METHOD OF MEASURING HOLE DIAMETER, HOLE POSITION, HOLE SURFACE ROUGHNESS, OR BENDING LOSS OF AN OPTICAL FIBER WITH A HOLE, METHOD OF MANUFACTURING OPTICAL FIBER WITH HOLE, AND METHOD OF TESTING OPTICAL FIBER LINE WITH HOLE

摘要

PROBLEM TO BE SOLVED: To easily know a hole diameter, a hole position, hole surface roughness, and bending loss, etc., of an optical fiber with a hole without cutting the optical fiber with the hole when measuring the hole diameter of the optical fiber with the hole.SOLUTION: Two-directional OTDR measurement is carried out in which reference optical fibers 2 are connected to both ends of an optical fiber 3 with the hole respectively and measurement light beams are made incident from both ends of the connected optical fiber 2 to measure back-scattered light beams. An arithmetic mean value lref at a part of the reference optical fibers 2 and an arithmetic mean value lhf(x) at a position (x) of the optical fiber 3 with the hole are calculated from two obtained back-scattered light waveforms, and a difference (Ihf-Iref) I between the arithmetic mean value lhf and arithmetic mean value lref is found. Based upon the correlation between the found difference I and the hole diameter of the optical fiber 3 with the hole, the hole diameter, the hole position, the surface roughness of the hole, and the bending loss at the position (x) are found.