KR20120010295A

KR20120010295A - A structure of FBG sensor fixing on one body material

Info

Publication number: KR20120010295A
Application number: KR1020100071714A
Authority: KR
Inventors: 전진용
Original assignee: (주)지티씨코퍼레이션
Priority date: 2010-07-26
Filing date: 2010-07-26
Publication date: 2012-02-03

Abstract

PURPOSE: A structure of FBG sensor fixing on one body material which can measure the deformation degree of the fixing member is provided to simplify a structure by preventing thermal deformation and breaking of optical fiber. CONSTITUTION: A structure of FBG sensor fixing on one body material comprises a fixing member(10) and a optical fiber grating sensor(9). The fixing member is formed in a fixing unit(20) and made of a member which physically moves as same as a measurement target. The fixing member is fixed in order to change according to the external physical power. The fixing unit is formed inside the sensor-device(S). The optical fiber grating sensor is integrally formed with the fixing member.

Description

A structure of FBG sensor fixing on one body material}

The present invention relates to a member integrated fiber grating sensor structure, and more particularly, to fix an optical fiber grating sensor to a fixed member as a whole without the need to correct the difference in displacement due to the temperature change of the optical fiber and the measuring object to be measured. The present invention relates to a member integrated optical fiber grating sensor structure configured to measure a deformation degree of a fixed member that is integrally fixed so as to obtain a measured value that is deformed.

The fiber optic sensor is not corroded, so it has high durability, is not affected by electromagnetic waves, and can be multiplexed.

Various measuring sensors are used to analyze the safety of buildings and other structures, but the use of fiber optic sensors is gradually increasing as a replacement for conventional measuring systems. As the optical fiber constituting the optical fiber sensor as shown in FIG. 1, the core (Fiber Core, 2) and cladding (3) having different refractive indices so that the incident light is totally reflected, and the jacket (4) for protecting the core and the cladding It is usually composed of.

The optical fiber sensor using the optical fiber 1 may be classified into one point, distribution, and multiple types according to the measurement range.

In other words, the one-point type optical fiber sensor is simple to measure the change amount of strain, temperature and pressure of the part where the optical fiber sensor is mounted. There may be some limitations.

ODTR (Optical Time Domain Reflectometry) is a typical example of a distributed optical fiber sensor. This has the advantage that it is useful to measure the overall behavior of the structure using a single optical fiber.

Multi-type fiber optic sensor is a type in which two or more single-point optical fiber sensors are installed in one optical fiber sensor, which corresponds to an FBG sensor (Fiber Bragg Grating Sensor).

The FBG sensor generates a grating by inducing a change in refractive index by periodically scanning a laser in the ultraviolet region to a Ge-doped optical fiber core, as shown in FIG. 2, and generates a grating. It is an optical device that reflects light. When the broadband spectrum is incident on the optical fiber, the wavelength component satisfying the condition is reflected on the optical fiber grating, and the remaining wavelength component passes through and appears in the optical spectrum analyzer.

In addition, the FBG sensor is composed of germanium-silica glass, which is not affected by electromagnetic waves at all, and has a physical advantage that corrosion by moisture or moisture does not occur.

In addition, the FBG sensor has the advantage of installing several Bragg gratings on one strand of optical fiber and installing several sensing units on one strand of optical fiber, and the optical fiber has a very small transmission loss of 0.2 dB per km. This allows the fiber to extend up to tens of kilometers. Since there is little loss of the light source, the FBG sensor has a great advantage to be applied to very long structures such as bridges, railways, rails and pipelines.

Due to these excellent characteristics, the FBG sensor can solve various shortcomings of the conventional electrical resistive sensor, and can measure minute strain and temperature of the structure, and thus has been spotlighted as an alternative to the conventional measuring device.

Looking at the FBG sensor, a pair of optical fiber sensor package (6) is fixed to the measuring plate (8) made of the same member as the measuring body to measure the deformation amount, and transferred to the inside of the optical fiber due to the deformation applied to the measuring plate (8) The amount of deformation can be known by measuring the change in wavelength. However, in this case, a separate measuring plate 8 should be provided, and since the amount of deformation due to the temperature of the measuring plate 8 and the optical fiber is different, a correct measurement value must be corrected for the difference between these differences.

Therefore, a device and a step for calibrating temperature by installing an additional optical fiber for temperature compensation were necessary.

