Product Code: ICAL07_905

Underwater Rock Drilling by CO2 Laser
Authors:
Toshio Kobayashi, Japan Drilling Co.,Ltd; Tokyo Japan
Kiyonobu Ohtani, Tohoku University; Sendai Japan
Kazuyoshi Takayama, Tohoku University; Sendai Japan
Satoru Umezu, Japan Drilling Co., LTD.,; Tokyo Japan
Komei Okatsu, Japan Oil, Gas and Metals National Corporation; chiba Japan
Presented at ICALEO 2007

As a part of fundamental studies of drilling rocks by laser irradiation, this paper describes the evolution of a cavitation cone created by irradiation of pulsed carbon dioxide laser into water. A carbon dioxide laser beam was intermittently irradiated onto a granite specimen submerged at 50mm depth from the surface. A high-speed video observation revealed the generation of an initial cone shaped water cavity, transmission of laser beams through it and eventual ablation of the granite specimen surface. The laser beam irradiations locally melt the granite surface to form small glassy beads, which are readily removable by a mechanical method. We will discuss the formation and removal of the glass beads. Repeating this procedure we then primarily confirmed that high power laser transmission in water indeed useful to drill rocks.