Optical sensor device

Abstract

To properly measure target fluid using a detector element including a prism.SOLUTION: An optical sensor device is disclosed. A detector element includes a prism having a slant and two leg surfaces, and a detection film arranged on the slant as a measurement object. The detection film is exposed to an airtight space where the measurement object is present. The detector element covers an opening in a partition wall of the airtight space where the measurement object is present. An elastic seal part is present between the detector element and the opening. A fixture presses the detector element so that the elastic seal part elastically deforms to fix the detector element. A light source and a photodetector are present outside the airtight space where the measurement object is present. Light from a light source transmitting through one of the two leg surfaces enters the detection film, and reflected light from the detection film is emitted from the other of the two leg surfaces. The photodetector detects the light emitted from the other of the two leg surfaces and reflected on the detection film.SELECTED DRAWING: Figure 20C

Description

[Technical field]

[0001] The present disclosure relates to an optical sensor device. [Background technology]

[0002] Sensor devices have been developed to detect the types and concentrations of various chemical substances. For example, a sensor for detecting hydrogen gas leaks has been developed as a gas sensor device. Several hydrogen gas sensors with different detection methods are known, but most require high-temperature operation to improve response speed and provide cleaning effects. Hydrogen gas sensors that require high-temperature operation are required to prevent the risk of explosion caused by overcurrent or sparks in the electric circuit coming into contact with hydrogen.

[0003] As an example of a gas sensor device, a method for detecting hydrogen gas by optical techniques is known, for example, an optical detection type gas sensor using surface plasmon resonance is known. In addition, a technology is known in which a metal layer formed on a glass substrate is used as a sensitive layer, and the back surface of the glass substrate and a prism are optically matched with optical coupling oil. Light is irradiated onto the sensitive layer from the prism side, and the reflected light passes through the prism and is detected by an external photodetector. The prism reduces the amount of light reflected by the glass substrate reaching the photodetector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] KR100927378B1 [Patent Document 2] CN112014358A [Patent Document 3] US2022042959A1 Summary of the Invention [Problem to be solved by the invention]

[0005] A sensing element in which a gas sensing laminated film (also simply called a gas sensing film) is formed on a transparent substrate including a prism can be used to measure fluids including gases and liquids, for example. For measurement, it is necessary that the sensing film of the sensing element is exposed to the measurement object. Components such as the light source and photodetector are required to be placed outside the measurement object. The measurement object is required to be enclosed in an airtight space and not to escape from the airtight space or to prevent the inflow of air from the outside into the airtight space. [Means for solving the problem]

[0006] The optical sensor device according to one aspect of the present disclosure includes a light source, a sensing element, a photodetector, a fixture, and an elastic seal part. The sensing element includes a prism including an inclined surface and two leg surfaces, and a sensing film of a measurement target arranged on the inclined surface. The sensing film is exposed to an airtight space in which the measurement target exists. The sensing element covers an opening in a partition wall of the airtight space in which the measurement target exists. The elastic seal part exists between the sensing element and the opening. The fixture fixes the sensing element while pressing the sensing element so that the elastic seal part elastically deforms. The light source and the photodetector exist outside the airtight space in which the measurement target exists. Light from the light source that passes through one of the two leg surfaces is incident on the sensing film. The reflected light from the sensing film exits from the other of the two leg surfaces. The photodetector detects the reflected light from the sensing film that exits from the other of the two leg surfaces. Effect of the Invention

[0007] According to one aspect of the present disclosure, a sensing element including a prism can be used to adequately measure a target fluid. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram for explaining a method of measuring hydrogen gas in a hydrogen gas sensor device according to an embodiment of the present specification. FIG. [Diagram 2] 1 illustrates a schematic configuration example of a hydrogen gas sensor device according to an embodiment of the present specification. [Figure 3A] FIG. 2 is a diagram for explaining the structure of a prism. [Figure 3B] FIG. 2 is a diagram for explaining the structure of a prism. [Figure 4] FIG. 1 is a cross-sectional view illustrating a schematic configuration example of a sensing element according to an embodiment of the present specification. [Diagram 5] FIG. 1 is a cross-sectional view illustrating a schematic configuration example of a sensing element according to an embodiment of the present specification. [Figure 6] 1A and 1B show an example of the configuration and use of a hydrogen gas sensor device according to an embodiment of the present specification. [Figure 7A] 1 shows an example of an airtight structure assembly using a sensing element in a hydrogen gas sensing device, and an example of assembling the same. [Figure 7B] 1 shows an example of an airtight structure assembly using a sensing element in a hydrogen gas sensing device, and an example of assembling the same. [Figure 7C] 1 shows an example of an airtight structure assembly using a sensing element in a hydrogen gas sensing device, and an example of assembling the same. [Figure 7D] 1 shows an example of an airtight structure assembly using a sensing element in a hydrogen gas sensing device, and an example of assembling the same. [Figure 8A] 1 shows an example of an assembly including a flow path block and a sensing element holder attached to the flow path block, and an example of assembling the assembly. [Figure 8B] 1 shows an example of an assembly including a flow path block and a sensing element holder attached to the flow path block, and an example of assembling the assembly. [Figure 8C] 1 shows an example of an assembly including a flow path block and a sensing element holder attached to the flow path block, and an example of assembling the assembly. [Figure 9A] FIG. 2 is an exploded perspective view showing cross sections of a flange, a sensing element, and a sensing element holder. [Figure 9B] The figure shows the flange being pressed and fixed to the sensing element holder by screws. [Figure 10A] 1 shows a cross-sectional view of the flange, the sensing element, the O-ring, and the sensing element holder before assembly. [Figure 10B]13 is a cross-sectional view of a state in which the flange, sensing element, and O-ring are assembled into the sensing element holder, and the flange has not yet been fixed to the sensing element holder with screws. [Figure 10C] 13 is a cross-sectional view showing a state in which the flange is pressed and fixed to the sensing element holder by a screw. [Figure 11] FIG. 13 is a diagram showing a portion where an O-ring is used to seal between a prism of a sensing element and a surface of a sensing element holder. [Figure 12A] 4 shows an example of a region of a laminated film formed on the slanting surface of a prism. [Figure 12B] 12B shows a state in which the sensing element shown in FIG. 12A is attached to a sensing element holder. [Figure 12C] The figure shows a state in which the flange that presses and fixes the detection element is fixed to the detection element holder with screws. [Figure 13A] 2 shows an example of the structure of a detector element. [Figure 13B] The detector element and the O-ring fitted to the side of the detector element are shown. [Figure 14A] 13A and 13B are diagrams illustrating an example of a configuration in which a sensing element having a prism in a truncated cone shape is fixed as a part of a partition wall. [Figure 14B] 13A and 13B are diagrams illustrating an example of a configuration in which a sensing element having a prism in a truncated cone shape is fixed as a part of a partition wall. [Figure 15A] The O-ring, optical element, and flange are placed on the detection element holder in this order, and the O-ring state before the flange is fixed with screws is shown. [Figure 15B] The figure shows the flange fixed to the sensing element holder by screws. [Figure 16A] FIG. 2 is an exploded perspective view showing a cross section of a component of the airtight structure of the present embodiment. [Figure 16B] This shows the state before the fixture is fixed with the screws. [Figure 16C] The figure shows the fixture being pressed and fixed to the bulkhead by a screw. [Figure 17A] The cross-sectional view of the screws, fixtures, prism, transparent plate, O-ring and bulkhead before assembly is shown. [Figure 17B]The fixture is shown secured to the bulkhead by a screw. [Figure 18A] FIG. 2 is a cross-sectional view illustrating a sealing structure using an O-ring. [Figure 18B] FIG. 2 is a cross-sectional view illustrating a sealing structure using an O-ring. [Figure 19] An example of a region of a laminated film formed on an oblique surface 181 of a prism is shown. [Figure 20A] 1 shows a schematic diagram of an airtight structure according to a first embodiment. [Figure 20B] 13 illustrates a schematic diagram of an airtight structure according to a second embodiment. [Figure 20C] 13 shows a schematic diagram of an airtight structure according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The size and scale of each component in each drawing are appropriately changed to ensure the visibility of the drawing. Furthermore, hatching in each drawing is for distinguishing each component, and does not necessarily mean a cut surface. It should be noted that this embodiment is merely an example for realizing the present disclosure, and does not limit the technical scope of the present disclosure.

[0010] In the following, an embodiment of a gas sensor device will be described as an example of an optical chemical sensor device. The gas sensor device of the embodiment of this specification detects a detection target by measuring a change in the optical properties of a detection film that comes into contact with the detection target.

