JP3115163B2 - Temperature distribution detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature distribution detecting device for measuring a temperature distribution along a longitudinal direction of an optical fiber probe by using backscattered light in an optical fiber. The present invention relates to a temperature distribution detecting device capable of improving the temperature distribution detection accuracy by associating the position with an optical fiber probe.

[0002]

2. Description of the Related Art Conventionally, in the field of optical applied sensing, an optical fiber probe has been used as a device for measuring the temperature in the longitudinal direction by inputting an optical pulse into an optical fiber and detecting backscattered light due to the optical pulse. A temperature distribution detecting device that detects a temperature distribution along a longitudinal direction of the device is widely used.

FIG. 6 is a block diagram showing the configuration of this type of temperature distribution detecting device. In this temperature distribution detecting device, a pulse light generating device 1 for generating a pulse light signal transmits the pulse light signal through a directional coupler 2 to an optical fiber probe 3.
From the incident end. The optical fiber probe 3 has an optical fiber 4 with an extra length inside, and a pulsed optical signal traveling in the optical fiber 4 generates backscattered light at each position in the optical fiber 4.

[0004] Here, the backscattered light is generated by Raman scattering caused by the interaction between photons and the optical mode of molecular vibration of a substance, and has two different wavelengths from the pulse light signal traveling in the optical fiber 4. It consists of light. These two
The types of light are anti-Stokes light whose scattering intensity depends on temperature and Stokes light whose scattering intensity does not depend much on temperature.

[0005] Such backscattered light is incident on the optical filter 5 through the directional coupler 2, and the optical filter 5 separates the anti-Stokes light and the Stokes light from the backscattered light while the first and second lights are separated. The signal passes through the signal detection devices 6 and 7 individually.

[0006] The first optical signal detector 6 detects the anti-Stokes light and sends out a first intensity signal to the temperature converter 8, and the second optical signal detector 7 detects the Stokes light and outputs the second intensity signal. Is transmitted to the temperature converter 8. The pulse light generating device 1, the directional coupler 2, the optical filter 5, the first optical signal detecting device 6, the second optical signal detecting device 7, and the temperature calculating device constitute a temperature distribution measuring device 9. .

The temperature converter 8 calculates the intensity ratio between the anti-Stokes light and the Stokes light from the first and second intensity signals, and measures the temperature for each backscattered light using a function of the intensity ratio.

On the other hand, the distance from the optical pulse generator 1 to the position where the scattered light is generated is generally OTDR (Optical Time D).
omain Reflectometry). The OTDR is such that, assuming that the light flux in the optical fiber 4 is constant, the optical path length from the optical pulse generator 1 to the position where the backscattered light is generated is the time from the generation of the optical pulse signal to the detection of the backscattered light. Is proportional to the optical path length, so that the optical path length can be measured.

Therefore, the temperature conversion device 8 converts the backscattered light into the optical fiber probe 3 based on the reception time of the anti-Stokes light and the first and second intensity signals of the Stokes light.
The temperature distribution along the longitudinal direction of the optical fiber probe 3 is measured by converting the temperature to a position within the range and calculating the temperature as described above.

[0010]

However, in the above-described temperature distribution detecting apparatus, the optical fiber 4 in the optical fiber probe 3 is given a spare length in advance and is slightly slackened, so that it is detected by the OTDR. Since the optical path length in the optical fiber 4 is different from the length of the optical fiber probe 3, there is a problem that it is difficult to accurately determine the measurement position on the optical fiber probe 4.

On the other hand, from the viewpoint of solving this problem, even if the extra length of the optical fiber 4 is eliminated, the very thin optical fiber 4 is easily damaged by thermal expansion and contraction of the coating. It is difficult to eliminate the extra length.

Further, since the speed of light inside the optical fiber 4 depends on the temperature, there is a problem that if a high-temperature portion and a normal-temperature portion coexist in the optical path, an apparent error occurs in the optical path length.

This error depends on the material of the optical fiber 4,
Normally, the optical path length change in the communication optical fiber is 1
It is about 0 ^-5 . For example, if the temperature of the optical fiber is 10
If the temperature changes by 0 ° C., an error of about 1 m occurs 1000 m ahead.
For this reason, an optical path length error that cannot be ignored occurs particularly at the time of high-temperature measurement or when the temperature of the measurement target greatly changes.

