Measurement device, measurement method, and program

Abstract

The invention relates to a measurement device, a measurement method, and a program. A measurement device (1) is provided with: an irradiation unit (10) that irradiates irradiation light (L); a light receiving unit (20) that receives light to be measured (ML) based on irradiation light (L) irradiated to the region to be measured (R) by the irradiation unit (10); and a control unit (90). And a light receiving unit (20) for receiving light to be measured (ML) on the basis of first reference information for the gas to be measured (G1) acquired at a first center wavelength (lambda1) of the gas to be measured (G1), second reference information for the interference gas (G2) acquired at a second center wavelength (lambda2) and the first center wavelength (lambda1) of the interference gas (G2), and light receiving signals at the first center wavelength (lambda1) and the second center wavelength (lambda2) of the light to be measured (ML) received by the light receiving unit (20). The state of the gas (G1) to be measured contained in the region (R) to be measured is calculated.

Description

[0001] Cross-references between related applications

[0002] This application claims the benefit of Japanese Patent Application No. 2024-054482 filed in Japan on March 28, 2024, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present invention relates to a measuring device, a measuring method, and a program. Background Art

[0004] Currently, there are known technologies for measuring the state of a gas to be measured, including its concentration, etc. For example, Patent Document 1 discloses a laser gas analyzer that eliminates the influence of interference by adding a simple analysis logic and can accurately calculate the concentration.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-191246

[0006] However, the conventional technology described in Patent Document 1 has room for improvement in reducing the influence of interfering gas in measuring the state of the gas to be measured. Summary of the Invention

[0007] An object of the present invention is to provide a measuring device, a measuring method, and a program that can reduce the influence of interfering gas and accurately measure the state of a gas to be measured.

[0008] The measuring device according to some embodiments includes: an irradiation unit that irradiates irradiation light;

[0009] a light receiving unit that receives light to be measured based on the irradiation light irradiated onto the area to be measured by the irradiation unit; and a control unit that calculates the state of the gas to be measured contained in the area to be measured based on first reference information of the gas to be measured obtained at the first center wavelength of the gas to be measured, second reference information of the interfering gas obtained at the second center wavelength of the interfering gas and the first center wavelength, and light reception signals at the first center wavelength and the second center wavelength of the light to be measured received by the light receiving unit.

[0010] Thus, the measuring device can reduce the influence of the interfering gas and accurately measure the state of the gas to be measured. The measuring device can correct the error caused by the interfering gas while using the reference information including the second reference information of the interfering gas, and accurately measure the state of the gas to be measured. For example, the measuring device obtains and corrects the information of the interfering gas contained in the measured area during the measurement process, so even if the distance to the scattered object changes or the concentration of the interfering gas changes, the measurement value based on the light-receiving signal can be corrected according to the change. For example, the measuring device can easily obtain a measurement value with reduced error of the interfering gas when measuring the state of the gas to be measured by WMS (Wavelength Modulation Spectroscopy). As an example, the measuring device can estimate the column concentration caused only by NH3 as the gas to be measured.

[0011] In one embodiment of the measurement device, the control unit may modulate the wavelength of the irradiation light at a modulation frequency, and the first reference information may include, as the first correlation data, a first calibration curve that correlates the concentration of the gas to be measured with the intensity of the light-receiving signal at a frequency component twice the modulation frequency. Thus, the measurement device can accurately calculate the corresponding concentration by comparing the magnitude of the 2f component obtained from the light-receiving signal at the first center wavelength with the pre-acquired first calibration curve.

[0012] In one embodiment of the measuring device, the first reference information may include a first phase of the light-receiving signal of the gas to be measured. Figure 5 As shown, the measurement device can set a criterion for determining whether the magnitude of the 2f component of the measured gas is calculated using the first or second calculation formula at the first center wavelength. For example, the measurement device can set the relationship between the phase and the first phase as the criterion. The measurement device can select the appropriate calculation formula based on this relationship.

[0013] In one embodiment of the measurement device, the second reference information may include, as the second correlation data, a second calibration curve that correlates the concentration of the interfering gas with the intensity of the light-receiving signal at a frequency component twice the modulation frequency. This allows the measurement device to accurately calculate the corresponding concentration by comparing the magnitude of the 2f component obtained from the light-receiving signal at the second central wavelength with the pre-acquired second calibration curve.

[0014] In one embodiment of the measurement device, the second calibration curve can include both a calibration curve at the first center wavelength and a calibration curve at the second center wavelength. This allows the measurement device to compare the magnitude of the 2f component obtained from the received light signal at the second center wavelength with the previously acquired calibration curve at the second center wavelength and accurately calculate the corresponding concentration. The measurement device can then compare the calculated concentration with the previously acquired calibration curve at the first center wavelength and accurately calculate the magnitude of the corresponding 2f component.

[0015] In one embodiment of the measurement device, the control unit may calculate the concentration of the interfering gas by comparing the first intensity of the received light signal of the frequency component, obtained at the second center wavelength, with the second calibration curve at the second center wavelength. This allows the measurement device to easily obtain correction information for reducing the error caused by the interfering gas in the measured value when measuring the state of the measured gas through WMS measurement.

[0016] In one embodiment of the measurement device, the control unit may compare the calculated concentration of the interfering gas with the second calibration curve at the first center wavelength to calculate the second intensity of the received light signal of the frequency component for the interfering gas at the first center wavelength. This allows the measurement device to accurately obtain the magnitude of the 2f component as the calibration information.

[0017] In one embodiment of the measurement device, the control unit may calculate a fourth intensity of the light-receiving signal of the frequency component for the gas to be measured at the first center wavelength by removing the contribution of the second intensity from a third intensity of the light-receiving signal of the frequency component acquired at the first center wavelength. This allows the measurement device to reduce errors due to interfering gases in measured values ​​when measuring the state of the gas to be measured, for example, through WMS measurement.

[0018] In one embodiment of the measurement device, the control unit may change the calculation formula for the fourth intensity based on whether the phase of the light-receiving signal associated with the third intensity matches or does not match the first phase. This allows the measurement device to calculate the fourth intensity using a more appropriate calculation formula based on the relationship between the phase and the first phase. Consequently, the measurement device can reduce the influence of interfering gas and accurately measure the state of the gas being measured.

[0019] In one embodiment of the measuring device, the control unit can calculate the concentration of the measured gas as the state of the measured gas by comparing the calculated fourth intensity with the first calibration curve. Thus, the measuring device can compare the magnitude of the 2f component obtained from the light-receiving signal at the first center wavelength with the pre-acquired first calibration curve to calculate the corresponding concentration with high precision. The measuring device can reduce the influence of interfering gas and measure the state of the measured gas with high precision. For example, the measuring device obtains the concentration of the interfering gas contained in the measured area and corrects the measured value. Therefore, even if the distance to the scattered object changes or the concentration of the interfering gas changes, the measured value can be corrected according to the change.

[0020] Several embodiments involve a measurement method comprising the steps of: irradiating irradiation light; receiving measured light based on the irradiation light irradiated onto the measured area; and calculating the state of the measured gas contained in the measured area based on first reference information of the measured gas obtained at the first center wavelength of the measured gas, second reference information of the interfering gas obtained at the second center wavelength of the interfering gas and the first center wavelength, and light receiving signals received at the first center wavelength and the second center wavelength of the measured light.