In addition, since the optical fiber is fixed while being pulled while being subjected to strain between the two fixtures, when the shock is received, the optical fiber is broken and the sensor does not operate.

The optical fiber 1 is generally penetrated and fixed through the fixture 7, which is such that the optical fiber 1 is strained by a strain bar, or loosely installed so that strain changes such as tension and compression and The temperature change can be measured, and in order to control the micro tension, in particular, the micro adjustment screw is installed in the protective tube.

The optical fiber is coated with a covering jacket of about 245 ~ 250 ㎛ because of the risk of its own breakage, mostly acrylate coating. The coated jacket has the advantage of protecting the optical fiber, but if it is directly attached to the coated jacket surface and the test specimen without partially peeling the optical fiber, slippage occurs between the jacket and the cladding to accurately measure the tensile behavior and the behavior against long-term deformation due to the tensile force. It becomes impossible to do.

Therefore, the optical fiber from which the protective jacket has been removed is fixed to the fastener 7 to the optical fiber sensor package 6. The shape or size of these fixtures can be developed depending on the shape and attachment method of the package and the shape and use of the surface of the specimen.

It is pointed out that even the optical fiber for the FBG sensor wrapped in the protective tube is very vulnerable to external factors such as impact on the concrete, and the FBG sensor has a characteristic that responds to both temperature and stress changes to compensate for the measured measured value. Additional thermometer installation and signal processing work was required.

In the case of such an optical fiber sensor, since the optical fiber 1 is fixed by a pair of fasteners 7 and is tensioned and installed with an appropriate force, the risk of damage still exists.

The present invention has been made in order to solve the problems described above, but to overcome the brittleness of the optical fiber used as an optical fiber grating sensor, there is an object to provide a member-integrated optical fiber grating sensor structure that does not require a separate temperature correction.

In addition, the optical fiber and the fixing member is formed to move integrally, so that the optical fiber and the fixing member have the same amount of deformation in accordance with the temperature change so that no separate temperature compensation is required.

It is intended to measure the change in the wavelength passing through the optical fiber grating sensor by causing the optical fiber to be deformed integrally with the bending or deformation of the fixing member made of the same material as the measuring object.

The present invention in the structure for fixing the optical fiber grating sensor in the sensor device using the optical fiber grating sensor in order to achieve the above object, the physical behavior such as the measuring body to the fixing portion 20 formed inside the sensor device (S) Fixing member 10 made of a member to be fixed so as to change in accordance with the external physical force, the optical fiber grating sensor 9 integrally with the fixing member 10 is fixed with an adhesive in a tensioned state in accordance with the measuring instrument characteristics, integral It is characterized in that it is configured to measure the wavelength due to the change in the gap between the grating of the optical fiber grating sensor 9, such as the deformation of the fixing member 10, the fixing member 10 on the upper surface of the groove-shaped body 11 The groove 11-1 is formed in the longitudinal direction, and the optical fiber grating sensor 9 is inserted into the groove 11-1 so as to be integrally fixed to the groove-shaped body 11 by the adhesive 11-2, The fixing member 10 is on the upper surface of the plate-shaped body 12 In the state in which the optical fiber grating sensor 9 is placed in the longitudinal direction, the adhesive member 11-2 is fixed integrally with the plate-shaped body 12, or the fixing member 10 is formed of the hollow hollow in the longitudinal direction formed in the tubular body 13. It provides a member-integrated optical fiber grating sensor structure, characterized in that the optical fiber grating sensor 9 is inserted into the hole (13-1) is fixed integrally with the tubular body (13) by the adhesive (13-2).

As described above, according to the present invention, the optical fiber grating sensor is attached to the holding member of the same material as the measuring body so as to be integrally deformed to measure the change of the measuring body by measuring the change of the reflection wavelength of the optical fiber grating sensor. It can be effective.

Since the optical fiber grating sensor is fixed integrally with the fixing member, there is no problem of breaking the optical fiber, and there is no need to compensate for the temperature deformation caused by the other material of the optical fiber grating sensor and the fixing member, thereby simplifying the structure.

