1 Engineering and Technology Research Center of Shanxi Province for Optical-Electric Information and Instrument, North University of China, Taiyuan, Shanxi 0 30051, China
2 Key Laboratory of Instrument Science & Dynamic Measurement, Ministry of Education, North University of China, Taiyuan, Shanxi 0 30051, China;
3 State Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan, Shanxi 0 30051, China