JP2001272213A - Distortion evaluator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable distortion evaluator which enables the measurement of both of a local static distortion and a wide ranging dynamic distortion. SOLUTION: The distortion evaluator, which has an optical fiber 2 stuck on an object on use for evaluating the distortion of the object includes an FBG measuring device 1, a BOTDR 3 connected to the FBG measuring device 1 via the optical fiber 2 to be measured and filters 8 and 9 with a wavelength band which are provided respectively at connection parts between the FBG measuring device 1, the BOTDR 3 and the optical fiber 2 to be used by the FBG measuring device 1 and the BOTDR 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain evaluation apparatus using an optical fiber, which can measure a local and static strain and a dynamic strain over a wide area, and particularly to a bridge, an aircraft,
The present invention relates to a distortion evaluation device applicable to large structures such as ships and plants.

[0002]

2. Description of the Related Art Conventionally, a strain evaluation apparatus is used, for example, for laying an optical fiber, which is a component of the apparatus, on a structure and evaluating the amount of deformation of the structure from the amount of distortion of the optical fiber. .

Recently, as a method of evaluating this distortion, the frequency shift of backward Brillouin scattered light, that is, the value obtained by subtracting the center frequency of the Brillouin scattered light spectrum from the frequency of the incident light increases with the tensile stress applied to the optical fiber. Focusing on this, a method of searching for an abnormal point of an optical fiber or an optical cable from the increase in the Brillouin frequency shift has been developed.

[0004] The frequency shift of the backward Brillouin scattered light increases with the tensile stress applied to the optical fiber, that is, the elongation strain of the optical fiber, which is the relative elongation due to the equivalent tensile stress.

Here, the relationship between Brillouin frequency shift and distortion is given by the following equation.

Fb (ε) = fb (0) (1 + C · ε) (1) In equation (1), ε is a distortion, and C is a proportional constant and is about 4.5. Fb (0) is the Brillouin frequency shift when the strain ε is zero, and the value when the wavelength of the incident light is 1550 nm is 11 GHz, for example.

When the above equation (1) is solved for the strain ε, the following equation is obtained: ε = {fb (ε) −fb (0)} / {Cfb (0)} (2)

That is, the distortion of the optical fiber can be obtained by measuring the Brillouin frequency shift.

In order to measure the Brillouin frequency shift, it is necessary to efficiently receive Brillouin scattered light having a weak light intensity. As an apparatus using this method, for example, a BOTDR (Brillouin Optical)
Fiber Time Reflectometry
y) is known. Here, the BOTDR has a function of injecting a pulse of light into an optical fiber and measuring a strain distribution of the optical fiber from a frequency change of Brillouin scattered light of the backscattered light.

[0010] Conventionally, FBG (Fiber Br)
A technique called "agg grating" is known.
In this method, a special processing called a diffraction grating (a waveguide whose refractive index change is constant) is applied to a part of an optical fiber in advance by an optical method, and the function to detect the expansion and contraction of the processed part sharply is used. It is. In other words, the FBG allows ordinary light of the light transmitted through the optical fiber to pass through the diffraction grating, but reflects light of a specific color at the diffraction grating portion, and measures the frequency to make the diffraction grating clear. A method for measuring the strain of an optical fiber in a certain portion will be described.

[0011] However, the BOTDR can measure the strain distribution of the optical fiber, but requires a measurement time of about 5 minutes to 1 hour, and has a problem that only a static strain can be measured. On the other hand, the FBG can measure dynamic (kHz) distortion, but has a problem that it is limited to a certain part of the sensor. In both cases, it is necessary to measure the temperature simultaneously for temperature correction.

However, for example, in order to evaluate the soundness of a large structure such as a plant, it is necessary to grasp the entire deformation. However, in order to grasp the fatigue of the structural material, various measures such as measuring the vibration period are required. It is necessary to collect data from a viewpoint. Conventionally, as a strain distribution measuring device using Brillouin scattered light, Japanese Patent Application Laid-Open No. 4-248426 is known, but it has not been sufficiently satisfactory.

