Method, device and storage medium for measuring temperature

Abstract

The present application provides a temperature measurement method, device and storage medium. The method includes: using a measurement system to measure the absorbance of a sample to pulsed laser at different temperatures, and obtaining a relationship curve between temperature and absorbance; using the correction term of the Grüneisen coefficient in the photoacoustic field to correct the original Grüneisen coefficient to obtain an absorption intensity-photoacoustic excitation intensity calculation formula between absorbance and acoustic wave intensity; further substituting the absorbance-temperature change curve at this wavelength to obtain an acoustic wave intensity-temperature fitting formula for the target temperature to be measured; and substituting the signal in the ROI region after image reconstruction using the photoacoustic reconstruction algorithm into the acoustic wave intensity-temperature fitting formula to obtain the temperature of the target temperature to be measured. Based on the photoacoustic effect, this method improves the temperature measurement accuracy on the basis of achieving accurate temperature measurement of deep tissues (3-5 cm).

Description

Technical Field

[0001] This application relates to the technical field of temperature measurement. Specifically, it relates to a method, device, and storage medium for measuring temperature. Background Art

[0002] Existing temperature measurement technologies mainly include contact temperature measurement technology, infrared temperature measurement technology, and acoustic wave temperature measurement technology, etc. Traditional contact temperature measurement methods require direct contact with the measured object, with complex operations and unable to achieve real-time monitoring; while infrared temperature measurement technology, although it does not require contact, can only measure surface temperature with limited penetration depth; acoustic wave temperature measurement technology can obtain deep temperature information to a certain extent, but its accuracy is often low and it is easily affected by the characteristics of the medium.

[0003] That is to say, the measurement accuracy of current temperature measurement technologies is not high enough. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a method, device, and storage medium for measuring temperature. This method is based on the photoacoustic effect and can improve the accuracy of temperature measurement.

[0005] In a first aspect, the embodiments of this application provide a method for measuring temperature, including: using a measurement system to measure the absorbance of a sample to pulsed laser at different temperatures, and obtaining a relationship curve between temperature and absorbance; using the correction term of the Grüneisen coefficient in the photoacoustic field to correct the original Grüneisen coefficient, and obtaining an absorption intensity - photoacoustic excitation intensity calculation formula between absorbance and acoustic wave intensity; further substituting the curve of absorbance changing with temperature at this wavelength, and obtaining a fitting formula of acoustic wave intensity - temperature for the temperature measurement target; and using the photoacoustic reconstruction algorithm to substitute the signal of the ROI region after image reconstruction into the acoustic wave intensity - temperature fitting formula to obtain the temperature of the temperature measurement target.

[0006] The above method for measuring temperature, based on the photoacoustic effect, removes the absorption singularity points where the sample temperature is insensitive to the change of absorbance in the relationship curve between temperature and absorbance, so as to correct the deviation of the relationship curve between temperature and absorbance. It avoids the problems of invasive operations and limited measurement depth that may be brought in contact temperature measurement. Since the laser can effectively penetrate opaque or highly scattering materials, the method provided by the embodiments of this application can measure the deep temperature more accurately, avoiding measurement errors caused by the difference between surface temperature and internal temperature. In addition, due to the high energy density of the laser, it can effectively irradiate the target object, generating a clear acoustic wave signal, thereby improving the signal-to-noise ratio of the measurement and reducing the interference of the external environment on the measurement, that is, improving the accuracy of temperature measurement.

[0007] In combination with the first aspect, optionally, the method of measuring the absorbance of a sample to a pulsed laser at different temperatures using a measurement system and obtaining a relationship curve between temperature and absorbance includes: measuring the absorption spectrum of the sample at different temperatures using a spectrophotometer; and determining the relationship curve between temperature and absorbance based on the absorption spectrum.

[0008] The above method for measuring temperature improves the accuracy of data acquisition by measuring the absorption spectrum of a sample at different temperatures using a spectrophotometer and determining the relationship curve between temperature and absorbance based on the absorption spectrum, thereby enabling the acquisition of a relationship curve with higher resolution. In addition, by recording and analyzing the absorption spectra at different temperatures, a detailed data archive can be obtained, facilitating future research and verification.

[0009] In combination with the first aspect, optionally, after using the measurement system to measure the absorbance of a sample to a pulsed laser at different temperatures and obtaining a relationship curve between temperature and absorbance, the method further includes: using the absorption singularity points in the relationship curve where the sample temperature is insensitive to the change in absorbance to correct the errors of the test system; wherein the errors include the system errors of the laser energy stability and the temperature control device and the gross errors in the measurement; the absorption singularity points are points where the maximum absorption difference is less than 0.001 abs, and the maximum temperature difference in the temperature range during the process of correcting the test system does not exceed the temperature difference threshold of the test system.

[0010] The above method for measuring temperature further improves the accuracy of the measurement result by removing the absorption singularity points that are not affected by temperature changes and correcting the absorbance fluctuations caused by temperature changes.

[0011] In combination with the first aspect, optionally, the method of using the absorption singularity points in the relationship curve where the sample temperature is insensitive to the change in absorbance to correct the errors of the test system includes: performing normalization correction of the absorption intensity range using the absorption singularity points; correcting the laser energy stability; correcting the system errors of the temperature control device; and correcting the gross errors in the measurement.

[0012] The above method for measuring temperature eliminates the absorbance fluctuations caused by temperature changes by performing absorption zero correction, correcting the laser energy stability, correcting the system errors of the temperature control device, and correcting the gross errors in the measurement, thereby further improving the accuracy and reliability of temperature measurement.

