ResearchSpace
→
Browsing by Author

Browsing by Author "Forbes, A"

Now showing items 34-53 of 261

Characterising laser beams with liquid crystal displays

Author: Dudley, Angela L ; Naidoo, Darryl ; Forbes, A Date: Sep 2016 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. Although the ... Read more
Characterization of high-dimensional entangled systems via mutually unbiased measurements

Author: Giovannini, D ; Romero, J ; Leach, J ; Dudley, Angela L ; Forbes, A ; Padgett, MJ Date: Apr 2013 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 in such bases ... Read more
Comparison of infrared laser beam shaping by diffractive and refractive methods

Author: Forbes, A ; Du Plessis, A ; Rohwer, EG Date: Aug 2005 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 have been developed ... Read more
Complete azimuthal decomposition of optical fields

Author: Dudley, Angela L ; Litvin, I ; Roux, FS ; Forbes, A Date: Feb 2013 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 ring, allowing us ... Read more
Computational fluid dynamics model of the spinning pipe gas lens

Author: Mafusire, C ; Forbes, A ; Snedden, Glen C Date: Aug 2010 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 results of its performance ... Read more
Constructing “petal” modes from the coherent superposition of Laguerre-Gaussian modes

Author: Naidoo, Darryl ; Forbes, A ; Aït-Ameur, K ; Brunel, M Date: Jan 2011 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 from a coherent ... Read more
Controlled acceleration of superimposed Bessel beams

Author: Dudley, Angela L ; Schulze, C ; Roux, FS ; Duparré, M ; Forbes, A Date: Jun 2013 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 parameter. We ... Read more
Controlled generation of higher-order Poincaré sphere beams from a laser

Author: Naidoo, Darryl ; Roux, Filippus S ; Dudley, Angela L ; Litvin, Igor ; Piccirillo, B ; Marrucci, L ; Forbes, A Date: Mar 2016 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 microscopy to materials ... Read more
Controlling the evolution of nondiffracting speckle by complex amplitude modulation on a phase-only spatial light modulator

Author: Dudley, Angela L ; Vasilyeu, R ; Belyi, V ; Khilo, N ; Ropot, P ; Forbes, A Date: Sep 2011 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 fields by using ... Read more
Creating and decomposing vector Bessel beams

Author: Dudley, Angela L ; Li, Y ; Mhlanga, T ; Escuti, M ; Forbes, A Date: Jul 2013 This is a paper presented on creating and decomposing vector Bessel beams, presented at the 58th annual SAIP conference. Read more
Creation and detection of optical modes with spatial light modulators

Author: Forbes, A ; Dudley, Angela L ; McLaren, M Date: Jun 2016 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, and with it all-digital ... Read more
Demonstrating optical aberrations in the laboratory

Author: Naidoo, Darryl ; Mafusire, C ; Forbes, A Date: Jul 2009 An optical aberration is a distortion of an image as compared to the object due to defects in an optical system Read more
Design and optimisation of a pulsed CO2 laser for laser ultrasonic applications

Author: Forbes, A ; Botha, LR ; Du Preez, N ; Drake, TE Date: Jul 2006 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. The response at ... Read more
Design and optimisation of a pulsed CO2 laser for laser ultrasonics

Author: Forbes, A ; Botha, LR ; du Preez, N ; Drake, T Date: Feb 2006 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 the composite ... Read more
Determination of the emissivity of the tungsten hexa-ethoxide pyrolysis flame using Fourier Transform Infrared (FTIR) spectroscopy

Author: Mudau, AE ; Mwakikunga, Bonex W ; Brink, N ; Willers, Cornelius J ; Forbes, A ; Shikwambana, L ; Govender, M Date: Sep 2010 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 present the ... Read more
Development of a Piezoelectric Adaptive Mirror for Laser Beam Control

Author: Long, Craig S ; Loveday, Philip W ; Forbes, A Date: Jun 2008 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 finish, bonded to ... Read more
Digital control of laser modes with an intra-cavity spatial light modulator

Author: Ngcobo, Sandile ; Litvin, I ; Burger, L ; Forbes, A Date: Feb 2014 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 light modulator as a ... Read more
Digital holograms for laser mode multiplexing

Author: Mhlanga, T ; Trichili, A ; Dudley, Angela L ; Naidoo, Darryl ; Zghal, M ; Forbes, A Date: 02 Oct 2014 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 transmission ... Read more
A digital laser for on-demand laser modes

Author: Ngcobo, Sandile ; Litvin, I ; Burger, L ; Forbes, A Date: Aug 2013 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 effort and suffer from ... Read more
The digital laser: on-demand laser modes with the click of a button

Author: Forbes, A ; Ngcobo, Sandile ; Burger, L ; Litvin, IA Date: Feb 2014 In this paper we will outline our recent advances in all-digital control of light. Importantly, we will outline how to create a so-called “digital laser”, where a conventional laser mirror is replaced with a phase-only spatial light modulator. ... Read more

Now showing items 34-53 of 261

Browse

All of ResearchSpace

Quick Links

Legislation and compliance

General Enquiries

Tel: + 27 12 841 2911
Email: callcentre@csir.co.za

Physical Address
Meiring Naudé Road
Brummeria
Pretoria
South Africa

Postal Address
PO Box 395
Pretoria 0001
South Africa

Social Connect

Copyright © CSIR 2017. All Rights Reserved

Resources on this site are free to download and reuse according to associated licensing provision. Please read the terms and conditions of usage of each resource.