[0011] A gas detection element in which a single-layer or multi-layer gas detection film is formed on a transparent substrate including a prism can be used, for example, in devices for generating, refining, and compounding gas. To be used in these devices, it is required to prevent the measurement target gas, which has a pressure higher than atmospheric pressure, from leaking to the outside, or to prevent the air from entering a space in which the measurement target gas, which has a pressure higher than atmospheric pressure, exists. For measurement, the gas detection film of the gas detection element must be present in the measurement target gas. On the other hand, for safety, components that require electrical current, such as a light source and a photodetector, are placed outside the measurement target atmosphere. Therefore, the light for measurement needs to pass through an airtight partition.

[0012] In one aspect of the present disclosure, a detection element including a prism is used as part of a partition wall of an airtight space in which a measurement target exists, thereby enabling measurement light to be irradiated from outside the airtight space onto a detection film exposed to the measurement target, and realizing a compact device. <Embodiment 1>

[0013] 1 is a schematic diagram for explaining a method for measuring hydrogen gas in a hydrogen gas sensor device according to an embodiment of the present specification. As described later, in an embodiment of the present specification, a hydrogen gas sensing element is fixed so as to cover an opening of a partition wall that confines hydrogen gas. The sensing element includes a sensing film formed on a transparent substrate, and the transparent substrate includes a prism. The sensing element constitutes a part of an airtight structure (partition wall) between the hydrogen atmosphere and the outside world, and a gap between the transparent substrate and other parts of the partition wall is sealed by a seal part.

[0014] The hydrogen gas sensor device is an example of an optical chemical sensor system, and the object to be detected is hydrogen gas. The hydrogen gas sensor device can detect the hydrogen gas concentration. The single arrow in the figure indicates the optical path, and the hydrogen gas sensor device is based on an oblique incidence optical system.

[0015] The hydrogen gas sensor device includes a light source 11, a polarization separation element (polarization separator) 13, a sensing element 14, a light detection device 17, and a detection control device 40. The incident optical system includes the light source 11 and the polarization separation element 13. The detection control device 40 controls the other components of the hydrogen gas sensor device, and also measures the intensity of reflected light by the sensing element 14 and calculates a measurement value based on the intensity of reflected light.

[0016] The detection element 14 includes a transparent flat plate 141 and a laminated film 140 formed on the transparent flat plate 141. The laminated film 140 is a hydrogen gas detection laminated film, and includes a half mirror layer 142, an optical interference layer 143, and a hydrogen gas detection layer 144, which are laminated from the transparent flat plate 141 side. Note that the configuration of the laminated film 140 is just an example, and any material may be used, and the number of layers may be any number greater than or equal to 1.

[0017] A prism 146 is provided on the opposite side of the transparent flat plate 141 to the laminated film 140, and is optically coupled to the transparent flat plate 141 by optical coupling oil (not shown) or the like. The prism 146 reduces the reflection of incident light on the rear surface of the transparent flat plate 141 on which the laminated film 140 is not formed and directed toward the photodetector.

[0018] The surface of the hydrogen gas detection layer 144 is in contact with the hydrogen gas 30, which is the detection target. The hydrogen gas sensor device detects hydrogen gas by measuring a change in the optical properties of the detection element 14 caused by the hydrogen gas 30. More specifically, the hydrogen gas concentration is detected by measuring the difference in reflectance of p-polarized light and s-polarized light by the laminated film 140 according to the hydrogen gas concentration.

[0019] 1, the hydrogen gas sensor device irradiates light obliquely through a prism 146 onto the laminated film 140 from the rear side of a transparent flat plate 141 on which the laminated film 140 for detecting hydrogen gas 30 is not formed. The light detection device 17 detects the reflected p-polarized light 32p and the reflected s-polarized light 32s, and the detection control device 40 determines the hydrogen concentration based on the difference in intensity between them. As will be described later, the difference in intensity can be expressed by a function that uses, for example, a difference or a ratio.

[0020] The laminated film 140 has a structure in which light reflected at the interface between the half mirror layer 142 and the transparent flat plate 141 interferes with light that penetrates the inside and is reflected by the hydrogen gas detection layer 144. For ease of illustration, the light reflected at the interface between the half mirror layer 142 and the transparent flat plate 141 is not shown in FIG. 1. This is the same in other figures. In the hydrogen gas sensor device, light emitted from the light source 11 is incident on the detection element 14 from an oblique direction relative to the film surface of the laminated film. In an oblique incidence optical system, the reflectance of p-polarized light and s-polarized light generally differs. Furthermore, in a laminated film such as that in the embodiment of the present disclosure, the effects of different interference conditions are superimposed on each other for p-polarized light and s-polarized light.

[0021] The behavior of the reflection of p-polarized light and s-polarized light in the laminated film 140, which is a combination of these, is reflected in the reflectance of p-polarized light and s-polarized light. What can actually be detected by the photodetectors 171 and 172 is the intensity of the reflected p-polarized light 32p and the reflected s-polarized light 32s. At this time, the intensity of the incident p-polarized light 31p and the incident s-polarized light 31s is a constant ratio because the light from one light source 11 is separated by the polarization separation element 13. Therefore, the reflectance of p-polarized light and s-polarized light can be obtained as the ratio between the intensity ratio of the reflected p-polarized light 32p and the reflected s-polarized light 32s. Furthermore, even if the intensity of the light emitted from the light source fluctuates, the effect of this can be eliminated.

[0022] The light source 11 emits light that is incident on a laminated film 140 formed on a transparent flat plate 141 via a prism 146. As the light source 11, a monochromatic light source that emits light of a single wavelength, such as a semiconductor laser, an LED, or a gas laser, can be used.

[0023] The polarization separation element 13 is disposed on the optical path between the light source 11 and the sensing element 14. The polarization separation element 13 separates the light from the light source 11 into p-polarized light 31p and s-polarized light 31s. The p-polarized light 31p and the s-polarized light 31s are incident lights on the sensing element 14. The p-polarized light 31p and the s-polarized light 31s are incident on different positions of the sensing element 14 via different optical paths.

[0024] The p-polarized light 31p and the s-polarized light 31s separated by the polarization separation element 13 travel along different optical paths and pass through the prism 146 to enter the rear surface of the transparent flat plate 141 on which the laminated film 140 is not formed. The incidence direction is oblique to the lamination direction of the laminated film 140 (the normal direction of the transparent flat plate 141). The angle is, for example, 45°.

[0025] A portion of the p-polarized light 31p and s-polarized light 31s incident on the laminated film 140 is reflected at the interface between the half mirror layer 142 and the transparent flat plate 141. The remaining portion is transmitted through the half mirror layer 142, passes through the optical interference layer 143, is reflected by the chemical detection layer 144, passes through the optical interference layer 143 again in the opposite direction, and then transmits through the half mirror layer 142 to interfere with the light reflected at the interface between the half mirror layer 142 and the transparent flat plate 141 described above.

[0026] At this time, p-polarized light and s-polarized light have different interference conditions. The laminated film 140 is set so that the interference of p-polarized light or s-polarized light is close to the resonance condition for the wavelength of the light emitted by the light source 11 used for detection. The reflected light intensity of the polarization component close to the resonance condition is extremely small due to interference. On the other hand, the reflected light intensity of the polarization component that does not meet the resonance condition is relatively large.

[0027] The p-polarized light 32p and the s-polarized light 32s reflected by the sensing element 14 travel along different optical paths. The reflected p-polarized light 32p and the reflected s-polarized light 32s are detected by a first photodetector 171 and a second photodetector 172, respectively. The first photodetector 171 and the second photodetector 172 are components of the detection device 17 and are installed at different positions. The first photodetector 171 and the second photodetector 172 are located on the optical paths of the reflected p-polarized light 32p and the reflected s-polarized light 32s, respectively, and detect the intensities of the reflected p-polarized light 32p and the reflected s-polarized light 32s, respectively.

[0028] The detection control device 40 controls the light emission of the light source 11, and receives detection signals from the first photodetector 171 and the second photodetector 172. The detection control device 40 receives signals indicating the intensities of the reflected p-polarized light 32p and the reflected s-polarized light 32s from the first photodetector 171 and the second photodetector 172. The detection control device 40 calculates the hydrogen gas concentration based on the comparison result.

[0029] For example, the detection control device 40 uses a preset function (including a lookup table) to determine the hydrogen concentration from the intensities of the reflected p-polarized light 32p and the reflected s-polarized light 32s. The function can include, for example, the ratio of the p-polarized light intensity to the s-polarized light intensity as a variable. When the ratio of the p-polarized light component to the s-polarized light component on the incident side is kept constant, the fluctuation in the intensity of the light emitted from the light source 11 can be eliminated by taking the ratio of the reflected light intensities of the p-polarized light and the s-polarized light.

