[1] Delft Univ Technol, Fac Elect Engn Math & Comp Sci, Delft, Netherlands
[2] Vrije Univ Amsterdam, Dept Phys & Astron, Amsterdam, Netherlands
[3] Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA
[4] Univ Rochester, Inst Opt, Rochester, NY 14627 USA