JP2015222225A - Device for measuring distribution type temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for measuring a distribution type temperature, excellent in spatial resolution.SOLUTION: A method for measuring a distribution type temperature comprises: extracting a temperature change point at which a temperature along an optical fiber rapidly changes; using only information on a first temperature distribution outputted by first output means about points except the extracted temperature change point; and combining the temperature distributions by using information on a second temperature distribution outputted by second output means about the temperature change point.

Description

  The present invention relates to a distributed temperature measuring device that uses an optical fiber as a sensor and calculates a temperature distribution along the optical fiber from the intensity ratio of the intensity of anti-Stokes light and stokes light of backward Raman scattered light.

  A type of temperature measuring device using an optical fiber as a sensor, a distributed temperature measuring device configured to measure a temperature distribution along the optical fiber (for example, a device disclosed in Japanese Patent Laid-Open No. 2012-27001) There is. This technique uses backscattered light generated in an optical fiber.

  Backscattered light includes Rayleigh scattered light, Brillouin scattered light, and Raman scattered light, but temperature-dependent back Raman scattered light is used for temperature measurement. Measure. The back Raman scattered light includes anti-Stokes light AS generated on the short wavelength side with respect to the wavelength of incident light and Stokes light ST generated on the long wavelength side.

  The distributed temperature measuring device using an optical fiber measures the intensity Ias of the anti-Stokes light and the intensity Ist of the stosk light, calculates the temperature from the intensity ratio, and displays the temperature distribution along the optical fiber. It is used in fields such as temperature management of plant equipment, investigation and research related to disaster prevention, and air conditioning related to power plants and large buildings.

  Such distributed temperature measurement devices using back Raman scattered light are divided into a one-way measurement method in which an optical pulse is incident only from one side of the optical fiber and a bidirectional measurement method in which an optical pulse is incident from both sides of the optical fiber. Broadly divided.

  In the case of the one-way measurement method, the temperature measurement value is not constant depending on the measurement position, even at the same temperature due to the effect of the transmission loss difference of the optical fiber due to the wavelength difference between the Stokes light and the anti-Stokes light. On the other hand, in the bidirectional measurement method disclosed in Japanese Patent Application Laid-Open No. 2013-92388 and the like, the transmission loss difference of the optical fiber is automatically increased by combining the results measured from both the Stokes light and the anti-Stokes light. And the error based on the measurement position is greatly suppressed.

  Because of such advantages, temperature measurement using a bidirectional measurement method has become mainstream in temperature measurement in petroleum plants and the like.

JP 2012-27001 A JP 2013-92388 A

  However, when the bidirectional measurement method is used, there is a problem that it is not possible to avoid deterioration of spatial resolution due to dispersion during optical fiber transmission. Dispersion mainly includes chromatic dispersion and mode dispersion. In a distributed temperature measuring device using an optical fiber, a multimode fiber having a high generation efficiency of Raman scattered light is often used instead of a single mode fiber used in optical communication. When this multimode fiber is used, deterioration of the optical pulse mainly due to the effect of mode dispersion becomes a problem regardless of the one-way measurement method or the two-way measurement method. The influence of this dispersion becomes more prominent as the fiber length increases and becomes a factor of deteriorating the spatial resolution indicating one of the performances of the distributed temperature measuring device.

  An object of the present invention is to provide a distributed temperature measuring device having excellent spatial resolution.