[0030] 1, the detection element 14 includes a laminated film 140 in which a half mirror layer 142, an optical interference layer 143, and a hydrogen gas detection layer 144 are laminated in this order on a transparent flat plate 141. Each of these layers is composed of a single layer or multiple layers. The hydrogen gas detection layer 144 is composed of an appropriate material depending on the object to be detected.

[0031] The hydrogen gas sensing layer 144 changes its optical properties, such as its refractive index and absorption coefficient, upon contact with hydrogen gas. The hydrogen gas sensor device detects hydrogen gas by measuring the change in intensity of the reflected p-polarized and s-polarized light that occurs due to the change in the optical properties of the hydrogen gas sensing layer 144.

[0032] The optical interference layer 143 is an intermediate layer, and has a structure in which, of the light irradiated to the laminated film 140, the light reflected at the interface between the half mirror layer 142 and the transparent flat plate 141 interferes with the light that penetrates inside and is reflected by the hydrogen gas detection layer 144. For example, the value obtained by multiplying and adding the thicknesses and refractive indices of the half mirror layer 142 and the optical interference layer 143 is greater than approximately ¼ of the wavelength of the irradiated light.

[0033] The half mirror layer 142 reflects a portion of the incident light and transmits a portion of it. The half mirror layer 142 has a thickness that allows the light irradiated to the laminated film 140 to penetrate into the laminated film 140. For example, the half mirror layer 142 can have a thickness greater than 0 nm and equal to or less than 30 nm. The hydrogen gas detection layer 144 has a thickness sufficient to reflect the light that penetrates into the laminated film 140, and can have a thickness of, for example, 20 nm or more. By increasing the thickness of the hydrogen gas detection layer 144, the influence of fluctuations in the surface state of the detection layer can be reduced, enabling more stable detection of the detection target.

[0034] The hydrogen gas sensing layer 144 may be made of any material whose optical properties, such as refractive index or absorption coefficient, change when it reacts with hydrogen gas. As an example, a thin film containing Pd (palladium), whose optical properties change significantly when it comes into contact with hydrogen gas, may be used. In this case, since Pd has the ability to absorb and release hydrogen gas at room temperature, it is possible to provide a hydrogen gas sensor that can operate at room temperature and has high detection sensitivity.

[0035] Examples of materials used for the optical interference layer 143 include general transparent oxides, transparent nitrides, and transparent fluorides such as SiO2 (silicon dioxide), ZnO (zinc oxide), MgO (magnesium oxide), TiO2 (titanium oxide), AlN (aluminum nitride), Si3N4 (silicon nitride), and MgF2 (magnesium fluoride). The optical interference layer 143 may be a dielectric material having high transmittance for the wavelength of light irradiated from the light source 11.

[0036] Examples of materials used for the half mirror layer 142 include general metal materials such as metals such as Ag (silver), Al (aluminum), Au (gold), Cu (copper), and Ta (tantalum), and alloys containing these metals. The material of the half mirror layer 142 may have high reflectance at the wavelength of light irradiated from the light source 11. The transparent flat plate 141 is, for example, a glass substrate of about 0.5 mm (500 μm).

[0037] As described above, the hydrogen gas sensor device irradiates the back surface of the laminated film 140 with light, and detects the p-polarized light and s-polarized light reflected by the laminated film 140. The hydrogen gas sensor device detects a change in the optical properties of the hydrogen gas sensing layer 144 due to contact with hydrogen gas 30 as an optical signal indicating a change in intensity of the p-polarized light and s-polarized light reflected by the laminated film 140, thereby detecting hydrogen gas.

[0038] When hydrogen gas comes into contact with the hydrogen gas sensing layer 144, the optical properties of the hydrogen gas sensing layer 144 change, and the interference conditions of the laminated film 140 change accordingly. The interference conditions change differently for p-polarized light and s-polarized light, and in particular the reflectance of the polarized light component near the resonance condition changes significantly due to the change in the optical properties of the hydrogen gas sensing layer 144 coming into contact with hydrogen. As a result, the ratio of the reflected light intensities of p-polarized light and s-polarized light changes significantly. In this way, the optical signal can be greatly enhanced by the interference of light generated in the laminated film 140, and hydrogen gas can be detected with high sensitivity. The same is true for other detection objects and laminated films of chemical sensing layers.

[0039] 2 is a schematic diagram showing a configuration example of a hydrogen gas sensor device according to an embodiment of the present specification. The following mainly describes the differences from the configuration example shown in FIG. 1. The hydrogen gas sensor device, like the configuration example shown in FIG. 1, is based on an oblique incidence optical system, and detects hydrogen gas by irradiating light from an oblique direction through a prism 146 onto the back surface of a transparent flat plate 141 on which a laminated film 140 for detecting hydrogen gas is not formed. The sensing element 14 has a structure similar to that of the configuration example shown in FIG. 1.

[0040] The incident optical system includes a light source 11 and a polarizer 12. The polarizer 12 is disposed on the optical path of the incident light 31 between the light source 11 and the detection element 14. The polarizer 12 passes linearly polarized light in a specific direction and attenuates polarized light in other directions. The polarizer 12 may be adjusted in advance so that the difference in intensity between the reflected p-polarized light and the reflected s-polarized light in the measurement range of hydrogen concentration is within a predetermined range. For example, the rotation angle of the polarizer 12 may be adjusted so that the intensities of the reflected p-polarized light and the reflected s-polarized light are approximately the same when hydrogen gas is not present. In this way, the measurement accuracy can be improved by appropriately adjusting the rotation angle of the polarizer 12. The polarizer 12 may be omitted.

[0041] Furthermore, a polarization separator 15 is disposed on the optical path between the sensing element 14 and the photodetector. In Fig. 2, for ease of illustration, the frame indicating the photodetector 17 shown in Fig. 1 is omitted, but similar to the configuration example in Fig. 1, the photodetector 17 includes a first photodetector 171 and a second photodetector 172. The polarization separator 15 separates the p-polarized light 32p and the s-polarized light 32s from the light reflected by the sensing element 14. The p-polarized light 32p and the s-polarized light 32s from the polarization separator 15 travel along different optical paths.

[0042] Linearly polarized light 31 that has passed through polarizer 12 from light source 11 is incident on stacked film 140 of detector element 14 via prism 146, with the intensity ratio of p-polarized light component and s-polarized light component corresponding to the polarization angle. As described above, linearly polarized light 31 is incident on stacked film 140 at an angle inclined with respect to the normal direction of stacked film 140. Unlike FIG. 1, the incident light is not separated into p-polarized light and s-polarized light, and linearly polarized light 31 is incident at a single point. This makes it possible to avoid the influence of differences in characteristics within the plane of stacked film 140.

[0043] The p-polarized light (component) and s-polarized light (component) of the incident light interfere under different interference conditions in the laminate film 140. In addition, the optical characteristics of the hydrogen gas detection layer 144 change due to the hydrogen gas 30, so that the reflectance of the p-polarized light and s-polarized light in the hydrogen gas detection layer 144 and the interference conditions of the laminate film 140 change. As a result, the ratio of the reflected light intensities of the p-polarized light and the s-polarized light by the laminate film 140 changes significantly.

[0044] The light reflected by the laminated film 140 enters the polarization separator 15 and is split into p-polarized light 32p and s-polarized light 32s. These travel different optical paths. The first photodetector 171 receives the p-polarized light 32p and outputs its intensity to the detection control device 40. The second photodetector 172 receives the s-polarized light 32s and outputs its intensity to the detection control device 40. In this way, by splitting the light reflected by the sensing element 14 into p-polarized light and s-polarized light, detecting the light intensities of each, and taking the ratio, it is possible to eliminate fluctuations in the light intensity of the light source.

[0045] 3A and 3B are diagrams for explaining the structure of prism 146. Prism 146 is a right-angled triangular prism. Note that the structure of prism 146 is not limited to the structure shown in Figures 3A and 3B. In addition, the angle between the incident light and the reflected light to prism 146 is not limited to 90°.

[0046] 3A and 3B, the prism 146 has an inclined surface 181 and two leg surfaces 182 and 183 that sandwich the inclined surface 181. The inclined surface 181 is connected to each of the two leg surfaces 182 and 183. The angle between the leg surfaces 182 and 183 is a right angle, and the angle between the leg surfaces 182 and 183 and the inclined surface 181 is 45 degrees. The transparent flat plate 141 on which the laminated film 140 is formed is placed on the inclined surface 181. The other two surfaces between the inclined surface 181 and the leg surfaces 182 and 183 are the top and bottom surfaces of the triangular prism.

[0047] 4 is a cross-sectional view showing a schematic configuration example of a detector element 250 according to an embodiment of the present specification. The detector element 250 includes a laminated film 260 for detecting hydrogen gas on a transparent flat plate 251 made of glass. The laminated film 260 is composed of a half mirror layer 253, an optical interference layer 254, and a hydrogen gas detection layer 255. The seed layer 252, the half mirror layer 253, the optical interference layer 254, and the hydrogen gas detection layer 255 are laminated on the transparent flat plate 251 in this order.

