Temperature monitoring method

Abstract

The invention relates to the technical field of temperature monitoring, in particular to a temperature monitoring method, which comprises the following steps of: dividing acquired initial data according to wave bands to obtain an FBG data segment and a direct band gap semiconductor data segment; performing comparative analysis on the FBG data segment and the FBG segment temperature-wavelength curve to obtain a first temperature; comparing and analyzing the direct band gap semiconductor data segment and the direct band gap semiconductor segment temperature-wavelength curve to obtain a second temperature; and fitting the first temperature and the second temperature to obtain temperature data. According to the invention, rough temperature positioning is obtained by analyzing the FBG data segment, the problems of possible overlapping and difficult distinguishing of the interference spectrum in wide temperature segment measurement are solved, and the second temperature obtained by analyzing the direct band gap semiconductor data segment is used for carrying out refined compensation on the temperature measurement result of the first temperature. And high-resolution and high-precision temperature measurement is realized in a wide temperature measurement range.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature monitoring, and particularly relates to a temperature monitoring method. Background Art

[0002] In the field of fiber optic sensing technology, temperature monitoring is a crucial application direction. With the continuous improvement of the requirements for temperature monitoring accuracy and response speed in industries, aerospace, energy, scientific research and other fields, traditional temperature monitoring methods have been difficult to meet these high-performance requirements. Therefore, the development of new high-speed and high-precision fiber optic temperature monitoring methods has become a current research hotspot.

[0003] Fiber Bragg grating (FBG), as a mature fiber optic sensing technology, has been widely used in the field of temperature monitoring due to its advantages such as high sensitivity, anti-electromagnetic interference, and easy multiplexing. The temperature response characteristic of FBG mainly shows that there is a certain linear relationship between the change of its reflection wavelength and temperature. By measuring the reflection wavelength of FBG, accurate temperature measurement can be achieved. However, FBG sensors are vulnerable to interference and have great limitations, making it difficult to achieve accurate temperature measurement in complex and variable environments. Summary of the Invention

[0004] (I) Object of the Invention

[0005] The object of the present invention is to provide a temperature monitoring method that can achieve high-precision temperature measurement within a wide temperature measurement range.

[0006] (II) Technical Solution

[0007] To solve the above problems, the present invention provides a temperature monitoring method, including:

[0008] Dividing the collected initial data according to the wavelength band to obtain an FBG data segment and a direct bandgap semiconductor data segment;

[0009] Comparing and analyzing the FBG data segment with the FBG segment temperature-wavelength curve to obtain the first temperature;

[0010] Comparing and analyzing the direct bandgap semiconductor data segment with the direct bandgap semiconductor segment temperature-wavelength curve to obtain the second temperature;

[0011] Fitting the first temperature and the second temperature to obtain temperature data.

[0012] On the other hand, preferably, the FBG segment temperature-wavelength curve is obtained through the following steps:

[0013] Using a peak searching algorithm to obtain the peak wavelength of the FBG reflection spectrum at different first experimental temperatures;

[0014] Perform linear fitting on the first experimental temperature and the peak wavelength of the FBG reflection spectrum to obtain the temperature-wavelength curve of the FBG section.

[0015] On the other hand, preferably, the temperature-wavelength curve of the direct bandgap semiconductor section is obtained through the following steps:

[0016] For the Fabry-Perot cavity formed by the direct bandgap semiconductor crystal, a reflective film is set at the reflection end of the direct bandgap semiconductor crystal to obtain reflection spectrum data at different second experimental temperatures;

[0017] Extract the interference spectrum drift amount in the reflection spectrum data;

[0018] Use a standard thermometer to calibrate the actual temperature data to obtain calibrated temperature data;

[0019] Based on the calibrated temperature data and the interference spectrum drift amount, obtain the temperature-wavelength curve of the direct bandgap semiconductor section.

[0020] On the other hand, preferably,

[0021] Perform preprocessing on the obtained reflection spectrum data, and the preprocessing includes:

[0022] Denoise the reflection spectrum data through quadratic Gaussian filtering to obtain a discrete reflection data spectrum;

[0023] Perform normalization processing on the discrete reflection data spectrum.

