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Projeto e construção de um amplificador paramétrico óptico operando no infravermelho médio; Design and construction of an optical parametric amplifier operating in the mid-infrared

Mendonça, Marcela de Freitas
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 24/05/2010 PT
Relevância na Pesquisa
36.45%
Um Amplificador Paramétrico Óptico (optical parametric amplifier - OPA) é uma fonte de luz coerente, de alta qualidade e sintonizável, baseada em processos ópticos não-lineares de segunda ordem. Alguns modelos possuem largura de banda estreita e um amplo intervalo de sintonia, podendo alcançar regiões que vão desde o ultravioleta até o infravermelho médio. A nossa motivação para construir este amplificador paramétrico óptico é sua utilização em experimentos de espectroscopia vibracional de superfícies através do processo óptico não-linear de segunda ordem, geração de soma de frequências (sum-frequency generation - SFG), que é uma técnica que exige fontes sintonizáveis no infravermelho médio e com altas intensidades de pico e largura de banda estreita. O objetivo desse trabalho foi projetar, montar e testar um amplificador paramétrico óptico capaz de produzir pulsos sintonizáveis de alta energia no infravermelho médio (λ ~ 2,5 a 10 μm) a partir de um laser de bombeio que fornece pulsos de 25 ps, com alta energia em λ = 1064 nm. Para obter-se uma geração de infravermelho bastante eficiente, foi proposto um projeto inovador para amplificadores paramétricos de picossegundos, utilizando-se a geração de supercontínuo de luz branca como feixe sinal do estágio de amplificação paramétrica. O pulso de bombeio (λ = 1064 nm) é dividido em duas partes: a primeira...

Crescimento, fabricação e teste de fotodetectores de radiação infravermelha baseados em pontos quânticos; Growth fabrication and testing of quantum-dots infrared photodetectors

Maia, Álvaro Diego Bernardino
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/08/2012 PT
Relevância na Pesquisa
36.39%
Os fotodetectores infravermelhos baseados em pontos quânticos (Quantum-dot Infrared Photodetectors, QDIPs) surgiram recentemente como uma nova tecnologia para a detecção de radiação infravermelha. Comparados com fotodetectores mais convencionais baseados em poços quânticos (Quantum-well Infrared Photodetectors, QWIPs), as suas vantagens se originam no confinamento tridimensional de portadores e incluem a sensibilidade intrínseca à incidência normal de luz, um maior tempo de vida dos portadores fotoexcitados e uma baixa corrente de escuro, que devem permitir o funcionamento dos dispositivos acima das temperaturas criogênicas. No presente trabalho, a técnica de epitaxia por feixe molecular (Molecular-Beam Epitaxy - MBE) foi usada para crescer várias amostras de QDIPs de InAs/GaAs com o objetivo de estudar a inuência dos parâmetros estruturais destes dispositivos. Após o crescimento, as amostras foram processadas em pequenas mesas quadradas por técnicas de litografia convencional e, então, caracterizadas. As propriedades ópticas e eletrônicas dos dispositivos foram verificadas para temperaturas a partir de 10 K. Com o objetivo de realizar medidas eletrônicas de alta qualidade, janelas de Ge e cabos com conectores de baixo ruído para baixa temperatura foram empregados. As curvas de corrente de escuro...

Infrared LED irradiation photobiomodulation of oxidative stress in human dental pulp cells

Montoro, L. A.; Turrioni, A. P. S.; Basso, F. G.; Souza Costa, C. A. de; Hebling, J.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 747-755
ENG
Relevância na Pesquisa
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 12/09502-6; Processo FAPESP: 11/16529-5; Aim To investigate the effect of infrared light-emitting diode (LED) irradiation on the oxidative stress induced in human dental pulp cells (HDPCs) by lipopolysaccharide (LPS).Methodology Human dental pulp cells (HDPCs) were harvested from sound primary teeth that were near exfoliation. Cells were seeded (10 5 cells cm(-2)) using alpha-MEM supplemented with 10% FBS and after 24 h, were placed in contact with LPS (10 mu g mL(-1) of culture medium). Immediately afterwards, HDPCs were subjected to a single irradiation with an infrared LED (855 nm) delivering different doses of energy (0, 2, 4, 8, 15 or 30 J cm(-2)). For each dose, there was a control group without LPS application. Twenty-four hours after irradiation, groups were tested for nitric oxide (NO) quantification, cell viability (MTT assay) and qualitative assessment of reactive oxygen species (ROS). Data were submitted to Kruskal-Wallis and Mann-Whitney tests (alpha = 0.05).Results Lipopolysaccharide (LPS)-induced stress resulted in significant increase in NO production by HDPC without causing damage to cell respiratory metabolism. Irrespective of energy dose delivered...

