WO2015178324A1

WO2015178324A1 - Pressure sensor

Info

Publication number: WO2015178324A1
Application number: PCT/JP2015/064121
Authority: WO
Inventors: 正人若原
Original assignee: 株式会社シミウス
Priority date: 2014-05-22
Filing date: 2015-05-17
Publication date: 2015-11-26
Also published as: JPWO2015178324A1; JP6392863B2

Abstract

In this pressure sensor, an optical fiber has an FBG section and a base member has an open end on one side. The optical fiber is affixed to the base member under tension so as to traverse the open end thereof. The base member exhibits rigidity so as not to be deformed by said tension. The outer edge of a diaphragm is supported in the aforementioned open end with the optical fiber placed between the base member and the diaphragm so as to be in contact with the diaphragm. A fulcrum that determines the length of the optical fiber that can move in accordance with deformation of the diaphragm is located in the traversing part of the optical fiber but outside the abovementioned open end.

Description

Pressure sensor

The present invention relates to a pressure sensor, and more particularly to a pressure sensor that includes an optical fiber and optically detects pressure.

Conventionally, in the design of automobiles, ships, airplanes, etc., it is required to grasp the physical quantity of fluid such as air pressure and water pressure acting on the surface of an object. Simulations are often used to grasp such fluid physical quantities. In addition, for the purpose of improving the accuracy of simulation and confirming its validity, measurement of air pressure on the model surface by a wind tunnel experiment using a reduced model (for example, 1/100 model) or an actual size model, and the water pressure of the model surface by a tank experiment Measurements are being carried out.

An optical pressure sensor using an optical fiber having an FBG (Fiber Bragg Grating) portion is used for measuring the fluid physical quantity. This type of optical pressure sensor requires no wiring for measurement and power supply like a pressure sensor using an electric strain gauge, and it is necessary to make a hole in the model in order to place the wiring inside the model. In addition, a large number of sensors can be easily arranged on the model surface.

The optical pressure sensor has, for example, a configuration in which an FBG portion is fixed to a diaphragm with an adhesive as disclosed in Patent Document 1. In this configuration, a change in pressure in the diaphragm is converted into a change in strain (stress), and the strain is detected as a change in wavelength of reflected light in the FBG section.

Further, in Patent Document 2, an optical fiber having an FBG portion is arranged on a through hole of a base film so that a more minute pressure change can be detected, and the diaphragm is covered so as to cover the through hole in a state of contacting the optical fiber. A configuration in which is arranged is disclosed. Moreover, in this structure, since the base film has flexibility, it is possible to arrange a pressure sensor on an arbitrary surface such as a curved surface.

JP 2002-098604 A JP 2008-070357 A

In order to stably measure strain with an optical fiber including an FBG section, it is necessary to stably apply tension to the optical fiber. However, in the configuration in which the optical fiber is directly fixed to the diaphragm as in Patent Document 1, the diaphragm is deformed in a short or long term due to the tension applied to the optical fiber, and the tension of the optical fiber is released. There is a problem that it is not possible to obtain accurate measurement reproducibility.

It seems that such a problem can be solved by using a highly rigid diaphragm that does not deform. However, in such a correspondence, since the diaphragm is not deformed by a minute pressure change, it is impossible to detect the minute pressure change.

Moreover, according to the structure which patent document 2 discloses, since the optical fiber is arrange | positioned on the through-hole of a base film, and is contacting with the diaphragm on the said through-hole, it detects the micro distortion change of a diaphragm. I can. However, since the base member that holds the optical fiber is in the form of a film, there is a problem that sufficient measurement reproducibility cannot be obtained as in Patent Document 1. Even if the base film is made of a high-rigidity material such as a metal, the problem is that the base film is short-term or long-term due to the tension applied to the optical fiber as long as the base film has flexibility. Is deformed, and there is a problem that sufficient measurement reproducibility cannot be obtained.