[0013] In combination with the first aspect, optionally, the original Grüneisen coefficient is corrected by using the correction term of the Grüneisen coefficient in the photoacoustic field to obtain the absorption intensity-photoacoustic excitation intensity calculation formula between the absorbance and the acoustic wave intensity, including: correcting the original photoacoustic (Grüneisen formula) by using the correction term of thermal saturation caused by the change of absolute temperature (AT) in the photoacoustic field to obtain the photoacoustic dynamic formula and the dynamic correction term introduced by the change of absolute temperature in the photoacoustic excitation-absolute temperature variable temperature correction formula; where,

[0014] The dynamic correction term introduced by the change of absolute temperature is:

[0015] ;

[0016] The corrected photoacoustic dynamic correction formula is:

[0017] ;

[0018] In the formula, is the correction term caused by the change of absolute temperature, λ i is the wavelength, μ a is the light absorption coefficient, p0 is the corrected photoacoustic pressure, F pulse is the light flux of a single pulse, b is a constant that can at least characterize the physical properties of the sample material and the measurement system, is the thermal relaxation time constant, is the thermal energy conversion efficiency, is the reference Grüneisen coefficient, is the time interval between pulses of the pulsed laser;

[0019] Substitute the dynamic correction formula, the light source parameters of the pulsed laser, and the normalization coefficient, test system energy correction parameter, and temperature control compensation parameter obtained from the singular point into the photoacoustic excitation intensity formula to obtain the absorption intensity-photoacoustic excitation intensity calculation formula.

[0020] The above temperature measurement method corrects the original Grüneisen formula by using the correction term of the Grüneisen coefficient in the photoacoustic field, and substitutes the obtained dynamic correction formula together with the light source parameters of the pulsed laser and the absorption zeroing coefficient into the photoacoustic excitation intensity formula. The finally obtained absorption intensity-photoacoustic excitation intensity calculation formula further improves the accuracy of temperature measurement.

[0021] Combined with the first aspect, optionally, the signal of the ROI region after image reconstruction using the photoacoustic reconstruction algorithm is brought into the temperature measurement calculation formula to obtain the temperature of the target to be measured, including: using the image reconstruction algorithm to reconstruct the acoustic wave signal generated during the absorption of the pulsed laser by the target to be measured, to obtain the photoacoustic intensity image slice of the target to be measured; and determining the region of interest of the photoacoustic intensity image slice, and calculating the temperature of the region of interest using the absorption intensity - photoacoustic excitation intensity calculation formula, to obtain the temperature distribution of the region of interest.

[0022] The above temperature measurement method, by using the image reconstruction algorithm to determine the photoacoustic intensity image slice and calculating the temperature distribution of the region of interest in this photoacoustic intensity image slice, not only further improves the accuracy and reliability of the measurement result, but also provides more intuitive and comprehensive temperature information.

[0023] Combined with the first aspect, optionally, the measurement of the temperature to be measured of the target to be measured according to the acoustic wave intensity of the target to be measured and the absorption intensity - photoacoustic excitation intensity calculation formula further includes: real-time correcting the propagation rate of the acoustic wave signal generated during the absorption of the pulsed laser by the sample measured based on the acoustic wave transmission component; the use of the image reconstruction algorithm to reconstruct the acoustic wave signal generated during the absorption of the pulsed laser by the target to be measured to obtain the photoacoustic intensity image slice of the target to be measured includes: using the image reconstruction algorithm and the propagation rate of the wave signal to reconstruct the acoustic wave signal generated during the absorption of the pulsed laser by the target to be measured, to obtain the photoacoustic intensity image slice.

[0024] The above temperature measurement method, by calibrating the propagation speed of the acoustic wave signal at multiple temperatures to be measured and introducing the propagation speed of the acoustic wave signal during the process of correcting the size of the image reconstruction, further improves the accuracy of the reconstructed image size, and thus further improves the accuracy of the finally measured temperature.

[0025] Second aspect, the present application provides a temperature measurement device, including a controller, an acoustic wave sensor, a temperature sensor, a laser emission component, a cuvette, a temperature control component, and a housing; an acoustic wave coupling agent that is close to isotropic is provided inside the housing; the cuvette is located inside the housing and is immersed in the acoustic wave coupling agent; the cuvette is used to hold a sample; the cuvette is made of a material with uniformity and high light transmittance that is close to isotropic with the measured sample; the laser emission component is located inside the housing and is electrically connected to the controller; the laser output end of the laser emission component faces the cuvette and is used to emit pulsed laser to the cuvette; the acoustic wave sensor is located inside the housing and is electrically connected to the controller; the acoustic wave acquisition end of the acoustic wave sensor faces the cuvette and is used to collect acoustic wave signals from the cuvette; the temperature sensor is located inside the cuvette and is electrically connected to the controller; the temperature sensor is used to collect the temperature of the sample; the temperature control end of the temperature control component is located inside the housing and is immersed in the acoustic wave coupling agent; the temperature control component is electrically connected to the controller; the controller is used to: measure the absorbance of the sample to the pulsed laser at different temperatures by using a measurement system, and obtain a relationship curve between temperature and absorbance; correct the original Grüneisen coefficient by using the correction term of the Grüneisen coefficient in the photoacoustic field to obtain an absorption intensity-photoacoustic excitation intensity calculation formula between absorbance and acoustic wave intensity; further substitute the curve of absorbance changing with temperature at this wavelength to obtain an acoustic wave intensity-temperature fitting formula for the temperature measurement target; and substitute the signal of the ROI area after image reconstruction using a photoacoustic reconstruction algorithm into the acoustic wave intensity-temperature fitting formula to obtain the temperature of the temperature measurement target.

[0026] The above temperature measurement device has the same beneficial effects as the temperature measurement method provided in the above first aspect, or any optional implementation manner of the first aspect, and will not be elaborated here.

