JP2018146371A - Temperature-strain sensing device and temperature-strain sensing method - Google Patents

Abstract

An apparatus and a method for detecting temperature change and strain of a sensor medium are provided.
Using a spatially multiplexed optical fiber having a plurality of spatial channels as a sensor medium, optical frequency spectrum of backward Rayleigh scattered light (hereinafter referred to as “optical frequency spectrum of backward Rayleigh scattered light” and “scattering spectrum”) using test light. Light reflection measuring means for measuring a plurality of spatial channels, a scattering spectrum shift is calculated for the plurality of spatial channels from the measured scattering spectrum, and any two of the plurality of spatial channels with respect to the center optical frequency of the test light are calculated. By utilizing the fact that the ratio of the scattering spectrum shift of each of the two spatial channels is expressed by the temperature change of the spatial multiplexing optical fiber and the strain of the spatial multiplexing optical fiber, the temperature change of the spatial multiplexing optical fiber and the spatial multiplexing optical fiber A temperature / strain sensing device, comprising: .
[Selection] Figure 3

Description

  The present disclosure relates to a temperature / strain sensing device and a temperature / strain sensing method for detecting temperature / strain of an optical fiber.

The optical fiber is useful as a sensor medium because of its characteristics such as non-induction, corrosion resistance, small diameter, and light weight. As a highly sensitive sensing technique using an optical fiber, there is a method using a scattering spectrum shift of backward Rayleigh scattered light shown in Non-Patent Document 1. In this method, the optical frequency spectrum of the backward Rayleigh scattered light at an arbitrary distance point of the optical fiber using the light reflection measurement (hereinafter, the “optical frequency spectrum of the backward Rayleigh scattered light” may be referred to as “scattering spectrum”). ) And the phenomenon that the scattering spectrum shifts with respect to the temperature change and strain of the optical fiber. Hereinafter, the “scattering spectrum shift” is referred to as “scattering spectrum shift”. The scattering spectrum shift Δν has the following relationship with respect to the temperature change ΔT and strain ε.

Here, ν ₀ is the optical center frequency of the test light in the light reflection measurement, and K _T and K _ε are the scattering spectrum shift proportional constants with respect to temperature change and strain, respectively. Δν is measured using an optical fiber having a known _KT or K _ε, and the temperature change and strain can be obtained from the relationship of Equation (1).

D. K. Gifford et al., “Swept-wavelength interferometric interrogation of fibre Rayleigh scatter scatter ic p 67 p Proc. P Pro 70. H.B. Liu et al., “Strain and temperature sensor using a combination of polymers and silica fiber Bragg gratings,” Opt. Commun. 219, 139-142 (2003). Y. Koyamada et al., “Fiber-optic distributed strain and temperature sensing sensation with high high measurement over long range usage.

  As is clear from Equation (1), since the scattering spectrum shift Δν is affected by both the temperature change and strain of the optical fiber, the influence of both cannot be measured separately. In many scenes, both temperature and strain are constantly changing. Therefore, in order to measure accurately, it is necessary to correct the measurement result in combination with other sensing means. As a result, the configuration becomes complicated and the cost is high, which is not always easy. In addition, there is a method of combining a plurality of optical fibers having different characteristics as in Non-Patent Document 2, but since the temperature change and strain generated in each optical fiber are strictly different, sensing accuracy is lacking.

  The present disclosure uses a spatially multiplexed optical fiber as a sensor medium to detect the change in temperature and strain of the sensor medium by using the shift of the optical frequency spectrum of backward Rayleigh scattered light, that is, using the scattered spectrum shift. With the goal.

  In order to achieve the above object, a spatially multiplexed optical fiber is used as a sensor medium, a scattering spectrum is measured for a plurality of spatial channels of the spatially multiplexed optical fiber, and a difference in scattering spectrum shift for each spatial channel is used.

  In the case of a spatially multiplexed optical fiber, there are a plurality of spatial channels, and since these spatial channels are in the same optical fiber, it may be considered that the temperature change is the same and the distortion is also the same. As the spatially multiplexed optical fiber, a multimode optical fiber in which a plurality of modes propagate in a common core or a multicore optical fiber having a plurality of cores in one optical fiber can be applied. In multimode optical fiber, different modes can be used as different spatial channels, and in multicore optical fiber, different cores can be used as different spatial channels.

