High-temperature femtosecond fiber grating temperature measuring device and anti-interference temperature measuring method

Abstract

A high-temperature femtosecond fiber grating temperature measuring device disclosed by the present invention comprises a packaging substrate of a T-shaped structure, the packaging substrate is provided with an installation surface used for being installed on an electrolytic aluminum tank tab, the packaging substrate is provided with installation parts perpendicular to the installation surface at intervals, and a femtosecond fiber grating is embedded in each installation part. The part, penetrating out of the packaging base body, of the femtosecond fiber grating is sleeved with a ceramic fiber buffer sleeve, and the packaging base body is filled with a boron nitride sealant layer located between the two installation parts. The femtosecond fiber grating packaging structure can be applied to electrolytic aluminum tank tabs in complex environments of long-term high temperature, corrosive gas and mechanical vibration.

Description

Technical Field

[0001] This invention relates to the field of aluminum electrolytic cell tab temperature monitoring technology, and in particular to a high-temperature femtosecond fiber optic grating temperature measuring device and an anti-interference temperature measuring method. Background Technology

[0002] During operation, the tab area of ​​an aluminum electrolytic cell is prone to significant localized high temperatures due to the long-term bearing of high current density and accompanying complex electrochemical reactions. Under industrial operating conditions, the current density in the tab area can typically reach over 1.0 A / cm², and the surface and internal local temperatures can rise to 300℃~400℃, potentially increasing further under abnormal operating conditions or heat accumulation. Changes in tab temperature directly affect the conductivity, structural safety, and service life of the electrolytic cell; therefore, long-term, stable, and accurate monitoring of the tab temperature is of significant engineering importance.

[0003] Currently, electrode temperature monitoring mainly employs traditional methods such as thermocouples and infrared thermometry. Thermocouples are susceptible to interference in strong electromagnetic fields, resulting in poor signal stability. Furthermore, under long-term high-temperature conditions (>300℃), the sensor lifespan is typically short, making it difficult to meet the requirements of continuous operation in electrolytic aluminum tanks. Additionally, it cannot achieve multi-point or distributed measurements. Infrared thermometry is highly dependent on the condition of the measured surface. When the electrode surface has an oxide layer, dust coverage, or geometric obstructions, the measurement error can typically reach ±5℃ or even higher. The measurement results are easily affected by environmental changes, making it difficult to meet the requirements for refined monitoring.

[0004] Distributed fiber optic temperature measurement technology has been increasingly applied in high-temperature industrial monitoring due to its advantages such as strong resistance to electromagnetic interference, ability to achieve continuous multi-point measurement, and suitability for long-distance monitoring. However, the tabs of electrolytic aluminum tanks are exposed to a complex environment with high temperatures, corrosive gases, and mechanical vibrations for extended periods. Existing fiber optic packaging structures still have shortcomings in terms of temperature resistance, mechanical protection, and environmental adaptability, which can easily lead to fiber damage, signal attenuation, or measurement distortion, thus limiting the engineering application of distributed fiber optic temperature measurement technology under tab conditions. Summary of the Invention

[0005] (a) Technical issues

[0006] The purpose of this invention is to provide a high-temperature femtosecond fiber grating temperature measurement device and an anti-interference temperature measurement method, so as to enable the femtosecond fiber grating packaging structure to meet the requirements of application in complex environments such as long-term high temperature, corrosive gas and mechanical vibration of electrolytic aluminum tank tabs.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A high-temperature femtosecond fiber Bragg grating temperature measurement device includes a T-shaped encapsulation substrate. The encapsulation substrate has a mounting surface for mounting onto an electrolytic aluminum tank tab. Mounting portions perpendicular to the mounting surface are spaced apart on the encapsulation substrate. A femtosecond fiber Bragg grating is embedded in each mounting portion. A ceramic fiber buffer sleeve is fitted over the portion of the femtosecond fiber Bragg grating that protrudes from the encapsulation substrate. The encapsulation substrate is filled with a boron nitride sealant layer located between two mounting portions.

[0010] Furthermore, the femtosecond fiber grating array is coiled inside the mounting portion, and the spacing between adjacent femtosecond fiber gratings is 10mm-50mm.

[0011] Furthermore, the array of femtosecond fiber gratings is wound 10 times, and the spacing between adjacent femtosecond fiber gratings is 20 mm.

