Fig. 8

Drift of the laser beam position in y-direction in the sample plane as a function of time. The plot shows the positional drift of the laser beam center (black line) that was measured by the correction procedures. The measured drift between two subsequent images was used to generate a feedback signal to the scanning mirror, which kept the laser center in a conjugate position to the center of the virtual detector. The 1/e²-radius ${\omega }_0$ of the beam at its waist was 2 μm (gray area in the plot). The extension of the confocal slit detector in the object plane corresponded to 4 μm and is indicated by the dashed blue lines.