Дисертації з теми "Optical and near-Infrared"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Optical and near-Infrared.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Optical and near-Infrared".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Houston, Jessica Perea. "Near infrared optical lymphography for cancer diagnostics." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4807.
Анотація:
A new molecular imaging modality has been developed to detect and locate positive axillary and sentinel lymph nodes non-invasively in breast cancer patients undergoing lymphoscintigraphy. The modality is based on fluorescent photon detection to locate the presence of indocyanine green (ICG) in the lymph subsequent to peritumoral injection of ICG into the breast. The imaging system consists of a gain-modulated intensified charge-coupled device (ICCD) camera, which captures low-intensity, near-infrared, and frequency-modulated photons. A four-fold âÂÂoptical lymphographyâ study was conducted to (1) examine fluorescence depth penetration and ICCD system accuracy at clinically relevant depths, (2) compare image quality of the ICCD system vs. conventional gamma imaging, (3) measure ICG pharmacokinetics in vivo, and (4) develop a clinical protocol while examining pre-clinical factors such as the outcome of combining ICG with sulfur colloids used in lymphoscintigraphy. The frequency-domain ICCD system was found to precisely detect modulation amplitude, IAC, and phase, ø, at depths up to 9 cm and with IAC accuracy less than 20% and ø less than 2ú using an 80-mW laser incident on phantoms having ranging tissue optical properties. Significant differences in the mean depth of penetration owing to 0.62-ns lifetime and 100-MHz frequency increases were detected. An in vivo optical vs. nuclear image quality comparison demonstrated statistically similar (ñ=0.05) target-to-background ratios for optical (1.4+/-0.3) and nuclear (1.5+/-0.2). Alternatively, resulting image signal-to-noise ratios (SNR) from the ICCD system were greater than that achieved with a conventional gamma camera (pvalue<<0.01). Analysis of SNR versus contrast showed greater sensitivity of optical over nuclear imaging for subcutaneous tumors. In vivo and rapid detection of ICG in the blood-stream of nude mice was accomplished with a home-built avalanche photodiode dynamic fluorescence measurement system. Intensity data upon i.v. injection were regressed with a pharmacokinetic model describing the partitioning of ICG from the blood to the surrounding tissues. ICG blood-clearance was detected approximately 15 min after injection. Lastly, a human subject protocol was written, practiced, and federally approved for the application of optical lymphography. Furthermore, ICG was unaffected when mixed with sulfur colloids thus supporting the feasibility for combining fluorescence imaging with lymphoscintigraphy in breast cancer patients.
2
Lan, Zhaojue. "Spectral tunable organic near-infrared photodetectors." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/771.
Анотація:
Filter-free spectral tunable photodetectors (PDs) are critical for a plethora of applications in imaging, indoor light fidelity (Li-Fi), and light communications. The present band-selective light detection is realized by incorporating different optical filters with broadband inorganic semiconductor-based PDs. However, the use of the optical filters reduces the overall performance of these PDs and is not appliable in the emerging flexible and wearable applications. The rapid advancement of the organic semiconductors offers an exciting opportunity for the development of high-performance filter-free spectral tunable organic photodetectors (OPDs). The development of OPDs has attracted tremendous interests because of the tailored optoelectronic properties of the π-conjugated organic semiconductors and the solution fabrication process of the OPDs. Apart from the rapid progresses made in improving the responsivity and detectivity of OPDs, the spectral properties of OPDs also receive intense attention. This Ph.D. research work has been focused on developing a universal strategy to achieve high-performance filter-free band-selective and spectral tunable OPDs. The correlation between the optical profile and responsivity spectrum of the novel OPDs with a bilayer photoactive layer has been investigated. It suggests that the responsivity spectrum of the OPDs can be effectively modulated by managing the optical profile in the bilayer and multilayer photoactive layer. A filter-free band-selective OPD model, comprising a bilayer shorter-wavelength light depletion layer/longer-wavelength light-absorbing layer architecture photoactive layer, has been developed. The depletion layer in the filter-free OPDs has a dual-function serving as a shorter-wavelength light-absorbing layer and a hole-transporting layer. The photodetection spectrum window of the filter-free band-selective OPDs, defined by the difference in wavelengths between the transmission cutoff of the shorter-wavelength light depletion layer and the absorption edge of the longer-wavelength light-absorbing layer, can then be tuned over the different wavelength ranges by using an appropriate combination of the shorter-wavelength light depletion layer and the longer-wavelength light-absorbing layer. A dual-mode OPD, having a trilayer visible light absorber/optical spacer/near-infrared (NIR) light absorber configuration photoactive layer, has been proposed. The dual-mode OPD exhibits electrically switchable NIR response operated under a reverse bias and visible light response operated under a forward bias. In the presence of NIR light, the trap-assisted charge-injection behavior at the organic/cathode interface in the OPDs operated under a reverse bias. The photocurrent is produced in the visible light-absorbing layer, enabled by the trap-assisted charge injection at the anode/organic interface under a forward bias. The developed filter-free band-selective OPDs and electrically switchable dual-mode OPDs provided an attractive alternative optical detection technology to the conventional panchromatic and single-mode OPDs. The spectral tunable photodetection thus demonstrated offers a promising option for new OPD applications.
3
Higgs, Tim D. "Optical and near infrared properties of massive galaxies." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/optical-and-near-infrared-properties-of-massive-galaxies(de9bfef2-67bd-45f1-bd7d-d54e08566237).html.
Анотація:
In this thesis, we present a comparison of the evolution of the massive galaxies in the 7.8Gyr since redshift z=1 to the evolution predicted from galaxy formation models. Observing the most massive galaxies in the Universe at high redshift is challenging due to their red colours, owing to both their intrinsically red Spectral Energy Distributions (SEDs) and their redshift. In Chapter 1, We produce a method using catalogue-level data to produce matched aperture photometry for the SDSS and UKIDSS surveys in order to extend the wavelength coverage of a sample of galaxies in order to improve the precision with which models can be fitted to photometric data for these high redshift galaxies. Our matched photometry has consistent colours with those of the full processing of SDSS+UKIDSS images performed by the GAMA survey, and produces magnitudes within ∼0.1 magnitudes of the GAMA photometry for all galaxies. This is reduced to within 0.04 magnitudes when all blended sources are excluded. We compute stellar masses by fitting a Maraston et al. (2009) LRG model to both our derived photometry and that of the GAMA processing, and find that our photometry’s best fit stellar masses are within ∼0.2 dex of that which comes from the GAMA photometry, demonstrating that the method is consistent with that of a full processing, and that it is possible to quickly compute matched photometry for large area surveys of complimentary wavelength coverage. This is of vital importance for upcoming surveys e.g. DES, VISTA, EUCLID etc. Fitting Stellar Population Models to galaxy photometry is a widely used technique in order to convert from observables (colours, magnitudes) to physical properties (mass, absolute magnitude, age). In spite of their widespread use, the optical and Near Infrared (NIR) properties of stellar population models are still subject to debate. Two of the most commonly used models are those of (Maraston, 2005) (M05) and (Bruzual & Charlot, 2003) (BC03), which can differ greatly in the NIR due to the M05 models’ inclusion of the TP-AGB phase, which was neglected for BC03 models. We explore the ability of these models to reproduce measured optical+NIR properties of galaxies in Chapter 3. We produce matched optical+NIR photometry for the subsample of the galaxies surveyed by Zibetti et al. (2013) (Z13) which lie within the UKIDSS imaging area in an attempt to reproduce the findings of Z13, who conclude that their optical and NIR spectroscopy is better fit by models from Bruzual & Charlot (2003) than similar models from Maraston et al (2005). We compare the observed optical+NIR Spectral Energy Distributions (SEDs) to those of BC03 and M05 models, as well as the approximate Z13 NIR fluxes. Z13 found that M05 models fitted to the optical data and extrapolated into the NIR displayed excess flux in the NIR relative to the data, and BC03 models are better at reproducing the data. However, we show that our data is consistent with both sets of models, and on average brighter in the NIR than that of Z13. We also compare the strength of spectral features in the optical to rest frame optical and optical-NIR colours, and show that our set of Composite Stellar Population (CSP) models agree well with data, with a preference for the M05 models, showing the validity of using these models on massive galaxies. A measurement of the Stellar Mass Function (SMF) of galaxies is a powerful tool in detecting evolution of the galaxy population. With a statistically complete sample of a galaxy population down to a given stellar mass, it is possible to calculate a statistically complete SMF down to this mass. Comparison of the shape of this SMF to that of a similar sample over a different redshift interval allows the evolution of galaxies over this redshift interval to be calculated, in order to determine whether these galaxies are forming stars, merging or simply passively evolving. For this purpose, in 4 compute matched SDSS+UKIDSS photometry for the AA omega KIDSS SDSS (AUS) survey. This is a 145.416 deg² area survey of Luminous Red Galaxies (LRGs) from redshift z∼0.5 to z∼1 located within Stripe 82. We fit this photometry to a Maraston et al. (2009) Luminous Red Galaxy (LRG) template to give stellar masses, and scale masses according to the magnitude difference between the matched photometry and the SDSS model photometry in order to produce “total” stellar masses. We produce a volume-weighted SMF for the survey, and find that our SMF is consistent with the Maraston et al. (2013) SMF from the BOSS survey, meaning that the most massive galaxies in the universe are evolving passively from z=1 to the present day, which is a challenge to hierarchical models of galaxy formation. Comparison of observed SMFs to those produced by galaxy formation models is a method of testing the ability of the models to reproduce the evolution displayed by the real galaxy population. This is therefore a test of the physics included within the models, with the level of agreement between the simulation and the real galaxy SMF being indicative of whether the modelling has incorporated all the processes in action in the real universe. In order to test the ability of the state of the art semi analytical models of Henriques et al. (2013) (H13 hereafter), we compare SMFs of the simulated galaxies to those of the AUS and BOSS surveys in Chapter 5. The H13 galaxies were tailored via the application of both the AUS and BOSS colour and magnitude cuts, and SMFs calculated within lightcones of the same area as the surveys in order to compare equal volumes. Our findings extend the conclusions of Maraston et al. (2013), namely that the most massive galaxies in the simulations are not sufficiently massive to agree with the observed galaxy population at this redshift. By extending this analysis to redshift z∼1, we can confirm that the discrepancy is larger at higher redshift, with the difference between the most massive galaxies in the simulations and those observed being log(ΔM/M⊙) ≃0.2 at z≃0.6–0.7, whereas going beyond this to the range z≃0.7–1 the difference becomes log(ΔM/M⊙) ≃0.25, as can be seen in Figure 5.6, which demonstrates that the simulations are failing to either form, or assemble, the mass quickly enough to reproduce the observations. Instead, the simulations continue to assemble mass through to low redshift at a higher rate than is seen in the galaxy SMF. These discrepancies may indicate that the physics of the simulations is not fully accounting for the real processes in the Universe,and that we do not yet have a model capable of reproducing the galaxy population in the real universe. Clearly semi analytical galaxy simulations need to be modified in order to reproduce the observations, before being further challenged by upcoming spectroscopic surveys of galaxies at redshifts as high as z=2 eg. eBoss, DESI.
4
Pietka-Eddleston, Magdalena. "Optical And Near Infrared Studies of Cluster Galaxies." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523662.
5
Black, Leo-Jay. "Near-infrared nano-optical elements using plasmonic nanoantennas." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/410269/.