The present invention has been made in view of the above-mentioned circumstances, and has been made to accurately correspond a temperature distribution in an optical fiber having an extra length to a temperature distribution on an optical fiber probe, thereby improving measurement accuracy of the temperature distribution. It is an object of the present invention to provide an apparatus for detecting a temperature distribution.

Another object of the present invention is to provide a temperature distribution detecting device capable of compensating for an optical path length error caused by the speed of light in an optical fiber depending on temperature and accurately detecting a temperature distribution at the time of measuring a high temperature. Is to provide.

[0016]

According to a first aspect of the present invention, an optical pulse signal is incident from an incident end to an optical fiber probe having an optical fiber having an extra length therein and transmitted through the optical fiber. In a temperature distribution detecting device that detects a backscattered light by the optical pulse signal and performs a predetermined calculation to measure a temperature distribution along a longitudinal direction of the optical fiber probe, a total length data in a longitudinal direction of the optical fiber probe is When the optical pulse signal is scattered by the end of the optical fiber, the optical path length along the longitudinal direction from the incident end to the end of the optical fiber is determined based on the optical pulse signal. An optical path length measuring means for measuring the optical path length measured by the optical path length measuring means and the total length data stored by the full length data storage means. An optical path length correction unit that performs a correction operation to compress the optical path length in accordance with the full length data, and a temperature distribution along a longitudinal direction of the optical fiber probe based on a calculation result by the optical path length correction unit. The temperature distribution detecting device includes a temperature distribution calculating means for calculating.

According to a second aspect of the present invention, there is provided an optical fiber probe having an optical fiber having an extra length therein, the optical pulse signal being incident from an incident end of the optical fiber probe, and transmitted through the optical fiber. In a temperature distribution detection device that detects a backscattered light by performing a predetermined calculation and measures a temperature distribution along a longitudinal direction of the optical fiber probe, the optical fiber probe provided with a plurality of markers, A marker optical path length storage unit in which optical path length data of the optical fiber at the marker position is stored for each marker on the fiber probe; and the respective marker positions based on the optical path length data stored by the marker optical path length storage unit. And a marker temperature distribution calculating means for calculating a temperature distribution corresponding to the temperature distribution.

Further, according to a third aspect of the present invention, there is provided an optical fiber probe having an optical fiber having an extra length therein, the optical pulse signal being incident from an incident end of the optical fiber probe, and transmitted through the optical fiber. In the temperature distribution detection device that detects the backscattered light by performing a predetermined calculation and measures the temperature distribution along the longitudinal direction of the optical fiber probe, temperature-dependent information of the light velocity in the optical fiber is stored. Light speed / temperature information storage means;
The optical path length of the optical fiber is corrected based on the temperature-dependent information stored by the temperature information storage unit, and the temperature distribution is calibrated along the longitudinal direction of the optical fiber probe so as to correspond to the corrected optical path length. It is a temperature distribution detecting device provided with temperature distribution calibrating means.

[0019]

Therefore, in the invention corresponding to claim 1, by taking the above means, the full length data storage means stores the full length data in the longitudinal direction of the optical fiber probe.
When the optical pulse signal is scattered by the end of the optical fiber, the optical path length measuring means measures the optical path length along the longitudinal direction from the incident end to the end of the optical fiber based on the optical pulse signal, and corrects the optical path length. The means corrects the optical path length based on the optical path length measured by the optical path length measuring means and the full length data stored by the full length data storage means so as to compress the optical path length in correspondence with the full length data, and calculates the temperature distribution. In the means, the temperature distribution along the longitudinal direction of the optical fiber probe is calculated based on the calculation result by the optical path length correcting means, so that the temperature distribution in the optical fiber having the extra length is calculated as the temperature distribution on the optical fiber probe. And the accuracy of measuring the temperature distribution can be improved.

