To see the other types of publications on this topic, follow the link: Scanning Near-field Optical Microscopy (SNOM).
Dissertations / Theses on the topic 'Scanning Near-field Optical Microscopy (SNOM)'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Scanning Near-field Optical Microscopy (SNOM).'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
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.
Full text
2
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.
Full textAbstract:
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
3
Raval, Meera. "Development of novel distance control methods for the scanning near-field optical microscope (SNOM) to reliably image biological samples in liquids." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621239.
Full text
4
Rothery, Alison Melinda. "Development of a novel light source for use in a scanning ion conductance-scanning near-field optical microscope (SICM-SNOM) for imaging of biological samples." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619813.
Full text
5
Bobek, Juraj. "Příprava a testování SNOM sond speciálních vlastností." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402582.
Full textAbstract:
Fotonická krystalická vlákna (PCF) představují slibný nástroj pro spojení technik známých z mikroskopie rastrovací sondou, elektronové mikroskopie a systémů pro vstřikování plynu. Přivedení světla a přenos pracovního plynu současně do blízkosti vzorku umístěného uvnitř elektronového mikroskopu přináší nové možnosti experimentů. PCF by mohly být použity nejen k charakterizaci nebo modifikaci struktur na mikroskopické úrovni, ale také k jejich výrobě. Tato práce se zabývá výzkumem literárních zdrojů s tématikou fotonických krystalů s důrazem na PCF. Leptání PCF pomocí kyseliny fluorovodíkové bez poškození jejich vnitřní struktury je experimentálně studováno s velkou precizností. Optické vlastnosti závislé na geometrii PCF jsou testovány pro různé modifikace PCF. Dále se práce zabývá spojením PCF s mikroskopií atomárních sil a následnou integrací do elektronového mikroskopu.
6
Xie, Zhihua. "Fiber-integrated nano-optical antennas and axicons as ultra-compact all-fiber platforms for luminescence detection and imaging down to single nano-emitters." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2046/document.
Full textAbstract:
Ma thèse concerne le développent de systèmes ultra compactes auto-alignés et à faible coût intégréssur fibre optique monomode pour la collection fibrée de la luminescence locale. Dans un premiertemps, un axicon fibré auto-aligné (AXIGRIN) est proposé permettant de fournir la première imagerierésolue ultra-compacte fibrée de quantum dots PbS infrarouges. Ensuite, la première nano-imagerie(système entièrement fibrée) de quantum dots PbS uniques est réalisée à l’aide d’une nano-antenneà ouverture bowtie intégrée sur pointe fibrée. Enfin, le concept d’≪antenne cornet≫ nano-optiqueest proposé pour le couplage direct et efficace de la luminescence excitée par rayons X à une fibreoptique, dans le but de générer les premiers capteurs et dosimètres fibrés à rayons XMy thesis is devoted to develop ultra-compact, plug-and-play and low-cost single-mode optical fibersystems for in-fiber luminescence collection. First, a new fiber self-aligned axicon is proposed toprovide the first resolved infrared fluorescence imaging of PbS quantum dots in far field. Then,all-fiber near-field imaging of single PbS quantum dots is achieved by double resonance bowtienano-aperture antenna (BNA) with nanometer resolution. Finally, the concept of fiber nano-opticalhorn antenna is proposed for in-fiber X-ray excited luminescence out-coupling, with the purpose ofgenerating the first generation of fiber X-ray sensors and dosimeters
7
Foubert, Kevin. "Etude en champ proche optique de structures nanophotoniques couplées." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOS091.
