The Review of Laser Engineering
Online ISSN : 1349-6603
Print ISSN : 0387-0200
ISSN-L : 0387-0200
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Volume 25, Issue 4
Displaying 1-12 of 12 articles from this issue
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  • [title in Japanese]
    Kunioki MIMA
    1997 Volume 25 Issue 4 Pages 265
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.265
    JOURNAL FREE ACCESS
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  • New Idea of Laser Material Processing
    Koichi TOYODA
    1997 Volume 25 Issue 4 Pages 266
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.266
    JOURNAL FREE ACCESS
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  • Fundamental Mechanisms of Laser Desorption and Plume Formation from Ionic Crystals
    J. Thomas DICKINSON, David R. ERMER, Jaw-Jung SHIN, Stephen C. LANGFOR ...
    1997 Volume 25 Issue 4 Pages 267-277
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.267
    JOURNAL FREE ACCESS
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    In applications of high intensity lasers to materials processing, the formation of an ablation plume is of high importance. For wide bandgap insulators (e.g., oxides, halides, nitrides, carbides) irradiated with sub bandgap photon energies, the route to plume formation is not well understood. For example, contrary to metals and semiconductors, inverse bremsstrahlung (IB) is not possible for a wide range of laser intensities on these materials due to insufficient photon and electron densities. We present an alternative path to plume formation on nominally transparent materials. We first examine the interaction of photo-and thermally-emitted particles from exposure to pulsed laser irradiation of surfaces which include photoelectrons, energetic positive ions, and neutral metal atoms. We establish experimentally that there is overlap in space and time of significant portions of the distributions of these particles in the near surface region. We present a model for the collective motion of these particles and show that as laser fluence is increased we achieve sufficient densities, overlap, and kinetic energies to result in the onset of plume fluorescence and eventually ionization at fluences far below any IB or catastrophic breakdown process.
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  • Progress in Oxide Materials Research by Laser Molecular Beam Epitaxy
    Hideomi KOINUMA, Tsuyoshi OHNISHI, Naoki KANDA
    1997 Volume 25 Issue 4 Pages 278-282
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.278
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    The advantages of pulsed laser deposition for oxide film growth and of molecular beam epitaxy for 2-dimensional film growth have been combined to develop a method for atomically controlled epitaxy of oxide thin films and heterojunctions. Molecular layer epitaxy has been verified by the clear observation of RHEED intensity oscillations for the growths of various oxides with perovskite, infinite-layer, rock salt, corundum, and fluorite structures. Epitaxial growth of BaO and sapphire films was achieved even at such a low temperature as 20°C. New structures with exotic properties were revealed in SrTiO3/SrVO3 superlattice, infinite-layer cuprates, and ZnO hexagonal platelets film. In view of the versatility and structure-sensitive properties of oxides, this lattice engineering technology by laser MBE is expected to open a new field of oxide electronics.
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  • Ablation Using Vacuum-Ultraviolet Lasers
    Koji SUGIOKA, Satoshi WADA, Hideo TASHIRO, Koichi TOYODA
    1997 Volume 25 Issue 4 Pages 283-287
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.283
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    Material ablation using vacuum-ultraviolet (VUV) lasers is reviewed. High photon energy of VUV beam accomplishs clean ablation of transparent materials in the UV region such as polytetrafluoroethylene (PTFE) and fused silica with little thermal effect. A novel ablation scheme using multiwavelength excitation by coupling of VUV and UV laser beams is also presented. In this process, the VUV beams have two important roles, that is, photodecomposition of constituent atoms (stationary effect) and formation of excited state (transitional effect), although their energy is too small to ablate materials by themselves. The multiwavelength ablation provides great potential for high-quality microfabrication of wide band-gap materials such as fused silica, crystal quartz, sapphire, lithium niobate and SiC.
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  • Development and Application of Nanosecond Interferometry for the Clarification of Laser Ablation Dynamics
    Hiroshi FURUTANI, Hiroshi FUKUMURA, Hiroshi MASUHARA
    1997 Volume 25 Issue 4 Pages 288-295
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.288
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    A nanosecond interferometric technique and its applications for the clarification of laser ablation dynamics are reviewed, and the morphological dynamics of the irradiated polymer films during or just after the excitation laser pulse is described. Since the nanosecond interferometric technique is based on the Michelson interferometer combined with a Q-switched Nd3+:YAG laser, expansion and contraction of the irradiated films about 20-30nm can be resolved with a time resolution of -10 ns. It is clarified that morphological dynamics of polymer films with different chemical and physical properties show a different morphological behavior depending on their chemical and physical properties upon laser ablation. On the basis of the revealed expansion and etching dynamics, ablation mechanism is discussed.