[0024] On the other hand, preferably, the step of obtaining the temperature-wavelength curve of the direct bandgap semiconductor section based on the calibrated temperature data and the interference spectrum drift amount includes:

[0025] Determine the interference peak, and the interference peak is any single peak in the interference spectrum;

[0026] Obtain the drift amount of the interference peak under different calibrated temperature data;

[0027] Use a preset fitting step size to identify the peak point of the interference peak, and perform Gaussian fitting within the wavelength range of the interference peak spectrum to obtain a fitted function model;

[0028] Based on the fitted function model and a preset wavelength interval, perform spectral reconstruction to obtain the Gaussian fitting curve of the interference peak spectrum;

[0029] Perform linear fitting on the drift amount of the interference peak and the Gaussian fitting curve of the interference peak spectrum under different calibrated temperature data to obtain the temperature-wavelength curve of the direct bandgap semiconductor section.

[0030] On the other hand of the present invention, preferably, the interference spectral drift amount in the reflection spectral data is extracted through the following steps:

[0031] Based on the characteristic that the refractive index of a direct bandgap semiconductor crystal changes with temperature, analyze the change in the optical path traveled by light of each wavelength in the interference spectrum in the Fabry-Perot cavity;

[0032] According to the change, extract the interference spectral drift amount in the reflection spectral data.

[0033] On the other hand of the present invention, preferably, the reflection spectral data is represented by the following formula (1):

[0034]

[0035] where R FP represents the reflection spectral data, R1 represents the reflectivity of the incident end of the direct bandgap semiconductor crystal, R2 represents the reflectivity of the reflection end of the direct bandgap semiconductor crystal, and φ represents the phase difference between adjacent light beams.

[0036] On the other hand of the present invention, preferably, the phase difference between adjacent light beams is represented by the following formula (2):

[0037]

[0038] where φ represents the phase difference between adjacent light beams, n1 represents the refractive index of the direct bandgap semiconductor crystal, λ represents the incident light wavelength at the incident end of the direct bandgap semiconductor crystal, θ represents the incident angle, and L represents the cavity length of the Fabry-Perot cavity.

[0039] On the other hand of the present invention, preferably,

[0040] When the incident angle is 0, and when the incident light wavelength λ and the cavity length L satisfy the following formula (3), the reflected light of the light wavelength undergoes constructive interference:

[0041] 2nL = m1λ (3);

[0042] When the incident angle is 0, and when the incident light wavelength λ and the cavity length L satisfy the following formula (4), the reflected light of the light wavelength undergoes destructive interference:

[0043]

[0044] where 2nL represents the optical path traveled by light in the Fabry-Perot cavity, m1 and m2 are integers, and λ represents the incident light wavelength at the incident end of the direct bandgap semiconductor crystal.

[0045] On the other hand of the present invention, preferably, the peak wavelength of the FBG reflection spectrum satisfies the following formula (5):

[0046] λ Bragg = 2nΛ (5);

[0047] where λ Bragg represents the peak wavelength of the FBG reflection spectrum, n is the refractive index, and Λ is the grating period.

[0048] (III) Advantageous Effects

[0049] The above technical solution of the present invention has the following beneficial technical effects:

[0050] By combining the FBG-direct bandgap semiconductor dual-mode sensing mechanism, the present invention can simultaneously obtain two independent temperature data, namely the first temperature and the second temperature, and further improve the measurement accuracy through data fitting. The temperature-wavelength curves of the FBG and the direct bandgap semiconductor crystal have different characteristics. By analyzing the FBG data segment, a rough temperature positioning is obtained, solving the problems of possible overlap and difficult resolution of the interference spectrum in wide-temperature-range measurements. At the same time, the second temperature obtained by analyzing the direct bandgap semiconductor data segment is used to refine and compensate the temperature measurement result of the first temperature, achieving high-resolution and high-precision temperature measurement in a wide temperature measurement range. Description of the Drawings

[0051] Figure 1 is the overall flowchart of an embodiment of the present invention;

[0052] Figure 2 is the schematic diagram of the initial data division of an embodiment of the present invention;

[0053] Figure 3 is the schematic diagram of the direct bandgap semiconductor data segment of an embodiment of the present invention;

[0054] Figure 4 is the schematic diagram of the preprocessed direct bandgap semiconductor data segment of an embodiment of the present invention;

[0055] Figure 5 is the schematic diagram of the Gaussian fitting curve of the interference peak spectrum of an embodiment of the present invention;

[0056] Figure 6 is the schematic diagram of the temperature-wavelength curve of the direct bandgap semiconductor segment of an embodiment of the present invention;