The distributed temperature measuring device of the present invention uses an optical fiber as a sensor, and calculates the temperature distribution along the optical fiber from the intensity ratio of the intensity of anti-Stokes light and the intensity of stokes light of backward Raman scattered light. In the measurement device, an optical fiber arranged to reciprocate around the turning point, and a first calculation means for calculating the intensity ratio along the optical fiber by measurement from one end side from the optical fiber, Second calculation means for calculating the intensity ratio along the optical fiber by measurement from the other end side from the optical fiber, and calculation results obtained by the first calculation means and the second calculation means. A first output means for outputting first temperature distribution information along the optical fiber using a bidirectional measurement method based on both; the first calculation means; A second output means for outputting second temperature distribution information along the optical fiber using a one-way measurement method based on one of the calculation results obtained by the calculating means; and a temperature along the optical fiber is rapidly increased. And using only the first temperature distribution information output by the first output means for points other than the temperature change point extracted by the extraction means, and extracting means for extracting the temperature change point that changes to The temperature change point includes synthesis means for synthesizing a temperature distribution by using the second temperature distribution information output by the second output means.
According to this distributed temperature measuring apparatus, only the first temperature distribution information is used for points other than the temperature change point, and the second temperature distribution information is used for the temperature change point to synthesize the temperature distribution. Therefore, it is possible to maintain the fiber loss difference canceling effect, which is an advantage of the bidirectional measurement method, while improving the spatial resolution at the temperature change point.

  The synthesizing unit may synthesize the temperature distribution in such a form that the spatial resolution of the second temperature distribution information output from the second output unit is maintained for the temperature change point.

  For the temperature change point, the synthesizing unit obtains a change width ratio between the anti-Stokes light intensity and the stosk light intensity between different measurement positions from the second temperature distribution information output from the second output unit. The temperature distribution about the temperature change point may be obtained by calculating and using the change width ratio.

The distributed temperature measurement method of the present invention uses an optical fiber as a sensor, and calculates a temperature distribution along the optical fiber from the intensity ratio of the intensity of anti-Stokes light and the intensity of stokes light of backward Raman scattered light. In the measurement method, a first calculation step of calculating the intensity ratio along the optical fiber by using an optical fiber arranged so as to reciprocate around the turning point and measuring from one end side from the optical fiber; , A second calculation step for calculating the intensity ratio along the optical fiber by measurement from the other end side from the optical fiber, and a calculation result obtained by the first calculation step and the second calculation step A first output step of outputting first temperature distribution information along the optical fiber using a bidirectional measurement method based on A second output step of outputting second temperature distribution information along the optical fiber using a one-way measurement method based on one of the calculation step or the calculation result obtained in the second calculation step; An extraction step for extracting a temperature change point at which the temperature along the fiber abruptly changes, and the first temperature output by the first output step for points other than the temperature change point extracted by the extraction step A synthesis step of synthesizing a temperature distribution by using only the distribution information and using the second temperature distribution information output by the second output step for the temperature change point. To do.
According to this distributed temperature measurement method, only the first temperature distribution information is used for points other than the temperature change point, and the temperature distribution is synthesized by using the second temperature distribution information for the temperature change point. Therefore, it is possible to maintain the fiber loss difference canceling effect, which is an advantage of the bidirectional measurement method, while improving the spatial resolution at the temperature change point.

  According to the distributed temperature measuring apparatus of the present invention, only the first temperature distribution information is used for points other than the temperature change point, and the second temperature distribution information is used for the temperature change point. Therefore, it is possible to maintain the fiber loss difference canceling effect, which is an advantage of the bidirectional measurement method, while improving the spatial resolution at the temperature change point.

  Further, according to the distributed temperature measuring method of the present invention, only the first temperature distribution information is used for points other than the temperature change point, and the second temperature distribution information is used for the temperature change point, Since the temperature distribution is synthesized, it is possible to maintain the fiber loss difference canceling effect, which is an advantage of the bidirectional measurement method, while improving the spatial resolution at the temperature change point.

The figure which shows the structure of a distributed temperature measuring apparatus. The block diagram which shows the structure of a temperature distribution measurement part. Flow chart showing operation of temperature distribution measurement unit The figure which shows the relationship between the optical fiber full length m and the measurement position X. FIG. The figure which shows the example which contrasted the measurement result in the distributed temperature measuring apparatus of this invention, and the measurement result by the conventional bidirectional | two-way measurement system.

  Hereinafter, an embodiment of a distributed temperature measuring device of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a distributed temperature measuring apparatus according to the present embodiment.