[0048] The half mirror layer 253 is composed of a 14 nm thick Ag thin film. The optical interference layer 254 is composed of a laminated film consisting of a 30 nm thick ZnO thin film and a 143 nm thick Al2O3 thin film. The hydrogen gas detection layer 255 is composed of a 100 nm thick PdCuSi alloy thin film. The seed layer 252 is composed of a 30 nm thick ZnO thin film. The seed layer 252 maintains adhesion to the transparent plate 251.

[0049] On the rear surface of the transparent flat plate 251 on which the laminated film 260 is not formed, a prism 256 is optically coupled to the transparent flat plate 251 by optical coupling oil 257. The prism 256 can suppress the influence of light reflection on the rear surface of the transparent flat plate 251. The optical coupling oil 257 reduces light reflection at the interface between the transparent flat plate 251 and the prism 256.

[0050] FIG. 5 is a cross-sectional view showing a schematic configuration example of the sensing element 270 according to an embodiment of the present specification. The sensing element 270 has a structure in which the transparent flat plate 251 and the optical coupling oil 257 are removed from the sensing element 250 shown in FIG. 4. In this example, a laminated film is formed directly on the inclined surface of the prism 256 without using thin glass. The thin glass is no longer present in the portion that receives pressure for fixing the sensing element 270, and the mechanical strength of the sensing element is increased. In addition, contamination of the gas to be measured can be avoided because immersion oil is not required. On the other hand, the manufacturing of the sensing element 250 in which a film is formed on the transparent flat plate 251 can be performed more easily and efficiently than the manufacturing of the sensing element 270 in which a film is formed on the prism 256, because the substrate can be easily held during the formation of the laminated film.

[0051] In the gas sensor device according to the embodiment of the present specification described below, the sensing element 14 may have the configuration described with reference to Fig. 4 or 5 or another configuration. For example, the seed layer may be omitted, and a protective layer having a catalytic effect for protecting the surface of the hydrogen gas sensing layer 255 and / or promoting the reaction may be formed on the surface of the hydrogen gas sensing layer 255. Also, each layer may be composed of multiple layers rather than a single layer. Furthermore, an anti-reflection film may be formed on the leg surface of the prism 256.

[0052] FIG. 6 shows a configuration example of a hydrogen gas sensor device according to an embodiment of the present specification and an example of its use. In FIG. 6, the hydrogen gas sensor device is inserted into a pipe 315 through which a gas to be measured flows, and the hydrogen concentration in the gas to be measured flowing through a gas flow path 310 of the hydrogen gas sensor device is measured. The gas to be measured is a gas that contains or may contain hydrogen, and the space in the gas flow path 310 may be pressurized or depressurized depending on the application, that is, the pressure in the gas flow path 310 may be equal to atmospheric pressure or higher or lower than atmospheric pressure. Gas containing hydrogen gas, or gas that contains or may contain hydrogen, flows through the gas flow path 310. The hydrogen gas sensor device has an optical system of the configuration example described with reference to FIG. 2, and some configurations of the configuration example shown in FIG. 2 are omitted, and further includes configuration examples not shown in FIG. 2.

[0053] In the gas flow path 310, a partition wall is formed from the outside world by a flow path block 320 and a detection element holder 350 on which the detection element 14 is mounted, which separate the space inside the gas flow path 310 and the gas flowing therein from the outside world. In Fig. 6, the flow path block 320 and the detection element holder 350, which are elements constituting the two partition walls, are indicated by reference numerals. The flow path block 320 and the detection element holder 350 may be made of, for example, metal or resin.

[0054] The sensing element holder 350 is plate-shaped, and the sensing element 14 is fitted into a recess formed in the sensing element holder 350. The sensing element 14 is pressed and fixed to the sensing element holder 350 by a flange 360. The flange 360 ​​is fixed to the sensing element holder 350 by, for example, a screw. Note that in this specification, the screw includes a bolt. Through a hole in the flange 360, the laminated film 140 of the sensing element 14 is exposed in the gas flow passage 310. The hole is a through hole. Light from the light source 11 is irradiated to the sensing element 14 through a hole 351 in the sensing element holder 350. The reflected light from the sensing element 14 enters the polarization separator 15 through another hole 352 in the sensing element holder 350.

[0055] The detection element holder 350 is fixed to the flow path block 320 by, for example, screws. The flange 360 ​​is fixed to a surface of the detection element holder 350 facing the flow path block 320. An O-ring 370 is sandwiched between the detection element holder 350 and the flow path block 320. The O-ring 370 surrounds the flange 360. The O-ring 370 seals the gap between the flow path block 320 and the detection element holder 350, and prevents gas leakage from the gas flow path 310 or inflow of outside air into the gas flow path 310. Note that all O-rings described below are examples of elastic seal parts.

[0056] 7A to 7D show an example of an airtight structure assembly using sensing element 14 and its assembly in a hydrogen gas detection device. Fig. 7A shows an example of the structure of sensing element holder 350. Fig. 7A is a view of sensing element holder 350 as seen from the side facing flow path block 320.

[0057] The detector element holder 350 has a recess 356 on a surface facing the flow path block 320. The detector element 14 is fitted in the recess 356. The openings of holes 351 and 352 that form a part of the optical path for measurement are formed on the inner surface of the recess 356. The recess 356 is penetrated to the outside of the flow path by the holes 351 and 352. The surface on which the openings of the holes 351 and 352 are formed is a surface that is parallel to the leg surfaces 182 and 183 of the prism 146 and is oblique to the opposing surface of the partition. The other two inner surfaces of the approximately triangular shape between them are also perpendicular to the opposing surface of the partition in accordance with the shapes of the other surfaces of the prism 146.

[0058] The sensing element 14 is disposed in the recess 356 such that the leg surfaces 182, 183 of the sensing element 14 cover the holes 351, 352, respectively. Recessed surfaces (steps) 352, 354 are formed around the openings of the holes 351, 352. The surfaces 353, 354 are sealing surfaces that are sealed by an O-ring. Thus, the recess 356 includes a triangular prism-shaped space that houses the sensing element 14 including the prism, and a ring-shaped space that houses the O-ring. The holes 351, 352, the recess 356, and the sealing surfaces 353, 354 can be formed, for example, by cutting a metal plate.

[0059] FIG. 7B shows O-rings 371 and 372 arranged in the detection element holder 350 and the recess 356. The O-rings 371 and 372 are arranged on the sealing surface 353 of the hole 351 and the sealing surface 354 of the hole 352, respectively. For example, the inner diameter (diameter of the central hole) of the torus-shaped O-rings 371 and 372 is equal to or larger than the diameter of the holes 351 and 352, the outer diameter is equal to or smaller than the outer diameter of the step surfaces 353 and 354, and the wire diameter (thickness) is greater than the depth of the sealing surfaces 353 and 354, and the difference is within the range of the compression amount in which the sealing properties of the O-rings 371 and 372 are effectively exhibited. The cross section of the elastic ring for sealing does not have to be a circle like a general O-ring, and may be, for example, an ellipse or a rectangle. This point is similar to other embodiments.

[0060] 7C shows an example of the configuration of an assembly of the detection element holder 350 and the detection element 14 attached to the partition wall. The detection element 14 is fitted into a recess 356 formed in one main surface of the plate-shaped detection element holder 350. This surface faces the flow path block 320 and the gas flow path 310. Leg surfaces 182 and 183 (reference numbers not shown in FIG. 7C) of the detection element 14 face the inner surface of the recess 356, and a portion of each is exposed to the holes 351 and 352. The leg surfaces 182 and 183 are in contact with the O-rings 371 and 372, respectively. The inclined surface 181 is exposed on the side surface of the detection element holder 350 facing the flow path block 320. The area of ​​the inclined surface 181 exposed from the hole 363 is exposed to hydrogen gas in the gas flow path 310.

[0061] FIG. 7D shows a configuration example of an assembly including a flange 360 ​​in addition to the sensing element 14 and the sensing element holder 350. The flange 360 ​​is a ring-shaped plate with circular outer and inner circumferences and has a hole 363 in the center. The flange 360 ​​is fixed to the sensing element holder 350 by a plurality of screws 362. The screws 362 pass through mounting holes in the flange 360 ​​and are fixed to screw holes in the sensing element holder 350. The screw holes are blind holes. In FIGS. 7A to 7C, the screw holes in the sensing element holder 350 are omitted from the drawings to avoid complicating the drawings. In FIG. 7D, one screw is indicated by the reference numeral 362 as an example. The flange 360 ​​covers a part of the inclined surface 181, and all or a part of the laminated film 140 (not shown in FIG. 7D) of the sensing element 14 is exposed from the hole 363.

[0062] Flange 360 ​​is a fixture that fixes sensing element 14 while pressing sensing element 14 against sensing element holder 350. Recess 356 is formed so that when sensing element 14 is fitted without O-rings 371, 372 attached, the inclined surface of prism 146 is substantially flush with sensing element holder 350. O-rings 371, 372 in contact with leg surfaces 183, 184 and seal surfaces 353, 354 of sensing element holder 350 are compressed by the pressing of sensing element 14 by flange 360, and when sensing element 14 is fitted at a predetermined position in recess 356, the compression amount of the O-rings is sufficient to properly seal the gaps between leg surfaces 183, 184 and seal surfaces 353, 354.

[0063] Elastic seal parts such as O-rings properly seal gaps on the sealing surface by being compressed by other parts and collapsing their cross-sectional shape. "Collapse" here refers to the phenomenon in which the cross-sectional shape of the elastic seal part is elastically deformed by pressure, reducing the dimensions in the direction of pressure and expanding in other directions. The fixing device fixes the detection element while pressing it so that the elastic seal part is compressed and elastically deformed.

[0064] 8A, 8B, and 8C show an example of an assembly including a flow path block 320 and a detection element holder 350 attached to the flow path block, and an example of assembly thereof. Fig. 8A shows an example of the configuration of the flow path block 320, and Fig. 8B shows an example of the configuration of the flow path block 320 and an O-ring 370 disposed in the flow path block 320.

[0065] The flow path block 320 has a recess 323 and a hole that constitutes a part of the gas flow path 310 at its bottom surface. The flange 360 ​​described with reference to FIG. 7D is fitted into the recess 323. A recessed surface (step) 325 is formed on the outer periphery of the recess 323. The O-ring 370 is disposed on the recessed surface 325 provided on the outer periphery of the recess 323. This recessed surface 325 is a sealing surface, and the O-ring 370 is disposed on the sealing surface 325. For example, the inner diameter of the torus-shaped O-ring 370 is equal to or larger than the inner diameter of the sealing surface 325, the outer diameter is equal to or smaller than the outer diameter of the sealing surface 325, and the wire diameter (thickness) is larger than the depth of the sealing surface 325, and the difference is within the range of the compression amount at which the sealing property of the O-ring 370 is effectively exhibited. The cross section of the elastic ring for sealing does not have to be a circle like a general O-ring, and may be, for example, an ellipse or a rectangle.

[0066] 8C shows a configuration example of an assembly including the flow path block 320 and the detection element holder 350 fixed to the flow path block 320. The assembly including the detection element holder 350, the detection element 14, and the flange 360 ​​shown in FIG. 7D is assembled to the flow path block 320 so that the flange 360 ​​is inserted into the recess 323. The detection element holder 350 is fixed to the flow path block 320 by a plurality of screws 375. The screws 375 pass through mounting holes in the detection element holder 350 and are inserted into screw holes in the flow path block 320 and fixed. The screw holes are blind holes. In FIG. 8C, one screw is indicated by the reference numeral 375 as an example.

[0067] The inner diameter of O-ring 370 is larger than the outer diameter of flange 360, and the flange is disposed inside O-ring 370. O-ring 370 is compressed by detection element holder 350 to provide an appropriate seal between detection element holder 350 and flow path block 320, resulting in a structure corresponding to the cross-sectional view shown in FIG.

[0068] 8A to 8C is located in the recess 323 of the flow path block 320, and at least a part of the laminated film 140 on the inclined surface 181 of the detection element 14 is exposed to the gas flow path 310 through a hole 363 (see FIG. 7D) of the flange 360. In addition, light from the light source 11 enters the hole 351, and reflected light by the detection element 14 exits from the hole 352.

[0069] Next, the fixing of the detection element 14 by the flange 360 ​​and the detection element holder 350 will be described in more detail. Fig. 9A is an exploded perspective view showing cross sections of the flange 360, the detection element 14, and the detection element holder 350. The hydrogen gas to be measured is present on the upper side of Fig. 9A, and the outside world is on the lower side. Light from the light source 11 enters the detection element 14 through a hole 351, and the reflected light from the detection element 14 exits from a hole 352.

[0070] O-ring 371 is disposed on sealing surface 353 formed in recess 356 of sensing element holder 350. O-ring 372 is disposed on sealing surface 354 formed in recess 356 of sensing element holder 350. The inner periphery of sealing surface 353 defines the opening of hole 351, and the inner periphery of sealing surface 354 defines the opening of hole 352.

[0071] The sensing element 14 including the prism 146 is placed in the recess 356. The leg surface 182 faces the O-ring 371 and the hole 351 and is in contact with the O-ring 371. The leg surface 183 faces the O-ring 372 and the hole 352 and is in contact with the O-ring 372. The inclined surface 181 faces the opening side of the recess 356 (the side opposite to the bottom surface). The flange 360 ​​is assembled to the sensing element holder 350 so as to be in contact with a partial area of ​​the inclined surface 181.

[0072] When O-rings 371, 372, sensing element 14, and flange 360 ​​are simply assembled to sensing element holder 350 and placed in a predetermined position, inclined surface 181 of sensing element 14 protrudes above sensing element holder 350, and O-rings 371, 372 have not yet elastically deformed. As shown in Fig. 7D, by fixing flange 360 ​​to sensing element holder 350 with screws 362, O-rings 371, 372 are compressed between sensing element 14 and the surface of sensing element holder 350, and elastically deform, sealing the gap between them.

[0073] 9B shows a state in which flange 360 ​​is pressed and fixed to detection element holder 350 by screws 361 (not shown in FIG. 9B). Detection element 14 is pressed against flange 360 ​​and lowered to the inner surface (surface on the measurement target side) of recess 356 in detection element holder 350. At the same time, leg surfaces 182, 183 contact the upper surfaces of steps formed near O-rings 371, 372. At this time, the amount of compression of O-rings 371, 372 becomes appropriate.

[0074] Fig. 10A shows a cross-sectional view of flange 360, detection element 14, O-rings 371 and 372, and detection element holder 350 before assembly, and corresponds to Fig. 9A. In Fig. 10A, the upper region is the region where hydrogen gas exists, and the lower region is the region where the optical system is disposed.

[0075] 10B shows a cross-sectional view of the state before O-rings 371 and 372, sensing element 14, and flange 360 ​​are assembled into sensing element holder 350 and pressed and fixed by screw 361 (not shown in FIG. 10B). O-rings 371 and 372 are disposed on sealing surfaces 353 and 354, respectively. Sensing element 14 is disposed on O-rings 371 and 372. Leg surfaces 182 and 183 abut against O-rings 371 and 372, respectively. O-rings 371 and 372 are not compressed, and inclined surface 181 of the sensing element is located above the upper surface of sensing element holder 350 in FIG. 10A. Flange 360 ​​is disposed on inclined surface 181 so that a part of inclined surface 181 is exposed from hole 363.

[0076] 10C is a cross-sectional view showing a state in which flange 360 ​​is pressed and fixed to detection element holder 350 by screw 361 (not shown in FIG. 10C), and corresponds to FIG. 9B. Detection element 14 is pressed against flange 360 ​​and lowered to the inner surface (surface on the measurement target side) of recess 356 of detection element holder 350. At the same time, leg surfaces 182 and 183 contact the upper surface of a step formed near O-rings 371 and 372. At this time, O-rings 371 and 372 are crushed between leg surfaces 182 and 183 and the inner surface of recess 356, sealing the gap between leg surfaces 182 and 183 and the inner surface of recess 356.

[0077] 11 is a diagram of a portion where O-rings 371 and 372 are sealed between the prism 146 of the sensing element 14 and the surface of the sensing element holder 350. FIG. 11 shows a state after the flange 360 ​​is fixed to the sensing element holder 350.

[0078] Sloped surface 181 of sensing element 14 is pressed vertically downward in Fig. 11 by flange 360. The sealing surfaces of sensing element 14 are parts of leg surfaces 182, 183 inclined at 45° to slope 181, and the components of the pressing force press O-rings 371, 372 in two directions, respectively. As a result, the sealing surfaces of leg surfaces 182, 183 and sealing surfaces 353, 354 of sensing element holder 350 are sealed.

[0079] The general method of using an O-ring is to apply a tightening force in the direction of compression, but in this configuration example, a force in one direction different from the direction in which O-rings 371, 372 are compressed, and the O-rings 371, 372 in multiple directions are compressed and sealed simultaneously by the component forces.