Анотація:
In recent years Nanophotonics, the behaviour of light at the nanometer scale has gathered Significant interest with recent advances in nanotechnology. Specifically, nanoantennas can help us access the near and mid-infrared wavelength range. The drivers are that it is a very attractive spectral region for a wide variety of technology applications, such as communications, environmental sensing, biosensing, security and astronomy. This thesis covers the functionality of single plasmonic nanoantennas for polarisation control and nonlinear frequency conversion, characterised by quantitative single-particle extinction spectroscopy and nonlinear optical microscopy. It then moves on to look at the use of plasmonic resonators as coherent absorbers in a mechanically tunable cavity. Finally, it looks at the performance of antennas in surface enhanced Raman (SERS) and IR spectroscopy (SEIRS) using new experimental setups.
6
Rosvick, Joanne Marie. "Optical and near-infrared photometry of old galactic clusters." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21945.pdf.
7
Wolters, Stephen D. "Thermal infrared and optical observations of near-Earth asteroids." Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437781.
8
Richardson, Mark. "Errors in predicting snow's near-infrared optical grain size." Thesis, University of Reading, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625443.
Анотація:
Knowledge of snow's spatial distribution in terms of snow water equivalent (SWE) is important for hydrological forecasting, but current SWE products commonly disagree on regional scales. Assimilating passive microwave observations into a forecast from a physically-based snow model has been suggested to reduce or remove this disagreement, in which case the snow model must produce properties that are relevant to radiative transfer in snow. Here, the SNOWCAN model produces profiles of grain size for comparison with field measurements using contact probe spectroscopy and the impact of considering grain shape or conglomeration type (chain or cluster) is estimated. Prediction error in near-infrared optical grain size is estimated to be ±0.094 mm for all grains, or a possible best-case of ±0.083 mm if grain shape is included. The Helsinki University of Technology microwave radiative transfer model is used with the Cold Land Processes Experiment field data to make a preliminary estimate of the associated errors in simulated microwave brightness temperature difference, which is commonly used in SWE products such as Globsnow. Grain size error is associated with a ±5.1 K error and including grain shape, at best, reduces this error to ±4.5 K. Increasing stratigraphic detail by simulating more layers is an alternative method to reduce error, and layering error is found to increase linearly with snow depth. A single-layer simulation of 100 cm depth is associated with a ±8.7 K error relative to a pack described at the measurement resolution, whereas a 2-layer model is associated with a ±3.9 K error. Further work is required to determine the impact of grain: shape in the microwave regime, rather than the near infrared, but these results suggest that increased stratigraphic detail is a higher priority than including grain shape in order to improve the assimilation of passive microwave observations.
9
Lamour, Tobias Paul. "High pulse energy near-infrared ultrafast optical parametric oscillators." Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2509.
Анотація:
A source-demand in the near- and mid-IR wavelength spectrum exists for various applications such as waveguide inscription, multiphoton imaging, and nonlinear spectroscopy. All of the applications seek for higher repetitions rates for faster processing speed, better signal to noise ratios or to improve the results for applications like laser waveguide inscription. This is in contrast to the high pulse energies, required to drive the nonlinear processes involved with these applications. Available systems are either based on low-energy, high-repetition-rate optical parametric oscillators or high-energy, low-repetition-rate optical parametric amplifiers. In this thesis a sources was developed that can bridge the wide gap between these two extremes, providing sufficient energy to drive nonlinear processes, with repetition rates in the MHz domain. This was achieved by introducing three techniques previously employed for energy scaling in laser cavities. Firstly an exchange from the conventionally used Ti:sapphire pump to a commercial high power Yb:fibre laser system readily scaled the usable pump energy. This was combined with a technique known as cavity-length extension, which allows a lowering of the cavity roundtrip time offering the build-up of pulses with increased energy. In a final stage, cavity-dumping on basis of an acousto-optic modulator was introduced into the a redesigned cavity. The combination of these three techniques, novel to synchronously pumped optical parametric oscillators, enabled the extraction of record-high pulse energies and peak powers
10
Machado, Ana Cristina Moreira. "Optical and near-infrared surveys in star forming regions." Universidade Federal de Minas Gerais, 2005. http://hdl.handle.net/1843/ESCZ-6L6H6C.
Анотація:
We have observed several different star formation regions, in top quality observatories: two missions at the Kitt Peak National Observatory, in Arizona, using the 4m and the 0.9m telescopes and two other missions at the Mauna Kea observatory in Hawaii, using the 2.2m optical telescope and the 4m infrared telescope (UKIRT). We have obtained very good quality data, high resolution deep images with seeing of the order of 1 or less, combined with large field of view, with the objective to obtain as much information on each region as possible.In order to probe the more evolved optically visible young stars, we have analyzed surveys to detect H_ emission stars in two very well known star forming regions: NGC 2264 and M 42. They where obtained with a wide field Schmidt telescope associated with the best quality photographic films, providing a survey of an area of 5×5 in the sky and enough sensitivity to reach red photographic magnitudes up to 19 mag, yielding a detection of a much larger number of young stars than previously known. We provide tables with coordinates, finding charts, cross identification with other surveys and magnitudes in public catalogs. Optical narrow-band surveys to detect Herbig-Haro objects are presented as well, for the star forming regions S140 and L1551. In the latter, previous images allowed the determination of proper motion using a cross correlation technique. A modern wide
field MOSAIC CCD was used, providing a large scale view of the entire region, as well as high enough resolution (0.26/pix) to detect structure details of the knots inside the shock regions. New Herbig-Haro objects were detected. A possible alignment of the main flow axis with the magnetic field in the cloud is discussed. The same correlation technique was used to measure proper motions in the well known HH 47 jet, using even higher resolution Hubble Space Telescope images (0.1/pix) taken in two epochs. Some other known star forming regions were surveyed at optical and near-infrared wavelengths for a study of both the young sources and the Herbig-Haro objects, in an attempt to relate them and to shed more light into the understanding of the star formation processes in those areas. Two of those regions are presented in this work: the IC 1396N globule and a region called by us the Gulf of Mexico, because of its location in the dark cloud southwest of the North America Nebula. The optical images were obtained in perfect conditions in one of the best observing sites in the world (the Mauna Kea observatory in Hawaii). The surveyed regions were only a few arcminutes wide, but the resolution was good and the areas cover the main region where the star formation processes are occurring. Several new Herbig-Haro objects were found, as well as new H_ emission line stars. The near-infrared observations allowed a view of the interior of the molecular clouds, probing embedded young stars and outflows. In some cases the near-infrared observations lacked the quality necessary for building a comprehensive view of the young sources, and we could not infer physical properties for those stars. But we were able to detect some previously unknown young stars, some of them powering outflows of various types. So far we have seven different star forming regions studied using various techniques, for which we discuss differences and similarities. A few other regions were also observed and their study is planned in the near future. We conclude that the star formation process is much more complex than it was thought a few years ago, and only with the simultaneous use of different techniques applied to several star forming regions will we be able to answer the numerous questions about this process (and probably create many more questions. . . ).Algumas regiões de formação estelar com características bem diferentes foram medidas em observatórios localizados em alguns dos melhores sítios do mundo: duas missões no Kitt Peak National Observatory no Arizona, Estados Unidos, usando os telescópios de 4m e de 0,9m, e outras duas missões no observatório de Mauna Kea no Havaí, com o telescópio óptico de 2.2m e o telescópio infravermelho de 4m (UKIRT). Obtivemos dados de ótima qualidade, imagens com alta resolução, longo tempo de exposição, com seeing da ordem de 1 ou menos, aliados a grandes campos de visão, com objetivo de obter o maior número possível de informações para cada região. Para procurar por estrelas jovens, porém já mais evoluídas (opticamente visíveis), analisamos buscas feitas por estrelas com emissão em H_ em duas regiões de formação estelar bem conhecidas: NGC 2264 e M 42. As buscas foram feitas usando-se um telescópio Schmidt, com grande campo de visão, associado a filmes fotográficos da melhor qualidade, fornecendo uma pesquisa que cobre uma área de 5×5 no céu e sensibilidade suficiente para alcançar limites de magnitudes no vermelho de até 19 mag, resultando na detecção de um número superior de estrelas do que previamente conhecido. Apresentamos tabelas, cartas de identificação, correlação com levantamentos prévios e magnitudes obtidas em catálogos públicos. Apresentamos também buscas por objetos Herbig-Haro usando imagens ópticas de banda estreita, nas regiões de S140 e L1551. Nesta última, imagens obtidas anteriormente permitiram a determinação de movimentos próprios usando uma técnica de correlação cruzada. Um moderno CCD MOSAIC forneceu uma visão em grande escala de toda a região, bem como resolução (0.26/pix) para se detectar detalhes na estrutura dos nós dentro das regiões de choque. Novos objetos Herbig-Haro foram detectados. Discutimos um possível alinhamento do eixo principal dos jatos com o campo magnético da nuvem. A mesma técnica de correlação foi usada para se medir movimentos próprios no bastante conhecido HH 47, com imagens de resolução ainda maior (0.1/pix) obtidas pelo Hubble Space Telescope em duas épocas distintas. Algumas outras regiões de formação estelar foram pesquisadas em comprimentos de onda no visível e no infravermelho próximo, para um estudo tanto das fontes jovens quanto dos objetos Herbig-Haro, numa tentativa de relacioná-los e melhorar o entendimento dos processos de formação estelar nessas áreas. Duas das regiões observadas são apresentadas neste trabalho: a nuvem globular IC 1396N e uma região chamada por nós de Golfo do México, por sua localização na nuvem escura a sudoeste da Nebulosa América do Norte. As imagens ópticas foram obtidas em condições perfeitas em um dos melhores sítios de observação no mundo (o observatório de Mauna Kea, no Havaí). A região pesquisada tinha tamanho de apenas alguns minutos de arco, mas a resolução foi ótima e as áreas cobrem a região principal onde os processos de formação estão acontecendo. Muitos objetos Herbig-Haro novos foram descobertos, bem como novas estrelas com linhas de emissão em H_ As observações no infravermelho permitem uma visão do interior da nuvem molecular, detectando estrelas jovens embebidas, bem como ejeções de matéria. Em alguns casos, as observações no infravermelho não possuem a mesma qualidade, necessária para se construir uma visão compreensível das fontes jovens, e não pudemos determinar propriedades físicas para estas estrelas. Mas fomos capazes de detectar estrelas até então desconhecidas, algumas delas criando jatos de vários tipos. Até agora sete regiões diferentes foram estudadas com uso de técnicas variadas, para as quais discutimos as diferenças e similaridades. Algumas outras regiões também foram observadas e seu estudo está planejado para breve. Concluímos, através de nosso estudo, que o processo de formação estelar é bem mais complexo do que se acreditava há poucos anos, e que somente o uso de várias técnicas aplicadas a diversas regiões de formação estelar poderá responder às inúmeras questões ainda sem resposta sobre este processo (e provavelmente colocar muitas outras questões . . . ).
11
Lee, Hanshin. "Optical Alignment and Novel Instrumentation Techniques for Optical and Near-Infrared Astronomy." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504421.
12
Li, Ning. "Charge carrier manipulation for high performing near-infrared light detection." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/538.
