Measurement device, measurement method, and program

Abstract

To provide a measurement device capable of representing reliability of a measurement value when a state of a measured gas is measured.SOLUTION: A measurement device 1 includes: an irradiation part 10 for emitting irradiation light L; a light reception part 20 for receiving measured light ML based on the irradiation light L applied to a measured gas S by the irradiation part 10; and a control part 90 for measuring a state of the measured gas S on the basis of a light reception signal of the measured light ML received by the light reception part 20. The control part 90 calculates a measurement limit CRlimit of the state of the measured gas S on the basis of the light reception signal so as to compare a measurement value obtained in the measurement of the state of the measured gas S with the measurement limit CRlimit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a measurement device, a measurement method, and a program. [Background technology]

[0002] Conventionally, there are known techniques for measuring the state of a measurement gas, including the concentration of the measurement gas, etc. For example, Patent Document 1 discloses a gas detection device that performs stable gas detection by minimizing the influence of background light on measurement light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP2007-051894 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technique described in Patent Document 1, the reliability of the measured value when the state of the measurement target gas is measured is not fully considered.

[0005] An object of the present disclosure is to provide a measurement device, a measurement method, and a program that can indicate the reliability of a measurement value when the state of a measurement target gas is measured. [Means for solving the problem]

[0006] In some embodiments, the measuring device comprises an irradiation unit that irradiates irradiation light, a light receiving unit that receives measured light based on the irradiation light irradiated to the measured gas by the irradiation unit, and a control unit that measures the state of the measured gas based on a light receiving signal of the measured light received by the light receiving unit, and the control unit calculates a measurement limit of the state of the measured gas based on the light receiving signal and compares the measurement value obtained in measuring the state of the measured gas with the measurement limit.

[0007] This allows the measurement device to indicate the reliability of the measurement value when the state of the measured gas is measured. The measurement device evaluates the measurement result by comparing the measurement value obtained in measuring the state of the measured gas with the measurement limit. This allows the measurement device to indicate the lower limit of the measurement value when measuring the state of the measured gas. The measurement device can provide the user with a criterion for determining whether the measurement value captures the presence of the measured gas or is simply a false detection due to external disturbance. This allows the user to easily ensure the reliability of the measurement value.

[0008] In one embodiment, the control unit may calculate a first light receiving power, which is the light receiving power of the light under measurement, and a second light receiving power, which is the light receiving power of background light, based on the light receiving signal, and calculate the measurement limit based on the first light receiving power and the second light receiving power. This allows the measurement device to more clearly determine the reliability of the measurement value.

[0009] In one embodiment, the control unit may calculate the first received light power by modulating the wavelength of the irradiated light with a modulation frequency and extracting a first frequency component identical to the modulation frequency from the received light signal, thereby enabling the measurement device to easily and accurately calculate the first received light power based on phase-sensitive detection using a lock-in amplifier of the extraction unit.

[0010] In one embodiment, the control unit may calculate the second light receiving power based on a difference between an optical power corresponding to the light receiving signal and the calculated first light receiving power, which allows the measurement device to easily and accurately calculate the second light receiving power based on the phase sensitive detection using a lock-in amplifier of the extraction unit and the light receiving signal output from the light receiving unit.

[0011] In one embodiment of the measuring device, the control unit may extract a second frequency component, which is twice the modulation frequency, from the received light signal, and calculate the state of the measured gas based on the extracted second frequency component. This allows the measuring device to easily calculate the state of the measured gas, such as the column concentration of the measured gas, based on the magnitude of the second frequency component proportional to the column concentration of the measured gas. For example, the measuring device can cancel the fluctuation of the first received light power by dividing the second frequency component by the first frequency component, and more accurately obtain a value proportional to the column concentration of the measured gas.

[0012] In one embodiment of the measuring device, the control unit may determine that the reliability of the measurement value is low if the measurement value is below the calculated measurement limit, and may determine that the reliability of the measurement value is high if the measurement value is greater than the calculated measurement limit.

[0013] This enables the measurement device to determine that a measurement value equal to or less than the measurement limit does not indicate the state of the measurement gas, such as the column concentration of the measurement gas, but may indicate a false positive due to disturbance.The measurement device can also determine that a measurement value greater than the measurement limit indicates the column concentration of the measurement gas.

[0014] In one embodiment of the measuring device, the control unit may display the calculated measurement limit together with the measured value. This allows the measuring device to show the reliability of the measured value to a user via an output unit of the measuring device or the like. The user can compare the magnitude of the two values ​​and clearly understand the reliability of the measured value by displaying the measurement limit together with the measured value on a display of the output unit or the like. As a result, false detection of the state of the measured gas is reduced.

[0015] In one embodiment, the control unit may measure the state of the measurement gas based on the absorption characteristics of the measurement gas with respect to the irradiated light, so that the measurement device can accurately measure the state of the measurement gas and accurately calculate the optical absorption spectrum of the measurement gas.

[0016] In one embodiment of the measuring device, the light receiving unit may be disposed on the same side as the irradiation unit, and may receive the measured light scattered or reflected by a scatterer located behind the measured gas. This allows the measuring device to have the irradiation unit and the light receiving unit disposed on the same side of the scatterer, and to integrally configure the irradiation optical system and the light receiving optical system. Therefore, the measuring device can be configured compactly as a whole.

[0017] A measurement method in some embodiments includes irradiating irradiation light, receiving measured light based on the irradiation light irradiated to a measured gas, measuring a state of the measured gas based on a received light signal of the received measured light, calculating a measurement limit of the state of the measured gas based on the received light signal, and comparing a measurement value obtained in measuring the state of the measured gas with the measurement limit.

[0018] This allows the measurement device performing the measurement method to indicate the reliability of the measurement value when the state of the measured gas is measured. The measurement device evaluates the measurement result by comparing the measurement value obtained in measuring the state of the measured gas with the measurement limit. This allows the measurement device to indicate the lower limit of the measurement value when measuring the state of the measured gas. The measurement device can provide the user with a criterion for determining whether the measurement value captures the presence of the measured gas or is simply a false detection due to external disturbance. This allows the user to easily ensure the reliability of the measurement value.