[0057] Figure 7 is the schematic diagram of the FBG temperature segment of an embodiment of the present invention;

[0058] Figure 8 is the schematic diagram of the temperature-wavelength curve of the FBG segment of an embodiment of the present invention;

[0059] Figure 9 is the schematic diagram of the structure of the direct bandgap semiconductor. Detailed implementation manners

[0060] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the specific implementation manners and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0061] Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0062] In the description of the present invention, it should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0063] In addition, the technical features involved in the different implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0064] Embodiment 1

[0065] A temperature monitoring method. The temperature monitoring method in this embodiment is based on an optical fiber temperature monitoring system. The optical fiber temperature monitoring system includes an FBG-direct bandgap semiconductor composite temperature sensing device and an optical signal analysis and processing module. After receiving the spectral signal, the FBG-direct bandgap semiconductor composite temperature sensing device generates a reflected spectral signal. After receiving the reflected spectral signal, the optical signal analysis and processing module analyzes and processes it to obtain temperature information.

[0066] The FBG-direct bandgap semiconductor composite temperature sensing device in this embodiment includes an optical fiber conduction unit and a direct bandgap semiconductor crystal sensing unit. The optical fiber conduction unit is connected to the direct bandgap semiconductor crystal sensing unit. Among them, the direct bandgap semiconductor crystal sensing unit constructs a Fabry-Perot cavity structure, while the optical fiber conduction unit forms a Bragg fiber grating structure. The role of the Bragg fiber grating structure is to reflect the optical signal to form a Bragg reflection spectrum, and the Fabry-Perot cavity structure is used to generate an interference spectrum. Further, one end of the light incident of the direct bandgap semiconductor crystal sensing unit is connected to one end of the optical fiber conduction unit, while the light reflection end of the direct bandgap semiconductor crystal sensing unit is far from the optical fiber conduction unit. And, the incident end and the reflection end of the direct bandgap semiconductor crystal sensing unit constitute the parallel mirrors of the Fabry-Perot cavity structure, and a reflection film is provided at the reflection end of the direct bandgap semiconductor crystal. Figure 9 The structural schematic diagram of the direct bandgap semiconductor is shown, asFigure 9 As shown, the structure of a direct bandgap semiconductor is such that the top of the valence band and the bottom of the conduction band are at the same position in momentum space. The energy gap between the conduction band and the valence band, i.e., the forbidden band, allows electrons to directly transition from the top of the valence band (the position with the highest energy in the valence band) to the bottom of the conduction band (the position with the lowest energy in the conduction band) by absorbing photons (light of a specific wavelength), and the photon energy is equal to or greater than its forbidden band width. This transition process does not involve the participation of other intermediate energy levels or states, so it is called a "direct" transition. A semiconductor with such a band structure is called a direct bandgap semiconductor.

[0067] Figure 1 Figure 5 shows a schematic diagram of the overall process of an embodiment of the present invention. As Figure 1 shown, the temperature monitoring method of this embodiment includes: dividing the collected initial data according to wavelength bands to obtain an FBG data segment and a direct bandgap semiconductor data segment; the reflected spectral signal received by the optical signal analysis and processing module contains rich information. Since the light response characteristics of the two sensing structures of FBG (fiber Bragg grating) and direct bandgap semiconductor are different in different wavelength bands, Figure 2 Figure 9 shows a schematic diagram of the division of initial data of an embodiment of the present invention. Figure 3 Figure 11 shows a schematic diagram of the direct bandgap semiconductor data segment of an embodiment of the present invention. Figure 7 Figure 13 shows a schematic diagram of the FBG temperature segment of an embodiment of the present invention. As Figure 2 、 Figure 3 and Figure 7 shown, dividing the initial data according to wavelength bands provides a clear and accurate data basis for subsequent analysis and processing.

[0068] Compare and analyze the FBG data segment with the FBG segment temperature-wavelength curve to obtain the first temperature; the characteristic of FBG is that its reflection wavelength changes linearly with temperature. By comparing and analyzing the FBG data segment with the pre-acquired FBG segment temperature-wavelength curve, the corresponding temperature value, i.e., the first temperature, can be accurately calculated based on the change in the reflection wavelength. FBG temperature measurement principle: Light is transmitted from a single-mode optical fiber to the FBG, and a small amount of light is reflected at each position with a periodic refractive index change in front of the air hole. When the grating period is approximately half of the incident light wavelength, all the reflected light coherently combines into a large reflection with a specific wavelength, and the light of other wavelengths passes through the FBG and continues to propagate.