[0080] Next, the deposition area of ​​the laminated film 140 on the inclined surface 181 of the prism 146 will be described. If the laminated film 140 is deposited without any particular consideration to the right-angle prism, the flange 360 ​​and the laminated film 140 will come into contact when fixed. If there is a place where the flange 360 ​​and the laminated film 140 come into contact, the film may be damaged at the contact portion. If damage occurs in even one place, it may affect the entire laminated film 140 from that point on. In one embodiment of the present specification, the laminated film 140 is deposited so as to avoid the area where the flange 360 ​​comes into contact and to cover the area that contributes to the measurement of hydrogen gas.

[0081] FIG. 12A shows an example of a region of the laminated film 140 formed on the inclined surface 181 of the prism 146. In FIG. 12A, the laminated film 140 is circular, but the shape is not particularly limited. The laminated film 140 may be directly formed on the inclined surface 181 of the prism 146, or the laminated film 140 may be formed on a glass plate, and the opposite surface of the glass plate may be bonded to the inclined surface 181 of the prism 148 by optical coupling oil. Sputtering is generally used for forming the laminated film 140, but in order to form the laminated film 140 on a part of the inclined surface 181 of the prism 146, a method of using a metal mask having an opening on the portion of the inclined surface 181 of the prism 146 where the laminated film is to be formed, when holding the prism during film formation, can be applied.

[0082] Fig. 12B shows a state in which the sensing element 14 shown in Fig. 12A is attached to a sensing element holder 350. Furthermore, Fig. 12C shows a state in which a flange 360 ​​that presses and fixes the sensing element 14 is fixed to the sensing element holder 350 with screws.

[0083] 12C, the entire area of ​​the laminate film 140 is accommodated within the central hole 363 of the flange 360. Since the laminate film 140 does not contact the flange 360, the laminate film 140 is not damaged by the flange 360, and peeling of the laminate film 140 from damaged areas can be prevented. <Embodiment 2>

[0084] Another structural example of a prism will be described. Fig. 13A shows a structural example of sensing element 44. Sensing element 44 has a shape in which a foot surface is formed on a truncated cone. That is, inclined surface 481 is the bottom surface of the truncated cone, and foot surfaces 482 and 483 are two flat inclined surfaces formed on the side surface of the truncated cone and perpendicular to each other at 45° with respect to inclined surface 481. A laminated film for measuring hydrogen gas is formed on inclined surface 481. Prism 446 of sensing element 44 shown in Fig. 13A is a right-angle prism.

[0085] FIG. 13B shows the sensing element 44 and an O-ring 470 fitted to the side of the sensing element 44. The O-ring 470 seals between the side of the truncated cone and the partition wall. The O-ring 470 is torus-shaped and has a circular cross section. The inner diameter of the O-ring 470 is smaller than the diameter of the inclined surface 481. In the configuration example shown in FIG. 13B, the O-ring 470 is disposed outside the leg surfaces 482 and 483, and is located between the leg surfaces 482 and 483 and the inclined surface 481. The cross section of the O-ring 470 does not have to be a circle. The ring shape of the O-ring 470 is the same as the outer peripheral shape of the side surface of the prism 446 of the sensing element 44. Therefore, if the outer periphery of the side surface of the sensing element 44 is, for example, an ellipse, the O-ring is also an elliptical ring.

[0086] 14A and 14B are cross-sectional views for explaining a configuration example in which sensing element 44 having a truncated cone-shaped prism is fixed as a part of a partition wall. Fig. 14A shows the configuration before sensing element 44 and flange 560 are assembled to sensing element holder 550. Sensing element 44 is pressed and fixed between flange 560 and plate-shaped sensing element holder 550. Sensing element holder 550 corresponds to sensing element holder 350 described above.

[0087] The flange 560 is fixed to the detection element holder 550 by a plurality of screws 575. The screws 575 pass through holes in the flange 560 and are inserted into screw holes in the detection element holder 550 to be fixed. The screw holes are blind holes. In Figs. 14A and 14B, one of the plurality of screws is indicated by reference numeral 575 as an example. The flange 560 may be disk-shaped with a hole 563 in the center, similar to the flange 360. The hydrogen gas to be measured is present on the upper side of Fig. 14A, and the outside world is on the lower side. Light from the light source 11 enters the detection element 44 through a hole 551, and the reflected light of the detection element 44 exits from a hole 552.

[0088] O-ring 470 is placed on sealing surface 553, which is the surface of a step formed in tapered hole 556 of detection element holder 350. Sealing surface 553 faces the flange 560 side. Sealing surface 553 is formed in a ring shape on the inner circumferential surface of hole 556. O-ring 470 is placed on sealing surface 553. The inner periphery of sealing surface 553 defines the mouth of a deeper space in hole 556 in which leg surfaces 482, 483 are housed.

[0089] 14A and 14B, hole 556 includes two spaces. The width of the space at a shallower position on the flange 560 side (upper side in FIG. 14A) is constant, and the space is cylindrical. The width of the space at a deeper position (lower side in FIG. 14A) gradually decreases from the flange 560 side, and the space is frustum-shaped. The inner surface of hole 556 that defines the frustum-shaped space is a tapered surface, and is approximately the same as the tapered surface that forms the side surface of the frustum-shaped prism 446.

[0090] The sensing element 44 including the prism 446 is disposed in the hole 556. The leg surface 482 faces the hole 551. The leg surface 483 faces the hole 552. The inclined surface 481 faces the opposite side to the holes 551 and 552. The flange 560 is assembled to the sensing element holder 550 so as to contact a partial area of ​​the inclined surface 481. The laminated film of the sensing element 44 is exposed from the hole 563 of the flange 560.

[0091] When the O-ring 470, the sensing element 44 and the flange 560 are simply assembled to the sensing element holder 550 and placed in the specified position, the inclined surface 481 of the sensing element 44 protrudes above the sensing element holder 550 and the O-ring 470 is not yet compressed.

[0092] 14B shows a state in which the flange 560 is fixed to the sensing element holder 550 by the screw 575. The side surface of the prism 446 covers the opening (the opening between the shallow space and the deep space) of the space at a deeper position (lower side in FIG. 14A) in the hole 556. The O-ring 470 surrounds the opening between the side surface of the prism 446 and the inner surface of the hole 556 of the sensing element holder 550. By fixing the flange 560 to the sensing element holder 550 by the screw 575, the O-ring 470 is pressed between the side surface of the prism 446 and the surface inside the hole 556 of the sensing element holder 550, sealing the gap between them.

[0093] 15A shows the state of O-ring 470 after O-ring 470, sensing element 44, and flange 560 are placed on sensing element holder 550 in this order, and before flange 560 is fixed with screw 575. O-ring 470 is surrounded by surfaces 553, 554 of hole 556 in sensing element holder 550 and part 485 of the side surface of prism 446. As described above, O-ring 470 is placed on sealing surface 553, and then prism 446 is inserted into hole 556. Flange 560 is placed on top of prism 446. O-ring 470 is not yet compressed.

[0094] 15B shows a state in which the flange 560 is fixed to the detection element holder 550 by the screw 575. The O-ring 470 is in contact with the sealing surfaces 553, 554, and 485 and is pressed and compressed by them. This allows the O-ring 470 to perform a sealing function. <Embodiment 3>

[0095] Another embodiment of the airtight structure using a sensing element including a prism will be described. The structure of the prism is the same as that of the first embodiment. FIG. 16A is an exploded perspective view showing a cross section of the components of the airtight structure of this embodiment. The airtight structure includes a fixture 660, a prism 146 and a transparent plate 141 of the sensing element 14, a partition wall 650, and an O-ring 670. The hydrogen gas to be measured is present on the lower side of FIG. 16A, and the upper side is the outside world. In the following description, the sensing element 14 includes the transparent plate 141, but in other examples, the transparent plate 141 may be omitted and the laminated film 140 may be directly formed on the inclined surface of the prism.

[0096] Fig. 16A shows half of the airtight structure. Therefore, a structure that is the same as the structure shown in Fig. 16A and is plane-symmetric with respect to the cross section may exist on the opposite side. That is, the prism 146 may be fixed to the partition wall 650 by a single fixture 660. The number of fixtures 660 may be two or more.

[0097] O-ring 670 is placed on sealing surface 652 of a step formed in hole 656 of partition wall 650. The step formed between sealing surface 652 and support surface 654 is smaller than the wire diameter of O-ring 670, and the difference is set to be within the range of the amount of compression where the seal of O-ring 670 effectively works.

[0098] The sensing element 14 including the prism 146 and the transparent flat plate 141 is disposed on the O-ring 670 in the hole 656 of the partition wall 650. The transparent flat plate 141 contacts the O-ring 670. The leg surfaces 182 and 183 face the side opposite to the sealing surface 652 of the partition wall 650, i.e., toward the outside world. A part of the hole 656 constitutes a part of the gas flow path.

