CN116105891B - High-temperature sensing device and calibration method thereof - Google Patents
High-temperature sensing device and calibration method thereof Download PDFInfo
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- CN116105891B CN116105891B CN202310153853.8A CN202310153853A CN116105891B CN 116105891 B CN116105891 B CN 116105891B CN 202310153853 A CN202310153853 A CN 202310153853A CN 116105891 B CN116105891 B CN 116105891B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/324—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Raman scattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K15/00—Testing or calibrating of thermometers
- G01K15/005—Calibration
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
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Abstract
The embodiment of the application provides a high-temperature sensing device and a calibration method of the high-temperature sensing device, wherein the high-temperature sensing device comprises a laser emitting module, a single crystal optical fiber module, an optical detection module and a data processing module; the single crystal optical fiber module comprises a single crystal optical fiber, wherein the single crystal optical fiber is used for transmitting and exciting a back scattering signal of laser; the optical detection module comprises a Stokes module and an anti-Stokes module. The calibration method of the high-temperature sensing device comprises the following steps: acquiring Stokes data and anti-Stokes data of the single crystal optical fiber at a plurality of temperatures; carrying out noise reduction treatment on Stokes data and anti-Stokes data at a plurality of temperatures; and calculating AS/S ratio of the anti-Stokes noise reduction data and the Stokes noise reduction data at a plurality of temperatures, and determining a temperature and AS/S ratio relation curve. The high-temperature sensing device is high in accuracy.
Description
Technical Field
The embodiment of the application relates to the field of sensors, in particular to a high-temperature sensing device and a calibration method of the high-temperature sensing device.
Background
The high-temperature sensing has important application value and effect in the fields of aerospace and the like, especially in the high-temperature sensing of more than 1000 ℃. For example, the temperature of high-temperature fuel gas and wall surface of a hot end component (a combustion chamber and a turbine) in an aeroengine is the most critical parameter for determining the performance and the working state of the hot end component, and is also a key technology with great difficulty in the temperature test of the engine. As the thrust to weight ratio of the engine increases, high temperature monitoring of the hot side components presents a greater challenge. The optical fiber sensor has the unique advantages of light weight, electromagnetic interference resistance, corrosion resistance and the like, and is rapidly developed in the field of temperature sensing. The existing optical fiber high-temperature sensor mainly comprises an optical F-P cavity sensor constructed based on a sapphire optical fiber with an ultra-high melting point (2054 ℃) and a write-in sapphire optical fiber FBG for high-temperature detection. However, the above solutions have cross sensitivity to temperature, shock and strain. In complex severe environments, temperature compensation and complex signal cross demodulation are required. In addition, the high-temperature sensing needs to monitor the temperature of a certain area range of the hot end component in many cases, and the single-point optical fiber high-temperature sensor has difficulty in networking arrangement and signal demodulation. Writing multiple FBGs on the sapphire fiber also has the limitation of spatial resolution to construct a quasi-distributed high temperature sensor.
Disclosure of Invention
In order to overcome the defects of the technology, the application provides the high-temperature sensing device and the calibration method of the high-temperature sensing device, and the accuracy is high.
One aspect of the embodiments of the present application provides a high temperature sensing device, including: the device comprises a laser emission module, a single crystal optical fiber module, an optical detection module and a data processing module;
the single crystal optical fiber module comprises a single crystal optical fiber, the single crystal optical fiber is arranged along a light path of laser emitted by the laser emitting module, and the single crystal optical fiber is used for transmitting the laser and exciting a back scattering signal;
the optical detection module is arranged on the optical path of the back scattering signal and comprises a Stokes module for obtaining Stokes data of the back scattering signal and an anti-Stokes module for obtaining anti-Stokes data of the back scattering signal, and the data processing module is electrically connected with the optical detection module and is used for obtaining temperature according to the Stokes data and the anti-Stokes data.
Optionally, the single crystal optical fiber module further includes a focusing lens, which is disposed on a light path of the laser emitted by the laser emitting module, and one end of the single crystal optical fiber is disposed at a focal point formed by focusing the laser by the focusing lens.
Optionally, the optical detection module includes a beam splitter, where the beam splitter is disposed on an optical path where the laser emitted by the laser emission module and the back-scattering signal overlap, and is configured to change an optical path direction of the back-scattering signal so that the back-scattering signal enters the optical detection module.
Optionally, the high temperature sensing device further comprises a photoelectric detector connected with the data processing module, and the photoelectric detector is arranged on a light path of the laser emitted by the laser emitting module after being reflected by the beam splitter.
Optionally, the high temperature sensing device further comprises a photoelectric detector or an extinction module connected with the data processing module, and the photoelectric detector or the extinction module is arranged on a light path of the laser emitted by the laser emitting module after being reflected by the beam splitter.
Optionally, the optical detection module further includes a notch filter, where the notch filter is disposed on an optical path of the backscattered signal and before the dichroic mirror.
Optionally, the Stokes module includes the first avalanche photodiode detector disposed on the optical path of the first light beam and electrically connected to the data processing module; and
The anti-Stokes module comprises a second avalanche photodiode detector arranged on the optical path of the second light beam and is electrically connected with the data processing module.
