Dissertations / Theses on the topic 'Near-field scanning optical lithography'
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Chong, Karen S. L. "Fabrication of molecular nanostructures by scanning near-field optical (SNOM) lithography." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422175.
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Fenwick, Oliver. "Scanning near-field optical lithography and microscopy of conjugated polymer structures." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445444/.
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This thesis is concerned with the use of the scanning near-field optical microscope (SNOM) to pattern and image conjugated polymer structures. The SNOM is one of just a few optical instruments which are capable of breaking the diffraction limit which limits conventional microscopes to a resolution of approximately half a wavelength. It does so by directing light onto a sub-wavelength aperture at the apex of a probe, establishing a local evanescent field of subwavelength dimensions around the aperture. Conjugated polymers on the other hand are an interesting class of materials which have semiconducting properties and a rich photophysics making them suitable for use in novel light-emitting diodes, transistors and solar cells. I demonstrate direct patterning of several conjugated polymers using the SNOM with a resolution extending below 100 nm and attempt to explain the resolution of the lithography through simulations using the Bethe-Bouwkamp model of the field surrounding a sub-wavelength aperture. In particular the modelling focuses on the role of the film thickness and reflections from the substrate. Further experiments demonstrate that thermal effects which can be caused by heating of the SNOM probe do not play a role in lithography with the SNOM in this case. However, I demonstrate the use of a scanning thermal microscope to do a novel and purely thermal lithography on one of the same conjugated polymers. Resolutions of 120 nm are demonstrated, and finite element analysis is used to show that significant improvements in resolution should be possible by optimisation of the probe and the polymer film. In addition, I present simulations of imaging artefacts caused by topography on samples under SNOM investigation, and use the same model to look at the potential of the SNOM to obtain information about sub-surface objects. SNOM images are presented of blends and supramolecular fibres of conjugated polymers.
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Pendery, Joel S. "Nanoscale Patterning and Imaging of Liquid Crystals and Colloids at Surfaces." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396623443.
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Dvořák, Petr. "Studium vlastností povrchových plazmonových polaritonů na magnetických materiálech." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229810.
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The diploma thesis deals with the experimental study of surface plasmon polaritons (SPPs) on nano-structures with the Au/Co/Au multilayer. Plasmonic structures were prepared by the electron beam lithography and by the focused ion beam. A Scanning optical near-field microscope was used for detection of surface plasmon polaritons. SPPs were confirmed by the experiment with different polarizations of the illuminating light. Furthermore, differences in plasmon interference wavelengths was measured for different surface dielectric functions. Finally, the decantation of the SPPs interference image was measured in dependence on the external magnetic field.
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Leong, Siang Huei. "Apertureless scanning near-field optical microscopy." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615953.
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Melville, David O. S. "Planar Lensing Lithography: Enhancing the Optical Near Field." Thesis, University of Canterbury. Electrical and Computer Engineering, 2006. http://hdl.handle.net/10092/1091.
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In 2000, a controversial paper by John Pendry surmised that a slab of negative index material could act as a perfect lens, projecting images with resolution detail beyond the limits of conventional lensing systems. A thin silver slab was his realistic suggestion for a practical near-field superlens - a 'poor-mans perfect lens'. The superlens relied on plasmonic resonances rather than negative refraction to provide imaging. This silver superlens concept was experimentally verified by the author using a novel near-field lithographic technique called Planar Lensing Lithography (PLL), an extension of a previously developed Evanescent Near-Field Optical Lithography (ENFOL) technique. This thesis covers the computational and experimental efforts to test the performance of a silver superlens using PLL, and to compare it with the results produced by ENFOL. The PLL process was developed by creating metal patterned conformable photomasks on glass coverslips and adapting them for use with an available optical exposure system. After sub-diffraction-limited ENFOL results were achieved with this system additional spacer and silver layers were deposited onto the masks to produce a near-field test platform for the silver superlens. Imaging through a silver superlens was achieved in a near-field lithography environment for sub-micron, sub-wavelength, and sub-diffraction-limited features. The performance of PLL masks with 120-, 85-, 60-, and 50-nm thick silver layers was investigated. Features on periods down to 145-nm have been imaged through a 50-nm thick silver layer into a thin photoresist using a broadband mercury arc lamp. The quality of the imaging has been improved by using 365 nm narrowband exposures, however, resolution enhancement was not achieved. Multiple layer silver superlensing has also been experimentally investigated for the first time; it was proposed that a multi-layered superlens could achieve better resolution than a single layer lens for the same total silver thickness. Using a PLL mask with two 30-nm thick silver layers gave 170-nm pitch sub-diffraction-limited resolution, while for a single layer mask with the same total thickness (60 nm) resolution was limited to a 350-nm pitch. The proposed resolution enhancement was verified, however pattern fidelity was reduced, the result of additional surface roughness. Simulation and analytical techniques have been used to investigate and understand vi ABSTRACT the enhancements and limitations of the PLL technique. A Finite-Difference Time- Domain (FDTD) tool was written to produce full-vector numerical simulations and this provided both broad- and narrowband results, allowing image quality as a function of grating period to be investigated. An analytical T-matrix method was also derived to facilitate computationally efficient performance analysis for grating transmission through PLL stacks. Both methods showed that there is a performance advantage for PLL over conventional near-field optical lithography, however, the performance of the system varies greatly with grating period. The advantages of PLL are most prominent for multi-layer lenses. The work of this thesis indicates that the utilisation of plasmonic resonances in PLL and related techniques can enhance the performance of near-field lithography.
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LeBlanc, Philip R. "Dual-wavelength scanning near-field optical microscopy." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82911.
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A dual-wavelength Scanning Near-Field Optical Microscope was developed in order to investigate near-field contrast mechanisms as well as biological samples in air. Using a helium-cadmium laser, light of wavelengths 442 and 325 nanometers is coupled into a single mode optical fiber. The end of the probe is tapered to a sub-wavelength aperture, typically 50 nanometers, and positioned in the near-field of the sample. Light from the aperture is transmitted through the sample and detected in a confocal arrangement by two photomultiplier tubes. The microscope has a lateral topographic resolution of 10 nanometers, a vertical resolution of 0.1 nanometer and an optical resolution of 30 nanometers. Two alternate methods of producing the fiber probes, heating and pulling, or acid etching, are compared and the metal coating layer defining the aperture is discussed. So-called "shear-force" interactions between the tip and sample are used as the feedback mechanism during raster scanning of the sample. An optical and topographic sample standard was developed to calibrate the microscope and extract the ultimate resolution of the instrument. The novel use of two wavelengths enables the authentication of true near-field images, as predicted by various models, as well as the identification of scanning artifacts and the deconvolution of often highly complicated relationships between the topographical and optical images. Most importantly, the use of two wavelengths provides information on the chemical composition of the sample. Areas of a polystyrene film are detected by a significant change in the relative transmission of the two wavelengths with a resolution of 30 nanometers. As a biological application, a preliminary investigation of the composition of Black Spruce wood cell fibers was performed. Comparisons of the two optical channels reveal the expected lignin distributions in the cell wall.
