Gas measurement visualization device

Abstract

To provide a gas measurement visualization apparatus which can measure and visualize the distribution of gas in a measurement area having a constant area with the dimension being equal to or greater than 10 mm almost in real time.SOLUTION: A gas measurement visualization apparatus comprises: a laser beam irradiation device 11 which emits a laser beam having an excitation wavelength of measurement object gas; a beam expander 12 which expands the diameter of the laser beam to the beam diameter with the diameter equal to or greater than 10 mm and emits the beam to the measurement area; a light receiving device 20 which receives resonance Raman scattered light from the measurement area by a light receiving part 24 having a plurality of light receiving elements that are two-dimensionally arranged; and a processing device 30 which creates image data in which the distribution of measurement object gas is visualized on the basis of the time-series data of the light receiving data of the plurality of light receiving elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas measurement visualization device that measures and visualizes a gas to be measured from a remote location. [Background technology]

[0002] Conventionally, a substance remote identification device has been disclosed that includes a laser device that irradiates a space to be irradiated with laser light, a wavelength conversion device that converts the wavelength of the laser light emitted from the laser device into a plurality of different wavelengths and emits the converted wavelengths into the space to be irradiated, a light focusing processing device that focuses and detects resonant Raman scattered light generated by resonant Raman scattering from the irradiated object, and a processing device that identifies the irradiated object based on the detection results by the light focusing processing device (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Re-tabled publication 2019 / 065828 Summary of the Invention [Problem to be solved by the invention]

[0004] The substance remote identification device described in Patent Document 1 discloses a configuration in which the diameter of the laser beam emitted from the laser device is 1 mm at the measurement location in order to increase spatial resolution. However, if the laser beam diameter is reduced in this way, when determining the gas distribution in a measurement area having a certain area (e.g., 100 mm diameter), the two-dimensional gas distribution in the measurement area can be determined by rotating the laser device slightly up, down, left, and right to repeatedly irradiate the laser beam in different directions in sequence and combining the detection results of the resonance Raman scattered light obtained when irradiating the laser beam in each direction. However, in this case, in order to detect the two-dimensional gas distribution in the measurement area, it is necessary to repeatedly rotate the laser device, irradiate the pulsed laser beam, and detect the resonance Raman scattered light (e.g., when the beam diameter is 1 mm, the above steps must be repeated 10,000 times to measure a 100 mm diameter measurement area). Therefore, the larger the measurement area, the longer the measurement time (e.g., several minutes to several tens of minutes), making it difficult to measure the two-dimensional gas distribution in the measurement area in real time. Furthermore, it was expected that obtaining a three-dimensional distribution of gas in the measurement area, including the distribution in the optical axis direction, would take even longer, making it difficult to put into practical use.

[0005] The present invention provides a gas measurement and visualization device that can measure and visualize gas distribution in a measurement area having a certain area of ​​10 mm or more in diameter almost in real time. [Means for solving the problem]

[0006] The gas measurement visualization device according to the present invention includes a laser light irradiation device that irradiates a laser light having an excitation wavelength of a gas to be measured, and a laser beam irradiated with a diameter 50The measurement system includes a beam expander that expands the beam diameter to 1 mm or more and emits it onto a measurement area, a light-receiving device that receives the resonance Raman scattered light from the measurement area with a light-receiving unit having a plurality of light-receiving elements arranged two-dimensionally, and a processing device that creates image data that visualizes the distribution of the gas to be measured based on the light-receiving data of the plurality of light-receiving elements. In the gas measurement visualization device described above, the light receiving device may have an optical filter that passes the resonance Raman scattered light scattered by the gas to be measured and blocks light of a specific wavelength that is not the wavelength of the resonance Raman scattered light scattered by the gas to be measured, and may be configured to receive the resonance Raman scattered light that has passed through the optical filter. In the gas measurement visualization device, the processing device creates three-dimensional image data that visualizes the three-dimensional distribution of the measurement target gas distributed in the arrangement direction of the multiple light-receiving elements and the optical axis direction of the laser light, based on the time series data of the light-receiving data of the multiple light-receiving elements. In the above-described gas measurement visualization device, the light-receiving unit of the light-receiving device can be configured to repeatedly receive the resonance Raman scattered light from the measurement area and output reception data of the received resonance Raman scattered light, thereby outputting time-series data of the reception data of the resonance Raman scattered light to the processing device. In the gas measurement visualization device, laser light The irradiation device can be configured to be capable of changing the pulse width of the pulsed laser light, and by changing the pulse width of the pulsed laser light, the spatial resolution in the optical axis direction of the measurement area can be adjusted. In the gas measurement visualization device, the beam expander may have a plano-concave lens and a plano-convex lens, and the beam diameter of the laser light irradiated onto the measurement area may be adjusted by changing the position of the plano-concave lens and / or the plano-convex lens in the optical axis direction. In the gas measurement visualization device, laser lightThe irradiation device may have a configuration including a laser light source and a wavelength converter that converts the laser light emitted from the laser light source into laser light having a wavelength that matches the excitation wavelength of the gas to be measured. In the gas measurement visualization device, the processing device may be configured to have a function of detecting a measurement target gas leaking from an inspection target placed on the optical axis of the laser light and visualizing the leakage position of the measurement target gas. [Effects of the Invention]