Анотація:
Near infrared (NIR) light detection has drawn substantial attentions in a variety of applications. NIR detectors prepared by the solution processable organic semiconductors and organic-inorganic hybrid material systems have the advantages for achieving flexible, light weight and large area NIR detection devices. The aim of this research work is to study the modulation of the photo-generated charge carriers in perovskite and polymer systems for attaining high performing solution-processable NIR phototransistors (PTs) and photodiodes (PDs). In the first part, an organo-lead halide perovskite/polymer bi-layer channel PT is discussed. Compared to the performance of the polymer only PTs, the PTs with a perovskite/polymer hybrid channel exhibit a profound broadband enhancement in photoresponsivity over the light wavelength range from UV to NIR. The improved performance in the hybrid perovskite/polymer PTs is closely associated with the efficient charge separation and transfer between the perovskite and polymer functional layers in the heterojunction. With the success in developing the bi-layer perovskite/polymer PTs, the enhancement in NIR detection is further realized in PTs by incorporating a bulk heterojunction (BHJ) channel. The BHJ channel is formed by blending NIR sensitive polymer donor with three different acceptor materials for enhancing exciton dissociation and charge separation efficiency. It is shown that the use of donor/acceptor BHJ greatly facilitates the dissociation of photo generated excitons. The efficient exciton dissociation helps to boost the utilization of the photo generated excitons, and thereby improves the photoresponsivity. Although the PTs with a BHJ channel possess high photoresponsivity, the photosensitivity of these NIR PTs is still less than satisfactory. The results reveal that a higher activation energy of charge carriers is favorable for a lower carrier density in the channel. While under NIR light illumination, the mobile charge carriers, created due to the dissociation of the photo generated excitons, result in a dramatic increase in carrier density in the active channel. The increase in carrier density under NIR illumination, gives rise to a higher channel current, thereby a higher photosensitivity. A pixel-less NIR imaging device based on light up-conversion from near-infrared to green is demonstrated. A polymer donor/non-fullerene acceptor BHJ serving as the NIR sensitive unit is integrated monolithically with a perovskite-based light emitting diode (LED) unit for achieving light up-conversion from NIR to visible light. The BHJ serves as an NIR sensitive hole injection layer in the perovskite LEDs. Therefore, the efficient electroluminescence in area where NIR-induced efficient charge injection occurs in the LEDs can be displayed clearly, producing the visible light image. The photoresponsivity of perovskite based UV-Visible-NIR photodiodes (PDs) is discussed in the last part of the thesis. A periodic nano-grating hole transporting layer (HTL), formed by the nano-imprinting, is adopted for enhancing the photoresponsivity of the PDs. Theoretical simulation reveals that the periodic nano-grating HTL helps to improve light absorption in the active layer, caused by the enhanced light in-coupling effect. In the meantime, the nano-grating HTL based PDs exhibit weak angular dependency as compared to that of the planar control ones which is appealing for wide angle light detections.
13
Johnston, Ian Ronald. "Near-infrared photodetectors and optical interconnects fabricated monolithically on silicon." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241870.
14
Ikpe, Stanley A. Triplett Gregory Edward. "Atmospheric effects on near-infrared free space optical communication links." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6654.
Анотація:
Title from PDF of title page (University of Missouri--Columbia, viewed on March 10, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Gregory E. Triplett Jr. Includes bibliographical references.
15
Buchanan, Bruce Randall. "Compatability of optical-fiber measurements with near-infrared and visible analysis /." Thesis, Connect to this title online; UW restricted, 1987. http://hdl.handle.net/1773/11591.
16
Wang, Tsuei-Lian. "High-Power Optically Pumped Semiconductor Lasers for Near Infrared Wavelengths." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242398.
Анотація:
Optically pumped semiconductor lasers (OPSLs) combine features including an engineerable emission wavelength, good beam quality, and scalable output power and are desirable for a wide variety of applications. Power scaling of OPSLs requires a combination of accurate epitaxial quantum design, accurate wafer growth and good thermal management. Here a fabrication process for OPSL devices was developed to ensure efficient OPSL device cooling and minimum surface scattering. A systematic thermal analysis was performed to optimize thermal management. Strategies for optimizing power extraction were developed; including increasing the gain/micro-cavity detuning that increases the threshold but also increases the slope efficiency and the roll-over temperature, recycling the excess pump via reflection from a metalized reflector at the back of a transparent DBR, anti-reflection coating at the pump wavelength while preserving the signal micro-cavity resonance. With optimized thermal management and the strategy of using large gain/micro-cavity detuning structure, a CW output power of 103 W from a single OPSL device was achieved. 42% optical-to-optical efficiency from the net pump power was obtained from the OPSL device with the double pass pump design and 39% optical-to-optical efficiency with respect to the total pump power was obtained with the new pump anti-reflection coating. For the fundamental mode operation, over 27 W of CW output power was achieved. To our knowledge, this is the highest 1 µm TEM₀₀ mode power reported to date for an OPSL. Finally, strategies for generating high peak power are also discussed. A maximum peak power of over 270 W was achieved using 750 ns pump pulses.
17
Panthani, Matthew George. "Colloidal Nanocrystals with Near-infrared Optical Properties| Synthesis, Characterization, and Applications." Thesis, The University of Texas at Austin, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3572875.
Анотація:
Colloidal nanocrystals with optical properties in the near-infrared (NIR) are of interest for many applications such as photovoltaic (PV) energy conversion, bioimaging, and therapeutics. For PVs and other electronic devices, challenges in using colloidal nanomaterials often deal with the surfaces. Because of the high surface-to-volume ratio of small nanocrystals, surfaces and interfaces play an enhanced role in the properties of nanocrystal films and devices.
Organic ligand-capped CuInSe2 (CIS) and Cu(InXGa 1-X)Se2 (CIGS) nanocrystals were synthesized and used as the absorber layer in prototype solar cells. By fabricating devices from spray-coated CuInSe nanocrystals under ambient conditions, solar-to-electric power conversion efficiencies as high as 3.1% were achieved. Many treatments of the nanocrystal films were explored. Although some treatments increased the conductivity of the nanocrystal films, the best devices were from untreated CIS films. By modifying the reaction chemistry, quantum-confined CuInSe XS2-X (CISS) nanocrystals were produced. The potential of the CISS nanocrystals for targeted bioimaging was demonstrated via oral delivery to mice and imaging of nanocrystal fluorescence.
The size-dependent photoluminescence of Si nanocrystals was measured. Si nanocrystals supported on graphene were characterized by conventional transmission electron microscopy and spherical aberration (Cs)-corrected scanning transmission electron microscopy (STEM). Enhanced imaging contrast and resolution was achieved by using Cs-corrected STEM with a graphene support. In addition, clear imaging of defects and the organic-inorganic interface was enabled by utilizing this technique.
18
Quartel, John Conrad. "A study of near-field optical imaging using an infrared microscope." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313413.
19
Cheng, Ran. "NONINVASIVE NEAR-INFRARED DIFFUSE OPTICAL MONITORING OF CEREBRAL HEMODYNAMICS AND AUTOREGULATION." UKnowledge, 2013. http://uknowledge.uky.edu/cbme_etds/9.
Анотація:
Many cerebral diseases are associated with abnormal cerebral hemodynamics and impaired cerebral autoregulation (CA). CA is a mechanism to maintain cerebral blood flow (CBF) stable when mean arterial pressure (MAP) fluctuates. Evaluating these abnormalities requires direct measurements of cerebral hemodynamics and MAP. Several near-infrared diffuse optical instruments have been developed in our laboratory for hemodynamic measurements including near-infrared spectroscopy (NIRS), diffuse correlation spectroscopy (DCS), hybrid NIRS/DCS, and dual-wavelength DCS flow-oximeter. We utilized these noninvasive technologies to quantify CBF and cerebral oxygenation in different populations under different physiological conditions/manipulations. A commercial finger plethysmograph was used to continuously monitor MAP. For investigating the impact of obstructive sleep apnea (OSA) on cerebral hemodynamics and CA, a portable DCS device was used to monitor relative changes of CBF (rCBF) during bilateral thigh cuff occlusion. Compared to healthy controls, smaller reductions in rCBF and MAP following cuff deflation were observed in patients with OSA, which might result from the impaired vasodilation. However, dynamic CAs quantified in time-domain (defined by rCBF drop/MAP drop) were not significantly different between the two groups. We also evaluated dynamic CA in frequency-domain, i.e., to quantify the phase shifts of low frequency oscillations (LFOs) at 0.1 Hz between cerebral hemodynamics and MAP under 3 different physiological conditions (i.e., supine resting, head-up tilt (HUT), paced breathing). To capture dynamic LFOs, a hybrid NIRS/DCS device was upgraded to achieve faster sampling rate and better signal-to-noise. We determined the best hemodynamic parameters (i.e., CBF, oxygenated and total hemoglobin concentrations) among the measured variables and optimal physiological condition (HUT) for detecting LFOs in healthy subjects. Finally, a novel dual-wavelength DCS flow-oximeter was developed to monitor cerebral hemodynamics during HUT-induced vasovagal presyncope (VVS) in healthy subjects. rCBF was found to have the best sensitivity for the assessment of VVS among the measured variables and was likely the final trigger of VVS. A threshold of ~50% rCBF decline was observed which can completely separate subjects with or without presyncope, suggesting its potential role for predicting VVS. With further development and applications, NIRS/DCS techniques are expected to have significant impacts on the evaluation of cerebral hemodynamics and autoregulation.
20
Li, Hongxia. "Characteristic and sensing properties of near- and mid-Infrared optical fibres." Thesis, Heriot-Watt University, 2009. http://hdl.handle.net/10399/2305.
Анотація:
The work within this thesis investigates the characteristics and sensing properties of novel near- and mid-infrared tellurite and germanate glass fibres and their potential as sensing elements. An asymmetric splicing method for fusion-splicing tellurite and germanate glass fibres to standard silica fibre is demonstrated. The thermal and strain sensing properties of these glass fibres have been studied by analysing the properties of optical fibre Fabry-Perot cavities, which were formed when these high refractive index fibres were spliced to silica fibre, and fibre Bragg gratings. Using fibre F-P interferometer, the normalized thermal sensitivity of tellurite and germanate fibre was measured to be 10.76×10-6/°C and 15.56×10-6/°C respectively, and the normalized strain sensitivity of tellurite and germanate fibre was also measured with values of 0.676×10-6 /με and 0.817×10-6 /με respectively. These results show good agreement with measurements using fibre Bragg gratings in these fibres and are reasonably consistent with the values predicted using available published data for glasses of similar compositions. Tellurite and germanate glass fibres show potential as thermal sensing and load sensing elements compared with silica fibre. The design of an evanescent field gas sensor using tapered germanate fibre for methane gas species detection was investigated and modelled. This model shows the maximum gas cell length (sensing fibre length), detectable gas concentration range, and required gas cell length range for the expected minimum detectable gas concentration of a fibre evanescent field sensor, which gives guidance for the effective gas cell length choosen according to different minimum detectable gas concentration requirement in practise. The investigation of tellurite and germanate glass fibre characteristics and sensing properties offer guidance for their applications in sensing areas.
21
Davis, R. Wesley. "A digital communication system using near infrared radiation transmitted through the atmosphere : presented." Scholarly Commons, 1993. https://scholarlycommons.pacific.edu/uop_etds/2253.
Анотація:
A prototype communication system has been designed, built and tested. The system is a digital communication system that uses near infrared radiation transmitted through the atmosphere. The prototype system consists of two transceivers, each with associated electronics and power supplies. Each transceiver is capable of simultaneously transmitting and receiving light at a wavelength of 830 nm . The transmitter emits light in a 0.3 degree (full angle) cone through the atmosphere , while the receiver accepts light within its 0.33 degree field of view. For the purpose of alignment, each receiver also has an eyepiece and alignment reticle with a field-of-view of approximately 1.5 degrees.
The system is capable of transmitting and receiving digital data at a rate of up to 72 thousand bits per second (kbps) over a distance of 0 . 2 km on a clear day with an average transmitted power of less than 100 MW. Data is encoded for transmission using Pulse Position Modulation (PPM). The transmitting electronics include a pulse code modulation (PCM) voice digitizer, PPM modulator, and infrared emitter driver circuitry. The receiving circuitry includes a photodiode with bias supply and preamplifier, PPM automatic gain control, PPM demodulator, and PCM digital to analog converter
Finally, a model has been developed which describes system performance. The model may be used for investigating the performance of other similar systems which may need t o meet specific design criteria or restrictions.