According to a second aspect of the present invention, a plurality of markers are previously attached to the optical fiber probe, and the marker optical path length storage means stores, for each marker on the optical fiber probe, the optical path length data of the optical fiber at the marker position. Is stored, and the marker temperature distribution calculating means calculates the temperature distribution corresponding to each marker position based on the optical path length data stored by the marker optical path length storing means. Measurement accuracy can be improved.

Further, according to a third aspect of the present invention, there is provided a light speed / temperature information storage means for storing temperature dependency information of a light speed in an optical fiber, and the temperature distribution calibrating means comprises the light speed / temperature information storage means. The optical path length of the optical fiber is corrected based on the temperature-dependent information stored in the optical fiber probe, and the temperature distribution is calibrated along the longitudinal direction of the optical fiber probe so as to correspond to the corrected optical path length. The optical path length error caused by the speed depending on the temperature can be compensated, and the temperature distribution at the time of measuring the high temperature can be accurately detected.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a temperature distribution detecting apparatus according to a first embodiment of the present invention. The same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. Only mentioned.

That is, in the apparatus of this embodiment, the temperature distribution data in the optical fiber 4 is made to correspond to the temperature distribution data on the optical fiber probe 3. On the other hand, full length data storage unit 1
1, a distance conversion device 15 including an optical path length measurement unit 12, an optical path length correction unit 13, and a temperature distribution calculation unit 14 is added.

Here, the full length data storage section 11 stores full length data indicating the total length of the optical fiber probe 3 in the longitudinal direction. When the scattering of the optical pulse signal at the end of the optical fiber is detected, the optical path length measuring unit 12 measures the optical path length along the longitudinal direction from the incident end to the end of the optical fiber based on the optical pulse signal. This is sent to the optical path length correction unit 13.

The optical path length correction section 13 is provided with the optical path length measurement section 1.
Based on the optical path length measured in Step 2 and the full length data stored in the full length data storage unit 11, a correction operation is performed so that the optical path length is compressed in correspondence with the full length data, and the calculation result is converted into a temperature distribution calculation unit 14 To be sent.

The temperature distribution calculator 14 calculates the optical fiber probe 3 based on the calculation result of the optical path length corrector 13.
Is calculated and output.

Next, the operation of the temperature distribution detecting device thus configured will be described. First, the optical fiber probe 3
Is measured by the measurer and then attached to the object to be measured. The full length data indicating the total length is stored in the full length data storage unit 11 by an input unit (not shown).

Subsequently, as described above, the apparatus of the present embodiment
The temperature distribution along the optical path is measured in the same manner as in the related art by the backscattered light generated in the optical fiber 4 by inputting the optical pulse signal into the optical fiber 4.

Next, the optical path length measuring unit 12 obtains the optical path length from the start end to the end position of the optical fiber 4 based on the scattered light intensity in the optical fiber 4. Here, as shown in FIG. 2, the intensity of the scattered light is detected because the optical pulse signal is scattered at the end position of the optical fiber 4, and the optical pulse signal propagates at a position farther from the end position of the optical fiber 4. No backscattered light is detected. Therefore, the terminal position can be easily determined, and the optical path length measurement unit 12 calculates the optical path length up to the terminal position of the optical fiber 4 based on the scattered light intensity, and outputs the optical path length data as the calculation result. It is sent to the length correction unit 13.

Upon receiving the optical path length data, the optical path length correction section 13 reads out the full length data from the full length data storage section 11, and
The optical path length data and the full length data are compared. As described above, since the optical fiber 4 has an extra length in the optical fiber probe 3, the optical path length data is longer than the full length data. Thus, the optical path length correction unit 13 performs the following conversion based on the optical path length data up to the end of the optical fiber 4 and the total length data.

At the beginning of the optical fiber 4, both the optical path length and the total length are zero and coincide, and at the end, the optical path length data and the full length data differ by the extra length. Therefore, assuming that the surplus length of the optical fiber 4 is uniformly distributed over the entire optical fiber probe 3, the measurement data at the start and end in the optical fiber 4 is converted into the measurement data at the start and end on the optical fiber probe 3. Based on the optical path length at the intermediate point between the start and end points, the measurement position on the optical fiber probe 3 corresponding to this optical path length is corrected and calculated.

