1. Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
2. Institute of Applied Optics, Friedrich Schiller University Jena, Fröbelstieg 1, 07743 Jena, Germany
3. Institute of Scientific Instruments of the Czech Academy of Sciences v.v.i., Královopolská 147, 612 64 Brno, Czech Republic