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McNab, Sharee J. "Evanescent near-field optical lithography : overcoming the diffraction limit." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2001. http://hdl.handle.net/10092/6655.
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Concepts of optical resolution limits have been transformed in the past two decades with the development of near-field optical microscopy. Resolutions of λ/40 have been demonstrated by taking advantage of additional information present the near field of an object. These resolutions are far higher than what diffraction-limited lens-based optical systems are capable of. Attempts have been made to replicate these resolutions for lithography using a scanning probe based optical equivalent, but these systems suffer from low throughput owing to their serial nature.
A desirable alternative would be replication of all the patterns within a field in a single flood exposure in a manner similar to how optical projection lithography replicates the field of a mask, but with the additional resolution available from working in the near field. This is the basis of evanescent near-field optical lithography, the subject of this thesis. Evanescent near-field optical lithography (ENFOL) brings traditional contact lithography into the near-near field using a combination of conformable masks and ultra-thin photoresists.
This thesis describes a study of ENFOL both experimentally and via electromagnetic simulations to evaluate what the resolution limit might be. The fabrication of membrane masks is described, a key component for the ENFOL exposure. The characteristics of an ENFOL exposure using broad-band light are investigated from exposures into thick resist. These exposures demonstrate the trend of decreasing depth of field as the period of grating structures is reduced.
ENFOL's requirement of a thin imaging photoresist for high resolution lithography complicates the pattern transfer step essential to translate the photoresist image into a useful material for devices. The development of an additive pattern transfer process is described, that utilises a trilayer resist scheme to enable lift-off metallisation. NiCr gratings with periods down to 270nm have been fabricated using this process subsequent to an ENFOL exposure. Wire-grid polarisers consisting of 270nm-period NiCr gratings on glass substrates have been fabricated and their polarisation properties measured at visible wavelengths.
Simulation results of exposures of sub-wavelength grating structures are presented that investigate the fundamental limit to resolution for contact lithography techniques such as ENFOL. A full-vector, rigorous electromagnetic simulation technique, the multiple multipole program is used to provide information about the near field of subwavelength gratings. The potential for λ/20 resolution is indicated; a tantalising prospect for optical lithography and well below the diffraction limit of conventional optical projection-based lithographies. Perhaps the most critical parameter for an evanescent exposure, the depth of field, was characterised and a linear relationship shown between the depth of field and grating period. The effect of parameters such as grating duty cycle, absorber material and thickness on the exposure are observed with the intention to optimise the experimental setup.
Interesting interference phenomena are observed in simulation results for exposures. where the effective exposure wavelength is equivalent to the grating period. In particular a period halving occurs in the transverse magnetic polarisation due to interference of the first diffracted orders. A novel interference technique - evanescent interference lithography is proposed that takes advantage of an enhanced period halving at an exposure wavelength corresponding to a grating resonance.
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Sefa-Ntiri, Baah. "Embedded metal mask evanescent near field optical lithography (EMM-ENFOL)." Thesis, University of Birmingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522037.
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Wright, Alan James. "Distortion in conformable masks for evanescent near field optical lithography." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1161.
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In this thesis the in-plane pattern distortion resulting from the use of Evanescent Near Field Optical Lithography (ENFOL) masks was investigated. ENFOL is a high resolution low-cost technique of lithography that is able to pattern features beyond the diffraction limit of light. Due to its use of the evanescent near field, ENFOL requires the use of conformable masks for intimate contact. Such masks can stretch and skew as they come into contact with silicon substrates and therefore distort the high resolution features patterned on them. It was desired to measure this distortion to ascertain the patterning performance of ENFOL masks and possibly correct for any uniform distortion found. To this end a sophisticated measuring process was successfully demonstrated. This involved the use of a Raith 150 Electron Beam Lithography (EBL) system with precision laser interferometer stage and metrology software module for automated measurements. Custom software was written for the Raith to enable it to take additional measurements to compensate for electron beam drift. Processing algorithms were then employed to using the measurements to compensate for beam drift and correcting for shift and rotation systematic errors. The performance of the in-plane distortion measuring process was found to have a precision of 60nm. With the ability to measure distortion, ENFOL masks were used to pattern substrates and distortion was found to be large, on the order of 1µm. This is much larger than desired for sub 100nm patterning as is expected of ENFOL. The distortions were non-uniform patterns of localised displacements. This, the observation of Newton's rings beneath a test mask and the observation of a single particle distortion across measurements of the same mask across different loadings in the EBL pointed to particulate contamination causing the distortion. In order to prove beyond doubt that particulate contamination was the cause of the spurious distortions, mechanical modelling using the Finite Element Method (FEM) of analysis was employed. The results from this matched the distortions observed experimentally, particles 20-40µm modelling the observed distortion.
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Hillman, Christopher Wyndham John. "Scanning near-field optical microscope characterisation of microstructured optical fibre devices." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/15484/.
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This thesis details work relating to the characterisation of microstructured fibres using SPM techniques. More specifically the optical properties of the fibres have been investigated by the use of a scanning near-field optical microscope and atomic force microscopy. The SNOM was constructed and fully characterised as part of this work. The current state of research into microstructured fibre fabrication, theory and applications is currently benefitting from a great deal of interest from academia and commercial investors alike. New fibre structures are being produced at a rate previously impossible. With this increase comes a need to be able to characterise more effectively the fibres that are produced. SNOM provides a number of significant features that address this issue. In this work four recently fabricated microstructured fibres have been investigated at a number of wavelengths. In each case accurate mode pro- files have been measured and compared with resolution that would be extremely difficult to obtain with traditional mode profiling techniques. A theoretical model has also been used to predict the mode profiles. Measurements of the mode profiles after propagation in free space are presented and are compared to a theoretical beam propagation technique. An interferometric technique at 1550nm was used to image electric field amplitude and phase of the fibre modes, including results on the phase evolution of the mode as it propagates in free space.
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Yang, Seung Yun. "Imaging silver nanowire using near-field scanning optical microscope." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58761.pdf.
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Huang, Yi-ting 1976. "Investigation of tapping-mode scanning near-field optical microscope." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33777.
