Non-contact fluorescent optical temperature measurement method based on asym2sig function

Abstract

The application discloses a non-contact fluorescent optical temperature measuring method based on an Asym2Sig function. Firstly, the Asym2Sig function is used to fit the fluorescent material emission spectrum of a fluorescent optical temperature sensor under different temperatures; the low-energy side variance and the high-energy side variance of the emission spectrum in the Asym2Sig function are obtained as peak shape parameters w2 and w3; then, the peak shape parameters w2 or w3 are compared to obtain a parameter R; the parameter R and the environmental temperature T are linearly distributed; and the linear equation between the parameter R and the environmental temperature T is used for function fitting calculation of the temperature of a measured object. The application uses the ratio R of the peak shape parameters w2 and w3 obtained by using the Asym2sig function fitting as a parameter for non-contact optical temperature measurement, has the advantages of simple operation, high measurement precision, high sensitivity and the like, and has important application value in non-contact optical temperature sensor temperature measurement.

Description

Technical Field

[0001] This invention belongs to the technical field of material temperature measurement methods, and particularly relates to a non-contact fluorescence optical temperature measurement method based on the Asym2Sig function. Background Technology

[0002] With the rapid development of science and technology and the continuous improvement of industrial levels, the requirements for temperature measurement in various industries are becoming increasingly stringent, sometimes even requiring temperature measurements across multiple spaces. Examples include long-distance detection of object temperature, surface temperature in a vacuum environment, or detection of temperatures in special environments such as biological tissues or even within cells. Traditional temperature measurement methods mostly use resistance temperature detectors (RTDs) as probes. However, the probe needs time to achieve thermal equilibrium in close contact with the object being measured, and the probe is connected to the microcomputer module by wires, making it a crucial component that cannot be separated spatially. Therefore, traditional temperature sensors cannot be applied to the current complex temperature measurement environments. Non-contact temperature sensors based on infrared thermography also cannot meet some high-precision temperature measurement needs due to insufficient resolution and sensitivity. Therefore, existing temperature measurement methods cannot simultaneously meet the requirements of high accuracy and speed while performing temperature measurements in special spaces. Non-contact optical temperature sensors break through spatial limitations. Their fast response speed and ultra-high resolution enable accurate measurement of target temperatures under special conditions, and they are expected to become the next generation of temperature sensors.

[0003] Currently, the development of non-contact optical temperature sensors mainly focuses on detecting temperature using optical parameters such as fluorescence intensity, fluorescence intensity ratio, half-width at half-maximum (HWHM), peak wavelength, and fluorescence lifetime. However, when using single-peak fluorescence intensity and HWHM as parameters for temperature detection, the measurement results are easily affected by instrument parameters and other conditions. Fluorescence lifetime thermometry, due to its extremely high requirements for instrument performance, is difficult to commercialize. In contrast, non-contact optical temperature sensors based on FIR technology have become a research hotspot due to their simple operation and high sensitivity.

[0004] Despite their high sensitivity, FIR optical temperature sensors still suffer from low measurement accuracy. This is because FIR sensors measure temperature by collecting the fluorescence intensity of multiple emission peaks. However, some fluorescence emission peaks have narrow peak shapes, meaning only a small amount of experimental data from the emission spectrum can be utilized, making them prone to significant measurement errors. This is especially true when some emission peaks are close together, for example, those from Er... 3+ ion 2 H 11 / 2 → 4 I 15 / 2 and 4 S 3 / 2 → 4 I15 / 2 The two fluorescence emission peaks of the energy level transition have complex shapes and their peak wavelengths are only 20 nm apart, making them highly susceptible to interference when acquiring their fluorescence intensity. Solving this problem requires using a high-resolution and high-sensitivity spectrometer to acquire the fluorescence signal. However, this not only increases the cost of the equipment but also fails to fundamentally address the issue of low measurement accuracy. Therefore, proposing a novel optical temperature measurement scheme that ensures both sensitivity and accuracy without increasing equipment requirements is of significant value in promoting the commercial application of optical temperature sensors. Summary of the Invention

[0005] To address the shortcomings mentioned in the background section, this invention provides a non-contact fluorescence optical thermometry method based on the Asym2Sig function.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A non-contact fluorescence optical thermometry method based on the Asym2Sig function, comprising the following steps:

[0008] (1) The emission spectrum of the fluorescent material in the fluorescent optical temperature sensor at different temperatures was fitted using the Asym2Sig function; the low-energy lateral variance and high-energy lateral variance of the emission spectrum in the Asym2Sig function are the peak shape parameters w2 and w3, respectively.