That is, when there is the optical fiber probe 3 having the optical path length data C (m) and the total length data L (m), the optical fiber probe 3 corresponding to C1 (m) on the optical path from the start end.
The upper measurement position x (m) is obtained by the following equation (1).

From C: L = C 1: x, x = C 1 · L / C (1) Therefore, the temperature distribution calculating unit 14 converts the temperature distribution on the optical path into the temperature distribution on the optical fiber probe 3. , Cn are multiplied by (full length data L / optical path length data C), respectively, so that the temperature data corresponding to the optical path lengths C1, C2,. It is converted into temperature data corresponding to the measurement positions x1, x2,..., Xn on the probe.

For example, the measurement position x on the optical fiber probe corresponding to the optical path length data 1010 (m) and the total length data 1000 (m) and corresponding to 505 (m) on the optical path is expressed by the following equation (2). .

X = 505 × 1000/1010 (2) = 500 (m) Next, the temperature distribution calculation unit 14 calculates the temperature data 20 ° C. on the optical path 505 (m) from the measurement position x on the optical fiber probe 3. To 20 ° C.

Hereinafter, similarly, the temperature distribution calculating section 14 calculates the temperature distribution along the longitudinal direction of the optical fiber probe 4. As described above, according to the first embodiment, the entire length data in the longitudinal direction of the optical fiber probe 3 is stored in the entire length data storage unit 11, and the optical pulse signal at the end of the optical fiber probe 3 is stored in the optical path length measurement unit 12. Is reflected, the optical path length along the longitudinal direction of the optical fiber 4 from the incident end to the end of the optical fiber probe 3 is measured based on the optical pulse signal, and the optical path length correction unit 13 Optical path length and total length data storage unit 1 measured by 12
1, the optical path length is corrected so as to be compressed so as to correspond to the full length data, and the temperature distribution calculating section 14 calculates the optical fiber probe based on the calculation result by the optical path length correcting section 13. Since the temperature distribution along the longitudinal direction of the optical fiber 3 is calculated, the temperature distribution in the optical fiber 4 having the extra length accurately corresponds to the temperature distribution on the optical fiber probe 3, thereby improving the accuracy of measuring the temperature distribution. Can be.

Next, a temperature distribution detecting device according to a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of this temperature distribution detecting device. The same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. Only different parts will be described here.

That is, the apparatus according to the present embodiment employs the optical fiber 4
Even if the surplus length is not uniformly distributed over the entire optical fiber probe 3, the temperature distribution data in the optical fiber 4 is made to correspond to the temperature distribution data on the optical fiber probe 3, and specifically, Has a configuration in which a plurality of identification markers 3 a are attached to the optical fiber probe 3, and a distance conversion unit 23 including a marker optical path length storage unit 21 and a marker temperature distribution calculation unit 22 is added to the temperature conversion device 8.

Here, the marker optical path length storage section 21 stores optical path length data indicating the optical path length in the optical fiber 4 corresponding to each marker position for each identification marker 3a on the optical fiber probe 3. is there.

The marker temperature distribution calculation section 22 calculates a temperature distribution corresponding to each marker position based on the optical path length data stored in the marker optical path length storage section 21. Next, the operation of the temperature distribution detecting device thus configured will be described.

At this time, an identification marker 3a for position identification is attached to the optical fiber probe 3 before attachment by a measurer at regular intervals. Thereafter, calibration data indicating the relationship between the position of the identification marker 3a and the optical path length of the optical fiber probe 3 is obtained, and the calibration data is stored in the marker optical path length storage unit 21.

In order to obtain the calibration data, first,
The position of the identification marker 3a is locally heated and the temperature distribution is measured in the same manner as in the related art, to obtain a temperature distribution in which only a certain portion has a high-temperature portion as shown in FIG. The optical path length corresponding to the high temperature portion is longer than the optical fiber probe length from the start end to the marker position due to the extra length of the optical fiber 4. The correspondence between the optical path length and the probe length at this marker position is calibration data.

After obtaining the calibration data, the optical fiber probe 3 is attached to the object to be measured, and the temperature distribution is measured as in the conventional case. Thereafter, as described above, the temperature converter 8 obtains the conventional temperature distribution corresponding to the optical path length of the optical fiber 4.