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A crucial part of the Scanning Near-Field Microscope (SNOM) is the distance regulation that keeps the separation of a fiber probe tip and the sample surface constant. Previously, shear-force detection was implemented. Shear-force interactions have the disadvantage of being destructive on soft sample. The implementation of an alternative tapping-mode is investigated in this thesis. In tapping-mode, the fiber tip oscillates perpendicularly to the sample surface, thus avoiding the destructive lateral shear-force.This thesis also provides a general overview of SNOM, including the theory of near-field, the definition of spatial resolution, as well as the tip-sample distance regulation. Tapping-mode feedback is implemented and discussed in comparison to traditional shear-force feedback. Both CD stamper and Polystyrene images were obtained by using tapping-mode SNOM, and compared to images taken under shear-force mode SNOM and Scanning Electron Microscope. Different factors, which affect the performance of tapping-mode SNOM are discussed.
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Hadjipanayi, Maria. "Scanning near-field optical microscopy of semiconducting nano-structures." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442754.
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Schneider, Susanne Christine. "Scattering Scanning Near-Field Optical Microscopy on Anisotropic Dielectrics." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1192105974322-82865.
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Near-field optical microscopy allows the nondestructive examination of surfaces with a spatial resolution far below the diffraction limit of Abbe. In fact, the resolution of this kind of microscope is not at all dependent on the wavelength, but is typically in the range of 10 to 100 nanometers. On this scale, many materials are anisotropic, even though they might appear isotropic on the macroscopic length scale. In the present work, the previously never studied interaction between a scattering-type near-field probe and an anisotropic sample is examined theoretically as well as experimentally. In the theoretical part of the work, the analytical dipole model, which is well known for isotropic samples, is extended to anisotropic samples. On isotropic samples one observes an optical contrast between different materials, whereas on anisotropic samples one expects an additional contrast between areas with different orientations of the same dielectric tensor. The calculations show that this anisotropy contrast is strong enough to be observed if the sample is excited close to a polariton resonance. The experimental setup allows the optical examination in the visible and in the infrared wavelength regimes. For the latter, a free-electron laser was used as a precisely tunable light source for resonant excitation. The basic atomic force microscope provides a unique combination of different scanning probe microscopy methods that are indispensable in order to avoid artifacts in the measurement of the near-field signal and the resulting anisotropy contrast. Basic studies of the anisotropy contrast were performed on the ferroelectric single crystals barium titanate and lithium niobate. On lithium niobate, we examined the spectral dependence of the near-field signal close to the phonon resonance of the sample as well as its dependence on the tip-sample distance, the polarization of the incident light, and the orientation of the sample. On barium titanate, analogous measurements were performed and, additionally, areas with different types of domains were imaged and the near-field optical contrast due to the anisotropy of the sample was directly measured. The experimental results of the work agree with the theoretical predictions. A near-field optical contrast due to the anisotropy of the sample can be measured and allows areas with different orientations of the dielectric tensor to be distinguished optically. The contrast results from variations of the dielectric tensor components both parallel and perpendicular to the sample surface. The presented method allows the optical examination of anisotropies of a sample with ultrahigh resolution, and promises applications in many fields of research, such as materials science, information technology, biology, and nanoopticsDie optische Nahfeldmikroskopie ermöglicht die zerstörungsfreie optische Unter- suchung von Oberflächen mit einer räumlichen Auflösung weit unterhalb des klas- sischen Beugungslimits von Abbe. Die Auflösung dieser Art von Mikroskopie ist unabhängig von der verwendeten Wellenlänge und liegt typischerweise im Bereich von 10-100 Nanometern. Auf dieser Längenskala zeigen viele Materialien optisch anisotropes Verhalten, auch wenn sie makroskopisch isotrop erscheinen. In der vorliegenden Arbeit wird die bisher noch nicht bestimmte Wechselwirkung einer streuenden Nahfeldsonde mit einer anisotropen Probe sowohl theoretisch als auch experimentell untersucht. Im theoretischen Teil wird das für isotrope Proben bekannte analytische Dipol- modell auf anisotrope Materialien erweitert. Während fÄur isotrope Proben ein reiner Materialkontrast beobachtet wird, ist auf anisotropen Proben zusätzlich ein Kontrast zwischen Bereichen mit unterschiedlicher Orientierung des Dielektrizitätstensors zu erwarten. Die Berechnungen zeigen, dass dieser Anisotropiekontrast messbar ist, wenn die Probe nahe einer Polaritonresonanz angeregt wird. Der verwendete experimentelle Aufbau ermöglicht die optische Untersuchung von Materialien im sichtbaren sowie im infraroten Wellenlängenbereich, wobei zur re- sonanten Anregung ein Freie-Elektronen-Laser verwendet wurde. Das dem Nahfeld- mikroskop zugrunde liegende Rasterkraftmikroskop bietet eine einzigartige Kombi- nation verschiedener Rastersondenmikroskopie-Methoden und ermöglicht neben der Untersuchung von komplementären Probeneigenschaften auch die Unterdrückung von mechanisch und elektrisch induzierten Fehlkontrasten im optischen Signal. An den ferroelektrischen Einkristallen Lithiumniobat und Bariumtitanat wurde der anisotrope Nahfeldkontrast im infraroten WellenlÄangenbereich untersucht. An eindomÄanigem Lithiumniobat wurden das spektrale Verhalten des Nahfeldsignals sowie dessen charakteristische Abhängigkeit von Polarisation, Abstand und Proben- orientierung grundlegend untersucht. Auf Bariumtitanat, einem mehrdomänigen Kristall, wurden analoge Messungen durchgeführt und zusätzlich Gebiete mit ver- schiedenen Domänensorten abgebildet, wobei ein direkter nachfeldoptischer Kon- trast aufgrund der Anisotropie der Probe nachgewiesen werden konnte. Die experimentellen Ergebnisse dieser Arbeit stimmen mit den theoretischen Vorhersagen überein. Ein durch die optische Anisotropie der Probe induzierter Nahfeldkontrast ist messbar und erlaubt die optische Unterscheidung von Gebie- ten mit unterschiedlicher Orientierung des Dielektriziätstensors, wobei eine Än- derung desselben sowohl parallel als auch senkrecht zur Probenoberfläche messbar ist. Diese Methode erlaubt die hochauflösende optische Untersuchung von lokalen Anisotropien, was in zahlreichen Gebieten der Materialwissenschaft, Speichertech- nik, Biologie und Nanooptik von Interesse ist
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Stevenson, Richard. "Scanning near-field optical microscopy (SNOM) of semiconductor nanostructures." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621756.
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Chaipiboonwong, Tipsuda. "Characterising nonlinear waveguides by scanning near-field optical microscopy." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/65528/.
