Distributed fluorescence temperature measurement method based on 45-degree inclined grating

Abstract

The invention discloses a distributed fluorescence temperature measurement method based on 45-degree inclined gratings, and relates to the field of temperature monitoring under high-temperature conditions of engine turbine blades and the like. 45-degree inclined grating strings are designed and manufactured, the outer sides of the 45-degree inclined gratings are coated with fluorescent materials, and the fluorescent materials are made to emit light through ultraviolet pulse excitation light; the fluorescence returns to the optical fiber through the 45-degree inclined grating, the fluorescence lifetime is measured, temperature monitoring is achieved according to the relation between the fluorescence lifetime and the temperature, the detection position is calculated through the pulse light return time, and temperature distribution of different positions is obtained. According to the distributed fluorescence temperature measurement method based on the 45-degree inclined grating, the measurement precision and the signal processing capacity are improved through a time correlation single photon counting method, the grating can be inscribed on a sapphire optical fiber, and the method is suitable for temperature monitoring in the high-temperature field of engine turbine blades and the like; and meanwhile, the device has a multi-point temperature measurement effect with high precision and strong high-temperature adaptability, and is of great significance to high-temperature environment monitoring.

Description

Technical Field

[0001] The present invention relates to the field of temperature monitoring under high temperature conditions such as engine turbine blades, and in particular to a distributed fluorescence temperature measurement method based on a 45° inclined grating. Background Art

[0002] Temperature measurement technology has a wide range of applications in industry, scientific research and daily life, especially in temperature monitoring in high-temperature environments, such as engine turbine blades, nuclear reactors and high-temperature industrial furnaces. Accurate temperature monitoring is of great significance for ensuring safe operation of equipment, optimizing process control and extending equipment life.

[0003] Traditional temperature measurement methods, such as thermocouples and single-point fluorescence temperature measurement technology (fluorescent agent is applied to the end of the optical fiber), can measure temperature in high-temperature environments, but they can usually only provide single-point temperature data. This single-point temperature measurement technology is difficult to meet the needs of modern industry and scientific research for temperature field distribution information, especially in situations where high spatial resolution is required. The limitations of the single-point temperature measurement method are particularly obvious.

[0004] Distributed temperature measurement technology based on the Raman effect can provide temperature distribution information along the entire length of the optical fiber, but its signal-to-noise ratio is low and its measurement accuracy is poor, which limits its application in high-temperature environments. This technology relies on the intensity change of the Raman scattering signal, and the Raman scattering signal itself is weak and easily interfered by noise, resulting in inaccurate measurement results.

[0005] Therefore, a new type of high-precision distributed temperature measurement method is needed that can realize multi-point temperature monitoring in a high-temperature environment and provide high signal-to-noise ratio and high-precision temperature distribution data. The distributed fluorescence temperature measurement method based on a 45° inclined grating of the present invention is proposed to meet this demand. Summary of the invention

[0006] The main purpose of the present invention is to provide a distributed fluorescence temperature measurement method based on a 45° tilted grating, which can effectively solve the problems in the background technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A distributed fluorescence temperature measurement method based on a 45° tilted grating includes the following steps:

[0009] S1: Design and manufacture a 45° tilted grating string: prepare optical fiber and 45° tilted grating, write multiple 45° tilted gratings on the same optical fiber at a certain interval, and the optical fiber can be bent and coiled;

[0010] S2: Apply fluorescent material on the outside of the 45° inclined grating;

[0011] S3: The fluorescent material coated on the 45° inclined grating is excited by ultraviolet pulse excitation light to emit fluorescence, and the 45° inclined grating coated with fluorescent material is placed in an incubator, and the incubator temperature is set at 20°C, 40°C, 60°C, 80°C, 100°C, and 120°C, and the fluorescence lifetime is measured at different temperatures;

[0012] S4: Allow the fluorescence to return to the optical fiber through a 45° tilted grating;

[0013] S5: Detect the lifetime of fluorescence and realize temperature measurement based on the functional relationship between the lifetime of the fluorescent material and the temperature. The relationship between the lifetime τ(T) of the fluorescent material and the temperature T is as follows: Formula 3:

[0014]

[0015] Among them, ΔE is the activation energy, which determines the sensitivity of the fluorescence lifetime to temperature changes; k is the Boltzmann constant, which is 8.617×10 -5 eV / K; Rs, R T are constants related to the material; ΔE, Rs, R T It can be obtained by calibrating and fitting the measured life data with more than 6 temperature points;

