Gas Sensing Equipment

Abstract

The present invention relates to a gas sensing device. A gas sensing element reflects light incident along an optical path on a sensing surface. The characteristics of the light reflected by the gas sensing element vary depending on the amount of a specific gas in contact with the gas sensing element. Each of a first optical element and a second optical element bends the optical path. The gas sensing element, a light source, a light detector, and a magnetic field applicator are arranged on the same side relative to a virtual plane, the virtual plane being perpendicular to an incident plane of incident light incident on the sensing surface of the gas sensing element and including a point where the light is emitted from the first optical element on the optical path and a point where the light is incident on the second optical element on the optical path.

Description

Technical Field

[0001] The present invention relates to gas sensing devices. Background Art

[0002] There is a known technology for hydrogen sensing using the magneto-optical effect of a stacked film (sensor element) including a gas sensing layer, a magnetic layer, an optical interference layer, and a reflective layer (for example, JP 2017-172993A). The hydrogen sensor disclosed in JP2017-172993A detects hydrogen by irradiating the surface of the sensor element, detecting reflection, and measuring changes in polarization angles. The main components of the hydrogen sensor, which are composed of a light source, a light detector, a sensing element, and a magnetic field applicator, are arranged to sandwich the atmosphere to be inspected. Specifically, a magnetic field generating mechanism is arranged on the back side of the sensor element (the substrate side of the sensor element), and a light source and a light detector are arranged on the front side of the sensor element (the film surface side of the sensor element). Summary of the invention

[0003] The above-mentioned hydrogen sensor applies light and a magnetic field to a sensing element to detect changes in a gas sensing layer in the sensing element using light. Changes in the gas sensing layer are caused by the surface of the sensing element being exposed to the atmosphere to be inspected. The above-mentioned structure has a light source and a light detector on the atmosphere side, and therefore, a mechanism for holding these components is required. Even if the thickness of all layers is added up, the laminated film of the sensing element is very thin, at about 200nm (0.200μm). The thickness of the glass substrate on which the laminated film is held is about 0.5mm (500μm), and therefore, the sensing element is thin and small. However, since the light source, the light detector, and the structure for holding these components are arranged in front of the sensing element, the sensing element is located at a deeper position when viewed from the atmosphere side.

[0004] Therefore, in the example case where the gas sensor is used to detect hydrogen leakage, in order to expose the surface of the gas sensing element to the atmosphere, the atmosphere must be guided behind the components arranged above the gas sensing element. The structure becomes complicated and restrictions on installation increase.

[0005] One aspect of the present invention is a gas sensing device, comprising: a light source; a photodetector; a gas sensing element, the gas sensing element being arranged on an optical path from the light source to the photodetector; a first optical element, the first optical element being arranged between the light source and the gas sensing element on the optical path; a second optical element, the second optical element being arranged between the gas sensing element and the photodetector on the optical path; and a magnetic field applicator, the magnetic field applicator being configured to apply a magnetic field to the gas sensing element. The gas sensing element reflects light incident along the optical path on a sensing surface. The characteristics of the light reflected by the gas sensing element vary depending on the amount of a specific gas in contact with the gas sensing element. Each of the first optical element and the second optical element bends the optical path. The gas sensing element, the light source, the photodetector, and the magnetic field applicator are arranged on the same side relative to a virtual plane, the virtual plane being perpendicular to an incident plane of incident light incident on the sensing surface of the gas sensing element and including a point where light is emitted from the first optical element on the optical path and a point where light is incident on the second optical element on the optical path.

[0006] One aspect of the present invention realizes a simple structure in front of the sensing face of the sensor element. This structure is conducive to exposing the sensing face of the gas sensing element to the atmosphere to be inspected and reduces the restrictions on installing the gas sensing device.

[0007] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A configuration example of a gas sensing device in Embodiment 1 is schematically shown;

[0009] Figure 2 An example of a stacked structure of a gas sensing element in Embodiment 1 is shown;

[0010] Figure 3A The positional relationship of the components in Embodiment 1 relative to the plane defined by the optical path is shown;

[0011] Figure 3B The positional relationship of the components in Embodiment 1 relative to other planes defined by the optical path is shown;

[0012] Figure 3C The arrangement of the light source, the gas sensing element, and the light detector in Embodiment 1, and the directions of light incident on and emitted from these components are shown;

[0013] Figure 4 is a more specific structural example showing the gas sensing device in Embodiment 1;

[0014] Figure 5A A configuration example of a gas sensing device in Embodiment 2 is schematically shown;

[0015] Figure 5B Another structural example of the gas sensing device in Embodiment 2 is schematically shown;

[0016] Fig. 6A The positional relationship of the components in Embodiment 2 relative to the plane defined by the optical path is shown;

[0017] Figure 6B The positional relationship of the components in Embodiment 2 relative to other planes defined by the optical path is shown;

[0018] Figure 6C The arrangement of the light source, the gas sensing element, and the light detector in Embodiment 2, and the directions of light incident on and emitted from these components are shown;

[0019] Figure 7 An example of the structure of the explosion-proof gas sensing device in Embodiment 3 is shown;

[0020] Figure 8 Another structural example of the explosion-proof gas sensing device in Embodiment 3 is shown;

[0021] Fig. 9 Another structural example of the explosion-proof gas sensing device in Embodiment 3 is shown; and

[0022] Fig.10 Still another structural example of the explosion-proof gas sensing device in Embodiment 3 is shown. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention are described with reference to the accompanying drawings. It should be noted that these embodiments are merely examples for implementing the present invention and do not limit the technical scope of the present invention.

[0024] Described below are embodiments of a gas sensing device. One of the features of the gas sensing device described herein is the arrangement of components. The specific arrangement of components provides an open space in front of the sensing face (surface) of the gas sensing element, which reduces restrictions on installing the gas sensing device.