Optionally, the bandwidth of the first avalanche photodiode detector and/or the second avalanche photodiode detector is 1GHz.
Optionally, the optical detection module includes a Stokes lens disposed on the optical path of the first light beam between the dichroic mirror and the first avalanche photodiode detector; and
The optical detection module includes an anti-Stokes lens disposed on an optical path of the second light beam between the dichroic mirror and the second avalanche photodiode detector.
Optionally, the optical detection module includes a first filter disposed on the optical path of the first light beam between the dichroic mirror and the Stokes lens; and
The optical detection module comprises a second optical filter arranged on the optical path of the second light beam and between the dichroic mirror and the anti-Stokes lens.
Optionally, the high temperature sensing device includes a Stokes attenuation sheet, and is disposed on the optical path of the first light beam and between the dichroic mirror and the Stokes module.
Optionally, the high temperature sensing device further comprises one or more mirrors, which are arranged on the optical path of the laser emitted by the laser emitting module and/or on the optical path of the back scattering signal emitted by the single crystal optical fiber and/or on the optical path of the first light beam and/or on the optical path of the second light beam.
Optionally, the high temperature sensing device comprises a laser attenuation sheet, and the laser attenuation sheet is arranged on a light path of the laser emitted by the laser emitting module and between the laser emitting module and the single crystal optical fiber module.
Optionally, the laser emitting module comprises a high-energy picosecond pulse laser with a full width half maximum in the range of 5ps-1000ps.
Optionally, the central wavelength range of the laser emitted by the laser emitting module is 300nm-1550nm.
Optionally, the single crystal optical fiber is a sapphire optical fiber or a YAG optical fiber.
Optionally, the single crystal optical fiber is a sapphire optical fiber, and the melting point is 2054 ℃; or (b)
The single crystal optical fiber is YAG optical fiber, and the melting point is 1950 ℃.
Optionally, the optical density of the notch filter and/or the first filter and/or the second filter is greater than 6.
In another aspect, the present application provides a calibration method of a high temperature sensing device, where the high temperature sensing device includes: the device comprises a laser emission module, a single crystal optical fiber module, an optical detection module and a data processing module;
the single crystal optical fiber module comprises a single crystal optical fiber, the single crystal optical fiber is arranged along a light path of laser emitted by the laser emitting module, and the single crystal optical fiber is used for transmitting and exciting a back scattering signal of the laser;
The optical detection module is arranged on the optical path of the back scattering signal, and comprises a Stokes module for obtaining Stokes data of the back scattering signal and an anti-Stokes module for obtaining anti-Stokes data of the back scattering signal, the data processing module is electrically connected with the optical detection module and is used for obtaining temperature according to the Stokes data and the anti-Stokes data, and the calibration method comprises the following steps:
acquiring Stokes data and anti-Stokes data of the single crystal optical fiber at a plurality of temperatures;
performing noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures, and determining Stokes noise reduction data and anti-Stokes noise reduction data;
and calculating AS/S ratio of the anti-Stokes noise reduction data and the Stokes noise reduction data at a plurality of temperatures, and determining a temperature and AS/S ratio relation curve.
Optionally, the performing noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures, and determining Stokes noise reduction data and anti-Stokes data includes:
and directly averaging the Stokes data and the anti-Stokes data of the single crystal optical fiber of the multiframe at a plurality of temperatures, and taking the Stokes data and the anti-Stokes data after direct averaging as Stokes noise reduction data and anti-Stokes data.
Optionally, the performing noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures, and determining Stokes noise reduction data and anti-Stokes noise reduction data includes:
and carrying out noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures through a non-local mean algorithm, and determining Stokes noise reduction data and anti-Stokes noise reduction data.
Optionally, the performing noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures through a non-local mean algorithm to determine Stokes noise reduction data and anti-Stokes noise reduction data includes:
establishing a two-dimensional matrix according to the Stokes data and the anti-Stokes data of a plurality of frames, and analogizing each data point in the matrix into a pixel point in an image to establish the image;
determining similar information and redundant information in the image according to the image;
and denoising by using the similar information and the redundant information, and determining Stokes denoising data and anti-Stokes denoising data.
Optionally, the acquiring Stokes data and anti-Stokes data of the single crystal optical fiber at a plurality of temperatures includes:
acquiring Stokes signal tracks and anti-Stokes signal tracks of the single crystal optical fiber distributed along the length at a plurality of temperatures;
Performing noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures to determine Stokes noise reduction data and anti-Stokes noise reduction data, including:
carrying out noise reduction treatment on the Stokes signal track and the anti-Stokes signal track to obtain a Stokes noise reduction track and an anti-Stokes noise reduction track;
the calculating AS/S ratio of the anti-Stokes noise reduction data and the Stokes noise reduction data at a plurality of temperatures, determining a temperature and AS/S ratio relation curve, comprising:
determining Stokes noise reduction values and inverse Stokes noise reduction values corresponding to the single crystal optical fiber at a plurality of temperatures according to the Stokes noise reduction track and the inverse Stokes noise reduction track;
and calculating AS/S ratios of the anti-Stokes noise reduction values and the Stokes noise reduction data at a plurality of temperatures, and determining a relation curve corresponding to the plurality of temperature-AS/S ratios.
