inserted at one end in order for the beam to traverse the entire optical path to the other end. The ends of the optical train may not be easily accessible to the alignment beam. Typically, when a series of optical elements is to be aligned, an alignment laser beam is inserted into the optical path with a pick-off mirror at one end of the series of elements. But it may be impossible to insert the beam at an end-point. It can be difficult to locate the pick-off mirror at the desired position because there is not enough space, there is no mounting surface, or the location is occupied by a source, detector, or other component. Alternatively, the laser beam might be inserted at an intermediate location (not at an end-point) and sent, first in one direction and then the other, to the opposite ends of the optical system for alignment. However, in this case, alignment must be performed in two directions and extra effort is required to co-align the two beams to make them parallel and coincident, i.e., to follow the same path as an end-to-end beam. An optical device has been developed that accepts a laser beam as input and produces two co-aligned, but counter-propagating beams. In contrast to a conventional alignment laser placed at one end of the optical path, this invention can be placed at a convenient position within the optical train and aligned to send its two beams simultaneously along precisely opposite paths that, taken together, trace out exactly the same path as the conventional alignment laser. This invention allows the user the freedom to choose locations within the optical train for placement of the alignment beam. It is also self-aligned by design and requires

  8. Stable donutlike vortex beam generation from lasers with controlled Ince-Gaussian modes

    NASA Astrophysics Data System (ADS)

    Chu, Shu-Chun; Otsuka, Kenju

    2007-11-01

    This study proposes a three-lens configuration for generating a stable donutlike vortex laser beam with controlled Ince-Gaussian mode (IGM) operation in the model of laser-diode (LD)-pumped solid-state lasers. Simply controlling the lateral off-axis position of the pump beam's focus on the laser crystal can generate a desired donutlike vortex beam from the proposed simple and easily made three-lens configuration, a proposed astigmatic mode converter assembled into one body with a concave-convex laser cavity.

  9. Enhanced tunable narrow-band THz emission from laser-modulated electron beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xiang, D.; Stupakov, G.; /SLAC

    2009-06-19

    We propose and analyze a scheme to generate enhanced narrow-band terahertz (THz) radiation through down-conversion of the frequency of optical lasers using laser-modulated electron beams. In the scheme the electron beam is first energy modulated by two lasers with wave numbers k{sub 1} and k2, respectively. After passing through a dispersion section, the energy modulation is converted to density modulation. Due to the nonlinear conversion process, the beam will have density modulation at wave number k = nk{sub 1} + mk{sub 2}, where n and m are positive or negative integers. By properly choosing the parameters for the lasers andmore » dispersion section, one can generate density modulation at THz frequency in the beam using optical lasers. This density-modulated beam can be used to generate powerful narrow-band THz radiation. Since the THz radiation is in tight synchronization with the lasers, it should provide a high temporal resolution for the optical-pump THz-probe experiments. The central frequency of the THz radiation can be easily tuned by varying the wavelength of the two lasers and the energy chirp of the electron beam. The proposed scheme is in principle able to generate intense narrow-band THz radiation covering the whole THz range and offers a promising way towards the tunable intense narrow-band THz sources.« less

  10. Beam conditioner for free electron lasers and synchrotrons

    DOEpatents

    Liu, H.; Neil, G.R.

    1998-09-08

    A focused optical has been used to introduce an optical pulse, or electromagnetic wave, collinear with the electron beam in a free electron laser or synchrotron thereby adding an axial field component that accelerates the electrons on the radial outside of the distribution of electrons in the electron beam. This invention consists of using the axial electrical component of a TEM{sub 10} mode Gaussian beam in vacuum to condition the electron beam and speed up the outer electrons in the beam. The conditioning beam should possess about the same diameter as the electron beam. The beam waist of the conditioning wave must be located around the entrance of the undulator longitudinally to have a net energy exchange between the electrons in the outer part of the distribution and the conditioning wave owing to the natural divergence of a Gaussian beam. By accelerating the outer electrons, the outer and core electrons are caused to stay in phase. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron. 4 figs.

  11. Beam conditioner for free electron lasers and synchrotrons

    DOEpatents

    Liu, Hongxiu; Neil, George R.

    1998-01-01

    A focused optical is been used to introduce an optical pulse, or electromagnetic wave, colinearly with the electron beam in a free electron laser or synchrotron thereby adding an axial field component that accelerates the electrons on the radial outside of the distribution of electrons in the electron beam. This invention consists of using the axial electrical component of a TEM.sub.10 mode Gaussian beam in vacuum to condition the electron beam and speed up the outer electrons in the beam. The conditioning beam should possess about the same diameter as the electron beam. The beam waist of the conditioning wave must be located around the entrance of the undulator longitudinally to have a net energy exchange between the electrons in the outer part of the distribution and the conditioning wave owing to the natural divergence of a Gaussian beam. By accelerating the outer electrons, the outer and core electrons are caused to stay in phase. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron.

  12. Electronic-beam analysis of excimer lasers used for photorefractive keratotomy

    NASA Astrophysics Data System (ADS)

    Roundy, Carlos B.

    1998-07-01

    Excimer lasers are an excellent instrument for performing photorefractive keratotomy, PRK. The UV light from the laser causes an ablation of the cornea in proportion to the intensity of the light. The primary characteristic essential to successful PRK is the uniformity of the Top Hat, or working portion of the laser beam. In order for this intensity profile to be sufficiently uniform for PRK, it is essential to periodically measure the equality of the laser beam profile. This ensures that the laser continues to operate properly and provide the expected performance.

  13. Using harmonic oscillators to determine the spot size of Hermite-Gaussian laser beams

    NASA Technical Reports Server (NTRS)

    Steely, Sidney L.

    1993-01-01

    The similarity of the functional forms of quantum mechanical harmonic oscillators and the modes of Hermite-Gaussian laser beams is illustrated. This functional similarity provides a direct correlation to investigate the spot size of large-order mode Hermite-Gaussian laser beams. The classical limits of a corresponding two-dimensional harmonic oscillator provide a definition of the spot size of Hermite-Gaussian laser beams. The classical limits of the harmonic oscillator provide integration limits for the photon probability densities of the laser beam modes to determine the fraction of photons detected therein. Mathematica is used to integrate the probability densities for large-order beam modes and to illustrate the functional similarities. The probabilities of detecting photons within the classical limits of Hermite-Gaussian laser beams asymptotically approach unity in the limit of large-order modes, in agreement with the Correspondence Principle. The classical limits for large-order modes include all of the nodes for Hermite Gaussian laser beams; Sturm's theorem provides a direct proof.

  14. Beam by design: Laser manipulation of electrons in modern accelerators

    NASA Astrophysics Data System (ADS)

    Hemsing, Erik; Stupakov, Gennady; Xiang, Dao; Zholents, Alexander

    2014-07-01

    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, 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 are reviewed. Basic theories of electron-laser interactions, techniques to create microstructures and nanostructures in electron beams, and techniques to produce radiation with customizable waveforms are reviewed. An overview of laser-based techniques for the generation of fully coherent x rays, mode-locked x-ray pulse trains, light with orbital angular momentum, and attosecond or even zeptosecond long coherent pulses in free-electron lasers is presented. Several methods to generate femtosecond pulses in storage rings are also discussed. Additionally, various schemes designed to enhance the performance of light sources through precision beam preparation including beam conditioning, laser heating, emittance exchange, and various laser-based diagnostics are described. Together these techniques represent a new emerging concept of "beam by design" in modern accelerators, which is the primary focus of this article.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Metzkes, J.; Rehwald, M.; Obst, L.

    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 energymore » 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.« less

  16. Spatial Control of Laser Wakefield Accelerated Electron Beams

    NASA Astrophysics Data System (ADS)

    Maksimchuk, A.; Behm, K.; Zhao, T.; Joglekar, A. S.; Hussein, A.; Nees, J.; Thomas, A. G. R.; Krushelnick, K.; Elle, J.; Lucero, A.; Samarin, G. M.; Sarry, G.; Warwick, J.

    2017-10-01

    The laser wakefield experiments to study and control spatial properties of electron beams were performed using HERCULES laser at the University of Michigan at power of 100 TW. In the first experiment multi-electron beam generation was demonstrated using co-propagating, parallel laser beams with a π-phase shift mirror and showing that interaction between the wakefields can cause injection to occur for plasma and laser parameters in which a single wakefield displays no significant injection. In the second experiment a magnetic triplet quadrupole system was used to refocus and stabilize electron beams at the distance of 60 cm from the interaction region. This produced a 10-fold increase in remote gamma-ray activation of 63Cu using a lead converter. In the third experiment measurements of un-trapped electrons with high transverse momentum produce a 500 mrad (FWHM) ring. This ring is formed by electrons that receive a forward momentum boost by traversing behind the bubble and its size is inversely proportional to the plasma density. The characterization of divergence and charge of this electron ring may reveal information about the wakefield structure and trapping potential. Supported by U.S. Department of Energy and the National Nuclear Security Administration and Air Force Office of Scientific Research.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. High efficiency laser-assisted H - charge exchange for microsecond duration beams

    DOE PAGES

    Cousineau, Sarah; Rakhman, Abdurahim; Kay, Martin; ...

    2017-12-26

    Laser-assisted stripping is a novel approach to H - charge exchange that overcomes long-standing limitations associated with the traditional, foil-based method of producing high-intensity, time-structured beams of protons. This paper reports on the first successful demonstration of the laser stripping technique for microsecond duration beams. The experiment represents a factor of 1000 increase in the stripped pulse duration compared with the previous proof-of-principle demonstration. The central theme of the experiment is the implementation of methods to reduce the required average laser power such that high efficiency stripping can be accomplished for microsecond duration beams using conventional laser technology. In conclusion,more » the experiment was performed on the Spallation Neutron Source 1 GeV H - beam using a 1 MW peak power UV laser and resulted in ~95% stripping efficiency.« less

  19. High efficiency laser-assisted H - charge exchange for microsecond duration beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cousineau, Sarah; Rakhman, Abdurahim; Kay, Martin

    Laser-assisted stripping is a novel approach to H - charge exchange that overcomes long-standing limitations associated with the traditional, foil-based method of producing high-intensity, time-structured beams of protons. This paper reports on the first successful demonstration of the laser stripping technique for microsecond duration beams. The experiment represents a factor of 1000 increase in the stripped pulse duration compared with the previous proof-of-principle demonstration. The central theme of the experiment is the implementation of methods to reduce the required average laser power such that high efficiency stripping can be accomplished for microsecond duration beams using conventional laser technology. In conclusion,more » the experiment was performed on the Spallation Neutron Source 1 GeV H - beam using a 1 MW peak power UV laser and resulted in ~95% stripping efficiency.« less

  20. Electro-optic harmonic conversion to switch a laser beam out of a cavity

    DOEpatents

    Haas, Roger A.; Henesian, Mark A.

    1987-01-01

    The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.

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

    PubMed Central

    Hofmann, Kerstin M; Schell, Stefan; Wilkens, Jan J

    2012-01-01

    Abstract Laser-accelerated particles are a promising option for radiation therapy of cancer by potentially combining a compact, cost-efficient treatment unit with the physical advantages of charged particle beams. To design such a treatment unit we consider different dose delivery schemes and analyze the necessary devices in the required particle beam line for each case. Furthermore, we point out that laser-driven treatment units may be ideal tools for motion adaptation during radiotherapy. Reasons for this are the potential of a flexible gantry and the time structure of the beam with high particle numbers in ultrashort bunches. One challenge that needs to be addressed is the secondary radiation produced in several beam line elements. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) PMID:22930653

  2. Efficiency of laser beam utilization in gas laser cutting of materials

    NASA Astrophysics Data System (ADS)

    Galushkin, M. G.; Grishaev, R. V.

    2018-02-01

    Relying on the condition of dynamic matching of the process parameters in gas laser cutting, the dependence of the beam utilization factor on the cutting speed and the beam power has been determined. An energy balance equation has been derived for a wide range of cutting speed values.

  3. Note: Laser beam scanning using a ferroelectric liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Das, Abhijit; Boruah, Bosanta R.

    2014-04-01

    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.

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

    PubMed

    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.

  5. Electron-Beam Recombination Lasers

    NASA Astrophysics Data System (ADS)

    Rhoades, Robert Lewis

    1992-01-01

    The first known instance of electron-beam pumping of the 546.1 nm mercury laser is reported. This has been achieved using high-energy electrons to create intense ionization in a coaxial diode chamber containing a mixture of noble gases with a small amount of mercury vapor. Also reported are the results of a study of the 585.3 nm neon laser in He:Ne:Ar mixtures under similar experimental conditions. Both of these lasers are believed to be predominantly pumped by recombination. For the mercury laser, kinetic processes in the partially ionized plasma following the excitation pulse of high-energy electrons should favor the production of atomic mercury ions and molecular ions containing mercury. Subsequent recombination with electrons heavily favors the production of the 7^3S and 6^3 D states of Hg, of which 7^3S is the upper level of the reported laser. For the neon laser, the dominant recombining ion has been previously shown to be Ne_2^{+}. One of the dominant roles of helium in recombination lasers is inferred from the data for the neon laser at low helium concentrations. Helium appears to be necessary for the rapid relaxation of the electron energy which then increases the reaction rates for all known recombination processes thus increasing the pump rate into the upper state.

  6. Laser Beam Propagation in Inertial Confinement Plasmas*

    NASA Astrophysics Data System (ADS)

    Froula, Dustin

    2006-10-01

    A study of the relevant laser-plasma interaction processes in a long-scale length high-temperature transparent plasma has been performed using a new target platform to emulate the plasma conditions in an indirect drive fusion target. Recent experiments in this plasma emulator have demonstrated that for ignition relevant conditions (Te>3 keV, I < 2x10^15 W-cm-2) the 3φ laser light propagates through a high-density (5x10^20 cm-3) plasma with a peak transmission of 90%. Experiments have demonstrated an understanding of filamentation in these conditions that is consistent with theory increasing our confidence in our ability to execute the beam conditioning and focal spot designs for future ignition experiments. This target has been well characterized using Thomson-scattering where the peak electron temperature is shown to be 3.5 keV. The electron temperature measurements agree with HYDRA flux-limited radiation hydrodynamics calculations. Using a recently implemented 3φ transmitted beam diagnostic, the filamentation threshold has been experimentally measured for a beam that employs a continuous phase plate (CPP). For intensities above the threshold for filamentation, the beam was shown to spray. Defocusing the high-power laser beam reduced the backscatter while filamentation was not changed as predicted. Recent experiments investigating the importance of polarization and temporal smoothing of laser beams for propagation in this target platform will be presented. Detailed hydrodynamic and laser-plasma interaction simulations capture the stimulated Brillouin, stimulated Raman, and filamentation thresholds providing significant confidence that our models used for ignition designs can correctly predict the conditions where energy loss and beam propagation through the under dense NIF hohlraum plasmas will be small. ** Collaborators: L. Divol, S. H. Glenzer, J. S. Ross, N. Meezan, S. Prisbrey, S. Dixit.

  7. On the exploration of effect of critical beam power on the propagation of Gaussian laser beam in collisionless magnetized plasma

    NASA Astrophysics Data System (ADS)

    Urunkar, T. U.; Valkunde, A. T.; Vhanmore, B. D.; Gavade, K. M.; Patil, S. D.; Takale, M. V.

    2018-05-01

    It is quite known that critical power of the laser plays vital role in the propagation of Gaussian laser beam in collisionless plasma. The nonlinearity in dielectric constant considered herein is due to the ponderomotive force. In the present analysis, the interval of critical beam power has been explored to sustain the competition between diffraction and self-focusing of Gaussian laser beam during propagation in collisionless magnetized plasma. Differential equation for beam-width parameter has been established by using WKB and paraxial approximations under parabolic equation approach. The effect of critical power on the propagation of Gaussian laser beam has been presented graphically and discussed.

  8. Rippled beam free electron laser amplifier

    DOEpatents

    Carlsten, Bruce E.

    1999-01-01

    A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

  9. Using an intense laser beam in interaction with muon/electron beam to probe the noncommutative QED

    NASA Astrophysics Data System (ADS)

    Tizchang, S.; Batebi, S.; Haghighat, M.; Mohammadi, R.

    2017-02-01

    It is known that the linearly polarized photons can partly transform to circularly polarized ones via forward Compton scattering in a background such as the external magnetic field or noncommutative space time. Based on this fact we explore the effects of the NC-background on the scattering of a linearly polarized laser beam from an intense beam of charged leptons. We show that for a muon/electron beam flux {overline{ɛ}}_{μ, e}˜ 1{0}^{12}/{10}^{10} TeV cm-2 sec-1 and a linearly polarized laser beam with energy k 0 ˜1 eV and average power {overline{P}}_{laser}˜eq 1{0}^3 KW, the generation rate of circularly polarized photons is about R V ˜ 104 /sec for noncommutative energy scale ΛNC ˜ 10 TeV. This is fairly large and can grow for more intense beams in near future.

  10. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    NASA Astrophysics Data System (ADS)

    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.

  11. Laser-driven electron beam and radiation sources for basic, medical and industrial sciences

    PubMed Central

    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. PMID:26062737

  12. Laser-driven electron beam and radiation sources for basic, medical and industrial sciences.

    PubMed

    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.

  13. Apparatus and process for active pulse intensity control of laser beam

    DOEpatents

    Wilcox, Russell B.

    1992-01-01

    An optically controlled laser pulse energy control apparatus and process is disclosed wherein variations in the energy of a portion of the laser beam are used to vary the resistance of a photodetector such as a photoresistor through which a control voltage is fed to a light intensity controlling device through which a second portion of the laser beam passes. Light attenuation means are provided to vary the intensity of the laser light used to control the resistance of the photodetector. An optical delay path is provided through which the second portion of the beam travels before reaching the light intensity controlling device. The control voltage is supplied by a variable power supply. The apparatus may be tuned to properly attenuate the laser beam passing through the intensity controlling device by adjusting the power supply, the optical delay path, or the light attenuating means.

  14. Emittance of positron beams produced in intense laser plasma interaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen Hui; Hazi, A.; Link, A.

    2013-01-15

    The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be usefulmore » as an alternative positron source for future accelerators.« less

  15. Laser ablation of hard tissue: correlation between the laser beam parameters and the post-ablative tissue characteristics

    NASA Astrophysics Data System (ADS)

    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.

  16. VideoBeam portable laser communicator

    NASA Astrophysics Data System (ADS)

    Mecherle, G. Stephen; Holcomb, Terry L.

    1999-01-01

    A VideoBeamTM portable laser communicator has been developed which provides full duplex communication links consisting of high quality analog video and stereo audio. The 3.2-pound unit resembles a binocular-type form factor and has an operational range of over two miles (clear air) with excellent jam-resistance and low probability of interception characteristics. The VideoBeamTM unit is ideally suited for numerous military scenarios, surveillance/espionage, industrial precious mineral exploration, and campus video teleconferencing applications.

  17. Single lens laser beam shaper

    DOEpatents

    Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

    2011-10-04

    A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

  18. Single electron beam rf feedback free electron laser

    DOEpatents

    Brau, C.A.; Stein, W.E.; Rockwood, S.D.

    1981-02-11

    A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

  19. Laser ion source for high brightness heavy ion beam

    DOE PAGES

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. But, 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. Furthermore, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory in 2014. Now most of all the solid based heavy ions are being provided from the laser ion sourcemore » for regular operation.« less

  20. Continuous and pulsed laser high power beam combiner for additive manufacturing applications

    NASA Astrophysics Data System (ADS)

    Bassignana, Marta; Califano, Alessio; Pescarmona, Francesco; Braglia, Andrea; Perrone, Guido

    2018-02-01

    Laser-based additive manufacturing (AM) from metal powders is emerging as the new industrial revolution, although current fabrication approaches still require long mechanical post-processing to improve the final surface quality and meet the design tolerances. To overcome this limitation, the next generation machines are expected to complement laser AM with laser ablation (LA) to implement surface finishing and micro texturing already during the device growth process. With this aim, a new beam combiner to allow the real-time interchange of additive and subtractive processes using the same scanner head has been designed. Extensive tests have been carried out using a 6 kW continuous-wave laser similar to that used for the metal powder fusion and a nanosecond 100W pulsed source similar to that used for laser ablation.

  1. Direct diode lasers with comparable beam quality to fiber, CO2, and solid state lasers

    NASA Astrophysics Data System (ADS)

    Huang, Robin K.; Chann, Bien; Burgess, James; Kaiman, Michael; Overman, Robert; Glenn, John D.; Tayebati, Parviz

    2012-03-01

    TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers.

  2. Intense laser beams; Proceedings of the Meeting, Los Angeles, CA, Jan. 23, 24, 1992

    NASA Technical Reports Server (NTRS)

    Wade, Richard C. (Editor); Ulrich, Peter B. (Editor)

    1992-01-01

    Various papers on intense laser beams are presented. Individual topics addressed include: novel methods of copper vapor laser excitation, UCLA IR FEL, lasing characteristics of a large-bore copper vapor laser (CVL), copper density measurement of a large-bore CVL, high-power XeCl excimer laser, solid state direct-drive circuit for pumping gas lasers, united energy model for FELs, intensity and frequency instabilities in double-mode CO2 lasers, comparison of output power stabilities of CO and CO2 lasers, increasing efficiency of sealed-off CO lasers, thermal effects in singlet delta oxygen generation, optical extraction from the chemical oxygen-iodine laser medium, generation and laser diagnostic analysis of bismuth fluoride. Also discussed are: high-Q resonator design for an HF overtone chemical lasers, improved coatings for HF overtone lasers, scaled atmospheric blooming experiment, simulation on producing conjugate field using deformable mirrors, paraxial theory of amplitude correction, potential capabilities of adaptive optical systems in the atmosphere, power beaming research at NASA, system evaluations of laser power beaming options, performance projections for laser beam power to space, independent assessment of laser power beaming options, removal of atmospheric CFCs by lasers, efficiency of vaporization cutting by CVL.

  3. Scaling laws for positron production in laser-electron beam collisions

    NASA Astrophysics Data System (ADS)

    Blackburn, Tom; Ilderton, Anton; Murphy, Christopher; Marklund, Mattias

    2017-10-01

    Showers of gamma rays and positrons are produced when a multi-GeV electron beam collides with a super-intense laser pulse. All-optical realisation of this geometry, where the electron beam is generated by laser-wakefield acceleration, is currently attracting much experimental interest as a probe of radiation reaction and QED effects. These interactions may be modelled theoretically in the framework of strong-field QED or numerically by large-scale PIC simulation. To complement these, we present analytical scaling laws for the electron beam energy loss, gamma ray spectrum, and the positron yield and energy that are valid in the radiation-reaction-dominated regime. These indicate that by employing the collision of a 2 GeV electron beam with a laser pulse of intensity 5 ×1021Wcm-2 , it is possible to produce 10,000 positrons in a single shot at currently available laser facilities. The authors acknowledge support from the Knut and Alice Wallenberg Foundation.

  4. Full-wave and ray-based modeling of cross-beam energy transfer between laser beams with distributed phase plates and polarization smoothing

    DOE PAGES

    Follett, R. K.; Edgell, D. H.; Froula, D. H.; ...

    2017-10-20

    Radiation-hydrodynamic simulations of inertial confinement fusion (ICF) experiments rely on ray-based cross-beam energy transfer (CBET) models to calculate laser energy deposition. The ray-based models assume locally plane-wave laser beams and polarization averaged incoherence between laser speckles for beams with polarization smoothing. The impact of beam speckle and polarization smoothing on crossbeam energy transfer (CBET) are studied using the 3-D wave-based laser-plasma-interaction code LPSE. The results indicate that ray-based models under predict CBET when the assumption of spatially averaged longitudinal incoherence across the CBET interaction region is violated. A model for CBET between linearly-polarized speckled beams is presented that uses raymore » tracing to solve for the real speckle pattern of the unperturbed laser beams within the eikonal approximation and gives excellent agreement with the wavebased calculations. Lastly, OMEGA-scale 2-D LPSE calculations using ICF relevant plasma conditions suggest that the impact of beam speckle on laser absorption calculations in ICF implosions is small (< 1%).« less

  5. Full-wave and ray-based modeling of cross-beam energy transfer between laser beams with distributed phase plates and polarization smoothing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Follett, R. K.; Edgell, D. H.; Froula, D. H.

    Radiation-hydrodynamic simulations of inertial confinement fusion (ICF) experiments rely on ray-based cross-beam energy transfer (CBET) models to calculate laser energy deposition. The ray-based models assume locally plane-wave laser beams and polarization averaged incoherence between laser speckles for beams with polarization smoothing. The impact of beam speckle and polarization smoothing on crossbeam energy transfer (CBET) are studied using the 3-D wave-based laser-plasma-interaction code LPSE. The results indicate that ray-based models under predict CBET when the assumption of spatially averaged longitudinal incoherence across the CBET interaction region is violated. A model for CBET between linearly-polarized speckled beams is presented that uses raymore » tracing to solve for the real speckle pattern of the unperturbed laser beams within the eikonal approximation and gives excellent agreement with the wavebased calculations. Lastly, OMEGA-scale 2-D LPSE calculations using ICF relevant plasma conditions suggest that the impact of beam speckle on laser absorption calculations in ICF implosions is small (< 1%).« less

  6. Beam delivery system with a non-digitized diffractive beam splitter for laser-drilling of silicon

    NASA Astrophysics Data System (ADS)

    Amako, J.; Fujii, E.

    2016-02-01

    We report a beam-delivery system consisting of a non-digitized diffractive beam splitter and a Fourier transform lens. The system is applied to the deep-drilling of silicon using a nanosecond pulse laser in the manufacture of inkjet printer heads. In this process, a circularly polarized pulse beam is divided into an array of uniform beams, which are then delivered precisely to the process points. To meet these requirements, the splitter was designed to be polarization-independent with an efficiency>95%. The optical elements were assembled so as to allow the fine tuning of the effective overall focal length by adjusting the wavefront curvature of the beam. Using the system, a beam alignment accuracy of<5 μm was achieved for a 12-mm-wide beam array and the throughput was substantially improved (10,000 points on a silicon wafer drilled in ~1 min). This beam-delivery scheme works for a variety of laser applications that require parallel processing.

  7. Wind Tunnel Testing of a One-Dimensional Laser Beam Scanning and Laser Sheet Approach to Shock Sensing

    NASA Technical Reports Server (NTRS)

    Tokars, Roger; Adamovsky, Grigory; Anderson, Robert; Hirt, Stefanie; Huang, John; Floyd, Bertram

    2012-01-01

    A 15- by 15-cm supersonic wind tunnel application of a one-dimensional laser beam scanning approach to shock sensing is presented. The measurement system design allowed easy switching between a focused beam and a laser sheet mode for comparison purposes. The scanning results were compared to images from the tunnel Schlieren imaging system. The tests revealed detectable changes in the laser beam in the presence of shocks. The results lend support to the use of the one-dimensional scanning beam approach for detecting and locating shocks in a flow, but some issues must be addressed in regards to noise and other limitations of the system.

  8. Non-intrusive beam power monitor for high power pulsed or continuous wave lasers

    DOEpatents

    Hawsey, Robert A.; Scudiere, Matthew B.

    1993-01-01

    A system and method for monitoring the output of a laser is provided in which the output of a photodiode disposed in the cavity of the laser is used to provide a correlated indication of the laser power. The photodiode is disposed out of the laser beam to view the extraneous light generated in the laser cavity whose intensity has been found to be a direct correlation of the laser beam output power level. Further, the system provides means for monitoring the phase of the laser output beam relative to a modulated control signal through the photodiode monitor.

  9. Design and development of 24 times high-power laser beam expander

    NASA Astrophysics Data System (ADS)

    Lin, Zhao-heng; Gong, Xiu-ming; Wu, Shi-bin; Tan, Yi; Jing, Hong-wei; Wei, Zhong-wei

    2013-09-01

    As currently, laser calibration, laser radar, laser ranging and the relative field raised up the demand for high magnification laser beam expander. This article intends to introduce a high-energy laser beam expander research and design, large- diameter, wide-band, high-magnification and small obscuration ratio are the main features. By using Cassegrain reflective optical system, this laser beam expander achieves 24 times beam expand, and outgoing effective limiting aperture is Φ600 mm, band scope between 0.45μm to 5μm, single-pulse laser damage threshold greater than 1J/cm2, continuous-wave laser damage threshold greater than 200W/cm2 and obscuration ratio 1:10. Primary mirror underside support uses 9 points float supporting, lateral support mainly depends on mercury belt support and assists by mandrel ball head positioning support. An analyzing base on finite element analysis software ANSYS, and primary mirror deformation status analysis with debug mode and operativemode, when inputs four groups of Angle 170°, 180°, 210° and 240° , mercury belt under each group of angle load-bearing is 65%, 75% , 85% and 100% respectively, totally 16 workingcondition analyze results. At last, the best way to support primary mirror is finalized. Through design of secondary mirror to achieve a five-dimensional precision fine-tune. By assembling and debugging laser beam expander, Zygo interferometer detection system proof image quality (RMS) is 0.043λ (λ=632.8nm), stability (RMS) is 0.007λ (λ=632.8nm), and effective transmission hit 94%, meets the requirements of practical application completely.

  10. Free-electron laser power beaming to satellites at China Lake, California

    NASA Astrophysics Data System (ADS)

    Bennett, Harold E.; Rather, John D.; Montgomery, Edward E.

    1994-05-01

    Laser power beaming of energy through the atmosphere to a satellite can extend its lifetime by maintaining the satellite batteries in operating condition. An alternate propulsion system utilizing power beaming will also significantly reduce the initial insertion cost of these satellites, which now are as high as $72,000/lb for geosynchronous orbit. Elements of the power beaming system are a high-power laser, a large diameter telescope to reduce diffractive losses, an adaptive optic beam conditioning system and possibly a balloon or aerostat carrying a large mirror to redirect the laser beam to low earth orbit satellites after it has traversed most of the earth's atmosphere vertically. China Lake, California has excellent seeing, averages 260 cloud-free days/year, has the second largest geothermal plant in the United States nearby for power, groundwater from the lake for cooling water, and is at the center of one of the largest restricted airspaces in the United States. It is an ideal site for such a laser power beaming system. Technological challenges in building such a system and installing it at China Lake are discussed.

  11. Measurement system with high accuracy for laser beam quality.

    PubMed

    Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

    2015-05-20

    Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%.

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

    PubMed

    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.