[0069] Furthermore, in this embodiment, the FBG segment temperature-wavelength curve is obtained through the following steps:

[0070] Use a peak-seeking algorithm to obtain the peak wavelength of the FBG reflection spectrum at different first experimental temperatures.

[0071] The first experimental temperature and the peak wavelength of the FBG reflection spectrum are linearly fitted to obtain the FBG segment temperature-wavelength curve. The peak-finding algorithm is used to obtain the FBG peak wavelength at different first experimental temperatures. First, a series of different temperature conditions are set, namely the first experimental temperature. In order to accurately obtain the peak wavelength reflected by the FBG at each temperature, it is necessary to use the peak-finding algorithm. The peak-finding algorithm is able to accurately identify the position of the peak in a complex spectral signal, that is, to determine the wavelength of the FBG reflection spectrum. By performing peak-finding processing on the spectral signal at different first experimental temperatures, a set of corresponding data can be obtained, namely the peak wavelength of the FBG reflection spectrum at different temperatures. The first experimental temperature and the FBG peak wavelength are linearly fitted to obtain the FBG segment temperature-wavelength curve. After obtaining the different first experimental temperatures and their corresponding FBG peak wavelengths, a linear fitting method is used. Linear fitting is to process a set of data points to find a straight line that best represents the distribution trend of these data points. Figure 8 FIG. 1 is a schematic diagram of a FBG segment temperature-wavelength curve according to an embodiment of the present invention. Figure 8 As shown, in this embodiment, the first experimental temperature is used as the independent variable, and the peak wavelength of the FBG reflection spectrum is used as the dependent variable. A straight line equation that can best fit these data points is calculated through a specific mathematical algorithm, such as the least squares method, and the straight line represents the FBG segment temperature-wavelength curve.

[0072] The direct bandgap semiconductor data segment is compared and analyzed with the direct bandgap semiconductor segment temperature-wavelength curve to obtain the second temperature; the direct bandgap semiconductor sensing structure generates an interference spectrum through its unique Fabry-Perot cavity structure, and the characteristics of the interference spectrum are also closely related to temperature. Similarly, by comparing and analyzing the direct bandgap semiconductor segment temperature-wavelength curve obtained in advance, the direct bandgap semiconductor data segment is compared with the curve, and the corresponding temperature value, i.e., the second temperature, can be accurately calculated according to the change of the interference spectrum.

[0073] In this embodiment, the temperature-wavelength curve of the direct bandgap semiconductor segment is obtained by the following steps:

[0074] Through the Fabry-Perot cavity formed by the direct bandgap semiconductor crystal, the reflection spectrum data at different second experimental temperatures are obtained; the interference effect of the Fabry-Perot cavity formed by the direct bandgap semiconductor crystal on light will change with the change of temperature. First, a series of different temperature conditions, namely the second experimental temperature, are set. Under each temperature condition, let the light pass through the Fabry-Perot cavity formed by the direct bandgap semiconductor crystal. At this time, the Fabry-Perot cavity will reflect the light and produce a specific reflection spectrum, and the reflection spectrum data at different second experimental temperatures are obtained.

[0075] Extract the interference spectrum drift amount in the reflected spectrum data; Since the interference characteristics of the Fabry-Perot cavity are temperature-related, as the temperature changes, the interference spectrum will drift. By carefully analyzing and processing the obtained reflected spectrum data and using specific algorithms and technical means, we can accurately extract the drift amount of the interference spectrum.

[0076] Calibrate the actual temperature data using a standard thermometer to obtain calibrated temperature data; Calibrate the actual temperature data using a standard thermometer to obtain calibrated temperature data. To ensure the accuracy and reliability of the obtained temperature data, it is necessary to measure and calibrate the actual temperature in the experiment using a standard thermometer. The standard thermometer has the characteristics of high precision and high reliability and can provide an accurate temperature reference value. By comparing and calibrating the temperature measured by the standard thermometer with the second experimental temperature set in the experiment, accurate calibrated temperature data can be obtained.

