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Dissertations / Theses on the topic 'Opticality'
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1
el, Mathus Miguel Mathus. "Tactility and opticality in contemporary abstract painting." Thesis, Goldsmiths College (University of London), 2011. http://research.gold.ac.uk/6544/.
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The thesis analyses the construction of surface in contemporary abstract painting and its broader implications, mainly in regard to Clement Greenberg's understanding of modernist painting. It considers how this issue was contended between art critics such as Greenberg and Michael Fried and artists that challenged the formalist account of painting's medium specificity through a wide range of procedures and techniques. I review Thierry de Duve's analysis of Robert Ryman's work in regard to Greenberg's understanding of modernist painting and discuss the ways in which the contest between painting and photography (since photography made painting reproducible) is central. The analysis of Ryman's work leads to a consideration of Duchamp's readymade and its significance to painting. Painting's resistance to being annexed by photography follows de Duve's contention in regard to painting-photography competitiveness where he argues that opposition to photographic reproducibility has been critical for painting since the invention of photography. At this point the historical significance of Duchamp's readymade is regarded as a repetition of the invention of photography within the domain of painting. The assertion is then that the key to contemporary abstract painting - what supports its attraction - is the manner in which the construction of surface is made through the reformulation of pictorial practices that were developed from the 1960s - such as Informel - and continue to be elaborated in a contemporary context in the works of artists like Katharina Grosse or Sergej Jensen. By considering Informel as a manifestation of a painting-photography contest I argue for its value in contemporary abstract painting as a means to further develop abstract painting's potentiality, as Katharina Grosse and Sergej Jensen do through their engagement with architectural space.
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McColm, Donna. "Opticality and the Work of Morris Louis (1912-1962)." Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/2180.
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This thesis investigates the work of Morris Louis (1912-1962) in relation to ‘opticality’, a theory developed by the prominent American art critic Clement Greenberg. Between the late 1930s and 1950s, Greenberg developed a comprehensive argument concerning the opticality, or the optical illusion, of abstract painting. This theory influenced common approaches towards Abstract Expressionist painting during the 1940s and 1950s, culminating in Greenberg’s writing on ‘Colourfield’ painting in major texts of the 1960s such as ‘Louis and Noland’ (1960). Through research into the development of Morris Louis’ technique, including several of his major series as well as lesser known works, this thesis argues that our understanding of Louis’ work has been constricted by a narrow perception of the opticality of his 'stain' paintings, and explores Louis' technique in light of alternative interpretations of his work.
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McColm, Donna. "Opticality and the Work of Morris Louis (1912-1962)." University of Sydney, 2007. http://hdl.handle.net/2123/2180.
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Master of PhilosophyThis thesis investigates the work of Morris Louis (1912-1962) in relation to ‘opticality’, a theory developed by the prominent American art critic Clement Greenberg. Between the late 1930s and 1950s, Greenberg developed a comprehensive argument concerning the opticality, or the optical illusion, of abstract painting. This theory influenced common approaches towards Abstract Expressionist painting during the 1940s and 1950s, culminating in Greenberg’s writing on ‘Colourfield’ painting in major texts of the 1960s such as ‘Louis and Noland’ (1960). Through research into the development of Morris Louis’ technique, including several of his major series as well as lesser known works, this thesis argues that our understanding of Louis’ work has been constricted by a narrow perception of the opticality of his 'stain' paintings, and explores Louis' technique in light of alternative interpretations of his work.
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Dracoulis, Wendy Fay, and wdracoulis@gmail com. "Coloured light." RMIT University. Art, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080102.093428.
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This project involves the examination of abstract, geometric paintings, kinetic sculptures, electronic art and installations that use opticality, perspectival space and colour relationships that destabilise compositional cohesion. Works made between 1964 and 1980, particularly those by Victor Vasarely and Bridget Riley are referenced in the determination of how geometric forms, colour transitions, interactions and juxtapositions have been used to suggest movement. This enquiry includes a review of the usage of planar space and the creation of optical effects. Artworks such as Bridget Riley's Chant 2, (1967) inform new works in which available digital technological processes are utilised. These new works consist mainly of compositions of line and coloured forms and are created in response to the outcomes of the research into the selected works. For example, static works that create movement through the use of colour and geometric form inform the creation of new w ork in media that uses motion. The artworks produced are installation-based works. The works include digital projections and static images that use painting processes as well as digital media. The objective of the project is to produce artworks that reference painting processes and extend explorations into colour usage designed to maximise optical effects and spatial disorientation. The artworks are intended to reflect elements researched whilst maximising the potential for using new media.
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Collett, Michael Adam. "Optically reconfigurable antennas." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723518.
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Neale, Steven Leonard. "Optically controlled microfluidics." Thesis, University of St Andrews, 2007. http://hdl.handle.net/10023/147.