Determinação de parametros de qualidade em bananas utilizando espectroscopia no infravermelho e calibração multivariada; Determination of banana quality parameters by infrared spectroscopy and multivariate analysis

Luciana Viviani Gallo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/06/2008 PT
Relevância na Pesquisa
36.42%
Neste trabalho foi desenvolvida uma metodologia analítica alternativa para a determinação de parâmetros de qualidade em bananas: pH, acidez titulável e Brix utilizando as espectroscopias no infravermelho médio e próximo em conjunto com calibração multivariada. A estratégia adotada foi obter os espectros na região do infravermelho próximo e médio do fruto e estabelecer um modelo de calibração multivariada, baseada no método dos mínimos quadrados parciais, para prever os diversos parâmetros. Foram utilizadas 54 amostras de banana, em diferentes estágios de maturação. Os espectros foram obtidos a partir da análise da polpa do fruto macerada, da solução obtida após a centrifugação da polpa, e pela técnica “Dry Extract Spectroscopy by infrared Absorption” (DESIR). Um total de 9 modelos foram propostos para a determinação dos parâmetros de qualidade e o melhor resultado para a determinação de pH foi na região do infravermelho médio utilizando a técnica DESIR, com erro médio de 1,32%. Já para a acidez, o melhor modelo obtido foi na região do infravermelho próximo utilizando DESIR, com erro relativo médio de 6,20%. O parâmetro brix apresentou melhores resultados na região do infravermelho médio através da análise da solução...

Aplicação de espectroscopia no infravermelho e análise multivariada para previsão de parâmetros de qualidade em soja e quinoa= : Application of infrared spectroscopy and multivariate analysis to predict quality parameters in soybean and quinoa; Application of infrared spectroscopy and multivariate analysis to predict quality parameters in soybean and quinoa

Daniela Souza Ferreira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/03/2013 PT
Relevância na Pesquisa
36.39%
A avaliação da qualidade nutricional de alimentos é realizada principalmente por meio da determinação dos componentes majoritários, conhecida como composição centesimal (umidade, proteína, cinza, lipídio, carboidrato e fibra). No entanto, os métodos tradicionais de análise são demorados e utilizam materiais, equipamentos e diversos reagentes químicos, que além de oferecerem risco ao analista, geram resíduos tóxicos. Diante disto, uma alternativa para a análise química de grãos, rápida, de baixo custo e sem uso de reagentes químicos é a espectroscopia na região do infravermelho. Visando atender a demanda do Brasil por pesquisas empregando espectroscopia no infravermelho para análise de alimentos, o objetivo desse trabalho foi avaliar a possibilidade de utilização das técnicas espectroscopia no infravermelho próximo (NIR), principalmente, e médio MIR, associadas à quimiometria, para previsão de parâmetros de qualidade da soja brasileira e quinoa da América do Sul. Para comparar a aplicação de NIR e MIR, amostras de soja provenientes do Paraná foram analisadas pelas duas técnicas para previsão da composição centesimal. Os erros relativos (E%) entre os valores de referência e os valores previstos pelos modelos de calibração PLS...

