Temperature monitoring system and monitoring method based on optical fiber interferometer

Abstract

The invention relates to the technical field of optical fiber interferometer temperature monitoring, and discloses an optical fiber interferometer-based temperature monitoring system, which comprises an optical fiber temperature sensing probe, a light source, an optical fiber coupler, a detector and a signal processing unit, the output end of the optical fiber temperature sensing probe is connected with the detector, and the output end of the detector is connected with the signal processing unit through a line. According to the optical fiber temperature sensor probe, the single-mode optical fiber and the multi-mode optical fiber are combined to serve as main components of the optical fiber sensor probe, an inter-mode interference structure is formed, the temperature measurement resolution of the optical fiber temperature sensor probe formed by combining the single-mode optical fiber and the multi-mode optical fiber can reach 0.0002 DEG C, the temperature measurement sensitivity can reach 3022 nm / DEG C, and the optical fiber temperature sensor probe can be used for measuring the temperature. Tiny temperature changes can be detected, then actual temperature changes in the environment are deduced by measuring interference fringes, and the system has the advantages of being high in response speed, good in stability, high in anti-interference capacity and high in precision.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic interferometer temperature monitoring, and in particular to a fiber optic interferometer-based temperature monitoring system and a monitoring method. Background Art

[0002] At present, the commonly used methods for monitoring the temperature of electric arc furnace transformers are mainly traditional temperature measuring instruments and infrared thermal imaging technology. Traditional temperature measuring instruments need to contact the transformer, which has disadvantages such as difficult installation, inaccurate temperature measurement, and susceptibility to interference. For example, when using a winding temperature indicator (WTI), the probe is installed on the top layer of the oil tank, which is far away from the winding. Since heat transfer takes time, this method has a certain lag, ranging from about 15-20 minutes, and cannot reflect the real temperature of the winding online in real time. Infrared thermal imaging technology can achieve non-contact temperature measurement, but it requires manual regular inspections and cannot achieve real-time online monitoring. In addition, data processing and analysis rely on manual experience, making it difficult to achieve intelligent early warning.

[0003] Based on the above background, it is urgent to establish a signal detection system based on fiber optic interferometer, which can obtain the output signal of fiber optic temperature sensor in real time, extract temperature information through digital signal processing technology, and perform temperature calibration and compensation. Improve the measurement performance of fiber optic temperature sensor to adapt to the harsh environment of submerged arc furnace. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a temperature monitoring system and a monitoring method based on an optical fiber interferometer, which have the advantages of being able to obtain the output signal of an optical fiber temperature sensor in real time, extract temperature information through digital signal processing technology, and perform temperature calibration and compensation, thereby solving the problems in the background technology.

[0006] (II) Technical solution

[0007] In order to achieve the above-mentioned purpose of being able to obtain the output signal of the optical fiber temperature sensor in real time, extracting the temperature information through digital signal processing technology, and performing temperature calibration and compensation, the present invention provides the following technical solutions: a temperature monitoring system based on an optical fiber interferometer, comprising an optical fiber temperature sensing probe, a light source, an optical fiber coupler, a detector and a signal processing unit, wherein the optical fiber temperature sensing probe is connected to the light source through the optical fiber coupler, and the output end of the optical fiber temperature sensing probe is connected to the detector, and the output end of the detector is connected to the signal processing unit through a line;

[0008] The optical fiber temperature sensing probe comprises a single-mode optical fiber, a multi-mode optical fiber and a housing, wherein the single-mode optical fiber and the multi-mode optical fiber are connected by fusion splicing, and the single-mode optical fiber and the multi-mode optical fiber are fusion spliced ​​and packaged inside the housing;

[0009] The signal processing unit includes an acquisition module, an analysis module, a temperature calibration module and an output module. The acquisition module is connected to the output end of the detector, the analysis module processes the information collected by the acquisition module in real time, and the analysis module is connected to the temperature calibration module, and the temperature calibration module is connected to the output module.

[0010] Preferably, the core diameter of the single-mode optical fiber is 8.5-9.5 μm, the core diameter of the multi-mode optical fiber is 50 μm-62.5 μm, and the temperature for fusing the single-mode optical fiber with the multi-mode optical fiber is 1600°C.

[0011] Preferably, the light source is a laser diode or a superluminescent diode, the detector is a photodiode, an avalanche photodiode or a photomultiplier tube, and the detector is used to receive the optical signal of the optical fiber temperature sensor probe.

[0012] Preferably, the wavelength emitted by the light source is 1550 nanometers.

[0013] Preferably, the acquisition module is used to acquire the electrical signal output by the detector, and the acquisition module converts the acquired electrical signal into interference fringes.