Optionally, the calibration method further includes:
and determining the spatial resolution of the high-temperature sensing device according to the full width at half maximum of the last reflection peak of the anti-Stokes noise reduction track of the single crystal optical fiber.
Optionally, the calibration method further includes:
repeatedly obtaining a Stokes test value and an anti-Stokes test value obtained by the high-temperature sensing device for a plurality of times at the same room temperature, and determining an AS/S test ratio of the anti-Stokes test value and the Stokes test value;
Substituting the AS/S ratio obtained repeatedly for any position into the temperature-AS/S ratio relation curve, determining the test temperature of the position, and calculating to obtain the test temperature standard deviation of the test temperature;
and determining a test temperature standard deviation curve distributed along the length of the single crystal optical fiber according to a plurality of test temperature standard deviations of the single crystal optical fiber, and taking the test temperature standard deviation curve as the temperature resolution of the high temperature sensing device.
Optionally, the values of the temperatures are in a range of [20 ℃,1400 ℃; and/or the plurality of temperatures comprises at least five temperatures.
According to the high-temperature sensing device and the calibration method thereof, on one hand, the high-temperature sensing device is built based on the single crystal optical fiber, raman signals in the single crystal optical fiber can be excited and efficiently collected, the Raman intensity is irrelevant to vibration and strain of the external environment, and the Raman intensity is sensitive to the temperature of the external environment around the single crystal optical fiber, so that the high-temperature sensing device has high robustness and no cross-sensitive interference. On the other hand, the whole single crystal optical fiber does not need any modification or micro-processing treatment, and the single crystal optical fiber transmits light and is a sensor, so that the distributed high-temperature monitoring can be performed with high spatial resolution based on the device to obtain the temperature field distribution information.
According to the calibration method of the high-temperature sensing device based on the single crystal optical fiber, which is provided by the application, the data acquired by the system device are subjected to denoising treatment, so that the temperature resolution, namely the temperature measurement precision, can be effectively improved. In addition, the ratio of the anti-Stokes to the Stokes is used for demodulating the signals, so that signal disturbance caused by vibration and loss change can be effectively eliminated, and the device can work stably for a long time.
Drawings
FIG. 1 is a schematic diagram of a high temperature sensor according to an embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram of a high temperature sensing device according to another embodiment of the present application;
FIG. 3 is a flow chart of a calibration method of a high temperature sensor according to an embodiment of the present application;
FIG. 4 is a chart of Stokes noise reduction data of a high temperature sensing device at multiple temperatures according to an embodiment of the present application;
FIG. 5 is an inverse Stokes noise reduction data plot of the high temperature sensing device of the embodiment of FIG. 4 at multiple temperatures;
FIG. 6 is a graph showing the temperature resolution of the high temperature sensor device before and after noise reduction according to an embodiment of the present application;
FIG. 7 is an inverse Stokes noise reduction data trace diagram of a high temperature sensing device at 1400 ℃ according to an embodiment of the present application;
FIG. 8 is a graph showing the relationship between the temperature and AS/S ratio of the high temperature sensor of the embodiment shown in FIG. 4.
The high-temperature sensing device 99, the laser emitting module 2, the single crystal optical fiber module 94, the optical detection module 98, the data processing module 97, the single crystal optical fiber 1, the high-speed acquisition system 18, the Stokes module 96, the anti-Stokes module 95, the focusing lens 6, the beam splitter 4, the photoelectric detector 5, the dichroic mirror 9, the notch filter 70, the first avalanche photodiode detector 13, the Stokes lens 12, the second avalanche photodiode detector 17, the anti-Stokes lens 16, the first filter 11, the second filter 15, the laser attenuation sheet 3, the Stokes attenuation sheet 10 and the reflecting mirror 14.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus consistent with some aspects of the present application as detailed in the accompanying claims.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless defined otherwise, technical or scientific terms used in the embodiments of the present application should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present application belongs. The terms "first," "second," and the like in the description and in the claims, are not used for any order, quantity, or importance, but are used for distinguishing between different elements. Likewise, the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "plurality" means two or more. Unless otherwise indicated, the terms "front," "rear," "lower," and/or "upper" and the like are merely for convenience of description and are not limited to one location or one spatial orientation. The word "comprising" or "comprises", and the like, means that elements or items appearing before "comprising" or "comprising" are encompassed by the element or item recited after "comprising" or "comprising" and equivalents thereof, and that other elements or items are not excluded. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
The high-temperature sensing has important application value and effect in the fields of aerospace and the like, especially in the high-temperature sensing of more than 1000 ℃. For example, the temperature of high-temperature fuel gas and wall surface of a hot end component (a combustion chamber and a turbine) in an aeroengine is the most critical parameter for determining the performance and the working state of the hot end component, and is also a key technology with great difficulty in the temperature test of the engine. As the thrust to weight ratio of the engine increases, high temperature monitoring of the hot side components presents a greater challenge. The present disclosure provides a high temperature sensing device 99, fig. 1 is a schematic structural diagram of the high temperature sensing device 99 according to an embodiment of the present disclosure, and fig. 2 is a schematic structural diagram of the high temperature sensing device 99 according to another embodiment of the present disclosure.