[0016] S6: preparing an ultraviolet pulse excitation light source, a WDM wavelength division multiplexer, a detector, and a single photon detector, wherein the WDM wavelength division multiplexer includes a through arm and a reflection arm;

[0017] The ultraviolet pulse excitation light source emits excitation light, which is transmitted to the WDM wavelength division multiplexer. The central wavelength of the through arm of the WDM wavelength division multiplexer matches the excitation light, and the central wavelength of the reflection arm matches the central wavelength of the fluorescence. The excitation light enters the 45° inclined grating area through the through arm of the WDM wavelength division multiplexer. Each time it passes through a 45° inclined grating, a part of the excitation light is reflected. The reflected excitation light is incident on the fluorescent material to excite the fluorescence. The fluorescence is received by the 45° inclined grating, returned to the WDM wavelength division multiplexer, and reflected to the detector. The positioning of the inclined grating can be achieved through the emission and detection time difference of the pulse light. A time-correlated single-photon detector is used to enhance the signal-to-noise ratio of the system and to achieve the measurement of the fluorescence lifetime.

[0018] The distance between the detection point and the emission point is calculated according to the return time of the ultraviolet pulse excitation light, as shown in Formula 4. Combined with the 45° inclined grating string layout scheme, the detection position is obtained, thereby obtaining temperature data at different positions. By detecting and analyzing the fluorescence signals of multiple return times, the time division multiplexing of multiple gratings for the same set of acquisition systems is realized, so that multi-point temperature measurement can be achieved, and then the temperature distribution of the area to be measured can be drawn. The following is Formula 4:

[0019] Where Lm is the distance from the grating to the light source corresponding to the mth pulse, L m To time the pulses emitted from the laser, the time it takes for the mth pulse to return to the detector;

[0020] The detection position is obtained by calculating the time difference between the emission and return time of the ultraviolet pulse excitation light and the fluorescence receiving time. The detection results of different temperature measurement points are obtained by detecting the return time of the ultraviolet pulse excitation light at multiple 45° inclined gratings. The period calculation formula of the 45° inclined grating is:

[0021] Formula 1: Formula 2:

[0022] Where ∧1 corresponds to ultraviolet excitation light, ∧2 corresponds to fluorescence, λ1 is the central wavelength of ultraviolet excitation light, n1 is the refractive index of the fiber core under ultraviolet excitation light, λ2 is the central wavelength of fluorescence, and n2 is the refractive index of the fiber core under fluorescence.

[0023] Preferably, in step S1, the number of 45° tilted gratings to be written is determined based on the total length of the optical fiber and the temperature of the points to be monitored. When the temperature of 100 points needs to be monitored, 200 m of optical fiber is used, and one 45° tilted grating is written every 2 m. The optical fiber is a sapphire optical fiber. The spacing of the 45° tilted gratings is determined by the spatial resolution required for monitoring. The higher the spatial resolution requirement, the smaller the spacing between the two gratings.

[0024] Preferably, the WDM wavelength division multiplexer is used to make the passband of the direct light 200nm-300nm, and the passband of the coupled light 400nm-600nm, which is used to realize the input of excitation light and the detection of fluorescence. The 45° inclined grating adopts a double-period composite design, which is used for the input of 200nm-300nm ultraviolet excitation light and the reception of fluorescence in the spectral range of 400nm-600nm.

[0025] Preferably, in step S3, the fluorescent material includes but is not limited to inorganic fluorescent materials and organic fluorescent materials.

[0026] Beneficial Effects

[0027] Compared with the prior art, the present invention provides a distributed fluorescence temperature measurement method based on a 45° tilted grating, which has the following beneficial effects:

[0028] 1. The distributed fluorescence temperature measurement method based on 45° tilted grating uses 45° tilted grating design to enable ultraviolet pulse excitation light to efficiently excite fluorescent materials and reflect back to the optical fiber through the grating to achieve efficient collection of fluorescence signals. The lifetime of fluorescence has a functional relationship with temperature. Temperature measurement is achieved by detecting changes in fluorescence lifetime, which can provide high-precision temperature data. In addition, the 45° tilted grating with a double-period composite design can be used for both the input of ultraviolet excitation light and the reception of fluorescence, further improving the performance of the system. This distributed fluorescence temperature measurement method based on 45° tilted grating not only solves the limitations of traditional single-point temperature measurement technology, but also overcomes the problems of low signal-to-noise ratio and poor accuracy of distributed temperature measurement technology based on Raman effect, providing an effective solution for multi-point temperature monitoring in high temperature environments, which is of great significance for improving the safety of industrial equipment, optimizing process control and scientific research.