[0025] Implementation Method 1

[0026] Figure 1The structure example of the gas sensing device 1 in the embodiment is schematically shown. The gas sensing device 1 includes a light source 11, a first polarizer 12, a first reflector 13, a gas sensing element (also simply referred to as a sensing element) 14, a second reflector 15, a second polarizer 16, a photodetector 17, and a magnetic field applicator 18. The gas sensing element 14 includes a substrate 141 and a laminated film 142 provided on the substrate 141. The surface of the laminated film 142 is exposed to the atmosphere 30 to be inspected, and the atmosphere 30 may include the gas to be detected.

[0027] The gas sensing device 1 detects the target gas by measuring the change of the magneto-optical effect (magnetic Kerr effect) of the gas sensing element 14 caused by the target gas. More specifically, the gas sensing device 1 detects the target gas by measuring the change of light as the change of the magneto-optical effect of the stacked film 142 caused by the target gas.

[0028] The light source 11 generates and emits light (measurement light) to illuminate the laminated film 142. The light from the light source 11 is reflected by the laminated film 142, and the light detector 17 detects the light reflected by the laminated film 142. On the optical path 50 from the light source 11 to the light detector 17, the first polarizer 12 and the first reflector 13 are provided between the light source 11 and the gas sensing element 14.

[0029] exist Figure 1 In the illustrated structural example, the first polarizer 12 is disposed between the light source 11 and the first reflector 13 on the optical path 50. Further, on the optical path 50, the second reflector 15 and the second polarizer 16 are disposed between the gas sensing element 14 and the light detector 17. Figure 1 In the illustrated structural example, the second polarizer 16 is arranged between the second reflector 15 and the photodetector 17 on the optical path 50 .

[0030] The magnetic field applicator 18 is disposed on the side of the gas sensing element 14 opposite to the first reflecting mirror 13 and the second reflecting mirror 15. Figure 1 In the example of , the magnetic field applicator 18 is disposed below the gas sensing element 14, and the first reflector 13 and the second reflector 15 are disposed above the stacked film 142. Figure 1 In the example of FIG. 1 , the gas sensing element 14 is disposed between the light source 11 and the light detector 17 when viewed in a direction perpendicular to the sensing surface of the stacked film 142 .

[0031] When viewed in a direction perpendicular to the sensing face of the laminate film 142, the magnetic field applicator 18 at least partially overlaps the gas sensing element 14. Figure 1, the bottom side of the magnetic field applicator 18 is located farther from the sensing surface of the stacked film 142 than the bottom side of the gas sensing element 14. When viewed in a direction perpendicular to the sensing surface of the stacked film 142, the magnetic field applicator 18 is disposed between the light source 11 and the light detector 17.

[0032] The light source 11 generates and emits light to illuminate the gas sensing element 14. The light source 11 may be a semiconductor laser or a light emitting diode. The light from the light source 11 includes a specific wavelength suitable for gas detection using the laminated film 142; an example of the light is monochromatic light having a specific wavelength. The first polarizer 12 transmits light (linearly polarized light) vibrating in a specific direction of the incident light, and attenuates light vibrating in other directions. In other words, the first polarizer 12 generates linearly polarized light from the light of the light source 11.

[0033] Although this structural example generates linearly polarized light using the light source 11 and the first polarizer 12, another structural example may employ a light source that outputs linearly polarized light, such as a semiconductor laser including a polarizer, to omit the first polarizer 12. Figure 1 Different from the structural example in FIG. 1 , the first polarizer 12 may be disposed between the first reflector 13 and the gas sensing element 14 on the optical path 50 .

[0034] The first reflector 13 reflects the light transmitted through the first polarizer 12 to bend the optical path 50. The linearly polarized light reflected by the first reflector 13 is incident on the laminated film 142 of the gas sensing element 14. The magnetic field applicator 18 applies a magnetic field to the laminated film 142. The direction of the magnetic field is parallel or perpendicular to the surface of the laminated film 142.

[0035] When the laminate film to which the magnetic field is applied reflects the incident light, the characteristics of the reflected light (e.g., polarization angle and intensity) are changed to be different from the characteristics of the incident light due to the magneto-optical effect of the laminate film 142. At the same time, the characteristics of the reflected light vary depending on whether the target gas exists and the density of the target gas. The reflected light is incident on the second reflector 15.

[0036] The light reflected by the second reflector 15 is incident on the second polarizer 16. The second polarizer 16 transmits light (linearly polarized light) vibrating in a specific direction in the incident light, and attenuates light vibrating in other directions. The second polarizer 16 enables the characteristic change caused by the magneto-optical effect of the stacked film 142 to be detected from the reflected light. Specifically, in a structure in which the characteristic change of the reflected light manifests as a change in the polarization angle (like the polarized Kerr effect or the longitudinal Kerr effect), the second polarizer 16 converts the characteristic change of the reflected light into a change in light intensity. The light transmitted through the second polarizer 16 is incident on the photodetector 17. The photodetector 17 measures the intensity of the incident light. More optical elements may be added to Figure 1for example, a filter for transmitting light having a specific wavelength as light emitted from the light source 11 may be provided between the second reflector 15 and the photodetector 17.

[0037] Figure 2 An example of a stacked structure of the gas sensing element 14 is shown. Figure 2 The stacked film 142 is provided on the substrate 141. The stacked structure of the stacked film 142 (e.g., the material of each layer, the number of layers, the order of layers, and the thickness of each layer) is appropriately selected to adjust the detectable density range of the target gas or detect gases other than hydrogen.