22
Zhao, Jun. "Fast optical signal detected in the prefrontal lobe with near-infrared spectroscopy during sleep." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4237.
Анотація:
Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 11, 2007) Includes bibliographical references.
23
Samanta, Goutam Kumar. "High-power, continuous-wave optical parametric oscillators from visible to near-infrared." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/29963.
Анотація:
This thesis presents the development of a new class of high-power, continuous-wave (cw) optical parametric oscillators (OPOs) with extended tunability from visible to near-infrared (near-IR). While lasers have been in use for nearly 50 years, it is still difficult to develop laser systems that can cover many regions of the optical spectrum, from ultraviolet (UV) and visible to the near and mid-infrared wavelength range, with potential applications in the fields such as spectroscopy, remote sensing, trace gas detection, and many more.
Development of cw OPOs in singly-resonant oscillator (SRO) configurations, the focus of this thesis, is challenging due to the high threshold pump power (several watts). In addition, with visible pumping, photorefractive effect and thermal lensing effects become important issues to overcome. Therefore, the realization of practical cw SROs requires optimal cavity design, suitable nonlinear materials, and high-power laser with high spectral and spatial quality.
High-power, single-frequency, cw SROs based on 30-mm-long MgO-doped, stoichiometrically grown, periodically-poled LiTaO3 (MgO:sPPLT) have been developed. The oscillators were pumped in the green by a frequency-doubled cw diode-pumped Nd:YVO4 laser at 532 nm. With a single grating period of 7.97 µm, continuous signal and idler coverage over 848-1430 nm is obtained by temperature tuning between 52 oC and 248 oC. In a linear cavity configuration and double-pass pumping, an oscillation threshold of 2.88 W has been obtained, and single-pass idler powers in excess of 1.51 W have been generated over 1104-1430 nm for 6 W of pump power at an extraction efficiency of 25.2% and photon conversion efficiency of 56.7%.
For single-frequency performance of the cw SRO across 848-1430 nm, we have used a compact ring cavity configuration along with a frequency selecting element (etalon). Using the same MgO:sPPLT crystal, the SRO oscillation threshold of 2.84 W has been obtained, and single-pass idler powers in excess of 1.59 W have been generated over 1104-1430 nm with a maximum SRO extraction efficiency of 25.2% and pump depletions as much as 67%. The single-frequency idler output has a linewidth of ~7 MHz. Under free-running conditions and in the absence of thermal isolation, the idler power exhibits a peak-to-peak stability of 16% over 5 hours.
Although the cw SRO can provide optical radiation across 848-1430 nm, the high output power was only available over 1104-1430 nm, due to the high reflectivity of the cavity mirrors for SRO operation. Using finite output coupling of the resonant wave, we have extended the available practical output power across the entire tuning range. The cw out-coupled SRO (OC-SRO) can deliver total power of up to 3.6 W at 40% extraction efficiency with a linewidth of 3 MHz across 848-1430 nm. The signal power shows a peak-to-peak power stability <10.7% over 40 minutes in a TEM00 spatial mode with M2 <1.52. Without any active stabilization, the resonant signal exhibits a natural long-term frequency stability <75 MHz over 15 minutes and short-term frequency stability <10 MHz over 10 seconds, demonstrating the potential of the system for spectroscopic applications.
Using internal second-harmonic-generation of the resonant near-infrared signal radiation of the MgO:sPPLT cw SRO in a 5-mm-long BiB3O6 crystal, we have generated 1.27 W of cw, single-frequency blue power over a tunable range of 425-489 nm with a linewidth of 8.5 MHz and a Gaussian spatial beam profile. The blue source is frequency-stable to better than 280 MHz, limited by the resolution of the wavemeter.
We have also developed cw green sources, in a simple single-pass experimental configuration by frequency-doubling a fiber laser using MgO:sPPLT and periodically-poled KTiOPO4 (PPKTP) crystals, generating as much as 9.6 W of green radiation in TEM00 spatial beam profile (M2 <1.33) with a single-pass efficiency of 32.7% in MgO:sPPLT. This green source has also successfully been used to pump cw SROs and will be used to pump Ti:sapphire lasers.
Using this frequency-doubled green source, we have demonstrated cw OC-SRO providing a stable single-frequency output power up to 2 W across the tuning range of 855-1408 nm, with peak-to-peak power stability <11.7%, frequency-stability <10 MHz over 10 seconds, in TEM00 (M2 <1.26) spatial beam profile.Esta tesis presenta el desarrollo de una nueva clase de osciladores ópticos paramétricos (OPOs) de onda continua (cw) y alta potencia con extendida sintonización desde el visible al infrarrojo (IR) cercano. A pesar de que los láseres están en uso desde hace casi 50 años, todavía es difícil desarrollar sistemas láser que puedan cubrir muchas regiones del espectro óptico en los rangos de longitud de onda desde el ultravioleta (UV) y visible hasta el infrarrojo cercano y medio, con potenciales aplicaciones en campos como la espectroscopia, sensores remotos, detección de trazas de gases, entre muchas otras. El desarrollo de cw OPOs en configuraciones de oscilador simplemente resonante (SRO), objetivo principal de esta tesis, es un gran desafío debido al alto umbral de potencia de bombeo (varios watts). Además, cuando se emplea bombeo visible, los efectos fotorrefractivo y de lente térmica adquieren especial relevancia y son difíciles de superar. Por lo tanto, la realización de cw SROs prácticos requiere de un óptimo diseño de cavidad, adecuados materiales no lineales y láseres de alta potencia con excelente calidad tanto espectral como espacial. Se han desarrollado cw SROs de alta potencia y frecuencia única basados en cristales de LiTaO3 de 30 mm de longitud, de crecido estequiométrico, con dopado de MgO y periódicamente pulidos (MgO:sPPLT). Los osciladores fueron bombeados en el verde mediante el láser de cw Nd:YVO4 bombeado por diodos y doblado en frecuencia. Utilizando un único periodo de red de 7.97 m, se ha obtenido cobertura continua de los campos señal y pivote en el rango 848-1430 nm por sintonización de temperatura entre 52ºC y 248ºC. Empleando una configuración de cavidad lineal y bombeo de doble paso, se ha logrado un umbral de oscilación de 2.88 W y se han generado potencias superiores a 1.51 W para el campo pivote en simple paso dentro del rango 1104-1430 nm para 6 W de potencia de bombeo, eficiencia de extracción del 25.2% y eficiencia de conversión de fotón del 56.7%. Con el objetivo de operar el cw SRO en frecuencia única a través del rango 848-1430 nm, hemos utilizado una configuración compacta de cavidad en anillo junto a un elemento para la selección de frecuencia (etalon). Utilizando el mismo cristal de MgO:sPPLT, se ha obtenido un umbral de oscilación del SRO de 2.84 W y se han generado potencias superiores a 1.59 W para el campo pivote en paso único dentro del rango 1104-1430 nm con una eficiencia máxima de extracción del 25.2 % y agotamiento del bombeo tan alto como el 67%. La salida del campo pivote en frecuencia única tiene un ancho de línea de ~ 7 MHz. Bajo condiciones de sistema libre y en ausencia de aislamiento térmico, la potencia del campo pivote exhibe estabilidad de pico a pico de 16% durante 5 horas. A pesar de que el cw SRO puede proveer radiación óptica en el rango 848-1430 nm, la alta potencia de salida solo se consiguió obtener en el rango 1104-1430 nm a causa de la alta reflectividad de los espejos de la cavidad para operar en SRO. Utilizando un acoplamiento de salida finito de la onda resonante, hemos extendido la disponibilidad de prácticas potencias de salida a través de todo el rango de sintonía. El cw SRO con acoplador de salida (OC-SRO) puede entregar un apotencia total de hasta 3.6 W con una eficiencia de extracción del 40% y con un ancho de línea de 3 MHz en el rango 848-1430 nm. La potencia del campo señal muestra fluctuaciones en potencia de pico a pico <10.7% durante 40 minutos y modo espacial TEM00 con M2<1.52. En ausencia de estabilización activa, el campo señal resonante exhibe una estabilidad en frecuencia natural a largo término con fluctuaciones <75 MHz durante 15 minutos, así como a corto término con fluctuaciones<10MHz durante 10 segundos, demostrando el potencial del sistema para aplicaciones en espectroscopia. Utilizando generación interna de segundo harmónico del campo señal resonante en el rango del infrarrojo cercano del MgO:sPPLT cw SRO mediante un cristal de BiB3O6 de 5 mm de longitud, hemos logrado generar 1.27 W de potencia cw y frecuencia única en el azul dentro del rango de sintonía 425-489 nm y con un ancho de línea de 8.5 MHz y un perfil espacial del haz de tipo Gaussiano. La estabilidad en frecuencia de la fuente azul es mejor que 280 MHz, donde la limitación viene impuesta por la resolución del medidor de longitud de onda empleado. Adicionalmente, hemos desarrollado fuentes verdes en cw en una sencilla configuración experimental de único paso, mediante el doblado en frecuencia de un láser de fibra con cristales de MgO:sPPLT y KTiOPO4 pulido periódicamente (PPKTP), generando hasta 9.6 W de radiación verde en modo espacial TEM00 (M2<1.33) con una eficiencia de paso único de 32.7% en MgO:sPPLT. Esta fuente verde has sido también empleada exitosamente para bombear cw SROs y será utilizada para bombear láseres de Ti:sapphire. Mediante esta fuente verde doblada en frecuencia, hemos demostrado que el cw OC-SRO proporciona una salida estable en frecuencia única con potencia de hasta 2 W a través del rango de sintonía 855-1408 nm, con estabilidad en potencia de pico a pico <11.7%, estabilidad en frecuencia <10 MHZ durante 10 segundos y modo espacial TEM00 (M2<1.26).
24
Gurfinkel, Mikhail. "Cancer diagnostics using dynamic near-infrared optical imaging and fluorescent contrast agents." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3162.
Анотація:
A new optical imaging modality has been developed for small animal in vivo imaging of near-infrared fluorescence resulting from fluorescent contrast agents specifically targeted to molecular markers of cancer. The imaging system is comprised of an intensified charge-coupled device (ICCD) for the detection of ultra-low levels of re-emitted fluorescence following the delivery of an expanded beam of excitation light. The design of the ICCD detection system allows for both continuous wave (CW) and frequency-domain modes of operation. Since the accurate acquisition of frequency-domain photon migration (FDPM) data is important for tomographic imaging, the imaging system was also validated using experimentally obtained FDPM measurements of homogenous turbid media and diffusion theory to obtain estimates of the optical properties characteristic of the media. The experiments demonstrated that the absorption and reduced scattering coefficients are determined least accurately when relative
rel
measurements of average light intensity IDC are employed either alone or in a
rel
combination with relative modulation amplitude data IAC and/or relative phase shift data
rel
. However, when FDPM measurements of are employed either alone or in
rel
combination with IAC data, the absorption and reduced scattering coefficients may be found accurate to within 15% and 11%, respectively, of the values obtained from standard single-pixel measurements; a result that suggests that FDPM data obtained from an ICCD detection system may in fact be useful in tomographic imaging. Furthermore, intensified-detection allows for sub-second exposure times, permitting the acquisition of dynamic fluorescence images immediately following administration of the contrast agent. Experimental results demonstrate that when coupled with a suitable pharmacokinetic model describing targeted dye distribution throughout the body, dynamic fluorescence imaging may be used to discriminate spontaneous canine adenocarcinoma from normal mammary tissue. A separate experiment demonstrates that pharmacokinetic analysis of dynamic fluorescence images enables one to estimate the rate constant governing Kaposi's sarcoma tumor uptake of an integrin-targeted dye and integrin receptor turnover rate. The rate constant for uptake was calculated to be 0.16-sec-1 while the turnover rate of the integrin receptor
was estimated to occur within 24-hours.