[0019] A program in some embodiments causes a measurement device to perform operations including irradiating irradiation light, receiving measured light based on the irradiation light irradiated to a measured gas, measuring a state of the measured gas based on a reception signal of the received measured light, calculating a measurement limit of the state of the measured gas based on the reception signal, and comparing a measurement value obtained in measuring the state of the measured gas with the measurement limit.

[0020] This allows the measuring device to indicate the reliability of the measurement value when the state of the measured gas is measured. The measuring device evaluates the measurement result by comparing the measurement value obtained in measuring the state of the measured gas with the measurement limit. This allows the measuring device to indicate the lower limit of the measurement value when measuring the state of the measured gas. The measuring device can provide the user with a criterion for determining whether the measurement value captures the presence of the measured gas or is simply a false detection due to external disturbance. This allows the user to easily ensure the reliability of the measurement value. Effect of the Invention

[0021] According to the present disclosure, it is possible to provide a measurement device, a measurement method, and a program that can indicate the reliability of a measurement value when the state of a measurement target gas is measured. [Brief description of the drawings]

[0022] [Figure 1] 1 is a block diagram showing an example of a configuration of a measurement device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a conceptual diagram showing an example of the operation of the measurement device of FIG. [Diagram 3] 4 is a flowchart illustrating an example of a measurement method executed by the measurement device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The background and problems of the prior art will now be described in more detail.

[0024] Spectroscopic gas detectors using a laser as a light source have been widely known. Conventional spectroscopic gas detectors irradiate a space with a laser beam as irradiation light, and receive, as measured light, return light reflected or scattered by an object located in the background of an area where a measured gas may exist. Conventional spectroscopic gas detectors detect a measured gas based on a change in a light receiving signal output by a photodetector receiving the measured light.

[0025] In a measurement system for measuring the concentration of a measured gas, including a conventional spectroscopic gas detector, not only return light as the light to be measured but also background light such as sunlight may be incident on the photodetector. In this case, the measurement accuracy when measuring the concentration of a measured gas using a spectroscopic gas detector is affected not only by the magnitude of the light power received by the photodetector of the return light as the light to be measured, but also by noise due to background light such as sunlight.

[0026] For example, when a conventional spectroscopic gas detector measures the concentration of a gas to be measured over a wide range by spatially scanning a laser beam outdoors, the detector receives return light as the light to be measured under various conditions. The conditions include, for example, changes in the distance from a scattering medium located in the background of an area where the gas to be measured may exist to the spectroscopic gas detector, and the surface condition of the scattering medium. Therefore, the power of the light to be measured received by the conventional spectroscopic gas detector changes significantly for each measurement.

[0027] In addition, the brightness of the background light varies greatly depending on the movement of the sun and weather changes, including the effects of clouds and rain, which causes the noise level of a conventional spectroscopic gas detector to vary, i.e., the measurement limit of a conventional spectroscopic gas detector to vary.

[0028] The gas detector described in Patent Document 1 narrows the wavelength band of light incident on the light receiving section to the absorption wavelength band of the measured gas by an optical filter located on the optical path in front of the light receiving section. That is, the gas detector described in Patent Document 1 reduces the influence of background light on the light receiving section by the optical filter, reduces noise caused by the background light, and reduces the deterioration of measurement accuracy. However, the effect of removing background light using such an optical filter is limited. With the performance of a realistic optical filter, it is difficult to completely eliminate the influence of background light.

[0029] In conventional spectroscopic gas detectors including the gas detection device described in Patent Document 1, it was not easy to distinguish whether the measurement value and the fluctuation of the measurement value obtained when attempting to measure the concentration of the measured gas were caused by capturing the presence of the measured gas or caused by noise due to background light, etc. Therefore, it was not easy for users to ensure the reliability of the measurement value.

[0030] In order to solve the above problems, the present disclosure aims to provide a measuring device, a measuring method, and a program that can indicate the reliability of a measured value when the state of a gas to be measured is measured. For example, the present disclosure aims to provide a measuring device, a measuring method, and a program that can indicate the reliability of a measured value by comprehensively taking into account not only background light but also other noise components that cannot necessarily be reduced to zero, thereby indicating the measurement limit of the measured value.

[0031] An embodiment of the present disclosure will be mainly described below with reference to the accompanying drawings. The following description also applies to a measurement method and a program executed by a measurement device 1 to which the present disclosure is applied.

[0032] 1 is a block diagram showing an example of the configuration of a measurement device 1 according to an embodiment of the present disclosure. An example of the configuration and functions of the measurement device 1 according to an embodiment of the present disclosure will be mainly described with reference to FIG.

[0033] The measurement device 1 has an irradiation section 10, a light receiving section 20, a driving section 30, an extraction section 40, a modulation section 50, a storage section 60, an input section 70, an output section 80, and a control section 90.

[0034] The irradiation unit 10 has 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 a lens and a mirror that optically act on the irradiation light L emitted from the light source 11. The irradiation unit 10 guides the irradiation light L emitted from the light source 11 to the outside of the measurement device 1 via the irradiation optical system 12. The irradiation unit 10 irradiates the irradiation light L toward a space including an area where the measurement gas S exists.

[0035] In this disclosure, the "measurement gas S" includes any gas that is to be detected and measured using the measurement device 1. The irradiation unit 10 irradiates the measurement gas S with irradiation light L. The measurement gas S exists, for example, in a space between a scattering medium W and the irradiation unit 10. The scattering medium W includes background objects such as walls and piping.

[0036] The wavelength of the irradiation light L irradiated by the irradiation unit 10 is included in the light absorption band of the measurement gas S. That is, the wavelength of the irradiation light L is included in one of the light absorption wavelengths of the measurement gas S. The light absorption wavelength is included in a wavelength region such as the visible region and the infrared region.

[0037] The light receiving unit 20 has a photodetector 21 and a light receiving optical system 22. The photodetector 21 includes a light receiving element such as a photodiode (PD). The light receiving optical system 22 includes optical elements such as a lens and a mirror that optically act on light such as the measured light ML incident on the light receiving unit 20. The light receiving unit 20 guides the light such as the measured light ML incident on the light receiving unit 20 to the photodetector 21 via the light receiving optical system 22. The light receiving unit 20 receives the measured light ML based on the irradiation light L irradiated to the measured gas S by the irradiating unit 10.

