Spectral pressure broadening compensation method, device and equipment of off-axis integral cavity system

Abstract

The invention relates to the technical field of data correction, in particular to a spectral pressure broadening compensation method, device and equipment of an off-axis integral cavity system.The method comprises the steps that a 2f harmonic signal is obtained, fitting is conducted on the 2f harmonic signal through a second Fourier Lorentz linear function, an optimal fitting parameter is calculated, and then according to the optimal fitting parameter, the spectral pressure broadening compensation value of the off-axis integral cavity system is obtained. And finally, according to the pressure calibration coefficient, determining an amplitude calibration equation of the 2f harmonic signal, and according to the amplitude calibration equation, carrying out spectral pressure broadening compensation on the 2f harmonic signal.

Description

Technical Field

[0001] The present invention relates to the technical field of data correction, and in particular to a method, device and equipment for compensating for spectral pressure broadening of an off-axis integrating cavity system. Background Art

[0002] At present, the accuracy, sensitivity and stability of instrument concentration inversion based on off-axis integrated cavity absorption spectroscopy (OA-ICOS) for gas monitoring have been relatively perfect. However, there are significant differences between the OA-ICOS technology used in portable breath diagnosis in static air intake mode and the dynamic air intake mode in the gas monitoring process. The air pressure in the air chamber in static air intake mode is not constant; in addition, since portable instruments need to meet the requirements of fast response and miniaturization, they are usually designed with a small air chamber structure. Therefore, under the dual influence of static air intake and small air chamber volume, the increase in the volume and concentration of the exhaled gas will cause a significant increase in the air pressure in the cavity. At this time, the air pressure change has a significant impact on the accuracy of the monitoring results. However, there is currently no effective theoretical model or method to compensate and correct the influence of pressure increase on the broadening effect of the second harmonic (2f) signal, which seriously reduces the accuracy of the measurement results. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a method, device and apparatus for compensating for spectral pressure broadening of an off-axis integrating cavity system, so as to overcome the problems existing in the current prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present application provides a method for compensating spectral pressure broadening of an off-axis integrating cavity system, comprising:

[0006] Get 2f harmonic signal;

[0007] Fitting the 2f harmonic signal by a second Fourier Lorentzian linear function;

[0008] Calculate best-fit parameters;

[0009] Determining a pressure calibration coefficient according to the best fitting parameters;

[0010] An amplitude calibration equation of the 2f harmonic signal is determined according to the pressure calibration coefficient, and spectral pressure broadening compensation is performed on the 2f harmonic signal according to the amplitude calibration equation.

[0011] Furthermore, in the above method, the step of fitting the 2f harmonic signal by a second Fourier Lorentz linear function comprises:

[0012] According to the Beer-Lambert law, determining the absorption coefficient of the 2f harmonic signal;

[0013] Performing transformation processing on the absorption coefficient;

[0014] Determining the 2f Fourier coefficient of the 2f harmonic signal according to the absorption coefficient after transformation;

[0015] The 2f Fourier coefficients are transformed, and the 2f amplitude of the Lorentz linear function of the 2f harmonic signal is determined according to the transformed 2f Fourier coefficients.

[0016] Furthermore, in the above method, the step of calculating the best fitting parameters includes:

[0017] Obtaining a fitting result of the 2f harmonic signal;

[0018] Determining the goodness of fit of the 2f harmonic signal according to the fitting result;

[0019] When the goodness of fit is less than a preset threshold, refitting the 2f harmonic signal;

[0020] When the goodness of fit is greater than or equal to a preset threshold, the parameters of the second Fourier Lorentz linear function are modified and fitted again until the best fitting parameters are determined.

[0021] Furthermore, the above method further includes:

[0022] According to the state equation of the gas, determine the relationship equation between the pressure and CO2 concentration X in the sealed environment;

[0023] According to the relationship equation, transform the amplitude calibration equation;

[0024] Based on the transformation processing results, the amplitude calibration equation is evaluated.

[0025] Further, in the method described above, the pressure calibration coefficient is:

[0026]

[0027] Where Δv c is the full width at half maximum of the Lorentz lineshape, is the 2f amplitude of the Lorentz line function, is the modulation depth.

[0028] Furthermore, in the above method, the amplitude calibration equation is:

[0029]

[0030] Where k is the pressure calibration factor.