Infrared coagulation: a preferred option in treating early hemorrhoids

Gupta,Pravin J.
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2004 EN
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36.42%
BACKGROUND: The ideal therapy for hemorrhoids is always debated. For early grades of the disease, many different modalities of treatment have been proposed. Some are effective but are more painful, others are less painful but their efficacy is not assured on long term. Infrared photocoagulation has emerged as a new addition to the list. In this procedure, the tissue is coagulated by infrared radiation. During treatment, mechanical pressure and radiation energy are applied simultaneously to ablate the blood supply to the hemorrhoidal mass. METHODS: In the present retrospective study, the effect of infrared coagulation on patients with early grades of hemorrhoids is described. In a separate study, a comparison is made between Infrared coagulation and rubber band ligation in terms of their effectiveness and discomfort. RESULTS: 212 patients were treated by infrared coagulation and were followed up for a period of 18 months. Only 28 patients had persistence or recurrence of bleeding. Overall ratio of comfort and patient satisfaction from pain and bleeding was quite satisfactory. The comparative study showed that though rubber band ligation is more effective, it is a more painful procedure. CONCLUSION: These studies shows that Infrared coagulation for hemorrhoids in early stages could prove to be a easy and effective alternative to conventional methods as it is quick...

Espectroscopia de infravermelho próximo em análises de solos e plantas; Near-infrared spectroscopy in analysis of soils and plants

Santos, Ana Paula dos
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
36.39%
As análises de solos e plantas, essenciais no manejo da adubação das culturas, estão baseadas em metodologias que consomem tempo e reagentes. A espectroscopia de infravermelho próximo (NIR – Near-infrared) tem se mostrado uma alternativa mais rápida e limpa para quantificação simultânea de compostos. Objetivou-se nesse trabalho avaliar as metodologias baseadas na região NIR, aliada a métodos de calibração multivariada para estimar teores de silício (Si), matéria orgânica (M.O.) e argila em solos e, nitrogênio total (N-Total) em folhas de milho e soja. Para isto, 170 amostras de solos foram utilizadas para a calibração de modelos de análises de solos e 109 amostras de folhas (58 de milho e 51 de soja), sendo seus espectros obtidos em um espectrofotômetro de infravermelho próximo modelo NIR 900PLS pertencente ao Laboratório de Fertilizantes da Universidade Federal de Uberlândia (LAFER), em Uberlândia-MG, onde os modelos foram construídos. O método matemático utilizado foi o de mínimos quadrados parciais: PLS (Parcial Least Squares). A validação dos modelos foi cruzada e o número de variáveis latentes variaram entre 5 e 8. Os métodos de referência comparados foram: colorimétrico com extração por cloreto de cálcio (0...

Cerebral oxygenation monitoring by near-infrared spectroscopy is not clinically useful in patients with severe closed-head injury: a comparison with jugular venous bulb oximetry

Lewis, S.; Myburgh, J.; Thornton, E.; Reilly, P.
Fonte: Williams & Wilkins Publicador: Williams & Wilkins
Tipo: Artigo de Revista Científica
Publicado em //1996 EN
Relevância na Pesquisa
36.44%
OBJECTIVE: To compare continuous jugular venous bulb oximetry and cerebral near-infrared spectroscopy in patients with severe closed head injury. DESIGN: A prospective observational study. SETTING: Intensive care unit of a major teaching hospital. PATIENTS: Adults (n = 10) with severe closed-head injury (Glasgow Coma Scale score of < or = 8). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Jugular venous bulb oximetry, cerebral near-infrared spectroscopy, and cerebral perfusion pressure were measured continuously. A total of 3,691 paired measurements of near-infrared spectroscopy and jugular venous bulb oximetry were analyzed. Poor correlation (r2 = .04) between paired measurements and wide limits of agreement (-13% to +21%) were demonstrated. The mean difference between measurements was +/- 4% and the standard deviation of the mean difference was +/- 8.69%. The data were subsequently grouped according to three clinically significant subgroups of jugular venous bulb oxygen saturation reflecting low ( < 55%), normal (55% to 75%) and high ( > 75%) saturation values. Poor correlation and wide limits of agreement between the two methods of measurement were observed in all groups. Values recorded by near-infrared spectroscopy did not significantly change between the groups...

