Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"thermal lensing"”.
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The study of photo-thermal lensing system and its applications
… per million (ppm). In this thesis, the photo-thermal lens setup provides another way to measure the change in the sample related to heating with sensitivity up to 10^{-6}. This technique is a pump-probe technique which depends on a change in an optical property measured by a weak probe laser …
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Investigation of Thermal Lensing in Nuclear Combined Wall/volume Pumped Lasers
Finally, a radioisotope powered gas medium is proposed for the first time as a method to produce gas lenses for potential industrial applications.
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Investigation of the optical, thermal, and mechanical properties of a bulk polymer using the surface thermal lensing technique
<p>The sensitive and simple photothermal technique of Surface Thermal Lensing (STL) was employed to study the thermo-mechanical response of an amorphous polycarbonate as a bulk. A discussion is given of how previously developed theories did not fit well with the present work. Therefore, only …
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Laser surface thermal lensing (STL): An optical method for surface analysis of glass transition effects in transparent polymers
… beam by a transparent substrate leads to cyclic thermal expansion and contraction of the surface at the pump beam focus. This minute distortion of the surface forms a transient optical lens structure, which can be monitored by the changes it induces in a second laser beam reflected at an angle …
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Study of the physics of the power-scaling of end-pumped solid-state laser sources based on Nd:YVO<sub>4</sub>
Using a modified Mach-Zehnder interferometer the thermal lensing in Nd:YV0<sub>4</sub> was measured for several different operating conditions. The thermal lens focal length can be determined from the measured transverse phase profile. It was found that the thermal lensing was weakest for …
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Laser-induced heating, phase-shift, and damage : measurements and simulations
… of Texas at Austin to study laser induced thermal lensing. Analysis with a high-frame rate thermal camera system in an optical cuvette determined rates of heating and cooling in water exposed to 1200, 1310 and 1318-nm wavelengths. Thermal modeling software (BTEC) developed at AFRL was used …
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Powers scaling and nonlinear frequency conversion of single-frequency lasers based
… laser rod, increasing the effects of detrimental thermally related problems such as thermal lensing, stress-induced birefringence and stress induced laser rod fracture. Also a passive technique for mode-hopping-suppression is described, allowing the oscillating frequency within the laser cavity to …
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Modal Properties and Spontaneous Emission Factor in Unstable-Resonator Semiconductor Lasers
… the unstable-resonator is sensitive to the thermal lensing effect that normally occurs when the laser in under CW pumping. In the laser device used in this study, the thermal lensing effects can make the resonator more "stable", resulting in a drastic reduction in the spontaneous emission …
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Thermal and Optical Simulations of Vertical Cavity Surface Emitting Lasers
… a fully self-consistent and coupled electronic-thermal-optical simulator for vertical cavity surface emitting lasers (VCSELs). The lattice temperature model is derived based on carrier transport and the conservation of energy. A novel treatment is applied to model distributed Peltier heat at a …
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Hyper-Rayleigh scattering measurements of hyperpolarizabilities for tetrahedral molecules
… nonlinear optics. Through z-scan measurements, thermal lensing and/or absorption coefficients have been obtained for six molecules.
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Quantum limited optical phase detection in a high power suspended interferometer
… suspended optics, laser frequency control, and thermal lensing.
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Development of high power fibre amplifier components, systems and applications
… plate between the rotators to compensate for thermal stress induced birefringence. Using this approach the isolation was shown to be constant to greater than 60W. The isolator was also compensated for thermal lensing by balancing the positive thermal lens produced in the Faraday rotator with a …
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Thermal and spectral effects in intracavity Raman lasers
… This thesis presents a detailed investigation of thermal and spectral effects in CW intracavity Raman lasers. A disk geometry was used to reduce the thermal lens in the laser gain crystal, thereby permitting more flexible cavity design. This facilitated experiments to probe and control the thermal …
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Influence of Induced natural convection on laser propagation : analysis and interferometric visualization
… Here, this formation is referred to as the thermal ring. The horizontal laser beam is first modeled as a linear source of uniform strength along the propagation path. The change in temperature is calculated using a similarity solution, and the resulting refractive index change predicts the …
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Rare-earth-doped gallium lanthanum sulphide glasses for mid-infrared fibre lasers
… glass and glass fibre, respectively. The strong thermal lensing in the bulk glass rules out the use of GLS glass as a bulk laser material. The effect was eliminated by using a fibre geometry showing the advantages and necessity of GLS glass fibre.
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Cladding-pumped Raman fibre laser sources
… output power is limited to around 24 kW by thermal lensing if the core is large enough and enough pump power available. Experimentally, in collaboration with co-workers, a 100 W claddingpumped Raman fibre laser was demonstrated at 1116 nm. The output beam was nearly diffraction-limited. It …
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The synergistic role of light and heat in liquid-based nanoparticle manipulation
… biomolecules. When optical effects dominate over thermal effects, the motion of nanoparticles can be controlled by optical forces. Here, we study the motion of 100 nm gold particles within a 1D optical potential, created by interfering counterpropagating beams. Tracking of particle trajectories …