MEASURING INSTRUMENT FOR TRANSMISSIVITY OF OPTICAL FIBER

摘要

PURPOSE:To find stable transmissivity by using an exciting element provided in contact with an optical fiber and vibrating the optical fiber faster than the time constant of a power monitor. CONSTITUTION:A linear deflection carbon dioxide laser oscillator 5 emits a carbon dioxide laser light beam 2. This light beam 2 is branched by a beam splitter 6 and the majority of it passes through a condenser lens 7 and is condensed on the incidence end surface 8 of an infrared-ray optical fiber 3. The remainder is guided to the 1st power monitor 9 and its energy quantity Pi is measured. Further, the light beam 2 which is guided by the optical fiber 3 and emitted from the projection end surface 10 of the optical fiber 3 is supplied to a 2nd power monitor 11 and its energy quantity P0 is measured, so that the transmissivity of the optical fiber is found. The exciting element 12 made of piezoelectric ceramic is provided in contact with the center part of the optical fiber 3, which is vibrated at 120Hz. An exciting circuit 13 which drives the element 12 doubles the frequency of an AC power source and controls the voltage.