[0031] In a second aspect, the present application provides a spectral pressure broadening compensation device for an off-axis integrating cavity system, comprising:

[0032] A data acquisition module, used for acquiring a 2f harmonic signal;

[0033] A fitting module, used for fitting the 2f harmonic signal through a second Fourier Lorentz linear function to calculate the best fitting parameters;

[0034] The pressure broadening compensation module is used to determine the pressure calibration coefficient according to the best fitting parameters, determine the amplitude calibration equation of the 2f harmonic signal according to the pressure calibration coefficient, and perform spectral pressure broadening compensation on the 2f harmonic signal according to the amplitude calibration equation.

[0035] In a third aspect, the present application provides a spectral pressure broadening compensation device for an off-axis integrating cavity system, including a processor and a memory, wherein the processor is connected to the memory:

[0036] Wherein, the processor is used to call and execute the program stored in the memory;

[0037] The memory is used to store the program, and the program is used to at least execute any one of the above-mentioned spectral pressure broadening compensation methods for the off-axis integrating cavity system.

[0038] The beneficial effects of the present invention are:

[0039] Improve measurement accuracy: By introducing the pressure calibration method, combined with linewidth compensation and modulation depth compensation, the 2f amplitude decrease problem caused by the pressure broadening effect can be effectively corrected, thereby improving the accuracy of gas concentration inversion.

[0040] Reduce system errors: In view of the characteristics of static air intake mode and small air chamber design, the present invention can effectively compensate for the influence of pressure changes on the absorption spectrum, significantly reduce the system errors in the measurement process, and improve the overall measurement reliability. In addition, through the precise pressure calibration method, the present invention can maintain the stability of the second harmonic signal, avoid signal jitter caused by random pressure changes, and make the measurement results have better repeatability and reliability, meeting the medical detection needs of high sensitivity and high stability.

[0041] Adapt to portable design requirements: The method of the present invention does not need to change the compact structure of the existing instrument, is suitable for the miniaturization and rapid response requirements of portable respiratory diagnostic instruments, does not increase the volume and complexity of the equipment, and has high practical application value. Expand application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a flow chart provided by an embodiment of a method for compensating for spectral pressure broadening of an off-axis integrating cavity system of the present invention;

[0044] Figure 2 It is a structural schematic diagram provided by an embodiment of a spectral pressure broadening compensation device of an off-axis integrating cavity system of the present invention;

[0045] Figure 3 It is a structural schematic diagram provided by an embodiment of a spectral pressure broadening compensation device of an off-axis integrating cavity system of the present invention;

[0046] Figure 4 It is a schematic diagram of the structure of a wavelength modulated off-axis integrating cavity provided by an embodiment of a spectral pressure broadening compensation method of an off-axis integrating cavity system of the present invention;

[0047] Figure 5 The spectral pressure broadening compensation method of the off-axis integrating cavity system of the present invention provides 0.08cm under different pressures. -1 A traditional 2f signal diagram with modulation amplitude;

[0048] Figure 6 This is a graph showing the relationship between the 2f amplitude and the CO2 concentration before pressure compensation provided by an embodiment of the spectral pressure broadening compensation method for an off-axis integrating cavity system of the present invention;

[0049] Figure 7 The relationship between the 2f amplitude and the CO2 concentration after pressure compensation is provided in one embodiment of the spectral pressure broadening compensation method of the off-axis integrating cavity system of the present invention. DETAILED DESCRIPTION

[0050] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0051] by 13 For example, Graham first reported in Lancet that patients with Helicobacter pylori infection took oral 13After C urea, the CO2 in the exhaled gas has obvious 13 C enrichment characteristics [1] By detecting the 13 The change in C concentration can effectively determine the infection status of Helicobacter pylori. This discovery has promoted the research and development of breath diagnosis technology. Laser absorption spectroscopy technology has become an important means to achieve accurate breath diagnosis with its incomparable advantages such as high sensitivity, high selectivity and non-invasiveness. Among them, off-axis integrating cavity output spectroscopy technology (0A-ICOS) is a highly sensitive detection technology method designed specifically for trace gas detection. Since its light beam and the optical axis in the integrating cavity do not need to be strictly coaxial, OA-ICOS has the significant advantages of simple structure, stable system, high integration and non-invasiveness, and is very suitable for medical respiratory diagnosis applications that have extremely high requirements for weak signals (for example: Helicobacter pylori infection detection and oxidative metabolic status assessment).

[0052] For portable respiratory diagnostic measurement systems, their design and measurement methods are significantly different from those of conventional gas monitoring systems due to the following reasons: 1. Portability and miniaturization requirements: In order to meet portability, the instrument usually adopts a compact design with a small air chamber volume. 2. Limited exhaled gas volume: The sample volume of human exhaled gas is small, resulting in insufficient sampling. 3. Fast response requirements: Respiratory diagnosis requires measurement to be completed in a short time, requiring the instrument to respond quickly. Based on the above requirements, portable respiratory diagnostic instruments usually adopt a static air intake mode, which is different from the mode of "the air inlet and outlet are opened at the same time and a certain flow rate of gas is maintained through the air chamber" in dynamic monitoring. In the static air intake mode, the air outlet is closed before the start of exhalation, and the patient's exhaled air directly enters the air chamber. However, due to the small volume of the air chamber, the exhalation process will cause the pressure in the air chamber to increase. In the OA-ICOS system based on wavelength modulation spectroscopy (WMS) technology, the pressure change will cause the absorption spectrum to broaden, which will lead to a decrease in the amplitude of the second harmonic (2f) signal, seriously affecting the accuracy of data inversion.

[0053] Figure 1 This is a flow chart provided by an embodiment of the spectral pressure broadening compensation method of the off-axis integrating cavity system of the present invention. Figure 1 , this embodiment may include the following steps:

[0054] S1, obtain 2f harmonic signal;

[0055] S2, fitting the 2f harmonic signal by the second Fourier Lorentzian line function;

[0056] S3, calculating the best fitting parameters;

[0057] S4. Determine the pressure calibration coefficient according to the best fitting parameters;

[0058] S5. Determine an amplitude calibration equation of the 2f harmonic signal according to the pressure calibration coefficient, and perform spectral pressure broadening compensation on the 2f harmonic signal according to the amplitude calibration equation.

[0059] It can be understood that this embodiment achieves accurate calibration of the 2f amplitude by correcting the line broadening effect caused by increased pressure. The calibrated 2f amplitude can effectively eliminate the interference of the pressure broadening effect and accurately invert the content of the gas to be measured. By compensating for the broadened absorption line, the system error is significantly reduced and the overall performance of the respiratory diagnostic instrument is improved.

[0060] Preferably, step S2 comprises:

[0061] According to the Beer-Lambert law, the absorption coefficient of the 2f harmonic signal is determined;

[0062] Transform the absorption coefficient;

[0063] Determine the 2f Fourier coefficient of the 2f harmonic signal according to the absorption coefficient after transformation;

[0064] The 2f Fourier coefficients are transformed, and the 2f amplitude of the Lorentz linear function of the 2f harmonic signal is determined according to the transformed 2f Fourier coefficients.

[0065] It can be understood that the basic principle of wavelength modulation theory 2f is the Beer-Lambert law, which describes the relationship between the incident radiation and the transmitted radiation when a laser beam passes through a uniform gas medium. According to the Beer-Lambert law and weak gas absorption, the absorption coefficient α v Defined as:

[0066]

[0067] Δv c is the full width at half maximum (FWHM) of the Lorentzian lineshape, which gives:

[0068] Δv c =P[Xγ self +(1-X)γ air ] (2)

[0069] where α v is the absorption coefficient at frequency V; L is the path length; S is the line strength of the transition; v0 is the center frequency; γ self and γ air are the self-broadening coefficient and the air broadening coefficient, respectively. From the above formula, it can be seen that the fraction of the term in brackets is the peak normalized Lorentzian line shape function α0 is the absorption coefficient given by PXSL and is proportional to the concentration at constant pressure.

[0070] Multiply equation (1) by Δvc / 2, the new formula can be expressed as:

[0071]

[0072] According to equation (3), the amplitude absorption coefficient of the Lorentz linear function α'0 can be written as 2PXSL / πAv c In addition, for the theory of 2fWMS, the article by Pawel and Ove was adopted, so the signal The 2f Fourier coefficients can be written as:

[0073]

[0074] in, is the modulation depth (by 2v a / Δv c Given, v a is the modulation amplitude), is the width normalized center detuning (for the Lorentz case, given by 2(v-v0) / Δv c Given), η is the instrument factor, I D is the laser intensity detected in the absence of gas absorption, is the 2f signal of the Lorentzian line function. To obtain the 2f amplitude, we substitute α'0 into equation (4) and obtain the 2f amplitude function:

[0075]

[0076] Then, the 2f amplitude of the Lorentzian line function can be easily derived as:

[0077]

[0078] Preferably, step S3 includes:

[0079] Get the fitting result of 2f harmonic signal;

[0080] According to the fitting results, the fitting goodness of the 2f harmonic signal is determined;

[0081] When the goodness of fit is less than a preset threshold, the 2f harmonic signal is refitted;

[0082] When the goodness of fit is greater than or equal to a preset threshold, the parameters of the second Fourier Lorentz linear function are modified and fitted again until the best fitting parameters are determined.