On the other hand, in the optical pressure sensor as described above, it is generally possible to detect more minute pressure fluctuations by increasing the diameter of the diaphragm. However, for example, as in the configuration disclosed in Patent Document 2, in the case where the thickness of the diaphragm is thin for detection of minute pressure fluctuations, if the diameter of the diaphragm is increased, the diaphragm is adjusted to the applied pressure. Correspondingly, it will be deformed unevenly. In this case, the region where the shift amount of the Bragg wavelength in the FBG portion changes linearly with respect to the pressure becomes narrow. As a result, the measurable pressure range (dynamic range) becomes small.

In the configuration of Patent Document 2, when the diameter of the diaphragm is increased, the portion of the optical fiber that moves according to the deformation of the diaphragm (the portion of the optical fiber that crosses the through hole) becomes longer. In this case, the response speed of the deformation of the FGB portion with respect to the deformation of the diaphragm becomes slow. In order to increase the response speed, it is generally only necessary to reduce the diaphragm diameter. However, if the diaphragm diameter is reduced, the detectable pressure fluctuation increases, and the minute pressure fluctuation cannot be detected.

The present invention has been made in view of the above-described problems of the prior art, and has high measurement reproducibility and can detect a minute pressure change, that is, a minute pressure change can be detected. It is an object of the present invention to provide a small pressure sensor and a pressure sensor with a high reaction speed capable of detecting a minute pressure change.

In order to achieve the above object, the present invention employs the following technical means. That is, the pressure sensor according to the present invention includes an optical fiber, a base member, and a diaphragm. The optical fiber includes an FBG (Fiber Bragg Grating) section. The base member has an open end on one surface. An optical fiber to which tension is applied is fixed to the base member so as to cross the open end. The base member has rigidity that is not deformed by the tension. The outer periphery of the diaphragm is supported at the open end in a state where the optical fiber is disposed between the diaphragm and the base member and in a state where the diaphragm is in contact with the optical fiber. And the fulcrum which prescribes | regulates the length of the optical fiber which can move according to a deformation | transformation of a diaphragm is arrange | positioned in the position different from the opening end in the part which an optical fiber crosses. That is, the length of the optical fiber that can move according to the deformation of the diaphragm is not the same as the opening width of the opening end of the base member at the portion where the optical fiber crosses, but is in a long state or a short state.

According to the pressure sensor of the present invention, since the base member has rigidity that does not deform due to the tension applied to the optical fiber, the diaphragm is deformed in a short term or a long term, and the tension of the optical fiber is released. There is nothing. As a result, stable measurement reproducibility can be ensured.

Further, in the configuration in which the length of the optical fiber movable according to the deformation of the diaphragm is longer than the opening width of the opening end of the base member in the portion where the optical fiber crosses, the opening width (opening area) of the opening end is increased. Therefore, the measurement sensitivity of pressure fluctuation can be improved and the dynamic range can be increased. As a result, a small and highly sensitive pressure sensor can be realized.

On the other hand, when the length of the optical fiber movable according to the deformation of the diaphragm is shorter than the opening width of the opening end of the base member at the portion where the optical fiber crosses, the opening width (opening area) of the opening end is reduced. The reaction rate with respect to pressure fluctuation can be improved. As a result, a pressure sensor with high sensitivity and high reaction speed can be realized.

Furthermore, although it is necessary to adjust the dimensions of each part, it is possible to measure from low pressure to high pressure with the same structure. For example, when measuring pressure in a reduced model and measuring pressure in a real model In this case, a pressure sensor having the same structure can be used.

For example, the above-mentioned fulcrum is formed by the end of the groove part deeper than the fixing position of the optical fiber provided in the base member in a state of extending toward the outside of the opening end along the arrangement direction of the optical fiber in plan view. Can be configured. In this case, the length of the optical fiber movable in accordance with the deformation of the diaphragm is longer than the opening width of the opening end of the base member at the portion where the optical fiber crosses. Moreover, the above-mentioned fulcrum can be constituted by the tip of a projecting portion that extends toward the inside of the opening end in a state in which the fulcrum is in contact with the optical fiber in a plan view. In this case, the length of the optical fiber that can move according to the deformation of the diaphragm is shorter than the opening width of the opening end of the base member at the portion where the optical fiber crosses.

