| 摘要 |
PURPOSE:To measure exactly the length of an optical fiber to be measured by subjecting the light from a light source to sinusoidal modulation by using a synthesizer, making incident the light to the optical fiber, subjecting the exit light from the optical fiber to optoelectric conversion and measuring the phase difference with the electric signal from the synthesizer by a phase meter. CONSTITUTION:The sinusoidal modulation light signal form an electrooptic converter modulated by the sinusoidal wave from the synthesizer 1 is made incident to the optical fiber 3 to be measured. The exit light from the optical fiber 3 is converted to the electric signal by the optoelectric converter 4 and is outputted to the phase meter 5. The sinusoidal modulation light from the synthesizer 1 is inputted by a coaxial cable 6 to the phase meter 5. The phase meter 5 measures the phase difference between the two electric signals. The length of the optical fiber 3 can be exactly determined by investigating preliminarily the phase delays (advances) DELTAthetai, DELTAtheta0 of the converter 2 and the converter 4. The determination of said length is made possible simply by calibrating the phase characteristic with an optical fiber of which the length is exactly known if the investigation of DELTAthetai, DELTAtheta0 is not possible. |
