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1
McRobbie, Andrew Douglas. "Novel semiconductor based light sources." Thesis, University of St Andrews, 2009. http://hdl.handle.net/10023/565.
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The research described in this thesis relates to the design, fabrication and testing of novel semiconductor-based light sources that have been designed for the generation of infra-red light. The thesis is formatted to account for two distinct components of my work, where the first part concerns sources producing coherent light by direct laser emission, notably, ultrashort-pulse quantum-dot lasers. These types of lasers continue to show considerable promise as efficient, compact sources of ultrashort pulses with durations of hundreds of femtoseconds, while giving rise to unique and interesting electronic properties such as low lasing thresholds through the quantum nature of their density of states. At the outset a study of the most relevant aspects of the lasing dynamics of an optically pumped quantum-dot laser is outlined. Pumping of the device with intense discrete optical pulses leads to output from multiple electronic states, each having a characteristic wavelength and temporal properties. I show that pulses produced by excited-state emission have shorter durations (24 ps) and arrive earlier in time than those due to transitions from the ground state, which themselves have durations of around 180 ps. Investigations are then made on two different mode-locked quantum-dot laser systems. One is an all-quantum-dot external-cavity laser that is mode locked using a quantum-dot SESAM device at a repetition frequency of 860 MHz with output power approaching 20 mW. This is followed by a study of a monolithic two-section quantum-dot laser that is mode locked stably in a wide temperature range of 20°C to 70°C. The excellent performance characteristics presented serve to demonstrate both the versatility of quantum-dot material as components in mode-locked laser systems and the temperature stability of such laser devices. The second part of the thesis relates to structures that are designed to take advantage of nonlinear frequency conversion in GaAs-based semiconductors. This material system possesses a nonlinear coefficient of ~170 pm/V and is transparent from around 0.9 μm through to 17 μm, making it attractive for the realisation of a new class of efficient, integrable, quasi-phase-matched, optical parametric oscillator devices. Initially, ion implantation is utilised as a vector to create a periodically-switched nonlinear ridge waveguided device. The observation is made that in the course of implantation the transmissive properties of the device are severely degraded. Unfortunately, the high losses incurred, which reached 250 dB/cm, could not be removed without also destroying the modulation in nonlinearity. During the course of this investigation, significant technological advances were made in the production of orientation-patterned GaAs structures. By recognising the elegance and potential of this new orientation-patterned (OP) methodology, a study of its implications and applicability in the context of my project is initiated.
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McRobbie, Andrew Douglas. "Novel semiconductor based light sources /." St Andrews, 2008. http://hdl.handle.net/10023/565.
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Craig, Katie. "Sweetness and light." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9477.
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1. Sweetness and Light. A novel. Judi lives in a nice, clean house with her seventeen year old stepson, who won’t talk to her in anything but monosyllables. His father, Nelson, and she are struggling to relate to each other, since they fell out over Judi’s continued desire to have a baby, despite many miscarriages. She’s forty-one. Her relationship has lost its spark, she doesn’t know how to talk to the man that she lives with anymore. To make matters worse, he is her boss too. Judi needs answers, what she discovers instead is The Secret, Rhonda Byrne’s internationally bestselling guide to shaping the world around you with the power of your mind. Judi soon discovers she’s pretty good at it. Uncanny things start to happen. A wine-do with literary pretentions leads to an unexpectedly spiritual interlude, during which Judi is led, by a cosmic vision, to discover the sinister happenings at her work place. Hope, a schizophrenic woman in their care, has been raped, and is pregnant. Worse, Judi has strong reason to suspect that her abuser is the man she has shared her life with. With The Secret as her moral compass, Judi decides to kidnap Hope and raise the baby as her own. The relationship on the brink, becomes a game of brinkmanship. As Judi struggles to build a dream-life from the wreckage of the old, the burden of past makes its weight felt. A novel of secrets, and The Secret. An exploration of cosmic ordering, and its consequences. 2. Making Light Of The Holocaust: Modelling Calvino’s concept of lightness as an appropriate literary response to the Shoah in Anne Michaels’ Fugitive Pieces. In Six Memos For The New Millenium, Italo Calvio proposes that lightness is a literary value which can act against cultural and creative paralysis. Given the ongoing cultural obligation to bear witness to the events of The Holocaust, might lightness be a necessary approach to post-holocaust literature? Calvino’s concept of lightness is deconstructed and examined in relation to the Memorial to The Murdered Jews Of Europe. The understandable critical hesitancy surrounding a light approach to the atrocities is examined, with special reference to Benigni’s La vita è bella Finally, taking Anne Michaels’ novel Fugitive Pieces as an exemplar of the lightness Calvino advocated at work in the field of holocaust literature, the case is made for the appropriateness, and potential necessity, of this approach in works that address The Holocaust, in the specific context of Michaels’ work and more generally.
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Wang, Yongchang. "Novel Approaches in Structured Light Illumination." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/116.
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Among the various approaches to 3-D imaging, structured light illumination (SLI) is widely spread. SLI employs a pair of digital projector and digital camera such that the correspondences can be found based upon the projecting and capturing of a group of designed light patterns. As an active sensing method, SLI is known for its robustness and high accuracy. In this dissertation, I study the phase shifting method (PSM), which is one of the most employed strategy in SLI. And, three novel approaches in PSM have been proposed in this dissertation. First, by regarding the design of patterns as placing points in an N-dimensional space, I take the phase measuring profilometry (PMP) as an example and propose the edge-pattern strategy which achieves maximum signal to noise ratio (SNR) for the projected patterns. Second, I develop a novel period information embedded pattern strategy for fast, reliable 3-D data acquisition and reconstruction. The proposed period coded phase shifting strategy removes the depth ambiguity associated with traditional phase shifting patterns without reducing phase accuracy or increasing the number of projected patterns. Thus, it can be employed for high accuracy realtime 3-D system. Then, I propose a hybrid approach for high quality 3-D reconstructions with only a small number of illumination patterns by maximizing the use of correspondence information from the phase, texture, and modulation data derived from multi-view, PMP-based, SLI images, without rigorously synchronizing the cameras and projectors and calibrating the device gammas. Experimental results demonstrate the advantages of the proposed novel strategies for 3-D SLI systems.
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Eftekhari, Ehsan. "Novel Nanostructures for Manipulating the Light." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/367254.
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Optical sensor devices currently occupies multi-billion dollar markets in the water and oil & gas industries. Fluorescent sensors currently demonstrate the highest sensing efficiency for general detection applications. Proper design of light management is required for fluorescent sensor devices, which can increase the overall efficiency or add new device functionality.
To overcome this limitation, this thesis proposes the use of novel double heterostructure colloidal photonic crystals as a fluorescent sensor device. Double heterostructure colloidal photonic crystals sensor has the potential to be the elementary building blocks of the next generation of optoelectronic and sensing devices. This thesis presents the development of robust, facile, scalable, stable and cost-effective three dimensional fluorescent double heterostructure colloidal photonic crystals using conventional fabrication technology, thereby enabling photonic functionality to enhance fluorescence signal and sensing performance.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Ho, P. K. H. "Novel architectures for polymer light-emitting diodes." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604103.
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This dissertation work aims to develop novel optoelectronic polymer device architectures through appropriate control of the interfacial and bulk structures of the semiconducting polymer. The two approaches developed here are the hole-injection interlayer engineering via the layer-by-layer polyelectrolyte assembly, and refractive-index engineering via the use of polymer-inorganic nanocomposites. The poly-electrolyte assembly route enables vertical interfacial structuring of the electronic properties to be achieved at the anode contact for improved hole injection and electron confinement. The development of the nanocomposites provides solution-processable photonic building blocks that are semiconducting and that could provide optical feedback in polymer devices. Both of these developments have made possible new high-performance device architectures. For example, polymer light-emitting diodes (LEDs) with efficiencies of 20 cd/A in the green spectral region (estimated internal quantum yield, 15-20% photon/electron), and polymer microcavity LEDs with emission full-width-at-half-maximum of 25 nm and less have been demonstrated. This dissertation also addresses a few of the scientific issues encountered in the course of the work. The relationship between external and internal electroluminescence quantum yields of these LEDs is analysed, and the role played by optical properties of the metal cathode-reflector delineated. The effects of embedding SiO2 nanoparticles on the optical, electronic and morphological properties of the poly(p-phenylenevinylene) matrix, together with the extent of increased localisation of its p-electrons, are also studied.
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Fedorova, Ksenia Alexandrovna. "Novel semiconductor based broadly tunable light sources." Thesis, University of Dundee, 2011. https://discovery.dundee.ac.uk/en/studentTheses/ce12469e-3473-4a97-9f4d-45ade4c0acfb.
