1. Department of Physics; Goethe University of Frankfurt; Max-von-Laue-Str. 1 60438 Frankfurt am Main Germany
2. HF Systems Engineering GmbH & Co. KG; Heinrich-Hertz-Str. 6 34123 Kassel Germany
3. Wölfel Engineering GmbH + Co. KG; Max-Planck-Str. 15 97204 Höchberg Germany