[0027] Combined with the second aspect, optionally, the temperature control component includes a constant temperature medium container, a heat conducting member, and a pipeline; a constant temperature medium is contained in the constant temperature medium container and is electrically connected to the controller; the heat conducting member has a flow channel for the constant temperature medium to flow through and is located inside the housing and is immersed in the acoustic wave coupling agent; the heat conducting member is connected to the constant temperature medium container through the pipeline; the constant temperature medium container is configured to adjust the temperature of the constant temperature medium under the control of the controller and make the constant temperature medium flow through the flow channel of the heat conducting member.

[0028] The above temperature measurement device, by using a temperature control component composed of a constant temperature medium container, a heat conducting member, and a pipeline, not only realizes the control of the temperature of the cuvette and the sample, but also simplifies the structure of the temperature control component.

[0029] In combination with the second aspect, optionally, the laser emission component includes a laser and a combined lens; the laser is electrically connected to the controller and is configured to emit pulsed laser under the control of the controller; the combined lens is located on the optical path of the laser emitted by the laser and is configured to shape the laser emitted by the laser.

[0030] The above temperature measuring device shapes the pulsed laser emitted by the laser through the combined lens, ensuring the precise irradiation of the pulsed laser on the sample, thereby further improving the accuracy of temperature measurement.

[0031] In a third aspect, an embodiment of the present application further provides a storage medium, which includes a computer-readable storage medium, and a computer program is stored on the computer-readable storage medium. When the computer program is run by a processor, it executes the method described above.

[0032] The above storage medium has the same beneficial effects as the temperature measurement method provided in the first aspect or any optional implementation manner of the first aspect, and will not be elaborated here. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0034] Figure 1 It is the first flowchart of the temperature measurement method provided by the embodiment of the present application;

[0035] Figure 2 It is the specific flowchart of step S120 in the temperature measurement method provided by the embodiment of the present application;

[0036] Figure 3 It is the second flowchart of the temperature measurement method provided by the embodiment of the present application;

[0037] Figure 4 It is the specific flowchart of step S130 in the temperature measurement method provided by the embodiment of the present application;

[0038] Figure 5 It is the specific flowchart of step S140 in the temperature measurement method provided by the embodiment of the present application;

[0039] Figure 6 It is the specific flowchart of step S180 in the temperature measurement method provided by the embodiment of the present application;

[0040] Figure 7 Schematic structural diagram of the temperature measurement device provided by the embodiment of the present application;

[0041] Figure 8 Stereogram of the temperature measurement device provided by another embodiment of the present application.

[0042] Icons: 100, temperature measurement device; 110, controller; 120, acoustic wave sensor; 130, temperature sensor; 140, laser emission component; 141, laser; 142, combined lens; 150, cuvette; 160, temperature control component; 161, constant temperature medium container; 162, heat conducting member; 163, pipeline; 170, outer shell; 180, acoustic wave coupling agent; 1, constant temperature circulating liquid pipeline joint; 2, photoacoustic probe fixing device; 3, constant temperature circulating liquid pipeline; 4, outer shell 5, upper plate; 6, photoacoustic probe; 7, sample fixture; 8, sample cuvette. Specific embodiments

[0043] Hereinafter, embodiments of the technical solutions of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, and therefore are only examples and cannot be used to limit the protection scope of the present application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0045] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "multiple" means more than two, unless otherwise specifically defined.

[0046] The currently mainly used temperature measurement technologies will be briefly described below.

[0047] Regarding the contact temperature measurement technology, it mainly measures the temperature by contact sensors such as thermocouples and thermistors, which usually need to directly contact the surface of the object to be measured. However, the temperature of deep tissues or internal objects cannot be directly measured by simple contact and requires invasive operations (such as inserting a probe), which may cause tissue damage or contamination.

[0048] Regarding the infrared temperature measurement in the contact technology, it can only measure the surface temperature and cannot penetrate obstacles or measure deep tissues.

[0049] Regarding laser Raman scattering temperature measurement in contact technologies, it is applicable to gases or transparent liquids, but it is difficult to apply in complex media or opaque environments.

[0050] Regarding acoustic wave temperature measurement in contact technologies, although it can obtain deep temperature information to a certain extent, its resolution is low, and it is easily affected by environmental noise and medium characteristics.

[0051] Regarding traditional optical imaging in imaging technologies, the penetration depth of light in opaque or scattering media is limited and usually insufficient to obtain the deep temperature distribution.

[0052] Regarding ultrasonic imaging in imaging technologies, ultrasonic waves can penetrate a certain depth, but there is no signal mechanism directly related to temperature, making it difficult to accurately measure temperature.

[0053] In view of this, the present application provides a temperature measurement method, device and storage medium to solve the above technical problems. It mainly realizes the temperature measurement of the temperature measurement target based on the photoacoustic effect. The photoacoustic effect is a phenomenon in which when a substance absorbs light energy (pulsed laser), part of the energy is converted into heat energy, causing a local temperature increase and volume expansion, and generating sound waves. Photoacoustic imaging technology (Photoacoustic Imaging, PAI) is based on the principle of converting light energy into sound energy, and detects and images the internal structure and properties of samples (various materials and biological tissues) through thermoelastic sound waves excited by pulsed lasers. Current photoacoustic devices all analyze the differences in the sound wave signals generated by materials to obtain the types and spatial distributions of substances inside the object, while ignoring the correlation between the sound wave intensity and temperature.