[0012] Furthermore, the array-wound femtosecond fiber grating is coated with a polyimide nano-alumina composite coating with a thickness of 50±5μm.

[0013] Furthermore, the thermal conductivity of the boron nitride sealant layer is ≥35 W / m·K.

[0014] Furthermore, the encapsulation substrate includes a top plate, on which an L-shaped left side plate and a right side plate are mounted. Optical fiber slots are formed on the opposing inner surfaces of the left and right side plates, and the femtosecond fiber Bragg grating array is wound within the optical fiber slots. Cover plates for sealing the optical fiber slots are provided on both the left and right side plates. A bottom plate is fixed to the bottom of the left and right side plates. The top plate, the bottom plate, the left side plate, and the right side plate enclose a cavity, and the boron nitride sealant layer fills the cavity. The mounting surface is located on the top plate.

[0015] Furthermore, the bottom of the cover plate is provided with cable outlet grooves at intervals, and the bottom plate is provided with cable through holes corresponding to the cable outlet grooves. The through portions of the femtosecond fiber gratings on both sides pass through the cable outlet grooves and cable through holes in sequence.

[0016] Furthermore, the top plate, the bottom plate, the left side plate, and the right side plate are all made of alloy material.

[0017] This invention also proposes an interference-resistant temperature measurement method, comprising:

[0018] Multiple high-temperature femtosecond fiber Bragg grating temperature measuring devices are connected in series and installed on the tabs of the electrolytic aluminum tank.

[0019] Acquire optical signals generated by the change in tab temperature of femtosecond fiber gratings;

[0020] The optical signal is transmitted to the fiber optic splitter and signal aggregation unit after dynamic wavelength compensation.

[0021] The fiber optic splitter and signal aggregation unit aggregates optical signals from multiple point temperature sensors and transmits the aggregated signals to the sensor demodulation device in the temperature demodulation and data processing unit.

[0022] The received optical signal is demodulated by a sensor demodulation device to obtain the electrode temperature information at the corresponding temperature measurement location.

[0023] The electrode temperature information is uploaded to the control center.

[0024] Furthermore, multiple high-temperature femtosecond fiber optic grating temperature measuring devices are symmetrically installed on the tabs of the electrolytic aluminum tank. The temperature measuring points are located by laser calibration, covering the welding joints of the tabs and areas with poor heat dissipation.

[0025] (III) Beneficial Effects

[0026] The femtosecond fiber grating is encapsulated in a T-shaped packaging substrate to form a modular structure, which facilitates installation on the electrolytic aluminum bath tab. The mounting surface ensures reliable installation and positioning of the entire modular structure. The mounting parts of the encapsulated femtosecond fiber grating are spaced apart and set perpendicular to the mounting surface. This avoids excessive temperature changes in the femtosecond fiber grating and ensures stability during temperature measurement. The boron nitride sealant layer inside achieves heat balance between the two mounting parts, thus minimizing the difference in optical signals of the femtosecond fiber gratings on both sides based on temperature changes. The protruding parts are protected by a ceramic fiber buffer sleeve. This enables the entire device to achieve stable temperature measurement in the complex environment of long-term high temperature, corrosive gas, and mechanical vibration of the electrolytic aluminum bath tab.

[0027] Meanwhile, by applying the temperature measuring device to the temperature measurement method in the electrode temperature measurement process, the optical signal detected during the temperature measurement process is made anti-interference, and the obtained electrode temperature information is more stable. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0029] Figure 2 This is a cross-sectional structural diagram of an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the exploded structure according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the structure of the left and right side plates according to an embodiment of the present invention;

[0032] Figure 5This is a schematic diagram of the anti-interference temperature measurement method of the present invention;

[0033] exist Figures 1 to 5 In the diagram, the correspondence between component names or lines and the drawing numbers is as follows:

[0034] 1. Encapsulation substrate; 2. Mounting surface; 3. Mounting part; 4. Top plate; 5. Left side plate; 6. Right side plate; 7. Fiber optic tray; 8. Cover plate; 9. Bottom plate; 10. Cavity; 11. Outlet slot; 12. Through hole. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0036] See Figures 1-4As shown, an embodiment of the present invention proposes a high-temperature femtosecond fiber optic grating temperature measurement device, comprising a T-shaped encapsulation substrate 1. The encapsulation substrate 1 has a mounting surface 2 for mounting onto the tabs of an electrolytic aluminum tank. The mounting surface 2 enables the entire temperature measurement device to be positioned and installed, directly conducting the temperature of the tabs. Mounting portions 3 perpendicular to the mounting surface 2 are spaced apart on the encapsulation substrate 1. Each mounting portion 3 is embedded with a femtosecond fiber optic grating. The portion of the femtosecond fiber optic grating extending out of the encapsulation substrate 1 is fitted with a ceramic fiber buffer sleeve. The interior of the encapsulation substrate 1 is filled with a boron nitride sealant layer located between two mounting portions 3. The filling of the interior with the boron nitride sealant layer ensures temperature uniformity between the two mounting portions 3. The thermal conductivity of the boron nitride sealant layer is ≥35. The heat dissipation capacity is W / m·K, ensuring good thermal conductivity. A continuous, high-thermal-conductivity heat diffusion channel is formed within the encapsulation substrate 1, promoting lateral heat diffusion and homogenization between the two mounting portions 3. This reduces the temperature difference between the two mounting portions 3 and improves the consistency of synchronous temperature measurement, resulting in a more consistent trend in the center wavelength drift of the femtosecond fiber gratings on both sides due to temperature changes. It should be noted that in actual working conditions where the mounting surface 2 serves as the heat input interface and there are heat dissipation boundary conditions on the outer surface, the temperature at the two mounting portions 3 may differ. The boron nitride sealant layer serves to reduce this difference and improve consistency, rather than ensuring that the two temperatures are absolutely identical under any working condition. Regarding the filling process, the boron nitride sealant can be degassed first, and the cavity filling can be completed using a low-level slow injection method combined with an upper-level venting channel. After curing, a continuous and dense thermally conductive filling layer is formed to reduce the impact of bubble defects and interface thermal resistance on thermal conductivity consistency. The fiber optic cable exiting the optical fiber is protected by a ceramic fiber buffer sleeve, which provides thermal insulation and mechanical buffering for the exposed fiber optic cable. This reduces the risk of micro-bending loss, coating aging or breakage caused by high-temperature radiation, vibration friction and external impacts, thereby improving the reliability and stability of temperature measurement of the entire device in complex environments such as long-term high temperature, corrosive gases and mechanical vibration in the electrolytic aluminum cell tab.

[0037] After the temperature of the tab is conducted through the mounting surface 2 to the two mounting parts 3 and reaches a uniform temperature, the femtosecond fiber grating generates an optical signal due to the temperature change. During the outward transmission, the ceramic fiber buffer sleeve protects the protruding part (protection against high temperature, vibration, etc.), thereby effectively avoiding interference.

[0038] The entire temperature measuring device has a modular structure, which can be installed and arranged according to the temperature measuring points. Two femtosecond fiber gratings are integrated in each temperature measuring device, and the temperature measurement is balanced by using a boron nitride sealant layer. This ensures stable temperature measurement in the complex environment of long-term high temperature, corrosive gas and mechanical vibration of the electrolytic aluminum tank tab, and the temperature measurement data has small differences.

[0039] In addition, by using mounting surface 2 to directly install onto the electrode tab for contact temperature measurement, the temperature measurement accuracy is higher.

[0040] The femtosecond fiber grating array is coiled inside the mounting part 3, with a spacing of 10mm-50mm between adjacent femtosecond fiber gratings. To ensure the accuracy of the measurement data, the array of femtosecond fiber gratings is coiled 10 times, with a spacing of 20mm between adjacent femtosecond fiber gratings, thus balancing measurement accuracy and space utilization.

[0041] The femtosecond fiber grating uses a femtosecond direct-write type II fiber grating, formed by point-by-point direct writing with a 1030nm femtosecond laser to meet the thermal stability requirements of the tab under long-term high-temperature environments. Each package substrate 1 contains one femtosecond fiber grating on each side: the left grating has a center wavelength of 1528.6nm, an edge-mode rejection ratio of 27.3dB, a reflectivity of 83%, a 3dB bandwidth of 0.34nm, and a length of 3mm; the right grating has a center wavelength of 1543.3nm, an edge-mode rejection ratio of 28.5dB, a reflectivity of 79%, a 3dB bandwidth of 0.32nm, and a length of 3mm. The temperature sensitivity coefficient of the femtosecond fiber grating is 13.8pm / ℃, and the center wavelength exhibits an approximately linear relationship with temperature change within the range of room temperature to 600℃; there is no significant change in temperature sensitivity before and after packaging.

