2,693 research outputs found

    Co-Phased 360-Degree Profilometry of Discontinuous Solids with 2-Projectors and 1-Camera

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    Here we describe a co-phased 360-degree fringe-projection profilometer which uses 2-projectors and 1-camera and can digitize discontinuous solids with diffuse light surface. This is called co-phased because the two phase demodulated analytic-signals from each projection are added coherently. This 360-degree co-phased profilometer solves the self-generated shadows cast by the object discontinuities due to the angle between the camera and the single white-light fringe projector in standard profilometry.Comment: 4 pages, 6 Figure

    Propagation of electromagnetically generated wake fields in inhomogeneous magnetized plasmas

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    Generation of wake fields by a short electromagnetic pulse in a plasma with an inhomogeneous background magnetic field and density profile is considered, and a wave equation is derived. Transmission and reflection coefficients are calculated in a medium with sharp discontinuities. Particular attention is focused on examples where the longitudinal part of the electromagnetic field is amplified for the transmitted wave. Furthermore, it is noted that the wake field can propagate out of the plasma and thereby provide information about the electron density profile. A method for reconstructing the background density profile from a measured wake field spectrum is proposed and a numerical example is given.Comment: 12 pages in LaTeX style, 11 eps figure

    Fast algorithm for estimation of the orientation term of a general quadrature transform with application to demodulation of an n-dimensional fringe pattern

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    The spatial orientation of fringes has been demonstrated to be a key point in reliable phase demodulation from a single n-dimensional fringe pattern, regardless of the frequency spectrum of the signal. Recent publications have shown a general method for determination of the orientation factor by use of a regularized phase-tracking (RPT) algorithm. We propose a generalization of a RPT algorithm for estimation of the spatial orientation in a general n-dimensional case. The proposed algorithm makes use of a simplified cost function that remains one dimensional regardless of the dimension of the problem. This makes the calculation faster than with a standard RPT algorithm, with which it is necessary to minimize an n + 1-dimensional cost function for each point of the sample space. We have applied the method to the three-dimensional demodulation of a time-evolving fringe pattern, with good results
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