Jan Siegel

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Conventional analyses of fluorescence lifetime measurements resolve the fluorescence decay profile in terms of discrete exponential components with distinct lifetimes. In complex, heterogeneous biological samples such as tissue, multi-exponential decay functions can appear to provide a better fit to fluorescence decay data than the assumption of a(More)
The cleaning of silicon surfaces from submicron dust particles has been studied by means of the " Steam Laser Cleaning " (SLC) process and compared to " Dry Laser Cleaning " (DLC) which is used nowadays in many applications. For SLC a thin liquid layer (e.g. a water-alcohol mixture) is condensed onto the substrate, and is subsequently evaporated by(More)
We report a hybrid imaging technique capable of performing measurements of the spatial, temporal, and spectral emission characteristics of laser-induced plasmas by use of a single detection system. We apply this technique to study the plasma produced by laser ablation of LiNbO3 and observe phenomena not seen in such detail with standard instruments. These(More)
We report an experimental method for directly imaging optical near-fields of dielectric microspheres upon illumination with ultraviolet nanosecond laser pulses. The intensity distribution is imprinted in chalcogenide films leaving behind a characteristic fingerprint with features below 200 nm in size, which we read out with high-resolution field emission(More)
We report a quantitative investigation on the efficiency of the steam laser cleaning process using ns and ps pulses. Well-characterized polymer particles with a diameter of 800 nm dispersed on commercial Si wafers were chosen as a modeling contaminant system. As a result of our investigation , we show for the first time the feasibility of performing(More)
Ultrafast laser processing applications need fast approaches to assess the nonlinear propagation of the laser beam in order to predict the optimal range of processing parameters in a wide variety of cases. We develop here a method based on the simple monitoring of the nonlinear beam shaping against numerical prediction. The numerical code solves the(More)
In this work we analyze the ablation dynamics of crystalline Si in the intense near field generated by a small dielectric particle located at the material surface when being irradiated with an infrared femtosecond laser pulse (800 nm, 120 fs). The presence of the particle (7.9 μm diameter) leads to a strong local enhancement (ca. 40 times) of the incoming(More)
When exposing small particles on a substrate to a light plane wave, the scattered optical near field is spatially modulated and highly complex. We show, for the particular case of dielectric microspheres, that it is possible to image these optical near-field distributions in a quantitative way. By placing a single microsphere on a thin film of the(More)
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