[0014] Preferably, the analysis module is connected to the acquisition module, and the analysis module calculates the movement amount of the interference fringes, and the formula is as follows:

[0015]

[0016] Where Δφ is the movement of the interference fringes, λ is the wavelength of the light source, Δn is the change in the refractive index of the optical fiber, and L is the total length of the single-mode fiber and the multimode fiber after fusion.

[0017] Preferably, the temperature calibration module is used to receive the interference fringe movement amount calculated by the analysis module, and derive the temperature change according to the interference fringe movement amount, and the derivation formula is as follows:

[0018]

[0019] Where ΔT is the temperature change, λ is the wavelength of the light source, n is the refractive index of the optical fiber, and Δφ is the movement of the interference fringes.

[0020] Preferably, the output module is used to output the temperature value calculated by the temperature calibration module and store the temperature value.

[0021] The present invention also provides a temperature monitoring method based on a fiber optic interferometer, which is performed according to the following steps:

[0022] S1, the light source emits light with a wavelength of 1550 nanometers and transmits it to the optical fiber temperature sensor probe through the optical fiber coupler;

[0023] S2. When light passes through the optical fiber temperature sensor probe, it is affected by temperature and produces interference, and then is received by the detector to convert the optical signal into an electrical signal;

[0024] S3, the acquisition module collects the electrical signal output by the detector and converts it into interference fringes;

[0025] S4, the analysis module processes the interference fringe information collected by the acquisition module in real time, and calculates the movement amount of the interference fringe using formula 1;

[0026] S5, the temperature calibration module calculates the temperature change according to the interference fringe movement calculated by the analysis module using Formula 2, and then compensates for the actual temperature;

[0027] S6. The output module outputs the actual temperature value and saves it.

[0028] Compared with the prior art, the present invention provides a temperature monitoring system and monitoring method based on optical fiber interferometer, which has the following beneficial effects:

[0029] The present invention provides a temperature monitoring system and a monitoring method based on an optical fiber interferometer. By combining single-mode optical fiber and multi-mode optical fiber as the main components of an optical fiber sensor probe, an inter-mode interference structure is formed. The optical fiber temperature sensor probe formed by the combination of single-mode optical fiber and multi-mode optical fiber has a temperature measurement resolution of up to 0.0002°C and a temperature measurement sensitivity of up to 3022nm / °C. It can detect tiny temperature changes and then deduce actual temperature changes in the environment by measuring interference fringes. It has the advantages of fast response speed, good stability, strong anti-interference ability and high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention; DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1, a temperature monitoring system based on fiber optic interferometer, including a fiber optic temperature sensing probe, a light source, a fiber optic coupler, a detector and a signal processing unit, the fiber optic temperature sensing probe is connected to the light source through the fiber optic coupler, and the output end of the fiber optic temperature sensing probe is connected to the detector, and the output end of the detector is connected to the signal processing unit through a line;

[0033] The optical fiber temperature sensor probe includes a single-mode optical fiber, a multi-mode optical fiber and a housing. The single-mode optical fiber and the multi-mode optical fiber are connected by fusion splicing, and the single-mode optical fiber and the multi-mode optical fiber are fusion spliced ​​and encapsulated inside the housing.

[0034] The signal processing unit includes an acquisition module, an analysis module, a temperature calibration module and an output module. The acquisition module is connected to the output end of the detector, the analysis module processes the information collected by the acquisition module in real time, and the analysis module is connected to the temperature calibration module, and the temperature calibration module is connected to the output module.

[0035] Specifically, the core diameter of single-mode optical fiber is 8.5-9.5μm, the core diameter of multi-mode optical fiber is 50μm-62.5μm, and the temperature for fusing single-mode optical fiber and multi-mode optical fiber is 1600℃. The advantage is that when making the optical fiber temperature sensor probe, single-mode optical fiber with a core diameter between 8.5-9.5μm and multi-mode optical fiber with a core diameter between 50μm-62.5μm are selected, and then a section of single-mode optical fiber and multi-mode optical fiber can be fused together by setting the temperature of the fusion machine at 1600℃ and the advancing speed at 20μm / s; after the fusion is completed, the fusion point needs to be tested, and the fusion loss of the actual link test can be lower than 3.5dB to ensure that its strength and transmission efficiency meet the requirements; through the fusion of single-mode optical fiber and multi-mode optical fiber, an inter-mode interference structure can be formed, which is very sensitive to temperature changes and can achieve high-precision temperature measurement.

