JP2002352369A - Optical fiber multipoint physical quantity measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber multipoint physical quantity measuring system that can connect a large number of FBGs (optical fiber Bragg grating elements) and perform batch monitoring without a wrong signal. SOLUTION: This optical fiber multipoint physical quantity measuring system is composed of an optical trunk line part 12 for transmitting light from a light source part 11 and reflected light from the FBG 15, optical branch parts 13 installed in a line on the optical trunk line part 12, optical branch line parts 14 with a plurality of FBGs 15 arranged in lines so that the wavelength of the reflected light is on the long wavelength side as the distance between the FBG 15 and the optical branch part 13 becomes longer, an optical detecting and processing part 16 for detecting and processing the reflected light from the optical trunk line part 12, a signal processing control part 17 for performing control between the light source part 12 and the optical detecting and processing part 16, and a data processing part 18 storing information on the connected positions, distances and reflected wavelength of all the FBGs 15 and performing identification processing of the data of each FBG 15 using the information in signal processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber Bragg grating (hereinafter referred to as F) which has been developed for optical wavelength division multiplexing communication using optical transmission means such as an optical fiber as a medium.
It is called BG. The present invention relates to an optical fiber multi-point physical quantity measurement system using ()) as a sensing element for measuring various physical quantities.

[0002]

2. Description of the Related Art An FBG has been developed as a key component for optical wavelength division multiplexing communication using an optical fiber as a medium, but its use for optical fiber sensing has been considered for a long time. In recent years, based on the experience of large-scale earthquake disasters, etc., the importance of monitoring technology for structural distortion of civil engineering buildings has been re-recognized, and research and development in various fields have been developed.

[0003] For example, K. O. Hill, et a
l. , Applied Physics Let
t. , 32, 10, 647, (1978),
K. O. See Hill, et al. , Applied
Physics Lett. , 62, 10, 1
035, (1993); Kurashima,
et al. , “Optronics”, 6, 11
9 (1998); Takahashi, “Opt
ronics ", 12, 157 (1996).

Attempts have been made to measure temperature and other physical quantities (strain, displacement, pressure, etc.) by converting the physical quantities into minute strains, with a focus on micro strain measurement. Development of collective multi-point measurement technology that effectively uses tracks is also underway.

A conventional optical fiber multipoint physical quantity measuring system is configured as shown in FIG.

A conventional optical fiber multipoint physical quantity measuring system includes an optical trunk 1 composed of an optical fiber serving as a backbone of optical transmission, and a plurality of FBGs 2 connected in tandem (series) by the optical trunk 1. A light source unit 3 for outputting probe light for measuring the reflection wavelength of the FBG 2 to the optical trunk line unit 1;
An optical branching unit 4 for branching the reflected light from the BG 2 from the optical trunk unit 1, a light detection processing unit 5 connected to the light branching unit 4 by an optical fiber, a light source unit 3 and a light detection processing unit 5; Signal processing control unit 6 that controls while considering the time synchronization condition
And a data processing unit 7.

The light source unit 3 is often called a white light source or a broadband light source, and has an emission spectrum that can cover all the reflection wavelength bands of the FBGs 9 used. Each reflected light from the FBG 2 is divided into an optical fiber port different from that on the light introduction side via the light branching unit 4 and reaches the light detection processing unit 5 from the light branching unit 4 on the light source unit 3 side. The light detection processing unit 5 includes a high-resolution wavelength scanning unit 8 and a high-resolution wavelength measuring unit 9 that filter a wavelength with high resolution using a diffraction grating or the principle of wavelength interference / resonance.

When a continuous light is used for the light source unit 3, an FBG
If different wavelengths are selected as the reflection wavelengths from the light source 2, wavelength analysis and optical spectrum analysis are performed on the light receiving side to measure the reflection wavelength of the light reflected from each FBG 2, the shift amount from the initial wavelength, and the like. By comparing each reflected light with a physical quantity, it is possible to measure the target physical quantity.

In the case where a pulsed light source obtained by switching with a pulsed semiconductor laser or acousto-optic device or the like is used instead of continuous light,
The reflected light from G2 reaches the light detection processing unit 5 with a propagation delay time corresponding to the installation position.

In this case, the reflection wavelength from the focused FBG 2 and the shift amount from the initial wavelength can be measured by high-resolution wavelength measurement within a time width corresponding to the delay time of the focused FBG 2.

In order to perform wavelength measurement, an FBG is generally used.
Light having a line width sufficiently smaller than the line width of the reflection spectrum of No. 2 is generated as probe light, the wavelength of this probe light is scanned to search for the wavelength of maximum light intensity, and the searched wavelength is set as the peak (center) wavelength. Identification is commonly performed. In the optical fiber multipoint physical quantity measurement system configured as described above, a plurality of FBG2 signals are identified using a system configuration including a high-resolution wavelength measurement function.

[0012]

In the conventional optical fiber multipoint physical quantity measurement system, it is assumed that a high-resolution wavelength measurement is first provided. There is a problem that a scanning time is inevitably required to scan.

In order to realize high-resolution wavelength measurement in individual wavelength steps, a sufficient amount of light is required.
The problem is that measurement time per wavelength, or when pulsed light is used, integration measurement for a large number of pulses is indispensable, and simple light intensity measurement requires a clearly long measurement time. was there.

Of course, high-resolution wavelength measurement is commercially available as a general device such as an optical spectrum analyzer or a wavelength meter, and an optical interferometer or the like for wavelength selection is arranged at the light input portion of the photodetector. It is well known as a structured structure. The same configuration can be partially applied to this optical fiber multipoint physical quantity measurement system, but there is a problem that not only the processing time as described above takes time but also the equipment cost becomes extremely high. Was.

Further, there are serious problems in the number of connected FBGs 2 and the arrangement of the FBGs 2 on an actual measurement object. In a system in which continuous light is used as the light source and FBGs 2 are simply connected in series, it is necessary to allocate the reflection wavelengths of the FBGs 2 so as not to overlap each other within the wavelength band of the light source. Change width =
There is a restriction that the maximum number of FBGs 2 can be connected to one trunk line at most.

In the case of performing data processing by time division multiplexing by pulsing light, FBGs 2 of the same wavelength can be connected in series unless delay times are overlapped, but reflected light of wavelength λa from FBG 2 far from the light source. However, when the light returns to the reflection wavelength λa connected closer to the light source, the light is not completely transmitted to the light source side but is reflected in accordance with the design reflectance of the FBG 2. Therefore, two FBs having the same wavelength λa
While light is attenuated between G2 and G2, multiple round trips are repeated, and there is a problem that it is difficult to effectively use light.

Further, as a practical problem, it is known that the reflected light component of the FBG 2 has a mode coupling phenomenon of a propagation component at the cladding and a propagation component at the core, and the like.
There is also a gentle reflection component on the shorter wavelength side than the reflection spectrum wavelength, and depending on the connection order and conditions of the FBG 2, this returns to the light detection processing unit 5 as a stray light component, and is detected as a noise component and an erroneous signal. There was a problem.

The present invention has been made in view of the above-mentioned circumstances, and provides an optical fiber multipoint physical quantity measurement system capable of connecting a larger number of FBGs, eliminating erroneous signals, and monitoring all at once. With the goal.

It is another object of the present invention to provide a simple, high-speed, and inexpensive optical fiber multipoint physical quantity measurement system using simple optical measurement and data processing.

Further, the present invention provides an optical fiber multi-point physical quantity measuring system capable of performing not only static physical quantity measurement but also dynamic physical quantity measurement, for example, measurement of temperature and vibration state. Aim.

[0021]

According to a first aspect of the present invention, there is provided an optical fiber multi-point physical quantity measuring system comprising a plurality of optical fiber Bragg grating elements (hereinafter, referred to as "FBG") for measuring a physical quantity. In an optical fiber multipoint physical quantity measurement system connected by optical fiber,
An optical trunk line that transmits measurement light and reflected light of the FBG output from the light source unit, and a plurality of optical branches that are arranged in a row on the optical trunk line and branch the measurement light from the optical trunk line unit. And a plurality of FBGs having different wavelengths of reflected light while transmitting the branched light and the reflected light of the FBG, and the wavelength of the reflected light becomes longer as the distance between the optical branching unit and the FBG becomes longer. And a light detection processing unit for detecting and processing the reflected light from the FBG, and a control between the light source unit and the light detection processing unit. The signal processing control unit stores information on connection positions or distance conditions of all the FBGs and the reflected light wavelength,
A data processing unit for identifying and processing data of each FBG using stored information at the time of signal processing.

According to the present invention, a plurality of FBGs
Are sequentially arranged in the order of the wavelength of the reflected light, and as a unit, a large number of optical branching sections are branched and arranged on the optical trunk line. As a result, while securing the degree of freedom of the connection of the optical branching path connected to the optical trunk line, it is possible to suppress the stray light due to the mutual reflection of the reflected light of the FBG and the cladding mode coupling, which were problems in the past. However, many FBGs can be connected.

In the optical fiber multi-point physical quantity measuring system according to the present invention, the output side of the optical branching unit connected to a position closest to the light source unit is provided with a plurality of optical trunk lines. A plurality of optical trunks are installed, and a plurality of optical trunks are directly connected to the output side of the optical branch unit connected to the position closest to the light source unit, or connected to the position closest to the light source unit. An optical switch is interposed on the output side of the optical branching unit, and a plurality of optical trunk lines are switchably connected to the output side of the optical switch.

By providing a plurality of optical trunk lines in this way, it is possible to secure a greater number of sensor connections.

In the optical fiber multipoint physical quantity measuring system according to the present invention, the distance between the optical branching sections of the optical trunk line, the distance between the FBGs in the optical branching path section, and
The distance between the optical branching unit and the FBG closest to the optical branching unit can be equalized.

When the connection distances are made equal,
When the wavelength band of the light source section spans a plurality of FBG reflection wavelengths, signals of a plurality of kinds of reflection wavelengths overlap and return to the light detection processing section within the same delay time, but the wavelength parameter is scanned with the time parameter fixed. As a result, signal processing of a plurality of FBGs can be performed collectively, and measurement can be performed simply and quickly.

Further, in the optical fiber multipoint physical quantity measuring system according to the present invention, as described in claim 4, the distance between the optical branching parts is located farthest from the optical branching part in the optical branching path. It can be longer than the distance between the FBG and the optical branching unit.

With such a connection distance, reflected pulses from all the FBGs can be generated without causing stray light due to cladding mode coupling light of the FBG or reciprocation due to mutual reflection of light between FBGs having the same reflection wavelength. The measurement can be returned to the photodetection processing unit without overlapping in time, and measurement can be performed simply and quickly.

In the optical fiber multipoint physical quantity measuring system according to the present invention, the light source unit may include a broadband light source unit that outputs continuous light, and an arbitrary wavelength of the output continuous light. A wavelength tunable filter unit that can selectively transmit only a band, and an optical switching unit that converts continuous light into pulse light by intermittently turning on and off the filtered light can be provided. .

In the present invention, it is possible to provide an optical fiber multi-point physical quantity measurement system capable of monitoring a large number of FBGs collectively by applying pulse light capable of performing such a wide-band wavelength scan. it can.

According to a sixth aspect of the present invention, the signal processing control section includes a gate signal generating section, and the data processing section includes a binary decision processing section, a wavelength measuring section, and a binary decision processing section. A wavelength shift measuring unit, and any one of the wavelength measuring unit and the dynamic wavelength shift measuring unit. The gate signal generating unit generates a gate signal with a required delay time for the FBG of interest. The light detection processing unit has a function of detecting light only while the gate signal is active, and the binary determination processing unit of the data processing unit has a binary determination whether the light detection processing unit has detected a light pulse. From the information, it is determined whether or not the wavelength of the reflected light from the focused FBG has changed significantly, and the wavelength measuring unit determines the maximum intensity wavelength of the observed light or the center wavelength of the wavelength spectrum, and determines the dynamic wavelength shift. The measuring section is based on the above time conditions On the other hand, the light intensity is continuously measured a plurality of times in the required time after fixing the wavelength, and attention is paid to using the relative ratio of the obtained light intensity and the calibration curve stored in the data processing unit in advance. Time change information such as the center wavelength or the wavelength shift amount of the reflected light of the FBG and the period of the change may be obtained.

In such a measuring system, it is possible to easily detect whether or not there is a certain change or more by the binary judgment processing section. In addition, it is possible to apply a general optical spectrum measurement method as a wavelength measurement unit, and furthermore, by providing these and a dynamic wavelength shift measurement unit, it is possible to mix both static and dynamic physical quantities. Measurement becomes possible.

Further, in the optical fiber multipoint physical quantity measuring system according to the present invention having a light source unit having a broadband light source unit, a wavelength tunable filter unit and an optical switching unit, the signal processing control unit may be configured as described above. Comprises a gate signal generator and a wavelength scanner, the data processor comprises at least one of a wavelength measurement unit and a dynamic wavelength shift measurement unit, and the gate signal generator
A gate signal is generated with a required delay time for BG, and the light detection processing unit has a function of detecting light only while the gate signal is active. The wavelength tunable filter section of the light source section is scanned by two or more wavelength center values, and the wavelength measurement section calculates the intensity value of the reflected light pulse and the scan wavelength value obtained by the light detection processing section for each wavelength scan. The center wavelength or the amount of wavelength shift of the reflected light is calculated by using the center of gravity calculation, or the relative ratio of the intensity of the reflected light pulse obtained by the light detection processing unit for each wavelength scan and stored in the data processing unit in advance. Using the calibration curve, the center wavelength or the amount of wavelength shift of the reflected light of the FBG of interest is determined, and the dynamic wavelength shift measurement unit fixes the wavelength with respect to the above time condition and continuously performs the required time a plurality of times. Measure light intensity Using the obtained relative ratio of the light intensity and the calibration curve stored in the data processing unit in advance, the time change information such as the center wavelength or the wavelength shift amount of the reflected light of the FBG of interest and the cycle of the change is obtained. You can ask.

In such a measurement system, the effective center reflection wavelength of the FBG and the shift amount thereof can be obtained by a method using the center of gravity calculation and the calibration curve, and simple and quick measurement can be performed. Further, by adding a dynamic wavelength shift measuring unit, it is possible to perform a measurement in which both a static physical quantity and a dynamic physical quantity are mixed.

In the optical fiber multipoint physical quantity measuring system according to the present invention having the light source unit including the broadband light source unit, the wavelength tunable filter unit and the optical switching unit, the signal processing control unit may be configured as follows. A series data measurement storage unit, the data processing unit includes a time series data binary determination processing unit, or a time series data binary determination processing unit and a dynamic wavelength shift measurement unit, the time series data measurement storage unit In synchronization with the switching timing of the optical switching unit, the reflected light pulse trains from the plurality of FBGs are measured and recorded as time-series data, and the time-series data binary determination processing unit uses the time-series data to output individual FBG signals. Is extracted to determine whether or not there is a reflected light pulse. The dynamic wavelength shift measurement unit fixes the wavelength and continuously performs the light intensity multiple times in the required time. The measurement is performed, the individual FBG signals are extracted from the time series data, and the relative ratios of the light intensities of the individual FBG reflected light pulses belonging to the plurality of time series data and the calibration previously stored in the data processing unit are measured. Using the curve, it is possible to obtain time change information such as the center wavelength or the wavelength shift amount of the reflected light of the focused FBG and the period of the change.

In such a measurement system, the probe light is converted to the half-width of the reflection spectrum of the FBG, or 1
If the wavelength width spectrum is set to the order of 1/0 width, it is possible to easily detect whether or not there is a certain change or more, and to obtain time-series data, change the delay time of the time gate. Scanning is not required, and measurement is performed quickly. If the probe light has the above-mentioned wavelength width spectrum, the time change of the wavelength shift is continuously tracked from the change in the light amount of a plurality of FBGs having the same fundamental reflection wavelength, and the change of the plurality of physical quantities is determined from the period and the shift amount. Dynamic parameters can be measured. Further, it is possible to perform a measurement in which both a static physical quantity and a dynamic physical quantity are mixed.

Further, in the optical fiber multipoint physical quantity measuring system according to the present invention having a light source unit having a broadband light source unit, a wavelength tunable filter unit, and an optical switching unit, the signal processing control unit may include: A time series data measurement storage unit and a wavelength scanning unit; the data processing unit includes at least one of a wavelength measurement unit and a dynamic wavelength shift measurement unit; In synchronization with the timing, reflected light pulse trains from a plurality of FBGs are measured and recorded as time-series data, and the wavelength scanning unit controls the wavelength-variable filter unit with two or more wavelength center values in order to obtain the time-series data. After scanning, the wavelength measurement unit extracts individual FBG signals from these time series data, and returns individual FBG reflections belonging to a plurality of time series data. Find the center wavelength or the wavelength shift of the reflected light by the centroid calculation using the value of the intensity value and scanning the wavelength of the pulse, or the individual from the time-series data of the F
The BG signal is extracted, and the F signal of interest is focused on using the relative ratios of the intensities of the individual FBG reflected light pulses belonging to the plurality of time-series data and the calibration curve stored in the data processing unit in advance.
Find the center wavelength or wavelength shift amount of the reflected light of BG,
The dynamic wavelength shift measurement unit measures the light intensity plural times continuously for a required time after fixing the wavelength, and as a result, extracts individual FBG signals from these time series data, Using the relative ratio of the light intensity of each FBG reflected light pulse belonging to the series data and the calibration curve stored in advance in the data processing unit, the center wavelength or the wavelength shift amount of the reflected light of the focused FBG and the period of the change Such time change information as described above may be obtained.

In such a measurement system, an effective center reflection wavelength of the FBG and a shift amount of the center reflection wavelength can be obtained by a method using a center of gravity calculation or a calibration curve. In addition, since light intensity data is acquired as time-series data, simple and quick measurement can be performed. Further, if the probe light is set to a half-width of the reflection spectrum of the FBG or a wavelength width spectrum of the order of 1/10 width,
The time change of the wavelength shift can be continuously tracked from the light quantity change of the plurality of FBGs having the same basic reflection wavelength, and the dynamic parameters of the plurality of physical quantity changes can be measured from the period and the shift amount. In addition, it is possible to perform a measurement in which both a static physical quantity and a dynamic physical quantity are mixed.

In the optical fiber multipoint physical quantity measuring system according to the present invention, the light introduced from the light source section is reflected by the reflection means at each end of the optical trunk line section and the optical branch path section. The data processing unit includes a terminal reflection unit that is returned to the light introduction side as reflected light, and a soundness monitoring unit that measures changes in soundness and transmission loss related to the connection state of the optical trunk line and the optical branching path from the reflected light in the data processing unit. Can be prepared.

Thus, according to the present invention, it is possible to monitor online that the optical trunk line and the optical branching unit are all properly connected without disconnection while the system is operating.

In the optical fiber multi-point physical quantity measuring system according to the present invention, when the information of the connection position / distance of the connected FBG and the reflected light wavelength cannot be given in advance, the light source unit Of each F
A wavelength scanning unit that uses light having a line width sufficiently smaller than the half-value width of the BG reflection spectrum and sequentially introduces the light into the optical trunk while sequentially scanning the wavelength in a range covering the reflected light wavelength band of all connected FBGs. A time-series data measurement storage unit for measuring and recording time-series data of the reflected light pulse train with respect to the scanning wavelength; calculating a basic reflected light wavelength of the FBG from the time-series data and the scanning wavelength information; And a calibration calculation processing unit that calculates connection position / distance information from the delay time information of the detected optical pulse and stores the result in the data processing unit.

Accordingly, in the present invention, even if there is no FBG connection condition before installation, or if a new sensor or the like is added to the installed system, a new sensor or the like may be used even after the system is operated. Thus, a calibration value prompting an actual installation state can be obtained.

Further, in the optical fiber multipoint physical quantity measuring system according to the present invention, as described in claim 12, a physical quantity transmitting mechanism for converting a physical quantity to be measured into a minute strain or a temperature change with respect to the FBG, A calibration curve storage unit that stores a calibration curve indicating a relationship between a physical quantity of a measurement target assigned to the FBG and a wavelength shift amount of the FBG;
Fiber degradation measurement unit that calculates the change in transmission loss for each path due to aging and environmental degradation from continuously accumulated data, and converts the physical quantity of the measurement target from the calibration curve recorded in the calibration curve storage unit And a conversion correction unit that performs a correction necessary for the correction based on the transmission loss change value calculated by the fiber deterioration measurement unit, and can monitor a measurement in which one or more physical quantities are mixed.

With the measurement system having such a configuration, for example, a sensor installed in a harsh environment such as a high radiation environment such as a PCV of a nuclear power plant and in a place where it is not easy to perform a patrol inspection by a person. The accuracy and reliability of system data can be improved.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical fiber multipoint physical quantity measuring system according to the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, an optical fiber multipoint physical quantity measuring system according to the present invention is indicated by reference numeral 10 as a whole. The optical fiber multipoint physical quantity measurement system 10 includes a light source unit 11,
An optical trunk 12 serving as an optical transmission means for transmitting output light or reflected light from the light source 11; a plurality of optical branching units 13 arranged in series on the optical trunk 12; Optical branching path section 14 branched from optical trunk section 12 at branching section 13
An optical fiber Bragg grating element (hereinafter, referred to as FBG) 15 installed in the branch path section 14; and a light detection processing section 16 for detecting and processing the reflected light from the optical trunk section 1.
A signal processing control unit 17 for controlling the light source unit 11 and the light detection processing unit 16; and a data processing unit 18 for identifying and processing data of each FBG 15.
The light branching unit 13 branches the light or the reflected light from the optical trunk unit 12, and transmits the branched light and the reflected light of the FBG 15 in the branch path 14. The optical trunk line section 12 and the optical branch path section 14 may be constituted by optical transmission means such as a plastic fiber instead of an optical fiber.

Further, the inside of the optical branching section 14 is arranged so that the wavelength of the reflected light of the FBG 15 becomes longer gradually toward the downstream side away from the optical branching section 13. In FIG. 1, the light source 11
The line connecting the signal processing control unit 17, the light detection processing unit 16 and the data processing unit 18 to each other represents a connection for transmitting and receiving an electric signal.

The probe light for multipoint physical quantity measurement output from the light source unit 11 is introduced into, for example, an optical fiber constituting the optical trunk unit 12, passes through the first optical branching unit 13, and is output from the optical trunk unit 1 on the output side. , While each of the light branching sections 1 on the way
Propagated through 3 and 13 sequentially. The light split by each of the splitting sections 13 is separated into an optical splitting path section 14 as an optical transmission means according to a splitting ratio. The branched light is the optical trunk line 1
The light propagates in the optical branching section 14 made of the same optical fiber as that of the optical fiber 2 and sequentially reaches the physical quantity measuring FBGs 15 arranged in series in a row. The FBG 15 is arranged in the optical branching section 14 so that the wavelength of the reflected light becomes longer on the long wavelength side as the distance from the optical branching section 13 increases.

At the FGB 15 to which the branched light of the output light from the light source unit 11 arrives, reflected light is generated in accordance with the reflected wavelength, and the reflected light from the FBG 15 is directed toward the light introduction side by the light branching path unit 14. In the opposite direction, the light propagates through the optical branching section 13 and, depending on the position of the optical branching path 13, further through the optical trunk line section 12 and the plurality of optical branching sections 13, 13. The light reaches the near optical splitter 13 (first optical splitter).

The reflected light is guided to an optical fiber port different from the light introduction side (light source section side) via the first light branching section 13 and reaches the light detection processing section 16.

The light detection processor 16 measures the amount of change such as the wavelength reflected from each FBG 15 and the amount of shift from the initial wavelength. The measured data is sent as an electric signal to a signal processing control unit 17 that controls between the light source unit 11 and the light detection processing unit 16 and is subjected to signal processing. Data processing unit 18
In the following, each FBG is connected using the connection position or distance condition of the FBG 15 stored in advance and information on the reflected light wavelength.
Data identification of 15, 15 and measurement processing of physical quantities such as temperature, pressure, strain, and change are performed.

In the case where pulse light is used as probe light output from the light source unit 11 and signal processing is performed by time division multiplexing, the FBGs 15 having the same basic reflection wavelength are arranged with different time differences on the time axis. The reflected light of the FBG 15 having the fundamental reflection wavelength can reach the light detection processing unit 5 without encountering another FBG 15 having the same fundamental reflection wavelength. By doing so, FBG15, 1
100% by avoiding the influence of stray light reflected light components caused by the mode coupling between the cladding propagation mode and the core propagation mode which occur on the short wavelength side due to the mutual reflection between the five and the original reflection spectrum.
An FBG 15 having a similar reflectance design can be connected.
As a result, the amount of reflected light increases, so that multi-stage branching becomes possible, and as a result, collective measurement of a large number of FBG sensors becomes possible.

Although it is simpler to make the branching ratio of each optical branching section 13 practically the same for all practical purposes, in order to further increase the number of connection points, the closer to the light source section, the closer to the optical branching path section 14 side. It is also effective to keep the measurement accuracy uniform by reducing the distribution (light branching ratio) of the light and by leveling the amount of light introduced into the light branching path 14 as a whole.

A plurality of optical trunks In the optical fiber multipoint physical quantity measuring system 10 shown in FIG. 1, an example in which one optical trunk 12 is provided is shown.
As shown in FIG. Hikari Line 12
By providing a plurality of sensors as shown in FIGS. 12a and 12b, it is possible to secure a greater number of sensor connections, thereby increasing the light utilization rate and making it possible to collectively measure a greater number of physical quantities. Become.

For example, as shown in the optical fiber multi-point physical quantity measuring system 10 A of FIG. 2, a plurality of optical trunk lines 12 a and 12 b are provided on the branch output side of the optical branch unit 13 connected to the position closest to the light source unit 11. Are directly connected to form a configuration having a plurality of optical trunk lines 12a and 12b. Also,
As shown in the optical fiber multipoint physical quantity measurement system 10B of FIG. 3, the optical switch 20 may be installed on the branch output side of the optical branching unit 12 connected to the position closest to the light source unit 11. The optical switch 20 is configured to switchably connect one optical trunk line (optical fiber) on the input side to a plurality of output optical trunk lines 12a and 12b. By providing the optical switch 20, a plurality (pieces) of optical trunk lines 12a and 12b can be provided.

The same components as those of the optical fiber multi-point physical quantity measuring system 10 shown in FIG.

In FIG. 2, the optical trunk 12 from the light source 11
The optical branching unit 13 that first meets the two optical trunk lines 12
a and 12b are connected. As shown in FIG. 2, at least one of the optical trunks 12b has a different length from the optical trunk 12b so that a propagation delay occurs after branching.

By setting this delay time to a convenient optical trunk length according to the signal processing, it becomes possible to distinguish between the two optical trunks 12a and 12b. As a result, the optical fiber multipoint physical quantity measurement system 10A is configured with two systems of optical trunk lines 12a and 12b, and these two systems can be processed collectively. This allows
It is possible to realize a system capable of monitoring a larger number of FBGs 15 collectively.

Usually, it is necessary to introduce probe light into the optical fiber which becomes the optical trunk line section 12 (12a, 12b) and to detect reflected light returning from the same line, so that the optical branching means is provided to the optical branching sections 13, 13. Used. As a light branching unit, a fusion type optical branching unit is often used for the light branching units 13 and 13. Since this optical branching unit can connect two-port optical fibers to the input and output sides, respectively, the light source unit is used. The optical trunk line section 12 is provided on the side opposite to each port on the optical detection processing side.
a and 12b can be connected. By maximizing the light utilization rate in this way, it is possible to secure at least twice or more sensor connections.

In FIG. 3, the optical trunk line 12 from the light source 11
The optical switch 20 is connected to the output side of the optical branching unit 13 where the optical fiber is first encountered, and the optical fiber multipoint physical quantity in which the two optical trunk lines 12a and 12b are branched and connected to the output side of the optical switch 20. The measurement system 10B is shown. in this case,
The same configuration can be used for the plurality of optical trunk lines 12a and 12b to be switched and the optical branching path 14 connected thereto.

The optical switching unit 20 is also electrically connected to the signal processing control unit 17, and switches the optical switching unit 20 in synchronization with the light detection processing and the data processing operation by a control signal from the signal processing control unit 17. Is performed. By using a plurality of optical trunk lines 12a and 12b of the same connection design connected to the optical fiber multipoint physical quantity measurement system 10B and using them while switching, it is possible to realize a system capable of monitoring a large number of FBGs 15 collectively. it can. When the optical switch 20 is used in combination with an optical splitter, it is possible to connect more optical trunk lines than the number of output ports of the optical splitter described above.

Branch interval Optical fiber multipoint physical quantity measuring systems 10 and 10 of the present invention
A, 10B, the distance between the optical branching parts 13, 13;
Length of optical branching section 14, FBG1 in optical branching section 14
The distance between the light sources 5 and 15 and the like are not particularly limited, and can be appropriately determined in general according to the wavelength band of the light source unit 11 to be used, the signal processing of the FBG 15, the identification method, and the like.

For example, in one optical trunk section 12, the distance between the optical branch sections 13 and 13 and the FB in the optical branch path section 14
The distance between G15 and G15, the optical splitter 13 and the optical splitter 13
Can be made equal to the distance from the FBG 15 closest to the FBG 15.

The optical fiber multi-point physical quantity measuring system 10C shown in FIG. 4 has the same basic components as the optical fiber multi-point physical quantity measuring system 10 shown in FIG. are doing. Optical branching unit 13,
Lc is the connection interval between the optical branching units 13 and F
Assuming that the connection interval of the BG 15 is Lsc and the connection interval of the FBGs 15 and 15 is Ls, all of them are equal intervals Ls = Lc.
= Lsc.

When an FBG 15 discriminating method utilizing pulsed light and propagation delay time using time division multiplexing is applied, reflected light pulses from all FBGs 15 are:
There is no same wavelength component having the same delay time. Conversely,
With the same delay time, signals of the FBGs 15 having different wavelengths can exist simultaneously.

For this reason, the wavelength tunable filter on the side of the light source unit 11 is controlled by the signal processing control unit 17 for scanning, or the appropriate wavelength filtering and wavelength scanning are performed on the photodetection processing unit 16 side. Signal processing of a plurality of FBGs 15 can be performed collectively for time conditions, and a simple and quick multipoint physical quantity measurement system 10C can be realized.

In the optical fiber multipoint physical quantity measuring system 10 C, the distance between the optical branching units 13, 13 is the distance between the FBG 15 located farthest from the optical branching unit 13 in the optical branching unit 14 and the optical branching unit. 13 can be made longer.

In the optical fiber multi-point physical quantity measuring system 10D shown in FIG. 5, the basic components are the same as those in FIG. 1, but a length restriction is added as a connection condition. The connection interval between the optical branching units 13 and 13 is Lc, and the optical branching unit 14
, The connection interval between the optical branching unit 13 and the farthest FBG 15 is Ld, and Ld <Lc.

When an FBG 15 discrimination method using pulsed light and propagation delay time using time division multiplexing is applied, reflected light pulses from all FBGs 15 are arranged with different delay times on the time axis. The FBG 15 that satisfies one wavelength condition can be acquired by one time scanning measurement, and a simple and quick physical quantity measurement system 10D can be realized.

When such a connection distance relationship is maintained, F
As described above, without causing stray light due to cladding mode coupling light of the BG 15 or reciprocation due to mutual reflection of light between the FBGs 15 having the same reflection wavelength,
The reflected pulses from the BG 15 can return to the light detection processing unit 16 without overlapping in time, have no noise (noise) or erroneous signal components, and can be separated by wavelength or in time, so that many FBGs 15 can be separated. Can be simply processed.

Light source section optical fiber multipoint physical quantity measuring system 10 (10A to 10A)
As the light source unit 11 in B), any of broadband light emission, broadband wavelength spectrum light such as white light, arbitrary line spectrum light, continuous light, and pulsed light can be used, and the reflection wavelength of the target FBG 15 can be used. , FBG 15 signal processing, identification method and the like.

For example, as shown in FIG. 6, the light source unit 11 includes a broadband light source unit 22 that outputs continuous light (CW),
A wavelength tunable filter unit 23 such as a band-pass filter capable of selectively transmitting only an arbitrary wavelength band out of the output continuous light, and a continuous operation by intermittently turning on and off the filtered light. An optical switching unit 24 that converts light into pulsed light is provided.

In the optical fiber multipoint physical quantity measuring system,
As a light source in the light source section 11, as shown in FIG. 7A, it is preferable to use a broadband light source (section) 22 having a nearly flat emission characteristic in a wide emission wavelength band. Specifically, it is possible to use an ASE light source using a spontaneous emission light component (ASE) in a light amplification operation of a rare earth doped fiber doped with a rare earth element such as europium, a super luminescence diode (SLD), and a wavelength tunable laser. it can.

As shown in FIG. 7A, the FBG of interest
The wavelength tunable filter unit 23 and the optical switching unit 24 are used to generate pulsed probe light including light corresponding to the 15 reflection wavelength bands Δλ. Tunable filter section 2
3 is a filter having a wide line width by an acousto-optic element,
Alternatively, a filter element having a small line width using an optical interference / resonator can be used. Also, the optical switching unit 2
4 is a pulse that changes over time as shown in FIG. 7B by electrically controlling the acousto-optic element and the dielectric multilayer film to control the effective transmittance of light in a specific wavelength band. Can create light.

With such a light source section 11, spectrum characteristics can be arbitrarily adjusted in accordance with a signal processing mode, from a broadband wavelength spectrum of broadband light emission and white light to light having an arbitrary line spectrum. Also, by obtaining a pulsed optical output over a wide wavelength band, signal processing can be performed by time division multiplexing using propagation delay time in addition to wavelength multiplexing by the FBG 15, so that FBG
The number of 15 connections can be greatly increased.

Signal processing controller: gate signal generator Optical fiber multipoint physical quantity measurement system 10 (10A to 10A)
D), the light source unit 11 includes a broadband light source unit 22, a wavelength tunable filter unit 23, and an optical switching unit 24. In this optical fiber multipoint physical quantity measurement system 10, FIG.
As shown in (1), the signal processing control unit 17 includes a gate signal generation unit 25, and the data processing unit 18 includes a binary determination processing unit 26. The data processing unit 18 includes, in addition to the binary determination processing unit 26, a wavelength measurement unit, one of the binary determination processing unit 26 and the dynamic wavelength shift measurement unit, and one of the wavelength measurement unit and the dynamic wavelength shift measurement unit. With the provision, a large number of physical quantities can be measured favorably.

The gate signal generating section 25 outputs the FBG of interest.
15 has a function of generating a gate signal with an appropriate delay time, and the light detection processing unit 16 detecting light only while the gate signal is active. Binary judgment processing unit 26
Determines whether or not the wavelength of the reflected light from the focused FBG 15 has changed significantly based on the binary information indicating whether or not the light detection processing unit 16 has detected the light pulse. In addition, the wavelength measurement unit of the data processing unit 18 measures the maximum intensity wavelength of the observed light or the center wavelength of the wavelength spectrum, and the dynamic wavelength shift measurement unit fixes the wavelength with respect to the above time condition. Then, the measurement is performed a plurality of times continuously over time, and the center wavelength or the wavelength shift amount of the reflected light of the FBG 15 and the amount thereof are determined by using the obtained relative ratio of the light intensity and the calibration curve stored in the data processing unit 18 in advance. Time change information of a change cycle is obtained.

Gate Type Digital Binary Judgment The optical fiber multipoint physical quantity measuring system 10 (10A to 10D) shown in FIGS. 8 and 9 includes a gate signal generator 25 in the signal processing controller 17 and a data processor 18 in the data processor 18. An example including a binary determination processing unit 26 is shown.

In FIG. 8, the signal processing control unit 17 includes a gate signal generation unit 25, and the light detection processing unit 16 has a function of detecting light only while the gate signal is active. The data processing unit 18 includes a binary determination processing unit 26.

With respect to the optical pulse of the probe light output from the light source unit 11 to the optical trunk unit 12, the reflected pulse from each of the FBGs 15 and 15 is subjected to a light detection processing unit 16 with a propagation delay time corresponding to the connection position. Come back to, but in that,
As shown in FIG. 9 (a), the gate signal generation unit 25 has a delay time T corresponding to the propagation delay time of the FBG 15 of interest.
Along with d, a time gate signal Tw having a time width equal to or greater than the pulse width of the light reflection pulse is generated. In synchronization with the gate signal Tw, the light detection processing unit 16 detects the reflected light of the focused FBG 15 and extracts the signal, thereby extracting the gate signal in the time zone including the reflected pulse signal of the focused FBG 15. be able to.

The binary determination processing section 26 determines whether or not the intensity of the light intensity signal extracted in synchronization with the gate signal is equal to or greater than a predetermined threshold. As shown in FIG. 9B, the probe light wavelength band (λ ± Δλ) from the light source unit 11 is kept constant, and in a normal state, the wavelength width state a is such that the reflection wavelength of the focused FBG 15 is almost covered. Keep it. Here, it is assumed that the reflection wavelength of the FBG 15 shifts to the longer wavelength side as indicated by b. In this case, the light detection processing unit 1
The reflected light signal detected in 6 is, as shown in FIG.
This indicates a small value b from the original reflected pulse light intensity a from the FBG 15. By comparing this change in light intensity with a preset threshold value, it is possible to determine whether there has been a change in wavelength, that is, whether there has been a change in physical quantity. In addition, by sequentially changing the delay time Td in FIG. 9A and outputting the time gate signal Tw, it is possible to read whether or not there is a change in the physical quantity state of the FBG 15 of interest.

Assuming that the probe light is a half-width of the reflection spectrum of the FBG 15 or a wavelength width spectrum of the order of 1/10 width, it is easy to detect whether or not there is a change exceeding a certain level. Can be.

[0083] gate Wavelength Measurement Figure 10 is an optical fiber multi-point physical quantity measuring system 10 (10
A to 10D) are provided with a gate signal generation unit 25 in the signal processing control unit 17 and a wavelength measurement unit 30 is provided in the data processing unit 18.
An example provided with

In FIG. 10, the signal processing control unit 17 includes:
A gate signal generation unit 25 is included, the light detection processing unit 16 has a function of detecting light only while the gate signal is active, and a wavelength measurement unit 30 is included in the data processing unit 18. ing.

The signal processing control unit 17 has a gate signal generation unit 2
5, the gate signal generator 2 is provided in the same manner as the example shown in FIG.
5, the reflected pulse light from the FBG 15 of interest is selectively input to the light detection processing unit 16. The wavelength measuring unit 30, the gate signal generating unit 25, and the light detection processing unit 16 are synchronized with each other, and perform spectrum analysis of the reflected pulse light input to the light detection processing unit 16.

More specifically, the maximum intensity wavelength of the light observed by the wavelength measuring unit 30 or the center wavelength of the wavelength spectrum can be obtained by using one FBG1 in the time gate signal.
When only five reflected pulses are included, a method of simply obtaining the wavelength having the highest light intensity is employed. When light pulses having reflection wavelengths of a plurality of different FBGs 15 and 15 are mixed, wavelength scanning is performed to search for a plurality of wavelength values that are maximal with respect to the scanning wavelength, and these are searched for by the respective FBGs 15 and 15.
It is recognized as the reflection wavelength from.

An optical fiber multipoint physical quantity measurement system 1 including such a gate signal generation unit 25 and a wavelength measurement unit 30
At 0, the FBG 15 of interest can be specified by a time gate signal with a delay time, and then a general-purpose device such as a general optical spectrum measuring method or an optical spectrum analyzer is applied as the wavelength measuring unit 30. be able to.

Signal processing controller: gate signal generator and wavelength
Scanning unit and optical fiber multipoint physical quantity measurement system 10 (10A
10D), the light source unit 11 includes a broadband light source unit 22, a wavelength tunable filter unit 23, and an optical switching unit 24.
In the case of the optical fiber multipoint physical quantity measurement system 10, the signal processing control unit 17 includes the gate signal generation unit 25, and the data processing unit 18 includes the wavelength measurement unit 30 and / or the dynamic wavelength shift measurement unit. It is possible to measure a large number of physical quantities satisfactorily.

Gate signal generator 2 of signal processing controller 17
Reference numeral 5 has a function of generating a time gate signal with an appropriate delay time for the focused FBG 15 and allowing the light detection processing unit 16 to detect light only while the gate signal is active. The wavelength scanning unit 31 of the signal processing control unit 17 scans the wavelength tunable filter unit 23 of the light source unit 11 with two or more wavelength center values with respect to the above-mentioned time condition. Using the intensity value of the reflected pulse light and the value of the scanning wavelength obtained by the light detection processing unit 16, the center wavelength or the wavelength shift amount of the reflected light is calculated by the center of gravity calculation, or the light detection processing unit Using the relative ratio of the intensity of the reflected pulse light obtained in step 16 and the calibration curve stored in the data processing unit 18 in advance, the central wavelength or the amount of wavelength shift of the reflected pulse light of the focused FBG 15 is determined. The dynamic wavelength shift measurement unit of the data processing unit 18 performs measurement a plurality of times continuously over time after fixing the wavelength with respect to the time condition, and stores the relative ratio of the obtained light intensity and the data processing unit 18 in advance. Using the calibration curve
Time change information such as the center wavelength or the wavelength shift amount of the reflected light of the BG 15 and the cycle of the change is obtained.

Gate signal generator, wavelength scanner, wavelength measurement
The signal processing control unit 17 includes a gate signal generation unit 25 and a wavelength scanning unit 31, and the data processing unit includes an optical fiber multipoint physical quantity measurement system 10 (10A to 10A) including a wavelength measurement unit.
FIG. 11 shows an example of D).

In FIG. 11, the signal processing control unit 17 includes:
A gate signal generation unit 25 and a wavelength scanning unit 31 are provided. The light detection processing unit 16 has a function of detecting light only while the gate signal is active.
In the wavelength measurement, the center wavelength or the wavelength shift amount of the reflected light is calculated by the center of gravity calculation using the intensity value of the reflected light pulse and the value of the scanning wavelength obtained by the light detection processing unit 16 for each wavelength scan. A unit 30 is provided.

Gate signal generator 2 of signal processing controller 17
5 generates a time gate signal having a time width equal to or greater than the pulse width of the optical pulse, with a delay time corresponding to the propagation delay time of the FBG of interest. The reflected pulse light is detected by the light detection processing unit 16 in synchronization with the gate signal, and the signal is taken out.
Is input to the light detection processing unit 16 selectively. The wavelength scanning unit 31 of the signal processing control unit 17 uses the light source unit 11 with two or more wavelength center values for this time condition.
The wavelength variable filter unit 23 is scanned a plurality of times, and the light detection processing unit 16 measures the light intensity of the reflected light pulse obtained for each wavelength scan. The wavelength measuring unit 30 of the data processing unit 18 calculates the center wavelength or the amount of wavelength shift of the reflected light by calculating the center of gravity using the intensity value of the reflected light pulse and the value of the scanning wavelength obtained by the light detection processing unit 16.

Calculation of the center of gravity The calculation of the center of gravity will be described with reference to FIGS. 12 (a) and 12 (b). FIG. 12A shows that the light source unit 11 scans the reflected wavelength spectrum three times with λ1 to λ3 with pulse probe light having a certain wavelength spread. The light intensity obtained in each scan is shown in FIG.
If the three wavelength scans are completely symmetric with respect to the reflection spectrum, that is, if the scanning wavelength center value λ2 completely matches the reflection center wavelength, the three times scanning shown in FIG. Has a symmetric distribution. However, actually, λ2 and the reflection center wavelength are shifted.

Assuming that the wavelength width of the probe light output from the light source unit 11 is Δ, the reflection center wavelength is indicated by a dotted line in FIG. 12B, and the relative light intensity obtained by each wavelength scanning is shown in FIG. Suppose that they are I ₁ , I ₂ , I _{3 as shown} in FIG. In this case, the center wavelength is set to λ2-x. The following equation holds as the center of gravity calculation.

[0095]

(Equation 1)

Since x is obtained by solving this, the center wavelength λ2-x can be calculated.

In such a measuring system, the probe light is not converted into a half-width of the reflection spectrum of the FBG 15 or a wavelength width spectrum in the order of 1/10 width, instead of performing the scanning of the probe light in a linear spectrum many times. Based on the premise, an effective FBG center reflection wavelength can be obtained from the light intensity measurement data for a plurality of wavelength values and the center-of-gravity calculation using the scanning center wavelength of the probe light. Since the center of gravity can be calculated at least twice, the wavelength center of the FBG can be obtained with only a very small number of wavelength scans, so that simple and quick measurement can be performed.

Relative Ratio / Calibration Curve Next, similarly to FIG. 11, the signal processing control unit 17 includes a gate signal generation unit 25 and a wavelength scanning unit 31, and the data processing unit 18 includes a wavelength measurement unit 30. FIG. 13 shows an example in which the calculation method in the wavelength measurement unit 30 included in the data processing unit 18 is different.

The calculation method in the wavelength measuring unit 30 of the data processing unit 18 is such that the relative ratio of the intensity of the reflected light pulse obtained by the light detection processing unit 16 for each wavelength scan and the ratio stored in the data processing unit 18 in advance. F using the calibration curve
This is a method for obtaining the center wavelength or the wavelength shift amount of the reflected light of the BG 15. FIG. 13 shows this wavelength calculation method.

FIG. 13A shows that wavelength scanning is performed on the reflection wavelength spectrum of the FBG 15 at wavelengths λ1 and λ2 having a constant width Δ. It is assumed that the shift direction of the reflection wavelength from the FBG 15 can be specified in only one direction as shown in FIG. In this case, FIG.
As shown in (b), the ratio R of the light intensity obtained in each of the two wavelength scans is related to the amount of the wavelength shift, and the relationship between the wavelength shift and the light intensity is previously shown in FIG. The multi-point physical quantity measurement system 10 (10A
To 10D). At the time of actual measurement, the amount of wavelength shift can be calculated by applying the observed R value to the calibration curve A.

According to this, the wavelength shift amount can be calculated with the minimum number of scans of two wavelength scans.

In such an optical fiber multipoint physical quantity measuring system 10 (10A to 10D), the probe light is not scanned by the linear spectrum probe light many times, but the half width of the reflection spectrum of the FBG 15 or 10 times. Assuming that the wavelength width spectrum is on the order of one-half width, the effective shift amount of the center reflection wavelength of the FBG 15 can be obtained from the ratio of the light intensity measurement data to the wavelength scanning values for a plurality of times and the calibration curve A. . Since the wavelength center of the FBG 15 can be obtained with only a very small number of wavelength scans, simple and quick measurement can be performed.

Gate signal generator / wavelength scanner / dynamic wavelength
FIG. 14 shows a shift measuring section in which the light source section 11 includes a broadband light source section 22, a wavelength tunable filter section 23,
Optical fiber multi-point physical quantity measurement system 10 including
In (10A to 10D), an example of a dynamic physical quantity measurement system 10E in which the signal processing control unit 17 includes the gate signal generation unit 25 and the wavelength scanning unit 31 and the data processing unit 18 includes the dynamic wavelength shift measurement unit 33 Is shown.

Gate signal generator 2 of signal processing controller 17
Reference numeral 5 has a function of generating a time gate signal with an appropriate delay time for the focused FBG 15 and allowing the light detection processing unit 16 to detect light only while the gate signal is active. The dynamic wavelength shift measuring unit 33 of the data processing unit 18
The light intensity is continuously measured a plurality of times in the required time after fixing the wavelength with respect to the above time condition, and the relative ratio of the obtained light intensity and the calibration curve stored in advance in the data processing unit 18 are used. The dynamic physical quantity can be satisfactorily measured by obtaining the time-varying information such as the center wavelength or the wavelength shift amount of the reflected light of the focused FBG 15 and its changing period.

This optical fiber multipoint physical quantity measurement system 1
FIG. 14 shows an example of 0E.

In FIG. 14, the signal processing control unit 17 includes
A gate signal generation unit 25 and a wavelength scanning unit 31 are provided, and a dynamic wavelength measurement unit 30 is provided in the data processing unit 18.

The reflected light of the focused FBG 15 corresponding to the delay time of the gate signal generator 25 is measured by the light detection processor 16. When the light intensity and wavelength of the probe light are constant, pulse reflected light that can always be regarded as having the same intensity is detected unless the reflected wavelength spectrum is shifted.

However, when the pulse reflection wavelength from the FBG 15 changes (shifts), the intensity of the pulse reflection light also changes. In contrast, when the expansion and contraction of the FBG 15 occurs periodically, the shift of the pulse reflection wavelength also becomes periodic. As a result, the period of the intensity change of the detected light intensity becomes equal to these periods. According to the sampling theorem, FBG1
By measuring the change in the light intensity at a sampling frequency of half or more of the frequency components of the physical phenomenon causing the wavelength shift of 5, the frequency of the physical phenomenon change can be measured.

As described above, by temporarily fixing the wavelength in the wavelength scanning unit 31 and repeatedly collecting data continuously over time, the period of the FBG wavelength change in that section can be dynamically detected. Can be.

In this measurement system 10E, the gate signal generation unit 15 outputs the FBG 1 of interest as described above.
A time gate signal having a time width equal to or greater than the pulse width of the optical pulse is generated with a delay time corresponding to the propagation delay time of No. 5. The light is detected by the light detection processing unit 16 in synchronization with the gate signal, and the signal is extracted, so that the reflected light of the FBG 15 of interest is measured by the light detection processing unit 16. At this time, the dynamic wavelength shift measurement unit measures the light intensity a plurality of times consecutively temporally after fixing the wavelength with respect to this measurement condition, and performs a data processing in advance with the relative ratio of the obtained light intensity. Using the calibration curve stored in the section,
The time change information of the center wavelength or the wavelength shift amount of the reflected light of the focused FBG 15 and the period of the change is obtained.

The static and dynamic physical quantity measurement light source unit 11 includes a broadband light source unit 22 and a tunable filter unit 2.
In the optical fiber multi-point physical quantity measurement system 10 (10A to 10D) of FIG. 6 including the optical switching unit 3 and the optical switching unit 24, the signal processing control unit 17 further includes a gate signal generation unit and a wavelength scanning unit 31, and a data processing unit. By providing the dynamic wavelength shift measuring unit 33 with the dynamic wavelength shift measuring unit 18, the dynamic physical quantity can be measured.

The multi-point physical quantity measuring system 10E for measuring dynamic physical quantities can be combined with the above-described system 10 (10A to 10D) for measuring static physical quantities. The dynamic multi-point physical quantity measurement system 10E includes a configuration including a gate signal generation unit and a binary determination processing unit, a configuration including a gate signal generation unit and a wavelength measurement unit, a gate signal generation unit, a wavelength scanning unit, and a wavelength measurement unit. And a static multi-point physical quantity measurement system 10 (10A to 10D) provided in the signal processing control unit and the data processing unit 18 of the dynamic wavelength shift measurement unit 33 to form one measurement system.

This static / dynamic physical quantity measurement system 10
In E, the measurement of the dynamic physical quantity is fixed at a specific scanning wavelength, and the light intensity of the reflected pulse of the FBG 15 focused on a specific gate time is temporally and continuously obtained.
This is performed by calculating the wavelength shift period of the BG 15 and calculating the amount of wavelength shift by performing wavelength scanning. By these procedures, it is possible to obtain both the amount of the wavelength shift and the period thereof, and it is necessary to measure the fact that the change over time is itself a physical quantity, such as a vibration measurement and a static steady state measurement. Can be used for both.

Time series data measurement storage section / time series data 2
Value determination processing unit Optical fiber multipoint physical quantity measurement system 10 (10A to 10E) including light source unit 11 having broadband light source unit 22, variable wavelength filter unit 23, and optical switching unit 24 in light source unit 11 as described above.
, The signal processing control unit 17 includes a time-series data measurement storage unit 28, and the data processing unit 18 includes a time-series data binary determination processing unit 29 or a time-series data binary determination processing unit 2.
9 and the dynamic wavelength shift measuring unit 33, a large number of static or dynamic physical quantities can be measured favorably.

The time series data measurement storage section 28 of the signal processing control section 17 measures and records reflected light pulse trains from the plurality of FBGs 15 as time series data in synchronization with the switching timing of the optical switching section.
The time series data binary judgment processing unit 29 extracts the signals of the individual FBGs 15 from these time series data and judges whether or not there is a reflected light pulse. , The measurement is continuously performed a plurality of times at a certain time after the wavelength is fixed, and the individual F
The signal of the BG 15 is extracted, and the signal of the focused FBG 15 is extracted using the relative ratio of the light intensity of the pulse reflected light from the individual FBGs 15 belonging to the plurality of time series data and the calibration curve stored in the data processing unit 18 in advance. Time change information such as the center wavelength or the amount of wavelength shift of the reflected light and the cycle of the change can be obtained.

FIGS. 15 and 16 show examples in which the signal processing control section 17 is provided with a time series data measurement storage section 28 and the data processing section 18 is provided with a time series data binary decision processing section 29.

In FIG. 15, the signal processing control unit 17 includes
A time-series data measurement storage unit 28 is provided, and a time-series data binary determination processing unit 29 is provided in the data processing unit 18.

The time-series data measurement storage unit 28 includes the light source unit 1
Synchronize with the pulsing timing of 1 and collectively measure and store all the reflected pulse trains from the FBG whose reflected wavelength matches the wavelength band of the pulsed light returning from the section with a certain delay time in a time-series manner. Is what you do. One practical method is to convert a light pulse into an electric pulse using a photoelectric conversion element,
The data may be converted and stored as a digital data string.

The time-series data binary decision processing section 29 converts each of the FBGs of interest from the stored digital data string.
The presence or absence of a pulse detected in the delay time section corresponding to the 15 connection positions or the light intensity (peak value) is sequentially calculated and determined. Thus, by acquiring the reflection signals of all the FBGs 15 collectively by introducing the optical pulse at least once, it is possible to detect whether or not each FBG 15 has changed.

By adopting such a procedure, the detailed change amount is limited to only the FBG 15 where the change is detected.
Since the procedure for examining the change in the amount of wavelength shift = measured physical quantity can be continued, the processing can be performed in a reasonable and shortest time.

As shown in FIG. 16, by sequentially changing the wavelength band λ to be pulsed by the light source section 11, signals from all the FBGs 15 can be acquired with a small number of scans. In the figure, λ is sequentially scanned at regular intervals, so to speak, continuously, but it is measured by designating an arbitrary wavelength discretely according to the FBG 15 of interest and measuring and storing time-series data for the wavelength. Time can be kept to a minimum.

In such a measurement system, if the probe light is a half-width of the reflection spectrum of the FBG 15 or a wavelength width spectrum of the order of 1/10 width, it is easy to determine whether or not there is a certain change or more. Can be detected. Also, data (time-series data) according to the time axis of light intensity, not the light intensity for a specific time window
, It is not necessary to perform scanning while changing the delay time of the time gate, and quick measurement can be performed.

Signal processing control unit: time-series data measurement storage unit
Wavelength Scanning Unit In an optical fiber multipoint physical quantity measurement system in which the light source unit 11 includes a broadband light source unit 22, a wavelength tunable filter unit 23, and an optical switching unit 24, as shown in FIG. Is the time series data measurement storage unit 28
And the wavelength scanning unit 31, and the data processing unit 18 includes at least one of the wavelength measuring unit 30 and the dynamic wavelength shift measuring unit, so that a large number of physical quantities can be measured favorably.

As described above, the time series data measurement storage unit 28 measures and records the reflected light pulse trains from the plurality of FBGs 15 and 15 as time series data in synchronization with the switching timing of the optical switching unit. Wavelength scanning unit 31
Scans the wavelength tunable filter unit with two or more wavelength center values to acquire this time-series data,
The wavelength measuring unit 30 extracts the signals of the individual FBGs 15 from the time series data and calculates the center of gravity using the intensity values of the individual FBG reflected light pulses belonging to the plurality of time series data and the values of the scanning wavelength. To obtain the center wavelength or the amount of wavelength shift of the reflected light, or extract the signal of each FBG 15 from these time-series data, and determine in advance the relative ratio of the intensity of each FBG reflected light pulse belonging to a plurality of time-series data. Using the calibration curve stored in the data processing unit 18, the central wavelength or the amount of wavelength shift of the reflected light of the FBG 15 of interest is determined. The data processing unit 18 may include a dynamic wavelength shift measuring unit 33. This measuring section 33 is shown in FIG.
As shown in FIG. 4, the light intensity is measured a plurality of times continuously for a required time after fixing the wavelength, and the signals of the individual FBGs 15 are extracted from the time series data and belong to the plurality of time series data. Using the relative ratio of the light intensity of each FBG reflected light pulse and the calibration curve stored in advance in the data processing unit, the time change such as the center wavelength or the wavelength shift amount of the reflected light of the focused FBG 15 and the period of the change. Ask for information.

Time-series data measurement storage unit / wavelength scanning unit / wave
FIG. 17 shows an example in which the length measurement unit signal processing control unit 17 includes a time-series data measurement storage unit and a wavelength scanning unit, and the data processing unit includes a wavelength measurement unit.

In FIG. 17, the signal processing control unit 17 includes:
A time series data measurement storage unit 28 and a wavelength scanning unit 31 are provided, and the wavelength measurement unit 30 is included in the data processing unit 18.
Is provided.

The time-series data measurement storage unit 28 of the center-of-gravity calculation signal processing control unit 17
As described above, in synchronism with the pulsing timing of the light source unit 11, all the reflected pulse trains from the FBG 15 whose reflected wavelength matches the wavelength band of the pulsed light returning from the section with a certain delay time are collectively collected. Then, measurement and storage are performed in chronological order. As a practical example, the time-series data measurement storage unit 28 may convert an optical pulse converted into an electric pulse by a photoelectric conversion element into an AD at a sampling interval of a predetermined time, and store the digital data as a digital data string.

The wavelength scanning unit 31 of the signal processing control unit 17
In order to obtain the time series data, the wavelength variable filter unit 23 of the light source unit 11 is scanned with two or more wavelength center values, and the reflected light pulse obtained by this wavelength scanning is scanned by the light detection processing unit 16.
The time series data measurement storage unit 28 measures and records the time series data.

A signal of each FBG 15 is extracted from time series data obtained by performing wavelength scanning a plurality of times around the wavelength of the pulse reflected light from the FBG 15 of interest, and the pulse of each FBG 15 belonging to the plurality of time series data is extracted. The light intensity value of the reflected light is obtained. Using this light intensity value and the value of the scanning wavelength,
By performing the center-of-gravity calculation described above with reference to FIG. 12, the center wavelength or the wavelength shift amount of the reflected light of the focused FBG 15 can be obtained.

By the time series data measurement storage unit 28 and the calculation of the center of gravity of FIG. 12, physical quantity data for a plurality of FBGs 15 can be obtained only by the required number of wavelength scans.

The physical quantity measuring system 10 (10
A to 10E), the probe light is converted to FBG instead of multiple scans of the linear spectrum probe light.
The half-width of the reflection spectrum, or the wavelength width spectrum of the order of 1/10 width, makes it possible to calculate the effective FBG 15 from the light intensity measurement data for a plurality of wavelength values and the center of gravity calculation using the center wavelength of the probe light. The center reflection wavelength can be determined. This center of gravity operation can be calculated at least twice. Further, since the light intensity data is acquired not as a time gate but as time-series data, a delay time scan is unnecessary, and the FBG1 is scanned with only a very small number of wavelengths.
Since five wavelength centers can be obtained, simple and quick measurement can be performed.

Relative Ratio / Calibration Curve Next, similarly to FIG. 17, the signal processing control unit 17 includes a time-series data measurement storage unit 28 and a wavelength scanning unit 31, and the data processing unit 18 includes a wavelength measurement unit 30. However, an example in which the calculation method of the wavelength measurement unit 30 provided in the data processing unit 18 is different will be described.

The calculation method in the wavelength measuring section 30 is as follows.
The method is the same as the method shown in FIG. 13, and the individual FBG1s are obtained from the time-series data stored in the time-series data measurement storage unit 28.
5 is extracted and the reflection ratio of the FBG 15 of interest is determined using the relative ratios of the intensities of the individual FBG reflected light pulses belonging to the plurality of time series data and the calibration curve A stored in the data processing unit 18 in advance. This is a method of obtaining the center wavelength or the amount of wavelength shift of light.

The measuring system 10 (10A to 10F)
According to the above, the wavelength shift amount can be calculated for a plurality of FBGs 15 and 15 having the same wavelength of the reflected light but different delay times with a minimum number of scans of two time scans at a time.

The measuring system 10 (10A to 1A)
0F), it is assumed that the probe light is not a multiple scan of the linear spectrum of the probe light but a wavelength width spectrum of a half width of the reflection spectrum of the FBG 15 or a 1/10 width. The effective shift amount of the center reflection wavelength of the FBG 15 can be obtained from the calibration curve A and the ratio of the light intensity measurement data to the plurality of wavelength scan values. Furthermore, since light intensity data is acquired as time series data instead of time gates,
No delay time scanning is required, and F
Since the wavelength center of the BG 15 can be obtained, simple and quick measurement can be performed.

Time series data measurement storage unit, wavelength scanning unit, operation
Wavelength shift measuring section 18 in the optical fiber multi-point physical quantity measuring system including an optical switching unit 24 and the broadband light source 22 and the wavelength tunable filter 23 in the light source unit 11, the signal processing control unit 1
Reference numeral 7 denotes an optical fiber multipoint physical quantity measurement system 10F including a time-series data measurement storage unit 28 and a wavelength scanning unit 31, and a data processing unit 18 including a dynamic wavelength shift measurement unit 33.

The time series data measurement storage section 28 of the signal processing control section 17 of the physical quantity measurement system 10F measures and records the reflected light pulse trains from the plurality of FBGs 15 as time series data in synchronization with the switching timing of the optical switching section. The wavelength scanning unit 31 scans the wavelength tunable filter unit 23 with two or more wavelength center values using the light source unit 11 to obtain the time-series data, while the data processing unit 18
The dynamic wavelength shift measuring unit 33 performs measurement a plurality of times in a required time after fixing the wavelength, extracts the signal of each FBG 15 from these time series data, and outputs the individual signals belonging to the plurality of time series data. The relative ratio of the light intensity of the FBG reflected light pulse and the calibration curve A stored in the data processing unit 18 in advance.
The dynamic physical quantity can be favorably measured by obtaining time change information such as the central wavelength or the wavelength shift amount of the reflected light of the focused FBG 15 and the change cycle thereof using the above.

More specifically, the time-series data storage / measurement unit 28 of the signal processing control unit 17 synchronizes with the pulsing timing of the light source unit 11 to synchronize the wavelength band of the pulsed light returning from the section with a fixed delay time. And all the reflected pulse trains from the FBG 15 having the same reflected wavelength are collectively measured and stored in chronological order.

As in FIG. 14, when the light intensity and wavelength of the probe light are constant,
If the reflected wavelength spectrum is not shifted, a reflected pulse train that can always be regarded as having the same intensity is measured and stored. However, when the reflection wavelength from the FBG 15 changes (shifts), the intensity of the reflected light also changes, and the changing light intensity is stored as time-series data. On the other hand, the wavelength scanning unit 31 fixes the wavelength once, continuously collects the required time repeated data, and sets the individual FBG1s included in the time series data.
By extracting the signal component of No. 5, it becomes the same as the case described in FIG. This makes it possible to dynamically detect the wavelength change period for the plurality of FBGs 15 belonging to the specific reflection wavelength band.

In this measurement system 10F, a plurality of FBGs 15 having a plurality of the same basic reflection wavelengths are assumed on the assumption that the probe light is a half-width of the reflection spectrum of the FBG 15 or a wavelength width spectrum of the order of 1/10 width. The time change of the wavelength shift can be continuously tracked from the change in the amount of light, and a plurality of dynamic parameters of the change in the physical quantity can be measured from the cycle and the shift amount.

Measurement of Static / Dynamic Physical Quantity In the optical fiber multi-point physical quantity measurement system 10F in which the light source section 11 includes the broadband light source section 22, the wavelength variable filter section 23, and the optical switching section 21, the time series A configuration including a data storage / measurement unit 28, a wavelength scanning unit 31, and a dynamic wavelength shift measurement unit 33 for measuring a dynamic physical quantity, and a system 10 (10A) for measuring the static physical quantity described above.
10D) can be incorporated to form one measurement system.

The system 10 for measuring the above-mentioned static physical quantity
As (10A to 10D), a configuration in which the signal processing control unit 17 includes a time-series data measurement storage unit 28 and the data processing unit 18 includes a time-series data binary determination processing unit 29, or the signal processing control unit 17 includes a time-series data A configuration in which the data measurement storage unit 28 and the wavelength scanning unit 31 are provided, and the data processing unit 18 includes the wavelength measurement unit 30 is provided.

The static / dynamic physical quantity measuring system 10
In F, the measurement of the dynamic physical quantity is performed by fixing the scanning wavelength to a specific scanning wavelength and continuously acquiring the light intensity of the reflected pulse train from all the FBGs 15 of interest in time.
The wavelength shift period of the BG 15 is calculated, and the amount of the wavelength shift is calculated by performing wavelength scanning.

The procedure for calculating the light intensity and the wavelength shift makes it possible to obtain both the amount of the wavelength shift and the period thereof, and to measure the physical quantity itself that changes over time, such as vibration measurement. It can be used for both measurement of dynamic physical quantities and static steady-state physical quantities.
In addition, by measuring signals of a plurality of FBGs 15 collectively using time-series data, measurement time can be minimized.

Self-health monitoring This optical fiber multipoint physical quantity measurement system 10 (10A to 10A)
10F), as shown in FIG.
It is preferable to include a soundness monitoring unit 35 that monitors that all of the optical branching sections 2 and the optical branching section 13 are soundly connected without disconnection.

For example, at each end of the optical trunk section 12 and the optical branching section 14, there is provided a terminal reflecting means 36 for reflecting the light introduced from the light source section 11 by the reflecting means and returning the light to the light introducing side. By providing the soundness monitoring means 36 for measuring the reflected light from the terminal reflection means 36, the soundness and the change in transmission loss relating to the connection state of the optical trunk 12 and the optical branching path 14 are measured to monitor the soundness. can do.

The terminal reflection means 36 for the light introduced from the light source unit 11 includes at least one kind of light reflection means of Fresnel reflection, specular reflection, and irregular reflection reflection which do not change the wavelength of light.

FIG. 19 shows an example of the configuration of an optical fiber multipoint physical quantity measurement system 10G for soundness monitoring.

A physical quantity measuring system 10 shown in FIG.
In G, for example, a soundness monitoring unit 35 is provided in the data processing unit 18, and a terminal reflection unit 36 is attached to each terminal end of the optical branch path unit 14 and the optical trunk line unit 12.

Normally, the open end of an optical fiber causes Fresnel reflection, and in some cases, measures are taken to prevent this light from being reflected by the action of absorption, scattering, or the like. In the physical quantity measuring system 10G, the light reflected from the terminal reflecting means 36 is to be used.
The light from the end of the optical fiber is returned to the optical trunk section 12 and the light detection processing section 16 detects the light.

The light from the light source 11 is pulsed, and is introduced into the optical trunk 12 while undergoing wavelength scanning.
Regardless of the wavelength, if the optical trunk line section 12 and each of the optical branching sections 14 maintain a healthy connection state, the reflected light from the terminal reflecting means 36 has a known timing with respect to the pulse introduction timing. Detected after a delay time. Of course, when the optical trunk line section 12 is divided on the way, the signal from the tip of the optical branch path section 14 connected after the division point does not return. When only a specific optical branching section 14 is broken, only light from the terminal reflecting means 36 attached to the optical branching section 14 does not return. These series of determinations are made by the soundness monitoring means 35.

Further, the soundness monitoring means 35 pays attention not only to the presence or absence of the return of the reflected pulse but also to the aging and the aging of the light intensity of the reflected pulse. If the reflected pulse is returned but the light intensity is significantly reduced, the line 1
It is conceivable that there is a connection loss of the optical fiber 2 or 14, an abnormality of the optical branching unit (optical branching device) 13, or the like. In each section, since a plurality of signals pass through in an overlapping manner, the soundness itself of the optical fiber and the components connected thereto can be determined by a combination of comprehensive information.

According to the present invention, while the system is operating, it is possible to monitor online that the optical trunk line section and the optical branch path section are all properly connected without disconnection.

Optical Branch 1 in Self-Calibrating Optical Fiber Multipoint Physical Quantity Measurement System
The connection positions of the FBG 3 and the FBG 15 are known at the time of designing or laying the system, and it is a general method to register such position and length information in the system in advance. However, in this optical fiber multipoint physical quantity measurement system, calibration can be performed on the spot even if information on the connection position / distance of the connected FBG 15 or the reflected light wavelength is not given in advance. .

More specifically, light having a line width sufficiently smaller than the half-width of each FBG reflection spectrum is used as the light source of the light source section 11, and a range covering the reflection light wavelength band of all the connected FBGs 15 is used. A wavelength scanning unit 31 that introduces light into the optical trunk unit 12 while sequentially scanning wavelengths, a time-series data measurement storage unit 28 that measures and records time-series data of a reflected light pulse train with respect to a scanning wavelength, The basic reflected light wavelength of the FBG 15 is calculated from the scanning wavelength information,
A calibration calculation processing unit (not shown) that calculates connection position / distance information from delay time information of the detected light pulse extracted from the time series data and stores the result in the data processing unit 18; Can be calibrated.

In this optical fiber multipoint physical quantity measurement system, the time series data measurement storage unit 28 and the wavelength scanning unit 3
1 and a calibration calculation processing unit, and by performing only wavelength scanning, reflected pulses from all FBGs can be measured and recorded (FIG. 20). Regarding the reflected pulses from all the FBGs 15 acquired as the calibration calculation targets,
The delay time (position) and the basic reflection wavelength of the connected FBG 15 can be acquired from the corresponding wavelength and the delay time for the pulse light from the light source unit 11. Therefore,
By performing these search measurements after the installation and registering the obtained results in the system, "in-situ calibration" can be performed even when calibration information is not given in advance.

The calibration prompting to the actual installation state in the state after the system operation such as when a sensor or the like is newly added to the system in the installation state, not only when there is no connection condition of the FBG 15 before the installation. The value can be determined.

In the self-correcting optical fiber multipoint physical quantity measuring system 10H,
As shown in FIG. 21, it is preferable to provide a correction unit that can improve the accuracy and reliability of the data of the measurement system even in an environment in which fiber deterioration or the like occurs.

More specifically, the physical quantity to be measured is expressed as FBG1
5, a physical quantity transmission mechanism 38 for converting the temperature into a small strain or a temperature change, a physical quantity (a type and a change in strain) of an object to be measured and an FBG assigned to each FBG 15 in advance.
A calibration curve storage unit 39 that stores a calibration curve indicating a relationship with the wavelength shift amount of 15 and a continuously accumulated data,
Fiber degradation measurement unit 40 that calculates changes in transmission loss for each path due to aging degradation and degradation due to the environment (degradation due to heat, humidity, etc., radiation irradiation degradation, etc.), and calibration recorded in calibration curve storage unit 39 Conversion correction unit 4 that performs necessary correction when converting the physical quantity of the measurement target from the curve based on the transmission loss change value calculated by the fiber deterioration measurement unit 40.
By providing 1, the monitoring of measurement in which one or more physical quantities are mixed can be sufficiently performed, and the accuracy and reliability of data can be improved even under a severe environment.

FIG. 21 shows one physical quantity measurement system 10.
An example in which one or more physical quantities can be measured and monitored by H will be described. FIG.
The physical quantity measurement system 10H illustrated in FIG. 1 includes, for example, a fiber deterioration measurement unit 39, a conversion correction unit 41, and a calibration curve storage unit 39 in the data processing unit 18 in addition to the system 10 illustrated in FIG. In addition, a terminal reflecting means 36 is provided at the terminal such as the optical branching section 14.

Further, each FBG 15 is provided with a physical quantity transmission mechanism 38, a single type assigned to each FBG 15;
Alternatively, a mechanism for converting a plurality of types of measured physical quantities into minute distortion of the FBG 15 and causing a shift in the reflection wavelength of the FBG 15 is provided.

The calibration curve storage section 39 stores a calibration curve indicating the relationship between the wavelength shift amount of each FBG 15 and the physical quantity to be measured. Further, the fiber deterioration estimating unit 40 of the data processing unit 18 measures loss and wavelength change due to aging, deterioration of the optical fiber and the FBG 15 itself due to heat, radiation, and the like. The conversion correction unit 41 calculates a correction coefficient for each physical quantity conversion from the measured deterioration, and corrects the physical quantity calculated from the calibration curve stored in the calibration curve storage unit 39.

As a result, correct measurement information can be provided even in a system on the assumption that different types of physical quantities to be measured are mixed in the system 10H and deterioration of the optical fiber or the like occurs.

[0164]

According to the optical fiber multipoint physical quantity measuring system of the present invention, since connection can be made without being restricted by the wavelength constraint of the FBG, it is possible to connect many FBGs to one system.

In the present invention, the presence or absence of a change in the reflection wavelength of the FBG can be detected at a high speed by determining the change in the light intensity itself as a threshold value.

According to the present invention, the scanning condition of the two parameters of time and wavelength can be minimized, and the wavelength change can be measured efficiently.

In the present invention, the period of the wavelength change can be grasped by the dynamic wavelength shift measurement, so that the dynamically changing physical quantity itself such as vibration measurement can be measured. By having both the wavelength scanning and the wavelength change detection means, it is possible to achieve both static physical quantity measurement.

In the present invention, since the measurement system itself can have the functions of self-calibration, self-health monitoring, and self-correction, when the physical configuration conditions change, or when these configurations remain unchanged, It is possible to construct a measurement system that can continue normal measurement and operation even when the typical parameters and characteristics change.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of an optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 2 is an explanatory view showing an example in which a plurality of optical trunks are provided in the optical fiber multipoint physical quantity measuring system according to the present invention.

FIG. 3 is an explanatory diagram showing another example in which the optical fiber multipoint physical quantity measurement system according to the present invention includes a plurality of optical trunk lines.

FIG. 4 is an explanatory diagram showing an example of a branch interval in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 5 is an explanatory diagram showing another example of a branch interval in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 6 is an explanatory diagram of a light source unit used in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 7A is a diagram showing emission characteristics of a probe light output from a light source unit of the optical fiber multipoint physical quantity measurement system according to the present invention, and FIG. 7B is a pulse light generated by controlling the output probe light; FIG.

FIG. 8 is an explanatory diagram showing a relationship example between a data processing unit and a signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 9A is a view showing reflected pulses from each FBG and an FBG to be focused on in the optical fiber multipoint physical quantity measurement system according to the present invention.
7A and 7B are explanatory diagrams showing a relationship with a gate signal, and FIG. 7B is a diagram showing an example of a shift in a reflection wavelength of a focused FBG, and FIG. 7C is a diagram showing an example of an optical signal detected by a light detection processing unit.

FIG. 10 is an explanatory diagram showing another example of the relationship between the data processing unit and the signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 11 is an explanatory view showing still another example of the relationship between the data processing unit and the signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIGS. 12A and 12B are explanatory diagrams of calculation of a center wavelength by a center-of-gravity calculation showing a relationship between light intensity and scanning wavelength in the optical fiber multipoint physical quantity measurement system according to the present invention.

13 (a), (b) and (c) are diagrams illustrating the calculation of the wavelength shift amount by the ratio operation in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 14 is an explanatory diagram showing still another example of the relationship between the data processing unit and the signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 15 is a diagram showing still another example of the relationship between the data processing unit and the signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 16 is a diagram showing a measurement example of time-series data at a focused FBG wavelength.

FIG. 17 is a diagram showing still another example of the relationship between the data processing unit and the signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 18 is a diagram showing still another example of the relationship between the data processing unit and the signal processing control unit in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 19 is an explanatory diagram showing an example of self-health monitoring in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 20 is an explanatory diagram of self-calibration in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 21 is an explanatory diagram showing an example of self-correction in the optical fiber multipoint physical quantity measurement system according to the present invention.

FIG. 22 is an explanatory diagram showing a conventional physical quantity measurement system.

[Explanation of symbols]

10, 10A to 10H Optical fiber multi-point physical quantity measurement system 11 Light source unit 12 Optical trunk line unit (optical transmission unit) 13 Optical branch unit 14 Optical branch path unit (optical transmission unit) 15 FBG (optical fiber Bragg grating element) 16 light detection Processing unit 17 Signal processing control unit 18 Data processing unit 20 Optical switch 22 Broadband light source unit 23 Wavelength variable filter unit 24 Optical switching unit 25 Gate signal generation unit 26 Binary judgment processing unit 28 Time series data measurement storage unit 29 Time series data Binary judgment processing unit 30 Wavelength measurement unit 31 Wavelength scanning unit 33 Dynamic wavelength shift measurement unit 35 Soundness monitoring unit 36 Termination reflection unit 38 Physical quantity transmission mechanism 39 Calibration curve storage unit 40 Fiber degradation measurement unit 41 Conversion correction unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Sumida 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Hamakawasaki Plant (72) Inventor Mikio Izumi, No. 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 Inside the Toshiba Hamakawasaki Plant (72) Inventor Soichiro Morimoto 8 Shingsugitacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 2F073 AA22 AB01 BB06 BC04 CC02 CD11 CD24 DD05 FF08 FG01 FG02 FH03 FH07 FH17 FH20 2H038 AA12 AA34 BA27 5K002 AA01 AA03 BA04 BA05 BA06 BA21 FA01 GA03

Claims (12)

[Claims] 1. An optical fiber multi-point physical quantity measurement system in which a plurality of optical fiber Bragg grating elements (hereinafter, referred to as “FBGs”) for measuring physical quantities are connected by optical fibers. An optical trunk line for transmitting light and reflected light of the FBG; a plurality of optical branching units arranged in a row on the optical trunk line and branching measurement light from the optical trunk line; While transmitting the reflected light of
A plurality of FBGs having different wavelengths of reflected light are arranged in a row so that the wavelength of the reflected light becomes longer as the distance between the optical branching portion and the FBG becomes longer. A light detection processing unit that detects and processes reflected light from the FBG; a signal processing control unit that controls between the light source unit and the light detection processing unit; and a connection position or distance condition and reflection of all FBGs. An optical fiber multi-point physical quantity measurement system, comprising: a data processor for storing information relating to an optical wavelength and identifying and processing data of each FBG using the stored information at the time of signal processing. 2. A plurality of optical trunk lines are provided, and a plurality of optical trunk lines are directly connected to an output side of an optical branch unit connected to a position closest to the light source unit, or the plurality of optical trunk lines are closest to the light source unit. The optical fiber multipoint physical quantity according to claim 1, wherein an optical switch is interposed on the output side of the optical branch unit connected to the position, and a plurality of optical trunk lines are switchably connected to the output side of the optical switch. Measurement system. 3. A method according to claim 1, wherein the distance between the optical branching portions of the optical trunk line, the distance between the FBGs in the optical branching path, and the distance between the optical branching portion and the FBG closest to the optical branching portion are equalized. Item 3. The optical fiber multipoint physical quantity measurement system according to item 1 or 2. 4. The light according to claim 1, wherein a distance between the optical branching sections is longer than a distance between an FBG located farthest from the optical branching section in the optical branching path section and the optical branching section. Fiber multipoint physical quantity measurement system. 5. The light source unit includes a broadband light source unit that outputs continuous light, a wavelength tunable filter unit that can selectively transmit only an arbitrary wavelength band of the output continuous light, and a filtered light source unit. The optical fiber multipoint physical quantity measurement system according to any one of claims 1 to 4, further comprising: an optical switching unit configured to convert continuous light into pulsed light by intermittently turning light on and off. 6. The signal processing control section includes a gate signal generating section, and the data processing section includes a binary decision processing section, a wavelength measuring section, a binary decision processing section, a dynamic wavelength shift measuring section, and a wavelength measuring section. And a dynamic wavelength shift measuring unit. The gate signal generating unit generates a gate signal with a required delay time for the FBG of interest, and the optical signal is generated only while the gate signal is active. The detection processing unit has a function of detecting light, and the binary determination processing unit of the data processing unit is configured to detect reflected light from the FBG based on binary information indicating whether the light detection processing unit has detected a light pulse. Determine whether the wavelength has changed significantly, and the wavelength measurement unit determines the maximum intensity wavelength of the observed light or the center wavelength of the wavelength spectrum, the dynamic wavelength shift measurement unit, the above-mentioned time conditions, With the wavelength fixed The light intensity is continuously measured a plurality of times at a time, and the center wavelength or the wavelength shift of the reflected light of the FBG of interest using the relative ratio of the obtained light intensity and the calibration curve stored in the data processing unit in advance. 6. The optical fiber multipoint physical quantity measurement system according to claim 5, wherein time change information such as a quantity and a cycle of the change is obtained. 7. The gate signal generation unit, wherein the signal processing control unit includes a gate signal generation unit and a wavelength scanning unit, and the data processing unit includes at least one of a wavelength measurement unit and a dynamic wavelength shift measurement unit. The unit generates a gate signal with a required delay time for the FBG of interest, and has a function that the light detection processing unit detects light only while the gate signal is active. The wavelength tunable filter unit of the light source unit is scanned with two or more wavelength center values with respect to the time condition, and the wavelength measurement unit compares the intensity value of the reflected light pulse obtained by the light detection processing unit with each wavelength scan. The center wavelength or the wavelength shift amount of the reflected light is obtained by calculating the center of gravity using the value of the scanning wavelength, or the relative ratio of the intensity of the reflected light pulse obtained by the light detection processing unit to each wavelength scan and the data processing unit in advance Remember By using a calibration curve that is, attention to FB
The central wavelength or the amount of wavelength shift of the reflected light of G is obtained, and the dynamic wavelength shift measuring unit measures the light intensity continuously plural times in the required time after fixing the wavelength with respect to the above-mentioned time condition. Using the relative ratio of the obtained light intensity and the calibration curve stored in the data processing unit in advance, time change information such as the center wavelength or the wavelength shift amount of the reflected light of the focused FBG and the period of the change is obtained. The optical fiber multi-point physical quantity measurement system according to claim 5. 8. The signal processing control unit includes a time-series data measurement storage unit, and the data processing unit includes a time-series data binary determination processing unit, or a time-series data binary determination processing unit and a dynamic wavelength shift measurement unit. The time-series data measurement storage unit measures and records reflected light pulse trains from a plurality of FBGs as time-series data in synchronization with the switching timing of the optical switching unit, and the time-series data binary determination processing unit Then, the individual FBG signals are extracted from these time-series data to determine whether or not there is a reflected light pulse. The dynamic wavelength shift measuring unit fixes the wavelength and continuously performs a plurality of times in the required time. The light intensity is measured in advance, the individual FBG signals are extracted from the time series data, and the relative ratios of the light intensities of the individual FBG reflected light pulses belonging to the plurality of time series data and data processing are performed in advance. 6. The optical fiber multiplexing device according to claim 5, wherein the calibration curve stored in the section is used to determine the time change information such as the center wavelength or the wavelength shift amount of the reflected light of the FBG of interest and the period of the change. Point physical quantity measurement system. 9. The signal processing control unit includes a time-series data measurement storage unit and a wavelength scanning unit, and the data processing unit includes at least one of a wavelength measurement unit and a dynamic wavelength shift measurement unit. The data measurement storage unit measures and records the reflected light pulse trains from the plurality of FBGs as time-series data in synchronization with the switching timing of the optical switching unit. The wavelength scanning unit uses two sets of data to acquire the time-series data. The wavelength tunable filter section is scanned with the above wavelength center value, and the wavelength measuring section extracts individual FBG signals from these time series data and obtains the intensity of each FBG reflected light pulse belonging to a plurality of time series data. The center wavelength or the wavelength shift amount of the reflected light is obtained by the center of gravity calculation using the value and the value of the scanning wavelength, or the signal of each FBG is extracted from these time series data, Using the relative ratio of the intensities of the individual FBG reflected light pulses belonging to the number of time-series data and the calibration curve stored in advance in the data processing unit, the center wavelength or the wavelength shift amount of the reflected light of the focused FBG is obtained. The dynamic wavelength shift measurement unit measures the light intensity plural times continuously for a required time after fixing the wavelength, and as a result, extracts individual FBG signals from these time series data, Using the relative ratio of the light intensity of each FBG reflected light pulse belonging to the series data and the calibration curve stored in advance in the data processing unit,
6. The optical fiber multipoint physical quantity measurement system according to claim 5, wherein time change information such as a center wavelength or a wavelength shift amount of the reflected light of the focused FBG and a change cycle thereof is obtained. 10. The optical trunk line section and the optical branching path section each end portion,
A light reflected from the light source unit is reflected by the reflection unit as reflected light back to the light introduction side.The reflected light is used to determine changes in soundness and transmission loss relating to the connection state of the optical trunk line and the optical branching path. The optical fiber multipoint physical quantity measurement system according to any one of claims 1 to 9, wherein the data processing unit includes a health monitoring unit for performing measurement. 11. A light source having a line width sufficiently smaller than a half-width of an individual FBG reflection spectrum as a light source of a light source unit when information on a connection position / distance of a connected FBG and a reflected light wavelength is not given in advance. A wavelength scanning unit that introduces light into the optical trunk while sequentially scanning the wavelength in a range that covers the reflected light wavelength band of all connected FBGs, and measures time-series data of reflected light pulse trains with respect to the scanning wavelength. A time-series data measurement storage unit for recording and recording, and a basic reflected light wavelength of the FBG is calculated from the time-series data and the scanning wavelength information, and the connection position / The optical fiber multipoint physical quantity measurement system according to any one of claims 1 to 10, further comprising: a calibration calculation processing unit that calculates distance information and stores the result in a data processing unit. 12. A physical quantity transmission mechanism for converting a physical quantity to be measured into a minute strain or a temperature change with respect to the FBG, and a calibration curve showing a relationship between the physical quantity to be measured and the wavelength shift amount of the FBG, which are assigned to each FBG in advance. And a fiber degradation measurement unit that calculates a change in transmission loss for each path due to aging and environmental degradation from continuously accumulated data, and a calibration curve storage unit. A conversion correction unit that performs correction necessary when converting the physical quantity of the measurement target from the calibration curve based on the transmission loss change value calculated by the fiber deterioration measurement unit,
2. The monitoring of measurement in which one or more physical quantities are mixed.
12. The optical fiber multi-point physical quantity measurement system according to any one of claims 11 to 11.