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Scanning near-field optical microscopy (SNOM) has been applied to investigate the dispersion and nonlinear phenomena in a multimode Ta2O5 rectangular waveguide. Unlike the conventional approach of observing only the output spectra, the SNOM technique can collect the localised spectra from the evanescent field at various locations of the waveguide. This provides the visualisation of pulse evolution prior to the final development as the output light. The SNOM-acquired spectra consist of unique features which have not been observed before in previous nonlinear pulse propagation researches. These distinctive characteristics are attributed to the localised nature of the data and the multimode nonlinear pulse propagation. In order to understand the underlying physics of the experimental data, a numerical model simulating this SNOM visualisation has been developed. The simulation was based on the nonlinear Schrödinger equation, adapted for multimode pulses, and performed by the split-step Fourier algorithm. The spectra exhibit very fine features which can be attributed to the interference of various modes with different phase modulation owing to dispersion and nonlinear effects. Accordingly, the complexity of the spectral features increase with the propagation distance and the number of contributing modes. The multimode spectra rapidly broaden at the beginning stage of the propagation, owing to the supplementary intermodal phase modulation. Unlike the single-mode case, in which the spectral broadening caused by the self-phase modulation continuously develops along the propagation distance, the broadening process in the multimode pulse is decelerated at the later distance. This is owing to the separation of the higher-order modes and consequently the influence of the cross-phase modulation on the spectral broadening is reduced. The SNOM technique can also provide the observation of high resolution evolution of the pulse spectra. Both spectral variations along the length of the waveguide and across the waveguide are observable. Such a variation over the wavelength scale is caused by the interference of modes with different phases complexly formed by the dispersion and nonlinear effects.
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Low, Chun Hong. "Near Field Scanning Optical Microscopy(NSOM) of nano devices." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Dec/08Dec%5FLow.pdf.
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Thesis (M.S. in Combat Systems Science and Technology)--Naval Postgraduate School, December 2008.Thesis Advisor(s): Haegel, Nancy M. ; Luscombe, James. "December 2008." Description based on title screen as viewed on January 29, 2009. Sponsoring/Monitoring Agency Report Number: "DMR-0526330." Includes bibliographical references (p. 59-61). Also available in print.
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Kann, Joshua Louis. "Numerical modeling of a near-field scanning optical system." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187376.
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A near-field scanning optical (NFO) system utilizes a subwavelength sized aperture to illuminate a sample. The aperture raster scans the sample. During the scan, the aperture is held in proximity to the sample. At each sampling point, the integrated far-zone energy distribution is stored. This collection of data is used to generate an image of the sample's surface. The main advantage of NFO systems is their very high spatial resolution. In this dissertation a hybrid finite-difference-time-domain (FDTD)/angular spectrum code is used to study the electromagnetic and imaging properties of a NFO scanning system. In addition, a finite-difference thermal (FD-thermal) code is used to calculate the thermal properties of a NFO system. Various aperture/sample geometries are studied numerically using both TE and TM polarization within a two-dimensional metallic waveguide that forms the aperture. The spatial properties of the electric field emitted by the aperture with no sample present are greatly influenced by the polarization. In particular, the electric field with TM polarization exhibits sharp peaks near the corners of the aperture, while the field with TE polarization is smooth and peaked at the center of the aperture. For both polarizations, the electric field remains collimated for a distance comparable to the aperture size. The electric field for both polarizations is altered when a dielectric sample is placed in proximity to the aperture. It is shown that the most representative image of the sample's topography is obtained using TE polarization and the resulting total far-zone energy as the sampled data. It is also shown that simpler scalar methods do not accurately predict the imaging behavior of a NFO system. Under certain circumstances the relationship between the sample's topography and the detected image is nearly linear. Under these conditions a system transfer function is calculated. Using the transfer function, it is shown that the spatial resolution of a NFO system is on the order of the aperture size plus the aperture to sample spacing. Interestingly, the transfer function is object dependent. Post image equalization techniques are shown to increase system resolution. When a metallic sample is imaged, the object/image relationship is more complex than with a pure dielectric sample. In the metallic sample, signal enhancement is observed over sharp topographic features. In addition, the optical power that is absorbed in a metallic sample is converted to heat that flows throughout the sample. Thermal transfer between the tip and the sample is shown to play a smaller role in sample heating. It is shown that a wider thermal profile in the sample is obtained with TM polarization than with TE polarization. This is important in areas such as optical data storage, where an elliptically shaped data mark is predicted.
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Kershaw, Kevin Neil. "Development of scanning near-field optical microscopy for biological applications." Thesis, University of Leeds, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405591.
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Demming, Anna Linda. "Theoretical investigations into apertureless scanning near field optical microscopy systems." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429644.
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Milner, Robert George. "Scanning near field optical microscopy : aperture experiments and apertureless theory." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620218.
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SHARMA, ADITI. "A NEAR FIELD SCANNING OPTICAL MICROSCOPY INVESTIGATION OF PHOTONIC STRUCTURES." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1046725704.
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Xiao, Zhizhao. "Optical properties of zinc oxide nanostructure materials using near-field scanning optical microscopy /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202007%20XIAO.
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Froehlich, Fred Franklin. "Optical contrast mechanisms and shear force interactions in near-field scanning optical microscopy." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/187486.
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This dissertation investigates mechanisms that influence image formation in near-field scanning optical microscopy (NSOM) performed with tapered fiber aperture probes. Both the generation of optical contrast for transmission mode NSOM and the force interaction between the probe and sample that is the basis for topographic imaging by shear force microscopy (SFM) are studied. A brief introduction and review of the field of NSOM are given. The lack of understanding in the previous work of the optical and force interactions between the probe and sample is cited as the motivation for the present investigation. A theoretical model is developed that describes the linear scattering of the probe's source field by the complex transmittance of the sample. The imaging of subwavelength features is shown to arise from the spatial mixing of the evanescent waves of the probe's source field with the high spatial frequencies of the object. Calculations of the optical transfer function are presented. The shear force servo that regulates the probe-to-sample separation and facilitates the acquisition of SFM imagery is extensively analyzed. The optical detection scheme that measures the dither vibration of the probe is characterized in order to optimize the servo performance. The shear force interaction is then analyzed by modeling the probe as a simple harmonic oscillator. Measurements of the probe's resonant response while interacting with the sample reveal that the shear force is mainly frictional. The magnitude of the force is derived, and limitations on its measurement are established through analysis of the minimum detectable displacement of the probe. The servo performance is shown to be shot noise limited, as opposed to being limited by the thermal vibration noise of the probe. Experimental SFM and NSOM images of various grating structures and optical data storage materials are presented. The optical contrast mechanisms displayed in the images are identified. Linear scattering generally dominates the contrast, but some images exhibit unique near-field effects due to probe-sample interactions that lead to nonlinear imaging behavior. The origin of these interactions is the boundary conditions imposed on the probe's aperture by the sample's composition and structure.