[0099] Fixture 660 is disposed on prism 146 and partition wall 650 so as to cover a portion of prism 146, specifically a portion of each of leg surfaces 182, 183. The surface of fixture 660 facing prism 146 has a shape that fits into the corners of leg surfaces 182, 183 of prism 146, and is in surface contact with a portion of leg surfaces 182, 183. Furthermore, screw 675 passes through a hole in fixture 660 and is inserted into a screw hole in partition wall 650.

[0100] 16B shows the state before fastener 660 is fixed by screw 675. O-ring 670 is not yet compressed just by assembling O-ring 670, sensing element 14, and fastener 660 to partition wall 650 and placing them in a predetermined position. By fixing fastener 660 to partition wall 650 with screw 675, O-ring 670 is compressed between sensing element 14 and the surface of partition wall 650, and the gap between them is sealed.

[0101] 16C shows a state in which the fixture 660 is pressed and fixed to the partition wall 650 by the screw 675. The transparent substrate including the prism 146 and the transparent flat plate 141 is fixed in a predetermined position as shown in FIG. 16C. The transparent substrate including the prism 146 and the transparent flat plate 141 is pressed against the O-ring 670 by the fixture 660. At this time, the O-ring 670 is compressed between the transparent flat plate 141 of the transparent substrate and the sealing surface 652. When the transparent flat plate is in contact with the support surface 654 and fixed in a predetermined position, the compression amount of the O-ring 670 becomes appropriate, and the gap between the inner surface of the hole 656 and the sensing element 14 is sealed.

[0102] The optical paths of the light 31 incident on the leg surface 182 and the light 32 reflected from the leg surface 183 pass through the space between the fixture 660 and the partition wall 650. In this manner, the airtight structure is designed so that the optical path for measurement is not blocked by components. In FIG. 16C, the space below the transparent plate 141 in the hole 656 is an airtight space in which hydrogen gas exists. The airtightness is maintained by an O-ring 670. The laminated film 140 on the transparent plate 141 is exposed to hydrogen gas inside the O-ring 670 in the hole 656.

[0103] Fig. 17A shows a cross-sectional view of the screw 675, the fixture 660, the prism 146, the transparent plate 141, the O-ring 670, and the partition wall 650 before assembly. In Fig. 17A, the lower region is a region where hydrogen gas exists, and the upper region is a region where the optical system is disposed.

[0104] Hole 656 of partition wall 650 includes three spaces with different shapes from the top to the bottom in Fig. 17A. The uppermost space, i.e., the space on the fixing device 660 side, accommodates (a part of) sensing element 14 including prism 146 and transparent plate 141. As shown in Fig. 16A and Fig. 17A, the space accommodating sensing element 14 has a substantially rectangular parallelepiped shape.

[0105] The second space is a rounded rectangular columnar space that accommodates the O-ring 670. Here, in order to make the opening of the rectangular sensing element film surface facing the measurement target large, the cross section is made rectangular with rounded corners and the O-ring is fitted along it, but it may be circular or elliptical. When viewed from the side of the fixture 660, this space is accommodated within the space that accommodates the sensing element 14. The lowest space is a rounded rectangular columnar shape that constitutes a part of the gas flow path 310. The opening shape of this space is similar to the opening shape of the space that accommodates the O-ring 670, for example. When viewed from the side of the fixture 660, this space is accommodated within the space that accommodates the O-ring 670. Note that the shape of the space that includes the hole 656 is not limited to these.

[0106] The O-ring 670 is disposed on the sealing surface 652. In addition to the sealing surface 652, a support surface 654 is formed on the inner surface of the hole 656. As described below, the support surface 654 supports the detection element 14. These surfaces 652, 654 face the transparent flat plate 141 or the prism 146. In FIG. 17A, the surfaces 652, 654 face upward. The sealing surface 652 is a surface of a lower step formed on the inner surface of the hole 656, and the support surface 654 is a surface of an upper step. The two surfaces 652, 654 are ring-shaped when viewed from the prism side, and, for example, the inner diameter of the support surface 654 is equal to or larger than the outer diameter of the sealing surface 652.

[0107] After the O-ring 670 is placed on the sealing surface 652, the sensing element 14 including the transparent flat plate 141 and the prism 146 is placed on the O-ring 670. The main surface of the transparent flat plate 141 faces and contacts the O-ring 670. When viewed in the vertical direction (pressing direction) of FIGS. 17A and 17B, the outer periphery of the O-ring 670 exists within the main surface of the transparent flat plate 141. The main surface of the transparent flat plate 141 is separated from the support surface 654. The laminated film 140 is formed on the surface of the transparent flat plate 141 facing the O-ring 670.

[0108] Thereafter, the fastener 660 is placed on the prism 146 and the partition wall 650 so as to cover a portion of each of the leg surfaces 182, 183 of the prism 146. A screw 675 is inserted through a mounting hole in the fastener 660 and into a screw hole in the partition wall 650. The screw 675 is tightened, and the transparent substrate including the prism 146 and the transparent plate 141 is lowered into the hole 656, and the O-ring 670 is compressed.

[0109] 17B shows a state in which the fixture 660 is fixed to the partition wall 650 by a screw 675. The sensing element 14 including the prism 146 and the transparent plate 141 is pressed against the O-ring 670 and the support surface 654 by the fixture 660. The sensing element 14, together with the O-ring 670, covers the opening in the hole 656 of the partition wall 650.

[0110] The detection element 14 is pressed and fixed between the fixing tool 660 and the partition wall 650. At this time, the transparent flat plate 141 is in contact with the support surface 654. In addition, the O-ring 670 is compressed between the sealing surface 652 and the transparent flat plate 141 to seal the gap between the transparent flat plate 141 and the sealing surface 652.

[0111] 18A and 18B are cross-sectional views for explaining the sealing structure by the O-ring 670. The state of FIG. 18A corresponds to the state of FIG. 16B, and the state of FIG. 18B corresponds to the state of FIG. 16C. That is, in FIG. 18A, the O-ring 670 and the sensing element 14 are disposed in the hole 656 of the partition wall 650, and the sensing element 14 is not pressed by the fixing tool 660. The transparent flat plate 141 is on the O-ring 670 and is in contact with the O-ring 670. The transparent flat plate 141 is spaced apart from the support surface 654.

[0112] An O-ring 670 is disposed on the sealing surface 652. In the example shown in Fig. 18A, the cross section of the O-ring is circular and has a wire diameter D. The wire diameter D is greater than the step H between the two surfaces 652, 654. The difference between these is the compression allowance of the O-ring 670. The end face of the transparent flat plate 141 is inserted along a wall surface 657 that is a part of the inner surface of the hole 656. The wall surface 657 functions as a guide to position the transparent substrate including the prism 146 so that it fits correctly.

[0113] 18B shows the state of transparent flat plate 141 and O-ring 670 of sensing element 14 pressed and fixed by fastener 660 and screw 675. O-ring 670 is compressed by transparent flat plate 141 on sealing surface 652. The edge region of the main surface of transparent flat plate 141 abuts against supporting surface 654. Supporting surface 654 supports sensing element 14 together with O-ring 670. An appropriate compression allowance is applied to O-ring 670, which allows for a reliable seal and maintains the surface of laminated film 140 at the correct position (height).

[0114] Next, the deposition area of ​​the laminated film 140 on the transparent flat plate 141 or the inclined surface 181 of the prism 146 will be described. If the laminated film 140 is deposited on the transparent flat plate 141 or the prism 146 without any special consideration, the O-ring 670 will come into contact with it. If there is a place where the O-ring 670 and the laminated film 140 come into contact with each other, the film may be damaged at the contact portion. If damage occurs in even one place, it may affect the entire laminated film 140 from that point onwards.

[0115] 19 shows an example of an area of ​​the laminated film 140 formed on the inclined surface 181 of the prism 146. In FIG. 19, the laminated film 140 is a rectangle with rounded corners, but the shape is not particularly limited. The laminated film 140 may be directly formed on the inclined surface 181 of the prism 146, or the laminated film 140 may be formed on a glass plate, and the opposite surface of the glass plate may be bonded to the inclined surface 181 of the prism 148 by optical coupling oil.

[0116] 19, the entire area of ​​the laminated film 140 is contained within the central hole of the O-ring 670. The laminated film 140 does not come into contact with the O-ring 670. A configuration is adopted in which the laminated film 140 adheres to at least the area that is irradiated with the measurement light and contributes to measurement, and the laminated film 140 is not formed in the area required for sealing. Since the laminated film 140 is not present in the area that comes into contact with the O-ring 670, damage to the laminated film 140 can be avoided, resulting in a stable and highly reliable element. <Embodiment 4>

[0117] Figures 20A to 20C show the airtight structure of each of the above-mentioned embodiments. Figure 20A shows the airtight structure of embodiment 1, Figure 20B shows the airtight structure of embodiment 2, and Figure 20C shows the airtight structure of embodiment 3. In Figures 20A, 20B, and 20C, the white arrows indicate the pressing direction of prism 146. Prism 146 is pressed in the direction in which the O-ring is compressed.