[0007] According to the present invention, it is possible to measure and visualize the distribution of a specific gas almost in real time even in a measurement area having a predetermined area of ​​10 mm or more in diameter. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing a gas measurement visualization device according to an embodiment of the present invention. [Figure 2] 10A and 10B are diagrams for explaining a test method for a gas measurement test using the gas measurement visualization device according to the present embodiment. [Figure 3] FIG. 3 is a diagram showing an example of a two-dimensional distribution image of the measurement target gas obtained in the gas measurement test shown in FIG. 2 (part 1). [Figure 4] FIG. 3 is a diagram showing an example of a two-dimensional distribution image of the measurement target gas obtained in the gas measurement test shown in FIG. 2 (part 2). [Figure 5] FIG. 1 is a diagram for explaining a method for creating a three-dimensional distribution image of a gas to be measured (part 1). [Figure 6] FIG. 10 is a diagram for explaining a method for creating a three-dimensional distribution image of a gas to be measured (part 2). [Figure 7] 10 is a diagram for explaining the relationship between the pulse width of a pulsed laser beam and the spatial resolution of a gas to be measured in the optical axis direction. FIG. [Figure 8] FIG. 2 is a diagram for explaining a measurement area according to the present embodiment. [Figure 9] FIG. 1 is a diagram showing a two-dimensional distribution image of sulfur dioxide (SO2) gas captured in this embodiment. [Figure 10] FIG. 1 is a diagram showing an example of a three-dimensional distribution image of sulfur dioxide (SO2) gas created based on the two-dimensional distribution image captured in this embodiment. [Figure 11] FIG. 10 is a diagram showing an image of nitric oxide (NO) gas captured in a configuration similar to that of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The gas measurement visualization device 1 according to this embodiment will be described below with reference to the drawings. In this embodiment, a configuration for measuring sulfur dioxide (SO2) gas as the measurement target gas will be described as an example; however, in the present invention, the measurement target gas is not limited to sulfur dioxide (SO2) gas, and gases such as CO2, O2, CO, N2, H2S, CH4, NH3, and H2 can also be measured. Furthermore, in this embodiment, a gas measurement visualization device 1 that measures and visualizes the concentration of a gas will be described as an example; however, the present invention is not limited to devices that measure and visualize the concentration of a gas, and can also be applied, for example, as a gas identification device that identifies a gas present in a measurement target area, or a monitoring device that monitors whether a measurement target gas is present in a measurement target area.

[0010] FIG. 1 is a configuration diagram showing a gas measurement visualization device 1 according to this embodiment. As shown in FIG. 1, the gas measurement visualization device 1 according to this embodiment includes an irradiation device 10, a light receiving device 20, and a processing device 30. Each component will be described below. In the example shown in FIG. 1, sulfur dioxide (SO2) gas is emitted from a gas outlet of a gas cell, and the sulfur dioxide (SO2) gas is measured and visualized using the area around the gas outlet of the sulfur dioxide (SO2) gas as a measurement area. In addition, in this embodiment, a configuration in which the irradiation device 10 and the light receiving device 20 are provided as independent devices is illustrated. However, the present invention is not limited to this. For example, the irradiation device 10 and the light receiving device 20 can also be used as an integrated device, such as a flash-type LIDAR (Light Detection and Ranging).