25
Yoxall, Edward. "Applications of scattering-type scanning near-field optical microscopy in the infrared." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23637.
Анотація:
This thesis is split into two broad sections. These are defined by the various applications of scattering-type near-field optical microscopy (s-SNOM) in different parts of the electromagnetic spectrum; the near-infrared (700 - 1000nm) and the mid-infrared (6 - 10um). S-SNOM is a means of imaging surfaces at resolutions well below the diffraction limit - the level of recorded detail does not depend on the wavelength of light (as it does with traditional optical microscopy), but instead on the sharpness of a probe (usually around 10nm), meaning an image resolution approaching a thousandth of a wavelength in the mid-infrared. For the work presented in the near-infrared, the focus lies with the modelling and mapping of various plasmonic resonances supported by metallic nanostructures. These resonances have the ability to "squeeze" light into substantially sub-wavelength volumes which is useful for a variety of applications ranging from cancer treatments to molecular sensing. The mid-infrared section starts with the implementation of a pulsed quantum cascade laser (QCL) as the system's light source. This presents some instrumentation challenges as all s-SNOM imaging to date has been conducted with continuous-wave (CW) lasers. Using a pulsed laser also raises some significant signal-to-noise implications which are quantified and discussed. In terms of the experimental applications of such a setup, the first steps towards ultra-high resolution infrared chemical spectroscopy are made by studying the epithelial cells of an oesophageal biopsy. The thesis concludes with an examination of the major noise sources faced by s-SNOM, and makes a number of recommendations on how their effects can be mitigated.
26
Reid, Derryck T. "Novel nonlinear techniques for femtosecond pulse generation in the visible and near-infrared." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/14885.
Анотація:
The work presented in this thesis describes the design, configuration and operation of femtosecond optical parametric oscillators based on the materials KTiOPO4 (KTP) and RbTiOAsO4 (RTA) and pumped by a self- modelocked Ti:sapphire laser. The alignment of the pump laser is detailed and thermal effects in the Ti:sapphire rod are examined in the context of a general technique which optimises modelocked performance at any pump power. A KTP-based femtosecond parametric oscillator is described which produces 400-fs-duration signal pulses at an average output power of 150 mW when operated in the absence of group-velocity dispersion- compensation. With intracavity dispersion-compensation, the oscillator produces 40-fs-duration pulses with an average power of 50 mW. Tuning is demonstrated from 1.12 - 1.25 mum in the signal wave and from 2.5 - 3.0 mum in the idler wave by changing only the pump-laser wavelength. Using a novel idler-feedback arrangement, reductions in the oscillation threshold and increases in the signal output power of 10 % are described. Soliton generation in the oscillator is achieved when the net cavity dispersion is positive and results show good agreement with theory. An oscillator using RTA is demonstrated which achieves conversion efficiencies exceeding 30 % and has an operating threshold of only 50 mW. Average signal powers of 100 mW and 185 mW are extracted from the oscillators with and without dispersion-compensation respectively. The corresponding pulse durations are 67 fs and 980 fs and tunability in the signal and idler waves from 1.23 - 1.34 mum and 2.10 - 2.43 mum is demonstrated. Visible output from 620 - 660 nm is obtained by intracavity- doubling and powers of up to 170 mW are measured. These results suggest that RTA has a higher nonlinear coefficient than KTP.
27
Norouzi, Neil. "Synthesis and application of novel near infrared cyanine dyes and optical imaging agents." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/10002.
Анотація:
The use of fluorescent imaging probes for the real time detection of cellular malfunctions, such as enzyme over expression has shown promise. Fluorescent dyes with absorption and emission values below 600 nm are limited in their in vivo applications due to high background auto-fluorescence and low resolution images. Employing near infrared (NIR) fluorophores such as cyanine dyes can overcome this disadvantage. Cyanine dyes can be synthesised using solution or solid-phase techniques with the use of solution phase chemistry allowing for larger scale and higher yielding reactions. Utilising a selection of functional groups and varying polymethine chain lengths a cyanine dye library with tuneable absorption and emission wavelengths was synthesised. This thesis gives the first detailed examples of how modifications on heptamethine cyanine dyes alter their cellular uptake and cellular toxicity. Furthermore, a NIR fluorescent microsphere is reported as well as NIR functionalised microspheres with the ability to be tracked within cells. Additional lines of work involved the synthesis of a fluorescent sensor for the visualisation of bacteria. Aminopeptidases are present within the peptidoglycan cell wall of Gram negative bacteria and therefore can be targeted for real time detection of bacteria to aid in the detection of infectious diseases. A coumarin based probe is reported which detects aminopeptidase in gram negative bacteria in vitro.
28
Kilpatrick, Charles D., Jennifer E. Andrews, Nathan Smith, Peter Milne, George H. Rieke, WeiKang Zheng, and Alexei V. Filippenko. "An optical and near-infrared study of the Type Ia/IIn Supernova PS15si." OXFORD UNIV PRESS, 2016. http://hdl.handle.net/10150/622110.
Анотація:
We present optical/near-infrared spectroscopy and photometry of the supernova (SN) PS15si. This object was originally identified as a Type IIn SN, but here we argue that it should be reclassified as a Type Ia SN with narrow hydrogen lines originating from interaction with circumstellar matter (CSM; i.e. SN Ia/IIn or SN Ia-CSM). Based on deep non-detections 27 d before discovery, we infer that this SN was discovered around or slightly before optical maximum, and we estimate the approximate time that it reached R-band maximum based on comparison with other SNe Ia/IIn. In terms of spectral morphology, we find that PS15si can be matched to a range of SN Ia spectral types, although SN 1991T-like SNe Ia provides the most self-consistent match. While this spectral classification agrees with analysis of most other SNe Ia/IIn, we find that the implied CSM-interaction luminosity is too low. We infer that the similarity between PS15si and the hot, overluminous, high-ionization spectrum of SN 1991T is a consequence of a spectrum that originates in ejecta layers that are heated by ultraviolet/X-ray radiation from CSM interaction. In addition, PS15si may have rebrightened over a short time-scale in the B and V bands around 85 d after discovery, perhaps indicating that the SN ejecta are interacting with a local enhancement in CSM produced by clumps or a shell at large radii.
29
Davies, Christopher W. "Quantification of Optical Parameters Using Frequency Domain Functional Near-Infrared Spectroscopy (FD-fNIRS)." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1559369168541587.
30
Ferreiro, Teresa I. "Development and characterisation of a near-infrared femtosecond optical parametric oscillator frequency comb." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2802.
Анотація:
This thesis describes a 280 MHz MgO:PPLN-based optical parametric oscillator (OPO) synchronously pumped by a 50 fs Ti:sapphire laser to produce ultrafast pulses in the near-infrared. The OPO tuned over a wavelength range from 1450 - 1550 nm and 1624 - 1750 nm for the signal and idler respectively. The carrier-envelope-offset (CEO) frequency of the signal pulses was stabilised to a 10 MHz reference frequency without f-2f self-referencing, with an RMS phase variation of 0.56 rad over an observation time of 1 second. The relative intensity noise was measured for the CEO-stabilised OPO over an observation time of 64 seconds as 0.04%. The repetition frequency of the OPO was stabilised to 280 MHz using a frequency synthesiser at the eighth harmonic (2.24 GHz). This locking loop had an RMS phase variation of 0.98 mrad over a 1 second observation time. The CEO- and repetition frequencies were then locked simultaneously to a synthesiser referenced to a Rb-disciplined source, to generate a fully stabilised 1.5 μm frequency comb with an absolute uncertainty in comb mode position of 110 Hz. The upper limit for the fractional instability for a comb mode at 200 THz was found to be 2 x 10-11, limited by the stability of the Rb reference. A five-fold increase in comb mode spacing to 1.4 GHz was demonstrated with the stabilised frequency comb. This was achieved using a passive filter cavity, stabilised to a transmission peak via dither locking. The FWHM bandwidth of the optical spectrum for the filtered frequency comb was reduced to 8 nm, however no increase in comb linewidth was observed. An additional experiment was carried out where an external cavity diode laser was frequency-stabilised to a saturated absorption peak in Rb at 780.2 nm using dither locking, providing an optical frequency reference for future OPO frequency combs.
31
Fakhri, Maryam. "Near-infrared optical frequency comb Vernier spectroscopy in air and in a flame." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-132520.
Анотація:
A Vernier spectrometer is built with a near-infrared mode-locked Er:doped fiber laser, a Fabry-Perot cavity with finesse of 1000, a diffraction grating and a photo detector. The optical cavity provides high sensitivity in absorption detection by enhancing the interaction length of the light with molecular species contained in the cavity. Coupling an optical frequency comb to the cavity provided a broadband spectral bandwidth with high precision to measure the absorption of several molecular species simultaneously. Also, by using the optical cavity as a filter, transmission of some bunch comb lines was achieved. This comb filtering together with a simple grating and a photodiode formed the Vernier detection technique to provide very fast measurements while it kept the setup very simple and compact. The system allows to detect carbon dioxide in the air and water vapor and OH radicals in the flame in a spectrum spanning from 1550 nm to 1590 nm, approximately. The retrieved spectrum has a resolution of 9.3 GHz being acquired in 0.05 s.
32
Dorfmüller, Jens. "Implementation of an Apertureless Scanning Near-Field Optical Microscope for the Infrared Spectrum." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-50341.
33
Wang, Hao. "Near infrared autofluorescence augmentation of optical coherence tomography for diagnosis of coronary atherosclerosis." Thesis, Boston University, 2014. https://hdl.handle.net/2144/12941.
Анотація:
Thesis (Ph.D.)--Boston UniversityCoronary artery disease accounts for nearly 50% of cardiovascular disease, the leading cause of death in the United States. The progression of atherosclerotic plaque is not yet fully understood. Histopathologic analysis of cadaver coronary plaques has suggested that certain subsets of coronary lesions, the vulnerable plaques, predispose patients to myocardial infarction. Prospective identification and treatment of vulnerable plaques has emerged as an important future goal for intravascular imaging and intervention. However, no single imaging modality has been shown to be capable of definitively identifying these lesions. Optical coherence tomography is a catheter-based imaging method that rapidly acquires three-dimensional images of coronary artery wall microstructure. While OCT has been documented to be capable of visualizing morphologic features associated with vulnerable plaques, it has not been shown to identify necrotic core or other putative chemicals/molecules associated with plaque progression and rupture. One solution is to add a secondary modality to OCT which detects molecules specific to necrotic cores. While conducting bench top spectroscopy measurements, our laboratory discovered that the intensity of near-infrared autofluorescence (NIRAF) is associated with plaque types. Using benchtop spectroscopy, this dissertation research established the relationship between the NIRAF signal intensity and spectral shape and atherosclerosis, and demonstrated its potential to differentiate necrotic core plaques from other arterial lesions. In addition to these spectroscopy-disease correlations, this thesis describes research conducted to identify the chemical/molecular origin of the NIRAF signal, using histopathology, confocal microscopy, spectroscopy, and chemical synthesis. The results indicate that protein modification in necrotic core is a potential mechanism for high NIRAF in advanced plaques. To translate OCT-NIRAF clinically, this dissertation describes the design of a double clad fiber that enables catheter-based detection of both OCT and NIRAF and a safety study to demonstrate that NIRAF excitation does not damage the artery wall. A preclinical OCT-NIRAF catheter was fabricated and used to image human coronary arteries ex vivo. These data showed that vulnerable plaques can potentially be identified using intracoronary OCT-NIRAF. The sum total of results from this thesis reseatch demonstrate the feasibility of conducting OCT-NIRAF imaging in human patients for the prospective identification ofvulnerable coronary plaques.
