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Proceedings Paper

A computational fluid dynamics model of the spinning pipe gas lens
Author(s): C. Mafusire; A. Forbes; G. Snedden
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Paper Abstract

When a metal horizontal pipe is heated and spun along its axis, a graded refractive index distribution is generated which is can be used as a lens, thus its name, the spinning pipe gas lens (SPGL). Experimental results showed that though increase in rotation speed and/or temperature resulted in a stronger lens and removed distortions due to gravity, it also increased the size of higher order aberrations resulting in an increase in the beam quality factor (M2). A computational fluid dynamics (CFD) model was prepared to simulate the aerodynamics that show how it operates and, in the process shed some light on the optical results. The results of the model consist of velocity profiles and the resultant density data and profiles. At rest the cross-sectional density profile has a vertical symmetry due to gravity but becomes rotationally symmetric with a higher value of density at the core as rotation speed increases. The longitudinal density distribution is shown to be parabolic towards the ends but is fairly uniform at the centre. The velocity profiles show that this centre is the possible source of higher order aberrations which are responsible for the deterioration of beam quality.

Paper Details

Date Published: 16 August 2010
PDF: 9 pages
Proc. SPIE 7789, Laser Beam Shaping XI, 77890Y (16 August 2010); doi: 10.1117/12.862857
Show Author Affiliations
C. Mafusire, Council for Scientific and Industrial Research (South Africa)
Univ. of KwaZulu-Natal (South Africa)
A. Forbes, Council for Scientific and Industrial Research (South Africa)
Univ. of KwaZulu-Natal (South Africa)
Stellenbosch Univ. (South Africa)
G. Snedden, Council for Scientific and Industrial Research (South Africa)


Published in SPIE Proceedings Vol. 7789:
Laser Beam Shaping XI
Andrew Forbes; Todd E. Lizotte, Editor(s)

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