[0042] Meanwhile, a polyimide nano-alumina composite coating with a thickness of 50±5μm is coated on the femtosecond fiber grating coiled in the array; this further ensures the high temperature resistance and mechanical strength of the femtosecond fiber grating, and significantly improves key properties such as heat resistance, mechanical properties, corona resistance, and corrosion resistance, enabling the grating to adapt to the working environment of the tab.

[0043] Specifically, the encapsulation substrate 1 includes a top plate 4, on which an L-shaped left side plate 5 and a right side plate 6 are mounted. Fiber optic slots 7 are formed on the inner surfaces of the left side plate 5 and the right side plate 6, respectively. The femtosecond fiber grating array is coiled within the fiber optic slots 7. The fiber optic slots 7 are used to coil and place the femtosecond fiber grating. After coiling, cover plates 8 are provided on both the left side plate 5 and the right side plate 6 to close the fiber optic slots 7. The cover plates 8 are attached to the left side plate 5 and the right side plate 6 to form a seal inside. At the same time, a bottom plate 9 is fixed to the bottom of the left side plate 5 and the right side plate 6. A cavity 10 is formed by the top plate 4, the bottom plate 9, the left side plate 5, and the right side plate 6. The boron nitride sealant layer fills the cavity 10, and the mounting surface 2 is located on the top plate 4. The top plate 4 directly contacts the tab for heat conduction, and the temperature is evenly conducted to the femtosecond fiber gratings on both sides through the boron nitride sealant layer, so as to achieve relatively stable temperature measurement.

[0044] The T-shaped structure of the encapsulation substrate 1 facilitates positioning and installation on the tabs and also establishes a clear load transfer path: after the mounting surface 2 is attached to the tabs, external vibration loads are mainly transferred to the overall structure of the encapsulation substrate 1 via the top plate 4. This load is borne by the frame structure formed by the top plate 4, left side plate 5, right side plate 6, and bottom plate 9, thereby reducing local stress concentration at the mounting section 3. The mounting sections 3 are spaced apart and integrally connected to the encapsulation substrate 1. The mounting sections 3 are surrounded by a cured boron nitride sealant layer, providing support and damping, which helps suppress relative displacement and stress cycling under long-term vibration, reducing the risk of fatigue failure. The mounting surface 2 serves as the main heat input interface. The vertical arrangement of the mounting sections 3 ensures that the temperature-sensing area of ​​the femtosecond fiber grating is heated along the main heat conduction direction, reducing non-uniform heating caused by lateral temperature gradients, local thermal shocks, and changes in mounting posture. Simultaneously, the mounting sections 3 provide geometric support for the femtosecond fiber grating, which helps reduce the coupling between external vibrations and additional mechanical stresses, thereby improving the stability and repeatability of the wavelength-temperature response.

[0045] To facilitate the exit of femtosecond fiber Bragg gratings, exit grooves 11 are provided at intervals at the bottom of the cover plate 8, and through holes 12 corresponding to the exit grooves 11 are provided on the base plate 9. The exit portions of the femtosecond fiber Bragg gratings on both sides pass through the exit grooves 11 and through holes 12 in sequence and then connect to external devices. This does not affect the internal filling of the boron nitride sealant layer, and allows for convenient exit, with the exit portions used for external communication connections.

[0046] Furthermore, the routing and coiling of the optical fiber inside the encapsulation substrate 1 can be achieved as follows: After entering through the through hole 12 on one side, the optical fiber enters the fiber coiling groove 7 inside the left side plate 5 or the right side plate 6 through the corresponding exit groove 11 for coiling, and then exits through another exit groove 11 and through hole 12, achieving close proximity of the optical fiber exit on both sides and a compact structural arrangement. The optical fiber coiled in the fiber coiling groove 7 is filled and fixed with a high-temperature curing agent or high-temperature adhesive to improve the structural stability under high temperature and mechanical vibration conditions. To avoid introducing additional stress or optical loss during coiling, routing, and bending, the minimum bending radius of the optical fiber in the coiling, routing, and bending areas is not less than 30mm. To ensure the accuracy of the femtosecond fiber grating temperature sensing, the optical fiber inside the encapsulation substrate 1 (including the grating temperature sensing coiling section and crossing section) is not additionally sleeved; only the exposed part that protrudes from the encapsulation substrate 1 is sleeved with a ceramic fiber buffer sleeve to form high temperature and vibration protection.