1 is a view showing a conventional optical fiber.
2 is a view schematically showing a FBG structure of a conventional optical fiber.
3 is a view showing a conventional optical fiber sensor structure.
Figure 4 is a perspective view showing a holding member of the member integrated optical fiber grating sensor structure of the present invention.
5 is a cross-sectional view showing a holding member of the member integrated optical fiber grating sensor structure of the present invention.
Fig. 6 is a schematic view showing a sensor device in which the member integrated optical fiber grating sensor structure of the present invention is constructed.
FIG. 7 is a perspective view showing another embodiment of the fixing member used in the member integrated optical fiber grating sensor structure of the present invention. FIG.
FIG. 8 is a perspective view showing another embodiment of the fixing member used in the member integrated optical fiber grating sensor structure of the present invention. FIG.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, the term or word used in the present specification and claims is based on the principle that the inventor can appropriately define the concept of the term in order to best describe the invention of his or her own. It should be interpreted as meanings and concepts corresponding to the technical idea of

According to the present invention, an optical fiber 1 having an optical fiber grating FBG 5, that is, an optical fiber grating sensor 9 is integrally fixed to directly touch the fixing member 10 so that the wavelength of light generated from the light emitting part is changed to the optical fiber grating 5. By measuring the wavelength change passing through the optical fiber grating sensor 9 as modified according to the deformation of the fixing member 10 to pass through the applied to the measuring object to know the strain value, the optical fiber slip does not occur The main configuration is to fix the fixing member and the optical fiber grating sensor as a whole so as not to break.

In the present invention, the optical fiber 1 formed in the core of the optical fiber grid 5 is referred to as an optical fiber grating sensor 9, and the optical fiber grating sensor 9 is integrally fixed to the fixing member 10, and the fixing member 10 is As shown in FIGS. 4 and 5, the grooved body 11, the plate body 12 shown in FIG. 7, and the tubular body 13 shown in FIG. 8 may be formed.

The sensor device (S) is formed with a fixing part 20 for fixing an optical fiber grating, that is, an optical fiber grating sensor, formed at two points, and deformed as the deformation of the measuring object is fixed in the state where the optical fiber grating sensor is fixed. The refractive index change is measured. The present invention relates to a change in the method of fixing the optical fiber grating sensor at two points, unlike the conventional invention, in the present invention, the optical fiber grating sensor 9 is fixed to the fixing member 10 to be integrally integrated with the object to be measured. The deformation value of the fixing member 10 formed of a member having a similar behavior to the variation is measured to obtain a deformation value.

In the sensor device (S) of the present invention, there are various methods for deforming the fixing member 10 according to an external force, and the shape of the fixing portion 20 for fixing the fixing member 10 according to the structure may be Can vary. That is, only one end of the fixing member 10 may be fixed to the fixing unit 20, and the tensile contraction force may be converted to a direction perpendicular to the one end of the fixing member 10 to bend the other end to measure the value. .

The present invention relates to a fixing member for fixing the optical fiber grating sensor in the sensor device (S) rather than the sensor device (S).

The optical fiber is composed of a core, cladding, and a jacket, which is a coating protecting the core and cladding, and light is transmitted from the core and the cladding, and the material constituting the glass is glass. The transmission of light (light) is transmitted through the glassy core portion having a high refractive index, and the glassy cladding portion having a low refractive index serves to prevent the loss of light transmitted to the core portion.

As described above, since the core part and the cladding part made of glass are vulnerable to external impacts, the core part and the cladding part are protected by a covering jacket such as polymer or acrylate.

In the present invention, in order to protect the glass fiber optical fiber grating sensor that is easy to be broken in this way from external impact, it is fixed and integrated with the fixing member 10 as a whole.

As described above, the optical fiber grating sensor 9 is integrally fixed to the fixing member 10. As shown in FIGS. 4 and 5, the groove body 11 having the groove 11-1 formed along the longitudinal direction of the upper surface is shown. The optical fiber grating sensor 9 is fixed to the groove 11-1 by inserting the optical fiber grating sensor 9 into the groove 11-1 and then using an adhesive 11-2 or a hardener.

At this time, unlike the prior art, the optical fiber grating sensor 9 is fixed by the adhesive 11-2 after temporarily fixing by appropriate force. It is preferable to use such an adhesive 11-2 that can harden and fix the optical fiber grating sensor 9 to the groove part 11-1 rapidly.

