The Review of Laser Engineering
Online ISSN : 1349-6603
Print ISSN : 0387-0200
ISSN-L : 0387-0200
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Volume 24, Issue 9
Displaying 1-11 of 11 articles from this issue
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  • [title in Japanese]
    Tomoji KAWAI
    1996 Volume 24 Issue 9 Pages 947
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.947
    JOURNAL FREE ACCESS
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  • Laser Atomic Layer Epitaxy
    Takashi MEGURO, Yoshinobu AOYAGI
    1996 Volume 24 Issue 9 Pages 948-954
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.948
    JOURNAL FREE ACCESS
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    Laser atomic layer epitaxy technique is reviewed, and growth characteristics and surface processes in laser Atomic Layer Epitaxy (ALE) are described. The self-limiting mechanism is the key to attain the ideal layer-by-layer controllability in growth rate. The self-limited growth is obtained in a wide range of several growth parameters. The self-limiting mechanism is induced by the site-selective decomposition of alkylgallium precursors (alkylgallium precursors decompose only at the As surface, but not at the Ga surface), and the direct absorption of laser light in the chemisorbed alkylgallium layer provides the site selectivity.
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  • Atomic Layer Growth Control of Thin Films Using Laser Ablation
    Tomoji KAWAI
    1996 Volume 24 Issue 9 Pages 955-962
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.955
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    Laser ablation has been used for the atomic layer growth control of functional thin films, especially metal oxide thin films. The time of flight analysis of laser ablation of alkaline earth metals has revealed the multi-photon initial processes followed by the energy injection by successive laser light. Utilizing this laser ablation technique, artificial lattices of high Tc superconductors and dielectrics have been formed layer-by-layer which exhibit novel functional properties. It is emphasized that laser molecular beam expitaxy (LMBE) combined with Reflection High Energy Electron Diffraction (RHEED) and Scanning Tunneling Microscopy (STM) is a powerful technique for this purpose.
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  • Dynamical Mechanism of Laser Ablation and Synthesis of Nanoclusters
    Kouichi MURAKAMI, Tetsuya MAKIMURA, Osamu YODA, Atsumi MIYASHITA
    1996 Volume 24 Issue 9 Pages 963-970
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.963
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    We have studied dynamical mechanism of laser ablation using combined time- and spatially-resolved measurements of laser plasma soft x-ray absorption spectroscopy and visible light emission imaging/spectroscopy. The obtained results indicate that there are no significant formation of silicon clustres and no growth of silicon nanoclusters till 2.55 ms after laser ablation. We have fabricated nanocluster-based silicon films by laser ablation in ambient gases and investigated photoluminescence at room temperature from the films. It is found that the growth of silicon nanocluster-based films with visible light emission can be well controlled by means of novel laser ablation methods.
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  • Preparation of Bi-Iron-Garnet Films on Platinized Si Substrate with Bi-Substituted Y-Iron-Garnet Template Layer
    Yasuto YONEZAWA, Kazuko MATSUDA, Akiharu MORIMOTO, Tatsuo SHIMIZU
    1996 Volume 24 Issue 9 Pages 971-976
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.971
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    Bi-iron garnet (BIG) films were prepared using Bi-substituted Y-iron-garnet (Bi:YIG) template layer on platinized Si. First, Bi:YIG template layer was prepared on the platinized (100) Si (Pt/Ti/SiO2/Si) by PLA deposition and successive rapid thermal annealing (RTA). Then Bi3Fe5O12 film was grown on the template layer by PLA. The Bi3Fe5O12 film deposited was found to have a garnet (BIG) phase by x-ray diffraction measurement. For the BIG film, the saturated magnetization and the Faraday rotation were characterized and discussed.
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  • Fabrication of Copper-Phthalocyanine Thin Films by Laser Ablation Deposition
    Naotaka MATSUMOTO, Eigorou INA, Takeo FUJII, Fumihiko KANNARI
    1996 Volume 24 Issue 9 Pages 978-986
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.978
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    Copper-phthalocyanine (CuPc) thin films were successfully fabricated via pulsed laser ablation. In order to maintain a molecule architechture in the deposited films, laser fluence must be kept near the laser ablation threshold. Despite of poor crystallinity exhibited in the films, the CuPc film still maintains its electrical property and works as a hole-transport layer in a double-layer electroluminescence cell emitting -500nm light. The crystallinity of CuPc thin films was improved by heating a substrate at -320K during the deposition or by irradiating the film surface with He-Ne laser at room temperature.