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Three projects are described in this thesis that combine microfabrication techniques with optical micromanipulation. The aim of these projects is to use expertise in microlithography and optical tweezing to create new tools for Lab-on-Chip devices. The first project looks at the creation of microgears that can be moved using an optical force. The microgears include one dimensional photonic crystal that creates birefringence. This allows the transfer of angular momentum from a circularly polarised light beam to the microgear, making them spin. The microgears are simulated, fabricated and tested. Possible biological applications are suggested. The second project looks at creating microchannels to perform micromanipulation experiments in. Different methods of fabricating the microfluidic channels are compared, and the resulting chambers are used to find the maximum flow rate an optical sorting experiment can be performed at. The third project involves using a thin photoconductive layer to allow the optical control of an electrical force called dielectrophoresis. This light induced dielectrophoresis (LIDEP) allows similar control to optical tweezing but requires less irradiance than optical tweezing, allowing control over a larger area with the same input optical power. A LIDEP device is created and experiments to measure the electrical trap size that is created with a given optical spot size are performed. These three projects show different microfabrication techniques, and highlight how well suited they are for use in optical manipulation and microfluidic experiments. As the size of objects that can be optically manipulated matches well with the size of objects that can be created with microfabrication, it seems likely that many more interesting applications will develop.
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Whittam, Anne J. "Optically nonlinear materials." Thesis, Cranfield University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391585.
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Carnegie, David John. "Optically guided neuronal growth." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1860.
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In this thesis, experiments into artificially guiding neuronal growth cones using tightly focused laser beams were performed and evaluated. The experiments are performed by focusing a laser beam to the leading edge of a developing growth cone and attempting to change the direction of growth cone. These experiments were carried out using Gaussian, line and asymmetric line beam profiles. There was no noticeable change in the success rate with different beam profiles. Following this, I assisted my colleague Dr Michael Mazilu in the construction of a mathematical model of filopedia in an optical field in order to help explain the mechanism for optically guided neuronal growth which suggests that optical trapping forces on filopedia are responsible. Next, I set about implementing a system to automate the process of laser guided neuron growth by employing a spatial light modulator and a custom-built computer program. This allowed the computer to track a developing growth cone and automatically adjust the position of the laser beam as the growth cone developed. This program was successfully employed to artificially grow neuronal growth cones towards a user-inputted target point. The use of the spatial light modulator to beam shape was also demonstrated with the use of a Bessel beam being used to guide neurons for the first time. I also used a transgenic cell line of neurons to show for the first time that HSP70 is not involved in this phenomenon. This was accomplished by transfecting NG108’s with a plasmid containing HSP70 promoter tagged GFP. Under enough thermal or mechanical stress, the cells would express HSP70 which would produce a detectable GFP signal. No GFP was detected in cells after being exposed to laser irradiation of a power higher than would normally be used to guide neurons. Combined, these experiments show that the beam profile of the operating laser does not significantly affect the success of artificial growth and that the optical force on filopedia near the laser beam is likely to be the mechanism for this phenomenon. A possible heating effect of the laser has also been shown to not be strong enough to elicit a heat shock stress response from the cell. The demonstration of an automatic system which incorporates beam shaping has also been shown and such a system shows the potential to advance the investigation of artificial neuron growth using lasers.
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Maguire, Glenn E. M. "Optically responsive host systems." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482023.
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Jablonski, Amy E. "Optically modulated fluorescent proteins." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52327.
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Optical modulation has shown the selective and sensitive signal improvement in high background systems in cell imaging; however, cell applications are still limited due to biocompatibility and delivery issues. Fluorescent proteins have a variety of optically accessible states that make them ideal candidates for investigation of modulatability. Combining the optical modulation technique with the biocompatibility of fluorescent proteins is a major advance. This work focuses on evaluation fluorescent proteins and their optical states for modulation, as well demonstrations of cellular imaging. Herein, we evaluate a green fluorescent protein with interesting photophysical properties favorable for optical modulation. Positive for optical modulation, further investigation of the state dictating modulation reveals the presence of a slow component on the order of milliseconds. To better understand the mechanism responsible modulation, blue fluorescent proteins are created to modify the chromophore environment. Extraction of photophysics confirm the alteration timescales of the modulated state. Motivated by the ability to improve imaging and decode hidden dynamics, demodulation of these proteins demonstrates the selective recovery of signal in the presence of high cellular background. The continued investigation of several other fluorescent proteins identifies modulatable proteins across the visible wavelength region. Additionally, solvent environmental factors show varying timescales which, when combined with mutagenesis, suggest a cis/trans isomerization coupled with a proton transfer. This information of the properties dictating optical modulation allows for the engineering of improved modulatable proteins to study cellular dynamics.
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Symington, Keith James. "Optically interconnected computing systems." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/1128.
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Hounsell, Kyle. "Optically encoded physical keys." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/96455.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (page 56).
Lock based security has been used since the early days of human history. Whenever people have wanted to keep their possessions safe, they have used locks to hinder those who would want to access their belongings against their will. As such, an arms race has ensued, consisting of ever more complex locks, and lock-defeating methods. This thesis is not the first time that optics have been used in locking mechanisms, but it puts forth a robust, versatile, and economical security system employing optics based on the spirit of physical keys. The proposed system uses a physical key with embedded optical fibers routed between optical ports on its surface. The corresponding reader scans the key by sequentially illuminating each port, and observing where the light exits the key. The reader then builds a matrix representing the internal connections of the key, and compares it to each key's unique identifying matrix to determine whether to grant or deny access to the current user.
by Kyle Hounsell.
M. Eng.
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Collington, James Robert. "Optically accessed electronic memory." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627357.
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Cho, Hanho. "Optically Powered Logic Transistor." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2525.pdf.
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Barclay, Scott Sinclair. "The production and use of cyclohexanone monooxygenase for Baeyer-Villiger biotransformations." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325511.
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Drabik, Timothy J. "Optically interconnected parallel processor arrays." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/14795.
