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Browsing by Author "Forbes, A"

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  • Katumba, G; Baisitse, T; Forbes, A; Olumekor, L; Wackelgard, E (2006-07)
    The Bruggeman and Maxwell-Garnett effective medium approximations (EMAs) have been used to investigate optical properties of composite materials. The EMA assumptions are based on random unit cell models in which metal ...
  • Katumba, G; Forbes, A (Society of Photo-optical Instrumentation Engineers (SPIE), 2009-08)
    The Bruggeman and Maxwell-Garnett effective medium approximations have been used widely to investigate optical properties of many different composite materials. In most cases, the effective medium approximation assumptions ...
  • Tile, N; Roro, Kittessa T; Forbes, A (2011-07)
    Nanocomposite materials have wide range of applications in solar energy conversion. In this work, C-NiO nanocomposite coatings are prepared using sol-gel synthesis and deposited on aluminium substrates using a spin coater. ...
  • Snedden, Glen C; Forbes, A; Mahlatse, ACK; Mafusire, C; Michaelis, MM (2006-07)
    Slides on: Spinning Pipe Gas Lens; Focal Length; Refractive Index; Gas Dynamics; Guess at the gas dynamics; Density Profile; Flow Profile; Rosby Waves; Rayleigh–Taylor Instabilities
  • Mafusire, C; Forbes, A; Snedden, Glen C; Michaelis, MM (International Society for Optical Engineering (SPIE), 2007)
    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 ...
  • Baisitse, TR; Forbes, A; Katumba, G; Botha, JR; Engelbrecht, JAA (John Wiley & Sons Ltd, 2008)
    In this paper, infrared reflectance spectroscopy was employed to extract information on the optical and electrical properties of metal organic vapour phase epitaxial (MOVPE) grown InAs and InAsSb epilayers. These epitaxial ...
  • Dudley, Angela L; Naidoo, Darryl; Forbes, A (SPIE, 2016-09)
    We show how one can determine the various properties of light, from the modal content of laser beams to decoding the information stored in optical fields carrying orbital angular momentum, by performing a modal decomposition. ...
  • Giovannini, D; Romero, J; Leach, J; Dudley, Angela L; Forbes, A; Padgett, MJ (American Physical Society, 2013-04)
    Mutually unbiased bases (MUBs) play a key role in many protocols in quantum science, such as quantum key distribution. However, defining MUBs for arbitrary high-dimensional systems is theoretically difficult, and measurements ...
  • Forbes, A; Du Plessis, A; Rohwer, EG (The International Society for Optical Engineering, 2005-08)
    Infra-red laser beam shaping has the inherent difficulty that simple ray tracing methods often yield anomalous results, due primarily to the propagation effects at longer wavelengths. Techniques based on diffraction theory ...
  • Dudley, Angela L; Litvin, I; Roux, FS; Forbes, A (SPIE Digital library, 2013-02)
    By using digital holograms, we present a simple technique for performing a complete azimuthal decomposition of an arbitrary laser mode. The match-filter, used to perform the azimuthal decomposition, is bounded by an annular ...
  • Mafusire, C; Forbes, A; Snedden, Glen C (2010-08)
    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). Previous experimental ...
  • Naidoo, Darryl; Forbes, A; Aït-Ameur, K; Brunel, M (SPIE, 2011-01)
    An experimental approach in generating Petal-like transverse modes, which are similar to what is seen in porro-prism resonators, has been successfully demonstrated. We hypothesize that the petal-like structures are generated ...
  • Dudley, Angela L; Schulze, C; Roux, FS; Duparré, M; Forbes, A (2013-06)
    In this work we present a mechanism for generating superpositions of non-canonical, higherorder Bessel beams, which are characterized by the anisotropy of the optical vortex on the propagation axis, known as the morphology ...
  • Naidoo, Darryl; Roux, Filippus S; Dudley, Angela; Litvin, Igor; Piccirillo, B; Marrucci, L; Forbes, A (Nature Publishing Group, 2016-03)
    The angular momentum of light can be described by positions on a higher-order Poincaré sphere, where superpositions of spin and orbital angular momentum states give rise to laser beams that have many applications, from ...
  • Dudley, Angela L; Vasilyeu, R; Belyi, V; Khilo, N; Ropot, P; Forbes, A (Elsevier, 2011-09)
    In this work we investigate the structure of nondiffracting speckle fields, both experimentally and theoretically. We are able to produce very good agreement between the experimentally recorded and theoretically calculated ...
  • Dudley, Angela L; Li, Y; Mhlanga, T; Escuti, M; Forbes, A (2013-07)
    This is a paper presented on creating and decomposing vector Bessel beams, presented at the 58th annual SAIP conference.
  • Forbes, A; Dudley, Angela; McLaren, M (Optical Society of America, 2016-06)
    Modal decomposition of light has been known for a long time, applied mostly to pattern recognition. With the commercialization of liquid-crystal devices, digital holography as an enabling tool has become accessible to all, ...
  • Naidoo, Darryl; Mafusire, C; Forbes, A (South African Institute of Physics, 2009-07)
    An optical aberration is a distortion of an image as compared to the object due to defects in an optical system
  • Forbes, A; Botha, LR; Du Preez, N; Drake, TE (Acad Science South Africa A S S AF, 2006-07)
    Laser ultrasonic is currently the optimal method for non-destructive testing of composite materials in the aerospace industry. The process is based on a laser-generated, ultrasound wave which propagates inside the composite. ...
  • Forbes, A; Botha, LR; du Preez, N; Drake, T (2006-02)
    Laser ultrasonics is the present state-of-the art method for non-destructive testing of composite materials in the aerospace industry. The process is based on an IR laser generating an ultrasound wave that propagates inside ...