[0021] Thus, the measuring device that performs the measuring method can reduce the influence of the interfering gas and accurately measure the state of the gas to be measured. The measuring device can correct the error caused by the interfering gas while using the reference information including the second reference information of the interfering gas, and accurately measure the state of the gas to be measured. For example, the measuring device obtains and corrects the information of the interfering gas contained in the measured area during the measurement process, so even if the distance to the scattered object changes or the concentration of the interfering gas changes, the measurement value based on the light-receiving signal can be corrected according to the change. For example, the measuring device can easily obtain a measurement value with reduced error due to the interfering gas when measuring the state of the gas to be measured by WMS measurement. As an example, the measuring device can estimate the column concentration caused only by NH3 as the gas to be measured.

[0022] Several embodiments involve programs that cause a measuring device to perform an action including the following steps: irradiating irradiation light; receiving measured light based on the irradiation light irradiated onto a measured area; and calculating a state of the measured gas contained in the measured area based on first reference information of the measured gas obtained at a first center wavelength of the measured gas, second reference information of the interfering gas obtained at a second center wavelength of the interfering gas and the first center wavelength, and light reception signals received at the first center wavelength and the second center wavelength of the measured light.

[0023] As a result, the measuring device can reduce the influence of the interfering gas and accurately measure the state of the gas to be measured. The measuring device can correct the error caused by the interfering gas while using the reference information including the second reference information of the interfering gas, and accurately measure the state of the gas to be measured. For example, the measuring device obtains and corrects the information of the interfering gas contained in the measured area during the measurement process, so even if the distance to the scattered object changes or the concentration of the interfering gas changes, the measurement value based on the light-receiving signal can be corrected according to the change. For example, the measuring device can easily obtain a measurement value with reduced error due to the interfering gas when measuring the state of the gas to be measured by WMS measurement. As an example, the measuring device can estimate the column concentration caused only by NH3 as the gas to be measured.

[0024] Effects of the Invention

[0025] According to the present invention, it is possible to provide a measuring device, a measuring method, and a program that can reduce the influence of interfering gas and accurately measure the state of a gas to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a block diagram showing an example of the configuration of a measuring device according to one embodiment of the present invention.

[0027] Figure 2 It is used for Figure 1 FIG1 is a diagram illustrating an example of the operation of the measuring device.

[0028] Figure 3 It is used for Figure 1 FIG2 is a diagram illustrating an example of the operation of the measuring device.

[0029] Figure 4 It is used for Figure 1 FIG3 is a diagram illustrating an example of the operation of the measuring device.

[0030] Figure 5 It is used to utilize Figure 1 A flowchart illustrating an example of a measurement method performed by a measurement device.

[0031] Figure 6 This is a graph used to explain the problems of the conventional technology. DETAILED DESCRIPTION

[0032] The background and problems of the prior art are described in more detail.

[0033] Spectroscopic gas detectors that use lasers as their light source are widely known. These detectors use wavelength-modulated laser light as illumination light and receive the return light reflected or scattered by background objects in an area where the target gas is likely to be present as the target light. These detectors detect the target gas based on changes in the received light signal output by the detector. For example, these detectors utilize the inherent light absorption properties of the target gas to detect the target gas based on the target light.

[0034] Figure 6 It is a graph used to illustrate the problems of the prior art. Figure 6 In FIG. 1 , the solid line curve represents the wavelength dependence of the absorbance of ammonia (hereinafter referred to as “NH 3 ”) as the measured gas, and the dotted line curve represents the wavelength dependence of the absorbance of water (hereinafter referred to as “H 2 O”) as the interfering gas.

[0035] When measuring the state of NH₃ using light, light sources with wavelengths in the near-infrared region are widely used. For example, wavelength modulation spectroscopy (WMS) is widely used, known for its ability to achieve highly sensitive measurements. When WMS is used to measure NH₃ in the near-infrared region, the wavelength of the light used as the light source is primarily limited to the 1.5μm band due to the wavelength dependence of the absorption spectrum of the measured gas.

[0036] The wavelength of the light used as the light source matches a specific absorption peak among the multiple absorption peaks of the gas being measured. For example, a specific absorption peak is one with high sensitivity and absorbance, and also includes absorption peaks that, due to gas selectivity, do not overlap with the absorption of other interfering gases, i.e., do not interfere. To detect NH3 leaks in the atmosphere, it is necessary to select absorption peaks that do not interfere with the absorption of other gases in the atmosphere.

[0037] However, for example, H2O absorption mostly occurs in the 1.5μm band. Therefore, it is not easy to select an absorption peak for NH3 that does not interfere with H2O at all. Therefore, even if the wavelength of light is set to the wavelength of a certain absorption peak for NH3, the measured value related to the state of the gas being measured will include errors caused by H2O. Furthermore, since the entire atmosphere contains H2O, the concentration varies depending on the distance from the background. This is because the concentration of the signal value obtained by WMS is the cumulative value of the concentration based on the optical path length. This concentration is specifically called column concentration and is expressed in units such as ppm·m.

[0038] To address the above-mentioned issues, the present invention aims to provide a measurement device, a measurement method, and a program that can accurately measure the state of a gas being measured while mitigating the effects of interfering gases. For example, the present invention aims to provide a measurement device, a measurement method, and a program that can correct errors in light-received signals containing interfering gases such as H₂O based on the measured value of a light-received signal, using a gas being measured such as NH₃ as the target.

[0039] Hereinafter, one embodiment of the present invention will be described mainly with reference to the drawings. The following description also applies to the measurement method and program executed by the measurement device 1 to which the present invention is applied.

[0040] Figure 1 1 is a block diagram showing an example of the structure of a measuring device 1 according to an embodiment of the present invention. Figure 1 An example of the configuration and function of the measurement device 1 according to one embodiment of the present invention will be mainly described.

[0041] The measurement device 1 includes an irradiation unit 10 , a light receiving unit 20 , a driving unit 30 , an extraction unit 40 , a modulation unit 50 , a storage unit 60 , an input unit 70 , an output unit 80 , and a control unit 90 .

[0042] The irradiation unit 10 includes a light source 11 and an irradiation optical system 12. The light source 11 includes a laser such as a semiconductor laser. The irradiation optical system 12 includes optical elements such as lenses and reflectors that perform optical functions on the irradiation light L emitted from the light source 11. The irradiation unit 10 uses the irradiation optical system 12 to guide the irradiation light L emitted from the light source 11 toward the exterior of the measurement device 1. The irradiation unit 10 irradiates the irradiation light L toward the measurement area R where the measurement gas G1 may be present. The measurement area R also contains interfering gases G2, such as H2O, which are normally present in the atmosphere, in addition to the measurement gas G1 that may be present due to leakage, etc.

[0043] In the present invention, the "measured gas G1" includes, for example, any gas that is the subject of detection and measurement using the measuring device 1. For example, the measured gas G1 may include NH3. The "interference gas G2" includes, for example, any gas that absorbs and interferes at the first center wavelength of the absorption peak of the measured gas G1. For example, the interference gas G2 may include H2O. The irradiation unit 10 irradiates the irradiation light L toward the measured area R where the measured gas G1 may exist in addition to the interference gas G2. The measured area R exists, for example, in the space between the scatterer W and the irradiation unit 10. The scatterer W includes background objects such as walls and pipes.

[0044] The wavelength of the irradiation light L emitted by the irradiation unit 10 is included in the light absorption band of the gas G1 being measured. That is, the wavelength of the irradiation light L is included in one of the first light absorption wavelength bands of the gas G1 being measured. Similarly, the wavelength of the irradiation light L is included in the light absorption band of the interfering gas G2. That is, the wavelength of the irradiation light L is included in one of the second light absorption wavelength bands of the interfering gas G2. The first and second light absorption wavelength bands are each included in wavelength regions such as the visible region and the infrared region, for example.

[0045] The light receiving unit 20 includes a photodetector 21 and a light receiving optical system 22. The photodetector 21 includes a light receiving element such as a photodiode (PD) and an IV conversion circuit. The light receiving optical system 22 includes optical elements such as lenses and reflectors that perform optical operations on light such as the light to be measured ML incident on the light receiving unit 20. The light receiving unit 20 uses the light receiving optical system 22 to guide the light such as the light to be measured ML incident on the light receiving unit 20 toward the photodetector 21. The light receiving unit 20 receives the light to be measured ML based on the irradiation light L irradiated onto the measurement region R by the irradiation unit 10.

[0046] In the present invention, "measurement light ML" refers to, for example, scattered light or reflected light from the scatterer W based on the irradiation light L emitted from the irradiation unit 10, including light absorbed by gases present in the measurement region R, such as the measurement gas G1 and the interfering gas G2. The light receiving unit 20 receives the measurement light ML transmitted through the gas in the measurement region R between the scatterer W and the light receiving unit 20. At least a portion of the wavelength band that can be received by the light receiving unit 20 is included in the light absorption band of the gas. The photodetector 21 included in the light receiving unit 20 has detection sensitivity specific to the wavelength of the measurement light ML.

[0047] The light receiving unit 20 is arranged on the same side as the illuminating unit 10. More specifically, the illuminating unit 10 is arranged on the opposite side of the scatterer W relative to the measured region R, such that the measured region R is located between the scatterer W and the illuminating unit 10. Similarly, the light receiving unit 20 is arranged on the opposite side of the scatterer W relative to the measured region R, such that the measured region R is located between the scatterer W and the light receiving unit 20.

[0048] The photodetector 21 further includes the aforementioned IV conversion circuit, which converts the current-based light reception signal output by the PD when the measured light ML is detected into a voltage. When the photodetector 21 detects the measured light ML, it converts the current-based light reception signal into a voltage-based light reception signal and outputs it to the extraction unit 40.

[0049] The driving unit 30 includes a driving module for driving the light source 11 of the irradiation unit 10. The driving module includes, for example, a laser driver for driving a laser such as a semiconductor laser.

[0050] The extraction unit 40 includes an arbitrary circuit module that extracts a predetermined frequency component from the voltage-based light-receiving signal output from the photodetector 21 of the light-receiving unit 20. This circuit module includes, for example, a lock-in amplifier. The lock-in amplifier receives a voltage signal output from the modulator 50, representing a signal waveform such as a sine wave that fluctuates at a predetermined frequency, and multiplies the voltage-based light-receiving signal by the voltage-based light-receiving signal, thereby extracting the predetermined frequency component from the light-receiving signal.

[0051] The modulation unit 50 includes an arbitrary circuit module that outputs a voltage signal representing a predetermined signal waveform. This circuit module includes, for example, a signal generator (FG). The FG outputs a voltage signal as a modulation signal to the driver 30 for modulating the wavelength of the irradiation light L emitted from the irradiation unit 10 at a modulation frequency f. The FG outputs a voltage signal as a reference signal to the extraction unit 40 for extracting a predetermined frequency component from the voltage-based light reception signal.

[0052] The storage unit 60 includes storage modules such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), an EEPROM (Electrically Erasable Programmable Read-Only Memory), a ROM (Read-Only Memory), and a RAM (Random Access Memory). The storage unit 60 stores information necessary for the operation of the measurement device 1. The storage unit 60 also stores information acquired through the operation of the measurement device 1. For example, the storage unit 60 stores system programs, application programs, and various data acquired through various methods such as communication.

[0053] The storage unit 60 can function as a main storage module, an auxiliary storage module, or a buffer. The storage unit 60 is not limited to being built into the measurement device 1, and may include an external storage module connected via a digital input / output port such as a USB (Universal Serial Bus).

[0054] The input unit 70 includes one or more input interfaces for detecting user input and acquiring input information based on user operations. These input interfaces include physical keys, capacitive keys, a touch screen integrated with the display of the output unit 80, a camera or other imaging module, and a microphone for receiving voice input.

[0055] The output unit 80 includes one or more output interfaces for outputting information and notifying the user. These output interfaces include displays that output information as images, speakers that output information as voice, and vibrators that output information through vibration. Displays include LCDs (Liquid Crystal Displays) and organic EL (Electro Luminescence) displays.

[0056] The control unit 90 includes one or more processors. In the present invention, a "processor" may be a general-purpose processor or a dedicated processor that performs specific processing, but is not limited thereto. For example, the control unit 90 includes a CPU (Central Processing Unit). The control unit 90 is communicatively connected to the various components that make up the measurement device 1 and controls the overall operation of the measurement device 1.

[0057] The measuring device 1 can be configured as a single device in which the storage unit 60, input unit 70, output unit 80, and control unit 90 are integrated with other components, or it can be configured as a separate device in which the other components are separately configured. In the case of a separate device, the storage unit 60, input unit 70, output unit 80, and control unit 90 can be included in any general-purpose electronic device capable of performing their functions, such as a PC (Personal Computer), tablet PC, smartphone, or wearable device such as a smartwatch. By utilizing the control of such a general-purpose electronic device, the measuring device 1 can cooperate with the electronic device to perform various processes related to the measurement method described below.

[0058] The measuring device 1 operates, for example, as a spectroscopic gas detector using a light source 11. To detect the surrounding gas G1 to be measured, the measuring device 1 irradiates a measurement region R with laser light as irradiation light L from the light source 11 of the irradiation unit 10. The measuring device 1 receives, using the light receiving unit 20, the measurement light ML that is scattered or reflected by scatterers W in the background of the measurement region R, where the gas G1 to be measured may be present.

[0059] Measurement device 1 detects the gas G1 using light absorption characteristics determined by the type of gas G1. Measurement device 1 operates using WMS, a type of laser spectroscopy. WMS is a method for determining the state of the gas G1 on the optical path by modulating the wavelength of laser light and measuring changes in the received signal of the modulated light ML.

[0060] In the present invention, the "state of the gas G1 to be measured" includes, for example, the concentration of the gas G1 to be measured. The concentration of the gas G1 to be measured includes, for example, the column concentration of the gas G1 to be measured. The column concentration is expressed as the product of the optical path length of light passing through the gas G1 to be measured and the concentration of the gas G1 to be measured. As mentioned above, the unit of the column concentration is ppm·m.

[0061] The following mainly describes the basic processing contents of the control unit 90 when the measurement device 1 operates using the WMS.

[0062] The control unit 90 controls, for example, a laser driver included in the drive unit 30. Thus, the control unit 90 sets the center wavelength λc of the laser light output from the light source 11 to a desired first center wavelength of the absorption peak of the gas G1 to be measured.

[0063] The control unit 90 controls the FG included in the modulator 50, inputting a voltage signal that fluctuates at a modulation frequency f from the modulator 50 to the laser driver included in the driver 30 as a modulation signal. By inputting this modulation signal from the FG to the driver 30, the control unit 90 modulates the wavelength of the irradiation light L emitted from the irradiation unit 10 at the modulation frequency f. The control unit 90 controls the FG so that the wavelength of the laser light, serving as the irradiation light L, is modulated at a constant modulation frequency f and a modulation width ΔλL near the center wavelength λc. For example, the control unit 90 modulates the wavelength of the laser light at the modulation frequency f and a modulation width ΔλL near the center wavelength λc. As an example, the modulation width ΔλL is expressed in units of wavelength rather than frequency.

[0064] The control unit 90 uses the light source 11 and irradiation optical system 12 of the irradiation unit 10 to irradiate the measurement region R with wavelength-modulated laser light as irradiation light L. The measurement light ML scattered or reflected by the scatterer W is detected by the photodetector 21 via the light receiving optical system 22 of the light receiving unit 20. The measurement light ML is converted into a photocurrent by the PD of the photodetector 21, and then converted into a voltage signal by the IV conversion circuit of the photodetector 21. The light receiving unit 20 outputs this voltage signal as a received light signal to the extraction unit 40.

[0065] The control unit 90 measures the state of the gas G1 based on the light reception signal from the light receiving unit 20. The control unit 90 extracts the 2f component, which is twice the modulation frequency f, from the light reception signal and calculates the state of the gas G1 based on the extracted frequency component.

[0066] For example, when the desired target gas G1 is present in the optical path of the irradiation light L, a frequency component at twice the modulation frequency f is newly generated in the target light ML after the target gas G1 has passed through it. The magnitude of the 2f component in the received light signal is proportional to the column concentration of the target gas G1. Therefore, the control unit 90 extracts the 2f component from the received light signal using phase-sensitive detection using the lock-in amplifier of the extraction unit 40, thereby obtaining a voltage signal proportional to the column concentration of the target gas G1. By measuring the magnitude of the 2f component, the control unit 90 calculates the column concentration of the target gas G1.

[0067] At this time, the 2f component is proportional not only to the column concentration of the gas G1 being measured, but also to the received light power of the measured light ML. In the present invention, "received light power" refers to the received light power of the measured light ML at the light receiving unit 20. The received light power varies based on factors such as the distance between the scatterer W and the measurement device 1 and the surface condition of the scatterer W. Therefore, the control unit 90 needs to remove the fluctuations in the received light power from the 2f component in order to calculate the column concentration of the gas G1 being measured.

[0068] Therefore, the control unit 90 uses the same frequency component as the modulation frequency f, namely the 1f component. Similar to the 2f component, the control unit 90 also uses a lock-in amplifier to obtain the magnitude of the 1f component. The magnitude of the 1f component contained in the received light signal is proportional to the received light power. Therefore, the control unit 90 eliminates fluctuations in the received light power by dividing the 2f component by the 1f component, that is, by calculating the 2f component / 1f component, and obtains a value proportional to the column concentration of the gas G1 being measured.

[0069] As described above, the control unit 90 measures the state of the gas G1 to be measured based on the absorption characteristics of the gas G1 to be measured with respect to the irradiation light L. The control unit 90 measures the state of the gas G1 to be measured based on the 1f signal and the 2f signal obtained from the light reception signal from the light receiving unit 20 by the lock-in amplifier of the extraction unit 40. For example, the control unit 90 calculates the column concentration of the gas G1 to be measured based on the 1f signal and the 2f signal obtained from the light reception signal from the light receiving unit 20.

[0070] On this basis, the control unit 90 also performs other calculations and processing related to the measurement of the state of the gas G1 to be measured. Figure 6 As shown, when the interfering gas G2 has a predetermined absorbance at the first center wavelength λ1 of the measured gas G1, the basic calculation method described above results in an error in the calculated measurement value due to the interfering gas G2. Below, as an example, NH3 is used as the measured gas G1, and H2O is used as the interfering gas G2, primarily to describe the operation of the measurement device 1 to address this problem. However, the present invention is also equally applicable to gases other than those described above.

[0071] exist Figure 6 The figure shows a situation in which the absorption peak of NH3, including interference from H2O, is located at the first center wavelength λ1 in the near-infrared region. As an example, the first center wavelength λ1 is approximately 1512.2 nm. The absorption waveform of H2O overlaps with the absorption waveform of NH3 at the first center wavelength λ1. In other words, interference occurs. As described above, in WMS measurement, the column concentration of NH3 is proportional to the magnitude of the 2f component contained in the measured light ML. In actual measurement, in order to eliminate fluctuations in the received light power, the 1f component is also obtained and the 2f component / 1f component is calculated. This produces a received light signal that is independent of fluctuations in the received light power and is proportional to the column concentration.

[0072] This is an advantage of WMS, but the 1f component has nothing to do with absorption, and this is not included in the present invention in essence. Therefore, the following description will focus on the 2f component only. Figure 6 As shown in FIG. 1 , if interference due to H 2 O occurs as in the absorption peak at the first central wavelength λ1, the 2f component of the received light signal includes an error due to H 2 O.

[0073] In both the calibration and measurement processes described below, phase-sensitive detection is performed using the lock-in amplifier of the extraction unit 40 to measure minute signals. The received light signal generated by phase-sensitive detection is acquired as a vector. Typically, the magnitude of the received light signal vector is assumed to be a 2f component proportional to the concentration. In this case, the error for gases other than the target gas G1, which is the target gas, is expressed as a vector sum.

[0074] According to simulations using the database at the first central wavelength λ1, the phase of the light-receiving signal at the "bottom" of the H2O absorption spectrum, based on the overlap, differs by 180° from that of the light-receiving signal of NH3. Consequently, the light-receiving signals cancel each other out. Therefore, the measuring device 1 considers not only the magnitude of the light-receiving signal, which is a vector including both NH3 and H2O, but also its phase, thereby estimating the light-receiving signal due solely to NH3, corrected for the effects of H2O. The measuring device 1 calculates the NH3 column concentration by applying a pre-acquired calibration curve to this light-receiving signal. Note that the calibration curve is primarily generated based on the magnitude of the light-receiving signal and does not include phase information.

[0075] The measuring device 1 needs to obtain the column concentration of H2O as information in the prior calibration process. In order to avoid the influence of NH3 absorption, the measuring device 1 obtains this information in the frequency band other than the first central wavelength λ1. For example, only using Figure 6The absorption peak of H2O at the second center wavelength λ2 is shown. As an example, the second center wavelength λ2 is approximately 1511.8 nm. By utilizing the absorption peak of H2O at the second center wavelength λ2, the influence of NH3 absorption is reduced, and H2O becomes dominant.

[0076] If the measurement device 1 previously acquires a calibration curve containing information about the column concentration of HO at the second center wavelength λ2 through calibration processing, the column concentration of HO can be acquired during the WMS measurement at the second center wavelength λ2. The measurement device 1 also previously acquires a calibration curve for HO at the first center wavelength λ1 through calibration processing. This allows the magnitude of the 2f component of HO at the first center wavelength λ1 to be determined based on the column concentration of HO acquired at the second center wavelength λ2. By performing WMS measurement at the first center wavelength λ1 and utilizing information about the 2f component of HO, the measurement device 1 can extract the received light signal due solely to NH3 based on the magnitude and phase of the received light signal. As described above, even if the measured value at the first center wavelength λ1 includes contributions from both HO and NH3, the measurement device 1 can reproduce only the 2f component of NH3 by acquiring the column concentration of HO based on the measurement results at the second center wavelength λ2.

[0077] Next, the operation of the measuring device 1 described above will be described in more detail with reference to the drawings.

[0078] Figure 2 It is used for Figure 1 FIG1 is a diagram for explaining an example of the operation of the measuring device 1. Figure 2 The configuration of the calibration process executed by the measurement device 1 before measuring the state of the gas G1 to be measured is schematically shown. Figure 3 It is used for Figure 1 FIG2 is a diagram illustrating an example of the operation of the measuring device 1. Figure 4 It is used for Figure 1 FIG3 is a diagram illustrating an example of the operation of the measuring device 1. Figure 3 and Figure 4 The structure of the measurement process when the measurement device 1 actually performs the measurement of the state of the gas G1 to be measured is schematically shown. Figure 5 Is used for Figure 1 A flowchart illustrating an example of a measurement method performed by the measurement device 1.

[0079] In step S101, the control unit 90 of the measuring device 1 acquires reference information. In the present invention, "reference information" includes, for example, first reference information and second reference information. Step S101 corresponds to the calibration process performed by the measuring device 1 before measuring the state of the gas G1 to be measured. Figure 2 As shown, in step S101, for example, when only one of the measured gas G1 and the interfering gas G2 exists in the measured region R, first reference information and second reference information are acquired for each of the gases. This configuration is not limiting, and reference information may be acquired in advance at a location different from the measured region R.

[0080] The first reference information is, for example, reference information of the gas G1 under test, obtained at its first center wavelength λ1. The first reference information includes, as first correlation data, a first calibration curve La1 that correlates the concentration Ca of the gas G1 under test with the intensity of the light-receiving signal at a frequency component twice the modulation frequency f, namely, the magnitude Sa of the 2f component. For example, the concentration Ca can be the column concentration (ppm·m). Furthermore, the first reference information includes the first phase θ1 of the light-receiving signal of the gas G1 under test, obtained through WMS measurement.

[0081] The second reference information is, for example, reference information of the interfering gas G2 obtained at its second center wavelength λ2 and its first center wavelength λ1. The second reference information includes, as second correlation data, a second calibration curve Lw that correlates the concentration Cw of the interfering gas G2 with the intensity of the received light signal at a frequency component twice the modulation frequency f, i.e., the magnitude Sw of the 2f component. As an example, the concentration Cw can be the column concentration (ppm·m). The second calibration curve Lw includes both the calibration curve Lw1 at the first center wavelength λ1 and the calibration curve Lw2 at the second center wavelength λ2.

[0082] The control unit 90 of the measurement device 1 stores the acquired reference information in the storage unit 60 .

[0083] The processing after step S102 corresponds to the measurement processing when the measurement device 1 actually performs the measurement of the state of the gas G1 to be measured. Figure 3 and Figure 4 As shown, after step S102 , it is assumed that both the gas to be measured G1 and the interfering gas G2 exist in the region to be measured R.

[0084] In step S102, the control unit 90 of the measurement device 1 performs WMS measurement at the second center wavelength λ2. As the measurement results of the WMS measurement, the control unit 90 obtains the magnitude S2 and the second phase θ2 of the 2f component. Figure 3 As shown, the gas to be measured G1 and the interfering gas G2 exist in the measured region R, but the interfering gas G2 plays a dominant role in the absorption of light.

[0085] In step S103, the control unit 90 of the measurement device 1 compares the first intensity of the received signal of the frequency component of twice the modulation frequency f, obtained at the second center wavelength λ2, with the second calibration curve Lw2 at the second center wavelength λ2, thereby calculating the concentration Cw of the interfering gas G2. For example, the control unit 90 sets the magnitude S2 of the 2f component obtained in step S102 as the first intensity and calculates the concentration Cw of the interfering gas G2 based on the second calibration curve Lw2 obtained in step S101.

[0086] In step S104, the control unit 90 of the measurement device 1 compares the concentration Cw of the interfering gas G2 calculated in step S103 with the second calibration curve Lw1 at the first central wavelength λ1. This calculation calculates the second intensity of the received light signal at the first central wavelength λ1, representing a frequency component twice the modulation frequency f, for the interfering gas G2. For example, the control unit 90 calculates the magnitude Sw of the 2f component at the first central wavelength λ1 for the interfering gas G2 as the second intensity.

[0087] In step S105, the control unit 90 of the measurement device 1 performs WMS measurement at the first center wavelength λ1. As the measurement result of the WMS measurement, the control unit 90 obtains the magnitude S and phase θ of the 2f component. Figure 4 As shown, the measured gas G1 and the interfering gas G2 exist in the measured region R, and the absorption of light is affected by both the measured gas G1 and the interfering gas G2. Therefore, the magnitude S of the 2f component includes information on both the measured gas G1 and the interfering gas G2.

[0088] In step S106, the control unit 90 of the measurement device 1 determines whether the phase θ acquired in step S105 and the first phase θ1 acquired in step S101 are identical. If the control unit 90 determines that the phase θ and the first phase θ1 are identical, the process of step S107 is executed. If the control unit 90 determines that the phase θ and the first phase θ1 are different, the process of step S108 is executed.

[0089] In steps S107 and S108, the control unit 90 of the measurement device 1 removes the contribution of the second intensity from the third intensity of the received signal for the frequency component of the light received signal at twice the modulation frequency f, obtained at the first center wavelength λ1. This calculation then calculates the fourth intensity of the received signal for the frequency component at the first center wavelength λ1 for the gas G1 being measured. For example, the control unit 90 sets the magnitude S of the 2f component obtained in step S105 as the third intensity, the magnitude Sw of the 2f component obtained in step S104 as the second intensity, and the magnitude Sa of the 2f component as the fourth intensity, and performs the calculation for the gas G1 at the first center wavelength λ1. At this point, the control unit 90 changes the calculation formula for the fourth intensity based on whether the phase θ of the received signal associated with the third intensity matches or does not match the first phase θ1.

[0090] For example, in step S107, if the control unit 90 of the measurement device 1 determines in step S106 that the phase θ and the first phase θ1 coincide with each other, the magnitude Sa of the 2f component is calculated using the first calculation formula. The first calculation formula includes, for example, a formula such as Sa=S+Sw.

[0091] For example, in step S108, if the control unit 90 of the measurement device 1 determines in step S106 that the phase θ and the first phase θ1 do not coincide with each other, the magnitude Sa of the 2f component is calculated using the second calculation formula. The second calculation formula includes, for example, a formula such as Sa = |S - Sw|. An example of θ ≠ θ1 is a relationship such as θ = θ1 + π.

[0092] In step S109, the control unit 90 of the measurement device 1 compares the magnitude Sa of the 2f component as the fourth intensity calculated in step S107 or step S108 with the first calibration curve La1 obtained in step S101, thereby calculating the concentration Ca of the measured gas G1 as the state of the measured gas G1.

[0093] As described above, the control unit 90 of the measurement device 1 calculates the state of the gas G1 to be measured contained in the measurement region R based on the reference information acquired through the calibration process and the light reception signals at the first center wavelength λ1 and the second center wavelength λ2 of the light to be measured ML received by the light receiving unit 20. The control unit 90 can display the calculated state of the gas G1 to be measured on the display of the output unit 80 or the like.

[0094] In step S110, the control unit 90 of the measurement device 1 determines whether the measurement has ended. If the control unit 90 determines that the measurement has ended, the process ends. If the control unit 90 determines that the measurement has not ended, the process returns to step S102 and executes the process from step S102 onwards again.

[0095] The measurement device 1 according to the aforementioned embodiment can accurately measure the state of the gas G1 to be measured, while mitigating the effects of the interfering gas G2. The measurement device 1 calculates the state of the gas G1 to be measured within the measurement region R based on pre-acquired reference information and the light signals received at the first and second center wavelengths λ1 and λ2. The reference information includes first reference information about the gas G1 to be measured, acquired at the first center wavelength λ1 of the gas G1, and second reference information about the interfering gas G2, acquired at the second and first center wavelengths λ1 of the interfering gas G2.

[0096] Thus, the measurement device 1 can accurately measure the state of the measured gas G1 by correcting errors due to the interfering gas G2 while utilizing reference information, including the second reference information regarding the interfering gas G2. For example, the measurement device 1 acquires and corrects information regarding the interfering gas G2 contained in the measured region R during the measurement process. Therefore, even if the distance to the scatterer W or the concentration Cw of the interfering gas G2 changes, the measured value based on the received light signal can be corrected accordingly. For example, when measuring the state of the measured gas G1 using WMS, the measurement device can easily obtain a measurement value that minimizes errors due to the interfering gas G2. As an example, the measurement device 1 can estimate the column concentration Ca due solely to NH3 in the measured gas G1.

[0097] The first reference information includes, as first correlation data, a first calibration curve La1 that correlates the concentration Ca of the gas G1 being measured with the intensity Sa of the received light signal at a frequency component twice the modulation frequency f. This allows measurement device 1 to accurately calculate the corresponding concentration Ca by comparing the magnitude Sa of the 2f component obtained from the received light signal at the first central wavelength λ1 with the pre-acquired first calibration curve La1.

[0098] The first reference information includes the first phase θ1 of the light-receiving signal of the gas G1 to be measured. Figure 5 As shown, the measurement device 1 can set a criterion for determining whether to use the first or second calculation formula to calculate the magnitude Sa of the 2f component for the measured gas G1 at the first center wavelength λ1. For example, the measurement device 1 can set the relationship between the phase θ and the first phase θ1 as the criterion. The measurement device 1 can select the appropriate calculation formula based on this relationship.

[0099] The second reference information includes, as second correlation data, a second calibration curve Lw that correlates the concentration Cw of the interfering gas G2 with the intensity of the received light signal at a frequency component twice the modulation frequency f. Thus, measurement device 1 compares the magnitude S2 of the 2f component obtained from the received light signal at the second central wavelength λ2 with the pre-acquired second calibration curve Lw to accurately calculate the corresponding concentration Cw.

[0100] The second calibration curve Lw includes both the calibration curve Lw1 at the first center wavelength λ1 and the calibration curve Lw2 at the second center wavelength λ2. Thus, the measurement device 1 compares the magnitude S2 of the 2f component obtained from the received light signal at the second center wavelength λ2 with the previously acquired calibration curve Lw2 to accurately calculate the corresponding concentration Cw. Next, the measurement device 1 compares the calculated concentration Cw with the previously acquired calibration curve Lw1 to accurately calculate the magnitude Sw of the corresponding 2f component.

[0101] The measurement device 1 compares the first intensity S2 of the received signal, obtained at the second center wavelength λ2 and having a frequency component twice the modulation frequency f, with the second calibration curve Lw2 at the second center wavelength λ2 to calculate the concentration Cw of the interfering gas G2. This allows the measurement device 1 to easily obtain correction information for reducing the error due to the interfering gas G2 relative to the measured value when measuring the state of the measured gas G1 using WMS.

[0102] The measuring device 1 compares the calculated concentration Cw of the interfering gas G2 with the second calibration curve Lw1 at the first central wavelength λ1. This calculates the second intensity Sw of the received light signal corresponding to the frequency component twice the modulation frequency f for the interfering gas G2 at the first central wavelength λ1. This allows the measuring device 1 to accurately obtain the magnitude Sw of the 2f component as the aforementioned correction information.

[0103] The measurement device 1 removes the contribution of the second intensity Sw from the third intensity S of the received light signal for the frequency component twice the modulation frequency f, obtained at the first center wavelength λ1. This calculation results in a fourth intensity Sa of the received light signal for the frequency component at the first center wavelength λ1 for the gas G1 being measured. This allows the measurement device 1 to reduce errors caused by the interfering gas G2 relative to the measured value when measuring the state of the gas G1 using WMS, for example.

[0104] The measurement device 1 changes the calculation formula for the fourth intensity Sa based on whether the phase θ of the light-receiving signal associated with the third intensity S matches or does not match the first phase θ1. This allows the measurement device 1 to calculate the fourth intensity Sa using an appropriate formula based on the relationship between the phase θ and the first phase θ1. Consequently, the measurement device 1 can reduce the influence of the interfering gas G2 and accurately measure the state of the gas G1 being measured.

[0105] The measuring device 1 compares the calculated fourth intensity Sa with the first calibration curve La1, thereby calculating the concentration Ca of the measured gas G1 as the state of the measured gas G1. Thus, by comparing the magnitude Sa of the 2f component obtained from the received light signal at the first central wavelength λ1 with the pre-acquired first calibration curve La1, the measuring device 1 can accurately calculate the corresponding concentration Ca. The measuring device 1 can reduce the influence of the interfering gas G2 and accurately measure the state of the measured gas G1. For example, the measuring device 1 obtains the concentration Cw of the interfering gas G2 contained in the measured region R and corrects the measured value. Therefore, even if the distance to the scatterer W or the concentration Cw of the interfering gas G2 changes, the measured value can be corrected accordingly.

[0106] While the present invention has been described based on the accompanying drawings and embodiments, it should be noted that those skilled in the art are capable of various modifications and variations based on the present invention. Therefore, it should be noted that the scope of the present invention includes such modifications and variations. For example, the functions included in each structure or step may be rearranged in a logically consistent manner, and multiple structures or steps may be combined into one or divided.

[0107] For example, a general-purpose electronic device such as a smartphone or computer can function as part of the measurement device 1 according to one embodiment described above. Specifically, a program describing the processing details that implement the various functions of the control unit 90 and other components of the measurement device 1 according to one embodiment is stored in the memory of the electronic device, and the program is read and executed by the processor of the electronic device. Therefore, the present invention can also be implemented as a program that can be executed by the processor.

[0108] Alternatively, the present invention may be implemented as a non-transitory computer-readable medium storing a program executable by one or more processors in order to enable the measurement device 1 according to one embodiment to perform various functions.

[0109] For example, the shape, pattern, size, arrangement, orientation, type, and number of the aforementioned components are not limited to those illustrated in the above description and accompanying drawings. Any shape, pattern, size, arrangement, orientation, type, and number of the components can be configured as desired as long as they achieve their intended functions. The illustrated components of the measurement device 1 are merely functional concepts, and their specific implementation is not limited to the illustrated components.

[0110] In the above embodiment, the first reference information includes, as first correlation data, a first calibration curve La1 that correlates the concentration Ca of the gas G1 to be measured and the intensity Sa of the received light signal having a frequency component twice the modulation frequency f. However, the present invention is not limited to this. The first reference information may include, in place of the first correlation data or in addition to it, any other information that can be used to calculate the state of the gas G1 to be measured.

[0111] In the above embodiment, the first reference information includes the first phase θ1 of the light-receiving signal of the gas G1 being measured. However, this is not limiting. The first reference information may include, in addition to or in place of the first phase θ1, any other information useful for calculating the state of the gas G1 being measured. For example, the first reference information may include the second phase θ2 included in the measurement results of a WMS measurement performed at the second center wavelength λ2.

[0112] In the above embodiment, the second reference information includes, as the second correlation data, a second calibration curve Lw that correlates the concentration Cw of the interfering gas G2 and the intensity of the received light signal having a frequency component twice the modulation frequency f. However, the present invention is not limited to this. The second reference information may also include, in place of the second correlation data or in addition to it, any other information that can be used to calculate the state of the gas G1 being measured.

[0113] In the above embodiment, the second calibration curve Lw is described as including both the calibration curve Lw1 at the first center wavelength λ1 and the calibration curve Lw2 at the second center wavelength λ2. However, this is not limiting. If the measurement device 1 is capable of calculating the state of the measured gas G1, the second calibration curve Lw may include only one of the calibration curves Lw1 and Lw2.

[0114] In the above embodiment, the measurement device 1 calculates the concentration Cw of the interfering gas G2 by comparing the first intensity S2 of the received signal having a frequency component twice the modulation frequency f, obtained at the second center wavelength λ2, with the second calibration curve Lw2 at the second center wavelength λ2. However, the present invention is not limited to this. The measurement device 1 may calculate the concentration Cw by any other method using reference information and the received signal at the second center wavelength λ2. If the state of the gas G1 to be measured can be calculated using the reference information and the received signal at the second center wavelength λ2, the concentration Cw may not be calculated during the measurement process.

[0115] In the above embodiment, the measurement device 1 compares the calculated concentration Cw of the interfering gas G2 with the second calibration curve Lw1 at the first central wavelength λ1 to calculate the second intensity Sw of the received light signal having a frequency component twice the modulation frequency f for the interfering gas G2 at the first central wavelength λ1. However, the present invention is not limited to this. The measurement device 1 may also calculate the second intensity Sw by any other method using reference information and the received light signal at the second central wavelength λ2.

[0116] In the above embodiment, the measurement device 1 calculates the fourth intensity Sa of the light reception signal of the frequency component twice the modulation frequency f, obtained at the first center wavelength λ1, by removing the contribution of the second intensity Sw from the third intensity S of the light reception signal of the frequency component at twice the modulation frequency f, for the measured gas G1. However, the present invention is not limited to this embodiment. The measurement device 1 may also calculate the fourth intensity Sa by any other method using reference information and the light reception signals at the first center wavelength λ1 and the second center wavelength λ2.

[0117] In the above embodiment, the measurement device 1 changes the calculation formula for the fourth intensity Sa based on whether the phase θ of the light-receiving signal associated with the third intensity S matches or does not match the first phase θ1. However, the present invention is not limited to this. The measurement device 1 may utilize any other criterion in addition to or in place of the relationship between the phase θ and the first phase θ1 as a criterion for selecting the calculation formula.

[0118] In the above embodiment, the measurement device 1 calculates the concentration Ca of the gas G1 as the state of the gas G1 by comparing the calculated fourth intensity Sa with the first calibration curve La1. However, the present invention is not limited to this. The measurement device 1 may also calculate the concentration Ca by any other method using reference information and the light reception signals at the first center wavelength λ1 and the second center wavelength λ2.

[0119] In the above embodiment, the measurement device 1 calculates the state of the gas G1 at a single first center wavelength λ1 for a single gas G1, but the present invention is not limited to this. The measurement device 1 may calculate the state of the gas G1 for a plurality of gases G1, or may calculate the state of the gas G1 when the first center wavelength λ1 includes a plurality of wavelengths.

[0120] In the above embodiment, the measurement device 1 calculates the state of the gas G1 to be measured based on a single second center wavelength λ2 for a single interfering gas G2. However, the present invention is not limited to this. The measurement device 1 may calculate the state of the gas G1 to be measured for multiple interfering gases G2, or may calculate the state of the gas G1 to be measured when the second center wavelength λ2 includes multiple wavelengths.

[0121] For example, in the above embodiment, the measuring device 1 includes the irradiation unit 10 and the drive unit 30 as separate components, but the present invention is not limited to this. The measuring device 1 may include the irradiation unit 10 and the drive unit 30 as a single component. For example, the measuring device 1 may integrate the functions of a driver into the irradiation unit 10, or integrate the functions of the light source 11 into the drive unit 30. The irradiation light L is then emitted to the outside via the irradiation optical system 12, which includes light guide components such as optical fibers and lenses.

[0122] In the above embodiment, the measuring device 1 includes the light receiving unit 20 and the extraction unit 40 as separate components, but the present invention is not limited thereto. The measuring device 1 includes the light receiving unit 20 and the extraction unit 40 as a single component.

[0123] In the above embodiment, the measurement device 1 extracts a frequency component that is twice the modulation frequency f from the received light signal and calculates the state of the gas G1 based on the extracted frequency component. However, this is not limiting. The measurement device 1 may also calculate the state of the gas G1 using any other method. For example, the measurement device 1 may calculate the state of the gas G1 using a method that does not rely on the WMS.

[0124] In the above embodiment, the measurement device 1 calculates the 2f component / 1f component to eliminate fluctuations in the received light power and obtain a value proportional to the concentration Ca of the gas G1 to be measured, which represents the state of the gas G1 to be measured. However, the present invention is not limited to this. The measurement device 1 may also calculate the state of the gas G1 to be measured using any other calculation formula based on the 2f component extracted from the received light signal.

[0125] In the above embodiment, the measurement device 1 is described as including a lock-in amplifier as the extraction unit 40, but the present invention is not limited to this. The measurement device 1 may also implement the same functions as the lock-in amplifier of the extraction unit 40 by using software executed by the CPU of the control unit 90, etc., instead of or in addition to the lock-in amplifier. In this case, the measurement device 1 may utilize Fourier transform.

[0126] In the above embodiment, the measurement device 1 measures the state of the gas G1 based on the absorption characteristics of the gas G1 with respect to the irradiation light L. However, the present invention is not limited to this. The measurement device 1 may also measure the state of the gas G1 based on the scattering characteristics and reflection characteristics of the gas G1 with respect to the irradiation light L.

[0127] In the above embodiment, the light receiving unit 20 is arranged on the same side as the irradiating unit 10 and receives the measured light ML scattered or reflected by the scatterer W located behind the measured gas G1. However, the present invention is not limited to this embodiment. The light receiving unit 20 may also be arranged to face the irradiating unit 10 across the measured region R. In this case, the light receiving unit 20 can receive the measured light ML obtained by transmitting the irradiation light L emitted by the irradiating unit 10 through the measured region R.

[0128] In the above embodiment, the scatterer W is described as including background objects such as walls and pipes, but the present invention is not limited thereto. The scatterer W may be any object other than walls and pipes.

[0129] In the above embodiment, the state of the gas G1 to be measured includes the concentration of the gas G1 to be measured, but the present invention is not limited thereto. The state of the gas G1 to be measured may include the presence or absence of the gas G1 to be measured.

[0130] The following examples illustrate some embodiments of the present invention, but it should be noted that the embodiments of the present invention are not limited thereto.

[0131] [Note 1]

[0132] A measuring device, wherein

[0133] The measuring device comprises:

[0134] an irradiation portion that irradiates irradiation light;

[0135] a light receiving unit that receives light to be measured based on the irradiation light irradiated to the area to be measured by the irradiation unit; and

[0136] A control unit that calculates the state of the gas to be measured contained in the measured area based on the first reference information of the gas to be measured obtained at the first center wavelength of the gas to be measured, the second reference information of the interfering gas obtained at the second center wavelength of the interfering gas and the first center wavelength, and the light receiving signals at the first center wavelength and the second center wavelength of the light to be measured received by the light receiving unit.

[0137] [Note 2]

[0138] The measuring device according to Supplementary Note 1, wherein

[0139] The control unit modulates the wavelength of the irradiation light at a modulation frequency,

[0140] The first reference information includes, as first correlation data, a first calibration curve that correlates the concentration of the gas to be measured and the intensity of the light-receiving signal having a frequency component twice the modulation frequency.

[0141] [Note 3]

[0142] The measuring device according to Supplementary Note 2, wherein:

[0143] The first reference information includes a first phase of the light reception signal of the gas to be measured.