[0054] Applying the photoacoustic effect involves two processes. First, the sample absorbs the energy of the pulsed light, and the sample is heated and expands in volume in a short time, realizing the conversion of light energy into heat energy; then the sample expands and contracts thermally and vibrates to generate sound waves, realizing the conversion of heat energy into sound energy. The change in temperature will change the parameters such as the light absorption coefficient of the sample, thereby affecting the conversion of light energy into heat energy; the change in temperature will also affect the volume thermal expansion coefficient, heat capacity at constant pressure and other parameters of the sample, further affecting the conversion of heat energy into sound energy. Through research, it is found that the relationship between the temperature change and parameters such as the light absorption coefficient and volume thermal expansion coefficient of the sample satisfies the following formula:

[0055]

[0056] P represents the sound wave intensity generated by the sample, F represents the local light flux, μ a represents the light absorption coefficient, β represents the volume thermal expansion coefficient, V l represents the longitudinal wave sound velocity and C pCp represents the heat capacity at constant pressure. Γ represents the Grüneisen parameter. The Grüneisen parameter (which depends on the isothermal compressibility, volume thermal expansion coefficient, mass density, and specific heat capacity at constant volume of the sample) varies significantly with temperature.

[0057] Specifically, refer to the various embodiments provided in this application and the accompanying drawings of the specification.

[0058] Please refer to Figure 1 , Figure 1 is the first flowchart of the temperature measurement method provided by the embodiments of this application. The temperature measurement method provided by the embodiments of this application may include:

[0059] Step S120: Use the measurement system to measure the absorbance of the sample to the pulsed laser at different temperatures, and obtain the relationship curve between temperature and absorbance.

[0060] In the above step S120, the sample may be water. By controlling the laser emission component in the measurement system to emit pulsed laser to the sample, the absorption of the sample to the pulsed laser at different temperatures can be measured by using an optical sensor. Thus, the relationship curve between temperature and absorbance is obtained to understand the light absorption characteristics of the sample at different temperatures.

[0061] Step S140: Use the correction term of the Grüneisen coefficient in the photoacoustic field to correct the original Grüneisen coefficient, and obtain the absorption intensity - photoacoustic excitation intensity between absorbance and acoustic wave intensity.

[0062] In the above step S140, the correction term of the Grüneisen coefficient in the photoacoustic field is used to describe the relationship between the absorption of laser energy and the generation of acoustic waves in the photoacoustic effect. After correction, it can more accurately reflect the photoacoustic effect of the object.

[0063] Step S160: Further substitute the curve of absorbance varying with temperature at this wavelength to obtain the acoustic wave intensity - temperature fitting formula of the temperature measurement target.

[0064] In the above step S160, by detecting the acoustic wave intensity generated by the temperature measurement target based on the photoacoustic effect and combining with the absorption intensity - photoacoustic excitation intensity calculation formula obtained previously, the temperature to be measured of the temperature measurement target can be obtained.

[0065] Step S180: Substitute the signal of the ROI region after image reconstruction using the photoacoustic reconstruction algorithm into the acoustic wave intensity - temperature fitting formula to obtain the temperature of the temperature measurement target.

[0066] In the above implementation process, based on the photoacoustic effect, absorption singularities where the sample temperature is insensitive to changes in absorbance in the relationship curve between temperature and absorbance are removed to correct the relationship curve between temperature and absorbance. This avoids the problems of invasive operations and limited measurement depth that may occur in contact temperature measurement. Since the laser can effectively penetrate opaque or highly scattering materials, the method provided by the embodiments of the present application can measure the deep temperature more accurately, avoiding measurement errors caused by differences between surface temperature and internal temperature. In addition, due to the high energy density of the laser, it can effectively irradiate the target object, generating clear acoustic wave signals, thereby improving the signal-to-noise ratio of the measurement and reducing interference from the external environment to the measurement, that is, improving the accuracy of temperature measurement.

[0067] Please refer to Figure 2 , Figure 2 which is a specific flowchart of step S120 in the temperature measurement method provided by the embodiments of the present application. In some optional implementation manners, step S120 may include:

[0068] Step S121: Measure the absorption spectra of the sample at different temperatures using a spectrophotometer.

[0069] Step S122: Determine the relationship curve between temperature and absorbance based on the absorption spectra.

[0070] In the above steps, the optical sensor that can be specifically used may be a spectrophotometer. Using a spectrophotometer, the absorption spectra of the sample for pulsed laser can be measured. Based on this absorption spectrum, the relationship curve between temperature and absorbance can be determined.

[0071] In the above implementation process, by using a spectrophotometer to measure the absorption spectra of the sample at different temperatures and determining the relationship curve between temperature and absorbance based on this absorption spectrum, the accuracy of data acquisition is improved, and thus a relationship curve with higher resolution can be obtained. In addition, by recording and analyzing the absorption spectra at different temperatures, detailed data archives can be obtained, facilitating future research and verification.

[0072] Please refer to Figure 3 , Figure 3 which is the second flowchart of the temperature measurement method provided by the embodiments of the present application. After step S120, the temperature measurement method provided by the embodiments of the present application may further include:

[0073] Step S130: Use the absorption singularities in the relationship curve where the sample temperature is insensitive to changes in absorbance to correct the error of the test system.

[0074] In the above step S130, the errors include the system errors of the laser energy stability and the temperature control device and the gross errors in measurement; the absorption singularity points are the points where the maximum absorption difference is less than 0.001 abs, and the maximum temperature difference within the temperature range during the process of calibrating the test system does not exceed the temperature difference threshold of the test system. During the temperature change process, it is usually possible to find that some absorption points do not change with the temperature change (i.e., the absorption intersection points insensitive to temperature), then these intersection points can be used for absorption zero calibration, for example: the absorption of water to the laser with a wavelength of 1003.4 nm. By removing the absorption singularity points that are not affected by the temperature change and calibrating the absorbance fluctuations caused by the temperature change, the measurement results can be made more accurate.