[0038] In the present disclosure, the "measured light ML" is scattered light or reflected light from the scattering medium W based on the irradiated light L irradiated from the irradiating unit 10, and includes light absorbed by the measured gas S. The light receiving unit 20 receives the measured light ML that has passed through the measured gas S present in the space between the scattering medium W and the light receiving unit 20. At least a part of the wavelength band that can be received by the light receiving unit 20 is included in the light absorption band of the measured gas S. The photodetector 21 of the light receiving unit 20 has detection sensitivity at the wavelength of the measured light ML.

[0039] The light receiving unit 20 is disposed on the same side as the irradiation unit 10. More specifically, the irradiation unit 10 is disposed on the opposite side of the scattering medium W with respect to the measurement gas S so that the measurement gas S is located between the scattering medium W and the irradiation unit 10. Similarly, the light receiving unit 20 is disposed on the opposite side of the scattering medium W with respect to the measurement gas S so that the measurement gas S is located between the scattering medium W and the light receiving unit 20.

[0040] The photodetector 21 further includes an IV conversion circuit that converts a current-based light-receiving signal, which is output when the PD detects the measured light ML, into a voltage. When the photodetector 21 detects the measured light ML, it converts the current-based light-receiving signal into a voltage-based light-receiving signal and outputs it to the extraction unit 40.

[0041] 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.

[0042] 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. The circuit module includes, for example, a lock-in amplifier. The lock-in amplifier receives a voltage signal that indicates a signal waveform, such as a sine wave, that fluctuates at a predetermined frequency output from the modulation unit 50, and multiplies it by the voltage-based light receiving signal to extract the predetermined frequency component from the light receiving signal.

[0043] The modulation unit 50 includes an arbitrary circuit module that outputs a voltage signal that exhibits a predetermined signal waveform. The circuit module includes, for example, a function generator (FG). The FG outputs a voltage signal for modulating the wavelength of the irradiation light L irradiated from the irradiation unit 10 at a modulation frequency f to the driving unit 30 as a modulation signal. The FG outputs a voltage signal for extracting a predetermined frequency component from the light receiving signal based on the voltage in the extraction unit 40 as a reference signal to the extraction unit 40.

[0044] The storage unit 60 includes storage modules such as a hard disk drive (HDD), a solid state drive (SSD), an electrically erasable programmable read-only memory (EEPROM), a read-only memory (ROM), and a random access memory (RAM). The storage unit 60 stores information necessary to realize the operation of the measuring device 1. The storage unit 60 stores information obtained by the operation of the measuring device 1. For example, the storage unit 60 stores system programs, application programs, and various data acquired by any means such as communication.

[0045] The storage unit 60 may function as a main storage module, an auxiliary storage module, or a cache memory. 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 Universal Serial Bus (USB).

[0046] The input unit 70 includes one or more input interfaces that detect user input and acquire input information based on the user's operation. The input interfaces include physical keys, capacitive keys, a touch screen that is integrated with the display of the output unit 80, an imaging module such as a camera, and a microphone that accepts voice input.

[0047] The output unit 80 includes one or more output interfaces that output information to notify the user. The output interfaces include a display that outputs information as an image, a speaker that outputs information as sound, and a vibrator that outputs information as vibration. The display includes an LCD (Liquid Crystal Display) and an organic EL (Electro Luminescence) display.

[0048] The control unit 90 includes one or more processors. In the present disclosure, a "processor" refers to, but is not limited to, a general-purpose processor or a dedicated processor specialized for a specific process. The control unit 90 includes, for example, a CPU (Central Processing Unit). The control unit 90 is communicably connected to each component of the measurement device 1 and controls the operation of the measurement device 1 as a whole.

[0049] Fig. 2 is a conceptual diagram showing an example of the operation of the measurement device 1 in Fig. 1. An example of the operation realized by the measurement device 1 in Fig. 1 will be described in detail with reference to Fig. 2. In the following description using Fig. 2, the same reference numerals as those in Fig. 1 are used for the components of the measurement device 1.

[0050] The measuring device 1 operates, for example, as a spectroscopic gas detector using a light source 11. In order to detect the surrounding measured gas S, the measuring device 1 irradiates a space with laser light from the light source 11 of the irradiating unit 10 as irradiation light L. The measuring device 1 receives, using the light receiving unit 20, the measured light ML that is scattered or reflected back from a scatterer W located in the background of an area where the measured gas S may be present.

[0051] The measuring device 1 detects the measured gas S by utilizing the light absorption characteristics determined by the type of the measured gas S. The measuring device 1 operates by a method called Wavelength Modulation Spectroscopy (WMS) among laser spectroscopy. WMS is a method for acquiring the state of the measured gas S on the optical path by modulating the wavelength of a laser beam and measuring the change in the received light signal of the modulated measured light ML.

[0052] In the present disclosure, the "state of the measurement gas S" includes the concentration of the measurement gas S. The concentration of the measurement gas S is, for example, the column concentration C R Includes column concentration C R is given by the product of the optical path length when light passes through the measured gas S and the concentration of the measured gas S. R The unit is ppm·m.

[0053] The following mainly describes the contents of the processing by the control unit 90 when the measurement device 1 operates according to the WMS.

[0054] The control unit 90 controls, for example, a laser driver included in the driving unit 30. In this way, the control unit 90 sets the central wavelength λc of the laser light output from the light source 11 to the absorption wavelength of the desired measurement target gas S.

[0055] The control unit 90 controls the FG included in the modulation unit 50 to input a voltage signal fluctuating at a modulation frequency f from the modulation unit 50 to a laser driver included in the drive unit 30 as a modulation signal. The control unit 90 inputs the modulation signal from the FG to the drive unit 30, thereby modulating the wavelength of the irradiation light L irradiated 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 as the irradiation light L is modulated at a constant modulation frequency f and modulation width ΔλL around the central wavelength λc. For example, the control unit 90 modulates the wavelength of the laser light at a modulation frequency f and modulation width ΔλL around the central wavelength λc. The modulation width ΔλL is expressed in units of wavelength, not frequency, as an example.

[0056] The control unit 90 causes the light source 11 and the irradiation optical system 12 of the irradiation unit 10 to irradiate the wavelength-modulated laser light as irradiation light L toward the measurement gas S. 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 is converted into a voltage signal by the IV conversion circuit of the photodetector 21. The light receiving unit 20 outputs such a voltage signal to the extraction unit 40 as a light receiving signal.

[0057] The control unit 90 measures the state of the measurement gas S based on the light receiving signal from the light receiving unit 20. The control unit 90 extracts a second frequency component that is twice the modulation frequency f, i.e., the 2f component, from the light receiving signal, and calculates the state of the measurement gas S based on the extracted second frequency component.

[0058] For example, when the desired gas S is present in the optical path of the irradiated light L, a second frequency component having a frequency twice the modulation frequency f is generated in the measured light ML that passes through the gas S. The magnitude of the second frequency component in the received light signal is expressed as the column concentration C of the measured gas S. R Therefore, the control unit 90 extracts the second frequency component from the received light signal based on the phase-sensitive detection using the lock-in amplifier of the extraction unit 40, thereby obtaining the column concentration C R The control unit 90 obtains a voltage signal proportional to the column concentration C of the measurement target gas S by measuring the magnitude of the second frequency component. R Calculate.

[0059] At this time, the second frequency component is the column concentration C of the measurement gas S. R In the present disclosure, the "first received power" is the received power of the measured light ML at the light receiving unit 20. The first received power varies based on the distance from the scattering medium W to the measuring device 1 and the surface condition of the scattering medium W. Therefore, the control unit 90 determines the column concentration C R In order to calculate, it is necessary to remove the fluctuation caused by the first received light power from the second frequency component.

[0060] Therefore, the control unit 90 uses a first frequency component that is the same as the modulation frequency f, i.e., the 1f component. The control unit 90 acquires the magnitude of the first frequency component as well as the second frequency component by a lock-in amplifier. The magnitude of the first frequency component included in the received light signal is proportional to the first received light power. Therefore, the control unit 90 cancels the fluctuation of the first received light power by dividing the second frequency component by the first frequency component, i.e., calculating 2f component / 1f component, and thereby obtains the column concentration C of the measured gas S. R to obtain a value proportional to

[0061] As described above, the control unit 90 measures the state of the measurement gas S based on the absorption characteristics of the measurement gas S with respect to the irradiated light L. The control unit 90 measures the state of the measurement gas S based on the 1f signal and the 2f signal obtained by the lock-in amplifier of the extraction unit 40 based on the light receiving signal from the light receiving unit 20. As shown in FIG. 2, the control unit 90 calculates, for example, the column concentration C R Calculate.

[0062] In addition to the above, the control unit 90 also performs other calculation processes related to the measurement of the state of the measurement target gas S. For example, the control unit 90 determines the measurement limit C R limit The control unit 90 calculates the measurement value obtained in the measurement of the state of the measurement target gas S within the measurement limit C R limit The measurement results are evaluated by comparing them with the above.

[0063] The control unit 90 calculates a first light receiving power of the measured light ML and a second light receiving power of the background light based on the light receiving signal. In the present disclosure, the "second light receiving power" is the light receiving power of the background light in the light receiving unit 20. The control unit 90 calculates the measurement limit C R limit At this time, the control unit 90 calculates the first received light power by extracting a first frequency component, which is the same as the modulation frequency f, from the received light signal using the extraction unit 40. The control unit 90 calculates the second received light power based on the difference between the optical power corresponding to the received light signal and the calculated first received light power. In the present disclosure, the "optical power corresponding to the received light signal" is the received light power obtained by adding the received light power of the measured light ML in the light receiving unit 20 and the received light power of the background light. As shown in FIG. 2, the control unit 90 calculates the measurement limit C R limit Calculate.

[0064] The control unit 90 may, for example, set the first light receiving power to P dcThe second receiving power is P b Based on Equation 1, the measurement limit C R limit Calculate.

number

[0065] JPEG2025027356000003.jpg47170

[0066] In Equation 1, the first term on the right side is a term indicating noise that depends on each individual laser with respect to the RIN of the laser included in the light source 11. The second term on the right side is the first received light power P dc The third term on the right side is the second received power P b The control unit 90 controls the second light receiving power P b The first receiving power P dc By adding a term divided by R limit The measurement device 1 according to the embodiment calculates the second light receiving power P b This differs from the conventional technique in that a third term, which indicates noise based on the above, is added to the right-hand side for calculation.

[0067] In Equation 1, the fourth term on the right side is the dark current of the PD of the photodetector 21 and the first light receiving power P dc The fifth term on the right side is a term added in consideration of noise due to the IV conversion circuit of the photodetector 21.

[0068] As described above, the measurement limit C calculated by the control unit 90 R limit is the second received power P of the background light, as shown in the third term on the right side of Equation 1. b In addition, the measurement limit C R limit is also determined by the noise as shown in the first and fifth terms on the right hand side based on the components of the measurement device 1. Furthermore, the measurement limit CR limit is the first receiving power P dc The measurement limit C is also determined by the shot noise as shown in the fourth term on the right side of the equation. R limit corresponds to the state of the measured gas S where the S / N is equal to 1, for example, the column concentration of the measured gas S. R limit corresponds to the measurement accuracy of the column concentration of the measurement target gas S.

[0069] For example, when the measurement device 1 measures the state of the measurement target gas S over a wide range by spatially scanning the irradiated light L from the light source 11 outdoors, the first light receiving power P dc varies based on various conditions. The conditions include, for example, the distance from the scatterer W to the measurement device 1 and the surface condition of the scatterer W. In addition, the second received power P b changes depending on the brightness of the surroundings of the measuring device 1. Therefore, the measurement limit C calculated by the control unit 90 based on the formula 1 R limit changes from moment to moment even when the state of the measurement gas S is being measured.

[0070] The control unit 90 determines whether the 1f signal acquired by the lock-in amplifier of the extraction unit 40 is a first received power P dc The first received light power P dc The control unit 90 calculates the second light receiving power P b The control unit 90 calculates the first light receiving power P based on the light receiving signal and the 1f signal from the PD of the photodetector 21. dc and the second receiving power P b The two received light powers are obtained and the measurement limit C is calculated by applying Equation 1. R limit Calculate.

[0071] As shown in the function block of "measurement limit display" in FIG. 2, the control unit 90 displays the calculated measurement limit C R limitAt this time, the control unit 90 displays the measurement limit C together with the measured value obtained in measuring the state of the measurement target gas S. R limit or the calculated measurement limit C R limit may be displayed alone.

[0072] Measurement limit C based on measured light ML and background light R limit The relationship between the measurement value obtained in measuring the state of the measurement target gas S and the measurement limit C can be considered as follows. R limit For example, the control unit 90 compares the measured value obtained in measuring the state of the measurement target gas S with k·C R limit For example, the control unit 90 determines that the reliability of the measurement value is low when the measurement value is less than the column concentration C R The control unit 90 determines that the measured value obtained in measuring the state of the measurement target gas S is k·C R limit For example, the control unit 90 determines that the reliability of the measurement value is high when the measurement value is greater than the column concentration C R It is determined that the above expression indicates

[0073] k is a coefficient corresponding to the S / N. k is a value that is appropriately set by the user using the input unit 70 of the measurement device 1. When S / N=1, k=1. R limit "Compare with" means, for example, the measurement limit C when k = 1. R limit Not only can we compare it with the measured value, but also we can compare k C when k ≠ 1 R limit This also includes comparing the measured value with the measured value.

[0074] JPEG2025027356000004.jpg25170

[0075] The control unit 90 receives the measurement value obtained in measuring the state of the measurement target gas S, the measurement limit C R limit , and the measured value and k·C R limit At least one of the above-mentioned judgment contents based on the comparison with may be displayed on the display of the output unit 80. For example, the control unit 90 may display the measurement value obtained in measuring the state of the measurement target gas S, the measurement limit C R limit , and the judgment results may be displayed on the display of the output unit 80. For example, the control unit 90 may display the measurement value and the measurement limit C obtained in measuring the state of the measurement target gas S. R limit Alternatively, only the determination content may be displayed on the display of the output unit 80 without specifically displaying the above.

[0076] Fig. 3 is a flowchart for explaining an example of a measurement method executed by the measurement device 1 in Fig. 1. The example of the measurement method executed by the measurement device 1 in Fig. 1 will be mainly explained with reference to Fig. 3.

[0077] In step S101, the irradiation unit 10 of the measurement device 1 irradiates irradiation light L.

[0078] In step S102, the light receiving section 20 of the measurement device 1 receives the measured light ML based on the irradiated light L.

[0079] In step S103, the control unit 90 of the measurement device 1 measures the state of the measurement target gas S based on the light receiving signal output from the light receiving unit 20 in step S102.

[0080] In step S104, the control unit 90 of the measurement device 1 determines the measurement limit C of the state of the measurement target gas S based on the light receiving signal output from the light receiving unit 20 in step S102. R limit Calculate.

[0081] In steps S105 to S107, the control unit 90 of the measurement device 1 converts the measured value obtained in the measurement of the state of the measurement target gas S in step S103 into the measurement limit C calculated in step S104. R limit In this way, the control unit 90 of the measurement device 1 evaluates the measurement result.

[0082] In step S105, the control unit 90 of the measurement device 1 determines whether the measured value obtained in the measurement of the state of the measurement target gas S in step S103 is k·C R limit The control unit 90 determines whether the measured value is greater than k·C R limit If it is determined that the measured value is equal to or less than k·C, the process of step S107 is executed. R limit If it is determined that the difference is greater than 1, the process of step S106 is executed.

[0083] In step S106, the control unit 90 of the measurement device 1 determines whether the measured value in step S105 is k·C R limit For example, the control unit 90 determines that the reliability of the measurement value is high when the measurement value is greater than the column concentration C R It is determined that the above expression indicates

[0084] In step S107, the control unit 90 of the measurement device 1 determines whether the measured value in step S105 is k·C R limit For example, the control unit 90 determines that the reliability of the measurement value is low when the measurement value is less than the column concentration C R It is determined that there is a possibility of a false positive due to disturbance rather than a false positive.

[0085] According to the measurement device 1 of the embodiment described above, it is possible to indicate the reliability of the measured value when the state of the measurement target gas S is measured. The measurement device 1 measures the measured value obtained in measuring the state of the measurement target gas S within the measurement limit C R limitThe measurement result is evaluated by comparing it with the measured value. This allows the measurement device 1 to indicate the lower limit of the measured value when measuring the state of the measurement target gas S. The measurement device 1 can provide the user with a criterion for determining whether the measured value captures the presence of the measurement target gas S or is simply a false detection due to external disturbance. This allows the user to easily ensure the reliability of the measured value.

[0086] The measurement device 1 calculates a first received power of the measured light ML and a second received power of the background light based on the received light signal, and calculates a measurement limit C R limit This allows the measurement device 1 to more clearly ascertain the reliability of the measurement value.

[0087] For example, the first light receiving power of the measured light ML as return light from the scatterer W and the second light receiving power of other background light change while the state of the measured gas S is being measured. Therefore, noise caused by these light powers increases and decreases, affecting the measured value of the state of the measured gas S, which may result in a false detection of the measured gas S or an erroneous change in the state of the measured gas S. The measuring device 1 calculates the measurement limit C R limit By calculating the above, the reliability of the measured value can be more clearly confirmed in real time. As a result, the measurement device 1 can reduce erroneous detection of the state of the measurement target gas S.

[0088] The measurement device 1 modulates the wavelength of the irradiated light L with a modulation frequency f, and calculates the first received light power by extracting a first frequency component that is the same as the modulation frequency f from the received light signal. This allows the measurement device 1 to easily and accurately calculate the first received light power based on phase-sensitive detection using a lock-in amplifier in the extraction unit 40.