Referring to fig. 1 and 2, a high temperature sensing device 99 provided in the present application includes: a laser emitting module 2, a single crystal fiber module 94, an optical detection module 98 and a data processing module 97.
In some embodiments, the single crystal fiber module 94 includes a single crystal fiber 1, the single crystal fiber 1 being disposed along the optical path of the laser light emitted by the laser emitting module 2, the single crystal fiber 1 being configured to propagate the laser light along the single crystal fiber 1 and to generate a backscatter signal in the opposite direction of the laser light. During the temperature measurement of the high temperature sensor 99, the single crystal fiber 1 is placed at the temperature to be measured, and in some embodiments, the specific location of the temperature measurement is determined by the back-scattering round trip time.
Referring to fig. 1 and 2, the optical detection module 98 is disposed on the optical path of the back-scattered signal, and includes a Stokes module 96 for obtaining Stokes data of the back-scattered signal and an anti-Stokes module 95 for obtaining anti-Stokes data of the back-scattered signal, where the data processing module 97 is electrically connected to the optical detection module 98, and is used for obtaining a temperature according to the Stokes data and the anti-Stokes data. In some embodiments, the single crystal optical fiber 1 is arranged along the optical path of the laser emitted by the laser emitting module 2, the high temperature sensing device 99 of the present application generates raman scattering by means of short and strong ear laser pulse propagation in the single crystal optical fiber 1, since Stokes data and anti-Stokes data obtained at different temperatures are different, stokes and anti-Stokes have the same coupling efficiency, laser power fluctuation and transmission attenuation, the ratio of the Stokes and the anti-Stokes counteracts negative effects caused by the metabolic factors, so that the measurement stability can be improved, and the high temperature sensing device 99 of the present application can be applied to high temperature, large-scale and long-distance temperature monitoring, and the temperature can be estimated through the ratio of Stokes scattering and anti-Stokes scattering.
In some embodiments, the laser emitting module 2 comprises a pump laser for emitting pump laser light. The pump laser has the advantages of low power consumption, reliable performance, long service life and the like, and the output laser beam has high quality, so that the coupling loss can be further reduced. The laser emitting module 2 comprises a narrow pulse laser.
In some embodiments, the single crystal fiber module 94 further includes a focusing lens 6 disposed on the optical path of the laser light emitted from the laser emitting module 2, and one end of the single crystal fiber 1 is disposed at a focal point formed by focusing the laser light by the focusing lens 6. The focusing lens 6 is used for focusing the laser emitted by the laser emitting module 2 on the optical fiber, so that the optical fiber raman scattering is realized, and the optical detection module 98 can conveniently obtain Stokes data and anti-Stokes data of the optical fiber backscattering signal.
In some embodiments, since the optical path direction of the light beam scattered back by the optical fiber is back-emitted along the direction of the laser light emitted by the laser emitting module 2, in order to enable the backscattered signal to be received by the optical detection module 98, the optical detection module 98 further includes a beam splitter 4, where the beam splitter 4 is disposed on the optical path where the laser light emitted by the laser emitting module 2 and the backscattered signal overlap, and the beam splitter 4 is configured to change the optical path direction of the backscattered signal so that the backscattered signal enters the optical detection module 98. Thus avoiding the laser emitted by the laser emitting module 2 from affecting the detection result. In some embodiments, the beam splitter 4 is a 50:50 beam splitter 4.
The laser emitted by the laser emitting module 2 will also pass through the beam splitter 4, and is split by the beam splitter 4 into a portion that irradiates the optical fiber and a portion that reflects the optical fiber, and in the embodiment shown in fig. 1, an extinction module may be disposed on the optical path of the laser emitted by the laser emitting module 2 after being reflected by the beam splitter 4, to absorb the portion that is reflected by the beam splitter 4.
In the embodiment shown in fig. 2, for the reflected part, a photodetector 5 connected to the data processing module 97 may be provided, and the photodetector 5 is also provided on the optical path of the laser light emitted by the laser emitting module 2 after being reflected by the beam splitter. The data of the laser emitted by the real laser emitting module 2 can be obtained, and can be used for subsequent calculation, so that accuracy is improved. In the illustrated embodiment, the data processing module 97 includes a high-speed acquisition system 18 electrically connected to the Stokes module 96, the anti-Stokes module 95, and the photodetector 5 for high-speed acquisition of Stokes data, anti-Stokes data, and initial light intensity.
In some embodiments, to split the light beam reflected by the beam splitter 4 into a portion that enters the Stokes module 96 and a portion that enters the anti-Stokes module 95, the optical detection module 98 further includes a dichroic mirror 9, where the dichroic mirror 9 splits the backscattered signal into a reflected first light beam and a direct second light beam, the Stokes module 96 is disposed on the optical path of the first light beam, and the anti-Stokes module 95 is disposed on the optical path of the second light beam. The dichroic mirror 9 thus transmits or reflects light according to wavelength, the reflected first light beam enters the Stokes module 96 to obtain Stokes data, and the passing second light beam enters the anti-Stokes module 95 to obtain anti-Stokes data of the back-scattered signal.