[0038] The substrate 141 may be a glass substrate having a thickness of about 0.5 mm (500 μm). The laminated film 142 is formed by laminating a reflective metal layer 424, a dielectric optical interference layer 423, a magnetic metal layer 422, and a gas sensing layer 421 in order from bottom to top. Another dielectric optical interference layer may be interposed between the magnetic metal layer 422 and the gas sensing layer 421. As will be described below, the thickness of each layer is appropriately determined so that light incident on the laminated film 142 will be multiply reflected within the laminated film 142. For example, the thickness of each layer is about several tens of nanometers. The laminated film 142 may have a different structure that causes the effects described later, instead of Figure 2 The structure shown.

[0039] Due to the reaction with hydrogen, the optical properties of the gas sensing layer 421, such as the refractive index and the absorption coefficient, change. Hydrogen can be detected by measuring the change in the properties of the reflected light caused by the change in the optical properties of the gas sensing layer 421. The gas sensing layer 421 can be made of any material that causes a change in optical properties (such as the refractive index and the absorption coefficient) due to the reaction with hydrogen. For example, Pd can be used because Pd shows a significant optical change in response to contact with hydrogen.

[0040] The magnetic metal layer 422 may be a single-layer film or a multi-layer film of a common magnetic material. The magnetic material may be a metal such as Fe, Co or Ni or an alloy thereof. The dielectric optical interference layer 423 may be made of an oxide or nitride transparent to light of a specific wavelength, such as SiO2, ZnO, MgO, TiO2 or AlN. The material of the reflective metal layer 424 may be a common metal material having a high reflectivity to a specific wavelength of light emitted from the light source 11, such as Ag, Al, Au, Cu or an alloy thereof.

[0041] The mechanism of detecting hydrogen gas using the gas sensing device 1 is described. The stacked film 142 is configured so that multiple reflections within the stacked film 142 cause the polarization angle of reflected light reflected therefrom to be maximally changed with respect to linearly polarized incident light having a specific wavelength.

[0042] The gas sensing device 1 irradiates the stacked film 142 with linearly polarized light, and at the same time causes the magnetic field applicator 18 to apply a magnetic field strong enough to saturate the magnetization of the magnetic metal layer 422 in one direction to the stacked film 142. The irradiated light (incident light) is reflected multiple times in the stacked film 142 to receive a significant magneto-optical effect, with the result that the reflected light is emitted at a polarization angle that is much different from the polarization angle of the incident light.

[0043] When the gas sensing layer 421 comes into contact with hydrogen, optical properties such as the refractive index or absorption coefficient in the gas sensing layer 421 change. Therefore, the optical interference condition in the stacked film 142 changes, thereby reducing the effect of multiple reflections. When this action occurs under the condition that a magnetic field is being applied, the frequency of the change in the polarization angle caused by the magneto-optical effect occurring in the magnetic metal layer 422 decreases, with the result that the change in the polarization angle of the outgoing light relative to the polarization angle of the linearly polarized incident light becomes smaller than in the case where hydrogen is not present.

[0044] The polarization angle of light reflected from the stacked film 142 changes according to the magnetization direction of the magnetic metal layer 422 of the stacked film 142. The gas sensing device 1 applies a magnetic field that periodically changes its direction to the opposite direction to the stacked film 142 using the magnetic field applicator 18, and detects the change in the polarization angle of light reflected from the stacked film 142, thereby detecting hydrogen gas with high accuracy.

[0045] Since the second polarizer 16 transmits only light (component) linearly polarized in a specific direction, the intensity of light transmitted through the second polarizer 16 among the reflected light reflected from the stacked film 142 varies according to the polarization angle of the reflected light reflected from the stacked film 142. The photodetector 17 detects the change in the polarization angle in the form of a change in light intensity.

[0046] The gas sensing device 1 can measure the change of the magneto-optical effect of the stacked film 142 caused by hydrogen in different ways. For example, a light detector can be used to detect the polarization angle, such as differential detection using a polarization beam splitter. In this case, the second polarizer 16 can be omitted. In another example, the gas sensing device 1 can apply a fixed (non-alternating) magnetic field to the stacked film 142 to detect the target gas. The gas sensing device 1 can also utilize the transverse Kerr effect. The transverse Kerr effect occurs when the direction of the applied magnetic field is in the plane of the stacked film 142 and perpendicular to the projection of the incident light and the reflected light on the reflective surface. The change in the transverse Kerr effect is not observed in terms of polarization angle but in terms of reflectivity (intensity of reflected light). Therefore, the second polarizer 16 can be omitted. The second polarizer 16 can be replaced by a filter.

[0047] Figure 3AThe positional relationship of the components of the gas sensing device 1 and the plane (virtual plane) defined by the optical path 50 of the gas sensing device 1 is shown. The light on the optical path 50 is incident on a point 511 on the first reflector 13 and is reflected. The point 511 is the point where the light exits the first reflector 13. The light on the optical path 50 is incident on a point 512 on the second reflector 15 and is reflected. The point 512 is the point where the light is incident on the second reflector 15.

[0048] The incident plane of the incident light 501 to the sensing surface of the gas sensing element 14 and the reflected light 502 reflected from the sensing surface is a plane including the incident light 501 and the reflected light 502. Figure 3A In the example of , the normal of the incident plane is perpendicular to the drawing. A virtual plane 513 including the above-mentioned points 511 and 512 and perpendicular to the incident plane of the incident light 501 and the reflected light 502 can be defined. In the following, the term "virtual plane" is sometimes abbreviated as "plane". Figure 3A In the example of FIG. 5 , the plane 513 is perpendicular to the drawing. The gas sensing element 14, the light source 11, the light detector 17 and the magnetic field applicator 18 are arranged on the same side relative to the plane 513 ( Figure 3A This arrangement simplifies the structure in front of the sensing surface of the gas sensing element, is conducive to exposing the sensing surface of the gas sensing element to the atmosphere to be inspected, and reduces restrictions on the installation of the gas sensing device.

