1. Department of Electric Engineering, Aichi Institute of Technology, Yachikusa1247, Yakusa-cho, Toyota, Aichi 470-0392, Japan
2. Research Institute for Industrial Technology, Aichi Institute of Technology, Yachikusa1247, Yakusa-cho, Toyota, Aichi 470-0392, Japan
3. Research & Development Department, Hamamatsu Photonics K.K., 314-5 Shimokanzo, Iwata, Shizuoka 438-0193, Japan