JP6364305B2 - Hydrogen gas concentration measuring apparatus and method - Google Patents

Description

  The present invention relates to a gas concentration measurement apparatus and method using Raman scattered light for measuring the concentration of a measurement target gas, and in particular, a measurement apparatus capable of measuring a hydrogen gas concentration even under the influence of laser-induced fluorescence, and Regarding the method.

  Recently, there is a demand for a technique for measuring the concentration of gas existing in a building from a remote location. There are two types of gas sensors that can measure the concentration, a contact type and a non-contact type, but there is a great need for a non-contact type sensor that requires little maintenance. Examples of the optical gas detection method include Raman scattering spectroscopy (laser Raman method).

  Here, Raman scattering is a phenomenon in which when the molecule is irradiated with monochromatic light, the frequency of the scattered light changes by the vibration frequency of the molecule, and the frequency shift amount of the scattered light is independent of the frequency of the emitted monochromatic light. This is the amount specific to the substance. Therefore, when laser light having a specific wavelength is irradiated onto a measurement target substance, Raman scattered light having a wavelength different from the wavelength of the laser light is generated from the substance hit with the laser light. Further, it is known that the intensity of the scattered light is proportional to the density of the substance.

  By the way, in an environment where hydrogen gas is used / stored, it is necessary to monitor gas leakage by installing a stationary combustible gas detector in a place where colorless, transparent, and odorless hydrogen gas stays. However, since the location of the leak was entrusted to a patrol of a staff member who carried a portable gas detector, a continuous monitoring technique for detecting the leak of the gas and identifying the leak location was required. Therefore, the applicant has proposed a number of gas detection techniques that detect non-contact without sucking the gas.

  For example, in Patent Document 1, laser light is irradiated onto a monitoring target space via an optical fiber, and Raman scattered light and background light having a wavelength that is Raman shifted from the wavelength of the irradiated laser light according to the type of the monitoring target gas. We have proposed a gas leak monitoring method and system in which the optical axes of both cameras are aligned by forming an image on the end face of the optical fiber and guiding it to a Raman scattered light compatible camera while guiding the background image to a visible light compatible camera.

  Further, in Patent Document 2, as a method for remotely measuring the gas concentration with high accuracy even when the measurement conditions are not uniform, the target space is irradiated with pulsed laser light having a pulse half width of 8 ns or less, and nitrogen gas is used. The first step of collecting the scattered light of the laser beam with a light collecting mechanism having a light receiving optical axis that intersects the laser optical axis and measuring the Raman scattered light signal intensity with the first light receiving mechanism, synchronized with the first step, A second step of irradiating the space with laser light, condensing the scattered light of the target gas with a condensing mechanism having a light receiving optical axis that intersects the laser optical axis, and measuring the Raman scattered light signal intensity with the second light receiving mechanism And a third step of calculating the concentration of the target gas in the target space based on the intensity ratio of the Raman scattered light intensity of the nitrogen gas and the target gas.

Further, in Patent Document 3, as a method of visualizing hydrogen gas using coherent anti-Stokes Raman scattering spectroscopy (CARS) that simultaneously irradiates laser light and Stokes light of hydrogen gas and captures anti-Stokes light, a space to be monitored is used. The light to be detected having a wavelength of approximately 309 nm caused by two or more different laser beams irradiated on the light is condensed, converted into an electronic image, amplified, and converted into an optical image again to image a spatial intensity distribution at a specific wavelength. A hydrogen gas and hydrogen flame monitoring method was proposed.
Note that CARS (coherent anti-Stokes Raman spectroscopy) is detailed in Non-Patent Document 1.

Japanese Patent No. 3783019 Japanese Patent No. 5159799 Japanese Patent No. 383050

M.D.Levenson, S.S.Kano; “Nonlinear Laser Spectroscopy” (first edition), Ohm, P159-182, 1989.

  However, in the measurement by the laser Raman method, the hydrogen gas concentration may not be able to be measured in the vicinity of pipes, pipe joints, pipe valves and the like due to the influence of laser-induced fluorescence.

