Light scattering and color shift are two major sources of distortion for underwater photography. Light scattering is caused by light incident on objects reflected and deflected multiple times by particles present in the water before reaching the camera. This in turn lowers the visibility and contrast of the image captured. Color shift corresponds to the varying degrees of attenuation encountered by light traveling in the water with different wavelengths, rendering ambient underwater environments dominated by bluish tone. This paper proposes a novel approach to enhance underwater images by a dehazing algorithm with wavelength compensation. Once the depth map, i.e., distances between the objects and the camera, is estimated by dark channel prior, the light intensities of foreground and background are compared to determine whether an artificial light source is employed during image capturing process. After compensating the effect of artifical light, the haze phenomenon from light scattering is removed by the dehazing algorithm. Next, estimation of the image scene depth according to the residual energy ratios of different wavelengths in the background is performed. Based on the amount of attenuation corresponding to each light wavelength, color shift compensation is conducted to restore color balance. A Super-Rsolution image can offer more details that must be important and necessary in low resolution underwater image. In this paper combine Gradient-Base Super Resolution and Iterative Back-Projection (IBP) to propose Cocktail Super Resolution algorithm, with the bilateral filter to remove the chessboard effect and ringing effect along image edges, and improve the image quality. The underwater videos with diversified resolution downloaded from the Youtube website are processed by employing WCID, histogram equalization, and a traditional dehazing algorithm, respectively. Test results demonstrate that videos with significantly enhanced visibility and superior color fidelity are obtained by the WCID proposed.

In this paper, we propose an image registration algorithm to form a set of images to a high-resolution image. This algorithm employs a fringe projected scheme to perform the registration. The proposed algorithm provides several advantages, such as high precision, low computation cost, simple system configuration and robotic performance. An example which used three images to form a hight-resolution image was given. It was found that the resolution had enhanced 2.72 times.

This paper presents a set of Image Registration, Image Integration, interpolation and image restoration and other technology, the number of low-resolution images synthesized high-resolution image. Relative to the existing image fusion technology, the method provided in this paper has more advantages, such as: (1) high-precision value; (2)low computation cost; (3)a compact system; (4) applicable to noise images; (5) robotic and automatic performance.

Dynamics between organic molecules and surface enhanced Raman scattering (SERS) hot spots are extracted from far-field optical images by two experimental methods presented in this thesis: orientational imaging and super-resolution optical imaging. We introduce SERS orientational imaging as an all-optical technique able to determine the three-dimensional orientations of SERS-active Ag nanoparticle dimers. This is accomplished by observing lobe positions in SERS emission patterns formed by the directional polarization of SERS emission along the longitudinal axis of the dimer. We further extend this technique to discriminate nanoparticle dimers from higher order aggregates by observing the wavelength-dependence of SERS emission patterns, which are unchanged in nanoparticle dimers, but show differences in higher order aggregates involving two or more nanoparticle junctions. Dynamic fluctuations in the SERS emission pattern lobes are observed in aggregates labeled with low dye concentrations, as molecules diffuse into regions of higher electromagnetic enhancement in multiple nanoparticle junctions. In order to investigate these dynamic interactions between single organic molecules and nanoparticle hot spots we present the first super-resolution optical images of single-molecule SERS (SM-SERS), introducing super-resolution imaging as a powerful new tool for SM-SERS studies. Mapping the dynamic movement of SM-SERS centroid positions with +/- 5 nm resolution reveals the position-dependent SERS intensity as the centroid samples different positions in space. We have proposed that the diffusion of the SERS centroid is due to diffusion of a single molecule on the surface of the nanoparticle, which leads to changes in coupling between the scattering dipole and the optical near field of the nanoparticle. Finally, we combine an isotope-edited bi-analyte SERS spectral approach with super-resolution optical imaging and atomic force microscopy (AFM) structural analysis for a more complete picture of molecular dynamics in SERS hot spots. We demonstrate the ability to observe multiple molecule dynamics in a single hot spot and show that in addition to the single-molecule regime, a "few" molecule regime is able to report on position-dependent SERS intensities in a hot spot. Furthermore, we are able to identify multiple local hot spots in single nanoparticle aggregates. / text