  As shown in FIG. 1, the distributed temperature measuring apparatus of the present embodiment combines a temperature distribution measuring unit 1, an optical fiber FB connected to the temperature distribution measuring unit 1, a temperature distribution measuring unit 1 and an optical fiber FB. And an optical switch 3 for performing.

  The temperature distribution measurement unit 1 receives backward Raman scattered light (Stokes light and anti-Stokes light) generated in the optical fiber FB, and measures the temperature distribution in the length direction of the optical fiber FB (R-OTDR). ). As the optical fiber FB, for example, a silica-based multimode optical fiber having a length of about several kilometers to several tens of kilometers can be used. A single mode optical fiber may be used.

  The optical fiber FB functions as a bidirectional fiber by connecting the front end and the rear end to the temperature distribution measuring unit 1 via the optical switch 3. By switching the optical switch 3 to either channel A (front end) or channel B (rear end), either the front end or the rear end of the fiber FB and the temperature distribution measuring unit 1 are selectively connected. Thereby, the temperature distribution of the optical fiber FB can be bidirectionally measured.

  The optical fiber FB is arranged so as to reciprocate through substantially the same temperature measurement point with the center of the optical fiber FB as a turning point P.

  The front and rear ends of the optical fiber FB are connected to the optical switch 3, but the optical fiber extends from the optical switch 3 to the inside of the temperature distribution measuring unit 1. Here, the optical fiber FB arranged in a loop shape with the optical switch 3 as the base end functions as a bidirectional fiber.

  FIG. 2 is a block diagram showing a configuration of the temperature distribution measuring unit 1.

  As shown in FIG. 2, the temperature distribution measurement unit 1 includes a pulse generation unit 11 that controls timing for generating a light pulse, a light source 12 that emits a light pulse, and a directional coupler 13 that controls the direction of light. An optical filter 14 that receives light from the directional coupler 13, a pair of photoelectric converters 15a and 15b that convert the light amount into a voltage value or a current value, and a photoelectric converter 15a and a photoelectric converter 15b. A pair of amplifier circuits 16a and 16b for amplifying the outputs, respectively, an A / D converter circuit 17a and an A / D converter circuit 17b for converting analog signals output from the amplifier circuits 16a and 16b into digital signals, respectively An averaging circuit 18 that averages sampling data output from the A / D conversion circuit 17a and the A / D conversion circuit 17b; 18, a calculation unit 19 that calculates the temperature distribution of the optical fiber FB based on the output from the temperature 18, a temperature reference unit 21 that gives the internal temperature of the temperature distribution measurement unit 1, and a connector CN for detachably connecting the optical fiber And comprising.

  Next, the function of each element provided in the temperature distribution measurement unit 1 will be described.

  The pulse generator 11 outputs a pulse signal that defines timing for generating pulsed light from the light source 12 and timing for operating the averaging circuit 18. The light source 12 includes a semiconductor laser, for example, and emits a pulsed laser beam at a timing when a pulse signal is output from the pulse generator 11. The wave number of laser light emitted from the light source 12 is k0. The directional coupler 13 is configured so that the laser light emitted from the light source 12 is guided to the temperature reference unit 21 and the backscattered light generated in the optical fiber FB is guided to the optical filter 14. The unit 21 and the optical filter 14 are optically coupled.

  The temperature reference unit 21 includes a wound optical fiber 21a and a temperature sensor 21b, and is used to obtain the temperature (reference temperature) inside the temperature distribution measurement unit 1. The optical fiber 21a is an optical fiber having an overall length of about several tens to several hundreds of meters, one end of which is optically coupled to the directional coupler 13 and the other end of which is optically coupled to the connector CN. The temperature sensor 21b includes, for example, a platinum resistance thermometer and measures the temperature near the optical fiber 21b. The measurement result of the temperature sensor 21 b is output to the calculation unit 19.

