The Review of Laser Engineering
Online ISSN : 1349-6603
Print ISSN : 0387-0200
ISSN-L : 0387-0200
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Volume 26, Issue 10
Displaying 1-11 of 11 articles from this issue
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  • [title in Japanese]
    Hiroshi KASHIWAGI
    1998 Volume 26 Issue 10 Pages 721
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.721
    JOURNAL FREE ACCESS
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  • On the Topical Papers of Laser Beam-Quality Measurement and Characterization
    Kunihiko WASHIO
    1998 Volume 26 Issue 10 Pages 722
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.722
    JOURNAL FREE ACCESS
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  • Concept for Measuring Laser Beam-Quality Parameters
    Takunori TAIRA
    1998 Volume 26 Issue 10 Pages 723-729
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.723
    JOURNAL FREE ACCESS
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    This paper provides brief descriptions of recent developments in the basic formulas and measurement methods for determining laser beam-quality. The M2 factor concept has been studied in order to describe the laser beam quality of real laser beams, including potentially multimode and arbitrarily distorted laser beams. The study shows that the M2 value can be determined by measuring the beam spot sizes around the beam-waist. In addition, various methods for measuring beam spot sizes are discussed. Finally, the beam quality of fiberbundled diode lasers is evaluated by the moving-slit method. A good agreement is obtained between the theoretical and experimental beam propagation results.
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  • Beam-Quality Measurement of High-Power Lasers for Material Processing Applications
    Koji YASUI, Tetsuo KOJIMA, Shuichi FUJIKAWA, Yushi TAKENAKA, Jyunichi ...
    1998 Volume 26 Issue 10 Pages 730-734
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.730
    JOURNAL FREE ACCESS
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    The basic formulas and procedures for beam-quality measurements have been investigated for high-power industrial lasers designed for material processing applications. The beam quality definition of M2 is studied assuming laser beams extracted from stable resonators. The importance of the M2 definition is related to recent results with high-power high-brightness CO2 lasers and Nd: YAG lasers.
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  • Diode Laser Focusing Optics for Optical Disc Applications
    Kimio TATSUNO
    1998 Volume 26 Issue 10 Pages 735-739
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.735
    JOURNAL FREE ACCESS
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    Wave aberration analysis, measurement, and correction of diode laser beams applied to optical disc systemsare reported. The results can be applied to other optical systems such as optical communications, laser beamprintings, diode pumped solid state lasers, wave guide type nonlinear wavelength converters, etc.
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  • Beam-Shaping Techniques and Focusing Performance for a Diode Bar Used as a Pumping Source
    Takao IZAWA
    1998 Volume 26 Issue 10 Pages 740-743
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.740
    JOURNAL FREE ACCESS
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    The end-pumping scheme in diode-pumped solid-state lasers has promised the achivement of high opticalconversion efficiency. However, in the case of using high-power diode bars as a pumping sourse, it is difficultto focuse the small-diamater beams required for an end-pumping laser due to the poor beam quality of thediode bar. This paper reviews beam-shaping techniques to improve the quality of the diode-bar and to achievea suitably focused spot size for end pumping.
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  • A Laser System for Detecting Surface Flaws of a Molding
    Jing CHEN, Toshihiko YAMAGUCHI, Keiji TANIGUCHI, Katsuhiko ASADA, Masa ...
    1998 Volume 26 Issue 10 Pages 744-746
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.744
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    An optical system for detecting the surface flaws of a molding, e. g., the brake disc of a car, has been proposed which involves a sheet-like laser beam of length, l, and width, w, as a probing light. Optimum conditions forthe sheet like laser beam were found to be l=10 mm and w=0.5 mm for a flaw diameter of 2 mm which is thesmallest diameter that can be detected in practice. The system consists of a sensor head including a lightsource and a light receiver, and a processing system including an amplifier, an A/D converter, a personalcomputer and a display. This system can detect all flaws in a few second by using a sampling frequency of dataacquisition at 1 kHz.
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  • 5.5kW YAG Laser System with Combined Beams from Three Oscillators and Its Application to Materials Processing
    Toru NARIKIYO, Hiroshi MIURA, Shigeki FUJINAGA, Akira OHMORI, Syuichi ...
    1998 Volume 26 Issue 10 Pages 747-753
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.747
    JOURNAL FREE ACCESS
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    We constructed a system incorporating integration optics and a newly developed pulse excited YAG laseroscillator of 1.5 kW average power. Two CW YAG laser oscillators of 2 kW average power, and a PC were alsoincorporated. The integration optics combined three laser beams transmitted through optical fibers. Using thissystem, we are able to obtain the following results. (1) Good welding quality was achieved with a focused spotdiameter with integration optics. Furthermore, quality was attained without changing the work distance byadjusting the collimator lenses of the integration optics. (2) The delay time between the pulse excited YAGlaser beam and the rectangularly modulated CW YAG laser beams greatly influenced the cross-sectional shapesof weld. The full penetration weld of a 10 mm thick SUS304 plate is obtained by half power density of thesimultaneous irradiation of the pulse excited and two rectangularly modulated CW YAG laser beams, when theformer beam is irradiated just after a keyhole has been formed by the latter laser beams. (3) The deepestpenetration depth and the largest volume of weld is obtained from the overhead position welding, as comparedto the flat, horizontal, and vertical position welding.
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  • Study on Analyses of Frequency Characteristics of Laser Processing Sound
    Tsuneo KURITA, Tomohiko ONO, Noboru MORITA
    1998 Volume 26 Issue 10 Pages 754-758
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.754
    JOURNAL FREE ACCESS
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    The final goal of this research is to construct a laser processing system to manufacture stepped shapes or freeform surfaces using detected sound. In order to achieve this goal, basic investigations concerning the analysisof characteristics of the laser processing sound are necessary. The purposes of this study are to determine therelationship between transfer functions and sound frequencies when a work material, its dimensions, andprocessing conditions are changed, and to calculate the frequency characteristics of sound if a high frequencylaser beam is utilized for laser grooving. The main findings are as follows. 1) It was shown experimentallythat the distribution of transfer functions versus sound frequencies has almost the same pattern even if the laserenergy per pulse, the work material, and its dimensions are changed. 2) The numerical analyses revealed thatthe pattern of the distribution of sound pressure level qualitatively coincides with that of the experimentalresults.
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  • Report on Ultrafast Phenomena '98
    Nobuhiko SARUKURA
    1998 Volume 26 Issue 10 Pages 759-761
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.759
    JOURNAL FREE ACCESS
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  • The Technical Basis of Lasers: II
    All Solid-State Lasers
    Masanobu YAMANAKA, Sadao NAKAI
    1998 Volume 26 Issue 10 Pages 762-768
    Published: October 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.762
    JOURNAL FREE ACCESS
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