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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design and implementation of ultra-high resolution, large bandwidth, and compact diffuse light spectrometers

Badieirostami, Majid 07 November 2008 (has links)
My research on the new concepts for spectrometer has been focused on the development of true multi-dimensional spectrometers, which use a multi-dimensional [two-dimensional (2D) or 3D] mapping of the spectral information into space. I showed that by combining a simple dispersive element (a volume hologram) formed in very inexpensive polymers with a basic Fabry-Perot interferometer, we can form a spectrometer with ultra-high resolution over a large spectral bandwidth, which surpasses all conventional spectrometers. I strongly believe that the extension of this mapping into three dimensions by using synthetic nanophotonic structures with engineered dispersion can further improve the performance and reduce the overall spectrometer size into the micron regime. The need for efficient modeling and simulation tools comes from the sophisticated nature of the new 3D nanophotonic structures, which makes their simple analysis using well-known simple formulas for the propagation of the electromagnetic fields in bulk materials impossible. In my Ph.D. research, I developed new approximate modeling tools for both the modeling of incoherent sources in nanophotonics, and for the propagation of such optical beams inside the 3D nanophotonic structures of interest with several orders of magnitude improvement in the simulation speed for practical size devices without sacrificing accuracy. To enable new dispersive properties using a single nanophotonic structure, I have focused in my Ph.D. research into polymer-based 3D photonic crystals, which can be engineered using their geometrical features to demonstrate unique dispersive properties in three dimensions that cannot be matched by any bulk material even with orders of magnitude larger sizes. I have demonstrated the possibilities of using a very compact structure for wavelength demultiplexing and also for spectroscopy without adding any other device.
2

Pozorování amplitudových a fázových předmětů přes rozptylující prostředí pomocí holografického mikroskopu s kontrolovatelnou koherencí / Amplitude and phase objects observation through scattering media by means of coherence-controlled holographic microscope

Effenberger, Adam January 2015 (has links)
This diploma thesis deals with phase and amplitude objects observation through scattering media by means of a coherence-controlled holographic microscope (CCHM). A brief history of development and construction of the microscope, its advantages compared to the classical light microscopy and hologram processing are described. Quantitative phase imaging through scattering media by means of ballistic as well as diffuse light is verificated in the experimental part. A comparison of an image obtained through a scattering layer by means of CCHM and a classical microscopy in the light field is demonstrated.
3

Koherencí řízená holografická mikroskopie v opticky rozptylujících prostředích / COHERENCE-CONTROLLED HOLOGRAPHIC MICROSCOPY IN DIFFUSE MEDIA

Lošťák, Martin January 2015 (has links)
This thesis deals with imaging through diffuse media in coherence-controlled holographic microscope (CCHM) developed in IPE FME BUT. The mutual coherence function as well as the signal dependence on the lateral mutual shift between both arms of the CCHM are calculated. Both functions are related to each other. The latter dependence is measured experimentally. A principle of imaging with CCHM through diffuse media with both ballistic and diffuse light is explained by a simple geometrical model. This model is then verified experimentally by imaging a sample through diffuse medium. The point spread function (PSF) of CCHM for imaging through diffuse media is then calculated. Results of PSF calculation are proved experimentally.

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