[0013]

SUMMARY OF THE INVENTION The first invention of the present application has been made in view of such circumstances, and an FBG measuring instrument,
An optical fiber strain / loss measuring instrument connected to the FBG measuring instrument via an optical fiber to be measured; and an FBG measuring instrument, and a connecting portion between the strain / loss measuring instrument and the optical fiber, respectively. By providing a configuration including a filter in a wavelength band used by each measuring instrument, a highly reliable distortion evaluation apparatus capable of measuring both local and static distortion and dynamic distortion over a wide area is provided. The purpose is to:

According to a second aspect of the present invention, there is provided a distortion evaluation apparatus which uses an optical fiber attached to an object and evaluates distortion of the object, the FBG measuring instrument being connected to the FBG measuring instrument via the optical fiber to be measured. The invention according to the first aspect of the present invention has a configuration including an optical fiber strain / loss measuring instrument connected to the optical fiber and a wavelength branching filter connected to the FBG measuring instrument and the strain / loss measuring instrument via an optical fiber. It is another object of the present invention to provide a distortion evaluation device that can obtain the same effect and can select only light having a specific wavelength and send it to each measuring instrument.

A third invention is an FBG measuring instrument and this FB
A temperature distribution measurement device connected to the G measurement device via an optical fiber to be measured, the FBG measurement device, and a connection portion between the temperature distribution measurement device and the optical fiber;
By providing a configuration including a measuring device and a filter in a wavelength band used by the temperature distribution measuring device, the same effects as those of the first invention can be obtained, and the temperature distribution measuring device can be used as a measuring device for temperature correction of the FBG. An object of the present invention is to provide a usable distortion evaluation device.

According to a fourth aspect of the present invention, there is provided an FBG measuring instrument,
A temperature distribution measurement device connected to the G measurement device via an optical fiber to be measured, and the FBG measurement device, a configuration including a wavelength branching filter connected via the temperature distribution measurement device, In addition to obtaining the same effect as that of the first invention, a strain evaluation device which can select only light having a specific wavelength and send it to each measuring device, and can use the temperature distribution measuring device as a measuring device for temperature correction of FBG. The purpose is to provide.

[0017]

According to a first aspect of the present invention, there is provided a distortion evaluation apparatus which uses an optical fiber attached to an object and evaluates distortion of the object, comprising: an FBG measuring instrument; An optical fiber strain / loss measuring instrument connected via an optical fiber to be measured, and the FBG measuring instrument;
A distortion evaluation device comprising: a filter for a wavelength band used by each measuring device, which is provided at each connection portion between the distortion / loss measuring device and the optical fiber.

The second invention of the present application is directed to a distortion evaluation apparatus which is used by attaching an optical fiber to an object and evaluates distortion of the object, comprising an FBG measuring instrument, an FBG measuring instrument and an optical fiber to be measured. A strain evaluation device comprising: an optical fiber strain / loss measuring device connected via a fiber; a wavelength branching filter connected to the FBG measuring device and the strain / loss measuring device via an optical fiber. .

The third invention of the present application is directed to a distortion evaluating apparatus which is used by attaching an optical fiber to an object and evaluates distortion of the object, comprising: an FBG measuring instrument; and an FBG measuring instrument and an optical fiber to be measured. A temperature distribution measuring instrument connected via the FBG measuring instrument, a filter of a wavelength band used by the FBG measuring instrument and the temperature distribution measuring instrument provided at each connection portion between the temperature distribution measuring instrument and the optical fiber. A distortion evaluation device comprising:

According to a fourth aspect of the present invention, there is provided a distortion evaluation apparatus for evaluating the distortion of an object, wherein the optical fiber is used by attaching the optical fiber to the object. A distortion evaluation device comprising: a temperature distribution measuring device connected via the temperature distribution measuring device; the FBG measuring device; and a wavelength branching filter connected via the temperature distribution measuring device.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a distortion evaluation apparatus according to the present invention will be described in detail. In the first invention, the distortion evaluation device includes:
Basically, an FBG measuring device that measures local static strain, an optical fiber strain / loss measuring device (BOTDR) that measures static distortion over a wide area, and a diffraction grating formed on the optical path. It is composed of an optical fiber and an FBG measuring instrument, and a filter formed at each connection between the BOTDR and the optical fiber. Here, the FBG measuring instrument and BOTDR are:
For example, they may be arranged to face each other via an optical fiber as shown in FIG. 1 described later, or may be arranged in a state as shown in FIG. 4, for example. Further, as a means for transmitting light to the FBG measuring device and the BOTDR, an optical coupler for dividing propagating light at a predetermined ratio can be used.

A second invention is characterized in that a wavelength branching filter is used instead of the optical coupler. When a wavelength branching filter is used, only light of a specific wavelength can be selectively transmitted to the FBG measuring instrument or BOTDR by the wavelength branching filter, so that different wavelengths of light can be selected as shown in FIG. 4 using an optical coupler. It is not necessary to use the first and second filters to perform the processing (see FIG. 5). The BOTDR
Can measure not only distortion but also light loss.

A third aspect of the present invention is characterized in that a temperature distribution measuring device is used in place of the BOTDR. In this case, the temperature distribution measuring device is used as a measuring device for temperature correction of the FBG, but the BOTDR itself can be used as a temperature distribution measuring device.

According to a fourth aspect of the present invention, an FBG is used as an acceleration sensor (or a vibration sensor), and a strain distribution of a structure deformed by the external force is measured by BOTDR while simultaneously grasping an external force due to acceleration (or vibration). It is characterized by comprehensively judging the degree of damage. Note that a pressure sensor may be used instead of the above-described pressure sensor or the like. For example, if a pressure sensor is installed on a river embankment or the like, when a river overflows, a rise in the water level can be sensed and the location of the flood can be specified. Further, the pressure sensor and the like are applicable to all strain measurement devices having an optical sensor formed with FBG.

In the first and second inventions, BOTDR
Are used to determine the maximum, minimum and intermediate values of the fluctuation distortion in the optical fiber by determining the maximum value, minimum value and intermediate value of the frequency shift from the measured intensity distribution of the scattered light. The frequency of the distortion can be measured by the FBG measuring device based on the value of. Thereby, the amplitude of the distortion caused by the amplitude of the structure, the central distortion,
The frequency can be grasped.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. However, the materials, numerical values, and the like of the respective constituent members described in the following examples are merely examples, and do not specify the scope of rights of the present invention.

(Embodiment 1) Referring to FIG. Reference number 1 in the figure indicates an FBG measuring instrument. In this FBG measuring instrument 1,
An optical fiber strain / loss measuring instrument (BOTDR) 3 is arranged to face the FBG measuring instrument 1 via an optical fiber 2 to be measured. Here, the BOTDR3 can measure optical fiber distortion and optical loss. The optical fiber 2
Is composed of a core 4 and a clad 5 disposed outside the core 4 as shown in FIG. here,
In the middle of the core 4, for example, a first F as a sensor
BG6 and second FBG7 are formed respectively.

The FBGs 6 and 7 specifically form a diffraction grating on a part of the optical path of the optical fiber 2 in advance by an optical method. That is, the FBGs 6 and 7 are formed with gratings having different grating intervals W1 and W2 according to the wavelength of light to be detected. Therefore, the FBG6
In No. 7, a specific wavelength range corresponding to the grating interval can be detected. Specifically, the FBG 6 can detect a sharp wavelength in, for example, a band of 1300 nm as shown in FIG.
In the BG7, for example, as shown in FIG.
A sharp wavelength can be detected in nm. Filters 8 and 9 for the wavelength bands used by the FBG measuring device 1 and the BTDR 3 are provided at the connection portions between the FBG measuring device 1 and the BOTDR 3 and the optical fiber 2, respectively.