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Montague, Matthew. "Optically addressable nanonscale biomolecular arrays." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499977.
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Williams, Ian. "Colloids in optically defined confinement." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633436.
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Materials under spatial confinement are subject to volume exclusion conditions differing from those of a bulk material. On reducing a system to a lengthscale of the order of a few particles onc can observe new structures, modified dynamics and phase behaviour dramatically differing from that of the bulk system. Through understanding and controlling the boundaries confining a system one can alter the energy landscape it experiences. Three colloidal model systems are realised using holographic optical tweezers to investigate confinement phenomena in quasi two dimensions. ~Whereas the bulk of existing rescarch is concerned with confinement by hard boundaries, the systems presented here employ an adaptive, deformable wall or a soft confining potential. The first system, dubbed the colloidal corral consists of a circular boundary of optically trapped colloids confining additional colloids to its interior. Despite the fact that boundary curvature inhibits hexagonal ordering within this geometry, a bistability is observed between locally favoured hexagonal structures and globally preferential configurations mimicking the symmetry of the confinement. Such behaviour is not observed with hard wall confinement and is entirely due to the adaptivity of the boundary. Additionally, a novel technique for the mechanical measurement of pressure is presented, facilitated by the deformable wall. The second system introduces shear to the colloidal corral through rotation of the boundary and is known as the colloidal washing machine. The flow behaviour in this rotating confinement is investigated for a range of rotation rates. Rigid-body- like and shear melted regimes are identified and their structural behaviours characterised. The final system confines colloids within a circularly symmetric optical potential without a boundary. The result is the assembly of two-dimensional clusters, which are characterised for a range of potential widths and depths. The absence of a curved wall allows enhanced hexagonal ordering compared to the colloidal corral.
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Davies, Hilary Jane. "An optically guided atomic fountain." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4580/.
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This thesis describes the development of a laser-cooling experiment aimed at efficient transfer of cold atoms over a short distance, for loading into a conservative atom trap. We detail the construction of a 3D magneto-optical trap (MOT) and perform characterisation measurements to optimise the number and temperature of the cold atoms. The atoms are launched vertically in a fountain from the MOT using a 'moving molasses' technique and a red-detuned far-off-resonant laser beam is used to guide them into an UHV chamber. Loading into the guiding beam is optimised with respect to the beam and MOT parameters. We demonstrate a maximum loading of 20% and guiding over a distance of more than 10 cm without loss of atoms. The atoms are delivered to the UHV chamber in a cloud with a transverse dimension of order 200 µm. We discuss the extension to continuous operation of the guided atomic fountain. The 3D MOT is replaced by a funnel with 2D trapping and 3D cooling which continuously extracts the cold atoms using moving molasses. A comparison between the flux of guided atoms obtained in a pulsed fashion from the 3D MOT and continuously from the funnel indicate that the pulsed case is a factor of ten more efficient. The difference is due to inferior loading from the funnel. The optically guided fountain is used to load an optical dipole trap in the UHV chamber, using an 'optical trap door'. No additional cooling is required. The dynamics of the atoms in the optical dipole trap are studied. We discuss multiple loading of a conservative trap with the view of accumulating more atoms than can be obtained in a MOT.
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Gillanders, Ross Neil. "Optically addressed thin film sensors." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415379.
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Olyabek, Zuhair. "Digital optically coupled transient recorder." Thesis, City University London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238838.
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Guerrier, Dan. "Optically detected NMR in semiconductors." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241950.
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Amiri, M. A. "Optically nonlinear Langmuir Blodgett films." Thesis, Cranfield University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273468.
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Lam, David Tai-Yuen. "Optically implementable neural network algorithms." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385426.
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Bell, Laurence Livingstone. "Optically interrogated biosensors in microfluidics." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610215.
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Fiester, Steven E. "Characterization of Optically Active Biopolymers." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1302187683.
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Zeier, William Kovaleski Scott D. "Optically enhanced nano-forest cathodes." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/6106.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 9, 2009) Thesis advisor: Dr. Scott Kovaleski. Includes bibliographical references.
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Mestres, Junqué Pau. "Cavity optomechanics with optically trapped particles." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/460885.
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Optical trapping and manipulation have emerged as powerful tools to investigate single microscopic objects in a controlled environment. Using the momentum carried by light, forces can be exerted to confine and manipulate objects in a wide range of conditions ranging from liquid environments to high vacuum. In this thesis I implement different optical manipulation schemes to trap nano-objects and coupled them to optical cavities, giving rise to a cavity optomechanical interaction between the trapped object and the cavity mediated by the light¿s radiation-pressure.
In a first experiment I implement a mobile optical tweezer (MobOT) with nanometer precision to place a levitated silica nanosphere at the standing wave of a high Finesse Fabry-Perot cavity aiming to cool its center of mass motion to the ground state at room temperature. To attain this goal I design a two step cooling process that starts with a parametrical modulation of the optical trapping potential which pre-cools the center of mass motion along the three axis. Then driving the cavity with a red-detuned laser furthers cool the particle motion along the cavity axis via the optomechanical interaction. To monitor the particle motion in the optical trap, I implement a highly robust and sensitive detection scheme that collects the trap forward scattered field and sends it to a set of three balanced photodiodes. According to a semiclassical model I present, this approach can resolve the nanoparticle motion down to a single phonon excitation provided a shot noise limited balance detector.