In the scattering spectrum shift shown in Equation (1), the scattering spectrum shift proportional constant K _{T with} respect to temperature change and the scattering spectrum shift proportional constant K _{ε with} respect to strain are expressed as the effective refractive index n of the core of the spatially multiplexed optical fiber as the sensor medium On the other hand, it has the following relationship.

Here, α is a constant indicating the influence of physical expansion and contraction due to temperature change, T is temperature, p _ij is a photoelastic tensor, and σ is Poisson's ratio. Since the multimode optical fiber has a plurality of propagation modes having different effective refractive indexes in the same core, the scattering spectrum of each mode varies depending on the temperature change and strain from the formulas (1) to (3). Indicates. As an example, FIG. 1 shows the relationship between the ratio (Δν / ν ₀ ) of the scattering spectrum shift to the center optical frequency of the test light and the temperature change (ΔT), and the ratio of the scattering spectrum shift to the center optical frequency of the test light (Δν / The relationship between (ν ₀ ) and strain (ε) is shown in FIG. 1 and 2, the mode scattering spectral shift proportional constant K _T to temperature _changes, scattering spectral shift proportional constant K _epsilon against distortion represent different.

  When a multi-core optical fiber is used, the optical fiber to be used has cores having different effective refractive indexes, and the scattering spectrum is measured for a plurality of cores having different effective refractive indexes.

When the scattering spectrum shifts of the spatial channel 1 and the spatial channel 2 are Δν ₁ and Δν ₂ , respectively, the ratio of Δν ₁ and Δν ₂ to the optical center frequency ν ₀ of the test light has the following relationship with respect to temperature change and strain: is there.

数式（５）によって、空間多重光ファイバの温度変化及び歪を算出することができる。 For the spatial channel 1 and the spatial channel 2, the scattering spectrum shift proportionality constant for each temperature change and the scattering spectral shift proportionality constant _{KT, 1} , _{Kε, 1} , _{KT, 2} , _{Kε, 2} for the strain are known. Using the spatially multiplexed optical fiber, the scattering spectrum shift is measured for the spatial channel 1 and the spatial channel 2, and Equation (4), which is a simultaneous equation, is solved, whereby the temperature change and strain can be obtained individually. The solution of Equation (4) is as follows:

The change in temperature and strain of the spatially multiplexed optical fiber can be calculated by Equation (5).

Specifically, the temperature / strain sensing device of the present disclosure is:
Using a spatially multiplexed optical fiber having a plurality of spatial channels as a sensor medium, an optical frequency spectrum of backward Rayleigh scattered light (hereinafter referred to as “optical frequency spectrum of backward Rayleigh scattered light” or “scattering spectrum”) using test light. Light reflection measuring means for measuring the plurality of spatial channels;
A scattering spectrum shift is calculated for a plurality of spatial channels from the measured scattering spectrum, and a ratio of a scattering spectrum shift of any two spatial channels of the plurality of spatial channels to a center optical frequency of the test light is calculated as follows. A calculation means for obtaining a temperature change of the spatially multiplexed optical fiber and a distortion of the spatially multiplexed optical fiber by utilizing the temperature change of the spatially multiplexed optical fiber and the strain represented by the distortion of the spatially multiplexed optical fiber,
Is provided.

  With the temperature / strain sensing device of the present disclosure, it is possible to detect a temperature change and strain of a sensor medium using a spatially multiplexed optical fiber as a sensor medium and using a scattering spectrum shift.

In the temperature / strain sensing device of the present disclosure,
The computing means is
The center optical frequency of the test light is ν ₀ ,
The scattering spectrum shifts of any two spatial channels among the plurality of spatial channels are denoted by Δν ₁ and Δν ₂ , respectively.
The scattering spectral shift proportional constants with respect to temperature changes of the two spatial channels are denoted as K _{T, 1} and K _{T, 2} respectively.
The scattering spectral shift proportional constants for the distortions of the two spatial channels are K _{ε, 1} , K _{ε, 2} respectively.
The temperature change ΔT or strain ε may be obtained using the following equation.