According to the first embodiment, the FBG measuring device 1 and B
OTDR3 and the first FBG in the path connecting them
6. The optical fiber 2 having the second FBG 7 and the filters 8 and 9 of the wavelength band used by the FBG measuring instrument 1 and the BOTDR 3 respectively provided at the connection portions of the FBG measuring instrument 1 and the BOTDR 3 and the optical fiber 2. Are provided. As described above, by combining the FBG measuring device 1 and the BOTDR 3, it is possible to measure a local dynamic distortion and a wide-area static distortion.

(Embodiment 2) Referring to FIG. However, FIG.
The same members are denoted by the same reference numerals and description thereof will be omitted. Reference numeral 11 in the figure denotes an optical coupler in which the FBG measuring instrument 1 and the BOTDR 3 are connected via an optical fiber 2. Although not shown, the other end of the optical fiber 2 is evenly attached to an object to be measured. In the optical coupler 11, for example, 50% of the 100% of the light transmitted through the optical fiber 2 is transmitted in the direction of the first filter 5, and the remaining 50%
Is transmitted in the direction of the second filter 6. In the first filter 5, only light having a wavelength in the band used by the BOTDR3, for example, light having a wavelength near 1550 nm is transmitted to the BOTDR3, and only light having a wavelength in the band used by the FBG measuring instrument 1 and a wavelength near 1300 nm is FBG. It is transmitted to the measuring instrument 1.

According to the second embodiment, light is branched by the optical coupler 11 into the first filter 5 and the second filter 7 at a predetermined ratio (for example, 50% each). Can transmit light having wavelengths of 1550 nm and 1300 nm. Therefore, similarly to the first embodiment, local dynamic distortion measurement and wide-area static distortion measurement can be realized.

(Embodiment 3) Referring to FIG. However, FIG.
The same members are denoted by the same reference numerals and description thereof will be omitted. Example 3
Is a wavelength branching filter 1 instead of the optical coupler of the second embodiment.
2 is provided, and the first filter and the second filter are removed. In the third embodiment as well, the other end of the optical fiber 2 is affixed evenly to the object to be measured, although not shown. The wavelength branching filter 1
2, for example, when light having wavelengths of 1550 nm and 1300 nm passes through the optical fiber 2, light near 1550 nm is transmitted to the BOTDR 3 side by the wavelength branching filter 12, and light near 1300 nm is transmitted to the FBG measuring instrument 1 side. And transmitted.

According to the third embodiment, the wavelength branching filter 1
BOTDR3, FBG
Since each can be transmitted to the measuring instrument 1, a decrease in light energy can be avoided as compared with the second embodiment.

(Embodiment 4) Referring to FIG. However, the same members as those in FIGS. 1 and 5 are denoted by the same reference numerals, and description thereof will be omitted. In the fourth embodiment, the temperature distribution measuring device 13 is used instead of the BOTDR in the third embodiment, and the first FBG 6 and the second FB are used.
It is characterized in that it is used as a measuring device for temperature correction of G7. Note that the optical fiber 2 is attached only to the FBG portion, and the other portions are free.

By the way, the BOTDR is changed to the FBGs 6, 7
When used as a temperature correction, the relationship between the frequency shift and the temperature is as shown in FIG. 7, and the relationship between the temperature and the apparent strain is as shown in FIG. Also, the distance and the first F
The relationship between the correction temperature of the BG 5 and the correction temperature of the second FBG 6 is as shown in FIG.

According to the fourth embodiment, a decrease in light energy can be avoided as in the third embodiment, and the temperature correction of the FBGs 6 and 7 can be performed by providing the temperature distribution measuring device 13, so that more accurate measurement can be performed. realizable.

In the fourth embodiment, the case where the temperature distribution measuring device is used instead of the BOTDR has been described. However, the present invention is not limited to this. Has an effect.

(Embodiment 5) Referring to FIG. However, the same members as those in FIGS. 1 and 5 are denoted by the same reference numerals, and description thereof will be omitted. The strain measuring apparatus according to the fifth embodiment includes a first FBG 6 and a second FBG 6.
FBG7 to acceleration sensor (or vibration sensor) 14
The other basic configuration is the same as that of the third embodiment.

