Remote Indicator of Fiber End Temperature for Laser Surgery

For a laser scalpel, a method has been developed to control the temperature at the end of its optical fiber with a converter by excitation of ultrasonic pulses of longitudinal and bending waves in it and measuring the delay time of their propagation. The wedge method was used to excite ultrasonic waves at a frequency of 1.1 MHz in the fiber core using a PZT-19 piezoelectric element. Rose alloy was used as the material of the wedge, and a thin wire wound on it was used to fix it on the protective sheath of the optical fiber. Delays of ultrasonic pulses were measured by signal gating for ranges of locations corresponding to reflection from the working end of the optical fiber. When the set temperatures are exceeded, a digital signal is generated for the sound alarm and for the laser control circuit in order to reduce the radiation power.