WO2010084523A1 - Humidity sensor and humidity measurement device - Google Patents

Humidity sensor and humidity measurement device Download PDF

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Publication number
WO2010084523A1
WO2010084523A1 PCT/JP2009/000187 JP2009000187W WO2010084523A1 WO 2010084523 A1 WO2010084523 A1 WO 2010084523A1 JP 2009000187 W JP2009000187 W JP 2009000187W WO 2010084523 A1 WO2010084523 A1 WO 2010084523A1
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Prior art keywords
optical fiber
light
humidity
refractive index
film
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PCT/JP2009/000187
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French (fr)
Japanese (ja)
Inventor
博幸 佐々木
篤志 関
一弘 渡辺
尚平 秋田
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学校法人創価大学
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Priority to PCT/JP2009/000187 priority Critical patent/WO2010084523A1/en
Publication of WO2010084523A1 publication Critical patent/WO2010084523A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/7703—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator using reagent-clad optical fibres or optical waveguides
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/55—Specular reflectivity
    • G01N21/552—Attenuated total reflection
    • G01N21/553—Attenuated total reflection and using surface plasmons

Definitions

  • the present invention relates to a surface plasmon humidity sensor using an optical fiber, a surface plasmon humidity sensor, an optical fiber type humidity sensor, and a humidity measuring apparatus using these humidity sensors.
  • a surface plasmon sensor that uses the surface plasmon phenomenon for detection of a measurement object is known.
  • a Kretschmann type surface plasmon sensor known as a kind of surface plasmon sensor has a structure in which a metal film is provided on a flat plate made of glass and the metal film is brought into contact with a sample to be measured.
  • surface plasmon resonance occurs when the incident angle of the light with respect to the metal film and the refractive index of the sample to be measured in contact with the metal film satisfy a predetermined relationship. It occurs and the intensity of reflected light decreases. Therefore, the refractive index of the measurement target sample obtained by detecting the incident angle at which the reflected light attenuates can be used for measurement of the measurement target.
  • Patent Documents 3 and 4 a metal film for generating surface plasmons on the surface of the hetero-core part is provided by fusion-bonding a part called a hetero-core part having a different core diameter at the middle part or end part of the optical fiber.
  • the provided arrangement is disclosed.
  • the present invention provides an optical fiber type surface plasmon humidity sensor, a surface plasmon humidity sensor, an optical fiber type humidity sensor, and a humidity measuring device using these humidity sensors, which have improved sensitivity to humidity. That is the issue.
  • An optical fiber type surface plasmon humidity sensor includes an optical fiber, a light transmission member provided in a middle portion of the optical fiber, and a part of transmitted light interacts with the outside, and an outer peripheral surface of the light transmission member
  • the above-described optical fiber type surface plasmon humidity sensor of the present invention is provided with a light transmission member that causes a part of transmitted light to interact with the outside world in the middle part of the optical fiber, and the outer peripheral surface has the outer peripheral surface.
  • a metal film that generates surface plasmon by reflection of light in the light transmitting member is provided, and a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface of the metal film.
  • the film whose refractive index changes is a plurality of stacked polyion films.
  • the film whose refractive index changes is a gelatin film.
  • the light transmitting member is a hetero-core portion having a core diameter different from the core diameter of the optical fiber.
  • the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  • the optical fiber is a multimode optical fiber.
  • one end of the optical fiber is branched into two to provide a light incident end and an output end, and the other end of the optical fiber reflects light transmitted through the optical fiber. Then, a reflection part for returning to the optical fiber is provided.
  • the surface plasmon humidity sensor of the present invention includes a light transmissive substrate, a metal film that is provided on the surface of the light transmissive substrate, and generates surface plasmons by reflection of light in the light transmissive substrate on the surface. And a film provided on an upper layer of the metal film, the refractive index of which changes according to the humidity in the atmosphere.
  • a metal film that generates surface plasmons by reflection of light in the light-transmitting substrate on the surface is provided on the surface of the light-transmitting substrate, and the upper layer of the metal film.
  • a film whose refractive index changes according to the humidity in the atmosphere is provided.
  • the optical fiber type humidity sensor of the present invention includes an optical fiber, a light transmissive member provided in the middle of the optical fiber, allowing a part of transmitted light to interact with the outside world, and an outer peripheral surface of the light transmissive member. And a film whose refractive index changes depending on the humidity in the atmosphere.
  • a light transmission member that causes a part of transmitted light to interact with the outside world is provided in the middle of the optical fiber, and the outer peripheral surface thereof is adjusted to the atmospheric humidity.
  • a film whose refractive index changes accordingly is provided.
  • the film whose refractive index changes is a plurality of stacked polyion films.
  • the film whose refractive index changes is a gelatin film.
  • the light transmitting member is a hetero core portion having a core diameter different from the core diameter of the optical fiber.
  • the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  • the optical fiber is a multimode optical fiber.
  • one end portion of the optical fiber is branched into two, and an incident end and an exit end of light are provided, and light transmitted through the optical fiber is reflected to the other end portion of the optical fiber. And a reflecting portion for returning to the optical fiber.
  • the humidity measuring device of the present invention is provided on the optical fiber, a light transmission member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, and an outer peripheral surface of the light transmission member.
  • a light source configured to emit sensor light to the incident end of the optical fiber; and a light receiving unit configured to detect the sensor light emitted from the output end of the optical fiber via the light transmitting member.
  • a light transmission member that causes a part of transmitted light to interact with the outside world is provided in the middle part of the optical fiber, and the light transmission member on the outer peripheral surface is provided on the outer peripheral surface thereof.
  • a metal film that generates surface plasmons by reflection of light therein is provided, and a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface of the metal film.
  • a light source is provided to emit sensor light to the incident end of the optical fiber, and a light receiving unit is provided to detect the sensor light emitted from the output end of the optical fiber via the light transmitting member. ing.
  • the film whose refractive index changes is a plurality of stacked polyion films.
  • the film whose refractive index changes is a gelatin film.
  • the light transmitting member is a hetero-core portion having a core diameter different from the core diameter of the optical fiber.
  • the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  • the optical fiber is a multimode optical fiber.
  • one end portion of the optical fiber is branched into two to provide the incident end and the output end, and reflects light transmitted through the optical fiber to the other end portion of the optical fiber. And a reflecting portion for returning to the optical fiber.
  • the humidity measuring device of the present invention is a light transmissive substrate, a metal film that is provided on the surface of the light transmissive substrate and generates surface plasmons by reflection of light in the light transmissive substrate on the surface, Sensor light is emitted from the inner side of the light-transmitting substrate toward the interface between the metal film and the light-transmitting substrate, provided on the upper layer of the metal film and having a refractive index that changes according to the humidity in the atmosphere. And a light receiving unit that detects the sensor light reflected from the interface between the metal film and the light transmissive substrate.
  • a metal film that generates surface plasmons by reflection of light in the light-transmitting substrate on the surface is provided on the surface of the light-transmitting substrate.
  • a film whose refractive index changes according to the humidity in the atmosphere is provided.
  • a light source is provided to emit sensor light from the inside of the light transmissive substrate toward the interface between the metal film and the light transmissive substrate, and a light receiving unit is provided to reflect from the interface between the metal film and the light transmissive substrate. The sensor light is detected.