[0083] Preferably, the pressure calibration factor is:

[0084]

[0085] Where Δv c is the full width at half maximum of the Lorentz lineshape, is the 2f amplitude of the Lorentz line function, is the modulation depth.

[0086] Preferably, the amplitude calibration equation is:

[0087]

[0088] Where k is the pressure calibration factor.

[0089] It can be understood that by combining equation (2) and equation (5), we can find the principle of the pressure broadening effect: increasing the pressure P can broaden the line width Δv c , affecting the modulation depth Thus, we need to establish a calibrated 2f amplitude function that is proportional to the line width Δv c and modulation depth It is not related to the gas concentration or particle number density. In this way, the pressure P will not affect the line width and modulation depth, so the 2f amplitude will not decrease. In order to establish this equation, line width compensation and modulation depth compensation are introduced: According to equation (5), multiply the equation by the line width Δv c and equation (6) The reciprocal of the 2f amplitude S 2f becomes an equation that satisfies the above conditions. Therefore, the pressure calibration coefficient (or line width compensation and modulation depth compensation coefficient) κ can be written as:

[0090]

[0091] The 2f amplitude calibration equation H is defined 2f , this equation is related to the 2f amplitude S 2f It is proportional to the pressure calibration coefficient κ. Finally, the peak value H of the second harmonic signal can be obtained. 2f function:

[0092]

[0093] In specific practice, Figure 4 As shown, Figure 4It is a schematic diagram of a wavelength modulated off-axis integrating cavity structure provided by an embodiment of the spectral pressure broadening compensation method of the off-axis integrating cavity system of the present invention, and the wavelength modulated off-axis integrating cavity structure includes a data acquisition card 1, a phase-locked amplifier 2, a function generator 3, an adder 4, a laser controller 5, a DFB laser 6, an optical resonant cavity 7, a front high-reflection mirror 8a, a rear high-reflection mirror 8b, an air inlet 9a, an air outlet 9b, a converging lens 10, and a photodetector 11. First, before exhaling gas into the instrument, close the air outlet 9b, open the air inlet 9a, and scan the wavelength of the DFB laser 4 through the data acquisition card 1, the phase-locked amplifier 2 and the function generator 3 through the adder 4 and the laser controller 5. The laser emitted by the laser 6 after being tuned by the triangular wave current passes through the front high-reflection mirror 8a and is off-axis coupled to the inside of the optical resonant cavity 7. The planar ends of the front and rear high-reflection mirrors 8a and 8b are coated with anti-reflection films, and the concave ends are coated with high-reflection films with a reflectivity of 99.9%. Therefore, only 0.1% of the incident light can enter the resonant cavity 5 for back and forth reflection. At the same time, a large number of weak light beams are transmitted through the high-reflection film of the rear high-reflection mirror 8b to form the required detection light, which is then received by the photodetector 11 after passing through the converging lens 10. The final spectrum data is analyzed and processed by the data acquisition card and the computer to obtain the absorption intensity and concentration results of the gas.

[0094] The 2f absorption signal generated by the lock-in amplifier is obtained by using the second Fourier Lorentzian line shape function, and the fitted 2f absorption information can be calculated, where A n , B n , C n , D n yes and In addition, when the best fitting parameters between the measured absorbance signal and the fitted absorbance signal are obtained, the fitted Δv can be derived. c and v a Then according to equation (6), we can calculate Finally, according to equation (7), the pressure calibration coefficient κ can be calculated.

[0095] Preferably, it also includes:

[0096] According to the state equation of the gas, determine the relationship equation between the pressure and CO2 concentration X in the sealed environment;

[0097] According to the relational equation, the amplitude calibration equation is transformed;

[0098] Based on the transformation processing results, the amplitude calibration equation is evaluated.

[0099] It can be understood that the optical resonant cavity pressure P and the density of the number of particles N satisfy the state equation of the gas:

[0100]

[0101] Where N A [mol -1 ] is Avogadro's constant, V is the gas volume, n is the amount of substance in gas, R [J / (mol·K)] is the gas constant, and T [K] is the thermodynamic temperature.