  13. Laser beam propagation through a full scale aircraft turboprop engine exhaust

    NASA Astrophysics Data System (ADS)

    Henriksson, Markus; Gustafsson, Ove; Sjöqvist, Lars; Seiffer, Dirk; Wendelstein, Norbert

    2010-10-01

    The exhaust from engines introduces zones of extreme turbulence levels in local environments around aircraft. This may disturb the performance of aircraft mounted optical and laser systems. The turbulence distortion will be especially devastating for optical missile warning and laser based DIRCM systems used to protect manoeuvring aircraft against missile attacks, situations where the optical propagation path may come close to the engine exhaust. To study the extent of the turbulence zones caused by the engine exhaust and the strength of the effects on optical propagation through these zones a joint trial between Germany, the Netherlands, Sweden and the United Kingdom was performed using a medium sized military turboprop transport aircraft tethered to the ground at an airfield. This follows on earlier trials performed on a down-scaled jet-engine test rig. Laser beams were propagated along the axis of the aircraft at different distances relative to the engine exhaust and the spatial beam profiles and intensity scintillations were recorded with cameras and photodiodes. A second laser beam path was directed from underneath the loading ramp diagonally past one of the engines. The laser wavelengths used were 1.5 and 3.6 μm. In addition to spatial beam profile distortions temporal effects were investigated. Measurements were performed at different propeller speeds and at different distances from exhaust nozzle to the laser path. Significant increases in laser beam wander and long term beam radius were observed with the engine running. Corresponding increases were also registered in the scintillation index and the temporal fluctuations of the instantaneous power collected by the detector.

  14. Vertical laser beam propagation through the troposphere

    NASA Technical Reports Server (NTRS)

    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.

  15. Laser-accelerated ion beam diagnostics with TOF detectors for the ELIMED beam line

    NASA Astrophysics Data System (ADS)

    Milluzzo, G.; Scuderi, V.; Amico, A. G.; Borghesi, M.; Cirrone, G. A. P.; Cuttone, G.; De Napoli, M.; Doria, D.; Dostal, J.; Larosa, G.; Leanza, R.; Margarone, D.; Petringa, G.; Pipek, J.; Romagnani, L.; Romano, F.; Schillaci, F.; Velyhan, A.

    2017-02-01

    Laser-accelerated ion beams could represent the future of particle acceleration in several multidisciplinary applications, as for instance medical physics, hadrontherapy and imaging field, being a concrete alternative to old paradigm of acceleration, characterized by huge and complex machines. In this framework, following on from the ELIMED collaboration, launched in 2012 between INFN-LNS and ELI-Beamlines, in 2014 a three-years contract has been signed between the two institutions for the design and the development of a complete transport beam-line for high-energy ion beams (up to 60 MeV) coupled with innovative diagnostics and in-air dosimetry devices. The beam-line will be installed at the ELI-Beamlines facility and will be available for users. The measurement of the beam characteristics, such as energy spectra, angular distributions and dose-rate is mandatory to optimize the transport as well as the beam delivery at the irradiation point. In order to achieve this purpose, the development of appropriate on-line diagnostics devices capable to detect high-pulsed beams with high accuracy, represents a crucial point in the ELIMED beamline development. The diagnostics solution, based on the use of silicon carbide (SiC) and diamond detectors using TOF technique, will be presented together with the preliminary results obtained with laser-accelerated proton beams.

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

    DOE PAGES

    Wu, Chongzhao; Khanal, Sudeep; Reno, John L.; ...

    2016-07-07

    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 that are utilized as nanoscale sources of radiation, 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) thatmore » 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 operation of the DFB lasers. Experimentally, the antenna-feedback method, which does not require the phase matching to a well-defined effective index, is implemented for terahertz QCLs, and single-mode terahertz QCLs with a beam divergence as small as 4°×4° are demonstrated, which is the narrowest beam reported for any terahertz QCL to date. Moreover, in contrast to a negligible radiative field in conventional photonic band-edge lasers, in which the periodicity follows the integer multiple of half-wavelengths inside the active medium, antenna-feedback breaks this integer limit for the first time and enhances the radiative field of the lasing mode. Terahertz lasers with narrow-beam emission will find applications for integrated as well as standoff terahertz spectroscopy and sensing. Furthermore, the antenna-feedback scheme is generally applicable to any plasmonic laser with a Fabry–Perot cavity

  17. Study on elucidation of bactericidal effects induced by laser beam irradiation Measurement of dynamic stress on laser irradiated surface

    NASA Astrophysics Data System (ADS)

    Furumoto, Tatsuaki; Kasai, Atsushi; Tachiya, Hiroshi; Hosokawa, Akira; Ueda, Takashi

    2010-09-01

    In dental treatment, many types of laser beams have been used for various surgical treatments, and the influences of laser beam irradiation on bactericidal effect have been investigated. However, most of the work has been performed by irradiating to an agar plate with the colony of bacteria, and very few studies have been reported on the physical mechanism of bactericidal effects induced by laser beam irradiation. This paper deals with the measurement of dynamic stress induced in extracted human enamel by irradiation with Nd:YAG laser beams. Laser beams can be delivered to the enamel surface through a quartz optical fiber. Dynamic stress induced in the specimen using elastic wave propagation in a cylindrical long bar made of aluminum alloy is measured. Laser induced stress intensity is evaluated from dynamic strain measured by small semiconductor strain gauges. Carbon powder and titanium dioxide powder were applied to the human enamel surface as absorbents. Additionally, the phenomenon of laser beam irradiation to the human enamel surface was observed with an ultrahigh speed video camera. Results showed that a plasma was generated on the enamel surface during laser beam irradiation, and the melted tissues were scattered in the vertical direction against the enamel surface with a mushroom-like wave. Averaged scattering velocity of the melted tissues was 25.2 m/s. Induced dynamic stress on the enamel surface increased with increasing laser energy in each absorbent. Induced dynamic stresses with titanium dioxide powder were superior to those with carbon powder. Induced dynamic stress was related to volume of prepared cavity, and induced stress for the removal of unit volume of human enamel was 0.03 Pa/mm 3.

  18. Method for changing the cross section of a laser beam

    DOEpatents

    Sweatt, W.C.; Seppala, L.

    1995-12-05

    A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser. 4 figs.

  19. Method for changing the cross section of a laser beam

    DOEpatents

    Sweatt, William C.; Seppala, Lynn

    1995-01-01

    A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser.

  20. D-Cluster Converter Foil for Laser-Accelerated Deuteron Beams: Towards Deuteron-Beam-Driven Fast Ignition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miley, George H.

    Fast Ignition (FI) uses Petawatt laser generated particle beam pulse to ignite a small volume called a pre-compressed Inertial Confinement Fusion (ICF) target, and is the favored method to achieve the high energy gain per target burn needed for an attractive ICF power plant. Ion beams such as protons, deuterons or heavier carbon ions are especially appealing for FI as they have relative straight trajectory, and easier to focus on the fuel capsule. But current experiments have encountered problems with the 'converter-foil' which is irradiated by the Petawatt laser to produce the ion beams. The problems include depletion of themore » available ions in the convertor foils, and poor energy efficiency (ion beam energy/ input laser energy). We proposed to develop a volumetrically-loaded ultra-high-density deuteron deuterium cluster material as the basis for converter-foil for deuteron beam generation. The deuterons will fuse with the ICF DT while they slow down, providing an extra 'bonus' energy gain in addition to heating the hot spot. Also, due to the volumetric loading, the foil will provide sufficient energetic deuteron beam flux for 'hot spot' ignition, while avoiding the depletion problem encountered by current proton-driven FI foils. After extensive comparative studies, in Phase I, high purity PdO/Pd/PdO foils were selected for the high packing fraction D-Cluster converter foils. An optimized loading process has been developed to increase the cluster packing fraction in this type of foil. As a result, the packing fraction has been increased from 0.1% to 10% - meeting the original Phase I goal and representing a significant progress towards the beam intensities needed for both FI and pulsed neutron applications. Fast Ignition provides a promising approach to achieve high energy gain target performance needed for commercial Inertial Confinement Fusion (ICF). This is now a realistic goal for near term in view of the anticipated ICF target burn at the National

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, F.; Bohler, D.; Ding, Y.

    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 Lightmore » Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.« less

  2. Noncontact Acousto-Ultrasonic Testing With Laser Beams

    NASA Technical Reports Server (NTRS)

    Huber, Robert D.; Green, Robert E., Jr.

    1994-01-01

    Laser beams used to excite and detect acoustic waves in specimens. Laser/acousto-ultrasonic technique entails no mechanical contact between specimens and testing apparatus. Apparatus located at relatively large distances (meters) from specimens, making it possible to test specimens too hot for contact measurements or located in inaccessible places, vacuums, or hostile environments.

  3. UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bakeman, M.S.; Fawley, W.M.; Leemans, W. P.

    to couple the THUNDER undulator to the LOASIS Lawrence Berkeley National Laboratory (LBNL) laser wakefield accelerator (LWFA). Currently the LWFA has achieved quasi-monoenergetic electron beams with energies up to 1 GeV. These ultra-short, high-peak-current, electron beams are ideal for driving a compact XUV free electron laser (FEL). Understanding the electron beam properties such as the energy spread and emittance is critical for achieving high quality light sources with high brightness. By using an insertion device such as an undulator and observing changes in the spontaneous emission spectrum, the electron beam energy spread and emittance can be measured with high precision.more » The initial experiments will use spontaneous emission from 1.5 m of undulator. Later experiments will use up to 5 m of undulator with a goal of a high gain, XUV FEL.« less

  4. Narrow linewidth operation of a spectral beam combined diode laser bar.

    PubMed

    Zhu, Zhanda; Jiang, Menghua; Cheng, Siqi; Hui, Yongling; Lei, Hong; Li, Qiang

    2016-04-20

    Our experiment is expected to provide an approach for realizing ultranarrow linewidth for a spectral beam combined diode laser bar. The beams of a diode laser bar are combined in a fast axis after a beam transformation system. With the help of relay optics and a transform lens with a long focal length of 1.5 m, the whole wavelength of a spectral combined laser bar can be narrowed down to 0.48 nm from more than 10 nm. We have achieved 56.7 W cw from a 19-element single bar with an M2 of 1.4  (in horizontal direction)×11.6  (in vertical direction). These parameters are good evidence that all the beams from the diode laser bar are combined together to increase the brightness.

  5. Generation of a cylindrically symmetric, polarized laser beam with narrow linewidth and fine tunability

    NASA Astrophysics Data System (ADS)

    Hirayama, Toru; Kozawa, Yuichi; Nakamura, Takahiro; Sato, Shunichi

    2006-12-01

    We demonstrated a generation of cylindrically symmetric, polarized laser beams with narrow linewidth and fine tunability. Since an LP11 mode beam in an optical fiber is a superposition of an HE21 (hybrid) mode beam and a TE01 or TM01 mode beam, firstly, a higher order transverse (TEM01 or TEM10) mode laser beam with narrow linewidth and fine tunability was generated from an external cavity diode laser (ECDL) in conjunction with a phase adjustment plate. Then the beam generated was passed in a two mode optical fiber. A doughnut shaped laser beam with the cylindrically symmetric polarization (a radially or azimuthally polarized beam) was obtained by properly adding stress-induced birefringence in the optical fiber.

  6. Surface Structuring with Polarization-Singular Femtosecond Laser Beams Generated by a q-plate

    PubMed Central

    Nivas, Jijil JJ; Cardano, Filippo; Song, Zhenming; Rubano, Andrea; Fittipaldi, Rosalba; Vecchione, Antonio; Paparo, Domenico; Marrucci, Lorenzo; Bruzzese, Riccardo; Amoruso, Salvatore

    2017-01-01

    In the last few years femtosecond optical vortex beams with different spatial distributions of the state of polarization (e.g. azimuthal, radial, spiral, etc.) have been used to generate complex, regular surface patterns on different materials. Here we present an experimental investigation on direct femtosecond laser surface structuring based on a larger class of vector beams generated by means of a q-plate with topological charge q = +1/2. In fact, voltage tuning of q-plate optical retardation allows generating a family of ultrashort laser beams with a continuous spatial evolution of polarization and fluence distribution in the focal plane. These beams can be thought of as a controlled coherent superposition of a Gaussian beam with uniform polarization and a vortex beam with a radial or azimuthal state of polarization. The use of this family of ultrashort laser beams in surface structuring leads to a further extension of the achievable surface patterns. The comparison of theoretical predictions of the vector beam characteristics at the focal plane and the generated surface patterns is used to rationalize the dependence of the surface structures on the local state of the laser beam, thus offering an effective way to either design unconventional surface structures or diagnose complex ultrashort laser beams. PMID:28169342

  7. Surface Structuring with Polarization-Singular Femtosecond Laser Beams Generated by a q-plate.

    PubMed

    Nivas, Jijil Jj; Cardano, Filippo; Song, Zhenming; Rubano, Andrea; Fittipaldi, Rosalba; Vecchione, Antonio; Paparo, Domenico; Marrucci, Lorenzo; Bruzzese, Riccardo; Amoruso, Salvatore

    2017-02-07

    In the last few years femtosecond optical vortex beams with different spatial distributions of the state of polarization (e.g. azimuthal, radial, spiral, etc.) have been used to generate complex, regular surface patterns on different materials. Here we present an experimental investigation on direct femtosecond laser surface structuring based on a larger class of vector beams generated by means of a q-plate with topological charge q = +1/2. In fact, voltage tuning of q-plate optical retardation allows generating a family of ultrashort laser beams with a continuous spatial evolution of polarization and fluence distribution in the focal plane. These beams can be thought of as a controlled coherent superposition of a Gaussian beam with uniform polarization and a vortex beam with a radial or azimuthal state of polarization. The use of this family of ultrashort laser beams in surface structuring leads to a further extension of the achievable surface patterns. The comparison of theoretical predictions of the vector beam characteristics at the focal plane and the generated surface patterns is used to rationalize the dependence of the surface structures on the local state of the laser beam, thus offering an effective way to either design unconventional surface structures or diagnose complex ultrashort laser beams.

  8. Surface Structuring with Polarization-Singular Femtosecond Laser Beams Generated by a q-plate

    NASA Astrophysics Data System (ADS)

    Nivas, Jijil Jj; Cardano, Filippo; Song, Zhenming; Rubano, Andrea; Fittipaldi, Rosalba; Vecchione, Antonio; Paparo, Domenico; Marrucci, Lorenzo; Bruzzese, Riccardo; Amoruso, Salvatore

    2017-02-01

    In the last few years femtosecond optical vortex beams with different spatial distributions of the state of polarization (e.g. azimuthal, radial, spiral, etc.) have been used to generate complex, regular surface patterns on different materials. Here we present an experimental investigation on direct femtosecond laser surface structuring based on a larger class of vector beams generated by means of a q-plate with topological charge q = +1/2. In fact, voltage tuning of q-plate optical retardation allows generating a family of ultrashort laser beams with a continuous spatial evolution of polarization and fluence distribution in the focal plane. These beams can be thought of as a controlled coherent superposition of a Gaussian beam with uniform polarization and a vortex beam with a radial or azimuthal state of polarization. The use of this family of ultrashort laser beams in surface structuring leads to a further extension of the achievable surface patterns. The comparison of theoretical predictions of the vector beam characteristics at the focal plane and the generated surface patterns is used to rationalize the dependence of the surface structures on the local state of the laser beam, thus offering an effective way to either design unconventional surface structures or diagnose complex ultrashort laser beams.

  9. Multi-Wavelength, Multi-Beam, and Polarization-Sensitive Laser Transmitter for Surface Mapping

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Ramos-Izquierdo, Luis; Harding, David; Huss, Tim

    2011-01-01

    A multi-beam, multi-color, polarized laser transmitter has been developed for mapping applications. It uses commercial off-the-shelf components for a lowcost approach for a ruggedized laser suitable for field deployment. The laser transmitter design is capable of delivering dual wavelengths, multiple beams on each wavelength with equal (or variable) intensities per beam, and a welldefined state of polarization. This laser transmitter has been flown on several airborne campaigns for the Slope Imaging Multi-Polarization Photon Counting Lidar (SIMPL) instrument, and at the time of this reporting is at a technology readiness level of between 5 and 6. The laser is a 1,064-nm microchip high-repetition-rate laser emitting energy of about 8 microjoules per pulse. The beam was frequency-doubled to 532 nm using a KTP (KTiOPO4) nonlinear crystal [other nonlinear crystals such as LBO (LiB3O5) or periodically poled lithium niobiate can be used as well, depending on the conversion efficiency requirements], and the conversion efficiency was approximately 30 percent. The KTP was under temperature control using a thermoelectric cooler and a feedback monitoring thermistor. The dual-wavelength beams were then spectrally separated and each color went through its own optical path, which consisted of a beam-shaping lens, quarterwave plate (QWP), and a birefringent crystal (in this case, a calcite crystal, but others such as vanadate can be used). The QWP and calcite crystal set was used to convert the laser beams from a linearly polarized state to circularly polarized light, which when injected into a calcite crystal, will spatially separate the circularly polarized light into the two linear polarized components. The spatial separation of the two linearly polarized components is determined by the length of the crystal. A second set of QWP and calcite then further separated the two beams into four. Additional sets of QWP and calcite can be used to further split the beams into multiple

  10. 2000W high beam quality diode laser for direct materials processing

    NASA Astrophysics Data System (ADS)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

    2011-11-01

    This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

  11. Research of beam conditioning technologies on SG-III laser facility

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Su, Jingqin; Yuan, Haoyu; Li, Ping; Tian, Xiaocheng; Wang, Jianjun; Dong, Jun; Zhang, Ying; Yuan, Qiang; Wang, Yuancheng; Zhou, Wei; Peng, Zhitao; Wang, Fang; Hu, Dongxia; Zhu, Qihua; Zheng, Wanguo; Zhang, Xiaomin

    2014-12-01

    Multi-FM SSD and CPP was experimentally studied in high fluence and will be equipped on all the beams of SG-III laser facility. The output spectrum of the cascade phase modulators are stable and the residual amplitude modulation is small. FM-to-AM effect caused by free-space propagation after using smoothing by spectral dispersion is theoretically analyzed. Results indicate inserting a dispersion grating in places with larger beam aperture could alleviate the FM-to- AM effect, suggesting minimizing free-space propagation and adopting image relay. Experiments taken on SG-III laser facility indicate when the number of color cycles (Nc) adopts 1, imposing of SSD with 3.3 times diffraction limit (TDL) did not lead to pinhole closure in the spatial filters of the preamplifier and main amplifier with 30-TDL pinhole size. The nonuniformity of the focal spot using Multi-FM SSD and CPP drops to 0.26, comparing to 0.84 only using CPP. The experiments solve some key technical problems using SSD and CPP on SG-III laser facility, and provide a flexible platform for laser-plasma interaction experiments. Combined beam smoothing and polarization smoothing are also analyzed. Simulation results indicate through adjusting dispersion directions of one-dimensional SSD beams in a quad, two-dimensional SSD could be obtained. The near field and far field properties of beams using polarization smoothing were also studied, including birefringent wedge and polarization control plate (PCP). By using PCP, cylindrical vector beams could be obtained. New solutions will be provided to solve the LPI problem encountered in indirect drive laser fusion.

  12. Beam current controller for laser ion source

    DOEpatents

    Okamura, Masahiro

    2014-10-28

    The present invention relates to the design and use of an ion source with a rapid beam current controller for experimental and medicinal purposes. More particularly, the present invention relates to the design and use of a laser ion source with a magnetic field applied to confine a plasma flux caused by laser ablation.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Hollow core waveguide as mid-infrared laser modal beam filter

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Patimisco, P.; Giglio, M.; Spagnolo, V.

    2015-09-21

    A novel method for mid-IR laser beam mode cleaning employing hollow core waveguide as a modal filter element is reported. The influence of the input laser beam quality on fiber optical losses and output beam profile using a hollow core waveguide with 200 μm-bore size was investigated. Our results demonstrate that even when using a laser with a poor spatial profile, there will exist a minimum fiber length that allows transmission of only the Gaussian-like fundamental waveguide mode from the fiber, filtering out all the higher order modes. This essentially single mode output is preserved also when the waveguide is bentmore » to a radius of curvature of 7.5 cm, which demonstrates that laser mode filtering can be realized even if a curved light path is required.« less

  15. Methods and Devices for Space Optical Communications Using Laser Beams

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M. (Inventor)

    2018-01-01

    Light is used to communicate between objects separated by a large distance. Light beams are received in a telescopic lens assembly positioned in front of a cat's-eye lens. The light can thereby be received at various angles to be output by the cat's-eye lens to a focal plane of the cat's-eye lens, the position of the light beams upon the focal plane corresponding to the angle of the beam received. Lasers and photodetectors are distributed along this focal plane. A processor receives signals from the photodetectors, and selectively signal lasers positioned proximate the photodetectors detecting light, in order to transmit light encoding data through the cat's-eye lens and also through a telescopic lens back in the direction of the received light beams, which direction corresponds to a location upon the focal plane of the transmitting lasers.

  16. Feasibility study of using laser-generated neutron beam for BNCT.

    PubMed

    Kasesaz, Y; Rahmani, F; Khalafi, H

    2015-09-01

    The feasibility of using a laser-accelerated proton beam to produce a neutron source, via (p,n) reaction, for Boron Neutron Capture Therapy (BNCT) applications has been studied by MCNPX Monte Carlo code. After optimization of the target material and its thickness, a Beam Shaping Assembly (BSA) has been designed and optimized to provide appropriate neutron beam according to the recommended criteria by International Atomic Energy Agency. It was found that the considered laser-accelerated proton beam can provide epithermal neutron flux of ∼2×10(6) n/cm(2) shot. To achieve an appropriate epithermal neutron flux for BNCT treatment, the laser must operate at repetition rates of 1 kHz, which is rather ambitious at this moment. But it can be used in some BNCT researches field such as biological research. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Multi-GeV electron-positron beam generation from laser-electron scattering.

    PubMed

    Vranic, Marija; Klimo, Ondrej; Korn, Georg; Weber, Stefan

    2018-03-16

    The new generation of laser facilities is expected to deliver short (10 fs-100 fs) laser pulses with 10-100 PW of peak power. This opens an opportunity to study matter at extreme intensities in the laboratory and provides access to new physics. Here we propose to scatter GeV-class electron beams from laser-plasma accelerators with a multi-PW laser at normal incidence. In this configuration, one can both create and accelerate electron-positron pairs. The new particles are generated in the laser focus and gain relativistic momentum in the direction of laser propagation. Short focal length is an advantage, as it allows the particles to be ejected from the focal region with a net energy gain in vacuum. Electron-positron beams obtained in this setup have a low divergence, are quasi-neutral and spatially separated from the initial electron beam. The pairs attain multi-GeV energies which are not limited by the maximum energy of the initial electron beam. We present an analytical model for the expected energy cutoff, supported by 2D and 3D particle-in-cell simulations. The experimental implications, such as the sensitivity to temporal synchronisation and laser duration is assessed to provide guidance for the future experiments.

  18. Compact two-beam push-pull free electron laser

    DOEpatents

    Hutton, Andrew [Yorktown, VA

    2009-03-03

    An ultra-compact free electron laser comprising a pair of opposed superconducting cavities that produce identical electron beams moving in opposite directions such that each set of superconducting cavities accelerates one electron beam and decelerates the other electron beam. Such an arrangement, allows the energy used to accelerate one beam to be recovered and used again to accelerate the second beam, thus, each electron beam is decelerated by a different structure than that which accelerated it so that energy exchange rather than recovery is achieved resulting in a more compact and highly efficient apparatus.

  19. Free-electron laser power beaming to satellites at China Lake, California

    NASA Astrophysics Data System (ADS)

    Bennett, Harold E.; Rather, John D.; Montgomery, Edward E.

    1994-05-01

    Laser power beaming of energy through the atmosphere to a satellite can extend its lifetime by maintaining the satellite batteries in operating condition. An alternate propulsion system utilizing power beaming will also significantly reduce the initial insertion cost of these satellites, which now are as high as $DLR72,000/lb for geosynchronous orbit. Elements of the power beaming system are a high-power laser, a large diameter telescope to reduce diffractive losses, an adaptive optic beam conditioning system and possibly a balloon or aerostat carrying a large mirror to redirect the laser beam to low earth orbit satellites after it has traversed most of the earth's atmosphere vertically. China Lake, California has excellent seeing, averages 260 cloud-free days/year, has the second largest geothermal plant in the United States nearby for power, groundwater from the lake for cooling water, and is at the center of one of the largest restricted airspaces in the United States. It is an ideal site for such a laser power beaming system. Technological challenges in building such a system and installing it at China Lake will be discussed.

  20. Laser beam methane detector

    NASA Technical Reports Server (NTRS)

    Hinkley, E. D., Jr.

    1981-01-01

    Instrument uses infrared absorption to determine methane concentration in liquid natural gas vapor. Two sensors measure intensity of 3.39 mm laser beam after it passes through gas; absorption is proportional to concentration of methane. Instrument is used in modeling spread of LNG clouds and as leak detector on LNG carriers and installations. Unit includes wheels for mobility and is both vertically and horizontally operable.

  1. Laser-induced retinal damage thresholds for annular retinal beam profiles

    NASA Astrophysics Data System (ADS)

    Kennedy, Paul K.; Zuclich, Joseph A.; Lund, David J.; Edsall, Peter R.; Till, Stephen; Stuck, Bruce E.; Hollins, Richard C.

    2004-07-01

    The dependence of retinal damage thresholds on laser spot size, for annular retinal beam profiles, was measured in vivo for 3 μs, 590 nm pulses from a flashlamp-pumped dye laser. Minimum Visible Lesion (MVL)ED50 thresholds in rhesus were measured for annular retinal beam profiles covering 5, 10, and 20 mrad of visual field; which correspond to outer beam diameters of roughly 70, 160, and 300 μm, respectively, on the primate retina. Annular beam profiles at the retinal plane were achieved using a telescopic imaging system, with the focal properties of the eye represented as an equivalent thin lens, and all annular beam profiles had a 37% central obscuration. As a check on experimental data, theoretical MVL-ED50 thresholds for annular beam exposures were calculated using the Thompson-Gerstman granular model of laser-induced thermal damage to the retina. Threshold calculations were performed for the three experimental beam diameters and for an intermediate case with an outer beam diameter of 230 μm. Results indicate that the threshold vs. spot size trends, for annular beams, are similar to the trends for top hat beams determined in a previous study; i.e., the threshold dose varies with the retinal image area for larger image sizes. The model correctly predicts the threshold vs. spot size trends seen in the biological data, for both annular and top hat retinal beam profiles.

  2. Partial-Wave Representations of Laser Beams for Use in Light-Scattering Calculations

    NASA Technical Reports Server (NTRS)

    Gouesbet, Gerard; Lock, James A.; Grehan, Gerard

    1995-01-01

    In the framework of generalized Lorenz-Mie theory, laser beams are described by sets of beam-shape coefficients. The modified localized approximation to evaluate these coefficients for a focused Gaussian beam is presented. A new description of Gaussian beams, called standard beams, is introduced. A comparison is made between the values of the beam-shape coefficients in the framework of the localized approximation and the beam-shape coefficients of standard beams. This comparison leads to new insights concerning the electromagnetic description of laser beams. The relevance of our discussion is enhanced by a demonstration that the localized approximation provides a very satisfactory description of top-hat beams as well.

  3. Laser beam modeling in optical storage systems

    NASA Technical Reports Server (NTRS)

    Treptau, J. P.; Milster, T. D.; Flagello, D. G.

    1991-01-01

    A computer model has been developed that simulates light propagating through an optical data storage system. A model of a laser beam that originates at a laser diode, propagates through an optical system, interacts with a optical disk, reflects back from the optical disk into the system, and propagates to data and servo detectors is discussed.

  4. Electron beam switched discharge for rapidly pulsed lasers

    DOEpatents

    Pleasance, Lyn D.; Murray, John R.; Goldhar, Julius; Bradley, Laird P.

    1981-01-01

    Method and apparatus for electrical excitation of a laser gas by application of a pulsed voltage across the gas, followed by passage of a pulsed, high energy electron beam through the gas to initiate a discharge suitable for laser excitation. This method improves upon current power conditioning techniques and is especially useful for driving rare gas halide lasers at high repetition rates.

  5. Safe Laser Beam Propagation for Interplanetary Links

    NASA Technical Reports Server (NTRS)

    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.

  6. Appropriate Measures and Consistent Standard for High Energy Laser Beam Quality (Postprint)

    DTIC Science & Technology

    2006-08-01

    another. a We follow the 99% criteria [ Siegman , Lasers , chapter 17.1] which corresponds to a... Siegman , “ Lasers ” University Science Books, 1986. • A.E. Siegman , “New developments in laser resonators”, SPIE Vol. 1224, Optical Resonators, 1990...pp. 1-14. • Anthony E. Siegman & Steven W. Townsend, “Output Beam Propagation and Beam Quality from a Multimode Stable-Cavity Laser ”, IEEE Journal

  7. Laser beam interactions with vapor plumes during Nd:YAG laser welding on aluminum

    NASA Astrophysics Data System (ADS)

    Peebles, H. C.; Russo, A. J.; Hadley, G. R.; Akau, R. L.

    Welds produced on pure aluminum targets using pulsed Nd:YAG lasers can be accurately described using a relatively simple conduction mode heat transfer model provided that the fraction of laser energy absorbed is known and the amount of metal vaporized is smalled however at laser fluences commonly used in many production welding schedules significant aluminum vaporization does occur. The possible mechanisms have been identified which could result in laser beam attenuation by the vapor plume.

  8. The suppression of radiation reaction and laser field depletion in laser-electron beam interaction

    NASA Astrophysics Data System (ADS)

    Ong, J. F.; Moritaka, T.; Takabe, H.

    2018-03-01

    The effects of radiation reaction (RR) have been studied extensively by using the interaction of ultraintense lasers with a counter-propagating relativistic electron. At the laser intensity at the order of 1023 W/cm2, the effects of RR are significant in a few laser periods for a relativistic electron. However, a laser at such intensity is tightly focused and the laser energy is usually assumed to be fixed. Then, the signal of RR and energy conservation cannot be guaranteed. To assess the effects of RR in a tightly focused laser pulse and the evolution of the laser energy, we simulated this interaction with a beam of 109 electrons by means of a Particle-In-Cell method. We observe that the effects of RR are suppressed due to the ponderomotive force and accompanied by a non-negligible amount of laser field energy reduction. This is because the ponderomotive force prevents the electrons from approaching the center of the laser pulse and leads to an interaction at the weaker field region. At the same time, the laser energy is absorbed through ponderomotive acceleration. Thus, the kinetic energy of the electron beam has to be carefully selected such that the effects of RR become obvious.