In the temperature / strain sensing device of the present disclosure,
The light reflection measuring means includes
A frequency swept light source that emits continuous light that is frequency swept linearly with respect to time;
A selective excitation separation circuit that makes continuous light emitted from the frequency swept light source incident on a desired spatial channel of the spatially multiplexed optical fiber and separates backward Rayleigh scattered light from the same spatial channel on which the optical fiber to be measured is incident;
An optical multiplexer for combining the backward Rayleigh scattered light from the selective excitation separation circuit and the continuous light from the frequency swept light source;
A light receiver that converts a beat component obtained by multiplexing with the optical multiplexer into a beat signal of an electrical signal;
After the beat signal converted into the electrical signal is A / D converted into a digital signal, the A / D converted beat signal is Fourier transformed to obtain the scattered light amplitude distribution with respect to the distance in the longitudinal direction of the spatially multiplexed optical fiber. A scattered spectrum measuring circuit that calculates and multiplies a rectangular window centered on a desired distance point to extract an arbitrary interval component, and then inverse Fourier transforms the scattered light amplitude distribution of the arbitrary interval component to measure the scattered spectrum When,
May be provided.

  Even if the optical frequency domain reflection measurement method is used, the temperature change and strain of the sensor medium can be detected by using the spatially multiplexed optical fiber as the sensor medium and the scattering spectrum shift.

In the temperature / strain sensing device of the present disclosure,
The light reflection measuring means includes
A pulsed light output unit that emits pulsed test light by changing the center optical frequency;
Selective excitation separation circuit for entering test light emitted from the pulsed light output unit into a desired spatial channel of the spatially multiplexed optical fiber and separating backward Rayleigh scattered light from the same spatial channel on which the spatially multiplexed optical fiber is incident When,
A receiver that converts back Rayleigh scattered light from the selective excitation separation circuit into an electrical signal;
After the A / D conversion of the electrical signal to a digital signal, the A / D conversion is performed by changing the center optical frequency of the pulsed test light using the A / D converted back Rayleigh scattered light signal. A scattering spectrum measuring circuit for measuring the intensity change of the back Rayleigh scattered light signal as a scattering spectrum;
May be provided.

  Even when the optical time domain reflection measurement method is used, the temperature change and strain of the sensor medium can be detected by using the spatially multiplexed optical fiber as the sensor medium and the scattering spectrum shift.

Specifically, the temperature / strain sensing method of the present disclosure is:
Using a spatially multiplexed optical fiber having a plurality of spatial channels as a sensor medium, an optical frequency spectrum of backward Rayleigh scattered light (hereinafter referred to as “optical frequency spectrum of backward Rayleigh scattered light” or “scattering spectrum”) using test light. A first optical frequency spectrum measurement procedure for measuring in advance for the plurality of spatial channels;
A second optical frequency spectrum measurement procedure for measuring again the scattering spectrum for the plurality of spatial channels using test light with respect to the spatially multiplexed optical fiber having the plurality of spatial channels when performing temperature / strain sensing;
A scattering spectrum shift calculation procedure for calculating a scattering spectrum shift of the scattering spectrum measured in the second optical frequency spectrum measurement procedure with respect to the scattering spectrum measured in the first optical frequency spectrum measurement procedure for a plurality of spatial channels;
A ratio of each of the scattering spectrum shifts of any two spatial channels among the plurality of spatial channels with respect to the center optical frequency of the test light is expressed by a temperature change of the spatially multiplexed optical fiber and a distortion of the spatially multiplexed optical fiber. A temperature / strain calculation procedure for determining the temperature change of the spatially multiplexed optical fiber and the strain of the spatially multiplexed optical fiber,
Is provided.

  Using a spatially multiplexed optical fiber as a sensor medium, a change in temperature and strain of the sensor medium can be detected using a scattering spectrum shift.