[0036] Specifically, the light source is a laser diode or a superluminescent diode, the detector is a photodiode, an avalanche photodiode or a photomultiplier tube, and the detector is used to receive the optical signal of the optical fiber temperature sensor probe. The advantage is that the temperature measurement resolution of the optical fiber temperature sensor probe formed by the combination of single-mode optical fiber and multimode optical fiber can reach 0.0002°C, and the temperature measurement sensitivity can reach 3022nm / °C, which can detect small temperature changes. Since the laser diode or superluminescent diode has the characteristics of high brightness, narrow bandwidth and good directivity, it can provide a strong optical signal to ensure the sensitivity of monitoring, which is conducive to improving the purity and stability of the signal. The use of high-quality laser diodes or superluminescent diodes as light sources can ensure the stability and accuracy of the signal; at the same time, the use of photodiodes, avalanche photodiodes or photomultipliers as detectors can accurately detect the optical signal emitted by the optical fiber temperature sensor probe, even if the optical signal changes caused by temperature changes are very small, they can be captured, and can timely follow the temperature changes to generate corresponding electrical signal outputs, with good real-time performance.

[0037] Specifically, the wavelength emitted by the light source is 1550 nanometers. The advantage is that the wavelength of 1550 nanometers is the central wavelength of the C band commonly used in optical fiber communication. The optical fiber loss in this band is relatively low, which is conducive to long-distance transmission of signals. In addition, the light source in the 1550 nanometer band has a strong anti-interference ability in the transmission of optical fibers, especially in a high-temperature environment, which can reduce the interference caused by high temperature, thereby reducing signal attenuation and distortion, and ensuring the accuracy of the measurement results.

[0038] Specifically, the acquisition module is used to collect the electrical signal output by the detector, and the acquisition module converts the collected electrical signal into interference fringes. The advantage is that since single-mode optical fiber can support single-mode light propagation, and multi-mode optical fiber allows multiple modes to propagate simultaneously, when light enters multi-mode optical fiber from single-mode optical fiber, different modes will propagate at different speeds, causing them to produce phase differences at the output end. The optical signal emitted by the optical fiber temperature sensor probe is detected by the detector and converted into an electrical signal, and the acquisition module analyzes the electrical signal output by the detector to obtain interference fringes, and then the temperature change is derived by calculating the movement of the interference fringes.

[0039] Specifically, the analysis module is connected to the acquisition module, and the analysis module calculates the movement amount of the interference fringes, and the formula is as follows:

[0040]

[0041] Where Δφ is the movement of the interference fringes, λ is the wavelength of the light source, Δn is the change in the refractive index of the optical fiber, and L is the total length of the single-mode optical fiber and the multi-mode optical fiber after fusion. The advantage is that the movement of the interference fringes can be calculated according to Formula 1 through the wavelength of the light source, the change in the refractive index of the optical fiber, and the total length of the single-mode optical fiber and the multi-mode optical fiber after fusion. The temperature field distribution can be calculated by calculating the movement of the interference fringes, which can significantly improve the measurement accuracy. The interference fringes are very sensitive to the detection of temperature changes, because even a small temperature change can cause a change in the propagation characteristics of the light wave, thereby producing a detectable movement in the interference pattern.

[0042] Specifically, the temperature calibration module is used to receive the interference fringe movement calculated by the analysis module, and derive the temperature change according to the interference fringe movement. The derivation formula is as follows:

[0043]

[0044] Among them, ΔT is the temperature change, λ is the wavelength of the light source, n is the refractive index of the optical fiber, and Δφ is the movement of the interference fringes. The advantage is that the basic principle of Formula 2 utilizes the interference phenomenon of light and the temperature sensitivity of the optical fiber. When the temperature changes, the refractive index of the optical fiber will change, resulting in the movement of the interference fringes. By measuring the movement of the interference fringes, the temperature change can be inferred. The temperature change is calculated by Formula 2 to deduce the difference between the actual temperature, and then temperature compensation is performed to obtain the actual temperature value. The temperature calibration module can adjust the calibration parameters according to different environments and requirements, so that the system can adapt to various complex application scenarios. Through accurate temperature calibration, it can ensure that the output temperature data is consistent with the actual temperature and reduce errors.

[0045] Specifically, the output module is used to output the temperature value calculated by the temperature calibration module and store the temperature value. The advantage is that the actual temperature value in the environment is derived by the temperature calibration module and then sent to the output module. The output module displays the actual temperature value in the environment through a terminal device such as a large screen or a display, and saves the temperature value for user inspection.