Feasibility of infrared spectroscopy with pattern recognition techniques to identify a subpopulation of mares at risk of producing foals diagnosed with failure of transfer of passive immunity

Riley, Christopher Bruce; McClure, J. Trenton; Low-Ying, Sarah; Dolenko, B. K.; Somorjai, R. L.; Shaw, R. Anthony
Fonte: Australian Veterinary Association Publicador: Australian Veterinary Association
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.39%
OBJECTIVE: To assess the feasibility of a serum-based test using infrared spectroscopy to identify a subpopulation of mares at risk of producing foals susceptible to failure of passive transfer of immunity (FPT) because of mare-associated factors. MATERIALS AND METHODS: Serum was collected from postparturient mares (n = 126) and their foals at 24–72 h of age. A radial immunodiffusion IgG test was used to determine each foal’s serum IgG concentration. Infrared absorbance spectra of dam sera were collected in the wave number range of 400–4000 cm-1. Following data preprocessing, pattern recognition techniques were used to identify spectroscopic information capable of distinguishing between mares with FPT foals and those with normal foals. The sensitivity and specificity of infrared spectroscopy to detect riskpositive mares were calculated. RESULTS: Five wave number regions were identified as optimal for distinguishing between the two groups of mares: 740.9–785.2 cm-1, 796.8–816.0 cm-1, 970.4–993.5 cm-1, 1371.6–1406.3 cm-1 and 1632.0–1659.0 cm-1. Based upon the infrared spectroscopic information within these discriminatory subregions, the spectra provided the risk status of the mares with a classification success rate of 81.0%. The sensitivity of the classification system was 85.7% and specificity was 80.0%. CONCLUSION: This preliminary study demonstrates that infrared spectra of dam serum have the potential to provide the basis for a new periparturient screening method for a subpopulation of mares at risk of having a foal susceptible to FPT. Further developmentmay provide an economic and rapid technique for the pre-parturient assessment of mares.; C.B. Riley...

NIR, MWIR and LWIR quantum well infrared photodetector using interband and intersubband transitions

Alves, Fabio Durante P.; Karunasiri, G.; Hanson, N.; Byloos, M.; Liu, H.C.; Bezinger, A.; Buchanan, M.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.42%
The article of record as published may be located at http://dx.doi.org/10.1016/j.infrared.2006.10.021; This paper presents the design, fabrication and characterization of a QWIP photodetector capable of detecting simultaneously infrared radiation within near infrared (NIR), mid wavelength infrared (MWIR) and long wavelength infrared (LWIR). The NIR detection was achieved using interband transition while MWIR and LWIR were based on intersubband transition in the conduction band. The quantum well structure was designed using a computational tool developed to solve self-consistently the Schro¨dinger–Poisson equation with the help of the shooting method. Intersubband absorption in the sample was measured for the MWIR and LWIR using Fourier transform spectroscopy (FTIR) and the measured peak positions were found at 5.3 lm and 8.7 lm which agree well with the theoretical values obtained 5.0 lm and 9.0 lm for the two infrared bands which indicates the accuracy of the self-consistent model. The photodetectors were fabricated using a standard photolithography process with exposed middle contacts to allow separate bias and readout of signals from the three wavelength bands. The measured photoresponse gave three peaks at 0.84 lm, 5.0 lm and 8.5 lm wavelengths with approximately 0.5 A/W...

Integrated visible and near-infrared, shortwave infrared, and longwave infrared full-range hyperspectral data analysis for geologic mapping

Kruse, Fred A.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.44%
Airborne visible/infrared imaging spectrometer (AVIRIS) and spatially coincident hyperspectral thermal emission spectrometer (HyTES) data were used to map geology and alteration for a site in northern Death Valley, California and Nevada. AVIRIS with 224 bands from 0.4 to 2.5 μm were converted to reflectance. HyTES data with 256 bands covering 8 to 12 μm were converted to emissivity. Two approaches were investigated for integration of the datasets for full spectrum analysis. A combined (integrated) bands method utilized 332 spectral bands spanning both datasets. Spectral endmembers were extracted, and the predominant material at each pixel was mapped for the full spectral range using partial unmixing. This approach separated a variety of materials, but it was difficult to directly relate mapping results to surface properties. The second method used visible to near-infrared, shortwave infrared, and longwave infrared data independently to determine and map key endmembers in each spectral range. AVIRIS directly mapped a variety of specific minerals, while HyTES separated and mapped several igneous rock phases. Individual mapping results were then combined using geologically directed logical operators. The full-range results illustrate that integrated analysis provides advantages over use of just one spectral range...

