DISPLACEMENT MEASURING INSTRUMENT BY OPTICAL FIBER

摘要

PURPOSE:To measure exactly a vibration of an object to be measured having a curved surface by a continuously high resolution, by constituting the titled device by focusing a compensating optical fiber together with plural projecting optical fibers and plural photodetecting optical fibers. CONSTITUTION:A fiber probe 5 is constituted by combining two pieces of projecting optical fibers 10 and two pieces of photodetecting fibers 11, so that for instance, they cross each other, and also focusing a compensating optical fiber 9 which is bent in the tip part and connected to a photodetecting circuit. This probe 5 is clamped and fixed 4 to a pipe 1 being an object to be measured, through a supporting base 2, a supporting part 8, a fiber fixing part 3, etc. In this state, a vibration is given to the pipe 1 in the same way as in a real car, and a light beam from the fiber 10 is irradiated to the pipe 1. The light beam which has been made incident on the curved surface of the pipe 1 and has been reflected is caught by two pieces of fibers 11, therefore, a sufficient light quantity can be photodetected, and it is converted to an electrical signal in the photodetecting circuit. This signal is subtracted from a signal which has been converted electrically through the photodetecting circuit from the fiber 9, brought to a phase comparison with a signal from an oscillation circuit, and thereafter, taken out as an output for showing a displacement.