34
Ballerini, Paola. "Effects of starspots activity on optical and near infrared observations of planetary transits." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1377.
Анотація:
In this thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being the radial velocity technique.
Stellar magnetic activity is a source of noise in the study of the transits of extra-solar planets since it induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Surface brightness inhomogeneities, such as starspots or bright faculae, on star disc have an intrinsic dependence on wavelength and thus on the stellar colours. The colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres since it produces stellar flux variations that may mimic those due to the presence of molecular or atomic species in the transmitted planetary spectra. In this thesis I focus on the effects due essentially to stellar spots present in the visible hemisphere of solar-type stars. The proposed method is a theoretical one, aiming to predict the starspot-induced effects with the use of stellar atmospheric models and I present a systematic approach to quantify the corresponding stellar flux
variations as a function of wavelength bands. Therefore I consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. Then I compare starspot-induced flux variations in these different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. My results suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps to constrain spots effects by estimating the R parameter, i.e. the ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K). Its numerical value can be used to distinguish starspot brightness dips from planetary transits in a single stellar light curve.
In addition to the perturbations in the measurement of the planetary radius, the perturbations in the transit light curve profiles due to starspots can affect the determinations of orbital parameters, i.e., the relative semi-major axis and the inclination of the planetary orbit, that are directly derived by fitting procedure of the transit light curves. These distortions in the transit light curves have a significant impact on the derivation of stellar parameters and, above all, on the stellar density thus bothering the stellar evolutionary estimates.
The results derived from the synthetic photometric analysis are presented and discussed in Ballerini et al. 2012.
35
Aydogdu, Selcuk. "Near Infrared Interference Filter Design And The Production Withion-assisted Deposition Techniques." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614092/index.pdf.
Анотація:
Near infrared region (NIR) of the electromagnetic spectrum (EM) is defined as 700nm to
1400nm wavelength interval by International Commission on Illumination(CIE). This wavelength
interval is extensively used for target acquisition, night vision, wireless communication
etc. Therefore, filtering the desired portion of EM spectra becomes a need for that kind
of applications. Interference filters are multilayer optical devices which can be designed and
produced for the desired wavelength intervals. The production of near infrared interference
filters is a process of depositing thin material layers on the suitable substrates. In this thesis, a
multilayer NIR filter will be designed for a selected wavelength interval by the use of dierent
materials. Then, transmission quality, thermal stability, dependence of the transmission
values on the incoming beam angle, performance and durability of the filter will be studied.
36
Alfeeli, Bassam. "Miniature gas sensing device based on near-infrared spectroscopy." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/35911.
Анотація:
The identification and quantification of atoms, molecules, or ions concentrations in gaseous samples are in great demand for medical, environmental, industrial, law enforcement and national security applications. These applications require in situ, high-resolution, non-destructive, sensitive, miniature, inexpensive, rapid detection, remotely accessed, real time and continuously operating chemical sensing devices. The aim of this work is to design a miniature optical sensing device that is capable of detecting and measuring chemical species, compatible with being integrated into a large variety of monitoring systems, and durable enough to be used under extreme conditions.
The miniature optical sensor has been realized by employing technologies from the optical communication industry and spectroscopic methods and techniques. Fused silica capillary tubing along with standard communication optical fibers have been utilized to make miniature gas sensor based on near-infrared spectroscopy for acetylene gas detection.
In this work, the basic principles of infrared spectroscopy are reviewed. Also, the principle of operation, fabrication, testing, and analysis of the proposed sensor are discussed in details.Master of Science
37
Boone, Marc. "High-definition optical coherence tomography: Contribution to the non-invasive near infrared optical imaging techniques of the skin." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/232235.
Анотація:
Background. The development of non-invasive imaging techniques has been stimulated by the shortcomings of histopathology. Currently the only valid diagnostic technique in dermatology is skin biopsy which remains a painful, invasive intervention for the patient. Moreover, this approach is not always convenient for monitoring and follow-up of a skin disease. Optical imaging technologies could solve these shortcomings as they are fast, precise, repeatable and painless. There are four established non-invasive skin imaging techniques used in daily practice: dermoscopy, high-frequency ultrasound, reflectance confocal microscopy (RCM) and conventional optical coherence tomography (C-OCT). In imaging there is a trade-off between resolution and penetration depth. The former permits the visualization of cells, if the resolution is at least 3 µm. The latter enables the recognition of patterns and structures in deeper layers of the skin if the penetration depth is deeper than 150 µm. New non-invasive techniques using infrared light sources have been developed recently. The technique used in this work is a high-definition optical coherence tomography (HD-OCT).Objectives. The overall aims of this thesis were the feasibility of HD-OCT to visualize in/ex vivo, in real time and in 3-D the cellular and structural morphology of the skin, secondly the assessment of the capability of this technology to measure in vivo and real time the cutaneous optical properties, and finally the determination of the contribution of this technique to the non-invasive near-infrared imaging technologies. Five specific objectives have been established: i) could cells be observed in their 3-D microenvironment in normal and diseased skin, ii) could we describe morphologic features of cells and structures in normal and diseased skin (m_HD-OCT), iii) could these morphologic features be quantified by optical property analysis (o_HD-OCT), iv) was it possible to perform accurate thickness measurements in normal and diseased skin, and finally v) what was the diagnostic potential of this technique?Methodology. HD-OCT uses a combination of parallel time-domain interferometry, high power tungsten lamp (with Gaussian filter, very low lateral coherence and ultra-high bandwidth (1300 nm +/- 100 nm)), and last but not least, full field illumination with real time focus tracking. A constant homogeneous resolution of 3 µm resolution in all three dimensions is obtained up to a depth of 570 µm. Hence, the system is capable of capturing real time full 3-D images. Moreover, the in vivo assessment of optical properties of the skin is only applicable to OCT when operating in focus-tracking mode, which is the case for HD-OCT. The means to obtain answers to the five specific questions were the comparison of en face HD-OCT images with RCM and HD-OCT cross-sectional images with histopathology and C-OCT. Results. At least 160 line pares were observed by imaging a high resolution phantom with HD-OCT. This suggested a 3 µm lateral resolution. The presence of cells such as keratinocytes, melanocytes, inflammatory cells, fibroblasts and melanophages in their 3-D cutaneous microenvironment in vivo as well as ex vivo has been demonstrated .A qualitative description of structures and patterns in normal and diseased skin could be performed by HD-OCT. Clear structural changes of the epidermis, dermo-epidermal junction, papillary dermis and reticular dermis related to intrinsic skin ageing could be observed. Lobulated structures, surrounded by stretched stromal fibers and arborizing vessels, could be demonstrated in nodular basal cell carcinoma (BCC). The o_HD-OCT of normal and diseased skin could be assessed in vivo. This approach permitted the quantitative assessment of the OCT signal attenuation profiles of normal healthy skin, actinic keratosis (AK) and squamous cell carcinoma (SCC). Differences in signal attenuation profiles could be demonstrated between these three groups. These differences were also observed between BCC subtypes. The slope of the exponential attenuation of the signal in the upper part of the epidermis was very high in benign nevi. The more malignant the lesion the lower the slope. Thickness measurements of epidermis and papillary dermis could be performed by m_HD-OCT, based on a cross-sectional images and their corresponding en face image. More accurate measurements of epidermal and papillary dermal thickness could be performed based on the optical analysis of a skin volume by o_HD-OCT. The diagnostic potential of HD-OCT in comparison with dermoscopy, RCM and C-OCT could be assessed regarding i) melanoma, ii) BCC differentiation from BCC imitators and BCC sub-differentiation and iii) SCC differentiation from AK. A much higher diagnostic potential could be demonstrated for o_HD-OCT in comparison with m_HD-OCT concerning melanoma detection. The diagnostic potential of HD-OCT to discriminate BCC from clinical BCC imitators was moderate. However, HD-OCT seemed to have high potential in sub-differentiation of BCC subtypes: i) it seemed to be the best technique to include and exclude a superficial BCC, ii) the technique appeared to be the best approach to exclude nodular BCC, and iii) HD-OCT looked to be the best technique to include an infiltrative BCC. Finally, HD-OCT has proven to be a powerful method to discriminate AK from SCC.Conclusions. HD-OCT is able to capture real time 3-D imaging with a sufficiently high optical resolution and penetration depth to allow the visualization of cells in and ex vivo in their micro-architectural context. At the same time, HD-OCT permits the recognition of patterns and structures in a sufficiently large volume of skin (1.5 mm³). HD-OCT closes therefore the gap between RCM with a high resolution but low penetration depth and C-OCT with a low resolution but high penetration depth. Moreover, HD-OCT permits, in contrast to RCM and C-OCT, the real time in vivo analysis of optical properties of the skin. HD-OCT seems to be a promising tool for early diagnosis of melanoma, BCC sub-differentiation and differentiation between SCC and AK.Future perspectives. Multicenter validation studies are needed to determine the diagnostic performance of this promising new technology, especially in other clinical settings combining both morphological and optical property analysis. This combined analysis could be a valuable method not only for diagnosis, monitoring and therapeutic guidance of dermatologic diseases but it could also be helpful in the management of non-dermatologic conditions such as diabetic micro-angiopathy, infantile cystinosis or even osteoporosis.Doctorat en Sciences médicales (Santé Publique)
info:eu-repo/semantics/nonPublished
38
Martinić, Ivana. "Novel perspectives in near-infrared optical imaging with lanthanide based molecules, macromolecules and nanomaterials." Thesis, Orléans, 2016. http://www.theses.fr/2016ORLE2033.