In recent years, localization-based super-resolution imaging has been developed to overcome the diffraction limit of far-field fluorescence microscopy. Photoswitchable probes are a hallmark of this technique. Their fluorescence can be modulated between an emissive and dark state whereby the sequential, nanoscale measurement of individual fluorophore positions can be used to reconstruct an image at higher spatial resolution. Despite the importance of photoswitchable probes for localization-based super-resolution imaging, both a mechanistic and quantitative understanding of the essential photoswitching properties is lacking for most fluorophores. In this thesis, we begin to address this need. Furthermore, we demonstrate the development of new probes and methodologies for both multicolor and live-cell super-resolution imaging. Chapter 2 describes our mechanistic insights into the photoswitching of a common class of dyes called carbocyanines. Red carbocyanines, such as Cy5, enter a long-lived dark state upon illumination with red light in the presence of a primary thiol. We show that the dark state is a covalent conjugate between the thiol and dye and that this dark state recovers by illumination with ultraviolet light. We also speculate on possible reactivation mechanisms. Our mechanistic studies may ultimately lead to the creation of new probes with improved photoswitching properties. Chapter 3 details our quantitative characterization of the photoswitching properties of 26 organic dyes, including carbocyanines and several other structural classes. We define the essential properties of photoswitchable probes, including photons per switching event, on/off duty cycle, photostability, and number of switching cycles, and demonstrate how these properties dictate super-resolution image quality. This rigorous evaluation will enable more effective use of probes. In Chapters 4 and 5, we focus on expanding the super-resolution toolbox with novel strategies for multicolor and live-cell imaging. Chapter 4 discusses two approaches we have developed for multicolor super-resolution imaging, which distinguish probes based on either the color of activation or emission light. These tools allow multiple cellular targets to be resolved with high spatial resolution. Lastly, Chapter 5 introduces a method for targeted cellular labeling with photoswitchable probes using a small peptide tag, as well as a new sulfonate-protection strategy for intracellular delivery of high performing photoswitchable dyes.

The main purpose of the project was to create an initial lab set-up for a dig-ital in-line holographic microscope and a reconstruction algorithm. Different parameters including: light source, pin-hole size and distances pinhole-object and object-camera had to be optimized. The lab set-up is to be developed further by a master student at the University of Nairobi and then be used for malaria detection in blood samples. To acquire good enough resolution for malaria detection it has been found necessary to purchase a gray scale camera with smaller pixel size. Two dierent approaches, in this report called the on-sensor approach and the object-magnication approach, were investigated. A reconstruction algorithm anda phase recovery algorithm was implemented as well as a super resolution algorithm to improve resolution of the holograms. The on-sensor approach proved easier and cheaper to use with approximately the same results as the object-magnication method. Necessary further research and development of experimental set-up was thoroughly discussed. / Projketet har gått ut på att bygga en billigare och enklare metod för att identifiera malaria i blodprover. Malaria är ett stort problem i en mängd områden i världen. Flera av dessa är fattiga och kan i nuläget inte tillhandahålla den här tjänsten till sin befolkning. Förutom att dyr apparatur krävs måste även utbildad personal lägga ner mycket tid för att kolla en stor mängd blodprover för att statistiskt säkerställa om en person har malaria eller inte. Vårt mål var att bygga en labbuppställning för "Digital in line holographic microscopy" och en rekonstruktionsalgoritm som en masterstudent vid Nairobi universitet ska fortsätta utveckla. Vi kom också fram till vilken upplösning som krävdes för att kunna urskilja malaria i blodproverna. Digital in line holographic microscopy går till så att man har en ljuskälla som riktas genom ett pinnhål, ljuset som går genom pinnhålet ljuser upp det prov, blodproverna i vårt fall, man vill undersöka och det resulterande ljuset fångas på en kamera. Med kunskap om fourieroptik går det att rekonstruera den digitala bilden man fångat på kameran, innan rekonstruktion är den ett hologram vilken är svårtydd. Labbuppställningen byggdes delvis med en 3D printer. För att förbättra resultaten implementerades flera algoritmer vilka lade ihop en mängd förskjutna bilder till en bättre bild, så kallad super resolution. Vi lyckades inte komma till den upplösning som krävdes för att urskilja malaria men gjorde en grundlig förstudie och en utförlig beskrivning av det arbete som väntar den student som fortsätter med projektet. Framför allt beskrevs värden på parametrar och vilken typ av kamera som ska användas för att optimera uppställningen.