[0029] 2. This distributed fluorescence temperature measurement method based on 45° inclined grating improves the accuracy and signal-to-noise ratio of temperature measurement by designing and using 45° inclined grating strings and efficient fluorescent materials, overcoming the limitations of traditional temperature measurement technology in high temperature environments. At the same time, multi-point temperature monitoring is achieved through time-sharing solution of multiple gratings, solving the problem that traditional single-point temperature measurement technology is difficult to measure temperature fields, and can provide a complete temperature distribution map.

[0030] 3. This distributed fluorescence temperature measurement method based on a 45° tilted grating can be engraved on a sapphire optical fiber, making it particularly suitable for high-temperature environments, such as engine turbine blades, etc. It can ensure the tolerance and stability of the system at high temperatures, and the spacing of the 45° tilted grating is determined by the spatial resolution required for monitoring. The grating spacing can be adjusted according to demand to achieve high spatial resolution temperature monitoring.

[0031] 4. This distributed fluorescence temperature measurement method based on a 45° tilted grating measures the fluorescence lifetime through a time-correlated single-photon detector, which improves the detection accuracy and reliability of the system, can perform measurements at extremely low photon count rates, and reduce the impact of noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a double-period 45° tilted grating of the present invention;

[0033] Figure 2 is a typical curve diagram of fluorescence lifetime changing with temperature in the present invention;

[0034] Figure 3 This is a schematic diagram of a distributed fluorescence temperature measurement device based on a 45° tilted grating according to the present invention;

[0035] Figure 4 This is a schematic diagram of the time division multiplexing principle of multiple 45° tilted gratings of the present invention;

[0036] Figure 5 This is a diagram of the layout of the distributed fluorescence temperature measurement based on the 45° tilted grating of the present invention;

[0037] Figure 6 This is a diagram showing an example of temperature model calibration of the fluorescence lifetime of the present invention. DETAILED DESCRIPTION

[0038] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0039] A distributed fluorescence temperature measurement method based on a 45° tilted grating includes the following steps:

[0040] S1: Design a grating string consisting of multiple 45° tilted gratings on the same optical fiber. The number of 45° tilted gratings is determined by the number of monitoring points, where each 45° tilted grating corresponds to the temperature of a monitoring point. The interval of the 45° tilted gratings is determined by the required spatial resolution. For example, if the temperature of 100 points needs to be monitored, a 45° tilted grating is engraved every 2m on a 200m optical fiber. The 45° tilted grating can be arranged in a curved S shape. The measurement spatial resolution is determined by the arrangement points, such as Figure 5 As shown, the 45° tilted grating adopts a dual-period composite design, which enables it to be used for the input of ultraviolet excitation light (wavelength 200nm to 300nm) and the reception of fluorescence (wavelength 400nm to 600nm) at the same time. The period calculation formula of the 45° tilted grating is shown in Formula 1 and Formula 2: Formula 1: Formula 2: Taking the UV excitation light wavelength of 250nm and the fluorescence wavelength of 600nm as an example, the period of the 45° tilted grating can be designed to be 118nm and 287nm;

[0041] Among them, λ1 is the central wavelength of ultraviolet excitation light, n1 is the refractive index of the fiber core under ultraviolet excitation light, λ2 is the central wavelength of fluorescence, n2 is the refractive index of the fiber core under fluorescence, and the 45° tilted grating is arranged in two periods, such as Figure 1 As shown, the 45° tilted grating can simultaneously realize the emission of ultraviolet excitation light and the reception of fluorescence. The 45° tilted grating as described above is engraved at a certain interval on the same optical fiber and arranged in the temperature area to be measured to form a distributed temperature field measurement;

