JP2002162210A - Measuring device for distortion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device for distortion capable of carrying out a good measuring by installing it easily in place with a high degree of accuracy even in the case of many objects. SOLUTION: The device is provided with an optic fiber for sensor 11 which bears a light source and FBG part 21 that reflects light sent from a light source and a multi-wave meter 6 which detects the quantity of expansion and contraction of the optical fiber for a sensor 11 with reflection light reflected from FBG part 21 of the optical fiber for the sensor 11. Screw parts 16 having a male-screw 15 are provided at both ends of the optical fiber 11 for the sensor. Support parts 13 having a female-screw 17 into which the screw parts 16 are screwed together are fit on the objects. The optic fiber for the sensor 11 is set up with clearance between the object S and itself. Male-screws 15 of the screw parts 16 and female-screws 17 of the support parts 13 which screws together are inverted screw each other at both the ends of the optic fiber 11 for the sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain measuring device used for detecting distortion of various structures and displacement of the ground or the like using an optical fiber.

[0002]

2. Description of the Related Art Conventionally, in order to avoid dangers such as collapse of earth and sand and rocks, a guard has been patrolling to grasp the situation. However, such monitoring by patrols is not only very inefficient but also inaccurate.Therefore, crustal deformation is detected by strain gauges to understand the situation. For example, it is also used for detecting distortion of a steel structure such as an iron bridge or a building such as a building, and these defects are grasped in advance.

[0003] However, the strain gauge can only detect a local strain, and is not suitable for a long structure or the like. For this reason, in recent years, a strain measurement device that measures a strain by using an optical fiber and detecting a change in the wavelength of reflected light corresponding to the expansion and contraction rate of the optical fiber has been developed.

[0004]

However, in such a strain measuring device using an optical fiber, the optical fiber as a sensor must be attached to the object under tension with a predetermined tension along the object to be measured. However, the installation work is extremely complicated, and in particular, when it is installed at a large number of installation locations, there is a problem that the installation work requires a great deal of labor and time. For this reason, a structure for easily attaching a strain sensor to an object to be measured using this optical fiber is desired, and it is also required that the tension state of the optical fiber after installation is easily adjusted. Met.

Further, in this strain measuring apparatus using an optical fiber, it is necessary to install the optical fiber on one optical fiber so that the wavelength measurement range of each sensor portion does not overlap.
Because the range of wavelengths of light that can be measured is limited, only a few parts of the sensor can be installed on one optical fiber. However, there is a problem that not only the installation work becomes complicated and prolonged, but also the entire apparatus becomes complicated and the cost becomes high.

The present invention has been made in view of the above circumstances, and can be extremely easily attached to an object to be measured with high accuracy. It is another object of the present invention to provide a low-cost strain measuring apparatus that can perform the adjustment and easily adjust the tension state.

[0007]

According to another aspect of the present invention, there is provided a distortion measuring apparatus according to claim 1, wherein the distortion measuring apparatus is disposed along an object to be measured in accordance with an expansion ratio of light from the light source. A sensor optical fiber having a Bragg greeting portion that reflects light of a specific wavelength, and a measuring device that detects expansion and contraction of the sensor optical fiber from light reflected at the Bragg greeting portion of the sensor optical fiber. Have
A distortion measuring device that measures distortion of the object to be measured based on a detection result of expansion and contraction of the sensor optical fiber, wherein the sensor optical fiber is provided with a threaded portion having male threads at both ends thereof. A support portion having a female screw to which the screw portion is screwed is fixed to the object to be measured, and the sensor optical fiber is connected to the object by screwing the screw portion to the support portion. The male thread of the screw portion and the female screw of the support portion, which are arranged with a gap along and are screwed together, are oppositely threaded at both ends of the sensor optical fiber. And

That is, by screwing the threaded portions at both ends of the sensor optical fiber having the Bragg greeting portion to the supporting portion fixed to the object to be measured, the sensor optical fiber can be very easily placed along the object to be measured. And the female thread of the support part and the female screw of the support part are reverse-threaded at both ends. By rotating the optical fiber for the sensor, The tension can be adjusted by expanding and contracting the optical fiber without twisting while being supported on the object to be measured very easily. Thereby, even if there are many objects to be measured, the sensor optical fiber can be supported on the object with a predetermined tension easily and in a short time.