[0075] In the above implementation process, by removing the absorption singularity points that are not affected by the temperature change and calibrating the absorbance fluctuations caused by the temperature change, the accuracy of the measurement results is further improved.

[0076] Please refer to Figure 4 , Figure 4 is the specific flowchart of step S130 in the temperature measurement method provided by the embodiment of the present application. In some optional implementation manners, step S130 may include:

[0077] Step S131: Perform normalization calibration on the absorption intensity range by using the absorption singularity points.

[0078] In the above step S131, exemplarily, at a wavelength of 1003.4 nm, the absorbance of water remains unchanged within the temperature range from -6°C to 30°C. When measuring the absorbance of a sample within this temperature range, if it is found that the absorbance fluctuates with the temperature change, the absorbance at 1003.4 nm can be used as a reference point to remove these fluctuations, thereby achieving absorption zero calibration.

[0079] Step S132: Calibrate the laser energy stability.

[0080] Step S133: Calibrate the system errors of the temperature control device.

[0081] Step S134: Calibrate the gross errors in measurement.

[0082] In the above implementation process, through absorption zero calibration, calibration of the laser energy stability, calibration of the system errors of the temperature control device, and calibration of the gross errors in measurement, the absorbance fluctuations caused by the temperature change are eliminated, thereby further improving the accuracy and reliability of the temperature measurement.

[0083] Please refer to Figure 5 , Figure 5It is a specific flowchart of step S140 in the temperature measurement method provided by the embodiments of the present application. In some optional embodiments, step S140 may include:

[0084] Step S141: Using the correction term in the photoacoustic field caused by the change in absolute temperature (AT) to correct the original photoacoustic (Griineisen formula), and obtaining the photoacoustic dynamic formula and the dynamic correction term introduced by the change in absolute temperature in the photoacoustic excitation - absolute temperature variable temperature correction formula; where

[0085] The dynamic correction term introduced by the change in absolute temperature is:

[0086] ;

[0087] The corrected photoacoustic dynamic correction formula is:

[0088] ;

[0089] In the formula, is the correction term caused by the change in absolute temperature, λ i is the wavelength, μ a is the light absorption coefficient, p0 is the corrected photoacoustic pressure, F pulse is the light flux of a single pulse, b is a constant that can at least characterize the physical properties of the sample material and the measurement system, is the thermal relaxation time constant, is the thermal energy conversion efficiency, is the reference Griineisen coefficient, is the time interval between pulses of the pulsed laser.

[0090] In the above step S141, the formula of the original Griineisen parameter is specifically as follows:

[0091]

[0092] Step S142: Substitute the dynamic correction formula, the light source parameters of the pulsed laser, the normalization coefficient obtained from the singular point, the energy correction parameter of the test system, and the temperature control compensation parameter into the photoacoustic excitation intensity formula to obtain the absorption intensity - photoacoustic excitation intensity calculation formula.

[0093] In the above step S142, the light source parameters of the pulsed laser can be obtained from the factory parameters of the laser emission component, and the absorption zeroing parameter is obtained from the previous steps S131 to S134.

[0094] In the above implementation process, the original Grüneisen formula is corrected by using the correction term of the Grüneisen coefficient in the photoacoustic field, and the obtained dynamic correction formula, together with the light source parameters of the pulsed laser and the absorption zeroing coefficient, is substituted into the photoacoustic excitation intensity formula. The finally obtained absorption intensity - photoacoustic excitation intensity calculation formula further improves the accuracy of temperature measurement.

[0095] Please refer to Figure 6 , Figure 6 which is the specific flowchart of step S180 in the temperature measurement method provided by the embodiments of the present application. In some optional implementation manners, step S180 may include:

[0096] Step S181: Use an image reconstruction algorithm to reconstruct the acoustic wave signal generated during the process of the temperature measurement target absorbing the pulsed laser, and obtain the photoacoustic intensity image slice of the temperature measurement target.

[0097] In the above step S181, the DAS or BP algorithm can be used to reconstruct the photoacoustic signal to obtain the photoacoustic intensity image slice of the object section, from which it can be seen that the photoacoustic intensity is positively correlated with the temperature.

[0098] Among them, regarding the DAS algorithm, its specific process can be:

[0099] 1. Collect photoacoustic signals: Collect photoacoustic signals from multiple detectors (sensors).

[0100] 2. Delay correction: Correct the time delay of the signal according to the distance between each detector and each point in the imaging area.

[0101] 3. Signal weighted sum: Perform a weighted sum on the signals at each position (i.e., superimpose the signals of all detectors after delay).

[0102] 4. Image reconstruction: Map the result of the weighted sum to the image space to obtain the temperature or signal intensity distribution of the imaging area.

[0103] The theoretical formula it is based on can be:

[0104]

[0105] In the formula, represents the signal received by the i-th detector, is the time calculated according to the propagation time delay.

[0106] Delay The calculation formula of

[0107]

[0108] In the formula, is the detector position, is the imaging point position, is the speed of sound.

[0109] Regarding the BP (Back Projection) image reconstruction algorithm, its specific process can be as follows:

[0110] 1. Collect photoacoustic signals: Collect photoacoustic signals from multiple detectors.

[0111] 2. Project the signals into the image space: Back-project the signals of each detector into the image space and calculate its contribution to the imaging area.

[0112] 3. Image accumulation: Accumulate the results of the back-projection of each detector to obtain the final image.

[0113] 4. Image reconstruction: Finally, obtain the temperature or signal intensity distribution of each point in the area.

[0114] The theoretical formula based on this BP algorithm is:

[0115]

[0116] In the formula, is the photoacoustic signal received by the th detector, is the projection factor from the detector to the imaging point .