  • the humidity measuring device of the present invention is provided on the optical fiber, a light transmission member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, and an outer peripheral surface of the light transmission member.
  • a light receiving portion for detecting the sensor light is provided on the optical fiber, a light transmission member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, and an outer peripheral surface of the light transmission member.
  • a film whose refractive index changes according to the humidity in the atmosphere a light source that emits sensor light to the incident end of the optical fiber, and an output end of the optical fiber through the light transmitting member.
  • a light receiving portion for detecting the sensor light for detecting the sensor light.
  • a light transmission member that causes a part of the transmitted light to interact with the outside world is provided in the middle of the optical fiber, and the outer peripheral surface thereof has a humidity according to the humidity in the atmosphere.
  • a film whose refractive index changes is provided.
  • a light source is provided to emit sensor light to the incident end of the optical fiber, and a light receiving unit is provided to detect the sensor light emitted from the output end of the optical fiber via the light transmitting member.
  • the film whose refractive index changes is a plurality of stacked polyion films.
  • the film whose refractive index changes is a gelatin film.
  • the light transmitting member is a hetero-core portion having a core diameter different from the core diameter of the optical fiber.
  • the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  • the optical fiber is a multimode optical fiber.
  • one end of the optical fiber is branched into two to provide the incident end and the output end, and the other end of the optical fiber reflects light transmitted through the optical fiber. Then, a reflection part for returning to the optical fiber is provided.
  • the surface plasmon humidity sensor of the present invention is an optical fiber type surface plasmon sensor in which a light transmitting member such as a hetero core is provided in the middle of an optical fiber, and the humidity in the atmosphere on the outer peripheral surface or upper layer of the metal film. Accordingly, a film whose refractive index changes according to the above is provided, and the sensitivity to humidity in the atmosphere can be improved.
  • a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface of a light transmitting member such as a hetero core provided in the middle of the optical fiber.
  • the sensitivity to the humidity in the atmosphere can be improved.
  • the humidity measuring apparatus of the present invention described above is the surface plasmon humidity sensor or optical fiber type humidity sensor of the present invention, wherein the outer peripheral surface or upper layer of the metal film of the surface plasmon humidity sensor, or the light transmitting member of the optical fiber type humidity sensor.
  • a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • FIG. 2A is a perspective view of the vicinity of the sensor portion of the optical fiber type surface plasmon humidity sensor according to the first embodiment of the present invention
  • FIG. 2B is a longitudinal sectional view of the vicinity of the sensor portion
  • FIGS. 3A and 3B are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion of the optical fiber type surface plasmon humidity sensor according to the second embodiment of the present invention.
  • FIG. 10A is a perspective view of the vicinity of the sensor portion of the optical fiber type humidity sensor according to the ninth embodiment of the present invention
  • FIG. 10B is a longitudinal sectional view of the vicinity of the sensor portion.
  • Embodiments of an optical fiber type surface plasmon humidity sensor, a surface plasmon humidity sensor, an optical fiber type humidity sensor, and a humidity measuring device using these will be described below with reference to the drawings.
  • a humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor according to the first embodiment of the present invention will be described. With reference to FIG. 1, this humidity measuring device is provided with a sensor part SP in the middle of optical fibers 20a and 20b.
  • a light source 11 that emits sensor light such as a white light source is provided at the light incident end of the optical fiber 20a, and a photodiode that detects sensor light emitted from the light emitting end is provided at the light emitting end of the optical fiber 20b.
  • a spectrum analyzer 12 having a light receiving unit such as a power meter is provided. The sensor unit SP is placed in the measurement target atmosphere, and the humidity of the measurement target atmosphere is measured by measuring the sensor light at this time.
  • FIG. 2A shows a perspective view of the vicinity of the sensor part SP of the optical fiber type surface plasmon humidity sensor used in the humidity measuring apparatus of the present embodiment
  • FIG. 2B shows a longitudinal sectional view of the vicinity of the sensor part SP.
  • the optical fiber type surface plasmon humidity sensor has a configuration in which, for example, a sensor unit SP is provided between one optical fiber 20a and the other optical fiber 20b which are multimode fibers having a core diameter of 50 ⁇ m.
  • the sensor part SP is provided on the outer peripheral surface of the heterocore part 3 that is a light transmitting member that causes a part of the transmitted light to interact with the outside world, and the light in the light transmitting member on the outer peripheral surface of the heterocore part 3.
  • the optical fibers 20a and 20b have a core 21 and a clad 22 provided on the outer periphery thereof.
  • the hetero core part 3 has a core 31 having a core diameter different from the core diameters of the optical fibers 20a and 20b, and a clad 32 provided on the outer peripheral part thereof.
  • the length cl of the heterocore part 3 is 1 mm to several cm.
  • the hetero-core portion 3 and the optical fibers 20a and 20b constituting the sensor portion SP are joined substantially coaxially so that the cores are joined at the interface 4 orthogonal to the longitudinal direction, for example, by fusion using a generalized discharge. Has been.
  • optical fibers 20a and 20b and the hetero core section 3 for example, any of a single mode optical fiber and a multimode optical fiber can be used, and these may be used in combination.
  • the metal film 50 is formed so that the hetero core part 3 of the sensor part SP according to the present embodiment covers the surface side.
  • the metal film 50 is formed, for example, by forming a chromium (Cr) film on the outer surface of the hetero core portion 3 by vapor deposition, and forming a gold (Au) film on the chromium film by vapor deposition.
  • a metal film 50 made of a laminated film is formed.
  • the film thickness of the chromium film is, for example, about several nm
  • the film thickness of the gold film is, for example, about several tens of nm.
  • the metal film 50 may be formed using other metals such as silver (Ag) and aluminum (Al).
  • the surface plasmon is generated by reflection of light inside the hetero-core part 3 at the boundary between the hetero-core part 3 and the metal film 50.
  • the film 60 whose refractive index changes according to the humidity in the atmosphere is, for example, a plurality of stacked polyion films or gelatin films.
  • the polyion film is a polymer film in which a large number of positively or negatively charged functional groups such as ionized carboxylic acid groups (—COO—) and protonated amino groups (—NH 3+) are bonded.
  • the film 60 can have a structure in which a plurality of positive functional group polyion films and negative functional group polyion films are alternately stacked, and a gelatin film can also be used. Any material whose refractive index varies with humidity can be used.
  • the film thickness of the film 60 such as a polyion film is not particularly limited, but is, for example, about 1 nm to several ⁇ m.
  • the diameter bl of the core 31 in the hetero core part 3 and the diameter al of the core 21 of the optical fibers 20a and 20b are the interface 4. Is different. Due to the difference in the core diameter, as shown in FIG. 2A, a leak W to the clad 32 of the hetero-core portion 3 that is a part of the light occurs.
  • the sensor light is transmitted as light in which a plurality of modes are formed due to the normal properties of the optical fiber.
  • the mode of light transmitted by the optical fiber 20a can also be schematically taken as the reflection angle of light at the boundary between the core 21 and the clad 22.
  • the reflection angle of the light in the optical fiber 20a can be considered as a very large number of discrete angles.
  • the mode when light defined in a certain mode is incident on the hetero-core portion 3, the mode is deregulated, the mode is destroyed, and the light is reflected at various reflection angles and becomes a mode-disrupted light. Leaks in.