Next, when the conventional temperature distribution is obtained from the temperature conversion unit 8, the marker temperature distribution calculation unit 22 reads the calibration data from the marker optical path length storage unit 21 and also obtains the temperature data on the conventional temperature distribution. The optical path length of the optical fiber 4 is made to correspond to the marker position, and the conventional temperature distribution is converted into a calibrated temperature distribution corresponding to each marker position. Note that the measurement points that are not on the calibration data are approximately obtained by interpolation or extrapolation.

As described above, according to the second embodiment, the identification marker 3a is attached to the optical fiber probe 3 in advance, and the marker optical path length storage unit 21 stores the marker 3a on the optical fiber probe 3 for each marker 3a. Since the optical path length data of the optical fiber 4 is stored and the marker temperature calculating section 22 calculates the temperature distribution corresponding to each marker position based on the optical path length data stored in the marker optical path length storing section 21, the first In addition to the effects of the embodiment, the measurement accuracy of the temperature distribution can be further improved.

That is, in the first embodiment, the optical fiber 4
Assuming that the extra length is uniformly distributed, the case where the temperature distribution corresponding to the optical path length in the optical fiber 4 is compressed to the temperature distribution corresponding to the entire length of the optical fiber probe 3 has been described. However, the length of the optical fiber 4 may be non-uniform depending on the state at the time of manufacture. For example, when there is almost no extra length from the start point to the intermediate point and there is much extra length from the intermediate point to the end point, an error occurs near the intermediate point when the temperature distribution is obtained as in the first embodiment. On the other hand, in the second embodiment, since the temperature distribution is calibrated in accordance with the marker position provided on the optical fiber probe 3, even if the surplus length is non-uniform, it is possible to cope with the non-uniform surplus length. And the temperature distribution can be measured.

According to the second embodiment, even if the optical fiber probe 3 is attached to a complicated shape, the temperature distribution corresponding to the shape can be easily measured, and an unexpected situation can be urgently avoided. can do.

That is, since the optical fiber probe 3 usually having a total length of 1 km or more is wound around a bobbin during manufacturing or working, it is difficult to accurately measure the total length. Further, since the optical fiber probe 3 is usually attached in a complicated shape, it is also difficult to measure the total length and the length in the middle after the attachment. Therefore, such an optical fiber probe 3 has the following problems. For example, it is assumed that the optical fiber probe 3 is attached to an industrial plant having a complicated shape and the temperature distribution is measured, and a certain point indicates an abnormal temperature. At this time, although the optical path length indicating the abnormal temperature and the corresponding distance on the optical fiber probe 3 are known, as described above, the optical fiber probe 3 is attached in a complicated shape, and it is difficult to measure the length. For this reason, there is a problem that the distance indicating the abnormality and the attached location on the industrial plant cannot be corresponded, and it is difficult to specify the position indicating the abnormal temperature.

According to the second embodiment, even with respect to this problem, according to the temperature distribution corresponding to each marker position, the attachment location is recorded in advance for each marker position after the optical fiber probe 3 is attached. In addition, it is possible to easily specify an abnormal position on the attachment, and to quickly respond to the abnormality.

Next, a temperature distribution detecting device according to a third embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of the temperature distribution detecting device. The same parts as those in FIG. 6 are denoted by the same reference numerals, detailed description thereof will be omitted, and only different parts will be described here.

That is, in the present embodiment, the temperature distribution is accurately measured by compensating for the temperature dependence of the light velocity in the optical fiber 4. Specifically, the apparent optical path length change due to temperature Is added to the temperature conversion device 8 in order to correct the distance. A distance correction device 33 including a light speed / temperature information storage unit 31 and a distance conversion unit 32 is added.

Here, the light speed / temperature information storage section 31 stores information on the temperature dependency of the light speed in the optical fiber 4. As the temperature dependence information of the light speed, a relational expression or a table showing the temperature dependence of the light speed can be used. In this case, when the light speed is v and the temperature is T, v (T) The known temperature dependent function shown is used.