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  • Laser Ablation of Graphite in the Presence of a Magnetic Field
    Fumio KOKAI, Kimitsugu SAITO, Kazuhiro YAMAMOTO, Takako NAKAMURA, Yosh ...
    1997 Volume 25 Issue 4 Pages 296-300
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.296
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    Optical emission spectroscopic studies were carried out on ablation plumes produced by laser ablation of graphite at 266nm and 1064nm in vacuum and in nitrogen gas atmosphere with or without a magnetic field of -0.1 T. In vacuum, in the presence of the magnetic field, the intensity distribution of C, C+, and C2+ emission lines were varied remarkably and some of the emission lines originated from relatively higher excited states became obscure. In addition, C2 Swan band emission appeared particularly during 1064nm laser ablation. These changes in emission spectra are interpreted by promotion of ionization of C and C+, formation of C2, and deexcitation of electronically excited states, resulting from enhanced collisions between ablated species due to cyclotron motions under the magnetic field. In nitrogen gas atmosphere, enhanced N2 emission (2nd positive system) was observed and explained by electron-impact excitation of N2 molecules.
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  • Fabrication of Micro-Magnetic Device by Excimer Laser Ablation
    Tsutomu TAKAHASHI, Koji SUGIOKA, Koichi TOYODA
    1997 Volume 25 Issue 4 Pages 301-305
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.301
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    A micro-magnetic divice consisting of patterned Sr-ferrite by excimer laser ablation is described. By using a projection-patterned etching, the etched pattern of 80μm in depth is achieved in focused laser irradiation (600mJ/cm2, 10Hz, 45 minutes) in air. The magnetic properties for aspect ratio and profile of laser etched grooves are calculated by a three dimensional magnetic field analysis. Furthermore, the magnetic flux density onto the Sr-ferrite substrate is also measured by magneto-optical sensor.
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  • Laser Ablation Dynamics of Amorphous Film of a Cu-Phthalocyanine Derivative
    Masahiro HOSODA, Hiroshi FURUTANI, Hiroshi FUKUMURA, Hiroshi MASUHARA, ...
    1997 Volume 25 Issue 4 Pages 306-311
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.306
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    Laser ablation dynamics of amorphous film of a Cu-phthalocyanine derivative was studied by using nanosecond interferometry, nanosecond photography, space- and time-resolved absorption spectroscopy, and atomic force microscope (AFM). At 140mJ/cm2, etching of the film was found to begin at the early half of an excimer laser pulse followed by the ejection of gaseous compounds. Since the absorption spectrum of ejected materials was similar to that of the amorphous film, main molecular specie of the ejected materials is the Cu-phthalocyanine derivative, meaning no decomposition even upon laser ablation. It is suggested that photothermal mechanism is responsible for the ablation. It was observed with AFM that surface structure of the PMMA film adhered with ejected materials was covered with humps whose minimum dimension was about 120nm. It is suggested that Cu-phthalocyanine derivative was ejected not as single molecules but as submicron particles upon laser ablation.
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  • Stereolithography in Resin by Using Laser-Irradiation through a Bubble
    Yoji MARUTANI, Takayuki KAMITANI
    1997 Volume 25 Issue 4 Pages 312-315
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.312
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    In conventional stereolithography methods, the solidified photopolymer layers are stacked one by one in resin. As a result, these methods have such disadvantages as time consumption to recoat new resin layer and to remove the surface roughness caused by steps on the models. This paper proposes a new method of fabricating 3-D models in a resin. An air bubble is formed at the end of a pipe under the surface of the resin. A laser beam is introduced through the bubble so as to solidify the resin on the bubble surface. As the solidified parts have no mechanical interference with the pipe, it is free to move the exposing point in the 3-dimensional space. The resolution and sensitibity of the method were measured, and some objects were fabricated. Through these experiments, the possibility of making 3-D models without processes of lamination and recoating was demonstrated.
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  • He-Ne Laser Propagation in Silica Fiber after Delivery of KrF Excimer Laser
    Kazuyuki OKADA, Hiroshi TSUBAKIHARA, Akihiko SAKAMOTO, Masahiro NAKATS ...
    1997 Volume 25 Issue 4 Pages 316-319
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.316
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    He-Ne laser propagation in silica fiber after delivery of KrF excimer laser was experimentally investigated. The intensity at the outer part of deliveried He-Ne laser beam after delivery of KrF excimer laser was observed to be extremely reduced in comparison with that before delivery of KrF laser. We consider that this reduction results from the absorption of skew rays and/or the refractive index change at the outer part of core silica. It is supposed that these changes of optical property originate from the KrF-laser-induced defects located at the outer part of core layer.
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  • Particle and Wave Nature of Light I
    What is Light
    Koichi SHIMODA
    1997 Volume 25 Issue 4 Pages 320-323
    Published: April 15, 1997
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.25.320
    JOURNAL FREE ACCESS
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