I also study the use of plasmonic nanoapertures as a novel optomechanical system that increases by 10^8 the single photon optomechanical coupling strength between the trapped nanoparticle and the cavity. These experiments are performed in the overdamped regime and result into a large optomechanical interaction that allows direct measurement of dynamical modulation of the trapping potential due to the motion of the trapped object. Different detuning regimes are studied aiming to improve the optical trapping performances at low laser intensities. These findings are supported by finite element simulations.
Finally I have also made use of optical traps to perform non-equilibrium thermodynamic processes with an optically trapped microparticle in a virtual thermal bath. The virtual bath consists of an electrical white noise force. The agreement between the temperatures obtained from equilibrium and non-equilibrium measurements demonstrates the accuracy of this method. Supported by theory and simulations, our experiments highlight the importance of properly choosing the sampling rate and noise bandwidth for the validity of the method. We apply this technique to study non-equilibrium isothermal compression-expansion cycles at different temperatures ranging from room temperature to 3000K. We calculate some thermodynamic functionals for these processes such as work, heat and entropy. We show that work distributions verify the Crooks fluctuation theorem, and that they fit well to a generalized Gamma Function.L'atrapament i manipulació òptiques han esdevingut tècniques importants en la investigació d'objectes microscòpics en condicions controlades. Gràcies al moment lineal de la llum, es poden exercir forces per confinar i manipular aquests objectes en un ampli ventall de condicions que van des de líquids a alt buit. En aquesta tesi he implementat diferents tècniques de manipulació òptica per atrapar i acoblar nanopartícules a cavitats òptiques, donant lloc a una interacció optomecànica a traves de la pressió de radiació de la llum. En un primer experiment he implementat una pinça òptica mòbil amb precisió nanométrica per tal de posicionar una nanoesfera de SiO2 a l'ona estacionaria de una cavitat òptica Fabry-Perot d'alta finesa amb l'objectiu de refredar el seu centre de massa fins a l'estat fonamental. Per aconseguir aquest objectiu he dissenyat un procés de refradament en dos passos. Primer aconseguim un pre-refredament de centre de massa en les tres direccions modulant paramètricament el potencial òptic. Després, fent us de la cavitat il·luminada amb un làser desplaçat cap al vermell, aconseguim un refredament addicional en la direcció de l'eix òptic de la cavitat gràcies a la interacció optomecànica. Per registrar el moviment de la partícula a la trampa òptica, implemento un sistema de detecció interferomètrica robust i sensible que recull els fotons dispersats per la nanopartícula i els envia a tres fotodíodes balancejats. D`'acord amb un model semiclàssic que presento, aquest mètode es capaç de resoldre el moviment de la nanopartícula fins al nivell de un sol fonó sempre i quan es disposi de detectors amb soroll electrònic inferior al soroll quàntic de la trampa òptica. També estudio l'ús de nano-apertures plasmòniques com a nou sistema optomecànic que incrementa en un factor 10^8 la força d'acoblament optomecànic d'un sol fotó entre la partícula i la cavitat. Aquests experiments són realitzats en condicions sobre-esmorteïdes i aconsegueixen una interacció optomecánica prou gran com per resoldre la modulació dinàmica del potencial òptic causada pel desplaçament de la partícula atrapada. En aquest sistema estudiem diferents condicions de de-sintonització per tal de millorar el rendiment d'aquestes trampes amb potències de làser baixes. Aquests resultats els contrastem amb simulacions d'elements finits. Finalment també he fet servir trampes òptiques per estudiar processos termodinàmics fora de l'equilibri amb una micropartícula en un bany tèrmic virtual. Aquest bany tèrmic consisteix en una força electrònica amb un espectre blanc. La concordança entre les temperatures obtingudes a través de mesures en processos d'equilibri i de no-equilibri demostra precisió d'aquest mètode. Amb l'ajuda d'un model analític i de simulacions, els nostres experiments remarquen la importància d'escollir adequadament la freqüència de mostreig i del soroll per tal de garantir la validesa d'aquest mètode. Fent us d'aquesta tècnica estudiem cicles de compressió i expansió isotèrmics en el no-equilibri a temperatures que van des dels 300K als 3000K. Calculant diferents funcionals termodinàmics com el treball i el calor demostrem que les distribucions de no-equilibri satisfan el teorema de fluctuació de Crooks i que s'ajusten a adequadament a una funció Gamma generalitzada.
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Blyth, William. "Temperature measurements of optically ionised plasmas." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386826.
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Theisen, Michael John. "Polarimetric Properties of Optically Resonant Nanostructures." Thesis, University of Rochester, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3686567.
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Optically resonant nanostructures have been incorporated into a variety of devices used in a number of different fields. In this thesis, we explore optically resonant nanostructures in two forms. First we investigate a relatively new material, gallium implanted silicon (Si:Ga). We cover the fabrication process and experimentally find the optical properties as a function of both dose and wavelength. We then use the properties of this new material to create suspended arrays of Si:Ga nanowires, and determine their optical characteristics. In the second part of this thesis, we use more conventional materials and fabrication procedures to investigate the phase effects of guided mode resonators. We look at the spectral phase effects for a grating coupled silicon-on-insulator based guided mode resonator. We also look the angular phase effects of a surface plasmon polariton based guided mode resonator, comparing experimental results to theory calculated with rigorous coupled wave analysis for both cases. In addition, the guided mode resonance is modeled as a Fano resonance to gain insight into the functional form of the phase. Knowing the phase response of guided mode resonances may allow the creation of guided mode resonance based devices with higher sensitivity than traditional reflectance based devices.