Анотація:
Le domaine du proche infrarouge a une importance majeure pour l'imagerie optique en raison de la faible autofluorescence des systèmes biologiques et de la diffusion limitée de la lumière permettant l’amélioration du rapport signal-sur-bruit et une pénétration plus profonde dans les tissus. Les sondes fluorescentes proche-infrarouges les plus couramment utilisées à ce jour sont les fluorophores organiques ou les nanocristaux semi-conducteurs qui sont affectés par un certain nombre d’inconvénients. Plusieurs cations lanthanide possèdent des propriétés optiques uniques comme des bandes d'émissions étroites dont les longueurs d'ondes sont très peu sensibles à l’environnement, de grandes différences d’énergie entre longueurs d’onde d’excitation et d'émission et une forte résistance au photoblanchiment. Afin de bénéficier de la luminescence des lanthanides, les faibles absorbances des cations lanthanides libres doivent être compensées par l'utilisation de groupes chromophores appropriés fonctionnant comme sensibilisateurs. On parle d’effet d’"antenne". Nous présentons dans ce travail plusieurs familles de sondes à base de lanthanides (i) de petites molécules, plus spécifiquement des complexes monométalliques constitués par la coordination de Ln³⁺ par un ligand de type TTHA-anthraquinone et des métallacrowns polymétalliques Ln³⁺/Zn²⁺ auto-assemblés; (ii) de nouveaux nanomatériaux basés sur des billes de polystyrène possédant deux types de chargements différents, à savoir (i) un complexe bimétallique d-f Cr³⁺-Ln³⁺ ainsi que (ii) des antennes dérivées d’hydroxyanthraquinone et des cations lanthanide libres; (iii) des macromolécules de type dendrimère polyamidoamine de génération 3 fonctionnalisés avec sensibilisateurs aza-BODIPY en leurs périphéries et qui encapsulent des lanthanide luminescents. Les propriétés photophysiques, la cytotoxicité et l'incorporation cellulaire ont été décrites et discutées pour chacun des types de sondes. En outre, ces sondes ont été testées en imagerie in vitro visible et/ou proche-infrarouge par des expériences de microscopie confocale et d’épifluorescence. L’ensemble des sondes décrites dans ce travail, en raison de leurs propriétés avantageuses et nouvelles, constituent des avancées majeures pour le développement de nouvelles générations d'agents d'imagerie optiqueThe near-infrared (NIR) region has a significant importance for optical imaging due to the minimal autofluorescence and reduced light scattering thus allowing for improved signal-to-noise ratio and deeper penetration through tissues. Nowadays, the most commonly used NIR-emitting fluorescent probes rely mainly on organic fluorophores or quantum dots and exhibit drawbacks. Several lanthanide(III) ions (Ln³⁺) possess unique optical properties e.g. sharp emission bands the wavelengths of which have minimal sensitivity to the microenvironment, large differences between excitation and emission wavelengths and strong resistance toward photobleaching. In order to obtain the luminescence of lanthanides, the low absorbances of the free Ln³⁺ have to be overcome by the use of appropriate chromophoric groups functioning as a sensitizing “antenna”. We present here several families of Ln³⁺-based probes: (i) small molecules, in particular monometallic complexes constituted by the TTHA-anthraquinone moiety and Ln³⁺, and polymetallic self-assembled Ln³⁺/Zn²⁺ metallacrowns; (ii) novel nanomaterials based on polystyrene beads with two different loadings, i.e. d-f bimetallic Cr³⁺- Ln³⁺+ complex and hydroxyanthraquinone antennae and Ln³⁺ ; (iii) macromolecular generation-3 polyamidoamine dendrimers functionalized with aza-BODIPY sensitizers at their periphery and encapsulating the luminescent Ln³⁺. The photophysical properties, cytotoxicity and cellular uptake were reported and discussed for each of the presented types of Ln³⁺-based probes. Moreover, these probes were successfully tested for visible and/or NIR in vitro imaging by confocal or epifluorescence microscopy experiments. Finally, the reported Ln³⁺-based probes, due to the number of advantageous properties, represent significant breakthroughs toward the developments of new generations of optical imaging agents
39
Van, der Zee Pieter. "Measurement and modelling of the optical properties of human tissue in the near infrared." Thesis, University of London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319667.
40
Kearns, Hayleigh. "Hollow gold nanoshells as unique near infrared optical materials for surface enhanced Raman scattering." Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=26531.
Анотація:
Hollow gold nanoshells (HGNs) demonstrate a tunable localised surface plasmon resonance (LSPR) from the visible to the near infrared (NIR). The NIR region of the electromagnetic spectrum is of particular interest as it provides an uncongested spectral window for optical analysis due to many molecules having reduced absorption and scattering backgrounds. In addition, the superior depth of light penetration and reduced interference which is observed in this region when compared to the visible region means that there is a great need to design SERS nanotags which can provide a unique vibrational fingerprint in this uncongested optical region. The research described herein demonstrates three ways in which red-shifted nanotags can be engineered to provide effective SERS signals in the NIR region. Firstly, NIR active HGNs were synthesised and encapsulated with seven non-resonant commercial Raman reporters and shown to provide effective SERS when excited with a 1064 nm laser. The nanotags were then tested using a 1280 nm laser excitation however; they were unsuccessful at providing a SERS spectrum. Through a successful collaboration with Professor Michael Detty's group (University at Buffalo) newly synthesised Raman reporters where obtained. The chalcogenopyrylium dyes were resonant from 650 to 1000 nm and when combined with HGNs, demonstrated an unprecedented performance. Through the design of these nanotags, extreme red-shifted SERS was achieved with laser excitations from 1064 nm up to 1550 nm and detection limits in the picomolar to femtomolar range where obtained. Finally, this research demonstrates that when hollow gold nanotags are functionalised with a thermopolymer such as poly(N-isopropylacrylamide), the LSPR can be shifted into the NIR region and laser induced plasmonic heating of the nanoshells can be used to turn on and off the SERS enhancement. Overall, the development of NIR active nanotags could provide the basis for future advancements in bio-chemical, medical and optical applications.
41
Hesselbach, Erica N. "Probing the Circumstellar Disks of Classical Be Stars with Optical and Near-Infrared Spectroscopy." Connect to full text in OhioLINK ETD Center, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1249334993.
Анотація:
Dissertation (Ph.D.)--University of Toledo, 2009.Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics ." Bibliography: leaves 71-74.
42
Nagel, Evangelos [Verfasser], and Jürgen [Akademischer Betreuer] Schmitt. "High precision optical and near-infrared velocimetry with CARMENES / Evangelos Nagel ; Betreuer: Jürgen Schmitt." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/121218095X/34.
43
STEIJN, KIRK WILLIAM. "COUPLING AND PROPAGATION OF SURFACE PLASMONS IN THE FAR-INFRARED (NEAR-MILLIMETER WAVES, SUB-MILLIMETER WAVES)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183973.
Анотація:
This work describes a study of the propagation properties of a modified surface plasmon mode, and of the coupling properties of that mode using a grating coupler. The surface plasmon, a polariton involving coupling of electromagnetic waves to the plasma oscillations of a metal, is modified by the application of a dielectric overlayer to the interface between the metal and air. In the far infrared region of the electromagnetic spectrum, the overlayer causes dramatic changes in several properties of the mode, which can be verified by measuring the propagation length of the mode. Measurements at a wavelength of 118.8 μm of the propagation length as a function of the thickness of a polycrystalline silicon overlayer on silver showed that the mode has the expected properties. They also indicated that the Drude model of the dielectric function of the silver is valid at 118.8 μm, even when using established Drude parameters, which are based on measurements in the visible and near infrared region of the electromagnetic spectrum. The coupling study measured the fundamental coupling parameters, also at a wavelength of 118.8 μm, for coupling via a grating between free-space waves and the surface plasmon, and measured the effect of the overlayer on these parameters. Efficient coupling was achieved, but a theoretical treatment of the coupling system proved to be beyond the scope of first-order grating-coupler theory. This was true despite the fact that the grating amplitude was a small fraction of the wavelength, a common criterion for the application of such a theory. Several possible reasons for the breakdown of the theory were considered, but definite answers require additional experiments. The most prominent possibilities are the shape factor, and the depth of the grating compared to the penetration depth of the fields into the metal. Though not all the data is completely explained, the studies herein demonstrate that the overlayer eliminates many of the deficiencies which limit the generation and control of far-infrared surface plasmons.
44
Parsa, Shahrzad. "High-power fiber-laser-pumped picosecond nonlinear optical sources from the near- to mid-infrared." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/620786.
Анотація:
Ultrafast picosecond coherent sources in the near-to-mid-infrared (IR) spectral range are of great interest for a variety of applications such as pump-probe spectroscopy, remote sensing, photobiology and novel upconversion imaging techniques. Nonlinear optics, and in particular nonlinear frequency conversion techniques, offer an efficient and effective approach towards the realization of sources emitting such radiation, as nowadays, nonlinear frequency conversion technologies are recognised to be viable and reliable sources of laser radiation with broad wavelength tunability and power scalability, without the need of cryogenic cooling.
In this thesis, we have demonstrated high-power, high-repetition-rate picosecond sources based on nonlinear frequency conversion processes through optical parametric oscillators (OPOs) and difference-frequency-generation (DFG), in order to cover the near- to mid-IR wavelength region.
We have developed a stable, high-repetition-rate picosecond rapidly tunable OPO based on fan-out designed grating periods in PPKTP nonlinear crystal. The OPO is synchronously pumped by a mode-locked frequency-doubled Yb-fiber laser in the green at 532 nm, and can provide stable and high-power radiation which is rapidly tunable from 749-962 nm in the signal and from 1189-1838 nm in the idler, at room temperature.
Further, we have demonstrated what we believe to be the first tunable high-repetition-rate picosecond source based on OP-GaP crystal in the mid-IR. Using a single-pass DFG between a mode-locked Yb-fiber laser at 1064 nm and the tunable output from a picosecond MgO:sPPLT OPO synchronously pumped by the same laser, the source generated continuous tunable radiation across 3040-3132 nm in the mid-IR at the repetition rate of ~80 MHz, in good beam quality.
Additionally, we have also presented the first high-power, high-beam-quality, idler-resonant picosecond OPO based on a multi-grating MgO:PPLN crystal tunable across 2100-4000 nm in the mid-IR. The OPO provided as much as 3.5 W of mid-IR radiation with M2 values to be better than 1.8 in both horizontal and vertical directionsLas fuentes coherentes de picosegundos ultrarrápidos en el rango espectral de infrarrojo cercano a infrarrojo medio (IR) son de gran interés para una amplia variedad de aplicaciones tales como pump-probe espectroscopia, la teledetección, la fotobiología y las nuevas técnicas de upconversion imaging. La óptica no lineal, y en particular las técnicas de conversión de frecuencia no lineal, ofrecen un enfoque eficiente y eficaz para la realización de fuentes que emiten tales radiaciones, ya que hoy en día, las fuentes basadas en la conversión de frecuencia no lineal son fuentes viables y fiables de emisión de radiaciones láser con amplia sintonía de longitud de onda y escalabilidad de potencia, sin necesidad de refrigeración criogénica. En esta tesis, hemos demostrado fuentes de picosegundos de alta potencia y alta tasa de repetición basadas en procesos de conversión de frecuencia no lineales a través de osciladores ópticos paramétricos (OPO) y generación de frecuencias de diferencia (DFG) para cubrir la región de longitud de onda de IR cercano a IR medio del espectro electromagnético. Hemos desarrollado una fuente de picosegundos estable, de alta tasa de repetición, rápidamente sintonizable, basado en un cristal PPKTP con períodos de rejilla diseñados en forma de abanico. El OPO, es bombeado sincrónicamente por un mode-locked láser de fibra de Yb, doblado en frecuencia para generar verde a 532 nm, que proporciona radiación estable y de alta potencia rápidamente sintonizable de 749-962 nm en el signal y de 1189-1838 nm en el idler, a temperatura ambiente. Además, hemos demostrado lo que creemos que es la primera fuente de picosegundos sintonizable con alta tasa de repetición basada en el cristal OP-GaP en el IR medio. Usando una DFG de un solo paso entre un mode-locked láser de fibra de Yb a 1064 nm y la salida ajustable de un OPO de picosegundo basado en un cristal de MgO:sPPLT bombeado sincrónicamente por el mismo láser, la fuente generó radiación sintonizable de 3040-3132 nm en el medio-IR a la velocidad de repetición de ~80 MHz, con buena calidad de haz. Además, también presentamos el primer OPO de picosegundos de alta potencia y buena calidad de haz, con resonancia del idler, basado en un cristal MgO:PPLN de rejilla múltiple sintonizable a lo largo de 2100-4000 nm en el IR medio. El OPO proporcionó hasta 3.5 W de radiación de IR medio con valores de M2 mejores que 1.8 tanto en dirección horizontal como vertical
45
Buset, Jonathan. "Near infrared optical manipulation of a GaAs/AlGaAs quantum well in the quantum hall regime." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21957.
