Observation of the laser ablation process by the soft X-ray laser interferometer

Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Oba, Toshiyuki; Kaihori, Takeshi; Suemoto, Toru*; Terakawa, Kota*; Tomita, Takuro*; Yamamoto, Minoru*

In this study, we developed the shingle-shot soft X-ray laser interferometer at the wavelength of 13.9 nm by use of the double Lloyd's mirror geometry to measure the dynamics of the laser ablation. The lateral resolution and depth sensitivity of this interferometer were measured to be less than 1.5 micron and 1 nm, respectively. We combined this interferometer with Ti;Sapphire laser for this experiment. After 50 ps from laser irradiation, 35 nm expansion of the platinum sample was measured. And the expansion speed of the ablation front was estimated to be 700 m/s. The result of it shows there is low density structure (like as bubble structure) under the ablation front.