[0009] The distortion measuring device according to the second aspect is the first aspect.
In the strain measuring apparatus according to the above, a strain measuring optical fiber in which a plurality of the sensor optical fibers supported by a plurality of the objects to be measured are connected by a transmission optical fiber is connected to the measuring device, and the measuring device The expansion and contraction of the optical fiber for sensor of the optical fiber for strain measurement is respectively detected, and the measurement of the distortion of the object to be measured is performed.

As described above, since a plurality of optical fibers for sensors are connected by a transmission optical fiber to use a single optical fiber for strain measurement, the reflected light in the Bragg greeting portion of each optical fiber for sensors is used. By using different wavelengths, it is possible to measure the strain of a large number of objects using a single optical fiber for strain measurement, especially for measuring the strain of a large number of objects arranged over a long distance. It is advantageous.

According to a third aspect of the present invention, there is provided a strain measuring apparatus.
Alternatively, in the strain measuring device according to claim 2, the support portion includes a base support portion fixed to the object to be measured, and a cover support portion fixed to and integrated with an upper portion of the base support portion. The sensor optical fiber is fixed by fixing the cover support to the base support in a state where the thread of the optical fiber for the sensor is arranged on the female thread of the base support. Wherein the screw portion is screwed to the support portion.

That is, the supporting portion for screwing and supporting the screw portion of the sensor optical fiber is composed of a base supporting portion fixed to the object to be measured and a cover supporting portion fixed to the base supporting portion. Since the sensor optical fiber is supported on the object to be measured because it has a half-split structure, simply fix the cover support to the base support with the threaded portion provided on the female thread of the base support. Makes it extremely easy
The screw portion of the sensor optical fiber can be supported in a state in which the screw portion is screwed to the support portion.In particular, when using a strain measurement optical fiber in which a plurality of sensor optical fibers are connected by a transmission optical fiber, Even if these are fusion-spliced in advance, the optical fiber for the sensor can be supported on the object to be measured, and extremely complicated work such as fusion work at the site can be eliminated.

According to a fourth aspect of the present invention, there is provided a strain measuring apparatus.
4. The strain measuring device according to any one of items 3 to 3, wherein the Bragg greeting portion has a relatively lower elastic modulus than other portions.

That is, since the elasticity of the Bragg greeting portion is relatively lower than that of the other portions, the amount of expansion and contraction in the Bragg greeting portion due to the distortion of the object to be measured is reduced. The range of fluctuation of the reflected light is reduced, so that a larger range of the wavelength of the reflected light can be provided within the range of the wavelength of the light that can be measured. The amount of sensor optical fibers that can be installed can be greatly increased. This eliminates the need for preparing a large amount of optical fiber for strain measurement, especially when measuring the strain of a large amount of an object to be measured, and can greatly reduce the cost. Can be facilitated. Further, since many optical fibers for sensors can be provided in one optical fiber for strain measurement, it is particularly advantageous for measuring the distortion of a large number of objects to be measured provided over a long distance.

According to a fifth aspect of the present invention, there is provided a strain measuring apparatus.
In the distortion measuring device described above, the elasticity of the Bragg greeting portion is reduced by providing a reinforcing material around the Bragg greeting portion.

That is, by providing a reinforcing material around the Bragg greeting portion and hardening, the elastic modulus can be reduced very easily and at low cost.

According to a sixth aspect of the present invention, there is provided a strain measuring apparatus.
In the distortion measuring device described above, the elasticity of the Bragg greeting portion is reduced by increasing the hardness of the Bragg greeting portion.

As described above, by increasing the hardness of the Bragg greeting portion, the elastic modulus can be reduced extremely easily and at low cost.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a distortion measuring device according to the present invention will be described below with reference to the drawings. In FIG.
Reference numeral 1 denotes a distortion measuring device according to the embodiment. This strain measuring device 1 has a plurality of strain measuring optical fibers 2, and these strain measuring optical fibers 2 are connected to an optical channel selector 3. A light source 5 and a multi-wavelength meter (measuring device) 6 are connected to the optical channel selector 3 via a circulator 4.