The optics and photonics development is currently driven towards nanometer scales. However, diffraction imposes challenges for this development because it prevents confinement of light below a physical limit, commonly known as the diffraction limit. Several implications of the diffraction limit include that conventional optical microscopes are unable to resolve objects smaller than 250nm, and photonic circuits have a physical dimension on the order of the wavelength. Metals at optical frequencies display collective electron oscillations when excited by photon energy, giving rise to the surface plasmon modes with subdiffractional modal profile at metal-dielectric interfaces. Therefore, metallo-dielectric structures are promising candidates for alleviating the obstacles due to diffraction. This thesis investigates a particular branch of plasmonic structures, namely plasmonic antennas, for the purpose of optical imaging and sensing applications. Plasmonic antennas are known for their ability of dramatic near-field enhancement, as well as effective coupling of free-space radiation with localized energy. Such properties are demonstrated in this thesis through two particular applications. The first one is to utilize the interference of evanescent waves from an array of antennas to achieve near-field subdiffraction focusing, also known as superfocusing, in both one and two dimensions. Such designs could alleviate the tradeoffs in the current near-field scanning optical microscopy by improving the signal throughput and extending the imaging distance. The second application is to achieve more efficient radiation from single-emitters through coupling to a highly directive leaky-wave antenna. In this case, the leaky-wave antenna demonstrates the ability of enhancing the directivity over a very wide spectrum.

The optics and photonics development is currently driven towards nanometer scales. However, diffraction imposes challenges for this development because it prevents confinement of light below a physical limit, commonly known as the diffraction limit. Several implications of the diffraction limit include that conventional optical microscopes are unable to resolve objects smaller than 250nm, and photonic circuits have a physical dimension on the order of the wavelength. Metals at optical frequencies display collective electron oscillations when excited by photon energy, giving rise to the surface plasmon modes with subdiffractional modal profile at metal-dielectric interfaces. Therefore, metallo-dielectric structures are promising candidates for alleviating the obstacles due to diffraction. This thesis investigates a particular branch of plasmonic structures, namely plasmonic antennas, for the purpose of optical imaging and sensing applications. Plasmonic antennas are known for their ability of dramatic near-field enhancement, as well as effective coupling of free-space radiation with localized energy. Such properties are demonstrated in this thesis through two particular applications. The first one is to utilize the interference of evanescent waves from an array of antennas to achieve near-field subdiffraction focusing, also known as superfocusing, in both one and two dimensions. Such designs could alleviate the tradeoffs in the current near-field scanning optical microscopy by improving the signal throughput and extending the imaging distance. The second application is to achieve more efficient radiation from single-emitters through coupling to a highly directive leaky-wave antenna. In this case, the leaky-wave antenna demonstrates the ability of enhancing the directivity over a very wide spectrum.

abstract: In this work, atomic force microscopy (AFM) and time resolved confocal fluorescence microscopy are combined to create a microscopy technique which allows for nanometer resolution topographic and fluorescence imaging. This technique can be applied to any sample which can be immobilized on a surface and which can be observed by fluorescence microscopy. Biological problems include small molecular systems, such as membrane receptor clusters, where very high optical resolutions need to be achieved. In materials science, fluorescent nanoparticles or other optically active nanostructures can be investigated using this technique. In the past decades, multiple techniques have been developed that yield high resolution optical images. Multiple far-field techniques have overcome the diffraction limit and allow fluorescence imaging with resolutions of few tens of nanometers. On the other hand, near-field microscopy, that makes use of optically active structures much smaller than the diffraction limit can give resolutions around ten nanometers with the possibility to collect topographic information from flat samples. The technique presented in this work reaches resolutions in the nanometer range along with topographic information from the sample. DNA origami with fluorophores attached to it was used to show this high resolution. The fluorophores with 21 nm distance could be resolved and their position on the origami determined within 10 nm. Not only did this work reach a new record in optical resolution in near-field microscopy (5 nm resolution in air and in water), it also gave an insight into the physics that happens between a fluorescent molecule and a dielectric nanostructure, which the AFM tip is. The experiments with silicon tips made a detailed comparison with models possible on the single molecule level, highly resolved in space and time. On the other hand, using silicon nitride and quartz as tip materials showed that effects beyond the established models play a role when the molecule is directly under the AFM tip, where quenching of up to 5 times more efficient than predicted by the model was found. / Dissertation/Thesis / Ph.D. Physics 2012

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