In some embodiments, the optical detection module 98 further includes a notch filter 70, the notch filter 70 being disposed in the optical path of the back-scattered signal, before the dichroic mirror 9. Referring to fig. 1 and 2, a notch filter 70 may be disposed between the dichroic mirror 9 and the dichroic mirror, to filter out in advance the optical signals that do not need to enter the Stokes module 96 and the anti-Stokes module 95. In the embodiment shown in fig. 1, notch filter 70 includes a first notch filter 707 and a second notch filter 708.
Referring to fig. 1 and 2, the stokes module 96 includes a first avalanche photodiode detector 13 disposed in the optical path of the first light beam and electrically connected to the data processing module 97. The first avalanche photodiode detectably receives the light beam reflected by the dichroic mirror 9, obtains Stokes data, and transmits the Stokes data to the data processing module 97 for data processing. To obtain Stokes data, the optical detection module 98 further comprises a Stokes lens 12 arranged in the optical path of the first light beam, between the dichroic mirror 9 and the first avalanche photodiode detector 13, for focusing the first light beam onto the first avalanche photodiode detector 13. In the illustrated embodiment, the first avalanche photodiode detector 13 is provided at the focal point of the first light beam transmitted through the Stokes lens 12.
With continued reference to fig. 1 and 2, the anti-Stokes module 95 includes a second avalanche photodiode detector 17 disposed in the optical path of the second light beam and electrically connected to the data processing module 97. The second avalanche photodiode detectably receives the light beam reflected by the dichroic mirror 9 and obtains anti-Stokes data, and the anti-Stokes data is transferred to the data processing module 97 for data processing. To obtain the anti-Stokes data, the optical detection module 98 comprises an anti-Stokes lens 16 arranged in the optical path of the second light beam, between the dichroic mirror 9 and the second avalanche photodiode detector 17, for focusing the second light beam onto the second avalanche photodiode detector 17. In the illustrated embodiment, the second avalanche photodiode detector 17 is disposed at the focal point of the second light beam transmitted through the anti-Stokes lens 16.
In some embodiments, the bandwidths of the first avalanche photodiode detector 13 and the second avalanche photodiode detector 17 are 1GHz. Thus, the avalanche photodiode detector of the present application has high bandwidth and low noise, which can improve the spatial resolution of the high temperature sensing device 99 of the present application.
In some embodiments, to ensure accuracy of the resulting Stokes data and anti-Stokes data, the optical detection module 98 further includes a first filter 11 disposed in the optical path of the first light beam between the dichroic mirror 9 and the Stokes lens 12, and a second filter 15 disposed in the optical path of the second light beam between the dichroic mirror 9 and the anti-Stokes lens 16. The first light beam and the second light beam are filtered in this way, so that accurate Stokes data and anti-Stokes data which can be used for temperature detection are obtained.
In some embodiments, the optical density of the filter used in the high temperature sensing device 99 of the present application is greater than 6. Therefore, the filtering effect of the optical filter is ensured, noise light with the wavelength of the pumping light can be effectively filtered, and the signal-to-noise ratio of a real effective Raman signal is improved. The high temperature sensing device 99 of the present application has high measurement accuracy.
In the embodiment shown in fig. 1, the first light beam has an intensity higher than the required intensity, and the high temperature sensing means 99 comprises a Stokes attenuator 10 arranged in the optical path of the first light beam between the dichroic mirror 9 and the Stokes module 96. Therefore, the intensity of the first light beam is reduced, and Stokes data are conveniently acquired.
In the embodiment shown in fig. 1, the laser emitting module 2 emits laser light with an intensity higher than the required intensity, and the high temperature sensing device 99 includes a laser attenuator 3 disposed between the laser emitting module 2 and the single crystal fiber module 94 on the optical path of the laser light emitted from the laser emitting module 2. In this way, the intensity of the laser emitted by the laser emitting module 2 is reduced, so that the temperature is conveniently detected. In other embodiments, attenuation pads may be provided where it is desired to reduce the intensity of light.
In some embodiments, the high temperature sensing device 99 further comprises one or more mirrors 14 arranged in the optical path of the laser light emitted by the laser emitting module 2 and/or in the optical path of the back-scattered signal emitted by the single crystal fiber 1 and/or in the optical path of the first light beam and/or in the optical path of the second light beam.
The mirror 14 is used to change the direction of the light path, for example, in the embodiment shown in fig. 1 and 2, in order to arrange the first avalanche photodiode detector 13 and the second avalanche photodiode detector 17 in parallel, a mirror 14 is provided on the light path of the second light beam to change the direction of the second light beam, and in the illustrated embodiment, the mirror 14 is arranged at 45 ° and reflects the second light beam vertically, so that the first avalanche photodiode detector 13 and the second avalanche photodiode detector 17 are arranged in parallel.
In the embodiment shown in fig. 2, in order to adapt to the setting of the housing of the high temperature sensing device 99, the laser energy emitted by the laser emitting module 2 is transmitted to the single crystal optical fiber 1, and meanwhile, the optical path of the laser emitted by the laser emitting module 2 is prolonged, please refer to fig. 2, in the embodiment shown in fig. 2, a two-sided mirror 14 is disposed on the optical path of the laser emitted by the laser emitting module 2, the laser emitted by the laser emitting module 2 is vertically reflected twice, the two-sided mirror 14 is disposed between the single crystal optical fiber 1 and the laser emitting module 2, and the single crystal optical fiber 1 is disposed on the optical path of the laser emitted by the laser emitting module 2 after the two reflections, so that the high temperature sensing device 99 of the present application is reasonable in design.