The measurement light from the light source 5 is transmitted to the circulator 4
The optical fiber is sent to the optical channel selector 3 via the optical fiber selector 2, and is sent to the strain measuring optical fiber 2 selected by the optical channel selector 3 among the plurality of strain measuring optical fibers 2. The reflected light from the strain measuring optical fiber 2 to which the measuring light has been sent is sent from the optical channel selector 3 to the multiwavelength meter 6 via the circulator 4.

Next, the strain measuring optical fiber 2 will be described. As shown in FIG.
Has a plurality of sensor optical fibers 11, and the sensor optical fibers 11 are connected to each other and between the sensor optical fiber 11 and the optical channel selector 3 by a transmission optical fiber 12.

The optical fibers 11 for the sensors are attached to the object S to be measured, and measure the distortion of the object S to be measured. As shown in FIGS. 3 and 4, the object to be measured S has a pair of support portions 1 installed at intervals.
The sensor optical fiber 11 of the strain measuring optical fiber 2 is supported by the support 13 with a gap along the measured object S.

As shown in FIG. 5, a transmission optical fiber 12 covered with a coating material 12a is fused and connected to both ends of the sensor optical fiber 11, and a single strain measuring optical fiber is provided. The fused portion 14 is provided with a screw portion 16 on the outer periphery of which a male screw 15 is formed. Then, this optical fiber for sensor 11
The threaded portion 16 on which the male thread 15 is formed is screwed and supported by the female thread 17 of the support portion 13 provided on the measured object S.

Here, the external thread 15 of the threaded portion 16 at both ends of the optical fiber 11 for the sensor and the internal thread 1 of the support portion 13 are provided.
Numerals 7 are reverse screws. That is, by rotating the optical fiber for sensor 11, the threaded portions 1 on both ends are
The amount of screwing of the 6 into the support portion 13 is changed so that the sensor optical fiber 11 can be expanded and contracted without twisting.

As shown in FIG. 6, the support portion 13 includes a base support portion 13a fixed to the object S to be measured, and a cover support portion 13b fixed on the base support portion 13a by screws 13c. The base support 1
In a state where the screw portion 16 is disposed on the female screw 17 of 3a, the cover support portion 13b is covered and fixed by the screw 13c to be integrated, so that the screw portion 16 is screwed to the female screw 17 of the support portion 13. It is to be supported in the state where it was.

The sensor optical fiber 11 has a fiber Bragg grating (hereinafter referred to as an FBG)
Unit 21). The FBG part 21 reflects the light by Bragg diffraction and reflects the laser beam from the side to the core 11b formed at the center of the clad 11a to change the refractive index, as shown in FIG. A plurality of reflection plate portions 22 having different refractive indexes with respect to other portions are formed by a processing method such as a laser irradiation method.

That is, when light enters the FBG section 21, a part of the light is reflected by each of the reflection plate sections 22 of the FBG section 21, interferes with each other, strengthens each other, and is returned as a relatively large reflected light. It has become. And this FBG
When the portion 21 expands and contracts, the interval between the reflection plate portions 22 changes, and accordingly, the wavelength of the reflected light that interferes with each other and returns also changes. That is, the FBG unit 21
By detecting a change in the wavelength of the reflected light from the sensor, the amount of expansion and contraction of the sensor optical fiber 11 is determined, and the distortion of the object S on which the sensor optical fiber 11 is provided can be obtained.

The sensor optical fibers 11 provided on each of the strain measuring optical fibers 2 are provided with different predetermined tensions in advance, so that the reflected light of each sensor optical fiber 11 is The wavelengths do not overlap, and the reflected light of each sensor optical fiber 11 in each strain measuring optical fiber 2 can be specified.

That is, as shown in FIG. 8 and FIG. 9, in the measurable wavelength range Ws (see FIG. 8) which is the range of the wavelength of the measurable light, the measured light reflected from the sensor optical fiber 11 is measured. The reflection wavelength ranges Wb (see FIG. 9), which are ranges of wavelengths including the fluctuation due to the distortion of the object S, are set so as not to overlap with each other.

The sensor optical fiber 11 having the FBG portion 21 having the above structure is covered on its outer peripheral side with a coating 23 made of an ultraviolet curable resin. Further, a tubular reinforcing member 24 made of a resin such as plastic is adhered and fixed to the sensor optical fiber 11 on the outer peripheral side of the coating 23 in a portion where the FBG portion 21 is formed. The hardness of one part is increased and the elastic modulus is relatively lower than that of the other part.