Characterizing the Mid-infrared Extragalactic Sky with WISE and SDSS

Yan, L.; Donoso, Emilio; Tsai, Chao Wei; Stern, D.; Assef, R. J.; Eisenhardt, P.; Blain, A. W.; Cutri, R.; Jarrett, T. H.; Stanford, S. A.; Wright, E.; Bridge, C.; Riechers, D. A.
Fonte: American Astronomical Society Publicador: American Astronomical Society
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
36.45%
The Wide-field Infrared Survey Explorer (WISE) has completed its all-sky survey in four channels at 3.4–22um, detecting hundreds of millions of objects. We merge the WISE mid-infrared data with optical data from the Sloan Digital Sky Survey (SDSS) and provide a phenomenological characterization of WISE extragalactic sources. WISE is most sensitive at 3.4um (W1) and least sensitive at 22um (W4). The W1 band probes massive early-type galaxies out to z~1. This is more distant than SDSS identified early-type galaxies, consistent with the fact that 28% of 3.4um sources have faint or no r-band counterparts (r > 22.2). In contrast, 92%–95% of 12um and 22um sources have SDSS optical counterparts with r<22.2. WISE 3.4um detects 89.8% of the entire SDSS QSO catalog at S/N W1 >7σ, but only 18.9% at 22um with S/N W4 > 5 sigma. We show that WISE colors alone are effective in isolating stars (or local early-type galaxies), star-forming galaxies, and strong active galactic nuclei (AGNs)/QSOs at z~3. We highlight three major applications of WISE colors: (1) Selection of strong AGNs/QSOs at z~3 using W1−W2>0.8 and W2<15.2 criteria, producing a better census of this population. The surface density of these strong AGN/QSO candidates is 67.5$pm$0.14 deg^−2 . (2) Selection of dust-obscured...

The Night Sky at the Calar Alto Observatory II: The Sky at the Near-infrared

Sánchez, Sebastián F.; Aceituno, Jesús; Thiele, Ulrich; Cristóbal-Hornillos, David; Perea, Jaime; Alves, João
Fonte: American Astronomical Society; Astronomical Society of the Pacific; University of Chicago Press Publicador: American Astronomical Society; Astronomical Society of the Pacific; University of Chicago Press
Tipo: Artículo Formato: 767542 bytes; application/pdf
ENG
Relevância na Pesquisa
36.42%
11 pages, 6 figures, 4 tables.-- ArXiv pre-print available at: http://arxiv.org/abs/0809.4988; We present the characterization of additional properties of the night sky at the Calar Alto observatory, following the study started by Sánchez et al. in 2007. We focus here on the night-sky brightness at the near-infrared, the telescope seeing, and the fraction of useful time at the observatory. For this study we have collected a large data set comprising 7311 near-infrared images taken regularly along the last four years for the ALHAMBRA survey (J, H, and Ks bands), together with a more reduced data set of additional near-infrared images taken for the current study. In addition, we collected the information derived by the meteorological station at the observatory during the last 10 yrs, together with the results from the cloud sensor for the last ~2 yr. We analyze the dependency of the near-infrared night-sky brightness with the air mass and the seasons, studying its origins and proposing a zenithal correction. A strong correlation is found between the night-sky brightness in the Ks band and the air temperature, with a gradient of ~ -0.08 mag per 1°C. The typical (darkest) night-sky brightness in the J, H, and Ks-band are 15.95 mag (16.95 mag)...

