Calibration method for optical temperature measurement uncertainty, optical temperature measurement method and calibration device
By fitting with a double exponential function and processing multiple interference radiation signals, the problem of calibrating the temperature measurement uncertainty of fluorescence thermometry in complex environments was solved, and higher accuracy temperature measurement was achieved.
Patent Information
- Application Number
- CN202410753109.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-12
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2044-06-12
AI Technical Summary
Existing fluorescence thermometry methods struggle to accurately determine temperature measurement uncertainty in complex environments, especially under high-temperature conditions where the fluorescence decay curve exhibits non-single exponential characteristics, leading to a decrease in the fluorescence signal-to-noise ratio and affecting measurement accuracy.
A double exponential function is used to fit the fluorescence decay curve. Combined with multiple interference radiation signals, the temperature calculation and experimental uncertainty are determined by the fluorescence lifetime function and calibration function, which is applicable to complex fluorescence decay processes.
It improves the accuracy and precision of temperature measurement in complex environments using fluorescence thermometry, expands its applicability, and is particularly effective in determining temperature uncertainty more accurately under high-temperature conditions.
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Figure CN118654780B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of optical temperature measurement, in particular to an optical temperature measurement uncertainty calibration method, an optical temperature measurement method and a calibration device. BACKGROUND
[0002] The optical temperature measurement method (i.e. the fluorescence temperature measurement method) is an active optical temperature measurement method, which realizes surface temperature measurement based on fluorescence radiation information generated under light source excitation by coating a fluorescent coating on the surface of an object. Compared with the thermal radiation temperature measurement method, the fluorescence temperature measurement method has good anti-interference performance and overcomes the influence of unknown surface emissivity. The fluorescence temperature measurement method mainly includes two types of fluorescence intensity ratio temperature measurement method and fluorescence lifetime temperature measurement method, the former is suitable for dynamic and static target measurement, and the latter is suitable for static target measurement. Generally, the fluorescence lifetime temperature measurement method has higher temperature measurement accuracy and is widely used in the fields of biological medicine, aerospace, etc. In application, the fluorescence measurement will be disturbed by factors such as background radiation, path absorption and scattering, which reduces the signal-to-noise ratio of the fluorescence signal and further affects the fluorescence temperature measurement accuracy. The temperature measurement uncertainty obtained by calibration is difficult to directly guide the actual measurement. In addition, due to the time-varying characteristics of the actual measurement environment, the statistical method of calculating the standard deviation by multiple repeated measurements to obtain the temperature uncertainty is invalid. Therefore, how to obtain the temperature measurement uncertainty of the fluorescence lifetime temperature measurement method based on single fluorescence signal measurement data has been a difficult problem in actual environmental testing.
[0003] At present, in the research of fluorescence temperature measurement uncertainty, a single exponential function is usually used to fit the fluorescence decay curve, and the temperature measurement uncertainty is obtained based on the error transfer function theory. For example, by selecting a fitting window through an iterative algorithm, a single exponential function is used to fit the fluorescence decay curve, and the calculation uncertainty of temperature measurement of three kinds of fluorescent powder samples is determined. In addition, the temperature uncertainty can also be determined based on the weighted linear regression statistical method, and the prediction uncertainty of temperature is obtained. However, due to the diversity of the interaction between the doping ions and the matrix of the temperature measurement fluorescent material, the high-temperature fluorescence decay curve will show non-single exponential decay characteristics. For complex fluorescence decay processes, how to quantitatively determine the fluorescence temperature measurement uncertainty still needs to be solved. SUMMARY
[0004] In view of the above problems, the present application provides an optical temperature measurement uncertainty calibration method, an optical temperature measurement method and a calibration device,
[0005] As a first aspect of the present application, the optical temperature measurement uncertainty calibration method comprises:
[0006] subjecting the target object to different temperatures, obtaining the fluorescence lifetime of the target object at each temperature according to a double exponential function and fluorescence decay curves of the target object at each temperature; the fluorescence decay curve represents a curve of a fluorescence signal generated by the target object changing with time after stopping excitation of a pulsed laser, and the double exponential function includes a first decay part and a second decay part, the first decay part corresponds to a first decay process of the fluorescence signal, and the second decay part corresponds to a second decay process of the fluorescence signal;
[0007] obtaining a fluorescence lifetime function according to the fluorescence lifetime of the target object at different temperatures, the fluorescence lifetime function representing a function of the lifetime of the fluorescence signal changing with temperature;
[0008] obtaining a temperature calculation uncertainty of the target object at each temperature and a temperature experimental uncertainty of the target object at each temperature according to the fluorescence lifetime function;
[0009] obtaining a calibration function of the optical temperature measurement uncertainty of the target object according to the temperature calculation uncertainty of the target object at all temperatures and the temperature experimental uncertainty of the target object at all temperatures, the calibration function being used to complete determination of the optical temperature measurement uncertainty.
[0010] According to an embodiment of the present application, at each temperature, the target object is subjected to multiple interference radiation signals with different intensities; for each intensity of the interference radiation signal, the fluorescence decay curve of the target object has multiple;
[0011] obtaining the fluorescence lifetime of the target object at each temperature according to a double exponential function and fluorescence decay curves of the target object at each temperature includes:
[0012] for each temperature, when the intensity of the interference radiation signal is a preset value, obtaining the fluorescence lifetime of the target object at each temperature according to the fluorescence lifetime of the target object corresponding to all the fluorescence decay curves.
[0013] According to an embodiment of the present application, obtaining the fluorescence lifetime of the target object corresponding to each fluorescence decay curve of the target object according to each fluorescence decay curve of the target object and the double exponential function includes:
[0014] fitting each fluorescence decay curve of the target object by using the double exponential function to obtain a first parameter pair and a second parameter pair corresponding to each fluorescence decay curve of the double exponential function; the first decay part includes the first parameter pair, and the second decay part includes the second parameter pair;
[0015] The fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained according to the first parameter pair and the second parameter pair.
