An optical scanning device is for scanning two information layers with two radiation beams in two operating modes. In one embodiment the pads are arranged to reduce the loop inductance of corresponding signal and power supply bond wires. The incompressible fluid is contacted by at least one getter to reduce instabilities caused by the release of hydrogen gas accumulating over time. In an illustrative embodiment, the first representation is a core representation containing core audio information. A permanent-magnet generator is used as the electricity generator of the wind turbine to obtain a power supply at start-up.