[0077] Based on the calibrated temperature data and the interference spectrum drift amount, obtain the temperature-wavelength curve of the direct bandgap semiconductor segment. After obtaining the accurate calibrated temperature data and the interference spectrum drift amount, establish the corresponding relationship between the two. Using mathematical methods such as curve fitting to process these data, find a curve that can best describe the relationship between temperature and interference spectrum drift amount, that is, the temperature-wavelength curve of the direct bandgap semiconductor segment.

[0078] Furthermore, in this embodiment, Figure 4 shows a schematic diagram of the preprocessed direct bandgap semiconductor data segment of an embodiment of the present invention, as Figure 4 shown, preprocess the obtained reflected spectrum data, and the preprocessing includes:

[0079] Denoise the reflected spectrum data through quadratic Gaussian filtering to obtain a discrete reflected data spectrum;

[0080] Normalize the discrete reflection data spectrum. During the actual spectrum acquisition process, due to various factors such as environmental noise and the noise of the device itself, the collected reflection spectrum data often contains a certain amount of noise components. Noise will affect the accurate extraction of the interference spectrum drift amount in the subsequent process, and thus affect the accuracy of temperature measurement. In this embodiment, quadratic Gaussian filtering is used to improve the denoising effect and more thoroughly eliminate the influence of noise. By performing quadratic Gaussian filtering on the reflection spectrum data, a relatively pure discrete reflection data spectrum can be obtained, providing a high-quality data basis for subsequent analysis. The purpose of normalization is to map the data in the discrete reflection data spectrum to a unified range, eliminate the differences in the magnitude of the data, make the data at different wavelengths comparable, and is also conducive to subsequent data processing and analysis. For example, when extracting the interference spectrum drift amount and performing curve fitting and other operations in the subsequent process, the normalized data can more accurately reflect the change characteristics of the spectrum, improving the accuracy and reliability of the analysis.

[0081] The interference spectrum drift amount in the reflection spectrum data is extracted through the following steps:

[0082] Based on the characteristic that the refractive index of a direct bandgap semiconductor crystal changes with temperature, analyze the change in the optical path traveled by light of each wavelength in the Fabry-Perot cavity in the interference spectrum;

[0083] According to the above change, extract the interference spectrum drift amount in the reflection spectrum data.

[0084] Based on the characteristic that the refractive index of a direct bandgap semiconductor crystal changes with temperature, analyze the change in the optical path traveled by light of each wavelength in the Fabry-Perot cavity in the interference spectrum. The refractive index of a direct bandgap semiconductor crystal changes with the change of temperature, and the interference characteristic of the Fabry-Perot cavity is closely related to the optical path traveled by light in it. When the temperature changes, the change in the refractive index of the direct bandgap semiconductor crystal will cause the optical path traveled by light in the Fabry-Perot cavity to change, thereby causing the drift of the interference spectrum. Establish the relationship between the temperature change and the optical path change, and then extract the interference spectrum drift amount.

[0085] Furthermore, in this embodiment, the reflection spectrum data is represented by the following formula (1):

[0086]

[0087] where R FP represents the reflection spectrum data, R1 represents the reflectivity of the incident end of the direct bandgap semiconductor crystal, R2 represents the reflectivity of the reflection end of the direct bandgap semiconductor crystal, and φ represents the phase difference between adjacent light beams;

[0088] The phase difference between adjacent light beams is represented by the following formula (2):

[0089]

[0090] Wherein, φ represents the phase difference between adjacent light beams, n1 represents the refractive index of the direct bandgap semiconductor crystal, λ represents the incident light wavelength at the incident end of the direct bandgap semiconductor crystal, θ represents the incident angle, and L represents the cavity length of the Fabry-Perot cavity.

[0091] When the incident angle is 0 and the incident light wavelength λ and the cavity length L satisfy the following formula (3), the reflected light of the light wavelength undergoes constructive interference:

[0092] 2nL = m1λ (3);

[0093] When the incident angle is 0 and the incident light wavelength λ and the cavity length L satisfy the following formula (4), the reflected light of the light wavelength undergoes destructive interference:

[0094]

[0095] Wherein, 2nL represents the optical path that light travels in the Fabry-Perot cavity, m1 and m2 are integers, and λ represents the incident light wavelength at the incident end of the direct bandgap semiconductor crystal.

[0096] Furthermore, the peak wavelength of the FBG reflection spectrum satisfies the following formula (5):

[0097] λ Bragg = 2nΛ (5);

[0098] Wherein, λ Bragg represents the peak wavelength of the FBG reflection spectrum, n is the refractive index, and Λ is the grating period.

