1. Optics R&D Center, CANON Inc., Utsunomiya 323-3298, Japan
2. Waseda University Honjo Senior High School, Honjo, Saitama 367-0035, Japan
3. CCSE, Japan Atomic Energy Agency, Kashiwa, Chiba 277-8587, Japan
4. CREST (JST), Kawaguchi, Saitama 332-0012, Japan
5. Department of Information Systems Science, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585, Japan