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The development of compact and low-cost coherent sources in visible and infrared wavelength range can provide indispensible tools for a variety of scientific, technological and industrial applications. Great progress over the last years in material science, crystal growth and semiconductor material processing in combination with recent advances in some of the more traditional technologies, in particular nonlinear frequency conversion and parametric sources, have led to the realisation of a new generation of laser sources. Furthermore, the advent of a new generation of quasi-phase-matched, waveguided and semiconductor nonlinear materials together with novel semiconductor lasers have led to the development of new frequency conversion and parametric sources with previously unattainable performance capabilities. The research described in this thesis relates to the development and characterisation of novel semiconductor based laser sources tunable in the broad spectral ranges which are unattainable for conventional lasers due to a lack of suitable laser gain materials. In the first part of the thesis the subject matter is concerned with the direct emission from laser devices. In particular, a broadly tunable InGaAs/InP strained multi-quantum well external cavity diode laser, operating in the spectral range of 1494 nm – 1667 nm with a maximum CW output power in excess of 81 mW and side-mode suppression ratio higher than 50 dB is demonstrated. This represents the highest output power and side-mode suppression ratio ever to be generated in this spectral region. A record broadly tunable high-power external cavity InAs/GaAs quantum-dot diode laser with a tuning range of 202 nm (1122 nm - 1324 nm), a maximum output power of 480 mW and a side-mode suppression ratio greater than 45 dB, is also demonstrated. This represents a promising achievement for the development of a high-power fast swept tunable laser and compact nonlinear frequency generation schemes for the green-yellow-orange-red spectral range. The second part of the thesis relates to induced nonlinear processes, focusing on frequency doubling and optical parametric oscillation. In particular, an all-room-temperature CW second harmonic generation at 612.9 nm and 591.5 nm in periodically poled potassium titanyl phosphate waveguides pumped by a broadly-tunable quantum-dot external cavity diode laser with a conversion efficiency of 10.5% and 7.9%, respectively, is demonstrated. For the first time, a green-to-red tunable laser source with tunability of over 60 nm (567.7 nm – 629.1 nm) based on frequency doubling in a single periodically poled potassium titanyl phosphate waveguide pumped by a single broadly-tunable quantum dot laser is demonstrated. These results are an important step towards a compact tunable coherent visible light source, operating at room temperature. The possibility of nonlinear frequency conversion in orientation-patterned GaAs waveguides is also investigated. The technology of low-loss periodically poled GaAs waveguided crystals is developed and such crystals are fabricated. Second harmonic generation at 1621 nm in low-loss periodically poled GaAs waveguide is demonstrated. An optical parametric oscillator system used as the pump source for GaAs devices and based on the periodically poled 5 mol% MgO-doped Congruent Lithium Niobate crystal, generating light in the wavelength range between 1430 nm and 4157 nm, is presented. The obtained results show a great promise for realisation of efficient quasi-phase-matched optical parametric oscillator devices based on orientation-patterned GaAs waveguides, which enables the extending generated wavelength up to 16 µm.
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SAVARESE, CLAUDIO. "A novel light detector for DarkSide-20k." Doctoral thesis, Gran Sasso Science Institute, 2018. http://hdl.handle.net/20.500.12571/9683.
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The astonishing precision of the Standard Model (SM) of particle physics in predicting observables to be measured by accelerators can rival only with its inability at describing most of the
energy-matter content of the universe. The most widely accepted cosmological model, the ΛCDM,
quantifies the percentage of matter fitting in the SM description to a mere 5% of the total. The
remaining 95% has to be divided among an unknown form of non-radiating matter and an even
more mysterious form of energy responsible for the universe accelerating expansion. In a 70 years
long period, since its first formulation, the Dark Matter (DM) scientific paradigm has accumulated
a huge number of arguments in its favor. Despite this, an irrefutable DM direct detection claim has
not yet been made.
Among all the possible species of dark matter, the Weakly Interacting Massive Particles (WIMPs)
form a class of candidates capable of explaining this physics puzzle in a natural way. Many experiments around the world aim for a WIMP direct detection under the leading assumption that a
weak DM-SM interaction is possible. Large noble liquids detectors lead this search in the high
WIMP-mass region thanks to their scalability to high target masses. Given the current lack of
positive observations, a new generation of multi-ton experiments is being designed to explore the
whole WIMP-nucleon interaction cross section range. DarkSide-20k aims to push its sensitivity up
to the ultimate experimental limit, the neutrino floor. This can be achieved exploiting the liquid
argon electron/nuclear recoil discrimination power, which together with volume fiducialization and
neutron tagging, allows the detector to run in background-free mode.
The key to successfully apply pulse shape discrimination to reject β/γ induced events lies in
having a high light yield, which is defined as the average number of detected photons per unit
of energy released in the target volume. In order to boost the detector photon efficiency in the
TPC volume, the DarkSide collaboration decided to abandon the traditional Photomultiplier Tube
(PMT) technology in favor of Silicon Photomultiplier (SiPM) one. Aiming to optimize these light
sensors for the experiment needs, an intense R&D activity was carried out to successfully equip and operate in liquid argon nearly 14 m2 of SiPMs grouped in 5210 Photon Detector Modules (PDM).
My PhD thesis is set in this context.
A first phase of the work consisted in choosing a suitable SiPM technology as building block
of the future Photon Detector Module. A campaign of cryogenic characterization of several SiPM
models was conducted. Pulse features (gain, pulse amplitude, single cell recharge time) as well as dark count rate (DCR) and correlated noises (direct crosstalk, after-pulse, delayed crosstalk) were studied as function of temperature and operating bias. The outcome of this campaign is described in Chapter 3 of my thesis and in the articles [1, 2].
This step came with the formulation of several requirements which PDMs have to comply in
order to ensure the accomplishment of the design physics reach of DarkSide-20k. In particular I contributed to formalize the specifications regarding the noise rate, SNR and dynamic range of the SiPM readout as described in Chapters 2, 5 and 6.
The second step towards a functioning PDM was the design of a transimpedance (TIA) preamplifier capable of operation in liquid Argon. The circuit was optimized to be compatible with the huge capacitance typical of solid-state photo-detectors. The extremely low noise and high bandwidth of the resulting TIA allow to readout a 10×10mm2 SiPM with a SNR of 30 and a timing resolution better than 1 ns. Starting from these results it was then possible to develop a SiPM connection
scheme to read 24 cm2 as a single channel fulfilling the SNR and timing resolution requirements.
These advancements are described in Chapter 4 and [3, 4].
The SiPM tile performances in terms of SNR and timing were reached also thanks to the study
and implementation of advanced digital filtering techniques. This, together with a possible DAQ
scheme based on these results, is discussed in Chapter 5.
Finally I developed a simulation code aiming to describe the effects of the electronics and readout
logic on the physics observables. The C++ based code adds to the Geant4 simulation of the detector the effects of the readout (noise, dynamic rage, timing). A whole set of the PDM parameters can be changed in order to study their impact on the performances of DarkSide-20k. This was fundamental to the editing of the specifications of the experiment as described in the Yellow Book [5]. Moreover my contribution extended to the definition of the requirements of the trigger logic and readout strategy. This part of the work is described in Chapter 6.
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Frese, Heather K. "A Hollow Light." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1212165103.
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Schmit, Jean-Paul. "Novel polymers for applications in light emitting diodes." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322867.
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Ng, Wai Lek. "Spectroscopy of novel light emitting silicon-based diodes." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/804881/.
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Ring, Josh. "Novel fabrication and testing of light confinement devices." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/novel-fabrication-and-testing-of-light-confinement-devices(51572720-0c49-482e-8523-e44ca877117f).html.
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The goal of this project is to study novel nanoscale excitation volumes, sensitive enoughto study individual chromophores and go on to study new and exciting self assemblyapproaches to this problem. Small excitation volumes may be engineered using light con-finement inside apertures in metal films. These apertures enhance fluorescence emissionrates, quantum yields, decrease fluorescence quenching, enable higher signal-to-noiseratios and allow higher concentration single chromophore fluorescence, to be studied byrestricting this excitation volume. Excitation volumes are reported on using the chro-mophore's fluorescence by utilising fluorescence correlation spectroscopy, which monitorsfluctuations in fluorescence intensity. From the correlation in time, we can find the res-idence time, the number of chromophores, the volume in which they are diffusing andtherefore the fluorescence emission efficiency. Fluorescence properties are a probe ofthe local environment, a particularly powerful tool due to the high brightness (quantumyield) fluorescent dyes and sensitive photo-detection equipment both of which are readilyavailable, (such as avalanche photodiodes and photomultiplier tubes). Novel materialscombining the properties of conducting and non-conducting materials at scales muchsmaller than the incident wavelength are known as meta-materials. These allow combi-nations of properties not usually possible in natural materials at optical frequencies. Theproperties reported so far include; negative refraction, negative phase velocity, fluorescenceemission enhancement, lensing and therefore light confinement has also been proposed tobe possible. Instead of expensive and slow lithography methods many of these materialsmay be fabricated with self assembly techniques, which are truly nanoscopic and otherwiseinaccessible with even the most sophisticated equipment. It was found that nanoscaled volumes from ZMW and HMMs based on NW arrays wereall inefficient at enhancing fluorescence. The primary cause was the reduced fluorescencelifetime reducing the fluorescence efficiency, which runs contrary to some commentatorsin the literature. NW based lensing was found to possible in the blue region of the opticalspectrum in a HMM, without the background fluorescence normally associated with a PAAtemplate. This was achieved using a pseudo-ordered array of relatively large nanowireswith a period just smaller than lambda / 2 which minimised losses. Nanowires in the traditionalregime lambda / 10 produced significant scattering and lead to diffraction, such that they werewholly unsuitable for an optical lensing application.
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Hamam, Rafif E. (Rafif Ezzat). "Novel resonant and light-guiding phenomena in photonics." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/68974.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 100-109).
We investigate theoretically five novel resonant and light-guiding photonics phenomena. First, we develop a universal coupled mode theory (CMT) treatment of the freespace scattering of waves from resonant objects. This analytical framework very accurately models the scattering and absorption cross sections, as long as the resonant scatterer has spherical/cylindrical symmetry, or is sufficiently smaller than the resonant wavelength of the incident wave. We apply it to study the scattering of light from spherically symmetrical resonant objects and atoms, and also the neutron scattering off nuclei. Then, we propose an efficient weakly-radiative Wireless Energy Transfer (WET) scheme between two identical classical resonant objects, strongly coupled to an intermediate one having the same resonance frequency. The transfer mechanism, analyzed by CMT, relies on the adiabatic evolution of a dark eigenstate of the 3-object system. We explore its performance in various parameter regimes, and illustrate it by witricity-type WET between resonant inductively-coupled capacitively-loaded metallic loops. Third, we develop an analytical CMT model for the electric field generated by an arbitrary polarization source in a general photonic structure (that could involve loss, gain and/or nonlinearities). Based on this model, we investigate the criteria for enhancing the efficiency of nonlinear effects, and produce efficient terahertz sources. The results, validated by Finite-Difference Time-Domain (FDTD) calculations, suggest that this approach could potentially be a substitute for the more numerically intensive FDTD method. Next, we propose a 2D PhC structure that supports super-collimation over a large frequency range. We theoretically and numerically investigate the collimation mechanism in this 2D structure, in comparison to that of two other frequently used related PhC structures. We also point out the potential importance of this structure in designing super-collimation-based devices for monochromatic and polychromatic light. Finally, we present numerical simulations of anisotropic multilayers that strongly discriminate certain incidence angles of light, over a broad range of frequencies and irrespective of polarization. Such systems could improve the efficiency of solar cells.
by Rafif E. Hamam.
