CN111504496B - Signal processing method for fluorescence demodulation temperature - Google Patents
Signal processing method for fluorescence demodulation temperature Download PDFInfo
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- 238000004364 calculation method Methods 0.000 claims description 5
- 241001198707 Aglia tau Species 0.000 claims description 3
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- 238000013213 extrapolation Methods 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 230000001360 synchronised effect Effects 0.000 claims description 3
- 238000012935 Averaging Methods 0.000 claims description 2
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- 238000009529 body temperature measurement Methods 0.000 description 1
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- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
- G01K11/3213—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering using changes in luminescence, e.g. at the distal end of the fibres
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Abstract
The invention relates to a signal processing method for fluorescence demodulation temperature, which solves the problems of large fluctuation of fluorescence lifetime demodulation results and low single-index fitting accuracy caused by weak fluorescence lifetime attenuation waveform, and comprises the following steps: the method comprises the following steps: respectively collecting continuous fluorescence excitation waveforms and fluorescence attenuation waveforms; step two: obtaining the initial point and the final point of each fluorescence excitation waveform; step three: obtaining a complete fluorescence attenuation waveform; step four: obtaining a fluorescence attenuation waveform after eliminating Gaussian white noise; step five: establishing a double-index fluorescence attenuation waveform model, and including the following steps: obtaining initial values of afterglow intensity a and afterglow intensity b; step seven: performing least square fitting on the double-index fluorescence attenuation waveform model, calculating to obtain an optimal fitting parameter, and calculating the fluorescence life to obtain the fluorescence life; step eight: and comparing the fluorescence lifetime obtained in the step seven with the existing fluorescence lifetime table to obtain a temperature value.
Description
Technical Field
The invention relates to a fluorescent optical fiber temperature sensing detection technology, in particular to a signal processing method for fluorescence demodulation temperature.
Background
The basic principle of fluorescence thermometry is that the fluorescence lifetime of fluorescent substances shows a certain correlation with temperature in a certain temperature range, so that the temperature can be measured through the fluorescence lifetime at different temperatures. According to the atomic transition principle, when light irradiates on a fluorescent substance, electrons in the fluorescent substance obtain energy so as to change from a ground state to an excited state, the fluorescent substance emits fluorescence by radiation energy emitted from the excited state returning to the ground state, the continuous emission time of the fluorescence depends on the life of the ground state after the excitation light is removed, the final attenuation curve is similar to an exponential attenuation mode, the time constant of the attenuation, namely the fluorescence life, is a single-value function of temperature, and the corresponding temperature is calculated by detecting the life of the fluorescence generated after excitation.
The method is characterized in that the fluorescence life is rapidly and accurately obtained, which is the key of fluorescence life temperature measurement, and in the process of solving the fluorescence life, because a fluorescence life attenuation signal is collected by a photoelectric detector, the signal amplitude after photoelectric conversion is small, generally in the mV level, the fluorescence attenuation signal is easily influenced by an interference signal, so that the signal-to-noise ratio of an effective signal is low, and finally, the fluorescence life demodulation result fluctuates greatly. In addition, the fluorescence lifetime attenuation signal is acquired by the photoelectric detector, and the photoelectric detector has certain sensitivity, namely, the front section of the fluorescence lifetime attenuation signal has certain non-exponential tendency. When the fluorescent material is excited to generate electron transition, several possible energy levels exist, photons with different energies are generated during transition, so that a spectrum has multiple spectral lines, namely, a fluorescence attenuation waveform is formed by overlapping several fluorescence attenuation waveforms, so that the fluorescence life is not exponentially inclined, and the single-index fitting accuracy is low.
Disclosure of Invention
The invention aims to solve the problems that the conventional fluorescence lifetime attenuation waveform is a weak signal, so that the fluorescence lifetime demodulation result has large fluctuation and the single-exponential fitting accuracy is low, and provides a signal processing method for fluorescence demodulation temperature.