Full textAbstract:
Depuis une vingtaine d’années, l’optique bénéficie des avancées considérables de la microélectronique.Ainsi, il est maintenant possible de produire, guider, confiner ou encore ralentirla lumière sur puce à une échelle sub-longueur d’onde. Dans cette thèse, nous étudions de telscomposants par l’intermédiaire d’un microscope en champ proche optique (SNOM).La première partie présente une vision d’ensemble de la situation actuelle en nanophotoniqueintégrée sur substrat diélectrique. Elle expose plusieurs enjeux et faits marquants récents dansce domaine. Elle introduit également le principe physique et le fonctionnement d’un SNOMdans les grandes lignes.La seconde partie est consacrée à la microscopie en champ proche optique d’un point devue instrumental. Après une analyse physique, nous détaillons le montage de notre propremicroscope sur le banc de caractérisation optique du laboratoire, avant d’analyser la formationdes images optiques obtenues avec cette technique.La troisième partie concerne l’étude de guides d’onde couplés en Silicium sur isolant (SOI),dans lesquels s’intègrent des nano-cavités optiques. Les phénomènes de couplage par recouvrementde champs évanescents sont étudiés numériquement et analytiquement. L’analyse de cesstructures grâce au SNOM nous a permis d’une part de vérifier la validité de ces modèles, etd’autre part d’observer directement le guidage et le confinement de la lumière dans un milieude faible indice de réfraction. Nous montrons cependant que ces résultats restent très sensiblesaux aléas de fabrication. Enfin, nous mettons en évidence grâce au SNOM et à des mesuresspectrales que la description de structures de N cavités juxtaposées peut être approchée par lathéorie des modes couplésSince the end of the XXth century, optics benefits from significant breakthrough comingfrom the micro-electronic technologies. It is thus now possible to produce, guide, slow downor even trap light on a chip at a sub-wavelength scale. In this thesis, we study such opticalcomponents thanks to a Scanning Near-Field Optical Microscope (SNOM).The first part exposes an overall view of the current situation in the field of dielectricsubstrate integrated nanophotonics. Some of the recent outstanding issues and results are hereintroduced, as well as the general principle and the necessary tools to operate a SNOM.The second part is dedicated to optical near-field microscopy, technically speaking. Thephysical rules are here developed. Then we detail the instrumental set up of our own SNOMon our optical characterization bench. We end by analysing the optical images formation witha SNOM.The third part bears upon the study of Silicon-on-Insulator (SOI) coupled waveguides whereoptical nano-cavities could be inserted, by resorting to the previously implemented SNOM.Overlapping evanescent fields induced coupling phenomena are numerically and analyticallystudied. The use of the SNOM allowed us here to check the validity of our models. Besides,we have directly observed thanks to this instrument the guiding and confinement of light ina low refractive index media. However, we show that this phenomenon is highly subjected tofabrication uncertainties. Finally, we use the SNOM and spectral measurements in order todemonstrate that systems of N coupled nanocavities could be described with a simple coupledmodes model
8
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.
Full text
9
Neacsu, Corneliu Catalin. "Tip-enhanced near-field optical microscopy." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16284.
Full textAbstract:
Die vorliegende Arbeit beschreibt neue Entwicklungen im Verständnis und in der Umsetzung der optischen Nahfeldmikroskopie (scattering - type scanning near-field optical microscopy, s-SNOM) für die lineare und nichtlineare optische Bildgebung mit ultrahoher Auslösung und Empfindlichkeit. Die fundamentalen Mechanismen, die der Feldverstärkung am Ende von ultrascharfen metallischen Spitzen zugrunde liegen, werden systematisch behandelt. Die plasmonischen Eigenschaften der Spitze wurden erstmalig beobachtet, und ihre Bedeutung für die optische Kopplung zwischen Spitze und Probe sowie für die sich ergebende Einengung des Nahfeldes wird diskutiert. Ein aperturloses Nahfeldmikroskop für die spitzenverstärkte Ramanspektroskopie (tip-enhanced Raman spectroscopy, TERS) wurde entwickelt. Die Grundlagen der TERS und die wesentliche Rolle des plasmonischen Verhaltens der Spitze sowie die klare Unterscheidung von Nahfeld-Ramansignatur und Fernfeld-Abbildungsartefakten werden beschrieben. Nahfeld Raman Verstärkungsfaktoren von bis zu 10 wurden erreicht, was einer Feldverstärkung von bis zu 130 entspricht und Raman-Messungen bis auf Einzel-Molekül-Niveau ermöglichte. Die optische Frequenzverdopplung (second harmonic generation, SHG) an einzelnen Spitzen wurde untersucht. Aufgrund ihrer teilweise asymmetrischen Nanostruktur erlauben die Spitzen eine klare Unterscheidung von lokalen Oberflächen und nichtlokalen Volumenbeiträgen zur nichtlinearen Polarisation sowie die Analyse ihrer Polarisations- und Emissions-Auswahlregeln. Die spitzenverstärkte Frequenzverdopplungs-Spektroskopie und die räumlich hoch aufgelöste Abbildung auf Basis des dielektrischen Kontrasts werden demonstriert. Mit Hilfe einer phasen-sensitiven, Selbst-homodyn-Frequenzverdopplungs-s-SNOM-Abbildungsmethode kann die Oberflächen-Struktur der intrinsischen 180-Domänen im hexagonal multiferroischen YMnO aufgelöst werden.This thesis describes the implementation of scattering-type near-field optical microscopy (s-SNOM) for linear and nonlinear optical imaging. The technique allows for optical spectroscopy with ultrahigh spatial resolution. New results on the microscopic