  9. Precision laser surveying instrument using atmospheric turbulence compensation by determining the absolute displacement between two laser beam components

    DOEpatents

    Veligdan, James T.

    1993-01-01

    Atmospheric effects on sighting measurements are compensated for by adjusting any sighting measurements using a correction factor that does not depend on atmospheric state conditions such as temperature, pressure, density or turbulence. The correction factor is accurately determined using a precisely measured physical separation between two color components of a light beam (or beams) that has been generated using either a two-color laser or two lasers that project different colored beams. The physical separation is precisely measured by fixing the position of a short beam pulse and measuring the physical separation between the two fixed-in-position components of the beam. This precisely measured physical separation is then used in a relationship that includes the indexes of refraction for each of the two colors of the laser beam in the atmosphere through which the beam is projected, thereby to determine the absolute displacement of one wavelength component of the laser beam from a straight line of sight for that projected component of the beam. This absolute displacement is useful to correct optical measurements, such as those developed in surveying measurements that are made in a test area that includes the same dispersion effects of the atmosphere on the optical measurements. The means and method of the invention are suitable for use with either single-ended systems or a double-ended systems.

  10. Influence of fundamental mode fill factor on disk laser output power and laser beam quality

    NASA Astrophysics Data System (ADS)

    Cheng, Zhiyong; Yang, Zhuo; Shao, Xichun; Li, Wei; Zhu, Mengzhen

    2017-11-01

    An three-dimensional numerical model based on finite element method and Fox-Li method with angular spectrum diffraction theoy is developed to calculate the output power and power density distribution of Yb:YAG disk laser. We invest the influence of fundamental mode fill factor(the ratio of fundamental mode size and pump spot size) on the output power and laser beam quality. Due to aspherical aberration and soft aperture effect in laser disk, high beam quality can be achieve with relative lower efficiency. The highest output power of fundamental laser mode is influenced by the fundamental mode fill factor. Besides we find that optimal mode fill factor increase with pump spot size.

  11. Evaluating the beam quality of double-cladding fiber lasers in applications.

    PubMed

    Yan, Ping; Wang, Xuejiao; Gong, Mali; Xiao, Qirong

    2016-08-10

    We put forward a new βFL factor, which is used exclusively in fiber lasers and is suitable to assess beam quality and choose the LP01 mode as the new suitable ideal beam. We present a new simple measurement method and verify the reasonability of the βFL factor in experiment in a 20/400 μm fiber laser. Furthermore, we use the βFL factor to evaluate the beam quality of a 3-kW-level fiber laser. It can be concluded that βFL is a key factor not only for assessing the performance of the high-power fiber laser that is our main focus, but also for the simple measurement.

  12. Foil cooling for rep-rated electron beam pumped KrF lasers

    NASA Astrophysics Data System (ADS)

    Giuliani, J. L.; Hegeler, F.; Sethian, J. D.; Wolford, M. F.; Myers, M. C.; Abdel-Khalik, S.; Sadowski, D.; Schoonover, K.; Novak, V.

    2006-06-01

    In rep-rated electron beam pumped lasers the foil separating the vacuum diode from the laser gas is subject to repeated heating due to partial beam stopping. Three cooling methods are examined for the Electra KrF laser at the Naval Research Laboratory (NRL). Foil temperature measurements for convective cooling by the recirculating laser gas and by spray mist cooling are reported, along with estimates for thermal conductive foil cooling to the hibachi ribs. Issues on the application of each of these approaches to laser drivers in a fusion power plant are noted. Work supported by DOE/NNSA.

  13. Long range laser propagation: power scaling and beam quality issues

    NASA Astrophysics Data System (ADS)

    Bohn, Willy L.

    2010-09-01

    This paper will address long range laser propagation applications where power and, in particular beam quality issues play a major role. Hereby the power level is defined by the specific mission under consideration. I restrict myself to the following application areas: (1)Remote sensing/Space based LIDAR, (2) Space debris removal (3)Energy transmission, and (4)Directed energy weapons Typical examples for space based LIDARs are the ADM Aeolus ESA mission using the ALADIN Nd:YAG laser with its third harmonic at 355 nm and the NASA 2 μm Tm:Ho:LuLiF convectively cooled solid state laser. Space debris removal has attracted more attention in the last years due to the dangerous accumulation of debris in orbit which become a threat to the satellites and the ISS space station. High power high brightness lasers may contribute to this problem by partially ablating the debris material and hence generating an impulse which will eventually de-orbit the debris with their subsequent disintegration in the lower atmosphere. Energy transmission via laser beam from space to earth has long been discussed as a novel long term approach to solve the energy problem on earth. In addition orbital transfer and stationkeeping are among the more mid-term applications of high power laser beams. Finally, directed energy weapons are becoming closer to reality as corresponding laser sources have matured due to recent efforts in the JHPSSL program. All of this can only be realized if he laser sources fulfill the necessary power requirements while keeping the beam quality as close as possible to the diffraction limited value. And this is the rationale and motivation of this paper.

  14. The study of the structural stability of the spiral laser beams propagation through inhomogeneous phase medium

    NASA Astrophysics Data System (ADS)

    Zinchik, Alexander A.; Muzychenko, Yana B.

    2015-06-01

    This paper discusses theoretical and experimental results of the investigation of light beams that retain their intensity structure during propagation and focusing. Spiral laser beams are a family of laser beams that preserve the structural stability up to scale and rotation with the propagation. Properties of spiral beams are of practical interest for laser technology, medicine and biotechnology. Researchers use a spiral beams for movement and manipulation of microparticles. Functionality laser manipulators can be significantly enhanced by using spiral beams whose intensity remains invariable. It is well known, that these beams has non-zero orbital angular momentum. Spiral beams have a complicated phase distribution in cross section. In this paper we investigate the structural stability of the laser beams having a spiral phase structure by passing them through an inhomogeneous phase medium. Laser beam is passed through a medium is characterized by a random distribution of phase in the range 0..2π. The modeling was performed using VirtualLab 5.0 (manufacturer LightTrans GmbH). Compared the intensity distribution of the spiral and ordinary laser beam after the passage of the inhomogeneous medium. It is shown that the spiral beams exhibit a significantly better structural stability during the passage phase heterogeneous environments than conventional laser beams. The results obtained in the simulation are tested experimentally. Experimental results show good agreement with the theoretical results.

  15. Laser beam propagation through turbulence and adaptive optics for beam delivery improvement

    NASA Astrophysics Data System (ADS)

    Nicolas, Stephane

    2015-10-01

    We report results from numerical simulations of laser beam propagation through atmospheric turbulence. In particular, we study the statistical variations of the fractional beam energy hitting inside an optical aperture placed at several kilometer distance. The simulations are performed for different turbulence conditions and engagement ranges, with and without the use of turbulence mitigation. Turbulence mitigation is simulated with phase conjugation. The energy fluctuations are deduced from time sequence realizations. It is shown that turbulence mitigation leads to an increase of the mean energy inside the aperture and decrease of the fluctuations even in strong turbulence conditions and long distance engagement. As an example, the results are applied to a high energy laser countermeasure system, where we determine the probability that a single laser pulse, or one of the pulses in a sequence, will provide a lethal energy inside the target aperture. Again, turbulence mitigation contributes to increase the performance of the system at long-distance and for strong turbulence conditions in terms of kill probability. We also discuss a specific case where turbulence contributes to increase the pulse energy within the target aperture. The present analysis can be used to evaluate the performance of a variety of systems, such as directed countermeasures, laser communication, and laser weapons.

  16. Electron beam cooling in intense focussed laser pulses

    NASA Astrophysics Data System (ADS)

    Yoffe, Samuel R.; Noble, Adam; Macleod, Alexander J.; Jaroszynski, Dino A.

    2017-05-01

    In the coming years, a new generation of high-power laser facilities (such as the Extreme Light Infrastructure) will become operational, for which it is important to understand how the interaction with intense laser pulses affects the bulk properties of relativistic electron bunches. At such high field intensities, we expect both radiation reaction and quantum effects to have a dominant role to play in determining the dynamics. The reduction in relative energy spread (beam cooling) at the expense of mean beam energy predicted by classical theories of radiation reaction has been shown to occur equally in the longitudinal and transverse directions, whereas this symmetry is broken when the theory is extended to approximate certain quantum effects. The reduction in longitudinal cooling suggests that the effects of radiation reaction could be better observed in measurements of the transverse distribution, which for real-world laser pulses motivates the investigation of the angular dependence of the interaction. Using a stochastic single-photon emission model with a (Gaussian beam) focussed pulse, we find strong angular dependence of the stochastic heating.

  17. Electron beam-switched discharge for rapidly pulsed lasers

    DOEpatents

    Pleasance, L.D.; Murray, J.R.; Goldhar, J.; Bradley, L.P.

    1979-12-11

    A method and apparatus are designed for electrical excitation of a laser gas by application of a pulsed voltage across the gas, followed by passage of a pulsed, high energy electron beam through the gas to initiate a discharge suitable for laser excitation. This method improves upon current power conditioning techniques and is especially useful for driving rare gas halide lasers at high repetition rates.

  18. First light from the Diocles laser: Relativistic laser-plasmas and beams

    NASA Astrophysics Data System (ADS)

    Umstadter, Donald

    2007-06-01

    Reported are first experimental results from a new high-power (150 TW) laser, Diocles, now in operation at the University of Nebraska, Lincoln. Discussed are novel approaches to using the ultra-high-intensity light from this laser to study relativistic laser plasma interactions. Bright, ultrashort duration (femtosecond ) pulses of energetic (keV -- MeV) x-ray and charged-particle beams are generated through these interactions. Also covered in this talk will be applications of these unique radiation sources for research in the physical sciences, as well as biomedicine, defense and homeland security.

  19. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    NASA Astrophysics Data System (ADS)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Döbeli, Max; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

    2015-10-01

    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 18O substituted La0.6Sr0.4MnO3 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.

  20. Spot size characterization of focused non-Gaussian X-ray laser beams.

    PubMed

    Chalupský, J; Krzywinski, J; Juha, L; Hájková, V; Cihelka, J; Burian, T; Vysín, L; Gaudin, J; Gleeson, A; Jurek, M; Khorsand, A R; Klinger, D; Wabnitz, H; Sobierajski, R; Störmer, M; Tiedtke, K; Toleikis, S

    2010-12-20

    We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula. As a generalization of the beam spot area we apply and refine the definition of so called effective area (A(eff)) [1] in order to avoid using the full-width at half maximum (FWHM) parameter which is inappropriate for non-Gaussian beams. Furthermore, we demonstrate a practical utilization of our technique for a femtosecond soft X-ray free-electron laser. The ablative imprints in poly(methyl methacrylate) - PMMA and amorphous carbon (a-C) are used to characterize the spatial beam profile and to determine the effective area. Two procedures of the effective area determination are presented in this work. An F-scan method, newly developed in this paper, appears to be a good candidate for the spatial beam diagnostics applicable to lasers of various kinds.

  1. Generation of vortex array laser beams with Dove prism embedded unbalanced Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Chu, Shu-Chun

    2009-02-01

    This paper introduces a scheme for generation of vortex laser beams from a solid-state laser with off-axis laser-diode pumping. The proposed system consists of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer configuration. This configuration allows controlled construction of p × p vortex array beams from Ince-Gaussian modes, IGep,p modes. An incident IGe p,p laser beam of variety order p can easily be generated from an end-pumped solid-state laser with an off-axis pumping mechanism. This study simulates this type of vortex array laser beam generation and discusses beam propagation effects. The formation of ordered transverse emission patterns have applications in a variety of areas such as optical data storage, distribution, and processing that exploit the robustness of soliton and vortex fields and optical manipulations of small particles and atoms in the featured intensity distribution.

  2. ISTC projects devoted to improving laser beam quality

    NASA Astrophysics Data System (ADS)

    Malakhov, Yu. I.

    2007-05-01

    Short overview is done about the activity of ISTC in a direction concerned with improving powerful laser beam quality by means of nonlinear and linear adaptive optics methods. Completed projects #0591 and #1929 resulted in the development of a stimulated Brillouin scattering (SBS) phase conjugation mirror of superhigh fidelity employing the kinoform optical elements (rasters of small lenses) of new generation designed for pulsed or pulse-periodic lasers with nanosecond scale pulse duration. Project #2631 is devoted to development of an adaptive optical system for phase registration and correction of laser beams with wave front vortices. The principles of operation of conventional adaptive systems are based on the assumption that the phase is a smooth continuous function in space. Therefore the solution of the Project tasks will assume a new step in adaptive optics.

  3. Direct periodic patterning of GaN-based light-emitting diodes by three-beam interference laser ablation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch

    2014-04-07

    We report on the direct patterning of two-dimensional periodic structures in GaN-based light-emitting diodes (LEDs) through laser interference ablation for the fast and reliable fabrication of periodic micro- and nano-structures aimed at enhancing light output. Holes arranged in a two-dimensional hexagonal lattice array having an opening size of 500 nm, depth of 50 nm, and a periodicity of 1 μm were directly formed by three-beam laser interference without photolithography or electron-beam lithography processes. The laser-patterned LEDs exhibit an enhancement in light output power of 20% compared to conventional LEDs having a flat top surface without degradation of electrical and optical properties of themore » top p-GaN layer and the active region, respectively.« less

  4. Single laser beam of spatial coherence from an array of GaAs lasers - Free-running mode

    NASA Technical Reports Server (NTRS)

    Philipp-Rutz, E. M.

    1975-01-01

    Spatially coherent radiation from a monolithic array of three GaAs lasers in a free-running mode is reported. The lasers, with their mirror faces antireflection coated, are operated in an external optical cavity built of spherical lenses and plane mirrors. The spatially coherent-beam formation makes use of the Fourier-transformation property of the internal lenses. Transverse mode control is accomplished by a spatial filter. The optical cavity is similar to that used for the phase-controlled mode of spatially coherent-beam formation; only the spatial filters are different. In the far field (when restored by an external lens), the intensities of the lasers in the array are concentrated in a single laser beam of spatial coherence, without any grating lobes. The far-field distribution of the laser array in the free-running mode differs significantly from the interference pattern of the phase-controlled mode. The modulation characteristics of the optical waveforms of the two modes are also quite different because modulation is related to the interaction of the spatial filter with the longitudinal modes of the laser array within the optical cavity. The modulation of the optical waveform of the free-running mode is nonperiodic, confirming that the fluctuations of the optical fields of the lasers are random.

  5. Systems analysis on laser beamed power

    NASA Technical Reports Server (NTRS)

    Zeiders, Glenn W., Jr.

    1993-01-01

    The NASA SELENE power beaming program is intended to supply cost-effective power to space assets via Earth-based lasers and active optics systems. Key elements of the program are analyzed, the overall effort is reviewed, and recommendations are presented.

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

    DOE PAGES

    Liu, Tao; Zhang, Tong; Wang, Dong; ...

    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)more » is also adopted as an effective energy spread compensator to generate high-brilliance FEL radiation. As a result, 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.« less

  7. Laser controlled deposition of metal microstructures via nondiffracting Bessel beam illumination

    NASA Astrophysics Data System (ADS)

    Drampyan, Rafael; Leonov, Nikita; Vartanyan, Tigran

    2016-04-01

    The technique of the laser controlled deposition of sodium and rubidium deposits on the sapphire substrate is presented. The metals were deposited on the clean sapphire substrate from the vapor phase contained in the evacuated and sealed cell. We use an axicon to produce a non-diffracting Bessel beam out of the beam got from the cw diode laser with 200 mW power at the wavelength of 532 nm. After 30 minutes of the laser-controlled deposition the substrates were examined in the optical microscope. The obtained metal deposits form the sharp-cut circles with the pitch of 10 μm, coincident with the tens of dark rings of the Bessel beam. Reduction of the laser power leads to the build up of the continuous metal film over the whole substrate.

  8. High beam quality and high energy short-pulse laser with MOPA

    NASA Astrophysics Data System (ADS)

    Jin, Quanwei; Pang, Yu; Jiang, JianFeng; Tan, Liang; Cui, Lingling; Wei, Bin; Sun, Yinhong; Tang, Chun

    2018-03-01

    A high energy, high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with two amplifier stages is demonstrated. The two-rod birefringence compensation was used as beam quality controlling methods, which presents a short-pulse energy of 40 mJ with a beam quality value of M2 = 1.2 at a repetition rate of 400Hz. The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns.The method of spherical aberration compensation is improved the beam quality, a M2 factor of 2.3 and an optical-to-optical efficiency of 27.7% is obtained at the maximum laser out power.The laser obtained 1.4J out energy with polarization integration.

  9. Method for obtaining a collimated near-unity aspect ratio output beam from a DFB-GSE laser with good beam quality.

    PubMed

    Liew, S K; Carlson, N W

    1992-05-20

    A simple method for obtaining a collimated near-unity aspect ratio output beam from laser sources with extremely large (> 100:1) aspect ratios is demonstrated by using a distributed-feedback grating-surfaceemitting laser. Far-field power-in-the-bucket measurements of the laser indicate good beam quality with a high Strehl ratio.

  10. Technique Using Axicons For Generating Flat Top Laser Beam Profiles

    NASA Astrophysics Data System (ADS)

    Viswanathan, V. K.; Woodfin, G. L.; Stahl, D.; Carpenter, J. P.; Kyrala, G.

    1983-11-01

    In certain fusion experiments using CO2 lasers, like Helios, it is desired to produce a focal spot several times larger than the nominal focal spot, with a flat beam profile. The typical focal spot in Helios is roughly 70 μm and just defocussing the beam produces beam breakup, with several hot spots with roughly the original diameter, and a gaussian distribution. A number of schemes were tried to achieve a large spot with desired characteristics. These are described in the article. Axicons were found to produce spots with desired characteristics. Axicons are lenses or mirrors having a cone-shaped surface. The various schemes are described, as well as an. experiment in Helios which confirmed that axicons produced the spots with desirable characteristics. Helios is an 8-beam CO2 laser which produces 10 kJ at power in excess of 20 TW. It is currently being used for Laser Fusion studies at the Los Alamos National Laboratory.

  11. Laser-driven atomic-probe-beam diagnostics

    NASA Astrophysics Data System (ADS)

    Knyazev, B. A.; Greenly, J. B.; Hammer, D. A.

    2000-12-01

    A new laser-driven atomic-probe-beam diagnostic (LAD) is proposed for local, time-resolved measurements of electric field and ion dynamics in the accelerating gap of intense ion beam diodes. LAD adds new features to previous Stark-shift diagnostics which have been progressively developed in several laboratories, from passive observation of Stark effect on ion species or fast (charge-exchanged) neutrals present naturally in diodes, to active Stark atomic spectroscopy (ASAS) in which selected probe atoms were injected into the gap and excited to suitable states by resonant laser radiation. The LAD scheme is a further enhancement of ASAS in which the probe atoms are also used as a local (laser-ionized) ion source at an instant of time. Analysis of the ion energy and angular distribution after leaving the gap enables measurement, at the chosen ionization location in the gap, of both electrostatic potential and the development of ion divergence. Calculations show that all of these quantities can be measured with sub-mm and ns resolution. Using lithium or sodium probe atoms, fields from 0.1 to 10 MV/cm can be measured.

  12. A comparison of the physics of Gas Tungsten Arc Welding (GTAW), Electron Beam Welding (EBW), and Laser Beam Welding (LBW)

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    1985-01-01

    The physics governing the applicability and limitations of gas tungsten arc (GTA), electron beam (EB), and laser beam (LB) welding are compared. An appendix on the selection of laser welding systems is included.

  13. Quasi-static modeling of beam-plasma and laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Huang, Chengkun

    Plasma wave wakefields excited by either laser or particle beams can sustain acceleration gradients three orders of magnitude larger than conventional RF accelerators. They are promising for accelerating particles in short distances for applications such as future high-energy colliders, and medical and industrial accelerators. In a Plasma Wakefield Accelerator (PWFA) or a Laser Wakefield Accelerator (LWFA), an intense particle or laser beam drives a plasma wave and generates a strong wakefield which has a phase velocity equal to the velocity of the driver. This wakefield can then be used to accelerate part of the drive beam or a separate trailing beam. The interaction between the plasma and the driver is highly nonlinear and therefore a particle description is required for computer modeling. A highly efficient, fully parallelized, fully relativistic, three-dimensional particle-in-cell code called QuickPIC for simulating plasma and laser wakefield acceleration has been developed. The model is based on the quasi-static or frozen field approximation, which assumes that the drive beam and/or the laser does not evolve during the time it takes for it to pass a plasma particle. The electromagnetic fields of the plasma wake and its associated index of refraction are then used to evolve the driver using very large time steps. This algorithm reduces the computational time by at least 2 to 3 orders of magnitude. Comparison between the new algorithm and a fully explicit model (OSIRIS) are presented. The agreement is excellent for problems of interest. Direction for future work is also discussed. QuickPIC has been used to study the "afterburner" concept. In this concept a fraction of an existing high-energy beam is separated out and used as a trailing beam with the goal that the trailing beam acquires at least twice the energy of the drive beam. Several critical issues such as the efficient transfer of energy and the stable propagation of both the drive and trailing beams in

  14. Direct femtosecond laser ablation of copper with an optical vortex beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anoop, K. K.; Rubano, A.; Marrucci, L.

    Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N=1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (21000) and a deep crater is formed. The nanostructure variation with themore » laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.« less

  15. Resonant Laser Manipulation of an Atomic Beam

    DTIC Science & Technology

    2010-07-01

    similar species such as alkali metals . 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES...resonant laser-atom interaction with other rarefied and collisional solvers for similar species such as alkali metals . Keywords: atomic beam, cesium...a target flow over length scales which push the limits of physical manufacture. The ability to create masks, beam blocks, controlling electric

  16. A nonlinear OPC technique for laser beam control in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Markov, V.; Khizhnyak, A.; Sprangle, P.; Ting, A.; DeSandre, L.; Hafizi, B.

    2013-05-01

    A viable beam control technique is critical for effective laser beam transmission through turbulent atmosphere. Most of the established approaches require information on the impact of perturbations on wavefront propagated waves. Such information can be acquired by measuring the characteristics of the target-scattered light arriving from a small, preferably diffraction-limited, beacon. This paper discusses an innovative beam control approach that can support formation of a tight laser beacon in deep turbulence conditions. The technique employs Brillouin enhanced fourwave mixing (BEFWM) to generate a localized beacon spot on a remote image-resolved target. Formation of the tight beacon doesn't require a wavefront sensor, AO system, or predictive feedback algorithm. Unlike conventional adaptive optics methods which allow wavefront conjugation, the proposed total field conjugation technique is critical for beam control in the presence of strong turbulence and can be achieved by using this non-linear BEFWM technique. The phase information retrieved from the established beacon beam can then be used in conjunction with an AO system to propagate laser beams in deep turbulence.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Halavanau, Aliaksei; Edstrom, Dean; Gai, Wei

    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.

  18. Phase-transition oscillations induced by a strongly focused laser beam

    NASA Astrophysics Data System (ADS)

    Devailly, Clémence; Crauste-Thibierge, Caroline; Petrosyan, Artyom; Ciliberto, Sergio

    2015-11-01

    We report the observation of a surprising phenomenon consisting in a oscillating phase transition which appears in a binary mixture when this is enlightened by a strongly focused infrared laser beam. The mixture is poly-methyl-meth-acrylate (PMMA)-3-octanone, which has an upper critical solution temperature at Tc=306.6 K and volume fraction ϕc=12.8 % [Crauste et al., arXiv:1310.6720, 2013]. We describe the dynamical properties of the oscillations, which are produced by a competition between various effects: the local accumulation of PMMA produced by the laser beam, thermophoresis, and nonlinear diffusion. We show that the main properties of this kind of oscillations can be reproduced in the Landau theory for a binary mixture in which a local driving mechanism, simulating the laser beam, is introduced.

  19. Beam-Riding Analysis of a Parabolic Laser-thermal Thruster

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Scharring, Stefan; Eckel, Hans-Albert; Roeser, Hans-Peter

    2011-11-10

    Flight experiments with laser-propelled vehicles (lightcrafts) are often performed by wire-guidance or with spin-stabilization. Nevertheless, the specific geometry of the lightcraft's optics and nozzle may provide for inherent beam-riding properties. These features are experimentally investigated in a hovering experiment at a small free flight test range with an electron-beam sustained pulsed CO{sub 2} high energy laser. Laser bursts are adapted with a real-time control to lightcraft mass and impulse coupling for ascent and hovering in a quasi equilibrium of forces. The flight dynamics is analyzed with respect to the impulse coupling field vs. attitude, given by the lightcraft's offset andmore » its inclination angle against the beam propagation axis, which are derived from the 3D-reconstruction of the flight trajectory from highspeed recordings. The limitations of the experimental parameters' reproducibility and its impact on flight stability are explored in terms of Julia sets. Solution statements for dynamic stabilization loops are presented and discussed.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Far field beam pattern of one MW combined beam of laser diode array amplifiers for space power transmission

    NASA Technical Reports Server (NTRS)

    Kwon, Jin H.; Lee, Ja H.

    1989-01-01

    The far-field beam pattern and the power-collection efficiency are calculated for a multistage laser-diode-array amplifier consisting of about 200,000 5-W laser diode arrays with random distributions of phase and orientation errors and random diode failures. From the numerical calculation it is found that the far-field beam pattern is little affected by random failures of up to 20 percent of the laser diodes with reference of 80 percent receiving efficiency in the center spot. The random differences in phases among laser diodes due to probable manufacturing errors is allowed to about 0.2 times the wavelength. The maximum allowable orientation error is about 20 percent of the diffraction angle of a single laser diode aperture (about 1 cm). The preliminary results indicate that the amplifier could be used for space beam-power transmission with an efficiency of about 80 percent for a moderate-size (3-m-diameter) receiver placed at a distance of less than 50,000 km.

  2. Electron Acceleration by Beating of Two Intense Cross-Focused Hollow Gaussian Laser Beams in Plasma

    NASA Astrophysics Data System (ADS)

    Mahmoud, Saleh T.; Gauniyal, Rakhi; Ahmad, Nafis; Rawat, Priyanka; Purohit, Gunjan

    2018-01-01

    This paper presents propagation of two cross-focused intense hollow Gaussian laser beams (HGBs) in collisionless plasma and its effect on the generation of electron plasma wave (EPW) and electron acceleration process, when relativistic and ponderomotive nonlinearities are simultaneously operative. Nonlinear differential equations have been set up for beamwidth of laser beams, power of generated EPW, and energy gain by electrons using WKB and paraxial approximations. Numerical simulations have been carried out to investigate the effect of typical laser-plasma parameters on the focusing of laser beams in plasmas and further its effect on power of excited EPW and acceleration of electrons. It is observed that focusing of two laser beams in plasma increases for higher order of hollow Gaussian beams, which significantly enhanced the power of generated EPW and energy gain. The amplitude of EPW and energy gain by electrons is found to enhance with an increase in the intensity of laser beams and plasma density. This study will be useful to plasma beat wave accelerator and in other applications requiring multiple laser beams. Supported by United Arab Emirates University for Financial under Grant No. UPAR (2014)-31S164

  3. Simulation of laser beam reflection at the sea surface modeling and validation

    NASA Astrophysics Data System (ADS)

    Schwenger, Frédéric; Repasi, Endre

    2013-06-01

    A 3D simulation of the reflection of a Gaussian shaped laser beam on the dynamic sea surface is presented. The simulation is suitable for the pre-calculation of images for cameras operating in different spectral wavebands (visible, short wave infrared) for a bistatic configuration of laser source and receiver for different atmospheric conditions. In the visible waveband the calculated detected total power of reflected laser light from a 660nm laser source is compared with data collected in a field trial. Our computer simulation comprises the 3D simulation of a maritime scene (open sea/clear sky) and the simulation of laser beam reflected at the sea surface. The basic sea surface geometry is modeled by a composition of smooth wind driven gravity waves. To predict the view of a camera the sea surface radiance must be calculated for the specific waveband. Additionally, the radiances of laser light specularly reflected at the wind-roughened sea surface are modeled considering an analytical statistical sea surface BRDF (bidirectional reflectance distribution function). Validation of simulation results is prerequisite before applying the computer simulation to maritime laser applications. For validation purposes data (images and meteorological data) were selected from field measurements, using a 660nm cw-laser diode to produce laser beam reflection at the water surface and recording images by a TV camera. The validation is done by numerical comparison of measured total laser power extracted from recorded images with the corresponding simulation results. The results of the comparison are presented for different incident (zenith/azimuth) angles of the laser beam.

  4. Complementary equipment for controlling multiple laser beams on single scanner MPLSM systems

    NASA Astrophysics Data System (ADS)

    Helm, P. Johannes; Nase, Gabriele; Heggelund, Paul; Reppen, Trond

    2010-02-01

    Multi-Photon-Laser-Scanning-Microscopy (MPLSM) now stands as one of the most powerful experimental tools in biology. Specifically, MPLSM based in-vivo studies of structures and processes in the brains of small rodents and imaging in brain-slices have led to considerable progress in the field of neuroscience. Equipment allowing for independent control of two laser-beams, one for imaging and one for photochemical manipulation, strongly enhances any MPLSM platform. Some industrial MPLSM producers have introduced double scanner options in MPLSM systems. Here, we describe the upgrade of a single scanner MPLSM system with equipment that is suitable for independently controlling the beams of two Titanium Sapphire lasers. The upgrade is compatible with any actual MPLSM system and can be combined with any commercial or self assembled system. Making use of the pixel-clock, frame-active and line-active signals provided by the scanner-electronics of the MPLSM, the user can, by means of an external unit, select individual pixels or rectangular ROIs within the field of view of an overview-scan to be exposed, or not exposed, to the beam(s) of one or two lasers during subsequent scans. The switching processes of the laser-beams during the subsequent scans are performed by means of Electro-Optical-Modulators (EOMs). While this system does not provide the flexibility of two-scanner modules, it strongly enhances the experimental possibilities of one-scanner systems provided a second laser and two independent EOMs are available. Even multi-scanner-systems can profit from this development, which can be used to independently control any number of laser beams.

  5. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions.

    PubMed

    Dong, Yu-Hui; Liu, He-Shan; Luo, Zi-Ren; Li, Yu-Qiong; Jin, Gang

    2014-07-01

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differential Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.