In some embodiments, the laser emitting module 2 comprises a high energy picosecond pulsed laser with a full width half maximum in the range of 5ps-1000ps. So can promote the spatial resolution of high temperature sensing device 99 of this application in the aspect of hardware, the spatial resolution of high temperature sensing device 99 of this application is high.
In some embodiments, the laser emitting module 2 emits laser light having a central wavelength in the range of 300nm to 1550nm. The laser of the laser emission module 2 of the application covers a common wave band of the system, so that the single crystal optical fiber 1 is convenient to acquire for Raman scattering, and the Stokes data and the anti-Stokes data are acquired to realize high-temperature detection. On the other hand, a suitable laser wavelength also facilitates filtering out noise photons.
In some embodiments, the single crystal optical fiber 1 is a sapphire optical fiber or a YAG optical fiber, wherein a sapphire optical fiber having a melting point of 2054 ℃ or a YAG (yttrium aluminum garnet) optical fiber having a melting point of 1950 ℃ may be selected. The use of the single crystal optical fiber 1 having an ultra-high melting point can improve the stability of the high temperature sensing device 99 of the present application, and is also the basis for realizing the ultra-high temperature sensing of the present application.
In another aspect of the present application, a method for calibrating a high temperature sensing device 99 is provided, which is suitable for the high temperature sensing device 99 provided in the present application, and fig. 3 is a flowchart of a method for calibrating the high temperature sensing device 99 according to an embodiment of the present application. Referring to fig. 3, the calibration method includes steps S1-S3. After the calibration of the high temperature sensing device 99 based on the single crystal optical fiber 1 of the above example is completed, the data collected during the use of the device can be signal-demodulated based on the calibration result.
In step S1, stokes data and inverse Stokes data of the single crystal optical fiber 1 at a plurality of temperatures are acquired. In some embodiments, the whole single crystal optical fiber 1 may be placed in a high temperature tube furnace, the high temperature furnace is set to gradually raise the temperature from room temperature (25 ℃) to 1400 ℃ at a speed of raising the temperature to 150 ℃ every 60 minutes, and the original data of the responses of the single crystal optical fiber 1 at different temperatures are collected in real time, so that Stokes data and anti-Stokes data of the single crystal optical fiber 1 are obtained.
In step S2, the Stokes data and the inverse Stokes data at a plurality of temperatures are subjected to noise reduction processing, and Stokes noise reduction data and inverse Stokes noise reduction data are determined. The denoised Stokes noise reduction data and the inverse Stokes noise reduction data obtained after the noise reduction are accurate, so that the calibration of the high temperature sensing device 99 is convenient. FIG. 4 is a graph of Stokes noise reduction data at multiple temperatures for a high temperature sensing device 99 according to an embodiment of the present application; FIG. 5 is a graph of anti-Stokes noise reduction data for the high temperature sensing device 99 of the embodiment of FIG. 4 at multiple temperatures. In some embodiments, the plurality of temperatures has a range of values of [20 ℃,1400 ℃). In some embodiments, the plurality of temperatures includes at least five temperatures. The data obtained in this way are comprehensive and accurate, please refer to fig. 4 and 5, fig. 4 and 5 show that the high temperature sensing device 99 changes the Stokes data and the anti-Stokes data of the single crystal optical fiber 1 with temperature change for a plurality of sets of Stokes and anti-Stokes channels at 25 ℃, 150 ℃,300 ℃,450 ℃,600 ℃,750 ℃,900 ℃,1050 ℃,1200 ℃,1400 ℃. Referring to fig. 4 and 5, the higher the actual temperature of the single crystal optical fiber 1, the greater the Stokes response signal intensity and the inverse Stokes response signal intensity. Thus, the high temperature sensing device 99 of the present application can be used for ultra-high temperature detection.
In some embodiments, regarding how to perform noise reduction processing on the Stokes data and the anti-Stokes data, the Stokes data and the anti-Stokes data of the single crystal fiber 1 of the multiframe at a plurality of temperatures can be directly averaged, and the directly averaged Stokes data and anti-Stokes data are used as Stokes noise reduction data and anti-Stokes data. The multi-frame data is the multi-frame data collected under a certain time, and can be expressed as L11, L12, L13 and … L1n; l21, L22, L23, … L2n; …; lm1, lm2, lm3, … Lmn. The single frame data obtained after the multi-frame superimposition averaging process was [ (l11+l21+ … +lm1)/m, (l12+l22+ & lt 2 & gt)/m, (l1n+l2n+ & lt Lmn)/m ]. In some embodiments, the Stokes and anti-Stokes data may be integrated for 1s, i.e., the superposition of 1000 frames of data is averaged, resulting in averaged Stokes and anti-Stokes data. The Stokes data and the anti-Stokes data after being averaged can have a certain noise reduction effect. In other embodiments, 2000 frames of data acquired at 2s time may also be acquired. And after the 2000 frames are overlapped and subjected to average processing, obtaining single frame data after average noise reduction, so that the accuracy is further improved, and the method is not limited.
