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PhD. of Alejandro Diaz Tormo

Author: Alejandro Diaz Tormo
Promotor: Nicolas Le Thomas
Dutch Title: 4π-ramanmicroscopie
English Title: 4π Raman Microscopy
Date: 21/10/2019
Main Language: English
ISBN number: 978-94-6355-295-0
Thesis: Download the PhD Thesis (5.9MB) (5.9MB)


Until 1992, microscopes could only focus light tightly in the transversal plane but not along the direction of propagation. That year, it was experimentally proven that the focal spot could be shrunk further along the optical axis by using not one, but two opposing objective lenses simultaneously. The result is a resolution that is up to seven-fold better than the conventional resolution. Namely, an almost spherical focal spot of typically 100-150 nm in diameter can be achieved. This technique is dubbed 4π microscopy as it enlarges the theoretical maximum solid angle of the microscope, for light excitation and collection, from 2π to 4π steradians.
4π microscopy has long been used to improve the optical resolution in fluorescence microscopy. The approach is, however, not limited to fluorescence microscopy --we demonstrate in this dissertation that it can bring similar benefits to Raman microscopy as well. We developed a 4π Raman microscope with better spatial resolution and enhanced Raman signal compared to standard spontaneous Raman microscopy.

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