[0042] S2: Apply fluorescent material evenly on the outside of the 45° inclined grating area. The types of fluorescent materials available for the 45° inclined grating include inorganic fluorescent materials and organic fluorescent materials. These fluorescent materials have high temperature stability and can emit fluorescence under the excitation of ultraviolet light. Different fluorescent materials emit different wavelengths of fluorescence. For example, FITC fluorescein emits green fluorescence with a wavelength mainly at 518nm. The excited and emitted fluorescence will dissipate at a certain speed, and the lifetime of fluorescence is a monotonic function of temperature. Taking FITC fluorescein as an example, high temperature increases the non-radiative transition and The frequency of intermolecular collisions is increased, thereby reducing the probability of returning to the ground state through the radiation pathway. The fluorescence lifetime of FITC fluorescein is negatively correlated with temperature, that is, as the temperature increases, the fluorescence lifetime of FITC fluorescein gradually shortens. The 45° inclined grating coated with fluorescein is placed in an incubator, and the incubator temperatures are set at 20°C, 40°C, 60°C, 80°C, 100°C, and 120°C. The fluorescence lifetime is measured at different temperatures, and the temperature-lifetime curve of the fluorescein is plotted. The relationship between the lifetime τ(T) of the fluorescent material and the temperature T is shown in Formula 3: In this way, the activation energy ΔE and the material constants Rs and RT of the fluorescein are obtained;

[0043] Among them, ΔE is the activation energy, which determines the sensitivity of the fluorescence lifetime to temperature changes. For FITC fluorescein, the typical activation energy range is between 0.1-0.5 eV, and the actual value may vary depending on the experimental conditions and environment; k is the Boltzmann constant, which is 8.617×10 -5 eV / K; Rs, R T are constants related to the material, ΔE, Rs, R T It can be obtained by calibrating and fitting the measured life data at several temperature points (the number of temperature points is greater than 6). The typical life curve with temperature is as follows: Figure 2 As shown;

[0044] S3: Measurement scheme as Figure 3As shown, the ultraviolet pulse excitation light source emits excitation light, which is transmitted to the WDM wavelength division multiplexer. The central wavelength of the through arm of the WDM wavelength division multiplexer matches the excitation light, and the central wavelength of the reflection arm matches the central wavelength of the fluorescence. The excitation light enters the 45° inclined grating area through the through arm of the WDM wavelength division multiplexer. Each time it passes through a 45° inclined grating, a part of the excitation light will be reflected. The reflected excitation light is incident on the fluorescent material to excite the fluorescence. The fluorescence is received by the 45° inclined grating, returned to the WDM wavelength division multiplexer, and reflected to the detector. The positioning of the inclined grating can be achieved through the emission and detection time difference of the pulse light. In order to enhance the signal-to-noise ratio of the system, a time-correlated single-photon detector is used to measure the fluorescence lifetime. Using a time-correlated single-photon counter to measure the fluorescence lifetime is a very effective method, mainly because of its high precision, high sensitivity and reliability of data processing. Compared with other measurement methods, the single-photon detector can detect extremely low-intensity light signals, which enables fluorescence lifetime measurement to be performed at extremely low photon counting rates. By measuring the time difference between the trigger signal of the laser pulse and the arrival of the photon at the detector and fitting it with an exponential decay model, the influence of noise is reduced and the fluorescence lifetime parameters are extracted;

[0045] S4: In order to achieve multi-point temperature measurement, the distance between the detection point and the emission point is calculated according to the return time of the ultraviolet pulse excitation light, as shown in Formula 4: Combined with the 45° tilted grating string layout scheme, the detection position is obtained, so as to obtain the temperature data at different positions. By detecting and analyzing the fluorescence signals at multiple return times, the time division multiplexing of multiple 45° tilted gratings for the same set of acquisition systems is realized, which can realize multi-point temperature measurement and then draw the temperature distribution map of the area to be measured.

[0046] Among them, L m is the distance between the grating and the light source corresponding to the mth pulse, L m To time the pulse emitted from the laser, the time it takes for the mth pulse to return to the detector is Figure 4 As shown;

[0047] In addition, in order to improve the tolerance and stability of the system in high-temperature environments, the 45° tilted grating can be engraved on sapphire optical fiber using a femtosecond laser point-by-point writing method, making it particularly suitable for temperature monitoring in high-temperature fields such as engine turbine blades, and can provide temperature data with high precision and high spatial resolution. Specific embodiment:

[0049] A grating string consisting of 200 45° tilted gratings is designed on the same optical fiber. A 45° tilted grating is engraved every 2m on the 200m optical fiber. The 45° tilted grating can be arranged in a curved S shape. The measurement spatial resolution is determined by the arrangement points, such as Figure 5As shown, the grating adopts a dual-period composite design, so that it can be used for the input of ultraviolet excitation light (wavelength 200nm to 300nm) and the reception of fluorescence (wavelength 400nm to 600nm) at the same time. The calculation formula of the grating period is formula 1: Formula 2: Taking the ultraviolet excitation light wavelength of 250nm and the fluorescence wavelength of 600nm as an example, the period of the grating can be designed to be 118nm and 287nm;

[0050] If the 45° tilted grating is engraved on an ordinary communication optical fiber, the production of the 45° tilted grating can adopt the traditional 45° tilted grating production method based on the phase mask. The mask is also made with a double period. In order to improve the tolerance and stability of the system in a high temperature environment, the 45° tilted grating can be engraved on a sapphire optical fiber, making it suitable for high temperature fields such as engine turbine blades. The writing method is femtosecond laser point-by-point writing.

[0051] Select a fluorescent material with high temperature stability, such as fluorescein, which emits green fluorescence (wavelength of 518nm) under ultraviolet light excitation. Apply fluorescein evenly on the outside of the 45° inclined grating area to ensure good contact between the fluorescent material and the optical fiber surface to ensure effective excitation and reception of fluorescence. Place the 45° inclined grating coated with fluorescein in an incubator, set the incubator temperature to 20℃, 40℃, 60℃, 80℃, 100℃, and 120℃, measure the lifetime of fluorescence at different temperatures, and draw the temperature-lifetime curve of the fluorescein using Formula 3: The activation energy ΔE, Rs, and R of the fluorescein were obtained by fitting. T Material constants, for example, the fluorescence lifetime measured at different temperatures is shown in the table:

[0052]

[0053]

[0054] Plotting the life curve of temperature as Figure 6 As shown, using the least squares fitting method of formula 3, we can get ΔE = 0.16 eV, Rs = 6.64, RT = -0.79, which is substituted into formula 3 to obtain the temperature-lifetime model of the fluorescein as formula 5:

[0055] Place the grating string coated with fluorescent material on the object to be measured, such as Figure 5 As shown, the layout location and density are determined according to the temperature measurement points that the user is concerned about;

[0056] By measuring the change of fluorescence lifetime and substituting it into the formula 5 with filled parameters to calculate the temperature change, the time-correlated single-photon detector is used to achieve high-precision measurement of fluorescence lifetime, and the positioning of the tilted grating is achieved through the emission and detection time difference of pulse light. The positioning formula is as follows: For example, when the time difference between laser emission and return is 1ns, the demodulated grating is 1m away from the light source. By detecting and analyzing the fluorescence signals at multiple return times, the temperature data at different positions can be obtained and the temperature distribution map of the area to be measured can be drawn.

[0057] Through the above steps and methods, high-precision, high signal-to-noise ratio multi-point temperature measurement is achieved, which effectively solves the problem that traditional single-point temperature measurement technology is difficult to achieve distributed temperature field measurement, and improves the signal-to-noise ratio and accuracy of distributed temperature measurement technology based on the Raman effect. The above specific implementation methods describe in detail the design principles, implementation methods and application effects of the present invention, and demonstrate the significant advantages of the present invention in multi-point distributed temperature monitoring under high temperature environments.

[0058] The present invention provides a high-precision, high signal-to-noise ratio multi-point temperature measurement method by designing and utilizing a combination of a 45° tilted grating and a fluorescent material. The method can effectively solve the problem that traditional single-point temperature measurement technology is difficult to achieve distributed temperature field measurement, and the problem that distributed temperature measurement technology based on the Raman effect has a low signal-to-noise ratio and poor accuracy. The present invention is of great significance for industrial equipment monitoring, scientific research and process control in high-temperature environments.