  • the leaked light is reflected at the boundary between the clad 32 of the hetero-core portion 3 and the metal film 50.
  • an evanescent interaction an interaction occurs between the light in the clad 32 and the metal film 50, a change appears on the spectrum as an optical loss, the reflectivity changes, and in most cases In some cases, the reflectance of light decreases and the intensity of reflected light decreases.
  • the presence of the metal film 50 causes the energy of light to be lost and lost to create a surface plasmon resonance wave by a phenomenon called surface plasmon resonance (SPR). Therefore, the presence of the metal film 50 can increase the change in reflectivity and facilitate the measurement of the change in light intensity.
  • SPR surface plasmon resonance
  • the reflection spectrum of the light in the clad 32 changes according to the refractive index of the film 60 whose refractive index changes according to the humidity which is a substance in contact with the metal film 50.
  • the wavelength causing surface plasmon resonance changes, and this causes a change in the attenuation peak wavelength of the spectrum of the reflected light in the cladding 32.
  • the refractive index of the film 60 can be measured by measuring the spectrum of the reflected light in the hetero-core part 3, and here, the refractive index and the atmospheric humidity of the film 60 whose refractive index changes according to the humidity can be measured. By relating in advance, the humidity value in the atmosphere can be obtained from the refractive index of the film 60.
  • the leak W increases and the loss of sensor light to be transmitted also increases.
  • the leak W is reduced, the loss is also reduced.
  • the magnitude of the leak W that is, the amount of loss of sensor light changes sharply due to changes in the bending of the optical fibers 20a and 20b in the vicinity of the sensor unit SP.
  • the optical fibers 20a and 20b can be bent and held so as to have a certain radius of curvature at the sandwiched position, and the leakage can be adjusted to increase the measurement sensitivity due to the surface plasmon phenomenon. Measurement sensitivity can be improved.
  • the outer periphery of the metal film 50 is a surface plasmon sensor in which a light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b.
  • a film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • a protonated amino group (—NH 3+) is introduced into the surface of the metal film 50 by treatment with an ion coupling agent, and then It can be produced by alternately immersing in a solution of a polymer having an ionized carboxylic acid group (—COO—) and a solution of a polymer having a protonated amino group (—NH 3+).
  • the film thickness of each polyion layer can be adjusted by the concentration of the polymer solution, the immersion time, and the like.
  • a carboxylic acid group (—COO—) ionized on the surface of the metal film 50 by treatment with an ion coupling agent is introduced, and then a polymer solution having a protonated amino group (—NH 3+); It may be alternately immersed in a polymer solution having ionized carboxylic acid groups (—COO—).
  • the gelatin film can be formed, for example, by applying a gelatin aqueous solution to the metal film 50 and drying it.
  • FIGS. 3A and 3B are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion SP of the optical fiber type surface plasmon humidity sensor used in the humidity measuring apparatus of the present embodiment.
  • the diameter bl of the core 31 of the hetero-core part 3 which is a light transmitting member constituting the sensor part SP is larger than the diameter al of the core 21 of the optical fibers 20a and 20b.
  • a metal film 50 is formed on the outer peripheral surface of the hetero core portion 3.
  • the light transmitting member 30 that is not a hetero-core part and made of a material having a refractive index equivalent to the refractive index of the core 21 of the optical fibers 20a and 20b or the refractive index of the cladding 22 is used as the sensor part SP.
  • the fiber 20a, 20b is joined to the middle part.
  • a metal film 50 is formed on the outer peripheral surface of the light transmitting member 30, and a film 60 whose refractive index changes according to the humidity in the atmosphere, such as a polyion film or a gelatin film, is provided on the outer peripheral surface. .
  • the configuration of the present embodiment other than the above is substantially the same as that of the first embodiment.
  • the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • the humidity measuring device is provided with a sensor part SP in the middle of the optical fibers 20a and 20b.
  • An optical coupler 16 is provided in the middle of the optical fiber 20a, and the optical fiber 20c is branched in the optical coupler 16, and a reflecting portion (mirror) 15 formed by vapor-depositing silver at the end of the optical fiber 20b. Is provided.
  • the end of the optical fiber 20a is the light incident end, and the end of the optical fiber 20c is the light emitting end.
  • a light source 11 is provided at the light incident end of the optical fiber 20a, and a spectrum analyzer 12 is provided at the light emitting end of the optical fiber 20c.
  • the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • this humidity measuring device is provided with a sensor part SP in the middle of optical fibers 20a and 20b.
  • a light source 11a for emitting sensor light such as a laser diode or a light emitting diode is provided at the light incident end of the optical fiber 20a, and an optical multimeter for detecting sensor light emitted from the light emitting end at the light emitting end of the optical fiber 20b.
  • the laser diode or the light emitting diode emits light of a single wavelength
  • an optical multimeter that can monitor the light intensity without being split can be used for the light receiving portion.
  • the emission wavelength of a laser diode or a light emitting diode is selected as the wavelength at which surface plasmon resonance occurs, and the refractive index change of the film 60 whose refractive index changes according to humidity from the attenuation of light intensity monitored by an optical multimeter. Can be detected.
  • the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • a humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a fifth embodiment of the present invention will be described. Referring to FIG. 6, this humidity measuring device is provided with a sensor part SP in the middle of the optical fibers 20a and 20b.
  • An optical coupler 16 is provided in the middle of the optical fiber 20a, and the optical fiber 20c is branched at the optical coupler 16.
  • the end of the optical fiber 20a is the light incident end, and the end of the optical fiber 20c is the light exit end.
  • a light source 11a that emits sensor light such as a laser diode or a light emitting diode is provided at the light incident end of the optical fiber 20a, and an optical multimeter that detects sensor light emitted from the light emitting end at the light emitting end of the optical fiber 20c. 12a is provided.
  • the laser diode or the light emitting diode emits light of a single wavelength
  • an optical multimeter that can monitor the light intensity without being split can be used for the light receiving portion.
  • the emission wavelength of a laser diode or a light emitting diode is selected as the wavelength at which surface plasmon resonance occurs, and the refractive index change of the film 60 whose refractive index changes according to humidity from the attenuation of light intensity monitored by an optical multimeter. Can be detected.
  • the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • a humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a sixth embodiment of the present invention will be described.
  • the humidity measuring device is provided with a sensor part SP in the middle of the optical fibers 20a and 20b.
  • An OTDR (Optical time-domain reflectometer) device 70 is connected to the optical fiber 20a.
  • the OTDR device 70 itself detects Rayleigh scattered light behind the sensor light incident from the OTDR device 70.
  • the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • this humidity measurement device an optical fiber 20a, the sensor unit SP 1 is provided in an intermediate portion of the 20b, the optical fiber 20b, the sensor unit SP 2 in the middle portion of the 20c provided, further optical fibers 20c, the sensor unit SP 3 in the middle of 20d are provided. That is, a plurality of sensor units SP 1 to SP 3 are connected in series on one optical fiber.
  • An OTDR device 70 is connected to the optical fiber 20a. When the sensor light from the OTDR apparatus 70 is incident, the Rayleigh scattered light backward is generated in each of the plurality of sensor portions SP 1 to SP 3, which OTDR apparatus 70 is detected.
  • the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
  • a humidity measurement apparatus using a Kretschmann type surface plasmon humidity sensor according to an eighth embodiment of the present invention will be described.
