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Visar resultat 1 - 5 av 15 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Phase Retrieval Methods for Electromagnetic Source Modeling

    Författare :Markus Johansson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; source modeling; optimization; SAR; phase retrieval; dosimetry;

    Sammanfattning : Modeling of the field distributions from electromagnetic sources is of interest for various applications including electromagnetic compatibility investigations, near-field to far-field transformations, antenna diagnostics and electromagnetic dosimetry. In order to determine whether exposure safety guidelines, such as the EU directive 2004/40/EC, are complied with, source modeling methods are important. LÄS MER

  3. 2. Numerical and experimental aspect of coherent lensless imaging

    Författare :Erik Malm; NanoLund: Centre for Nanoscience; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Coherent diffractive imaging; Holography; Phase retrieval; Diffraction; Inverse scattering; XUV light; non-rigid image registration; Fysicumarkivet A:2021:Malm;

    Sammanfattning : This thesis is devoted to the understanding, application, and extension of coherent lensless imaging methods for microscopy purposes. Particular attention is given to the Fourier transform holography and coherent diffractive imaging methods. LÄS MER

  4. 3. Phase retrieval method for quantitative terahertz spectroscopy in reflection geometry

    Författare :Kasturie Jatkar; Stefano Bonetti; Magnus Berntsen; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Terahertz; reflection; THz spectroscopy; InSb; Physics; fysik;

    Sammanfattning : Terahertz time-domain spectroscopy (THz-TDS) is a reliable technique used for studying the complex optical properties of materials. Its frequency range makes it suitable for detecting low-energy collective excitations such as phonons, magnons, and plasmons. THz-TDS in transmission geometry has gained much attention over the years. LÄS MER

  5. 4. High-resolution biomedical phase-contrast tomography

    Författare :William Twengström; Hans Hertz; Anna Burvall; Marco Stampanoni; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; x-ray; x-ray imaging; biomedical; phase contrast; tomography; zebrafish; coronary artery; virtual histology; ring artifacts; phase retrieval; mummy; Fysik; Physics;

    Sammanfattning : Improved three-dimensional biomedical imaging can give a better understanding of tissue structure, growth and diseases. Most present imaging techniques that provide cellular spatial resolution are based on visible or infrared light. These methods cannot image deeper than a millimeter into tissue. LÄS MER

  7. 5. Flash Diffractive Imaging in Three Dimensions

    Författare :Tomas Ekeberg; Janos Hajdu; Keith Nugent; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; X-ray; diffraction; mimivirus; three dimensional; phase retrieval; EMC; manifold embedding; CXI; FEL; free-electron laser; single particle; Physics with specialization in Biophysics; Fysik med inriktning mot biofysik;

    Sammanfattning : During the last years we have seen the birth of free-electron lasers, a new type of light source ten billion times brighter than syncrotrons and able to produce pulses only a few femtoseconds long. One of the main motivations for building these multi-million dollar machines was the prospect of imaging biological samples such as proteins and viruses in 3D without the need for crystallization or staining. LÄS MER