understanding of the imaging mechanism and the employment of s-SNOM for structure determination at solid surfaces are presented. The method relies on the use of metallic probe tips with apex radii of only few nanometers. The local-field enhancement and its dependence on material properties are investigated. The plasmonic character of Au tips is identified and its importance for the optical tip-sample coupling and subsequent near-field confinement are discussed. The experimental results offer valuable criteria in terms of tip-material and structural parameters for the choice of suitable tips required in s-SNOM. An near-field optical microscope is developed for tip-enhanced Raman spectroscopy (TERS) studies. The principles of TERS and the role of the tip plasmonic behavior together with clear distinction of near-field Raman signature from far-field imaging artifacts are described. TERS results of monolayer and submonolayer molecular coverage on smooth Au surfaces are presented. Second harmonic generation (SHG) from individual tips is investigated. As a partially asymmetric nanostructure, the tip allows for the clear distinction of local surface and nonlocal bulk contributions to the nonlinear polarization and the analysis of their polarization and emission selection rules. Tip-enhanced SH microscopy and dielectric contrast imaging with high spatial resolution are demonstrated. SHG couples directly to the ferroelectric ordering in materials and in combination with scanning probe microscopy can give access to the morphology of mesoscopic ferroelectric domains. Using a phase sensitive self-homodyne SHG s-SNOM imaging method, the surface topology of 180 intrinsic domains in hexagonal multiferroic YMnO is resolved.
10
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.
Full textAbstract:
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.
11
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.
Full text
12
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.
Full text
13
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.
Full textAbstract:
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.
14
Chaipiboonwong, Tipsuda. "Characterising nonlinear waveguides by scanning near-field optical microscopy." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/65528/.
Full textAbstract:
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.
15
Siry, Pierre. "Développement d'un dispositif d'acoustique picoseconde en microscopie optique de champ proche pour l'étude des propriétés élastiques de nano-objets." Paris 6, 2002. http://www.theses.fr/2002PA066339.
Full text
16
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.
Full text
17
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.
Full text
18
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.
Full text
19
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.
Full text
20
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/.
Full textAbstract:
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.
21
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.
Full text
22
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.
Full textAbstract:
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.
23
Gallina, Pavel. "Využití kovové sondy pro ovládání optických procesů a zobrazování v blízkém poli." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382288.
Full textAbstract:
Hlavním předmětem této diplomové práce jsou elektromagnetické simulace pomocí metody konečných prvků (FEM) k vyšetření vlivu grafenu na hrotem zesílenou Ramanovu spektroskopii (TERS) a povrchem zesílenou infračervenou absorpční spektroskopii (SEIRA) a k prozkoumání citlivosti sondy skenovacího optického mikroskopu blízkého pole (SNOM) ke složkám elektromagnetického pole v závislosti na parametrech sondy (průměru apertury v pokovení). Nejprve je proveden výpočet TERS systému složeného ze stříbrného hrotu nacházejícího se nad zlatým substrátem s tenkou vrstvou molekul, jehož účelem je porozumění principů TERS. Poté je na molekuly přidána grafenová vrstva, aby se prozkoumal její vliv ve viditelné (TERS) a infračervené (SEIRA) oblasti spektra. Druhá část práce se zabývá výpočty energiového toku SNOM hrotem složeným z pokoveného skleněného vlákna interagujícím s blízkým polem povrchových plasmonových polaritonů. Zde uvažujeme zlatou vrstvu se čtyřmi štěrbinami uspořádanými do čtverce na skleněném substrátu sloužícími jako zdroj stojatého vlnění povrchových plasmonů s prostorově oddělenými maximy složek elektrického pole orientovanými rovnoběžně či kolmo na vzorek. Ve výpočtech hrotem zesílené spektroskopie zjišťujeme, že grafen přispívá pouze malým dílem k zesílení pole ve viditelné oblasti spektra, ovšem v infračervené oblasti má grafen vliv pro záření s energií menší než dvojnásobek Fermiho energie grafenu, pro kterou je hodnota zesílení pole větší než v případě výpočtu bez grafenu. Avšak pro velmi vysoké vlnové délky zesílení pole v přítomnosti grafenu klesá pod (konstantní) hodnotu pro případ bez grafenu. Při studiu citlivosti SNOM hrotu k jednotlivým složkám pole shledáváme, že pro hrot se zlatým pokovením je energiový tok skleněným jádrem hrotu kombinací příspěvků energie prošlé aperturou a periodické výměny energie mezi povrchovým plasmonem šířícím se po vnějším okraji pokovení a mody propagujícími se v jádře. Dále zjišťujeme, že hroty s malou aperturou (či bez apertury) jsou více citlivé na složku elektrického pole orientovanou kolmo ke vzorku (rovnoběžně s osou hrotu), zatímco hroty s velkou aperturou sbírají spíše signál ze složky rovnoběžné s povrchem vzorku. V případě hrotu s hliníkovým pokovením jsou hroty citlivější ke složce pole rovnoběžné s povrchem, což je způsobeno slabším průnikem pole skrze pokovení.