[0016] According to an embodiment of the present application, for each temperature, when the intensity of the interference radiation signal is a preset value, the fluorescence lifetime of the target object at each temperature is obtained according to the fluorescence lifetime of the target object corresponding to all fluorescence decay curves at each temperature.
[0017] For each temperature, the fluorescence lifetime of the target object corresponding to all fluorescence decay curves at each intensity of the interference radiation signal is obtained by averaging the fluorescence lifetime of the target object corresponding to all fluorescence decay curves at each intensity of the interference radiation signal.
[0018] According to an embodiment of the present application, the fluorescence lifetime function is obtained according to the fluorescence lifetime of the target object at different temperatures.
[0019] The fluorescence lifetime function is obtained by performing a third-order polynomial fitting on the different temperatures of the target object and the fluorescence lifetime function at different temperatures.
[0020] According to an embodiment of the present application, for each temperature, the uncertainty of the fluorescence lifetime of the target object corresponding to each fluorescence decay curve at each intensity of the interference radiation signal is obtained by fitting each fluorescence decay curve at each intensity of the interference radiation signal.
[0021] According to an embodiment of the present application, the temperature calculation uncertainty of the target object at each temperature comprises:
[0022] For each temperature, the calculation uncertainty of the target object corresponding to each intensity of the interference radiation signal;
[0023] According to the fluorescence lifetime function, the temperature calculation uncertainty of the target object at each temperature comprises:
[0024] For each temperature, the temperature calculation uncertainty of the target object corresponding to each fluorescence decay curve is obtained according to the uncertainty of the fluorescence lifetime of the target object corresponding to each fluorescence decay curve at each intensity of the interference radiation signal and the fluorescence lifetime function.
[0025] For each temperature, the temperature calculation uncertainty of the target object corresponding to each intensity of the interference radiation signal is obtained by averaging the temperature calculation uncertainty of the target object corresponding to all fluorescence decay curves at each intensity of the interference radiation signal.
[0026] According to an embodiment of the present application, the temperature experimental uncertainty of the target object at each temperature comprises:
[0027] for each temperature, an experimental uncertainty of the target object corresponding to each intensity of the interfering radiation signal;
[0028] obtaining, according to the fluorescence lifetime function, an experimental temperature of the target object corresponding to each fluorescence decay curve for each intensity of the interfering radiation signal;
[0029] obtaining, according to the fluorescence lifetime function, an experimental temperature of the target object corresponding to each fluorescence decay curve for each intensity of the interfering radiation signal;
[0030] obtaining, according to the fluorescence lifetime function, an experimental temperature of the target object corresponding to each fluorescence decay curve for each intensity of the interfering radiation signal;
[0031] According to an embodiment of the present application, obtaining a calibration function of the optical temperature measurement uncertainty of the target object according to the temperature calculation uncertainty of the target object at all temperatures and the temperature experimental uncertainty of the target object at all temperatures comprises:
[0032] fitting, at all temperatures, a polynomial to the temperature experimental uncertainty of the target object at all intensities of the interfering radiation signal and the temperature calculation uncertainty of the target object corresponding to each intensity of the interfering radiation signal, to obtain the calibration function of the optical temperature measurement uncertainty of the target object.
[0033] According to an embodiment of the present application, the double exponential function is expressed as:
[0034] I ph,norm (t i )=I ph (t i ) / I ph (t0)=A 1,n exp(-t i / τ1)+A 2,n exp(-t i / τ2)
[0035] wherein I ph,norm represents a normalized fluorescence intensity, A 1,n and τ1 are a first pair of parameters, A 2,n and τ2 are a second pair of parameters, t i is the i-th time after the pulsed laser stops exciting, I ph (t i ) is the fluorescence intensity at the i-th time after the pulsed laser stops exciting, and I ph (t0) is the fluorescence intensity at the 0-th time after the pulsed laser stops exciting.
[0036] As a second aspect of the present application, an optical temperature measurement method is also provided, comprising:
[0037] obtaining a plurality of fluorescence decay curves generated by the object to be measured under excitation of pulsed laser;
[0038] obtaining a fluorescence lifetime and a fluorescence lifetime uncertainty corresponding to each fluorescence decay curve of the object to be measured according to a double exponential function and each fluorescence decay curve of the object to be measured;
[0039] obtaining a measurement temperature of the object to be measured according to the fluorescence lifetime and the fluorescence lifetime function corresponding to each fluorescence decay curve;
[0040] obtaining a temperature calculation uncertainty corresponding to each fluorescence decay curve of the object to be measured according to the fluorescence lifetime uncertainty corresponding to each fluorescence decay curve of the object to be measured and the fluorescence lifetime function;
[0041] obtaining a temperature measurement uncertainty corresponding to each fluorescence decay curve of the object to be measured according to the temperature calculation uncertainty corresponding to each fluorescence decay curve of the object to be measured and a calibration function;
[0042] wherein the fluorescence lifetime function and the calibration function are determined by the calibration method described above.
[0043] As a third aspect of the present application, an optical temperature measurement uncertainty calibration device is also provided, which is used to implement the calibration method described above, and comprises:
[0044] a temperature-controllable heating furnace in which a target object is placed, a detection window being formed on the temperature-controllable heating furnace, the temperature-controllable heating furnace being adapted to control the temperature of the target object so that the target object has different temperatures;
[0045] a pulsed laser adapted to emit pulsed laser, the pulsed laser passing through the detection window and being incident on a fluorescent material on the surface of the target object so that the target object generates a fluorescence signal;
[0046] a photodetector adapted to collect the fluorescence signal generated by the target object after the pulsed laser stops and convert the fluorescence signal into an electrical signal to obtain a fluorescence decay curve;
[0047] a calculation component adapted to determine the optical temperature measurement uncertainty according to a double exponential function and the fluorescence decay curve of the target object at each temperature.
[0048] According to the embodiments of the present application, the calibration device further comprises:
[0049] The interference radiation signal source is suitable for emitting interference radiation signals, and the interference radiation signals are incident on the surface of the target object through the detection window.
