German Title: Kohärenzgatter-Wellenfrontabtastung in stark streuenden Proben
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.
|Supervisor:||Denk, Prof. Dr. Winfried|
|Date of thesis defense:||30 June 2004|
|Faculties / Institutes:||Service facilities > MPI for Medical Research|
|Controlled Keywords:||Adaptive Optik, Wellenfront, Wellenfrontsensor, Optische Kohärenz, Fluoreszenzmikroskopie|
|Uncontrolled Keywords:||Optische KohärenztomographieAdaptive Optics , Wave-Front Sensing , Coherence , Optical Coherence Tomography , Fluorescence Microscopy|