In the temperature / strain sensing method of the present disclosure,
The temperature / strain calculation procedure is as follows:
The center optical frequency of the test light is ν ₀ ,
The scattering spectrum shifts of any two spatial channels among the plurality of spatial channels are denoted by Δν ₁ and Δν ₂ , respectively.
The scattering spectral shift proportional constants with respect to temperature changes of the two spatial channels are denoted as K _{T, 1} and K _{T, 2} respectively.
The scattering spectral shift proportional constants for the distortions of the two spatial channels are K _{ε, 1} , K _{ε, 2} respectively.
You may obtain | require temperature change (DELTA) T or distortion (epsilon) using following Formula.

In the temperature / strain sensing method of the present disclosure,
In the first optical frequency spectrum measurement procedure or the second optical frequency spectrum measurement procedure,
Emits continuous light linearly swept in frequency with respect to time,
The continuous light is incident on a desired spatial channel of the spatially multiplexed optical fiber, and rear Rayleigh scattered light is separated from the same spatial channel on which the spatially multiplexed optical fiber is incident;
Combining the back Rayleigh scattered light and the continuous light;
The beat component obtained by combining is converted into the beat signal of the electric signal,
After the beat signal is A / D converted into a digital signal, the A / D converted beat signal is Fourier transformed to calculate the scattered light amplitude distribution with respect to the longitudinal distance of the spatially multiplexed optical fiber, and a desired distance After extracting the arbitrary interval component by multiplying the rectangular window centered on the point, the scattered light amplitude distribution of the arbitrary interval component is calculated by inverse Fourier transform,
In the scattering spectrum shift calculation procedure, the scattering spectrum shift is calculated in a plurality of spaces from the cross-correlation of the scattering spectrum measured in the first optical frequency spectrum measurement procedure and the scattering spectrum measured in the second optical frequency spectrum measurement procedure. You may calculate about a channel.

  Even if the optical frequency domain reflection measurement method is used, the temperature change and strain of the sensor medium can be detected by using the spatially multiplexed optical fiber as the sensor medium and the scattering spectrum shift.

In the temperature / strain sensing method of the present disclosure,
In the first optical frequency spectrum measurement procedure or the second optical frequency spectrum measurement procedure,
Change the center optical frequency to emit pulsed test light,
The test light is incident on a desired spatial channel of the spatially multiplexed optical fiber as a sensor medium, and rear Rayleigh scattered light is separated from the same spatial channel on which the spatially multiplexed optical fiber is incident;
Converting the back Rayleigh scattered light into an electrical signal;
After the A / D conversion of the electrical signal into a digital signal, the A / D converted rear Rayleigh is measured by changing the center optical frequency of the test light using the A / D converted rear Rayleigh scattered light signal. Measure the intensity change of the scattered light signal as a scattering spectrum,
In the spectrum shift calculation procedure, the scattering spectrum shift is calculated in a plurality of spaces from the cross-correlation between the optical frequency spectrum measured in the first optical frequency spectrum measurement procedure and the scattering spectrum measured in the second optical frequency spectrum measurement procedure. You may calculate about a channel.

  Even when the optical time domain reflection measurement method is used, the temperature change and strain of the sensor medium can be detected by using the spatially multiplexed optical fiber as the sensor medium and the scattering spectrum shift.

  The above disclosures can be combined as much as possible.

  According to the present disclosure, it is possible to detect a temperature change and strain of a sensor medium by using a spatially multiplexed optical fiber as a sensor medium and using a scattering spectrum shift.

It is an example of the temperature change dependence of the scattering spectrum shift of mode 1 and mode 2 measured by this invention. It is an example of the strain dependence of the scattering spectrum shift of the mode 1 and mode 2 which are measured by this invention. It is a flowchart which shows the flow of the measurement in embodiment of this invention. It is a block diagram which shows an example of an apparatus structure at the time of using the optical frequency domain reflection measuring method in embodiment of this invention. It is a block diagram which shows an example of an apparatus structure at the time of using the optical time domain reflection measuring method in embodiment of this invention.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, this indication is not limited to embodiment shown below. These embodiments are merely examples, and the present disclosure can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

  Hereinafter, the present embodiment will be described with reference to the drawings. Here, as an example, a case where an optical frequency domain reflectometry (OFDR) is used for measurement of the scattering spectrum will be described.

