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Multiphoton and non-linear Raman microscopy through a multimode fibre
Pikálek, Tomáš ; Marte, Monika Ritsch- (oponent) ; Zemánek, Pavel (oponent) ; Čižmár, Tomáš (vedoucí práce)
Multimode fibres have recently shown promise as miniature endoscopic probes for imaging deep inside brain tissue of mouse animal models with minimal damage. By employing wavefront shaping, the speckle pattern associated with coherent light propagation through a multimode fibre can be transformed into a tightly focused point, essentially turning the fibre into a miniature point-scanning device. Many microscopic techniques have been successfully implemented through a multimode fibre, and even in-vivo imaging has been demonstrated. This work extends the capabilities to label-free non-linear microscopy with chemical contrast using coherent anti-Stokes Raman scattering (CARS), which can potentially extend the use of multimode fibre endoscopes to clinical applications for, for example, tumour diagnosis. The main focus is the optimisations of the endoscopic system and the fibre probe to allow efficient focusing of pulsed light through multimode fibres, including dispersion control and thus allowing implementation of non-linear imaging techniques. The optimised setup is then employed to demonstrate CARS imaging of biologically relevant tissue, such as myelinated axons in a mouse brain, and chemical selectivity is verified by imaging polymer beads. In addition, multimodal CARS and two-photon excitation fluorescence (TPEF) imaging of fixed mouse tissue is demonstrated.
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