[0047] Specifically, the top plate 4, the bottom plate 9, the left side plate 5, and the right side plate 6 are all made of alloy material, which further ensures the structural stability and structural strength of the entire encapsulation substrate 1.

[0048] Therefore, by winding the two femtosecond fiber grating arrays for synchronous temperature measurement inside the packaging substrate 1 to form an integral structure, it is easy to install according to the temperature measurement point. At the same time, the boron nitride sealant layer ensures the uniformity of the temperature measurement of the two femtosecond fiber gratings. While ensuring structural stability and adapting to high temperature and vibration environments, the measurement stability and accuracy are improved.

[0049] Based on the above implementation methods, such as Figure 5 As shown, the present invention also proposes an interference-resistant temperature measurement method, comprising:

[0050] S01. Connect multiple high-temperature femtosecond fiber optic grating temperature measuring devices in series and install them onto the tabs of the electrolytic aluminum tank.

[0051] Generally, eight high-temperature femtosecond fiber optic temperature measuring devices are symmetrically installed on the tabs of the electrolytic aluminum tank, and the temperature measuring points are located by laser calibration. The temperature measuring points cover the welding joints of the tabs and the poor heat dissipation areas, such as the top window area of ​​the tabs and the tab connection area, so that the temperature measurement results can reflect the true temperature distribution of the tabs.

[0052] S02. Acquire the optical signal generated by the femtosecond fiber grating as the tab temperature changes.

[0053] Temperature changes induce changes in the period of the femtosecond fiber grating and the refractive index of the fiber, which in turn causes a shift in the center wavelength of the reflected / transmitted light. The temperature value can be accurately calculated by detecting the amount of wavelength shift. The optical signal here is the wavelength shift.

[0054] S03. After dynamic wavelength compensation, the optical signal is transmitted to the fiber optic splitter and signal aggregation unit. Dynamic compensation eliminates wavelength deviations caused by non-temperature factors such as electromagnetic interference and fluctuations in the fiber optic transmission environment, ensuring that the transmitted optical signal accurately corresponds to the actual temperature changes of the tab.

[0055] Dynamic wavelength compensation uses a reference fiber (reference channel) to obtain the wavelength drift caused by non-temperature factors as the compensation amount, and establishes a compensation model (fitting compensation coefficients / relationships) through calibration experiments to correct the temperature measurement optical signal to reduce errors. It is one of the commonly used methods for fiber optic transmission compensation.

[0056] S04, the fiber optic splitter and signal aggregation unit, aggregates optical signals from multiple point-type temperature sensors and transmits the aggregated signal to the sensor demodulation device in the temperature demodulation and data processing unit. This integrates the multiple optical signals from eight temperature measurement points, achieving centralized and unified transmission, reducing signal loss over long distances, and improving the efficiency of subsequent demodulation processing.

[0057] S05. The received optical signal is demodulated using a sensor demodulation device to obtain the tab temperature information at the corresponding temperature measurement location. The demodulation device converts the acquired wavelength offset optical signal into a specific temperature value and synchronously outputs the tab temperature data for each temperature measurement point.

[0058] S06. Upload the electrode temperature information to the control center. Upload the processed temperature data from each measuring point to the backend to facilitate real-time monitoring of the electrode temperature distribution and timely warning of abnormal high temperature risks.

[0059] The temperature measurement method, which applies a temperature measuring device to the electrode temperature measurement process, can effectively suppress interference in complex field environments, ensuring the stability of the demodulated electrode temperature information. Furthermore, after calibration comparison before and after packaging, the temperature response characteristics of the femtosecond fiber grating remain consistent, the center wavelength-temperature relationship remains approximately linear, and the temperature sensitivity does not change. This indicates that the packaging structure does not adversely affect the temperature measurement characteristics, thus guaranteeing the consistency and repeatability of this temperature measurement method in practical applications.