Ph.D.
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Peacock, Anna Claire. "Applications of light propagation in novel photonic devices." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/42429/.
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In this thesis, the propagation of light in novel photonic devices has been studied theoretically, numerically and experimentally. In particular, self-similar solutions to the nonlinear Schrödinger equation have been investigated as a means of avoiding distortions associated with high power pulse propagation in optical fibres. The results show that it is the interplay between the nonlinear and dispersive effects that leads to stable formation of the self-similar solutions. By considering generalised nonlinear Schrödinger equations we have extended the previous investigations of linearly chirped parabolic pulse solutions, which exist in the normal dispersion regime, and have found a new broader class of self-similar solutions, which exist when the fibre parameters are allowed to vary longitudinally. Numerical simulations of these systems confirm the analytic predictions. Experimental confirmation of parabolic pulse generation in high gain cascaded amplifier systems and in highly nonlinear microstructured fibres is also reported. In addition, the propagation of light in modulated crystal structures has been investigated. By modifying the linear and nonlinear properties of the crystals it has been shown that it is possible to manipulate the speed and the wavelength of the propagating light. In particular, negative refractive index materials have been shown to support fast and/or slow propagating light, whilst two dimensional nonlinear photonic crystals have been used to demonstrate multiple harmonic generation over a wide range of phase matching angles. The influence of waveguiding geometries has also been considered to determine the optimum design for the efficiency of the devices
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Shangguan, Hanqun. "Novel Cylindrical Illuminator Tip for Ultraviolet Light Delivery." PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/4647.
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The design, processing, and sequential testing of a novel cylindrical diffusing optical fiber tip for ultraviolet light delivery is described. This device has been shown to uniformly(+/- 15%) illuminate angioplasty balloons, 20 mm in length, that are used in an experimental photochemotherapeutic treatment of swine intimal hyperplasia. Our experiments show that uniform diffusing tips of < 400 micron diameter can be reliably constructed for this and other interstitial applications. Modeling results indicate that this design is scalable to smaller diameters. The diffusing tips are made by stripping the protective buffer and etching away the cladding over a length of 20 mm from the fiber tip and replacing it with a thin layer of optical epoxy mixed with A/203 powder. To improve the uniformity and ease of fabrication, we have evaluated a new device configuration where the tip is etched into a modified conical shape, and the distal end face is polished and then coated with an optically opaque epoxy. This is shown to uniformly scatter - 70% of the light launched into the fiber without forward transmission. To our knowledge, we are the first to use this device configuration, and we have achieved a uniform cylindrical pattern of laser energy with uniformity < ± 15% of the average value. A simple computational model suitable for the interpretation of laser energy irradiance along the bare core surface of multimode optical fiber tips is proposed and experimentally verified. The model used is based on geometrical optics and Gaussian approximation. Good agreement is obtained between the calculation and experiment. We have measured the optical properties of the tips through all the sequences of the fabrication. The performances of the diffusing tips for illuminating angioplasty balloons are then evaluated by Ultraviolet Light at 365 nm. A Ti:Sapphire Ring Laser System with a doubling crystal pumped by an argon ion laser is used to generate the wavelength in this study.
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Zanardi, Noemi <1993>. "Strategie visive: analisi paratestuale dei romanzi light novel." Master's Degree Thesis, Università Ca' Foscari Venezia, 2018. http://hdl.handle.net/10579/12564.
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Le light novel sono un genere di romanzi di intrattenimento, che dall’inizio del nuovo millennio ha attirato grande interesse nel mondo mediatico giapponese, ma rimane ancora poco analizzato nel contesto dei popular cultural studies internazionali. Questa tipologia di romanzi è spesso collegata alla cultura otaku ed è caratterizzata dalla presenza di illustrazioni che la avvicinano ad anime, manga e videogiochi. Questa trattazione cercherà di analizzare come il paratesto visivo di questi libri (copertina, illustrazioni, label, ecc.) influenza il posizionamento di essi all’interno del mercato editoriale giapponese, condizionandone il consumo in base ai meccanismi del character. Si cercherà dunque di dimostrare che il principale ruolo delle illustrazioni che compongono la dimensione visiva di questi romanzi non è quello narrativo, ma quello rappresentativo, dato che il paratesto visivo crea un’immagine del libro e ne condiziona le modalità di lettura. A questo scopo a un’analisi semiotica del processo di codifica del paratesto visivo vengono affiancate tecniche di ricerca qualitativa (interviste e osservazione partecipante), volte a rappresentare la prospettiva emica degli agenti che producono questa categoria di romanzi.
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Wood, Danielle. "The Alphabet of Light and Dark : A Novel and Accompanying Essay." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/303.
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This thesis comprises n novel titled The Alphabet of Light and Dark and an accompanying essay titled ''The Skeleton of a Mermaid: Writing The Alphabet of Light and Dark'. The novel tells the story of Essie Lewis, an oceanographer in Western Australia, who returns to her home in Tasmania at the time of her grandfather's death. She inherits a sea chest full of strange treasures- among them a paper nautilus shell, a wedding band, a coil of fair hair, a coconut, and a thruppence piece coated in nacre.
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Powell, Zachary Michael. "Iron kills the stars: the commune of eternal light." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/13776.
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Master of ArtsDepartment of English
Daniel A. Hoyt
This project is the opening chapters of a novel in which two brothers, Txanton and Riddley, are split from each other in post-apocalyptic Kansas. The Commune of Eternal Light has been their family’s peaceful home for more than a hundred years but is crushed by a fascist army that considers killing the only way to survive in civilization’s aftermath. In this destruction, Txanton sees his father’s murder, while Riddley watches his mother’s death. After the separation, Txanton, along with several other boys from the Commune, becomes part of the very army that destroyed his family, and he is visited by the ghost of his great-great grandfather who begins telling his personal story along with the tale of the downfall of the world. Riddley, meanwhile, wanders a picaresque path in which he sees cannibals, zombies, witches, a cowboy, and other ghosts. Both boys struggle with the brutality of the wasteland they are thrust into and try to cope with the memories of their peaceful home and the deaths of their family and friends. Told in chapters that jump back-and-forth between the two brothers, the novel parallels their challenges in a close third-person narrative.
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Enevold, Jenny. "Development of light-emitting electrochemical cells for novel applications." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-59072.
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The work intended to make progress towards the objective of fiber-shaped light-emitting electrochemical cells (LECs). LECs comprising a film of poly(3,4-ethylenedioxythiophene): poly (styrenesulphonate) (PEDOT:PSS) cast from aqueous dispersion as the sole transparent anode were produced and characterized. It was shown that it is possible to achieve uniform yellow-green light emission at an efficiency of 0.96 cd/A from such LECs fabricated by spin coating at low rotational speed. Implications of using different cathode metals and varying the order of deposition of the films were studied and shown to have significant influence on device performance. Lastly, a novel fiber-like LEC in a coaxial geometry was produced, which promises bright prospects for new applications due to the flexibility of the used materials.
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Junco, Alberto. "Characterisation [i.e. Characterization] of a novel Kinesin Light Chain." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ55220.pdf.
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Preece, Daryl. "Novel uses of spatial light modulators in optical tweezers." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2619/.
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In recent years spatial light modulators (SLMs) have become an integral part of many optical trapping experiments. Yet their usefulness, which stems from their flexibility, is often under exploited. In this thesis I seek to demonstrate how it is possible to expand the range of optical trapping applications that may benefit from the use of spatial light modulators. From exploring the benefits of increased resolution to demonstrating novel applications like position clamping and polarization control, I show how SLMs are a resource which can benefit optical trapping in new and unconventional ways. The optical properties of liquid crystals have long been known however it is only recently that they have been applied to optical tweezers. The physics and operation of spatial light modulators are discussed in chapter 1, with specific attention paid to those aspects of operation which are of pertinent practical use to optical trapping. In chapter 2 it is shown how phase only modulation can be used to create effective holographic optical tweezers systems which are capable of manipulating micron scale particles and measuring pico-Newton forces. Chapter 3 charts the development and characterization of a 4 Mega-pixel spatial light modulator which was created as an improvement on current SLM technology. The role of SLMs in utilising lights angular momentum as a tool for creating rotational torque is discussed in chapter 4. In chapter 5 describes how SLMs can be used to create torques based the application of spin angular momentum to birefringent particles. We show, in chapter 6 how with suitable software engineering it is possible to both move optical traps and track particles in real time. Since the use of SLMs has been previously been limited by their bandwidth constraints we discuss in chapter 7 the use spatial light modulators in closed loop systems. We finish with a discussion of the use of SLMs in a new technique that may be applied to microrheology.
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Liu, Shi. "Development of novel conjugated polymers for light-emitting diodes /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/10569.
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Bevilacqua, Maurizio. "Novel models and methods for structured light 3D Scanners." Doctoral thesis, Universita degli studi di Salerno, 2012. http://hdl.handle.net/10556/289.
