2,714 research outputs found
Co-Phased 360-Degree Profilometry of Discontinuous Solids with 2-Projectors and 1-Camera
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
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
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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