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Characterization of photoinduced gratings in optical glass fibers.Kuo, Chai-Pei. January 1988 (has links)
The properties of photo-induced gratings in germania doped glass fibers were studied. Permanent phase gratings in a fiber core were fabricated by the mixing of two contra propagating waves. Experiments are described and results are presented which show that the strength of a photoinduced grating is strongly dependent on the writing power as well as the laser writing wavelength. A rigorous development of linear coupled mode theory for the contra propagation geometry is given and used to model the experimentally observed grating responses as a function of fine tuning frequency of probing light. Measurements have been done of the amplitude and phase response of the grating structure and compared with theoretical models of uniform and chirped gratings. The theoretically predicted negative group velocity dispersion in fiber grating was observed interferometrically and described in detail. The nonlinear coupled mode theory has been fully implemented in a computer program and some numerical results are given in the second part of this thesis. The dynamics of a pulse propagating in the fiber grating is simulated and the results show its dependence on pulse energy, frequency detuning, and the type of grating geometry. A limitation is found in the dispersion property of a constant amplitude fiber grating so that the pulse compression ratio and the width of a compressible pulse is strictly limited to ≅250 picoseconds.
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TRADITIONAL AND SYNCHRONOUS CONVOLUTION METHODS FOR PROCESSING FRINGE PATTERN IMAGES.WOMACK, KENNETH HOWARD. January 1982 (has links)
The problem of recovering a wavefront or surface deviation from a fringe pattern image is investigated. The data sets generated in sampling a fringe pattern are considered in the frequency domain and errors that arise in analyzing the pattern are given an aliasing interpretation. Uniform sampling is shown to be superior to other sampling schemes. A variety of techniques for locating fringe centers are reviewed and three synchronous convolution methods are demonstrated that do not require the location of fringe centers. For the latter, direct phase measurements are obtained from fringe pattern photographs over a uniform grid with an accuracy comparable to temporal heterodyne interferometry. Two microprocessor-based video systems are described in which the traditional and synchronous convolution methods were implemented.
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High pressure behaviour of pyroxenesHugh-Jones, Demelza Alice January 1995 (has links)
No description available.
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Analytical transmission electron microscopy of authigenic chloritesWhittle, Caroline Kay January 1985 (has links)
No description available.
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Image quality of optical systems when used with focal plane array detectorsWood, Sean James January 1993 (has links)
No description available.
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Ultrastructure of the A-band unit cell in relaxed muscleHudson, Liam January 1996 (has links)
No description available.
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A study of near-field optical imaging using an infrared microscopeQuartel, John Conrad January 1999 (has links)
No description available.
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Crystallographic studies of complexes of transition and post-transition metalsFraser, Kelly A. January 1994 (has links)
No description available.
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Structural studies of lithium compoundsHodgson, Susan Marie January 1989 (has links)
No description available.
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Study of two-phase annular flow in inclined pipesAltunbas, Ayse January 1999 (has links)
No description available.
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