[0049] Figure 3B The positional relationship of the components of the gas sensing device 1 and other planes (virtual planes) defined by the optical path 50 of the gas sensing device 1 is shown. Plane 521 includes the incident light 501 and is perpendicular to the incident planes of the incident light 501 and the reflected light 502; one end of the plane 521 is defined by the sensing surface of the gas sensing element 14. Plane 522 includes the reflected light 502 and is perpendicular to the incident planes of the incident light 501 and the reflected light 502; one end of the plane 522 is defined by the sensing surface of the gas sensing element 14. These ends on the sensing surface are common to plane 521 and plane 522.

[0050] exist Figure 3B In the example of FIG. 1 , the gas sensing element 14, the light source 11, the light detector 17 and the magnetic field applicator 18 are arranged on the same side relative to the planes 521 and 522 ( Figure 3B This arrangement simplifies the structure in front of the sensing surface of the gas sensing element to facilitate exposure of the sensing surface of the gas sensing element to the atmosphere to be inspected and reduces restrictions on the installation of the gas sensing device.

[0051] Figure 3CThe arrangement of the light source 11, the gas sensing element 14 and the light detector 17, as well as the direction and orientation (direction of the vector) of the light incident to and emitted from these components are shown. The direction and orientation of the light are represented by a direction vector. First, a normal vector 59 of the sensing surface pointing from the sensing surface to the atmosphere to be inspected is defined along a normal 143 perpendicular to the sensing surface of the gas sensing element 14 as a reference for the orientation of the light. The direction vector 54 of the incident light incident on the gas sensing element 14 has a component 541 parallel to the normal vector 59 of the sensing surface. The direction vector 54 of the incident light also has a component perpendicular to the normal vector 59 of the sensing surface (the light is obliquely incident and obliquely reflected).

[0052] The direction vector 53 of the light emitted from the light source 11 has a component parallel to the normal vector 59 of the sensing surface. In this example, the direction vector 53 is parallel to the normal vector 59 of the sensing surface and has no component perpendicular to the normal vector 59 of the sensing surface. The direction vector 53 has the same orientation as the normal vector 59 of the sensing surface.

[0053] The direction vector 57 of the light incident on the light detector 17 has a component parallel to the normal vector 59 of the sensing surface. In this example, the direction vector 57 is parallel to the normal vector 59 of the sensing surface and has no component perpendicular to the normal vector 59 of the sensing surface. The orientation of the direction vector 57 is opposite to the orientation of the normal vector 59 of the sensing surface.

[0054] As reference Figure 1 As described above, the first reflector 13 and the second reflector 15 bend the optical path 50 between the light source 11 and the light detector 17. Figure 3C The three direction vectors 53, 54 and 57 having the above relationship realize an arrangement in which the light source 11 and the light detector 17 are located on the same side as the gas sensing element 14, rather than an arrangement in which the light source 11 and the light detector 17 are located on opposite sides of the gas sensing element 14 across the atmosphere 30 to be inspected.

[0055] Specifically, the light source 11 and the light detector 17 are disposed on the substrate side of the gas sensing element 14 relative to the space of the atmosphere 30 that may include the target gas. Figure 1 In the structural example of FIG. 1 , the light source 11 , the light detector 17 , the gas sensing element 14 , and the magnetic field applicator 18 are arranged on the same side relative to the atmosphere 30 .

[0056] The gas sensing device 1 illuminates the gas sensing element 14 from the atmosphere side with the measuring light emitted from the substrate side of the gas sensing element 14 toward the laminated film side and reflected by the first reflector 13. The reflected light from the gas sensing element 14 toward the atmosphere is reflected by the second reflector 15 and directed toward the photodetector 17. This structure helps to provide an open space in front of the laminated film 142 of the gas sensing element 14.

[0057] exist Figure 1 In the structural example of FIG. 1 , when the gas sensing element 14 is observed along the normal line 143 from the film side of the laminated film 142, neither the light source 11 nor the light detector 17 overlaps with the gas sensing element 14. This arrangement provides an open space in front of the laminated film 142, so that the laminated film 142 is more appropriately exposed to the atmosphere 30 to be inspected.

[0058] exist Figure 1 In the structural example, the direction vector 53 of the light emitted from the light source 11 and the direction vector 57 of the light incident on the light detector 17 are parallel to the normal 143 of the stacked film 142; however, these vectors may have a component parallel to the normal 143 and a component perpendicular to the normal 143. For example, the vector 53 has a component parallel to the normal 143 that is greater than the component perpendicular to the normal 143; and the vector 57 also has a component parallel to the normal 143 that is greater than the component perpendicular to the normal 143.

[0059] exist Figure 1 In the structural example, the light emitting surface ( Figure 1 The top surface in the image) and the incident surface of the light detector 17 ( Figure 1 The top surface in the stacked film 142 is positioned closer to the atmosphere 30 ( Figure 1 In another example, the light exit surface of the light source 11 or the incident surface of the light detector 17 may be positioned to be higher than Figure 1 The sensing surface of the laminated film 142 is lower, or positioned further away from the atmosphere 30 .

[0060] Figure 4 A more specific structural example of the gas sensing device 1 is shown. Figure 4 In the structural example shown, the light source 11, the light detector 17, and the magnetic field applicator 18 are fixed to the base 19. The first polarizer 12, the first reflector 13, the second reflector 15, and the second polarizer 16 are held by unillustrated components fixed to the base 19. The first polarizer 12 can be attached to the front side of the light source 11, and the second polarizer 16 can be attached to the front side of the light detector 17. Due to these structures, these components are fixed in appropriate positions and orientations to define the optical path 50 and are integrated into the gas sensing device 1. In actual use, the user installs the integrated gas sensing device 1 at a desired position.