[0089] The measurement device 1 calculates the second received light power based on the difference between the optical power corresponding to the received light signal and the calculated first received light power. This allows the measurement device 1 to easily and accurately calculate the second received light power based on the phase-sensitive detection using the lock-in amplifier of the extraction unit 40 and the received light signal output from the light receiving unit 20.

[0090] The measurement device 1 extracts a second frequency component, which is twice the modulation frequency f, from the received light signal, and calculates the state of the measurement target gas S based on the extracted second frequency component. As a result, the measurement device 1 calculates the column concentration C R Based on the magnitude of the second frequency component proportional to R For example, the measurement device 1 can easily calculate the state of the measurement gas S, such as the column concentration C R It is also possible to obtain a value proportional to with greater precision.

[0091] The measuring device 1 is a measurement limit C R limit If the measurement limit C is less than the measurement limit C, the measurement device 1 determines that the reliability of the measurement value is low. R limit The measured value is equal to or less than the column concentration C of the measured gas S. R It is also possible to determine that the detected value does not indicate the state of the measurement gas S, but may indicate a false positive due to disturbance.

[0092] The measuring device 1 is a measurement limit C R limit If the measurement limit C is greater than 0, the measurement device 1 determines that the reliability of the measurement value is high. R limit The measured value is greater than the column concentration C of the measured gas S. R It is also possible to determine that the

[0093] The measuring device 1 is a device that measures the calculated measurement limit C R limitBy displaying the measurement limit C together with the measurement value, the reliability of the measurement value can be indicated to the user via the output unit 80 of the measurement device 1. The user can display the measurement limit C together with the measurement value on the display of the output unit 80, etc. R limit By displaying the value, the user can compare the two values ​​and clearly understand the reliability of the measured value. As a result, false positives regarding the state of the measured gas S are reduced.

[0094] The measurement device 1 measures the state of the measurement gas S based on the absorption characteristics of the measurement gas S with respect to the irradiated light L. This enables the measurement device 1 to accurately measure the state of the measurement gas S and accurately calculate the optical absorption spectrum of the measurement gas S.

[0095] In the measurement device 1, the light receiving unit 20 is disposed on the same side as the irradiation unit 10, and receives the measured light ML scattered or reflected by the scatterer W located behind the measurement gas S. This makes it possible for the measurement device 1 to integrally configure the irradiation optical system 12 and the light receiving optical system 22 by disposing the irradiation unit 10 and the light receiving unit 20 on the same side of the scatterer W. Therefore, the measurement device 1 can be configured to be compact as a whole.

[0096] Although the present disclosure has been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications and alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included in the scope of the present disclosure. For example, the functions included in each configuration or each step can be rearranged so as not to be logically inconsistent, and multiple configurations or steps can be combined or divided into one.

[0097] For example, a general-purpose electronic device such as a smartphone or a computer can be configured to function as a part of the measuring device 1 according to the embodiment described above. Specifically, a program describing the processing contents for realizing each function of the control unit 90 of the measuring device 1 according to the embodiment is stored in the memory of the electronic device, and the program is read and executed by a processor of the electronic device. Therefore, the present disclosure can also be realized as a program executable by a processor.

[0098] Alternatively, the present disclosure may be realized as a non-transitory computer-readable medium storing a program executable by one or more processors to cause the measurement device 1 according to one embodiment to execute each function. It should be understood that these are also included within the scope of the present disclosure.

[0099] For example, the shape, size, arrangement, orientation, and number of each of the above-mentioned components are not limited to the above description and the contents illustrated in the drawings. The shape, size, arrangement, orientation, and number of each of the components may be configured arbitrarily as long as the function can be realized. Each component of the illustrated measuring device 1 is a functional concept, and the specific form of each component is not limited to that illustrated.

[0100] For example, in the above embodiment, the measurement device 1 has the irradiation unit 10 and the drive unit 30 as different components, but is not limited to this. The measurement device 1 may have the irradiation unit 10 and the drive unit 30 together as one component. For example, the measurement device 1 may be configured such that the driver function is integrated into the irradiation unit 10, or the drive unit 30 may be configured to integrate the function of the light source 11, and irradiate the irradiation light L to the outside via an irradiation optical system 12 including a light guide member such as an optical fiber and a lens.

[0101] In the above embodiment, the measurement device 1 has the light receiving unit 20 and the extraction unit 40 as different components, but is not limited to this. The measurement device 1 may have the light receiving unit 20 and the extraction unit 40 together as a single component.

[0102] In the above embodiment, the measurement device 1 has been described as having the storage unit 60, the input unit 70, the output unit 80, and the control unit 90, but is not limited thereto. The measurement device 1 may not have these components by itself. The measurement device 1 may be communicably connected to any general-purpose electronic device, such as a PC (Personal Computer), a tablet PC, a smartphone, or a wearable device such as a smart watch, which realizes the same functions as the storage unit 60, the input unit 70, the output unit 80, and the control unit 90. The measurement device 1 may be controlled by such a general-purpose electronic device and execute various processes related to the above-mentioned measurement method while cooperating with the electronic device.

[0103] In the above embodiment, the measurement device 1 calculates the first received power of the measured light ML and the second received power of the background light based on the received light signal from the light receiving unit 20, and calculates the measurement limit C R limit However, the present invention is not limited to this. R limit may be calculated based on any other parameter that may affect the received signal instead of or in addition to the second received power of the background light. For example, the measurement limit C R limit may be calculated based on the amount of fluctuation in the first received light power of the measured light ML caused by the scatterer W vibrating at a predetermined vibration frequency.

[0104] In the above embodiment, the measurement limit C R limit Although it has been explained that the calculation is based on the above formula 1, it is not limited to this. R limit For example, the measurement limit C may be calculated based on a new formula obtained by modifying formula 1 by adding weighting coefficients to each term on the right side of formula 1 and setting the value of each coefficient to any value, including 0. R limit For example, the measurement limit C may be calculated based on a new formula derived by adding at least one new term to the right side of formula 1 or by replacing at least one term on the right side of formula 1.R limit may be calculated based on a new equation including a term based on the amount of fluctuation in the first received light power caused by the scatterer W vibrating at a predetermined vibration frequency, for example.

[0105] For example, when there are parameters whose exact values ​​cannot be obtained in advance among the multiple parameters included in the right side of Equation 1, the measurement device 1 may obtain the exact values ​​of such parameters in advance based on actual measurements. For example, the measurement device 1 may use a gas cell or the like having a known concentration of the measurement gas S as a reference. The measurement device 1 may measure changing parameters such as the first light receiving power of the measurement light ML and the second light receiving power of the background light, as well as the variation of the concentration signal, and may use the relationship between them to correct the parameters included in the right side of Equation 1 in advance.

[0106] In the above embodiment, the measurement device 1 modulates the wavelength of the irradiated light L with the modulation frequency f, and calculates the first light receiving power by extracting the first frequency component that is the same as the modulation frequency f from the light receiving signal. However, the measurement device 1 may calculate the first light receiving power by any other method. For example, the measurement device 1 may calculate the first light receiving power by using another method that does not depend on the WMS.

[0107] In the above embodiment, the measurement device 1 calculates the second received light power based on the difference between the optical power corresponding to the received light signal from the light receiving unit 20 and the calculated first received light power, but this is not limited to the above. The measurement device 1 may calculate the second received light power using any other method. For example, the measurement device 1 may calculate the second received light power using another method that does not depend on the WMS.

[0108] In the above embodiment, the measurement device 1 extracts the second frequency component, which is twice the modulation frequency f, from the received light signal, and calculates the state of the measurement gas S based on the extracted second frequency component. However, the present invention is not limited to this. The measurement device 1 may calculate the state of the measurement gas S by any other method. For example, the measurement device 1 may calculate the state of the measurement gas S by using another method that does not depend on the WMS.

[0109] In the above embodiment, the measurement device 1 divides the second frequency component by the first frequency component, i.e., calculates the 2f component / 1f component, thereby canceling the fluctuation of the first received light power and obtaining the column concentration C R However, the present invention is not limited to this. The measurement device 1 may calculate the state of the measurement target gas S by any other arithmetic expression based on the second frequency component extracted from the light receiving signal.

[0110] In the above embodiment, the measurement device 1 has been described as having a lock-in amplifier as the extraction unit 40, but is not limited to this. Instead of or in addition to the lock-in amplifier, the measurement device 1 may use software executed by the CPU of the control unit 90 or the like to achieve a function similar to that of the lock-in amplifier of the extraction unit 40. In this case, the measurement device 1 may utilize a Fourier transform.

[0111] In the above embodiment, the measurement device 1 is configured to calculate the measurement limit C R limit It has been described that the reliability of the measurement value is determined to be low if the measurement value is less than or equal to the measurement limit C , but this is not limiting. The measurement device 1 does not have to execute such a determination process by itself. For example, the measurement device 1 may evaluate the measurement result by determining the reliability of the measurement value and the measurement limit C R limit may simply be compared and displayed on the display of the output unit 80. In this case, the final decision as to whether the reliability of the measured value is low may be made subjectively by the user himself.

[0112] In the above embodiment, the measurement device 1 is configured to calculate the measurement limit C R limit However, the present invention is not limited to this. The measurement device 1 does not have to execute such a determination process by itself. For example, the measurement device 1 may evaluate the measurement result by determining the reliability of the measurement value and the measurement limit C R limit may simply be compared and displayed on the display of the output unit 80. In this case, the final decision as to whether the measurement value is reliable may be made subjectively by the user himself.

[0113] In the above embodiment, the measurement device 1 calculates the measurement limit C R limit However, the present invention is not limited to this. As described above, the measurement device 1 displays the measurement value obtained in measuring the state of the measurement gas S, the measurement limit C R limit , and the measured value and k·C R limit It is sufficient that at least one of the judgment contents based on the comparison with the measurement limit C is displayed on the display of the output unit 80. The measurement device 1 may display this information on any external device other than the measurement device 1 instead of or in addition to the display of the output unit 80. Alternatively, the measurement device 1 may display the measurement limit C R limit Calculation process, measured value and measurement limit C R limit It is also possible to perform only the evaluation process of the measurement result based on the comparison with, and it is not necessary to perform the display process of the above information, etc.

[0114] In the above embodiment, the coefficient k corresponding to the S / N is described as k=1 assuming that the S / N=1, but the present invention is not limited to this. The measurement device 1 may set the value of k to any value other than 1 depending on the application, situation, etc.

[0115] In the above embodiment, the measurement device 1 measures the state of the measurement gas S based on the absorption characteristics of the measurement gas S with respect to the irradiated light L, but is not limited to this. The measurement device 1 may measure the state of the measurement gas S based on the scattering characteristics and reflection characteristics of the measurement gas S with respect to the irradiated light L.

[0116] In the above embodiment, the light receiving unit 20 is arranged on the same side as the irradiating unit 10, and is described as receiving the measured light ML scattered or reflected by the scatterer W located behind the measured gas S, but is not limited thereto. The light receiving unit 20 may be arranged to face the irradiating unit 10 across the measured gas S. In this case, the light receiving unit 20 may receive the measured light ML obtained when the irradiation light L irradiated from the irradiating unit 10 passes through the measured gas S.

[0117] In the above embodiment, the scatterer W includes a background object such as a wall or a pipe, but is not limited thereto. The scatterer W may be any object other than a wall or a pipe.

[0118] In the above embodiment, the state of the measurement target gas S is described as including the concentration of the measurement target gas S, but is not limited thereto. The state of the measurement target gas S may include the presence or absence of the measurement target gas S itself.

[0119] Some of the embodiments of the present disclosure will be described below as examples. However, it should be noted that the embodiments of the present disclosure are not limited to these examples. [Appendix 1] An irradiation unit that irradiates irradiation light; a light receiving unit that receives light to be measured based on the irradiated light irradiated onto the gas to be measured by the irradiating unit; a control unit for measuring a state of the measurement target gas based on a light receiving signal of the measurement target light received by the light receiving unit; Equipped with The control unit calculates a measurement limit of the state of the measurement target gas based on the light receiving signal, and compares a measurement value obtained in measuring the state of the measurement target gas with the measurement limit. Measuring equipment. [Appendix 2] 2. The measurement device according to claim 1, the control unit calculates a first light receiving power that is a light receiving power of the measured light and a second light receiving power that is a light receiving power of background light based on the light receiving signal, and calculates the measurement limit based on the first light receiving power and the second light receiving power. Measuring equipment. [Appendix 3] 3. The measurement device according to claim 2, the control unit modulates a wavelength of the irradiated light at a modulation frequency, and calculates the first light receiving power by extracting a first frequency component that is the same as the modulation frequency from the light receiving signal. Measuring equipment. [Appendix 4] 4. The measurement device according to claim 3, the control unit calculates the second light receiving power based on a difference between an optical power corresponding to the light receiving signal and the calculated first light receiving power. Measuring equipment. [Appendix 5] 5. The measuring device according to claim 3 or 4, the control unit extracts a second frequency component having a frequency twice the modulation frequency from the light receiving signal, and calculates a state of the measurement target gas based on the extracted second frequency component. Measuring equipment. [Appendix 6] 6. A measuring device according to any one of claims 1 to 5, The control unit determines that the reliability of the measurement value is low when the measurement value is equal to or less than the calculated measurement limit, and determines that the reliability of the measurement value is high when the measurement value is greater than the calculated measurement limit. Measuring equipment. [Appendix 7] 7. A measuring device according to any one of claims 1 to 6, The control unit displays the calculated measurement limit together with the measurement value. Measuring equipment. [Appendix 8] 8. A measuring device according to any one of claims 1 to 7, the control unit measures a state of the measurement target gas based on an absorption characteristic of the measurement target gas with respect to the irradiated light. Measuring equipment. [Appendix 9] 9. A measuring device according to any one of claims 1 to 8, The light receiving unit is disposed on the same side as the irradiating unit, and receives the light to be measured that is scattered or reflected by a scattering body located behind the gas to be measured. Measuring equipment. [Appendix 10] Irradiating with irradiation light; receiving light to be measured based on the light irradiated onto the gas to be measured; Measuring a state of the measurement target gas based on a light reception signal of the received measurement target light; calculating a measurement limit of the state of the measurement target gas based on the light receiving signal; comparing a measurement value obtained in measuring the state of the measurement target gas with the measurement limit; Including, Measurement method. [Appendix 12] The measuring device, Irradiating with irradiation light; receiving light to be measured based on the light irradiated onto the gas to be measured; Measuring a state of the measurement target gas based on a light reception signal of the received measurement target light; calculating a measurement limit of the state of the measurement target gas based on the light receiving signal; comparing a measurement value obtained in measuring the state of the measurement target gas with the measurement limit; performing an operation including program. [Explanation of symbols]

[0120] 1. Measuring equipment 10 Irradiation unit 11 Light source 12 Irradiation optical system 20 Light receiving section 21 Photodetector 22 Light receiving optical system 30 Drive unit 40 Extraction part 50 Modulation section 60 Storage section 70 Input section 80 Output section 90 Control section f Modulation frequency C R Column Concentration C R limit Measurement Limit L irradiation light ML Measured light P b Second receiving power P dc First receiving power S Measured gas W Scatterer

Claims

1. An irradiation unit that irradiates irradiation light; a light receiving unit that receives light to be measured based on the irradiated light irradiated onto the gas to be measured by the irradiating unit; a control unit for measuring a state of the measurement target gas based on a light receiving signal of the measurement target light received by the light receiving unit; Equipped with The control unit calculates a measurement limit of the state of the measurement target gas based on the light receiving signal, and compares a measurement value obtained in measuring the state of the measurement target gas with the measurement limit. Measuring equipment.

2. 2. The measuring device according to claim 1, the control unit calculates a first light receiving power, which is a light receiving power of the measured light, and a second light receiving power, which is a light receiving power of background light, based on the light receiving signal, and calculates the measurement limit based on the first light receiving power and the second light receiving power. Measuring equipment.

3. The measuring device according to claim 2, the control unit modulates a wavelength of the irradiated light at a modulation frequency, and calculates the first light receiving power by extracting a first frequency component that is the same as the modulation frequency from the light receiving signal. Measuring equipment.

4. The measuring device according to claim 3, the control unit calculates the second light receiving power based on a difference between an optical power corresponding to the light receiving signal and the calculated first light receiving power. Measuring equipment.

5. The measuring device according to claim 3 or 4, the control unit extracts a second frequency component having a frequency twice the modulation frequency from the light receiving signal, and calculates a state of the measurement target gas based on the extracted second frequency component. Measuring equipment.

6. 5. The measuring device according to claim 1 , The control unit determines that the reliability of the measurement value is low when the measurement value is equal to or less than the calculated measurement limit, and determines that the reliability of the measurement value is high when the measurement value is greater than the calculated measurement limit. Measuring equipment.

7. 5. The measuring device according to claim 1 , The control unit displays the calculated measurement limit together with the measurement value. Measuring equipment.

8. 5. The measuring device according to claim 1 , the control unit measures a state of the measurement target gas based on an absorption characteristic of the measurement target gas with respect to the irradiated light. Measuring equipment.

9. 5. The measuring device according to claim 1 , The light receiving unit is disposed on the same side as the irradiating unit, and receives the light to be measured that is scattered or reflected by a scattering body located behind the gas to be measured. Measuring equipment.

10. Irradiating with irradiation light; receiving light to be measured based on the light irradiated onto the gas to be measured; Measuring a state of the measurement target gas based on a light reception signal of the received measurement target light; calculating a measurement limit of the state of the measurement target gas based on the light receiving signal; comparing a measurement value obtained in measuring the state of the measurement target gas with the measurement limit; Including, Measurement method.

11. The measuring device, Irradiating with irradiation light; receiving light to be measured based on the light irradiated onto the gas to be measured; Measuring a state of the measurement target gas based on a light reception signal of the received measurement target light; calculating a measurement limit of the state of the measurement target gas based on the light receiving signal; comparing a measurement value obtained in measuring the state of the measurement target gas with the measurement limit; performing an action including program.

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