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Jiad, Khalid Mohammed. "Nonlinear dynamics of optically pumped laser." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1403.
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Lacrouts, Pierre. "Synthesis of optically active A-factor." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260671.
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Hands, Michael Anthony. "Optically assisted switching and processing architectures." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412470.
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Mazal, Mohammed Jellop. "Optically scanned radio frequency field imaging." Thesis, King's College London (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266654.
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Bédard, Matthieu. "Optically addressable, integrative composite polymer microcapsules." Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/395.
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The development of remotely addressable tools to encapsulate, store and deliver active materials to living cells is a particularly challenging topic of material science. As drug delivery agents, microcontainers not only require high mechanical stability or to be delivered at target cells, but they should also possess efficient remotely addressable release mechanisms. Light responsive polyelectrolyte capsules are well suited for such purposes. Capsules are constructed using the Layer‐by‐Layer technique where oppositely charged polymers are alternatively deposited on a sacrificial template. The interest for such microcapsules lays in their versatile composition and stimuli‐responsive properties, which can be altered to suit specific needs. The primary aim of this work was to develop polymeric capsules with efficient optically addressable release mechanisms. Previous work on this topic revealed severe flaws in biological environments, especially with regards to the high energy requirements necessary for laser‐induced release and in the very limited knowledge of the fate of microcapsules in living cells. These issues were addressed by developing alternative types of light‐responsive capsules and gaining better understanding of existing ones. Three types of materials were used to sensitize microcapsules to the near‐UV, visible and near‐IR spectral regions: (1) azobenzene‐substituted polymers, (2) gold nanoparticles and (3) photocatalytic porphyrinoid dyes. Various methods were used for the characterization of microcapsules, including laser scanning confocal microscopy, colloidal probe and standard atomic force microscopy, electron microscopy, fluorescence spectrophotometry, UV‐visible spectroscopy and differential scanning calorimetry. Shells were probed for their mechanical stability as well as encapsulation and release behavior based on parameters such as: assembly strategies, shell deformability, permeability, thermal response and response to laser irradiation. This thesis begins with a brief introduction followed by an extensive literature review summarizing the various topics relevant to the work. The materials and methods used in the investigations are catalogued in Chapter 3 . Chapter 4 presents the destructive effects of pulsed UV lasing on polymeric microcapsules and introduces azobenzene‐functionalized capsules with the ability to encapsulate macromolecules by exposure to continuous wave UV light. Chapter 5 looks at the mechanical properties of capsules functionalized with gold nanoparticles as well as their remote release capabilities under near‐IR irradiation. While most of these studies were conducted ex vivo, Chapter 5 concludes with a summary of studies performed in vitro, which demonstrates that it is not only possible to release substances in living cells by light but that the latter also survive in the process. Finally, in Chapter 6, the assembly and light induced destabilization of microcapsules containing porphyrinoid dyes is presented.
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Tang, Xinke. "Optically switched quantum key distribution network." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289444.
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Encrypted data transmission is becoming increasingly more important as information security is vital to modern communication networks. Quantum Key Distribution (QKD) is a promising method based on the quantum properties of light to generate and distribute unconditionally secure keys for use in classical data encryption. Significant progress has been achieved in the performance of QKD point-to-point transmission over a fibre link between two users. The transmission distance has exceeded several hundred kilometres of optical fibre in recent years, and the secure bit rate achievable has reached megabits per second, making QKD applicable for metro networks. To realize quantum encrypted data transmission over metro networks, quantum keys need to be regularly distributed and shared between multiple end users. Optical switching has been shown to be a promising technique for cost-effective QKD networking, enabling the dynamic reconfiguration of transmission paths with low insertion loss. In this thesis, the performance of optically switched multi-user QKD systems are studied using a mathematical model in terms of transmission distance and secure key rates. The crosstalk and loss limitations are first investigated theoretically and then experimentally. The experiment and simulation both show that negligible system penalties are observed with crosstalk of -20 dB or below. A practical quantum-safe metro network solution is then reported, integrating optically-switched QKD systems with high speed reconfigurability to protect classical network traffic. Quantum signals are routed by rapid optical switches between any two endpoints or network nodes via reconfigurable connections. Proof-of-concept experiments with commercial QKD systems are conducted. Secure keys are continuously shared between virtualised Alice-Bob pairs over effective transmission distances of 30 km, 31.7 km, 33.1 km and 44.6 km. The quantum bit error rates (QBER) for the four paths are proportional to the channel losses with values between 2.6% and 4.1%. Optimising the reconciliation and clock distribution architecture is predicted to result in an estimated maximum system reconfiguration time of 20 s, far shorter than previously demonstrated. In addition, Continuous Variable (CV) QKD has attracted much research interest in recent years, due to its compatibility with standard telecommunication techniques and relatively low cost in practical implementation. A wide band balanced homodyne detection system built from modified off-the-shelf components is experimentally demonstrated. Practical limits and benefits for high speed CVQKD key transmission are demonstrated based on an analysis of noise performance. The feasibility of an optically switched CV-QKD is also experimentally demonstrated using two virtualised Alice-Bob pairs for the first time. This work represents significant advances towards the deployment of CVQKD in a practical quantum-safe metro network. A method of using the classical equalization technique for Inter-symbol-interference mitigation in CVQKD detection is also presented and investigated. This will encourage further research to explore the applications of classical communication tools in quantum communications.
