1. Physics Department, Saratov State University, Saratov, 83 Astrakhanskay str., 410012, Russian Federation, Russia
2. Laboratory of Laser Diagnostics of Technical and Living, Systems of Precise Mechanics and Control Institute of the Russian Academy of Sciences, 24 Rabochaya Str., Saratov, 410028, Russian Federation, Russia
3. Optoelectronics and Measurement Techniques Laboratory, University of Oulu, P. O. Box 4500, FIN-90014 Oulu, Finland