Reference numeral 15 in the figure denotes an FBG measuring instrument having an acceleration sensor (or vibration sensor) 14 function. A part of the optical fiber 2 that has passed through the wavelength branching filter 12 from the FBG measuring device 14 or the BOTDR 3 is evenly attached to the structure 15 corresponding to the position where distortion should be evaluated.

According to the fifth embodiment, the strain distribution of the structure 15 deformed by the external force is measured by the FBG measuring device 14 while simultaneously grasping the external force due to the acceleration (or the external force due to the vibration). The degree can be determined comprehensively.

In the fifth embodiment, the case where the FBG measuring device having the function of the acceleration sensor (or the vibration sensor) is used is described. However, the present invention is not limited to this. May be detected by a pressure sensor.

In the fifth embodiment, the case where the FBG measuring device has the acceleration sensor (or vibration sensor) function has been described. However, the present invention is not limited to this, and the BOTDR has the acceleration sensor (or vibration sensor) function. Is also good.

(Embodiment 6) Although Embodiment 6 is not shown, the basic components are, for example, FB as shown in FIG.
G measuring instrument 1, BOTDR3, optical fiber 2, first filter 8 and second filter 9 as constituent members,
Japanese Patent Application No. Hei 10-747 filed by the present applicant for TDR3
By using the FBG measuring instrument 1 and measuring the frequency of the distortion as in the case of the prior application 9 (prior application), the amplitude, the central distortion, and the frequency of the distortion caused by the vibration of the whole structure are grasped.

Here, “using BOTDR3 as in the prior application” means that the BOTDR3 is obtained by obtaining the maximum value, the minimum value and the intermediate value of the frequency shift from the measured intensity distribution of the scattered light. It is used to find the maximum, minimum and intermediate values of the fluctuation distortion to 2.

Hereinafter, a sixth embodiment will be described with reference to FIGS. In BOTDR, as in the prior application, the intensity distribution of Brillouin scattered light (hereinafter referred to as light distribution) obtained as a result of measurement of a fluctuating distortion has a broad shape as shown in FIG. The reason for this is that the Brillouin scattered light shifts in the frequency direction during the measurement, and the BOTDR averages it over a long time. Here, the light distribution includes a spread from the Brillouin scattered light shifted to the high frequency side to the Brillouin scattered light shifted to the low frequency side. Therefore, the shift amount on the high frequency side and the low frequency side is obtained from the light distribution by the following procedures 1) to 3).

1) As shown in FIG. 12, the frequency (high-frequency side fH and low frequency) of a portion lower than the maximum value (the average value of the broad portion is almost the same) by a specific level (for example, 3 dB) from the light distribution. Frequency side fL) is obtained.

2) As shown in FIG. 13, from the relationship between the frequency bandwidth of the Brillouin scattered light and the level of the Brillouin scattered light determined in advance, how far the specific level-reduced portion is from the center frequency Is required. Therefore, the center frequency (fCH, fCL) of the shifted light can be calculated from fH and fL obtained in 1) above (that is, fCH is obtained by subtracting half the width from fH, and fL
FCL is obtained by adding half of the width to.

3) Substituting fCH and fCL obtained in 2) above into the relationship between the frequency shift and the distortion of the optical fiber (FIG. 14), and converting them into distortion values εH and εL, the maximum and minimum values of the fluctuation distortion are obtained. Is obtained.

The value obtained in this manner is, as shown in FIG. 15, a dynamic distortion variation range (center, amplitude (maximum, minimum)).
Is shown. Combining this measurement with the dynamic strain of the FBG can simulate actual strain variations. Specifically, FB
From fCH and fCL at the position of the optical fiber with G,
When εH1 and εL1 are obtained, the maximum value and the minimum value of the dynamic strain measured by FBG should match εH1 and εL1.
At this time, εH at the position P where the change in dynamic strain is to be estimated
2, εL2 is calculated, and (εH2-εL
2) By multiplying by (εH1−εL1), the dynamic strain at the position P can be estimated.