  The method described in Patent Document 3 using CARS measures anti-Stokes light that is not affected by laser-induced fluorescence. However, the laser beam and Stokes light cannot reach at the same time, that is, in piping, packing, or piping valves. The other side of the hydrogen gas could not be detected.

When laser light and Stokes light of hydrogen gas are transmitted to a measurement location using an optical fiber, the polarization is lost during transmission, and light is randomly polarized at the exit, resulting in low generation efficiency of anti-Stokes light.
In addition, the polarization maintaining optical fiber generally has a small core diameter, and there is a problem that the coupling efficiency for introducing laser light or Stokes light into the optical fiber is low.

  Therefore, the present invention can transmit laser light and Stokes light to a desired measurement location, and also adjust the hydrogen gas concentration by CARS even under the influence of laser-induced fluorescence in the vicinity of the surface of piping, piping joints, and piping valves. An object of the present invention is to provide a measuring apparatus and method capable of measuring.

  A hydrogen gas concentration measuring device according to a first aspect of the present invention includes a laser light source that oscillates laser light for generating Raman scattered light in hydrogen gas at a measurement location, and a light receiver that detects Raman scattered light from hydrogen gas. When the laser light L1 from the laser light source is incident on one end, the Raman cell that emits the laser light and the Stokes light L2 from the other end, and the hydrogen gas at the measurement location based on the signal intensity of the Raman scattered light A control unit for calculating the concentration, a main body unit including a laser light source, a light receiver, a Raman cell, and a control unit, a probe unit installed at a measurement location, and an optical transmission path that optically connects the probe unit and the main body unit In the hydrogen gas concentration measurement apparatus comprising: the probe unit, an exit port, a convex lens that squeezes the beam diameter of the laser light and exits from the exit port to the measurement location; A plurality of mirrors comprising a positioning guide for positioning the reflector so that the reflecting object comes before the focal position of the user light, and the optical transmission path is provided with the body portion and the probe portion at the joint portion; It consists of an articulated optical transmission line that transmits laser light, Stokes light, and anti-Stokes light, and the light receiver measures the first light receiver that measures anti-Stokes light from hydrogen gas and the Stokes light from hydrogen gas. The Raman cell is arranged on the main body so as to be switchable between a first position and a second position, and the control unit is configured so that the Raman cell is on the irradiation path. At the position, the concentration of hydrogen gas is calculated based on the signal from the first light receiver, and at the second position where the Raman cell is outside the irradiation path, it is based on the signal from the second light receiver. And calculating the concentration of hydrogen gas can.

  The hydrogen gas concentration measurement method according to the first aspect of the present invention is a hydrogen gas concentration measurement method using the hydrogen gas concentration measurement device according to the first aspect, wherein the reflector that generates laser-induced fluorescence is the focal point of the laser beam. The probe unit is arranged so as to be positioned in front of the position, and the hydrogen gas concentration at the measurement location is measured.

  A hydrogen gas concentration measuring apparatus according to a second aspect of the present invention includes a laser light source that oscillates laser light for generating Raman scattered light in hydrogen gas at a measurement location, and a light receiver that detects Raman scattered light from hydrogen gas. When the laser light L1 from the laser light source is incident on one end, the Raman cell that emits the laser light and the Stokes light L2 from the other end, and the hydrogen gas at the measurement location based on the signal intensity of the Raman scattered light A control unit for calculating the concentration, a main body unit including a laser light source, a light receiver, a Raman cell, and a control unit, a probe unit installed at a measurement location, and an optical transmission path that optically connects the probe unit and the main body unit In the hydrogen gas concentration measuring apparatus, the probe unit includes an irradiation unit having a right-angle prism that irradiates the measurement site with laser light, and a llama from the measurement site. A light receiving portion having a right-angle prism for receiving scattered light, and the light transmission path emits laser light and Stokes light by a plurality of mirrors provided at the joint portion of the main body portion and the probe portion. Comprising an articulated light transmission path for transmission and an optical fiber for transmitting anti-Stokes light from hydrogen gas at a measurement location, and the light receiver comprises a light receiver for measuring anti-Stokes light from hydrogen gas, The control unit calculates the concentration of hydrogen gas based on a signal from the light receiver.