Full textAbstract:
2010 - 2011The work made during the PhD course in Information Engineering, was focused on the possibility to find out novel techniques for the quick calibration of a cheap 3D Scanner. It is based on a simple camera and a commercial projector, in order to develop low-cost devices with high reliability capable of acquiring large areas quickly. Many systems based on this configuration exist, those devices have benefits and disadvantages. They can acquire objects with large surface in a few seconds and with an adequate accuracy. On the other hand, they need a lengthy calibration and they are very sensitive to the noise due to the flicker of the light source. Considering these problems, I tried to find new robust calibration techniques in order to reduce the sensitivity to noise, and, in this way, to have high-performance low-cost 3D scanners with short-time calibration and reconfiguration. There are many calibration techniques available for these systems. First, it is necessary to calibrate the camera and then the overall system for projecting analog encoded patterns, typically sinusoidal or digital, such as Gray codes. These techniques are very time-consuming because they require a prior camera calibration phase separate from the calibration of the whole system and also disturbing factors are introduced by the ambient light noise. Indeed, a lot of projection patterns, used to map the calibration volume, are required to be projected. In order to achieve our goal, different types of structured light scanner have been studied and implemented, according to the schemes proposed in literature. For example, there exist scanners based on sinusoidal patterns and others based on digital patterns, which also allowed the implementation in real time mode. On these systems classical techniques of calibration were implemented and performance were evaluated ad a compromise between time and accuracy of the system. Classical calibration involves the acquisition of phase maps in the volume calibration following a pre-calibration of the camera. At the beginning, an algorithm that allows calibration through the acquisition of only two views has been implemented, including camera calibration, modeled by pin-hole model, in the calibration algorithm. To do this, we have assumed a geometric model for the projector which has been verified by the evaluation of experimental data. The projector is then modeled as a second camera, also using the pin-hole model, and we proceeded with the calibration of camera-projector pair as a pair of stereo cameras, using a DLT calibration. Thanks to the acquisition of two views of the target volume in the calibration, it is possible to extract the parameters of the two devices through which the projected pattern can be generated, and the acquisition by the camera can be done, eliminating the problem of noise due to ambient light. This system is a good compromise between the reduction in calibration time, which passed from half an hour to a couple of minutes, with a reduction in term of uncertainty in order of one percentage point of calibration volumes that was chosen of a depth of 10 centimeters… [edited by author]
X n.s.
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Nicol, David Brackin. "A Novel Solid State General Illumination Source." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14032.
Full textAbstract:
A novel solid state illumination source has been developed. A two terminal dual LED has been created with the ability to control the relative intensities of the two emission peaks by varying drive current. Doping profiles have been used to extend the dynamic range of the dual LED over other reported devices. Operation of the dual LEDs is explained as a function of drive current. In addition, novel use of phosphor mixtures allows the creation of a broadband spectral power distribution that can be varied using a dual LED as an excitation source. Combinations of phosphors that have varied excitation spectra provide the ability to selectively excite different phosphors with the different LED emission peaks. First and second generations of the two terminal dual LED and the phosphor combination are discussed. The final source has the ability to mimic the light of a blackbody radiator over a range of 3200 K - 5300 K. The development of a three terminal dual LED as a pump source was prohibited by the need for a III-nitride tunnel junction, that proved unattainable in the scope of this work. However, several novel doping schemes were investigated toward this end. Finally, a circadian light source has also been developed that can affect physiological changes in humans, and a light box for entrainment of circadian rhythms in rats has been built.
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Mangogna, Manuela. "Studies of light perceptionin marine diatoms and discovery of a novel blue light cryptochrome photoreceptor." Thesis, Open University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446292.
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Powell, Alexander. "Engineering plasmonic light scattering with thin dielectric films : towards enhanced light trapping and novel sensing elements." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:c18025ef-a693-441d-bd88-e37ebc09b6a5.
Full textAbstract:
Plasmonic research is becoming increasingly focused on the integration of noble metal nanostructures with planar devices to enhance their performance. Whilst the physics of noble metal nanoparticles at a simple interface is well studied, their behaviour inside a thin film structure is not. This work investigates the effect that placement in a thin dielectric film has on the excited modes and the directional scattering from various geometries of nanoparticle; the focus is on the fundamental principles but the application of this work in light trapping and nanoantenna design is also discussed. Research is conducted using finite-difference time-domain simulations and a custom built dark-field Fourier-space microscope, designed to interrogate individual particles and measure their angular scattering in thin films for the first time. It is found that the excited modes, large angle scattering and substrate coupling of the nanoparticles can be manipulated and improved considerably through careful choice of the materials and dimensions of the layers. Scattering from silver nanowires into a substrate is observed experimentally for the first time and an overcoating thin film is exploited to create highly directional emission, which is compared with nanoantennas in the literature. The potential to use this system as a novel sensing element is discussed. Following on from this, the nanocube patch antenna system is reviewed and its operation as a subwavelength plasmonic gas sensor is demonstrated for the first time to test for relative humidity using the Nafion polymer. This easily fabricable system shows superior sensitivities to other single-particle sensors across a range of humidities and simulations predict that by using sharper cubes and different deposition processes a further tripling of the recorded efficiency is achievable. The nanopatch structure can be readily adapted to detect a variety of other gases, and has the potential for integration into photonic circuitry.
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Mastandrea, Marco Michele. "Harnessing Visible Light for the Development of Novel Synthetic Strategies." Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/670605.
Full textAbstract:
L'objectiu principal d'aquesta tesi és el desenvolupament de noves estratègies sintètiques que aprofitin la irradiació amb llum visible. La catàlisi fotoredox en combinació amb catalitzadors orgànics i metàl·lics, així com la fotoquímica dels complexos pi-aniò, seran els principals conceptes emprats per explorar noves vies de reacció. Després d’una introducció general, es recullen tres projectes de recerca en aquesta tesi.
El primer projecte de recerca, inclòs al capítol II, mostra el desenvolupament d’una metodologia per a l’acoblament asimètric deshidrogenatiu creuat d’aldehids i xantens. La característica clau d’aquest enfocament es troba en el procés de dos passos emprat per oxidar els xantens als carbocations corresponents, que seran atrapats per una enamina formada in situ. La suavitat i selectivitat que permet la catàlisi fotoredox permet assolir alts nivells d’estereocontrol, bons rendiments i una àmplia tolerància de grup funcionals.
El segon projecte, que es mostra al capítol III, il·lustra una nova estratègia fotoredox per a la síntesi d’una àmplia gamma d’amines i èters al·lílics a partir d’àcids i alquins carboxílics. Aquesta aproximació es basa en l’activació d’alquins terminals mitjançant la fotoexcitació d’intermedis d’acetilur de coure formats in situ. Aquest procés té lloc mitjançant catàlisi cooperativa de coure i fotoredox orgànica i es pot dur a terme de manera estereodivergent. La metodologia desenvolupada s’ha aplicat a l’acoblament estereoselectiu de radicals alquils primaris, secundaris i terciaris amb alquins terminals (hetero)aromàtics.
Finalment, les interaccions anió-pi s’han identificat com el pas habilitant per a l’amidació de sistemes aromàtics promoguda per llum. Les proves disponibles indiquen que es produeix un complex anió entre un carbonat i una ariloxi amida pobra en electrons, permetent l'absorció de llum visible. Després de la irradiació, es produeix una transferència espontània d’electrons intracomplex, que condueix finalment a la generació de radicals amidil. Aquests radicals han estat atrapats eficientment per (hetero)arens rics en electrons o de manera intramolecular, proporcionant els corresponents productes amidats.El principal objetivo de esta tesis es el desarrollo de nuevas estrategias sintéticas que aprovechen la irradiación con luz visible. La catálisis fotoredox en combinación con catalizadores órganicos y metálicos, así como la fotoquímica de complejos pi-anión, serán los conceptos principales que permitirán explorar nuevas vías de reacción. Tras una introducción general, en esta tesis se recogen tres proyectos de investigación. El primer proyecto de investigación, incluido en el Capítulo II, muestra el desarrollo de una metodología para el acoplamiento cruzado deshidrogenativo asimétrico de aldehídos y xantenos. La característica clave de esta aproximación se encuentra en el proceso de dos pasos empleado para oxidar los xantenos a sus correspondientes carbocationes, posteriormente atrapados por una enamina formada in situ. La suavidad y selectividad que permite la catálisis fotoredox permite alcanzar altos niveles de estereocontrol, buenos rendimientos y una amplia tolerancia de grupos funcionales. El segundo proyecto, que se muestra en el Capítulo III, ilustra una nueva estrategia fotoredox para la síntesis de una amplia gama de aminas alílicas y éteres a partir de ácidos carboxílicos y alquinos. Este enfoque se basa en la activación de alquinos terminales a través de la fotoexcitación de intermedios de acetiluro de cobre formados transitoriamente. Este proceso se lleva a cabo mediante catálisis cooperativa de cobre y un catalizador orgánico fotoredox y se puede realizar de manera estereodivergente. La metodología desarrollada se ha aplicado al acoplamiento estereoselectivo de radicales alquilo primarios, secundarios y terciarios con alquinos terminales (hetero)aromáticos. Finalmente, las interacciones anión-pi se han identificado como el paso habilitador en la amidación de sistemas aromáticos promovida por la luz. La evidencia disponible indica que se produce un complejo anión-pi entre el carbonato y una ariloxi amida pobre en electrones, lo que facilita la absorción de la luz visible. Tras la irradiación, tiene lugar una transferencia de electrones intracomplejo espontánea, que conduce finalmente a la generación de radicales amidilo. Estos radicales han sido atrapados eficazmente por (hetero)arenos ricos en electrones o de forma intramolecular, proporcionando los correspondientes productos amidados.