In other embodiments, the Stokes noise reduction data and the anti-Stokes noise reduction data may be determined by performing noise reduction processing on the Stokes data and the anti-Stokes data at a plurality of temperatures through a non-local mean (NLM).
In other embodiments, noise reduction of Stokes data and anti-Stokes data at multiple temperatures by a non-local mean algorithm (NLM) includes the steps of: establishing a two-dimensional matrix according to Stokes data and anti-Stokes data of a plurality of frames, analogizing each data point in the matrix into a pixel point in an image, and establishing the image; determining similar information and redundant information in the image according to the image; and denoising by using the similar information and the redundant information, and determining Stokes denoising data and anti-Stokes denoising data. The Stokes noise reduction data and the anti-Stokes noise reduction data obtained in this way are high in accuracy.
In this embodiment, specifically, according to the non-local mean algorithm, in order to remove noise of the pixel point i in the two-dimensional matrix, the denoised data value may be calculated asWherein I is the whole matrix domain, f (j) corresponds to the value of the pixel point j, w (I, j) represents the weight factor and can be calculated as +.>Wherein h is smoothingControl factor, Z (i) is normalization factor, |f (η) i )-f(η j ) I is the Euclidean distance, where eta i,j To represent the similarity of two block windows in Euclidean distance for a two-dimensional data point block around pixel i, j, the h factor in the NLM algorithm parameter in this example takes a value of 6, the two-dimensional data point block size is 4×4, and the two-dimensional matrix size is a 20×20 matrix.
In still other embodiments, the Stokes data and the anti-Stokes data at a plurality of temperatures may be subjected to noise reduction treatment, and then a non-local mean algorithm is adopted to perform secondary noise reduction, so that the accuracy of the obtained Stokes noise reduction data and the obtained anti-Stokes noise reduction data is further improved.
Based on the Stokes and inverse Stokes data at room temperature after the treatment in fig. 4-5, 20 sets of data are taken to further calculate the standard deviation of twenty sets of temperature distribution data, so as to obtain fig. 6. Fig. 6 is a graph showing the temperature resolution of the high temperature sensor device 99 before and after noise reduction according to an embodiment of the present application, wherein the abscissa is the position (m) on the single crystal optical fiber 1, and the ordinate is the standard deviation of temperature (deg.c), and the x-sign curve is the temperature resolution without noise reduction. In this embodiment, the Stokes data and the inverse Stokes data at a plurality of temperatures are first subjected to noise reduction processing, and then a non-local mean algorithm is adopted to perform secondary noise reduction. It can be seen that the standard deviation of the temperatures of the Stokes data and the inverse Stokes data after the noise reduction in the step S2 is obviously reduced, and the temperature resolution is obviously improved.
In some embodiments, since the single crystal optical fiber 1 has a certain length, acquiring Stokes data and anti-Stokes data of the single crystal optical fiber 1 at a plurality of temperatures includes: a Stokes signal trace and an inverse Stokes signal trace of the single crystal optical fiber 1 distributed along the length at a plurality of temperatures are obtained. Correspondingly, the method for determining the Stokes noise reduction data and the anti-Stokes noise reduction data comprises the following steps of: and carrying out noise reduction processing on the Stokes signal track and the anti-Stokes signal track to obtain a Stokes noise reduction track and an anti-Stokes noise reduction track. In this way, the calibration method of the high temperature sensing device 99 of the present application is based on the design of the high temperature sensing device 99 with the single crystal optical fiber 1 of the present application, so that the distributed sensing track along the single crystal optical fiber 1 can be obtained, and the accuracy of the measurement result of the actual temperature in the use process can be improved.
Since the reflection of the raman signal accumulated at the end face of the single crystal fiber is equivalent to the response of the system to an infinitely small heating source in a mathematical model, the response speed depends on the response speed of the system, and corresponds to the minimum length of the system response, the spatial resolution of the system can be obtained through the full width at half maximum of the end face signal. In some embodiments, the calibration method further comprises: the spatial resolution of the high temperature sensing device 99 is determined from the full width at half maximum of the last reflection peak of the anti-Stokes noise reduction trace of the single crystal optical fiber 1. FIG. 7 is an inverse Stokes noise reduction data trace diagram of the high temperature sensing device 99 at 1400℃according to an embodiment of the present application. In the illustrated embodiment, the full width at half maximum of the last reflection peak is 7cm, from which the spatial resolution of the high temperature sensing device 99 can be obtained.
FIG. 8 is a graph showing the relationship between the temperature-AS/S ratio of the high temperature sensor 99 according to the embodiment shown in FIG. 4. Referring to fig. 8, in step S3, AS/S ratios of the anti-Stokes noise reduction data and the Stokes noise reduction data at a plurality of temperatures are calculated, and a temperature and AS/S ratio relationship is determined. In the embodiment shown in fig. 8, the data of ten groups of Stokes and anti-Stokes channels at 25 ℃, 150 ℃,300 ℃,450 ℃,600 ℃,750 ℃,900 ℃,1050 ℃,1200 ℃,1400 ℃ in the single crystal optical fiber 1 are selected, and curve fitting is performed to obtain a temperature and AS/S ratio relation curve.