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Klein, John S. M. Massachusetts Institute of Technology. "Additive manufacturing of optically transparent glass." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101831.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 90-92).
The thesis presents an Additive Manufacturing Enabling Technology for Optically Transparent Glass. The platform builds on existing manufacturing traditions and introduces new dimensions of novelty across scales by producing unique structures with numerous potential applications in product-, and architectural-design. The platform is comprised of scalable modular elements able to operate at the high temperatures required to process glass from a molten state to an annealed product. The process demonstrated enables the construction of 3D parts as described by Computer Aided Design (CAD) models. Processing parameters such as temperature, flow rate, layer height and feed rate, can be adjusted to tailor the printing process to the desired component; its shape and its properties. The research explores, defines and hard-codes geometric constraints and coiling patterns as well as the integration of various colors into the current controllable process, contributing to a new design and manufacturing space. Performed characterization of the printed material to determine its morphological, mechanical and optical properties, is presented and discussed. Printed parts demonstrated strong adhesion between layers and satisfying optical clarity. The molten glass 3D printer as well as the fabricated objects exhibited, demonstrate the production of parts which are highly repeatable, enable light transmission, and resemble the visual and mechanical performance of glass constructs that are conventionally obtained. Utilizing the optical nature of glass, complex caustic patterns were created by projecting light through the printed objects. The 3D printed glass objects and process described here, aim to contribute new capabilities to the ever-evolving history of a very challenging but limitless material - glass.
by John Klein.
S.M.
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Qian, Xin. "Optically-amplified radio-over-fibre systems." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612818.
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Torki, Amir. "Mechanical Transfer of Optically Trapped Nanoparticle." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-200901.
Full textAbstract:
In this project, a mechanical system for transferring a silica nanoparticle is designedand implemented. This system is based on a mobile optical trap which enables 3Dmanipulation of a nanoparticle in high vacuum condition. The silica nanoparticle withdiameter 177nm is trapped at ambient pressure in first chamber called loading chamberat wavelength 1565nm. Then the pressure of loading chamber is reduced by vacuumpump to 10−5−10−6mbar. The second chamber is always kept in high vacuum. There isa vacuum valve between two chambers which isolates them from each other. As we openthe valve, the pressure inside the both chambers would be equilibrated. The trappednanoparticle is transferred to the second chamber with the distance around 20-25cm inless than 20-30 seconds with macroscopic scale resolution. During this long range transfer,we are able to perform microscopic transfer due to the presence of three nanopositionersaligned with three axes. No feedback system is used to stabilize particle motion for lowerpressure.I detta master examensarbete ett mekaniskt system för överflyttning av en kiselnanopartikelär utformad och implementerad. Detta system bygger på en mobil optisk fälla sommöjliggör 3D manipulering av en nanopartikel i högt vakuumtillstånd. Kiselnanopartikelmed 177nm diameter fångas vid omgivningsryck och vid våglängden 1565nm i förstakammaren såkallad laddningskammaren. Sedan reduceras trycket i laddningskammarenmed vakuumpump till 10−5−10−6mbar. Den andra kammaren hålls alltid i högvakuum.I syfte att isolera dessa tvåkammare ifrån varandra finns det en vakuumventil emellankammarna. När ventilen öppnas trycket inne i båda kamrarna hålls i jämvikt ochden fångade nanopartikel överförs till den andra kammaren på en avståndet runt 20-25cm, på mindre än 20-30 sekunder med makroskopisk skala upplösning. Under dennalånga överföringsintervall, har vi möjlighet att utföra mikroskopisk överföring pågrundav närvaron av tre nanopositioners inriktade med tre axlar. Inget återkopplingssystem används för att stabilisera partikelrörelse för lägre tryck.
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Faradji, Charly Andre. "Optically active ligands derived from PH₃." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730899.
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Silva, Matteo. "Interactions in optically imprinted polariton lattices." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415858/.
Full textAbstract:
Microcavity exciton-polaritons results from the admixture of cavity photons and excitons in the strong coupling regime. Due to their hybrid nature, polaritons are a promising solid-state platform for both fundamental studies on light-matter interaction and applications in quantum and opto-electronics technologies. In this thesis, optically imprinted graphs of interacting polariton condensates are proposed and demonstrated to simulate universal spin models whose ground state brings about the solution of a bespoken optimisation task. The establishment, control and tailoring of a complex network of interactions across the graphs' nodes is an essential ingredient to map complex optimisation tasks to a polariton graph. Here, a method is proposed to quantify and measurecoupling strength between a pair of polariton condensates as a function of their physical separation. Furthermore, this thesis also outlines how the coupling is influenced by optically injecting a non-homogeneously polarised polariton graph.
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KRUTKO, OLEG B. "OPTICALLY SWITCHED INTEGRATED CIRCUIT POWER CONVERTERS." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973790864.
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Lai, Yi-Ying. "Injection-locked Optically Pumped Semiconductor Laser." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/577280.