[0050] According to the embodiment of the present application, the calibration device further comprises:
[0051] The coupling assembly is suitable for reflecting the pulsed laser generated by the laser to make the pulsed laser pass through the detection window, and is also suitable for transmitting the fluorescent signal from the target object.
[0052] The light filtering assembly is suitable for filtering the laser signal transmitted through the coupling assembly.
[0053] The collection assembly is suitable for collecting the filtered fluorescent signal and transmitting the collected fluorescent signal to the photodetector.
[0054] According to the embodiment of the present application, the calibration device further comprises:
[0055] The timing control assembly is suitable for controlling the working states of the pulsed laser, the photodetector and the interference radiation source.
[0056] The calibration method according to the embodiment of the present application applies a double exponential function to a complex fluorescent decay process (the fluorescent decay curve presents a non-single exponential decay characteristic) including multiple decay processes, and realizes the determination of the temperature uncertainty in optical temperature measurement. The calibration method of the embodiment of the present application is more accurate and has a wider application range than the calibration method of the temperature uncertainty using a single exponential function. BRIEF DESCRIPTION OF DRAWINGS
[0057] Figure 1 A flowchart of the calibration method of the optical temperature measurement uncertainty according to the embodiment of the present application is shown;
[0058] Figure 2 A calibration device of the optical temperature measurement uncertainty according to the embodiment of the present application is shown;
[0059] Figure 3 A flowchart of the calibration method of the optical temperature measurement uncertainty according to one specific embodiment of the present application is shown;
[0060] Figure 4 The relationship between the temperature experimental uncertainty and the temperature calculation uncertainty according to the embodiment of the present application is shown;
[0061] Figure 5 A flowchart of the optical temperature measurement method according to one specific embodiment of the present application is shown.
[0062] EXPLANATION OF REFERENCE NUMBERS
[0063] 1 temperature-controllable heating furnace
[0064] 1-1 detection window
[0065] 2 pulsed laser
[0066] 3 photodetector
[0067] 4 computing component
[0068] 5 interference radiation signal source
[0069] 6 coupling component
[0070] 7 filtering component
[0071] 8 collection component
[0072] 9 target object
[0073] 10 timing control component
[0074] 11 first interface
[0075] 12 second interface DETAILED DESCRIPTION
[0076] In the process of implementing the present application, it is found that the temperature uncertainty calibration method for the existing fluorescence temperature measurement method has limitations and difficulty problems, and it is of great significance to develop a temperature measurement uncertainty calibration method and device for the fluorescence lifetime temperature measurement method with a wide range of applications.
[0077] To make the objectives, technical solutions and advantages of the present application clearer and more apparent, the present application is further described in detail below with reference to the specific embodiments and the accompanying drawings.
[0078] Figure 1 A flowchart of the optical temperature uncertainty calibration method provided by the embodiment of the present application is shown.
[0079] As shown in Figure 1 , the flow of the optical temperature uncertainty calibration method includes operation S110 to operation S140.
[0080] In operation S110, the target object is at different temperatures. The fluorescence lifetime of the target object at each temperature is obtained according to a double exponential function and a fluorescence decay curve of the target object at each temperature. The fluorescence decay curve represents the curve of the fluorescence signal generated by the target object changing with time after stopping the excitation of the pulsed laser. The double exponential function includes a first decay part and a second decay part. The first decay part corresponds to the first decay process of the fluorescence signal, and the second decay part corresponds to the second decay process of the fluorescence signal.
[0081] In operation S120, a fluorescence lifetime function is obtained according to the fluorescence lifetime of the target object at different temperatures, and the fluorescence lifetime function represents a function of the lifetime of the fluorescence signal changing with temperature.
[0082] In operation S130, a temperature calculation uncertainty of the target object at each temperature and a temperature experimental uncertainty of the target object at each temperature are obtained according to the fluorescence lifetime function.
[0083] In operation S140, a calibration function of the optical temperature measurement uncertainty of the target object is obtained according to the temperature calculation uncertainty of the target object at all temperatures and the temperature experimental uncertainty of the target object at all temperatures, and the calibration function is used to realize determination of the optical temperature measurement uncertainty.
[0084] According to the calibration method of the embodiment of the present application, the double exponential function is applied to a complex fluorescence decay process (the fluorescence decay curve presents a non-single exponential decay characteristic) including multiple decay processes, and determination of the temperature uncertainty in optical temperature measurement is realized. The calibration method of the embodiment of the present application is more accurate and has a wider application range than the calibration method of the temperature uncertainty using the single exponential function.
[0085] According to the embodiment of the present application, in operation S110, the temperature of the target object is controlled, that is, the target object can be respectively at different temperatures in a time sequence.
[0086] According to the embodiment of the present application, at each temperature, the target object is applied with multiple interference radiation signals with different intensities, and the fluorescence decay curve of the target object has multiple curves for each intensity of the interference radiation signal. The interference radiation signal is suitable for simulating a typical background radiation interference scene in optical temperature measurement, such as high-temperature radiation of fuel gas, high-temperature spontaneous radiation, etc.
[0087] In operation S110, the fluorescence lifetime of the target object at each temperature is obtained according to the double exponential function and the fluorescence decay curve of the target object at each temperature, including operation S111 to operation S112.
[0088] In operation S111, for each temperature, for each intensity of the interference radiation signal, the fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained according to each fluorescence decay curve of the target object and the double exponential function.
[0089] In operation S112, for each temperature, the fluorescence lifetime of the target object at each temperature is obtained according to the fluorescence lifetime of the target object corresponding to all the fluorescence decay curves at each temperature when the intensity of the interference radiation signal is a preset value. The preset value may, for example, be 0.
[0090] According to an embodiment of the present application, in operation S111, the fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained according to each fluorescence decay curve of the target object and a double exponential function, including operation S1111-S1112.
[0091] In operation S1111, each fluorescence decay curve of the target object is fitted by using a double exponential function to obtain a first parameter pair and a second parameter pair corresponding to each fluorescence decay curve; the first decay part includes the first parameter pair, and the second decay part includes the second parameter pair.
[0092] In operation S1112, the fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained according to the first parameter pair and the second parameter pair.
[0093] According to an embodiment of the present application, the fluorescence decay curve has temperature dependence, and the temperature of the object can be determined according to the fluorescence decay lifetime information in the fluorescence decay curve, which is the basic principle of fluorescence lifetime thermometry. Due to the coupling effect of multiple energy relaxation, the fluorescence decay curve often shows non-single exponential function decay characteristics, and the fluorescence decay process can be expressed as formula (1).
[0094] I ph (t i )=A1exp(-t i / w1)+A2exp(-t i / w2)(1)
[0095] Wherein, A1 is the coefficient of the first decay part, i.e. the initial segment fast decay part, w1 is the fluorescence lifetime constant of the first decay part, i.e. the initial segment fast decay process, A2 is the coefficient of the second decay part, i.e. the initial segment fast decay part, w2 is the fluorescence lifetime constant of the second decay part, i.e. the initial segment fast decay process.I ph (t i ) is the fluorescence intensity at the i-th moment after the pulsed laser stops excitation, I ph (t0) is the fluorescence intensity at the 0-th moment after the pulsed laser stops excitation, in practical application, it is usually necessary to normalize the intensity of formula (1) at t=t0, taking I ph (t0) as the reference, and dividing both sides of formula (1) by I ph (t0), the normalized fluorescence intensity I ph,norm is obtained, and the double exponential function is obtained.
[0096] According to an embodiment of the present application, the double exponential function is expressed as formula (2).
[0097] I ph,norm (t i )=I ph (ti ) / I ph (t0)=A′1exp(-t i / w1)+A′2exp(-t i / w2) (2)
[0098] wherein I ph,norm represents a normalized fluorescence intensity, A'1 and w1 are a first parameter pair, A'2 and w2 are a second parameter pair, wherein A'1 represents a normalized exponential term coefficient of a first decay part, w1 represents a fluorescence lifetime constant of the first decay part, A'2 represents a normalized exponential term coefficient of a second decay part, and w2 represents a fluorescence lifetime constant of the second decay part, t i represents an i-th time after the pulsed laser stops exciting, I ph (t i ) represents a fluorescence intensity at an i-th time after the pulsed laser stops exciting, and I ph (t0) represents a fluorescence intensity at a 0-th time after the pulsed laser stops exciting.
[0099] When the fluorescence decay curve is fitted by using the double exponential function, the fitting parameter vector p = (A'1, w1, A'2 and w2) of the fluorescence lifetime function can be obtained when the residual sum of squares χ * ph,norm of the experimental measurement value I ph,norm and the function fitting value I 2 is the minimum value.
[0100]
[0101] wherein l is the number of points of the fluorescence decay curve data fitting.
[0102] According to the embodiment of the present application, at each temperature, a plurality of double exponential fluorescence decay curves of the target object can be obtained for each intensity of the interference radiation signal. The double exponential function is used to fit any double exponential fluorescence decay curve Dd obtained at any temperature T s and any intensity of the interference radiation signal B b to obtain a group of A'1, w1, A'2 and w2 values. The corresponding A'1, w1, A'2 and w2 values of any double exponential fluorescence decay curve D s at any temperature T b and any intensity of the interference radiation signal B d can be combined with formula (3) to obtain the corresponding fluorescence lifetime τ s of the double exponential fluorescence decay curve D b at temperature T d and the interference radiation signal B s,b,dWherein, b represents the serial number of the interference radiation signal, b≥1, d≥1, s represents the serial number of different temperatures s≥1.
[0103]
[0104] According to the embodiment of the present application, in operation S112, for each temperature, the fluorescence lifetime of the target object at each temperature is obtained according to the fluorescence lifetime of the target object corresponding to all the fluorescence decay curves at each temperature when the intensity of the interference radiation signal is the preset value, including: for each temperature, the fluorescence lifetime of the target object corresponding to all the fluorescence decay curves is averaged to obtain the fluorescence lifetime of the target object at each temperature when the intensity of the interference radiation signal is the preset value.
[0105] According to the embodiment of the present application, according to formula (4), when the temperature is T s , the interference radiation signal is B1, and B1=0, the fluorescence lifetime τ d of any double-exponential fluorescence decay curve D s,1,d can be expressed as formula (5).
[0106]
[0107] According to the embodiment of the present application, when the temperature is T s , the interference radiation signal is B1=0, the fluorescence lifetime τ s of the target object at any temperature T s is obtained by averaging the fluorescence lifetime of all the fluorescence decay curves.
[0108] According to the embodiment of the present application, in operation S120, the fluorescence lifetime function is obtained according to the fluorescence lifetime of the target object at different temperatures, including: performing a third-order polynomial fitting on the different temperatures of the target object and the fluorescence lifetime function at different temperatures to obtain the fluorescence lifetime function τ(T). The fluorescence lifetime function τ(T) represents the relationship between the fluorescence lifetime and the temperature.
[0109] According to the embodiment of the present application, for each temperature, the uncertainty of the fluorescence lifetime of the target object corresponding to each fluorescence decay curve under each intensity of the interference radiation signal is obtained by fitting each fluorescence decay curve under each intensity of the interference radiation signal.
[0110] According to the embodiment of the present application, the fluorescence lifetime function τ(T) is related to the four fitting parameters (A'1, w1, A'2, w2), therefore, for any temperature T s , the uncertainty u b of the fluorescence lifetime of the target object corresponding to any fluorescence decay curve D d under any interference radiation signal B s,b,d is expressed as formula (6).
[0111]
[0112] where p = (A'1, w1, A'2, w2) represents the fitting parameter vector of the fluorescence lifetime function. is the uncertainty of the mth fitting parameter p m , m = 1 ~ 4. is the covariance of the fitting parameters p m and p n , m = 1 ~ 4, n = 1 ~ 4.