In some embodiments, since the single crystal optical fiber 1 has a certain length, the AS/S ratio of the anti-Stokes noise reduction data and the Stokes noise reduction data at a plurality of temperatures is calculated, and a temperature and AS/S ratio relation curve is determined, comprising the following steps: firstly, according to a Stokes noise reduction track and an anti-Stokes noise reduction track, determining corresponding Stokes noise reduction values and anti-Stokes noise reduction values of the single crystal optical fiber 1 at a plurality of temperatures; and secondly, calculating AS/S ratios of the anti-Stokes noise reduction values and Stokes noise reduction data at a plurality of temperatures, and determining a relation curve corresponding to the plurality of temperature-AS/S ratios. Thus, the calibration method of the high-temperature sensing device 99 is based on the design of the high-temperature sensing device 99 with the single crystal optical fiber 1, and the distributed sensing track along the single crystal optical fiber 1 can be obtained with high accuracy.
In some embodiments, to improve the accuracy of the obtained AS/S ratio relationship curve, the Stokes test value and the anti-Stokes test value obtained by the high temperature sensing device 99 may be repeatedly obtained at the same room temperature for multiple times, and the AS/S test ratio of the anti-Stokes test value and the Stokes test value may be determined; substituting the AS/S ratio obtained repeatedly for any position into a temperature-AS/S ratio relation curve to determine the test temperature of the position, and calculating to obtain the test temperature standard deviation of the test temperature; from the plurality of test temperature standard deviations of the single crystal optical fiber 1, a test temperature standard deviation curve distributed along the length of the single crystal optical fiber 1 is determined as the temperature resolution of the high temperature sensing device 99. With continued reference to fig. 6, fig. 6 illustrates the temperature resolution of the high temperature sensing device 99.
Some steps in the calibration method of the high temperature sensing device 99 of the present application may be used for actual measurement of the high temperature sensing device 99 of the present application, for example, step S2 "noise reduction processing is performed on Stokes data and anti-Stokes data", and non-local mean (NLM) may be used to process the data obtained by actual measurement (specific processing steps are the same as above), and signal demodulation is performed to obtain relatively accurate temperature data.
According to the high-temperature sensing device 99, the accuracy of ultra-high temperature distributed temperature measurement is improved on two layers of hardware and a method, on the hardware, the high-temperature sensing device 99 measures temperature by utilizing Stokes data and anti-Stokes data obtained by Raman scattering of the single crystal optical fiber 1 at high temperature, the accuracy is high, on the method, the high-temperature sensing device 99 performs noise reduction treatment on the Stokes data and the anti-Stokes before obtaining a relation curve of a temperature-AS/S ratio, the obtained curve can reflect the relation of the temperature-AS/S ratio, the temperature resolution and the spatial resolution of the high-temperature sensing device 99 are improved, and the accuracy of temperature measurement of the high-temperature sensing device 99 is high.
According to the high-temperature sensing device and the calibration method thereof, on one hand, the distributed high-temperature sensing device is built based on the single crystal optical fiber, raman signals in the single crystal optical fiber can be excited and efficiently collected, the Raman intensity is irrelevant to vibration and strain of the external environment, and the Raman intensity is sensitive to the temperature of the external environment around the single crystal optical fiber, so that the distributed high-temperature sensing device has high robustness and no cross-sensitive interference. On the other hand, the whole single crystal optical fiber does not need any modification or micro-processing treatment, and the single crystal optical fiber transmits light and is a sensor, so that the distributed high-temperature monitoring can be performed with high spatial resolution based on the device to obtain the temperature field distribution information.
According to the calibration method of the high-temperature sensing device based on the single crystal optical fiber, which is provided by the application, the data acquired by the system device are subjected to denoising treatment, so that the temperature resolution, namely the temperature measurement precision, can be effectively improved. In addition, the ratio of the anti-Stokes to the Stokes is used for demodulating the signals, so that signal disturbance caused by vibration and loss change can be effectively eliminated, and the device can work stably for a long time.
The high temperature sensing device and the calibration method of the high temperature sensing device provided by the embodiment of the application are described in detail. Specific examples are used herein to illustrate the high temperature sensing device and the calibration method of the high temperature sensing device according to the embodiments of the present application, and the description of the above embodiments is only for helping to understand the core idea of the present application, and is not intended to limit the present application. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made herein without departing from the spirit and principles of the invention, which should also fall within the scope of the appended claims.
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| CN105953941A (en) * | 2016-04-29 | 2016-09-21 | 深圳艾瑞斯通技术有限公司 | Distributed fiber temperature measurement method and device based on Raman scattering |
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| US9964453B2 (en) * | 2014-03-14 | 2018-05-08 | Optromix Company | Device and method for high precision fiber-optic temperature profile measurements in long length areas |
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| RU2458325C1 (en) * | 2011-04-28 | 2012-08-10 | Общество с ограниченной ответственностью "ПетроФайбер" | Method of measuring temperature distribution and device for realising said method |
| CN105953941A (en) * | 2016-04-29 | 2016-09-21 | 深圳艾瑞斯通技术有限公司 | Distributed fiber temperature measurement method and device based on Raman scattering |
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