Vorschau

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Abstract

Twenty years after it was proposed, STED nanoscopy has evolved into a powerful tool in far-field fluorescence imaging which achieves resolutions below 20nm. Nevertheless, the application of STED nanoscopy in life sciences on a large scale is hindered by the high effort which the method requires. This effort is in great part due to the STED laser. So far, lasers which can be utilized for STED, e.g. titanium-sapphire lasers, show both, technical and practical shortcomings, resulting in complex nanoscopy systems. Semiconductor lasers which are compact, reliable and controllable without effort, are predestinated to improve this situation if they are adapted to meet the pulse requirements for STED. Therefore, this thesis examines the potential of different types of semiconductor lasers for STED. Fabry-Pérot laser diodes in overdriven gain switched operation are demonstrated to be suitable STED lasers. Even more suitable STED pulses, with pulse energies of up to 5nJ in 1ns, are obtained from a second semiconductor laser system. Based on a tapered amplifier, this system is constructed to be operated flexibly in various modes of ns pulse generation. With this semiconductor STED laser subdiffraction imaging of fluorescent nuclear track detectors is successfully performed for the first time. Thereby the size of tracks of carbon ions and protons in this material can be determined. Furthermore, a method for all-semiconductor picosecond-pulse generation at wavelengths of 532nm, 561nm and 593nm is presented. This was so far not possible and provides a convenient source of excitation light for red emitting organic dyes, not only for STED nanoscopy. With its findings this thesis proves that STED imaging with a fivefold resolution enhancement is possible with user-friendly and affordable lasers. This paves the way to a wide spread use of STED nanoscopy.