[0046] The present invention provides a temperature monitoring method based on optical fiber interferometer, which is carried out according to the following steps:

[0047] S1, the light source emits light with a wavelength of 1550 nanometers and transmits it to the optical fiber temperature sensor probe through the optical fiber coupler;

[0048] S2. When light passes through the optical fiber temperature sensor probe, it is affected by temperature and produces interference, and then is received by the detector to convert the optical signal into an electrical signal;

[0049] S3, the acquisition module collects the electrical signal output by the detector and converts it into interference fringes;

[0050] S4, the analysis module processes the interference fringe information collected by the acquisition module in real time, and calculates the movement amount of the interference fringe using formula 1;

[0051] S5, the temperature calibration module calculates the temperature change according to the interference fringe movement calculated by the analysis module using Formula 2, and then compensates for the actual temperature;

[0052] S6. The output module outputs the actual temperature value and saves it.

[0053] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A temperature monitoring system based on optical fiber interferometer, characterized in that: It includes an optical fiber temperature sensing probe, a light source, an optical fiber coupler, a detector and a signal processing unit, wherein the optical fiber temperature sensing probe is connected to the light source through the optical fiber coupler, and the output end of the optical fiber temperature sensing probe is connected to the detector, and the output end of the detector is connected to the signal processing unit through a line; The optical fiber temperature sensing probe comprises a single-mode optical fiber, a multi-mode optical fiber and a housing, wherein the single-mode optical fiber and the multi-mode optical fiber are connected by fusion splicing, and the single-mode optical fiber and the multi-mode optical fiber are fusion spliced ​​and packaged inside the housing; The signal processing unit includes an acquisition module, an analysis module, a temperature calibration module and an output module. The acquisition module is connected to the output end of the detector, the analysis module processes the information collected by the acquisition module in real time, and the analysis module is connected to the temperature calibration module, and the temperature calibration module is connected to the output module.

2. The temperature monitoring system based on fiber interferometer according to claim 1 is characterized in that: The core diameter of the single-mode optical fiber is 8.5-9.5 μm, the core diameter of the multi-mode optical fiber is 50 μm-62.5 μm, and the temperature for fusing the single-mode optical fiber and the multi-mode optical fiber is 1600°C.

3. The temperature monitoring system based on fiber interferometer according to claim 1, characterized in that: The light source is a laser diode or a superluminescent diode, the detector is a photodiode, an avalanche photodiode or a photomultiplier tube, and the detector is used to receive optical signals from a probe of the optical fiber temperature sensor.

4. The temperature monitoring system based on fiber interferometer according to claim 1, characterized in that: The wavelength emitted by the light source is 1550 nanometers.

5. The temperature monitoring system based on fiber interferometer according to claim 1, characterized in that: The acquisition module is used to acquire the electrical signal output by the detector, and the acquisition module converts the acquired electrical signal into interference fringes.

6. The temperature monitoring system based on fiber interferometer according to claim 1, characterized in that: The analysis module is connected to the acquisition module, and the analysis module calculates the movement amount of the interference fringes, and the formula is as follows: Where Δφ is the movement of the interference fringes, λ is the wavelength of the light source, Δn is the change in the refractive index of the optical fiber, and L is the total length of the single-mode fiber and the multimode fiber after fusion.

7. The temperature monitoring system based on fiber interferometer according to claim 1, characterized in that: The temperature calibration module is used to receive the interference fringe movement amount calculated by the analysis module, and derive the temperature change according to the interference fringe movement amount. The derivation formula is as follows: Where ΔT is the temperature change, λ is the wavelength of the light source, n is the refractive index of the optical fiber, and Δφ is the movement of the interference fringes.

8. The temperature monitoring system based on fiber interferometer according to claim 1, characterized in that: The output module is used to output the temperature value calculated by the temperature calibration module and store the temperature value.

9. A temperature monitoring method based on fiber interferometer, using a temperature monitoring system based on fiber interferometer according to any one of claims 1 to 8, characterized in that: Proceed as follows: S1, the light source emits light with a wavelength of 1550 nanometers and transmits it to the optical fiber temperature sensor probe through the optical fiber coupler; S2. When light passes through the optical fiber temperature sensor probe, it is affected by temperature and produces interference, and then is received by the detector to convert the optical signal into an electrical signal; S3, the acquisition module collects the electrical signal output by the detector and converts it into interference fringes; S4, the analysis module processes the interference fringe information collected by the acquisition module in real time, and calculates the movement amount of the interference fringe using formula 1; S5, the temperature calibration module calculates the temperature change according to the interference fringe movement calculated by the analysis module using Formula 2, and then compensates for the actual temperature; S6. The output module outputs the actual temperature value and saves it.

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