24
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.
Full textAbstract:
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.
25
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.
Full text
26
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.
27
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.
Full text
28
Mourched, Bachar. "Fabrication d'une sonde pour le champ proche optique en technologie sol-gel." Thesis, Montpellier 2, 2012. http://www.theses.fr/2013MON20008/document.
Full textAbstract:
L'utilisation de la microscopie de champ proche optique SNOM reste très limitée dû aux difficultés de mise en œuvre instrumentale. La sonde de champ proche est le cœur du microscope et la maîtrise de son utilisation (suppression d'un certain nombre de réglages optiques) constitue la clé technique de l'accès de cette méthode à un plus grand nombre d'utilisateurs. Ces travaux de thèse s'effectuent dans le contexte d'un projet qui consiste à réaliser la preuve de concept d'une sonde novatrice en matériau hybride organique/minéral, de type levier, intégrant une fonction optique. Dans la première partie, une étude bibliographique retrace l'historique des microscopies et donne le principe du champ proche optique. Ensuite, les différentes sondes commerciales de type fibre optique ou cantilever, à ouverture ou sans ouverture, ou autre, leurs avantages et inconvénients, leurs techniques de fabrication et les principaux matériaux utilisés sont présentés. En se basant sur cette étude bibliographique, on propose une nouvelle sonde à pointe pleine en matériau hybride qui associe les avantages de chaque type de sonde. Les raisons du choix du matériau hybride comme matériau de base de la sonde et ses caractéristiques sont aussi présentées dans cette partie. Dans une deuxième partie on détaille le procédé de fabrication du matériau (synthèse) ainsi que le rôle des différentes étapes dans ce procédé et les changements réalisées suite à des modifications des paramètres de la synthèse. Une caractérisation de ce matériau est aussi réalisée dans cette partie en mesurant son indice de réfraction et son module d'Young. La troisième partie est consacrée à la détermination des dimensions de la sonde qui permettent de maximiser le transfert de puissance optique en émission et réception. Ceci est fait en se basant sur une étude plus théorique au travers de simulations. L'effet de plusieurs paramètres sur la propagation de la lumière dans la sonde est étudié (longueur, largeur, épaisseur et raideur du levier ainsi qu'ouverture à l'extrémité de la pointe). La quatrième partie est dédié à la réalisation des sondes "micropoutres sol-gel" et aux caractérisations mécaniques et optiques associées. Elle présente le procédé de fabrication optimisé de sondes optiques couplant la définition des sondes par méthode de masquage et leur libération par gravure réactive ionique et gravure au fluorure de xénon "DRIE + XeF2". A partir de ce procédé, des guides d'ondes optiques ont été réalisés et caractérisés permettant la détermination des pertes optiques et donc du coefficient d'absorption du matériau hybride développé. La conclusion présente les perspectives ouvertes et en cours de ce travail dans le cadre d'un projet plus global..The use of near-field optical microscopy SNOM is still very limited due to difficulties in instrumental work. The probe is the heart of the microscope and control its use (removal of optical settings number) is the technique key to access this method to a larger number of users. This thesis work is realized in the context of a project to achieve a concept proof for an innovative probe organic / inorganic hybrid material, lever type, incorporating an optical function. In the first part, the history of microscopy and the principle of the optical near field are described in a literature study. Then, the various commercial probes of optical fiber or cantilever type, with aperture or apertureless, or otherwise, their advantages and disadvantages, their manufacturing techniques and the main materials used are presented. Based on this literature study, we propose a new probe full tip hybrid material that combines the advantages of each type of probe. The choice reasons of the hybrid material as base material of the probe and its characteristics are also presented in this part. In the second part we detail the manufacturing process of the material (synthesis) as well as each step role in this process and changes made in response to changes in the synthesis parameters. Characterization of this material is also carried out in this part by measuring its refractive index and its Young's modulus. The third part is devoted to the determination of the probe dimensions to maximize the optical transmission and collection power based on a theoretical study through simulations. Several parameters effect on the light propagation in the probe is also studied (length, width, thickness and stiffness of the lever and aperture towards the end of the tip). The fourth part is dedicated to the probe achievement in hybrid material and associated mechanical and optical characterizations. It presents the manufacturing optimized process of optical probes coupling masking defining method probes and releasing method by reactive ion etching and etching xenon fluoride "DRIE + XeF2". Using this process, optical waveguides were realized and characterized for the determination of optical losses and therefore the absorption coefficient of the developed hybrid material. The conclusion presents open perspectives as part of a larger project
29
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.