Full textAbstract:
High-power, single-frequency, narrow-linewidth lasers emitting at tailored wavelength are desired for many applications, especially for precision spectroscopy. By way of a free-space resonator, optically pumped semiconductor lasers (OPSLs), a.k.a. vertical external-cavity surface-emitting lasers (VECSELs), can provide near diffraction-limited, high-quality Gaussian beams and are scalable in output power. Free space resonators also allow the insertion of the birefringent filter and the etalon to enforce single-frequency operation. In addition, the emission wavelengths of OPSLs are tailorable through bandgap engineering. These advantages above make OPSL a strong candidate of laser sources for spectroscopic applications including atomic spectroscopy as well as optical lattice clocks. In this research, a single-frequency laser source with high power is demonstrated by applying the injection-locking technique on OPSLs for the first time. The behaviors of the injection-locked OPSL are studied by varying parameters such as output coupling, injection wavelengths and injection power. It was found that the best injection wavelength is by approximately 2 nm shorter than the free-running slave laser at any given pump power. Below the lasing threshold for free-running operation, the laser starts the stimulated emission process as soon as it is pumped, working as a resonant amplifier. With proper parameters, the output power of the injection-locked laser exceeds the output power of its free-running condition. Over 9 W of single-frequency output power at 1015 nm is achieved. The output beam is near-diffraction-limited with Mₓ² = 1.04 and My² = 1.02. By analyzing the surface photoluminescence (PL) and the output performance of the laser, the saturation intensity of OPSLs is estimated to be 100 kW/cm² when the passive loss of 1.4% is assumed. The injection-locked system adds fairly low phase noise to that of the master laser. By measuring the beat note between the master laser and the injection-locked laser, the RMS values of the phase noise are 0.112 rad and 0.081 rad when using the T = 3% and T = 4% output couplers respectively.
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Mauriello, Francesco <1980>. "Optically active photoresponsive multifunctional polymeric materials." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/711/1/Tesi_Mauriello_Francesco.pdf.
Full textAbstract:
In the last year [1], Angiolini and co-workers have synthesized and investigated
methacrylic polymers bearing in the side chain the chiral cyclic (S)-3-hydroxypyrrolidine
moiety interposed between the main chain and the trans-azoaromatic chromophore,
substituted or not in the 4’ position by an electron-withdrawing group. In these materials, the
presence of a rigid chiral moiety of one prevailing absolute configuration favours the
establishment of a chiral conformation of one prevailing helical handedness, at least within
chain segments of the macromolecules, which can be observed by circular dichroism (CD).
The simultaneous presence of the azoaromatic and chiral functionalities allows the polymers
to display both the properties typical of dissymmetric systems (optical activity, exciton
splitting of dichroic absorptions), as well as the features typical of photochromic materials
(photorefractivity, photoresponsiveness, NLO properties).
The first part of this research was to synthesize analogue homopolymers and copolymers
based on bisazoaromatic moiety and compare their properties to those of the above mentioned
analogue derivatives bearing only one azoaromatic chromophore in the side chain. We
focused also the attention on the effects induced on the thermal and chiroptical behaviours by
the insertion of particulars achiral comonomers characterized by different side-chain mobility
and grown hindrance (MMA, tert-BMA and TrMA).
On the other hand carbazole containing polymers [2] have attracted much attention
because of their unique features. The use of these materials in advanced micro- and
nanotechnologies spreads in many different applications such as photoconductive and
photorefractive polymers, electroluminescent devices, programmable optical
interconnections, data storage, chemical photoreceptors, NLO, surface relief gratings, blue
emitting materials and holographic memory.
The second part of the work was focused on the synthesis and the characterization polymeric
derivatives bearing in the side chain carbazole or phenylcarbazole moieties linked to the (S)-
2-hydroxy succinimide or the (S)-3-hydroxy pyrrolidinyl ring as chiral groups covalently
linked to the main chain through ester bonds.
The last objective of this research was to design, synthesize, and characterize multifunctional
methacrylic homopolymers and copolymers bearing three distinct functional groups (i.e.
azoaromatic, carbazole and chiral group of one single configuration) directly linked in the
side chain.
This polymeric derivatives could be of potential interest for several advanced application
fields, such as optical storage, waveguides, chiroptical switches, chemical photoreceptors,
NLO, surface relief gratings, photoconductive materials, etc.
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Mauriello, Francesco <1980>. "Optically active photoresponsive multifunctional polymeric materials." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/711/.
Full textAbstract:
In the last year [1], Angiolini and co-workers have synthesized and investigated
methacrylic polymers bearing in the side chain the chiral cyclic (S)-3-hydroxypyrrolidine
moiety interposed between the main chain and the trans-azoaromatic chromophore,
substituted or not in the 4’ position by an electron-withdrawing group. In these materials, the
presence of a rigid chiral moiety of one prevailing absolute configuration favours the
establishment of a chiral conformation of one prevailing helical handedness, at least within
chain segments of the macromolecules, which can be observed by circular dichroism (CD).
The simultaneous presence of the azoaromatic and chiral functionalities allows the polymers
to display both the properties typical of dissymmetric systems (optical activity, exciton
splitting of dichroic absorptions), as well as the features typical of photochromic materials
(photorefractivity, photoresponsiveness, NLO properties).
The first part of this research was to synthesize analogue homopolymers and copolymers
based on bisazoaromatic moiety and compare their properties to those of the above mentioned
analogue derivatives bearing only one azoaromatic chromophore in the side chain. We
focused also the attention on the effects induced on the thermal and chiroptical behaviours by
the insertion of particulars achiral comonomers characterized by different side-chain mobility
and grown hindrance (MMA, tert-BMA and TrMA).