  A hydrogen gas concentration measurement method according to a second aspect of the present invention is a hydrogen gas concentration measurement method using the hydrogen gas concentration measurement device according to the second aspect, and is disposed near a reflector that generates laser-induced fluorescence. A probe unit is arranged, and the hydrogen gas concentration at the measurement location is measured.

  According to the present invention, laser light or Stokes light can be transmitted to a desired measurement location, and the hydrogen gas concentration can be measured even in a location that is affected by laser-induced fluorescence.

It is a lineblock diagram of the gas concentration measuring device concerning a 1st embodiment. It is a principal part side view explaining the arrangement | positioning relationship between a Raman cell and two lenses. It is a side view of the optical transmission line concerning a 1st embodiment. It is a principal part permeation | transmission side view of the probe which concerns on 1st Embodiment. It is a block diagram of the light receiver which concerns on 1st Embodiment. It is the figure which exaggerated and showed the condensing characteristic of the lens which concerns on 1st Embodiment. It is explanatory drawing of the measurement test of the hydrogen gas concentration which concerns on 1st Embodiment. It is a graph which shows hydrogen gas concentration and signal intensity concerning a 1st embodiment. It is a principal part permeation | transmission side view of the probe which concerns on 2nd Embodiment. It is a graph which shows the discharge | release amount and signal strength of hydrogen gas (concentration 100%) which concern on 2nd Embodiment. It is a graph which shows the discharge | release amount and signal strength of hydrogen gas (4% of density | concentration) which concern on 2nd Embodiment.

Hereinafter, the present invention will be described based on examples.
<< First Embodiment >>
The hydrogen gas concentration measuring apparatus 1 according to the first embodiment avoids the influence of laser-induced fluorescence by using CARS, enables leak detection with high sensitivity and quick response, and interaction between hydrogen molecules and light. Since hydrogen gas is detected only by this, the measurement part (20, 30) is characterized in that it does not include any electrical system.
In CARS, anti-Stokes light is generated by utilizing the polarization of molecules generated by laser light (two photons) and Stokes light (one photon). Polarization (vector) is generated in proportion to the electric field, and the magnitude of the third-order polarization by the laser beam (two-photon) and the Stokes beam (one-photon) is the electric field of the laser beam (two-photon) and the Stokes beam (one-photon). The product of For this reason, when the electric fields of the laser beam (two-photon) and the Stokes beam (one-photon) are aligned, the polarization (vector) is maximized, and the generated anti-Stokes intensity is also maximized. Further, since gas is an isotropic substance and the third-order electrical susceptibility is the same in any direction, the intensity of anti-Stokes light is determined by the magnitude of polarization. That is, by making the direction of the electric field (light polarization direction) uniform, the generation efficiency of anti-Stokes light (one photon) by laser light (two photons) and Stokes light (one photon) can be increased.

FIG. 1 is a configuration diagram of a hydrogen gas concentration measuring apparatus 1 according to the first embodiment. The measuring apparatus 1 includes a main body unit 10, an optical transmission line 20, and a probe 30 as main components.
The main body 10 includes a laser light source 11 that oscillates laser light in a pulse shape, a control unit 12 that controls each device and performs signal processing, and Stokes light (wavelength 416 nm) that is Raman scattered light having a wavelength longer than that of the laser light. Is a box that includes an optical system (Raman cell) for generating the light and a light receiver 17 that detects anti-Stokes light (wavelength 309 nm) from hydrogen gas at a measurement location.
The laser light source 11 is a single light source such as a YAG laser oscillator that oscillates laser light having a wavelength of 355 nm with an output of 1 mJ. The laser light source 11 is connected to a control unit 12 in which a dedicated control program is introduced and a signal line made up of a BNC coaxial cable or the like. Upon receiving an oscillation instruction from the control unit 12, the laser light is sent to a predetermined pulse width ( For example, oscillation occurs at 5 ns).

