Author:McLaren, M; Sidderas-Haddad, E; Forbes, ADate:Sep 2011It is now well known that matter may be trapped by optical fields with high intensity gradients. Once trapped, it is then possible to manipulate microscopic particles using such optical fields, in so-called optical tweezers. Such optical ...Read more
Author:Ndhundhuma, IMDate:Jan 2010Lasers have emerged as powerful tools for tissue engineering. To examine cellular growth, and cell to cell interactions, in vitro skin models have been developed combining two major cell types of skin, keratinocytes and fibroblasts. The main ...Read more
Author:Tesfaye, M; Sivakumar, V; Mengistu, G; Botai, J; Sharma, Ameeth; Bollig, C; Rautenbach, CJdWHDate:2010In this paper, the tropospheric aerosol load morphological classification and its impact on temporal variation of visibility are investigated using a continuous 23-hour single channel CSIR-NLC mobile LIDAR backscatter measurement. The trajectory ...Read more
Author:Dudley, Angela L; Litvin, I; Roux, FS; Forbes, ADate:Jul 2012This presentation analyses the azimuthal decomposition of optical modes. Decomposition of azimuthal modes need two steps, namely generation and decomposition. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency ...Read more
Author:Mthunzi-Kufa, PatienceDate:Oct 2012In this presentation the author highlights the use of lasers in micro-manipulating single cells and molecules.Read more
Author:Esser, MJD; Collett, O; Bollig, CDate:Oct 2010The authors present a continuous-wave slab laser utilising both Ho:YLF and Ho:LuLF as laser gain media. 30 W of output power at 2 µm was demonstrated in a stable concave-plane resonator while 13 W was achieved in a hybrid stable-unstable ...Read more
Author:Esser, MJD; Preussler, DR; Bernhardi, EH; Bollig, C; Posewang, MDate:Oct 2009High power operation at 1818 and 1915 nm has been demonstrated from a Tm:GdVO4 laser operating in quasi-continuous-wave mode with a maximum measured power of 8.7Wand a laser output energy of 175 mJ was observed in a 20 ms pulse at 1.9 µm. The ...Read more
Author:Strauss, Hencharl J; Koen, W; Bollig, C; Esser, MJD; Preussler, D; Nyangaza, K; Jacobs, CobusDate:Jun 2009In this paper, researchers have demonstrated that a Ho:YLF oscillator and amplifier system can be designed in a compact setup where the pump power from an unpolarized fibre laser utilized efficiently. The system produced more than 20 mJ energy ...Read more
Author:Kotze, FJ; Strydom, CA; Du Plessis, A; Dlamini, TLDate:Mar 2010The direct excitation of CO2 using fast (nanosecond) and ultrafast (femtosecond) pulsed lasers was investigated. A gas reaction cell was used to excite CO2 in a 50 : 50 mixture of CO2 and CH4 using nano- and femtosecond laser systems, to ...Read more
Author:Govender, M; Shikwambana, L; Mwakikunga, Bonex W; Sideras-Haddad, E; Erasmus, RM; Forbes, ADate:Jun 2010This report focuses on the production of multi-phase WO3 and WO3-x (where x could vary between 0.2 and 0.33) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 ...Read more
Author:Botha, RC; Koen, W; Esser, MJD; Bollig, C; Combrinck, WL; Von Bergmann, M; Strauss, Hencharl JDate:Feb 2015A 1314 nm two-crystal Nd:YLF laser was designed and operated in both CW and actively Q-switched modes. Maximum CW output of 26.5 W resulted from 125 W of combined incident pump power. Active Q-switching was obtained by inserting a Brewster-cut ...Read more
Author:Koen, W; Strauss, Hencharl J; Bollig, C; Esser, MJDDate:Sep 2010The authors present a high-power Tm:YLF slab laser double-end-pumped by two 300 W laser diode stacks. The resonator was designed such that the laser emitted at 1890 nm instead of the conventional operating wavelength of 1912 nm. At full ...Read more
Author:Schellhorn, M; Ngcobo, S; Bollig, C; Esser, MD; Preussler, DR; Nyangaza, KDate:Jun 2009The aim is to develop a high-power Tm:YLF slab laser which can be utilized to pump a Ho slab laser. A 68 W Tm:YLF slab laser was recently presented in [1] pumped from one end by a single 6-bar stack delivering ~300 W of pump power. In this ...Read more
Author:Strauss, Hencharl J; Koen, W; Bollig, C; Esser, MJD; Jacobs, Cobus; Collett, OJP; Preussler, DRDate:Jul 2011A single-frequency single-pass amplifier based on Ho:YLF and Ho:LuLF in a scalable slab architecture delivering up to 210 mJ at 2064 nm is demonstrated. The amplifier was end-pumped by a 1890 nm Tm:YLF slab laser and was seeded with a 69 mJ ...Read more
Author:Adebiyi, DI; Fedotova, T; Pityana, Sisa L; Popoola, APIDate:Jul 2011The improvement in hardness of X12CrNiMo martensitic stainless steel laser alloyed with 99.9% pure titanium carbide, stellite 6 and two cases of premixed ratio of titanium carbide and stellite 6 [TiC (30 wt.%)- stellite 6 (70 wt.%) and TiC ...Read more
Author:Naidoo, Darryl; Aït-Ameur, K; Brunel, M; Forbes, ADate:2012In this paper we demonstrate experimentally the intra-cavity generation of a coherent superposition of Laguerre–Gaussian modes of zero radial order but opposite azimuthal order. The superposition is created with a simple intra-cavity stop ...Read more
Author:Burger, L; Forbes, ADate:Aug 2008The authors apply a new method of modeling Porro prism resonators, using the concept of rotating loss screens, to study stable and unstable Porro prism resonator. They show that the previously observed petal–like modal output is in fact only ...Read more
Author:Popoola, AP; Pityana, Sisa LDate:Oct 2010The present work deals with the development of Aluminium metal matrix composite (MMC) using TiB2 reinforcement. The aim is to improve the microhardness property of the substrate. The surface of the aluminium was sand blasted to improve its ...Read more
Author:Dudley, Angela L; Litvin, I; Forbes, ADate:Jan 2012To measure the Orbital Angular Momentum (OAM) density of superposition fields two steps are needed: generation and measurement. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency domain produces a higher-order ...Read more