Improved ratiometric fluorescent temperature sensing device and temperature detection method

Abstract

This invention discloses an improved ratiometric fluorescence temperature sensing device and temperature detection method, belonging to the field of temperature sensing technology. It includes a temperature-sensitive fluorescent material, two excitation sources of different wavelengths, a spectrometer, a spectrometer, and an imaging optical path. The method includes: the two excitation sources of different wavelengths are excited to the temperature-sensitive fluorescent material by the spectrometer through a common optical path; the fluorescence spectral data of fluorescent substance A is compared with the fluorescence spectral data of fluorescent substance B at the same wavelength to obtain new synthetic fluorescence spectral data; the intensity integral ratio of this new fluorescence spectral data is calculated within a specific range to obtain the fluorescence intensity ratio characterizing the temperature; the change of the intensity integral ratio with temperature is fitted to a temperature calibration curve to obtain the measured temperature. This invention can be applied to harsh environments, is unaffected by losses in the optical path, achieves absolutely accurate non-contact temperature measurement, and features high sensitivity, high precision, high temperature resistance, low manufacturing cost, and is unaffected by laser pump power.

Description

Technical Field

[0001] This invention relates to the field of temperature sensing technology, and in particular to an improved ratiometric fluorescent temperature sensing device and temperature detection method. Background Technology

[0002] Temperature is a fundamental physical quantity in physics, and also a very important and frequently used quantity, closely related to all aspects of production and daily life. Therefore, how to achieve accurate temperature measurement has received widespread attention. In the early history of temperature measurement equipment development, a series of temperature measuring devices appeared, such as thermocouple thermometers, semiconductor thermometers, and capacitance thermometers. However, their sensitivity characteristics, based on electrical signals, made them difficult or even impossible to apply to special environments such as those involving explosives, high voltage, strong electromagnetic fields, or corrosive gases and liquids. Temperature sensing technology based on luminescent materials has advantages such as fast response speed, high measurement accuracy, and intrinsic safety, thus playing an important role in temperature detection in complex and microscopic environments such as flammable and explosive environments, strong acids and alkalis, and even cells.

[0003] Currently, optical temperature sensing technologies mainly include infrared thermometry and fluorescence thermometry. Infrared thermometers determine their measurement range by using different infrared wavelengths, enabling rapid temperature changes. However, infrared thermometers are susceptible to scattering when acquiring data signals, i.e., receiving infrared spectral information, resulting in low spatial resolution, large measurement errors, and low sensitivity. Fluorescence thermometry is typically based on the luminescence intensity or fluorescence intensity ratio (FIR) of luminescent materials. Traditional FIR thermometry measures temperature based on the ratio of the peak intensities of two emission peaks of a material. It usually utilizes the fluorescence peaks of two thermally coupled levels (TCLs). By analyzing the ratio of the intensities of the two fluorescence peaks, interference from non-temperature-related external factors such as excitation power can be eliminated. This method has attracted much attention due to its non-invasive nature, fast response, self-reference, and high sensitivity. However, traditional FIR thermometry cannot withstand the losses during fluorescence signal propagation. When there are strong losses in the optical path, causing overall distortion of the fluorescence signal, the measurement accuracy will be severely compromised. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an improved ratiometric fluorescence temperature sensing device and temperature detection method, which can be applied to harsh environments, is not affected by losses in the optical path, achieves absolutely accurate non-contact temperature measurement, and has the characteristics of high sensitivity, high precision, high temperature resistance, low manufacturing cost, and is not affected by laser pump power.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] An improved ratiometric fluorescence temperature sensing device is characterized by comprising a temperature-sensitive fluorescent material, two excitation light sources of different wavelengths, a spectrometer, a spectrometer, and an imaging optical path.

[0007] The excitation light source is connected to the beam splitter through two imaging optical paths. The beam splitter is connected to the temperature-sensitive fluorescent material placed in the temperature measurement environment through the imaging optical path. The temperature-sensitive fluorescent material is connected to the spectrometer through the imaging optical path. The spectrometer is connected to the processor through a circuit.

