Apparatus for measuring convergence using FBG sensor and sensitivity and durability regulation method thereof

An apparatus for measuring a displacement using a fiber Bragg grating sensor, which is applied to a strain sensor using the fiber Bragg grating sensor, the apparatus comprising:

• a pair of attachment members spaced apart from each other by a predetermined interval;
• a first optical fiber and a second optical fiber, installed between the pair of attachment members in a horizontal direction;
• and
• a connection unit installed between the first and second optical fibers and fixed at a predetermined position by tension applied to the first and second optical fibers,
• wherein the fiber Bragg grating sensor is installed to one of the first and second optical fibers having mutually different numbers of strands, so that measurement sensitivity and durability are controllable,
• wherein the strain sensor is installed to a measurement object by using a sensor fixing device, and
• the sensor fixing device comprises a protective tube for containing the strain sensor therein;
• and
• a pair of fixing brackets for fixing both ends of the protective tube to the measurement object.

A method of controlling sensitivity and durability of an apparatus for measuring a displacement using a fiber Bragg grating sensor,

• wherein the fiber Bragg grating sensor is installed to one of a pair of optical fibers which include mutually different numbers of strands and are installed at both sides of a connection unit, such that measurement sensitivity and durability of the fiber Bragg grating sensor are controllable, the method comprising:
• (a) disposing the connection unit between a pair of attachment members to install the pair of attachment members to the connection unit, wherein the pair of attachment members wound around the connection unit at mutually different numbers of times and strands;
• and
• (b) installing the fiber Bragg grating sensor to one of the pair of optical fibers, which has a number of strands less than a number of strands of the other, in order to increase sensitivity of a displacement measurement of a measurement object;
• or
• (c) installing the fiber Bragg grating sensor to one of the pair of optical fibers, which has a number of strands larger than a number of strands of the other, in order to increase durability of the fiber Bragg grating sensor.