[0117] The projection factor can be defined as:

[0118]

[0119] In the formula, is the angle between the detector and the imaging point.

[0120] Step S182: Determine the region of interest of the photoacoustic intensity image slice, and calculate the temperature of the region of interest using the absorption intensity - photoacoustic excitation intensity calculation formula to obtain the temperature distribution of the region of interest.

[0121] In the above step S182, those skilled in the art can determine the region of interest of the photoacoustic intensity image slice according to actual application requirements. After determining the region of interest, the temperature of the region of interest can be calculated using the absorption intensity - photoacoustic excitation intensity calculation formula obtained previously.

[0122] In the above implementation process, by using the image reconstruction algorithm to determine the photoacoustic intensity image slice and calculating the temperature distribution of the region of interest in the photoacoustic intensity image slice, not only the accuracy and reliability of the measurement results are further improved, but also more intuitive and comprehensive temperature information is provided.

[0123] In some optional embodiments, step S180 may further include:

[0124] Step S183: Real-time correct the propagation rate of the acoustic wave signal generated by the sample during the absorption of the pulsed laser based on the acoustic wave transmission member.

[0125] In the above step S183, a fixed-length component can be used to calibrate the propagation speed of the acoustic wave signal at multiple temperatures to be measured.

[0126] Correspondingly, step S181 may include:

[0127] Step S1811: Use the image reconstruction algorithm and the propagation rate of the acoustic wave signal to perform image reconstruction on the acoustic wave signal generated by the temperature measurement target during the absorption of the pulsed laser, and obtain a photoacoustic intensity image slice.

[0128] In the above step S1811, by combining the DAS algorithm and the BP algorithm specifically introduced above, the propagation speed of the acoustic wave signal can be introduced during the process of correcting the size of the image reconstruction to ensure that the influence of the temperature change on the sound speed has been taken into account.

[0129] In the above implementation process, by calibrating the propagation speed of the acoustic wave signal at multiple temperatures to be measured and introducing the propagation speed of the acoustic wave signal during the process of correcting the size of the image reconstruction, the accuracy of the reconstructed image size is further improved, thereby further improving the accuracy of the finally measured temperature.

[0130] Please refer to Figure 7 , Figure 7It is a schematic structural diagram of a temperature measuring device 100 provided by an embodiment of the present application. Based on the same concept, an embodiment of the present application further provides a temperature measuring device 100, which may include a controller 110, an acoustic wave sensor 120, a temperature sensor 130, a laser emission component 140, a cuvette 150, a temperature control component 160, and a housing 170. An acoustic wave coupling agent 180 that is isotropic with the measured sample may be provided inside the housing 170. Here, the acoustic wave coupling agent 180 being isotropic with the measured sample does not mean exactly the same in an absolute sense, but rather means that the two are close to being isotropic. Taking the measured object as water, the reference coupling agent materials may be: ethylene glycol, dimethyl silicone oil. The cuvette 150 may be located inside the housing 170 and may be immersed in the acoustic wave coupling agent 180. The cuvette 150 may be used to hold the sample. Taking the measured object as water again, the reference cuvette materials may be: low-density polyethylene, polystyrene. The laser emission component 140 may be located inside the housing 170 and electrically connected to the controller 110. The laser output end of the laser emission component 140 may face the cuvette 150 and may be used to emit pulsed laser towards the cuvette 150. The acoustic wave sensor 120 may be located inside the housing 170 and electrically connected to the controller 110. The acoustic wave acquisition end of the acoustic wave sensor 120 may face the cuvette 150 and may be used to acquire the acoustic wave signal from the cuvette 150. The temperature sensor 130 may be located inside the cuvette 150 and electrically connected to the controller 110. The temperature sensor 130 may be used to acquire the temperature of the sample. The temperature control end of the temperature control component 160 may be located inside the housing 170 and immersed in the acoustic wave coupling agent 180. The temperature control component 160 is electrically connected to the controller 110. The controller 110 may be used to execute each of the method steps described above.

[0131] Specifically, the controller 110 may be a computer, the temperature sensor 130 may specifically be a combination of a thermocouple and a temperature data acquisition instrument, and the laser emission component 140 may include a laser 141 and a laser controller 110.

[0132] The temperature control component 160 may control the acoustic wave coupling agent 180 inside the housing 170 based on the temperature set by the computer, so as to control the temperature of the cuvette 150 and the sample.

[0133] The thermocouple may detect the temperature of the sample in the cuvette 150 and send the generated temperature signal to the temperature data acquisition instrument, and the temperature data acquisition instrument then sends the temperature signal to the computer, and the computer may record the temperature data at the corresponding time.

[0134] The laser controller 110 can control the power of the pulsed laser based on the settings of the computer, and control the laser 141 to emit pulsed laser. After the sample absorbs the pulsed light, heat is generated, and due to thermal expansion and contraction, vibrations generate sound waves. The acoustic couplant 180 transmits the sound waves, which are received by the acoustic sensor 120 and sent to the acoustic signal collector. After integration, they are sent to the computer and stored.

[0135] The above implementation process can be the same as the temperature measurement method described previously, and will not be elaborated here.

[0136] Please continue to refer to Figure 7 , in some optional embodiments, the temperature control component 160 can include a constant temperature medium container 161, a heat conducting member 162, and a pipeline 163. The constant temperature medium container 161 can contain a constant temperature medium and is electrically connected to the controller 110. The heat conducting member 162 can have a flow channel for the constant temperature medium to flow through and can be located inside the housing 170 and immersed in the acoustic couplant 180. The heat conducting member 162 can be connected to the constant temperature medium container 161 through the pipeline 163. The constant temperature medium container 161 can be configured to adjust the temperature of the constant temperature medium under the control of the controller 110 and make the constant temperature medium flow through the flow channel of the heat conducting member 162.