[0113] The uncertainty of the fitting parameters p m and p n in equation (6) is obtained based on the residual square χ 2 (p) and the covariance The residual square χ 2 (p) is obtained based on equation (3), and the covariance is obtained based on equation (7). Equation (7) is represented as follows.
[0114]
[0115] where q is the number of fitting parameters (q = 4); F is the partial derivative matrix (dimension: l x q), where
[0116] According to an embodiment of the present application, the temperature calculation uncertainty of the target object at each temperature comprises, for each temperature, a calculation uncertainty of the target object corresponding to each intensity of the interference radiation signal.
[0117] According to an embodiment of the present application, obtaining the temperature calculation uncertainty of the target object at each temperature according to the fluorescence lifetime function comprises operations S131-S132 in operation S130.
[0118] In operation S131, for each temperature, the temperature calculation uncertainty of the target object corresponding to each fluorescence decay curve is obtained according to the uncertainty of the fluorescence lifetime of the target object corresponding to each fluorescence decay curve and the fluorescence lifetime function under each intensity of the interference radiation signal.
[0119] According to an embodiment of the present application, the optical temperature measurement depends on the fluorescence lifetime function τ(T), which determines the accuracy of the optical temperature measurement, and therefore, the temperature calculation uncertainty u b of the target object corresponding to any fluorescence decay curve D d under the interference radiation signal B T,cal,s,b,d at temperature T s is represented as:
[0120]
[0121] Among them, u ref,s,b,d =u s,b,d / τ represents the relative uncertainty of fluorescence lifetime; It is the relative temperature sensitivity of fluorescence lifetime.
[0122] In operation S132, for each temperature, the temperature calculation uncertainty of the target object corresponding to all fluorescence decay curves under each intensity of interference radiation signal is averaged to obtain the temperature calculation uncertainty of the target object corresponding to each intensity of interference radiation signal.
[0123] For example, at a temperature of T s For interference radiated signal strength B b The average of the temperature uncertainties corresponding to all fluorescence decay curves at time T is used to obtain the temperature. s The target object corresponds to the interference radiation signal B. b Temperature calculation uncertainty.
[0124] According to an embodiment of the present invention, the experimental uncertainty of the target object at each temperature includes: the experimental uncertainty of the target object corresponding to each intensity of the interference radiation signal at each temperature.
[0125] In operation S130, the experimental uncertainty of the target object at each temperature is obtained based on the fluorescence lifetime function, including operations S133 to S134.
[0126] In operation S133, for each temperature, the experimental temperature of the target object corresponding to each fluorescence decay curve is obtained based on the fluorescence lifetime and fluorescence lifetime function of the target object under each intensity of interference radiation signal.
[0127] According to an embodiment of the present invention, for each temperature T s According to the interference radiation signal B b The target object corresponds to the fluorescence decay curve D. d The fluorescence lifetime and fluorescence lifetime function are used to obtain the fluorescence decay curve D corresponding to the target object. d The experimental temperature T exp,s,b,d .
[0128] Operation S134: For each temperature, calculate the standard deviation of the experimental temperature of the target object corresponding to all fluorescence decay curves under each intensity of interfering radiation signal to obtain the experimental temperature uncertainty u of the target object corresponding to each intensity of interfering radiation signal. T,exp,s,b .
[0129]
[0130] wherein, in formula (9), u T,exp,s,b represents the temperature experiment uncertainty of the target object at the temperature T s , the intensity of the interference radiation signal B b represents the average value of the experimental temperature of the target object corresponding to the fluorescence decay curve at the temperature T s , the intensity of the interference radiation signal B b
[0131] According to the embodiment of the present application, in operation S140, the calibration function of the optical temperature measurement uncertainty of the target object is obtained according to the temperature calculation uncertainty of the target object at all temperatures and the temperature experiment uncertainty of the target object at all temperatures, comprising: performing a polynomial fitting on the temperature experiment uncertainty of the target object at all intensities of the interference radiation signal and the temperature calculation uncertainty of the target object corresponding to each intensity of the interference radiation signal at all temperatures, to obtain the calibration function of the optical temperature measurement uncertainty of the target object.
[0132] As a second aspect of the present application, an optical temperature measurement method is also provided, comprising operations S210-S250.
[0133] In operation S210, a plurality of fluorescence decay curves generated by the target object under excitation of pulsed laser are obtained.
[0134] In operation S220, the fluorescence lifetime and the fluorescence lifetime uncertainty corresponding to each fluorescence decay curve of the target object are obtained according to the double exponential function and each fluorescence decay curve of the target object.
[0135] In operation S230, the measurement temperature of the target object is obtained according to the fluorescence lifetime corresponding to each fluorescence decay curve and the fluorescence lifetime function.
[0136] In operation S240, the temperature calculation uncertainty corresponding to each fluorescence decay curve of the target object is obtained according to the fluorescence lifetime uncertainty corresponding to each fluorescence decay curve of the target object and the fluorescence lifetime function.
[0137] In operation S250, the temperature measurement uncertainty corresponding to each fluorescence decay curve of the target object is obtained according to the temperature calculation uncertainty corresponding to each fluorescence decay curve of the target object and the calibration function.
[0138] wherein, the fluorescence lifetime function and the calibration function are determined by the calibration method described above.
[0139] Figure 2 A calibration device of optical temperature measurement uncertainty is shown according to the embodiment of the present application. As shown in Figure 4 As shown, the calibration device comprises a temperature-controllable heating furnace 1, a pulsed laser 2, a photodetector 3 and a computing component 4.