When the sensor optical fiber 11 of the strain measuring optical fiber 2 is supported by the object S, first, both ends of the sensor optical fiber 11 are attached to the base support 13a fixed to the object S. Is provided, and in this state, the cover 13b is covered with the screw 13c.
And the support part 13 is integrated, and the screw part 16 is fixed.
Is screwed into the female screw 17 of the support portion 13 to support the sensor optical fiber 11 along the measured object S.

Next, the optical fiber for sensor 11 is rotated to extend the optical fiber for sensor 11 with a predetermined tension. Here, the external thread 15 of the screw portion 16 and the internal thread 17 of the support portion 13 at both ends of the optical fiber 11 for sensor are
The optical fibers for sensor 1
By rotating 1, the amount of screwing of the screw portions 16 at both ends into the support portion 13 is changed, and the sensor optical fiber 11 is extended without twisting. By performing the above operation, it is possible to easily support the sensor optical fiber 11 along the measured object S with a gap therebetween so that the strain can be measured.

According to the strain measuring device 1 having the above-described structure, the measuring light emitted from the light source 5 is sent to the optical channel selector 3 via the circulator 4 and is used for measuring the strain selected by the optical channel selector 3. It is sent to the optical fiber 2. In the strain measuring optical fiber 2 into which the measuring light is sent, the light is reflected by the FBG unit 21 of the sensor optical fiber 11 supported by the measured object S, and is returned as reflected light. The reflected light reflected by the FBG section 21 of the sensor optical fiber 11 is changed in direction by the circulator 4 and sent to the multi-wavelength meter 6, and the multi-wavelength meter 6 uses the optical fiber for each sensor. The reflected light from 11 is detected, and the state is displayed.

That is, from the fluctuation of the wavelength of the reflected light of each sensor optical fiber 11 detected by the multi-wavelength meter 6, the distortion of the object S on which each sensor optical fiber 11 is supported is detected. Can be. In the optical channel selector 3, the strain measuring optical fibers 2 are sequentially selected and connected, whereby the strain of the object S in the plurality of strain measuring optical fibers 2 is constantly monitored.

As described above, according to the strain measuring apparatus 1 described above, the screw portions 16 at both ends of the sensor optical fiber 11 having the FBG portion 21 are screwed into the support portions 13 fixed to the object S. It is very easy to support the sensor optical fiber 11 with a gap along the measured object S, and the external thread 15 of the screw portion 16 and the internal thread 17 of the support portion 13 are provided at both ends. Since the sensor optical fiber 11 is rotated,
It is possible to adjust the tension of the sensor optical fiber 11 by very easily expanding and contracting it without twisting it while supporting it on the measurement object S. Thereby, even if there are many objects S to be measured, the sensor optical fiber 11 can be supported on the object S with a predetermined tension easily and in a short time.

Further, since a plurality of optical fibers for sensor 11 are connected by a transmission optical fiber 12 to use a single optical fiber 2 for strain measurement, the reflection of each of the optical fibers 11 for sensor in the FBG section 21 is performed. By making the wavelengths of light different, the strain of many objects S can be measured by one optical fiber 2 for strain measurement, and in particular, many objects S arranged over a long distance can be measured. This is advantageous for the measurement of the distortion.

Further, the support portion 13 for screwing and supporting the screw portion 16 of the sensor optical fiber 11 is provided on the object S to be measured.
Base support portion 13a fixed to the base support portion 1a
Since the optical fiber for sensor 11 is supported on the workpiece S, the screw portion is simply screwed into the female screw 17 of the base support portion 13a since the optical fiber for sensor 11 is supported on the workpiece S. By fixing the cover supporting portion 13b to the base supporting portion 13a in a state where the 16 is provided, it is possible to extremely easily support the screw portion 16 of the sensor optical fiber 11 in a state of being screwed to the supporting portion 13. Even if the sensor optical fiber 11 and the transmission optical fiber 12 are fusion-spliced in advance, the sensor optical fiber 11 can be supported on the object S to be measured. Extremely complicated work can be eliminated.