On the other hand carbazole containing polymers [2] have attracted much attention
because of their unique features. The use of these materials in advanced micro- and
nanotechnologies spreads in many different applications such as photoconductive and
photorefractive polymers, electroluminescent devices, programmable optical
interconnections, data storage, chemical photoreceptors, NLO, surface relief gratings, blue
emitting materials and holographic memory.
The second part of the work was focused on the synthesis and the characterization polymeric
derivatives bearing in the side chain carbazole or phenylcarbazole moieties linked to the (S)-
2-hydroxy succinimide or the (S)-3-hydroxy pyrrolidinyl ring as chiral groups covalently
linked to the main chain through ester bonds.
The last objective of this research was to design, synthesize, and characterize multifunctional
methacrylic homopolymers and copolymers bearing three distinct functional groups (i.e.
azoaromatic, carbazole and chiral group of one single configuration) directly linked in the
side chain.
This polymeric derivatives could be of potential interest for several advanced application
fields, such as optical storage, waveguides, chiroptical switches, chemical photoreceptors,
NLO, surface relief gratings, photoconductive materials, etc.
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Börger-Enkisch, Birgit. "Optically detected electron paramagnetic resonance of metalloproteins." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963108220.
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Mansfield, Eric. "Fabrication and characterization of optically emissive microresonators." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41120.
Full textAbstract:
Microresonators are devices that confine light in small volumes through total internal reflection. Introducing an emissive species into a microresonator allows for resonance enhanced emission at frequencies where the spectrum of the emissive species overlaps with the resonant frequencies of the microresonator. Previous research has led to a good understanding of these phenomena in 1D and 2D microresonators, but many 3D microresonator geometries have not yet been investigated. This work details the successful creation and demonstration of a cubic polymeric optical microresonator.
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Kusoglu, Sarikaya Cemre. "Optically Stimulated Luminescence Studies On Natural Fluorites." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612962/index.pdf.
Full textAbstract:
Optically Stimulated Luminescence (OSL) is the luminescence emitted from a previously irradiated insulator (or a wide band gap semiconductor) upon exposure to light. The OSL signal intensity is a function of the radiation dose absorbed by the sample and thus can be used as the basis of a radiation dosimetry method. In the literature, OSL studies on natural fluorites are rather limited. In order to promote the material for radiation dosimetry, OSL properties of natural fluorites of different origin were examined in this study. For this purpose, dose-response, reproducibility, thermal stability and fading of the OSL signals were analyzed. In order to find a relation between OSL and TL signals, TL signals and the effect of OSL measurements on TL signals were examined. Thermal activation energies of the light sensitive TL peaks and the OSL signals were also calculated using different methods and the results were compared. Also, absence of the thermal quenching was shown. Finally, TR-OSL signals were measured to have an opinion about the recombination centers. As a result of these studies, it is possible to conclude that natural fluorites show promising features to be used as an environmental dosimeter with regard to a suitable OSL signal, range of linearity, repeatability in response, as well as being readily available at a low cost.
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Episkopou, Elpida. "Reconfigurable optically-controlled waveguide for terahertz applications." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/42226.
Full textAbstract:
The development of tunable waveguide components for systems that require multifunctionality, at terahertz frequencies is investigated using the photoconductivity e ect. Specifically, by the photo-generation of free charged carriers highly conducting plasma regions are created and by changing the light pattern in real time, various tunable components can be implemented. The aim of this thesis is to present a novel reconfigurable optically-controlled terahertz waveguide switch as an illustrative example of this approach, addressing the challenges and limitations involved in simulation, implementation and measurement of such devices and is organised in the following chapters. Chapter 1 gives the background theory of the fundamental principles of optoelectronic devices and presents a literature survey of existing optically-controlled structures across a wide frequency spectrum. Chapter 2 presents a comparative study of four commercial software packages with the aim to show that it is not always straightforward to select the most appropriate boundary conditions and define a material's parameter within a software when terahertz structures are modelled. A study of various modelling approaches using commercially-available software packages has been undertaken; a number of approaches have been identified and the most appropriate solutions are indicated. Chapter 3 presents a microwave plasma switch as a proof-of-concept scaled demonstrator. In this preliminary experiment a metal pipe rectangular waveguide (similar to WR-650 standard) has been implemented, which can be reconfigured as an ON-OFF switch using a plasma column formed by commercially available discharge tubes. This provides a good starting point for more sophisticated devices as presented in the following chapters. In Chapter 4 a novel optically-controlled waveguide plasma switch for terahertz applications is presented. The switch is excited by a continuous wave (CW) laser source and the photoconductivity profile, due to the laser illumination, is described in detail. The performance of the switch is studied by means of full-wave numerical simulations and various parametric studies are undertaken to provide physical insight in the device performance. The thermal characteristics of the device are also investigated. Chapter 5 gives in detail the processing steps for the microfabrication of various prototypes with the assembly of the prototypes being also discussed. The waveguide experimental setup is described in detail and the measurement results obtained are presented. In particular, emphasis has been given on the alignment of the devices with the Vector Network Analyser waveguide heads. Finally, Chapter 6 gives a summary of the work presented in this thesis and potentially new research directions are indicated as future work.
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Shang, Alain. "Transceiver arrays for optically interconnected electronic systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ37024.pdf.
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