[0144] [Note 4]

[0145] The measuring device according to Supplement 2 or 3, wherein

[0146] The second reference information includes, as second correlation data, a second calibration curve that correlates the concentration of the interfering gas and the intensity of the light-receiving signal having a frequency component twice the modulation frequency.

[0147] [Note 5]

[0148] The measuring device according to Supplementary Note 4, wherein

[0149] The second calibration curve includes both a calibration curve at the first center wavelength and a calibration curve at the second center wavelength.

[0150] [Note 6]

[0151] The measuring device according to Supplement 4 or 5, wherein

[0152] The control unit calculates the concentration of the interfering gas by comparing a first intensity of the light reception signal of the frequency component acquired at the second central wavelength with the second calibration curve at the second central wavelength.

[0153] [Note 7]

[0154] The measuring device according to Supplementary Note 6, wherein:

[0155] The control unit compares the calculated concentration of the interfering gas with the second calibration curve at the first central wavelength to calculate a second intensity of the light reception signal of the frequency component for the interfering gas at the first central wavelength.

[0156] [Note 8]

[0157] The measuring device according to Supplementary Note 7, wherein:

[0158] The control unit calculates a fourth intensity of the light reception signal of the frequency component for the gas to be measured at the first center wavelength by removing a contribution of the second intensity from a third intensity of the light reception signal of the frequency component acquired at the first center wavelength.

[0159] [Note 9]

[0160] The measuring device according to Supplementary Note 8, wherein

[0161] The control unit changes a calculation formula for the fourth intensity according to whether a phase of the light-receiving signal associated with the third intensity matches or does not match the first phase.

[0162] [Note 10]

[0163] The measuring device according to Supplementary Note 8 or 9, wherein

[0164] The control unit calculates the concentration of the gas to be measured as the state of the gas to be measured by comparing the calculated fourth intensity with the first calibration curve.

[0165] [Note 11]

[0166] A determination method, wherein

[0167] The determination method comprises the following steps:

[0168] irradiate irradiating light;

[0169] receiving light to be measured based on the irradiation light irradiated onto the area to be measured; and

[0170] Based on the first reference information of the measured gas obtained at the first center wavelength of the measured gas, the second center wavelength of the interfering gas and the second reference information of the interfering gas obtained at the first center wavelength, and the received light signals at the first center wavelength and the second center wavelength of the measured light, the state of the measured gas contained in the measured area is calculated.

[0171] [Note 12]

[0172] A procedure in which

[0173] The program causes the measuring device to perform actions including the following steps:

[0174] irradiate irradiating light;

[0175] receiving light to be measured based on the irradiation light irradiated onto the area to be measured; and

[0176] Based on the first reference information of the measured gas obtained at the first center wavelength of the measured gas, the second center wavelength of the interfering gas and the second reference information of the interfering gas obtained at the first center wavelength, and the received light signals at the first center wavelength and the second center wavelength of the measured light, the state of the measured gas contained in the measured area is calculated.

[0177] Description of the label

[0178] 1. Measuring device

[0179] 10Irradiation Department

[0180] 11 Light Source

[0181] 12 Illumination optical system

[0182] 20 light receiving part

[0183] 21 photodetectors

[0184] 22 Light receiving optical system

[0185] 30 drive unit

[0186] 40 Extraction Department

[0187] 50 Modulation Department

[0188] 60 Storage Department

[0189] 70 Input unit

[0190] 80 output unit

[0191] 90 Control Department

[0192] f modulation frequency

[0193] Ca concentration

[0194] Cw concentration

[0195] G1 measured gas

[0196] G2 interference gas

[0197] L irradiation light

[0198] La1 first calibration line

[0199] Lw 2nd calibration line

[0200] Lw1 calibration curve

[0201] Lw2 calibration curve

[0202] ML measured light

[0203] RMeasured area

[0204] The magnitude of the S2f component (third intensity)

[0205] The magnitude of the S22f component (first intensity)

[0206] Sa 2f component magnitude (fourth intensity)

[0207] The magnitude of the Sw 2f component (second intensity)

[0208] W scatterer

[0209] λ1 first central wavelength

[0210] λ2 second center wavelength

[0211] θ phase

[0212] θ1 first phase

[0213] θ2 second phase

Claims

1. A measuring device, wherein: The measuring device comprises: an irradiation portion that irradiates irradiation light; a light receiving unit that receives light to be measured based on the irradiation light irradiated to the area to be measured by the irradiation unit; and A control unit that calculates the state of the gas to be measured contained in the measured area based on the first reference information of the gas to be measured obtained at the first center wavelength of the gas to be measured, the second reference information of the interfering gas obtained at the second center wavelength of the interfering gas and the first center wavelength, and the light receiving signals at the first center wavelength and the second center wavelength of the light to be measured received by the light receiving unit.

2. The measuring device according to claim 1, wherein The control unit modulates the wavelength of the irradiation light at a modulation frequency, The first reference information includes, as first correlation data, a first calibration curve that correlates the concentration of the gas to be measured and the intensity of the light-receiving signal having a frequency component twice the modulation frequency.

3. The measuring device according to claim 2, wherein The first reference information includes a first phase of the light reception signal of the gas to be measured.

4. The measuring device according to claim 3, wherein The second reference information includes, as second correlation data, a second calibration curve that correlates the concentration of the interfering gas and the intensity of the light-receiving signal having a frequency component twice the modulation frequency.

5. The measuring device according to claim 4, wherein The second calibration curve includes both a calibration curve at the first center wavelength and a calibration curve at the second center wavelength.

6. The measuring device according to claim 4, wherein The control unit calculates the concentration of the interfering gas by comparing a first intensity of the light reception signal of the frequency component acquired at the second central wavelength with the second calibration curve at the second central wavelength.

7. The measuring device according to claim 6, wherein The control unit compares the calculated concentration of the interfering gas with the second calibration curve at the first central wavelength to calculate a second intensity of the light reception signal of the frequency component for the interfering gas at the first central wavelength.

8. The measuring device according to claim 7, wherein The control unit calculates a fourth intensity of the light reception signal of the frequency component for the gas to be measured at the first center wavelength by removing a contribution of the second intensity from a third intensity of the light reception signal of the frequency component acquired at the first center wavelength.

9. The measuring device according to claim 8, wherein The control unit changes a calculation formula for the fourth intensity according to whether a phase of the light-receiving signal associated with the third intensity matches or does not match the first phase.

10. The measuring device according to claim 8, wherein The control unit calculates the concentration of the gas to be measured as the state of the gas to be measured by comparing the calculated fourth intensity with the first calibration curve.

11. A determination method, wherein: The determination method comprises the following steps: irradiate irradiating light; receiving light to be measured based on the irradiation light irradiated onto the area to be measured; and Based on the first reference information of the measured gas obtained at the first center wavelength of the measured gas, the second center wavelength of the interfering gas and the second reference information of the interfering gas obtained at the first center wavelength, and the received light signals at the first center wavelength and the second center wavelength of the measured light, the state of the measured gas contained in the measured area is calculated.

12. A program, wherein The program causes the measuring device to perform actions including the following steps: irradiate irradiating light; receiving light to be measured based on the irradiation light irradiated onto the area to be measured; and Based on the first reference information of the measured gas obtained at the first center wavelength of the measured gas, the second center wavelength of the interfering gas and the second reference information of the interfering gas obtained at the first center wavelength, and the received light signals at the first center wavelength and the second center wavelength of the measured light, the state of the measured gas contained in the measured area is calculated.

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