In the optical fiber 11 for the sensor,
The FBG portion 21 has a relatively low elastic modulus compared to other portions and is suppressed from expanding and contracting by the reinforcing member 24 provided on the outer peripheral side thereof. The amount of expansion and contraction in the portion 21 is reduced, and the range of fluctuation of the reflected light from the FBG portion 21 is reduced. Therefore, in the measurable wavelength range Ws which is the range of the wavelength of the measurable light, more The reflection wavelength range Wb can be provided, whereby the installation amount of the sensor optical fiber 11 that can be installed on one strain measurement optical fiber 2 can be greatly increased.

Accordingly, even when measuring a large amount of distortion of the object S to be measured, a large amount of the optical fiber 2 for measuring the strain can be used.
It is not necessary to prepare the optical fiber 2 and the cost can be greatly reduced, and the work of disposing the optical fiber 2 for strain measurement can be facilitated. Also, since many optical fibers 11 for sensors can be provided in one optical fiber 2 for strain measurement, it is particularly advantageous for measuring the distortion of a large number of objects S to be measured provided over a long distance. Moreover, with a simple structure in which the reinforcing member 24 is provided around the FBG portion 21 and hardened, the elastic modulus can be reduced extremely easily and at low cost.

As a means for hardening the portion where the FBG portion 21 is provided, the hardness of the FBG portion 21 itself in the core 11b may be increased. In this case as well, the elastic modulus can be reduced very easily and at low cost. can do.

The above-described strain measuring apparatus 1 can be applied to any object for measuring strain. For example, it is possible to measure not only a steel structure such as an iron bridge or a building such as a building, but also a strain in the ground. It can also be used for monitoring crustal deformation such as land subsidence, or for measuring distortion of the main wing or fuselage of an airplane.

[0042]

As described above, according to the distortion measuring device of the present invention, the following effects can be obtained. According to the strain measuring device of the first aspect, by screwing the screw portions at both ends of the sensor optical fiber having the Bragg greeting portion to the support portion fixed to the object to be measured, the sensor optical fiber can be very easily connected. It is possible to support the sensor optical fiber with a gap along it, and since the male thread of the screw part and the female screw of the support part are reverse-threaded at both ends, the optical fiber for the sensor can be rotated. By moving, the sensor optical fiber can be extended and contracted without twisting while being supported by the object to be measured, and the tension thereof can be adjusted. Thereby, even if there are many objects to be measured, the sensor optical fiber can be supported on the object with a predetermined tension easily and in a short time.

According to the second aspect of the present invention, since a plurality of optical fibers for sensors are connected by a transmission optical fiber to use a single optical fiber for strain measurement, each optical fiber for sensors is used. By making the wavelength of the reflected light different in the Bragg greeting section of, it is possible to measure the distortion of many objects to be measured with one optical fiber for distortion measurement, and in particular, many optical fibers are arranged over a long distance. This is advantageous for measuring the distortion of the measured object.

According to the third aspect of the present invention, the supporting portion for screwing and supporting the screw portion of the optical fiber for the sensor comprises a base supporting portion fixed to the object to be measured and the supporting portion fixed to the base supporting portion. When the optical fiber for the sensor is supported on the object to be measured, the cover is simply provided with the threaded portion provided on the female thread of the base support. By fixing the support portion to the base support portion, it is possible to extremely easily support the sensor optical fiber in a state where the screw portion of the optical fiber for the sensor is screwed to the support portion,
In particular, when using a strain measurement optical fiber in which a plurality of sensor optical fibers are connected by a transmission optical fiber, even if these are fusion-spliced in advance, the object to be measured supports the sensor optical fiber. It is possible to eliminate the need for extremely complicated work such as fusion work at the site.

According to the strain measuring device of the fourth aspect, since the elasticity of the Bragg greeting portion is relatively lower than that of the other portions, the amount of expansion and contraction in the Bragg greeting portion due to the distortion of the object to be measured. Is reduced so that the range of fluctuation of the reflected light from the Bragg greeting portion is reduced, and therefore, a larger wavelength range of the reflected light can be provided within the range of the wavelength of the light that can be measured. (1) The amount of sensor optical fibers that can be installed on one strain measuring optical fiber can be greatly increased. This eliminates the need for preparing a large amount of optical fiber for strain measurement, especially when measuring the strain of a large amount of an object to be measured, and can greatly reduce the cost. Can be facilitated. Further, since many optical fibers for sensors can be provided in one optical fiber for strain measurement, it is particularly advantageous for measuring the distortion of a large number of objects to be measured provided over a long distance.

