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Browsing by Author "Forbes, A"

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  • 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 ...
  • 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 ...
  • Mudau, AE; Mwakikunga, BW; Brink, N; Willers, CJ; Forbes, A; Shikwambana, L; Govender, M (SAIP 2010, 2010-09)
    To determination the temperature using infrared cameras, the following issues need to be addressed, the emissivity of the object and atmospheric path effects. The later is negligible in the setup used. In this paper authors ...
  • Long, CS; Loveday, PW; Forbes, A (HVG Hanseatische Veranstaltungs-GmbH, 2008-06)
    An intra-cavity adaptive mirror is developed for compensation of time-dependent phase aberrations to a laser beam, such as those caused by thermal lensing. The unimorph-type device consists of a metallic disc, with a mirror ...
  • Ngcobo, S; Litvin, I; Burger, L; Forbes, A (SPIE Proceedings, 2014-02)
    In this paper we outline a simple laser cavity which produces customised on-demand digitally controlled laser modes by replacing the end-mirror of the cavity with an electrically addressed reflective phase-only spatial ...
  • Mhlanga, T; Trichili, A; Dudley, Angela L; Naidoo, Darryl; Zghal, M; Forbes, A (SPIE, 2014-10-02)
    High-capacity data transmission has been implemented using single channel optical systems. This technique is limited and soon it will be unable to ful ll the growing needs for higher bit rate data transmission. Hence multi-mode ...
  • Ngcobo, S; Litvin, I; Burger, L; Forbes, A (Nature Publishing Group, 2013-08)
    Customizing the output beam shape from a laser invariably involves specialized optical elements in the form of apertures, diffractive optics and free-form mirrors. Such optics require considerable design and fabrication ...