Aberrations of the Human Eye in Visible and Near Infrared Illumination

Llorente, Lourdes; Díaz-Santana, Luis; Lara-Saucedo, David; Marcos, Susana
Fonte: American Academy of Optometry; Lippincott Williams & Wilkins Publicador: American Academy of Optometry; Lippincott Williams & Wilkins
Tipo: Artículo Formato: 1383643 bytes; application/pdf
ENG
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10 pages, 8 figures.-- PMID: 12553541 [PubMed].; [Purpose] In most current aberrometers, near infrared light is used to measure ocular aberrations, whereas in some applications, optical aberration data in the visible range are required. We compared optical aberration measurements using infrared (787 nm) and visible light (543 nm) in a heterogeneous group of subjects to assess whether aberrations are similar in both wavelengths and to estimate experimentally the ocular chromatic focus shift.; [Methods] Ocular aberrations were measured in near infrared and visible light using two different laboratory-developed systems: laser ray tracing (LRT) and Shack-Hartmann. Measurements were conducted on 36 eyes (25 and 11 eyes, respectively), within a wide range of ages (20 to 71 years), refractive errors (-6.00 to +16.50), and optical quality (root mean square wavefront error, excluding defocus, from 0.40 to 9.89 μm). In both systems, wave aberrations were computed from the ray aberrations by modal fitting to a Zernike polynomial base (up to seventh order in laser ray tracing and sixth order in Shack-Hartmann). We compared the Zernike coefficients and the root mean square wavefront error corresponding to different terms between infrared and green illumination.; [Results] A Student's t-test performed on the Zernike coefficients indicates that defocus was significantly different in all of the subjects but one. Average focus shift found between 787 nm and 543 nm was 0.72 D. A very small percentage of the remaining coefficients was found to be significantly different: 4.7% of the 825 coefficients (25 eyes with 33 terms) for laser ray tracing and 18.2% of the 275 coefficients (11 eyes with 25 terms) for Shack-Hartmann. Astigmatism was statistically different in 8.3% of the eyes...

Organic/Inorganic Hybrid Nanocomposite Infrared Photodetection by Intraband Absorption

Lantz, Kevin Richard
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011
Relevância na Pesquisa
36.5%

The ability to detect infrared radiation is vital for a host of applications that include optical communication, medical diagnosis, thermal imaging, atmospheric monitoring, and space science. The need to actively cool infrared photon detectors increases their operation cost and weight, and the focus of much recent research has been to limit the dark current and create room-temperature infrared photodetectors appropriate for mid-to-long-wave infrared detection. Quantum dot infrared photodetectors (QDIPs) provide electron quantum confinement in three dimensions and have been shown to demonstrate high temperature operation (T>150 K) due to lower dark currents. However, these inorganic devices have not achieved sensitivity comparable to state-of-the-art photon detectors, due in large part to the inability to control the uniformity (size and shape) of QDs during strained-layer epitaxy.

The purpose of this dissertation research was to investigate the feasibility of room-temperature infrared photodetection that could overcome the shortfalls of QDIPs by using chemically synthesized inorganic colloidal quantum dots (CQDs). CQDs are coated with organic molecules known as surface ligands that prevent the agglomeration of dots while in solution. When CQDs are suspended in a semiconducting organic polymer...

Modeling the infrared emission from Cygnus A

Privon, George C.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.44%
The Spitzer Space Telescope provides a unique view of the Universe at infrared wavelengths. Improved sensitivity and angular resolution over previous missions enable detailed studies of astrophysical objects, both in imaging and spectroscopic modes. Spitzer observations of active galactic nuclei can help shed light on the physical conditions of the central regions of these active galaxies. The nearby radio galaxy Cygnus A is one of the most luminous radio sources in the local Universe. In addition to the high radio power, it is also very luminous in the infrared. New Spitzer spectroscopy and photometry of Cygnus A is combined with data from the literature at radio and sub-mm wavelengths. The resulting complication is modeled with a combination of: a synchrotron emitting jet, a burst of star formation, and emission from an AGN torus. The infrared emission in Cygnus A shows contributions from all three processes and the models are able to reproduce the observed emission over almost 5 dex in frequency. The bolometric AGN luminosity is found to be ~10^45 erg s^-1, with a clumpy torus size o ~7 pc. Evidence is seen for a break in the synchrotron spectrum in the mid-infrared. The relevant component of the infrared emission suggests Cygnus A has a star formation rate of ~20 M_Sun yr^-1. Even in the absence of the AGN...