Full text
30
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.
Full text
31
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.
Full textAbstract:
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.
32
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.
Full text
33
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.
Full text
34
Inglis, William. "Investigating probe-sample interactions in NSOM." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288999.
Full text
35
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.
Full textAbstract:
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.
36
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.
37
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.
Full text
38
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.
Full textAbstract:
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.
39
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.
Full text
40
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.
41
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/.
Full textAbstract:
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.
42
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.
43
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/.
Full text
44
Kohlgraf-Owens, Dana. "Optically Induced Forces in Scanning Probe Microscopy." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5649.
Full textAbstract:
The focus of this dissertation is the study of measuring light not by energy transfer as is done with a standard photodetector such as a photographic film or charged coupled device, but rather by the forces which the light exerts on matter. In this manner we are able to replace or complement standard photodetector-based light detection techniques. One key attribute of force detection is that it permits the measurement of light over a very large range of frequencies including those which are difficult to access with standard photodetectors, such as the far IR and THz. The dissertation addresses the specific phenomena associated with optically induced force (OIF) detection in the near-field where light can be detected with high spatial resolution close to material interfaces. This is accomplished using a scanning probe microscope (SPM), which has the advantage of already having a sensitive force detector integrated into the system. The two microscopies we focus on here are atomic force microscopy (AFM) and near-field scanning optical microscopy (NSOM). By detecting surface-induced forces or force gradients applied to a very small size probe ( diameter), AFM measures the force acting on the probe as a function of the tip-sample separation or extracts topography information. Typical NSOM utilizes either a small aperture ( diameter) to collect and/or radiate light in a small volume or a small scatterer ( diameter) in order to scatter light in a very small volume. This light is then measured with an avalanche photodiode or a photomultiplier tube. These two modalities may be combined in order to simultaneously map the local intensity distribution and topography of a sample of interest. A critical assumption made when performing such a measurement is that the distance regulation, which is based on surface induced forces, and the intensity distribution are independent. In other words, it is assumed that the presence of optical fields does not influence the AFM operation. However, it is well known that light exerts forces on the matter with which it interacts. This light-induced force may affect the atomic force microscope tip-sample distance regulation mechanism or, by modifying the tip, it may also indirectly influence the distance between the probe and the surface. This dissertation will present evidence that the effect of optically induced forces is strong enough to be observed when performing typical NSOM measurements. This effect is first studied on common experimental situations to show where and how these forces manifest themselves. Afterward, several new measurement approaches are demonstrated, which take advantage of this additional information to either complement or replace standard NSOM detection. For example, the force acting on the probe can be detected while simultaneously extracting the tip-sample separation, a measurement characteristic which is typically difficult to obtain. Moreover, the standard field collection with an aperture NSOM and the measurement of optically induced forces can be operated simultaneously. Thus, complementary information about the field intensity and its gradient can be, for the first time, collected with a single probe. Finally, a new scanning probe modality, multi-frequency NSOM (MF-NSOM), will be demonstrated. In this approach, the tuning fork is driven electrically at one frequency to perform a standard tip-sample distance regulation to follow the sample topography and optically driven at another frequency to measure the optically induced force. This novel technique provides a viable alternative to standard NSOM scanning and should be of particular interest in the long wavelength regime, e.g. far IR and THz.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
45
Tisler, Julia [Verfasser]. "Nitrogen-vacancy center in diamond as sensor for Fluorescence Resonance Energy Transfer Scanning Near Field Optical Microscopy / Julia Tisler." München : Verlag Dr. Hut, 2014. http://d-nb.info/1050331583/34.