[0059] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A distributed fluorescence temperature measurement method based on a 45° tilted grating, characterized in that: The steps include: S1: Design and manufacture a 45° tilted grating string: prepare optical fiber and 45° tilted grating, write multiple 45° tilted gratings on the same optical fiber at a certain interval, and the optical fiber can be bent and coiled; S2: Apply fluorescent material on the outside of the 45° inclined grating; S3: The fluorescent material coated on the 45° inclined grating is excited by ultraviolet pulse excitation light to emit fluorescence, and the 45° inclined grating coated with fluorescent material is placed in an incubator, and the incubator temperature is set at 20°C, 40°C, 60°C, 80°C, 100°C, and 120°C, and the fluorescence lifetime is measured at different temperatures; S4: Allow the fluorescence to return to the optical fiber through a 45° tilted grating; S5: Detect the lifetime of fluorescence and realize temperature measurement based on the functional relationship between the lifetime of the fluorescent material and the temperature. The relationship between the lifetime τ(T) of the fluorescent material and the temperature T is as follows: Formula 1: Where ΔE is the activation energy, which determines the sensitivity of the fluorescence lifetime to temperature changes; k is the Boltzmann constant, which is 8.617×10 -5 eV / K; Rs, R T are constants related to the material; ΔE, Rs, R T It can be obtained by calibrating and fitting the measured life data with more than 6 temperature points; S6: preparing an ultraviolet pulse excitation light source, a WDM wavelength division multiplexer, a detector, and a single photon detector, wherein the WDM wavelength division multiplexer includes a through arm and a reflection arm; The ultraviolet pulse excitation light source emits excitation light, which is transmitted to the WDM wavelength division multiplexer. The central wavelength of the through arm of the WDM wavelength division multiplexer matches the excitation light, and the central wavelength of the reflection arm matches the central wavelength of the fluorescence. The excitation light enters the 45° inclined grating area through the through arm of the WDM wavelength division multiplexer. Each time it passes through a 45° inclined grating, a part of the excitation light is reflected. The reflected excitation light is incident on the fluorescent material to excite the fluorescence. The fluorescence is received by the 45° inclined grating, returned to the WDM wavelength division multiplexer, and reflected to the detector. The positioning of the inclined grating can be achieved through the emission and detection time difference of the pulse light. A time-correlated single-photon detector is used to enhance the signal-to-noise ratio of the system and to achieve the measurement of the fluorescence lifetime. The distance between the detection point and the emission point is calculated according to the return time of the ultraviolet pulse excitation light, as shown in Formula 4. Combined with the 45° inclined grating string layout scheme, the detection position is obtained, thereby obtaining temperature data at different positions. By detecting and analyzing the fluorescence signals of multiple return times, the time division multiplexing of multiple gratings for the same set of acquisition systems is realized, so that multi-point temperature measurement can be achieved, and then the temperature distribution of the area to be measured can be drawn. The following is Formula 4: Where Lm is the distance from the grating to the light source corresponding to the mth pulse, L m To time the pulses emitted from the laser, the time it takes for the mth pulse to return to the detector; The detection position is obtained by calculating the time difference between the emission and return time of the ultraviolet pulse excitation light and the fluorescence receiving time. The detection results of different temperature measurement points are obtained by detecting the return time of the ultraviolet pulse excitation light at multiple 45° inclined gratings. The period calculation formula of the 45° inclined grating is: Formula 2: Formula 3: Where ∧1 corresponds to ultraviolet excitation light, ∧2 corresponds to fluorescence, λ1 is the central wavelength of ultraviolet excitation light, n1 is the refractive index of the fiber core under ultraviolet excitation light, λ2 is the central wavelength of fluorescence, and n2 is the refractive index of the fiber core under fluorescence.

2. The distributed fluorescence temperature measurement method based on a 45° tilted grating according to claim 1 is characterized in that: In step S1, the number of 45° tilted gratings to be written is determined based on the total length of the optical fiber and the temperature of the points to be monitored. When the temperature of 100 points needs to be monitored, 200m of optical fiber is used, and a 45° tilted grating is written every 2m. The optical fiber is sapphire optical fiber. The spacing of the 45° tilted gratings is determined by the spatial resolution required for monitoring. The higher the spatial resolution requirement, the smaller the spacing between the two gratings.

3. The distributed fluorescence temperature measurement method based on a 45° tilted grating according to claim 1 is characterized in that: The WDM wavelength division multiplexer is used to make the pass band of the direct light 200nm-300nm, and the pass band of the coupled light 400nm-600nm, which is used to realize the input of excitation light and the detection of fluorescence. The 45° inclined grating adopts a double-period composite design, which is used for the input of 200nm-300nm ultraviolet excitation light and the reception of fluorescence in the spectral range of 400nm-600nm.

4. The distributed fluorescence temperature measurement method based on a 45° tilted grating according to claim 1 is characterized in that: In step S3, the fluorescent material includes but is not limited to inorganic fluorescent materials and organic fluorescent materials.

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