1. Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan China
2. Key Laboratory of Biomedical Photonics of Ministry of Education, Department of Biomedical Engineering Huazhong University of Science and Technology Wuhan China
3. Department of Biomedical Engineering, University of Houston, Houston, USA and Department of Physiology and Biophysics Baylor College of Medicine Houston USA
4. Department of Optics and Biophotonics Saratov State University Saratov 410012 Russia
5. Laboratory of Laser Diagnostics of Technical and Living Systems Institute of Precise Mechanics and Control RAS Saratov 410028 Russia
6. Optoelectronics and Measurement Techniques Laboratory, P.O. Box 4500 University of Oulu, FIN‐90014 Oulu Finland