[0011] As shown in FIG. 1 , the irradiation device 10 includes a wavelength-tunable laser 11 and a beam expander 12. The wavelength-tunable laser 11 can include, for example, an Nd:YAG laser as a laser light source and an optical parametric oscillator (OPO). In this case, the wavelength-tunable laser 11 can output, for example, a laser beam having a wavelength of 1064 nm at a repetition rate of 10 Hz to several kHz using the Nd:YAG laser. The optical parametric oscillator can convert the laser beam emitted by the Nd:YAG laser to a wavelength of, for example, 200 nm to 1000 nm and output the converted laser beam to the beam expander 12. The wavelength-tunable laser 11 can also include a second harmonic generator or a third harmonic generator, as necessary. In this embodiment, the wavelength-tunable laser 11 can be a quasi-pulse laser, a Q-switched laser, a mode-locked laser, or the like, and can emit pulsed laser beams having a pulse width of several nanoseconds to several milliseconds.

[0012] 1, the beam expander 12 has a plano-concave lens 121 and a plano-convex lens 122, and can change the laser diameter of the pulsed laser beam emitted from the wavelength-tunable laser 11 using the plano-concave lens 121 and the plano-convex lens 122. Specifically, the plano-concave lens 121 diverges the pulsed laser beam emitted from the wavelength-tunable laser 11 so that the beam diameter of the pulsed laser beam expands, and the plano-convex lens 122 returns the pulsed laser beam diverged by the plano-concave lens 121 to a parallel beam. In this embodiment, the beam expander 12 can expand the beam diameter of the pulsed laser beam emitted from the wavelength-tunable laser 11 to a diameter of 10 mm or more, preferably 50 mm or more, and more preferably 100 mm or more in the measurement area. For example, the beam expander 12 can shift the position of the plano-concave lens 121 and / or the plano-convex lens 122 in the optical axis direction based on the control of the processing device 30, and by adjusting the position of the plano-concave lens 121 and / or the plano-convex lens 122 in the optical axis direction, the beam diameter of the pulsed laser light emitted by the wavelength-tunable laser 11 can be freely changed within a certain range.

[0013] Furthermore, in this embodiment, the irradiation device 10 can irradiate a pulsed laser beam having an excitation wavelength of the gas to be measured under the control of the processing device 30. For example, when the gas to be measured is sulfur dioxide (SO2) gas, the irradiation device 10 can irradiate a pulsed laser beam of 210 to 230 nm by controlling the tunable laser 11 to irradiate the gas with a pulsed laser beam of 210 to 230 nm, which causes the sulfur dioxide (SO2) gas to generate resonant Raman scattered light. In this embodiment, as shown in FIG. 1, a beam diffuser is disposed so that the pulsed laser beam irradiated from the irradiation device 10 terminates after passing through the measurement area.

[0014] The light-receiving device 20 has a light-receiving unit 24 that receives the resonance Raman scattered light from the measurement area and outputs a signal (light-receiving data) corresponding to the intensity of the resonance Raman scattered light received by the light-receiving unit 24 to the processing device 30. Specifically, as shown in FIG. 1, the light-receiving device 20 has a bandpass filter 21, an ultraviolet imaging lens 22, an edge filter 23, and the light-receiving unit 24. The bandpass filter 21 passes light in a predetermined wavelength range (for example, in this embodiment, light around 222.5 nm, which is the wavelength of the resonance Raman scattered light scattered by sulfur dioxide (SO2) gas) and blocks all or part of other light. The ultraviolet imaging lens 22 is a lens with high transmittance for light in the ultraviolet range, and is suitable for light around 222.5 nm, which is the wavelength of the resonance Raman scattered light corresponding to sulfur dioxide (SO2) gas, for example. Furthermore, the edge filter 23 is a filter that blocks light of wavelengths longer than the target wavelength (for example, 218 nm in this embodiment), and can block noise light of long wavelengths that has passed through the bandpass filter 21. As described above, in this embodiment, the light receiving device 20 includes the bandpass filter 21, the ultraviolet imaging lens 22, and the edge filter 23, and thus can detect light of the target wavelength (for example, in this embodiment, light of wavelengths around 210 to 230 nm corresponding to the resonant Raman scattering light of sulfur dioxide (SO2) gas) with high accuracy (high S / N ratio). Note that these configurations can be appropriately changed depending on the gas to be measured. Furthermore, in order to simplify the configuration of the light receiving device 20, it is also possible to configure it without the bandpass filter 21, the ultraviolet imaging lens 22, and / or the edge filter 23.

