1. University of Technology and Humanities, Faculty of Mechanical Engineering, Department of Physics, 26-600 Radom, E. Stasieckiego 54, Poland
2. Institute of Manufacturing Management, Faculty of Manufacturing Technologies, Technical University of Košice, Bayerova 1, 080 01 Prešov, Slovakia
3. Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 041 54 Košice, Slovakia