Mafusire, CForbes, ASnedden, Glen CMichaelis, MM2007-10-092007-10-092007Mafusire, C et al. 2007. Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor. Proceedings of SPIE, Vol. 6663(6663OH), pp 1-80277-786Xhttp://hdl.handle.net/10204/1291Copyright: 2007 SPIE - The International Society for Optical EngineeringA 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.enSpinning pipe gas lensZernike polynomialsGRIN lensOptical wavefrontArticleMafusire, C., Forbes, A., Snedden, G. C., & Michaelis, M. (2007). Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor. http://hdl.handle.net/10204/1291Mafusire, C, A Forbes, Glen C Snedden, and MM Michaelis "Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor." (2007) http://hdl.handle.net/10204/1291Mafusire C, Forbes A, Snedden GC, Michaelis M. Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor. 2007; http://hdl.handle.net/10204/1291.TY - Article AU - Mafusire, C AU - Forbes, A AU - Snedden, Glen C AU - Michaelis, MM AB - 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. DA - 2007 DB - ResearchSpace DP - CSIR KW - Spinning pipe gas lens KW - Zernike polynomials KW - GRIN lens KW - Optical wavefront LK - https://researchspace.csir.co.za PY - 2007 SM - 0277-786X T1 - Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor TI - Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor UR - http://hdl.handle.net/10204/1291 ER -