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Quartel, John Conrad. "A study of near-field optical imaging using an infrared microscope." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313413.
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Yoxall, Edward. "Applications of scattering-type scanning near-field optical microscopy in the infrared." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23637.
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This thesis is split into two broad sections. These are defined by the various applications of scattering-type near-field optical microscopy (s-SNOM) in different parts of the electromagnetic spectrum; the near-infrared (700 - 1000nm) and the mid-infrared (6 - 10um). S-SNOM is a means of imaging surfaces at resolutions well below the diffraction limit - the level of recorded detail does not depend on the wavelength of light (as it does with traditional optical microscopy), but instead on the sharpness of a probe (usually around 10nm), meaning an image resolution approaching a thousandth of a wavelength in the mid-infrared. For the work presented in the near-infrared, the focus lies with the modelling and mapping of various plasmonic resonances supported by metallic nanostructures. These resonances have the ability to "squeeze" light into substantially sub-wavelength volumes which is useful for a variety of applications ranging from cancer treatments to molecular sensing. The mid-infrared section starts with the implementation of a pulsed quantum cascade laser (QCL) as the system's light source. This presents some instrumentation challenges as all s-SNOM imaging to date has been conducted with continuous-wave (CW) lasers. Using a pulsed laser also raises some significant signal-to-noise implications which are quantified and discussed. In terms of the experimental applications of such a setup, the first steps towards ultra-high resolution infrared chemical spectroscopy are made by studying the epithelial cells of an oesophageal biopsy. The thesis concludes with an examination of the major noise sources faced by s-SNOM, and makes a number of recommendations on how their effects can be mitigated.
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Berry, Sam. "Ultra-high spatial and temporal resolution using Scanning Near-field Optical Microscopy." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/348102/.
Full textAbstract:
Scanning near-field optical microscopy (SNOM) is a system that can image beyond the conventional diffraction limit. It does this by collecting the information contained within evanescent fields. This unique ability to image using evanescent fields also enables SNOM to directly measure the electric field distribution in waveguides, where light is guided by total internal reflection. When SNOM is used with a spectrally resolving detector, local temporal phenomena can be detected by analysing spectral interference in the spectra collected by the probe. This spectrally resolving configuration was used to directly measure inter-modal group velocity difference in a multimode ridge waveguide and, using the modes’ spatial profiles to experimentally determine the mode amplitude coefficient ratio. Such an ability to provide measurements on the local dispersion characteristics and relative modal amplitudes of guided light establishes SNOM as a route for investigating the conversion of current single mode photonic devices into multimode devices. The spectrally resolving SNOM system was also used to investigate the sources of temporal delays created by a quasi disordered scattering sample, which was based on John H. Conway’s pinwheel tiling. Whilst the measurements do not create a complete picture of the scattering phenomena in this work, suggestions for improvement are offered with the aim establishing spectrally resolving SNOM systems as tools for mapping localised temporal phenomena in disordered scattering systems.
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Hall, Jeffrey E. "Exploring photorefractive polymer-dispersed liquid crystals using near-field scanning optical microscopy /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Williamson, Ricky Lawrence. "Near-field optical and shear force microscopy : instrument development, theoretical background and applications." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296690.
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Foulkes, John Edward. "Absorbance Modulation Optical Lithography: Simulating the Performance of an Adaptable Absorbance Mask in the Near-Field." Thesis, University of Canterbury. Electrical and Computer Engineering, 2010. http://hdl.handle.net/10092/5336.
Full textAbstract:
The challenge for lithography today is to continue the reduction of feature size whilst facing severe theoretical and practical limitations. In 2006 Rajesh Menon and Hank Smith proposed a new lithography system named absorbance modulation optical lithography (AMOL) [Menon 2006]. AMOL proposed replacing the normal metal mask of a lithography system with an absorbance modulation layer (AML), made from a photochromic material. This allows, through the competition between two incident wavelengths, the creation of an adaptive absorbance mask. The AML allows intimate contact to an underlying resist and hence the optical near-field may be used to create sub-diffraction limited exposures. The aim of this thesis is to model AMOL and demonstrate the abilities and the limits of the system, particularly focusing on sub-diffraction limited imaging.
This thesis describes the construction of a vector electromagnetic simulation to explore the idea and performance of AMOL, and an exploration of the ability of AMOL to propagate sub-diffraction limited images into a photoresist. A finite element method (FEM) model was constructed to simulate the formation of apertures in the AML and light transmission through the system. Three major areas of interest were explored in this thesis; the effect of polarisation on imaging, using a plasmonic reflector layers (PRLs) to improve the depth of focus (DOF), and introducing a superlens to AMOL.
Investigations of polarisation demonstrated strong preference for a transverse magnetic (TM) polarised exposing wavelength for near-field exposures. Associated with polarisation, and supporting work with absorbance gratings, the importance of the material parameters of the AML in allowing sub-diffraction limited exposures was discussed. It was also noted that, in common with all near-field systems, the depth of focus (DOF) was poor, worse than comparable metal systems. This thesis also demonstrates that the introduction of a PRL can improve the DOF and process latitude for resist thicknesses up to 60 nm and, although performance was reduced when using a silver PRL, the substantial improvements to the DOF and process latitude make a PRL valuable for an AMOL system.
This thesis also models the superlens to an AMOL system, which theoretically allows propagation of the image in the near-field. It is demonstrated that the superlens can project an AMOL image into an underlying resist, but that this image is degraded, especially for thick and non-ideal superlenses. The superlens does have a second useful effect, as it can act as a dichroic filter; decreasing the intensity ratio in the resist by a factor of ten, overcoming issues of resist sensitivity. The superlens can allow image projection and filtering with AMOL, however improvements to the available superlens materials or changes to the AML will be needed to avoid image deterioration.
This thesis has developed the first full-vector model of an absorbance modulation optical lithography (AMOL) system. This model has been used to increase the understanding of the complex effects that go into the creation of sub-diffraction limited features with AMOL. In particular the model has been used to investigate polarisation, PRLs and superlenses in AMOL. This thesis demonstrates the ability of AMOL to create narrow apertures and sub-diffraction limited exposures in a photoresist, and describes the limitations of AMOL, including material parameters and DOF. AMOL is a new and interesting lithography technique; this thesis simulates the abilities and challenges of sub-diffraction lithography using an AMOL system.