According to the sixth embodiment, as shown in FIG.
The distribution of the distortion range obtained by the OTDR is obtained with a predetermined amplitude. Also, as shown in FIG.
And the dynamic strain distribution by the combination of That is, in the portion where the first FBG and the second FBG were formed in the optical fiber, distortion measured by the FBG was confirmed as shown in FIG. As described above, by using the BOTDR as described above and measuring the frequency of the distortion with the FBG, the amplitude, the central distortion, and the frequency of the distortion caused by the amplitude of the structure can be grasped.

In the sixth embodiment, the case where the BOTDR is used in the arrangement shown in FIG. 1 has been described.
The present invention is not limited to this, and may be used in an arrangement as shown in FIG. 4 or FIG.

[0052]

As described above in detail, according to the first aspect, an FBG measuring instrument, a BOTDR measuring instrument connected to the FBG measuring instrument via an optical fiber to be measured, the FBG measuring instrument, Both static distortion and dynamic distortion can be measured by using a configuration that includes a BOTDR measuring instrument and a filter for the wavelength band used by each measuring instrument, which is provided at each connection part of the optical fiber. A highly reliable strain measuring device can be provided.

According to the second invention, an FBG measuring instrument, an optical fiber strain / loss measuring instrument connected to the FBG measuring instrument via an optical fiber to be measured, the FBG measuring instrument, the distortion / loss By providing a configuration including a measuring device and a wavelength branching filter connected via an optical fiber, the same effect as that of the first invention can be obtained. In addition, only light having a specific wavelength is selected and sent to each measuring device. And a distortion evaluation device capable of performing the evaluation.

According to the third invention, an FBG measuring instrument, a temperature distribution measuring instrument connected to the FBG measuring instrument via an optical fiber to be measured, the FBG measuring instrument, the temperature distribution measuring instrument, It is provided at each connection part with the fiber,
By providing a configuration including an FBG measuring device and a filter of a wavelength band used by the temperature distribution measuring device, the same effects as those of the first invention can be obtained, and the temperature distribution measuring device can be used as a measuring device for correcting the temperature of the FBG. A distortion evaluation device that can be used as a device can be provided.

According to the fourth aspect, the FBG measuring instrument, the temperature distribution measuring instrument connected to the FBG measuring instrument via the optical fiber to be measured, the FBG measuring instrument, and the temperature distribution measuring instrument via the temperature distribution measuring instrument. In addition to obtaining the same effect as the first aspect of the present invention, it is possible to select only a specific wavelength of light and send it to each measuring instrument, and to measure the temperature distribution. The distortion evaluation device which can use the device as a measuring device for temperature correction of FBG can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a strain measurement device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an optical fiber used in the strain measuring device of FIG.

FIG. 3 is an explanatory view of a diffraction grating of a core constituting the optical fiber of FIG. 2;

FIG. 4 is an explanatory diagram of a strain measurement device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a distortion measuring device according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of a distortion measuring device according to a fourth embodiment of the present invention.

7 is BOTDR, which is one configuration of the distortion measuring device of FIG.
FIG. 6 is a correlation diagram between the frequency shift of the measuring instrument and the temperature.

8 is BOTDR, which is one configuration of the distortion measuring device in FIG.
FIG. 6 is a correlation diagram between the temperature of the measuring instrument and the apparent strain.

FIG. 9 shows the distance and the first and second distances in the distortion measuring device of FIG. 6;
FIG. 6 is a characteristic diagram showing a relationship between the temperature of the fiber and the temperature for correction.

FIG. 10 is an explanatory diagram of a strain measurement device according to a fifth embodiment of the present invention.

FIG. 11 is a characteristic diagram showing an intensity distribution of Brillouin scattered light.

FIG. 12 is a characteristic diagram showing a relationship between a frequency and a light receiving level when a frequency of a portion lower than a maximum value by a specific level is obtained from a light distribution.