  The optical filter 14 extracts backward Raman scattered light (Stokes light ST and anti-Stokes light AS) included in the backscattered light from the directional coupler 13 and separates and outputs the Stokes light ST and the anti-Stokes light AS. It is a filter to do. When the Raman shift (wave number) generated in the optical fiber FB is kr, the wave number of the Stokes light ST is represented by k0-kr, and the wave number of the anti-Stokes light AS is represented by k0 + kr.

  The photoelectric conversion circuits 15a and 15b include light receiving elements such as avalanche photodiodes, and photoelectrically convert Stokes light ST and anti-Stokes light AS output from the optical filter 14, respectively. The amplifier circuits 16a and 16b amplify the photoelectric conversion signals output from the photoelectric conversion circuits 15a and 15b, respectively, with a predetermined amplification factor.

  The A / D conversion circuits 17a and 17b sample the photoelectric conversion signals amplified by the amplification circuits 16a and 16b, and output digitized sampling data. These A / D conversion circuits 17a and 17b have samplings set at regular intervals (for example, 1 m intervals) in the longitudinal direction of the optical fiber FB, with the position of the optical switch 3 (the outlets of the channels A and B) as the origin. The operation timing is set so as to sample the photoelectric conversion signal of the backward Raman scattered light (Stokes light ST and anti-Stokes light AS) generated at the point.

  The averaging circuit 18 operates in accordance with the pulse signal from the pulse generation unit 11 and is provided with an A / D conversion circuit 17a, which is obtained each time the laser light emitted from the light source 12 is incident on the optical fiber FB. The sampling data of 17b is averaged individually. Since the backward Raman scattered light (Stokes light ST and anti-Stokes light AS) generated in the optical fiber FB is weak, the sampling data obtained by making the laser light incident on the optical fiber FB multiple times is averaged. Thus, a desired signal-to-noise ratio (S / N ratio) is obtained.

  The calculation unit 19 performs calculation for obtaining the intensity ratio for each sampling point using the sampling data of the Stokes light ST and the anti-Stokes light AS averaged by the averaging circuit 18 while referring to the measurement result of the temperature sensor 21b. Do. With this calculation, the temperature at each sampling point is obtained, and thereby the temperature distribution in the length direction of the optical fiber FB is obtained. Note that the calculation unit 19 corrects the temperature distribution based on the measurement result of a temperature sensor (not shown) that measures the temperature of a specific part of the optical fiber FB.

  Next, the principle of temperature distribution measurement will be described. When the signal intensity of Stokes light and anti-Stokes light is expressed as a function of time with reference to the light emission timing in the light source 1, the speed of light in the optical fiber FB is known, so that the optical switch 3 is used as a reference along the optical fiber FB. Can be replaced by a function of the distance. That is, the horizontal axis can be regarded as the distance, and the intensity of Stokes light and anti-Stokes light generated at each distance point of the optical fiber, that is, the distance distribution.

  On the other hand, the anti-Stokes light intensity Ias and the Stokes light intensity Ist both depend on the temperature of the optical fiber FB, and the intensity ratio Ias / Ist of both lights also depends on the temperature of the optical fiber FB. Therefore, if the intensity ratio Ias / Ist is known, the temperature at the location where the Raman scattered light is generated can be known. Here, since the intensity ratio Ias / Ist is a function Ias (x) / Ist (x) of the distance x, the temperature distribution T (x along the optical fiber FB from the intensity ratio Ias (x) / Ist (x). ).

  Next, the operation of the distributed temperature measuring device of this embodiment will be described.

  FIG. 3 is a flowchart showing the operation of the distributed temperature measuring apparatus of the present embodiment.

  In step S1 of FIG. 3, the temperature distribution measurement unit 1 is operated with the optical switch 3 set to channel A and channel B, respectively, and forward measurement (FIG. 1 (a)) in which an optical pulse is incident from the channel A and A reverse direction measurement (FIG. 1B) in which an optical pulse is incident from channel B is performed. Thereby, data of the anti-Stokes light intensity Ias and the Stokes light intensity Ist in the forward direction measurement and the reverse direction measurement is acquired.