The main goal of this thesis is the development of new synthetic strategies harnessing visible light irradiation. Cooperative organo- and metal photoredox catalysis, as well as anion-pi complexes photochemistry, will be the main concepts exploited to explore new reaction pathways. After a general introduction, three research projects are collected in this thesis. The first research project, included in Chapter II, shows the development of a methodology for the asymmetric cross-dehydrogenative coupling of aldehydes and xanthenes. The key feature of this approach stands in the two-step process employed to oxidize xanthenes to their corresponding carbocations, subsequently trapped by an in situ formed enamine. The mildness and selectivity enabled by photoredox catalysis allows to reach high levels of stereocontrol, good yields and wide functional group tolerance. The second project, shown in Chapter III, illustrates a novel photoredox strategy for the synthesis of a wide range of allylic amines and ethers from carboxylic acids and alkynes. This approach relies on the activation of terminal alkynes through the photoexcitation of transiently formed copper acetylide intermediates. This process takes place through cooperative copper and organic photoredox catalysis and can be carried out in stereodivergent manner. The developed methodology has been applied to the stereoselective coupling of primary, secondary and tertiary alkyl radicals with (hetero)aromatic terminal alkynes. Finally, anion–pi interactions have been identified as the enabling step in the light-promoted amidation of aromatic systems. The available evidence indicates that an anion pi-complex between carbonate and an electron-poor aryloxy amide is elicited, facilitating the absorption of visible light. Upon irradiation, a spontaneous intracomplex electron transfer takes place, leading ultimately to the generation of amidyl radicals. These radicals have been efficiently trapped by electron-rich (hetero)arenes or in an intramolecular fashion, affording the corresponding amidated products.
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Schwartz, Gregor. "Novel Concepts for High-Efficiency White Organic Light-Emitting Diodes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1217967185179-03950.
Full textAbstract:
Diese Arbeit behandelt neue Konzepte zur Realisierung hocheffizienter Weißlicht emittierender organischer Leuchtdioden (OLEDs), wobei blaue fluoreszierende Emitter mit grünen und roten phosphoreszierenden Emittern kombiniert werden. Bisherige Ansätze zur Erreichung höchster Quantenausbeuten basieren auf der ausschließlichen Verwendung phosphoreszierender Emitter, da diese prinzipiell 100% der elektrisch erzeugten Exzitonen in Licht umwandeln können. Allerdings sind speziell OLEDs mit phosphoreszierenden tiefblauen Emittern heutzutage nach wie vor nicht langzeitstabil. Andererseits gibt es zwar sehr stabile fluoreszierende Emitter auch im tiefblauen Spektralbereich, jedoch kann eine rein fluoreszierende OLED aus spinstatistischen Gründen maximal nur ein Viertel der erzeugten Exzitonen in Licht umwandeln. Für eine ernsthafte Verwendung von OLEDs als Lichtquellen sind sowohl die Umwandlungseffizienz elektrischer Leistung in Lichtleistung im sichtbaren Spektralbereich, als auch ihre Langzeitstabilität entscheidend. Ein Kompromiss lässt sich daher mit der Kombination von blauen fluoreszierenden Emittern mit grünen und roten phosphoreszierenden Emittern erzielen. Die beiden in dieser Arbeit entwickelten Konzepte unterscheiden sich in der energetischen Lage des Triplettniveaus des jeweils verwendeten fluoreszierenden blauen Emitters relativ zu den verwendeten phosphoreszierenden Emittern. Das erste Konzept verwendet einen fluoreszierenden blauen Emitter mit niedriger Triplettenergie, weshalb er bei direktem Kontakt mit den phosphoreszierenden Emittern deren Phosphoreszenz löscht. Eine Exzitonen blockierende Zwischenschicht unterdrückt diesen Verlustmechanismus. Dies wird sowohl in Photolumineszenzexperimenten als auch in OLEDs nachgewiesen. Weiterhin muss die Zwischenschicht gleichzeitig die Exzitonengeneration auf beiden Seiten gewährleisten, sie muss also bipolare Transporteigenschaften haben. Mischschichten aus einem Elektronen transportierenden und einem Löcher transportierenden Material werden mit der Methode der raumladungsbegrenzten Ströme in unipolaren Strukturen untersucht, um ihren Einfluss auf die Ladungsträger- und Exzitonenbalance in OLEDs zu erklären. Das zweite Konzept verwendet einen fluoreszierenden blauen Emitter mit hoher Triplettenergie. Dadurch ergeben sich einige Vorteile. Phosphoreszenz wird nicht mehr gelöscht, weshalb keine Zwischenschicht mehr notwendig ist. Zusätzlich können außerdem die auf dem blauen fluoreszierenden Emitter erzeugten Triplettexzitonen für die Lichtemission verwendet werden, indem man sie auf die phosphoreszierenden Emitter überträgt. Damit ist es grundsätzlich möglich, 100% der elektrisch erzeugten Exzitonen für die Lichtemission zu verwenden, obwohl ein fluoreszierender Emitter verwendet wird. Allerdings ist dabei darauf zu achten, dass die Singulettexzitonen nicht ebenfalls übertragen werden, da sonst kein Weißlicht mehr erzeugt werden kann. Es werden verschiedene OLED-Strukturen untersucht, um Singulett- und Triplettexzitonen so auf die jeweiligen Emitter zu verteilen, dass eine ausgewogene spektrale Balance der Emission erreicht wird. Ein zentraler Punkt ist dabei die Ausnutzung der unterschiedlich großen Diffusionslängen von Singulett- und Triplettexzitonen.
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Turner, Matthew. "Light along the river a short novel in two parts /." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1211398623/.
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Stanton-Humphreys, Megan. "Design, synthesis and application of novel light-activated molecular probes." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:1d0905c4-7fba-4796-92a5-848715204950.
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Caged compounds are biologically active molecules that are rendered inert by masking an important functionality with a photolabile protecting, ‘caging’, group. The caging group can be removed by irradiation with light to reveal the active compound with restored pharmacological activity with high spatial and temporal control. This technology provides an ideal tool for the study of many chemical, physiological and biological systems. This DPhil dissertation highlights several projects in which caging technology has been employed to address biological problems and questions. The first example of spatially controlled mitochondrial inactivation is reported - a tool for the study of the role of mitochondria in Ca2+ signalling. Caged TRPV1 agonists and antagonists have been developed to probe TRPV1, specifically the location of the agonist-binding site. T cell activation has been controlled with light as a tool to gain insight into the adaptive immune response. Caged sodium channel blockers have been investigated. Wavelength-orthogonal photolysis in a neuronal system has been demonstrated using the neurotransmitters glutamate and GABA - this represents a significant advancement in caging technology. This dissertation also includes investigations into the development of novel caging groups.
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Meng, Xiangeng. "Studies on Novel Light Emitting Materials Based on Random Systems." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/66210.
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Schwartz, Gregor. "Novel Concepts for High-Efficiency White Organic Light-Emitting Diodes." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23655.
Full textAbstract:
Diese Arbeit behandelt neue Konzepte zur Realisierung hocheffizienter Weißlicht emittierender organischer Leuchtdioden (OLEDs), wobei blaue fluoreszierende Emitter mit grünen und roten phosphoreszierenden Emittern kombiniert werden. Bisherige Ansätze zur Erreichung höchster Quantenausbeuten basieren auf der ausschließlichen Verwendung phosphoreszierender Emitter, da diese prinzipiell 100% der elektrisch erzeugten Exzitonen in Licht umwandeln können. Allerdings sind speziell OLEDs mit phosphoreszierenden tiefblauen Emittern heutzutage nach wie vor nicht langzeitstabil. Andererseits gibt es zwar sehr stabile fluoreszierende Emitter auch im tiefblauen Spektralbereich, jedoch kann eine rein fluoreszierende OLED aus spinstatistischen Gründen maximal nur ein Viertel der erzeugten Exzitonen in Licht umwandeln. Für eine ernsthafte Verwendung von OLEDs als Lichtquellen sind sowohl die Umwandlungseffizienz elektrischer Leistung in Lichtleistung im sichtbaren Spektralbereich, als auch ihre Langzeitstabilität entscheidend. Ein Kompromiss lässt sich daher mit der Kombination von blauen fluoreszierenden Emittern mit grünen und roten phosphoreszierenden Emittern erzielen. Die beiden in dieser Arbeit entwickelten Konzepte unterscheiden sich in der energetischen Lage des Triplettniveaus des jeweils verwendeten fluoreszierenden blauen Emitters relativ zu den verwendeten phosphoreszierenden Emittern. Das erste Konzept verwendet einen fluoreszierenden blauen Emitter mit niedriger Triplettenergie, weshalb er bei direktem Kontakt mit den phosphoreszierenden Emittern deren Phosphoreszenz löscht. Eine Exzitonen blockierende Zwischenschicht unterdrückt diesen Verlustmechanismus. Dies wird sowohl in Photolumineszenzexperimenten als auch in OLEDs nachgewiesen. Weiterhin muss die Zwischenschicht gleichzeitig die Exzitonengeneration auf beiden Seiten gewährleisten, sie muss also bipolare Transporteigenschaften haben. Mischschichten aus einem Elektronen transportierenden und einem Löcher transportierenden Material werden mit der Methode der raumladungsbegrenzten Ströme in unipolaren Strukturen untersucht, um ihren Einfluss auf die Ladungsträger- und Exzitonenbalance in OLEDs zu erklären. Das zweite Konzept verwendet einen fluoreszierenden blauen Emitter mit hoher Triplettenergie. Dadurch ergeben sich einige Vorteile. Phosphoreszenz wird nicht mehr gelöscht, weshalb keine Zwischenschicht mehr notwendig ist. Zusätzlich können außerdem die auf dem blauen fluoreszierenden Emitter erzeugten Triplettexzitonen für die Lichtemission verwendet werden, indem man sie auf die phosphoreszierenden Emitter überträgt. Damit ist es grundsätzlich möglich, 100% der elektrisch erzeugten Exzitonen für die Lichtemission zu verwenden, obwohl ein fluoreszierender Emitter verwendet wird. Allerdings ist dabei darauf zu achten, dass die Singulettexzitonen nicht ebenfalls übertragen werden, da sonst kein Weißlicht mehr erzeugt werden kann. Es werden verschiedene OLED-Strukturen untersucht, um Singulett- und Triplettexzitonen so auf die jeweiligen Emitter zu verteilen, dass eine ausgewogene spektrale Balance der Emission erreicht wird. Ein zentraler Punkt ist dabei die Ausnutzung der unterschiedlich großen Diffusionslängen von Singulett- und Triplettexzitonen.
