PURPOSE: To prevent a lens and an optical fiber damaged due to a laser beam by detecting whether or not the laser beam is made incident on a laser beam incident side end face.
CONSTITUTION: When the terminal part wall plane side of a holding body 6 is irradiated coming off from the end face of the optical fiber 3, a temperature detecting body 9 provided by enclosing the optical fiber 3 at the terminal part wall plane of the holding body 6 is irradiated, The temperature detecting body 9 absorbs the laser beam with a laser beam absorber 9a, then, the temperature of the absorber 9a is increased. Then, a temperature detecting element 9b detects the temperature, and outputs it to a temperature detection circuit 10. The temperature detection circuit 10 outputs a signal to a laser power source when a temperature signal exceeds a reference signal i.e., the temperature before the surface of the metallic holding body 6 is melted. The laser power source circuit 11 controls a power unit so as to stop the oscillation of the laser beam by a laser oscillation device 2 by receiving the signal from the temperature detection circuit 10.
FUNAKOSHI TOSHIO
HONDA TETSUYA
SHIMIZU SUSUMU
TOSHIBA MEDICAL ENG