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  • Observation of Evaporated Particles Behaviors and Plasma Parameters in Laser Welding
    Jong-Do KIM, Seiji KATAYAMA, Tadashi TAKEMOTO, Akira MATSUNAWA
    1996 Volume 24 Issue 9 Pages 987-995
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.987
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    This study was undertaken to obtain a fundamental knowledge of pulsed laser welding phenomena, especially evaporation mechanism of different aluminum alloys. The dynamic behavior of Al-Mg alloys plume was very unstable and its fluctuation period was about 450 to 500μs. This instability was closely related to the unstable motion of a keyhole during laser irradiation. It was confirmed that the resonant lines of Al and Mg were strongly self-absorbed, in particular in the vicinity of pool surface. The intensities of molecular spectra of AlO and MgO were different each other depending on the power density of a laser beam. Under the low power density condition, the MgO band spectrum was predominant in intensity, while the AlO spectra became much stronger with an increase in the power density. These behaviors have been attributed to the difference in evaporation phenomena of Al and Mg metals with different boiling points and latent heats of vaporization. The time-averaged plume temperature and electron number density at 1 mm above the surface were determined by spectroscopic methods, and consequently the obtained temperature was 3, 280±150 K and the electron number density was 1.85×1019 1/m3.
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  • Structure and Composition of Evaporated Particles and Plume in Laser Welding
    Jong-Do KIM, Seiji KATAYAMA, Masami MIZUTANI, Tadashi TAKEMOTO, Akira ...
    1996 Volume 24 Issue 9 Pages 996-1005
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.996
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    To obtain fundamental knowledge of pulsed laser welding phenomena, especially evaporation mechanism of different aluminum alloys, the authors investigated the structure and composition of evaporated particles of Al-Mg alloys in air and in the Ar atmosphere during pulsed laser welding. It was found that ultra-fine particles of 5 to 100 nm diameter in a globular or irregular shape were formed in laser-induced plume and the main structure was MgAl2O4. The composition of particles was different depending on the power density of a laser beam ; namely, under the low power density irradiation conditions, magnesium was predominant in the particles, while aluminum content increased with an increase in the power density. These results were attributed to evaporation phenomena of metals with different boiling points and latent heats of vaporization. On the other hand, under the assumption that the mixed gas of different atoms and the ionized species was an ideal one, the number density of laser-induced plasma species was obtained by Saha's equation. It was confirmed that the number density depends upon the plasma temperature and total pressures.
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  • Intracavity Second Harmonic Generation of Chemical Oxygen Iodine Laser Using Brewster Cut LBO Crystal
    Takeo TEZUKA, Kuntetsu CHEN, Katsuki HASHIMOTO, Taro UCHIYAMA
    1996 Volume 24 Issue 9 Pages 1006-1012
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.1006
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    The second harmonic generation(SHG) of continuous wave chemical oxygen iodine laser(COIL) has been studied. Second harmonic of COIL has characteristics of the short wavelength of 0.658μm and the visible laser. So our purpose is to apply this study to industrial process. The two types of LBO crystal were used as the nonlinear crystal. One was a cubic LBO crystal whose surface were AR coated and the other was Brewster cut LBO crystal which was not used AR coating and cut for Brewster angle. We used two types of concentric asymmetric resonator whose length were different each other. The second harmonic maximum output of 16.4W were obtained using the Brewster cut LBO crystal and the conversion efficiency was 0.51% just then. So we achieved higher power second harmonic by using Brewster cut LBO crystal.
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  • Detection of Clearance in Laser Lap Joint Welding
    Isamu MIYAMOTO, Kiyokazu MORI
    1996 Volume 24 Issue 9 Pages 1013-1018
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.1013
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    An in-process monitoring system has been developed for detecting the clearance between two steel sheets in CO2 laser welding lap joint of automotive body where photo sensors are used to separate the light emission of the keyhole plasma, PK, from that of the plasma plume, PP. The acquired signal involved AC components with frequencies up to approximately 10kHz of the light emission of the laser-induced plasma. Peak frequency of plasma emission induced in full penetration welding was found to decrease with increasing thickness of the workpiece. The mean square value of the AC component at a 4 - 6 kHz band was found to increase sharply at clearances larger than 0.3mm where the mechanical strength of the lap joint begun to decrease. The time-change in the light emission was found to be caused by the resonant oscillations of the keyhole surrounded by liquid wall.
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  • Report on Eleventh International Conference on Optical Fiber Sensors (OFS-11) -Advanced Sensing Photonics-
    Ilko K. ILEV
    1996 Volume 24 Issue 9 Pages 1019-1024
    Published: September 25, 1996
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.24.1019
    JOURNAL FREE ACCESS
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