[1] Med Univ Innsbruck, Inst Biomed Phys, Mullerstr 44, A-6020 Innsbruck, Austria
[2] Friedrich Alexander Univ Erlangen Nurnberg, Inst Photon Technol, Konrad Zuse Str 3-5, D-91052 Erlangen, Germany
[3] Friedrich Alexander Univ Erlangen Nurnberg, Grad Sch Adv Opt Technol SAOT, Paul Gordan Str 6, D-91052 Erlangen, Germany