[0060] The above method can connect a high-temperature femtosecond fiber optic grating temperature measuring device in series with the temperature measuring system, compensate the collected optical signal and convert it into corresponding temperature information, and then transmit the temperature information. The process of converting optical signals into temperature information is a mature technology, and all components, units and devices involved are mature products. This embodiment applies the improved high-temperature femtosecond fiber optic grating temperature measuring device to the existing temperature measuring method to achieve an interference-resistant temperature measurement process.

[0061] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0063] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-temperature femtosecond fiber optic grating temperature measurement device, characterized in that: The package includes a T-shaped encapsulation substrate (1), which has a mounting surface (2) for mounting onto an electrolytic aluminum tank tab. The encapsulation substrate (1) is provided with mounting portions (3) spaced apart from the mounting surface (2). Each mounting portion (3) is embedded with a femtosecond fiber grating. The portion of the femtosecond fiber grating that extends out of the encapsulation substrate (1) is fitted with a ceramic fiber buffer sleeve. The encapsulation substrate (1) is filled with a boron nitride sealant layer located between two mounting portions (3).

2. The high-temperature femtosecond fiber optic grating temperature measuring device according to claim 1, characterized in that: The femtosecond fiber grating array is coiled inside the mounting part (3), and the spacing between adjacent femtosecond fiber gratings is 10mm-50mm.

3. The high-temperature femtosecond fiber optic grating temperature measuring device according to claim 2, characterized in that: The array of femtosecond fiber gratings is wound 10 times, and the spacing between adjacent femtosecond fiber gratings is 20 mm.

4. The high-temperature femtosecond fiber optic grating temperature measuring device according to claim 3, characterized in that: The array of femtosecond fiber gratings is coated with a polyimide nano-alumina composite coating with a thickness of 50±5μm.

5. The high-temperature femtosecond fiber optic grating temperature measuring device according to claim 1, characterized in that: The thermal conductivity of the boron nitride sealant layer is ≥35 W / m·K.

6. A high-temperature femtosecond fiber optic grating temperature measuring device according to any one of claims 1-5, characterized in that: The encapsulation substrate (1) includes a top plate (4), on which an L-shaped left side plate (5) and a right side plate (6) are mounted. Optical fiber slots (7) are opened on the inner sides of the left side plate (5) and the right side plate (6), and the femtosecond fiber grating array is coiled in the optical fiber slots (7). Both the left side plate (5) and the right side plate (6) are provided with cover plates (8) for closing the fiber optic tray (7); The bottom of the left side plate (5) and the right side plate (6) are fixed with a base plate (9); The top plate (4), the bottom plate (9), the left side plate (5) and the right side plate (6) enclose a cavity (10), and the boron nitride sealant layer fills the cavity (10); The mounting surface (2) is located on the top plate (4).

7. The high-temperature femtosecond fiber optic grating temperature measuring device according to claim 6, characterized in that: The bottom of the cover plate (8) is provided with a wire outlet groove (11) at intervals, and the bottom plate (9) is provided with a wire through hole (12) corresponding to the wire outlet groove (11). The protruding parts of the femtosecond fiber gratings on both sides pass through the wire outlet groove (11) and the wire through hole (12) in sequence.

8. The high-temperature femtosecond fiber optic grating temperature measuring device according to claim 6, characterized in that: The top plate (4), the bottom plate (9), the left side plate (5), and the right side plate (6) are all made of alloy material.

9. An anti-interference temperature measurement method, characterized in that, include: Multiple high-temperature femtosecond fiber optic grating temperature measuring devices as described in any one of claims 1-8 are connected in series and installed on the tabs of an electrolytic aluminum tank. Acquire optical signals generated by the change in tab temperature of femtosecond fiber gratings; The optical signal is transmitted to the fiber optic splitter and signal aggregation unit after dynamic wavelength compensation. The fiber optic splitter and signal aggregation unit aggregates optical signals from multiple point temperature sensors and transmits the aggregated signals to the sensor demodulation device in the temperature demodulation and data processing unit. The received optical signal is demodulated by a sensor demodulation device to obtain the electrode temperature information at the corresponding temperature measurement location. The electrode temperature information is uploaded to the control center.

10. The anti-interference temperature measurement method according to claim 9, characterized in that: Multiple high-temperature femtosecond fiber optic grating temperature measuring devices are symmetrically installed on the tabs of the electrolytic aluminum tank. The temperature measuring points are located by laser calibration, covering the welding joints of the tabs and the areas with poor heat dissipation.

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