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Dorfmüller, Jens. "Implementation of an Apertureless Scanning Near-Field Optical Microscope for the Infrared Spectrum." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-50341.
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Kolb, Paul Walter. "Cryogenic near-field scanning optical microscopy : quantum dots, charge-ordered domains, and ferromagnetic nucleation /." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1497.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Reitz, Frederick B. "Fluorescence anisotropy near-field scanning optical microscopy (FANSOM) : a new technique for biological microviscometry /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8098.
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Ube, Toru. "Orientation and Conformation of Single Polymer Chain Studied by Scanning Near-Field Optical Microscopy." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142243.
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Inglis, William. "Investigating probe-sample interactions in NSOM." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288999.
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Morrish, Dru, and DruMorrish@gmail com. "Morphology dependent resonance of a microscope and its application in near-field scanning optical microscopy." Swinburne University of Technology. Centre for Micro-Photonics, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20051124.121838.
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In recent times, near-field optical microscopy has received increasing attention for its
ability to obtain high-resolution images beyond the diffraction limit. Near-field optical
microscopy is achieved via the positioning and manipulation of a probe on a scale less
than the wavelength of the incident light.
Despite many variations in the mechanical design of near-field optical microscopes almost all rely on direct mechanical access of a cantilever or a derivative form to probe the sample. This constricts the study to surface examinations in simple sample environments. Distance regulation between the sample surface and the delicate probe
requires its own feedback mechanism. Determination of feedback is achieved through
monitoring the shift of resonance of one arm of a 'tuning fork', which is caused by the interaction of the probes tip with the Van der Waals force. Van der Waals force emanates from atom-atom interaction at the top of the sample surface. Environmental contamination of the sample surface with additional molecules such as water makes accurate measurement of these forces particularly challenging. The near-field study of
living biological material is extremely difficult as an aqueous environment is required for its extended survival. Probe-sample interactions within an aqueous environment that
result in strong detectable signal is a challenging problem that receives considerable
attention and is a focus of this thesis.
In order to increase the detectible signal a localised field enhancement in the probing region is required. The excitation of an optically resonant probe by morphology dependent resonance (MDR) provides a strong localised field enhancement. Efficient MDR excitation requires important coupling conditions be met, of which the localisation of the incident excitation is a critical factor.
Evanescent coupling by frustrated total internal reflection to a MDR microcavity provides an ideal method for localised excitation. However it has severe drawbacks if the probe is to be manipulated in a scanning process. Tightly focusing the incident illumination by a high numerical aperture objective lens provides the degree of freedom to enable both MDR excitation and remote manipulation. Two-photon nonlinear excitation is shown to couple efficiently to MDR modes due to the high spatial localisation of the incident excitation in three-dimensions. The dependence of incident excitation localisation by high numerical aperture objective on MDR efficiency is thoroughly examined in this thesis. The excitation of MDR can be enhanced by up to 10 times with the localisation of the incident illumination from the centre of the
microcavity to its perimeter.
Illuminating through a high numerical aperture objective enables the remote noninvasive
manipulation of a microcavity probe by laser trapping. The transfer of photon momentum from the reflection and refraction of the trapping beam is sufficient enough to exert piconewtons of force on a trapped particle. This allows the particle to be held and scanned in a predictable fashion in all three-dimensions. Optical trapping
removes the need for invasive mechanical access to the sample surface and provides a means of remote distance regulation between the trapped probe and the sample. The femtosecond pulsed beam utilised in this thesis allows the simultaneous induction of two-photon excitation and laser trapping. It is found in this thesis that a MDR microcavity can be excited and translated in an efficient manner. The application of this technique to laser trapped near-field microscopy and single molecule detection is of particular interest.
Monitoring the response of the MDR signal as it is scanned over a sample object enables a near-field image to be built up. As the enhanced evanescent field from the propagation of MDR modes around a microcavity interacts with different parts of the sample, a measurable difference in energy leakage from the cavity modes occurs. The definitive spectral properties of MDR enables a multidimensional approach to imaging and sensing, a focus of this thesis. Examining the spectral modality of the MDR signal
can lead to a contrast enhancement in laser trapped imaging. Observing a single MDR mode during the scanning process can increase the image contrast by up to 1:23 times compared to that of the integrated MDR fluorescence spectrum.
The work presented in this thesis leads to the possibility of two-photon fluorescence
excitation of MDR in combination with laser trapping becoming a valuable tool in near-
field imaging, sensing and single molecule detection in vivo. It has been demonstrated
that particle scanned, two-photon fluorescence excitation of MDR, by laser trapping 'tweezers' can provide a contrast enhancement and multiple imaging modalities. The spectral imaging modality has particular benefits for image contrast enhancements.
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Mannelquist, Anders. "Near-field scanning optical microscopy and fractal characterization with atomic force microscopy and other methods /." Luleå, 2000. http://epubl.luth.se/1402-1544/2000/40/index.html.
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Vilain, S. "Characterisation of plasmonic crystals and integrated photonic devices with hyperspectral scanning near field optical microscopy." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557848.
Full textAbstract:
Plasmonic nanostructures are an important class of nanophotonic components capable of localising light near a metal interface on subwavelength scales. Surface plasmon polaritons (SPPs) are confmed to the metal interface and can only be studied in the past in the far-field by indirect investigation of the light resulting from their scattering. They can be studied directly using optical near-field microscopy which is capable of detecting the optical field in proximity to the surface, with sub-wavelength spatial resolution. We have developed a new tool for the investigation of surface plasmonic polaritons in a broad spectral range, the hyperspectral scanning near- field optical microscope, capable of simultaneously recording multiple near-field images in the 500-800nm spectral wavelength range. Using this microscope, the Bloch mode formation in plasmonic crystals, periodically structured metal films, have been studied along with the SPP excitation by the crystals. The role of the film thickness and crystal lattice has been studied in both the far-field and near-field. Novel plasmonic crystals with exotic lattices have been designed which provides additional advantages over the standard square lattice crystals in terms of band structure engineering and designing flat SPP bands, advantageous for applications in light extraction and unidirectional transmission. SNOM has then been used to demonstrate the new plasmonic platform based on VCSEL light source, showing direct SPP excitation on the laser surface and their efficient guiding. Multimode and single mode waveguides, Y -splitters and Mach-Zehnder interferometer configurations wen: realised. Plasmonic waveguide-ring resonators were studied incorporating non linear optical materials and optical switching has been demonstrated. The developed hyperspectral SNOM is a powerful technique for understanding the optical properties of plasmonic nanostructures and evaluating their nanophotonic capabilities. The studied plasmonic components, such as plasmonic crystals, integrated plasmonic waveguides and ring- resonator exhibit unique optical properties that pave the way for applications in photonic device optimisation and developing new concepts of signal guiding and manipulation.