[0099] Obtaining the temperature-wavelength curve of the direct bandgap semiconductor segment according to the calibrated temperature data and the interference spectrum drift amount includes:

[0100] Determine the interference peak, and the interference peak is any single peak in the interference spectrum; in the interference spectrum, there are multiple single peaks. Selecting one of the single peaks as the research object is because each single peak reflects the specific characteristics of the interference spectrum. By analyzing a single interference peak, the problem can be simplified, and at the same time, the change of the interference spectrum can be accurately reflected.

[0101] Obtain the drift amount of the interference peak under different calibrated temperature data; under different calibrated temperature conditions, the position of the interference peak will drift. By accurately measuring and recording these drift amounts, a set of data on temperature and the drift amount of the interference peak is obtained.

[0102] Identify the peak points of the interference peaks using a preset fitting step size, perform Gaussian fitting within the wavelength range of the interference peak spectrum to obtain a fitted function model; the setting of the fitting step size is to more accurately identify the peak points within the wavelength range of the interference peak spectrum. By scanning the interference peak spectrum with the preset fitting step size, the position of the peak points can be found. Then, use the Gaussian fitting method to fit the interference peak spectrum to obtain a function model that can accurately describe the shape of the interference peak.

[0103] Perform spectral reconstruction based on the fitted function model and the preset wavelength interval. Figure 5 It is a schematic diagram of the Gaussian fitting curve of the interference peak spectrum in an embodiment of the present invention; as Figure 5 shown, obtain the Gaussian fitting curve of the interference peak spectrum; the Gaussian fitting curve of the interference peak spectrum can more accurately reflect the shape and characteristics of the interference peak.

[0104] Perform linear fitting on the drift amount of the interference peak and the Gaussian fitting curve of the interference peak spectrum under different calibrated temperature data. Figure 6 It is a schematic diagram of the temperature-wavelength curve of the direct bandgap semiconductor segment in an embodiment of the present invention; as Figure 6 shown, obtain the temperature-wavelength curve of the direct bandgap semiconductor segment. By performing linear fitting on the drift amount of the interference peak under different calibrated temperatures and the corresponding Gaussian fitting curve, a linear relationship between temperature and the drift amount of the interference peak can be established, thereby obtaining the temperature-wavelength curve of the direct bandgap semiconductor segment.

[0105] Perform fitting on the first temperature and the second temperature to obtain temperature data. The first temperature is used to locate the temperature range, and the second temperature is used to determine the temperature data within the temperature range. In this embodiment, the temperature detected according to the FBG data segment is a relatively wide temperature range, obtaining a rough temperature range, and a more accurate temperature indication value is obtained according to the direct bandgap semiconductor data segment. The monitoring method of this embodiment realizes a temperature sensitivity of 0.12 nm / °C, a wavelength demodulation resolution of 0.1 pm, and a temperature demodulation error of ±0.41 °C within the temperature measurement range of -20 to 150 °C.

[0106] By combining the FBG-direct bandgap semiconductor dual-mode sensing mechanism, the present invention can simultaneously obtain two independent temperature data, namely the first temperature and the second temperature, and further improve the measurement accuracy through data fitting. The temperature-wavelength curves of the FBG and the direct bandgap semiconductor crystal have different characteristics. By analyzing the FBG data segment, rough temperature positioning is obtained, solving the problems of possible overlap and difficult resolution of the interference spectrum in wide temperature range measurements. At the same time, the second temperature obtained by analyzing the direct bandgap semiconductor data segment refines and compensates the temperature measurement result of the first temperature, achieving high-resolution and high-precision temperature measurement in a wide temperature measurement range.

[0107] It should be understood that the above specific embodiments of the present invention are only for illustrative explanation or interpretation of the principles of the present invention, and do not constitute a limitation on the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

[0108] The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should fall within the scope of the present invention.

[0109] Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made to the embodiments of the present invention without departing from the spirit and scope of the present invention.

[0110] Obviously, the above embodiments are only examples for clear illustration and not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the embodiments here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A temperature monitoring method, characterized in that: include: The collected initial data are divided into bands to obtain FBG data segments and direct bandgap semiconductor data segments; Comparing and analyzing the FBG data segment with the FBG segment temperature-wavelength curve to obtain a first temperature; Comparing and analyzing the direct bandgap semiconductor data segment with a direct bandgap semiconductor segment temperature-wavelength curve to obtain a second temperature; The first temperature and the second temperature are fitted to obtain temperature data.