[0118] As described above, the transparent substrate of the sensing element 14 in the embodiment of the present specification includes the prism 146. Therefore, it can exhibit high mechanical strength compared to a transparent substrate made of only a thin glass plate.

[0119] As described above, the transparent substrate of the detection element 14 can be composed of the prism 146 or the prism 146 and the transparent flat plate 141. If a large pressure difference between the measurement gas containing hydrogen and the outside world is applied to the transparent flat plate 141, which is a thin glass plate, the transparent flat plate 141 may be damaged. The laminated film 140, which is a gas detection film, is formed directly on the inclined surface 181 of the prism 146, and the prism 146, which is a block of glass, is used as a structural member to form part of the airtight partition without using thin glass. This can reduce the possibility of damage to the detection element. On the other hand, the use of a transparent flat plate makes it easier to form the gas detection film.

[0120] 20A, 20B, and 20C, a sensing element 14 including a prism 146 is placed at the boundary between a space that contains a measurement gas with a pressure difference and the outside world, and a part of the airtight partition wall is supported by the structure of the sensing element 14. An O-ring is placed between the partition wall and the laminated film formation surface of the transparent substrate including the prism 146 to provide a seal. The presence of the O-ring maintains airtightness, preventing the measurement gas from leaking to the outside world or the air from flowing into the measurement space.

[0121] In the embodiment of the present disclosure, the sensing element 14 including the prism 146 is fixed at a position where the amount of compression is such that the sealing performance of the O-ring is effective. Even if the internal / external pressure difference acts on the prism 146, the amount of compression of the O-ring does not change to such an extent that it affects the sealing performance. Therefore, sufficient sealing performance is ensured regardless of the magnitude of the pressure difference between the measurement gas and the outside world.

[0122] In the embodiment shown in Figures 20A and 20B, the prism 146 or 446 is pressed toward the outside of the gas flow path 310 in which the measurement gas exists. When the measurement gas is pressurized, that is, when the measurement gas has a pressure higher than the atmosphere, the pressure difference acts in a direction that strengthens the deformation of the O-ring 371, 372 or 470. Therefore, leakage of the measurement gas can be prevented more reliably. When the transparent flat plate 141 is used in these embodiments, optical coupling oil may be present in the measurement gas atmosphere. By forming the laminated film 140, which is a hydrogen gas detection film, directly on the prism 146, contamination by optical coupling oil can be avoided.

[0123] In the embodiment shown in FIG. 20C, the prism 146 is pressed toward the gas flow path 310 where the measurement gas exists. When the measurement gas is in a reduced pressure state, that is, when the measurement gas has a pressure lower than the atmosphere, the pressure difference acts in a direction that strengthens the deformation of the O-ring 670. Therefore, leakage of the measurement gas can be more reliably prevented. Also, when the detection element 14 includes the transparent flat plate 141 and the O-ring 670 is pressed by the transparent flat plate 141, the optical coupling oil between the transparent flat plate 141 and the prism 146 is placed outside the space where the measurement gas exists, so that contamination of the measurement gas can be avoided. Note that the laminated film 140 may be formed directly on the inclined surface 181 of the prism 146.

[0124] In the above embodiment, the gap between the surface of the detector element 14 and the surface of the partition wall part is sealed by an O-ring, which is an example of an elastic seal part. A part or all of the seal part in other embodiments may be formed of an adhesive material. In addition, the cross-sectional shape of the mounting part of the detector element 14 is not limited to the shape of the embodiment described above with reference to the figures, and a step structure may be formed so that the position of the prism 146 is stable and the compression margin of the O-ring is uniform. A part or all of the seal part in other embodiments may be formed of an adhesive material. Specifically, the elastic seal member may be made of an elastic body whose surface layer is made of a material having adhesiveness or bonding properties. This ensures sealing.

[0125] In the above embodiment, an optical hydrogen gas sensor has been described as an example of an optical gas sensor, but the optical chemical sensor of the present disclosure is not limited to a hydrogen gas sensor. The detection target of the optical chemical sensor is the concentration of the detection target, and the airtight structure using the detection element of the present disclosure can be applied to, for example, an optical ion sensor that detects the pH of a liquid, an optical gas sensor that detects a type of gas other than hydrogen gas, and an optical biosensor that detects DNA and enzymes in a liquid. In this way, the measurement target can be a fluid including gas and liquid. The airtight structure of the present disclosure can achieve the same effect as the above embodiment even when applied to the various optical chemical sensors.

[0126] As described above, the optical chemical sensor of the embodiment of the present disclosure irradiates a measurement light onto a detection film surface formed on a transparent substrate from the back side of the transparent substrate, and performs measurement using the reflected light. The transparent substrate includes a prism, and a detection film is formed on the surface of the transparent substrate. The detection film is exposed to the measurement object, and the surface of the transparent substrate through which the measurement light passes is exposed to the outside environment. The transparent substrate including the prism forms part of a partition between the measurement object and the outside environment. The transparent substrate including the prism and the rest of the partition are sealed by a seal portion.

[0127] By using a transparent substrate including a prism, which is necessary to eliminate direct reflection from the transparent substrate, as part of the partition when measuring oblique incidence from the back surface, the mechanical strength that is insufficient for a thin glass substrate alone to be used as a partition is ensured, and the functions of a partition, light transmittance, and elimination of direct reflection from the back surface can be simultaneously achieved, resulting in a compact, low-cost device.

[0128] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. A person skilled in the art can easily change, add, or convert each element of the above embodiments within the scope of the present disclosure. It is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. [Explanation of symbols]

[0129] 11 Light source 14, 44 Detector element 146, 446 Prism 140 Laminated Film 171, 172 Photodetector 181 Slope 182, 183 leg surface 320 Flow path block 350 Detector element holder 360, 560 flange 660 Fixtures 371, 372, 470, 670 O-ring

Claims

1. A light source; A sensing element; A photodetector; Fixtures and An elastic sealing part; Including, The sensing element is a prism including a slope and two legs; A detection film for a measurement object disposed on the inclined surface; Including, the detection film is exposed to an airtight space in which the measurement target is present, the detection element covers an opening in a partition wall of the airtight space in which the measurement object is present, the elastic sealing member is between the sensing element and the opening; the fixing device fixes the sensing element while pressing the sensing element so that the elastic seal part elastically deforms, the light source and the light detector are present outside an airtight space in which the measurement object is present, The light from the light source that has passed through one of the two leg surfaces is incident on the detection film, The light reflected by the detection film is emitted from the other of the two leg surfaces, The photodetector detects light reflected by the detection film and emitted from the other of the two leg surfaces. Optical sensor device.

2. 2. The optical sensor device according to claim 1, The bevel covers the opening, the elastic seal member is disposed between the inclined surface and the partition wall and surrounds the opening; Optical sensor device.

3. 2. The optical sensor device according to claim 1, The prism further includes a conical side surface, the two leg surfaces and a portion of the conical side surface cover the opening; The elastic seal part is present between the conical side surface and the partition wall. Optical sensor device.

4. 2. The optical sensor device according to claim 1, the opening is a first opening, the resilient sealing component is a first resilient sealing component, The optical sensor device further includes a second elastic seal component, a first leg surface of the two leg surfaces covers the first opening; the first elastic sealing component is disposed between the first leg surface and the partition wall and surrounds the first opening; a second leg surface of the two leg surfaces covers a second opening of the partition wall; the second elastic sealing component is disposed between the second leg surface and the partition wall and surrounds the second opening; the fixing device fixes the prism while pressing the prism so that the first and second elastic seal components are elastically deformed. Optical sensor device.

5. 3. The optical sensor device according to claim 2, The detection film is formed on a transparent flat plate, Oil is present between the transparent plate and the inclined surface, the elastic seal part is between the transparent plate and the partition wall, The elastic seal part is in contact with a main surface of the transparent flat plate. Optical sensor device.

6. 2. The optical sensor device according to claim 1, The detection film is directly deposited on the inclined surface of the prism. Optical sensor device.

7. 2. The optical sensor device according to claim 1, The entire area of ​​the detection membrane is within the area surrounded by the elastic seal part. Optical sensor device.

8. 2. The optical sensor device according to claim 1, The elastic sealing component is an O-ring. Optical sensor device.

9. 2. The optical sensor device according to claim 1, The surface of the elastic seal component has adhesive or adhesive properties. Optical sensor device.

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