Affiliation: | a TW and MM are in the Department of Electrical Communications, Faculty of Engineering, Tohoku University, Sendai, 980-77, Japan b SS, TE and GM are in the Laser-Medizin-Zentrum GmbH, Berlin, Krahmerstrasse 6-10, D-12207, Berlin, Germany c LB is in the Dental Division. R&D Department, Siemens Fabrikstrasse 31, D-64625, Bensheim, Germany |