The laser head for processing or the processing stage in the conventional laser processing
method is mechanically rotated for drilling. The processing speed depends upon these structures'
acceleration/deceleration, which is limited by their masses and rigidities. Therefore, the laser
processing method has so far had limitations in enhancing the processing speed. Since processing
speed is limited, mitigation of the laser's thermal influences affecting processing quality has also
been limited. In coping with the problems, a laser optical system, with a mass much smaller than
that of the laser head or drilling stage was rotated quickly, thereby realizing much faster
processing with processing quality maintained equal to or better than that of conventional laser
processing.
