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Browsing by Author "Forbes, A"

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  • 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) ...
  • Mwakikunga, BW; Forbes, A; Sideras-Haddad, E; Arendse, C (Springer Verlag, 2008-10)
    Laser pyrolysis has been used to synthesize WO3 nanostructures. Spherical nano-particles were obtained when acetylene was used to carry the precursor droplet, whereas thin films were obtained at high flow-rates of oxygen ...
  • Romero, J; Giovannini, D; McLaren, MG; Galvez, EJ; Forbes, A; Padgett, MJ (European Optical Society, 2012-08)
    We report orbital angular momentum (OAM) and angle correlations between signal and idler photons observed when the nonlinear crystal used in spontaneous parametric down-conversion is illuminated by a non-fundamental Gaussian ...
  • Hamadou Ibrahim, A; Roux, FS; McLaren, M; Konrad, T; Forbes, A (American Physical Society, 2013-06)
    The turbulence-induced decay of orbital-angular-momentum (OAM) entanglement between two photons is investigated numerically and experimentally. To compare our resultswith previouswork,we simulate the turbulent atmosphere ...
  • Nkosi, SS; Kortidis, I; Motaung, DE; Malgas, GF; Keartland, J; Sideras-Haddad, E; Forbes, A; Mwakikunga, BW; Sinha-Ray, S; Kiriakidis, G (Elsevier, 2013-12)
    High quality un-doped and Mn-doped ZnO films deposited by a simple aerosol spray pyrolysis technique for 20 and 30 min were studied using electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and atomic force ...
  • Bruning, R; Zhang, Y; McLaren, M; Duparre, M; Forbes, A (2015-09)
    We investigated the overlap relation of the free-space Laguerre–Gaussian modes to the corresponding linearly polarized modes of a step-index fiber. To maximize the overlap for an efficient coupling of the free-space modes ...
  • Forbes, A; Du Preez, NC; Belyi, VN; Botha, LR (Society of Photo-Optical Instrumentation Engineers, 2009-08)
    In this paper the researchers present results on improved paint stripping performance with an intra-cavity generated Flattened Gaussian Beam (FGB). A resonator with suitable diffractive optical elements was designed in ...
  • Litvin, IA; Burger, L; Forbes, A (Optical Society of America, 2007-10)
    A new approach to modeling the spatial intensity profile from Porro prism resonators is proposed based on rotating loss screens to mimic the apex losses of the prisms. A numerical model based on this approach is presented ...