[0008] The thermosensitive fluorescent material is formed by uniformly and mechanically mixing two independent fluorescent substances A and B with the same emission wavelength. Fluorescent substances A and B include, but are not limited to, rare earth and transition metal element-doped fluorescent materials and quantum dots.

[0009] A further improvement of the technical solution of the present invention is that: fluorescent material A is Nd3+ doped YGG phosphor, and fluorescent material B is Yb3+ doped YGG phosphor.

[0010] A further improvement of the technical solution of the present invention is that: the two excitation light sources of different wavelengths include laser I and laser II, laser I and laser II include, but are not limited to, lasers and light-emitting diodes, and respectively excite two independent fluorescent substances in the thermosensitive fluorescent material.

[0011] A further improvement to the technical solution of the present invention is that laser I uses a 532nm laser and laser II uses a 980nm laser.

[0012] A further improvement of the technical solution of the present invention is that the beam splitting part includes a beam splitting prism and a beam splitting plate.

[0013] An improved temperature detection method for a ratiometric fluorescent temperature sensor includes the following steps:

[0014] S1. Two excitation sources of different wavelengths are excited to the thermosensitive fluorescent material by the beam splitter through a common optical path. The fluorescence spectrum signal emitted by the fluorescent material A excited by the laser I is used as the detection signal, and the fluorescence spectrum signal emitted by the fluorescent material B excited by the laser II is used as the reference signal.

[0015] S2. The fluorescence spectrum data of fluorescent substance A is compared with the fluorescence spectrum data of fluorescent substance B at the same wavelength to obtain new synthetic fluorescence spectrum data. Then, the fluorescence spectrum data is combined and the intensity integral ratio is taken in a specific range to obtain the intensity integral ratio characterizing the temperature.

[0016] S3. Fit the intensity integral ratio of the above-mentioned synthetic fluorescence spectrum data to a temperature calibration curve, and substitute the intensity integral ratio measured at the unknown temperature into the sensing equation to obtain the measured temperature.

[0017] A further improvement to the technical solution of the present invention is that S1 specifically includes the following steps:

[0018] S11, Under laser I excitation:

[0019]

[0020] When the system reaches steady state We can obtain:

[0021]

[0022] Because N1 and N2 are a pair of thermally coupled energy levels, the following conditions are met:

[0023]

[0024] S12, under laser II excitation:

[0025] Similarly, we can conclude that:

[0026]

[0027] Where N0, N1, N2, N a and N b They represent Nd3+ respectively: 4 I 9 / 2 , 4 F 3 / 2 , 4 F 5 / 2 and Yb3+: 2 F 7 / 2 , 2 F 5 / 2 The total number of particles in the energy level; h and c are Planck's constant and the speed of light, respectively; s I and s II σ represents the spot area of ​​laser I and laser II, respectively. I σ represents the absorption cross section of fluorescent substance A in the I band. II P represents the absorption cross section of fluorescent substance B in the II band; I and P II W1 and W2 represent the pump power of lasers I and II, respectively. b Representing the non-radiative transition rates, C1 and C b ΔE represents the radiative transition rate; T represents the absolute temperature; k represents the Boltzmann constant; D represents a constant; ΔE represents the energy level difference.

[0028] The fluorescence spectral signal intensity emitted by fluorescent substance A changes with temperature differently than that emitted by fluorescent substance B.

[0029] A further improvement to the technical solution of this invention lies in the following S2 process:

[0030] At a given temperature T, the emission intensity I of an electron transitioning from an excited state to the ground state is expressed as:

[0031] I i =N i hν i C i

[0032] i represents different energy levels, N i ν i and C i These represent the number of particles occupying the energy level, the photon frequency of the corresponding transition, and the radiative transition rate, respectively. Following the principles of this invention, the intensity ratio of the improved ratiometric fluorescence temperature detection method is defined as FIR. m :

[0033]

[0034] λ III and λ IV Each represents a specific band at one end;

[0035] Simplifying, we get:

[0036]

[0037] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0038] Compared with existing technologies, the optimized ratiometric fluorescence thermometry method proposed in this invention innovatively introduces a detection signal and a reference signal. By comparing the two, a new set of synthetic fluorescence signals is obtained. Then, the intensity integration ratio of the synthetic fluorescence signals can completely eliminate the influence of laser pump power and optical path loss. It has excellent performance in various harsh temperature measurement environments and is an absolutely accurate non-contact optical thermometry method with many advantages such as high precision, high sensitivity, intrinsic safety, stable performance, corrosion resistance, small size, and low cost. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the temperature measurement system of the present invention;

[0040] Figure 2 The fluorescence spectra of a certain fluorescent substance A (YGG:Nd3+) under excitation light source I (532nm laser) at different temperatures;

[0041] Figure 3 The fluorescence spectra of a certain fluorescent substance B (YGG:Yb3+) under excitation light source II (980nm laser) at different temperatures are shown.

[0042] Figure 4 The process of obtaining the integral intensity ratio at a certain temperature (200℃);

[0043] Figure 5 These are the synthetic fluorescence spectral signals at different temperatures;

[0044] Figure 6 The synthesized fluorescence spectrum signals at different temperatures after adding loss to the emission optical path;

[0045] Figure 7 The temperature measured by this invention is the temperature at 200°C when the pump power of two excitation sources in different wavelength bands fluctuates.

[0046] Figure 8 The temperature measured in this invention is 200°C when the pump power of two excitation sources in different wavelength bands fluctuates and there are losses in the optical path. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0048] An improved ratiometric fluorescence temperature sensing device includes a temperature-sensitive fluorescent material, two excitation sources in different wavelength bands, a spectrometer, a spectrometer, and an imaging optical path.

[0049] The excitation light source is connected to the beam splitter through two imaging optical paths. The beam splitter is connected to the temperature-sensitive fluorescent material placed in the temperature measurement environment through the imaging optical path. The temperature-sensitive fluorescent material is connected to the spectrometer through the imaging optical path. The spectrometer is connected to the processor through a circuit.

[0050] The thermosensitive fluorescent material is formed by uniformly and mechanically mixing two independent fluorescent substances A and B with the same emission wavelength. Fluorescent substances A and B include, but are not limited to, rare earth and transition metal element-doped fluorescent materials and quantum dots.

[0051] Preferably, fluorescent material A is Nd3+ doped YGG phosphor, and fluorescent material B is Yb3+ doped YGG phosphor.

[0052] The two excitation sources of different wavelengths include laser I and laser II, which include, but are not limited to, lasers and light-emitting diodes, and respectively excite two independent fluorescent substances in the thermosensitive fluorescent material. Here, laser I uses a 532nm laser, and laser II uses a 980nm laser.

[0053] The beam-splitting section includes a beam-splitting prism and a beam-splitting plate.

[0054] An improved temperature detection method for a ratiometric fluorescent temperature sensor includes the following steps:

[0055] S1. Two excitation sources of different wavelengths are excited to the thermosensitive fluorescent material by the beam splitter through a common optical path. The fluorescence spectrum signal emitted by the fluorescent material A excited by the laser I is used as the detection signal, and the fluorescence spectrum signal emitted by the fluorescent material B excited by the laser II is used as the reference signal.

[0056] Specifically, the following steps are included:

[0057] S11, Under laser I excitation:

[0058]

[0059] When the system reaches steady state We can obtain:

[0060]

[0061] Because N1 and N2 are a pair of thermally coupled energy levels, the following conditions are met:

[0062]

[0063] S12, under laser II excitation:

[0064] Similarly, we can conclude that:

[0065]

[0066] Where N0, N1, N2, N a and N b They represent Nd3+ respectively: 4 I 9 / 2 , 4 F 3 / 2 , 4 F 5 / 2 and Yb3+: 2 F 7 / 2 , 2 F 5 / 2 The total number of particles in the energy level; h and c are Planck's constant and the speed of light, respectively; s I and s II σ represents the spot area of ​​laser I and laser II, respectively. I σ represents the absorption cross section of fluorescent substance A in the I band. II P represents the absorption cross section of fluorescent substance B in the II band; I and P II W1 and W2 represent the pump power of lasers I and II, respectively. b Representing the non-radiative transition rates, C1 and C b ΔE represents the radiative transition rate; T represents the absolute temperature; K represents the Boltzmann constant; D represents a constant; ΔE represents the energy level difference.

[0067] Among them, the fluorescence spectral signal intensity emitted by fluorescent substance A changes with temperature differently than that emitted by fluorescent substance B.

[0068] S2. The fluorescence spectral data of fluorescent substance A is compared with the fluorescence spectral data of fluorescent substance B at the same wavelength to obtain new synthetic fluorescence spectral data. Then, this combined fluorescence spectral data is used to calculate the intensity integral ratio within a specific range to obtain the intensity integral ratio characterizing the temperature. The process is as follows:

[0069] At a given temperature T, the emission intensity I of an electron transitioning from an excited state to the ground state is expressed as:

[0070] I i =N i hν i C i

[0071] i represents different energy levels, N i ν i and C i These represent the number of particles occupying the energy level, the photon frequency of the corresponding transition, and the radiative transition probability, respectively. Following the principles of this invention, the intensity ratio of the improved ratiometric fluorescence temperature detection method is defined as FIR. m :

[0072]

[0073] λ III and λ IV Each represents a specific band at one end;

[0074] Simplifying, we get:

[0075]

[0076] S3. Integrate the intensity of the above-mentioned synthetic fluorescence spectral data by FIR. m A temperature calibration curve is fitted to the temperature change, and the intensity integral ratio measured at the unknown temperature is substituted into the sensing equation to obtain the measured temperature.

[0077] Example

[0078] like Figure 1The diagram shows the improved ratiometric fluorescence temperature sensing device of this invention, comprising a temperature-sensitive fluorescent material, excitation source I, excitation source II, a spectrometer, a beam splitter, an imaging optical path, and a PC for processing fluorescence signals. The specific description is as follows: The fluorescent material I is placed in the temperature measurement environment. The light signals emitted by excitation source I and excitation source II are coupled into the same optical path through the beam splitter to illuminate the same position on the temperature-sensitive fluorescent material. The emitted light from the temperature-sensitive fluorescent material enters the spectrometer through the imaging optical path, and the corresponding fluorescence spectrum is obtained under the drive of the PC. The obtained fluorescence spectrum is then processed by steps S2 and S3 to obtain the temperature to be measured.

[0079] An improved temperature detection method for a ratiometric fluorescent temperature sensor includes the following steps:

[0080] S1. Two excitation sources of different wavelengths are used by a beam splitter to excite the temperature-sensitive fluorescent material via a common optical path. The fluorescence spectrum signal emitted by fluorescent material A excited by laser I is used as the detection signal, and the fluorescence spectrum signal emitted by fluorescent material B excited by laser II is used as the reference signal. Using N0, N1, N2, N... a and N b They represent Nd3+ respectively: 4 I 9 / 2 , 4 F 3 / 2 , 4 F 5 / 2 and Yb3+: 2 F 7 / 2 , 2 F 5 / 2 The total number of particles in an energy level.

[0081] S11, under the excitation of laser I (532nm laser):

[0082]

[0083] When the system reaches steady state We can obtain:

[0084]

[0085] Because N1 and N2 are a pair of thermally coupled energy levels, the following conditions are met:

[0086]

[0087] S12, under excitation by laser II (980nm laser):

[0088] Similarly, we can conclude that:

[0089]

[0090] Where h and c are Planck's constant and the speed of light, respectively, and s 532 (s 980 ) represents the area of ​​the laser spot, σ 532 (σ 980 ) represents Nd 3+ (Yb 3+ The absorption cross section at 532 nm (980 nm), P 532 (P 980 W1(W) represents the pump power of the laser. b C1(C) represents the non-radiative transition rate. b () represents the radiative transition rate. T represents the absolute temperature, K represents the Boltzmann constant, D represents a constant, and ΔE represents the energy level difference;

[0091] The fluorescence spectral signal intensity emitted by fluorescent substance A (YGG:Nd3+) changes with temperature differently from that emitted by fluorescent substance B (YGG:Yb3+).