  Next, in step S2, the temperature distribution is calculated by the bidirectional measuring method in the calculation unit 19 using the data acquired in step S1. Equation (1) indicates the intensity ratio G (X) of the anti-Stokes light intensity Ias and the Stokes light intensity Ist obtained by the bidirectional measurement method. Here, X is an integer of 0 to m indicating the measurement position, m is the total length of the optical fiber FB, and X is the measurement position.

  FIG. 4 is a diagram showing the relationship between m and X. The measurement position X corresponds to the distance from the outlet of channel A, and the measurement position X is at a distance m−X from the outlet of channel B. The turning point P corresponds to the measurement position X = m / 2.

  Next, in step S3, the calculation unit 19 extracts a temperature change point that is a point where the temperature changes rapidly based on the data acquired in step S1. A specific method for extracting the temperature change point will be described later.

  Next, in step S4, with respect to the temperature change point extracted in step S2, in the calculation unit 19, the intensity Ias and intensity Ist shown in the expression (2.1) or (2.2) between the adjacent measurement positions. The change width ratio D (X) is calculated. The change width ratio D (X) is a parameter that can be regarded as equivalent to the differential value dG (X) / dX if the interval between the measurement positions is sufficiently small. The formula (2.1) is adopted for the measurement position X (X ≦ m / 2) close to the channel A with the turning point P as a boundary. Further, the equation (2.2) is adopted for the measurement position X (X ≧ m / 2) close to the channel B with the turning point P as a boundary. In formula (2.1) or formula (2.2), X-1 represents a measurement position one before X (close to channel A).

  In step S5, the calculation unit 19 calculates a final intensity ratio G (X) using the temperature distribution calculated in step S2 and D (X) calculated in step S4. Specifically, for positions other than the temperature change point extracted in step S3, the intensity ratio G (X) obtained by the bidirectional measurement method calculated in step S2 is employed. On the other hand, for the temperature change point extracted in step S3, the intensity ratio G (X) is calculated using D (X) calculated in step S4. In step S5, these intensity ratios G (X) are combined to obtain a temperature distribution over the entire length of the optical fiber FB.

  The expression (3) indicates the intensity ratio G (X) expressed using D (X) calculated by the expression (2.1) or the expression (2.2).

  As shown in equation (3), the intensity ratio G (X) can be obtained sequentially by adding D (X) to the intensity ratio G (X-1) at the immediately preceding measurement position.

  As described above, this embodiment is characterized in that a one-way measurement method using only data closer to the outlet of channel A or the outlet of channel B is used at the temperature change point.

  By the way, in FIG. 1A, the shapes of the optical pulses 41a, 41b, 41c, and 41d that enter the channel A and travel through the optical fiber FB are formed. In FIG. The shapes of the optical pulses 42a, 42b, 42c, and 42d traveling through the optical fiber FB are schematically shown. As described above, the shapes of the optical pulses 41a, 41b, 41c, 41d, 42a, 42b, 42c, and 42d are degraded as the distance traveled through the optical fiber FB is increased, resulting in degradation of spatial resolution. However, in the present embodiment, the one-way measurement method using only the data about the position close to the switch 3 is applied at the temperature change point caused by the presence of the heat source, etc., except for the temperature change point obtained by the bidirectional measurement method. Since the interpolation is performed so as to be continuous with the intensity ratio G (X), the spatial resolution at the temperature change point can be improved.

  FIG. 5 is a diagram showing an example in which the measurement result in the distributed temperature measurement device of the present invention is compared with the measurement result by the conventional bidirectional measurement method. FIG. 5 is a graph showing the measurement position X on the horizontal axis and the intensity ratio G (X) on the vertical axis. The solid line 51 is an example of the measurement result in the distributed temperature measuring device of the present invention, and the dotted line 52 is the conventional one. Examples of measurement results by the bidirectional measurement method are shown respectively.