FIG. 13 is a diagram showing the relationship between the frequency band width of the Brillouin scattered light and the level of the Brillouin scattered light obtained in advance, and the frequency and the light receiving level in the case where it is determined how far a specific level lowered portion is from the center frequency. FIG. 3 is a characteristic diagram showing a relationship with the graph.

FIG. 14 is a characteristic diagram showing a relationship between frequency shift and optical fiber distortion.

FIG. 15 is a characteristic diagram showing a relationship between a position on an optical fiber and distortion.

FIG. 16 is a distribution diagram of a strain range obtained by the BOTDR of the strain measurement device according to the sixth embodiment.

FIG. 17 is a characteristic diagram showing estimation of a dynamic strain distribution by combining the strain measuring apparatus according to the sixth embodiment with an FBG measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... FBG measuring device, 2 ... Optical fiber, 3 ... Optical fiber distortion / loss measuring device (BOTDR), 6, 7 ... FBG, 8, 9 ... Filter, 11 ... Optical coupler, 12 ... Wavelength branching filter, 13 ... Temperature Distribution measuring instrument.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01P 15/03 G01P 15/03 C // G01J 5/08 G01J 5/08 A (72) Inventor Hironori Ki Nagasaki Research Institute, Nagasaki City, Nagasaki Prefecture 5-717-1, Nagasaki Research Institute, Mitsubishi Heavy Industries, Ltd. Reference) 2F056 VF02 VF11 VF16 2F065 AA65 BB05 DD00 FF00 FF48 FF58 LL02 LL22 PP22 QQ29 QQ42 UU02 2F076 BB09 BB11 BD06 2G066 AC20 BA18 BA23 CA01 2G086 DD04

Claims (7)

[Claims] An optical fiber is attached to an object and used for evaluating a distortion of the object.
A BG measuring device, an optical fiber strain / loss measuring device connected to the FBG measuring device via an optical fiber to be measured,
A distortion evaluation device comprising: the FBG measuring device; and a filter for a wavelength band used by each measuring device, provided at each connection portion between the strain / loss measuring device and the optical fiber. 2. The distortion evaluation device according to claim 1, wherein the FBG measuring device and the distortion / loss measuring device are connected via an optical coupler and an optical fiber. 3. A distortion evaluation apparatus which is used by attaching an optical fiber to an object and evaluates distortion of the object.
A BG measuring device, an optical fiber strain / loss measuring device connected to the FBG measuring device via an optical fiber to be measured,
A distortion evaluation device comprising: the FBG measuring device; a wavelength branching filter connected to the distortion / loss measuring device via an optical fiber. 4. A distortion evaluation apparatus which is used by attaching an optical fiber to an object and evaluates distortion of the object.
A BG measuring device, a temperature distribution measuring device connected to the FBG measuring device via an optical fiber to be measured, and the FBG measuring device, provided at each connection portion between the temperature distribution measuring device and the optical fiber, A distortion evaluation device comprising: an FBG measuring device; and a filter in a wavelength band used by the temperature distribution measuring device. 5. A distortion evaluation apparatus which is used by attaching an optical fiber to an object and evaluates distortion of the object.
A BG measuring device, a temperature distribution measuring device connected to the FBG measuring device via an optical fiber to be measured, the FBG measuring device, and a wavelength branching filter connected via the temperature distribution measuring device. A distortion evaluation device characterized by the above-mentioned. 6. The apparatus according to claim 1, wherein the FBG measuring device has an acceleration sensor function or a vibration sensor function.
5. The distortion evaluation device according to any one of 5. 7. The optical fiber strain / loss measuring device calculates a maximum value of a frequency shift from a measured intensity distribution of scattered light,
Using the minimum value and the intermediate value to determine the maximum value, the minimum value, and the intermediate value of the fluctuation distortion in the optical fiber, and measuring the frequency of the distortion by the FBG measuring instrument based on these values. The strain measuring device according to claim 1, wherein: