1. Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic
2. Central European Institute of Technology, Brno University of Technology, Purkyňova 656/123, Brno 612 00, Czech Republic
3. Department of Optics, Palacký University, 17. Listopadu 1192/12, Olomouc 771 46, Czech Republic