  FIG. 3 is a flowchart showing a flow of temperature / strain detection in the present embodiment. These procedures measure the scattering spectrum for spatial channel 1 and spatial channel 2 using the apparatus shown in FIG. The spatial channel 1 and the spatial channel 2 have different modes when a multimode optical fiber is used as the optical fiber to be measured, and have different cores when a multicore optical fiber is used as the optical fiber to be measured. In FIG. 4, the optical fiber other than the optical fiber to be measured is composed of a single core single mode optical fiber.

  The frequency sweep light source 401 uses a light source having a frequency sweep function, and emits continuous light linearly swept in frequency with respect to time. The optical demultiplexer 402 splits the emitted continuous light into two, one used as test light incident on the fiber to be measured, and the other used as local light for coherent detection of backward Rayleigh scattered light. The test light is incident on the selective excitation separation circuit 404 through the circulator 403. The selective excitation separation circuit 404 enters the test light into a desired spatial channel of the measured optical fiber 405 as a sensor medium, and the backward Rayleigh scattered light generated by the test light from the same spatial channel on which the measured optical fiber 405 is incident. Isolate. Back Rayleigh scattered light passes through the circulator 403 and enters the optical multiplexer 406. The optical multiplexer 406 combines the backward Rayleigh scattered light and the local light. The light receiver 407 converts a beat component obtained by multiplexing into a beat signal of an electric signal. The A / D converter 411 converts the beat signal into a digital signal. The arithmetic processing unit 412 calculates a scattering spectrum at a desired distance point of the measured fiber using the beat signal converted into the digital signal. The data storage unit 413 stores the calculated scattering spectrum data. The A / D converter 411, the arithmetic processing unit 412 and the data storage unit 413 constitute a scattering spectrum measurement circuit 410.

  The first optical frequency spectrum measurement procedure 301 in the optical frequency domain reflection measurement method will be described. The scattering spectrum is calculated by the method described in Non-Patent Document 1. Specifically, the beat signal is first Fourier-transformed to calculate the scattered light amplitude distribution with respect to the distance in the longitudinal direction of the optical fiber to be measured, and an arbitrary interval component is extracted by multiplying a rectangular window centered at the desired distance point. After that, inverse Fourier transform is performed on the scattered light amplitude distribution of the arbitrary interval component. The scattering spectrum is measured in advance for the spatial channel 1 and the spatial channel 2 by the above method and stored in the data storage unit 413.

  In the second optical frequency spectrum measurement procedure 302 in the optical frequency domain reflection measurement method, the scattering spectrum measurement is performed again for the spatial channel 1 and the spatial channel 2 at the time of sensing, and stored in the data storage unit 413.

In the scattering spectrum shift calculation procedure 303, the cross correlations between the spatial channels 1 and 2 are calculated for the scattering spectra measured in the first optical frequency spectrum measurement procedure 301 and the second optical frequency spectrum measurement procedure 302, respectively. Scatter spectral shifts Δν ₁ and Δν ₂ are obtained. The cross-correlation R _m (ν ′) of the spatial channel m is calculated by the following equation.

Here, σ _{r, m} (ν) and σ _{s, m} (ν) are the scattering spectrum of mode m measured in the first optical frequency spectrum measurement procedure 301 and the second optical frequency spectrum measurement procedure 302, respectively. * Represents a complex conjugate. σ _{r, m} (ν) and σ _{s, m} (ν) have the following relationship.

From Equation (6) and Equation (7), R _m (ν ′) takes the maximum value at ν ′ = Δν _m . Therefore, R ₁ (ν ′) and R ₂ (ν ′) are calculated, and Δν ₁ and Δν ₂ are obtained from the values of ν ′ that take the maximum values.

Finally, in the temperature / strain calculation procedure 304, the temperature change of the optical fiber to be measured as the sensor medium is calculated by calculating Equation (5) using Δν ₁ and Δν ₂ obtained in the scattering spectrum shift calculation procedure 303. And distortion is required.