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Fröbel, Markus. "Novel Concepts For Alternating Current Operated Organic Light-Emitting Devices." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-221652.
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Inorganic alternating current electroluminescent devices (AC-ELs) are known for their ruggedness and extreme long-term reliability, which is why they can often been found in industrial and medical equipment as well as in applications in the military sector. In contrast to the inorganic phosphors used in AC-ELs, organic materials offer a number of advantages, in particular a significantly higher efficiency, easier processibility, and a wide selection of emitter materials spanning the entire visible spectrum. Several efforts towards alternating current driven organic light-emitting devices have recently been made, however, important operating mechanism are still not well understood. In the first part of this theses, alternating current driven, capacitively coupled, pin-based organic light-emitting devices are investigated with respect to the influence of the thickness of the insulating layer and the intrinsic organic layer on the driving voltage. A three-capacitor model is employed to predict the basic behavior of the devices and good agreement with the experimental values is found. The proposed charge regeneration mechanism based on Zener tunneling is studied in terms of field strength across the intrinsic organic layers. A remarkable consistency between the measured field strength at the onset point of light emission (3–3.1 MV/cm) and the theoretically predicted breakdown field strength of around 3 MV/cm is obtained. The latter value represents the field required for Zener tunneling in wide band gap organic materials according to Fowler-Nordheim theory. In a second step, asymmetric driving of capacitively coupled OLEDs is investigated. It is found that different voltages and/or pulse lengths for positive and negative half-cycle lead to significant improvements in terms of brightness and device efficiency.
Part two of this work demonstrates a device concept for highly efficient organic light-emitting devices whose emission color can be easily adjusted from, e.g., deep-blue through cold-white and warm-white to saturated yellow. The presented approach exploits the different polarities of the positive and negative half-cycles of an alternating current driving signal to independently address a fluorescent blue emission unit and a phosphorescent yellow emission unit vertically stacked on top of each other. The electrode design is optimized for simple fabrication and driving and allows for two-terminal operation by a single source. The presented approach for color-tunable OLEDs is versatile in terms of emitter combinations and meets application requirements by providing a high device efficiency of 36.2 lm/W, a color rendering index of 82 at application relevant brightness levels of 1000 cd/m², and warm-white emission color coordinates.
The final part demonstrates an approach for full-color OLED pixels that are fabricated by vertical stacking of a red-, green-, and blue-emitting unit. Each unit can be addressed separately which allows to efficiently generate every color that is a superposition of spectra of the individual emission units. The device is built in a top-emission geometrywhich is highly desirable for display fabrication as the pixel can be directly deposited onto the back-plane electronics. Furthermore, the presented device design requires only three independently addressable electrodes which simplifies fabrication and electrical driving.
The electrical performance of each individual unit is on par with standard pin single emission unit OLEDs, showing very low leakage currents and achieving high brightness levels at moderate voltages of around 3–4 V.
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Hsu, Chia Wei. "Novel Trapping and Scattering of Light in Resonant Nanophotonic Structures." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226083.
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Nanophotonic structures provide unique ways to control light and alter its behaviors in ways not possible in macroscopic structures. In this thesis, we explore novel behaviors of light created by nanophotonic structures, with a common theme on resonance effects. The first half of the thesis focuses on a peculiar type of electromagnetic resonance, where the resonance lifetime diverges to infinity. These states, called bound states in the continuum, remain localized in space even though their frequency lie within a continuum of extended modes. We find such states in photonic crystal slabs and the surface of bulk photonic crystals. We show the conditions necessary for them to exist, and provide the first experimental observation of these unusual states. We also show that these states have a topological nature, with conserved and quantized topological charges that govern their generation, evolution, and annihilation. The second half of the thesis concerns light scattering from resonant nanophotonic structures, where resonances can enhance or suppress scattering at particular wavelengths and angles. We show that multiple resonances in one nanostructure and in the same multipole channel generally lead to a scattering dark state where the structure becomes transparent. Based on the coherent interference from multiple scatterers, we show there are geometries that can achieve a sharp structural color where the hue, saturation, and brightness are all viewing-angle independent. We also invent a new type of transparent display based on wavelength-selective light scattering from nanostructures.
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Kwok, Chi Chung. "Synthesis and characterization of novel series of light-emitting oligomers." HKBU Institutional Repository, 2001. http://repository.hkbu.edu.hk/etd_ra/295.
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Cardile, Paolo. "Emission and amplification of light from novel Si-based materials." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/934.
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In questo lavoro di tesi mi sono occupato della sintesi di materiali innovativi basati sul silicio per applicazioni in microfotonica, della loro caratterizzazione e della realizzazione di dispositivi. Questo lavoro ha portato alla fabbricazione di un LED al silicio molto efficiente, funzionante a temperatura ambiente e a lunghezze d'onda utili per le telecomunicazioni. Inoltre sono stati proposti dei materiali innovativi basati sulle terre rare, come candidati ideali per la realizzazione di amplificatori ottici planari.
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Kalaji, Ali. "Novel cerium-doped phosphors for solid-state lighting." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607693.
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Jones, James Kevin. "Design of a novel stacked storage ring for low emittance light sources." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/design-of-a-novel-stacked-storage-ring-for-low-emittance-light-sources(53cedd16-ea4d-4343-abc9-78886a934a9b).html.
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Storage ring light sources are in use around the world operating as high brightness photon sources from the infrared to the X-ray photon regimes. Whilst modern light source designs achieve horizontal emittances in the few-nm range, they are only diffraction limited in the vertical plane with emittances as low as 10~pm-rad. To achieve fully diffraction limited light sources in the X-ray regime requires a fundamental change in the design of such machines. Many such designs have been proposed based on the multi-bend achromat (MBA) lattice, which have been shown to achieve the required emittance reduction. However MBA lattices typically have a reduced dynamic acceptance, and consequently shorter beam lifetimes. Whilst this can be ameliorated somewhat through the use of top-up injection schemes, many issues still remain. In this thesis we explore one possible alternative to the multi-bend achromat (MBA) paradigm: the stacked storage ring. We propose a storage ring consisting of two synchrotrons joined via a static magnetic vertical transfer line. One of the rings has a reduced emittance through the use of high field damping wigglers, whilst the other is used for standard user experiments. The cumulative emittance of the combined ring structure is a function of the emittances of the two rings. The stacked ring approach allows for a reduction in the beam emittance without a consequent increase in the machine footprint, as in the case of the MBA lattice. Additionally, we may use the more relaxed lattice structures popular in currently operating 3rd generation light sources to maintain a reasonable dynamic acceptance even with the reduced emittance. We apply the stacked storage ring concept to the design of a low emittance 700~MeV compact light source for low energy vacuum ultraviolet photon output. The desirability of such a low energy photon source for UK science has previously been explored in depth. We examine the design of such a light source based around a strong damping stacked storage ring in the presence of Touschek and Intra-Beam scattering whilst analysing the effects on the dynamic properties of the lattice. We also apply the stacked ring concept to two lattices designed to operate in the high energy X-ray region of the photon spectrum and investigate the potential advantages in this regime, including as an adjunct to further improve proposed MBA concepts.
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Beck, Tobias. "Novel Concepts of Light Application for ALA-PDT of Malignant Gliomas." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-117999.
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Rudhall, Andrew Peter. "Ultrashort laser pulse shaping for novel light fields and experimental biophysics." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3682.
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Broadband spectral content is required to support ultrashort pulses. However this broadband content is subject to dispersion and hence the pulse duration of corresponding ultrashort pulses may be stretched accordingly. I used a commercially-available adaptive ultrashort pulse shaper featuring multiphoton intrapulse interference phase scan technology to characterise and compensate for the dispersion of the optical system in situ and conducted experimental and theoretical studies in various inter-linked topics relating to the light-matter interaction. Firstly, I examined the role of broadband ultrashort pulses in novel light-matter interacting systems involving optically co-trapped particle systems in which inter-particle light scattering occurs between optically-bound particles. Secondly, I delivered dispersion-compensated broadband ultrashort pulses in a dispersive microscope system to investigate the role of pulse duration in a biological light-matter interaction involving laser-induced cell membrane permeabilisation through linear and nonlinear optical absorption. Finally, I examined some of the propagation characteristics of broadband ultrashort pulse propagation using a computer-controlled spatial light modulator. The propagation characteristics of ultrashort pulses is of paramount importance for defining the light-matter interaction in systems. The ability to control ultrashort pulse propagation by using adaptive dispersion compensation enables chirp-free ultrashort pulses to be used in experiments requiring the shortest possible pulses for a specified spectral bandwidth. Ultrashort pulsed beams may be configured to provide high peak intensities over long propagation lengths, for example, using novel beam shapes such as Bessel-type beams, which has applications in biological light-matter interactions including phototransfection based on laser-induced cell membrane permeabilisation. The need for precise positioning of the beam focus on the cell membrane becomes less strenuous by virtue of the spatial properties of the Bessel beam. Dispersion compensation can be used to control the temporal properties of ultrashort pulses thus permitting, for example, a high peak intensity to be maintained along the length of a Bessel beam, thereby reducing the pulse energy required to permeabilise the cell membrane and potentially reduce damage therein.
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Schott, CeÌcile. "Dynamic light scattering and Freedericksz transition in novel nematic liquid crystals." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274513.
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Wang, Yisu. "Fabrication and quantitative correlative light-electron microscopy of novel plasmonic nanoparticles." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/120089/.