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Farace, Giosi. "Biophysical applications of near-field scanning optical microscopy and the development of protein micro-patterns." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312241.
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Walker, Kelly-Ann D. "Scanning near-field optical microscopy studies of cell membrane proteins labelled with fluorescent quantum dots." Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa43114.
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Scanning near-field optical microscopy (SNOM) has been employed to simultaneously acquire high-resolution fluorescence images along with shear-force atomic force microscopy of cell membranes. Implementing such a technique overcomes the limits of optical diffraction found in standard fluorescence microscopy and also yields vital topographic information. However, one of the biggest challenges of imaging fluorescent biological specimens with SNOM, is the photostability and low yield of fluorescent labelling agents. Semiconductor quantum dots are a recently developed class of fluorophores which exhibit superior optical properties. They are significantly brighter and more resistant to photo-degradation than organic fluorophores. In this study, SNOM has been utilised in conjunction with quantum dot labelling to interrogate the biomolecular composition of cell membranes. The technique has been applied to investigate cell-cell adhesion in human epithelial cells. This has been realised through immunofluorescence labelling of the cell-cell adhesion protein E-cadherin. Moreover, a dual labelling protocol has been optimised to facilitate a comparative study of the adhesion mechanisms, and the effect of aberrant adhesion protein expression, in both healthy and cancerous epithelial cells. This study reports clear differences in the morphology and phenotype of healthy and cancerous cells. In healthy prostate epithelial cells (PNT2 cells), Ecadherin was predominantly located along the cell periphery and within filopodial protrusion. The presence of E-cadherin appeared to be enhanced when cell-cell contact was established. Furthermore this study has revealed the interactions of filopodia and their functional relationship in establishing adherens junctions in PNT2 cells. In contrast, examination of metastatic prostate cancer cells (PC-3 cells) revealed E-cadherin to be predominantly localised around the nuclear region of the cell, with no E-cadherin labelling around the periphery of the cells. This lack of functional E-cadherin in PC-3 cells coincided with a markedly different morphology and PC-3 cells were not observed to form tight cell-cell associations with their neighbours. Facilitated by the high-resolution imaging afforded by the SNOM technique, this research further highlights the important role th at E-cadherin plays in the development of invasive, metastatic cancers.
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Simpson, Stephen Hugh. "A computational study of the contrast and imaging properties of the scanning near field optical microscope." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393090.
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Gates, James Christopher. "Measurement of the local optical phase and amplitude in photonic devices using scanning near-field microscopy." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/15469/.
Full textAbstract:
This thesis presents the optical characterisation of various photonic devices using scanning near-field microscopy (SNOM). The SNOM technique has a unique capability of achieving a resolution beyond the diffraction limit. Placing the SNOM into the arm of a heterodyne interferometer also enables the measurement of both the optical phase and amplitude in the near infrared. In this work three different photonic devices are investigated. The optical field distribution within a fibre Bragg grating is investigated as a function of wavelength. This work details the direct observation of the spatial shift of the standing wave across the stop band of a fibre grating. The shift is an explicit feature of fibre Bragg gratings and has previously only been theoretically predicted. The thesis also details three analytical techniques for measuring the microscopic loss of planar or channel waveguides. Two of the techniques are experimentally tested. The techniques exploit a standing wave generated within the waveguide, the visibility of the standing wave provides sufficient information to determine to loss between two points. The present limitations of the techniques are presented. The SNOM technique has also been applied to the measurement of a large mode holey fibre. The work details the accurate characterisation of the mode at the end face of the fibre and as it propagates into free space. The results are compared to theoretically predicted modes.
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Shang, Guangyi. "Development of a shear force scanning near-field optical microscope for biological applications: imaging ans spectroscopy." Reims, 2004. http://www.theses.fr/2004REIMS005.
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Un microscope à champ proche optique basé sur un nouveau senseur de force fonctionnant dans le mode cisaillement a été développé. Il peut être combiné à un microspectrofluorimètre confocal laser pour des applications biologiques et utilisé dans différents modes de fonctionnement. Le mécanisme de détection des forces de cisaillement a été expérimentalement étudié. Il s'avère que l'origine principale de ce mécanisme est le contact intermittent de la sonde avec la surface de l'échantillon qui permet de contrôler la distance pointe-surface. Les paramètres expérimentaux concernant l'imagerie ainsi que les artefacts dus à la géométrie de la sonde sont discutés. Des images en champ proche optique d'un réseau de silicium dans le mode réflexion ainsi que la spectroscopie de structures électroluminescentes dans le mode collection ont été respectivement obtenues. Comme étude préliminaire pour des applications biologiques, la distribution de P-glycoprotéines dans la membrane plasmatique de petites cellules cancéreuses de langue humaine a été étudiée avec une résolution inférieure à la limite de résolution due à la diffraction. Cette distribution n'est pas homogène et se présente sous forme de petits amas. De plus, des spectres de fluorescence ont été obtenus sur des cellules cancéreuses du poumon humain colorées avec la sonde fluorescente JC-1. Des variations dans le spectre de fluorescence ont été mises en évidence avec une résolution verticale de l'ordre de 100 nm. Ces résultats suggèrent que notre système est un outil d'investigation prometteur pour des applications biologiques, capable de fournir des informations dignes d'intérêt permettant de mieux comprendre certains problèmes biologiquesBased on a new force sensor, a shear force scanning near-field optical microscope (ShF-SNOM), that can be operated in the different modes and combined with a confocal laser microspectrofluorometer (CLMF) for biological applications, has been developed. Shear force mechanism was experimentally studied and the knocking mechanism is the main origin responsible for shear force distance control in our system. Experimental parameters concerning the shear force imaging and artifacts due to probe geometric effects are discussed. Shear force and near-field imaging of a silicon grating in the reflection mode, imaging and spectroscopy of electroluminescent structures in the collection mode are demonstrated respectively. As a preliminary study for biological applications, the distribution of P-glycoprotein (P-gp) in the plasma membrane of human small cell lung cancer cells were investigated with sub-diffraction limit resolution. The distribution of P-gp in the cell membrane was found to be not homogenous and cluster formation of P-gp in the membrane was observed. In addition, fluorescence spectra were recorded in a single living cell of human breast adenocarcinoma cells stained with the fluorescent dye JC-1. The variations in fluorescence spectra were measured with vertical resolution of about 100 nm. These results suggest that our system would be a promising tool for biological applications and provide valuable information for understanding some biological problems
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Mills, John David. "An investigation of phase-mask diffraction patterns and fibre Bragg gratings with scanning near-field optical microscopy." Thesis, University of Southampton, 2001. https://eprints.soton.ac.uk/15492/.