[0137] The constant temperature medium container 161 can be a constant temperature circulating water tank, which can control the temperature of the internal constant temperature medium and make the constant temperature medium circulate between the constant temperature circulating water tank and the heat conducting member 162. Specifically, the constant temperature medium can be water, and the heat conducting member 162 can be a spiral coil made of heat conducting material.

[0138] In the above implementation process, by forming the temperature control component 160 with the constant temperature medium container 161, the heat conducting member 162, and the pipeline 163, while controlling the temperature of the cuvette 150 and the sample, the structure of the temperature control component 160 is also simplified.

[0139] Please continue to refer to Figure 7 , in some optional embodiments, the laser emission component 140 can include a laser 141 and a combined lens 142. The laser 141 is electrically connected to the controller 110 and can be used to emit pulsed laser under the control of the controller 110. The combined lens 142 is located on the optical path of the laser emitted by the laser 141 and can be used to shape the laser emitted by the laser 141, modulate the wavelength and spot shape. <Object:

[0140] The combined lens 142 can be located between the laser 141 and the cuvette 150. Specifically, it can be an aspherical lens group, a birefringent lens group, etc.

[0141] In the above implementation process, the pulsed laser emitted by the laser 141 is shaped by the combined lens 142, ensuring the precise irradiation of the pulsed laser on the sample, thereby further improving the accuracy of temperature measurement.

[0142] For the convenience of further understanding, please refer to FIG. 8. Figure 8 FIG. 5 is a perspective view of a temperature measurement device 100 provided by another embodiment of the present application. The temperature measurement device 100 provided by another embodiment of the present application may include: a heat-insulating housing 4, two connectors 1 for the constant temperature circulating liquid pipeline 3, a set of constant temperature circulating liquid pipelines 3, a perforated upper plate 5, a fixing device 2 for a photoacoustic probe 6, a photoacoustic probe 6, a set of sample clamps 7, and a sample cuvette 8. The photoacoustic probe 6 is a photoacoustic transceiver composed of a laser generator and a pulsed laser combined lens, which can emit a specified laser on the sample through control, and at the same time transmit the acoustic signal to the acoustic signal collector through an acoustic couplant. The heat-insulating housing 4 can support the upper plate 5 and cooperate with the upper plate 5 to form a liquid container. The container has connection holes for pipeline connection so that the pipeline can partially extend and be fixed in the container, and has threaded holes that can be connected to the fixing device 2 of the photoacoustic probe 6 to fix the relative positions of the photoacoustic probe 6 and the sample. In addition, the container has line holes for the entry of optical fibers, sensor wiring harnesses, etc. The fixing device 2 connected to the container can cooperate with the photoacoustic probe 6 and the sample clamp 7 through flanges to fix the relative spatial positions between the photoacoustic probe 6 and the sample cuvette 8, ensuring the measurement accuracy.

[0143] Based on the same concept, an embodiment of the present application also provides a storage medium, which includes a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and when the computer program is run by a processor, it executes the method described above.

[0144] Since when the entire temperature measurement system operates, the laser source, wavelength controller, ultrasonic collector, temperature measurement device, and temperature control device need to perform time frame synchronization and data sharing across multiple devices. Therefore, time synchronization can also be performed when executing the method described above.

[0145] Due to data throughput reasons, it is recommended to use an SSD hard disk with a capacity of more than 8T or use a pool of multiple solid-state hard disks for storage to ensure the requirements during data storage and processing.

[0146] Due to the limitation of the data frame frequency, too low data frames will seriously affect the photoacoustic relaxation phenomenon, and thus affect the photoacoustic signal intensity. It is recommended to use a memory of more than 64GB, and preferably use a 128GB memory for the average batch processing of data frames.

[0147] Among them, the computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0148] In several embodiments provided by the embodiments of the present application, it should be understood that the disclosed method can also be implemented in other ways. Each block in the flowchart or block diagram may represent a segment or a part of the code, and the segment or part of the code includes one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order from that marked in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the flowchart and the combination of blocks in the block flowchart can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0149] The above description is only an optional implementation manner of the embodiments of the present application, but the protection scope of the embodiments of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the embodiments of the present application can easily think of changes or substitutions, which should be covered within the protection scope of the embodiments of the present application.