  • a metal film 50 that generates surface plasmons by reflection of light in the light-transmitting substrate on the surface is formed on the surface of a light-transmitting substrate 80 made of a glass substrate or the like.
  • a film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the upper layer of the metal film 50.
  • the metal film 50 and the film 60 whose refractive index changes according to the humidity in the atmosphere are the same as those described in the first embodiment.
  • a humidity measuring device can be configured by combining a light source and a light receiving unit.
  • FIG. 10A shows a perspective view of the vicinity of the sensor part SP of the optical fiber type humidity sensor used in the humidity measuring apparatus of the present embodiment
  • FIG. 10B shows a longitudinal sectional view of the vicinity of the sensor part SP. Show.
  • the optical fiber type surface plasmon humidity sensor used in the humidity measuring apparatus of the present embodiment is provided with a sensor unit SP between one optical fiber 20a and the other optical fiber 20b, which are multimode fibers having a core diameter of 50 ⁇ m, for example. It is the structure which was made.
  • the sensor unit SP is provided on the outer surface of the hetero core unit 3 that is a light transmitting member that causes a part of transmitted light to interact with the outside world, and the refractive index changes according to the humidity in the atmosphere.
  • the metal film 50 is substantially omitted in FIGS. 2A and 2B.
  • the optical fibers 20a and 20b have a core 21 and a cladding 22 provided on the outer periphery thereof, and the hetero-core portion 3 has a core 31 having a core diameter different from that of the optical fibers 20a and 20b, and an outer periphery thereof. And a clad 32 provided on the portion.
  • the length cl of the heterocore part 3 is 1 mm to several cm.
  • the hetero-core part 3 and the optical fibers 20a and 20b constituting the sensor part SP are, for example, substantially coaxial so that the cores are joined at the interface 4 orthogonal to the longitudinal direction, for example, by fusion using a generalized discharge. Are joined.
  • optical fibers 20a and 20b and the hetero core section 3 for example, any of a single mode optical fiber and a multimode optical fiber can be used, and these may be used in combination.
  • the film 60 whose refractive index changes according to the humidity in the atmosphere is formed on the hetero core portion 3 of the sensor portion SP according to the present embodiment so as to cover the surface side.
  • the film 60 whose refractive index changes according to the humidity in the atmosphere is the same as in the first embodiment, and is, for example, a plurality of stacked polyion films or gelatin films.
  • the diameter bl of the core 31 in the hetero core part 3 and the diameter al of the core 21 of the optical fibers 20a and 20b are the interface 4. Is different. Due to the difference in the core diameter, as shown in FIG. 2A, a leak W to the clad 32 of the hetero-core portion 3 that is a part of the light occurs.
  • the refractive index of the film 60 whose refractive index changes according to the humidity in the atmosphere the leakage of light leaked to the cladding 32, that is, the loss changes.
  • the refractive index of the film 60 whose refractive index changes increases, and the loss increases.
  • the refractive index of the film 60 whose refractive index changes decreases, and the loss decreases.
  • the humidity value in the atmosphere can be obtained from the transmission loss by relating the transmission loss and the atmospheric humidity in advance.
  • the outer peripheral surface of the light transmitting member is an optical fiber type sensor in which a light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b. Further, a film 60 whose refractive index changes according to the humidity in the atmosphere is provided, and the sensitivity to the humidity in the atmosphere can be improved.
  • the metal film 50 is not formed in the configuration shown in the second embodiment, and a film in which the refractive index changes directly according to humidity is formed on the outer peripheral surface of the light transmitting member. It can also be.
  • the humidity measuring device can be applied to the configurations of the third to seventh embodiments.
  • the present invention is not limited to the above description.
  • the light source and the light receiving unit used are not limited to those described above, and various types can be used.
  • the optical fiber can be a multimode fiber or a single mode fiber.
  • various modifications can be made without departing from the scope of the present invention.
  • the optical fiber type surface plasmon humidity sensor, surface plasmon humidity sensor, and optical fiber type humidity sensor of the present invention can be applied as a head of a humidity measuring device.
  • the humidity measuring device of the present invention can be applied as a device for measuring humidity easily.

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Abstract

Disclosed are a surface plasmon humidity sensor with which sensitivity to humidity can be improved, a surface plasmon humidity sensor, an optical fiber type of humidity sensor, and a humidity measurement device. A sensor part SP arranged midway on optical fibers (20a, 20b) has a hetero-core part (3) that causes part of the transmitted light to interact with the outside. A metal film (50) that generates surface plasmons by reflecting the light in a light transmissive member on the outer peripheral surface of said hetero-core part (3) is formed on said outer peripheral surface. A film (60) whose refractive index changes according to the humidity in the atmosphere is formed on the outer peripheral surface of metal film (50).

Description

湿度センサ及び湿度測定装置Humidity sensor and humidity measuring device
　本発明は、光ファイバを用いた表面プラズモン湿度センサ、表面プラズモン湿度センサ、光ファイバ型湿度センサ、及びこれらの湿度センサを用いた湿度測定装置に関する。 The present invention relates to a surface plasmon humidity sensor using an optical fiber, a surface plasmon humidity sensor, an optical fiber type humidity sensor, and a humidity measuring apparatus using these humidity sensors.
　測定対象の検出に表面プラズモン現象を利用した表面プラズモンセンサが知られている。表面プラズモンセンサの一種として知られているクレッチマン型表面プラズモンセンサは、ガラス製の平板に金属膜を設け、この金属膜を測定対象試料に接触させる構成になっている。そして、ガラスを介して金属膜に光を入射させると、金属膜に対する光の入射角と金属膜に接触している測定対象試料の屈折率とが所定の関係を満たすときに、表面プラズモン共鳴が発生して反射光の強度が低下する。従って、反射光が減衰する入射角を検出することによって得られる測定対象試料の屈折率を、測定対象の測定に利用することができる。 A surface plasmon sensor that uses the surface plasmon phenomenon for detection of a measurement object is known. A Kretschmann type surface plasmon sensor known as a kind of surface plasmon sensor has a structure in which a metal film is provided on a flat plate made of glass and the metal film is brought into contact with a sample to be measured. When light is incident on the metal film through the glass, surface plasmon resonance occurs when the incident angle of the light with respect to the metal film and the refractive index of the sample to be measured in contact with the metal film satisfy a predetermined relationship. It occurs and the intensity of reflected light decreases. Therefore, the refractive index of the measurement target sample obtained by detecting the incident angle at which the reflected light attenuates can be used for measurement of the measurement target.
　ところが、上述のクレッチマン型表面プラズモンセンサは、ガラス板に光を入射させて、反射光が減衰するときの入射角を調べる必要があるため、例えば遠隔地におけるｉｎ ｓｉｔｕ測定（その場測定）は困難であり、小型化も難しいという問題がある。 However, since the above-mentioned Kretschmann type surface plasmon sensor needs to make the light incident on the glass plate and examine the incident angle when the reflected light is attenuated, for example, in-situ measurement (situ measurement) in a remote place is difficult. There is a problem that downsizing is difficult.