In the above pressure sensor, the diaphragm further includes a transmission part that concentrates the stress generated in the diaphragm on a specific part of the optical fiber according to the applied pressure, and a configuration in which the diaphragm abuts on the optical fiber through the transmission part is adopted. can do. According to this configuration, since the stress generated in the diaphragm is concentrated on a specific portion of the optical fiber fixed to the base member, the optical fiber can be distorted even with a minute pressure. As a result, it is possible to detect a smaller change in pressure applied to the diaphragm.

Further, the base member can be made of metal, ceramic or glass. Further, the diaphragm can be formed of a resin film. Further, the optical fiber may be configured to be fixed to the base member while being accommodated in a groove provided on one surface of the base member.

According to the present invention, it is possible to realize a high-performance pressure sensor with good measurement reproducibility and capable of detecting minute pressure changes.

FIG. 1 is a schematic configuration diagram illustrating an example of a pressure sensor according to an embodiment of the present invention. FIG. 2 is a schematic plan view showing an example of a pressure sensor in one embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing an example of a pressure sensor in one embodiment of the present invention. 4 (a) and 4 (b) are diagrams showing the effect of the pressure sensor in one embodiment of the present invention. FIG. 5 is a schematic configuration diagram illustrating another example of a pressure sensor according to an embodiment of the present invention. FIG. 6 is a schematic plan view showing another example of the pressure sensor in one embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing another example of the pressure sensor in one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of the overall configuration of the pressure sensor 1 in the present embodiment. FIG. 2 is a schematic plan view showing an example of the pressure sensor 1 in the present embodiment. FIG. 3 is a schematic cross-sectional view taken along the line AA shown in FIG.

1 to 3, the pressure sensor 1 includes a base member 11, an optical fiber 12, and a diaphragm 13. 1 and 2, only the outer shape of the diaphragm 13 is indicated by a broken line in order to show the internal structure.

In the present embodiment, the base member 11 has a form in which a circular through hole 15 is formed at the center of a pupil-shaped plate member having a thickness larger than the diameter of the optical fiber 12. The ends are exposed on both surfaces of the base member 11.

The groove part 16 which accommodates the optical fiber 12 is formed in the one surface (here upper surface) of the base member 11 along a longitudinal direction. In the base member 11, the groove portions 16 provided at portions facing each other with the through hole 15 interposed therebetween are arranged in the same straight line. Each groove 16 is provided with a portion having a width slightly larger than the diameter of the optical fiber 12 and a wide portion 17 having a width wider than the width. It is not essential to provide the wide portion 17.

Further, in the groove portion 16 on the side of the through hole 15 relative to the wide portion 17, a deep groove portion 19 having a deep groove is provided in a portion having a predetermined length from the through hole 15. Although not particularly limited, in the present embodiment, the deep groove portion 19 is a through groove (slit). Further, in the present embodiment, the entire groove portion 16 from the through hole 15 to the end portion on the through hole 15 side of the wide portion 17 is the deep groove portion 19, but the end of the deep groove portion 19 is the through hole 15 of the wide portion 17. It can also be arranged closer to the through hole 15 than the side end.

The optical fiber 12 is accommodated in the groove 16 in a state of crossing the through hole 15 and is fixed to the base member 11 in a state where a tension (pre-tension) is applied. Although the fixing method is not particularly limited, in this embodiment, the optical fiber 12 is fixed to the base member 11 with an ultraviolet curable adhesive filled in the wide portion 17. In the present embodiment, not only the wide portion 17 but also the entire groove portion 16 (hereinafter referred to as the shallow groove portion 20) excluding the deep groove portion 19 is filled with the adhesive. In FIGS. 1 to 3, the adhesive is not shown.

In the present embodiment, the shallow groove portion 20 has a uniform depth that is about the same as the diameter of the optical fiber 12. Further, the wide portion 17 is formed slightly deeper than the shallow groove portion 20 as shown in FIG. Thereby, in the wide part 17, an adhesive agent can be made to go around also to the downward side of the optical fiber 12. FIG. The bottom surface of the shallow groove portion 20 is formed in parallel with the top surface and the bottom surface of the base member 11, and the optical fiber 12 is fixed in contact with the bottom surface of the shallow groove portion 20, thereby fixing the optical fiber 12 to the top surface of the base member 11. And in the same plane parallel to the lower surface. Note that the bottom surface of the shallow groove portion 20 can be formed of a curved surface that matches the outer periphery of the optical fiber 12.

The base member 11 has a rigidity that does not deform in a short term and a long term due to the tension applied to the optical fiber 12. The material of the base member 11 is not particularly limited. For example, it can be made of metal, ceramic or glass. Here, the base member 11 is made of metal.

The optical fiber 12 includes an FBG (Fiber-Bragg-Grating) unit 18 having a specific Bragg wavelength. The length of the FBG portion 18 may be longer than the diameter of the through hole 15 or may be shorter than the diameter of the through hole 15. The FBG portion 18 only needs to be at least partially disposed in the portion of the optical fiber 12 that is fixed to the base member 11 on both sides. As described above, in this embodiment, the optical fiber 12 is fixed to the base member 11 over the entire wide portion 17 and the shallow groove portion 20. Therefore, in this embodiment, the portion of the optical fiber 12 whose both sides are fixed to the base member 11 extends from the end portion on the through hole 15 side of one wide portion 17 to the end portion on the through hole 15 side of the other wide portion 17. Become the part between. Although not particularly limited, in the present embodiment, the FBG portion 18 is configured to have a length of about ３ of the diameter of the through hole 15 and is disposed at the center of the through hole 15 in plan view. . In the drawing, for convenience, the FBG portion 18 is expressed by black painting.

As is well known, the FBG unit 18 reflects light having a wavelength defined by the Bragg wavelength. The FBG unit 18 is composed of a plurality of diffraction gratings arranged at a predetermined interval in the core of the optical fiber, and the Bragg wavelength is proportional to the product of the refractive index of the optical fiber and the arrangement interval of the diffraction gratings. Therefore, when the stress acts on the FBG part 18 and the interval between the diffraction gratings constituting the FBG part 18 increases, the wavelength of light reflected by the FBG part 18 increases. Further, when the FBG portion 18 is compressed by stress and the interval between the diffraction gratings constituting the FBG portion 18 is narrowed, the wavelength of light reflected by the FBG portion 18 becomes small. The change in wavelength is acquired by a light source and a measuring instrument connected to one end of the optical fiber 12. When using a plurality of pressure sensors 1 connected in series, the Bragg wavelength of the FBG unit 18 of each pressure sensor 1 is set to a different wavelength. Thereby, the reflection position of reflected light can be easily distinguished based on the wavelength of reflected light.

The outer periphery of the diaphragm 13 is fixedly supported on the upper surface of the base member 11 that is the open end of the through hole 15. Therefore, the optical fiber 12 is disposed between the diaphragm 13 and the base member 11. Although not particularly limited, in the present embodiment, the diaphragm 13 has a pupil-shaped outer shape slightly smaller than the outer shape of the base member 11 in plan view, and covers the wide portion 17 and the shallow groove portion 20.

The diaphragm 13 has a function of converting a change in pressure applied to the diaphragm 13 into a change in strain (stress). The diaphragm 13 can be made of a flexible material (for example, a resin film). Although not particularly limited, in the present embodiment, the diaphragm 13 is made of a polyimide film. A fixing method between the diaphragm 13 and the base member 11 is not particularly limited. For example, it can be fixed with an ultraviolet curable adhesive.