Full text
46
López, Ayón Gabriela. "Applying a commercial atomic force microscope for scanning near-field optical microscopy techniques and investigation of Cell-cell signalling." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92400.
Full textAbstract:
The field of research of this thesis is Condensed Matter Physics applied to Biology. Specifically it describes the development of different Atomic Force Microscopy techniques and tools towards the study of living cells in physiological solution. Particular interest is put into the understanding of the influence of noise in the determination of ordered liquid layers above a mica surface - as work towards the study of the role of water and ions in biological processes - and the influence of "diving bell" to boost the Q factor and allow stable imaging and force spectroscopy with tips based on Scanning Near-field Optical Microscopy [LeDue, 2010 and LeDue, 2008]. By combining SNOM techniques as a local illumination method (and thus avoiding photo bleaching of individual molecules) and high resolution AFM techniques we will be able to investigate mechano-transduction and associated signaling in living cells and individual proteins.Le domaine de recherche de cette thèse consiste en l'application de la physique de la matière condensée à la biologie. Plus précisément, ce travail décrit le développement de différentes techniques de Microscopie à Force Atomique (MFA) et d'outils permettant l'étude de cellules vivantes en solution physiologique. Un intérêt particulier est porté à la compréhension de l'influence du bruit dans la détermination de couches liquides ordonnées au-dessus d'une surface de mica - en tant que travail préalable à l'étude du rôle de l'eau et des ions dans les processus biologiques - et de l'influence d'une "cloche de plongée" pour renforcer le facteur Q ainsi que pour permettre l'imagerie stable et la spectrométrie de force avec des sondes basées sur la Microscopie Optique en Champ Proche (MOCP). En combinant des techniques MOCP, utilisées comme méthode d'éclairement local (évitant ainsi le photoblanchiment des molécules individuelles), et des techniques MFA haute résolution, nous serons capables d'investir la mécano-transduction et le signalement associé dans des cellules vivantes et dans des protéines individuelles.
47
Lehnen, Stephan [Verfasser]. "Investigation of light propagation in thin-film silicon solar cells by dual-probe scanning near-field optical microscopy / Stephan Lehnen." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2015. http://d-nb.info/1114841439/34.
Full text
48
Mehtani, Disha. "Development and Optimization of Scanning nano-Raman Spectroscopy." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1152212506.
Full text
49
Cao, Zhao [Verfasser], Thomas [Akademischer Betreuer] Taubner, and Uwe [Akademischer Betreuer] Rau. "High-resolution photocurrent mapping of thin-film silicon solar cells using scanning near-field optical microscopy / Zhao Cao ; Thomas Taubner, Uwe Rau." Aachen : Universitätsbibliothek der RWTH Aachen, 2021. http://d-nb.info/1239116829/34.
Full text
50
Eftekhar, Ali Asghar. "Nanoscale light-matter interactions in the near-field of high-Q microresonators." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45900.
Full textAbstract:
The light-matter interaction in the near-field of high-Q resonators in SOI and SiN platforms is studied. The interactions of high-Q traveling-wave resonators with both resonant and non-resonant nanoparticles are studied and different applications based on this enhanced interactions in near-field such as high-resolution imaging of mode profile of high-Q resonators, label-free sensing, optical trapping, and SERS sensing are investigated. A near-field imaging system for the investigation of the near-field phenomena in the near-field of high-Q resonators is realized. A new technique for high-resolution imaging of the optical modes in high-Q resonators based on the near-field perturbation is developed that enables to achieve a very high resolution (< 10 nm) near-field image. The prospect of the high Q resonators on SOI platform for highly multiplexed label-free sensing and the effect of different phenomena such as the analyte drift and diffusion and the binding kinetics are studied. Also, the possibility of enhancing nanoparticle binding to the sensor surface using optical trapping is investigated and the dynamic of a nanoparticle in the high-Q resonator optical trap is studied. Furthermore, the interaction between a resonant nanoparticle with a high-Q microdisk resonator and its application for SERS sensing is studied. A model for interaction of resonant nanoparticles with high-Q resonators is developed and the optimal parameters for the design of coupled microdisk resonator and a plasmonic nanoparticle are calculated. The possible of resonant plasmonic nanoparticle trapping and alignment in an SiN microdisk resonator optical trap is also shown.