  6. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dong, Yu-Hui; Liu, He-Shan; University of Chinese Academy of Sciences, Beijing 100190

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differentialmore » Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.« less

  7. Reshaping a multimode laser beam into a constructed Gaussian beam for generating a thin light sheet.

    PubMed

    Saghafi, Saiedeh; Haghi-Danaloo, Nikoo; Becker, Klaus; Sabdyusheva, Inna; Foroughipour, Massih; Hahn, Christian; Pende, Marko; Wanis, Martina; Bergmann, Michael; Stift, Judith; Hegedus, Balazs; Dome, Balazs; Dodt, Hans-Ulrich

    2018-06-01

    Based on the modal analysis method, we developed a model that describes the output beam of a diode-pumped solid state (DPSS) laser emitting a multimode beam. Measuring the output beam profile in the near field and at the constructed far field the individual modes, their respective contributions, and their optical parameters are determined. Using this information, the beam is optically reshaped into a quasi-Gaussian beam by the interference and superposition of the various modes. This process is controlled by a mode modulator unit that includes different meso-aspheric elements and a soft-aperture. The converted beam is guided into a second optical unit comprising achromatic-aspheric elements to produce a thin light sheet for ultramicroscopy. We found that this light sheet is markedly thinner and exhibits less side shoulders compared with a light sheet directly generated from the output of a DPSS multimode laser. © 2018 The Authors. Journal of Biophotonics published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Wavefront Tilt And Beam Walk Correction For A Pulsed Laser System

    NASA Astrophysics Data System (ADS)

    Bartosewcz, Mike; Tyburski, Joe

    1986-05-01

    The Lockheed Beam Alignment Assembly (BAA) is designed to be a space qualifiable, long life, low bandwidth beam stabilization system. The BAA will stabilize a wandering pulsed laser beam with an input beam tilt of ±750 microradians and translation of ±2.5 mm by two orders of magnitude at the bandwidth of interest. A bandwidth of three hertz was selected to remove laser and optical train thermal drifts and launch induced strain effects. The lambda over twenty RMS wavefront will be maintained in the optics at full power under vacuum test, to demonstrate space qualifiability and optical performance.

  9. Design of refractive laser beam shapers to generate complex irradiance profiles

    NASA Astrophysics Data System (ADS)

    Li, Meijie; Meuret, Youri; Duerr, Fabian; Vervaeke, Michael; Thienpont, Hugo

    2014-05-01

    A Gaussian laser beam is reshaped to have specific irradiance distributions in many applications in order to ensure optimal system performance. Refractive optics are commonly used for laser beam shaping. A refractive laser beam shaper is typically formed by either two plano-aspheric lenses or by one thick lens with two aspherical surfaces. Ray mapping is a general optical design technique to design refractive beam shapers based on geometric optics. This design technique in principle allows to generate any rotational-symmetric irradiance profile, yet in literature ray mapping is mainly developed to transform a Gaussian irradiance profile to a uniform profile. For more complex profiles especially with low intensity in the inner region, like a Dark Hollow Gaussian (DHG) irradiance profile, ray mapping technique is not directly applicable in practice. In order to these complex profiles, the numerical effort of calculating the aspherical surface points and fitting a surface with sufficient accuracy increases considerably. In this work we evaluate different sampling approaches and surface fitting methods. This allows us to propose and demonstrate a comprehensive numerical approach to efficiently design refractive laser beam shapers to generate rotational-symmetric collimated beams with a complex irradiance profile. Ray tracing analysis for several complex irradiance profiles demonstrates excellent performance of the designed lenses and the versatility of our design procedure.

  10. Fabrication of porous microrings via laser printing and ion-beam post-etching

    NASA Astrophysics Data System (ADS)

    Syubaev, S.; Nepomnyashchiy, A.; Mitsai, E.; Pustovalov, E.; Vitrik, O.; Kudryashov, S.; Kuchmizhak, A.

    2017-08-01

    Pulsed-laser dry printing of noble-metal microrings with a tunable internal porous structure, which can be revealed via an ion-beam etching post-procedure, was demonstrated. The abundance and average size of the pores inside the microrings were shown to be tuned in a wide range by varying the incident pulse energy and a nitrogen doping level controlled in the process of magnetron deposition of the gold film in the appropriate gaseous environment. The fabricated porous microrings were shown to provide many-fold near-field enhancement of incident electromagnetic fields, which was confirmed by mapping of the characteristic Raman band of a nanometer-thick covering layer of Rhodamine 6G dye molecules and supporting finite-difference time-domain calculations. The proposed laser-printing/ion-beam etching approach is demonstrated to be a unique tool aimed at designing and fabricating multifunctional plasmonic structures and metasurfaces for spectroscopic bioidentification based on surface-enhanced infrared absorption, Raman scattering, and photoluminescence detection schemes.

  11. Saturation of multi-laser beams laser-plasma instabilities from stochastic ion heating

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Michel, P.; Williams, E. A.; Divol, L.

    2013-05-15

    Cross-beam energy transfer (CBET) has been used as a tool on the National Ignition Facility (NIF) since the first energetics experiments in 2009 to control the energy deposition in ignition hohlraums and tune the implosion symmetry. As large amounts of power are transferred between laser beams at the entrance holes of NIF hohlraums, the presence of many overlapping beat waves can lead to stochastic ion heating in the regions where laser beams overlap [P. Michel et al., Phys. Rev. Lett. 109, 195004 (2012)]. This increases the ion acoustic velocity and modifies the ion acoustic waves’ dispersion relation, thus reducing themore » plasma response to the beat waves and the efficiency of CBET. This pushes the plasma oscillations driven by CBET in a regime where the phase velocities are much smaller than both the electron and ion thermal velocities. CBET gains are derived for this new regime and generalized to the case of multi ion species plasmas.« less

  12. Laser beam machining of polycrystalline diamond for cutting tool manufacturing

    NASA Astrophysics Data System (ADS)

    Wyszyński, Dominik; Ostrowski, Robert; Zwolak, Marek; Bryk, Witold

    2017-10-01

    The paper concerns application of DPSS Nd: YAG 532nm pulse laser source for machining of polycrystalline WC based diamond inserts (PCD). The goal of the research was to determine optimal laser cutting parameters for cutting tool shaping. Basic criteria to reach the goal was cutting edge quality (minimalization of finishing operations), material removal rate (time and cost efficiency), choice of laser beam characteristics (polarization, power, focused beam diameter). The research was planned and realised and analysed according to design of experiment rules (DOE). The analysis of the cutting edge was prepared with use of Alicona Infinite Focus measurement system.

  13. Multifractality of laser beam spatial intensity in a turbulent medium

    NASA Astrophysics Data System (ADS)

    Barille, Régis; Lapenna, Paolo

    2006-05-01

    We present the results of a laser beam passing through a turbulent medium. First we measure the geometric parameters and the spatial coherence of the beam as a function of wind velocities. A multifractal detrended fluctuation analysis algorithm is applied to determine the multifractal scaling behavior of the intensity patterns. The measurements are fitted with models used in the analysis of river runoff records. We show the surprising result that the multifractality decreases when the spatial coherence of the laser is decreased. Universal scaling properties could be applied to the spatial characterization of a laser propagating in a turbulent medium or random medium.

  14. High efficiency and high-energy intra-cavity beam shaping laser

    NASA Astrophysics Data System (ADS)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-09-01

    We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%.

  15. Laser marking on soda-lime glass by laser-induced backside wet etching with two-beam interference

    NASA Astrophysics Data System (ADS)

    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.

  16. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    PubMed Central

    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

  17. RFQ beam cooler and buncher for collinear laser spectroscopy of rare isotopes

    NASA Astrophysics Data System (ADS)

    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).

  18. Modulatory frequency of lasers in connection to laser beam therapeutic effect

    NASA Astrophysics Data System (ADS)

    Kucerova, Hana; Bartova, Jirina; Himmlova, Lucia; Dostalova, Tatjana; Mazanek, Jiri

    1998-04-01

    The subject of this work follows changes of the sIgA and albumin levels in the saliva of 48 patients treated after the extraction of their lower molars with either diode or He-Ne biostimulatory laser, using different modulatory frequencies (5 Hz, 292 Hz, 9000 Hz). The results were compared to the sIgA and albumin levels in the saliva of the control, i.e. not- treated group. For the tests radial immunodiffusion (RID) method was used (commercial RID kit of the Binding Site, Birmingham, Great Britain). Appropriately chosen laser beam modulatory frequency should influence the increase in the sIgA and albumin levels against the base level. In our study, this hypothesis was confirmed in the group treated with the frequency of 292 Hz and 9000 Hz (both diode GaAIAs, 670 nm, red, 20 mW, energy density 1.5 Jcm2) on albumin levels and 9000 Hz on sIgA levels. The changes of the levels of the watched markers versus the control group were at this frequencies (292 Hz and 9000 Hz) statistically significant. At the others used frequencies (5 Hz diode laser and 5 Hz He-Ne laser) the changes of the levels of the watched markers versus control group were statistically insignificant. The aim of this study was to contribute to the evaluation of specific modulatory frequencies (5 Hz, 292 Hz, 9000 Hz) for therapeutical use in a given pathological case of the oral cavity. We can conclude that using frequency 9000 Hz had best immunomodulatory effect.

  19. Variance of laser-beam intensity fluctuations during snowfall

    NASA Astrophysics Data System (ADS)

    Zhukov, A. F.; Kabanov, M. F.; Tsvyk, R. Sh.

    1985-02-01

    The results of an experimental study of the factors affecting the variance of laser-beam intensity fluctuations during snowfall are analyzed. The investigation covered short (L = 130 m) and long (390, 650, and 1310 m) beam paths, and used narrow diverging and wide collimated beams with Omega = 0.075 and 54, respectively, produced by the same laser. The dimensions of snow particles varied from 0.1 to 3.0 cm. It is shown that a distance l exists, such that when L is much less than l a geometric shadow of a snow particle is formed, whereas for L much greater than l a complex interference pattern can be seen. In both cases, the motion of a particle leads to intensity fluctuations. Furthermore, it was found that the proportionality coefficient for Omega = 54 is near 1 and depends insignificantly on the particle size; for a diverging beam, however, it changes from 0.3 to 0.8 as the maximum particle diameter increases from 0.1 to 3 cm.

  20. Laser diode stack beam shaping for efficient and compact long-range laser illuminator design

    NASA Astrophysics Data System (ADS)

    Lutz, Y.; Poyet, J. M.

    2014-04-01

    Laser diode stacks are interesting laser sources for active imaging illuminators. They allow the accumulation of large amounts of energy in multi-pulse mode, which is best suited for long-range image recording. Even when the laser diode stacks are equipped with fast-axis collimation (FAC) and slow-axis collimation (SAC) micro-lenses, their beam parameter products BPP are not compatible with direct use in highly efficient and compact illuminators. This is particularly true when narrow divergences are required such as for long-range applications. A solution to overcome these difficulties is to enhance the poor slow-axis BPP by virtually restacking the laser diode stack. We present a beam shaping and homogenization method that is low-cost and efficient and has low alignment sensitivity. After conducting simulations, we have realized and characterized the illuminator. A compact long-range laser illuminator has been set up with a divergence of 3.5×2.6 mrad and a global efficiency of 81%. Here, a projection lens with a clear aperture of 62 mm and a focal length of 571 mm was used.

  1. Laser beam uniformity and stability using homogenizer-based fiber optic launch method: square core fiber delivery

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.

    2011-03-01

    Over the years, technological achievements within the laser medical diagnostic, treatment, and therapy markets have led to ever increasing requirements for greater control of critical laser beam parameters. Increased laser power/energy stabilization, temporal and spatial beam shaping and flexible laser beam delivery systems with ergonomic focusing or imaging lens systems are sought by leading medical laser system producers. With medical procedures that utilize laser energy, there is a constant emphasis on reducing adverse effects that come about by the laser itself or its optical system, but even when these variables are well controlled the medical professional will still need to deal with the multivariate nature of the human body. Focusing on the variables that can be controlled, such as accurate placement of the laser beam where it will expose a surface being treated as well as laser beam shape and uniformity is critical to minimizing adverse conditions. This paper covers the use of fiber optic beam delivery as a means of defining the beam shape (intensity/power distribution uniformity) at the target plane as well as the use of fiber delivery as a means to allow more flexible articulation of the laser beam over the surface being treated. The paper will present a new concept of using a square core fiber beam delivery design utilizing a unique micro lens array (MLA) launch method that improves the overall stability of the system, by minimizing the impact of the laser instability. The resulting performance of the prototype is presented to demonstrate its stability in comparison to simple lens launch techniques, with an emphasis on homogenization and articulated fiber delivery.

  2. Laser power beaming applications and technology

    NASA Astrophysics Data System (ADS)

    Burke, Robert J.; Cover, Ralph A.; Curtin, Mark S.; Dinius, R.; Lampel, Michael C.

    1994-05-01

    Beaming laser energy to spacecraft has important economic potential. It promises significant reduction in the cost of access to space, for commercial and government missions. While the potential payoff is attractive, existing technologies perform the same missions and the keys to market penetration for power beaming are a competitive cost and a schedule consistent with customers' plans. Rocketdyne is considering these questions in the context of a commercial enterprise -- thus, evaluation of the requirements must be done based on market assessments and recognition that significant private funding will be involved. It is in the context of top level business considerations that the technology requirements are being assessed and the program being designed. These considerations result in the essential elements of the development program. Since the free electron laser is regarded as the `long pole in the tent,' this paper summarizes Rocketdyne's approach for a timely, cost-effective program to demonstrate an FEL capable of supporting an initial operating capability.

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

    DOE PAGES

    Sarri, G.; Warwick, J.; Schumaker, W.; ...

    2016-10-18

    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. Lastly, the results obtained indicate that current technology allowsmore » to create, in a compact setup, positron beams suitable for injection in radio-frequency accelerators.« less

  4. Higher-order paraxial theory of the propagation of ring rippled laser beam in plasma: Relativistic ponderomotive regime

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Purohit, Gunjan, E-mail: gunjan75@gmail.com; Rawat, Priyanka; Chauhan, Prashant

    This article presents higher-order paraxial theory (non-paraxial theory) for the ring ripple formation on an intense Gaussian laser beam and its propagation in plasma, taking into account the relativistic-ponderomotive nonlinearity. The intensity dependent dielectric constant of the plasma has been determined for the main laser beam and ring ripple superimposed on the main laser beam. The dielectric constant of the plasma is modified due to the contribution of the electric field vector of ring ripple. Nonlinear differential equations have been formulated to examine the growth of ring ripple in plasma, self focusing of main laser beam, and ring rippled lasermore » beam in plasma using higher-order paraxial theory. These equations have been solved numerically for different laser intensities and plasma frequencies. The well established experimental laser and plasma parameters are used in numerical calculation. It is observed that the focusing of the laser beams (main and ring rippled) becomes fast in the nonparaxial region by expanding the eikonal and other relevant quantities up to the fourth power of r. The splitted profile of laser beam in the plasma is observed due to uneven focusing/defocusing of the axial and off-axial rays. The growths of ring ripple increase when the laser beam intensity increases. Furthermore, the intensity profile of ring rippled laser beam gets modified due to the contribution of growth rate.« less

  5. Wavefront control of high-power laser beams in the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Zacharias, Richard A.; Bliss, Erlan S.; Winters, Scott; Sacks, Richard A.; Feldman, Mark; Grey, Andrew; Koch, Jeffrey A.; Stolz, Christopher J.; Toeppen, John S.; Van Atta, Lewis; Woods, Bruce W.

    2000-04-01

    The use of lasers as the driver for inertial confinement fusion and weapons physics experiments is based on their ability to produce high-energy short pulses in a beam with low divergence. Indeed, the focusability of high quality laser beams far exceeds alternate technologies and is a major factor in the rationale for building high power lasers for such applications. The National Ignition Facility (NIF) is a large, 192-beam, high-power laser facility under construction at the Lawrence Livermore National Laboratory for fusion and weapons physics experiments. Its uncorrected minimum focal spot size is limited by laser system aberrations. The NIF includes a Wavefront Control System to correct these aberrations to yield a focal spot small enough for its applications. Sources of aberrations to be corrected include prompt pump-induced distortions in the laser amplifiers, previous-shot thermal distortions, beam off-axis effects, and gravity, mounting, and coating-induced optic distortions. Aberrations from gas density variations and optic-manufacturing figure errors are also partially corrected. This paper provides an overview of the NIF Wavefront Control System and describes the target spot size performance improvement it affords. It describes provisions made to accommodate the NIF's high fluence (laser beam and flashlamp), large wavefront correction range, wavefront temporal bandwidth, temperature and humidity variations, cleanliness requirements, and exception handling requirements (e.g. wavefront out-of-limits conditions).

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Stable generation of GeV-class electron beams from self-guided laser-plasma channels

    NASA Astrophysics Data System (ADS)

    Hafz, Nasr A. M.; Jeong, Tae Moon; Choi, Il Woo; Lee, Seong Ku; Pae, Ki Hong; Kulagin, Victor V.; Sung, Jae Hee; Yu, Tae Jun; Hong, Kyung-Han; Hosokai, Tomonao; Cary, John R.; Ko, Do-Kyeong; Lee, Jongmin

    2008-09-01

    Table-top laser-driven plasma accelerators are gaining attention for their potential use in miniaturizing future high-energy accelerators. By irradiating gas jet targets with ultrashort intense laser pulses, the generation of quasimonoenergetic electron beams was recently observed. Currently, the stability of beam generation and the ability to scale to higher electron beam energies are critical issues for practical laser acceleration. Here, we demonstrate the first generation of stable GeV-class electron beams from stable few-millimetre-long plasma channels in a self-guided wakefield acceleration process. As primary evidence of the laser wakefield acceleration in a bubble regime, we observed a boost of both the electron beam energy and quality by reducing the plasma density and increasing the plasma length in a 1-cm-long gas jet. Subsequent three-dimensional simulations show the possibility of achieving even higher electron beam energies by minimizing plasma bubble elongation, and we anticipate dramatic increases in beam energy and quality in the near future. This will pave the way towards ultracompact, all-optical electron beam accelerators and their applications in science, technology and medicine.

  8. Laser beamed power - Satellite demonstration applications

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Westerlund, Larry H.

    1992-01-01

    Feasibility of using a ground-based laser to beam light to the solar arrays of orbiting satellites to a level sufficient to provide the operating power required is discussed. An example case of a GEO communications satellite near the end of life due to radiation damage of the solar arrays or battery failure is considered. It is concluded that the commercial satellite industry should be able to reap significant economic benefits through the use of power beaming which is capable of providing supplemental power for satellites with failing arrays, or primary power for failed batteries.

  9. Feedback stabilization of quantum cascade laser beams for stand-off applications

    NASA Astrophysics Data System (ADS)

    Müller, Reik; Kendziora, Christopher A.; Furstenberg, Robert

    2017-05-01

    Techniques which apply tunable quantum cascade lasers (QCLs) for target illumination suffer from fluctuations of the laser beam direction. This manuscript describes a method to stabilize the beam direction by using an active feedback loop. This approach corrects and stabilizes the laser pointing direction using the signal from a 4-element photo sensor as input to control an active 2 dimensional Galvo mirror system. Results are presented for measurements using known perturbations as well as actual mode hops intrinsic to external cavity QCL during wavelength tuning.

  10. An analytical reconstruction model of the spread-out Bragg peak using laser-accelerated proton beams.

    PubMed

    Tao, Li; Zhu, Kun; Zhu, Jungao; Xu, Xiaohan; Lin, Chen; Ma, Wenjun; Lu, Haiyang; Zhao, Yanying; Lu, Yuanrong; Chen, Jia-Er; Yan, Xueqing

    2017-07-07

    With the development of laser technology, laser-driven proton acceleration provides a new method for proton tumor therapy. However, it has not been applied in practice because of the wide and decreasing energy spectrum of laser-accelerated proton beams. In this paper, we propose an analytical model to reconstruct the spread-out Bragg peak (SOBP) using laser-accelerated proton beams. Firstly, we present a modified weighting formula for protons of different energies. Secondly, a theoretical model for the reconstruction of SOBPs with laser-accelerated proton beams has been built. It can quickly calculate the number of laser shots needed for each energy interval of the laser-accelerated protons. Finally, we show the 2D reconstruction results of SOBPs for laser-accelerated proton beams and the ideal situation. The final results show that our analytical model can give an SOBP reconstruction scheme that can be used for actual tumor therapy.

  11. Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Yun; Huang, Chunning; Aleksandrov, Alexander V

    2013-01-01

    We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstrationmore » of particle beam profile diagnostics using fiber optic laser pulse transmission line.« less

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

    PubMed

    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.

  13. High-Brightness Lasers with Spectral Beam Combining on Silicon

    NASA Astrophysics Data System (ADS)

    Stanton, Eric John

    Modern implementations of absorption spectroscopy and infrared-countermeasures demand advanced performance and integration of high-brightness lasers, especially in the molecular fingerprint spectral region. These applications, along with others in communication, remote-sensing, and medicine, benefit from the light source comprising a multitude of frequencies. To realize this technology, a single multi-spectral optical beam of near-diffraction-limited divergence is created by combining the outputs from an array of laser sources. Full integration of such a laser is possible with direct bonding of several epitaxially-grown chips to a single silicon (Si) substrate. In this platform, an array of lasers is defined with each gain material, creating a densely spaced set of wavelengths similar to wavelength division multiplexing used in communications. Scaling the brightness of a laser typically involves increasing the active volume to produce more output power. In the direction transverse to the light propagation, larger geometries compromise the beam quality. Lengthening the cavity provides only limited scaling of the output power due to the internal losses. Individual integrated lasers have low brightness due to combination of thermal effects and high optical intensities. With heterogeneous integration, many lasers can be spectrally combined on a single integrated chip to scale brightness in a compact platform. Recent demonstrations of 2.0-microm diode and 4.8-microm quantum cascade lasers on Si have extended this heterogeneous platform beyond the telecommunications band to the mid-infrared. In this work, low-loss beam combining elements spanning the visible to the mid-infrared are developed and a high-brightness multi-spectral laser is demonstrated in the range of 4.6-4.7-microm wavelengths. An architecture is presented where light is combined in multiple stages: first within the gain-bandwidth of each laser material and then coarsely between each spectral band to a

  14. Pulsed Nd:YAG laser beam drilling: A review

    NASA Astrophysics Data System (ADS)

    Gautam, Girish Dutt; Pandey, Arun Kumar

    2018-03-01

    Laser beam drilling (LBD) is one of non contact type unconventional machining process that are employed in machining of stiff and high-strength materials, high strength temperature resistance materials such as; metal alloys, ceramics, composites and superalloys. Most of these materials are difficult-to-machine by using conventional machining methods. Also, the complex and precise holes may not be obtained by using the conventional machining processes which may be obtained by using unconventional machining processes. The laser beam drilling in one of the most important unconventional machining process that may be used for the machining of these materials with satisfactorily. In this paper, the attention is focused on the experimental and theoretical investigations on the pulsed Nd:YAG laser drilling of different categories of materials such as ferrous materials, non-ferrous materials, superalloys, composites and Ceramics. Moreover, the review has been emphasized by the use of pulsed Nd:YAG laser drilling of different materials in order to enhance productivity of this process without adverse effects on the drilled holes quality characteristics. Finally, the review is concluded with the possible scope in the area of pulsed Nd:YAG laser drilling. This review work may be very useful to the subsequent researchers in order to give an insight in the area of pulsed Nd:YAG laser drilling of different materials and research gaps available in this area.

  15. Novel beam delivery fibers for delivering flat-top beams with controlled BPP for high power CW and pulsed laser applications

    NASA Astrophysics Data System (ADS)

    Jollivet, C.; Farley, K.; Conroy, M.; Abramczyk, J.; Belke, S.; Becker, F.; Tankala, K.

    2016-03-01

    Single-mode (SM) kW-class fiber lasers are the tools of choice for material processing applications such as sheet metal cutting and welding. However, application requirements include a flat-top intensity profile and specific beam parameter product (BPP). Here, Nufern introduces a novel specialty fiber technology capable of converting a SM laser beam into a flat-top beam suited for these applications. The performances are demonstrated using a specialty fiber with 100 μm pure silica core, 0.22 NA surrounded by a 120 μm fluorine-doped layer and a 360 μm pure silica cladding, which was designed to match the conventional beam delivery fibers. A SM fiber laser operating at a wavelength of 1.07 μm and terminated with a large-mode area (LMA) fiber with 20 μm core and 0.06 NA was directly coupled in the core of the flat-top specialty fiber using conventional splicing technique. The output beam profile and BPP were characterized first with a low-power source and confirmed using a 2 kW laser and we report a beam transformation from a SM beam into a flat-top intensity profile beam with a 3.8 mm*mrad BPP. This is, to the best of our knowledge, the first successful beam transformation from SM to MM flat-top with controlled BPP in a single fiber integrated in a multi-kW all-fiber system architecture.

  16. A large capacity time division multiplexed (TDM) laser beam combining technique enabled by nanosecond speed KTN deflector

    NASA Astrophysics Data System (ADS)

    Yin, Stuart (Shizhuo); Chao, Ju-Hung; Zhu, Wenbin; Chen, Chang-Jiang; Campbell, Adrian; Henry, Michael; Dubinskiy, Mark; Hoffman, Robert C.

    2017-08-01

    In this paper, we present a novel large capacity (a 1000+ channel) time division multiplexing (TDM) laser beam combining technique by harnessing a state-of-the-art nanosecond speed potassium tantalate niobate (KTN) electro-optic (EO) beam deflector as the time division multiplexer. The major advantages of TDM approach are: (1) large multiplexing capability (over 1000 channels), (2) high spatial beam quality (the combined beam has the same spatial profile as the individual beam), (3) high spectral beam quality (the combined beam has the same spectral width as the individual beam, and (4) insensitive to the phase fluctuation of individual laser because of the nature of the incoherent beam combining. The quantitative analyses show that it is possible to achieve over one hundred kW average power, single aperture, single transverse mode solid state and/or fiber laser by pursuing this innovative beam combining method, which represents a major technical advance in the field of high energy lasers. Such kind of 100+ kW average power diffraction limited beam quality lasers can play an important role in a variety of applications such as laser directed energy weapons (DEW) and large-capacity high-speed laser manufacturing, including cutting, welding, and printing.

  17. Green frequency-doubled laser-beam propagation in high-temperature hohlraum plasmas.

    PubMed

    Niemann, C; Berger, R L; Divol, L; Froula, D H; Jones, O; Kirkwood, R K; Meezan, N; Moody, J D; Ross, J; Sorce, C; Suter, L J; Glenzer, S H

    2008-02-01

    We demonstrate propagation and small backscatter losses of a frequency-doubled (2omega) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of 2 higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2omega laser-beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggest that good laser coupling into fusion hohlraums using 2omega light is possible.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Shipboard Measurements of 0.6328 Micrometer Laser Beam Extinction in the Marine Boundary Layer

    DTIC Science & Technology

    1976-06-01

    hdl.handle.net/10945/17938 Downloaded from NPS Archive: Calhoun SHIPBOARD MEASUREMENTS OF 0.6328 MICROMETER LASER BEAM EXTINCTION IN THE MARINE BOUNDARY LAYER P...W. Parish NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS SHIPBOARD MEASUREMENTS OF 0.6328 MICROMETER LASER BEAM EXTINCTION IN THE MARINE...CLASSIFICATION OF THIS PtkGE(Wh»n Dmta Enffd) Shipboard Measurements of 0.6328 Micrometer Laser Beam Extinction in the Marine Boundary Layer by P. W

  20. Development of high damage threshold multilayer thin film beam combiner for laser application

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nand, Mangla, E-mail: mnand@rrcat.gov.in; Babita,; Jena, S.

    2016-05-23

    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/cm{sup 2} 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.

  1. Development of high damage threshold multilayer thin film beam combiner for laser application

    NASA Astrophysics Data System (ADS)

    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.

  2. Beam transport and monitoring for laser plasma accelerators

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Sokollik, T.; van Tilborg, J.; Gonsalves, A. J.; Shaw, B.; Shiraishi, S.; Mittal, R.; De Santis, S.; Byrd, J. M.; Leemans, W.

    2012-12-01

    The controlled transport and imaging of relativistic electron beams from laser plasma accelerators (LPAs) are critical for their diagnostics and applications. Here we present the design and progress in the implementation of the transport and monitoring system for an undulator based electron beam diagnostic. Miniature permanent-magnet quadrupoles (PMQs) are employed to realize controlled transport of the LPA electron beams, and cavity based electron beam position monitors for non-invasive beam position detection. Also presented is PMQ calibration by using LPA electron beams with broadband energy spectrum. The results show promising performance for both transporting and monitoring. With the proper transport system, XUV-photon spectra from THUNDER will provide the momentum distribution of the electron beam with the resolution above what can be achieved by the magnetic spectrometer currently used in the LOASIS facility.

  3. Delivering pump light to a laser gain element while maintaining access to the laser beam

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Payne, Stephen A.

    2001-01-01

    A lens duct is used for pump delivery and the laser beam is accessed through an additional component called the intermediate beam extractor which can be implemented as part of the gain element, part of the lens duct or a separate component entirely.

  4. Determination of Cross-Sectional Area of Focused Picosecond Gaussian Laser Beam

    NASA Technical Reports Server (NTRS)

    Ledesma, Rodolfo; Fitz-Gerald, James; Palmieri, Frank; Connell, John

    2018-01-01

    Measurement of the waist diameter of a focused Gaussian-beam at the 1/e(sup 2) intensity, also referred to as spot size, is key to determining the fluence in laser processing experiments. Spot size measurements are also helpful to calculate the threshold energy and threshold fluence of a given material. This work reports an application of a conventional method, by analyzing single laser ablated spots for different laser pulse energies, to determine the cross-sectional area of a focused Gaussian-beam, which has a nominal pulse width of approx. 10 ps. Polished tungsten was used as the target material, due to its low surface roughness and low ablation threshold, to measure the beam waist diameter. From the ablative spot measurements, the ablation threshold fluence of the tungsten substrate was also calculated.

  5. Study on laser welding of austenitic stainless steel by varying incident angle of pulsed laser beam

    NASA Astrophysics Data System (ADS)

    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.

  6. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers.

    PubMed

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-01-17

    Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2-values of the laser with lowest spatial coherence. The principle of spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future.