  The Raman cell is detachably disposed on the main body 10. When the laser light L1 from the laser light source 1 is incident on one end of the Raman cell, the laser light and the Stokes light L2 are emitted from the other end. The outgoing light L2 from the Raman cell enters the optical transmission line 20 from the light entrance of the main body 10. The Raman cell is composed of a hydrogen gas high-pressure filling cell, and includes a separate lens type in which a pair of convex lenses and a hydrogen gas high-pressure filling cell are separately provided, and a lens integrated type in which convex lenses are attached to both ends.

  In the separate lens type shown in FIG. 2A, the center of the side surface of the cylindrical hydrogen gas high-pressure filling cell 13 is concentric with the irradiation port of the laser light source 11. Lenses 14 and 15 are arranged. The lenses 14 and 15 are convex lenses having the same focal length, and are arranged with their focal positions aligned with the longitudinal center of the hydrogen gas high-pressure filling cell 13.

  In the separate lens type test example, both the lens 14 (made of quartz) and the lens 15 (made of BK7) have a focal length of 30 cm, and the length of the hydrogen gas high-pressure filling cell 13 is 47 cm. Since the focal lengths of the lens 14 and the lens 15 are the same, the beam diameter of the laser beam does not change even when the hydrogen gas high-pressure filling cell 13 is inserted or removed. The reason why the lens 15 is made of BK7 is to attenuate the anti-Stokes light generated from the hydrogen gas high-pressure filling cell 13. When a functional test was performed, the Stokes light beam was observed at a hydrogen gas filling pressure of 5 atm or higher and stabilized at 7 atm or higher.

  In the lens-integrated type shown in FIG. 2B, a lens 14 is provided at one side end of the cylindrical hydrogen gas high-pressure filling cell 13, and a lens 15 is provided at the other side end. Thus, the Raman cell may be configured by a hydrogen gas high-pressure filling cell in which the lenses 14 and 15 are fixed. The beam diameter of the laser beam does not change even if this lens integrated type or the Raman cell (13, 14, 15) is inserted or removed. In the lens-integrated test example, both the lens 14 (made of quartz) and the lens 15 (made of BK7) have a focal length of 15 cm, and the length of the hydrogen gas high-pressure filling cell 13 is 30 cm. When a functional test was performed, the Stokes light beam was observed at a hydrogen gas filling pressure of 6 atm or more and stabilized at 8 atm or more.

  In the first embodiment, the Raman cell is configured to be detachable, and the gas concentration can be measured even when the Raman cell is detached from the irradiation path. When the Raman cell is at the position (first position) removed from the irradiation path, the laser beam L1 becomes irradiation light to the measurement location A, and when the Raman cell 12 is at the position (second position) attached to the irradiation path. The laser light L2 becomes irradiation light to the measurement location A. In the above-described separate lens type, the first position including the mode in which only the hydrogen gas high-pressure filling cell 13 is removed from the irradiation path (the mode in which the lenses 14 and 15 are in the irradiation path) will be referred to.

The mirror 16 is a dichroic mirror that transmits the laser light oscillated from the laser light source 11 and reflects the anti-Stokes Raman scattering light from the measurement location A to the light receiver 17. As the mirror 16, a mirror having a high reflectance in a wavelength region including 309 nm is used in order to reliably reflect the anti-Stokes Raman scattering light from the hydrogen gas.
Between the Raman cell and the mirror 16, a long pass filter 18 that blocks light of 325 nm or less is disposed in order to block anti-Stokes light generated from the Raman cell.