　一方、特許文献１及び２に開示されているように、ヘテロコア型の光ファイバセンサが開発されている。そして、上記のクレッチマン型表面プラズモンセンサの持つ問題に対応するため、光ファイバを用いた表面プラズモンセンサが開発され、例えば特許文献３及び４に開示されている。 On the other hand, as disclosed in Patent Documents 1 and 2, hetero-core type optical fiber sensors have been developed. And in order to cope with the problem which said Kretschmann type | mold surface plasmon sensor has, the surface plasmon sensor using an optical fiber was developed and is disclosed by patent document 3 and 4, for example.
　特許文献３及び４においては、光ファイバの中途部または端部に、コア径が異なるヘテロコア部と呼ばれる部分を融着接合して設け、ヘテロコア部の表面に表面プラズモンを発生させるための金属膜を設けた構成が開示されている。
国際公開９７／４８９９４号パンフレット 特開２００３－２１４９０６号公報 特開２００２－３５０３３５号公報 特開２００６－０４７０１８号公報 笠井，「表面プラズモン共鳴（SPR）を利用したバイオセンサー」蛋白質 核酸 酵素，Vol.３７，No.１５（１９９２年）p2977-2984 In Patent Documents 3 and 4, a metal film for generating surface plasmons on the surface of the hetero-core part is provided by fusion-bonding a part called a hetero-core part having a different core diameter at the middle part or end part of the optical fiber. The provided arrangement is disclosed.
International Publication No. 97/48994 Pamphlet JP 2003-214906 A JP 2002-350335 A JP 2006-047018 A Kasai, "Biosensor Using Surface Plasmon Resonance (SPR)" Protein Nucleic Acid Enzyme, Vol. 37, No. 15 (1992) p2977-2984
　しかしながら、特許文献３及び４に記載のヘテロコア部をセンサとして用いた表面プラズモンセンサは、雰囲気中の湿度を高感度に感知することはできない。そこで、さらなる感度の向上が求められていた。 However, the surface plasmon sensor using the hetero core part described in Patent Documents 3 and 4 cannot sense humidity in the atmosphere with high sensitivity. Therefore, further improvement in sensitivity has been demanded.
　本発明は、以上の点に鑑み、湿度に対する感度を向上させた光ファイバ型表面プラズモン湿度センサ、表面プラズモン湿度センサ、光ファイバ型湿度センサ、及びこれらの湿度センサを用いた湿度測定装置を提供することをその課題としている。 In view of the above, the present invention provides an optical fiber type surface plasmon humidity sensor, a surface plasmon humidity sensor, an optical fiber type humidity sensor, and a humidity measuring device using these humidity sensors, which have improved sensitivity to humidity. That is the issue.
　本発明の光ファイバ型表面プラズモン湿度センサは、光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、前記外周表面における前記光透過部材中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜とを有する。 An optical fiber type surface plasmon humidity sensor according to the present invention includes an optical fiber, a light transmission member provided in a middle portion of the optical fiber, and a part of transmitted light interacts with the outside, and an outer peripheral surface of the light transmission member A metal film that generates surface plasmons by reflection of light in the light transmitting member on the outer peripheral surface, and a film that is provided on the outer peripheral surface of the metal film and has a refractive index that changes according to the humidity in the atmosphere. And have.
　すなわち、上記の本発明の光ファイバ型表面プラズモン湿度センサは、光ファイバの中途部に、伝送する光の一部を外界と相互作用させる光透過部材が設けられ、その外周表面に、当該外周表面における光透過部材中の光の反射により表面プラズモンを発生する金属膜が設けられ、金属膜の外周表面に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられている。 That is, the above-described optical fiber type surface plasmon humidity sensor of the present invention is provided with a light transmission member that causes a part of transmitted light to interact with the outside world in the middle part of the optical fiber, and the outer peripheral surface has the outer peripheral surface. A metal film that generates surface plasmon by reflection of light in the light transmitting member is provided, and a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface of the metal film.
　上記の本発明の光ファイバ型表面プラズモン湿度センサにおいて、好適には、前記屈折率が変化する膜は、複数の積層されたポリイオン膜である。あるいは好適には、前記屈折率が変化する膜は、ゼラチン膜である。 In the above-described optical fiber type surface plasmon humidity sensor according to the present invention, preferably, the film whose refractive index changes is a plurality of stacked polyion films. Alternatively, preferably, the film whose refractive index changes is a gelatin film.
　上記の本発明の光ファイバ型表面プラズモン湿度センサにおいて、好適には、前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である。あるいは好適には、前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である。 In the above-described optical fiber type surface plasmon humidity sensor of the present invention, preferably, the light transmitting member is a hetero-core portion having a core diameter different from the core diameter of the optical fiber. Alternatively, preferably, the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
　上記の本発明の光ファイバ型表面プラズモン湿度センサにおいて、好適には、前記光ファイバがマルチモード光ファイバである。また、好適には、前記光ファイバの一方の端部が２本に分岐して光の入射端及び出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている。 In the above-described optical fiber type surface plasmon humidity sensor of the present invention, preferably, the optical fiber is a multimode optical fiber. Preferably, one end of the optical fiber is branched into two to provide a light incident end and an output end, and the other end of the optical fiber reflects light transmitted through the optical fiber. Then, a reflection part for returning to the optical fiber is provided.
　また、本発明の表面プラズモン湿度センサは、光透過性基板と、前記光透過性基板の表面に設けられ、前記表面における前記光透過性基板中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の上層に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜とを有する。 The surface plasmon humidity sensor of the present invention includes a light transmissive substrate, a metal film that is provided on the surface of the light transmissive substrate, and generates surface plasmons by reflection of light in the light transmissive substrate on the surface. And a film provided on an upper layer of the metal film, the refractive index of which changes according to the humidity in the atmosphere.
　すなわち、上記の本発明の表面プラズモン湿度センサは、光透過性基板の表面に、当該表面における光透過性基板中の光の反射により表面プラズモンを発生する金属膜が設けられ、金属膜の上層に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられている。 That is, in the surface plasmon humidity sensor of the present invention described above, a metal film that generates surface plasmons by reflection of light in the light-transmitting substrate on the surface is provided on the surface of the light-transmitting substrate, and the upper layer of the metal film. A film whose refractive index changes according to the humidity in the atmosphere is provided.
　また、本発明の光ファイバ型湿度センサは、光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜とを有する。 The optical fiber type humidity sensor of the present invention includes an optical fiber, a light transmissive member provided in the middle of the optical fiber, allowing a part of transmitted light to interact with the outside world, and an outer peripheral surface of the light transmissive member. And a film whose refractive index changes depending on the humidity in the atmosphere.
　すなわち、上記の本発明の光ファイバ型湿度センサは、光ファイバの中途部に、伝送する光の一部を外界と相互作用させる光透過部材が設けられ、その外周表面に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられている。 That is, in the above-described optical fiber type humidity sensor of the present invention, a light transmission member that causes a part of transmitted light to interact with the outside world is provided in the middle of the optical fiber, and the outer peripheral surface thereof is adjusted to the atmospheric humidity. A film whose refractive index changes accordingly is provided.
　上記の本発明の光ファイバ型湿度センサにおいて、好適には、前記屈折率が変化する膜は、複数の積層されたポリイオン膜である。あるいは好適には、前記屈折率が変化する膜は、ゼラチン膜である。 In the above-described optical fiber type humidity sensor of the present invention, preferably, the film whose refractive index changes is a plurality of stacked polyion films. Alternatively, preferably, the film whose refractive index changes is a gelatin film.
　上記の本発明の光ファイバ型湿度センサにおいて、好適には、前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である。あるいは好適には、前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である。 In the above-described optical fiber type humidity sensor of the present invention, preferably, the light transmitting member is a hetero core portion having a core diameter different from the core diameter of the optical fiber. Alternatively, preferably, the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
　上記の本発明の光ファイバ型湿度センサにおいて、好適には、前記光ファイバがマルチモード光ファイバである。あるいは好適には、前記光ファイバの一方の端部が２本に分岐して光の入射端及び出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている。 In the above-described optical fiber type humidity sensor of the present invention, preferably, the optical fiber is a multimode optical fiber. Alternatively, preferably, one end portion of the optical fiber is branched into two, and an incident end and an exit end of light are provided, and light transmitted through the optical fiber is reflected to the other end portion of the optical fiber. And a reflecting portion for returning to the optical fiber.
　また、本発明の湿度測定装置は、光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、前記外周表面における前記光透過部材中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜と、前記光ファイバの入射端に対してセンサ光を出射する光源と、前記光透過部材を介して前記光ファイバの出射端から出射される前記センサ光を検出する受光部とを有する。 In addition, the humidity measuring device of the present invention is provided on the optical fiber, a light transmission member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, and an outer peripheral surface of the light transmission member. A metal film that generates surface plasmons by reflection of light in the light transmitting member on the outer peripheral surface, a film that is provided on the outer peripheral surface of the metal film, and whose refractive index changes according to humidity in the atmosphere, A light source configured to emit sensor light to the incident end of the optical fiber; and a light receiving unit configured to detect the sensor light emitted from the output end of the optical fiber via the light transmitting member.
　すなわち、上記の本発明の湿度測定装置は、光ファイバの中途部に、伝送する光の一部を外界と相互作用させる光透過部材が設けられ、その外周表面に、当該外周表面における光透過部材中の光の反射により表面プラズモンを発生する金属膜が設けられ、金属膜の外周表面に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられている。さらに、光源が設けられて光ファイバの入射端に対してセンサ光を出射し、受光部が設けられて光透過部材を介して光ファイバの出射端から出射されるセンサ光を検出する構成となっている。 That is, in the humidity measuring apparatus of the present invention, a light transmission member that causes a part of transmitted light to interact with the outside world is provided in the middle part of the optical fiber, and the light transmission member on the outer peripheral surface is provided on the outer peripheral surface thereof. A metal film that generates surface plasmons by reflection of light therein is provided, and a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface of the metal film. Further, a light source is provided to emit sensor light to the incident end of the optical fiber, and a light receiving unit is provided to detect the sensor light emitted from the output end of the optical fiber via the light transmitting member. ing.
　上記の本発明の湿度測定装置において、好適には、前記屈折率が変化する膜は、複数の積層されたポリイオン膜である。あるいは好適には、前記屈折率が変化する膜は、ゼラチン膜である。 In the humidity measuring apparatus according to the present invention, preferably, the film whose refractive index changes is a plurality of stacked polyion films. Alternatively, preferably, the film whose refractive index changes is a gelatin film.
　上記の本発明の湿度測定装置において、好適には、前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である。あるいは好適には、前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である。 In the humidity measuring apparatus of the present invention described above, preferably, the light transmitting member is a hetero-core portion having a core diameter different from the core diameter of the optical fiber. Alternatively, preferably, the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
　上記の本発明の湿度測定装置において、好適には、前記光ファイバがマルチモード光ファイバである。あるいは好適には、前記光ファイバの一方の端部が２本に分岐して前記入射端及び前記出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている。 In the humidity measuring apparatus according to the present invention, preferably, the optical fiber is a multimode optical fiber. Alternatively, preferably, one end portion of the optical fiber is branched into two to provide the incident end and the output end, and reflects light transmitted through the optical fiber to the other end portion of the optical fiber. And a reflecting portion for returning to the optical fiber.
　また、本発明の湿度測定装置は、光透過性基板と、前記光透過性基板の表面に設けられ、前記表面における前記光透過性基板中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の上層に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜と、前記光透過性基板の内側から前記金属膜と前記光透過性基板の界面に向けてセンサ光を出射する光源と、前記金属膜と前記光透過性基板の界面から反射した前記センサ光を検出する受光部とを有する。 Further, the humidity measuring device of the present invention is a light transmissive substrate, a metal film that is provided on the surface of the light transmissive substrate and generates surface plasmons by reflection of light in the light transmissive substrate on the surface, Sensor light is emitted from the inner side of the light-transmitting substrate toward the interface between the metal film and the light-transmitting substrate, provided on the upper layer of the metal film and having a refractive index that changes according to the humidity in the atmosphere. And a light receiving unit that detects the sensor light reflected from the interface between the metal film and the light transmissive substrate.
　すなわち、上記の本発明の湿度測定装置は、光透過性基板の表面に、当該表面における光透過性基板中の光の反射により表面プラズモンを発生する金属膜が設けられ、金属膜の上層に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられている。さらに、光源が設けられて光透過性基板の内側から金属膜と光透過性基板の界面に向けてセンサ光を出射し、受光部が設けられて金属膜と光透過性基板の界面から反射したセンサ光を検出する構成となっている。 That is, in the humidity measuring device of the present invention described above, a metal film that generates surface plasmons by reflection of light in the light-transmitting substrate on the surface is provided on the surface of the light-transmitting substrate. A film whose refractive index changes according to the humidity in the atmosphere is provided. Furthermore, a light source is provided to emit sensor light from the inside of the light transmissive substrate toward the interface between the metal film and the light transmissive substrate, and a light receiving unit is provided to reflect from the interface between the metal film and the light transmissive substrate. The sensor light is detected.
　また、本発明の湿度測定装置は、光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜と、前記光ファイバの入射端に対してセンサ光を出射する光源と、前記光透過部材を介して前記光ファイバの出射端から出射される前記センサ光を検出する受光部とを有する。 In addition, the humidity measuring device of the present invention is provided on the optical fiber, a light transmission member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, and an outer peripheral surface of the light transmission member. A film whose refractive index changes according to the humidity in the atmosphere, a light source that emits sensor light to the incident end of the optical fiber, and an output end of the optical fiber through the light transmitting member. And a light receiving portion for detecting the sensor light.
　すなわち、上記の本発明の湿度測定装置は、光ファイバの中途部に、伝送する光の一部を外界と相互作用させる光透過部材が設けられ、その外周表面に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられている。さらに、光源が設けられて光ファイバの入射端に対してセンサ光を出射し、受光部が設けられて光透過部材を介して光ファイバの出射端から出射されるセンサ光を検出する構成となっている。 That is, in the humidity measuring apparatus of the present invention described above, a light transmission member that causes a part of the transmitted light to interact with the outside world is provided in the middle of the optical fiber, and the outer peripheral surface thereof has a humidity according to the humidity in the atmosphere. A film whose refractive index changes is provided. Further, a light source is provided to emit sensor light to the incident end of the optical fiber, and a light receiving unit is provided to detect the sensor light emitted from the output end of the optical fiber via the light transmitting member. ing.
