Fiberoptiska komponenter för biomedicinska tillämpningar

In this thesis, a fibre-based low-coherence interferometer for high-precision surface profiling is presented. The system, built on a Michelson interferometer with a 1565 nm broadband ASE source, utilises a piezoelectric fibre stretcher for modulating the optical path length. A characterisation of the instrument's performance is presented, detailing a custom data processing pipeline that achieves fringe-peak detection precision with a standard deviation of less than 1 µm. Systematic drift was identified as a primary source of error and was corrected by using a real-time compensation method. Final validation measurements on flat, reflective surfaces demonstrated a measurement accuracy of 0.36 µm over a ±400 µm scanning range, confirming the platform's viability for precise topographic analysis. This all-fibre design provides a compact and robust alternative to traditional free-space systems, exhibiting excellent performance on flat surfaces; however, it was found to be unsuitable for characterising biological samples due to signal-to-noise ratio limitations. The thesis further explores the application of fibre-based lasers for nanoparticle-free photothermal therapy. Localised cell death was demonstrated in MCF-7 cell cultures using high-energy pulses from a 1030 nm microchip laser, with pulse energies up to 2.5 µJ. To enhance treatment precision and intensity, fiber microlenses were fabricated using a tapering method. These lenses provided focal lengths as short as 9 µm, showing close agreement with theoretical models and demonstrating a viable path towards subcellular-level targeting.