[0061] The magnetic field applicator 18 includes: a coil 181, which is a magnetic field generating element for generating a magnetic field; and a yoke 182, which is used to guide the magnetic field generated by the coil 181 to the gas sensing element 14. The coil 181 is wound around the yoke 182, and the gas sensing element 14 is arranged in the gap between the magnetic poles of the yoke 182. The yoke 182 is fixed to the base 19 through a base, wherein the base is inserted between the yoke 182 and the base 19. In this example, the base 19 has a plate shape, but the shape is not limited to this example.

[0062] exist Figure 4 In the structural example, when viewed in a normal direction perpendicular to the sensing surface of the gas sensing element 14, the gas sensing element 14 and the magnetic field applicator 18 are located between the light source 11 and the light detector 17. When viewed in the same direction, the gas sensing element 14 is located inside the magnetic field applicator 18. The bottom side (bottom surface) of the magnetic field applicator 18 is closer to the base 19 than the bottom side of the gas sensing element 14. When viewed perpendicularly to a plane (reflection surface) including incident light incident on the film surface of the gas sensing element 14 and reflected light reflected from the film surface, the magnetic field applicator 18 is located between the light source 11 and the light detector 17.

[0063] exist Figure 4 In the structural example, the magnetic field applicator 18 applies a magnetic field in a direction along the sensing surface (main surface) of the laminate film 142. The magnetic field applicator 18 including the coil 181 and the yoke 182 can easily control the strength of the magnetic field and effectively apply the magnetic field to the laminate film 142. The magnetic field applicator 18 can be configured differently; for example, it can use a hard magnetic material or a hollow coil to surround the gas sensing element 14.

[0064] As described above, the components of the gas sensing device 1 of the present embodiment are arranged so that components requiring electrical wiring or components other than the first reflector 13 and the second reflector 15 are gathered around the base 19. The structure around the sensing surface of the laminated film 142 of the gas sensing element 14 is simplified. Therefore, the sensing surface is easily exposed to the atmosphere 30 to be inspected, and there are few restrictions on its installation for detecting gas.

[0065] Implementation Method 2

[0066] Embodiment 1 includes a first reflector 13 as a first optical element for bending the optical path 50 and a second reflector 15 as a second optical element for bending the optical path 50. Embodiment 2 described below uses optical fibers as the first optical element and the second optical element for bending the optical path 50. The optical fibers increase the flexibility of forming the optical path 50.

[0067] Figure 5AAn example of the structure of the gas sensing device 1 in this embodiment is schematically shown. The differences from Embodiment 1 are mainly described. The first optical fiber 21 is arranged between the light source 11 and the first polarizer 12 on the optical path 50. The second optical fiber 23 is arranged between the second polarizer 16 and the photodetector 17 on the optical path 50. A portion of the optical path 50 is located in the first optical fiber 21, and another portion of the optical path 50 is located in the second optical fiber 23. Both the first optical fiber 21 and the second optical fiber 23 bend the optical path 50.

[0068] The first optical fiber 21 and the second optical fiber 23 enable the light source 11, the light detector 17, the gas sensing element 14, and the magnetic field applicator 18 to be arranged on the same side of the atmosphere 30 to be inspected. The light from the light source 11 passes through the first optical fiber 21 and is incident on the first polarizer 12. The linearly polarized light from the first polarizer 12 is incident on the laminated film 142, and the reflected light reflected from the laminated film 142 is incident on the second polarizer 16. The light transmitted through the second polarizer 16 passes through the second optical fiber 23 and is incident on the light detector 17.

[0069] Figure 5A The light source 11 and the light detector 17 are shown arranged in a manner similar to that in FIG. Figure 1 However, as long as the above conditions are satisfied in the path where the optical fibers 21 and 23 are laid, various structures can be used. Figure 5B Another structural example of the gas sensing device 1 in Embodiment 2 is schematically shown. Figure 5B As shown, the optical fiber can be extended to obtain a structure in which the light source 11 emits light in a lateral direction or light is incident on the light detector 17 in a lateral direction, and another structure in which the light source 11 and the light detector 17 are placed quite far from the gas sensing element 14.

[0070] Fig. 6A The positional relationship of the components of the gas sensing device and the plane (virtual plane) defined by the optical path 50 of the gas sensing device 1 is shown. Point 531 is a point where light exits the first optical fiber 21. Point 532 is a point where light enters the second optical fiber 23.

[0071] A virtual plane 533 may be defined that includes the above-mentioned points 531 and 532 and is perpendicular to the incident plane of the incident light 501 and the reflected light 502. Fig. 6A In the example of FIG. 5 , the plane 533 is perpendicular to the drawing. The gas sensing element 14, the light source 11, the light detector 17 and the magnetic field applicator 18 are arranged on the same side relative to the plane 533 ( Fig. 6A This arrangement simplifies the structure in front of the sensing surface of the gas sensing element to facilitate exposure of the sensing surface of the gas sensing element to the atmosphere to be inspected and reduces restrictions on the installation of the gas sensing device.

[0072] Figure 6B The positional relationship of the components of the gas sensing device 1 and other planes (virtual planes) defined by the optical path 50 of the gas sensing device 1 is shown. Plane 541 includes the incident light 501 and is perpendicular to the incident planes of the incident light 501 and the reflected light 502; one end of the plane 541 is defined by the sensing surface of the gas sensing element 14. Plane 542 includes the reflected light 502 and is perpendicular to the incident planes of the incident light 501 and the reflected light 502; one end of the plane 542 is defined by the sensing surface of the gas sensing element 14. These ends on the sensing surface are common to plane 541 and plane 542.