The grooved body 11 measures the degree of bending of the fixing member 10 by using a member in which the same deformation behavior as that of the object to be measured is measured so as to measure the degree of deformation or deformation by applying force to the fixing member 10. Measure

Fixing ends 11-3 are formed at both ends of the groove-shaped body 11 to be molded in a convenient form to be fixed, but need not necessarily be limited to the shape as shown in the drawings.

In another embodiment, as shown in FIG. 7, the optical fiber grating sensor 9 is placed on the upper surface of the plate-shaped body 12 in the longitudinal direction, and the adhesive 12-1 is applied to fix the optical fiber grating sensor 9. . At this time, the optical fiber grating sensor 9 is preferably fixed by applying an adhesive in a state where both sides are temporarily fixed by fixing.

In another embodiment, as shown in FIG. 8, the optical fiber grating sensor 9 is inserted into and fixed to the tubular body 13 formed by penetrating the hole 13-1 in the longitudinal direction at the center thereof. This is sufficient if the hollow hole 13-1 is formed irrespective of the circular tube or the square tube. The optical fiber grating sensor 9 is inserted into the hole 13-1 of the tubular body 13 to apply and fix the adhesive 13-2. To this end, the adhesive 13-2 may be applied by forming a plurality of adhesive injection holes connected to the hollow holes 13-1 on the outside of the tubular body 13.

The groove 11-1 of the groove-shaped body 11 of the fixing member 10 may be formed to have a depth and a width enough to accommodate an optical fiber.

As described above, an optical fiber grating sensor generates an optical fiber grating by periodically inducing a refractive index change by periodically scanning a laser in an ultraviolet region to an optical fiber core, and is an optical device that reflects light of a specific wavelength determined by the gap of the grating. When light reaches the grating, wavelength components satisfying certain conditions are reflected from the optical fiber grating, and the remaining wavelength components pass through and appear in the optical spectrum analyzer. Accordingly, when the distance between the gratings is changed by the deformation of the fiber grating sensor, the reflected wavelength is changed by the difference.

This sensitive fiber optic sensor does not strip part of the optical fiber and attaches directly to the coated jacket surface and the test specimen, causing slippage between the catch and the cladding, making it impossible to accurately measure the tensile and long-term deformation due to the tensile force. The coated jacket with the acrylic lake coating protecting the cladding was partially peeled off and then attached to the portion to be measured.

However, in the present invention, since the optical fiber grating sensor 9 is attached to the fixing member 10 as a whole, there is no need to worry about slip phenomenon.

In addition, since the adhesive is produced in a state in which the tensile force is already applied in the factory manufacturing step, a separate strain adjustment is unnecessary in the sensor installation step.

1: fiber optic 2: core
3: cladding 4: jacket
5: optical fiber lattice 6: optical fiber sensor package
7: fixture 8: measuring plate
10: fixing member 11: grooved body
11-1: Groove 11-2: Adhesive
11-3: fixed end 12: plate body
12-1: adhesive 13: tubular body
13-1: Hole 13-2: Adhesive
20: fixed part S: sensor device

Claims

In the structure of fixing the optical fiber grating sensor in the sensor device using the optical fiber grating sensor,
The fixing member 10 made of a member having a physical behavior such as a measuring object is fixed to the fixing portion 20 formed inside the sensor device S so as to change according to an external physical force, and is integral with the fixing member 10. The optical fiber grating sensor 9 is fixed with an adhesive in a state where the characteristics of the measuring device are tensioned according to the characteristics of the measuring instrument. A member integrated optical fiber grating sensor structure configured to measure.

The fixing member 10 is a state in which the groove 11-1 is formed in the longitudinal direction on the upper surface of the groove-shaped body 11, the optical fiber grating sensor 9 is inserted into the groove 11-1. The member integrated optical fiber grating sensor structure, which is fixed integrally with the groove-shaped body 11 by an adhesive 11-2.

According to claim 1, wherein the fixing member 10 is integrally fixed to the plate-shaped body 12 with an adhesive 11-2 in a state in which the optical fiber grating sensor 9 is placed in the longitudinal direction on the upper surface of the plate-shaped body 12 A member integrated optical fiber grating sensor structure, characterized in that.

2. The fixing member (10) according to claim 1, wherein the fixing member (10) is tubular with an adhesive (13-2) in a state where the optical fiber grating sensor (9) is inserted into the hollow hole (13-1) in the longitudinal direction formed in the tubular body (13). A member integrated optical fiber grating sensor structure, which is fixed integrally with the body (13).