The distance conversion section 32 performs an optical path conversion on the basis of the temperature dependence of the light velocity stored in the light velocity / temperature information storage section 31 with respect to the temperature distribution corresponding to the optical path length of the optical fiber obtained by the temperature conversion device 8. The length is corrected, and a temperature distribution based on the corrected optical path length is created.

Next, the operation of such a temperature distribution detecting device will be described. Now, it is assumed that the temperature converter 8 measures the conventional temperature distribution corresponding to the optical path length of the optical fiber 4 as described above. Note that this temperature distribution is represented by a set {(X′i, T′i), i = 1,..., N} of the position X′i and the temperature T′i.
It is expressed as

Subsequently, the distance conversion unit 32 performs the calculations shown in the following equations (3) and (4) from i = 1 to N on the conventional temperature distribution, X _i
Ask for. Xo = X'o ... (3) X i = X i-1 + (X 'i -X' i-1) · (v (T 'i) / v B) ... (4) where, v _B the reference The speed of light at temperature TB, v
(T _B ).

Thereafter, based on the calculation results of the equations (3) and (4), the distance conversion section 32 calculates the corrected temperature distribution as a set 位置 (X _i , T _i) of the position X _i and the temperature T′i. 'I), i =
1,..., N}, and outputs the corrected temperature distribution.

As described above, according to the third embodiment, the light speed / temperature information storage unit 31 storing the temperature dependent function v (T) of the light speed in the optical fiber 4 is provided. . Thus calibrate the temperature distribution so as to correspond to the measurement point position X _i after correction by correcting each measurement point position X _'i of the optical fiber 4 on the basis of the function v (T), the optical fiber It is possible to compensate for an optical path length error caused by the speed of light in 4 being dependent on temperature, and to accurately detect a temperature distribution at the time of high temperature measurement.

In the second embodiment, the case where the identification marker 3a is attached to the optical fiber probe 3 has been described. However, the present invention is not limited to this case. Even if it is used, the present invention can be similarly implemented to obtain the same effect.

In the second embodiment, the case where the identification marker 3a is locally heated has been described. However, the present invention is not limited to this case. For example, the case where the optical fiber is bent at the marker position to increase the optical attenuation is also described. The present invention can be similarly implemented to obtain the same effect.

Further, in the above-described second embodiment, the case where the certain identification marker 3a is locally heated has been described. However, the present invention is not limited to this, and the optical fiber may be coupled by a directional coupler or fusion. Even if a change in light intensity at a portion is used instead of a marker, the present invention can be implemented in the same manner and a similar effect can be obtained.

In the second embodiment, the optical fiber probe 3 is attached to the object to be measured after the calibration data is obtained by attaching the identification marker 3a. However, the present invention is not limited to this. On the other hand, even if a marker is provided or a marker position is calibrated, the same effect can be obtained by implementing the present invention in the same manner.

Further, in the third embodiment, the case where the equation (4) is used has been described. However, the present invention is not limited to this.
Even if the following equation (5) is used instead of the equation (4), the present invention can be implemented in the same manner and the same effect can be obtained. X _i = X _i−1 + (X ′ _i −X ′ _i−1 ) · (v (T ′ _i ) + v (T ′ _i−1 )) / v _B ) (5) In the third embodiment, the case where the present invention is implemented separately has been described. However, the present invention is not limited to this, and the present invention can be implemented in the same manner and the same effect can be obtained even if the configuration is implemented by combining two or more. it can. For example, when the second embodiment and the third embodiment are combined, it is possible to specify a position by a marker in a wide temperature range, which is optimal for temperature distribution measurement in a high-temperature plant or the like. In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[0063]

As described above, according to the present invention, the total length data storage means for storing the total length data in the longitudinal direction of the optical fiber probe is provided, and the optical pulse length is measured by the optical path length measuring means. When the signal is reflected, the optical path length along the longitudinal direction of the optical fiber from the incident end to the end of the optical fiber probe is measured based on the optical pulse signal, and the optical path length is corrected by the optical path length measuring means and measured by the optical path length measuring means Based on the calculated optical path length and the total length data stored by the total length data storage means, the optical path length is corrected so as to be compressed in correspondence with the full length data. The temperature distribution along the longitudinal direction of the optical fiber probe is calculated based on the temperature distribution. Precisely in correspondence to the temperature distribution on Ibapurobu can provide a temperature distribution detecting apparatus capable of improving the measurement accuracy of the temperature distribution.