[0073] exist Figure 6B In the example of FIG. 1 , the gas sensing element 14, the light source 11, the light detector 17 and the magnetic field applicator 18 are arranged on the same side relative to the planes 541 and 542 ( Figure 6B This arrangement simplifies the structure in front of the sensing surface of the gas sensing element, facilitates the exposure of the sensing surface of the gas sensing element to the atmosphere to be inspected, and reduces restrictions on the installation of the gas sensing device. Fig. 6A and Figure 6B The description provided can be applied to Figure 5B An example of the structure is shown.

[0074] Figure 6C The arrangement of the light source 11, the gas sensing element 14 and the light detector 17 as well as the direction and orientation (direction of the vector) of the light incident on and emitted from these components are shown. The direction and orientation of the light are represented by the direction vector. Figure 6C In the same manner, the normal vector 59 of the sensing surface is defined as the reference for the orientation of the light. The direction vector 54 of the incident light to the gas sensing element 14 has a component 541 parallel to the normal vector 59 of the sensing surface. The direction vector 54 of the incident light also has a component perpendicular to the normal vector 59 of the sensing surface (the light is obliquely incident and obliquely reflected). Figure 6C In FIG. 1 , dashed lines 145A and 145B are parallel to normal line 143 .

[0075] The direction vector 53 of the light emitted from the light source 11 has a component 531 parallel to the normal vector 59 of the sensing surface. The direction vector 53 also has a component perpendicular to the normal vector 59 of the sensing surface. The orientation of the component 531 of the direction vector 53 parallel to the normal vector 59 of the sensing surface is the same as the orientation of the normal vector 59 of the sensing surface. The component 531 parallel to the normal vector 59 of the sensing surface is greater than the component perpendicular to the normal vector 59 of the sensing surface.

[0076] The direction vector 57 of the light incident on the light detector 17 has a component 571 parallel to the normal vector 59 of the sensing surface. In this example, the direction vector 57 also has a component perpendicular to the normal vector 59 of the sensing surface. The orientation of the component 571 of the direction vector 57 parallel to the normal vector 59 of the sensing surface is opposite to the orientation of the normal vector 59 of the sensing surface. The component 571 parallel to the normal vector 59 of the sensing surface is greater than the component perpendicular to the normal vector 59 of the sensing surface.

[0077] As reference Figure 5A As described, the first optical fiber 21 and the second optical fiber 23 bend the optical path 50 between the light source 11 and the light detector 17. Figure 6C The three direction vectors 53, 54 and 57 having the above relationship realize an arrangement in which the light source 11 and the light detector 17 are located on the same side as the gas sensing element 14, rather than an arrangement in which the light source 11 and the light detector 17 are located on opposite sides of the gas sensing element 14 across the atmosphere 30 to be inspected.

[0078] and Figure 5A The layout is different, refer to Figure 6C The described relationship does not apply to the case where the first optical fiber 21 and the second optical fiber 23 are extended. Figure 5B However, the first optical fiber 21 forming the optical path from the light source 11 to the first polarizer 12 and the second optical fiber 23 forming the optical path from the second polarizer 16 to the optical detector 17 have at least one section where the tangent vector along the optical path satisfies the reference Figure 6C Describes the relationship between segments A and B (see Figure 5B ).

[0079] It can be understood from the above that in the section from the point where the light is emitted from the light source 11 to the point where the light is emitted from the first optical fiber 21, there is a direction vector of the light, and the direction vector of the light includes a component parallel to the normal vector 59 of the sensing surface of the gas sensing element 14 and along the same orientation as the normal vector 59. The incident light incident on the sensing surface of the gas sensing element 14 has a component parallel to the normal vector 59 and along the opposite orientation to the normal vector 59. In addition, in the section from the point where the light is incident on the second optical fiber 23 to the point where the light is incident on the light detector 17, there is a direction vector of the light, and the direction vector of the light includes a component parallel to the normal vector 59 of the sensing surface of the gas sensing element 14 and along the opposite orientation to the normal vector 59. This structure is suitable for including the first reflector 13 and the second reflector 15 instead of the first optical fiber 21 and the second optical fiber 23. Figure 5A and Figure 5B The structure shown.

[0080] When the optical fiber is laid in the path including the above-mentioned section, it is possible to realize an arrangement in which the light source 11 and the light detector 17 are located on the same side as the gas sensing element 14, instead of an arrangement in which the gas light source 11 and the light detector 17 are located on the opposite side of the gas sensing element 14 across the atmosphere 30 to be inspected. Further, the flexibility of the arrangement of the light source 11 and the light detector 17 in the gas sensing device 1 is increased.

[0081] Compared with the structure including the reflector in Embodiment 1, the above-mentioned structure of irradiating light from the atmosphere side to the gas sensing element 14 using the first optical fiber 21 and causing the reflected light to enter the second optical fiber 23 to guide the light to the photodetector 17 can further simplify the structure in front of the surface (sensing surface) of the laminated film 142, and facilitates the laminated film 142 to be exposed to the atmosphere 30 to be inspected. The use of optical fibers reduces restrictions on the arrangement of the light source 11 and the photodetector 17, and improves flexibility in designing the gas sensing device 1. Reducing the height of the gas sensing device 1 significantly reduces restrictions on the installation of the gas sensing device 1. Either of the two optical fibers can be replaced by a reflector.

[0082] Implementation 3

[0083] The gas sensing device described below has a component to be energized within a container. When the target gas is a flammable gas such as hydrogen or an explosive gas, isolating the component to be energized from the atmosphere to be inspected improves safety.

[0084] Figure 7 An example of the structure of the explosion-proof gas sensing device 1 is shown. Figure 1 The difference from the structural example in the embodiment 1 shown. The gas sensing device 1 includes an airtight container 40. The airtight container 40 can be made of resin or metal. The airtight container 40 accommodates a light source 11, a light detector 17, and a magnetic field applicator 18. These components are components to be energized (active components). The airtight container 40 also accommodates a first polarizer 12 and a second polarizer 16. The first polarizer 12 and the second polarizer 16 are components that are not energized, and they can be arranged outside the airtight container 40. The first reflector 13 and the second reflector 15 are components that are not energized, and they are arranged outside the airtight container 40.