Although not particularly limited, the diaphragm 13 includes a transmission unit 14. The transmission unit 14 has a function of concentrating stress generated in the diaphragm 13 on a specific portion of the optical fiber 12 according to the pressure applied to the diaphragm 13. The transmission unit 14 is fixed to the diaphragm 13, and the diaphragm 13 is in contact with the optical fiber 12 through the transmission unit 14. The fixing can be realized by an ultraviolet curable adhesive. Further, the transmission unit 14 is not fixed to the optical fiber 12. In this embodiment, the transmission part 14 is comprised by the cylindrical body arrange | positioned in the center of the through-hole 15 in planar view. The cylindrical body is arranged in a direction orthogonal to the arrangement direction of the optical fiber 12. The transmission unit 14 makes point contact with the optical fiber 12 to concentrate stress generated in the diaphragm 13 on the portion of the optical fiber 12 located at the center of the through hole 15. In this embodiment, a small piece of an optical fiber having the same outer diameter as that of the optical fiber 12 is used as the transmission unit 14.

In the pressure sensor 1 having the above-described configuration, the fulcrum that defines the length of the optical fiber 12 that can move according to the deformation of the diaphragm 13 is not the side wall (open end) of the through-hole 15 but the deep groove 19. Become the end.

4 (a) and 4 (b) are diagrams showing effects obtained by adopting such a configuration. 4A and 4B, the horizontal axis corresponds to the pressure applied to the diaphragm 13. The vertical axis corresponds to the shift amount of the Bragg wavelength.

FIG. 4 (a) is a diagram showing the pressure dependence of the Bragg wavelength shift when the diameter of the diaphragm 13 (opening diameter of the through hole 15) is 6 mm, 10 mm, and 14 mm. In FIG. 4A, the deep groove portion 19 is not provided, and the fulcrum that defines the length of the optical fiber 12 that can move according to the deformation of the diaphragm 13 is the side wall portion of the through hole 15.

As can be understood from FIG. 4A, when the opening diameter is 6 mm, the shift amount of the Bragg wavelength increases in proportion to the increase in pressure applied to the diaphragm 13. It can be understood that when the opening diameters are 10 mm and 14 mm, the inclination is increased as compared with the case where the opening diameter is 6 mm, and a smaller pressure fluctuation can be detected. However, the slope is different between the region where the pressure is relatively low and the region where the pressure is relatively high, and the region between these regions, and the region where the shift amount of the Bragg wavelength changes linearly with respect to the pressure is narrow. It has become. That is, when the opening diameter of the through-hole 15 is increased, the measurement sensitivity is improved, but it can be understood that the dynamic range of pressure at which the measurement can be performed with the improved sensitivity is narrowed.

FIG. 4B is a diagram showing the pressure dependence of the Bragg wavelength shift amount when the length of the deep groove portion 19 along the longitudinal direction is set to 0 mm, 1 mm, and 3 mm. In FIG. 4B, the opening diameter of the through hole 15 is 6 mm.

As can be understood from FIG. 4B, the inclination increases as the length of the deep groove portion 19 is increased. Therefore, if the length of the deep groove portion 19 is increased, a more minute pressure fluctuation can be detected. Further, when the length of the deep groove portion 19 is increased, the linearity is not lost as in the case where the diameter of the diaphragm 13 is increased. That is, by increasing the length of the deep groove portion 19, it is possible to improve the pressure fluctuation measurement sensitivity without increasing the opening diameter of the through hole 15. In addition, the dynamic range can be increased. Further, since it is not necessary to increase the opening diameter of the through hole 15, it is possible to realize a small and highly sensitive pressure sensor 1.

For fixing the pressure sensor 1 to the measurement object, any known method such as an adhesive or a double-sided tape can be employed. Although not particularly limited, as shown in FIG. 3, the pressure sensor 1 is provided with a sheet member 21 having a rigidity lower than that of the base member 11 on a contact surface with the measurement object (here, the lower surface side of the base member 11). ing. As the material of the sheet member 21, for example, a resin material having a lower rigidity (having flexibility) than a metal such as an ultraviolet curable adhesive or a sealant can be used.

In the pressure sensor 1 described above, since the base member 11 has rigidity that does not deform due to the tension applied to the optical fiber 12, the diaphragm 13 is deformed in the short term or in the long term, and the tension of the optical fiber 12 is released. It is never done. As a result, stable measurement reproducibility can be ensured.

