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Browsing by Author "Forbes, A"

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  • Schulze, C; Ngcobo, S; Duparre, M; Forbes, A (Optical Society of America, 2012-12)
    The modal decomposition of an arbitrary optical field may be done without regard to the spatial scale of the chosen basis functions, but this generally leads to a large number of modes in the expansion. While this may be ...
  • Flamm, D; Naidoo, Darryl; Schulze, C; Forbes, A; Duparré, M (Optical Society of America, 2012-07)
    A procedure for the real-time analysis of laser modes using a phase-only spatial light modulator is outlined. The procedure involves encoding into digital holograms by complex amplitude modulation a set of orthonormal basis ...
  • Burger, L; Forbes, A (International Society for Optical Engineering (SPIE), 2007)
    A simple model of a Porro prism laser resonator has been found to correctly predict the formation of the “petal” mode patterns typical of these resonators. A geometrical analysis of the petals suggests that these petals ...
  • Forbes, A; Burger, L; Litvin, IA (2006-07)
    Laser brightness is a parameter often used to compare high power laser beam delivery from various sources, and incorporates both the power contained in the particular mode, as well as the propagation of that mode through ...
  • Loveday, PW; Long, CS; Forbes, A; Land, K (South African Conference on Computational and Applied Mechanics, 2008-03)
    An intra-cavity adaptive mirror is required to compensate for time-dependent phase aberrations to the laser beam, such as those caused by thermal lensing. A piezoelectric unimorph design can provide a small, low-cost ...
  • Michaelis, MM; Forbes, A; Conti, A; Nativel, N; Bencherif, H; Bingham, R; Kellett, B; Govender, K (The International Society for Optical Engineering, 2006-06-14)
    Non-solid and non-rigid optics employ gas and liquid transmission and reflection, as well as flexible membranes to influence laser beams, laser driven particle beams and harmonic generators. Some examples are acoustic ...
  • Long, CS; Loveday, PW; Forbes, A; Land, K (SACAM 2010, 2010-01)
    For intra-cavity laser beam control, a small, low-cost deformable mirror is required. This mirror can be used to correct for time- dependent phase aberrations to the laser beam, such as those caused by thermal expansion ...
  • Naidoo, Darryl; Ait-Ameur, K; Litvin, I; Fromager, M; Forbes, A (Deutsche Physikalische Gesellschaft, 2012-05)
    The mode inside a laser cavity may be understood as the interference of two counter-propagating waves, referred to as the forward and backward waves, respectively. We outline a simple experimental procedure, which does not ...
  • Mafusire, C; Forbes, A; Michaelis, MM; Snedden, Glen C (2010-08)
    Gas lenses work on the basis that aerodynamic media can be used to generate a graded refractive index distribution which can be used to focus a laser beam. Examples of these are the spinning pipe gas lens (SPGL) and the ...
  • Mafusire, C; Forbes, A; Michaelis, MM; Snedden, Glen C (Optical Society of America, 2008-06)
    If a heated pipe is rotated about its axis, a density gradient is formed which results in the pipe acting as a graded index lens. In this study the authors revisit the concept of a spinning pipe gas lens and for the first ...
  • Trichili, A; Rosales-Guzmán, C; Dudley, Angela; Ndagano, B; Salem, AB; Zghal, M; Forbes, A (Macmillan Publishers Limited, part of Springer Nature, 2016-06)
    Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase ...
  • Nkosi, SS; Kortidis, I; Motaung, DE; Keartland, J; Sideras-Haddad, E; Forbes, A; Mwakikunga, BW; Kiriakidis, G; Sinha-Ray, S (Elsevier, 2013-09)
    Diluted magnetic semiconductor (DMS) Mn:ZnO thin films with “ring-like or doughnut-like” structures were grown using aerosol spray pyrolysis for 20 and 30 min. Electron paramagnetic resonance revealed the ferromagnetic ...
  • Masina, BN; Forbes, A; DeGama, MP (South African Institute of Physics (SAIP), 2009-07)
    In principle all objects emit thermal radiation as a consequence of their temperature. The thermal radiation emitted by an object depends on its temperature, surface condition and thermal properties. A thermography camera ...
  • Roro, Kittessa T; Tile, N; Forbes, A (2010-12)
    Nanocomposite thin films are widely used for solar thermal applications. Using carbon nanoparticle containing metal oxide as a spectrally selective solar absorber coating has grown significantly in recent years. Recently, ...
  • Masina, B; Forbes, A (SAIP 2010, 2010-09)
    This presentation acknowledges that temperature induces damage in the diamond bits due to friction during the drilling process. The temperature of the diamond sample can be raised by laser heating it.
  • Ismail, Y; Mclaren, MG; Forbes, A (2009-07)
    This presentation provides information on optical trapping and tweezing using a spatial light modulator.
  • McLaren, M; Khanyile, T; Mthunzi, P; Forbes, A (Optical Society of America, 2013-04)
    We outline the possibility of optical trapping and tweezing with Super-Gaussian beam profiles. We show that the trapping strength can be tuned continuously by adjusting the order of a Super-Gaussian beam, approaching that ...
  • Mafusire, C; Forbes, A (South African Institute of Physics (SAIP), 2009-07)
    The researchers have managed to do quantitative analysis of ‘controlled’ turbulence. The researchers could control the degree of turbulence by controlling the rotation speed and wall temperature of the spinning pipe gas ...
  • Tile, N; Roro, Kittessa T; Forbes, A (2011-05)
    The demand for low cost, efficient and environmental friendly energy is increasing rapidly. Solar thermal energy is being widely investigated as a solution. Efficient thermal solar collectors require a spectrally selective ...
  • Masina, BN; Lafane, S; Wu, Lorinda; Abdelli-Messaci, S; Kerdja, T; Forbes, A (SPIE Proceedings, 2014-02)
    Fast imaging plasma plume study have been carried out on vanadium-oxygen plasma generated using 248 nm, 25 ns pulses from an excimer KrF laser under oxygen atmosphere. The plume expansion dynamics of an ablated VO(sub2) ...