1. College of Information Science and Technology, Jinan University, Guangzhou 510632, P. R. China
2. School of Engineering, Sun Yat-Sen University, Guangzhou 511400, P. R. China
3. Department of Physics and Electronic Engineering, Guangxi Normal University for Nationalites, Chongzuo 532200, P. R. China
4. School of Instrument Science and Engineering, Southeast University, Nanjing 210096, P. R. China
5. Key Laboratory of Astronomical Optics & Technology, Nanjing Institute of Astronomical Optics & Technology, Chinese Academy of Sciences, Nanjing 210042, P. R. China