Claims

1. A method for measuring temperature, characterized in that: include: The measurement system is used to measure the absorbance of the sample to the pulse laser at different temperatures, and a relationship curve between temperature and absorbance is obtained; The original Grignard coefficient was corrected using the correction term of Grignard coefficient in the field of photoacoustics to obtain the calculation formula of absorption intensity-photoacoustic excitation intensity between absorbance and sound wave intensity. Further, the absorbance-temperature curve at this wavelength is introduced to obtain the sound wave intensity-temperature fitting formula of the target to be measured; as well as The ROI region signal after image reconstruction using a photoacoustic reconstruction algorithm is brought into the acoustic wave intensity-temperature fitting formula to obtain the temperature of the target to be measured; The original Grignard coefficient is corrected by using the correction term of the Grignard coefficient in the photoacoustic field to obtain the absorption intensity-photoacoustic excitation intensity calculation formula between absorbance and sound wave intensity, including: The original photoacoustic correction term of thermal saturation caused by absolute temperature change in the photoacoustic field is used to correct the original photoacoustic, and the photoacoustic dynamic formula in the photoacoustic excitation-absolute temperature change correction formula and the dynamic correction term introduced by the absolute temperature change are obtained; among them, The dynamic correction term introduced by the absolute temperature change is: ； The corrected photoacoustic dynamic correction formula is: ； Where ∆p_AT is the correction term caused by absolute temperature change, λ i is the wavelength, μ a is the light absorption coefficient, p0 is the corrected photoacoustic pressure, F pulse is the light flux of a single pulse, b is a constant that can at least characterize the physical properties of the sample material and the measurement system, is the thermal relaxation time constant, is the thermal energy conversion efficiency, is the base Grüneisen coefficient, is the time interval between pulses of the pulsed laser; Substituting the dynamic correction formula, the light source parameters of the pulsed laser, the normalization coefficient obtained from the singular point, the energy correction parameters of the test system, and the temperature control compensation parameters into the photoacoustic excitation intensity formula to obtain the absorption intensity-photoacoustic excitation intensity calculation formula; The ROI region signal after image reconstruction using the photoacoustic reconstruction algorithm is brought into the absorption intensity-photoacoustic excitation intensity calculation formula to obtain the temperature of the target to be measured, including: Reconstructing an image of the acoustic wave signal generated when the temperature-measured target absorbs the pulsed laser using an image reconstruction algorithm to obtain a photoacoustic intensity image slice of the temperature-measured target; and The region of interest of the photoacoustic intensity image slice is determined, and the temperature of the region of interest is calculated using the absorption intensity-photoacoustic excitation intensity calculation formula to obtain the temperature distribution of the region of interest.

2. The method according to claim 1, characterized in that The method comprises measuring the absorbance of the sample to the pulsed laser at different temperatures using the measurement system and obtaining a relationship curve between the temperature and the absorbance, including: Measuring the absorption spectra of the samples at different temperatures using a spectrophotometer; and A relationship curve between temperature and absorbance is determined according to the absorption spectrum.

3. The method according to claim 1, characterized in that After measuring the absorbance of the sample to the pulsed laser at different temperatures using the measurement system and obtaining a relationship curve between temperature and absorbance, the method further includes: The absorption singular point in the relationship curve where the sample temperature is insensitive to changes in absorbance is used to correct the error of the test system; wherein the error includes the systematic error of the laser energy stability and the temperature control device and the gross error of the measurement; the absorption singular point is a point where the maximum absorption difference is less than 0.001abs, and the maximum temperature difference in the temperature range during the correction of the test system does not exceed the temperature difference threshold of the test system.

4. The method according to claim 3, characterized in that The method of using the absorption singular point in the relationship curve that is insensitive to changes in sample temperature with absorbance to correct the error of the test system includes: Using the absorption singular point to perform normalization correction on the absorption intensity range; Correct the laser energy stability; Correcting system errors of temperature control devices; and Correct for gross measurement errors.

5. The method according to claim 1, wherein The ROI region signal after image reconstruction using the photoacoustic reconstruction algorithm is brought into the acoustic wave intensity-temperature fitting formula to obtain the temperature of the target to be measured, further comprising: The real-time correction is based on the propagation rate of the acoustic wave signal generated by the sample during the absorption of the pulse laser by the acoustic wave conductive member; The method of reconstructing an image of the acoustic wave signal generated by the target to be temperature measured during absorption of the pulsed laser by an image reconstruction algorithm to obtain a photoacoustic intensity image slice of the target to be temperature measured includes: The image reconstruction algorithm and the propagation rate of the wave signal are used to reconstruct the acoustic wave signal generated when the temperature-measured target absorbs the pulse laser, so as to obtain the photoacoustic intensity image slice.

6. A temperature measuring device, characterized in that: Including a controller, an acoustic wave sensor, a temperature sensor, a laser emission component, a cuvette, a temperature control component and a housing; An acoustic wave coupling agent isotropic with the sample to be tested is provided in the housing; The cuvette is located in the housing and is immersed in the acoustic couplant; the cuvette is used to hold a sample; the cuvette is made of a material that is isotropic with the sample being measured, uniform, and has high light transmittance; The laser emitting assembly is located in the housing and is electrically connected to the controller; the laser output end of the laser emitting assembly faces the cuvette and is used to emit pulsed laser light toward the cuvette; The acoustic wave sensor is located in the housing and is electrically connected to the controller; the acoustic wave collecting end of the acoustic wave sensor faces the cuvette and is used to collect the acoustic wave signal from the cuvette; The temperature sensor is located in the cuvette and is electrically connected to the controller; the temperature sensor is used to collect the temperature of the sample; The temperature control end of the temperature control component is located in the housing and immersed in the acoustic wave coupling agent; the temperature control component is electrically connected to the controller; The controller is configured to execute the method according to any one of claims 1 to 5.

7. The temperature measuring device according to claim 6, characterized in that: The temperature control assembly includes a constant temperature medium container, a heat conducting member and a pipeline; The constant temperature medium container contains a constant temperature medium and is electrically connected to the controller; The heat conducting member has a flow channel for the constant temperature medium to flow, and is located in the housing and immersed in the acoustic wave coupling agent; The heat conducting member is connected to the constant temperature medium container through the pipeline; The constant temperature medium container is configured to adjust the temperature of the constant temperature medium under the control of the controller and allow the constant temperature medium to flow through the flow channel of the heat conducting member.

8. The temperature measuring device according to claim 7, characterized in that: The laser emission assembly includes a laser and a combined lens; The laser is electrically connected to the controller and is used to emit pulsed laser under the control of the controller; The combined lens is located on the optical path of the laser emitted by the laser, and is used to shape the laser emitted by the laser and modulate the wavelength and spot shape.

9. A storage medium, characterized in that: The storage medium comprises a computer-readable storage medium; a computer program is stored on the computer-readable storage medium, and the computer program executes the method according to any one of claims 1 to 5 when executed by a processor.

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