  As shown in FIG. 5, according to the distributed temperature measuring device of the present invention, a rapid temperature change at the temperature change point is measured more accurately, and the spatial resolution is improved as compared with the conventional bidirectional measurement method. I know that. According to the distributed temperature measuring apparatus of the present invention, the spatial resolution is greatly improved particularly at a point where the distance from the temperature distribution measuring unit 1 to the switch 3 is short, that is, at a point close to the outlet of channel A or the outlet of channel B. It becomes possible.

  In the conventional bidirectional measurement method, for example, even if the distance from the temperature distribution measurement unit 1 is close in the forward direction, the measurement result from the reverse direction, which is a long distance, is always taken into account. There is a problem that the measurement result from the reverse direction, which is substantially a long distance, becomes dominant and high spatial resolution cannot be obtained. On the other hand, according to the present invention, the spatial resolution in the unidirectional measurement at a shorter distance can be utilized as it is, so that the spatial resolution at a point where the distance from the temperature distribution measuring unit 1 is close is greatly improved. Is possible.

  Next, a specific method for extracting a temperature change point in step S3 (FIG. 3) will be described.

  The temperature change point can be extracted using D (X) calculated by the equation (2.1) or (2.2). For example, when the absolute value of D (X) is larger than a predetermined threshold value, the point can be regarded as a temperature change point, and G (X) can be calculated using equation (3). In this case, the threshold value can be changed according to the measurement position X in consideration of the noise in the one-way measurement method and the fact that the spatial resolution itself changes depending on the measurement position X.

  In addition, when D (X) is larger than a predetermined threshold at a specific measurement position X, the point before and after that point is regarded as a temperature change point, and G (X) is calculated using equation (3). Can be calculated. In this case, G (X) is calculated in a chain using the equation (3) in the section regarded as the temperature change point, and the spatial resolution can be increased in the entire section.

  In addition, since the measurement position X and the measurement position m-X are substantially the same as the temperature measurement point, for example, when X ≦ m / 2, the measurement position X and the measurement position m-X are measured by a one-way measurement method using a light pulse in the forward direction. The temperature change point is extracted using both D (X) at the measurement position X and D (m-X) at the measurement position m-X measured by the one-way measurement method using the light pulse in the reverse direction. Also good. In this case, for example, the absolute value of the average value of D (X) and D (m−X) may be compared with a threshold value, or the absolute value of either D (X) or D (m−X) may be compared. When the value exceeds the threshold value, it may be regarded as a temperature change point.

  In extracting the temperature change point, the temperature distribution obtained by the bidirectional method in step S2 can be used. In this case, a portion where the temperature distribution obtained by the bidirectional method changes rapidly can be extracted by some algorithm, and this portion can be regarded as a temperature change point.

  As described above, according to the distributed temperature measuring apparatus of the present invention, the temperature measurement is adopted by the bidirectional measurement method except for the temperature change point, and the temperature measurement by the bidirectional measurement method is performed by the one-way measurement method at the temperature change point. Interpolated. For this reason, the distributed temperature measuring device of the present invention can maintain the fiber loss difference canceling effect, which is an advantage of the bidirectional measurement method, while improving the spatial resolution at the temperature change point.

  Further, in the distributed temperature measuring apparatus of the present invention, the system configuration of the apparatus based on the conventional bidirectional measurement method can be used as it is, and the distributed temperature measuring apparatus of the present invention is configured by changing only the software algorithm. can do.

  In the distributed temperature measuring apparatus of the present invention, the spatial resolution takes the worst value at the turning point. Considering the case of an optical fiber length of 30 km as an example, the worst value of the spatial resolution in the distributed temperature measuring device of the present invention is almost equivalent to the spatial resolution at a 15 km point in the one-way measurement method. That is, with respect to the optical fiber length of 30 km, the influence of dispersion can be suppressed to 15 km equivalent to the intermediate point.

  As described above, a multimode fiber is often used as the optical fiber of the distributed temperature measuring device, but the present invention can also be applied to different types of optical fibers such as a single mode fiber. Although mode dispersion does not occur in a single mode fiber, spatial resolution can be degraded by chromatic dispersion at longer distances. In the present invention, it is possible to suppress the degradation of spatial resolution in the bidirectional measurement method regardless of the types such as chromatic dispersion and mode dispersion.