[0140] The temperature-controllable heating furnace 1 has a target object 9 placed inside, and a detection window 11 is formed on the temperature-controllable heating furnace 1. The temperature-controllable heating furnace 1 is suitable for controlling the temperature of the target object, so that the target object has different temperatures. VAL represents the current temperature, and SET represents the temperature setting value. The temperature-controllable heating furnace 1 is used for heating the target object 9, and the temperature of the target object 9 is monitored and controlled by a PID circuit. The pulsed laser 2 is suitable for emitting pulsed laser, and the pulsed laser passes through the detection window 11 and is incident on the fluorescent material on the surface of the target object, so as to make the target object generate a fluorescent signal. The wavelength of the pulsed laser can be selected as 355 nm, 532 nm and 1064 nm, and the energy of the pulsed laser can be continuously adjusted. The laser and the system optical path module are connected through a flange, and the emitted laser is reflected to the sample surface through the excitation detection coupling optical path module.
[0141] The photodetector 3 is suitable for collecting the fluorescent signal generated by the target object after the pulsed laser stops, and converting the fluorescent signal into an electrical signal to obtain a fluorescent decay curve. The computing component 4 is suitable for determining the optical temperature measurement uncertainty according to a double exponential function and the fluorescent decay curve of the target object at each temperature.
[0142] According to the embodiment of the present application, the above-mentioned calibration device further comprises an interference radiation signal source 5, which is suitable for emitting an interference radiation signal, and the interference radiation signal is incident on the surface of the target object through the detection window 1-1. The interference radiation source 5 is used to simulate the typical background radiation interference scene of fluorescent temperature measurement, such as high-temperature radiation of gas, high-temperature spontaneous radiation, etc.
[0143] According to the embodiment of the present application, the above-mentioned calibration device further comprises a coupling component 6, a light filtering component 7 and a collection component 8. The coupling component 6 is suitable for reflecting the pulsed laser generated by the pulsed laser 2, so that the pulsed laser passes through the detection window 1-1. The coupling component 6 is also suitable for transmitting the fluorescent signal from the target object. The light filtering component 7 is suitable for filtering the laser signal transmitted through the coupling component 6. The collection component 8 is suitable for collecting the filtered fluorescent signal, and transmitting the collected fluorescent signal to the photodetector 3. The coupling component 6, the light filtering component 7 and the collection component 8 are located inside the system optical path module. The system optical path module is used for optically detecting the target object 9 in the temperature-controllable heating furnace 1, and two optical interfaces and a detection window 1-1 are connected to the outside of the system optical path module. The detection window is located on the sample side, and is used for transmitting laser to the sample surface and collecting the excitation fluorescent signal from the sample surface. The first interface 11 is used for connecting with the laser, and the second interface 12 is connected to the photodetector through a flange
[0144] The photodetector 3 is connected to the system optical path module via a flange. The fluorescence signal passes sequentially through the coupling component 6, the filter component 7, and the collection component 8. Fluorescence signals in specific wavelength bands are acquired by the photodetector 3, and the converted electrical signals are displayed, calculated, analyzed, and stored in the computing component 4. The photodetector 3 is typically a high-gain photomultiplier tube.
[0145] According to an embodiment of the present invention, the calibration device further includes: a timing control component 11, which is adapted to control the operating status of the pulsed laser 2, the photodetector 3 and the interference radiation source 5.
[0146] Figure 3 A flowchart of a method for calibrating optical temperature measurement uncertainty according to a specific embodiment of the present invention is shown.
[0147] According to embodiments of the present invention, specific embodiments are listed below in conjunction with... Figures 2-3 The calibration method for optical temperature measurement uncertainty of the present invention will be described in detail.
[0148] In this embodiment, YSZ:Dy is coated on the surface. 3+ Taking target object 9 with fluorescent coating as an example for explanation. The YSZ:Dy coating on the surface of target object 9... 3+ The fluorescent coating was prepared using an atmospheric plasma spraying process. The substrate of the target object 9 was a nickel-based high-temperature alloy, and the thickness of the fluorescent coating was ~30μm.
[0149] The calibration method for optical temperature measurement uncertainty includes steps A1 to A10.
[0150] Step A1: Place the target object 9 to be tested in the temperature-controlled heating furnace 1, and turn on the temperature-controlled heating furnace 1, pulse laser 2, photodetector 3 and other equipment.
[0151] Step A2: Set the temperature of the controllable temperature heating furnace 1 to T. s .
[0152] Step A3: Set the interference radiation intensity to B b b = 1, 2...10.
[0153] Step A4: Collect N fluorescence decay curves.
[0154] Step A5: Adjust the intensity of the interference radiation signal to B b+1 There is B b+1 >B b And B1 = 0, repeat steps A4 to A5 until b = M and M = 10.
[0155] Step A6: Set the temperature of the controllable heating furnace to T. s+1 There is Ts+1 T s , repeat steps A3-A6 until s=Q, Q=7; T s+1 with T s temperature interval is 100℃.
[0156] Step A7: Nonlinear least squares fitting is performed on all the obtained fluorescence decay curves using a double exponential function to obtain the fluorescence lifetime and the uncertainty of the fluorescence lifetime corresponding to each fluorescence decay curve. The specific fitting process is shown in equations (1)-(6).
[0157] Step A8: For temperature T s , under the interference radiation intensity B1=0, the average value of the Y fluorescence lifetimes obtained by fitting is recorded as τ s , τ s is the fluorescence lifetime at temperature T s . The fluorescence lifetimes at different temperatures and different temperatures are fitted by a third-order polynomial to obtain the fluorescence lifetime function τ(T).
[0158] Step A9: For any temperature T s and interference radiation intensity B b , first, according to the uncertainty of the fluorescence lifetime corresponding to any one fluorescence decay curve D d and the fluorescence function calibrated in step (8), the temperature calculation uncertainty u T,cal,s,b,d can be obtained. The average value of the Y temperature calculation uncertainties under any temperature T s and interference radiation intensity B b . Secondly, according to the fluorescence lifetime corresponding to any one fluorescence decay curve D d and the fluorescence function calibrated in step (9), the temperature experimental uncertainty can be obtained. The average value of the Y temperature experimental uncertainties under any temperature T s and interference radiation intensity B b .