  7. Investigations of Self-Pumped Phase Conjugate Laser Beams and Coherence Length

    DTIC Science & Technology

    1993-03-01

    experiment was designed at the Naval Postgraduate School. This experimental arrangement involved a smaller argon-ion laser and a laser spectrometer...change in coherence length was observed in a phase conjugate laser beam. Eperimental results obtained in these experiments highlight the fact that

  8. Laser beam joining of optical fibers in silicon V-grooves

    NASA Astrophysics Data System (ADS)

    Kaufmann, Stefan; Otto, Andreas; Luz, Gerhard

    2000-06-01

    The increasing use of optical data transmission systems and the development of new optical components require adjustment-insensitive and reliable joining and assembling techniques. The state of the art includes the utilization of silicon submounts with anisotropically etched V-grooves. Several glass fibers are fixed in these V-grooves with adhesive. Adhesive bonds tend towards degradation under the influence of temperature and moisture. For this reason, the alternative joining processes laser beam welding and laser beam soldering are relevant. The goal is a reliable joining of optical fibers in V-grooves without damage to the fibers or the silicon submount. Because of the anomaly of silicon during phase transformation, a positive joining can be realized by laser beam welding. A melt pool is created through the energy of a Nd:YAG-laser pulse. During solidification, the volume of silicon increases and a bump is formed in the center. Experiments have shown that this phenomenon can be used for joining optical fibers in silicon-V-grooves. With suitable parameters the silicon flows half around the fiber during solidification. For each fiber, several welding points are necessary. Another promising joining method is laser bema soldering. In this case, a second silicon sheet with a solder deposit is placed on the fibers which lie in the V-grooves of the metallized silicon submount. The laser heats the upper silicon until the solder metals by heat conduction.

  9. Concepts for laser beam parameter monitoring during industrial mass production

    NASA Astrophysics Data System (ADS)

    Harrop, Nicholas J.; Maerten, Otto; Wolf, Stefan; Kramer, Reinhard

    2017-02-01

    In today's industrial mass production, lasers have become an established tool for a variety of processes. As with any other tool, mechanical or otherwise, the laser and its ancillary components are prone to wear and ageing. Monitoring of these ageing processes at full operating power of an industrial laser is challenging for a range of reasons. Not only the damage threshold of the measurement device itself, but also cycle time constraints in industrial processing are just two of these challenges. Power measurement, focus spot size or full beam caustic measurements are being implemented in industrial laser systems. The scope of the measurement and the amount of data collected is limited by the above mentioned cycle time, which in some cases can only be a few seconds. For successful integration of these measurement systems into automated production lines, the devices must be equipped with standardized communication interfaces, enabling a feedback loop from the measurement device to the laser processing systems. If necessary these measurements can be performed before each cycle. Power is determined with either static or dynamic calorimetry while camera and scanning systems are used for beam profile analysis. Power levels can be measured from 25W up to 20 kW, with focus spot sizes between 10μm and several millimeters. We will show, backed by relevant statistical data, that defects or contamination of the laser beam path can be detected with applied measurement systems, enabling a quality control chain to prevent process defects.

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

    PubMed

    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. © 2012 Optical Society of America

  11. With a laser beam centered on its panel of photovoltaic cells, a model plane makes the first flight of an aircraft powered by a laser beam inside a building at NASA Marshall.

    NASA Image and Video Library

    2003-09-18

    With a laser beam centered on its panel of photovoltaic cells, a lightweight model plane makes the first flight of an aircraft powered by a laser beam inside a building at NASA Marshall Space Flight Center.

  12. 2.1 μm high-power laser diode beam combining(Conference Presentation)

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    Laser power and brightness scaling, in "eye safe" atmospheric transmission windows, is driving laser system research and development. High power lasers with good beam quality, at wavelength around 2.1 µm, are necessary for optical countermeasure applications. For such applications, focusing on efficiency and compactness of the system is mandatory. In order to cope with these requirements, one must consider the use of laser diodes which emit directly in the desired spectral region. The challenge for these diodes is to maintain a good beam quality factor as the output power increases. 2 µm diodes with excellent beam quality in both axes are available with output powers of 100 mW. Therefore, in order to reach multi-watt of average output power, broad-area single emitters and beam combining becomes relevant. Different solutions have been implemented in the 1.9 to 2 µm wavelength range, one of which is to stack multiple emitter bars reaching more than one hundred watt, while another is a fibre coupled diode module. The beam propagation factor of these systems is too high for long atmospheric propagation applications. Here we describe preliminary results on non-coherent beam combining of 2.1 µm high power Fabry-Perot GaSb laser diodes supplied by Brolis Semiconductors Ltd. First we evaluated single mode diodes (143 mW) with good beam quality (M2 < 1.5 for slow axis and < 1.1 for fast axis). Then we characterized broad-area single emitter diodes (808 mW) with an electrical-to-optical efficiency of 19 %. The emitter width was 90 µm with a cavity length of 1.5 mm. In our experiments we found that the slow axis multimode output beam consisted of two symmetric lobes with a total full width at half maximum (FWHM) divergence angle of 25 degrees, corresponding to a calculated beam quality factor of M2 = 25. The fast axis divergence was specified to be 44 degrees, with an expected beam quality factor close to the diffraction limit, which informed our selection of collimation

  13. Theoretical and experimental research on laser-beam homogenization based on metal gauze

    NASA Astrophysics Data System (ADS)

    Liu, Libao; Zhang, Shanshan; Wang, Ling; Zhang, Yanchao; Tian, Zhaoshuo

    2018-03-01

    Method of homogenization of CO2 laser heating by means of metal gauze is researched theoretically and experimentally. Distribution of light-field of expanded beam passing through metal gauze was numerically calculated with diffractive optical theory and the conclusion is that method is effective, with comparing the results to the situation without metal gauze. Experimentally, using the 30W DC discharge laser as source and enlarging beam by concave lens, with and without metal gauze, beam intensity distributions in thermal paper were compared, meanwhile the experiments based on thermal imager were performed. The experimental result was compatible with theoretical calculation, and all these show that the homogeneity of CO2 laser heating could be enhanced by metal gauze.

  14. Energy exchange between a laser beam and charged particles using inverse transition radiation and method for its use

    DOEpatents

    Kimura, Wayne D.; Romea, Richard D.; Steinhauer, Loren C.

    1998-01-01

    A method and apparatus for exchanging energy between relativistic charged particles and laser radiation using inverse diffraction radiation or inverse transition radiation. The beam of laser light is directed onto a particle beam by means of two optical elements which have apertures or foils through which the particle beam passes. The two apertures or foils are spaced by a predetermined distance of separation and the angle of interaction between the laser beam and the particle beam is set at a specific angle. The separation and angle are a function of the wavelength of the laser light and the relativistic energy of the particle beam. In a diffraction embodiment, the interaction between the laser and particle beams is determined by the diffraction effect due to the apertures in the optical elements. In a transition embodiment, the interaction between the laser and particle beams is determined by the transition effect due to pieces of foil placed in the particle beam path.

  15. Refractive Index Seen by a Probe Beam Interacting with a Laser-Plasma System

    DOE PAGES

    Turnbull, D.; Goyon, C.; Kemp, G. E.; ...

    2017-01-05

    Here, we report the first complete set of measurements of a laser-plasma optical system’s refractive index, as seen by a second probe laser beam, as a function of the relative wavelength shift between the two laser beams. Both the imaginary and real refractive index components are found to be in good agreement with linear theory using plasma parameters measured by optical Thomson scattering and interferometry; the former is in contrast to previous work and has implications for crossed-beam energy transfer in indirect-drive inertial confinement fusion, and the latter is measured for the first time. The data include the first demonstrationmore » of a laser-plasma polarizer with 85$-$87% extinction for the particular laser and plasma parameters used in this experiment, complementing the existing suite of high-power, tunable, and ultrafast plasma-based photonic devices.« less

  16. Refractive Index Seen by a Probe Beam Interacting with a Laser-Plasma System

    NASA Astrophysics Data System (ADS)

    Turnbull, D.; Goyon, C.; Kemp, G. E.; Pollock, B. B.; Mariscal, D.; Divol, L.; Ross, J. S.; Patankar, S.; Moody, J. D.; Michel, P.

    2017-01-01

    We report the first complete set of measurements of a laser-plasma optical system's refractive index, as seen by a second probe laser beam, as a function of the relative wavelength shift between the two laser beams. Both the imaginary and real refractive index components are found to be in good agreement with linear theory using plasma parameters measured by optical Thomson scattering and interferometry; the former is in contrast to previous work and has implications for crossed-beam energy transfer in indirect-drive inertial confinement fusion, and the latter is measured for the first time. The data include the first demonstration of a laser-plasma polarizer with 85 %- 87 % extinction for the particular laser and plasma parameters used in this experiment, complementing the existing suite of high-power, tunable, and ultrafast plasma-based photonic devices.

  17. Refractive Index Seen by a Probe Beam Interacting with a Laser-Plasma System.

    PubMed

    Turnbull, D; Goyon, C; Kemp, G E; Pollock, B B; Mariscal, D; Divol, L; Ross, J S; Patankar, S; Moody, J D; Michel, P

    2017-01-06

    We report the first complete set of measurements of a laser-plasma optical system's refractive index, as seen by a second probe laser beam, as a function of the relative wavelength shift between the two laser beams. Both the imaginary and real refractive index components are found to be in good agreement with linear theory using plasma parameters measured by optical Thomson scattering and interferometry; the former is in contrast to previous work and has implications for crossed-beam energy transfer in indirect-drive inertial confinement fusion, and the latter is measured for the first time. The data include the first demonstration of a laser-plasma polarizer with 85%-87% extinction for the particular laser and plasma parameters used in this experiment, complementing the existing suite of high-power, tunable, and ultrafast plasma-based photonic devices.

  18. Beam transport and monitoring for laser plasma accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nakamura, K.; Sokollik, T.; Tilborg, J. van

    The controlled transport and imaging of relativistic electron beams from laser plasma accelerators (LPAs) are critical for their diagnostics and applications. Here we present the design and progress in the implementation of the transport and monitoring system for an undulator based electron beam diagnostic. Miniature permanent-magnet quadrupoles (PMQs) are employed to realize controlled transport of the LPA electron beams, and cavity based electron beam position monitors for non-invasive beam position detection. Also presented is PMQ calibration by using LPA electron beams with broadband energy spectrum. The results show promising performance for both transporting and monitoring. With the proper transport system,more » XUV-photon spectra from THUNDER will provide the momentum distribution of the electron beam with the resolution above what can be achieved by the magnetic spectrometer currently used in the LOASIS facility.« less

  19. Excitation of Accelerating Plasma Waves by Counter-Propagating Laser Beams

    NASA Astrophysics Data System (ADS)

    Shvets, Gennady

    2001-10-01

    The conventional approach to exciting high phase velocity waves in plasmas is to employ a laser pulse moving in the direction of the desired particle acceleration. Photon downshifting then causes the momentum transfer to the plasma and wave excitiation. We describe a novel approach to plasma wake excitation, colliding-beam accelerator (CBA), which involves the photon exchange between the long and short counter-propagating laser beams. Depending on frequency detuning Δ ω between beams and duration τL of the short pulse, there are two approaches to CBA. First approach assumes (τL ≈ 2/ω_p). Photons exchanged between the beams deposit their recoil momentum in the plasma driving the plasma wake. Frequency detuning between the beams determines the direction of the photon exchange, thereby controlling the phase of the plasma wake. This phase control can be used for reversing the slippage of the accelerated particles with respect to the wake ^1. It can also be used for developing an injector/pulse compressor for the particles of either sign (electrons or positrons)^2. In the second approach, one utilizes a longer pulse with τL >> ω_p-1, which is detuned by Δ ω ~ 2 ωp from the counter-propagating beam. While the parametric excitation of plasma waves by the electromagnetic beatwave at 2 ωp of two co-propagating lasers was first predicted by Rosenbluth and Liu in 1972, we realized, for the first time, that the two excitation beams can be counter-propagating^4. The advantages of using this geometry (lower threshold laser intensity, insensitivity to plasma inhomogeneity) will be explained, and the results of the numerical simulations presented. footnotetext[1]G. Shvets, N. J. Fisch, A. Pukhov, and J. Meyer-ter-Vehn, Phys. Rev. E 60, 2218 (1999). footnotetext[2]G. Shvets, N. J. Fisch, and A. Pukhov, 28, 1194 (2000). footnotetext[5]G. Shvets and N. J. Fisch, Phys. Rev. Lett. 86, 3328 (2001).

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

    PubMed

    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.

  1. Acceleration and evolution of a hollow electron beam in wakefields driven by a Laguerre-Gaussian laser pulse

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Guo-Bo; College of Science, National University of Defense Technology, Changsha 410073; Chen, Min, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com

    2016-03-15

    We show that a ring-shaped hollow electron beam can be injected and accelerated by using a Laguerre-Gaussian laser pulse and ionization-induced injection in a laser wakefield accelerator. The acceleration and evolution of such a hollow, relativistic electron beam are investigated through three-dimensional particle-in-cell simulations. We find that both the ring size and the beam thickness oscillate during the acceleration. The beam azimuthal shape is angularly dependent and evolves during the acceleration. The beam ellipticity changes resulting from the electron angular momenta obtained from the drive laser pulse and the focusing forces from the wakefield. The dependence of beam ring radiusmore » on the laser-plasma parameters (e.g., laser intensity, focal size, and plasma density) is studied. Such a hollow electron beam may have potential applications for accelerating and collimating positively charged particles.« less

  2. Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

    NASA Astrophysics Data System (ADS)

    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

  3. Spatial Distribution of the Threshold Beam Spots of Laser Weapons Simulators

    DTIC Science & Technology

    1993-09-08

    This paper was based on the transmission theory of elliptical Gaussian beam fluxes in deriving some transmission equations for the threshold beam...spots of laser weapon simulators, in order to revise and expand the expressions for the threshold beam spots, their maximum range, the extinction

  4. Laser beam apparatus and method for analyzing solar cells

    DOEpatents

    Staebler, David L.

    1980-01-01

    A laser beam apparatus and method for analyzing, inter alia, the current versus voltage curve at the point of illumination on a solar cell and the open circuit voltage of a solar cell. The apparatus incorporates a lock-in amplifier, and a laser beam light chopper which permits the measurement of the AC current of the solar cell at an applied DC voltage at the position on the solar cell where the cell is illuminated and a feedback scheme which permits the direct scanning measurements of the open circuit voltage. The accuracy of the measurement is a function of the intensity and wavelength of the laser light with respect to the intensity and wavelength distribution of sunlight and the percentage the dark current is at the open circuit voltage to the short circuit current of the solar cell.

  5. Simulation of laser beam reflection at the sea surface

    NASA Astrophysics Data System (ADS)

    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.

  6. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOEpatents

    Hohimer, John P.

    1994-01-01

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure.

  7. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOEpatents

    Hohimer, J.P.

    1994-06-07

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure. 6 figs.

  8. Time of Flight based diagnostics for high energy laser driven ion beams

    NASA Astrophysics Data System (ADS)

    Scuderi, V.; Milluzzo, G.; Alejo, A.; Amico, A. G.; Booth, N.; Cirrone, G. A. P.; Doria, D.; Green, J.; Kar, S.; Larosa, G.; Leanza, R.; Margarone, D.; McKenna, P.; Padda, H.; Petringa, G.; Pipek, J.; Romagnani, L.; Romano, F.; Schillaci, F.; Borghesi, M.; Cuttone, G.; Korn, G.

    2017-03-01

    Nowadays the innovative high power laser-based ion acceleration technique is one of the most interesting challenges in particle acceleration field, showing attractive characteristics for future multidisciplinary applications, including medical ones. Nevertheless, peculiarities of optically accelerated ion beams make mandatory the development of proper transport, selection and diagnostics devices in order to deliver stable and controlled ion beams for multidisciplinary applications. This is the main purpose of the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline that will be realized and installed within 2018 at the ELI-Beamlines research center in the Czech Republic, where laser driven high energy ions, up to 60 MeV/n, will be available for users. In particular, a crucial role will be played by the on-line diagnostics system, recently developed in collaboration with INFN-LNS (Italy), consisting of TOF detectors, placed along the beamline (at different detection distances) to provide online monitoring of key characteristics of delivered beams, such as energy, fluence and ion species. In this contribution an overview on the ELIMAIA available ion diagnostics will be briefly given along with the preliminary results obtained during a test performed with high energy laser-driven proton beams accelerated at the VULCAN PW-laser available at RAL facility (U.K.).

  9. A picosecond beam-timing system for the OMEGA laser

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Donaldson, W. R.; Katz, J.; Huff, R.

    A timing system is demonstrated for the OMEGA Laser System that guarantees all 60 beams will arrive on target simultaneously with a root mean square variability of 4 ps. The system relies on placing a scattering sphere at the target position to couple the ultraviolet light from each beam into a single photodetector.

  10. Generation of Multiple Vortex Beams with Specified Vortex Number from Lasers with Controlled Ince-Gaussian Modes

    NASA Astrophysics Data System (ADS)

    Chu, Shu-Chun

    2008-07-01

    This study proposes a systematic method of selecting excitations of part of Ince-Gaussian modes (IGMs) and a three-lens configuration for generating multiple vortex beams with forced IGMs in the model of laser-diode (LD)-pumped solid-state lasers. Simply changing the lateral off-axis position of the tight pump beam focus on the laser crystal can produce the desired multiple optical vortex beam from the laser in a well-controlled manner using a proposed astigmatic mode converter assembled into one body with the laser cavity.

  11. A three-dimensional laser vibration measurement technology realized on five laser beam and its calibration

    NASA Astrophysics Data System (ADS)

    Li, Lu-Ke; Zhang, Shen-Feng

    2018-03-01

    Put forward a kind of three-dimensional vibration information technology of vibrating object by the mean of five laser beam of He-Ne laser, and with the help of three-way sensor, measure the three-dimensional laser vibration developed by above mentioned technology. The technology based on the Doppler principle of interference and signal demodulation technology, get the vibration information of the object, through the algorithm processing, extract the three-dimensional vibration information of space objects, and can achieve the function of angle calibration of five beam in the space, which avoid the effects of the mechanical installation error, greatly improve the accuracy of measurement. With the help of a & B K4527 contact three axis sensor, measure and calibrate three-dimensional laser vibrometer, which ensure the accuracy of the measurement data. Summarize the advantages and disadvantages of contact and non-contact sensor, and analysis the future development trends of the sensor industry.

  12. Demonstration of relativistic electron beam focusing by a laser-plasma lens

    PubMed Central

    Thaury, C.; Guillaume, E.; Döpp, A.; Lehe, R.; Lifschitz, A.; Ta Phuoc, K.; Gautier, J.; Goddet, J-P; Tafzi, A.; Flacco, A.; Tissandier, F.; Sebban, S.; Rousse, A.; Malka, V.

    2015-01-01

    Laser-plasma technology promises a drastic reduction of the size of high-energy electron accelerators. It could make free-electron lasers available to a broad scientific community and push further the limits of electron accelerators for high-energy physics. Furthermore, the unique femtosecond nature of the source makes it a promising tool for the study of ultrafast phenomena. However, applications are hindered by the lack of suitable lens to transport this kind of high-current electron beams mainly due to their divergence. Here we show that this issue can be solved by using a laser-plasma lens in which the field gradients are five order of magnitude larger than in conventional optics. We demonstrate a reduction of the divergence by nearly a factor of three, which should allow for an efficient coupling of the beam with a conventional beam transport line. PMID:25880791

  13. Demonstration of relativistic electron beam focusing by a laser-plasma lens.

    PubMed

    Thaury, C; Guillaume, E; Döpp, A; Lehe, R; Lifschitz, A; Ta Phuoc, K; Gautier, J; Goddet, J-P; Tafzi, A; Flacco, A; Tissandier, F; Sebban, S; Rousse, A; Malka, V

    2015-04-16

    Laser-plasma technology promises a drastic reduction of the size of high-energy electron accelerators. It could make free-electron lasers available to a broad scientific community and push further the limits of electron accelerators for high-energy physics. Furthermore, the unique femtosecond nature of the source makes it a promising tool for the study of ultrafast phenomena. However, applications are hindered by the lack of suitable lens to transport this kind of high-current electron beams mainly due to their divergence. Here we show that this issue can be solved by using a laser-plasma lens in which the field gradients are five order of magnitude larger than in conventional optics. We demonstrate a reduction of the divergence by nearly a factor of three, which should allow for an efficient coupling of the beam with a conventional beam transport line.

  14. Two-beam combined 3.36  J, 100  Hz diode-pumped high beam quality Nd:YAG laser system.

    PubMed

    Qiu, J S; Tang, X X; Fan, Z W; Wang, H C; Liu, H

    2016-07-20

    In this paper, we develop a diode-pumped all-solid-state high-energy and high beam quality Nd:YAG laser system. A master oscillator power amplifier structure is used to provide a high pulse energy laser output with a high repetition rate. In order to decrease the amplifier working current so as to reduce the impact of the thermal effect on the beam quality, a beam splitting-amplifying-combining scheme is adopted. The energy extraction efficiency of the laser system is 50.68%. We achieve 3.36 J pulse energy at a 100 Hz repetition rate with a pulse duration of 7.1 ns, a far-field beam spot 1.71 times the diffraction limit, and 1.07% energy stability (RMS).

  15. Dynamics of laser-driven proton beam focusing and transport into solid density matter

    NASA Astrophysics Data System (ADS)

    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.

  16. Beam control of high-power broad-area photonic crystal lasers using ladderlike groove structure

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, Lijie; Shu, Shili; Tian, Sicong; Lu, Zefeng; Hou, Guanyu; Lu, Huanyu; Tong, Cunzhu; Wang, Lijun

    2017-06-01

    The high-power broad-area (BA) photonic bandgap crystal (PBC) diode laser is promising as a high-brightness laser source, however, it suffers from poor lateral beam quality owing to the intrinsic drawback of BA lasers. In this paper, a ladderlike groove structure (LLGS) was proposed to improve both the lateral beam quality and emission power of BA PBC lasers. An approximately 15.4% improvement in output power and 25.2% decrease in the lateral beam parameter product (BPP) were realized and the underlying mechanism was discussed. On the basis of the one-dimensional PBC epitaxial structure, a stable vertical far field was demonstrated.

  17. High-speed femtosecond laser beam shaping based on binary holography using a digital micromirror device.

    PubMed

    Cheng, Jiyi; Gu, Chenglin; Zhang, Dapeng; Chen, Shih-Chi

    2015-11-01

    In this Letter, we present a digital micromirror device (DMD)-based ultrafast beam shaper, i.e., DUBS. To our knowledge, the DUBS is the first binary laser beam shaper that can generate high-resolution (1140×912 pixels) arbitrary beam modes for femtosecond lasers at a rate of 4.2 kHz; the resolution and pattern rate are limited by the DMD. In the DUBS, the spectrum of the input pulsed laser is first angularly dispersed by a transmission grating and subsequently imaged to a DMD with beam modulation patterns; the transmission grating and a high-reflectivity mirror together compensate the angular dispersion introduced by the DMD. The mode of the output beam is monitored by a CCD camera. In the experiments, the DUBS is programmed to generate four different beam modes, including an Airy beam, Bessel beam, Laguerre-Gaussian (LG) beam, and a custom-designed "peace-dove" beam via the principle of binary holography. To verify the high shaping rate, the Airy beam and LG beam are generated alternately at 4.2 kHz, i.e., the maximum pattern rate of our DMD. The overall efficiency of the DUBS is measured to be 4.7%. With the high-speed and high-resolution beam-shaping capability, the DUBS may find important applications in nonlinear microscopy, optical manipulation, and microscale/nanoscale laser machining, etc.

  18. Study on the generation of a vortex laser beam by using phase-only liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Ma, Haotong; Hu, Haojun; Xie, Wenke; Xu, Xiaojun

    2013-09-01

    The generation of vortex laser beam by using phase-only liquid crystal spatial light modulator (LC-SLM) combined with the spiral phase screen is experimentally and theoretically studied. Results show that Gaussian and dark hollow vortex laser beams can be generated by using this method successfully. Differing with the Gaussian and dark hollow beams, far field intensities of the generated vortex laser beams still exhibit dark hollow distributions. The comparisons between the ideal generation and experimental generation of vortex laser beams with different optical topological charges by using phase only LC-SLM is investigated in detail. Compared with the ideal generated vortex laser beam, phase distribution of the experimental generated vortex laser beam contains many phase singularities, the number of which is the same as that of the optical topological charges. The corresponding near field and far field dark hollow intensity distributions of the generated vortex laser beams exhibit discontinuous in rotational direction. Detailed theoretical analysis show that the main reason for the physical phenomenon mentioned above is the response error of phase only LC-SLM. These studies can provide effective guide for the generation of vortex laser beam by using phase only LC-SLM for optical tweezers and free space optical communication.

  19. Beam Conditioning and Harmonic Generation in Free ElectronLasers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charman, A.E.; Penn, G.; Wolski, A.

    2004-07-05

    The next generation of large-scale free-electron lasers (FELs) such as Euro-XFEL and LCLS are to be devices which produce coherent X-rays using Self-Amplified Spontaneous Emission (SASE). The performance of these devices is limited by the spread in longitudinal velocities of the beam. In the case where this spread arises primarily from large transverse oscillation amplitudes, beam conditioning can significantly enhance FEL performance. Future X-ray sources may also exploit harmonic generation starting from laser-seeded modulation. Preliminary analysis of such devices is discussed, based on a novel trial-function/variational-principle approach, which shows good agreement with more lengthy numerical simulations.

  20. Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-03-01

    Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

  1. Molecular Dynamics Simulation of the Three-Dimensional Ordered State in Laser-Cooled Heavy-Ion Beams

    NASA Astrophysics Data System (ADS)

    Yuri, Yosuke

    A molecular dynamics simulation is performed to study the formation of three-dimensional ordered beams by laser cooling in a cooler storage ring. Ultralow-temperature heavy-ion beams are generated by transverse cooling with displaced Gaussian lasers and resonant coupling. A three-dimensional ordered state of the ion beam is attained at a high line density. The ordered beam exhibits several unique characteristics different from those of an ideal crystalline beam.

  2. A picosecond beam-timing system for the OMEGA laser

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Donaldson, W. R.; Katz, J.; Huff, R.

    Here, a timing system is demonstrated for the OMEGA Laser System that guarantees all 60 beams will arrive on target simultaneously with a root mean square variability of 4 ps. The system relies on placing a scattering sphere at the target position to couple the UV light from each beam into a single photodetector.

  3. A picosecond beam-timing system for the OMEGA laser

    DOE PAGES

    Donaldson, W. R.; Katz, J.; Huff, R.; ...

    2016-05-27

    Here, a timing system is demonstrated for the OMEGA Laser System that guarantees all 60 beams will arrive on target simultaneously with a root mean square variability of 4 ps. The system relies on placing a scattering sphere at the target position to couple the UV light from each beam into a single photodetector.

  4. Coherent beam combination of fiber lasers with a strongly confined waveguide: numerical model.

    PubMed

    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.

  5. Laser beam complex amplitude measurement by phase diversity.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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 < 1 / (2 πωpe)) laser pulses drive highly nonlinear plasma waves which can trap ~ nC of electrons and accelerate them to ~GeV energies over ~cm lengths. These electron beams can then be converted by a high-Z target via bremsstrahlung into low-divergence (< 20 mrad) beams of high-energy (<600 MeV) photons and subsequently into positrons via the Bethe-Heitler process. By increasing the material thickness and 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 < 40 fs) 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.

  7. Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

    NASA Astrophysics Data System (ADS)

    Xu, Tongjun; Shen, Baifei; Xu, Jiancai; Li, Shun; Yu, Yong; Li, Jinfeng; Lu, Xiaoming; Wang, Cheng; Wang, Xinliang; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2016-03-01

    Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron-positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 1021 s-1, thus allows specific studies of fast kinetics in millimeter-thick materials with a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.

  8. Development of Electron Beam Pumped KrF Lasers for Fusion Energy

    DTIC Science & Technology

    2008-01-01

    Direct drive with krypton fluoride (KrF) lasers is an attractive approach to inertial fusion energy (IFE): KrF lasers have outstanding beam spatial...attractive power plant [3]. In view of these advances, several world-wide programs are underway to develop KrF lasers for fusion energy . These include

  9. Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Osterhoff, J.; Nakamura, K.; Bakeman, M.

    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.

  10. Ultra-compact laser beam steering device using holographically formed two dimensional photonic crystal.

    PubMed

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

    2010-03-01

    In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results showed a beam steering angle of 10 degree for 30 nm wavelength variation.

  11. Generation of terahertz radiation by intense hollow Gaussian laser beam in magnetised plasma under relativistic-ponderomotive regime

    NASA Astrophysics Data System (ADS)

    Rawat, Priyanka; Rawat, Vinod; Gaur, Bineet; Purohit, Gunjan

    2017-07-01

    This paper explores the self-focusing of hollow Gaussian laser beam (HGLB) in collisionless magnetized plasma and its effect on the generation of THz radiation in the presence of relativistic-ponderomotive nonlinearity. The relativistic change of electron mass and electron density perturbation due to the ponderomotive force leads to self-focusing of the laser beam in plasma. Nonlinear coupling between the intense HGLB and electron plasma wave leads to generation of THz radiation in plasma. Resonant excitation of THz radiation at different frequencies of laser and electron plasma wave satisfies proper phase matching conditions. Appropriate expressions for the beam width parameter of the laser beam and the electric vector of the THz wave have been evaluated under the paraxial-ray and Wentzel-Kramers Brillouin approximations. It is found that the yield of THz amplitude depends on the focusing behaviour of laser beam, magnetic field, and background electron density. Numerical simulations have been carried out to investigate the effect of laser and plasma parameters on self-focusing of the laser beam and further its effect on the efficiency of the generated THz radiation.

  12. Generation of Ince-Gaussian beams in highly efficient, nanosecond Cr, Nd:YAG microchip lasers

    NASA Astrophysics Data System (ADS)

    Dong, J.; Ma, J.; Ren, Y. Y.; Xu, G. Z.; Kaminskii, A. A.

    2013-08-01

    Direct generation of higher-order Ince-Gaussian (IG) beams from laser-diode end-pumped Cr, Nd:YAG self-Q-switched microchip lasers was achieved with high efficiency and high repetition rate. An average output power of over 2 W was obtained at an absorbed pump power of 8.2 W a corresponding optical-to-optical efficiency of 25% was achieved. Various IG modes with nanosecond pulse width and peak power of over 2 kW were obtained in laser-diode pumped Cr, Nd:YAG microchip lasers under different pump power levels by applying a tilted, large area pump beam. The effect of the inversion population distribution induced by the tilted pump beam and nonlinear absorption of Cr4+-ions for different pump power levels on the oscillation of higher-order IG modes in Cr, Nd:YAG microchip lasers is addressed. The higher-order IG mode oscillation has a great influence on the laser performance of Cr, Nd:YAG microchip lasers.

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

    PubMed

    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.

