LASER IRRADIATION APPARATUS

PURPOSE:To detect securely the deterioration of an optical fiber cable and the abnormality when the optical fiber is burnt and facilitate monitoring and checking the characteristics of a power sensor by a method wherein the resistance value of the power sensor is measured at the time of initial operation and at the time when a laser beam is not emitted and compared with a reference value. CONSTITUTION:An analog switch 8 is so controlled as to put the output of a power sensor 2 into a voltage dividing resistance 9 and a comparator 10 and a voltage A corresponding to the resistance of the power sensor 2 is compared with the reference voltage B of a reference voltage source 11 at the time of initial operation and at the time when a laser beam is not emitted. If AB, a central control circuit 6 transmits a signal to an alarm indicator 15 in accordance with the comparison signal and the indicator 15 gives an alarm or abnormality indication or stops the apparatus. When the laser beam is emitted, the analog switch 8 is changed over to the opposite porality and the voltage A is amplified by an amplifier 12 and the output C of the amplifier 12 is compared with the reference voltage D of a reference voltage source 14. If CD, the central control circuit 6 receives the output signal and the alarm indicator 15 gives an alarm or abnormality indication or stops the operation of the apparatus.