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Metallic nanoparticles (MNPs) are attracting increasing interest for many applications in photonics, ranging from optoelectronic devices to bioimaging and biosensing. An advantage of these systems is that their optical properties, governed by their localised surface plasmon resonance, are widely tunable via the nanoparticle shape and size, which can be controlled via e.g. colloid synthesis. In that context, it is important to develop accurate experimental methods able to correlate the size and shape of an individual single MNP, measured with nanometric precision, with its individual optical properties. In this thesis, three different MNP systems, namely i) commercially-available Ag nanocubes of 75 nm edge; ii) Ag tetrahedra, bi-tetrahedra and decahedra in the 25 - 50 nm size range which was fabricated in-house using a plasmon-mediated photochemistry method; iii) Ag nanodimers was fabricated in-house via controlled self-assembly of polymer linkers onto commercial nominally spherical Ag nanoparticles of 40 nm diameter. Beyond fabrication, a substantial part of the work reported in this thesis describes the experimental protocol for correlative optical and transmission electron microscopy, which was developed and optimised, comprising reproducible deposition of these silver nanoparticles onto TEM grids, their optical characterisation via polarisation-resolved high-resolution dark-field and extinction micro-spectroscopy, and subsequent high-resolution TEM of the same particle. As proof-of-concept, the same Ag nanocubes of 75 nm edge were characterised optically in different dielectric environments, using solvents of different refractive index n; specifically, anisole (n=1.52), water (n=1.33), and air (n=1). The MNP scattering and extinction cross-section was determined in absolute units using an in-house developed quantitative measurement protocol, and the results are compared with numerical simulations using the measured geometry. These studies pave the way toward an in depth understanding of the relationship between geometrical and optical properties of MNPs of non-trivial shapes, which in turn have the potential to be exploited in innovative bioimaging and biosensing platforms.
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Heidt, Alexander Matthias. "Novel coherent supercontinuum light sources based on all-normal dispersion fibers." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17780.
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Thesis (PhD)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The concept of broadband coherent supercontinuum (SC) generation in all-normal dispersion (ANDi) fibers in the near-infrared, visible and ultraviolet (UV) spectral regions is introduced and investigated in detail. In numerical studies, explicit design criteria are established for ANDi photonic crystal fiber (PCF) designs that allow the generation of flat and smooth ultrabroad spectral profiles without significant fine structure and with excellent stability and coherence properties. The key benefit of SC generation in ANDi fibers is the conservation of a single ultrashort pulse in the time domain with smooth and recompressible phase distribution. In the numerical investigation of the SC generation dynamics self-phase modulation and optical wave breaking are identified as the dominant nonlinear effects responsible for the nonlinear spectral broadening. It is further demonstrated that coherence properties, spectral bandwidth and temporal compressibility are independent of input pulse duration for constant peak power. The numerical predictions are in excellent agreement with experimental results obtained in two realizations of ANDi PCF optimized for the near-infrared and visible spectral region. In these experiments, the broadest SC spectrum generated in the normal dispersion regime of an optical fiber to date is achieved. The exceptional temporal properties of the generated SC pulses are verified experimentally and their applicability for the time-resolved study of molecular dynamics in ultrafast transient absorption spectroscopy is demonstrated. In an additional nonlinear pulse compression experiment, the SC pulses obtained in a short piece of ANDi PCF could be temporally recompressed to sub-two cycle durations by linear chirp compensation. Numerical simulations show that even shorter pulse durations with excellent quality can be achieved by full phase compensation. The concept is further extended into the UV spectral regime by considering tapered optical fibers with submicron waist diameter. It is shown that coherent SC spectra with considerable spectral power densities in the usually hard to reach wavelength region below 300 nm can be generated using these freestanding photonic nanowires. Although technological difficulties currently prevent the fabrication of adequate nanofibers, the concept could be experimentally verified by coherent visible octave-spanning SC generation in tapered suspended core fibers with ANDi profile. The work contained in this thesis therefore makes important contributions to the availability and applicability of fiber-based broadband coherent SC sources with numerous high-impact applications in fundamental science and modern technology.
AFRIKAANSE OPSOMMING: Die konsep van breëband koherente superkontinuum (SK) in alles-normaal dispersiewe (ANDi) vesels in die naby-infrarooi, sigbare en ultraviolet (UV) spektrale gebiede word voorgestel en in detail ondersoek. In numeriese studies word eksplisiete ontwerpskriteria vasgestel vir ANDi fotoniese kristal vesel (FKV) ontwerpe wat dit moontlik maak om plat en gladde ultra-breë spektrale profiele te genereer sonder noemenswaardige fynstruktuur en met uitstekende stabiliteit en koherensie eienskappe. Die sleutel voordeel van SK genering in ANDi vesels is die behoud van ’n enkele ultrakort puls in tyd met ’n gladde en saamdrukbare fase distribusie. In die numeriese ondersoek van die SK generering is die dinamika van fase selfmodulering geïdentifiseer as die dominante nie-lineêre effek wat verantwoordelik is vir die nie-lineêre spektrale verbreding. Daar word voorts aangetoon dat die koherensie eienskappe, spektrale bandwydte en saamdrukbaarheid in tyd onafhanklik is van die inset pulsduur vir konstante drywing. Die numeriese voorspellings stem uitstekend ooreen met die eksperimentele resultate wat verkry is met twee ANDi FKVÕs wat optimeer is vir die naby-infrarooi en sigbare spektrale gebied. In hierdie eksperimente is die breedste SK spektrum gegenereer wat tot hede in die normaal dispersiewe regime met ’n optiese vesel behaal is. Die besondere eienskappe van die genereerde SK pulse is eksperimenteel bevestig en die toepasbaarheid vir tyd opgelosde studie van molekulêre dinamika is gedemonstreer. In ’n addisionele nie-lineêre puls kompressie eksperiment is SK pulse verkry in ’n kort stuk ANDi FKV wat in tyd saamgedruk kon word tot sub-twee siklus tydsduur deur liniêre tjirp kompensering. Numeriese simulasies toon aan dat selfs korter pulse met uitstekende kwaliteit behaalbaar is met volledige fase kompensasie. Die konsep is verder uitgebrei na die UV spektrale gebied deur ’n koniese vesel te beskou met sub-mikron diameter. Daar is aangetoon dat koherente SK spektra met noemenswaardige spektrale drywing in die golflengte gebied onder 300 nm, wat gewoonlik as moeilik toeganklik beskou word, bereik kan word deur hierdie vrystaande fotoniese nano-vesels aan te wend. Alhoewel tegnologiese probleme die vervaardiging van voldoende nano-vesels verhinder, kon die konsep eksperimenteel bewys word deur koherente sigbare oktaafspannende SK te genereer in koniese gesuspendeerde kern vesels met ’n ANDi profiel aan te wend. Die werk wat in die tesis vervat is, maak dus belangrike bydraes tot die beskikbaarheid en toepasbaarheid van vesel gebaseerde breëband koherente SK bronne met verskeie hoë impak toepassings in fundamentele wetenskap en moderne tegnologie.
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Breslin, John Anthony. "Novel pixel circuits for liquid crystal over silicon spatial light modulators." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/12059.
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Spatial Light Modulators are used in many applications and Liquid Crystal Spatial Light Modulators are a mature technology with devices now commercially available. Over the past 3 years there has been a rapid increase in device resolution, with a decrease in pixel size. To date though, on Static Memory pixels that incorporate charge-balancing circuitry, the underlying pixel architecture has remained unchanged. This thesis presents novel "load-and-display" Static Memory pixel designs. The importance of the pixels' architectural changes is highlighted, along with design and implementation issues. The thesis also presents two more specialised pixel architectures: pixels designed for a specific application, rather than as general purpose load-and-display devices. Future trends in Liquid Crystal Spatial Light Modulators are also considered: has research and development now reached steady-state; or what impact could the designs presented in this thesis in conjunction with changes in silicon process technology have on these future trends?
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Filip, Marina Rucsandra. "Electronic excitations and rational design of novel light sensitisers for photovoltaics." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:f514f6d8-201d-4055-aa53-182307e63b00.
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The development of scalable and cost-efficient solar cell technologies constitutes a priority in the field of photovoltaics research. Semiconductor sensitised solar cells (SSSC) and hybrid organic-inorganic perovskite solar cells (HOPSC) are two emerging technologies that have been actively pursued in the search for the most efficient, cost-competitive, stable and nontoxic photovoltaic devices. The HOPSCs have been polarising the attention of the photovoltaics community in the past three years due to their ever-increasing efficiencies, currently exceeding 20% while SSSCs have increased in popularity in the last decade, showing a steady increase of their efficiency and emergence of new materials implemented as light sensitisers. Improvement of these novel technologies relies on understanding of the physical properties of the materials components and on efficient strategies towards the discovery of novel compounds. In this thesis, we address these requirements by modelling the electronic structures of novel light sensitisers from first principles. We focus on the analysis of two groups of materials, the hybrid organic-inorganic lead-iodide perovskites and the metal chalcogenides of the stibnite family. We study the electronic structure of CH3NH3PbI3 within density functional theory and obtain the quasiparticle band gap for this material within the GW method in good agreement with experiment. Further, we conduct a systematic study of the interplay between the electronic properties of hybrid organic-inorganic perovskites and the structure of the inorganic perovskite network. As a result, we obtain a simple strategy for tuning the band gap of perovskite light absorbers by changing the size of the central cation, and propose AsH4PbI3 and SbH4PbI3 as potential novel light sensitisers for HOPSC. The second part of the thesis is dedicated to the study of the electronic structure of four isostructural metal chalcogenides of the stibnite family, stibnite, antimonselite, bismuthinite and guanajuatite. A study of the quasiparticle band gaps of these materials is conducted, similar to the approach used for CH3NH3PbI3. By using the Shockley-Queisser analysis, we obtain that all four materials are promising for application as light sensitisers.
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Lin, Meifang. "Robust organic light emitting device with advanced functional materials and novel device structures." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/939.
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Ark, Morris. "Development of a Novel Treatment Device for Upper Gastrointestinal Complications." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18134.