[0085] The gas sensing element 14 is fixed to the airtight container 40 so that the laminated film 142 will be exposed to the atmosphere 30 to be inspected. Figure 7In the structural example, the substrate 141 of the gas sensing element 14 is assembled in an opening (not shown) provided in the airtight container 40; a portion of the substrate 141 is located inside the airtight container 40, and the rest is exposed to the outside of the airtight container 40. The airtight container 40 can be made of a material that allows magnetic flux to pass through. In this case, the entire gas sensing element 14 can be arranged outside the airtight container 40, so that the magnetic field applicator 18 applies a magnetic field to the gas sensing element 14 from the back of the airtight container 40.

[0086] The airtight container 40 has a first window 41 and a second window 42. The first window 41 and the second window 42 are transparent to the measurement light having a specific wavelength. The first window 41 is arranged between the light source 11 and the first reflector 13 on the optical path 50, more specifically, between the first polarizer 12 and the first reflector 13. The second window 42 is arranged between the second reflector 15 and the light detector 17 on the optical path 50, more specifically, between the second reflector 15 and the second polarizer 16.

[0087] Figure 7 The structure in the embodiment achieves isolation of the light source 11, the light detector 17, and the magnetic field applicator 18 in the components to be energized from the atmosphere 30 to be inspected while maintaining the sensing function of the gas sensing device 1. In this structural example, as described in Embodiment 1, the light source 11, the light detector 17, the gas sensing element 14, and the magnetic field applicator 18 are arranged on the same side of the atmosphere 30 to be inspected; therefore, an airtight container (airtight chamber) 40 with a simple shape can accommodate the above-mentioned components so that the laminated film 142 of the gas sensing element 14 is exposed to the atmosphere 30 to be inspected.

[0088] Figure 8 Another structural example of the explosion-proof gas sensing device 1 is shown. Figure 7 The first reflector 13 and the second reflector 15 are accommodated in addition to the components accommodated in the container 40 in the structural example. This structure protects the reflective surfaces of the first reflector 13 and the second reflector 15 from contamination while maintaining the ease of installation of the explosion-proof gas sensing device 1.

[0089] Fig. 9 FIG. 1 shows another structural example of the explosion-proof gas sensing device 1. Figure 7 The window of the airtight container 40 has another additional function. Specifically, the first polarizer 12 and the second polarizer 16 are assembled in the opening of the airtight container 40 to form a window. The first polarizer 12 replaces Figure 7 In the structural example of FIG. 1 , the second window 41 is replaced by the second polarizer 16 , and the second window 42 is replaced. This structural example achieves a reduction in the number of components.

[0090] Fig.10 FIG. 1 shows another structural example of the explosion-proof gas sensing device 1. Figure 5A and Figure 5B The difference between the structural examples is shown in FIG. 1 . The airtight container 40 accommodates the light source 11, the light detector 17, and the magnetic field applicator 18. The airtight container 40 also accommodates the first optical fiber 21 and the second optical fiber 23. These optical fibers are components that are not energized and can be arranged outside the container 40. The first polarizer 12 and the second polarizer 16 are assembled in the opening of the airtight container 40, thereby reducing the number of components of the gas sensing device 1.

[0091] The gas sensing element 14 is fixed to the airtight container 40 so that the laminated film 142 will be exposed to the atmosphere 30 to be inspected. Fig.10 In the structural example, the substrate 141 of the gas sensing element 14 is assembled in the opening (not shown) of the airtight container 40; a part of the substrate 141 is inside the container 40, and the rest is exposed to the outside of the airtight container 40. The laminated film 142 on the substrate 141 is exposed to the outside of the airtight container 40.

[0092] Since the active components to be energized are protected in the airtight container as described above, the remaining components in the environment to be detected are only components that are not energized, such as the gas sensing element 14 and the reflectors 13 and 15. Such an explosion-proof structure is particularly useful for a gas sensing device for sensing combustible gas.

[0093] As mentioned above, embodiments of the present invention have been described. However, the present invention is not limited to the aforementioned embodiments. Within the scope of the present invention, those skilled in the art can easily modify, add or convert each element in the aforementioned embodiments. A part of the structure of an embodiment can be replaced by the structure of another embodiment, or the structure of an embodiment can be incorporated into the structure of another embodiment.

Claims

1. A gas sensing device comprising: light source; Light detector; a gas sensing element disposed on an optical path from the light source to the light detector; a first optical element, the first optical element being arranged between the light source and the gas sensing element on the optical path; a second optical element disposed between the gas sensing element and the light detector on the optical path; a magnetic field applicator configured to apply a magnetic field to the gas sensing element; a first polarizer, the first polarizer being located between the light source and the first optical element on the light path; as well as a second polarizer, the second polarizer being located between the second optical element and the light detector on the light path, wherein the gas sensing element is a stacked film including at least a reflective metal layer, a dielectric optical interference layer on a virtual plane side of the reflective metal layer, a magnetic metal layer on a virtual plane side of the dielectric optical interference layer, and a gas sensing layer on a virtual plane side of the magnetic metal layer, the gas sensing layer having optical properties that change due to a reaction of the gas sensing layer with a gas, The gas sensing element reflects the light incident along the light path on the sensing surface. wherein each of the first optical element and the second optical element is a reflector, wherein each of the first optical element and the second optical element bends the optical path by reflecting incident light, wherein the first optical element reflects light incident from the light source through the first polarizer to the gas sensing element, and the incident light incident to the first optical element has a component parallel to and oriented in the same direction as a normal vector of the sensing surface of the gas sensing element, wherein the second optical element reflects light incident from the gas sensing element to the second polarizer, and the light reflected by the second optical element has a component that is parallel to and opposite to the normal vector of the sensing surface of the gas sensing element, wherein the light detector receives light reflected by the second optical element and transmitted through the second polarizer, wherein the gas sensing element, the light source, the light detector, the first polarizer, the second polarizer, and the magnetic field applicator are arranged on the same side relative to a virtual plane, the virtual plane being perpendicular to an incident plane of incident light incident on the sensing surface of the gas sensing element and including a point where light is emitted from the first optical element on the optical path and a point where light is incident on the second optical element on the optical path, wherein the incident light incident on the sensing surface of the gas sensing element has a component parallel to and opposite to a normal vector of the sensing surface of the gas sensing element and a component perpendicular to the normal vector, wherein the light reflected by the gas sensing element has a component parallel to and oriented in the same direction as the normal vector and a component perpendicular to the normal vector, and There is an open space in front of the sensing surface of the gas sensing element.

