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Coherence-Gated Wave-Front Sensing in Strongly Scattering Samples

Feierabend, Marcus

German Title: Kohärenzgatter-Wellenfrontabtastung in stark streuenden Proben

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Abstract

In this thesis coherence-gated wave-front sensing (CGWS), a new approach for measuring wave-fronts in strongly scattering samples, is presented. This method combines Shack-Hartmann wave-front sensing and phase shifting interferometry (PSI). It employs virtual lenses to mimic the function of a conventional Shack-Hartmann sensor. The use of a modal estimation algorithm allows an approximation of the measured wave-front with a linear combination of Zernike polynomials up to the fifth radial degree. The principle of CGWS is tested by measuring two wave-front aberrations, defocus and astigmatism, for a mirror as a sample and a strongly scattering sample. The results are compared to theoretical models. The main advantage of CGWS is the discrimination against light backscattered from outside the focal region. A further advantage is the increase in the effective detection sensitivity. The capabilities of CGWS are demonstrated with wave-front measurements in scattering samples in the presence of background light that is dominant by about three orders of magnitude. In various microscopy applications, the ability to pre-emptively correct the wave-front, employing CGWS measurement data, may allow improvements of the optical focus and thus enhance the resolution and depth penetration in tissue considerably.

Item Type: Dissertation
Supervisor: Denk, Prof. Dr. Winfried
Date of thesis defense: 30 June 2004
Date Deposited: 17 Aug 2004 10:27
Date: 2004
Faculties / Institutes: Service facilities > Max-Planck-Institute allgemein > MPI for Medical Research
Subjects: 530 Physics
Controlled Keywords: Adaptive Optik, Wellenfront, Wellenfrontsensor, Optische Kohärenz, Fluoreszenzmikroskopie
Uncontrolled Keywords: Optische KohärenztomographieAdaptive Optics , Wave-Front Sensing , Coherence , Optical Coherence Tomography , Fluorescence Microscopy
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