  In the above embodiment, the calculation unit 19 calculates the intensity ratio of the Stokes light ST and the anti-Stokes light AS for each sampling point, but after calculating the respective intensities of the Stokes light ST and the anti-Stokes light AS separately, Finally, the light intensity ratio may be obtained.

  Various methods are known, such as a method using two types of light sources in the bi-directional measurement method, but in either method, the point of measuring the temperature by injecting light pulses from both ends of the optical fiber remains the same. In addition, the present invention can be applied.

  The scope of application of the present invention is not limited to the above embodiment. The present invention uses an optical fiber as a sensor, for a distributed temperature measuring device that calculates the temperature distribution along the optical fiber from the intensity ratio of the intensity of anti-Stokes light and the intensity of stokes light of backward Raman scattered light, etc. Can be widely applied.

1 temperature distribution measurement unit 19 calculation unit (first calculation means, second calculation means, first output means, second output means, extraction means, synthesis means)
FB optical fiber

Claims (4)

In a distributed temperature measuring device that uses an optical fiber as a sensor and calculates a temperature distribution along the optical fiber from the intensity ratio of the intensity of anti-Stokes light and the intensity of stokes light of back Raman scattered light,
An optical fiber arranged to reciprocate around the turning point; and
First calculating means for calculating the intensity ratio along the optical fiber by measurement from one end side from the optical fiber;
Second calculating means for calculating the intensity ratio along the optical fiber by measurement from the other end side from the optical fiber;
First output means for outputting first temperature distribution information along the optical fiber using a bidirectional measurement method based on both the calculation results obtained by the first calculation means and the second calculation means. When,
Second output means for outputting second temperature distribution information along the optical fiber using a one-way measurement method based on one of the calculation results obtained by the first calculation means or the second calculation means. When,
Extraction means for extracting a temperature change point at which the temperature along the optical fiber changes rapidly;
For the points other than the temperature change point extracted by the extraction means, only the first temperature distribution information output by the first output means is used, and for the temperature change point, the second output means. A synthesis means for synthesizing the temperature distribution by using the output second temperature distribution information;
A distributed temperature measuring device comprising:   The said synthesis | combination means synthesize | combines temperature distribution in the form in which the spatial resolution of the said 2nd temperature distribution information output from the 2nd output means is maintained about the said temperature change point. The distributed temperature measuring device described.   For the temperature change point, the synthesizing unit obtains a change width ratio between the anti-Stokes light intensity and the stosk light intensity between different measurement positions from the second temperature distribution information output from the second output unit. 3. The distributed temperature measuring apparatus according to claim 1, wherein the temperature distribution for the temperature change point is obtained by calculating and using the change width ratio. In the distributed temperature measurement method for calculating the temperature distribution along the optical fiber from the intensity ratio of the intensity of the anti-Stokes light and the intensity of the stosk light using the optical fiber as a sensor,
Using an optical fiber arranged to reciprocate around the turning point,
A first calculation step of calculating the intensity ratio along the optical fiber by measurement from one end side from the optical fiber;
A second calculation step of calculating the intensity ratio along the optical fiber by measurement from the other end side from the optical fiber;
A first output step of outputting first temperature distribution information along the optical fiber using a bidirectional measurement method based on both of the calculation results obtained by the first calculation step and the second calculation step. When,
A second output step of outputting second temperature distribution information along the optical fiber using a one-way measurement method based on one of the calculation results obtained by the first calculation step or the second calculation step. When,
An extraction step for extracting a temperature change point at which the temperature along the optical fiber changes abruptly;
For points other than the temperature change point extracted by the extraction step, only the first temperature distribution information output by the first output step is used, and for the temperature change point by the second output step. A synthesis step of synthesizing a temperature distribution by using the output second temperature distribution information;
A distributed temperature measurement method comprising:

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