Thermal Lens
Mostrando 13-24 de 27 artigos, teses e dissertações.
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13. Thermal Lens Spectrometry in solids:theory and applications / Espectrometria de lente térmica em sólidos: teoria e aplicações
Neste trabalho propomos o estudo da Espectrometria de Lente Térmica, sua teoria e aplicações, visto ser uma técnica de alta sensibilidade e que permite a medida das propriedades termo-ópticas dos materiais, como a difusividade térmica (D), a condutividade térmica (k), desvio do caminho óptico pela temperatura (ds/dT) - para materiais sólidos - ou a
Publicado em: 2005
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14. Medidas de lente termica em vidros borossilicato com pontos quanticos de CdTe / Thermal lens measurenments in quantum dots borossilicate glasses
Os vidros dopados com semicondutores são objeto de grande interesse como materiais ópticos não lineares e estudos intensivos acerca dos efeitos de confinamento quântico e não linearidade ótica tem sido realizados. Apesar do grande interesse nas propriedades óticas desses materiais, os dados térmicos e opto-térmicos são ainda escassos e raros. Neste
Publicado em: 2005
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15. Spectroscopy of thermal and population lens in rare-earth doped solids / Espectroscopia de lente térmica e de lente de população em sólidos dopados com íons terras-raras
As técnicas de lente térmica (LT) e "Z-scan" foram usadas para estudar as propriedades termo-óticas (difusividade térmica, condutividade térmica, taxa de variação do caminho ótico em função da temperatura e eficiência quântica de fluorescência) e não-lineares (partes real e imaginária do índice de refração não-linear, diferença de polariz
Publicado em: 2003
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16. Thermal lens temperature scanning for quantitative measurements in complex fluids
In this work thermal lens spectrometry is applied to investigate the thermo-optical properties of complex fluids as a function of the temperature. The method is applied in poly(vinyl chloride), in polycarbonate and in lyotropic liquid crystals as the testing samples. The focus of the discussion will be in the temperature range where the phase transitions occ
Brazilian Journal of Physics. Publicado em: 2002-06
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17. New applications of photothermal techniques for studying interfaces. / Novas aplicações de técnicas fototérmicas para o estudo de interfaces.
This work presents the development of new instrumentations based on photothermal phenomena to study solid-liquid and liquid-gas interfaces, including in the latter the effect of surfactants. The work is divided into chapters, each one focusing on the development and/or application of a new technique. Chapter I presents an introduction to photothermal phenome
Publicado em: 2001
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18. Espectroscopia não linear em cristais fluoretos e polianilina / Nonlinear spectroscopic characterization in fluoride crystals and polyaniline
In this work we studied the effect of nonlinear refraction in Cr+3 doped fluoride host crystals and polymers. The fluoride crystals have been attractive due a broad emission bandwidth and a tunable solid-state lasing in the range of approximately 780-1010 nm. Applying the Thermal Lens (TL) technique, we accomplished a quantitative study of the behavior of th
Publicado em: 2001
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19. Aplicações da técnica de lente térmica em materiais ópticos. / Applications of the thermal lens technique in optical materials
Neste trabalho, a técnica de Lente Térmica (LT) foi usada para determinar o valor absoluto da difusividade térmica (D), da condutividade térmica (K) e do coeficiente de temperatura do caminho óptico (ds/tD) de vidros fluoretos dopados com cobalto e neodímio, calcogenetos, calcohaletos (mistura de calcogenetos com haletos), aluminate de cálcio e de um
Publicado em: 1999
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20. Aplicação da técnica de varredura-Z para a determinação de parâmetros térmicos. / Z-scan technique to evaluate thermal parameters.
The Z-Scan technique is the most popular one for the determination of the nonlinear index of refraction (n2) of transparent media. In this work we present a theoretical analysis and results of the reflection z-scan technique, aiming the research of thermal effects in highly absorbing materials. Extensions of the technique, such as the time resolved z-scan an
Publicado em: 1998
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21. Espectroscopia de lente termica : propriedades termicas de cristais liquidos
Liquid Crystals are fluids that present intermediate properties between solid and liquid, and consist of a molecular arrange with structural order. These systems are classified as Thermotropic Liquid Cristals, Lyotropie Liquid Crystals and Plastic Crystals. Since their discovery, these systems have shown to be an important area of condensed matter research.
Publicado em: 1997
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22. Thermal lens measurements in the cornea.
Q-switched pulses from a neodymium/YAG (yttrium-aluminium-garnet) laser were passed through corneal discs taken from the enucleated eyes of three baboons and four rabbits. The time course of heat dissipation following absorption of laser energy by the tissue was studied with the use of a second continuous wave laser beam acting as a probe. It was found that
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23. D-value determinations are an inappropriate measure of disinfecting activity of common contact lens disinfecting solutions.
Determination of a D value for specific test organisms is a component of the efficacy evaluation of new contact lens disinfecting solutions. This parameter is commonly defined as the time required for the number of surviving microorganisms to decrease 1 logarithmic unit. The assumption made in establishing a D value is that the rate of kill exhibits first-or
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24. Cataracts and avionic radiations.
Nine cases of hertzian radiation cataracts are reported among personnel working in operational aviation environments, where they were irradiated repeatedly at subliminal non-thermal field intensities. The resultant ocular pathology evolved insidiously and slowly over a period of years in a similar way to other forms of radiational injury. By the time of cons