  14. Exploring vacuum birefringence based on a 100 PW laser and an x-ray free electron laser beam

    NASA Astrophysics Data System (ADS)

    Shen, Baifei; Bu, Zhigang; Xu, Jiancai; Xu, Tongjun; Ji, Liangliang; Li, Ruxin; Xu, Zhizhan

    2018-04-01

    Exploring vacuum birefringence with the station of extreme light at Shanghai Coherent Light Facility is considered. Laser pulses of intensity beyond 1023 W cm-2 are capable of polarizing the vacuum due to the ultra-strong electro-magnetic fields. The subtle difference of the vacuum refractive indexes along electric and magnetic fields leads to a birefringence effect for lights propagating through. The vacuum birefringence effect can now be captured by colliding a hard x-ray free electron laser (XFEL) beam with a high-power laser. The initial XFEL beam of pure linear polarization is predicated to gain a very small ellipticity after passing through the laser stimulated vacuum. Various interaction geometries are considered, showing that the estimated ellipticity lies between 1.8 × 10-10 and 10-9 for a 100 PW laser interacting with a 12.9 keV XFEL beam, approaching the threshold for todays’ polarity detection technique. The detailed experimental set-up is designed, including the polarimeter, the focusing compound refractive lens and the optical path. When taking into account the efficiencies of the x-ray instruments, it is found that about 10 polarization-flipped x-ray photons can be detected for a single shot for our design. Considering the background noise level, accumulating runs are necessary to obtain high confident measurement.

  15. Dual beam translator for use in Laser Doppler anemometry

    DOEpatents

    Brudnoy, David M.

    1987-01-01

    A method and apparatus for selectively translating the path of at least one pair of light beams in a Laser Doppler anemometry device whereby the light paths are translated in a direction parallel to the original beam paths so as to enable attainment of spacial coincidence of the two intersection volumes and permit accurate measurements of Reynolds shear stress.

  16. Dual beam translator for use in Laser Doppler anemometry

    DOEpatents

    Brudnoy, D.M.

    1984-04-12

    A method and apparatus for selectively translating the path of at least one pair of light beams in a Laser Doppler anemometry device whereby the light paths are translated in a direction parallel to the original beam paths so as to enable attainment of spacial coincidence of the two intersection volumes and permit accurate measurements of Reynolds shear stress.

  17. Surface treatment with linearly polarized laser beam at oblique incidence

    NASA Astrophysics Data System (ADS)

    Gutu, I.; Petre, C.; Mihailescu, I. N.; Taca, M.; Alexandrescu, E.; Ivanov, I.

    2002-07-01

    An effective method for surface heat treatment with 10.6 μm linear polarized laser beam at oblique incidence is reported. A circular focused laser spot on the workpiece surface, simultaneously with 2.2-4 times increasing of the absorption are obtained in the 70-80° range of the incidence angle. The main element of the experimental setup is the astigmatic focusing head which focalize the laser beam into an elliptical spot of ellipticity ɛ>3 at normal incidence. At a proper incidence angle (obtained by the focusing head tilting) the focused laser spot on the work piece surface gets a circular form and p-state of polarization is achieved. We performed laser heat treatment (transformation hardening, surface remelting) of the uncoated surface, as well as the alloying and cladding processes by powder injection. An enhancement of the processing efficiency was obtained; in this way the investment and operation costs for surface treatment with CO 2 laser can be significantly reduced. Several technical advantages concerning the pollution of the focusing optical components, powder jet flowing and reflected radiation by the work piece surface are obtained.

  18. A preclinical study testing "Focused multiple laser beams," a new concept of irradiation with the 1064-nm Nd:YAG laser for skin rejuvenation.

    PubMed

    Horiguchi, Masatoshi; Miyata, Nariaki; Mizuno, Hiroshi

    2017-04-01

    In order to avoid epidermal heat damage, we developed a novel irradiation method termed "Focused multiple laser beams (FMLB)," which allows long-pulse neodymium:yttrium aluminum garnet (Nd:YAG) laser beams to be irradiated from several directions in a concentric fashion followed by focusing into the dermis without epidermal damage. This study aimed to assess whether FMLB achieves the desired dermal improvement without epidermal damage. The dorsal skin of New Zealand White rabbits was irradiated with FMLB. Macroscopic and histological analyses were performed after 1 hour and 1, 2, 3 and 4 weeks. Real-time PCR analysis of type I and III collagen expression was performed at two and four weeks. Control groups exhibited skin ulcers which were healed with scar formation whereas FMLB groups remained intact macroscopically. Histologically, FMLB group showed increase in dermal thickness at four weeks while the epidermis remained intact. Real-time PCR demonstrated that both type I and III collagen increased at two weeks but decreased at four weeks. FMLB can deliver the target laser energy to the dermis without significantly affecting the epidermis.

  19. Undulator radiation from laser-plasma-accelerated electron beams

    NASA Astrophysics Data System (ADS)

    Shaw, B.; van Tilborg, J.; Gonsalves, A.; Nakamura, K.; Sokollik, T.; Shiraishi, S.; Mittal, R.; Esarey, E.; Schroeder, C.; Toth, C.; Leemans, W. P.

    2012-12-01

    Recent experiments coupled electron beams from the LOASIS TREX laser plasma accelerator (LPA) [1, 2, 3] to the Tapered Hybrid Undulator (THUNDER). Using the 1.5m, 66 period undulator, followed by an XUV spectrometer, spontaneous radiation was observed at photon energies extending to 100 eV. Previous experiments have reported visible [4] and soft-x-ray [5] radiation. The purpose of our experiments is to do highly precise, single shot diagnostics of the energy spread and emittance for each electron beam. We present recent results including measurements of electron beam transport through the undulator with and without the use of permanent magnetic quadrapoles, and measurements of XUV spectra up to 100 eV from LPA produced e-beams.

  20. A continuously variable beam-diameter, high-fluence, Q-switched Nd:YAG laser for tattoo removal: comparison of the maximum beam diameter to a standard 4-mm-diameter treatment beam.

    PubMed

    Bernstein, Eric F; Civiok, Jennifer M

    2013-12-01

    Laser beam diameter affects the depth of laser penetration. Q-switched lasers tend to have smaller maximum spot sizes than other dermatologic lasers, making beam diameter a potentially more significant factor in treatment outcomes. To compare the clinical effect of using the maximum-size treatment beam available for each delivered fluence during laser tattoo removal to a standard 4-mm-diameter treatment beam. Thirteen tattoos were treated in 12 subjects using a Q-switched Nd:YAG laser equipped with a treatment beam diameter that was adjustable in 1 mm increments and a setting that would enable the maximally achievable diameter ("MAX-ON" setting) with any fluence. Tattoos were randomly bisected and treated on one side with the MAX-ON setting and on the contralateral side with a standard 4-mm-diameter spot ("MAX-OFF" setting). Photographs were taken 8 weeks following each treatment and each half-tattoo was evaluated for clearance on a 10-point scale by physicians blinded to the treatment conditions. Tattoo clearance was greater on the side treated with the MAX-ON setting in a statistically significant manner following the 1st through 4th treatments, with the MAX-OFF treatment site approaching the clearance of the MAX-ON treatment site after the 5th and 6th treatments. This high-energy, Q-switched Nd:YAG laser with a continuously variable spot-size safely and effectively removes tattoos, with greater removal when using a larger spot-size. © 2013 Wiley Periodicals, Inc.

  1. Beam shaping by using small-aperture SLM and DM in a high power laser

    NASA Astrophysics Data System (ADS)

    Li, Sensen; Lu, Zhiwei; Du, Pengyuan; Wang, Yulei; Ding, Lei; Yan, Xiusheng

    2018-03-01

    High-power laser plays an important role in many fields, such as directed energy weapon, optoelectronic contermeasures, inertial confinement fusion, industrial processing and scientific research. The uniform nearfield and wavefront are the important part of the beam quality for high power lasers, which is conducive to maintaining the high spatial beam quality in propagation. We demonstrate experimentally that the spatial intensity and wavefront distribution at the output is well compensated in the complex high-power solid-state laser system by using the small-aperture spatial light modulator (SLM) and deformable mirror (DM) in the front stage. The experimental setup is a hundred-Joule-level Nd:glass laser system operating at three wavelengths at 1053 nm (1ω), 527 nm (2ω) and 351 nm (3ω) with 3 ns pulse duration with the final output beam aperture of 60 mm. While the clear arperture of the electrically addressable SLM is less than 20 mm and the effective diameter of the 52-actuators DM is about 15 mm. In the beam shaping system, the key point is that the two front-stage beam shaping devices needs to precompensate the gain nonuniform and wavefront distortion of the laser system. The details of the iterative algorithm for improving the beam quality are presented. Experimental results show that output nearfield and wavefont are both nearly flat-topped with the nearfield modulation of 1.26:1 and wavefront peak-to-valley value of 0.29 λ at 1053nm after beam shaping.

  2. Laser acceleration of quasi-monoenergetic MeV ion beams.

    PubMed

    Hegelich, B M; Albright, B J; Cobble, J; Flippo, K; Letzring, S; Paffett, M; Ruhl, H; Schreiber, J; Schulze, R K; Fernández, J C

    2006-01-26

    Acceleration of particles by intense laser-plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m(-1) (1 TV = 10(12) V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced. Such ion beams exhibit unprecedented characteristics--short pulse lengths, high currents and low transverse emittance--but their exponential energy spectra have almost 100% energy spread. This large energy spread, which is a consequence of the experimental conditions used to date, remains the biggest impediment to the wider use of this technology. Here we report the production of quasi-monoenergetic laser-driven C5+ ions with a vastly reduced energy spread of 17%. The ions have a mean energy of 3 MeV per nucleon (full-width at half-maximum approximately 0.5 MeV per nucleon) and a longitudinal emittance of less than 2 x 10(-6) eV s for pulse durations shorter than 1 ps. Such laser-driven, high-current, quasi-monoenergetic ion sources may enable significant advances in the development of compact MeV ion accelerators, new diagnostics, medical physics, inertial confinement fusion and fast ignition.

  3. Non-stationary self-focusing of intense laser beam in plasma using ramp density profile

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Habibi, M.; Ghamari, F.

    2011-10-15

    The non-stationary self-focusing of high intense laser beam in under-dense plasma with upward increasing density ramp is investigated. The obtained results show that slowly increasing plasma density ramp is very important in enhancing laser self-focusing. Also, the spot size oscillations of laser beam in front and rear of the pulse for two different density profiles are shown. We have selected density profiles that already were used by Sadighi-Bonabi et al.[Phys. Plasmas 16, 083105 (2009)]. Ramp density profile causes the laser beam to become more focused and penetrations deeps into the plasma by reduction of diffraction effects. Our computations show moremore » reliable results in comparison to the previous works.« less

  4. A heterodyne straightness and displacement measuring interferometer with laser beam drift compensation for long-travel linear stage metrology.

    PubMed

    Chen, Benyong; Cheng, Liang; Yan, Liping; Zhang, Enzheng; Lou, Yingtian

    2017-03-01

    The laser beam drift seriously influences the accuracy of straightness or displacement measurement in laser interferometers, especially for the long travel measurement. To solve this problem, a heterodyne straightness and displacement measuring interferometer with laser beam drift compensation is proposed. In this interferometer, the simultaneous measurement of straightness error and displacement is realized by using heterodyne interferometry, and the laser beam drift is determined to compensate the measurement results of straightness error and displacement in real time. The optical configuration of the interferometer is designed. The principle of the simultaneous measurement of straightness, displacement, and laser beam drift is depicted and analyzed in detail. And the compensation of the laser beam drift for the straightness error and displacement is presented. Several experiments were performed to verify the feasibility of the interferometer and the effectiveness of the laser beam drift compensation. The experiments of laser beam stability show that the position stability of the laser beam spot can be improved by more than 50% after compensation. The measurement and compensation experiments of straightness error and displacement by testing a linear stage at different distances show that the straightness and displacement obtained from the interferometer are in agreement with those obtained from a compared interferometer and the measured stage. These demonstrate that the merits of this interferometer are not only eliminating the influence of laser beam drift on the measurement accuracy but also having the abilities of simultaneous measurement of straightness error and displacement as well as being suitable for long-travel linear stage metrology.

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

    PubMed

    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.

  6. Comparisons of selected laser beam power missions to conventionally powered missions

    NASA Technical Reports Server (NTRS)

    Bozek, John M.; Oleson, Steven R.; Landis, Geoffrey A.; Stavnes, Mark W.

    1993-01-01

    Earth-based laser sites beaming laser power to space assets have shown benefits over competing power system concepts for specific missions. Missions analyzed in this report that show benefits of laser beam power are low Earth orbit (LEO) to geosynchronous Earth orbit (GEO) transfer, LEO to low lunar orbit (LLO) cargo missions, and lunar-base power. Both laser- and solar-powered orbit-transfer vehicles (OTV's) make a 'tug' concept viable, which substantially reduces cumulative initial mass to LEO in comparison to chemical propulsion concepts. Lunar cargo missions utilizing laser electric propulsion from Earth-orbit to LLO show substantial mass saving to LEO over chemical propulsion systems. Lunar-base power system options were compared on a landed-mass basis. Photovoltaics with regenerative fuel cells, reactor-based systems, and laser-based systems were sized to meet a generic lunar-base power profile. A laser-based system begins to show landed mass benefits over reactor-based systems when proposed production facilities on the Moon require power levels greater than approximately 300 kWe. Benefit/cost ratios of laser power systems for an OTV, both to GEO and LLO, and for a lunar base were calculated to be greater than 1.

  7. Unsteady thermal blooming of intense laser beams

    NASA Astrophysics Data System (ADS)

    Ulrich, J. T.; Ulrich, P. B.

    1980-01-01

    A four dimensional (three space plus time) computer program has been written to compute the nonlinear heating of a gas by an intense laser beam. Unsteady, transient cases are capable of solution and no assumption of a steady state need be made. The transient results are shown to asymptotically approach the steady-state results calculated by the standard three dimensional thermal blooming computer codes. The report discusses the physics of the laser-absorber interaction, the numerical approximation used, and comparisons with experimental data. A flowchart is supplied in the appendix to the report.

  8. Program Models A Laser Beam Focused In An Aerosol Spray

    NASA Technical Reports Server (NTRS)

    Barton, J. P.

    1996-01-01

    Monte Carlo analysis performed on packets of light. Program for Analysis of Laser Beam Focused Within Aerosol Spray (FLSPRY) developed for theoretical analysis of propagation of laser pulse optically focused within aerosol spray. Applied for example, to analyze laser ignition arrangement in which focused laser pulse used to ignite liquid aerosol fuel spray. Scattering and absorption of laser light by individual aerosol droplets evaluated by use of electromagnetic Lorenz-Mie theory. Written in FORTRAN 77 for both UNIX-based computers and DEC VAX-series computers. VAX version of program (LEW-16051). UNIX version (LEW-16065).

  9. Stem Cell Physics. Multiple-Laser-Beam Treatment of Parkinson's Disease

    NASA Astrophysics Data System (ADS)

    Stefan, V.

    2013-03-01

    A novel method for the treatment of Parkinson's disease is proposed. Pluripotent stem cells are laser cultured, using ultrashort wavelength, (around 0.1 micron-ultraviolet radiation-with intensities of a few mW/cm2) , multiple laser beams.[2] The multiple-energy laser photons[3] interact with the neuron DNA molecules to be cloned. The laser created dopaminergic substantia nigra neurons can be, (theoretically), laser transplanted, (a higher focusing precision as compared to a syringe method), into the striatum or substantia nigra regions of the brain, or both. Supported by Nikola Tesla Labs, Stefan University.

  10. Smith-Purcell terahertz radiation from laser modulated electron beam over a metallic grating

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Bhasin, Lalita; Tripathi, V. K.; Kumar, Ashok; Kumar, Manoj

    2016-09-01

    We propose a novel scheme of terahertz (THz) radiation generation from the beat frequency modulation of an electron beam by two co-propagating lasers and the generation of terahertz radiation by the modulated beam passing over a periodic metallic grating. The lasers cause velocity modulation of the beam by exerting a longitudinal ponderomotive force on it. In the drift space between the modulator and metallic grating, the velocity modulation translates into density and current modulation. The modulated beam, propagating over the grating of specific wave number, induces space periodic image current in the conductor that emits beat frequency Smith-Purcell radiation. With 1 μm, 4 × 1016 W/cm2 lasers, beam current modulation of the order of 50% can be achieved at optimum lengths of the modulator and drift space. Employing 10 mA, 0.5 MeV short-period electron beam, propagating at a height of 50 μ m above the grating of period 150 μm, one may obtain THz radiated power of the order of 6 mW at 10 THz.

  11. Multiscale permutation entropy analysis of laser beam wandering in isotropic turbulence.

    PubMed

    Olivares, Felipe; Zunino, Luciano; Gulich, Damián; Pérez, Darío G; Rosso, Osvaldo A

    2017-10-01

    We have experimentally quantified the temporal structural diversity from the coordinate fluctuations of a laser beam propagating through isotropic optical turbulence. The main focus here is on the characterization of the long-range correlations in the wandering of a thin Gaussian laser beam over a screen after propagating through a turbulent medium. To fulfill this goal, 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 the symbolic technique based on ordinal patterns to estimate the well-known permutation entropy. We show that the permutation entropy estimations at multiple time scales evidence an interplay between different dynamical behaviors. More specifically, a crossover between two different scaling regimes is observed. We confirm a transition from an integrated stochastic process contaminated with electronic noise to a fractional Brownian motion with a Hurst exponent H=5/6 as the sampling time increases. Besides, we are able to quantify, from the estimated entropy, the amount of electronic noise as a function of the turbulence strength. We have also demonstrated that these experimental observations are in very good agreement with numerical simulations of noisy fractional Brownian motions with a well-defined crossover between two different scaling regimes.

  12. Backscatter spectra measurements of the two beams on the same cone on Shenguang-III laser facility

    NASA Astrophysics Data System (ADS)

    Zha, Weiyi; Yang, Dong; Xu, Tao; Liu, Yonggang; Wang, Feng; Peng, Xiaoshi; Li, Yulong; Wei, Huiyue; Liu, Xiangming; Mei, Yu; Yan, Yadong; He, Junhua; Li, Zhichao; Li, Sanwei; Jiang, Xiaohua; Guo, Liang; Xie, Xufei; Pan, Kaiqiang; Liu, Shenye; Jiang, Shaoen; Zhang, Baohan; Ding, Yongkun

    2018-01-01

    In laser driven hohlraums, laser beams on the same incident cone may have different beam and plasma conditions, causing beam-to-beam backscatter difference and subsequent azimuthal variations in the x-ray drive on the capsule. To elucidate the large variation of backscatter proportion from beam to beam in some gas-filled hohlraum shots on Shenguang-III, two 28.5° beams have been measured with the Stimulated Raman Scattering (SRS) time-resolved spectra. A bifurcated fiber is used to sample two beams and then coupled to a spectrometer and streak camera combination to reduce the cost. The SRS spectra, characterized by a broad wavelength, were further corrected considering the temporal distortion and intensity modulation caused by components along the light path. This measurement will improve the understanding of the beam propagation inside the hohlraum and related laser plasma instabilities.

  13. LD-pumped erbium and neodymium lasers with high energy and output beam quality

    NASA Astrophysics Data System (ADS)

    Kabanov, Vladimir V.; Bezyazychnaya, Tatiana V.; Bogdanovich, Maxim V.; Grigor'ev, Alexandr V.; Lebiadok, Yahor V.; Lepchenkov, Kirill V.; Ryabtsev, Andrew G.; Ryabtsev, Gennadii I.; Shchemelev, Maxim A.

    2013-05-01

    Physical and fabrication peculiarities which provide the high output energy and beam quality for the diode pumped erbium glass and Nd:YAG lasers are considered. Developed design approach allow to make passively Q-switched erbium glass eye-safe portable laser sources with output energy 8 - 12 mJ (output pulse duration is less than 25 ns, pulse repetition rate up to 5 Hz) and beam quality M2 less than 1.3. To reach these values the erbium laser pump unit parameters were optimized also. Namely, for the powerful laser diode arrays the optimal near-field fill-factor, output mirror reflectivity and heterostructure properties were determined. Construction of advanced diode and solid-state lasers as well as the optical properties of the active element and the pump unit make possible the lasing within a rather wide temperature interval (e.g. from minus forty till plus sixty Celsius degree) without application of water-based chillers. The transversally pumped Nd:YAG laser output beam uniformity was investigated depending on the active element (AE) pump conditions. In particular, to enhance the pump uniformity within AE volume, a special layer which practically doesn't absorb the pump radiation but effectively scatters the pump and lasing beams, was used. Application of such layer results in amplified spontaneous emission suppression and improvement of the laser output beam uniformity. The carried out investigations allow us to fabricate the solid-state Nd:YAG lasers (1064 nm) with the output energy up to 420 mJ at the pulse repetition rate up to 30 Hz and the output energy up to 100 mJ at the pulse repetition rate of of 100 Hz. Also the laser sources with following characteristics: 35 mJ, 30 Hz (266 nm); 60 mJ, 30 Hz (355 nm); 100 mJ, 30 Hz (532 nm) were manufactured on the base of the developed Nd:YAG quantrons.

  14. Second harmonic generation of q-Gaussian laser beam in preformed collisional plasma channel with nonlinear absorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gupta, Naveen, E-mail: naveens222@rediffmail.com; Singh, Arvinder, E-mail: arvinder6@lycos.com; Singh, Navpreet, E-mail: navpreet.nit@gmail.com

    2015-11-15

    This paper presents a scheme for second harmonic generation of an intense q-Gaussian laser beam in a preformed parabolic plasma channel, where collisional nonlinearity is operative with nonlinear absorption. Due to nonuniform irradiance of intensity along the wavefront of the laser beam, nonuniform Ohmic heating of plasma electrons takes place. Due to this nonuniform heating of plasma, the laser beam gets self-focused and produces strong density gradients in the transverse direction. The generated density gradients excite an electron plasma wave at pump frequency that interacts with the pump beam to produce its second harmonics. The formulation is based on amore » numerical solution of the nonlinear Schrodinger wave equation in WKB approximation followed by moment theory approach. A second order nonlinear differential equation governing the propagation dynamics of the laser beam with distance of propagation has been obtained and is solved numerically by Runge Kutta fourth order technique. The effect of nonlinear absorption on self-focusing of the laser beam and conversion efficiency of its second harmonics has been investigated.« less

  15. High peak current operation of x-ray free-electron laser multiple beam lines by suppressing coherent synchrotron radiation effects

    NASA Astrophysics Data System (ADS)

    Hara, Toru; Kondo, Chikara; Inagaki, Takahiro; Togawa, Kazuaki; Fukami, Kenji; Nakazawa, Shingo; Hasegawa, Taichi; Morimoto, Osamu; Yoshioka, Masamichi; Maesaka, Hirokazu; Otake, Yuji; Tanaka, Hitoshi

    2018-04-01

    The parallel operation of multiple beam lines is an important means to expand the opportunity of user experiments at x-ray free-electron laser (XFEL) facilities. At SPring-8 Angstrom free-electron laser (SACLA), the multi-beam-line operation had been tested using two beam lines, but transverse coherent synchrotron radiation (CSR) effects at a dogleg beam transport severely limited the laser performance. To suppress the CSR effects, a new beam optics based on two double bend achromat (DBA) structures was introduced for the dogleg. After the replacement of the beam optics, high peak current bunches of more than 10 kA are now stably transported through the dogleg and the laser pulse output is increased by a factor of 2-3. In the multi-beam-line operation of SACLA, the electron beam parameters, such as the beam energy and peak current, can be adjusted independently for each beam line. Thus the laser output can be optimized and wide spectral tunability is ensured for all beam lines.

  16. Beam shaping of laser diode radiation by waveguides with arbitrary cladding geometry written with fs-laser radiation.

    PubMed

    Beckmann, Dennis; Schnitzler, Daniel; Schaefer, Dagmar; Gottmann, Jens; Kelbassa, Ingomar

    2011-12-05

    Waveguides with arbitrary cross sections are written in the volume of Al(2)O(3)-crystals using tightly focused femtosecond laser radiation. Utilizing a scanning system with large numerical aperture, complex cladding geometries are realized with a precision around 0.5 µm and a scanning speed up to 100 mm/s. Individual beam and mode shaping of laser diode radiation is demonstrated by varying the design of the waveguide cladding. The influence of the writing parameters on the waveguide properties are investigated resulting in a numerical aperture of the waveguides in the range of 0.1. This direct laser writing technique enables optical devices which could possibly replace bulky beam shaping setups with an integrated solution.

  17. Off-axis spectral beam combining of Bragg reflection waveguide photonic crystal diode lasers

    NASA Astrophysics Data System (ADS)

    Sun, Fangyuan; Wang, Lijie; Zhao, Yufei; Hou, Guanyu; Shu, Shili; Zhang, Jun; Peng, Hangyu; Tian, Sicong; Tong, Cunzhu; Wang, Lijun

    2018-06-01

    The spectral beam combining (SBC) of Bragg reflection waveguide photonic crystal (BRW-PC) diode lasers was studied for the first time. An off-axis feedback system was constructed using a stripe mirror and a spatial filter to control beam quality in the external cavity. It was found that the BRW-PC diode lasers with a low divergence and a circular beam provided a simplified and cost-effective SBC. The off-axis feedback broke the beam quality limit of a single element, and an M 2 factor of 3.8 times lower than that of a single emitter in the slow axis was demonstrated.

  18. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

    PubMed

    Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

    2016-04-19

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

  19. Flow speed of the ablation vapors generated during laser drilling of CFRP with a continuous-wave laser beam

    NASA Astrophysics Data System (ADS)

    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.

  20. Biomimetic surface structuring using cylindrical vector femtosecond laser beams

    NASA Astrophysics Data System (ADS)

    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.

  1. Dissociation phenomena in electron-beam sustained carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Harris, Michael R.; Willetts, David V.

    1990-01-01

    A number of applications are emerging requiring efficient, long pulse, long-life sealed CO2 lasers. Examples include the proposed NASA and ESA wind lidars. Electron-beam sustained discharge devices are strong contenders. Unlike self-sustained discharges, e-beam sustenance readily provides efficient performance from large volume discharges and offers pulse lengths well in excess of the microsecond or so generally associated with self-sustained devices. In the case of the e-beam sustained laser, since the plasma is externally maintained and operated at electric field strengths less than that associated with the glow to arc transition, the discharges can be run even in the presence of strongly attacking species such as O2. Build up of large levels of attacking contaminants is nevertheless undesirable as their presence reduces the current drawn by the plasma and thus the pumping rate to the upper laser level. The impedance rise leads to a mismatch of the pulse forming network with a consequent loss of control over energy deposition, operating E/N, and gain. Clearly CO2 dissociation rates, the influence of dissociation products on the discharge and gain, and tolerance of the discharge to these products need to be determined. This information can then be used to assess co-oxidation catalyst requirements for sealed operation.

  2. Biomimetic surface structuring using cylindrical vector femtosecond laser beams

    PubMed Central

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

    2017-01-01

    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. PMID:28327611

  3. Thermomagnetic recording and magneto-optic playback system having constant intensity laser beam control

    NASA Technical Reports Server (NTRS)

    Lewicki, G. W.; Guisinger, J. E. (Inventor)

    1973-01-01

    A system is developed for maintaining the intensity of a laser beam at a constant level in a thermomagnetic recording and magneto-optic playback system in which an isotropic film is heated along a continuous path by the laser beam for recording. As each successive area of the path is heated locally to the vicinity of its Curie point in the presence of a controlled magnetic field, a magneto-optic density is produced proportional to the amplitude of the controlled magnetic field. To play back the recorded signal, the intensity of the laser beam is reduced and a Faraday or Kerr effect analyzer is used, with a photodetector, as a transducer for producing an output signal.

  4. High-speed measurement of an air transect's temperature shift heated by laser beam

    NASA Astrophysics Data System (ADS)

    Li, WenYu; Jiang, ZongFu; Xi, Fengjie; Li, Qiang; Xie, Wenke

    2005-02-01

    Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.

  5. Guiding and focusing of fast electron beams produced by ultra-intense laser pulse using a double cone funnel target

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Wen-shuai; Cai, Hong-bo, E-mail: Cai-hongbo@iapcm.ac.cn; HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871

    A novel double cone funnel target design aiming at efficiently guiding and focusing fast electron beams produced in high intensity (>10{sup 19 }W/cm{sup 2}) laser-solid interactions is investigated via two-dimensional particle-in-cell simulations. The forward-going fast electron beams are shown to be directed and focused to a smaller size in comparison with the incident laser spot size. This plasma funnel attached on the cone target guides and focuses electrons in a manner akin to the control of liquid by a plastic funnel. Such device has the potential to add substantial design flexibility and prevent inefficiencies for important applications such as fast ignition.more » Two reasons account for the collimation of fast electron beams. First, the sheath electric fields and quasistatic magnetic fields inside the vacuum gap of the double cone provide confinement of the fast electrons in the laser-plasma interaction region. Second, the interface magnetic fields inside the beam collimator further guide and focus the fast electrons during the transport. The application of this technique to cone-guided fast ignition is considered, and it is shown that it can enhance the laser energy deposition in the compressed fuel plasma by a factor of 2 in comparison with the single cone target case.« less

  6. Electron beam magnetic switch for a plurality of free electron lasers

    DOEpatents

    Schlitt, Leland G.

    1984-01-01

    Apparatus for forming and utilizing a sequence of electron beam segments, each of the same temporal length (substantially 15 nsec), with consecutive beams being separated by a constant time interval of the order of 3 nsec. The beam sequence is used for simultaneous inputs to a plurality of wiggler magnet systems that also accept the laser beams to be amplified by interaction with the co-propagating electron beams. The electron beams are arranged substantially in a circle to allow proper distribution of and simultaneous switching out of the beam segments to their respective wiggler magnets.

  7. Effect of exponential density transition on self-focusing of q-Gaussian laser beam in collisionless plasma

    NASA Astrophysics Data System (ADS)

    Valkunde, Amol T.; Vhanmore, Bandopant D.; Urunkar, Trupti U.; Gavade, Kusum M.; Patil, Sandip D.; Takale, Mansing V.

    2018-05-01

    In this work, nonlinear aspects of a high intensity q-Gaussian laser beam propagating in collisionless plasma having upward density ramp of exponential profiles is studied. We have employed the nonlinearity in dielectric function of plasma by considering ponderomotive nonlinearity. The differential equation governing the dimensionless beam width parameter is achieved by using Wentzel-Kramers-Brillouin (WKB) and paraxial approximations and solved it numerically by using Runge-Kutta fourth order method. Effect of exponential density ramp profile on self-focusing of q-Gaussian laser beam for various values of q is systematically carried out and compared with results Gaussian laser beam propagating in collisionless plasma having uniform density. It is found that exponential plasma density ramp causes the laser beam to become more focused and gives reasonably interesting results.

