• JLA Vol:21 Iss:3 (Multibeam fiber laser cutting)


    Authors:
    Flemming Ove Olsen
    Klaus Schuett Hansen
    Jakob Skov Nielsen
    Department of Mechanical Engineering, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark


    The appearance of the high power high brilliance fiber laser has opened for new possibilities in laser materials processing. In laser cutting this laser has demonstrated high cutting performance compared to the dominating cutting laser, the CO2 laser. However, quality problems in fiber-laser cutting have until now limited its application to metal cutting. In this paper the first results of proof-of-principle studies applying a new approach (patent pending) for laser cutting with h...

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  • JLA Vol:24 Iss:3 (2D longitudinal modeling of heat transfer and fluid flow during multilayered direct laser metal deposition process)


    Authors:
    Simon Morville
    Muriel Carin
    LIMATB, Universite´ de Bretagne-Sud/UEB, Centre de recherche Ch. Huygens, Rue de Saint Maude´, BP 92116, 56321 Lorient cedex, France

    Patrice Peyre
    Myriam Gharbi
    PIMM, UMR 8006 CNRS-Arts et Me´tiers Paris Tech, 151 Boulevard de l’Hoˆpital, 75013 Paris, France

    Denis Carron
    Philippe Le Masson
    LIMATB, Universite´ de Bretagne-Sud/UEB, Centre de recherche Ch. Huygens, Rue de Saint Maude´, BP 92116, 56321 Lorient cedex, France

    Re´my Fabbro
    PIMM, UMR 8006 CNRS-Arts et Me´tiers Paris Tech, 151 Boulevard de l’Ho&ci...

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  • JLA Vol:6 Iss:4 (Holographic optical elements (HOEs): A serious application of holography)


    Authors:
    Gareth T. Williams
    Jeff Fredrick
    Physics Department, San Jose State University, San Jose, CA, U.S.A.


    Without disputing the excitement and sense of accomplishment associated with the production of display holograms, this paper suggests equal rewards from the production of holographic optical elements (HOEs). The elements described here are zone plates, diffraction gratings, interference filters and mirrors, and lenses. Ways of making each of these in an optics teaching laboratory are described, but the main emphasis will be on positive lens HOE.

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  • JLA Vol:15 Iss:3 (Steady-state laser cutting modeling)


    Authors:
    Ce´dric Mas
    Re´my Fabbro
    CLFA, 16 bis Avenue Prieur de la Côte d’Or, 94114 Arcueil Cedex, France

    Yannick Goue´dard
    OPTIS, ZE la Farlède, BP 275, 83078 Toulon Cedex 9, France


    We present a global self-consistent model of the laser cutting process where we have taken into account the main parameters of the process that are the laser beam intensity distribution, the thermal phenomena controlling the melt parameters, the fluid, both cutting gas and melt hydrodynamics, and the local equilibrium of the geometry of the cutting front. This steady state approach provides us with different fluid velocities, surface ...

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  • JLA Vol:19 Iss:3 (Single-Pass and Multi-Pass Laser Cutting of Si–SiC: Assessment of the Cut Quality and Microstructure in the Heat Affected Zone)


    Authors:
    F. Quintero
    J. Pou
    F. Lusquin˜os
    A. Riveiro
    M. Pe´rez-Amor
    Departamento Fi´sica Aplicada, E.T.S. Ingenieros Industriales, University de Vigo, 36310 Vigo, Spain

    A. J. S. Fernandes
    Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal


    Experimental investigations on the laser cutting of thick silicon infiltrated silicon carbide (Si–SiC) elements are presented. Si–SiC is a fully dense ceramic composite with high hardness and chemical and thermal stability, which makes it a valuable material in severe conditions. However, machining is still a challenging task. A...

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  • JLA Vol:7 Iss:1 (Development of laser finishing for non‐circular profiles)


    Authors:
    Ko‐Wang Liu
    Paul S. Sheng
    Department of Mechanical Engineering, University of California, Berkeley, CA 94720‐1740, U.S.A.


    A laser‐based technique for finishing of non‐circular cylindrical parts is presented. In this process, the frequency characteristics of a desired non‐circular shape is extracted from a CAD through a Fast Fourier Transform algorithm and implemented through a CO2 laser machining system. A galvanometer‐based scanner is used in the process to achieve programmable beam trajectories and high‐speed finishing. An error estimation scheme can be developed to determine the final dimensional erro...

    $25.00

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  • JLA Vol:18 Iss:1 (Three-dimensional analytical model on laser-powder interaction during laser cladding)


    Authors:
    Yan-Lu Huang
    Jian Liu
    Nai-Heng Ma
    Jian-Guo Li
    School of Materials Science and Engineering, Shanghai Jiaotong University, Shanghai, China 200030


    To compute the attenuation of laser power by powder stream and the temperature distribution of the powder particles arriving at different sites on the surface of the workpiece, a three-dimensional analytical model was presented based on Lambert-Beer theorem, Mie’s theory, and heat equilibrium principle. The obtained results revealed that for a given stream spread and speed of powder particles, the laser intensity distribution of laser spot and the temperature distribution of the powder part...

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  • JLA Vol:9 Iss:3 (Experimental study of cutting thick aluminum and steel with a chemical oxygen&ndash;iodine laser using an N<sub>2</sub> or O<sub>2</sub> gas assist)


    Authors:
    David L. Carroll
    James A. Rothenflue



    A chemical oxygen–iodine laser (COIL) was used to cut aluminum and carbon steel. Cut depths of 20 mm in aluminum and 41 mm in carbon steel were obtained using an N2 gas assist and 5–6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel with an O2 gas assist; a low quality cut to a depth of nearly 100 mm in carbon steel was also demonstrated. These data are compared with existing COIL and CO2 laser cutting data. COIL cuts carbon steel and stainless steel at approximately the same rate. For a given cut depth, power and spot size...

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  • JLA Vol:4 Iss:2 (Dynamic Laser Doppler Velocimetry on Solid Surfaces)


    Authors:
    Milind M. Rajadhyaksha
    Warren H. Stevenson
    Applied Optics Laboratory, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, U.S.A.


    This paper presents the results of a detailed analytical and experimental investigation into the accuracy of a differential laser Doppler velocimeter (LDV) for dynamic, solid surface velocity measurements made over very short averaging times on the order of one millisecond. Accuracy limitations are derived, along with operating conditions and signal processing considerations needed to optimize LDV performance. An experiment is described which demonstrates the use of an LDV to instantaneously and accurate...

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