The technical scheme of the invention is as follows:
a signal processing method for fluorescence demodulation temperature, comprising the steps of:
the method comprises the following steps: respectively collecting continuous fluorescence excitation waveforms and fluorescence attenuation waveforms;
step two: differentiating the acquired fluorescence excitation waveform, and judging the rising edge and the falling edge of the fluorescence excitation waveform to obtain the initial point and the final point of each fluorescence excitation waveform in each period;
step three: recording the serial numbers of the initial point and the final point of the fluorescence excitation waveform, and dividing the fluorescence attenuation waveform according to the serial numbers to obtain a complete fluorescence attenuation waveform;
step four: continuously collecting for multiple times, completely overlapping the fluorescence attenuation waveforms of each period, and overlapping and averaging each fluorescence attenuation waveform to obtain the fluorescence attenuation waveform with Gaussian white noise eliminated;
step five: establishing a double-exponential fluorescence attenuation waveform model,
I(t)＝a×exp(-t/τ1)+b×exp(-t/τ2)+c
dividing the fluorescence attenuation waveform obtained in the step four into two attenuation waveforms with different fluorescence life values through a double-exponential fluorescence attenuation waveform model, wherein I is fluorescence intensity; a. tau is1The afterglow intensity coefficients of one of the attenuation waveformsA fluorescence lifetime value; b. tau is2Respectively is the afterglow intensity coefficient and the fluorescence lifetime value of another attenuation waveform, and t is time; c is a direct current component;
step six: initializing parameters, initializing afterglow intensities a and b, continuously recording 100 fluorescence attenuation values according to a plurality of existing fluorescence attenuation wave waveforms at the termination time of an excitation pulse, and calculating the average value of the fluorescence attenuation values to be used as initial values of the afterglow intensities a and b;
step seven: obtaining an initial value through the sixth step, performing least square fitting on the double-exponential fluorescence attenuation waveform model, and calculating to obtain optimal fitting parameters a, b and tau1、τ2The fluorescence lifetime tau can be obtained by parameter calculation,
step eight: and comparing the fluorescence lifetime obtained in the step seven with the existing fluorescence lifetime table to obtain a temperature value.
Furthermore, if the fluorescence lifetime constant obtained in step seven exists in the table, the fluorescence lifetime constant directly corresponds to the temperature value corresponding to the fluorescence lifetime constant.
And further, if the fluorescence lifetime constant obtained in the step seven is between two adjacent standard fluorescence lifetimes of the check list, using a linear interpolation method to obtain a corresponding temperature value.
And further, the fluorescence lifetime constant obtained in the step seven is outside the standard fluorescence lifetime constant of the check table, and a corresponding temperature value is obtained by adopting a linear extrapolation method.
Further, in the first step, continuous fluorescence excitation waveforms and fluorescence attenuation waveforms are respectively collected through an AD synchronous data acquisition card.
Compared with the prior art, the invention has the following technical effects:
the invention provides a signal processing method for fluorescence demodulation temperature, which can eliminate the influence of local disturbance of measured data on fluorescence lifetime demodulation to a great extent by a double-exponential fitting method, and can fit the non-exponential trend of a fluorescence lifetime attenuation waveform, reduce fitting errors and improve fitting accuracy. The method reduces the influence of interference noise on the whole system, and greatly limits the interference of direct current components, background noise and the like on effective signals.
Drawings
FIG. 1 is a schematic representation of fluorescence excitation signals according to the present invention;
FIG. 2 is a schematic of the fluorescence decay signal of the present invention;
FIG. 3 is a schematic representation of the fluorescence excitation signal after differentiation in accordance with the present invention;
FIG. 4 is a schematic diagram of the initial and final points of a fluorescence excitation waveform of the present invention;
FIG. 5 is a schematic representation of a plurality of fluorescence decay waveforms of the present invention;
FIG. 6 is a schematic diagram of fluorescence attenuation waveforms after elimination of white Gaussian noise according to the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
A signal processing method for fluorescence demodulation temperature, comprising the steps of:
the method comprises the following steps: as shown in fig. 1 and fig. 2, continuous fluorescence excitation waveforms and fluorescence attenuation waveforms are respectively collected by an AD synchronous data acquisition card;
step two: as shown in fig. 3, the fluorescence excitation waveform is e (t), and the initial point and the final point of the fluorescence excitation waveform in each period can be obtained by differentiating the collected fluorescence excitation waveform and determining the rising edge and the falling edge of the fluorescence excitation waveform;
e(tn)＝E(tn+1)-E(tn)
wherein n is 0,1, 2.;
step three: as shown in FIG. 4, the initial point and final point of the fluorescence excitation waveform are recorded
Represents) serial number, and the fluorescence attenuation waveform is divided according to the serial number to obtain the complete fluorescence attenuation waveformThe fluorescence attenuation waveform of (a);
step four: as shown in fig. 5 and 6, the fluorescence attenuation waveforms of each cycle are continuously collected for a plurality of times, and the collection points of the fluorescence lifetime attenuation waveforms are superposed and averaged, so that the measurement error caused by the white gaussian noise can be effectively eliminated, and the fluorescence attenuation waveforms after the white gaussian noise is eliminated are obtained;
step five: establishing a double-exponential fluorescence attenuation waveform model,
I(t)＝a×exp(-t/τ1)+b×exp(-t/τ2)+c
dividing the fluorescence attenuation waveform obtained in the step four into two attenuation waveforms with different fluorescence life values through a double-exponential fluorescence attenuation waveform model; wherein I is the fluorescence intensity; a. tau is1The afterglow intensity coefficient (the amplitude of the fluorescence attenuation wave) and the fluorescence lifetime value of one attenuation waveform are respectively; b. tau is2Respectively is the afterglow intensity coefficient (the amplitude of the fluorescence attenuation wave) and the fluorescence life value of another attenuation waveform, and t is time; c is a direct current component;
step six: initializing parameters, initializing afterglow intensities a and b, continuously recording 100 fluorescence attenuation values according to a plurality of existing fluorescence attenuation wave waveforms at the termination time of an excitation pulse, and calculating the average value of the fluorescence attenuation values to be used as initial values of the afterglow intensities a and b;
step seven: obtaining an initial value through the sixth step, performing least square fitting on the double-exponential fluorescence attenuation waveform model, and calculating to obtain optimal fitting parameters a, b and tau1、τ2The fluorescence lifetime tau can be obtained by parameter calculation,
the least square fitting process is as follows:
FIG. 6 shows the fluorescence lifetime decay waveform after elimination of white Gaussian noise, where the given data point is (t)i,yi) i-0, 1,2,3Calculating a sampling interval and establishing a one-dimensional array; the fluorescent waveform sampling point is calculated according to the sampling rate and is a time abscissa ti；
Now, I (t) ═ a × exp (-t/τ) is obtained1)+b×exp(-t/τ2) + c, such that
Therefore, the above problems become
M＝M(a,b,τ1,τ2,c)
The problem of extreme values of (a);
the coefficient matrix of the upper equation set is a symmetrical positive definite matrix, so that a unique solution exists;
step eight: and comparing the fluorescence lifetime obtained in the step seven with the existing fluorescence lifetime table to obtain a temperature value.
If the fluorescence lifetime constant obtained by calculation exists in the table, the temperature value corresponding to the fluorescence lifetime constant is directly corresponding to the fluorescence lifetime constant; when the fluorescence lifetime constant obtained in the step seven is between two adjacent standard fluorescence lifetimes of the check table, obtaining a corresponding temperature value by using a linear interpolation method; and when the fluorescence lifetime constant obtained in the step seven is outside the standard fluorescence lifetime constant of the check meter, obtaining a corresponding temperature value by adopting a linear extrapolation method.
And measuring and calculating the fluorescence lifetime of the full-temperature section, wherein the fluorescence lifetime of the full-temperature section is basically in a linear relation with the temperature. If the relationship is non-linear, there is a possibility that one fluorescence lifetime corresponds to a plurality of temperature points, which may cause an error in output temperature.
The method can effectively improve the calculation accuracy of the fluorescence lifetime.
