WO2020213466A1

WO2020213466A1 - Physical quantity measurement device

Info

Publication number: WO2020213466A1
Application number: PCT/JP2020/015601
Authority: WO
Inventors: 顕小川; 圭一藤田; 山手　勉
Original assignee: 長野計器株式会社
Priority date: 2019-04-17
Filing date: 2020-04-07
Publication date: 2020-10-22
Also published as: JP2020176884A

Abstract

A physical quantity measurement device (1) that comprises a light source (10) that emits light of a broad band of wavelengths, a light path (20) that receives the light that is emitted from the light source (10), a plurality of optical filters (40) that are provided on the light path (20) and divide the light from the light path (20) into segregated light of respective wavelength ranges, and a plurality of optical sensors (50) that are provided to correspond to the plurality of optical filters (40), receive the segregated light, and output output light that corresponds to a physical quantity for a measured object to the light path (20). The optical filters (40) are arranged from near to far from the light source (10) in order of the magnitude of the transmission loss rate of the segregated light of the wavelength ranges divided thereby.

Description

Physical quantity measuring device

The present invention relates to a physical quantity measuring device.

A physical quantity measuring device using an optical sensor is known (for example, Patent Document 1).

In the physical quantity measuring device of Patent Document 1, a plurality of fabric perot type optical sensors having an optical filter for wavelength-dividing the light in a specific wavelength region are arranged on the optical path where the light emitted from the light source is incident. As a result, physical quantities at a plurality of measurement points on the optical path can be measured.

Further, it is known that the transmission loss rate depends on the wavelength region in the transmission of light using an optical fiber (for example, Patent Document 2).

U.S. Pat. No. 9,689,714 Republished Patent 2013/118389 Gazette

In Patent Document 1, the physical quantity is measured by using light in a wavelength region having a small transmission loss rate, specifically, a wavelength region of about 1460 nm to 1620 nm. Here, when a Fabry-Perot type interference type optical sensor is used as in Patent Document 1, light in a wavelength region of about 15 nm to 20 nm is required to measure a physical quantity, so that the number of measurement points is further increased. There is a problem that it is difficult.
Further, in order to increase the number of measurement points, it is conceivable to widen the wavelength range used for measurement. However, as shown in Patent Document 2, the transmission loss rate of the optical fiber depends on the wavelength region. Therefore, when the wavelength range used for the measurement is expanded, the light in the wavelength region having a large transmission loss rate is used. Become. Therefore, there is a problem that it is difficult to secure the measurement accuracy at the measurement point away from the light source.

An object of the present invention is to provide a physical quantity measuring device capable of increasing the number of measurement points while ensuring measurement accuracy.

The physical quantity measuring device of the present invention is provided in a plurality of light paths that emit light having a wide band wavelength, light paths in which light emitted from the light source is incident, and light paths emitted from the light source, and the light has different wavelengths. An optical filter that divides the wavelength of the separated light in the region from the optical path and a plurality of optical filters are provided according to the plurality of the optical filters, and the separated light is incident and output light corresponding to the physical quantity of the object to be measured is output to the optical path. An optical sensor, a beam splitter provided in the optical path, and a plurality of the output lights output from the plurality of optical sensors are incident and dispersed from the optical path, and a plurality of the output lights output from the beam splitter are combined. The optical filter includes a spectroscopic element that is incident and disperses according to the wavelength region, and a light detection unit that detects a plurality of the output lights dispersed by the spectroscopic element, and the optical filter divides the wavelength into the wavelength region. It is characterized in that they are arranged from near to far from the light source in the order of the magnitude of the transmission loss rate of the separated light.

In the present invention, a plurality of optical filters are provided in the optical path where the light emitted from the light source is incident, and the light is divided into separated light having different wavelength regions. Then, the optical filters are arranged in the order of the magnitude of the transmission loss rate of the separated light in the wavelength region for wavelength division from near to far from the light source. That is, the optical filter for wavelength-dividing the separated light in the wavelength region having a large transmission loss rate is arranged near the light source, and the optical filter for wavelength-dividing the separated light in the wavelength region having a small transmission loss rate is arranged far from the light source. .. As a result, even when the physical quantity is measured using the separated light in the wavelength region having a large transmission loss rate, the optical filter for wavelength-dividing the separated light in the wavelength region having a large transmission loss rate is arranged near the light source. The transmission loss from the beam splitter to the optical sensor can be suppressed. Therefore, it is possible to suppress a decrease in measurement accuracy due to transmission loss from the beam splitter to the optical sensor, and it is possible to use light in a wider wavelength range, so that the number of measurement points can be increased while ensuring measurement accuracy. Can be done.

In the physical quantity measuring device of the present invention, n (n is a natural number) of the optical filters may be provided, and n + 1 of the optical sensors may be provided.
In this configuration, light transmitted through the n + 1th optical sensor without being wavelength-divided by the nth optical filter is incident. Therefore, in the case where the light emitted from the light source is divided into n + 1 separated wavelengths and incident on the optical sensor, the number of optical filters is increased as compared with the case where n + 1 optical filters are provided, for example. Can be reduced.

The physical quantity measuring device of the present invention includes a light source that emits light having a wide band wavelength, an optical path in which light emitted from the light source is incident, and a plurality of light paths provided in the optical path that emit light emitted from the light source. An optical filter that divides the wavelength of the separated light in the wavelength region from the optical path and a plurality of optical filters that are wavelength-divided by the optical filter according to the separated light in a plurality of wavelength regions are provided, and the separated light is incident on the object to be measured. An optical sensor that outputs output light according to a physical quantity to the optical path, a beam splitter provided in the optical path that incidents a plurality of output lights output from the plurality of optical sensors and disperses the output light from the optical path, and the above. The present invention includes a spectroscopic element that incidents a plurality of the output lights output from the beam splitter and disperses them according to the wavelength region, and a light detection unit that detects the plurality of the output lights dispersed by the spectroscopic elements. The optical sensor is characterized in that it is arranged from near to far from the light source in the order of the magnitude of the transmission loss rate of the separated light in the incident wavelength region.

In the present invention, a plurality of optical sensors are provided according to the separated light in a plurality of wavelength regions wavelength-divided by an optical filter, and the separated light is incident to output the output light according to the physical quantity of the object to be measured to the optical path. .. Then, the optical sensors are arranged in the order of the magnitude of the transmission loss rate of the separated light in the incident wavelength region from near to far from the light source. That is, the optical sensor that injects the separated light in the wavelength region having a large transmission loss rate is arranged near the light source, and the optical filter that injects the separated light in the wavelength region having a small transmission loss rate is arranged far from the light source. As a result, even when the physical quantity is measured using the separated light in the wavelength region having a large transmission loss rate, the optical sensor that incidents the separated light in the wavelength region having a large transmission loss rate is arranged near the light source, so that the beam The transmission loss from the splitter to the optical sensor can be suppressed. Therefore, it is possible to suppress a decrease in measurement accuracy due to transmission loss from the beam splitter to the optical sensor, and it is possible to use light in a wider wavelength range, so that the number of measurement points can be increased while ensuring measurement accuracy. Can be done.

In the physical quantity measuring device of the present invention, in the photodetector, a plurality of photodetectors formed of different materials may be arranged in an array.
In this configuration, a plurality of photodetectors formed of different materials are arranged in an array in the photodetector, so that the photodetector can detect a plurality of output lights in different wavelength regions. it can. Therefore, the wavelength range of the output light detected by the photodetector can be easily expanded.

In the physical quantity measuring device of the present invention, the spectroscopic element may have a diffraction grating.
In this configuration, since the spectroscopic element that disperses the plurality of output lights has a diffraction grating, the output lights can be separated into different wavelength regions with a simple configuration.

In the physical quantity measuring device of the present invention, the optical sensor incidents the separated light and outputs a first polarized light corresponding to the physical quantity of the object to be measured and a second polarized light having a phase different from that of the first polarized light. It may have a polarization holding optical fiber sensor unit.
In this configuration, since the optical sensor has a polarization-holding optical fiber sensor unit that outputs first polarized light and second polarized light according to the physical quantity of the object to be measured, the first polarized light and the second polarized light. Physical quantities can be measured by analyzing the interference light of polarized light. Therefore, physical quantities such as pressure and strain can be measured with high accuracy.

The physical quantity measuring device of the present invention is provided with a light source that emits light having a wide band wavelength, an optical path into which the light emitted from the light source is incident, and a plurality of light paths provided in the optical path to incident the light emitted from the light source. An optical sensor that outputs output light of different wavelengths according to the physical quantity of the object to be measured, and a plurality of output lights provided in the optical path and output from the plurality of optical sensors are incident from the optical path. A beam splitter that disperses, a spectroscopic element that incidents a plurality of the output lights output from the beam splitter and disperses the light according to the wavelength, and a light that detects a plurality of the output lights dispersed by the spectroscopic element. The optical sensor includes a detection unit, and is characterized in that the optical sensor is arranged from near to far from the light source in the order of the magnitude of the transmission loss rate of the output light of the output wavelength.

In the present invention, a plurality of optical sensors are arranged in an optical path where light emitted from a light source is incident, and the light is incident and outputs light having different wavelengths according to the physical quantity of the object to be measured. Then, the optical sensors are arranged from near the light source toward far away in the order of the magnitude of the transmission loss rate of the output light of the output wavelength. That is, the optical sensor that outputs the output light having a wavelength having a large transmission loss rate is arranged near the light source, and the optical sensor that reflects the output light having a wavelength having a small transmission loss rate is arranged far from the light source. As a result, even when the physical quantity is measured using the output light having a wavelength having a large transmission loss rate, the optical sensor that outputs the output light having a wavelength having a large transmission loss rate is arranged near the light source. Transmission loss can be suppressed. Therefore, it is possible to suppress a decrease in measurement accuracy due to transmission loss of output light, and it is possible to use light in a wider wavelength region, so that it is possible to increase the number of measurement points while ensuring measurement accuracy.

The figure which shows the schematic structure of the physical quantity measuring apparatus which concerns on 1st Embodiment of this invention. The figure which shows the transmission loss rate of the optical path of the said embodiment, and the wavelength region of the separated light which is wavelength-divided by an optical filter. The figure which shows the schematic structure of the optical sensor of the said embodiment. The figure which shows the interference light of the said embodiment. The figure which shows the schematic structure of the physical quantity measuring apparatus of 2nd Embodiment. The figure which shows the schematic structure of the physical quantity measuring apparatus of 3rd Embodiment.

[First Embodiment]
The first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of the physical quantity measuring device 1 of the first embodiment.
As shown in FIG. 1, the physical quantity measuring device 1 includes a light source 10, an optical path 20, a beam splitter 30, an optical filter 40, an optical sensor 50, and a receiver 60.

[Light source 10]
The light source 10 is a light source that emits light having a wide band wavelength. The light source 10 is, for example, an SC (Super Continuum) light source, and is configured to be capable of emitting light in a wavelength region of 1250 nm to 1650 nm. The light source 10 is not limited to the above configuration, and may be a combination of an ASE (Amplified Spontaneous Emission) light source, an SLD (Super luminescent diode) light source, or the like, and has a wide band like a tunable laser. It may be a narrow band light source that sweeps. Further, the light source 10 may be configured to be capable of emitting light in a wavelength region wider than the illustrated wavelength region, or may be configured to be capable of emitting light in a wavelength region narrower than the illustrated wavelength region. Good.

[Optical path 20]
The optical path 20 is composed of a so-called optical fiber, and the light emitted from the light source 10 is incident on the optical path 20. In the present embodiment, the optical path 20 has a first optical path 21, a second optical path 22, and a third optical path 23. The first optical path 21 transmits the light emitted from the light source 10 to the beam splitter 30 and the optical filter 40. The second optical path 22 transmits the separated light separated from the optical filter 40 to the optical sensor 50. The third optical path 23 transmits the output light dispersed by the beam splitter 30 to the receiver 60.

[Beam Splitter 30]
The beam splitter 30 sends the light emitted from the light source 10 to the optical filter 40 and the optical sensor 50, incidents the output light output from the optical sensor 50, and splits it from the first optical path 21 to the third optical path 23. ..
The beam splitter 30 is not limited to the above configuration, and may be composed of, for example, a circulator.

[Optical filter 40]
The optical filter 40 is a WDM (Wavelength Division Multiplexing) filter that incidents the light emitted from the light source 10 and divides the separated light in a predetermined wavelength region into wavelength divisions from the first optical path 21 to the second optical path 22. Consists of.
N optical filters 40 (n is a natural number) are provided in the first optical path 21. In this embodiment, 19 optical filters 40 are provided, that is, a plurality of optical filters 40 are provided. Then, the optical filter 40 divides the light emitted from the light source 10 into separated light having different wavelength regions Δλ1 to Δλ19 at intervals of 20 nm. The optical filter 40 is not limited to the above configuration, and may be composed of, for example, a dichroic mirror that reflects only light in a specific wavelength region. Further, the optical filter 40 may be configured so as to be able to divide the wavelength into separated light having different wavelength regions at intervals of 15 nm, for example, and can be configured to be capable of dividing the wavelength into wavelength regions having a predetermined interval.

FIG. 2 is a diagram showing a transmission loss rate of the optical path 20 and a wavelength region of separated light whose wavelength is divided by the optical filter 40.
The transmission loss rate of the optical path 20 of the present embodiment depends on the wavelength of the light to be transmitted. For example, the transmission loss rate at a wavelength of 1250 nm is about 0.45 dB / km, while the transmission loss rate of light at a wavelength of 1550 nm is about 0.02 dB / km. Further, in the vicinity of the wavelength of 1375 nm, the light transmission loss rate becomes specifically large. That is, the optical path 20 has a large transmission loss rate depending on the wavelength of the light to be transmitted.
Therefore, in the present embodiment, the optical filters 40 are arranged from near to far from the light source 10 in the order of the magnitude of the transmission loss rate of the separated light in the wavelength region for wavelength division. That is, the optical filter 40 for wavelength-dividing the separated light of 1250 nm to 1270 nm, which is the wavelength region of Δλ1 having the largest transmission loss rate shown in FIG. 2, is arranged closest to the light source 10. Then, Δλ2 and Δλ3 and an optical filter 40 for wavelength-dividing the separated light in the wavelength region having a large transmission loss rate are arranged in order, and the optical filter 40 for wavelength-dividing the separated light in the wavelength region of Δλ19 is the farthest from the light source 10. Be placed. Further, the light in the wavelength region of Δλ20, that is, the wavelength region of 1550 nm to 1570 nm passes through all the optical filters 40 and is incident on the optical sensor 50 arranged farthest from the light source 10.

[Optical sensor 50]
Returning to FIG. 1, the optical sensor 50 is arranged on an object to be measured (not shown). N + 1 optical sensors 50 are provided according to the optical filter 40. In this embodiment, 20 optical sensors 50 are provided. Then, the optical sensor 50 incidents the separated light wavelength-divided by the optical filter 40, and transmits the output light according to the physical quantity of the object to be measured, for example, pressure and distortion, through the second optical path 22 and the optical filter 40. Then, it is output to the first optical path 21. That is, the optical sensor 50 is configured to be able to detect the physical quantity of the object to be measured.
An example of the object to be measured is a pipeline laid over several tens of kilometers. Further, the optical sensor 50 is not limited to outputting the output light according to the pressure and strain of the object to be measured, and for example, the optical sensor 50 can output the output light according to the acceleration and temperature of the object to be measured. It may have been. That is, the optical sensor 50 may be configured to be able to detect acceleration and temperature as physical quantities of the object to be measured.

FIG. 3 is a diagram showing a schematic configuration of the optical sensor 50.
As shown in FIG. 3, in the present embodiment, the optical sensor 50 is configured as a so-called polarization-holding optical fiber sensor having a polarization-holding optical fiber sensor unit 51 and a reflector 52.
The polarization-holding optical fiber sensor unit 51 incidents the separated light wavelength-divided by the optical filter 40, and the first-polarized light according to the physical quantity of the object to be measured and the second-polarized light having a phase different from that of the first polarized light. It is composed of a polarization-retaining optical fiber that outputs. In the present embodiment, the separated light wavelength-divided by the optical filter 40 is transmitted through the polarization-holding optical fiber sensor unit 51, and the transmitted light is reflected by the reflecting plate 52. Then, the reflected light passes through the polarization-holding optical fiber sensor unit 51 again, and the interference light between the first polarization light and the second polarization light is output from the optical sensor 50 as output light.

FIG. 4 is a diagram showing spectra of interference light of the first polarized light and the second polarized light output from the optical sensor 50. Note that FIG. 4 illustrates the interference light output from the optical sensor 50 when the separated light in the wavelength region of 1530 nm to 1550 nm, that is, the wavelength region of Δλ18 shown in FIG. 2 is incident.
As shown by the solid line L1 in FIG. 4, in the present embodiment, the mountain region X and the valley region Y are observed in the interference light output from the optical sensor 50. That is, interference fringes are observed. The interference light output from the optical sensor 50 is not limited to that illustrated in FIG. 4, and for example, the interference fringes may be observed more closely, or a part of the interference fringes may be observed. May be done.

[Receiver 60]
Returning to FIG. 1, the receiver 60 incidents interference light as output light output from the optical sensor 50, and calculates a physical quantity corresponding to the interference light. The receiver 60 includes a spectroscope 61, a photodetector 62, and an MPU 63.

[Spectroscope 61]
The spectroscope 61 incidents a plurality of output lights output from the beam splitter 30, that is, interference light output from the optical sensor 50, and disperses the interference light according to a wavelength region from Δλ1 to Δλ20. The spectroscope 61 is an example of the spectroscopic element of the present invention.
In the present embodiment, the spectroscope 61 includes a diffraction grating 611 that disperses the interference light in the wavelength region of Δλ1 to Δλ20.
The spectroscope 61 is not limited to the above configuration, and may be configured to include, for example, WDM or a plurality of diffraction gratings.

[Light detection unit 62]
The photodetector 62 includes a photodetector 621, a photoelectric converter (not shown), an amplifier, an AD converter, and the like, detects a plurality of interference lights dispersed by the spectroscope 61, and converts the interference light into each interference light. Outputs the corresponding interference signal.
Further, in the present embodiment, a plurality of photodetector elements 621 formed of different materials are arranged in an array. For example, in the photodetection unit 62, a plurality of photodetector elements 621 formed of Si and detecting interference light in a wavelength region having a short wavelength are arranged in an array. Further, in the photodetection unit 62, a plurality of photodetector elements 621 formed of InGaAs and detecting interference light in a wavelength region having a long wavelength are arranged in an array.
The photodetector 62 is not limited to the above configuration, as long as it can detect a plurality of interference lights dispersed by the spectroscope 61 and output an interference signal corresponding to each interference light. Good.

The MPU 63 is a so-called Micro Processing Unit, which inputs a plurality of interference signals output from the photodetector 62 and calculates a physical quantity corresponding to each interference signal. In the present embodiment, the MPU 63 measures a physical quantity from an interference signal by a known calculation method. That is, the MPU 63 obtains the interference fringes shown in FIG. 4 from the interference signal. Then, the MPU 63 calculates the phase change from the periodic intensity change of the interference fringes shown by the solid line L1 and the alternate long and short dash line L2 in FIG. The MPU 63 calculates the physical quantity according to the phase change by obtaining the correlation between the phase change and the physical quantity in advance.

[Effect of the first embodiment]
In the first embodiment as described above, the following effects can be obtained.
(1) In the present embodiment, a plurality of optical filters 40 are arranged in the optical path 20 in which the light radiated from the light source 10 is incident, and the light is wavelength-divided into separated light having different wavelength regions. Then, the optical filter 40 is arranged from near to far from the light source 10 in the order of the magnitude of the transmission loss rate of the separated light in the wavelength region for wavelength division. That is, the optical filter 40 for wavelength-dividing the separated light in the wavelength region having a large transmission loss rate, for example, the wavelength region of Δλ1, is arranged near the light source 10. Then, the optical filter 40 for wavelength-dividing the separated light in the wavelength region having a small transmission loss rate, for example, the wavelength region of Δλ19, is arranged far from the light source 10. As a result, the optical filter 40 that divides the separated light in the wavelength region having a large transmission loss rate into wavelengths is arranged near the light source 10 even when the physical quantity is measured by using the separated light in the wavelength region having a large transmission loss rate. Therefore, the transmission loss from the beam splitter 30 to the optical sensor 50 can be suppressed. Therefore, it is possible to suppress a decrease in measurement accuracy due to transmission loss from the beam splitter 30 to the optical sensor 50, and light in a wider wavelength region can be used, so that the measurement point can be set while ensuring measurement accuracy. Can be increased.

(2) In the present embodiment, the light transmitted through the 20th optical sensor 50 without being wavelength-divided by the 19th optical filter 40 is incident. Therefore, in the case where the light emitted from the light source 10 is divided into wavelengths of separated light in 20 wavelength regions and incident on each of the optical sensors 50, the optical filter is compared with the case where 20 optical filters 40 are provided, for example. The number of 40 can be reduced.

(3) In the present embodiment, since a plurality of photodetector elements 621 formed of different materials are arranged in an array in the photodetector 62, interference light as a plurality of output lights in different wavelength regions is emitted. , Each can be detected by the light detection unit 62. Therefore, the wavelength range of the output light detected by the photodetector 62 can be easily expanded.

(4) In the present embodiment, since the spectroscope 61 that divides the wavelengths of the plurality of output lights has a diffraction grating 611, the interference light as the output light is divided into different wavelength regions Δλ1 to Δλ20 with a simple configuration. Can be spectroscopic.

(5) In the present embodiment, the optical sensor 50 has a polarization-holding optical fiber sensor unit 51 that outputs first-polarized light and second-polarized light according to the physical quantity of the object to be measured. The physical quantity can be measured by analyzing the interference light of the first polarized light and the second polarized light. Therefore, physical quantities such as pressure and strain can be measured with high accuracy.

[Second Embodiment]
Next, the second embodiment of the present invention will be described with reference to the drawings.
The second embodiment is different from the first embodiment in that the optical sensor 50A is arranged from near to far from the light source 10A in the order of the magnitude of the transmission loss rate of the separated light in the incident wavelength region.

FIG. 5 is a diagram showing a schematic configuration of the physical quantity measuring device 1A of the second embodiment.
As shown in FIG. 5, the physical quantity measuring device 1A includes a light source 10A, an optical path 20A, a beam splitter 30A, an optical filter 40A, an optical sensor 50A, and a receiver 60A. Further, the receiver 60A includes a spectroscope 61A, a photodetector 62A, and an MPU 63A. The spectroscope 61A has a diffraction grating 611A, and the photodetector 62A has a photodetector 621A.
The light source 10A, the optical path 20A, the beam splitter 30A, the photodetector 60A, the spectroscope 61A, the photodetector 62A, the MPU 63A, the diffraction grating 611A, and the photodetector 621A are the same as those in the first embodiment described above. Explanation is omitted.

[Optical filter 40A]
The optical filter 40A is composed of a WDM filter as in the first embodiment described above, and incidents light emitted from the light source 10A from the first optical path 21A. Then, the light is divided into wavelengths of separated light having a plurality of different wavelength regions, and the light is output to the second optical path 22A.
In the present embodiment, the optical filter 40A divides the light emitted from the light source 10A into separated light having different wavelength regions Δλ1 to Δλ20 at intervals of 20 nm. That is, the optical filter 40A divides the light emitted from the light source 10A into separated light having 20 wavelength regions.

[Optical sensor 50A]
Similar to the first embodiment described above, the optical sensor 50A is configured as a polarization-retaining optical fiber sensor and is arranged on an object to be measured (not shown).
In the present embodiment, 20 optical sensors 50A are provided according to the separated light in a plurality of wavelength regions whose wavelengths are divided by the optical filter 40A. Then, each optical sensor 50A outputs output light corresponding to the physical quantity of the object to be measured to the first optical path 21A via the second optical path 22A and the optical filter 40A. The output light incident on the first optical path 21A is incident on the receiver 60A via the beam splitter 30A and the third optical path 23A.

Here, in the present embodiment, the optical sensors 50A are arranged from near to far from the light source 10A in the order of the magnitude of the transmission loss rate of the separated light in the incident wavelength region. That is, the wavelength region of Δλ1 having the largest transmission loss rate shown in FIG. 2, that is, the optical sensor 50A that incidents the separated light of 1250 nm to 1270 nm is arranged closest to the light source 10A. Then, Δλ2 and Δλ3 and the optical sensor 50A that injects the separated light in the wavelength region having a large transmission loss rate are arranged in order, and the optical sensor 50A that injects the separated light in the wavelength region of Δλ20 is arranged farthest from the light source 10A. Ru.

[Effect of the second embodiment]
In the second embodiment as described above, the following effects can be obtained.
(6) In the present embodiment, a plurality of optical sensors 50A are provided according to the separated light in a plurality of wavelength regions wavelength-divided by the optical filter 40A, and the separated light is incident and output according to the physical quantity of the object to be measured. Light is output to the optical path 20A. Then, the optical sensor 50A is arranged from near to far from the light source 10A in the order of the magnitude of the transmission loss rate of the separated light in the incident wavelength region. As a result, even when the physical quantity is measured using the separated light in the wavelength region having a large transmission loss rate, the optical sensor 50A that incidents the separated light in the wavelength region having a large transmission loss rate is arranged near the light source 10A. , The transmission loss from the beam splitter 30A to the optical sensor 50A can be suppressed. Therefore, as in the first embodiment described above, it is possible to suppress a decrease in measurement accuracy due to transmission loss from the beam splitter 30A to the optical sensor 50A, and it is possible to use light in a wider wavelength region. , The number of measurement points can be increased while ensuring the measurement accuracy.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to the drawings.
In the third embodiment, the optical sensor 50B differs from the first and second embodiments in that it is composed of a so-called FBG (fiber Bragg grating) sensor.

FIG. 6 is a diagram showing a schematic configuration of the physical quantity measuring device 1B of the third embodiment.
As shown in FIG. 6, the physical quantity measuring device 1B includes a light source 10B, an optical path 20B, a beam splitter 30B, an optical sensor 50B, and a receiver 60B. Further, the receiver 60B includes a spectroscope 61B, a photodetector 62B, and an MPU 63B. The spectroscope 61B has a diffraction grating 611B, and the photodetector 62B has a photodetector 621B.
The light source 10B, the optical path 20B, the third optical path 23B, the beam splitter 30B, the photodetector 60B, the spectroscope 61B, the photodetector 62B, the MPU 63B, the diffraction grating 611B, and the photodetector 621B are the first and second implementations described above. Since it is the same as the form, detailed description thereof will be omitted.

[Optical sensor 50B]
It is a so-called FBG sensor having an optical sensor 50B and a fiber Bragg grating, and a plurality of them are arranged on an object to be measured (not shown) in the first optical path 21B. In this embodiment, 20 optical sensors 50B are arranged in the first optical path 21B. Further, the optical sensor 50B measures the pressure and strain of the object to be measured, as in the first and second embodiments described above. Examples of the object to be measured include a pipeline laid over several tens of kilometers, as in the first and second embodiments described above. Further, the optical sensor 50B is not limited to measuring the pressure or strain of the object to be measured, and may be, for example, measuring the acceleration or temperature of the object to be measured.
Further, the optical sensor 50B is not limited to the above configuration, and for example, CFBG (chirp fiber Bragg grating), TFBG (tilted fiber Bragg grating), FP-FBG (Fabry-Perot type fiber). -Bragg grating), LPG (long-period optical type, fiber grating), etc. may be included.

Each optical sensor 50B incidents light in a predetermined wavelength region emitted from the light source 10B, and outputs output light having different wavelengths λ according to the physical quantity of the object to be measured.
In the present embodiment, the optical sensor 50B outputs the interference light as the output light. The output light output by the optical sensor 50B is not limited to the above configuration, and may be, for example, the reflected light reflected by the optical sensor 50B or the transmitted light transmitted through the optical sensor 50B. There may be. When the transmitted light is output as output light, the optical sensor 50B may be configured to include a loop mirror, a coupler, a circulator, and the like.

Here, in the present embodiment, the optical sensors 50B are arranged from near to far from the light source 10B in the order of the magnitude of the transmission loss rate of the output wavelength. For example, as shown in FIG. 2, the optical sensor 50B that outputs the output light of the wavelength λ1 of 1260 nm having a large transmission loss rate is arranged near the light source 10B, and outputs the output light of the wavelength λ20 of 1560 nm having a small transmission loss rate. The output optical sensor 50B is arranged far from the light source 10B. As described above, in the present embodiment, the wavelength of the output light to be output is in the order of the wavelength λ1 having the larger transmission loss rate to the wavelength λ20 having the smaller transmission loss rate from near to far from the light source 10B. 50B is arranged.

[Effect of Third Embodiment]
In the third embodiment as described above, the following effects can be obtained.
(7) In the present embodiment, a plurality of optical sensors 50B are arranged in the optical path 20B in which the light radiated from the light source 10B is incident, and the light is incident on the optical sensor 50B, and the output light having a different wavelength λ is emitted from the object to be measured. Output according to the physical quantity. Then, the optical sensor 50B is arranged from near to far from the light source 10B in the order of the magnitude of the transmission loss rate of the output light of the output wavelength. That is, the optical sensor 50B that outputs the output light of the wavelength λ1 having a large transmission loss rate is arranged near the light source 10B, and the optical sensor 50B that outputs the output light of the wavelength λ20 having a small transmission loss rate is arranged far from the light source 10B. Will be done. As a result, even when the physical quantity is measured using the output light having a wavelength having a large transmission loss rate, the optical sensor 50B that outputs the output light having a wavelength having a large transmission loss rate is arranged near the light source 10B. The transmission loss from the splitter 30B to the optical sensor 50B can be suppressed. Therefore, it is possible to suppress a decrease in measurement accuracy due to transmission loss from the beam splitter 30B to the optical sensor 50B, and it is possible to use light in a wider wavelength range, so that the measurement point can be set while ensuring measurement accuracy. Can be increased.

(8) In the present embodiment, since the so-called FBG sensor is used as the optical sensor 50B, more optical sensors 50B can be arranged with respect to the light in a predetermined wavelength region emitted from the light source 10B. Therefore, the number of measurement points can be increased.

[Modification example]
The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.
In the first and second embodiments, the

optical sensors

50 and 50A are configured as a so-called polarization-holding optical fiber sensor having a polarization-holding optical fiber sensor unit 51 and a reflector 52. Not limited. For example, the

optical sensors

50 and 50A may be configured as interference type sensors such as Fabry-Perot type, Mach-Zehnder type, Michelson type, and FBG type. Further, the case where these are mixed as the

optical sensors

50 and 50A is also included in the present invention.

In the first embodiment, 19 optical filters 40 are provided in the optical path 20, but the present invention is not limited to this, and 19 or more optical filters 40 may be provided, or 19 It may be less than one. That is, a plurality of optical filters 40 may be provided.
Similarly, in the first embodiment, 20 optical sensors 50 are provided, but the present invention is not limited to this. For example, the number of optical sensors 50 may be 20 or more, or may be less than 20. That is, a plurality of optical sensors 50 may be provided.

In the second embodiment, the optical filter 40A divides the light emitted from the light source 10A into separated light having 20 wavelength regions, but the present invention is not limited to this. For example, the optical filter 40A may divide the light emitted from the light source 10A into separated light having 20 or more wavelength regions, or may divide the light into separated light having less than 20 wavelength regions. It suffices that the light can be divided into wavelengths of separated light in a plurality of wavelength regions.
Similarly, in the above two embodiments, 20 optical sensors 50A are provided, but the present invention is not limited to this. For example, the number of optical sensors 50A may be 20 or more, or may be less than 20. That is, a plurality of optical sensors 50A may be provided.

In the third embodiment, 20 optical sensors 50B are provided in the optical path 20B, but the present invention is not limited to this, and 20 or more optical sensors 50B may be provided, or 20. It may be less than one. That is, a plurality of optical sensors 50B may be provided.

In the third embodiment, when the optical sensor 50B outputs the reflected light as the output light, the optical sensor 50B orders the reflected light of the output wavelength in the order of the magnitude of the transmission loss rate and the order of the shortest wavelength. It may be arranged from near the light source 10B toward a distance.
That is, in FIG. 2, the optical sensor 50B that outputs the reflected light having the wavelengths of λ4, λ11, λ14, λ17, and λ19, which are different in the order of the magnitude of the transmission loss rate and the order of the shortest wavelength, is not arranged. , The optical sensor 50B is arranged in the order of the magnitude of the transmission loss rate of the reflected light of the output wavelength and in the order of the shortest wavelength. As a result, the influence of the clad mode due to the reflected light can be suppressed.

1,1A, 1B ... Physical quantity measuring device, 10,10A, 10B ... Light source, 20,20A, 20B ... Optical path, 30,30A, 30B ... Beam splitter, 40,40A ... Optical filter, 50,50A, 50B ... Optical sensor , 51 ... Polarization-holding optical fiber sensor unit, 60, 60A, 60B ... Receiver, 61, 61A, 61B ... Spectrometer (spectrometer), 62, 62A, 62B ... Optical detection unit, 63, 63A, 63B ... MPU , 611, 611A, 611B ... Diffraction grating, 621, 621A, 621B ... Optical detection element.

Claims

A light source that emits light of a wide band wavelength,
An optical path in which the light emitted from the light source is incident, and
An optical filter provided in a plurality of optical paths and dividing the light emitted from the light source into separated light having different wavelength regions from the optical path.
An optical sensor that is provided in plurality according to the plurality of optical filters and that incidents the separated light and outputs output light corresponding to the physical quantity of the object to be measured to the optical path.
A beam splitter provided in the optical path, and a plurality of the output lights output from the plurality of optical sensors are incident and split from the optical path.
A spectroscopic element that incidents a plurality of the output lights output from the beam splitter and splits them according to the wavelength region.
A photodetector for detecting a plurality of the output lights dispersed by the spectroscopic element is provided.
The optical filter is a physical quantity measuring device, which is arranged from near to far from the light source in the order of the magnitude of the transmission loss rate of the separated light in the wavelength region for wavelength division.
In the physical quantity measuring device according to claim 1,
The optical filters are provided with n (n is a natural number).
The physical quantity measuring device is characterized in that n + 1 optical sensors are provided.
A light source that emits light of a wide band wavelength,
An optical path in which the light emitted from the light source is incident, and
An optical filter provided in the optical path that divides the light emitted from the light source into separated light having a plurality of different wavelength regions from the optical path.
An optical sensor provided in a plurality of wavelength regions according to the separated light in a plurality of wavelength regions divided by the optical filter, and the separated light is incident and the output light corresponding to the physical quantity of the object to be measured is output to the optical path.
A beam splitter provided in the optical path, and a plurality of the output lights output from the plurality of optical sensors are incident and split from the optical path.
A spectroscopic element that incidents a plurality of the output lights output from the beam splitter and splits them according to the wavelength region.
A photodetector for detecting a plurality of the output lights dispersed by the spectroscopic element is provided.
The optical sensor is a physical quantity measuring device, which is arranged from near to far from the light source in the order of the magnitude of the transmission loss rate of the separated light in the incident wavelength region.
In the physical quantity measuring device according to any one of claims 1 to 3.
The photodetector is a physical quantity measuring device characterized in that a plurality of photodetectors formed of different materials are arranged in an array.
In the physical quantity measuring device according to any one of claims 1 to 4.
The spectroscopic element is a physical quantity measuring device characterized by having a diffraction grating.
In the physical quantity measuring device according to any one of claims 1 to 5.
The optical sensor includes a polarization-holding optical fiber sensor unit that incidents the separated light and outputs a first polarized light according to a physical quantity of the object to be measured and a second polarized light having a phase different from that of the first polarized light. A physical quantity measuring device characterized by having.
A light source that emits light of a wide band wavelength,
An optical path in which the light emitted from the light source is incident, and
An optical sensor provided in a plurality of optical paths, incident light emitted from the light source, and output output light having different wavelengths according to the physical quantity of the object to be measured.
A beam splitter provided in the optical path, and a plurality of the output lights output from the plurality of optical sensors are incident and split from the optical path.
A spectroscopic element that incidents a plurality of the output lights output from the beam splitter and splits them according to the wavelength.
A photodetector for detecting a plurality of the output lights dispersed by the spectroscopic element is provided.
The optical sensor is a physical quantity measuring device, which is arranged from near the light source toward a distance in the order of the magnitude of the transmission loss rate of the output light having an output wavelength.