　上記の本発明の湿度測定装置において、好適には、前記屈折率が変化する膜は、複数の積層されたポリイオン膜である。あるいは好適には、前記屈折率が変化する膜は、ゼラチン膜である。 In the humidity measuring apparatus according to the present invention, preferably, the film whose refractive index changes is a plurality of stacked polyion films. Alternatively, preferably, the film whose refractive index changes is a gelatin film.
　上記の本発明の湿度測定装置において、好適には、前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である。あるいは好適には、前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である。 In the humidity measuring apparatus of the present invention described above, preferably, the light transmitting member is a hetero-core portion having a core diameter different from the core diameter of the optical fiber. Alternatively, preferably, the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
　上記の本発明の湿度測定装置において、好適には、前記光ファイバがマルチモード光ファイバである。あついは好適には、前記光ファイバの一方の端部が２本に分岐して前記入射端及び前記出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている。 In the humidity measuring apparatus according to the present invention, preferably, the optical fiber is a multimode optical fiber. Preferably, one end of the optical fiber is branched into two to provide the incident end and the output end, and the other end of the optical fiber reflects light transmitted through the optical fiber. Then, a reflection part for returning to the optical fiber is provided.
　上記の本発明の表面プラズモン湿度センサは、光ファイバの中途部にヘテロコア部などの光透過部材が設けられた光ファイバ型などの表面プラズモンセンサにおいて、金属膜の外周表面あるいは上層に雰囲気中の湿度に応じて屈折率が変化する膜が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 The surface plasmon humidity sensor of the present invention is an optical fiber type surface plasmon sensor in which a light transmitting member such as a hetero core is provided in the middle of an optical fiber, and the humidity in the atmosphere on the outer peripheral surface or upper layer of the metal film. Accordingly, a film whose refractive index changes according to the above is provided, and the sensitivity to humidity in the atmosphere can be improved.
　上記の本発明の光ファイバ型湿度センサは、光ファイバの中途部に設けられたヘテロコア部などの光透過部材の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 In the above-described optical fiber type humidity sensor of the present invention, a film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface of a light transmitting member such as a hetero core provided in the middle of the optical fiber. The sensitivity to the humidity in the atmosphere can be improved.
　上記の本発明の湿度測定装置は、本発明の表面プラズモン湿度センサあるいは光ファイバ型湿度センサにおいて、表面プラズモン湿度センサの金属膜の外周表面または上層、あるいは、光ファイバ型湿度センサの光透過部材の外周表面に、雰囲気中の湿度に応じて屈折率が変化する膜が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 The humidity measuring apparatus of the present invention described above is the surface plasmon humidity sensor or optical fiber type humidity sensor of the present invention, wherein the outer peripheral surface or upper layer of the metal film of the surface plasmon humidity sensor, or the light transmitting member of the optical fiber type humidity sensor. A film whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
本発明の第１実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor which concerns on 1st Embodiment of this invention. 図２（ａ）本発明の第１実施形態に係る光ファイバ型表面プラズモン湿度センサのセンサ部近傍の斜視図であり、図２（ｂ）は、センサ部近傍の長手方向の断面図である。FIG. 2A is a perspective view of the vicinity of the sensor portion of the optical fiber type surface plasmon humidity sensor according to the first embodiment of the present invention, and FIG. 2B is a longitudinal sectional view of the vicinity of the sensor portion. 図３（ａ）及び図３（ｂ）は、本発明の第２実施形態に係る光ファイバ型表面プラズモン湿度センサのセンサ部近傍の長手方向の断面図である。FIGS. 3A and 3B are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion of the optical fiber type surface plasmon humidity sensor according to the second embodiment of the present invention. 本発明の第３実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor which concerns on 3rd Embodiment of this invention. 本発明の第４実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor which concerns on 4th Embodiment of this invention. 本発明の第５実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor which concerns on 5th Embodiment of this invention. 本発明の第６実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor which concerns on 6th Embodiment of this invention. 本発明の第７実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor which concerns on 7th Embodiment of this invention. 本発明の第８実施形態に係るクレッチマン型表面プラズモン湿度センサの構成を示す模式図である。It is a schematic diagram which shows the structure of the Kretschmann type | mold surface plasmon humidity sensor which concerns on 8th Embodiment of this invention. 図１０（ａ）は、本発明の第９実施形態に係る光ファイバ型湿度センサのセンサ部近傍の斜視図であり、図１０（ｂ）は、センサ部近傍の長手方向の断面図である。FIG. 10A is a perspective view of the vicinity of the sensor portion of the optical fiber type humidity sensor according to the ninth embodiment of the present invention, and FIG. 10B is a longitudinal sectional view of the vicinity of the sensor portion.
符号の説明Explanation of symbols
　３…ヘテロコア部、４…界面、１０…光ファイバ、１１，１１ａ…光源、１２…受光部、１２ａ…光マルチメータ、１５…反射部、１６…光カプラ、２０ａ，２０ｂ，２０ｃ，２０ｄ…光ファイバ、２１，３１…コア、２２，３２…クラッド、３０…光透過部材、５０…金属膜、６０…膜、７０…ＯＴＤＲ装置、８０…光透過性基板、ＳＰ，ＳＰ１，ＳＰ２，ＳＰ３…センサ部、Ｗ…リーク、Ｌｉｎ…光、Ｌｏｕｔ…反射光 DESCRIPTION OF SYMBOLS 3 ... Hetero core part, 4 ... Interface, 10 ... Optical fiber, 11, 11a ... Light source, 12 ... Light receiving part, 12a ... Optical multimeter, 15 ... Reflection part, 16 ... Optical coupler, 20a, 20b, 20c, 20d ... Light fiber, 21 and 31 ... core, 22, 32 ... clad, 30 ... light transmitting member, 50 ... metal film, 60 ... film, 70 ... OTDR apparatus, 80 ... light transmitting substrate, SP, SP 1, SP 2 , SP 3 ... sensor unit, W ... leak, Lin ... light, Lout ... reflected light
　以下に、本発明の光ファイバ型表面プラズモン湿度センサ、表面プラズモン湿度センサ、光ファイバ型湿度センサ、及びこれらを用いた湿度測定装置の実施形態について、図面を参照して説明する。
［第１実施形態］
　本発明の第１実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図１を参照して、この湿度測定装置には、光ファイバ２０ａ，２０ｂの中途部にセンサ部ＳＰが設けられている。また、光ファイバ２０ａの光入射端に、白色光源などのセンサ光を出射する光源１１が設けられ、光ファイバ２０ｂの光出射端に、光出射端から出射されるセンサ光を検出するフォトダイオードやパワーメータなどの受光部を備えたスペクトラムアナライザ１２が設けられている。センサ部ＳＰは測定対象雰囲気下に置かれ、このときのセンサ光の測定によって測定対象雰囲気の湿度が測定される。 DESCRIPTION OF EMBODIMENTS Embodiments of an optical fiber type surface plasmon humidity sensor, a surface plasmon humidity sensor, an optical fiber type humidity sensor, and a humidity measuring device using these will be described below with reference to the drawings.
[First Embodiment]
A humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor according to the first embodiment of the present invention will be described. With reference to FIG. 1, this humidity measuring device is provided with a sensor part SP in the middle of optical fibers 20a and 20b. In addition, a light source 11 that emits sensor light such as a white light source is provided at the light incident end of the optical fiber 20a, and a photodiode that detects sensor light emitted from the light emitting end is provided at the light emitting end of the optical fiber 20b. A spectrum analyzer 12 having a light receiving unit such as a power meter is provided. The sensor unit SP is placed in the measurement target atmosphere, and the humidity of the measurement target atmosphere is measured by measuring the sensor light at this time.
