Study on laser processing by using pulse train beam with oscillation of coherent phonon (1st report) -Development of the system for generating pulse train and time resolved evaluation of the pulse train beam-

The laser processing with little thermal damage could be achieved by using the femto second laser. One of the unique aspects of femtosecond radiation is the excitation of coherent phonon in the pico-second order duration. We propose a surface processing method with excitation of coherent phonon by using femto pulse train beam. Currently, we are exploring the basic mechanisms of femtosecond laser processing with exicitation of coherent phonon. It is considered that the surface processing during coherent phonon oscillation enables to improve the processing rate of the femto second laser higher than that of the conventional femto pulse laser processing method. In this paper, we report the fundamental experiment to investigate the processing property for Ge(l00) with excitation of coherent phonon.