According to the fifth aspect of the present invention, the elastic modulus can be reduced very easily and at low cost by providing the reinforcing material around the Bragg greeting portion and hardening it.

According to the strain measuring device of the sixth aspect, by increasing the hardness of the Bragg greeting portion, the elastic modulus can be reduced extremely easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a distortion measurement device illustrating a configuration of a distortion measurement device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a strain measuring optical fiber included in the strain measuring device according to the embodiment of the present invention.

FIG. 3 is a plan view illustrating a state in which the optical fiber for sensor of the strain measuring optical fiber of the strain measuring device according to the embodiment of the present invention is attached to an object to be measured.

FIG. 4 is a side sectional view illustrating a state where the optical fiber for sensor of the strain measuring optical fiber of the strain measuring device according to the embodiment of the present invention is attached to the object to be measured.

FIG. 5 is a perspective view illustrating a structure of a sensor optical fiber of the strain measuring device according to the embodiment of the present invention.

FIG. 6 is a perspective view illustrating a structure of a supporting portion that supports a sensor optical fiber of the strain measuring device according to the embodiment of the present invention.

FIG. 7 is a schematic perspective view illustrating the structure of an FBG section provided in the sensor optical fiber of the strain measuring device according to the embodiment of the present invention.

FIG. 8 is a graph illustrating the distribution of reflected light in a strain measurement device using an optical fiber.

FIG. 9 is a graph illustrating the distribution of reflected light in a strain measurement device using an optical fiber.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 strain measuring device 2 strain measuring optical fiber 5 light source 6 multiwavelength meter (measuring instrument) 11 sensor optical fiber 12 transmission optical fiber 13 support 13 a base support 13 b cover support 15 male screw 16 screw 17 female 21 FBG part (Bragg greeting part) 24 Reinforcement material S Measurement object

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiromasa Ito 12 Nishikicho, Naka-ku, Yokohama-shi, Kanagawa Prefecture Mitsubishi Heavy Industries, Ltd. Yokohama Works F-term (reference) 2F065 AA65 BB05 CC40 FF00 FF48 FF51 JJ00 LL00 LL02 LL67 PP22 SS13 UU03

Claims (6)

[Claims] An optical fiber for a sensor, comprising: a light source; a Bragg greeting portion disposed along an object to be measured and reflecting light of a specific wavelength according to the expansion and contraction rate of the light from the light source; A measuring device for detecting expansion and contraction of the optical fiber for the sensor from light reflected by the Bragg greeting portion of the optical fiber, and a distortion of the object to be measured based on a detection result of the expansion and contraction of the optical fiber for the sensor. Wherein the sensor optical fiber is provided with a threaded portion having male threads at both ends thereof, and the object to be measured has a female thread to which the threaded portion is screwed. The supporting portion is fixed, and the screw portion is screwed to the supporting portion, whereby the sensor optical fiber is disposed with a gap along the object to be measured, and Male screw And a female screw of the support part is provided with opposite threads at both ends of the optical fiber for the sensor. 2. A strain measuring optical fiber in which a plurality of sensor optical fibers respectively supported by a plurality of objects to be measured are connected by a transmission optical fiber is connected to the measuring instrument, and the strain is measured by the measuring instrument. 2. The strain measuring apparatus according to claim 1, wherein expansion and contraction of the sensor optical fiber of the measurement optical fiber are respectively detected to measure the distortion of the object to be measured. 3. The support portion has a half-structure including a base support portion fixed to the object to be measured and a cover support portion fixed to and integrated with an upper portion of the base support portion. By fixing the cover support portion to the base support portion in a state where the screw portion of the sensor optical fiber is disposed on the female screw of the base support portion, the screw portion of the sensor optical fiber is The strain measuring device according to claim 1, wherein the strain measuring device is screwed to the support portion. 4. The strain measuring device according to claim 1, wherein the Bragg greeting portion has a relatively lower elastic modulus than other portions. 5. The strain measuring apparatus according to claim 4, wherein an elastic modulus of the Bragg greeting portion is reduced by providing a reinforcing material around the Bragg greeting portion. 6. The strain measuring apparatus according to claim 4, wherein the elasticity of the Bragg greeting portion is reduced by increasing the hardness of the Bragg greeting portion.