Анотація:
Using electronic spin rather than charge to replace existing microelectronic systems has been a well studied area of research in the last ten years. More recently, research has focused on using the nuclear spin of GaAs rather than the electron spin. This work has demonstrated that GaAs nuclear spins have many desirable properties and show great potential as quantum information carriers. The challenge in the implementation of nuclear spins lies in the ability to control and retrieve the information that they carry. One proposed method is to dynamically polarize the GaAs nuclear spins using circularly polarized photoexcitation. If successful, this could open new horizons in the field of quantum information processing. This thesis details an investigation into the use of polarized light to manipulate the properties of a GaAs/AlGaAs quantum well sample. The three main topics explored in this thesis are: 1) the design and operation of a polarization controller that is able to shine well-defined and tunable polarized light on to a sample contained in a cryogenic environment at T = 0.27K; 2) the manipulation of the nuclear polarization in GaAs using low power laser light with tunable polarization; and 3) a preliminary investigation into illuminating a quantum Hall sample with unfocused, low power laser light and the transport properties modifications that occur in the quantum Hall regime.L'utilisation du spin electronique plutot que la charge electronique pour remplacer les systemes microelectroniques a ete un domaine bien etudie de la recherche au cours des dix dernieres annees. Plus recemment, la recherche a porte sur l'utilisation du spin nucleaire du GaAs plutot que le spin electronique. Ce travail a demontre que les spins nucleaires du GaAs ont de nombreuses proprietes desirables et montrent un grand potentiel en tant que transporteurs de l'information quantique. Le defi dans la mise en oeuvre des spins nucleaires reside dans la capacite de controler et de recuperer les informations qu'elles transportent. Une methode proposee consiste a polariser dynamiquement les spins nucleaires du GaAs en utilisant la photoexcitation polarisee circulairement. Ceci pourrait ouvrir de nouveaux horizons dans le domaine du traitement de l'information quantique. Cette these expose en details une enquete sur l'utilisation de la lumiere polarisee pour manipuler les proprietes d'un echantillon puit quantique de GaAs/AlGaAs. Les trois principaux sujets abordes dans cette these sont les suivants: 1) la conception et le fonctionnement d'un controleur de polarisation qui est capable d'emettre une lumiere polarisee bien definie et ajustable sur un echantillon dans un environnement cryogenique a T = 0.27K, 2) la manipulation de la polarisation nucleaire dans le GaAs en utilisant un laser a faible puissance avec une polarisation ajustable, et 3) une enquete preliminaire sur l'illumination d'un echantillon de Hall quantique avec un laser non-focalise a faible puissance et les modifications des proprietes de transport qui se produisent dans le regime de Hall quantique.
46
Alves, Vaccari Paulo Roberto. "Near infrared and visible optical properties in electrochromic crystalline tungsten oxide thin films on ITO." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229122.
Анотація:
In this project I have studied the optical properties of electrochromic crystalline tungsten oxide, WO3. The practical application could be for a window for desalination of sea water which requires a high absorption coefficient A(λ) for near infrared radiation (NIR), while at the same time a high transmittance T(λ) in the visible spectral range. An electrochromic (EC) material is a material that changes its optical properties when inserting or extracting ions by applying a voltage. The WO3 was prepared on a glass substrate coated by a transparent electrical conductor. The conductor used is tin doped indium oxide. In2O3:Sn, indium-tin-oxide (ITO). The preparation of the thin films has been carried out using DC magnetron reactive sputtering. The structure of unheated tungsten oxide is amorphous and once heated it is crystalline. Li+ ions were inserted into the tungsten oxide material with electrochemical methods to create the coloring effect. The optical properties were recorded in the 330 < λ < 2500 nm wavelength range by use of a Perkin-Elmer Lambda 9 spectrophotometer. The highest reflectance R(λ), approximately 50% in NIR and absorption coefficient A(λ) = 1,5 x 105 [cm-1], were measured for the sample that had been post annealed at 500 deg C. The crystalline tungsten oxide films provides for a good switching capability in the NIR spectral range wile at the same time maintaining a high transmittance T(λ) in the visible spectrum.
47
Garcia, Soto Mariano de Jesús. "Synthesis of Gold Nanostructures with Optical Properties within the Near-Infrared Window for Biomedical Applications." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/321533.
Анотація:
The work reported in this dissertation describes the design and synthesis of different gold nanoshells with strong absorption coefficients at the near-infrared region (NIR) of the spectrum, and includes preliminary studies of their use for the photo-induced heating of pancreatic cancer cells and ex vivo tissues. As the emphasis was on gold nanoshells with maximum extinctions located at 800 nm, the methods explored for their synthesis led us to the preparation of silica-core and hollow gold nanoshells of improved stability, with maximum extinctions at or beyond the targeted within the near-infrared window. The synthesis of silica-core gold nanoshells was investigated first given its relevance as one of the pioneering methods to produce gold nanostructures with strong absorption and scattering coefficients in the visible and the near-infrared regions of the spectrum. By using a classical method of synthesis, we explored the aging of the precursor materials and the effect of using higher concentrations than the customary for the reduction of gold during the shell growth. We found that the aging for one week of the as-prepared or purified precursors, namely, the gold cluster suspensions, and the seeded silica particles, along with higher concentrations of gold in the plating solution, produced fully coated nanoshells of 120 nm in size with smooth surfaces and maximum extinctions around 800 nm. Additional work carried out to reduce the time and steps in the synthesis of silica-core gold nanoshells, led us to improve the seeding step by increasing the ionic strength of the cluster suspension, and also to explore the growth of gold on tin-seeded silica nanoparticles. The synthesis of hollow gold nanoshells (HGS) of with maximum extinctions at the NIR via the galvanic replacement of silver nanoparticles for gold in solution was explored next. A first method explored led us to obtain HGS with maximum extinctions between 650 and 800 nm and sizes between 30 and 80 nm from silver nanoparticles, which were grown by the addition of silver nitrate and a mild reducer. We developed a second method that led us to obtain HGS with maximum extinctions between 750 and 950 nm by adjusting the pH of the precursor solution of the silver particles without much effort or additional steps. The last part of this work consisted in demonstrating the photo-induced heating of two biological systems containing HGS. Photothermal therapy studies of immobilized PANC1 pancreas cancer cells in well-plates were carried out with functionalized HGS. We found that cells exposed to HGS remained viable after incubation. Moreover, the cells incubated with HGS modified with mercaptoundecanoic acid and folic acid turned non-viable after being irradiated with a laser at 800 nm. The other study consisted in the laser-induced heating between 750 and 1000 nm of ex vivo tissues of chicken and pork with nanoshells injected. In comparison with non-injected tissues, it was found that the temperature at the irradiated areas with HGS increased more than 10 °C. Moreover, the extent of the heated area was broader when the laser was used at wavelengths beyond 900 nm, suggesting that the heating was due to the radiation absorbed and transformed into heat primarily by the HGS and at a lesser extent by the water in the tissue.
48
Akin, Ryan E. "Minimally invasive assessment of lymphatic pumping pressure using near infrared imaging." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47536.
Анотація:
Although the major functions of the lymphatic system are fairly well defined, its vasculature has yet to be well characterized in comparison to its blood vasculature counterpart. Recent advances in optical imaging techniques have allowed for more detailed and quantitative evaluations of lymph flow dynamics and mechanism. A rat tail is often used for investigations of lymph flow because of the simple geometry, superficial nature, and disease progression models of its collecting lymphatic vessels. In this study, a pressure cuff system was fabricated and coupled with an existing functional near infrared (NIR) imaging system to measure the overall pumping pressure of the lymphatic vessels of a rat tail. In addition to adapting the system for use on rodents, previous systems used for measuring lymphatic pumping pressure in humans were improved upon in several ways. The system defined here utilizes closed-loop feedback control of pressure application at smaller, more precise intervals. Using this device, a significant difference in lymphatic vessel pumping pressure was detected between a control case and a treatment case in which a vasoactive substance with a nitric oxide donor (GTNO ointment) was applied to the tail. Although it is known that nitric oxide plays a crucial physiologic role in propagation of flow through lymphatic vessels, this study has quantified its significant pharmacological reduction of pumping pressure for the first time.
49
Bazkir, Ozcan. "Realization Of Detector Based Spectral Responsivity Scale From Ultraviolet To Near Infrared Regions Of Electromagnetic Spectrum." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605148/index.pdf.
Анотація:
Realization of spectral responsivity scale was studied in three stages. Firstly, absolute optical power measurements using Electrical Substitution Cryogenic Radiometer (ESCR) was studied. The absolute measurements were done at discrete laser wavelengths of tunable Ar+ (488 nm and 514.5 nm), Nd:YAG (532 nm) and fixed He-Ne (632.8 nm) laser sources. To increase measurement accuracy the method used for the stabilization of laser beams, transmittance measurements of optical windows, and minimization of scattered beams were discussed.
Secondly, realization of absolute responsivity scale between 350- 850 nm ranges was studied. The scale based on reflection type trap detectors consisting of three silicon photodiodes. Various measurement systems were established in order to make optical characterization of trap detectors like non-linearity, surface non-homogeneity, polarization dependency, reflectance, and internal quantum efficiency. The absolute responsivity was linked to the absolute optical power by measuring the current response of trap detectors to the absolute power measured by ESCR system at laser wavelengths. Using models for the trap detector&rsquos, reflectance and internal quantum efficiency the scale between 350- 850 nm ranges was realized with an uncertainty of 0.05 %. Finally, the spectral responsivity scale in ultraviolet (UV) and near-infrared (NIR) regions was realized using Electrically Calibrated Pyroelectric Radiometer (ECPR). Optically characterizing the spatial non-uniformity of pyroelectric detector and its surface reflectance, the spectral responsivity scale was established with uncertainties ±
0.5-1.0 % between 250 nm and 350 nm and ±
0.5-1.5 % between 850 and 2500 nm.
50
Lim, Jinkang. "All-fiber frequency comb employing a single walled carbon nanotube saturable absorber for optical frequency metrology in near infrared." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/7423.
Анотація:
Doctor of PhilosophyDepartment of Physics
Brian R. Washburn
Optical frequency combs produced by mode-locked fiber lasers are useful tools for high precision frequency metrology and molecular spectroscopy in a robust and portable format. We have specifically investigated erbium doped fiber mode-locked lasers that use single-walled carbon nanotubes as a saturable absorber. We have, for the first time, developed and phase- stabilized a carbon nanotube fiber laser (CNFL) frequency comb. The carbon nanotube saturable absorber, which was fabricated using an optically driven deposition method, permits a high repetition frequency (>150 MHz) since an optical nonlinearity of fibers is not used for mode-locking. The CNFL comb combined with a parabolic pulse erbium doped fiber amplifier (EDFA) has shown a compact, robust, and cost-effective supercontinuum source. The amplified pulse from the parabolic pulse EDFA was compressed with a hollow-core photonic bandgap fiber, which produced a wave-breaking-free pulse with an all-fiber set-up. The stabilized comb has demonstrated a fractional instability of 1.2 ×10[superscript]-11 at 1 sec averaging time, the reference-limited instability. We have performed optical frequency metrology with the CNFL comb and have measured an optical frequency, P(13) which is a molecular overtone transition of C2H2. The measured frequency has shown a good agreement with the known value within an uncertainty of 10 kHz. In order to extend the application of the CNFL comb such as multi-heterodyne dual comb spectroscopy, we have investigated the noise of the CNFL comb and particularly, the broad carrier envelope offset frequency (f[subscript]0) linewidth of the CNFL comb. The primary noise source is shown to be white amplitude noise on the oscillator pump laser combined with the sensitivity of the mode-locked laser to pump power fluctuations. The control bandwidth of f[subscipt]0 was limited by the response dynamics of the CNFL comb. The significant reduction of comb noise has been observed by implementing a phase-lead compensation to extend control bandwidth of the comb and by reducing the pump relative intensity noise simultaneously. Therefore the f[subscipt]0 linewidth has been narrower from 850 kHz to 220 kHz. The integrated phase noise for the f[subscipt]0 lock is 1.6 radians from 100 Hz to 102 kHz.