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One of the major upper gastrointestinal (UGI) complications that affect approximately 1 in 10 Australians is gastro-oesophageal reflux disease (GORD). GORD is when stomach acid frequently passes back up into the oesophagus and damages the oesophageal wall. Research has shown that frequent exposure of acid can increase the risk of adenocarcinoma in the oesophagus, where in Western populations the incidence is increasing. The survival rate for patients with oesophageal adenocarcinoma is low. This thesis proposed to develop a device with the potential to treat GORD and in turn reduce the risk of adenocarcinoma formation. The proposed device is made up of two main components, an anti-reflux valve and a novel device attachment system that uses LED light activation to adhere to tissue. Various tests were conducted such as tensile test, SEM imaging, pressure tests and cell cultures. These tests were performed to determine the device’s potential. The results showed that after 10 minutes of LED light activation the adhesive lap shear strength on porcine tissue was 7.50 kPa. The device showed it could support cell attachment and proliferation. Various valve designs were investigated, with the best valve able to prevent pressure up to 6 kPa, close to the natural pressure exerted by the lower oesophageal sphincter. Deployment of the device in porcine oesophagus using a standard medical endoscope was promising, but further optimisation is required. The significance of this research showed that a light activated adhesive system was possible using standard LED lighting, achieving strengths superior to fibrin glue while being safe and capable of tissue integration. The other key outcome was silicone anti-reflux valves were made from 3D-printed moulds capable of replicating the resistance of natural oesophagus. The final device shows promise and with future development could become a new treatment option for long-term sufferers of GORD. One of the major upper gastrointestinal (UGI) complications that affect approximately 1 in 10 Australians is gastro-oesophageal reflux disease (GORD). GORD is when stomach acid frequently passes back up into the oesophagus and damages the oesophageal wall. Research has shown that frequent exposure of acid can increase the risk of adenocarcinoma in the oesophagus, where in Western populations the incidence is increasing. The survival rate for patients with oesophageal adenocarcinoma is low. This thesis proposed to develop a device with the potential to treat GORD and in turn reduce the risk of adenocarcinoma formation. The proposed device is made up of two main components, an anti-reflux valve and a novel device attachment system that uses LED light activation to adhere to tissue. Various tests were conducted such as tensile test, SEM imaging, pressure tests and cell cultures. These tests were performed to determine the device’s potential. The results showed that after 10 minutes of LED light activation the adhesive lap shear strength on porcine tissue was 7.50 kPa. The device showed it could support cell attachment and proliferation. Various valve designs were investigated, with the best valve able to prevent pressure up to 6 kPa, close to the natural pressure exerted bOne of the major upper gastrointestinal (UGI) complications that affect approximately 1 in 10 Australians is gastro-oesophageal reflux disease (GORD). GORD is when stomach acid frequently passes back up into the oesophagus and damages the oesophageal wall. Research has shown that frequent exposure of acid can increase the risk of adenocarcinoma in the oesophagus, where in Western populations the incidence is increasing. The survival rate for patients with oesophageal adenocarcinoma is low. This thesis proposed to develop a device with the potential to treat GORD and in turn reduce the risk of adenocarcinoma formation. The proposed device is made up of two main components, an anti-reflux valve and a novel device attachment system that uses LED light activation to adhere to tissue. Various tests were conducted such as tensile test, SEM imaging, pressure tests and cell cultures. These tests were performed to determine the device’s potential. The results showed that after 10 minutes of LED light activation the adhesive lap shear strength on porcine tissue was 7.50 kPa. The device showed it could support cell attachment and proliferation. Various valve designs were investigated, with the best valve able to prevent pressure up to 6 kPa, close to the natural pressure exerted by the lower oesophageal sphincter. Deployment of the device in porcine oesophagus using a standard medical endoscope was promising, but further optimisation is required. The significance of this research showed that a light activated adhesive system was possible using standard LED lighting, achieving strengths superior to fibrin glue while being safe and capable of tissue integration. The other key outcome was silicone anti-reflux valves were made from 3D-printed moulds capable of replicating the resistance of natural oesophagus. The final device shows promise and with future development could become a new treatment option for long-term sufferers of GORD. y the lower oesophageal sphincter. Deployment of the device in porcine oesophagus using a standard medical endoscope was promising, but further optimisation is required. The significance of this research showed that a light activated adhesive system was possible using standard LED lighting, achieving strengths superior to fibrin glue while being safe and capable of tissue integration. The other key outcome was silicone anti-reflux valves were made from 3D-printed moulds capable of replicating the resistance of natural oesophagus. The final device shows promise and with future development could become a new treatment option for long-term sufferers of GORD.
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Keeling, David. "Novel thin film optical modulator/tunable retarder." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/29595.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.Committee Chair: A. Rahman Zaghloul ; Committee Members: W. Russell Callen and Doug Yoder. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Egertz, David. "Novel Safety Requirements and Crash Test Standards for Light- Weight Urban Vehicles." Thesis, KTH, Lättkonstruktioner, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-78694.
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In recent years the interest for smaller, cheaper and more energy efficient vehicles hasincreased significantly. These vehicles are intended to be used in urban areas, where theactual need of large heavy cars is generally minor. The travelled distance is on average lessthan 56km during a day and most often there is only one person travelling in the vehicle. Manyof the established car manufacturers have recently started to take interest into this marketsegment, but the majority of these small vehicles are still manufactured by smaller companiesat a low cost and with little or no research done on vehicle traffic safety. This may be becausethere are still no legal requirements on crash testing of this type of vehicles.This report will examine road safety for Urban Light-weight Vehicle (ULV) to find criticalcrash scenarios from which future crash testing methods for urban vehicles can be derived.The term ULV is specific to this report and is the title for all engine powered three- and fourwheeledvehicles categorized by the European Commission. Other attributes than the wheelgeometry is engine power and the vehicles unladen mass. The maximum allowed weight for athree-wheeled ULV is 1 000kg and 400kg for a four-wheeled one.By studying current crash test methods used in Europe by Euro NCAP it has beenconcluded that these tests are a good way of assessing car safety. For light-weight urbanvehicles it has been concluded that some of these tests need to be changed and that some newtest scenarios should be added when assessing road safety. The main reasons for this is linkedto that vehicle’s with a weight difference of more than 150kg cannot be compared withcurrent test methods, and that crash tests are performed with crash objects with similar orequal mass in current safety assessment programs. This correlates poorly to the trafficsituation for light-weight urban vehicles since it would most likely collide with a far heaviervehicle than itself in an accident event.To verify the actual traffic situation in urban areas, accident statistics have beenexamined closely. The research has shown that there are large differences between rural andurban areas. For instance; 66% of all severe and fatal traffic accident occurs in rural areaseven though they are less populated. Even the distribution of accident categories has showndifferent in rural and urban areas. The United Nations Economic Commission for Europe(UNECE) has defined accident categories in their database which is widely used within theEuropean Union. By comparing each accident category’s occurrence, injury and fatality rate,the most critical urban accident categories were found in the following order. 1. Collision due to crossing or turning 2. Vehicle and pedestrian collision 3. Rear-end collision 4. Single-vehicle accident 5. Other collisions 6. Head-on collision Statistics also show that of all fatally injured crash victims in urban trafficapproximately; one third is travelling by car; one third by motorcycle, moped or pedal-cycle;and one third are pedestrians. This means that unprotected road travelers correspond to twothirds of all fatal urban traffic accidents, a fact that has to be taken into account in future crashtesting of urban vehicles. With all the information gathered a total of four new crash testscenarios for light-weight urban vehicles have been presented: • Vehicle-to-vehicle side impact at 40km/h with a 1 300kg striking vehicle to evaluate theoccupant protection level of the light-weight vehicle. • Vehicle-to-motorcycle side impact at 40km/h with motorcycle rider protection evaluation. • Pedestrian protection assessment at 40km/h over the whole vehicle front and roof area. • Rigid barrier impact at 40km/h corresponding to an urban single vehicle accident with aroad side object or a collision with a heavier or similar sized vehicle.
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Shen, Hanfei M. 1979. "Novel broadband light sources and pulse generation techniques at 1.5 [mu]m." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54645.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.In title on title page, [mu] appear as lower case Greek letter. Cataloged from PDF version of thesis.
Includes bibliographical references.
A wide diversity of applications, in both fundamental science and practical technology, has come to rely on broadband optical light sources as key enabling tools. In this thesis, we investigate three devices that contribute to the generation of broadband light at 1.5 [mu]m. The first two fall into the same broader class of saturable absorber mirrors - one device was developed for low-repetition-rate sub-100-fs ultrafast lasers and the other for high-repetition- rate femtosecond lasers. The third device bypasses generating broadband light directly from a laser altogether through the use of extra-cavity spectral broadening in a novel highly nonlinear glass fiber. In the first category, ultra-broadband saturable absorber mirrors based on III/V and Si material systems were developed for ultrafast lasers. The III/V-based mirrors were designed, fabricated, characterized and implemented in a wide range of wavelengths, spanning the visible to the near-infrared. These mirrors exhibited high-reflectivity ranges of >300 nm. Implementation of these mirrors in Ti:sapphire, Cr4+:forsterite, Cr4+:YAG, and erbium-doped bismuth-oxide lasers demonstrated self-starting and stable modelocked operation. Saturable absorber mirrors were also developed for high-repetition-rate short-cavity femtosecond lasers, with modulation depths ranging from 1.7% to 11%. Post-growth proton bombardment was used to improve recovery times, and preliminary laser testing has yielded promising results, with all structures demonstrating modelocking in an erbium-doped fiber laser.
(cont.) Saturable absorber mirrors with integrated dispersion compensation were also designed with 750 fs2 of anomalous group delay dispersion at 1.5 [mu]m. Finally, a novel highly nonlinear bismuth-oxide glass fiber was used to generate smooth, controlled supercontinuum spanning 1200 to 1800 nm. With a 2-cm length and a grating pair for dispersion compensation, compression of 150-fs pulses down to 25-fs was also demonstrated.
by Hanfei M. Shen.
Ph.D.