[0009] (2) The peak shape parameters w2 and w3 obtained by fitting are compared to obtain parameter R. Parameter R represents the degree to which the peak shape symmetry of the emission spectrum is affected by the ambient temperature. The parameter R and the ambient temperature T are linearly distributed. The temperature of the analyte is calculated by using the linear equation R = a - bT between parameter R and ambient temperature T. Where a represents the intercept and -b is the slope of the line.

[0010] Preferably, the fluorescent material in the fluorescent optical temperature sensor has luminescent centers in its crystal structure.

[0011] Preferably, the fluorescent material is Mn 2+ Activated fluorescent materials, including Zn2SiO4:Mn 2+ Zn2GeO4:Mn 2+ CdAl2O4:Mn 2+ CdB4O7:Mn 2+ LiZnPO4:Mn 2+ or LiZnVO4:Mn 2+ .

[0012] Compared with the shortcomings and deficiencies of existing technologies, the present invention has the following beneficial effects:

[0013] This invention utilizes the relationship between the asymmetry of the emission spectrum of fluorescent materials under special crystal conditions and the ambient temperature. The emission spectrum of fluorescent materials at different temperatures is fitted using the Asym2sig function to obtain peak shape parameters w2 and w3. The temperature of the analyte is then calculated using the functional relationship between the ratio R of w2 and w3 and the ambient temperature. Using the R value as a parameter for non-contact optical temperature measurement has the advantages of simple operation, high measurement accuracy, and high sensitivity. Attached Figure Description

[0014] Figure 1 This invention provides Mn under a dielectric field environment within a crystal. 2+ A schematic diagram of fluorescence emission spectrum asymmetry and its causes.

[0015] Figure 2 This invention provides a portion of Mn. 2+ The emission spectra of the doped fluorescent materials were fitted using the Asym2Sig function.

[0016] Figure 3 This invention provides Zn2GeO4:Mn at different temperatures. 2+ The fluorescence emission spectrum and its spectral fitting results based on the Asym2Sig function.

[0017] Figure 4 This invention provides the relationship between ambient temperature and parameter R. Figure 4 (a) and the relationship between ambient temperature and relative sensitivity Sr ( Figure 4 (b)). Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] The Asym2sig (Asymmetric Double Sigmoidal) function is a common extreme value statistical distribution function. In its expression, the kurtosis parameter w2 represents the low-energy lateral variance, and w3 represents the high-energy lateral variance. The degree of asymmetry in the emission peak shape is mainly related to w2 and w3.

[0020] Ideally, the fluorescence intensity and photon energy in a fluorescence emission spectrum follow a Gaussian function distribution. However, for fluorescent materials with an internal dielectric field in their crystal structure, the emission spectrum is not fitted by a Gaussian function, but rather follows an Asymmetric Sig function distribution with an asymmetric peak shape. Examples of fluorescent materials with an internal dielectric field in their crystal structure include Zn₂SiO₄:Mn₂. 2+ Zn2GeO4:Mn2+ CdAl2O4:Mn 2+ CdB4O7:Mn 2+ LiZnPO4:Mn 2+ LiZnVO4:Mn 2+ And so on. Influenced by the dielectric field within the crystal, Mn 2+ Ionic 4 T1(4G)→ 6 The emission spectrum of the A1(6S) level transition does not fit to a Gaussian function, but instead follows an asymmetric Asymmetric Sig function distribution. Mn under an internal dielectric field in the crystal... 2+ A schematic diagram of fluorescence emission spectrum asymmetry and its causes is shown below. Figure 1 As shown, in Figure 1 As can be seen from the configuration coordinates, when an internal dielectric field exists in the crystal structure, the excited-state electrons are affected by the external electric field, causing a shift in photon energy during emission. This results in a decrease in the number of photons at high photon energies and an increase in the number of photons at low photon energies, thus reducing the symmetry of the fluorescence emission spectrum. Therefore, the emission spectrum no longer follows a symmetrical Gaussian function distribution, but rather an asymmetric Asym²Sig function distribution. (Partial Mn...) 2+ The emission spectrum of the doped fluorescent material was fitted using the Asym2Sig function as shown in the following figure. Figure 2 As shown. From Figure 2 It can be seen that when the fluorescent material crystal structure contains an internal dielectric field, Mn 2+ The emission spectrum exhibits significant peak asymmetry, but the Asym2Sig function provides a good fit. Here, parameters w2 and w3 represent the low-energy and high-energy lateral variances of the emission spectrum, respectively. A w2 greater than w3 indicates peak tailing towards the low-energy side, while a w2 less than w3 indicates peak tailing towards the high-energy side. The closer the values ​​of w2 and w3 are, the more symmetrical the peak shape and the closer it tends to a Gaussian distribution.