[0092] S2. The fluorescence spectral data of fluorescent substance A is compared with the fluorescence spectral data of fluorescent substance B at the same wavelength to obtain new synthetic fluorescence spectral data. Then, the intensity integral ratio of this new set of fluorescence spectral data is calculated within a specific range (e.g., 840-868 nm and 870-880 nm) to obtain the fluorescence intensity ratio characterizing the temperature. The process is as follows:

[0093] At a given temperature T, the emission intensity I of an electron transitioning from an excited state to the ground state is expressed as:

[0094] I i =N i hν i C i

[0095] N i ν i and C i These represent the number of particles occupying the energy level, the photon frequency of the corresponding transition, and the radiative transition rate, respectively. Following the concept of this invention, the intensity ratio of the improved ratiometric fluorescence temperature detection method is defined as FIR. m .

[0096]

[0097] Simplifying, we get:

[0098]

[0099] S3. Integrate the intensity of the above-mentioned synthetic fluorescence spectral data by FIR. mA temperature calibration curve is fitted to the temperature change, and the intensity integral ratio measured at the unknown temperature is substituted into the sensing equation to obtain the measured temperature.

[0100] like Figure 2 The figure shows the fluorescence spectra of a fluorescent substance A (YGG:Nd3+) at different temperatures under excitation by excitation source I (532nm laser). As the temperature increases, the fluorescence intensity in the 840-870nm range shows a thermally enhanced trend; the fluorescence intensity in the 870-890nm range quenches with increasing temperature.

[0101] like Figure 3 The figure shows the fluorescence spectrum of a certain fluorescent substance B (YGG:Yb3+) under excitation by excitation source II (980nm laser) at different temperatures. When the temperature increases, the fluorescence intensity in the 840-930nm range generally shows a thermal enhancement trend.

[0102] like Figure 4 The diagram illustrates the process of obtaining the integrated intensity ratio at a specific temperature (200℃). The fluorescence spectral data of fluorescent substance A is compared with the fluorescence spectral data of fluorescent substance B at the same wavelength to obtain new synthetic fluorescence spectral data. Then, specific intervals of the synthetic fluorescence spectral data (e.g., 840-868 nm and 870-880 nm) are selected for intensity integration. This integrated intensity ratio is the corresponding integrated intensity ratio at 200℃.

[0103] like Figure 5 The figure shows the synthesized fluorescence spectral signals at different temperatures. By fitting this data, the functional relationship between the integrated intensity ratio and temperature is obtained, i.e., the temperature calibration curve.

[0104] like Figure 6 The image shows the synthesized fluorescence spectra at different temperatures after adding loss to the emitted optical path. Figure 5 The results show almost no difference, and this temperature measurement method has good anti-loss performance.

[0105] like Figure 7 As shown, this invention measures the temperature at 200℃ when the pump power of two excitation sources in different wavelength bands fluctuates. The fluorescence thermometry method proposed in this invention can maintain the accuracy of temperature measurement even when the laser pump power fluctuates significantly.

[0106] like Figure 8 As shown, this invention measures the temperature at 200℃ when the pump power of two excitation sources at different wavelengths fluctuates and there are losses in the optical path. The fluorescence thermometry method proposed in this invention can maintain the accuracy of temperature measurement even when the laser pump power fluctuates significantly and there are losses in the optical path.

[0107] In summary, this invention can be applied to harsh environments, is unaffected by losses in the optical path, achieves absolutely accurate non-contact temperature measurement, and features high sensitivity, high precision, high temperature resistance, low manufacturing cost, and is unaffected by laser pump power.