[0102] Assume that the air number density in the sealed environment culture bottle is N0, the initial pressure P0 is normal pressure (1atm), and at a certain time t (t>0), the particle number density of CO2 is N t , the pressure of the sealing environment is P t [atm]. According to the above equation, the pressure Pt at time t can be obtained:

[0103]

[0104] N t +N0 is the total particle number density in the sealed environment at time t. Therefore, the CO2 concentration X[%] at time t can be obtained:

[0105]

[0106] At this point, the relationship equation between the pressure and CO2 concentration X in the sealed environment can be given:

[0107]

[0108] 2f Amplitude Calibration Equation H 2f It is linearly related to the particle number density of CO2, as described in equation (8). Combining equation (11) and equation (12), equation H 2f It has a monotonically increasing relationship with CO2 concentration, as described in equation (13):

[0109]

[0110] where G is a proportionality factor including a constant parameter.

[0111]

[0112] In specific practice, in order to verify the effectiveness of the pressure calibration method, taking CO2 gas as an example, the absorption line at 4991.25cm-1 was selected from the HITRAN2016 database, and its intensity at 296K is 1.26×10-21cm / molecule. The optical path is 3cm and the initial pressure is 1atm. As the CO2 concentration increases from 0 to 50%, the pressure also increases from 1atm to 2atm (8 groups, each group increases by 0.125atm). Figure 5Shows 0.08cm under different pressures -1 Conventional 2f signal with modulation amplitude. It can be seen that with the increase of CO2 concentration and pressure, the 2f signal increases until reaching 33% CO2 concentration condition (1.5atm pressure condition), after which the 2f signal decreases due to the pressure broadening effect.

[0113] like Figure 6 As shown, Figure 6 The relationship between the 2f amplitude and CO2 concentration before pressure compensation is described. Other different modulation amplitudes (including low modulation amplitude 0.04cm-1 and large modulation amplitude 0.16cm-1) are plotted in the figure. It can be seen from the simulation experiment that there is a nonlinear and non-monotonic curve between the traditional 2f amplitude and the CO2 concentration. The 2f amplitude before pressure compensation is proportional to CO2 in the 0-20% concentration range (1-1.25atm pressure range), and the pressure broadening effect becomes the main factor affecting the 2f amplitude in the 20-50% concentration range (1.25-2atm pressure range). In addition, although increasing the modulation amplitude can increase the traditional 2f amplitude and optimize the monotonicity of the curve, it cannot change the non-monotonic characteristics of the curve.

[0114] like Figure 7 As shown, Figure 7 The relationship between the calibrated 2f amplitude and the CO2 concentration according to equation (10) is depicted. Compared with the 2f amplitude before pressure compensation, there is a monotonic curve between the 2f amplitude and the CO2 concentration after compensation calibration. At the same time, these curves are not only unaffected by the pressure broadening effect, but also independent of the modulation amplitude, so similar concentration results can be obtained using the calibrated 2f amplitude. Through these simulation experiments, we can find that the calibrated 2f amplitude can realize CO2 concentration detection in a sealed environment with increased pressure and effectively eliminate the influence of the pressure broadening effect. In addition, according to equation (9), the linear relationship between the calibrated 2f amplitude and the CO2 particle number density is as follows Figure 5 As shown in Figure 2, the use of the calibrated 2f amplitude can better restore the situation with the same pressure conditions. Therefore, this pressure calibration method provides theoretical support for the application of WMS technology 2f signal in static intake breathing diagnostic measurement.

[0115] Specifically, a new pressure calibration method was introduced to calibrate the 2f amplitude attenuation caused by the pressure broadening effect during respiratory diagnosis. The new method combines linewidth compensation and modulation depth compensation, so that the 2f amplitude can accurately invert the CO2 concentration in a static intake mode environment without being affected by the pressure broadening effect. A simulation experiment was carried out in which an increase in CO2 concentration led to an increase in pressure. Compared with the 2f amplitude before compensation, the simulation results of the calibrated 2f amplitude showed a monotonic relationship with the CO2 concentration, especially when the CO2 particle number density was used instead of the CO2 concentration, a linear relationship was shown. It is proved that this model performs well in pressure compensation and application practicality.

[0116] The present invention also provides a spectral pressure broadening compensation device for an off-axis integrating cavity system, which is used to implement the above method embodiment. Figure 2 FIG. 1 is a schematic diagram of a structure of an embodiment of a spectral pressure broadening compensation device for an off-axis integrating cavity system of the present invention. Figure 2 As shown, this embodiment includes:

[0117] A data acquisition module 101 is used to acquire a 2f harmonic signal;

[0118] A fitting module 102 is used to fit the 2f harmonic signal through the second Fourier Lorentz linear function and calculate the best fitting parameters;

[0119] The pressure broadening compensation module 103 is used to determine the pressure calibration coefficient according to the best fitting parameters, determine the amplitude calibration equation of the 2f harmonic signal according to the pressure calibration coefficient, and perform spectral pressure broadening compensation on the 2f harmonic signal according to the amplitude calibration equation.

[0120] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0121] The present invention also provides a spectral pressure broadening compensation device for an off-axis integrating cavity system, which is used to implement the above method embodiment. Figure 3 FIG. 1 is a schematic diagram of a structure of an embodiment of a spectral pressure broadening compensation device for an off-axis integrating cavity system of the present invention. Figure 3 As shown, the spectral pressure broadening compensation device of the off-axis integrating cavity system of this embodiment includes a processor 21 and a memory 22, and the processor 21 is connected to the memory 22. The processor 21 is used to call and execute the program stored in the memory 22; the memory 22 is used to store the program, and the program is at least used to execute the spectral pressure broadening compensation method of the off-axis integrating cavity system in the above embodiment.

[0122] The specific implementation scheme of the spectral pressure broadening compensation device for the off-axis integrating cavity system provided in the embodiment of the present application can refer to the implementation scheme of the spectral pressure broadening compensation method for the off-axis integrating cavity system in any of the above embodiments, which will not be repeated here.

[0123] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0124] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0125] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0126] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0127] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0128] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0129] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0130] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0131] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for compensating spectral pressure broadening of an off-axis integrating cavity system, characterized in that: include: Get 2f harmonic signal; Fitting the 2f harmonic signal by a second Fourier Lorentzian linear function; Calculate best-fit parameters; Determining a pressure calibration coefficient according to the best fitting parameters; An amplitude calibration equation of the 2f harmonic signal is determined according to the pressure calibration coefficient, and spectral pressure broadening compensation is performed on the 2f harmonic signal according to the amplitude calibration equation.

2. The method according to claim 1, characterized in that The step of fitting the 2f harmonic signal by using a second Fourier Lorentz linear function comprises: According to the Beer-Lambert law, determining the absorption coefficient of the 2f harmonic signal; Performing transformation processing on the absorption coefficient; Determining the 2f Fourier coefficient of the 2f harmonic signal according to the absorption coefficient after transformation; The 2f Fourier coefficients are transformed, and the 2f amplitude of the Lorentz linear function of the 2f harmonic signal is determined according to the transformed 2f Fourier coefficients.

3. The method according to claim 2, characterized in that The calculating of the best fitting parameters comprises: Obtaining a fitting result of the 2f harmonic signal; Determining the goodness of fit of the 2f harmonic signal according to the fitting result; When the goodness of fit is less than a preset threshold, refitting the 2f harmonic signal; When the goodness of fit is greater than or equal to a preset threshold, the parameters of the second Fourier Lorentz linear function are modified and fitted again until the best fitting parameters are determined.

4. The method according to claim 3, characterized in that Also includes: According to the state equation of the gas, determine the relationship equation between the pressure and CO2 concentration X in the sealed environment; According to the relationship equation, transform the amplitude calibration equation; Based on the transformation processing results, the amplitude calibration equation is evaluated.

5. The method according to claim 4, characterized in that The pressure calibration factor is: Where Δv c is the full width at half maximum of the Lorentz lineshape, is the 2f amplitude of the Lorentz line function, is the modulation depth.

6. The method according to claim 5, characterized in that The amplitude calibration equation is: Where k is the pressure calibration factor.

7. A spectral pressure broadening compensation device for an off-axis integrating cavity system, characterized in that: include: A data acquisition module, used for acquiring a 2f harmonic signal; A fitting module, used for fitting the 2f harmonic signal through a second Fourier Lorentz linear function to calculate the best fitting parameters; The pressure broadening compensation module is used to determine the pressure calibration coefficient according to the best fitting parameters, determine the amplitude calibration equation of the 2f harmonic signal according to the pressure calibration coefficient, and perform spectral pressure broadening compensation on the 2f harmonic signal according to the amplitude calibration equation.

8. A spectral pressure broadening compensation device for an off-axis integrating cavity system, characterized in that: The invention comprises a processor and a memory, wherein the processor is connected to the memory: Wherein, the processor is used to call and execute the program stored in the memory; The memory is used to store the program, and the program is at least used to execute the spectral pressure broadening compensation method for the off-axis integrating cavity system according to any one of claims 1-6.

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