[0015] The light receiving unit 24 receives resonance Raman scattered light generated when the pulsed laser light irradiated by the irradiating device 10 collides with the target gas in the measurement area. The light receiving unit 24 has a plurality of light receiving elements arranged two-dimensionally, and receives signal data corresponding to the intensity of the resonance Raman scattered light corresponding to each position within the imaging range of the light receiving unit 24 from the light receiving elements corresponding to each position in the imaging range, and outputs the signal data as two-dimensional data to the processing device 30. The light receiving device 20 is set so that its focus is at infinity. For example, an ICCD detector can be used as the light receiving unit 24, and a process of receiving light in units of picoseconds to microseconds using an electronic shutter and outputting light reception data corresponding to the amount of received light to the processing device 30 can be repeated.

[0016] The processing device 30 receives two-dimensional data corresponding to the intensity of the resonance Raman scattered light output by the light-receiving device 20. Here, the intensity of the resonance Raman scattered light at each position in the measurement area indicates the two-dimensional distribution of the measurement target gas in the arrangement direction of the multiple light-receiving elements, and the processing device 30 generates two-dimensional distribution image data indicating the two-dimensional distribution of the measurement target gas based on the two-dimensional data. Furthermore, the processing device 30 has a display, and this display displays a two-dimensional distribution image that visualizes the two-dimensional distribution of the measurement target gas based on the generated two-dimensional distribution image data of the measurement target gas. Here, FIG. 2 is a diagram for explaining a test method for a gas measurement test using the gas measurement visualization device 1 according to this embodiment, and FIGS. 3 and 4 are diagrams showing examples of two-dimensional distribution images of the measurement target gas obtained in the gas measurement test shown in FIG. 2.

[0017] In the test example shown in FIG. 2, pulsed laser light of 217 nm, which is the excitation wavelength of sulfur dioxide gas (SO2), was irradiated by the irradiation device 10 onto the measurement area between the gas outlet of the gas cell and the duct for discharging the gas. Simultaneously with the irradiation of the pulsed laser light, 20 ppm of sulfur dioxide (SO2) gas was released from the gas outlet of the gas cell. The energy of the pulsed laser light was set to 0.5 mJ. Furthermore, although not shown in FIG. 2, the light-receiving device 20 was configured to receive resonant Raman scattered light (more specifically, light with a wavelength of 222 nm) from the measurement area using the light-receiving unit 24, and two-dimensional data corresponding to the light intensity of the received resonant Raman scattered light was output to the processing device 30.

[0018] For example, Fig. 3 is a two-dimensional distribution image of the target gas based on the measurement results when the beam diameter of the pulsed laser light irradiated by the irradiation device 10 is expanded to a diameter of 50 mm in the measurement area in the test example shown in Fig. 2. Fig. 4 is a two-dimensional distribution image of the target gas based on the measurement results when the beam diameter of the pulsed laser light irradiated by the irradiation device 10 is expanded to a diameter of 100 mm in the measurement area in the test example shown in Fig. 2. As shown in Figs. 3 and 4, the processing device 30 creates two-dimensional distribution image data of the target gas from two-dimensional data corresponding to the light intensity of the resonant Raman scattered light received by the light-receiving device 20. That is, as shown in Figs. 3 and 4, the processing device 30 creates image data showing the two-dimensional distribution of the target gas on the image plane (a plane perpendicular to the optical axis of the pulsed laser light) as two-dimensional distribution image data of the target gas. In particular, in this embodiment, two-dimensional distribution image data of the target gas can be created in real time by acquiring, as two-dimensional data, received light data of resonance Raman scattered light received at the same time by a plurality of light-receiving elements arranged two-dimensionally in the light-receiving unit 24. Furthermore, in this embodiment, the processing device 30 creates the two-dimensional distribution image data so that each pixel of the two-dimensional distribution image can be colored bluer as the light intensity of the resonance Raman scattered light decreases and redder as the light intensity of the resonance Raman scattered light increases. This allows a user viewing the two-dimensional distribution image to intuitively grasp the location of the target gas and the concentration of the target gas, as shown in FIGS. 3 and 4 .