Claims

1. An improved ratiometric fluorescent temperature sensing device, characterized by: It includes thermosensitive fluorescent materials, two excitation sources in different wavelength bands, a spectrometer, a spectrometer, and an imaging optical path; The excitation light source is connected to the beam splitter through two imaging optical paths. The beam splitter is connected to the temperature-sensitive fluorescent material placed in the temperature measurement environment through the imaging optical path. The temperature-sensitive fluorescent material is connected to the spectrometer through the imaging optical path. The spectrometer is connected to the processor through a circuit. The two excitation sources of different wavelengths include laser I and laser II. Laser I and laser II each include a laser and a light-emitting diode, and respectively excite two independent fluorescent substances in the thermosensitive fluorescent material. The thermosensitive fluorescent material is formed by uniformly and mechanically mixing two independent fluorescent substances A and B with the same emission band. Fluorescent substances A and B include rare earth, transition metal element doped fluorescent materials and quantum dots. The temperature detection method using the improved ratiometric fluorescent temperature sensing device described above includes the following steps: S1. Two excitation sources of different wavelengths are excited to the thermosensitive fluorescent material by the beam splitter through a common optical path. The fluorescence spectrum signal emitted by the fluorescent material A excited by the laser I is used as the detection signal, and the fluorescence spectrum signal emitted by the fluorescent material B excited by the laser II is used as the reference signal. S2. The fluorescence spectrum data of fluorescent substance A is compared with the fluorescence spectrum data of fluorescent substance B at the same wavelength to obtain new synthetic fluorescence spectrum data. Then, the fluorescence spectrum data is combined and the intensity integral ratio is calculated in a specific range to obtain the intensity integral ratio characterizing the temperature. S3. Fit the intensity integral ratio of the above-mentioned synthetic fluorescence spectrum data to a temperature calibration curve, and substitute the intensity integral ratio measured at the unknown temperature into the sensing equation to obtain the measured temperature.

2. The improved ratiometric fluorescent temperature sensing device of claim 1, wherein: Fluorescent material A uses Nd3+-doped YGG phosphor, and fluorescent material B uses Yb3+-doped YGG phosphor.

3. The improved ratiometric fluorescent temperature sensing device of claim 1, wherein: Laser I uses a 532 nm laser, and laser II uses a 980 nm laser.

4. The improved ratiometric fluorescent temperature sensing device of claim 1, wherein: The beam-splitting section includes a beam-splitting prism and a beam-splitting plate.

5. The improved ratiometric fluorescent temperature sensing device of claim 1, wherein: S1 specifically includes the following steps: S11, Under laser I excitation: When the system reaches steady state It follows that: because and They are a pair of thermally coupled energy levels, so they satisfy: S12, under laser II excitation: Similarly, we can conclude that: in, , , , and They represent Nd3+ respectively: and Yb3+: The total number of particles in the energy level; h and c are Planck's constant and the speed of light, respectively. and These represent the spot areas of laser I and laser II, respectively. This represents the absorption cross section of fluorescent substance A in the I band. This represents the absorption cross section of fluorescent substance B in the II band. and This indicates the pump power of laser I and laser II; and This represents the non-radiative transition rate. and The radiative transition rate is represented by T, absolute temperature by k, Boltzmann constant by k, and a constant by D. Indicates the energy level difference; The fluorescence spectral signal intensity emitted by fluorescent substance A changes with temperature differently than that emitted by fluorescent substance B.

6. The improved ratiometric fluorescent temperature sensing device of claim 1, wherein: The S2 process is as follows: At a given temperature T, the emission intensity I of an electron transitioning from an excited state to the ground state is expressed as: i represents different energy levels. , and These represent the number of particles occupying the energy level, the photon frequency of the corresponding transition, and the radiative transition rate, respectively. Following the principles of this invention, the intensity ratio of the improved ratiometric fluorescence temperature detection method is defined as... : and represent two specific wavelength bands at the ends, respectively; Simplifying, we get: 。

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