[0021] Zn2GeO4:Mn at different temperatures 2+ The fluorescence emission spectrum and its spectral fitting results based on the Asym2Sig function are as follows: Figure 3 As shown. By Figure 3 It can be seen that the Asym2Sig function can fit the fluorescence emission spectra at different temperatures well. Furthermore, as the temperature increases, the values ​​of w2 and w3 gradually increase, and the difference between them becomes smaller. At higher temperatures, the values ​​of w2 and w3 are nearly equal, indicating that Mn... 2+ The fluorescence emission peaks gradually tend towards a symmetrical Gaussian function distribution. Therefore, by fitting the emission spectra at different temperatures using the Asym2sig function, the peak shape parameters w2 and w3 gradually increase with increasing temperature.

[0022] Introducing parameters This reduces the complexity of direct optical temperature measurement based on parameters w2 and w3. The parameter R represents the degree to which the emission spectrum peak symmetry is affected by ambient temperature; a larger R indicates a greater influence of the internal dielectric field on the emission peak symmetry. An R value close to 1 indicates that the emission peak is almost unaffected by the internal dielectric field, and the emission peak approaches an ideal Gaussian function distribution. Therefore, the temperature measurement results of the fluorescence optical temperature sensor can be obtained by studying the relationship between the value of R and temperature.

[0023] Zn2GeO4:Mn at different temperatures 2+ The relationship between the emission spectral peak shape parameter R of fluorescent materials and the ambient temperature T is as follows: Figure 4 As shown in (a). By Figure 4 (a) It can be seen that the parameter R exhibits a linear distribution with respect to the ambient temperature T. Fitting the linear equation R = a - bT yields a = 2.2679 and b = 0.00324, where -b is the slope of the line, and the goodness of fit is 0.9956. This indicates a stable linear functional relationship between R and the ambient temperature T, where a represents the intercept and -b is the slope of the line. Therefore, the temperature of the analyte can be calculated based on the relationship between the R value obtained by fitting the asymmetric peak using the Asym2Sig function and the ambient temperature T, achieving the purpose of non-contact optical temperature measurement. The absolute sensitivity... Relative sensitivity The relationship between ambient temperature and relative sensitivity Sr is as follows: Figure 4 As shown in (b), the optical temperature sensor exhibits high and stable absolute sensitivity (S). a =0.324%K⁻¹) and high relative sensitivity (S r It reaches 0.303% K⁻¹ near 370 K.

[0024] Verification example:

[0025] To test the feasibility of the optical temperature measurement method of this invention and the accuracy of the measurement results, the Zn2GeO4:Mn... 2+ The sensitivity and accuracy of fluorescent materials as optical temperature sensors. Utilizing Figure 4 (a) The relationship between the obtained R value and the ambient temperature T led to the calculation of the ambient temperature T. cal (R), the results are shown in Table 1: Experimental results are shown in Table 1:

[0026] Table 1. Spectral peak shape parameters and estimated ambient temperature T under different test conditions. cal

[0027]

[0028] As shown in Table 1, despite significant variations in the measured fluorescence intensity of the emission spectrum and some impact on the spectral measurement accuracy under different voltages, slit widths, and even the presence of a glass slide in front of the detector, the temperature measurement results did not exhibit substantial errors. The optical temperature measurement method using the R-value as a parameter demonstrates high measurement accuracy, with an average temperature of 296.57 K and a maximum error of 2.19 K. Non-contact optical temperature measurement using the R-value as a parameter offers advantages such as simple operation, high measurement accuracy, and high sensitivity.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-contact fluorescence optical thermometry method based on the Asym2Sig function, characterized in that, Includes the following steps: (1) The emission spectrum of the fluorescent material in the fluorescent optical temperature sensor at different temperatures was fitted using the Asym2Sig function; the low-energy lateral variance and high-energy lateral variance of the emission spectrum in the Asym2Sig function are the peak shape parameters w2 and w3, respectively. (2) The peak shape parameters w2 and w3 obtained by fitting are compared to obtain parameter R. Parameter R represents the degree to which the symmetry of the emission spectrum peak shape is affected by the ambient temperature. The parameter R and the ambient temperature T are linearly distributed. The temperature of the analyte is calculated by function fitting using the linear equation R = a - bT between parameter R and ambient temperature T. Where a represents the intercept and -b is the slope of the line.

2. The non-contact fluorescence optical thermometry method based on the Asym2Sig function as described in claim 1, characterized in that, The fluorescent material in the fluorescent optical temperature sensor has luminescent centers in its crystal structure.

3. The non-contact fluorescence optical thermometry method based on the Asym2Sig function as described in claim 2, characterized in that, The fluorescent material is Mn 2+ Activated fluorescent materials, including Zn2SiO4:Mn 2+ Zn2GeO4:Mn 2+ CdAl2O4:Mn 2+ CdB4O7:Mn 2+ LiZnPO4:Mn 2+ or LiZnVO4:Mn 2+ .

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