[0019] In the test examples shown in Figures 3 and 4, a trace amount of sulfur dioxide (SO2) gas of 20 ppm was released from the gas cell, but sulfur dioxide gas (SO2) could be properly detected even when the beam diameter of the pulsed laser light was set to 50 mm in the measurement area, as in the test example shown in Figure 3. Furthermore, as shown in Figure 4, even when the beam diameter of the pulsed laser light was expanded to 100 mm in the measurement area, although noise increased compared to Figure 3, it was found that 20 ppm of sulfur dioxide (SO2) gas could be detected.

[0020] Furthermore, in this embodiment, the processing device 30 can generate three-dimensional distribution image data of the target gas distributed in the measurement area along the arrangement direction of the multiple light-receiving elements and the optical axis direction of the pulsed laser light in almost real time based on the time-series data of the two-dimensional data of the resonance Raman scattered light acquired from the light-receiving device 20, and can also display a three-dimensional distribution image based on the three-dimensional distribution image data. Here, FIG. 5 is a diagram for explaining a three-dimensional distribution image of the target gas. For example, as shown in FIG. 5(A), when the pulsed laser light irradiated from the irradiation device 10 travels through a space S1 in the measurement area, the pulsed laser light collides with the target gas present in the space S1, generating resonance Raman scattered light R1 due to the target gas in the space S1. Furthermore, as shown in FIG. 5(B), when the pulsed laser light travels to a space S2, the pulsed laser light collides with the target gas present in the space S2, generating resonance Raman scattered light R2. Note that part of the resonance Raman scattered light R1 generated in Fig. 5(A) travels toward the light-receiving device 20, but is not received by the light-receiving device 20 at the timing shown in Fig. 5(B). However, thereafter, the resonance Raman scattered light R1 and the resonance Raman scattered light R2 are sequentially received by the light-receiving device 20 at different timings, and two-dimensional data corresponding to the intensities of the received resonance Raman scattered light R1 and resonance Raman scattered light R2 are output to the processing device 30 in chronological order.

[0021] 6, like FIG. 5, is a diagram illustrating time-series data of two-dimensional data of resonance Raman scattering light. In the example shown in FIG. 6, the irradiation device 10 irradiates a measurement area with pulsed laser light, which reaches the measurement area at time n. The resonance Raman scattering light generated when the pulsed laser light travels between time n and time n+1 is received by the light-receiving device 20 between time n+2 and time n+3. In this case, the light-receiving device 20 outputs two-dimensional data corresponding to the intensity of the resonance Raman scattering light received between time n and time n+1 to the processing device 30 at time n+3, and also outputs two-dimensional data corresponding to the intensity of the resonance Raman scattering light received between time n+1 and time n+2 to the processing device 30 at time n+4. Similarly, the light-receiving device 20 repeatedly outputs two-dimensional data corresponding to the intensity of the resonance Raman scattering light received for a certain period of time, such as between time n+2 and time n+3 and between time n+3 and time n+4, to the processing device 30. This enables the processing device 30 to acquire time-series data of two-dimensional data corresponding to the intensity of the resonance Raman scattered light, such as two-dimensional data corresponding to the intensity of the resonance Raman scattered light when the pulsed laser light progresses from time n to time n+1, and two-dimensional data corresponding to the intensity of the resonance Raman scattered light when the pulsed laser light progresses from time n+1 to time n+2. The processing device 30 can then generate a three-dimensional distribution image of the measurement target gas, including the optical axis direction of the pulsed laser light, by combining, in the optical axis direction of the pulsed laser light, the two-dimensional data corresponding to the intensity of the resonance Raman scattered light when the pulsed laser light progresses from time n to time n+1, the two-dimensional data corresponding to the intensity of the resonance Raman scattered light when the pulsed laser light progresses from time n+1 to time n+2, and the two-dimensional data corresponding to the intensity of the resonance Raman scattered light received for a certain period of time thereafter.

[0022] Furthermore, in this embodiment, shortening the pulse width (irradiation time) of the pulsed laser beam makes it possible to increase the spatial resolution in the optical axis direction of the pulsed laser beam. Here, FIG. 7 is a diagram illustrating the relationship between the pulse width of the pulsed laser beam and the spatial resolution in the optical axis direction of the pulsed laser beam. For example, in the example shown in FIG. 7(A), the irradiation device 10 of the processing device 30 irradiates a pulsed laser beam having a pulse width W1, and in the example shown in FIG. 7(B), the irradiation device 10 irradiates a pulsed laser beam having a pulse width W2. As a result, in the example shown in FIG. 7(A), the spatial resolution in the optical axis direction of the pulsed laser beam is W1, but in the example shown in FIG. 7(B), the spatial resolution in the optical axis direction of the pulsed laser beam is W2, resulting in a higher spatial resolution in the optical axis direction of the pulsed laser beam than in the example shown in FIG. 7(A). [Example]

[0023] Next, with reference to FIGS. 8 to 10, an example of the gas measurement visualization device 1 according to this embodiment will be described. In this example, 200 ppm of sulfur dioxide (SO2) gas emitted from a 40 × 10 mm gas outlet was measured using the gas measurement visualization device 1 shown in FIG. 1. Specifically, laser light with an excitation wavelength of 217 nm was irradiated from the irradiation device 10 toward the upper side of the gas cell with an excitation energy of 2 mJ, and Raman scattered light with an observation wavelength of 222.6 nm coming from the gas cell was received. In this example, the laser light was irradiated so that the beam diameter in the measurement area was 250 mm, and the region included in the beam diameter was used as the measurement area to receive Raman scattered light. FIG. 8 is a diagram illustrating the measurement area in this example. In this example, the distance from the irradiation device 10 to the gas cell and the distance from the gas cell to the light receiving device 20 were 2 m. Furthermore, the timing (delay time) from the oscillation of the laser light to the opening of the gate of the light-receiving element of the light-receiving unit 24 was changed in increments of several nanoseconds from 96 to 112 nanoseconds, which corresponds to the measurement area in the optical axis direction of the gas outlet (enables reception of Raman scattered light from a predetermined region in the optical axis direction, including above the gas outlet), and images were captured (see Figure 9, described below). Note that the "96 nanoseconds" mentioned above, which corresponds to the start point of the measurement area in the optical axis direction, is a value determined by the device configuration (e.g., the distance to the gas outlet and the length of the signal cable) and may need to be changed appropriately depending on the device configuration. In addition, in this example, the 16-nanosecond range from 96 to 112 nanoseconds corresponds to a distance of approximately 2.4 m. Repeated imaging every 2 to 4 nanoseconds corresponds to imaging the above section at intervals of approximately 30 to 60 cm (distance is calculated by multiplying the time by the speed of light by 2, considering the round trip of light).

[0024] Figure 9 shows two-dimensional distribution images of sulfur dioxide (SO2) gas captured in this example. Specifically, Figure 9(A) is an image captured 96 nanoseconds after laser light irradiation, Figure 9(B) is an image captured 100 nanoseconds after laser light irradiation, Figure 9(C) is an image captured 102 nanoseconds after laser light irradiation, Figure 9(D) is an image captured 105 nanoseconds after laser light irradiation, Figure 9(E) is an image captured 108 nanoseconds after laser light irradiation, and Figure 9(F) is an image captured 112 nanoseconds after laser light irradiation. If the imaging position of the image captured after 96 nanoseconds shown in Figure 9(A) is 0 cm (the reference position of the measurement area), the imaging position of the image captured after 100 nanoseconds shown in Figure 9(B) is 60 cm from the reference position along the optical axis of the measurement area, the imaging position of the image captured after 102 nanoseconds shown in Figure 9(C) is 90 cm from the reference position along the optical axis, the imaging position of the image captured after 105 nanoseconds shown in Figure 9(D) is 135 cm from the reference position along the optical axis, the imaging position of the image captured after 108 nanoseconds shown in Figure 9(E) is 180 cm from the reference position along the optical axis, and the imaging position of the image captured after 112 nanoseconds shown in Figure 9(F) is 240 cm from the reference position along the optical axis. Therefore, by arranging these images according to their distance from the reference position and combining them, as shown in Figure 10, a three-dimensional image of sulfur dioxide (SO2) gas can be obtained. FIG. 10 is a diagram showing an example of a three-dimensional distribution image of sulfur dioxide (SO2) gas created based on the two-dimensional distribution image data obtained in this example.

[0025] 11 is a diagram showing an image of nitric oxide (NO) gas captured in a configuration similar to that of the above-described embodiment. As shown in FIG. 11, when detecting nitric oxide (NO) gas, the gas measurement visualization device 1 can capture a two-dimensional distribution image in the same way as for sulfur dioxide (SO2) gas, and can create a three-dimensional distribution image of nitric oxide (NO) gas from two-dimensional distribution image data captured at different times.

[0026] As described above, the gas measurement visualization device 1 according to this embodiment includes an irradiation device 10 that irradiates a measurement area with laser light having a beam diameter of 10 mm or more, a light-receiving device 20 that receives resonance Raman scattered light from the measurement area using a light-receiving unit 24 having a plurality of light-receiving elements arranged two-dimensionally, and measures the gas present in the measurement area based on two-dimensional data based on the intensity of the resonance Raman scattered light received at the same time by the plurality of light-receiving elements, thereby enabling real-time acquisition and visualization of two-dimensional distribution data of the target gas simultaneously present in the measurement area. That is, in the past, a raster scan method was used to measure the two-dimensional distribution of the target gas in the measurement area by irradiating each position in the measurement area with pulsed laser light, receiving Raman scattered light from the irradiated positions, and then changing the irradiation position and repeating the irradiation of pulsed laser light and receiving Raman scattered light again. However, in conventional methods, the irradiation of pulsed laser light and the reception of Raman scattered light must be repeated, and when the measurement area is large, it can take several minutes to several tens of minutes to measure the two-dimensional distribution of the target gas over the entire measurement area, making it impossible to measure the two-dimensional distribution of the target gas in real time. In contrast, the gas measurement visualization device 1 according to this embodiment irradiates the measurement area with laser light having a beam diameter of 10 mm or more and receives the resonant Raman scattered light from the measurement area with a light-receiving unit 24 having a plurality of light-receiving elements arranged two-dimensionally, thereby obtaining two-dimensional data corresponding to the concentration of the target gas present in the measurement area in real time and displaying a two-dimensional distribution image of the target gas in real time.

[0027] Furthermore, when measuring the concentration of a gas present in a measurement area by irradiating the target with pulsed laser light over a wide range to achieve a beam diameter of 10 mm or more and receiving Raman scattered light from the measurement area, there has been a problem in that, as shown in Figures 3 and 4, if the concentration of the target gas is low, Raman scattered light of sufficient intensity cannot be detected, making it impossible to measure the target gas. In contrast, the gas measurement visualization device 1 according to this embodiment is configured to irradiate the target with pulsed laser light having an excitation wavelength of the target gas and receive resonance Raman scattered light corresponding to the target gas. Because resonance Raman scattered light is 10,000 to 1,000,000 times more intense than Raman scattered light, it is possible to measure a target gas at a lower concentration than conventional methods, even when irradiating the target with pulsed laser light over a wide range.

[0028] Furthermore, in the gas measurement visualization device 1 according to this embodiment, the light receiving device 20 has optical filters 21-23 that pass the resonance Raman scattered light scattered by the gas to be measured and block light of specific wavelengths other than the wavelength of the resonance Raman scattered light scattered by the gas to be measured, thereby making it possible to remove light of wavelengths other than the resonance Raman scattered light as noise and improving the accuracy of detection of the gas to be measured based on the resonance Raman scattered light. Also, in the gas measurement visualization device 1 according to this embodiment, the irradiation device 10 has a beam expander 12 that expands the beam diameter of the laser light, and the beam diameter of the laser light irradiated onto the measurement area can be adjusted by adjusting the position of, for example, the plano-concave lens 121 and / or the plano-convex lens 122.

[0029] In addition, in this embodiment, the light receiving unit 24 of the light receiving device 20 repeatedly receives resonance Raman scattered light from the measurement area and outputs reception data of the received resonance Raman scattered light, thereby outputting time-series data of the reception data of the resonance Raman scattered light to the processing device 30, and the processing device 30 can create three-dimensional distribution image data of the measurement target gas distributed in the optical axis direction of the laser light in the measurement area in almost real time based on the time-series data of the reception data of the resonance Raman scattered light. Furthermore, the irradiation device 10 is capable of changing the pulse width of the pulsed laser light, and by changing the pulse width of the pulsed laser light, the spatial resolution in the optical axis direction of the measurement area can be adjusted.