Further, according to the present invention, there is provided a light speed / temperature information storage means for storing the temperature dependency information of the light speed in the optical fiber, and the light speed / temperature information storage means stores the light speed / temperature information storage means. The optical path length of the optical fiber is corrected based on the temperature-dependent information, and the temperature distribution is calibrated along the longitudinal direction of the optical fiber probe so as to correspond to the corrected optical path length. It is possible to provide a temperature distribution detecting device capable of compensating for an optical path length error caused by the speed depending on the temperature and accurately detecting a temperature distribution at the time of measuring a high temperature.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a temperature distribution detecting device according to a first embodiment of the present invention.

FIG. 2 is a view for explaining measurement of an optical path length in the embodiment.

FIG. 3 is a block diagram showing a configuration of a temperature distribution detecting device according to a second embodiment of the present invention.

FIG. 4 is a view for explaining measurement of a marker position in the embodiment.

FIG. 5 is a block diagram showing a configuration of a temperature distribution detecting device according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional temperature distribution detecting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pulse light generator, 2 ... Directional coupler, 3 ... Optical fiber probe, 4 ... Optical fiber, 5 ... Optical filter, 6 ...
First optical signal detection device, 7... Second optical signal detection device, 8
... temperature conversion device, 11 ... full length data storage unit, 12 ... optical path length measurement unit, 13 ... optical path length correction unit, 14 ... temperature distribution calculation unit, 21 ... marker optical path length storage unit, 22 ... marker temperature distribution calculation unit, 31 ... light speed / temperature information storage unit, 32 ... distance conversion unit.

Claims (3)

(57) [Claims] 1. An optical fiber probe having an extra length of an optical fiber inside, an optical pulse signal is incident from an incident end thereof, and backscattered light by the optical pulse signal transmitted through the optical fiber is detected to determine a predetermined value. In the temperature distribution detecting device for measuring the temperature distribution along the longitudinal direction of the optical fiber probe, a full length data storage means in which the full length data of the optical fiber probe in the longitudinal direction is stored, When the optical pulse signal is scattered by the end, based on the optical pulse signal, an optical path length measuring means for measuring the optical path length along the longitudinal direction from the incident end of the optical fiber to the end, and the optical path length measurement Based on the optical path length measured by the means and the full length data stored by the full length data storage means, the optical path length is made to correspond to the full length data. And a temperature distribution calculating means for calculating a temperature distribution along a longitudinal direction of the optical fiber probe based on a calculation result by the optical path length correcting means. A temperature distribution detecting device characterized by the above-mentioned. 2. An optical fiber probe having an extra length of optical fiber therein is provided with an optical pulse signal from an incident end thereof, and a backscattered light by the optical pulse signal transmitted through the optical fiber is detected to detect a predetermined amount of backscattered light. In the temperature distribution detecting device for calculating the temperature distribution along the longitudinal direction of the optical fiber probe, the optical fiber probe provided with a plurality of markers, the marker for each marker on the optical fiber probe Marker optical path length storage means for storing optical path length data of the optical fiber at a position, and a marker for calculating a temperature distribution corresponding to each of the marker positions based on the optical path length data stored by the marker optical path length storage means A temperature distribution detecting device comprising: a temperature distribution calculating unit. 3. An optical fiber probe having an extra length of optical fiber inside, an optical pulse signal is incident from an incident end thereof, and backscattered light by the optical pulse signal propagating through the optical fiber is detected to determine a predetermined value. A temperature distribution along the longitudinal direction of the optical fiber probe, and a temperature / velocity information storage unit in which temperature-dependent information of a light velocity in the optical fiber is stored; The optical path length of the optical fiber is corrected based on the temperature-dependent information stored by the light speed / temperature information storage unit, and the temperature distribution is adjusted along the longitudinal direction of the optical fiber probe so as to correspond to the corrected optical path length. A temperature distribution detecting device, comprising: temperature distribution calibrating means for calibrating.