LASER EXCAVATION FACILITY FOR ADVANCEMENT OF BOREHOLE USING LASER

摘要

PROBLEM TO BE SOLVED: To provide a facility, a device and a method for transmitting a laser over a long distance while maintaining output of laser energy for opening a borehole underground using the laser.SOLUTION: A laser excavation facility includes a pit bottom assembly which is arranged in a borehole and has a beam shaping optical element 1406 for shaping a pattern of a laser beam in a prescribed laser beam pattern and means for rotating the beam shaping optical element 1406 around the central axis of the laser beam. The prescribed laser pattern is in a linear shape crossing with the central axis and has energy application distribution of increasing substantially linearly as being separated from the position crossing with the central axis to the outer side. When the beam shaping optical element 1406 is rotated at constant speed, the prescribed laser pattern is rotated at the constant speed around the central axis and substantially uniform energy application distribution is formed on the bottom surface of the borehole.