  8. A quantitative evaluation of the L.B.W. efficiency on AISI 304 bead on plates welded under different focusing and tilted laser beam conditions

    NASA Astrophysics Data System (ADS)

    Daurelio, Giuseppe; Ludovico, Antonio D.; Lugara, M. P.; De Filippis, L. A. C.; Spera, A. M.; Rocco, S.

    2005-03-01

    The aim of this search is to evaluate the WE (Welding Efficiency) of each beads versus the different positions of the laser beam optical focus (positive or negative or zero values) respect to the work-piece surface and also versus different laser beam incidence angles (80° and 70°) by using two laser power levels (2 and 2.5 KW) and two welding speeds (3 and 6 m/min). The WE values have been reported on two DA.LU. method plots and the relate evaluations regarding the same ones as well as the recorded best parameters have been evidenced.

  9. Higher order mode laser beam intensity fluctuations in strong oceanic turbulence

    NASA Astrophysics Data System (ADS)

    Baykal, Yahya

    2017-05-01

    Intensity fluctuations of the higher order mode laser beams are evaluated when these beams propagate in a medium exhibiting strong oceanic turbulence. Our formulation involves the modified Rytov solution that extends the Rytov solution to cover strong turbulence as well, and our recently reported expression that relates the atmospheric turbulence structure constant to the oceanic turbulence parameters and oceanic wireless optical communication link parameters. The variations of the intensity fluctuations are reported against the changes of the ratio of temperature to salinity contributions to the refractive index spectrum, rate of dissipation of kinetic energy per unit mass of fluid, rate of dissipation of mean-squared temperature, viscosity and the source size of the higher order mode laser beam. Our results indicate that under any oceanic turbulence parameters, it is advantageous to employ higher order laser modes in reducing the scintillation noise in wireless optical communication links operating in a strongly turbulent ocean.

  10. 432- μm laser's beam-waist measurement for the polarimeter/interferometer on the EAST tokamak

    NASA Astrophysics Data System (ADS)

    Wang, Z. X.; Liu, H. Q.; Jie, Y. X.; Wu, M. Q.; Lan, T.; Zhu, X.; Zou, Z. Y.; Yang, Y.; Wei, X. C.; Zeng, L.; Li, G. S.; Gao, X.

    2014-10-01

    A far-infrared (FIR) polarimeter/interferometer (PI) system is under development for measurements of the current-density and the electron-density profiles in the EAST tokamak. The system will utilize three identical 432- μm CHCOOH lasers pumped by a CO2 laser. Measurements of the laser beam's waist size and position are basic works. This paper will introduce three methods with a beam profiler and several focusing optical elements. The beam profiler can be used to show the spatial energy distribution of the laser beam. The active area of the profiler is 12.4 × 12.4 mm2. Some focusing optical elements are needed to focus the beam in order for the beam profiler to receive the entire laser beam. Two principles and three methods are used in the measurement. The first and the third methods are based on the same principle, and the second method adopts an other principle. Due to the fast and convenient measurement, although the first method is a special form of the third and it can only give the size of beam waist, it is essential to the development of the experiment and it can provide guidance for the choices of the sizes of the optical elements in the next step. A concave mirror, a high-density polyethylene (HDPE) lens and a polymethylpentene (TPX) lens are each used in the measurement process. The results of these methods are close enough for the design of PI system's optical path.

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  12. Propagation of a laser beam in a time-varying waveguide. [plasma heating for controlled fusion

    NASA Technical Reports Server (NTRS)

    Chapman, J. M.; Kevorkian, J.

    1978-01-01

    The propagation of an axisymmetric laser beam in a plasma column having a radially parabolic electron density distribution is reported. For the case of an axially uniform waveguide it is found that the basic characteristics of alternating focusing and defocusing beams are maintained. However, the intensity distribution is changed at the foci and outer-beam regions. The features of paraxial beam propagation are discussed with reference to axially varying waveguides. Laser plasma coupling is considered noting the case where laser heating produces a density distribution radially parabolic near the axis and the energy absorbed over the focal length of the plasma is small. It is found that: (1) beam-propagation stability is governed by the relative magnitude of the density fluctuations existing in the axial variation of the waveguides due to laser heating, and (2) for beam propagation in a time-varying waveguide, the global instability of the propagation is a function of the initial fluctuation growth rate as compared to the initial time rate of change in the radial curvature of the waveguide.

  13. Analysis of the fluctuations of a laser beam due to thermal turbulence

    NASA Astrophysics Data System (ADS)

    Ndlovu, Sphumelele C.; Chetty, Naven

    2014-07-01

    A laser beam propagating in air and passing through a point diffraction interferometer (PDI) produces stable interferograms that can be used to extract wavefront data such as major atmospheric characteristics: turbulence strength, inner scale and outer scale of the refractive index. These parameters need to be taken into consideration when developing defense laser weapons since they can be affected by thermal fluctuations that are due to the changes in temperature in close proximity to the propagating beam and results in phase shifts that can be used to calculate the temperature which causes wavefront perturbations on a propagating beam.

  14. Intense laser-driven ion beams in the relativistic-transparency regime: acceleration, control and applications

    NASA Astrophysics Data System (ADS)

    Fernandez, Juan C.

    2016-10-01

    Laser-plasma interactions in the novel regime of relativistically-induced transparency have been harnessed to generate efficiently intense ion beams with average energies exceeding 10 MeV/nucleon (>100 MeV for protons) at ``table-top'' scales. We have discovered and utilized a self-organizing scheme that exploits persisting self-generated plasma electric ( 0.1 TV/m) and magnetic ( 104 Tesla) fields to reduce the ion-energy (Ei) spread after the laser exits the plasma, thus separating acceleration from spread reduction. In this way we routinely generate aluminum and carbon beams with narrow spectral peaks at Ei up to 310 MeV and 220 MeV, respectively, with high efficiency ( 5%). The experimental demonstration has been done at the LANL Trident laser with 0.12 PW, high-contrast, 0.65 ps Gaussian laser pulses irradiating planar foils up to 250 nm thick. In this regime, Ei scales empirically with laser intensity (I) as I 1 / 2. Our progress is enabled by high-fidelity, massive computer simulations of the experiments. This work advances next-generation compact accelerators suitable for new applications. E . g ., a carbon beam with Ei 400 MeV and 10% energy spread is suitable for fast ignition (FI) of compressed DT. The observed scaling suggests that is feasible with existing target fabrication and PW-laser technologies, using a sub-ps laser pulse with I 2.5 ×1021 W/cm2. These beams have been used on Trident to generate warm-dense matter at solid-densities, enabling us to investigate its equation of state and mixing of heterogeneous interfaces purely by plasma effects distinct from hydrodynamics. They also drive an intense neutron-beam source with great promise for important applications such as active interrogation of shielded nuclear materials. Considerations on controlling ion-beam divergence for their increased utility are discussed. Funded by the LANL LDRD program.

  15. Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator

    NASA Astrophysics Data System (ADS)

    Wang, X. L.; Xu, Z. Y.; Luo, W.; Lu, H. Y.; Zhu, Z. C.; Yan, X. Q.

    2017-09-01

    Photo-transmutation of long-lived nuclear waste induced by a high-charge relativistic electron beam (e-beam) from a laser plasma accelerator is demonstrated. A collimated relativistic e-beam with a high charge of approximately 100 nC is produced from high-intensity laser interaction with near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor and then radiates energetic bremsstrahlung photons with flux approaching 1011 per laser shot. Taking a long-lived radionuclide 126Sn as an example, the resulting transmutation reaction yield is the order of 109 per laser shot, which is two orders of magnitude higher than obtained from previous studies. It is found that at lower densities, a tightly focused laser irradiating relatively longer NCD plasmas can effectively enhance the transmutation efficiency. Furthermore, the photo-transmutation is generalized by considering mixed-nuclide waste samples, which suggests that the laser-accelerated high-charge e-beam could be an efficient tool to transmute long-lived nuclear waste.

  16. Wavefront measurement of single-mode quantum cascade laser beam for seed application in laser-produced plasma extreme ultraviolet system.

    PubMed

    Nowak, Krzysztof M; Ohta, Takeshi; Suganuma, Takashi; Yokotsuka, Toshio; Fujimoto, Junichi; Mizoguchi, Hakaru

    2012-12-01

    Quantum cascade laser (QCL) is a very attractive seed source for a multikilowatt pulsed CO2 lasers applied for driving extreme ultraviolet emitting plasmas. In this Letter, we investigate output beam properties of a QCL designed to address P18 and P20 lines of 10.6 micron band of CO2 molecule. In particular, output beam quality and stability are investigated for the first time. A well-defined linear polarization and a single-mode operation enabled a use of phase retrieval method for full description of QCL output beam. A direct, multi-image numerical phase retrieval technique was developed and successfully applied to the measured intensity patterns of a QCL beam. Very good agreement between the measured and reconstructed beam profiles was observed at distances ranging from QCL aperture to infinity, proving a good understanding of the beam propagation. The results also confirm a high spatial coherence and high stability of the beam parameters, the features expected from an excellent seed source.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jafari, M. J.; Jafari Milani, M. R., E-mail: mrj.milani@gmail.com; Niknam, A. R.

    2016-07-15

    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. Itmore » 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).« less

  18. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

    DOE PAGES

    Gauthier, M.; Kim, J. B.; Curry, C. B.; ...

    2016-08-24

    Here, we report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetitionmore » rate capability, this target is promising for future applications.« less

  19. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gauthier, M., E-mail: maxence.gauthier@stanford.edu; Kim, J. B.; Curry, C. B.

    2016-11-15

    We report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetition ratemore » capability, this target is promising for future applications.« less

  20. Role of laser beam radiance in different ceramic processing: A two wavelengths comparison

    NASA Astrophysics Data System (ADS)

    Shukla, Pratik; Lawrence, Jonathan

    2013-12-01

    Effects of laser beam radiance (brightness) of the fibre and the Nd3+:YAG laser were investigated during surface engineering of the ZrO2 and Si3N4 advanced ceramics with respect to dimensional size and microstructure of both of the advanced ceramics. Using identical process parameters, the effects of radiance of both the Nd3+:YAG laser and a fibre laser were compared thereon the two selected advanced ceramics. Both the lasers showed differences in each of the ceramics employed in relation to the microstructure and grain size as well as the dimensional size of the laser engineered tracks-notwithstanding the use of identical process parameters namely spot size; laser power; traverse speed; Gaussian beam modes; gas flow rate and gas composition as well the wavelengths. From this it was evident that the difference in the laser beam radiance between the two lasers would have had much to do with this effect. The high radiance fibre laser produced larger power per unit area in steradian when compared to the lower radiance of the Nd3+:YAG laser. This characteristically produced larger surface tracks through higher interaction temperature at the laser-ceramic interface. This in turn generated bigger melt-zones and different cooling rates which then led to the change in the microstructure of both the Si3N4 and ZrO2 advance ceramics. Owing to this, it was indicative that lasers with high radiance would result in much cheaper and cost effective laser assisted surface engineering processes, since lower laser power, faster traverse speeds, larger spot sizes could be used in comparison to lasers with lower radiance which require much slower traverse speed, higher power levels and finer spot sizes to induce the same effect thereon materials such as the advanced ceramics.

  1. Laser-driven electron beam acceleration and future application to compact light sources

    NASA Astrophysics Data System (ADS)

    Hafz, N.; Jeong, T. M.; Lee, S. K.; Pae, K. H.; Sung, J. H.; Choi, I. W.; Yu, T. J.; Jeong, Y. U.; Lee, J.

    2009-07-01

    Laser-driven plasma accelerators are gaining much attention by the advanced accelerator community due to the potential these accelerators hold in miniaturizing future high-energy and medium-energy machines. In the laser wakefield accelerator (LWFA), the ponderomotive force of an ultrashort high intensity laser pulse excites a longitudinal plasma wave or bubble. Due to huge charge separation, electric fields created in the plasma bubble can be several orders of magnitude higher than those available in conventional microwave and RF-based accelerator facilities which are limited (up to ˜100 MV/m) by material breakdown. Therefore, if an electron bunch is injected into the bubble in phase with its field, it will gain relativistic energies within an extremely short distance. Here, in the LWFA we show the generation of high-quality and high-energy electron beams up to the GeV-class within a few millimeters of gas-jet plasmas irradiated by tens of terawatt ultrashort laser pulses. Thus we realize approximately four orders of magnitude acceleration gradients higher than available by conventional technology. As a practical application of the stable high-energy electron beam generation, we are planning on injecting the electron beams into a few-meters long conventional undulator in order to realize compact X-ray synchrotron (immediate) and FEL (future) light sources. Stable laser-driven electron beam and radiation devices will surely open a new era in science, medicine and technology and will benefit a larger number of users in those fields.

  2. Laser effect on the 248 nm KrF transition using heavy ion beam pumping

    NASA Astrophysics Data System (ADS)

    Adonin, A.; Jacoby, J.; Turtikov, V.; Fertman, A.; Golubev, A.; Hoffmann, D. H. H.; Ulrich, A.; Varentsov, D.; Wieser, J.

    2007-07-01

    In December 2005 the first successful operation of a UV excimer laser pumped with a heavy ion beam was demonstrated at GSI. It was the first experiment in which the specific power deposition was sufficient to overcome laser threshold for a UV excimer scheme. The well known KrF* excimer laser line at λ=248 nm has been chosen for this experiment, because the wavelength is short, but still in the range of usual optical diagnostic tools and the emitted light can propagate in air without attenuation. A bunch compressed U+73238 beam with a particle energy of 250 MeV/u and about 110 ns pulse duration (FWHM) was used for this experiment. Single pulses of a beam intensity up to 2.5×109 particles per bunch were focused into the laser cell along the cavity axis. Compact spectrometers, high speed UV-photodiodes and gated CCD-cameras were used for diagnostics of the spontaneous and stimulated emission. As a main result of the experiment laser effect on the 248 nm KrF* excimer laser line has been obtained and verified by temporal and spectral narrowing of the laser line as well as the threshold behaviour and exponential growth of intensity with increasing pumping power. In summary it could be shown that the pumping power of the heavy ion beam at GSI is now sufficient to pump short wavelength lasers. It is planned to extend laser experiments in near future to the VUV range of the spectrum (λ<200 nm).

  3. Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Tongjun; Shen, Baifei, E-mail: bfshen@mail.shcnc.ac.cn; Xu, Jiancai, E-mail: jcxu@siom.ac.cn

    Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron–positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 10{sup 21} s{sup −1}, thus allows specific studies of fast kinetics in millimeter-thick materials withmore » a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.« less

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

    NASA Technical Reports Server (NTRS)

    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.

  5. Method and apparatus for reducing coherence of high-power laser beams

    DOEpatents

    Moncur, Norman K.; Mayer, Frederick J.

    1978-01-01

    Method and apparatus for reducing the coherence and for smoothing the power density profile of a collimated high-power laser beam in which the beam is focused at a point on the surface of a target fabricated of material having a low atomic number. The initial portion of the focused beam heats the material to form a hot reflective plasma at the material surface. The remaining, major portion of the focused beam is reflected by the plasma and recollected to form a collimated beam having reduced beam coherence.

  6. Reduction of angular divergence of laser-driven ion beams during their acceleration and transport

    NASA Astrophysics Data System (ADS)

    Zakova, M.; Pšikal, Jan; Margarone, Daniele; Maggiore, Mario; Korn, G.

    2015-05-01

    Laser plasma physics is a field of big interest because of its implications in basic science, fast ignition, medicine (i.e. hadrontherapy), astrophysics, material science, particle acceleration etc. 100-MeV class protons accelerated from the interaction of a short laser pulse with a thin target have been demonstrated. With continuing development of laser technology, greater and greater energies are expected, therefore projects focusing on various applications are being formed, e.g. ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration). One of the main characteristic and crucial disadvantage of ion beams accelerated by ultra-short intense laser pulses is their large divergence, not suitable for the most of applications. In this paper two ways how to decrease beam divergence are proposed. Firstly, impact of different design of targets on beam divergence is studied by using 2D Particlein-cell simulations (PIC). Namely, various types of targets include at foils, curved foil and foils with diverse microstructures. Obtained results show that well-designed microstructures, i.e. a hole in the center of the target, can produce proton beam with the lowest divergence. Moreover, the particle beam accelerated from a curved foil has lower divergence compared to the beam from a flat foil. Secondly, another proposed method for the divergence reduction is using of a magnetic solenoid. The trajectories of the laser accelerated particles passing through the solenoid are modeled in a simple Matlab program. Results from PIC simulations are used as input in the program. The divergence is controlled by optimizing the magnetic field inside the solenoid and installing an aperture in front of the device.

  7. Cold Cathode Electron Beam Controlled CO2 Laser Performance.

    DTIC Science & Technology

    1974-10-01

    Siegman (ref. 7), the cavity parameters are g, - 3/2, g2 3/4 so that 0he cavity will be confocal when the mirror separation is 2.5 m. The laser output was...E. Siegman , Laser Focus 7, 42, 1971. 8. W. F. Krupke and W. R. Sooy, IEEE Journal Quant. Elec. QE-5, 575, 1969. 9. 0. R. Wood, et al., Appl. Phys...U t AD/A-000 413 COLD CATHODE ELECTRON BEAM CONTROLLED C02 LASER PERFORMANCE Leslie L. McKee, 1II, et al Air Force Weapons Laboratory Kirtland Air

  8. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

    NASA Astrophysics Data System (ADS)

    Li, Chao-yu; Dong, Jun

    2016-08-01

    The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

  9. Modeling the ponderomotive interaction of high-power laser beams with collisional plasma: the FDTD-based approach.

    PubMed

    Lin, Zhili; Chen, Xudong; Ding, Panfeng; Qiu, Weibin; Pu, Jixiong

    2017-04-03

    The ponderomotive interaction of high-power laser beams with collisional plasma is modeled in the nonrelativistic regime and is simulated using the powerful finite-difference time-domain (FDTD) method for the first time in literature. The nonlinear and dissipative dielectric constant function of the collisional plasma is deduced that takes the ponderomotive effect into account and is implemented in the discrete framework of FDTD algorithms. Maclaurin series expansion approach is applied for implementing the obtained physical model and the time average of the square of light field is extracted by numerically evaluating an integral identity based on the composite trapezoidal rule for numerical integration. Two numerical examples corresponding to two different types of laser beams, Gaussian beam and vortex Laguerre-Gaussian beam, propagating in collisional plasma, are presented for specified laser and plasma parameters to verify the validity of the proposed FDTD-based approach. Simulation results show the anticipated self-focusing and attenuation phenomena of laser beams and the deformation of the spatial density distributions of electron plasma along the beam propagation path. Due to the flexibility of FDTD method in light beam excitation and accurate complex material modeling, the proposed approach has a wide application prospect in the study of the complex laser-plasma interactions in a small scale.

  10. Development of Laser Beam Transmission Strategies for Future Ground-to-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith E.; Kovalik, Joseph M.; Biswas, Abhijit; Roberts, William T.

    2007-01-01

    Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

  11. Tilt angle measurement with a Gaussian-shaped laser beam tracking

    NASA Astrophysics Data System (ADS)

    Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr; Lazar, Josef; Číp, Ondrej

    2014-05-01

    We have addressed the challenge to carry out the angular tilt stabilization of a laser guiding mirror which is intended to route a laser beam with a high energy density. Such an application requires good angular accuracy as well as large operating range, long term stability and absolute positioning. We have designed an instrument for such a high precision angular tilt measurement based on a triangulation method where a laser beam with Gaussian profile is reflected off the stabilized mirror and detected by an image sensor. As the angular deflection of the mirror causes a change of the beam spot position, the principal task is to measure the position on the image chip surface. We have employed a numerical analysis of the Gaussian intensity pattern which uses the nonlinear regression algorithm. The feasibility and performance of the method were tested by numeric modeling as well as experimentally. The experimental results indicate that the assembled instrument achieves a measurement error of 0.13 microradian in the range +/-0.65 degrees over the period of one hour. This corresponds to the dynamic range of 1:170 000.

  12. Beam wavefront and farfield control for ICF laser driver

    NASA Astrophysics Data System (ADS)

    Dai, Wanjun; Deng, Wu; Zhang, Xin; Jiang, Xuejun; Zhang, Kun; Zhou, Wei; Zhao, Junpu; Hu, Dongxia

    2010-10-01

    Five main problems of beam wavefront and farfield control in ICF laser driver are synthetically discussed, including control requirements, beam propagation principle, distortions source control, system design and adjustment optimization, active wavefront correction technology. We demonstrate that beam can be propagated well and the divergence angle of the TIL pulses can be improved to less than 60μrad with solving these problems, which meets the requirements of TIL. The results can provide theoretical and experimental support for wavefront and farfield control designing requirements of the next large scale ICF driver.

  13. Effects of beam configurations on wire melting and transfer behaviors in dual beam laser welding with filler wire

    NASA Astrophysics Data System (ADS)

    Ma, Guolong; Li, Liqun; Chen, Yanbin

    2017-06-01

    Butt joints of 2 mm thick stainless steel with 0.5 mm gap were fabricated by dual beam laser welding with filler wire technique. The wire melting and transfer behaviors with different beam configurations were investigated detailedly in a stable liquid bridge mode and an unstable droplet mode. A high speed video system assisted by a high pulse diode laser as an illumination source was utilized to record the process in real time. The difference of welding stability between single and dual beam laser welding with filler wire was also compartively studied. In liquid bridge transfer mode, the results indicated that the transfer process and welding stability were disturbed in the form of "broken-reformed" liquid bridge in tandem configuration, while improved by stabilizing the molten pool dynamics with a proper fluid pattern in side-by-side configuration, compared to sigle beam laser welding with filler wire. The droplet transfer period and critical radius were studied in droplet transfer mode. The transfer stability of side-by-side configuration with the minium transfer period and critical droplet size was better than the other two configurations. This was attributed to that the action direction and good stability of the resultant force which were beneficial to transfer process in this case. The side-by-side configuration showed obvious superiority on improving welding stability in both transfer modes. An acceptable weld bead was successfully generated even in undesirable droplet transfer mode under the present conditions.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei

    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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Manchester, Zachary; Loeb, Abraham, E-mail: zmanchester@seas.harvard.edu

    2017-03-10

    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 without active control or additional mechanical modifications. A new architecture for a passively stable sail-and-beam configuration is proposed. The novel spherical shell design for the sail 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.

  16. The random walk of a drilling laser beam

    NASA Technical Reports Server (NTRS)

    Anthony, T. R.

    1980-01-01

    The disregistry of holes drilled with a pulse laser beam in 330-micron-thick single-crystal silicon-on-sapphire wafers is examined. The exit positions of the holes were displaced from the hole entrance positions on the opposing face of the wafer, and this random displacement increased with the number of laser pulses required. A model in which the bottom of the drill hole experiences small random displacements during each laser pulse is used to describe the experimental observations. It is shown that the average random displacement caused by each pulse is only a few percent of the hole diameter and can be reduced by using as few laser pulses as necessary while avoiding the cracking and spalling of the wafer that occur with a hole drilled with a single pulse.

  17. Implementation of a Gaussian Beam Laser and Aspheric Optics for High Spatial Resolution MALDI Imaging MS

    NASA Astrophysics Data System (ADS)

    Zavalin, Andre; Yang, Junhai; Haase, Andreas; Holle, Armin; Caprioli, Richard

    2014-06-01

    We have investigated the use of a Gaussian beam laser for MALDI Imaging Mass Spectrometry to provide a precisely defined laser spot of 5 μm diameter on target using a commercial MALDI TOF instrument originally designed to produce a 20 μm diameter laser beam spot at its smallest setting. A Gaussian beam laser was installed in the instrument in combination with an aspheric focusing lens. This ion source produced sharp ion images at 5 μm spatial resolution with signals of high intensity as shown for images from thin tissue sections of mouse brain.

  18. Implementation of a Gaussian beam laser and aspheric optics for high spatial resolution MALDI imaging MS.

    PubMed

    Zavalin, Andre; Yang, Junhai; Haase, Andreas; Holle, Armin; Caprioli, Richard

    2014-06-01

    We have investigated the use of a Gaussian beam laser for MALDI Imaging Mass Spectrometry to provide a precisely defined laser spot of 5 μm diameter on target using a commercial MALDI TOF instrument originally designed to produce a 20 μm diameter laser beam spot at its smallest setting. A Gaussian beam laser was installed in the instrument in combination with an aspheric focusing lens. This ion source produced sharp ion images at 5 μm spatial resolution with signals of high intensity as shown for images from thin tissue sections of mouse brain.

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

    NASA Astrophysics Data System (ADS)

    Joshi, Chan; Malka, Victor

    2010-04-01

    The ability of short but intense laser pulses to generate high-energy electrons and ions from gaseous and solid targets has been well known since the early days of the laser fusion program. However, during the past decade there has been an explosion of experimental and theoretical activity in this area of laser-matter interaction, driven by the prospect of realizing table-top plasma accelerators for research, medical and industrial uses, and also relatively small and inexpensive plasma accelerators for high-energy physics at the frontier of particle physics. In this focus issue on laser- and beam-driven plasma accelerators, the latest advances in this field are described. Focus on Laser- and Beam-Driven Plasma Accelerators Contents Slow wave plasma structures for direct electron acceleration B D Layer, J P Palastro, A G York, T M Antonsen and H M Milchberg Cold injection for electron wakefield acceleration X Davoine, A Beck, A Lifschitz, V Malka and E Lefebvre Enhanced proton flux in the MeV range by defocused laser irradiation J S Green, D C Carroll, C Brenner, B Dromey, P S Foster, S Kar, Y T Li, K Markey, P McKenna, D Neely, A P L Robinson, M J V Streeter, M Tolley, C-G Wahlström, M H Xu and M Zepf Dose-dependent biological damage of tumour cells by laser-accelerated proton beams S D Kraft, C Richter, K Zeil, M Baumann, E Beyreuther, S Bock, M Bussmann, T E Cowan, Y Dammene, W Enghardt, U Helbig, L Karsch, T Kluge, L Laschinsky, E Lessmann, J Metzkes, D Naumburger, R Sauerbrey, M. Scḧrer, M Sobiella, J Woithe, U Schramm and J Pawelke The optimum plasma density for plasma wakefield excitation in the blowout regime W Lu, W An, M Zhou, C Joshi, C Huang and W B Mori Plasma wakefield acceleration experiments at FACET M J Hogan, T O Raubenheimer, A Seryi, P Muggli, T Katsouleas, C Huang, W Lu, W An, K A Marsh, W B Mori, C E Clayton and C Joshi Electron trapping and acceleration on a downward density ramp: a two-stage approach R M G M Trines, R Bingham, Z Najmudin

  20. High-speed electronic beam steering using injection locking of a laser-diode array

    NASA Astrophysics Data System (ADS)

    Swanson, E. A.; Abbas, G. L.; Yang, S.; Chan, V. W. S.; Fujimoto, J. G.

    1987-01-01

    High-speed electronic steering of the output beam of a 10-stripe laser-diode array is reported. The array was injection locked to a single-frequency laser diode. High-speed steering of the locked 0.5-deg-wide far-field lobe is demonstrated either by modulating the injection current of the array or by modulating the frequency of the master laser. Closed-loop tracking bandwidths of 70 kHz and 3 MHz, respectively, were obtained. The beam-steering bandwidths are limited by the FM responses of the modulated devices for both techniques.

  1. Numerical study on the selective excitation of Helmholtz-Gauss beams in end-pumped solid-state digital lasers with the control of the laser gain transverse position provided by off-axis end pumping

    NASA Astrophysics Data System (ADS)

    Tsai, Ko-Fan; Chu, Shu-Chun

    2018-03-01

    This study proposes a complete and unified method for selective excitation of any specified nearly nondiffracting Helmholtz-Gauss (HzG) beam in end-pumped solid-state digital lasers. Four types of the HzG beams: cosine-Gauss beams, Bessel-Gauss beams, Mathieu-Gauss beams, and, in particular, parabolic-Gauss beams are successfully demonstrated to be generated with the proposed methods. To the best of the authors’ knowledge, parabolic-Gauss beams have not yet been directly generated from any kind of laser system. The numerical results of this study show that one can successfully achieve any lasing HzG beams directly from the solid-state digital lasers with only added control of the laser gain transverse position provided by off-axis end pumping. This study also presents a practical digital laser set-up for easily manipulating off-axis pumping in order to achieve the control of the laser gain transverse gain position in digital lasers. The reported results in this study provide advancement of digital lasers in dynamically generating nondiffracting beams. The control of the digital laser cavity gain position creates the possibility of achieving real-time selection of more laser modes in digital lasers, and it is worth further investigation in the future.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Self-focusing and defocusing of Gaussian laser beams in collisional inhomogeneous plasmas with linear density and temperature ramps

    NASA Astrophysics Data System (ADS)

    Hashemzadeh, M.

    2018-01-01

    Self-focusing and defocusing of Gaussian laser beams in collisional inhomogeneous plasmas are investigated in the presence of various laser intensities and linear density and temperature ramps. Considering the ponderomotive force and using the momentum transfer and energy equations, the nonlinear electron density is derived. Taking into account the paraxial approximation and nonlinear electron density, a nonlinear differential equation, governing the focusing and defocusing of the laser beam, is obtained. Results show that in the absence of ramps the laser beam is focused between a minimum and a maximum value of laser intensity. For a certain value of laser intensity and initial electron density, the self-focusing process occurs in a temperature range which reaches its maximum at turning point temperature. However, the laser beam is converged in a narrow range for various amounts of initial electron density. It is indicated that the σ2 parameter and its sign can affect the self-focusing process for different values of laser intensity, initial temperature, and initial density. Finally, it is found that although the electron density ramp-down diverges the laser beam, electron density ramp-up improves the self-focusing process.

  4. Direct-writing lithography using laser diode beam focused with single elliptical microlens

    NASA Astrophysics Data System (ADS)

    Hasan, Md. Nazmul; Haque, Muttahid-Ull; Trisno, Jonathan; Lee, Yung-Chun

    2015-10-01

    A lithography method is proposed for arbitrary patterning using an elliptically diverging laser diode beam focused with a single planoconvex elliptical microlens. Simulations are performed to model the propagation properties of the laser beam and to design the elliptical microlens, which has two different profiles in the x- and y-axis directions. The microlens is fabricated using an excimer laser dragging method and is then attached to the laser diode using double-sided optically cleared adhesive (OCA) tape. Notably, the use of OCA tape removes the need for a complicated alignment procedure and thus significantly reduces the assembly cost. The minimum focused spot of the laser diode beam is investigated by performing single-shot exposure tests on a photoresist (PR) layer. Finally, the practical feasibility of this lithography technique to generate an arbitrary pattern is demonstrated by dotted and continuous features through thin chromium layer deposition on PR and a metal lift-off process. The results show that the minimum feature size for the dotted patterns is around 6.23 μm, while the minimum linewidths for continuous patterns is 6.44 μm. In other words, the proposed focusing technique has significant potential for writing any arbitrary high-resolution pattern for applications like printed circuit board fabrication.