[0159] Step A10: Based on the temperature experimental uncertainty of the target object corresponding to each intensity of the interference radiation signal and the temperature calculation uncertainty of the target object corresponding to each intensity of the interference radiation signal for each temperature, a polynomial fitting is performed to obtain a calibration function of the optical temperature measurement uncertainty of the target object, which represents the relationship between the temperature calculation uncertainty u cal,s of the target object at all temperatures and the temperature experimental uncertainty u exp,s of the target object at all temperatures, i.e., u exp,s =f(u cal,s ).
[0160] Figure 4The relationship between the temperature experimental uncertainty and the temperature calculation uncertainty provided by the embodiment of the present application is shown.
[0161] As shown in Figure 4 , the temperature experimental uncertainty and the temperature calculation uncertainty obtained from the same target object. The black data points represent a set of temperature calculation uncertainty and experimental uncertainty, i.e., (u ca l ,s ,u exp,s ), obtained under the condition of a certain temperature and a certain intensity of interference radiation signal. The red dashed line is the fitting result of the black data points, and the calibration function of both the temperature calculation uncertainty and the experimental uncertainty, i.e., u exp,s =f(u cal,s ), can be determined according to the fitting result.
[0162] Figure 5 The flowchart of the optical temperature measurement method provided by one specific embodiment of the present application is shown.
[0163] The flow of the optical temperature measurement uncertainty is to provide guidance for the implementation of the optical temperature measurement method in actual measurement. Based on the fluorescence decay curve of a single measurement, the uncertainty of the fluorescence lifetime is obtained through nonlinear least squares fitting. The specific flow is as steps B1 to B8.
[0164] Step B1: The surface of the object to be measured has a fluorescent coating, and the fluorescent coating is YSZ:Dy 3+ For example, the fluorescent coating sample is prepared by atmospheric plasma spraying process, and the substrate of the object to be measured is selected from nickel-based superalloy, and the thickness of the fluorescent coating is about 30 μm.
[0165] Step B2: Turn on the devices such as pulse laser 2 and photodetector 3, set the pulse laser energy to 1 mJ, the repetition frequency to 10 Hz, and the wavelength to 355 nm, and the pulse width to about 10 ns.
[0166] Step B3: Collect a series of fluorescence decay curves, the number R is 1000, and the fluorescence measurement center wavelength is 480 nm.
[0167] Step B4: For each fluorescence decay curve, take the rth curve as an example, the fluorescence lifetime τ r and the uncertainty of the fluorescence lifetime u τ,r are obtained through nonlinear least squares fitting.
[0168] Step B5: The measured temperature Tr can be obtained by combining the fluorescence lifetime τ r and the calibrated fluorescence lifetime function τ(T).
[0169] Step B6: Combining the uncertainty of fluorescence lifetime and the calibrated fluorescence lifetime function τ(T), the temperature calculation uncertainty can be obtained.
[0170] Step B7: Combining the temperature calculation uncertainty and the calibrated function of optical temperature measurement uncertainty, the temperature measurement uncertainty can be obtained.
[0171] Step B8: Through the above process, the measured temperature Tr and the uncertainty of the measured temperature can be obtained for each measurement point r based on a single fluorescence decay curve in the transient environment measurement process. Finally, 1000 measured temperatures and the uncertainty of the measured temperature are obtained.
[0172] The calibration method and device for optical temperature measurement uncertainty provided by the embodiments of the present application can realize reliable evaluation of fluorescence lifetime temperature measurement uncertainty, can be applied to determination of fluorescence lifetime temperature measurement uncertainty based on single measurement data in actual measurement environment, and overcomes the limitation that the temperature uncertainty calibrated in the existing laboratory environment is difficult to be popularized to actual measurement, and is suitable for determination of fluorescence lifetime temperature measurement uncertainty of complex fluorescence decay process with non-single exponential decay characteristics.
[0173] The above specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above are only specific embodiments of the present application and are not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims
1. A method for calibrating the uncertainty of optical temperature measurement, comprising: The target object is subjected to different temperatures, and the fluorescence lifetime of the target object at each temperature is obtained based on the double exponential function and the fluorescence decay curve of the target object at each temperature. The fluorescence decay curve represents the curve of the fluorescence signal generated by the target object changing over time after the excitation of the pulsed laser is stopped. The double exponential function includes a first decay part and a second decay part. The first decay part corresponds to the first decay process of the fluorescence signal, and the second decay part corresponds to the second decay process of the fluorescence signal. A fluorescence lifetime function is obtained based on the fluorescence lifetime of the target object at different temperatures. The fluorescence lifetime function represents the function of the lifetime of the fluorescence signal changing with temperature. The calculated temperature uncertainty and the experimental temperature uncertainty of the target object at each temperature are obtained based on the fluorescence lifetime function. as well as Based on the temperature calculation uncertainty of the target object at all temperatures and the temperature experimental uncertainty of the target object at all temperatures, a calibration function for the optical temperature measurement uncertainty of the target object is obtained. The calibration function is used to determine the optical temperature measurement uncertainty.
2. The calibration method according to claim 1, wherein, At each temperature, the target object is subjected to multiple interference radiation signals of varying intensities; for each intensity of interference radiation signal, the fluorescence decay curve of the target object has multiple lines. Based on the double exponential function and the fluorescence decay curve of the target object at each temperature, the fluorescence lifetime of the target object at each temperature is obtained as follows: For each temperature and for each intensity of the interfering radiation signal, the fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained based on each fluorescence decay curve of the target object and the double exponential function; as well as For each temperature, when the intensity of the interfering radiation signal is a preset value, the fluorescence lifetime of the target object at each temperature is obtained based on the fluorescence lifetime of the target object corresponding to all fluorescence decay curves.
3. The calibration method according to claim 2, wherein, Based on each fluorescence decay curve of the target object and the double exponential function, the fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained as follows: The fluorescence decay curve of the target object is fitted using the biexponential function to obtain a first parameter pair and a second parameter pair corresponding to each fluorescence decay curve; the first decay portion includes the first parameter pair, and the second decay portion includes the second parameter pair; and The fluorescence lifetime of the target object corresponding to each fluorescence decay curve is obtained based on the first parameter pair and the second parameter pair.