2. The gas sensing device according to claim 1, wherein: When the gas sensing element is viewed in an orientation opposite to the normal vector, the light source and the light detector are arranged so as not to overlap with the gas sensing element.

3. The gas sensing device according to claim 1, wherein: At least one of the magnetic field applicator and the gas sensing element is disposed between the light source and the light detector.

4. The gas sensing device according to claim 1, wherein: The light source, the light detector, the gas sensing element, and the magnetic field applicator are fixed to the same base.

5. The gas sensing device according to claim 1, further comprising an airtight container formed to accommodate the light source, the light detector, and a magnetic field generating element of the magnetic field applicator, in, The airtight container has a first window arranged between the light source and the gas sensing element on the light path and a second window arranged between the gas sensing element and the light detector on the light path, and Wherein, a surface of the gas sensing element for receiving the incident light is located outside the airtight container.

6. The gas sensing device according to claim 5, wherein: The airtight container also accommodates the first optical element and the second optical element.

7. The gas sensing device according to claim 5, wherein: The first window is the first polarizer and / or the second window is the second polarizer.

8. The gas sensing device according to claim 1, wherein: The portion of the optical path extending between the first polarizer and the second polarizer includes no optical components other than the first optical element, the gas sensing element, and the second optical element.

9. A gas sensing device comprising: light source; Light detector; a gas sensing element disposed on an optical path from the light source to the light detector; a first optical fiber, the first optical fiber being arranged between the light source and the gas sensing element on the optical path; a second optical fiber disposed between the gas sensing element and the light detector on the optical path; a magnetic field applicator configured to apply a magnetic field to the gas sensing element; a first polarizer, the first polarizer being arranged between the first optical fiber and the gas sensing element on the optical path; as well as a second polarizer, the second polarizer being arranged between the gas sensing element and the second optical fiber on the optical path, wherein the gas sensing element is a stacked film including at least a reflective metal layer, a dielectric optical interference layer on a virtual plane side of the reflective metal layer, a magnetic metal layer on a virtual plane side of the dielectric optical interference layer, and a gas sensing layer on a virtual plane side of the magnetic metal layer, the gas sensing layer having optical properties that change due to a reaction of the gas sensing layer with a gas, The gas sensing element reflects the light incident along the light path on the sensing surface. wherein each of the first optical fiber and the second optical fiber bends the optical path, wherein the gas sensing element, the light source, the light detector, and the magnetic field applicator are arranged on the same side relative to a virtual plane, the virtual plane being perpendicular to an incident plane of incident light incident on the sensing surface of the gas sensing element and including a point where light is emitted from the first optical fiber on the optical path and a point where light is incident on the second optical fiber on the optical path, wherein, in a section between a point where a light ray is emitted from the light source and a point where the light ray is emitted from the first optical fiber, the light path includes a point for showing a direction vector of the light ray, the direction vector of the light ray including a component that is parallel to and has the same orientation as a normal vector of the sensing surface of the gas sensing element, wherein the incident light incident on the sensing surface of the gas sensing element has a component parallel to and opposite to a normal vector of the sensing surface of the gas sensing element and a component perpendicular to the normal vector, wherein the light reflected by the gas sensing element has a component parallel to and oriented in the same direction as the normal vector and a component perpendicular to the normal vector, and Wherein, in the section between the point where the light ray is incident on the second optical fiber and the point where the light ray is incident on the light detector, the optical path includes a point for showing a direction vector of the light ray, and the direction vector of the light ray includes a component parallel to and opposite to the normal vector.

10. The gas sensing device according to claim 9, wherein: The direction vector of the light emitted from the light source has a component that is parallel to and oriented in the same direction as the normal vector of the sensing face of the gas sensing element, and The direction vector of the light incident on the light detector has a component that is parallel to and opposite to the normal vector.

11. The gas sensing device according to claim 9, wherein: The light source, the light detector, the gas sensing element, and the magnetic field applicator are fixed to the same base.

12. The gas sensing device according to claim 9, further comprising an airtight container formed to accommodate the light source, the light detector, and a magnetic field generating element of the magnetic field applicator, in, The airtight container has a first window arranged between the light source and the gas sensing element on the light path and a second window arranged between the gas sensing element and the light detector on the light path, and Wherein, a surface of the gas sensing element for receiving the incident light is located outside the airtight container.

13. The gas sensing device according to claim 12, wherein: The airtight container also accommodates the first optical fiber and the second optical fiber.

14. The gas sensing device according to claim 12, wherein: The first window is the first polarizer.

15. The gas sensing device according to claim 12, wherein: The second window is the second polarizer.

16. The gas sensing device of claim 12, wherein: The first window is the first polarizer and the second window is the second polarizer.

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