In addition, since the length of the optical fiber 12 movable according to the deformation of the diaphragm 13 is longer than the opening diameter of the through hole 15 at the portion where the optical fiber 12 crosses, the opening diameter (opening area) of the through hole 15 is increased. The measurement sensitivity of pressure fluctuation can be improved without doing so. In addition, the dynamic range can be increased. As a result, a small and highly sensitive pressure sensor can be realized.

Furthermore, the pressure sensor 1 does not measure the distortion of the diaphragm 13 but measures the distortion (stress) that is amplified and transmitted by the transmission unit 14 according to the distortion of the diaphragm 13. Therefore, since the stress generated in the diaphragm 13 is concentrated on a specific portion of the optical fiber 12 fixed to the base member 11, the optical fiber 12 can be distorted even with a minute pressure. As a result, a minute pressure change applied to the diaphragm 13 can be detected.

In addition, since the lower surface of the base member 11 is covered with a relatively soft sheet member 21, the pressure sensor 1 can be attached relatively easily even if the measurement target surface is a curved surface. Even when pasted on a curved surface in this way, the positional relationship between the base member 11 and the optical fiber 12 (FBG portion 18) does not change as in the conventional configuration using a flexible base film. The magnitude of the tension applied to the optical fiber 12 does not change. Therefore, unlike the conventional pressure sensor using a flexible base film, the situation where the output value of the pressure sensor differs depending on the attachment position does not occur.

In addition, since the sheet member 21 is disposed, even if vibration or deformation occurs on the measurement target surface, it is possible to suppress the vibration or deformation from being transmitted to the diaphragm 13 or the FBG unit 18. Can be prevented.

Moreover, although it is necessary to adjust the dimension of each part, according to the pressure sensor 1, since it can measure from low pressure to high pressure with the same structure, for example, when measuring pressure in a reduced model The pressure sensor having the same structure can be used when the pressure is measured in the real model. For example, when measuring a low pressure, the diameter of the through-hole 15 can be about 6 mm, and the diameter of the cylindrical body which is the transmission part 14 can be about 0.15 mm. The width and thickness of the base member 11 can be designed arbitrarily. Moreover, what is necessary is just to make the dimension of each part into a constant multiple when measuring a high pressure.

In the above example, the deep groove portion 19 is a through groove. However, the deep groove portion 19 is deeper than the fixing position of the optical fiber 12 and may interfere with the movable optical fiber 12 according to the deformation of the diaphragm 13. Any depth can be set as long as there is no depth.

In the above example, the diaphragm 13 and the transmission unit 14 are separate members, but the transmission unit 14 may be formed integrally with the diaphragm 13. In addition, it is not essential to include the transmission unit 14, and a configuration in which the optical fiber 12 directly contacts the diaphragm 13 without including the transmission unit 14 may be employed.

In the above, the fulcrum that defines the length of the optical fiber 12 that can move according to the deformation of the diaphragm 13 is arranged outside the through hole 15 along the arrangement direction of the optical fiber 12 in plan view. . However, although the measurement sensitivity and the dynamic range can be improved with the above-described configuration, the length of the movable optical fiber 12 is increased according to the deformation of the diaphragm 13, and as a result, the response speed of the diaphragm 13 to the pressure fluctuation is reduced. Resulting in. From the viewpoint of increasing the response speed, it is preferable to reduce the opening diameter of the through hole 15. However, as can be understood from FIG. 4A, if the opening diameter of the through hole 15 is reduced, the measurement sensitivity is lowered.

Therefore, in the following, a configuration capable of improving the response speed without causing a decrease in measurement sensitivity will be described. FIG. 5 is a schematic configuration diagram showing an example of the overall configuration of the pressure sensor 2 in the present embodiment. FIG. 6 is a schematic plan view showing an example of the pressure sensor 2 in the present embodiment. Further, FIG. 7 is a schematic cross-sectional view along the line BB shown in FIG.

As shown in FIGS. 5 to 7, the pressure sensor 2 is different from the configuration of the pressure sensor 1 in that the deep groove portion 19 is not provided and the protrusion portion 22 is provided. The other configuration is the same as that of the pressure sensor 1, and the same reference numerals are given to the components that exhibit the same effects as the pressure sensor 1. In FIGS. 5 and 6, only the outer shape of the diaphragm 13 is indicated by a broken line.