4. The calibration method according to claim 2, wherein, For each temperature, when the intensity of the interfering radiation signal is a preset value, the fluorescence lifetime of the target object at each temperature is obtained based on the fluorescence lifetime of the target object corresponding to all fluorescence decay curves at each temperature. This includes: for each temperature, when the intensity of the interfering radiation signal is a preset value, averaging the fluorescence lifetime of the target object corresponding to all fluorescence decay curves at each temperature to obtain the fluorescence lifetime of the target object at each temperature.
5. The calibration method according to claim 1, wherein, The fluorescence lifetime function is obtained based on the fluorescence lifetime of the target object at different temperatures by performing a third-order polynomial fitting on the fluorescence lifetime of the target object at different temperatures and at different temperatures.
6. The calibration method according to claim 2, wherein, For each temperature, each fluorescence decay curve under each intensity of interference radiation signal is fitted to obtain the uncertainty of the fluorescence lifetime of the target object corresponding to each fluorescence decay curve under each intensity of interference radiation signal.
7. The calibration method according to claim 2, wherein, The temperature calculation uncertainty of the target object at each temperature includes: For each temperature, the target object has a temperature calculation uncertainty corresponding to each intensity of interference radiation signal; The temperature calculation uncertainty of the target object at each temperature, obtained based on the fluorescence lifetime function, includes: For each temperature, the temperature calculation uncertainty of the target object corresponding to each fluorescence decay curve is obtained based on the uncertainty of the fluorescence lifetime of the target object corresponding to each fluorescence decay curve under each intensity of interference radiation signal and the fluorescence lifetime function; and For each temperature, the temperature calculation uncertainty of the target object corresponding to all fluorescence decay curves under each intensity of interference radiation signal is averaged to obtain the temperature calculation uncertainty of the target object corresponding to each intensity of interference radiation signal.
8. The calibration method according to claim 2, wherein, The temperature experimental uncertainty of the target object at each temperature includes: For each temperature, the target object corresponds to the experimental uncertainty of each interfering radiation signal; The experimental uncertainties of the target object at each temperature, obtained from the fluorescence lifetime function, include: For each temperature, the experimental temperature of the target object corresponding to each fluorescence decay curve is obtained based on the fluorescence lifetime of the target object corresponding to each fluorescence decay curve under each intensity of interference radiation signal and the fluorescence lifetime function; and For each temperature, the standard deviation of the experimental temperature corresponding to all fluorescence decay curves of the target object under each interfering radiation signal is calculated to obtain the experimental temperature uncertainty of the target object for each intensity of interfering radiation signal.
9. The calibration method according to claim 1, wherein, The calibration function for the optical thermometric uncertainty of the target object, derived from the calculated temperature uncertainty of the target object at all temperatures and the experimental temperature uncertainty of the target object at all temperatures, includes: At all temperatures, the experimental temperature uncertainty of the target object under all intensities of interference radiation signals and the calculated temperature uncertainty of the target object under each intensity of interference radiation signal are subjected to polynomial fitting to obtain the calibration function of the optical temperature measurement uncertainty of the target object.
10. The calibration method according to claim 1, wherein, The double exponential function is expressed as follows: in, Indicates normalized fluorescence intensity. and For the first parameter pair, and For the second parameter pair, At time i after the pulsed laser excitation stops, It is the fluorescence intensity at time i after the pulsed laser excitation stops. It is the fluorescence intensity at moment 0 after the pulsed laser excitation stops.
11. An optical temperature measurement method, comprising: Obtain multiple fluorescence decay curves generated by the object under test under pulsed laser excitation; Based on the double exponential function and each fluorescence decay curve of the test object, the fluorescence lifetime and fluorescence lifetime uncertainty corresponding to each fluorescence decay curve of the test object are obtained. The measured temperature of the object under test is obtained from the fluorescence lifetime and fluorescence lifetime function corresponding to each fluorescence decay curve; The temperature calculation uncertainty corresponding to each fluorescence decay curve of the test object is obtained based on the fluorescence lifetime uncertainty corresponding to each fluorescence decay curve of the test object and the fluorescence lifetime function; as well as The temperature measurement uncertainty corresponding to each fluorescence decay curve of the test object is obtained by calculating the temperature uncertainty and calibration function based on the temperature uncertainty corresponding to each fluorescence decay curve of the test object. The fluorescence lifetime function and the calibration function are determined by the calibration method described in any one of claims 1-10.
12. A calibration device for optical temperature measurement uncertainty, used to implement the calibration method according to any one of claims 1-10, the calibration device comprising: A temperature-controlled heating furnace has a target object placed inside. The temperature-controlled heating furnace has a detection window and is suitable for controlling the temperature of the target object so that the target object has different temperatures. A pulsed laser is used to emit pulsed laser light, which passes through the detection window and is incident on the fluorescent material on the surface of the target object, so as to make the target object generate a fluorescent signal. A photodetector is used to collect the fluorescence signal generated by the target object after the pulsed laser stops, and convert the fluorescence signal into an electrical signal to obtain a fluorescence decay curve; as well as The calculation component is suitable for determining the optical thermometry uncertainty based on a double exponential function and the fluorescence decay curve of the target object at each temperature.
13. The calibration apparatus according to claim 12, further comprising: An interference radiation signal source, suitable for emitting interference radiation signals, which are incident on the surface of the target object through the detection window; The coupling component is adapted to reflect the pulsed laser light generated by the laser so that the pulsed laser light passes through the detection window; the coupling component is also adapted to transmit fluorescence signals from the target object; A filter assembly, suitable for filtering the laser signal transmitted through the coupling assembly; The collection component is suitable for collecting the filtered fluorescence signal and transmitting the collected fluorescence signal to the photodetector; as well as The timing control component is suitable for controlling the operating status of the pulsed laser, the photodetector, and the interference radiation signal source.