Browsing by Subject "Thulium"

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    Development of a thulium (Tm:YAP) laser system for brain tissue ablation
    (2011) Bilici, T.; Mutlu, S.; Kalaycioglu H.; Kurt, A.; Sennaroglu, A.; Gulsoy, M.
    In this study, a thulium (Tm:YAP) laser system was developed for brain surgery applications. As the Tm:YAP laser is a continuous-wave laser delivered via silica fibers, it would have great potential for stereotaxic neurosurgery with highest local absorption in the IR region. The laser system developed in this study allowed the user to set the power level, exposure time, and modulation parameters (pulse width and on-off cycles). The Tm:YAP laser beam (200-600 mW, 69-208 W/cm 2) was delivered from a distance of 2 mm to cortical and subcortical regions of ex-vivo Wistar rat brain tissue samples via a 200-μm-core optical fiber. The system performance, dosimetry study, and ablation characteristics of the Tm:YAP laser were tested at different power levels by maximizing the therapeutic effects and minimizing unwanted thermal side-effects. The coagulation and ablation diameters were measured under microscope. The maximum ablation efficiency (100 × ablation diameter/coagulation diameter) was obtained when the Tm:YAP laser system was operated at 200 mW for 10 s. At this laser dose, the ablation efficiency was found to be 71.4% and 58.7% for cortical and subcortical regions, respectively. The fiber-coupled Tm:YAP laser system in hence proposed for the delivery of photothermal therapies in medical applications. © 2011 Springer-Verlag London Ltd.
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    Effect of Composition on the Spontaneous Emission Probabilities, simulated Emission Cross Sections and Local Environment of Tm+3, in Teo2-Wo3 Glass'
    (Elsevier Science B.V, 2003-04) Özen, G.; Aydınlı, Atilla; Cenk, S.; Sennaroğlu, A.
    Effect of composition on the structure, spontaneous and stimulated emission probabilities of various 1.0 mol% Tm2O3 doped (1 - x)TeO2 + (x)WO3 glasses were investigated using Raman spectroscopy, ultraviolet-visible-near-infrared (UV/VIS/NIR) absorption and luminescence measurements. Absorption measurements in the UV/VIS/NIR region were used to determine spontaneous emission probabilities for the 4f-4f transitions of Tm3+ ions. Six absorption bands corresponding to the absorption of the (1)G(4), F-3(2), F-3(3) and F-3(4), H-3(5) and H-3(4) levels from the H-3(6) ground level were observed. Integrated absorption cross-section of each band except that of H-3(5) level was found to vary with the glass composition. Luminescence spectra of the samples were measured upon 457.9 nm excitation. Three emission bands centered at 476 nm ((1)G(4) --> H-3(6) transition), 651 nm ((1)G(4) --> H-3(4) transition) and 800 nm ((1)G(4) --> H-3(5) transition) were observed. Spontaneous emission cross-sections together with the luminescence spectra measured upon 457.9 nm excitation were used to determine the stimulated emission cross-sections of these emissions. The effect of glass composition on the Judd-Ofelt parameters and therefore on the spontaneous and the stimulated emission cross-sections for the metastable levels of Tm3+ ions were discussed in detail. The effect of temperature on the stimulated emission cross-sections for the emissions observed upon 457.9 nm excitation was also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
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    ItemOpen Access
    Fluence of thulium laser system in skin ablation
    (IEEE, 2010) Bilici, T.; Tabakoğlu, O.; Kalaycıoğlu, Hamit; Kurt, A.; Sennaroglu, A.; Gülsoy, M.
    Tm:YAP laser system at power levels up to 1.2 W at 1980 nm was established in both continuous-wave and modulated modes of operation. The fluence effect of the laser system for skin ablation was analyzed by histology analysis with Wistar rat skin tissues. Thermally altered length, thermally altered area, ablation area, and ablation depth parameters were measured on histology images of skin samples just after the laser operation and after four-day healing period. Continuous-wave mode of operation provided higher thermal effects on the skin samples. Lower fluence levels were found for efficient ablation effect. © 2010 IEEE.
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    ItemOpen Access
    Optical transitions of Tm3 + ions for amplifiers: how the local structure works in (1-x) TeO2 + (x) M (where M = LiCl, CdCl2, WO3) glass
    (OSA, 2002) Aydınlı, Atilla; Ay, Feridun; Sennaroǧlu, A.; Cenk, S.; Özen, G.
    Optical transitions of Tm3+ ions for amplifiers was presented. Stimulated emission cross-section at the peak wavelength of the emission bands was determined. It was concluded that Tm3+ doped binary tellurite glasses are promising materials for the infrared amplifiers.