As shown in FIGS. 5 to 7, the projecting portion 22 is arranged so as to extend toward the inside of the through hole 15 in contact with the optical fiber 12 along the arrangement direction of the optical fiber 12 in plan view. The In the present embodiment, the protruding portion 22 is configured integrally with the base member 11, and the upper surface of the protruding portion 22 is configured to be flush with the bottom surface of the groove portion 16. Further, the lower surface of the protrusion 22 is configured to be flush with the lower surface of the base member 11. In the protrusion 22, the width in the direction perpendicular to the protrusion direction is the same as the width of the groove 16. On the protrusion 22, the optical fiber 12 is fixed to the upper surface of the protrusion 22. Such fixing can be performed, for example, with an ultraviolet curable adhesive.

In the pressure sensor 2 having the above-described configuration, the fulcrum that defines the length of the optical fiber 12 that can move according to the deformation of the diaphragm 13 is not the side wall (opening end) of the through-hole 15 but the protrusion 22. Become the tip.

As described above, in the configuration in which the length of the optical fiber 12 that is movable according to the deformation of the diaphragm 13 is shorter than the opening diameter of the through hole 15, the optical fiber 12 is rapidly deformed according to the deformation of the diaphragm 13. The response of the Bragg wavelength shift to 13 deformations can be improved. Further, according to this configuration, since the opening diameter (opening area) of the through hole 15 is not reduced, the measurement sensitivity due to the reduction of the diaphragm 13 does not occur. As a result, it is possible to realize a pressure sensor with high sensitivity and high reaction speed.

The above-described embodiments do not limit the technical scope of the present invention, and various modifications and applications can be made within the scope of the present invention other than those already described. For example, in the above embodiment, the shape of the through hole 15 is circular as a particularly preferable form, but the shape of the through hole may be polygonal. Further, the base member 11 may be configured to include a concave portion whose bottom surface is closed instead of the through hole 15.

According to the present invention, it is possible to realize a high-performance pressure sensor with good measurement reproducibility and capable of detecting minute pressure changes, and is useful as a pressure sensor.

DESCRIPTION OF

SYMBOLS

1, 2 Pressure sensor 11 Base member 12 Optical fiber 13 Diaphragm 14 Transmission part 15 Through-hole 16 Groove part 18 FBG part 19 Deep groove part 20 Shallow groove part 22 Projection part

Claims

An optical fiber including an FBG (Fiber Bragg Grating) section;
A base member having an opening end on one surface and having the rigidity that is not deformed by the tension while the optical fiber to which the tension is applied is fixed in a state of crossing the opening end,
A flexible diaphragm in which the optical fiber is disposed between the base member and an outer periphery is supported at the opening end in a state of being in contact with the optical fiber;
A fulcrum that defines the length of an optical fiber that is movable in response to deformation of the diaphragm, disposed at a position different from the opening end in a portion where the optical fiber crosses;
A pressure sensor.
The end portion of the groove portion deeper than the fixing position of the optical fiber provided in the base member in a state where the fulcrum extends toward the outside of the opening end along the arrangement direction of the optical fiber in plan view The pressure sensor according to claim 1, comprising:
2. The pressure according to claim 1, wherein the fulcrum is configured by a distal end of a projecting portion that extends toward the inside of the opening end in a state of contacting the optical fiber along a direction in which the optical fiber is disposed in plan view. Sensor.
The diaphragm further includes a transmission unit that concentrates stress generated in the diaphragm in response to an applied pressure to a specific portion of the optical fiber, and abuts on the optical fiber via the transmission unit. The pressure sensor according to claim 1.
The pressure sensor according to any one of claims 1 to 4, wherein the base member is made of metal, ceramic, or glass.
The pressure sensor according to any one of claims 1 to 5, wherein the diaphragm is made of a resin film.
The pressure sensor according to any one of claims 1 to 6, wherein the optical fiber is fixed to the base member in a state of being accommodated in a groove provided on one surface of the base member.