The light receiver 17 includes a first light receiver 17a and a second light receiver 17b.
As shown in FIG. 5A, the first light receiver 17 a includes a filter 41, a convex lens 42, an optical fiber 43, and a spectrometer 44. The first light receiver 17a is used (at the first position) when a Raman cell is attached to the irradiation path. That is, the first light receiver 17a irradiates the measurement location A with laser light (wavelength 355 nm) and Stokes light (wavelength 416 nm) generated by the Raman cell, and reflects from the reflector R that causes laser-induced fluorescence such as piping and bulbs. Anti-Stokes reflected light (wavelength 309 nm) is received via the optical transmission line 20.
The filter 41 is composed of a short-pass filter that blocks laser light (wavelength 355 nm) and hydrogen gas Stokes light (wavelength 416 nm) and transmits anti-Stokes light (wavelength 309 nm). The convex lens 42 condenses the Stokes light received at one end of the optical fiber 43. The other end of the optical fiber 43 is connected to a spectroscope 44 having a CCD detector. The spectroscope 44 is connected to the control unit 12 by a cable (not shown).
Instead of the spectroscope, a bandpass filter that transmits anti-Stokes light (wavelength 309 nm), a photomultiplier tube that converts light into an electric signal, an avalanche photodiode, or the like may be combined.

As shown in FIG. 5B, the second light receiver 17 b includes a filter 45, a convex lens 46, and a photomultiplier tube 47. The second light receiver 17b is used (at the second position) when the Raman cell is removed from the irradiation path. That is, the second light receiver 17b is used to irradiate only the laser beam to the measurement location A and measure the Stokes light (wavelength 416 nm) from hydrogen gas. The filter 45 includes a long-pass filter (edge filter) that blocks laser light (wavelength 355 nm) and a wavelength selection filter (interference filter) that has a transmission wavelength center substantially in the Stokes light of hydrogen gas (wavelength 416 nm). Yes.
The convex lens 46 condenses the Stokes light transmitted from the measurement location A to the photomultiplier tube 47. The photomultiplier tube 47 is connected to the control unit 12 by a cable (not shown).

  Switching between the first light receiver 17a and the second light receiver 17b may be performed by providing a switching mechanism in which the machine automatically attaches / detaches the Raman cell from the irradiation path and switches between the light receivers 17a and 17b based on an operation command. It can be done manually or manually.

  The control unit 12 calculates the gas concentration based on the anti-Stokes light from the light receiver 17 or the electric signal of the Stokes light and the calibration curve, and substantially in real time on a display device (not shown) provided in the main body unit 10. indicate. As a calibration curve for calculating the gas concentration, a calibration curve prepared in advance by obtaining a correlation between the gas concentration and the Raman scattered light intensity in a gas cell filled with the observation target gas having a known concentration is used. The dedicated software of the control unit 12 can set a time interval for analysis, the number of analyzes, the number of additions of emission spectrum intensity, the average number of emission spectrum signal intensities, and a coefficient for obtaining a concentration from the signal intensity. is there.

The optical transmission path 20 is an articulated optical transmission path that transmits irradiation light (L1 or L2) from the main body 10 to the measurement location A using a plurality of mirrors. The reason why the optical transmission line 20 is not configured by an optical fiber is that, as described above, the polarization is lost during transmission, and the generation efficiency of anti-Stokes light is reduced.
In the first embodiment, as shown in FIG. 3, the optical transmission line 20 is configured by an articulated mirror. The multi-joint mirror includes an entrance port 21, seven joint portions 22a to 22g, mirrors 23a to 23g provided at the seven joint portions, an exit port 24, and cylindrical portions 25a to 25h. Is done. Irradiation light (L 1 or L 2) emitted from the main body 10 is transmitted from the emission port 24 to the probe 30 through the incident port 21, and anti-Stokes Raman scattered light from the measurement point A incident on the probe 30 is emitted from the emission port 24. Then, the light is transmitted from the entrance 21 to the main body 10.

  In 1st Embodiment, it produced by replacing the mirror of the multi-joint reflector for carbon dioxide laser scalpels used for medical purposes with the mirror for ultraviolet rays. The mirrors 23a to 23g are mirrors that reflect a wavelength of 300 to 420 nm, and the reflectance per sheet is 99% or more. By rotating the seven joints, the probe 30 connected to the emission port 24 can be arranged at an arbitrary measurement location, and the back side of an obstacle such as a pipe can be measured. Note that the number of joints and mirrors constituting the optical transmission path is not limited to the illustrated number, and may be any number (for example, 3 to 10 each).