Tracking of various targets in the infrared and issues encountered

Ausfeld, Kyle
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.42%
The use of a computer to track objects has been a subject of interest for a few decades. The applications these algorithms may be applied to span a large number of fields; anything from homeland security to the study of animal behavior. In particular, visible tracking has been around the longest and has the largest library of algorithms available. Algorithms such as Mean Shift have become a standard for testing algorithms against. However, algorithms such as Mean Shift may work well for visible video data, infrared video data presents some issues beyond many visible algorithms. Infrared video gives certain advantages over visible, such as day/night tracking and camouflage detection. However, it also presents several issues as well. The detectors are more easily saturated, causing a temporary loss of data, as well as the drastic change in object appearance. These issues do not override the utility of infrared video being used for tracking purposes. This paper will go through some of the various applications of tracking, as well as the necessity of algorithm development in the infrared field. A couple algorithm metrics are also considered for a new basis for the testing of algorithms, as well as the introduction of a tracking algorithm testing platform.

Infrared symbolic scene comparator

Servoss, Thomas G.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.45%
Infrared image analysis has become a very popular subject of study. Situations as recent as the Gulf War have proved the advantages, and therefore the need, of having not only the proper imaging equipment but the training and expertise to use that equipment. To date, there are few tools that analysts can use to educate themselves and the operators of the state-of-the-art imaging equipment. There are even fewer tools that provide the flexibility to control nearly every aspect of infrared imaging phenomena. Several pre-existing and a few new remote sensing sub-systems have been combined to create an extremely user-friendly infrared imaging analysis package that can be used to educate people about infrared imaging phenomena or as a direct analysis tool to assist analysts in distinguishing between infrared phenomena in actual imagery.

Design and development of a 2-color infrared emitter array system

Rehrig, Robert
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
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Fouad E. Kiamilev; Infrared (IR) detectors have a wide array of uses because they can detect what our eyes cannot. We use IR information in astronomy for detecting hidden objects, wireless communication, weather forecasting, and much more. The military also uses infrared detectors for night vision, targeting, and even object tracking. Infrared is popular for object detection because most objects produce thermal frequencies in the IR range. That means with an infrared detector it is easy to observe and characterize an object based on the heat it produces. Unfortunately, these systems are not always easy to test. The best way to find out if the infrared detector is working is by testing it in the field, which can be expensive and hard to do. Fortunately, there is another way to test these systems that is much safer and more reasonable. It is possible to create an emulation environment so that the sensor can react as if it is in a live situation. This requires an array of IR pixels to reproduce previously observed heat signatures and a projection system to broadcast the array in order for the infrared detector to experience the output as if it were a real event. Previous work has included creating a 512x512 array of super-latticed LEDs (SLEDS) with one color...

Near-infrared and Brg observations of post-AGB stars

van de Steene, Griet; van Hoof, Peter A M; Wood, Peter R
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
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In this article we report further investigations of the IRAS selected sample of Planetary Nebula (PN) candidates that was presented in Van de Steene & Pottasch (1993). About 20% of the candidates in that sample have been detected in the radio and/or Ha and later confirmed as PNe. Here we investigate the infrared properties of the IRAS sources not confirmed as PNe. We observed 28 objects in the N-band of which 20 were detected and 5 were resolved, despite adverse weather conditions. We obtained medium resolution Brγ spectra and we took high resolution JHKL images of these 20 objects. We critically assessed the identification of the IRAS counterpart in the images and compared our identification with others in the literature. High spatial resolution and a telescope with very accurate pointing are crucial for correct identification of the IRAS counterparts in these crowded fields. Of sixteen positively identified objects, seven show Brγ in absorption. The absorption lines are very narrow in six objects, indicating a low surface gravity. Another six objects show Brγ in emission. Two of these also show photospheric absorption lines. All emission line sources have a strong underlying continuum, unlike normal PNe. In another three objects...