  The calculations in the scattering spectrum shift calculation procedure 303 and the temperature / strain calculation procedure 304 may be executed by the calculation processing device 412 and the data storage unit 413 of the light reflection measurement means, or separately provided with calculation means for executing these calculations. May be.

  Next, as another example, a case where an optical time domain reflectometry (OTDR) is used for measurement of the scattering spectrum will be described.

  The flowchart showing the flow of temperature / strain detection in the present embodiment is the same as FIG. These procedures measure the scattering spectrum for spatial channel 1 and spatial channel 2 using the apparatus shown in FIG. The spatial channel 1 and the spatial channel 2 have different modes when a multimode optical fiber is used as the optical fiber to be measured, and have different cores when a multicore optical fiber is used as the optical fiber to be measured. In FIG. 5, it is assumed that the optical fiber other than the optical fiber to be measured is composed of a single core single mode optical fiber.

  The pulse light source 501 uses a light source having a pulse emission function, and emits pulsed light at a constant frequency during the pulse emission period. The optical frequency changing unit 502 changes the center optical frequency of the pulsed light from the pulsed light source 501 to a desired value and emits it as test light. The pulsed light source 501 and the optical frequency changing unit 502 constitute a pulsed light output unit. The configuration may be such that only the pulse light source changes the center optical frequency of the pulsed test light to be emitted. The test light is incident on the selective excitation separation circuit 504 through the circulator 503. The selective excitation separation circuit 504 makes the test light incident on a desired spatial channel of the optical fiber 505 to be measured as a sensor medium, and the backward Rayleigh scattering caused by the test light from the same spatial channel on which the optical fiber 505 is incident. Separate the light. Back Rayleigh scattered light passes through the circulator 503 and enters the light receiver 507. The light receiver 507 converts the backward Rayleigh scattered light into an electrical signal. The A / D converter 511 converts the electrical signal of the backward Rayleigh scattered light into a digital signal. The arithmetic processing unit 512 measures the scattering spectrum at a desired distance point of the optical fiber to be measured, using the backward Rayleigh scattered light signal converted into the digital signal. The data storage unit 513 stores the calculated scattering spectrum data. The A / D converter 511, the arithmetic processing unit 512, and the data storage unit 513 constitute a scattering spectrum measurement circuit 510.

  The first optical frequency spectrum measurement procedure 301 in the optical time domain reflection measurement method will be described. The scattering spectrum is calculated by the method described in Non-Patent Document 2. Specifically, by changing the center optical frequency of the pulsed test light, the scattered light intensity distribution with respect to the distance in the longitudinal direction of the optical fiber to be measured is measured for a plurality of center optical frequencies, and the scattered light intensity light at the desired position is measured. The change with respect to the frequency is taken as the scattering spectrum. The measurement at each center optical frequency may be measured a plurality of times at the same optical frequency in order to improve the signal-to-noise ratio of the scattered light intensity, and this may be averaged. The scattering spectrum is measured in advance for the spatial channel 1 and the spatial channel 2 by the above method and stored in the data storage unit 513.

  In the second optical frequency spectrum measurement procedure 302 in the optical time domain reflection measurement method, the scattering spectrum measurement is performed again for the spatial channel 1 and the spatial channel 2 at the time of sensing, and stored in the data storage unit 513.

  Also in the optical time domain reflection measurement method, the temperature change and strain of the spatially multiplexed optical fiber as the sensor medium are obtained by performing the scattering spectrum shift calculation procedure 303 and the temperature / strain calculation procedure 304.

  The calculations in the scattering spectrum shift calculation procedure 303 and the temperature / strain calculation procedure 304 may be executed by the calculation processing device 512 and the data storage unit 513 of the light reflection measurement means, or separately provided with calculation means for executing these calculations. May be.

  Regardless of the measurement method of optical frequency domain reflectometry or optical time domain reflectometry, a spatially multiplexed optical fiber is used as a sensor medium, and the spectral change of the sensor medium is detected using a scattering spectrum shift. be able to.

  The present disclosure can be applied to the information communication industry.

