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Proceedings Paper

Characterisation of a spinning pipe gas lens using a Shack-Hartmann wavefront sensor
Author(s): Cosmas Mafusire; Andrew Forbes; Glen Snedden; Max M. Michaelis
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Paper Abstract

A heated horizontal spinning pipe causes gases inside it to assume dynamics resulting in a graded index lens - a spinning pipe gas lens (SPGL). A CFD model is presented which shows that gas exchanges of the SPGL with the surroundings resulting in a near parabolic density distribution inside the pipe created by the combination of velocity and thermal boundary layers. Fluid dynamic instabilities near the wall of the pipe are thought to have an deleterious effect on the quality of the beam and its wavefront. Measurements of the wavefront of a propagating laser beam shows strong defocus and tilt as well as higher order aberrations, thereby reducing the beam quality factor (M2) of the output beam. Results are presented as a function of pipe wall temperature and pipe rotation speed.

Paper Details

Date Published: 26 September 2007
PDF: 8 pages
Proc. SPIE 6663, Laser Beam Shaping VIII, 66630H (26 September 2007); doi: 10.1117/12.734110
Show Author Affiliations
Cosmas Mafusire, CSIR National Laser Ctr. (South Africa)
Univ. of Kwazulu-Natal (South Africa)
Andrew Forbes, CSIR National Laser Ctr. (South Africa)
Univ. of Kwazulu-Natal (South Africa)
Glen Snedden, CSIR Defence Peace Safety and Security (South Africa)
Max M. Michaelis, Univ. of Kwazulu-Natal (South Africa)

Published in SPIE Proceedings Vol. 6663:
Laser Beam Shaping VIII
Fred M. Dickey; David L. Shealy, Editor(s)

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