Claims (5)
1. A signal processing method for fluorescence demodulation temperature, comprising the steps of:
the method comprises the following steps: respectively collecting continuous fluorescence excitation waveforms and fluorescence attenuation waveforms;
step two: differentiating the acquired fluorescence excitation waveform, and judging the rising edge and the falling edge of the fluorescence excitation waveform to obtain the initial point and the final point of each fluorescence excitation waveform in each period;
step three: recording the serial numbers of the initial point and the final point of the fluorescence excitation waveform, and dividing the fluorescence attenuation waveform according to the serial numbers to obtain a complete fluorescence attenuation waveform;
step four: continuously collecting for multiple times, completely overlapping the fluorescence attenuation waveforms of each period, and overlapping and averaging each fluorescence attenuation waveform to obtain the fluorescence attenuation waveform with Gaussian white noise eliminated;
step five: establishing a double-exponential fluorescence attenuation waveform model,
I(t)＝a×exp(-t/τ1)+b×exp(-t/τ2)+c
dividing the fluorescence attenuation waveform obtained in the step four into two attenuation waveforms with different fluorescence life values through a double-exponential fluorescence attenuation waveform model; wherein I is the fluorescence intensity; a. tau is1Respectively is the afterglow intensity coefficient and the fluorescence lifetime value of one of the attenuation waveforms; b. tau is2Respectively is the afterglow intensity coefficient and the fluorescence lifetime value of the other attenuation waveform; t is time; c is a direct current component;
step six: initializing parameters, initializing afterglow intensities a and b, continuously recording 100 fluorescence attenuation values according to a plurality of existing fluorescence attenuation wave waveforms at the termination time of an excitation pulse, and calculating the average value of the fluorescence attenuation values to be used as initial values of the afterglow intensities a and b;
step seven: obtaining an initial value through the sixth step, performing least square fitting on the double-exponential fluorescence attenuation waveform model, and calculating to obtain optimal fitting parameters a, b and tau1、τ2The fluorescence lifetime tau can be obtained by parameter calculation,
step eight: and comparing the fluorescence lifetime obtained in the step seven with the existing fluorescence lifetime table to obtain a temperature value.
2. The signal processing method for fluorescence demodulation temperature according to claim 1, characterized in that: and if the fluorescence lifetime obtained in the step seven exists in the existing fluorescence lifetime table, directly obtaining a temperature value corresponding to the fluorescence lifetime.
3. The signal processing method for fluorescence demodulation temperature according to claim 1, characterized in that: and seventhly, if the fluorescence lifetime obtained in the step seven is between two adjacent standard fluorescence lifetimes in the existing fluorescence lifetime table, obtaining a temperature value corresponding to the fluorescence lifetime by using a linear interpolation method.
4. The signal processing method for fluorescence demodulation temperature according to claim 1, characterized in that: and if the fluorescence lifetime obtained in the step seven is beyond the standard fluorescence lifetime in the existing fluorescence lifetime table, obtaining a temperature value corresponding to the fluorescence lifetime by adopting a linear extrapolation method.
5. The signal processing method for fluorescence demodulation temperature according to any one of claims 1 to 4, characterized in that: in the first step, continuous fluorescence excitation waveforms and fluorescence attenuation waveforms are respectively collected through an AD synchronous data acquisition card.
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| JPS5830628A (en) * | 1981-08-15 | 1983-02-23 | Machida Oputo Giken:Kk | Method and device for measuring temperature |
| US5107445A (en) * | 1990-12-04 | 1992-04-21 | Luxtron Corporation | Modular luminescence-based measuring system using fast digital signal processing |
| JP4459390B2 (en) * | 2000-06-08 | 2010-04-28 | 浜松ホトニクス株式会社 | Fluorescence measurement method, fluorescence measurement apparatus, and sample evaluation apparatus using the same |
| CN100510716C (en) * | 2005-12-20 | 2009-07-08 | 北京交通大学 | Method and device for measuring fluorescence life time excited by periodical random wave form |
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Denomination of invention: A signal processing method for fluorescence demodulation temperature Effective date of registration: 20220422 Granted publication date: 20211112 Pledgee: CITIC Bank Limited by Share Ltd. Xi'an branch Pledgor: XI'AN HEQI OPTO-ELECTRONIC TECHNOLOGY CO.,LTD. Registration number: Y2022610000183 |
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