301: First optical frequency spectrum measurement procedure 302: Second optical frequency spectrum measurement procedure 303: Scattering spectrum shift calculation procedure 304: Temperature / strain calculation procedure 401: Frequency sweep light source 402: Optical demultiplexer 403: Circulator 404: Selective excitation separation circuit 405: optical fiber to be measured 406 as sensor medium: optical multiplexer 407: light receiver 410: scattering spectrum measurement circuit 411: A / D converter 412: arithmetic processing unit 413: data storage unit 501: pulse Light source 502: Optical frequency changing unit 503: Circulator 504: Selective excitation separation circuit 505: Optical fiber to be measured 507: Light receiver 510: Scattering spectrum measurement circuit 511: A / D converter 512: Arithmetic processing unit 513 : Data storage

Claims (8)

Using a spatially multiplexed optical fiber having a plurality of spatial channels as a sensor medium, an optical frequency spectrum of backward Rayleigh scattered light (hereinafter referred to as “optical frequency spectrum of backward Rayleigh scattered light” or “scattering spectrum”) using test light. Light reflection measuring means for measuring the plurality of spatial channels;
A scattering spectrum shift is calculated for a plurality of spatial channels from the measured scattering spectrum, and a ratio of a scattering spectrum shift of any two spatial channels of the plurality of spatial channels to a center optical frequency of the test light is calculated as follows. A calculation means for obtaining a temperature change of the spatially multiplexed optical fiber and a distortion of the spatially multiplexed optical fiber by utilizing the temperature change of the spatially multiplexed optical fiber and the strain represented by the distortion of the spatially multiplexed optical fiber,
A temperature / strain sensing device comprising: The computing means is
The center optical frequency of the test light is ν ₀ ,
The scattering spectrum shifts of any two spatial channels among the plurality of spatial channels are denoted by Δν ₁ and Δν ₂ , respectively.
The scattering spectral shift proportional constants with respect to temperature changes of the two spatial channels are denoted as K _{T, 1} and K _{T, 2} respectively.
The scattering spectral shift proportional constants for the distortions of the two spatial channels are K _{ε, 1} , K _{ε, 2} respectively.
The temperature / strain sensing device according to claim 1, wherein the temperature change ΔT or the strain ε is obtained using the following equation.

The light reflection measuring means includes
A frequency swept light source that emits continuous light that is frequency swept linearly with respect to time;
A selective excitation separation circuit that makes continuous light emitted from the frequency swept light source incident on a desired spatial channel of the spatially multiplexed optical fiber and separates backward Rayleigh scattered light from the same spatial channel on which the optical fiber to be measured is incident;
An optical multiplexer for combining the backward Rayleigh scattered light from the selective excitation separation circuit and the continuous light from the frequency swept light source;
A light receiver that converts a beat component obtained by multiplexing with the optical multiplexer into a beat signal of an electrical signal;
After the beat signal converted into the electrical signal is A / D converted into a digital signal, the A / D converted beat signal is Fourier transformed to obtain the scattered light amplitude distribution with respect to the distance in the longitudinal direction of the spatially multiplexed optical fiber. A scattered spectrum measuring circuit that calculates and multiplies a rectangular window centered on a desired distance point to extract an arbitrary interval component, and then inverse Fourier transforms the scattered light amplitude distribution of the arbitrary interval component to measure the scattered spectrum When,
The temperature / strain sensing device according to claim 1, further comprising: The light reflection measuring means includes
A pulsed light output unit that emits pulsed test light by changing the center optical frequency;
Selective excitation separation circuit for entering test light emitted from the pulsed light output unit into a desired spatial channel of the spatially multiplexed optical fiber and separating backward Rayleigh scattered light from the same spatial channel on which the spatially multiplexed optical fiber is incident When,
A receiver that converts back Rayleigh scattered light from the selective excitation separation circuit into an electrical signal;
After the A / D conversion of the electrical signal to a digital signal, the A / D conversion is performed by changing the center optical frequency of the pulsed test light using the A / D converted back Rayleigh scattered light signal. A scattering spectrum measuring circuit for measuring the intensity change of the back Rayleigh scattered light signal as a scattering spectrum;
The temperature / strain sensing device according to claim 1, further comprising: Using a spatially multiplexed optical fiber having a plurality of spatial channels as a sensor medium, an optical frequency spectrum of backward Rayleigh scattered light (hereinafter referred to as “optical frequency spectrum of backward Rayleigh scattered light” or “scattering spectrum”) using test light. A first optical frequency spectrum measurement procedure for measuring in advance for the plurality of spatial channels;
A second optical frequency spectrum measurement procedure for measuring again the scattering spectrum for the plurality of spatial channels using test light with respect to the spatially multiplexed optical fiber having the plurality of spatial channels when performing temperature / strain sensing;
A scattering spectrum shift calculation procedure for calculating a scattering spectrum shift of the scattering spectrum measured in the second optical frequency spectrum measurement procedure with respect to the scattering spectrum measured in the first optical frequency spectrum measurement procedure for a plurality of spatial channels;
A ratio of each of the scattering spectrum shifts of any two spatial channels among the plurality of spatial channels with respect to the center optical frequency of the test light is expressed by a temperature change of the spatially multiplexed optical fiber and a distortion of the spatially multiplexed optical fiber. A temperature / strain calculation procedure for determining the temperature change of the spatially multiplexed optical fiber and the strain of the spatially multiplexed optical fiber,
A temperature / strain sensing method comprising: The temperature / strain calculation procedure is as follows:
The center optical frequency of the test light is ν ₀ ,
The scattering spectrum shifts of any two spatial channels among the plurality of spatial channels are denoted by Δν ₁ and Δν ₂ , respectively.
The scattering spectral shift proportional constants with respect to temperature changes of the two spatial channels are denoted as K _{T, 1} and K _{T, 2} respectively.
The scattering spectral shift proportional constants for the distortions of the two spatial channels are K _{ε, 1} , K _{ε, 2} respectively.
6. The temperature / strain sensing method according to claim 5, wherein a temperature change ΔT or strain ε is obtained using the following equation.

