Analyzing apparatus, recording medium, and analyzing method

Abstract

The present application provides an analysis device, a recording medium and an analysis method. The analysis device (100) corrects the change in the light absorption spectrum of a measurement target component due to the coexisting component or the wavelength shift of the reference light, measures the concentration of the measurement target component with high accuracy, analyzes the measurement target component contained in a sample, and includes a light source (2) that emits reference light to the sample, a light detector (3) that detects the intensity of sample light after the reference light has passed through the sample, a parameter determination unit (64, 66) that determines a parameter indicating the change in the light absorption spectrum of the measurement target component or the interfering component due to the coexisting component contained in the sample or the wavelength shift of the reference light, and a concentration calculation unit (65) that calculates the concentration of the measurement target component after correction using the parameter indicating the change in the light absorption spectrum based on an intensity correlation signal associated with the intensity of the sample light.

Description

TECHNICAL FIELD

[0001] The present application relates to an analysis device or the like, for example, for component analysis of a gas or the like. BACKGROUND

[0002] In the past, as shown in Patent Literature 1, there is an analysis method (TDLAS: Tunable Diode Laser Absorption Spectroscopy) in which an injection current of a semiconductor laser is modulated, an oscillation wavelength is scanned, and an absorption spectrum of a measurement target gas is obtained, whereby a concentration is quantitatively analyzed.

[0003] PRIOR ART DOCUMENTS

[0004] Patent Literature 1: Japanese Patent Publication No. 2016-90521 SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, in the absorption spectroscopy method using a laser such as TDLAS, not only is the measurement target component affected by an interfering component having an optical absorption spectrum overlapping with the optical absorption spectrum of the measurement target component (interference effect), but also the concentration of a coexisting component coexisting at a high concentration (several % to several tens % or so) is affected, and the shape is changed (coexistence effect). Specifically, the width of the optical absorption spectrum is broadened, and the absorption peak is lowered (broadening). As a result, a measurement error occurs in the concentration of the measurement target component. In addition, in a case where the measurement target component itself is at a high concentration, the measurement target component itself becomes a coexisting component, and the coexistence effect occurs due to a change in the concentration of the measurement target component itself (self-broadening). That is, the coexisting component is a component that causes broadening effect on itself or other components. In addition, in the absorption spectroscopy method using a laser such as TDLAS, a wavelength of light emitted from the laser shifts due to a change in ambient temperature or the like, and a measurement error occurs in the concentration of the measurement target component. That is, in either case, the optical absorption spectrum of the measurement target component changes, and a measurement error occurs in the concentration of the measurement target component.

[0007] The present application has been made in view of the above-described problems, and a main object of the present application is to correct a change in the optical absorption spectrum due to a coexistence effect caused by a coexisting component or a wavelength shift, and to measure the concentration of a measurement target component with high accuracy in an analysis device using optical absorption.

[0008] An optical absorption spectrum known to be broadened due to the effect of a coexisting component is, for example, Figure 10As shown in (A) of FIG. 1, according to the concentration of the coexisting component, the spectral width becomes wide and the height of the absorption peak becomes low, but the entire area thereof hardly changes. On the other hand, as shown in (B) of FIG. 1, in the case of pressure fluctuation, the width of the light absorption spectrum becomes wide, but the height of the absorption peak hardly changes. Figure 10

[0009] Therefore, the present inventors focused on the difference and similarity of the changes in the light absorption spectrum due to the coexistence influence and the pressure fluctuation, and found that: a broadening factor F B which indicates the rate of change in the light absorption spectrum of the measurement target component due to the coexisting component contained in the sample is newly introduced B The absorbance signal A'(t, P) at the time of broadening due to the coexistence influence is approximately expressed by the following equation.

[0010] [Equation 1]

[0011]

[0012] That is, the spectral change due to the coexistence influence is basically the same as the spectral change in which the pressure becomes F B times and the absorbance becomes 1 / F B times. The basic concept of the present application is to convert the broadening due to the coexistence influence into the pressure change using this point, and to perform the coexistence influence correction at the same time as the pressure correction.

[0013] In addition, since the shift in the wavelength of the light source due to the change in the ambient temperature or the like also causes a change in the light absorption spectrum, it is necessary to detect this change and perform correction.

[0014] Technical solution for solving the technical problem

[0015] That is, the analysis device of the present application is characterized in that the analysis device analyzes a measurement target component contained in a sample, and the analysis device includes: a light source that irradiates a reference light to the sample; a light detector that detects the intensity of a sample light after the reference light transmits through the sample; a parameter determination section that determines a parameter indicating a change in the light absorption spectrum of the measurement target component or an interference component due to a coexisting component contained in the sample or a shift in the wavelength of the reference light; and a concentration calculation section that calculates the concentration of the measurement target component after correction using the parameter indicating the change in the light absorption spectrum, based on an intensity correlation signal correlated with the intensity of the sample light.

[0016] ​If such a configuration is adopted, since the concentration of the measurement target component after correction of the coexistence influence due to the coexisting component or the wavelength shift of the reference light is calculated using a parameter indicating a change in the optical absorption spectrum of the measurement target component or the interfering component due to the coexisting component or the wavelength shift of the reference light, the change in the optical absorption spectrum due to the coexistence influence or the wavelength shift can be corrected, and the concentration of the measurement target component can be measured with high accuracy.

[0017] As the parameter indicating the change in the optical absorption spectrum, a broadening factor indicating a rate of change in the optical absorption spectrum of the measurement target component or the interfering component due to the coexisting component included in the sample, or a wavelength shift amount of the reference light can be cited.

[0018] Thereby, the concentration calculating section calculates the concentration of the measurement target component after correction of the coexistence influence due to the coexisting component or the wavelength shift of the reference light using the intensity correlation signal correlated with the intensity of the sample light, and the broadening factor or the wavelength shift amount.

[0019] It can be considered that the parameter determining section determines the broadening factor by fitting reference data correlated with the optical absorption signals of the measurement target component and the interfering component for which the broadening factor or the pressure is known, and sample data correlated with the optical absorption signals calculated from the intensity of the sample light. Here, fitting means comparing and collating the reference data with the sample data. In addition, in the comparison and collation, the reference data is transformed using the pressure value of the sample and the relationship of the above-described equation (mathematical equation 1) and is used. As a specific method of comparison and collation, for example, a non-linear least square method accompanied by repeated calculation using a steepest descent method, a Gauss-Newton method, a Levenberg-Marquardt method, or the like can be cited.

[0020] In addition, it can be considered that the parameter determining section determines the broadening factor using relationship data indicating the relationship between the concentration of the coexisting component and the broadening factor, and the concentration of the coexisting component measured.

[0021] It can be considered that the parameter determining section determines the wavelength shift amount by fitting reference data correlated with the optical absorption signals of the measurement target component and the interfering component for which the wavelength shift amount is known, and sample data correlated with the optical absorption signals calculated from the intensity of the sample light.

[0022] In addition, it can be considered that the parameter determining section determines the wavelength shift amount of the reference light using relationship data indicating the relationship between the ambient temperature and the wavelength shift amount, and the ambient temperature measured.

[0023] Preferably, the analysis device further includes a correlation value calculation section that calculates a correlation value of an intensity correlation signal associated with the intensity of the sample light and a prescribed characteristic signal, and the concentration calculation section calculates the concentration of the measurement target component after correction of coexisting influence by the coexisting component or wavelength shift of the reference light, using the correlation value and a parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component.

[0024] If this configuration, a correlation value of an intensity correlation signal associated with the intensity of the sample light and a characteristic signal is calculated, and the concentration of the measurement target component is calculated using the calculated correlation value, so that the characteristics of the absorption signal can be dramatically captured with fewer variables without transforming the absorption signal into an absorption spectrum, and the concentration of the measurement target component can be measured with simple calculation without complex spectral calculation processing. For example, several hundred data are used in general spectral fitting, but in the present application, the concentration can be calculated with equal accuracy using several to several tens of correlation values at most. As a result, the load of the calculation processing can be dramatically reduced, a high-level calculation processing device is not required, the cost of the analysis device can be reduced, and the analysis device can be downsized.

[0025] Preferably, the analysis device of the present application analyzes a measurement target component in a sample containing one or more interference components from which interference influence should be removed, the correlation value calculation section calculates a plurality of correlation values using a number of characteristic signals equal to or more than the number obtained by adding the number of types of the measurement target component to the number of types of the interference components, and the concentration calculation section calculates the concentration of the measurement target component using the plurality of correlation values and a parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component.

[0026] Preferably, the analysis device of the present application further includes a storage section that stores individual correlation values that are correlation values of each of the measurement target component and each of the interference components per unit concentration, which are calculated from the respective intensity correlation signals and a plurality of characteristic signals of each of the measurement target component and each of the interference components when each of the measurement target component and each of the interference components exists alone, and the concentration calculation section calculates the concentration of the measurement target component using the plurality of correlation values obtained by the correlation value calculation section, the plurality of individual correlation values, and a parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component.

[0027] Specifically, preferably, the concentration calculation section corrects the plurality of individual correlation values using the parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component, and calculates the concentration of the measurement target component using the corrected plurality of individual correlation values and the plurality of correlation values obtained by the correlation value calculation section.

[0028] If this is the composition, then by solving a series of equations involving a maximum of several to dozens of elements, the concentration of the measured component can be determined, eliminating the effects of interference, coexistence effects caused by coexisting components, or wavelength shifts of the reference light.

[0029] More specifically, preferably, the concentration calculation unit calculates the concentration of the measured component by solving a simultaneous equation consisting of multiple correlation values ​​obtained by the correlation value calculation unit, the multiple corrected individual correlation values, and the concentrations of the measured component and each interfering component.

[0030] Here, in order to correct the individual correlation values, it is preferable to store the individual correlation values ​​of each component in advance in the storage unit under multiple known pressures or wavelength shifts of the reference light. By doing so, the individual correlation values ​​can be corrected using the broadening factor or wavelength shift determined by the parameter determination unit. Alternatively, the individual correlation values ​​stored in advance in the storage unit could be obtained under known pressures but with known broadening factors instead of known pressures. However, it is not easy to create a state with known broadening factors, so it is preferable to use the individual correlation values ​​obtained under known pressures.

[0031] Furthermore, when the pressure of the sample varies during measurement, it is preferable to monitor the pressure of the sample using a pressure sensor or similar means, and also use this pressure value to correct for the individual correlation value. By doing so, it is possible to simultaneously correct for the coexistence effects caused by coexisting components and the effects caused by pressure variations.

[0032] At this point, it can be considered that the concentration calculation unit uses the individual correlation values ​​of each component obtained according to the multiple known pressures of the sample, the multiple correlation values ​​obtained by the correlation value calculation unit, the pressure value in the pool, and the relationship of the following formula (Mathematical Formula 2) to correct the individual correlation values.

[0033] [Mathematical Expression 2]

[0034]

[0035] Here, p is the pressure of the sample measured by the pressure sensor, F B The broadening factor, s, is determined by the broadening factor determination unit. ij These are the individual correlation values ​​stored in the storage unit under each pressure, s′ ij This is the corrected individual correlation value. Furthermore, the above formula (Mathematical Formula 2) represents the individual correlation value s under the pressure p of the sample during measurement. ij (p) will multiply the pressure by F BThe individual correlation value obtained after the multiplication by the factor of 1 / F B The individual correlation value s' is obtained by multiplying the individual correlation value s by the factor of 1 / F ij .

[0036] In addition, in a case where the interference component is also affected by the broadening due to the coexisting component, the broadening factor of the interference component can be determined separately, and the individual correlation value of the interference component can be corrected. Thereby, the measurement accuracy can be further improved.

[0037] The recording medium of the present application records a program for an analysis device, characterized in that the program is applied to an analysis device that has a light source that irradiates a reference light to a sample, and a light detector that detects a sample light that has passed through the sample, and that functions as a parameter determination section that determines a parameter that represents a change in an optical absorption spectrum of a measurement target component or an interference component that is caused by a coexisting component included in the sample or a wavelength shift of the reference light, and a concentration calculation section that calculates a concentration of the measurement target component that is corrected using the parameter that represents the change in the optical absorption spectrum, based on an intensity correlation signal that is correlated with an intensity of the sample light.

[0038] Further, the analysis method of the present application is characterized in that the analysis method uses a light source that irradiates a reference light to a sample, and a light detector that detects a sample light that has passed through the sample, to analyze a measurement target component included in the sample, determines a parameter that represents a change in an optical absorption spectrum of the measurement target component or an interference component that is caused by a coexisting component included in the sample or a wavelength shift of the reference light, and calculates a concentration of the measurement target component that is corrected using the parameter that represents the change in the optical absorption spectrum, based on an intensity correlation signal that is correlated with an intensity of the sample light.

[0039] Effects of the Invention

[0040] According to the present application described above, in an analysis device that utilizes light absorption, a change in an optical absorption spectrum that is caused by a coexisting influence due to a coexisting component or a wavelength shift of a reference light can be corrected, and a concentration of a measurement target component can be measured with high accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a whole schematic view of an analysis device of the first embodiment of the present application.

[0042] Figure 2 is a functional block diagram of a signal processing device of the embodiment.

[0043] Figure 3is a schematic diagram showing a modulation method of a laser oscillation wavelength according to the embodiment.

[0044] Figure 4 is a time series chart showing one example of an oscillation wavelength, light intensity I(t), logarithmic intensity L(t), characteristic signal F i (t), and correlation value S i (t) according to the embodiment.

[0045] Figure 5 is a conceptual diagram showing concentration calculation using individual correlation values and measured correlation values according to the embodiment.

[0046] Figure 6 is a whole schematic diagram of an analysis device according to the second embodiment of the present application.

[0047] Figure 7 is a functional block diagram of a signal processing device according to the second embodiment of the present application.

[0048] Figure 8 is a diagram showing a drive current (voltage) and a modulation signal of quasi-continuous oscillation.

[0049] Figure 9 is a schematic diagram showing a measurement principle using quasi-continuous oscillation.

[0050] Figure 10 is a schematic diagram showing a spectrum change due to coexistence influence and a spectrum change due to pressure change.

[0051] Explanation of Reference Numerals

[0052] 100 · · · analysis device

[0053] 1 · · · cell

[0054] 2 · · · light source (semiconductor laser)

[0055] 3 · · · light detector

[0056] 4 · · · signal processing device

[0057] 61 · · · logarithmic calculation section

[0058] 62 · · · correlation value calculation section

[0059] 63 · · · storage section

[0060] 64 · · · spread factor determination section

[0061] 65 · · · concentration calculation section

[0062] 66 · · · wavelength shift determination section

[0063] 7 pressure sensor DETAILED DESCRIPTION

[0064] <First Embodiment (Coexistence Influence Correction Function)>

[0065] The analysis device 100 of the present embodiment is a concentration measuring device that measures the concentration of a measurement target component (here, for example, CO, CO2, etc.) contained in a sample gas such as exhaust gas, and is configured as shown in FIG. 1. Figure 1 As shown in FIG. 1, the analysis device 100 is provided with: a cell 1 into which a sample gas is introduced; a semiconductor laser 2 that is a light source that irradiates the cell 1 with modulated laser light; a photodetector 3 that is disposed on the optical path of sample light that is laser light that has passed through the cell 1 and that receives the sample light; a signal processing device 4 that receives the output signal of the photodetector 3 and calculates the concentration of the measurement target component based on the value thereof; and a pressure sensor 7 that monitors the pressure inside the cell 1.

[0066] In addition, the analysis device 100 of the present embodiment is connected to an introduction flow path for introducing a sample gas into the analysis device 100, and is connected to an exhaust flow path that exhausts a gas that has been analyzed by the analysis device 100. Furthermore, a pump for introducing a sample gas into the analysis device 100 is provided on the introduction flow path or the exhaust flow path. In addition, the introduction flow path can be configured to directly sample exhaust gas from an exhaust pipe or the like, can be configured to introduce exhaust gas from a bag that has captured the exhaust gas, or can be configured to introduce exhaust gas that has been diluted by a dilution device such as a CVS (Constant Volume Sampler) or the like.

[0067] The components will be described.

[0068] The cell 1 is formed of a transparent material such as quartz, calcium fluoride, barium fluoride, or the like that has little light absorption in the absorption wavelength range of the measurement target component, and is formed of a light entrance port and a light exit port. Although not shown in the drawing, an inlet for introducing a gas into the interior and an outlet for exhausting the gas from the interior are provided in the cell 1, and a sample gas is introduced from the inlet and is housed in the cell 1.

[0069] The semiconductor laser 2 is a quantum cascade laser (QCL) that is one type of semiconductor laser 2, and oscillates laser light in the mid-infrared (4 to 12 μm) range. The semiconductor laser 2 is able to modulate (change) the oscillation wavelength in accordance with the current (or voltage) that is applied. In addition, as long as the oscillation wavelength is variable, other types of lasers can also be used, and the temperature can be changed or the like in order to change the oscillation wavelength.

[0070] The light detector 3 uses a thermal type such as a thermoelectric element in this embodiment, but other types can be used, for example, a quantum type photoelectric element such as HgCdTe, InGaAs, InAsSb, PbSe, etc. can be used.

[0071] The signal processing device 4 has an analog circuit composed of a buffer, an amplifier, etc., a digital circuit composed of a CPU, a memory, etc., and an AD converter, a DA converter, etc. that mediates between these analog / digital circuits, and cooperates with the CPU and its peripherals according to a prescribed program stored in a prescribed area of the memory, whereby it functions as the light source control section 5 and the signal processing section 6 as shown in the figure, the light source control section 5 controls the output of the semiconductor laser 2, and the signal processing section 6 receives the output signal from the light detector 3 and performs calculation processing on the value, calculating the concentration of the measurement target component. Figure 2

[0072] The pressure sensor 7 monitors the pressure of the sample, and in this embodiment, the absolute pressure in the cell 1, and in this embodiment, a silicon piezoresistive absolute pressure sensor is used. Also, although not shown, a pump and a pressure regulator are used to adjust the pressure in the cell during measurement to be about 20 to 30 kPa.

[0073] The following describes each part in detail.

[0074] The light source control section 5 controls the current source (or voltage source) of the semiconductor laser 2 by outputting a current (or voltage) control signal. Specifically, the light source control section 5 causes the drive current (or drive voltage) of the semiconductor laser 2 to vary at a prescribed frequency, and modulates the oscillation wavelength of the laser light output from the semiconductor laser 2 at a prescribed frequency with respect to the center wavelength. As a result, the semiconductor laser 2 emits modulated light modulated with a prescribed modulation frequency.

[0075] In this embodiment, the light source control section 5 causes the drive current to vary into a triangular waveform, and modulates the oscillation frequency into a triangular waveform (see "oscillation wavelength" in Figure 4 . In practice, the modulation of the drive current is performed with another function so that the oscillation frequency becomes a triangular waveform. Also, as shown in Figure 3 , the oscillation wavelength of the laser light is modulated with the peak of the light absorption spectrum of the measurement target component as the center wavelength. Furthermore, the light source control section 5 can cause the drive current to vary into a sinusoidal waveform, a sawtooth waveform, or an arbitrary function shape, and modulate the oscillation frequency into a sinusoidal waveform, a sawtooth waveform, or an arbitrary function shape.

[0076] The signal processing section 6 is composed of a logarithmic calculation section 61, a correlation value calculation section 62, a storage section 63, a broadening factor determination section 64 as a parameter determination section, and a concentration calculation section 65, etc. ​

[0077] The logarithmic calculation unit 61 performs logarithmic calculations on the light intensity signal, which is the output signal of the photodetector 3. The function I(t) representing the time-varying change of the light intensity signal obtained by the photodetector 3 becomes as follows: Figure 4 As shown in the figure for “light intensity I(t)”, by performing logarithmic calculation, it becomes as follows: Figure 4 The “logarithmic intensity L(t)” is shown.

[0078] The correlation value calculation unit 62 calculates the correlation values ​​between the intensity correlation signal, which is correlated with the intensity of the sample light, and a plurality of prescribed characteristic signals. The characteristic signals are signals whose waveform characteristics are extracted by obtaining correlation with the intensity correlation signals. For example, a sine wave signal, or other signals consistent with the waveform characteristics to be extracted from the intensity correlation signals, can be used as characteristic signals.

[0079] The following describes an example of using a signal other than a sinusoidal signal as a characteristic signal. The correlation value calculation unit 62 calculates the intensity correlation signal correlated with the intensity of the sample light, and the correlation values ​​of various characteristic signals for which a different correlation than the sinusoidal signal (sine function) can be obtained. Here, the correlation value calculation unit 62 uses the logarithmically calculated light intensity signal (logarithmic intensity L(t)) as the intensity correlation signal.

[0080] In addition, the correlation value calculation unit 62 uses a feature signal F that is more than the number obtained by adding the number of types of the measured target component to the number of types of interfering components whose interference effects should be removed. i (t)(i=1,2,···,n), using the following formula (Mathematical Formula 3), calculate the multiple sample correlation values ​​S, which are the intensity correlation signals of the sample light and the correlation values ​​of multiple characteristic signals. i Additionally, T in the following formula (Mathematical Formula 3) is the modulation period.

[0081] [Mathematical Expression 3]

[0082]

[0083]

[0084] S′ i =S i -R i

[0085] Preferably, when calculating the correlation value of the sample, the correlation value calculation unit 62 calculates the correlation value of the sample light intensity correlation signal L(t) and multiple characteristic signals F as shown in formula (mathematical formula 3). i The correlation value S of (t) i Subtract the intensity-correlated signal L0(t) and multiple characteristic signals F used as the reference lighti a reference correlation value R of the correlation value of (t) i a corrected sample correlation value S' of (t) i . Thus, it is possible to remove the bias included in the sample correlation value, to become a correlation value proportional to the concentration of the measurement target component and the interfering component, and to reduce the measurement error. In addition, it can also be a configuration that does not subtract the reference correlation value.

[0086] Here, the timing of acquiring the reference light is simultaneously with the sample light, before and after measurement, or an arbitrary timing. The intensity correlation signal of the reference light or the reference correlation value can be acquired in advance and stored in the storage section 63. In addition, for the method of simultaneously acquiring the reference light, it is possible to consider, for example, providing two light detectors 3, branching the modulated light from the semiconductor laser 2 by a beam splitter or the like, and using one for sample light measurement and the other for reference light measurement.

[0087] In the present embodiment, the correlation value calculation section 62 uses a function that is easier to capture the waveform characteristics of the logarithmic intensity L(t) than the sine function, as the plurality of characteristic signals F i In the sample gas including the measurement target component and one interfering component, in the case where it is desired to further correct the coexistence influence of the coexisting component of the measurement target component, it is possible to consider using three characteristic signals F1(t), F2(t), F3(t), as the three characteristic signals, for example, it is possible to consider using a function based on the Lorentz function whose shape is close to the sum of the absorption spectra, and a partial differential function of the function based on the Lorentz function with respect to the Lorentz width, as shown in the following equation (Math. 4). In addition, w in the equation (Math. 4) is the Lorentz width, s is the shift of the absorption peak from the reference time position due to the wavelength shift, A is an arbitrary constant, A1, A2, A3 are biases adjusted in such a way that they become zero when integrating F1(t), F2(t), F3(t) with the modulation period, respectively. If such a function is used as a characteristic signal, it is possible to capture the spectral change due to the coexistence influence with higher sensitivity, and to perform the coexistence influence correction with higher accuracy. In addition, as the characteristic signal, instead of the function based on the Lorentz function, it is also possible to use a function based on the Voigt function or a function based on the Gaussian function, or the like. By using such a function as a characteristic signal, it is possible to obtain a larger correlation value than when using the sine function, and to improve the measurement accuracy.

[0088] [Equation 4]

[0089]

[0090]

[0091]

[0092] Here, it is preferable to remove the direct current component from the characteristic signal, that is, to adjust the bias in such a manner that it becomes zero when integrated with the modulation period. By doing so, it is possible to remove the influence of the bias attached to the intensity correlation signal due to the variation in light intensity. In addition, instead of removing the direct current component from the characteristic signal, it is also possible to remove the direct current component from the intensity correlation signal, and it is also possible to remove the direct current components of both the characteristic signal and the intensity correlation signal. Furthermore, as the characteristic signal, it is also possible to use the measured values of the absorption signals of the measurement target component and / or the interference components, respectively, or to use respective signals that imitate them.

[0093] In addition, by making the three characteristic signals F1(t), F2(t), F3(t) an orthogonal function series or a function series close to an orthogonal function series with respect to each other, it is possible to more effectively extract the characteristics of the logarithmic intensity L(t), and it is possible to make the concentration obtained by the simultaneous equations described later high in precision.

[0094] The storage section 63 stores individual correlation values that are correlation values per unit concentration of the measurement target component and each of the interference components, respectively, which are calculated from the respective intensity correlation signals and the plurality of characteristic signals F i (t) when the measurement target component and each of the interference components exist individually under the known pressure in the cell. The plurality of characteristic signals F i (t) used in the correlation value calculation section 62 are the same as the plurality of characteristic signals F i (t) used in the correlation value calculation section 62. In this way, the individual correlation values according to various pressures in the cell are stored in the storage section 63.

[0095] Here, it is preferable that the storage section 63, when storing the individual correlation values, store the individual correlation values corrected to per unit concentration after subtracting the reference correlation value from the correlation values when the measurement target component and each of the interference components exist individually. By doing so, it is possible to remove the bias included in the individual correlation values, it is possible to make the correlation values proportional to the concentrations of the measurement target component and the interference components, and it is possible to reduce the measurement error. In addition, it is also possible to be a configuration in which the reference correlation value is not subtracted.

[0096] The broadening factor 64 determines a broadening factor F B that represents the rate of change in the optical absorption spectrum of the measurement target component and the interference component due to the coexisting component included in the sample. In addition, in a case where the coexisting influence due to the coexisting component with respect to the interference component should also be considered, the broadening factor F B is additionally determined for each of the components.

[0097] As the determination method of the broadening factor F B , for example, the steps of (a) or (b) below can be considered.

[0098] (a) beforehand acquire each characteristic signal F k (k = 1, 2, ···, I) of the measurement target component and the interference component under each pressure p i (t) each individual correlation value s itar (p k ) corresponding to each pressure p iint (p k ) in the cell, and compare the sample correlation value obtained at the time of measurement with the individual correlation value, to determine the broadening factor F B . In addition, at the time of comparison, the individual correlation value is transformed using the relationship of the above-described equation (mathematical expression 2) using the pressure value in the cell, and is used. In the case of this method, the number of characteristic signals required becomes the number obtained by adding the number of types of the measurement target component, the number of types of the interference component, and the number of types of the broadening factor.

[0099] (b) using relationship data indicating the relationship of the concentration of the coexisting component and the broadening factor F B , and the concentration of the coexisting component measured, determine the broadening factor F B .

[0100] At this time, the broadening factor F B is previously found for each concentration of the coexisting component by experiment or by calculation, and the relationship data is generated. The concentration of the coexisting component measured can be measured by the analysis device 100 of the present embodiment before the coexistence influence correction, or can be obtained by measuring the concentration of the coexisting component using another analysis device.

[0101] The concentration calculating section 65 calculates the concentration of the measurement target component using the plurality of sample correlation values obtained by the correlation value calculating section 62.

[0102] Specifically, the concentration calculating section 65 calculates the concentration of the measurement target component from the plurality of sample correlation values obtained by the correlation value calculating section 62, the broadening factor F B determined by the broadening factor determining section 64, and the plurality of individual correlation values stored in the storage section 63. More specifically, the concentration calculating section 65 corrects the plurality of individual correlation values stored in the storage section 63 according to the broadening factor F B obtained by the broadening factor determining section 64, and acquires. Furthermore, the concentration calculating section 65 calculates the concentration of the measurement target component by solving a simultaneous equation constituted by the plurality of sample correlation values obtained by the correlation value calculating section 62, the plurality of individual correlation values corrected according to the broadening factor F B determined, and the concentration of each of the measurement target component and the interference components.

[0103] Next, an example of the operation of the analysis device 100 will be described as a detailed description of the above-described components. In the following, a case where a measurement target component and an interfering component are contained in a sample gas will be assumed.

[0104] <Reference Measurement>

[0105] First, the light source control section 5 controls the semiconductor laser 2 to modulate the wavelength of the laser light at a prescribed modulation frequency and modulation depth, with the peak of the absorption spectrum of the measurement target component as the center. In addition, a reference measurement using a zero-point gas can be performed before the reference measurement using a calibration gas, and a reference correlation value can be measured.

[0106] Next, a calibration gas (a gas whose component concentration is known) is introduced into the cell 1 by an operator or automatically, and a reference measurement is performed. This reference measurement is performed for a calibration gas in which the measurement target component alone is present and a calibration gas in which the interfering component alone is present, respectively.

[0107] Specifically, in the reference measurement, the log calculation section 61 receives each output signal of the light detector 3 at the pressure in each cell, and calculates the log intensity L(t). Furthermore, the correlation value calculation section 62 calculates the correlation value of the log intensity L(t) and the three characteristic signals F1(t), F2(t), and F3(t), and calculates the individual correlation value as the correlation value of each calibration gas per unit concentration by dividing the value obtained by subtracting the reference correlation value from the correlation value by the concentration of the calibration gas. In addition, instead of calculating the individual correlation value per unit concentration, the calibration gas concentration and the individual correlation value of the calibration gas can be stored.

[0108] This is as follows.

[0109] The pressure in the cell is adjusted to p k A calibration gas in which the measurement target component alone is present is introduced into the cell 1, and the correlation value S 1tar (p k ) of the measurement target component is calculated by the correlation value calculation section 62. 2tar (p k ), S 3tar (p k ). Here, S 1tar (p k ) is the correlation value with the first characteristic signal, S 2tar (p k ) is the correlation value with the second characteristic signal, and S 3tar (p k ) is the correlation value with the third characteristic signal. Furthermore, the correlation value calculation section 62 calculates the individual correlation value of each calibration gas per unit concentration by dividing the value obtained by subtracting the reference correlation value from these correlation values S 1tar (p k ), S 2tar(p k ), S 3tar (p k ) minus the reference correlation value R i , and dividing the resulting value by the calibration gas concentration c tar of the measurement target component, the individual correlation values s 1tar (p k ), s 2tar (p k ), and s 3tar (p k ) are calculated. By adjusting the pressure regulator that adjusts the pressure in the cell, or the like, this step is performed at each pressure while the pressure in the cell is changed (for example, by 1 kPa at a time within 20 to 40 kPa), and the relationship between the individual correlation values obtained at each pressure and the pressure is stored. In addition, the calibration gas concentration c tar of the measurement target component can be input to the signal processing section 6 in advance by the user or the like.

[0110] In addition, the calibration gas in which the interference component is present alone is introduced into the cell 1 in which the pressure value is adjusted to p k , and the correlation values S 1int (p k ), S 2int (p k ), and S 3int (p k ) of the interference component are calculated by the correlation value calculation section 62. Here, S 1int (p k ) is the correlation value with the first characteristic signal, S 2int (p k ) is the correlation value with the second characteristic signal, and S 3int (p k ) is the correlation value with the third characteristic signal. Furthermore, the correlation value calculation section 62 calculates the individual correlation values s 1int (p k ), s 2int (p k ), and s 3int (p k ) by subtracting the reference correlation value R i from these correlation values S int (p 1int ), S k (p 2int ), and S k (p 3int ), and dividing the resulting value by the calibration gas concentration c k of the interference component.). By sequentially changing the pressure in the cell (for example, within 20 to 40 kPa, by 1 kPa each time) while performing this step at each pressure, and storing the resulting individual correlation value at each pressure and the pressure, the relationship is stored. In addition, the calibration gas concentration c int The signal is input in advance by the user or the like to the signal processing section 6.

[0111] The individual correlation values s k (p 1tar ), s k (p 2tar ), s k (p 3tar ), s k (p 1int ), s k (p 2int ), s k (p 3int ), and s k (p i ) calculated above are stored in the storage section 63. In addition, this reference measurement can be performed before the product is shipped, or can be performed periodically.

[0112] <Sample Measurement>

[0113] The light source control section 5 controls the semiconductor laser 2 to modulate the wavelength of the laser light at a prescribed modulation frequency and modulation depth, and centered on the peak of the absorption spectrum of the measurement target component.

[0114] Next, the sample gas is introduced into the cell 1 by the operator or automatically, and sample measurement is performed.

[0115] Specifically, in the sample measurement, the logarithm calculation section 61 receives the output signal of the light detector 3, and calculates the logarithmic intensity L(t). Furthermore, the correlation value calculation section 62 calculates the sample correlation values S1, S2, S3 of the logarithmic intensity L(t) and the plurality of characteristic signals F1(t), F2(t), F3(t), and calculates the sample correlation values S'1, S'2, S'3 obtained by subtracting the reference correlation values R i from the correlation values.

[0116] In addition, the broadening factor determination section 64 determines the broadening factor F B by the above-described method (a) or (b).

[0117] The concentration calculation section 65 determines the individual correlation value s' of the measurement target component corrected by both the pressure in the cell and the broadening factor, using the individual correlation values at each pressure in the cell p k stored in the storage section 63, the pressure value p in the cell measured by the pressure sensor 7, the broadening factor F B determined by the broadening factor determination section 64, and the above-described equation (mathematical expression 2).1tar , s' 2tar , and the individual correlation value s' of the interference component corrected only with the pressure in the cell (the spread factor is set to 1) 1int , s' 2int The method of determination can be, for example, a method that considers using linear interpolation, quadratic interpolation, spline interpolation, or the like.

[0118] Further, the concentration calculation section 65 solves the following binary simultaneous equations of the sample correlation values S'1, S'2 corrected by the reference correlation values calculated by the correlation value calculation section 62, the corrected individual correlation values s' of the interference components, and the concentrations C of the measurement target component and the interference components, respectively. 1tar , s' 2tar , s' 1int , s' 2int tar , C int (see Figure 5 ).

[0119] [Equation 5]

[0120] s' 1tar · C tar + s' 1int · C int = S'1

[0121] s' 2tQr · C tar + s' 2int · C int = S'2

[0122] Thus, by solving the simultaneous equations of the above equations (Equation 5) in a simple and reliable calculation, the concentration C of the measurement target component that is removed from the interference and coexistence effects can be determined. tar .

[0123] In addition, even in a case where two or more interference components that are supposed to be removed from the interference effects exist, by adding only the individual correlation values of the interference components and solving the simultaneous equations of the same number of components, the concentration of the measurement target component that is removed from the interference and coexistence effects can be determined.

[0124] That is, in a case where n kinds of gases exist in which the measurement target component and the interference component are added, if the corrected individual correlation value of the jth gas species of the ith characteristic signal is set to s' ij , the concentration of the jth gas species is set to C j , and the sample correlation value of the ith characteristic signal F i (t) is set to S i , the following equation (Equation 6) is established. ​

[0125] [Equation 6]

[0126] s' 11 C1 + s' 12 C2 + s' 13 C3 +... + s' 1n C n = S'1

[0127] s' 21 C1 + s' 22 C2 + s' 23 C3 +... + s' 2n C n = S'2

[0128] s' 31 C1 + s' 32 C2 + s' 33 C3 +... + s' 3n C n = S'3

[0129]

[0130] s' n1 C1 + s' n2 C2 + s' n3 C3 +... + s' nn C n = S' n

[0131] By solving the n simultaneous equations represented by this equation (Equation 6), the concentration of the measurement target component and the interference effect and coexistence effect of each gas of the interference component after correction can be determined. In addition, even when the interference component is not included in the sample, by solving the above n simultaneous equations, the concentration of the measurement target component and the coexistence effect of each gas of the coexisting component after correction can be determined.

[0132] According to the analysis device 100 of the present embodiment configured in this way, the broadening factor F B representing the rate of change of the light absorption spectrum of the measurement target component due to the coexisting component is determined. B The concentration of the measurement target component after correction of the coexistence effect caused by the coexisting component is calculated using the determined broadening factor F , and thus the change in the light absorption spectrum of the measurement target component caused by the coexistence effect of the coexisting component can be corrected, and the concentration of the measurement target component can be measured with high precision.

[0133] In addition, according to the analysis device 100 of the present embodiment, the logarithmic intensity L(t) of the intensity correlation signal correlated with the intensity of the sample light and the plurality of characteristic signals F iThe various relevant values ​​S of (t) i Using multiple calculated correlation values ​​S i The concentration of the measured component is calculated using a significantly fewer variable method, thus enabling the capture of absorption signal characteristics without transforming the absorption signal into an absorption spectrum. This allows for simple calculations to determine the concentration of the measured component without complex spectral processing. For example, while conventional spectral fitting requires hundreds of data points, this invention uses only a few to dozens of correlation values ​​to calculate the concentration with equivalent accuracy. As a result, the computational load is dramatically reduced, eliminating the need for advanced processing equipment, thus lowering the cost of the analytical apparatus 100 and enabling miniaturization.

[0134] Here, multiple characteristic signals are used to obtain signals that are different from sinusoidal signals, so that the concentration of the measured component can be determined with the same or higher accuracy as analytical devices that calculate concentration using conventional phase-locked detection methods.

[0135] <Second Implementation Method (Wavelength Shift Correction Function)>

[0136] The analytical apparatus 100 of this embodiment is a concentration measuring device that measures the concentration of the target component (e.g., CO, CO2, etc.) contained in a sample gas such as exhaust gas. Figure 6 As shown, the analysis apparatus 100 includes: a cell 1 into which a sample gas is introduced; a semiconductor laser 2, which is a light source for irradiating the cell 1 with modulated laser light; a photodetector 3, which is disposed in the optical path of the sample light, which is the laser light transmitted through the cell 1, and receives the sample light; and a signal processing device 4, which receives the output signal of the photodetector 3 and calculates the concentration of the component to be measured based on its value. Furthermore, in the second embodiment, the functions of parts given the same reference numerals as in the first embodiment are substantially the same as those in the first embodiment, and their descriptions are omitted. The parts that differ from the first embodiment will be described below.

[0137] like Figure 7 As shown, the signal processing unit 6 consists of a logarithm calculation unit 61, a correlation value calculation unit 62, a storage unit 63, a concentration calculation unit 65, and a wavelength offset detection unit 66, which serves as a parameter determination unit.

[0138] In this embodiment, the correlation value calculation unit 62 uses a function that is easier to capture the waveform characteristics of the logarithmic intensity L(t) than a sine function, as multiple characteristic signals F. i(t). In the case where the influence of the wavelength shift of the reference light is to be further corrected in the sample gas including the measurement target component and one interference component, three characteristic signals F1(t), F2(t), F3(t) can be considered to be used. As the three characteristic signals, for example, a function based on a Lorentz function which approximates the shape of the absorption spectrum, and a partial differential function of the shift of the function based on the Lorentz function from a reference time position can be considered to be used as shown in the following equation (Math. 7). In the equation (Math. 7), w is a Lorentz width, s is a shift of an absorption peak from a reference time position due to the wavelength shift, A is an arbitrary constant, and A1, A2, A3 are deviations adjusted to be zero when F1(t), F2(t), F3(t) are integrated with a modulation period, respectively. If such a function is used as the characteristic signal, the spectrum change due to the influence of the wavelength shift of the reference light can be captured with higher sensitivity, and the correction of the influence of the wavelength shift of the reference light can be performed with higher accuracy. In addition, as the characteristic signal, a function based on a Voigt function or a function based on a Gaussian function, or the like can be used instead of the function based on the Lorentz function. By using such a function for the characteristic signal, a larger correlation value than when a sine function is used can be obtained, and the measurement accuracy can be improved.

[0139] [Equation 7]

[0140]

[0141]

[0142]

[0143] The storage section 63 stores an individual correlation value which is a correlation value per unit concentration of the measurement target component and each interference component individually present, calculated from the intensity correlation signal of each of the measurement target component and each interference component and the plurality of characteristic signals F1(t), F2(t), F3(t) when the wavelength shift of the known reference light is known. i (t). The plurality of characteristic signals F1(t), F2(t), F3(t) used to calculate the individual correlation value are the same as the plurality of characteristic signals F1(t), F2(t), F3(t) used in the correlation value calculation section 62. i (t). The plurality of characteristic signals F1(t), F2(t), F3(t) used to calculate the individual correlation value are the same as the plurality of characteristic signals F1(t), F2(t), F3(t) used in the correlation value calculation section 62. i (t). In this way, the individual correlation values according to various wavelength shifts of the reference light are stored in the storage section 63.

[0144] Here, it is preferable that the storage section 63 stores, when storing the individual correlation values, a corrected individual correlation value converted to per unit concentration after subtracting the reference correlation value from the correlation value when the measurement target component and each of the interference components exist individually. By this, it is possible to remove the bias included in the individual correlation value, to become a correlation value proportional to the concentration of the measurement target component and the interference components, and to reduce the measurement error. Also, it can be a configuration that does not subtract the reference correlation value.

[0145] The wavelength shift determination section 66 determines the wavelength shift amount W of the reference light from the light intensity signal that is the output signal of the light detector 3.

[0146] As the determination method of the wavelength shift amount W, for example, the steps of (a) or (b) below can be considered.

[0147] (a) The wavelength shift amount W of each of the reference lights is obtained in advance. k (k = 1, 2, ···, I) of the measurement target component and the interference components i (t) The individual correlation values corresponding to each itar (W k ), s iint (W k ), the sample correlation value obtained at the time of measurement is compared with the individual correlation values, and the wavelength shift amount W of the reference light is determined. In the case of this method, the number of characteristic signals required becomes the number obtained by adding the number of types of the measurement target components and the number of types of the interference components and adding 1. The reason for adding 1 is to correspond to the wavelength shift amount that is a parameter common to the light absorption spectrum of each component.

[0148] (b) The wavelength shift amount W of the reference light is determined using the relationship data indicating the relationship between the ambient temperature and the wavelength shift amount W and the measured ambient temperature.

[0149] At this time, the wavelength shift amount W of the reference light is obtained in advance from the ambient temperature of the light source 2 by experiment or by calculation, and the relationship data is generated.

[0150] The concentration calculation section 65 calculates the concentration of the measurement target component using the plurality of sample correlation values obtained by the correlation value calculation section 62.

[0151] Specifically, the concentration calculating section 65 calculates the concentration of the measurement target component from the plurality of sample correlation values obtained by the correlation value calculating section 62, the wavelength shift amount W determined by the wavelength shift determining section 66, and the plurality of individual correlation values stored in the storage section 63. More specifically, the concentration calculating section 65 corrects the plurality of individual correlation values stored in the storage section 63 and acquires them in accordance with the wavelength shift amount W obtained by the wavelength shift determining section 66. Further, the concentration calculating section 65 calculates the concentration of the measurement target component by solving simultaneous equations constituted of the plurality of sample correlation values obtained by the correlation value calculating section 62, the plurality of individual correlation values corrected in accordance with the determined wavelength shift amount W, and the concentrations of the measurement target component and each of the interference components (see FIG. 6). Figure 5

[0152] Next, one example of the operation of the analysis device 100 will be described as a detailed description of each section. Hereinafter, a case where one measurement target component and one interference component are contained in the sample gas will be assumed.

[0153] <Reference Measurement>

[0154] First, the light source controlling section 5 controls the semiconductor laser 2 to modulate the wavelength of the laser light at a prescribed modulation frequency and modulation depth and centered on the peak of the absorption spectrum of the measurement target component. In addition, a reference measurement using a zero-point gas can be performed before the reference measurement using the calibration gas, and the measurement of the reference correlation value can be performed.

[0155] Next, the calibration gas (a gas of which the component concentration is known) is introduced into the cell 1 by the operator or automatically, and a reference measurement is performed. This reference measurement is performed for the calibration gas in which the measurement target component alone exists and the calibration gas in which the interference component alone exists, respectively.

[0156] Specifically, in the reference measurement, the log calculating section 61 receives each output signal of the light detector 3 at each wavelength shift amount of the reference light and calculates the log intensity L(t). Further, the correlation value calculating section 62 calculates the correlation value of the log intensity L(t) and the three characteristic signals Fl(t), F2(t), and F3(t), and calculates the individual correlation value as the correlation value of each calibration gas per unit concentration by dividing the value obtained by subtracting the reference correlation value from the correlation value by the concentration of the calibration gas. In addition, instead of calculating the individual correlation value, the relationship between the calibration gas concentration and the correlation value of the calibration gas can be stored.

[0157] This is specifically as follows.

[0158] The wavelength shift amount of the reference light is adjusted to w k ​The calibration gas in which the measurement target component alone exists is introduced into the cell 1, and the correlation value S 1tar (w k ) of the measurement target component is calculated by the correlation value calculation section 62 2tar (w k ) of the measurement target component is calculated by the correlation value calculation section 62 3tar (w k ) of the measurement target component is calculated by the correlation value calculation section 62 1tar (w k ) is the correlation value of the first characteristic signal, S 2tar (w k ) is the correlation value of the second characteristic signal, and S 3tar (w k ) is the correlation value of the third characteristic signal. Further, the correlation value calculation section 62 calculates the individual correlation values s 1tar (w k ), s 2tar (w k ), and s 3tar (w k ) by dividing the values obtained by subtracting the reference correlation value R i from the correlation values S tar (w 1tar ), S k (w 2tar ), and S k (w 3tar ) by the calibration gas concentration c k of the measurement target component. By changing the set temperature of the semiconductor laser 2 and the like, and sequentially changing the wavelength shift amount of the reference light (for example, 0.001 cm -1 at a time within -0.01 cm -1 to +0.01 cm -1 ), this step is performed for each wavelength shift amount, and the relationship between the individual correlation values obtained at each wavelength shift amount and the wavelength shift amount is stored. In addition, the calibration gas concentration c tar of the measurement target component is input to the signal processing section 6 by the user or the like in advance.

[0159] In addition, the wavelength shift amount of the reference light is adjusted to w k , the calibration gas in which the interference component alone exists is introduced into the cell 1, and the correlation value S 1int (w k ), S 2int (w k ), and S 3int (w k ) of the interference component is calculated by the correlation value calculation section 62. Here, S 1int (w k ) is the correlation value of the first characteristic signal, S 2int (w kS is the correlation value with the second characteristic signal. 3int (w k The correlation value is the correlation value with the third characteristic signal. Furthermore, the correlation value calculation unit 62 calculates the correlation value from these correlation values ​​S. 1int (w k ), S 2int (w k ), S 3int (w k Subtract the reference value R i The obtained value is divided by the concentration c of the calibration gas used for interfering components. int Calculate the individual correlation value s 1int (w k ), s 2int (w k ), s 3int (w k By changing the set temperature of the semiconductor laser 2, the wavelength shift of the reference light is changed sequentially (for example, at -0.01 cm). -1 ~+0.01cm -1 The inner diameter is 0.001cm each time. -1 This step is performed for each wavelength offset, and the relationship between the obtained individual correlation values ​​for each wavelength offset and that wavelength offset is stored. Additionally, the calibration gas concentration c for interfering components... int The signal processing unit 6 is pre-input by the user or others.

[0160] The wavelength offset W of each reference light calculated above k Individual correlation value s 1tar (w k ), s 2tar (w k ), s 3tar (w k ), s 1int (w k ), s 2int (w k ), s 3int (w k The data is stored in storage unit 63. Furthermore, this reference measurement can be performed before product shipment or periodically.

[0161] <Sample Measurement>

[0162] The light source control unit 5 controls the semiconductor laser 2 to modulate the wavelength of the laser at a predetermined modulation frequency and modulation depth, centered on the peak of the absorption spectrum of the component being measured.

[0163] Next, the sample gas is introduced into cell 1 by the operator or automatically for sample measurement.

[0164] Specifically, in the sample measurement, the logarithmic calculation unit 61 receives the output signal of the photodetector 3 and calculates the logarithmic intensity L(t). Furthermore, the correlation value calculation unit 62 calculates the sample correlation values ​​S1, S2, and S3 between the logarithmic intensity L(t) and multiple characteristic signals F1(t), F2(t), and F3(t), and calculates the difference between these correlation values ​​and the reference correlation value R. i The obtained sample correlation values ​​S′1 and S′2.

[0165] In addition, the wavelength offset determination unit 66 determines the wavelength offset amount W using the method described above.

[0166] Concentration calculation unit 65 uses the wavelength offset w of each reference light stored in storage unit 63 k The individual correlation values ​​and the wavelength shift W determined by the wavelength shift determination unit 64 are used to determine the individual correlation values ​​s′ of the measurement target component and the interference component after correction by the wavelength shift W. 1tar ,s′ 2tar ,s′ 1int ,s′ 2int Determined methods could include linear interpolation, quadratic interpolation, spline interpolation, etc.

[0167] Furthermore, similarly to the first embodiment, the concentration calculation unit 65 calculates the sample correlation values ​​S′1, S′2, and the corrected individual correlation value s′ after correction by the reference correlation value calculated by the correlation value calculation unit 62. 1tar ,s′ 2tar ,s′ 1int ,s′ 2in t, and the concentrations C of the measured object and each interfering component. tar C int The following two simultaneous equations are formed.

[0168] [Mathematical Expression 8]

[0169] s′ 1tar ·C tar +s′ 1int ·C int =S′1

[0170] s′ 2tar ·C tar +s′ 2int ·C int =S′2

[0171] Furthermore, when there are n gases in the case of adding the target component and the interfering component, the concentration calculation unit 65, in the same manner as in the first embodiment, becomes an n-variable simultaneous equation that solves the formula (mathematical formula 6) as described above.

[0172] The analysis apparatus 100 of this embodiment, configured in this way, determines the wavelength offset W of the reference light, and uses the determined wavelength offset W to calculate the concentration of the target component after correcting for the influence of the wavelength offset of the reference light. Therefore, it is possible to correct the change in the light absorption spectrum of the target component caused by the wavelength offset of the reference light, and to measure the concentration of the target component with high precision.

[0173] <Other Implementation Methods>

[0174] For example, the configurations of the first embodiment and the second embodiment can be combined to form an analysis device that performs both coexistence effect correction and wavelength shift correction simultaneously. Specifically, the analysis device 100 includes a broadening factor determination unit 64 of the first embodiment and a wavelength shift determination unit 66 of the second embodiment, and stores in the storage unit 63 various pool pressures p as shown in the first and second embodiments. k And the wavelength shift w of the reference light k Individual correlation value s ij (p k ,w k In this analytical apparatus 100, the concentration calculation unit 65 uses the pressure value p in the cell measured by the pressure sensor 7, and the broadening factor F determined by the broadening factor determination unit 64 and the wavelength shift determination unit 66. B The wavelength offset W is used to determine the individual correlation values ​​of the target component and interfering components after correction for the pressure in the cell, the broadening factor, and the wavelength offset, using the following formula (Mathematical Formula 9). Furthermore, the concentration calculation unit 65 uses the corrected individual correlation values ​​and the aforementioned (Mathematical Formula 6) to calculate the concentration of the target component.

[0175] [Mathematical Expression 9]

[0176]

[0177] In each embodiment, the logarithmic calculation unit 61 performs logarithmic calculation on the light intensity signal of the photodetector 3. However, it is also possible to use the light intensity signal of the photodetector 3 to calculate the logarithm (so-called absorbance) of the ratio of the intensity of the sample light to the intensity of the modulation light used as a reference light. In this case, the logarithmic calculation unit 61 can calculate the absorbance by subtracting the logarithm of the intensity of the sample light and the logarithm of the intensity of the reference light, or it can calculate the absorbance by taking the logarithm of the ratio of the intensity of the sample light to the intensity of the reference light.

[0178] In addition, the correlation value calculation unit 62 of each embodiment calculates the correlation value between the intensity correlation signal and the feature signal, but it can also calculate the inner product value between the intensity correlation signal and the feature signal.

[0179] In addition, in each of the embodiments, the storage unit 63 stores the individual correlation value after correction using the reference correlation value, but the storage unit 63 may also store the individual correlation value before correction. The concentration calculation unit 63 is configured to calculate the corrected individual correlation value converted into a unit concentration after subtracting the reference correlation value from the individual correlation value before correction.

[0180] Multiple characteristic signals are not limited to the embodiments described above, as long as they are different functions of each other. Alternatively, as characteristic signals, functions representing the light intensity, logarithmic intensity, or absorbance obtained by flowing through a calibration gas of known concentration (sample spectrum) can also be used. Furthermore, when measuring the concentration of a single metric component, at least one characteristic signal is sufficient.

[0181] Furthermore, when there are n types of gases when the target component and interfering components are added together, characteristic signals of a type larger than n can be used to calculate the individual correlation values ​​of a number greater than the number of gas types, as well as the sample correlation value. A simultaneous equation with a number of elements greater than the number of gas types can be constructed, and the concentration of each component can be determined by the least squares method. By doing so, it is possible to further determine the concentration with relatively small measurement noise.

[0182] In the first embodiment, during reference measurement, the individual correlation values ​​under the pressure in each pool are stored in the storage unit 63, and converted into individual correlation values ​​for each broadening factor using the relationship of formula (mathematical formula 2). However, the individual correlation values ​​for each broadening factor can also be directly measured during reference measurement and stored in the storage unit 63.

[0183] The light source control unit 5 in each embodiment causes the semiconductor laser to oscillate continuously (CW), but as... Figure 8 As shown, the semiconductor laser can also be made to quasi-continuous oscillation (quasi-CW). In this case, the light source control unit 5 controls the current source (or voltage source) of each semiconductor laser 2 by outputting a current (or voltage) control signal, so that the driving current (driving voltage) of the current source (or voltage source) is above a predetermined threshold for pulse oscillation. Specifically, the light source control unit 5 causes the semiconductor laser to perform quasi-continuous oscillation with a predetermined pulse width (e.g., 10-50 ns, duty cycle 5%) that repeats with a predetermined period (e.g., 1-5 MHz). Moreover, the light source control unit 5 scans the value for the wavelength scanned with a wavelength smaller than the threshold for pulse oscillation and changes the driving current (driving voltage) of the current source (or voltage source) at a predetermined frequency to generate a temperature change and scan the oscillation wavelength of the laser. The modulation signal for modulating the driving current varies in the form of a triangular waveform, a sawtooth waveform, or a sine waveform, and its frequency is, for example, 1-100 Hz.

[0184] This allows the semiconductor laser to oscillate quasi-continuously, and the light intensity signal obtained through the photodetector to become... Figure 9 As shown. In this way, the absorption spectrum can be obtained as a whole pulse train. Compared with continuous oscillation, quasi-continuous oscillation consumes less power, heat dissipation is easier, and the lifespan of the light source can also be extended.

[0185] Furthermore, the sample gas can be not only exhaust gas, but also atmospheric gas, and can be liquid or solid. This means that the component of the measured object can be not only gaseous, but also liquid and solid. In addition, this invention can be used not only to measure the absorbance of light transmitted through the measured object, but also to calculate using the absorbance of reflected light.

[0186] The light source is not limited to semiconductor lasers; it can also be other types of lasers. As long as it is a single-wavelength light source with a sufficient half-width to guarantee measurement accuracy and capable of wavelength modulation, any light source can be used.

[0187] Furthermore, various modifications and combinations of implementation methods are possible as long as they do not violate the spirit of this invention.

[0188] Industrial applicability

[0189] According to the present invention, it is possible to correct the changes in the light absorption spectrum of the measured component caused by the coexistence effect of coexisting components or the wavelength shift of the reference light, and to measure the concentration of the measured component with high precision.

Claims

1. An analysis device characterized by comprising: the analysis device analyzes a measurement target component contained in a sample containing one or more interference components, the analysis device has: a light source that irradiates a reference light to the sample; a light detector that detects an intensity of a sample light after the reference light has passed through the sample; a parameter determination section that determines a parameter indicating a change in an optical absorption spectrum of the measurement target component or the interference component due to a coexisting component contained in the sample or a wavelength shift of the reference light; a correlation value calculation section that calculates a correlation value of an intensity correlation signal associated with the intensity of the sample light and a prescribed characteristic signal, the correlation value calculation section calculating a plurality of correlation values using a number of characteristic signals equal to or more than a number obtained by adding a number of kinds of the measurement target component to a number of kinds of the interference component; a storage section that stores individual correlation values, the individual correlation values being correlation values per unit concentration of the measurement target component and each interference component, which are calculated from the intensity correlation signal of each of the measurement target component and each interference component when each of them exists alone and a plurality of the characteristic signals; and a concentration calculation section that calculates a concentration of the measurement target component corrected for a coexistence influence caused by the coexisting component or the wavelength shift of the reference light using the plurality of correlation values obtained by the correlation value calculation section, the plurality of individual correlation values, and the parameter indicating the change in the optical absorption spectrum of the measurement target component or the interference component.

2. The analysis device according to claim 1, characterized in that the parameter indicating the change in the optical absorption spectrum is a broadening factor indicating a rate of change in the optical absorption spectrum of the measurement target component or the interference component due to the coexisting component contained in the sample or a wavelength shift amount of the reference light.

3. The analysis device according to claim 2, characterized in that the concentration calculation section calculates a concentration of the measurement target component corrected for a coexistence influence caused by the coexisting component or a wavelength shift of the reference light using the intensity correlation signal associated with the intensity of the sample light and the broadening factor or the wavelength shift amount.

4. The analysis device according to claim 2 or 3, characterized in that the parameter determination section determines the broadening factor by fitting reference data associated with optical absorption signals of the measurement target component and the interference component for which the broadening factor or the pressure is known and sample data associated with optical absorption signals calculated from the intensity of the sample light.

5. The analysis device according to claim 2 or 3, characterized in that the parameter determination section determines the broadening factor using relationship data indicating a relationship between a concentration of the coexisting component and the broadening factor and a measured concentration of the coexisting component.

6. The analysis device according to claim 2 or 3, characterized in that the parameter determination section determines the wavelength shift amount by fitting reference data associated with optical absorption signals of the measurement target component and the interference component for which the wavelength shift amount is known and sample data associated with optical absorption signals calculated from the intensity of the sample light.

7. The analysis device according to claim 2 or 3, wherein the parameter determining section determines the wavelength shift amount of the reference light using relationship data representing a relationship between a surrounding temperature and the wavelength shift amount, and a measured surrounding temperature.

8. The analysis device according to claim 1, wherein the concentration calculating section corrects a plurality of the individual correlation values using a parameter representing a change in an optical absorption spectrum of the measurement target component or the interference components, calculates the concentration of the measurement target component using the plurality of corrected individual correlation values and the plurality of correlation values obtained by the correlation value calculating section.

9. The analysis device according to claim 8, wherein the concentration calculating section calculates the concentration of the measurement target component by solving simultaneous equations constituted by the plurality of correlation values obtained by the correlation value calculating section, the plurality of corrected individual correlation values, and the concentration of each of the measurement target component and the interference components.

10. The analysis device according to claim 2, wherein the analysis device further comprises a pressure sensor that monitors a pressure of the sample, the concentration calculating section corrects the individual correlation values using a pressure value obtained by the pressure sensor.

11. The analysis device according to claim 10, wherein the concentration calculating section corrects the individual correlation values using the individual correlation values of each component obtained for a plurality of known pressures of the sample, the plurality of correlation values obtained by the correlation value calculating section, the pressure value of the sample, and a relationship of the following equation (Mathematical Equation 2), [Mathematical Equation 2] Here, p is the pressure of the sample measured by the pressure sensor, F B is the spread factor, s ij is the individual correlation value at each pressure stored in the storage section, s' is the corrected individual correlation value, and the above equation (mathematical equation 2) indicates that the individual correlation value s ij (p) at the pressure p of the sample at the time of measurement of the sample is multiplied by F B times, and the individual correlation value at the pressure obtained by multiplying the pressure by F B times is multiplied by 1 / F ij times to obtain the corrected individual correlation value s'.

12. A recording medium that records a program for an analysis device, wherein the program is applied to an analysis device that comprises: a light source that irradiates a reference light to a sample containing one or more interference components; and a light detector that detects a sample light that has passed through the sample, the analysis device functions as a parameter determining section, a correlation value calculating section, a storage section, and a concentration calculating section by the program, the parameter determining section determines a parameter representing a change in an optical absorption spectrum of a measurement target component or an interference component due to a coexisting component contained in the sample or a wavelength shift of the reference light, the correlation value calculating section calculates a correlation value of an intensity correlation signal associated with an intensity of the sample light and a prescribed characteristic signal, the correlation value calculating section calculates a plurality of correlation values using a number of characteristic signals equal to or more than a number obtained by adding a number of types of the measurement target component to a number of types of the interference components, the storage section stores individual correlation values that are correlation values per unit concentration of the measurement target component and each of the interference components, which are obtained from each of the intensity correlation signals and a plurality of the characteristic signals when each of the measurement target component and the interference components exists alone, and the concentration calculating section calculates the concentration of the measurement target component using the plurality of individual correlation values and the plurality of correlation values obtained by the correlation value calculating section. The concentration calculating section calculates the concentration of the measurement target component after correction of the coexistence influence due to the coexistence component or the wavelength shift of the reference light, using the plurality of correlation values obtained by the correlation value calculating section, the plurality of individual correlation values, and a parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component.

13. An analysis method characterized by comprising: The analysis method analyzes a measurement target component contained in a sample by irradiating the sample with a reference light from a light source containing one or more interference components, and detecting a sample light transmitted through the sample by a photodetector, The analysis method, determining a parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component due to a coexistence component contained in the sample or a wavelength shift of the reference light, calculating a correlation value of an intensity correlation signal associated with the intensity of the sample light with respect to a prescribed characteristic signal, using a number of characteristic signals equal to or more than a number obtained by adding the number of types of the measurement target component to the number of types of the interference component, storing individual correlation values which are correlation values per unit concentration of the measurement target component and each of the interference components, calculated from the intensity correlation signal of each of the measurement target component and each of the interference components when each of the measurement target component and each of the interference components exists alone, and a plurality of the characteristic signals, calculating the concentration of the measurement target component after correction of the coexistence influence due to the coexistence component or the wavelength shift of the reference light, using the plurality of correlation values, the plurality of individual correlation values, and a parameter indicating a change in the light absorption spectrum of the measurement target component or the interference component.

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