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In recent years, near-field microscopy has been utilized for assessing the properties of optical wave-guides at an increasing rate. Here, a Scanning Near-field Optical Microscope (SNOM) has been designed and constructed in order to expand this work into an analysis of the optical and structural properties of fibre Bragg gratings, which are used throughout the optical fibre telecommunications network. By imaging the evanescent fields of Bragg gratings, a characterization technique has been developed which has enabled the acquisition of sub-wavelength information about the optical field distribution within a fibre grating and its refractive index structure. Six separate fibre grating samples have been examined, demonstrating the feasibility of the developed scanning technique to become a useful characterization tool. In particular, the study has enabled grating standing wave fringes to be imaged relative to corresponding refractive index fringes, for the first time. The SNOM has also been utilized to map free-space diffraction patterns close to a phase-mask (transmission diffraction grating). The patterns are normally used to create fibre gratings via UV photosensitivity mechanisms. The field distributions have been imaged under various experimental conditions and have revealed some of the technical problems that might occur during the writing of gratings. The measured patterns have also served to confirm existing diffraction grating theory, which has been expanded during the course of this work to produce a new expression for the 'Talbot length', originally formulated by Rayleigh in 1881.
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Teetsov, Julie Ann. "Photophysical characterization and near-field scanning optical microscopy of dilute solutions and ordered films of alkyl-substituted polyfluorenes /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004384.
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Craig, Timothy. "The development of infrared scanning near-field optical microscopy for the study of cancer and other biological problems." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3004490/.
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Nowak, Derek Brant. "The Design of a Novel Tip Enhanced Near-field Scanning Probe Microscope for Ultra-High Resolution Optical Imaging." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/361.
Full textAbstract:
Traditional light microscopy suffers from the diffraction limit, which limits the spatial resolution to λ/2. The current trend in optical microscopy is the development of techniques to bypass the diffraction limit. Resolutions below 40 nm will make it possible to probe biological systems by imaging the interactions between single molecules and cell membranes. These resolutions will allow for the development of improved drug delivery mechanisms by increasing our understanding of how chemical communication within a cell occurs. The materials sciences would also benefit from these high resolutions. Nanomaterials can be analyzed with Raman spectroscopy for molecular and atomic bond information, or with fluorescence response to determine bulk optical properties with tens of nanometer resolution. Near-field optical microscopy is one of the current techniques, which allows for imaging at resolutions beyond the diffraction limit. Using a combination of a shear force microscope (SFM) and an inverted optical microscope, spectroscopic resolutions below 20 nm have been demonstrated. One technique, in particular, has been named tip enhanced near-field optical microscopy (TENOM). The key to this technique is the use of solid metal probes, which are illuminated in the far field by the excitation wavelength of interest. These probes are custom-designed using finite difference time domain (FDTD) modeling techniques, then fabricated with the use of a focused ion beam (FIB) microscope. The measure of the quality of probe design is based directly on the field enhancement obtainable. The greater the field enhancement of the probe, the more the ratio of near-field to far-field background contribution will increase. The elimination of the far-field signal by a decrease of illumination power will provide the best signal-to-noise ratio in the near-field images. Furthermore, a design that facilitates the delocalization of the near-field imaging from the far-field will be beneficial. Developed is a novel microscope design that employs two-photon non-linear excitation to allow the imaging of the fluorescence from almost any visible fluorophore at resolutions below 30 nm without changing filters or excitation wavelength. The ability of the microscope to image samples at atmospheric pressure, room temperature, and in solution makes it a very promising tool for the biological and materials science communities. The microscope demonstrates the ability to image topographical, optical, and electronic state information for single-molecule identification. A single computer, simple custom control circuits, field programmable gate array (FPGA) data acquisition, and a simplified custom optical system controls the microscope are thoroughly outlined and documented. This versatility enables the end user to custom-design experiments from confocal far-field single molecule imaging to high resolution scanning probe microscopy imaging. Presented are the current capabilities of the microscope, most importantly, high-resolution near-field images of J-aggregates with PIC dye. Single molecules of Rhodamine 6G dye and quantum dots imaged in the far-field are presented to demonstrate the sensitivity of the microscope. A comparison is made with the use of a mode-locked 50 fs pulsed laser source verses a continuous wave laser source on single molecules and J-aggregates in the near-field and far-field. Integration of an intensified CCD camera with a high-resolution monochromator allows for spectral information about the sample. The system will be disseminated as an open system design.
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Zhang, Peng. "Development of a near-field scanning optical microscope and its application in studying the optical mode localization of self-affine Ag colloidal films." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35379.pdf.
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Cotton, Daniel Vincent. "Near-Field Scanning Optical Lithography for Nanostructuring Electroactive Polymers." Thesis, 2007. http://hdl.handle.net/1959.13/30678.
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Research Doctorate - Doctor of Philosophy (PhD)The photochemistry of poly{p-phenylene[1-(tetrahydrothiophen-1-io)ethylene chloride]} (PPTEC), a water soluble precursor of the semiconducting polymer, poly{p-phenylenevinylene} (PPV), has been studied both under atmospheric conditions and in environments devoid of oxygen. UV-visible spectroscopy and photoluminescence data has been used to provide a picture of the mechanistic pathways involved in UV irradiation of the PPTEC material. A new quantitative model for the effect of UV irradiation upon film morphology is presented. The technique of near-field scanning optical lithography (NSOL) has been used to produce arbitrary structures of the semi-conducting polymer poly{p-phenylenevinylene} at sizes comparable with optical wavelengths. Structures on this scale are of interest for integrated optical devices and organic solar cells. The structures are characterised using AFM and SEM and examined in the context of the electric field distribution at the NSOM tip. The Bethe-Bouwkamp model for electric field distribution at an aperture has been used, in combination with the developed model for precursor solubility dependence on UV energy dose, to predict the characteristics of lithographic features produced by NSOL. Fine structure in the lithographic features that are characteristic of the technique are investigated and their origins explained. Suggestions for the improvement of the technique are made. Presented here for the first time is a device manufactured by the technique of NSOL functioning as an optical device. The technique of NSOL is used to manufacture an optical transmission phase grating (or phase mask) of PPV, this was done as a proof of concept for device manufacture by this method and to demonstrate the potential usefulness of the unique characteristics of the technique. The phase mask was characterised using AFM and SEM and examined in the context of how well a diffraction pattern matches with theoretical calculations.