In the first optical frequency spectrum measurement procedure or the second optical frequency spectrum measurement procedure,
Emits continuous light linearly swept in frequency with respect to time,
The continuous light is incident on a desired spatial channel of the spatially multiplexed optical fiber, and rear Rayleigh scattered light is separated from the same spatial channel on which the spatially multiplexed optical fiber is incident;
Combining the back Rayleigh scattered light and the continuous light;
The beat component obtained by combining is converted into the beat signal of the electric signal,
After the beat signal is A / D converted into a digital signal, the A / D converted beat signal is Fourier transformed to calculate the scattered light amplitude distribution with respect to the longitudinal distance of the spatially multiplexed optical fiber, and a desired distance After extracting the arbitrary interval component by multiplying the rectangular window centered on the point, the scattered light amplitude distribution of the arbitrary interval component is calculated by inverse Fourier transform,
In the scattering spectrum shift calculation procedure, the scattering spectrum shift is calculated in a plurality of spaces from the cross-correlation of the scattering spectrum measured in the first optical frequency spectrum measurement procedure and the scattering spectrum measured in the second optical frequency spectrum measurement procedure. Calculating for the channel,
The temperature / strain sensing method according to claim 5 or 6. In the first optical frequency spectrum measurement procedure or the second optical frequency spectrum measurement procedure,
Change the center optical frequency to emit pulsed test light,
The test light is incident on a desired spatial channel of the spatially multiplexed optical fiber as a sensor medium, and rear Rayleigh scattered light is separated from the same spatial channel on which the spatially multiplexed optical fiber is incident;
Converting the back Rayleigh scattered light into an electrical signal;
After the A / D conversion of the electrical signal into a digital signal, the A / D converted rear Rayleigh is measured by changing the center optical frequency of the test light using the A / D converted rear Rayleigh scattered light signal. Measure the intensity change of the scattered light signal as a scattering spectrum,
In the spectrum shift calculation procedure, the scattering spectrum shift is calculated in a plurality of spaces from the cross-correlation between the optical frequency spectrum measured in the first optical frequency spectrum measurement procedure and the scattering spectrum measured in the second optical frequency spectrum measurement procedure. Calculating for the channel,
The temperature / strain sensing method according to claim 5 or 6.

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