  5. Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas

    PubMed Central

    Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; Hamilton, Christopher E.; Santiago, Miguel A.; Kreuzer, Christian; Sefkow, Adam B.; Shah, Rahul C.; Fernández, Juan C.

    2015-01-01

    Table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ∼5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (∼1012 V m−1) and magnetic (∼104 T) fields. These results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science. PMID:26657147

  6. Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas

    DOE PAGES

    Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; ...

    2015-12-11

    Here, table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ~5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (~10 12 V m –1) and magnetic (~10 4 T)more » fields. These results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science.« less

  7. External-cavity beam combining of 4-channel quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Zhang, Jin-Chuan; Zhou, Yu-Hong; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2017-09-01

    We demonstrate an external-cavity (EC) beam combining of 4-channel quantum cascade lasers (QCLs) with an output coupler which makes different QCL beams propagating coaxially. A beam combining efficiency of 35% (up to 75% near threshold) is obtained with a beam quality M2 of 5.5. A peak power of 0.64 W is achieved at a wavelength of 4.7 μm. The differences of spot characteristic between coupled and uncoupled are also showed in this letter. The QCLs in this EC system do not have heat crosstalk so that the system can be used for high power beam combining of QCLs.

  8. Generation of high-order Hermite-Gaussian modes in end-pumped solid-state lasers for square vortex array laser beam generation.

    PubMed

    Chu, Shu-Chun; Chen, Yun-Ting; Tsai, Ko-Fan; Otsuka, Kenju

    2012-03-26

    This study reports the first systematic approach to the excitation of all high-order Hermite-Gaussian modes (HGMs) in end-pumped solid-state lasers. This study uses a metal-wire-inserted laser resonator accompanied with the "off axis pumping" approach. This study presents numerical analysis of the excitation of HGMs in end-pumped solid-state lasers and experimentally generated HGM patterns. This study also experimentally demonstrates the generation of an square vortex array laser beams by passing specific high-order HGMs (HGn,n + 1 or HGn + 1,n modes) through a Dove prism-embedded unbalanced Mach-Zehnder interferometer [Optics Express 16, 19934-19949]. The resulting square vortex array laser beams with embedded vortexes aligned in a square array can be applied to multi-spot dark optical traps in the future.

  9. Laser-driven relativistic electron beam interaction with solid dielectric

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sarkisov, G. S.; Ivanov, V. V.; Leblanc, P.

    2012-07-30

    The multi-frames shadowgraphy, interferometry and polarimetry diagnostics with sub-ps time resolution were used for an investigation of ionization wave dynamics inside a glass target induced by laser-driven relativistic electron beam. Experiments were done using the 50 TW Leopard laser at the UNR. For a laser flux of {approx}2 Multiplication-Sign 10{sup 18}W/cm{sup 2} a hemispherical ionization wave propagates at c/3. The maximum of the electron density inside the glass target is {approx}2 Multiplication-Sign 10{sup 19}cm{sup -3}. Magnetic and electric fields are less than {approx}15 kG and {approx}1 MV/cm, respectively. The electron temperature has a maximum of {approx}0.5 eV. 2D interference phasemore » shift shows the 'fountain effect' of electron beam. The very low ionization inside glass target {approx}0.1% suggests a fast recombination at the sub-ps time scale. 2D PIC-simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields.« less

  10. Ultrafast Bessel beams: advanced tools for laser materials processing

    NASA Astrophysics Data System (ADS)

    Stoian, Razvan; Bhuyan, Manoj K.; Zhang, Guodong; Cheng, Guanghua; Meyer, Remy; Courvoisier, Francois

    2018-05-01

    Ultrafast Bessel beams demonstrate a significant capacity of structuring transparent materials with a high degree of accuracy and exceptional aspect ratio. The ability to localize energy on the nanometer scale (bypassing the 100-nm milestone) makes them ideal tools for advanced laser nanoscale processing on surfaces and in the bulk. This allows to generate and combine micron and nano-sized features into hybrid structures that show novel functionalities. Their high aspect ratio and the accurate location can equally drive an efficient material modification and processing strategy on large dimensions. We review, here, the main concepts of generating and using Bessel non-diffractive beams and their remarkable features, discuss general characteristics of their interaction with matter in ablation and material modification regimes, and advocate their use for obtaining hybrid micro and nanoscale structures in two and three dimensions (2D and 3D) performing complex functions. High-throughput applications are indicated. The example list ranges from surface nanostructuring and laser cutting to ultrafast laser welding and the fabrication of 3D photonic systems embedded in the volume.

  11. Simplified Architecture for Precise Aiming of a Deep-Space Communication Laser Transceiver

    NASA Technical Reports Server (NTRS)

    Ortiz, Gerard G.; Farr, William H.; Charles, Jeffrey R.

    2011-01-01

    The simplified architecture is a minimal system for a deep-space optical communications transceiver. For a deepspace optical communications link the simplest form of the transceiver requires (1) an efficient modulated optical source, (2) a point-ahead mechanism (PAM) to compensate for two-way light travel, (3) an aperture to reduce the divergence of the transmit laser communication signal and also to collect the uplink communication signal, and (4) a receive detector to sense the uplink communication signal. Additional components are introduced to mitigate for spacecraft microvibrations and to improve the pointing accuracy. The Canonical Transceiver implements this simplified architecture (see figure). A single photon-counting smart focal plane sensor combines acquisition, tracking, and forward link data detection functionality. This improves optical efficiency by eliminating channel splits. A transmit laser blind sensor (e.g. silicon with 1,550-nm beam) provides transmit beam-pointing feedback via the two-photon absorption (TPA) process. This vastly improves the transmit/receive isolation because only the focused transmit beam is detected. A piezoelectric tiptilt actuator implements the required point-ahead angle. This point-ahead mechanism has been demonstrated to have near zero quiescent power and is flight qualified. This architecture also uses an innovative 100-mHz resonant frequency passive isolation platform to filter spacecraft vibrations with voice coil actuators for active tip-tilt correction below the resonant frequency. The canonical deep-space optical communications transceiver makes synergistic use of innovative technologies to reduce size, weight, power, and cost. This optical transceiver can be used to retire risks associated with deep-space optical communications on a planetary pathfinder mission and is complementary to ongoing lunar and access link developments.

  12. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, S.; Craxton, R.S.; Soures, J.

    1990-10-02

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temporal oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation. 16 figs.

  13. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, Stanley; Craxton, R. Stephen; Soures, John

    1990-01-01

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.

  14. Comparison of three methods reducing the beam parameter product of a laser diode stack for long range laser illumination applications

    NASA Astrophysics Data System (ADS)

    Lutz, Yves; Poyet, Jean-Michel; Metzger, Nicolas

    2013-10-01

    Laser diode stacks are interesting laser sources for active imaging illuminators. They allow the accumulation of large amounts of energy in multi-pulse mode, which is well suited for long-range image recording. Even when laser diode stacks are equipped with fast-axis collimation (FAC) and slow-axis collimation (SAC) microlenses, their beam parameter product (BPP) are not compatible with a direct use in highly efficient and compact illuminators. This is particularly true when narrow divergences are required such as for long range applications. To overcome these difficulties, we conducted investigations in three different ways. A first near infrared illuminator based on the use of conductively cooled mini-bars was designed, realized and successfully tested during outdoor experimentations. This custom specified stack was then replaced in a second step by an off-the-shelf FAC + SAC micro lensed stack where the brightness was increased by polarization overlapping. The third method still based on a commercial laser diode stack uses a non imaging optical shaping principle resulting in a virtually restacked laser source with enhanced beam parameters. This low cost, efficient and low alignment sensitivity beam shaping method allows obtaining a compact and high performance laser diode illuminator for long range active imaging applications. The three methods are presented and compared in this paper.

  15. Studies of the Influence of Beam Profile and Cooling Conditions on the Laser Deposition of a Directionally-Solidified Superalloy.

    PubMed

    Yang, Shuo; Du, Dong; Chang, Baohua

    2018-02-04

    In the laser deposition of single crystal and directionally-solidified superalloys, it is desired to form laser deposits with high volume fractions of columnar grains by suppressing the columnar-to-equiaxed transition efficiently. In this paper, the influence of beam profile (circular and square shapes) and cooling conditions (natural cooling and forced cooling) on the geometric morphology and microstructure of deposits were experimentally studied in the laser deposition of a directionally-solidified superalloy, IC10, and the mechanisms of influence were revealed through a numerical simulation of the thermal processes during laser deposition. The results show that wider and thinner deposits were obtained with the square laser beam than those with the circular laser beam, regardless of whether natural or forced cooling conditions was used. The heights and contact angles of deposits were notably increased due to the reduced substrate temperatures by the application of forced cooling for both laser beam profiles. Under natural cooling conditions, columnar grains formed epitaxially at both the center and the edges of the deposits with the square laser beam, but only at the center of the deposits with the circular laser beam; under forced cooling conditions, columnar grains formed at both the center and the edges of deposits regardless of the laser beam profile. The high ratios of thermal gradient and solidification velocity in the height direction of the deposits were favorable to forming deposits with higher volume fractions of columnar grains.

  16. Studies of the Influence of Beam Profile and Cooling Conditions on the Laser Deposition of a Directionally-Solidified Superalloy

    PubMed Central

    Yang, Shuo; Du, Dong

    2018-01-01

    In the laser deposition of single crystal and directionally-solidified superalloys, it is desired to form laser deposits with high volume fractions of columnar grains by suppressing the columnar-to-equiaxed transition efficiently. In this paper, the influence of beam profile (circular and square shapes) and cooling conditions (natural cooling and forced cooling) on the geometric morphology and microstructure of deposits were experimentally studied in the laser deposition of a directionally-solidified superalloy, IC10, and the mechanisms of influence were revealed through a numerical simulation of the thermal processes during laser deposition. The results show that wider and thinner deposits were obtained with the square laser beam than those with the circular laser beam, regardless of whether natural or forced cooling conditions was used. The heights and contact angles of deposits were notably increased due to the reduced substrate temperatures by the application of forced cooling for both laser beam profiles. Under natural cooling conditions, columnar grains formed epitaxially at both the center and the edges of the deposits with the square laser beam, but only at the center of the deposits with the circular laser beam; under forced cooling conditions, columnar grains formed at both the center and the edges of deposits regardless of the laser beam profile. The high ratios of thermal gradient and solidification velocity in the height direction of the deposits were favorable to forming deposits with higher volume fractions of columnar grains. PMID:29401715

  17. Laser beamed power: Satellite demonstration applications

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Westerlund, Larry H.

    1992-01-01

    It is possible to use a ground-based laser to beam light to the solar arrays of orbiting satellites, to a level sufficient to provide all or some of the operating power required. Near-term applications of this technology for providing supplemental power to existing satellites are discussed. Two missions with significant commercial pay-off are supplementing solar power for radiation-degraded arrays and providing satellite power during eclipse for satellites with failed batteries.

  18. Application of partially coherent modes for studying generation of a Gaussian partially coherent laser beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Suvorov, A A

    2010-10-15

    The problem of steady-state generation of a Gaussian partially coherent beam in a stable-cavity laser is considered within the framework of the method of expansion of the radiation coherence function in partially coherent modes. We discuss the conditions whose fulfilment makes it possible to neglect the intermode beatings of the radiation field and the effect of the gain dispersion on the steady-state generation of multimode partially coherent radiation. Based on the simplified model, we solve the self-consistent problem of generation of a Gaussian partially coherent beam for the given laser pump conditions and the resonator parameters. The dependence of themore » beam characteristics (power, radius, etc.) on the active medium properties and the resonator parameters is obtained. (laser beams)« less

  19. Pulsed dye laser treatment of rosacea using a novel 15 mm diameter treatment beam.

    PubMed

    Bernstein, Eric F; Schomacker, Kevin; Paranjape, Amit; Jones, Christopher J

    2018-04-10

    The pulsed-dye laser has been used to treat facial redness and rosacea for decades. Recent advances in dye laser technology enable 50% higher output energies supporting 50% larger treatment areas, and beam-diameters up to 15 mm with clinically-relevant fluences. In this study, we investigate this novel pulsed-dye laser using a 15 mm diameter beam for treatment of rosacea. Twenty subjects with erythemato-telangiectatic rosacea were enrolled in the study. A total of 4 monthly treatments were administered, first treating linear vessels with a 3 × 10 mm elliptical beam, then diffuse redness with a 15-mm diameter circular beam. Blinded assessment of digital, cross-polarized photographs taken 2 months following the last treatment was performed using an 11-point clearance scale. Nineteen subjects completed the study. Blinded reviewers correctly identified baseline photos in 55 out of the total of 57 images (96.5%). The blinded reviewers scored 17 of the 19 subjects with an improvement greater than 40%, and 11 of the 19 subjects greater than 50%. The average improvement was 53.9%. Side effects were limited to mild edema, mild to moderate erythema, and mild to moderate bruising. This study demonstrates that a newly designed pulsed-dye laser having a novel 15-mm diameter treatment beam improves the appearance of rosacea with a favorable safety profile. Lasers Surg. Med. 9999:1-5, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

  20. Collective effects in the Thomson back-scattering between a laser pulse and a relativistic electron beam

    NASA Astrophysics Data System (ADS)

    Bacci, A.; Maroli, C.; Petrillo, V.; Serafini, L.

    2006-08-01

    Collective effects in the radiation emission via Thomson back-scattering of an intense optical laser pulse by high brightness electron beams are analyzed. The micro-bunching of the electron beam on the scale of the wavelength of the emitted radiation and the consequent free-electron-laser instability may significantly enhance the number of photons emitted. Scaling-laws of the radiation properties, both in the collective and incoherent spontaneous regimes versus laser and electron beam parameters are discussed in the framework of the one-dimensional model.

  1. Additive Manufacturing Processes: Selective Laser Melting, Electron Beam Melting and Binder Jetting—Selection Guidelines

    PubMed Central

    Konda Gokuldoss, Prashanth; Kolla, Sri; Eckert, Jürgen

    2017-01-01

    Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties. PMID:28773031

  2. Additive Manufacturing Processes: Selective Laser Melting, Electron Beam Melting and Binder Jetting-Selection Guidelines.

    PubMed

    Gokuldoss, Prashanth Konda; Kolla, Sri; Eckert, Jürgen

    2017-06-19

    Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties.

  3. Optical levitation of absorbing particles with a nominally Gaussian laser beam.

    PubMed

    Huisken, Jan; Stelzer, Ernst H K

    2002-07-15

    We use a Gaussian laser beam to study the levitation of absorbing Mie particles. Several metal oxide particles are stably levitated, and their movement over time is recorded. Our studies show that the position of each particle is highly dependent on the other particles' locations. The observations are explained by the phenomenon of thermal creep. The increased local pressure that is due to a temperature gradient along the particle's surface induces levitation. The particles rest close to minima in the intensity distribution near the optical axis. An experiment is suggested that can be used to locate these minima in a laser beam.

  4. Efficient monoenergetic proton beam from ultra-fast laser interaction with nanostructured targets

    NASA Astrophysics Data System (ADS)

    Fazeli, R.

    2018-03-01

    The broad energy spectrum of laser-accelerated proton beams is the most important difficulty associated with such particle sources on the way to future applications such as medical therapy, proton imaging, inertial fusion, and high-energy physics. The generation of proton beams with enhanced monoenergetic features through an ultra-intense laser interaction with optimized nanostructured targets is reported. Targets were irradiated by 40 fs laser pulses of intensity 5.5 ×1020 W c m -2 and wavelength 1 μm. The results of multi-parametric Particle-in-Cell calculations showed that proton beams with considerably reduced energy spread can be obtained by using the proposed nanostructured target. At optimized target dimensions, the proton spectrum was found to exhibit a narrow peak at about 63 MeV with a relative energy spread of ΔE /Epeak˜ 5 % which is efficiently lower than what is expected for unstructured double layer targets (˜70%).

  5. Non-mechanical beam control for entry, descent and landing laser radar (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Stockley, Jay E.; Kluttz, Kelly; Hosting, Lance; Serati, Steve; Bradley, Cullen P.; McManamon, Paul F.; Amzajerdian, Farzin

    2017-05-01

    Laser radar for entry, descent, and landing (EDL) applications as well as the space docking problem could benefit from a low size, weight, and power (SWaP) beam control system. Moreover, an inertia free approach employing non-mechanical beam control is also attractive for laser radar that is intended to be employed aboard space platforms. We are investigating a non-mechanical beam steering (NMBS) sub-system based on liquid crystal polarization grating (LCPG) technology with emphasis placed on improved throughput and significant weight reduction by combining components and drastically reducing substrate thicknesses. In addition to the advantages of non-mechanical, gimbal free beam control, and greatly improved SWaP, our approach also enables wide area scanning using a scalable architecture. An extraterrestrial application entails additional environmental constraints, consequently an environmental test plan tailored to an EDL mission will also be discussed. In addition, we will present advances in continuous fine steering technology which would complement the coarse steering LCPG technology. A low-SWaP, non-mechanical beam control system could be used in many laser radar remote sensing applications including meteorological studies and agricultural or environmental surveys in addition to the entry, descent, and landing application.

  6. Target diagnostics for commissioning the AWE HELEN Laser Facility 100 TW chirped pulse amplification beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eagleton, R. T.; Clark, E. L.; Davies, H. M.

    2006-10-15

    The capability of the HELEN laser at the Atomic Weapons Establishment Aldermaston has been enhanced by the addition of a short-pulse laser beam to augment the twin opposing nanosecond time scale beams. The short-pulse beam utilizes the chirped pulse amplification (CPA) technique and is capable of delivering up to 60 J on target in a 500 fs pulse, around 100 TW, at the fundamental laser wavelength of 1.054 {mu}m. During the commissioning phase a number of diagnostic systems have been fielded, these include: x-ray pinhole imaging of the laser heated spot, charged particle time of flight, thermoluminescent dosimeter array, calibratedmore » radiochromic film, and CR39 nuclear track detector. These diagnostic systems have been used to verify the performance of the CPA beam to achieve a focused intensity of around 10{sup 19} W cm{sup -2} and to underwrite the facility radiological safety system.« less

  7. Terahertz radiation generation by beating of two laser beams in a collisional plasma with oblique magnetic field

    NASA Astrophysics Data System (ADS)

    Hematizadeh, Ayoob; Jazayeri, Seyed Masud; Ghafary, Bijan

    2018-02-01

    A scheme for excitation of terahertz (THz) radiation is presented by photo mixing of two super-Gaussian laser beams in a rippled density collisional magnetized plasma. Lasers having different frequencies and wave numbers but the same electric fields create a ponderomotive force on the electrons of plasma in the beating frequency. Super-Gaussian laser beam has the exclusive features such as steep gradient in laser intensity distribution, wider cross-section in comparison with Gaussian profiles, which make stronger ponderomotive force and higher THz radiation. The magnetic field is considered oblique to laser beams propagation direction; in this case, depending on the phase matching conditions different mode waves can propagate in plasma. It is found that amplitude and efficiency of the emitted THz radiation not only are sensitive to the beating frequency, collision frequency, and magnetic field strength but to the angle between laser beams and static magnetic field. The efficiency of THz radiation can be optimized in a certain angle.

  8. Concept of the solar-pumped laser-photovoltaics combined system and its application to laser beam power feeding to electric vehicles

    NASA Astrophysics Data System (ADS)

    Motohiro, Tomoyoshi; Takeda, Yasuhiko; Ito, Hiroshi; Hasegawa, Kazuo; Ikesue, Akio; Ichikawa, Tadashi; Higuchi, Kazuo; Ichiki, Akihisa; Mizuno, Shintaro; Ito, Tadashi; Yamada, Noboru; Nath Luitel, Hom; Kajino, Tsutomu; Terazawa, Hidetaka; Takimoto, Satoshi; Watanabe, Kemmei

    2017-08-01

    We have developed a compact solar-pumped laser (µSPL) employing an off-axis parabolic mirror with an aperture of 76.2 mm diameter and an yttrium aluminum garnet (YAG) ceramic rod of φ1 mm × 10 mm doped with 1% Nd and 0.1% Cr as a laser medium. The laser oscillation wavelength of 1.06 µm, just below the optical absorption edge of Si cells, is suitable for photoelectric conversion with minimal thermal loss. The concept of laser beam power feeding to an electric vehicle equipped with a photovoltaic panel on the roof was proposed by Ueda in 2010, in which the electricity generated by solar panels over the road is utilized to drive a semiconductor laser located on each traffic signal along the road. By substituting this solar-electricity-driven semiconductor laser with a solar-pumped laser, the energy loss of over 50% in converting the solar electricity to a laser beam can be eliminated. The overall feasibility of this system in an urban area such as Tokyo was investigated.

  9. Measurement of Refractive Index Gradients by Deflection of a Laser Beam

    ERIC Educational Resources Information Center

    Barnard, A. J.; Ahlborn, B.

    1975-01-01

    In this simple experiment for an undergraduate laboratory a laser beam is passed through the mixing zone of two liquids with different refractive indices. The spatial variation of the refractive index, at different times during the mixing, can be determined from the observed deflection of the beam. (Author)

  10. Study of beam aberrations in a germanium XXIII XUV laser amplifier

    NASA Astrophysics Data System (ADS)

    Smith, C. G.; Key, M. H.; Cairns, G.; Dwivedi, L.; Krishnan, J.; Lewis, C. L. S.; MacPhee, A. G.; Neely, D.; Ramsden, S. A.; Tallents, G.

    1996-02-01

    A beam of amplified spontaneous emission at {23.2}/{23.6}nm from a GeXXIII XUV laser has been injected into a separate amplifier plasma and the astigmatic aberrations introduced by plasma density gradients in the amplifier have been estimated from analysis of images of the amplified beam.

  11. Laser beam coupling with capillary discharge plasma for laser wakefield acceleration applications

    NASA Astrophysics Data System (ADS)

    Bagdasarov, G. A.; Sasorov, P. V.; Gasilov, V. A.; Boldarev, A. S.; Olkhovskaya, O. G.; Benedetti, C.; Bulanov, S. S.; Gonsalves, A.; Mao, H.-S.; Schroeder, C. B.; van Tilborg, J.; Esarey, E.; Leemans, W. P.; Levato, T.; Margarone, D.; Korn, G.

    2017-08-01

    One of the most robust methods, demonstrated to date, of accelerating electron beams by laser-plasma sources is the utilization of plasma channels generated by the capillary discharges. Although the spatial structure of the installation is simple in principle, there may be some important effects caused by the open ends of the capillary, by the supplying channels etc., which require a detailed 3D modeling of the processes. In the present work, such simulations are performed using the code MARPLE. First, the process of capillary filling with cold hydrogen before the discharge is fired, through the side supply channels is simulated. Second, the simulation of the capillary discharge is performed with the goal to obtain a time-dependent spatial distribution of the electron density near the open ends of the capillary as well as inside the capillary. Finally, to evaluate the effectiveness of the beam coupling with the channeling plasma wave guide and of the electron acceleration, modeling of the laser-plasma interaction was performed with the code INF&RNO.

  12. Beam profile measurements for target designators

    NASA Astrophysics Data System (ADS)

    Frank, J. D.

    1985-02-01

    An American aerospace company has conducted a number of investigations with the aim to improve on the tedious slow manual methods of measuring pulsed lasers for rangefinders, giving particular attention to beam divergence which is studied by varying aperture sizes and positions in the laser beam path. Three instruments have been developed to make the involved work easier to perform. One of these, the Automatic Laser Instrumentation and Measurement System (ALIMS), consists of an optical bench, a digital computer, and three bays of associated electronic instruments. ALIMS uses the aperture method to measure laser beam alignment and divergence. The Laser Intensity Profile System (LIPS) consists of a covered optical bench and a two bay electronic equipment and control console. The Automatic Laser Test Set (ALTS) utilizes a 50 x 50 silicon photodiode array to characterize military laser systems automatically. Details regarding the conducted determinations are discussed.

  13. Image Processing In Laser-Beam-Steering Subsystem

    NASA Technical Reports Server (NTRS)

    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.

  14. Deformation of a laser beam in the fabrication of graphite microstructures inside a volume of diamond

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kononenko, T V; Zavedeev, E V

    2016-03-31

    We report a theoretical and experimental study of the energy profile deformation along the laser beam axis during the fabrication of graphite microstructures inside a diamond crystal. The numerical simulation shows that the use of a focusing lens with a numerical aperture NA < 0.1 at a focusing depth of up to 2 mm makes it possible to avoid a noticeable change in the energy profile of the beam due to the spherical aberration that occurs in the case of refraction of the focused laser beam at the air – diamond interface. The calculation results are confirmed by experimental datamore » on the distribution of the laser intensity along the beam axis in front of its focal plane, derived from observations of graphitisation wave propagation in diamond. The effect of radiation self-focusing on laser-induced graphitisation of diamond is analysed. It is shown that if the wavefront distortion due to self-focusing can be neglected at a minimum pulse energy required for the optical breakdown of diamond, then an increase in the beam distortion with increasing pulse energy has no effect on the graphitisation process. (interaction of laser radiation with matter)« less

  15. A new method for incoherent combining of far-field laser beams based on multiple faculae recognition

    NASA Astrophysics Data System (ADS)

    Ye, Demao; Li, Sichao; Yan, Zhihui; Zhang, Zenan; Liu, Yuan

    2018-03-01

    Compared to coherent beam combining, incoherent beam combining can complete the output of high power laser beam with high efficiency, simple structure, low cost and high thermal damage resistance, and it is easy to realize in engineering. Higher target power is achieved by incoherent beam combination which using technology of multi-channel optical path correction. However, each channel forms a spot in the far field respectively, which cannot form higher laser power density with low overlap ratio of faculae. In order to improve the combat effectiveness of the system, it is necessary to overlap different faculae that improve the target energy density. Hence, a novel method for incoherent combining of far-field laser beams is present. The method compromises piezoelectric ceramic technology and evaluation algorithm of faculae coincidence degree which based on high precision multi-channel optical path correction. The results show that the faculae recognition algorithm is low-latency(less than 10ms), which can meet the needs of practical engineering. Furthermore, the real time focusing ability of far field faculae is improved which was beneficial to the engineering of high-energy laser weapon or other laser jamming systems.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Uniform heating of materials into the warm dense matter regime with laser-driven quasimonoenergetic ion beams

    NASA Astrophysics Data System (ADS)

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2015-12-01

    In a recent experiment at the Trident laser facility, a laser-driven beam of quasimonoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable at Trident, with a finite energy spread of ΔE /E ˜20 %, are expected to heat the targets more uniformly than a beam of 140-MeV aluminum ions with zero energy spread. The robustness of the expected heating uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.

  18. Laser Plasma Instability (LPI) Driven Light Scattering Measurements with 44 beam-lines of Nike KrF Laser^*

    NASA Astrophysics Data System (ADS)

    Oh, J.; Weaver, J. L.; Kehne, D. M.; Phillips, L. S.; Obenschain, S. P.; Serlin, V.; McLean, E. A.; Lehmberg, R. H.; Manka, C. K.

    2009-11-01

    With short wavelength (248 nm), large bandwidth (˜1 THz), and ISI beam smoothing, Nike KrF laser provides unique opportunities of LPI research for direct-drive inertial confinement fusion. Previous experiments at intensities (10^15˜10^16 W/cm^2) exceeded two-plasmon decay (TPD) instability threshold using 12 beam-lines of Nike laser.^a,b For further experiments to study LPI excitation in bigger plasma volumes, 44 Nike main beams have been used to produce plasmas with total laser energies up to 1 kJ of ˜350 psec FWHM pulses. This talk will present results of the recent LPI experiment focusing on light emission data in spectral ranges relevant to the Raman (SRS) and TPD instabilities. The primary diagnostics were time-resolved spectrometers with an absolute-intensity-calibrated photodiode array in (0.4˜0.8)φ0 and a streak camera near 0.5φ0. Blackbody temperature and expansion speed measurements of the plasmas were also made. The experiment was conducted at laser intensities of (1˜4)x10^15 W/cm^2 on solid planar CH targets. ^a J. L. Weaver, et al, NO4.14, APS DPP (2008) ^b J. Oh, et al, NO4.15, APS DPP (2008) * Work supported by DoE/NNSA and performed at Naval Research Laboratory.

  19. Terahertz plasmonic lasers with narrow beams and large tunability

    NASA Astrophysics Data System (ADS)

    Jin, Yuan; Wu, Chongzhao; Reno, John L.; Kumar, Sushil

    2017-02-01

    Plasmonic lasers generate coherent long-range or localized surface-plasmon-polaritons (SPPs), where the SPP mode exists at the interface of the metal (or a metallic nanoparticle) and a dielectric. Metallic-cavities sup- porting SPP modes are also utilized for terahertz quantum-cascade lasers (QCLs). Due to subwavelength apertures, plasmonic lasers have highly divergent radiation patterns. Recently, we theoretically and experimentally demonstrated a new technique for implementing distributed-feedback (DFB), which is termed as an antenna- feedback scheme, to establish a hybrid SPP mode in the surrounding medium of a plasmonic laser's cavity with a large wavefront. This technique allows such lasers to radiate in narrow beams without requirement of any specific design considerations for phase-matching. Experimental demonstration is done for terahertz QCLs that show beam-divergence as small as 4-degrees. The antenna-feedback scheme has a characteristic feature in that refractive-index of the laser's surrounding medium affects its radiative frequency in the same vein as refractive- index of the cavity. Hence, any perturbations in the refractive-index of the surrounding medium could lead to large modulation in the laser's emission frequency. Along this line, we report 57 GHz reversible, continuous, and mode-hop-free tuning of such QCLs operating at 78 K based on post-process deposition/etching of a dielectric on an already mounted QCL chip. This is the largest tuning range achieved for terahertz QCLs when operating much above the temperature of liquid-Helium. We review the aforementioned experimental results and discuss methods to increase optical power output from terahertz QCLs with antenna-feedback. Peak power output of 13 mW is realized for a 3.3 THz QCL operating in a Stirling cooler at 54 K. A new dual-slit photonic structure based on antenna-feedback scheme is proposed to further improve output power as well as provide enhanced tunability.

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

    NASA Technical Reports Server (NTRS)

    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.