  As shown in FIG. 4, the probe 30 according to the first embodiment includes a cylindrical body 31, a convex lens 32 provided in the body 31, a tip 33 having an emission port 34, and an attachment having an opening. A portion 35 and a positioning guide 36 are provided. The probe 30 is connected to the optical transmission line 20 by an attachment portion 35 provided at the end of the body portion 31. Irradiation light (L 1 or L 2) that has passed through the optical transmission path 20 is incident on the opening of the attachment portion 35, the beam diameter is reduced by the convex lens 32, and the light is emitted from the emission port 34 to the measurement location A. Here, it is important that the convex lens 32 functions to reduce the beam diameter of the laser light (wavelength 355 nm) and Stokes light (wavelength 416 nm) so that the beam waist of each light overlaps between the exit port and the reflector R. is there.

  A guide 36 made up of a plurality of rod-like members is provided at the emission port. The tip position of the guide 36 is set in a range between the focal position of the laser light (wavelength 355 nm) and the focal position of the anti-Stokes light (wavelength 309 nm). In order to allow the anti-Stokes light (wavelength 309 nm) emitted from the beam waist to sufficiently pass through the optical transmission line 20, it is located before the focal position of the laser beam (preferably the focal position of the anti-Stokes light). It is important to position with the positioning guide 36 so that the reflector R such as piping comes. This is because, when passing through the same lens, the focal length becomes shorter as the light has a shorter wavelength. The guide 36 is not limited to the illustrated configuration, and may be configured by, for example, a pipe with a vent hole or a wire mesh wound in a pipe shape.

  FIG. 6 is an exaggerated view showing the light collection characteristics of the lens according to the first embodiment (the tip 33 and the irradiation port 34 are not shown). As shown in the figure, since the refractive index of the substance increases as the wavelength becomes shorter, the lens focal length becomes shorter with respect to light having a shorter wavelength. For this reason, if there is an object surface (that is, a point light source with a wavelength of 309 nm) at the focal position of the anti-Stokes light (wavelength 309 nm), the light becomes a parallel light beam through the lens and can be transmitted far.

  According to the probe 30 of the first embodiment, the measurement location A is irradiated with laser light and Stokes light, and the anti-Stokes light generated from the hydrogen gas is collected, so that the gas can be contacted without sucking the hydrogen gas. It is possible to detect the concentration.

  FIG. 7 is an explanatory diagram of a hydrogen gas concentration measurement test according to the first embodiment. A probe 30 (not shown) is arranged on the left side of the drawing, and laser light and Stokes light (L2) are condensed and irradiated through a glass window 38 of a gas cell 37 filled with hydrogen gas. The anti-Stokes light L3 reflected and scattered from the aluminum plate 39 on the back surface of the gas cell 37 was measured by the probe 30. In this measurement test, the convex lens 32 of the probe 30 was made of quartz, having a diameter of 5 cm and a focal length of 10 cm.

  FIG. 8 is a graph showing the results of a measurement test in which Raman cells (13, 14, 15) are arranged in the irradiation path and anti-Stokes light is received by the first light receiver 17a. From FIG. 8, it was confirmed that there was a correlation between the hydrogen gas concentration and the signal intensity, and that the anti-Stokes light reflected from the aluminum plate could be measured through the glass window.

  According to the hydrogen gas concentration measuring apparatus 1 of the first embodiment described above, the irradiation light can be transmitted to a desired measurement location, and the laser-induced fluorescence of the vicinity of the surface of the pipe, pipe joint, pipe pipe, etc. Even under the influence, it is possible to measure the hydrogen gas concentration by CARS.

<< Second Embodiment >>
The hydrogen gas concentration measuring apparatus 1 of the second embodiment is mainly different in the optical transmission path 50 and the probe 60, and the other configuration is the same as that of the first embodiment. Below, it demonstrates centering on the point which is different from 1st Embodiment, and omits description about a common structure.

  As shown in FIG. 9, the probe 60 of the second embodiment includes an irradiation unit (61, 63, 64, 65), a light receiving unit (62, 66, 67), and a connection that fixes and fixes the irradiation unit and the light receiving unit. It is comprised including the tools 69a and 69b. The irradiation unit includes a cylindrical irradiation tube 61, a plano-convex lens 63, a mounting unit 64, and a first right-angle prism 65. The light receiving unit includes a cylindrical light receiving tube 62, a second right-angle prism 66, and a convex lens 67.

  The probe 60 is connected to the optical transmission line 50 by an attachment portion 64 provided at the end of the irradiation tube 61. Irradiation light L <b> 2 that has passed through the optical transmission path 50 is incident on the opening of the mounting portion 64, the beam diameter is reduced by the convex lens 63, and the light enters the first right-angle prism 65 from the exit. In this embodiment, the convex lens 63 and the prism 65 are made of BK7 having a low transmittance of 309 nm. In this embodiment, the convex lens 63 is a plano-convex lens, but it may be a simple convex lens.

  The light incident on the first right-angle prism 65 is incident on a second right-angle prism 66 located directly beside the first right-angle prism 65. A space between the first right-angle prism 65 and the second right-angle prism 66 is the measurement location A. In this embodiment, the prism 66 and the lens 67 are made of quartz having a high transmittance of 309 nm.

  The anti-Stokes light (wavelength 309 nm) from the measurement location A is bent 90 degrees by the second right-angle prism 66 and guided to the light receiving tube 62. The light receiving tube 62 is provided with a convex lens 67 that condenses incident light at the end of the optical fiber 68 connected to the irradiation section. The optical fiber 68 transmits the anti-Stokes light from the measurement location A to the light receiver 17.

The optical transmission path 50 of the second embodiment is an articulated optical transmission path similar to that of the first embodiment, but the optical transmission path 50 of the second embodiment is the first in that it includes an optical fiber 68 attached to the articulated optical transmission path as a light receiving optical path. It is different from the embodiment.
The main body 10 is the same as in the first embodiment, but in the second embodiment, the position of the Raman cell is not switchable, and the light receiver 17 that receives the Raman scattered light is only the light receiver 17a of the first embodiment. It differs from 1st Embodiment by the point comprised from.

FIG. 10 and FIG. 11 are graphs showing the results of a measurement test in which Raman cells (13, 14, 15) are arranged in the irradiation path and anti-Stokes light is received by the first light receiver 17a. In the measurement test of FIG. 10, hydrogen gas (concentration 100%) was discharged from the nozzle having an inner diameter of 1 mm to the measurement location A, and the anti-Stokes light was measured. In the measurement test of FIG. 11, hydrogen gas (concentration 4%, nitrogen gas dilution) was discharged from the nozzle having an inner diameter of 1 mm to the measurement location A, and the anti-Stokes light was measured.
From FIG. 10 and FIG. 11, it was confirmed that there was a correlation between the hydrogen gas flow rate and the hydrogen gas release amount and the signal intensity. It is known that the CARS signal intensity is proportional to the square of the gas density.

  According to the hydrogen gas concentration measuring apparatus 1 of the second embodiment described above, the irradiation light can be transmitted to a desired measurement location, and the laser-induced fluorescence of the vicinity of the surface of the pipe, pipe joint, pipe pipe, etc. Even under the influence, it is possible to measure the hydrogen gas concentration by CARS.

  Although some embodiments have been described in detail in the present disclosure as examples, modifications that do not substantially depart from the novel teachings and advantageous effects of the present invention are also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Main body part 11 Laser light source 12 Control part 13 Hydrogen gas high pressure filling cell 14 and 15 Convex lens 16 Dichroic mirror 17 Light receiver 18 Long pass filter 20 and 50 Optical transmission path 30 and 60 Probe 21 Entrance 22 Joint part 23 Mirror 24 Exit 25 Tube portion 31 Body portion 32 Convex lens 33 Tip portion 34 (Exit port) Convex lens 35 Mounting portion 36 Guide 41 Filter 42 Convex lens 43 Optical fiber 44 Spectrometer 45 Filter 46 Convex lens 47 Photomultiplier tube 61 Irradiation tube 62 Receptor tube 63 Planoconvex lens 64 Mounting portion 65 First right-angle prism 66 Second right-angle prism 67 Convex lens A Measurement location L1 Laser light L2 Laser light and Stokes light L3 Anti-Stokes light R Reflector

Claims (4)

A laser light source that oscillates laser light to generate Raman scattered light in hydrogen gas at the measurement location;
A receiver that detects Raman scattered light from hydrogen gas;
A Raman cell that emits laser light and Stokes light L2 from the other end when the laser light L1 from the laser light source is incident on one end;
A controller that calculates the concentration of hydrogen gas at the measurement location based on the signal intensity of the Raman scattered light;
A main body including a laser light source, a light receiver, a Raman cell, and a control unit;
A probe unit installed at a measurement location;
In a hydrogen gas concentration measuring device comprising an optical transmission line that optically connects the probe part and the main body part,
The probe unit includes an exit port, a convex lens that narrows the beam diameter of the laser beam and exits from the exit port to the measurement location, and a positioning guide that positions the reflector so that it comes closer to the focal point of the laser beam. Configured,
The optical transmission path consists of a multi-joint optical transmission path that transmits laser light, Stokes light, and anti-Stokes light by a plurality of mirrors provided at the joint portion of the main body portion and the probe portion,
The light receiver is configured to include a first light receiver that measures anti-Stokes light from hydrogen gas and a second light receiver that measures Stokes light from hydrogen gas,
In the main body, the Raman cell is disposed so as to be switchable between a first position and a second position,
The controller calculates the concentration of hydrogen gas based on a signal from the first light receiver at the first position where the Raman cell is on the irradiation path, and the second position at the second position where the Raman cell is outside the irradiation path. A hydrogen gas concentration measuring apparatus that calculates the concentration of hydrogen gas based on a signal from a photoreceiver. A hydrogen gas concentration measurement method using the hydrogen gas concentration measurement device according to claim 1,
A method for measuring a hydrogen gas concentration, comprising: arranging the probe portion so that a reflector that generates laser-induced fluorescence is positioned in front of a focal position of a laser beam, and measuring a hydrogen gas concentration at a measurement location. A laser light source that oscillates laser light to generate Raman scattered light in hydrogen gas at the measurement location;
A receiver that detects Raman scattered light from hydrogen gas;
A Raman cell that emits laser light and Stokes light L2 from the other end when the laser light L1 from the laser light source is incident on one end;
A controller that calculates the concentration of hydrogen gas at the measurement location based on the signal intensity of the Raman scattered light;
A main body including a laser light source, a light receiver, a Raman cell, and a control unit;
A probe unit installed at a measurement location;
In a hydrogen gas concentration measuring device comprising an optical transmission line that optically connects the probe part and the main body part,
The probe unit is configured to include an irradiation unit having a right-angle prism that irradiates a measurement spot with laser light, and a light-receiving unit having a right-angle prism that receives Raman scattered light from the measurement spot,
The optical transmission path includes an articulated optical transmission path for transmitting laser light and Stokes light by a plurality of mirrors provided at the joint between the main body part and the probe part, and anti-Stokes from hydrogen gas at a measurement location. An optical fiber that transmits light,
The receiver comprises a receiver that measures anti-Stokes light from hydrogen gas,
The hydrogen gas concentration measuring apparatus, wherein the control unit calculates a hydrogen gas concentration based on a signal from the light receiver. A hydrogen gas concentration measuring method using the hydrogen gas concentration measuring device according to claim 3,
A method for measuring a hydrogen gas concentration, comprising: arranging the probe unit disposed in the vicinity of a reflector that generates laser-induced fluorescence, and measuring a hydrogen gas concentration at a measurement location.