[0030] Although the above description has been given using an example of the gas measurement visualization device 1 that measures a measurement target gas, an inspection device can also be configured using such a gas measurement visualization device 1. For example, when inspecting a product having a pipe through which gas passes for gas leaks, the location and extent of the gas leak can be displayed as a two-dimensional or three-dimensional distribution image of the measurement target gas by measuring the gas using the gas measurement visualization device 1. Note that such a two-dimensional or three-dimensional distribution image may be displayed by superimposing the two-dimensional or three-dimensional distribution image of the gas on a separately captured image of the product.

[0031] Although the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments, and such modifications and improvements are also included in the technical scope of the present invention.

[0032] For example, in addition to the above-described embodiment, the further the pulsed laser light travels in the optical axis direction, the more attenuated the pulsed laser light is, and therefore, even if the concentration of the gas to be measured is the same, the intensity of the resonance Raman scattered light decreases at a more distant position (the further the pulsed laser light travels in the optical axis direction). Therefore, a configuration may be adopted in which the received light data is corrected so that the intensity of the resonance Raman scattered light increases at positions in the measurement area that are farther away from the irradiation device 10 (or the farther away from the light-receiving device 20).

[0033] The beam diameter can also be expanded to a diameter of more than 100 mm. Conversely, in order to measure trace components with high sensitivity, the beam diameter can be reduced to visualize them. That is, the gas measurement visualization device 1 according to this embodiment can freely expand or contract the beam diameter within a diameter range of 10 mm or more. Furthermore, when scanning with a wider beam diameter, the intensity of the resonant Raman scattered light is correspondingly weakened, and there is a possibility that the gas to be measured cannot be detected. In such a case, the number of scans can be increased to combine the received light data, the light receiving time can be extended, or the energy of the pulsed laser light can be increased. [Explanation of symbols]

[0034] 1...Gas measurement visualization device 10…Irradiation device 11...Tunable wavelength laser 12...Beam expander 121...Plano-concave lens 122...Plano-convex lens 20…Light receiving device 21...Bandpass filter 22...Ultraviolet photography lens 23...Edge filter 24...Light receiving section 30...Processing equipment

Claims

1. a laser light irradiation device that irradiates a laser light having an excitation wavelength of the measurement target gas; a beam expander that expands the laser light to a beam diameter of 50 mm or more and emits the laser light to a measurement area; a light-receiving device that receives the resonant Raman scattered light from the measurement area with a light-receiving unit having a plurality of light-receiving elements arranged two-dimensionally; a processing device that creates image data that visualizes the distribution of the gas to be measured based on time-series data of the light-receiving data from the plurality of light-receiving elements.

2. 2. The gas measurement visualization device according to claim 1, wherein the light receiving device has an optical filter that passes the resonance Raman scattered light scattered by the measurement target gas and blocks light of a specific wavelength other than the wavelength of the resonance Raman scattered light scattered by the measurement target gas, and receives the resonance Raman scattered light that has passed through the optical filter.

3. 3. The gas measurement visualization device according to claim 1, wherein the processing device creates three-dimensional image data that visualizes a three-dimensional distribution of the measurement target gas distributed in the arrangement direction of the plurality of light-receiving elements and the optical axis direction of the laser light, based on time-series data of the light-receiving data of the plurality of light-receiving elements.

4. 4. The gas measurement visualization device according to claim 3, wherein the light receiving unit of the light receiving device repeatedly receives the resonance Raman scattered light from the measurement area and outputs reception data of the received resonance Raman scattered light, thereby outputting time-series data of the reception data of the resonance Raman scattered light to the processing device.

5. 5. The gas measurement visualization device according to claim 4, wherein the laser light irradiation device is capable of changing a pulse width of the pulsed laser light, and by changing the pulse width of the pulsed laser light, a spatial resolution in an optical axis direction of the measurement area can be adjusted.

6. 6. The gas measurement visualization device according to claim 1, wherein the beam expander has a plano-concave lens and a plano-convex lens, and the beam diameter of the laser light irradiated onto the measurement area can be adjusted by changing the position of the plano-concave lens and / or the plano-convex lens in the optical axis direction.

7. 7. The gas measurement visualization device according to claim 1, wherein the laser light irradiation device comprises a laser light source and a wavelength converter that converts the laser light emitted from the laser light source into laser light having a wavelength that matches the excitation wavelength of the gas to be measured.

8. 8. The gas measurement visualization device according to claim 1, wherein the processing device has a function of detecting a measurement target gas leaking from an inspection target placed on the optical axis of the laser light and visualizing the leakage position of the measurement target gas.

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