2. The temperature monitoring method according to claim 1, characterized in that: The FBG segment temperature-wavelength curve is obtained by the following steps: The peak wavelength of the FBG reflection spectrum at different first experimental temperatures is obtained using a peak-finding algorithm; The first experimental temperature and the peak wavelength of the FBG reflection spectrum are linearly fitted to obtain the FBG segment temperature-wavelength curve.

3. The temperature monitoring method according to claim 1, characterized in that: The temperature-wavelength curve of the direct bandgap semiconductor segment is obtained by the following steps: A Fabry-Perot cavity is formed by a direct bandgap semiconductor crystal, and a reflective film is arranged at the reflective end of the direct bandgap semiconductor crystal to obtain reflective spectrum data at different second experimental temperatures; Extracting interference spectrum drift in the reflection spectrum data; Use a standard thermometer to calibrate the actual temperature data to obtain calibrated temperature data; According to the calibrated temperature data and the interference spectrum drift, the temperature-wavelength curve of the direct bandgap semiconductor segment is obtained.

4. The temperature monitoring method according to claim 3, characterized in that: The acquired reflectance spectrum data is preprocessed, and the preprocessing includes: De-noising the reflection spectrum data by using a secondary Gaussian filter to obtain a discrete reflection data spectrum; The discrete reflection data spectrum is normalized.

5. The temperature monitoring method according to claim 3, characterized in that: The step of obtaining a temperature-wavelength curve of a direct bandgap semiconductor segment according to the calibrated temperature data and the interference spectrum drift comprises: Determine an interference peak, wherein the interference peak is any single peak in the interference spectrum; Obtaining the drift amount of the interference peak under different calibrated temperature data; The peak point of the interference peak is identified by using a preset fitting step size, and Gaussian fitting is performed within the wavelength range of the interference peak spectrum to obtain a fitted function model; Performing spectrum reconstruction based on the fitted function model and a preset wavelength interval to obtain a Gaussian fitting curve of the interference peak spectrum; The drift amount of the interference peak under different calibrated temperature data and the Gaussian fitting curve of the interference peak spectrum are linearly fitted to obtain the temperature-wavelength curve of the direct bandgap semiconductor segment.

6. The temperature monitoring method according to claim 3, characterized in that: The interference spectrum drift in the reflection spectrum data is extracted by the following steps: Based on the property that the refractive index of direct bandgap semiconductor crystal changes with temperature, the change of the optical path of each wavelength of light in the interference spectrum in the Fabry-Perot cavity is analyzed; According to the change, the interference spectrum drift in the reflection spectrum data is extracted.

7. The temperature monitoring method according to claim 6, characterized in that: The reflectance spectrum data is expressed using the following formula (1): Among them, R FP represents the reflection spectrum data, R1 represents the reflectivity at the incident end of the direct bandgap semiconductor crystal, R2 represents the reflectivity at the reflection end of the direct bandgap semiconductor, and φ represents the phase difference between adjacent light beams.

8. The temperature monitoring method according to claim 7, characterized in that: The phase difference between the adjacent light beams is expressed by the following formula (2): Wherein, φ represents the phase difference between adjacent light beams, n1 represents the refractive index of the direct bandgap semiconductor crystal, λ represents the wavelength of the incident light at the incident end of the direct bandgap semiconductor crystal, θ represents the incident angle, and L represents the cavity length of the Fabry-Perot cavity.

9. The temperature monitoring method according to claim 8, characterized in that: When the incident angle is 0, and the wavelength of the incident light λ satisfies the following formula (3) with the cavity length L, the reflected light of the wavelength interferes constructively: 2nL=m1λ (3); When the incident angle is 0, and the wavelength λ of the incident light satisfies the following formula (4) with the cavity length L, the reflected light of the wavelength interferes destructively: Among them, 2nL represents the optical path of light in the Fabry-Perot cavity, m1 and m2 are integers, and λ represents the wavelength of the incident light at the incident end of the direct bandgap semiconductor crystal.

10. The temperature monitoring method according to claim 2, characterized in that: The FBG reflection spectrum peak wavelength satisfies the following formula (5): l Bragg =2nΛ (5); Among them, λ Bragg represents the peak wavelength of the FBG reflection spectrum, n is the refractive index, and Λ is the grating period.

Images