1. National University of Colombia, Department of Physics, Carrera 30 No. 45-03, Bogotá 11001, Colombia
2. University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Quantitative Light Imaging Laboratory, Department of Electrical and Computer Engineering, Urbana, Illinois 61801, United States
3. University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Quantitative Light Imaging Laboratory, Department of Electrical and Computer Engineering, Urbana, Illinois 61801, United StatescUniversity of Illinois at Ur