　本実施形態の湿度測定装置に用いられる光ファイバ型表面プラズモン湿度センサのセンサ部ＳＰ近傍の斜視図を図２（ａ）に示し、センサ部ＳＰ近傍の長手方向の断面図を図２（ｂ）に示す。光ファイバ型表面プラズモン湿度センサは、例えば、コア径５０μｍのマルチモードファイバである一方の光ファイバ２０ａと他方の光ファイバ２０ｂの間に、センサ部ＳＰが設けられた構成である。センサ部ＳＰは、伝送する光の一部を外界と相互作用させる光透過部材であるヘテロコア部３と、ヘテロコア部３の外周表面に設けられ、ヘテロコア部３の外周表面における光透過部材中の光の反射により表面プラズモンを発生する金属膜５０と、金属膜５０の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜６０とを有する。 FIG. 2A shows a perspective view of the vicinity of the sensor part SP of the optical fiber type surface plasmon humidity sensor used in the humidity measuring apparatus of the present embodiment, and FIG. 2B shows a longitudinal sectional view of the vicinity of the sensor part SP. Shown in The optical fiber type surface plasmon humidity sensor has a configuration in which, for example, a sensor unit SP is provided between one optical fiber 20a and the other optical fiber 20b which are multimode fibers having a core diameter of 50 μm. The sensor part SP is provided on the outer peripheral surface of the heterocore part 3 that is a light transmitting member that causes a part of the transmitted light to interact with the outside world, and the light in the light transmitting member on the outer peripheral surface of the heterocore part 3. A metal film 50 that generates surface plasmons by reflection of the light, and a film 60 that is provided on the outer peripheral surface of the metal film 50 and whose refractive index changes according to the humidity in the atmosphere.
　光ファイバ２０ａ，２０ｂは、コア２１と、その外周部に設けられたクラッド２２とを有する。ヘテロコア部３は、光ファイバ２０ａ，２０ｂのコア径と異なるコア径を有するコア３１と、その外周部に設けられたクラッド３２とを有する。また、ヘテロコア部３におけるコア３１の径ｂｌは、光ファイバ２０ａ，２０ｂのコア２１の径ａｌより小さく、例えばａｌ＝５０μｍ、ｂｌ＝３μｍである。また、ヘテロコア部３の長さｃｌは、１ｍｍ乃至数ｃｍである。 The optical fibers 20a and 20b have a core 21 and a clad 22 provided on the outer periphery thereof. The hetero core part 3 has a core 31 having a core diameter different from the core diameters of the optical fibers 20a and 20b, and a clad 32 provided on the outer peripheral part thereof. Moreover, the diameter bl of the core 31 in the hetero core part 3 is smaller than the diameter al of the core 21 of the optical fibers 20a and 20b, for example, al = 50 μm and bl = 3 μm. Moreover, the length cl of the heterocore part 3 is 1 mm to several cm.
　センサ部ＳＰを構成するヘテロコア部３と光ファイバ２０ａ，２０ｂは、長手方向に直交する界面４でコア同士が接合するようにほぼ同軸に、例えば汎用化されている放電による融着などにより、接合されている。 The hetero-core portion 3 and the optical fibers 20a and 20b constituting the sensor portion SP are joined substantially coaxially so that the cores are joined at the interface 4 orthogonal to the longitudinal direction, for example, by fusion using a generalized discharge. Has been.
　光ファイバ２０ａ，２０ｂ及びヘテロコア部３としては、例えば、シングルモード光ファイバ及びマルチモード光ファイバのいずれをも使用可能であり、これらを組み合わせて使用してもよい。 As the optical fibers 20a and 20b and the hetero core section 3, for example, any of a single mode optical fiber and a multimode optical fiber can be used, and these may be used in combination.
　本実施形態に係るセンサ部ＳＰのヘテロコア部３は、表面側を被覆するように金属膜５０が形成されている。金属膜５０は、例えば、ヘテロコア部３の外側表面に蒸着によりクロム（Ｃｒ）膜を形成し、このクロム膜上に蒸着により金（Ａｕ）の膜を形成して、クロム膜と金膜との積層膜からなる金属膜５０を形成する。クロム膜の膜厚は例えば数ｎｍ程度であり、金膜の膜厚は例えば数１０ｎｍ程度である。例えば、銀（Ａｇ）やアルミニウム（Ａｌ）等の他の金属を用いて金属膜５０を形成してもよい。詳細には後述するように、ヘテロコア部３の内部における光がヘテロコア部３と金属膜５０との境界において反射することにより、表面プラズモンが発生する。 The metal film 50 is formed so that the hetero core part 3 of the sensor part SP according to the present embodiment covers the surface side. The metal film 50 is formed, for example, by forming a chromium (Cr) film on the outer surface of the hetero core portion 3 by vapor deposition, and forming a gold (Au) film on the chromium film by vapor deposition. A metal film 50 made of a laminated film is formed. The film thickness of the chromium film is, for example, about several nm, and the film thickness of the gold film is, for example, about several tens of nm. For example, the metal film 50 may be formed using other metals such as silver (Ag) and aluminum (Al). As will be described in detail later, the surface plasmon is generated by reflection of light inside the hetero-core part 3 at the boundary between the hetero-core part 3 and the metal film 50.
　さらに、上記の金属膜５０の外周表面を被覆して、雰囲気中の湿度に応じて屈折率が変化する膜６０が形成されている。雰囲気中の湿度に応じて屈折率が変化する膜６０は、例えば、複数の積層されたポリイオン膜あるいはゼラチン膜などである。ポリイオン膜は、例えば、電離したカルボン酸基（－ＣＯＯ－）やプロトン化したアミノ基（－ＮＨ３＋）などの、正または負に帯電した官能基が多数結合されたポリマーの膜である。例えば、膜６０を、正の官能基のポリイオン膜と負の官能基のポリイオン膜などが交互に複数積層した構成とすることができる、また、ゼラチン膜も用いることが可能であり、雰囲気中の湿度に応じて屈折率が変化するものであれば用いることが可能である。ポリイオン膜などの膜６０の膜厚は、特に限定されないが、例えば、１ｎｍ乃至数μｍ程度である。 Further, the outer peripheral surface of the metal film 50 is covered, and a film 60 whose refractive index changes according to the humidity in the atmosphere is formed. The film 60 whose refractive index changes according to the humidity in the atmosphere is, for example, a plurality of stacked polyion films or gelatin films. The polyion film is a polymer film in which a large number of positively or negatively charged functional groups such as ionized carboxylic acid groups (—COO—) and protonated amino groups (—NH 3+) are bonded. For example, the film 60 can have a structure in which a plurality of positive functional group polyion films and negative functional group polyion films are alternately stacked, and a gelatin film can also be used. Any material whose refractive index varies with humidity can be used. The film thickness of the film 60 such as a polyion film is not particularly limited, but is, for example, about 1 nm to several μm.
　上記の光ファイバ２０ａ，２０ｂの中途部にヘテロコア型のセンサ部ＳＰが接合されてなる構成において、ヘテロコア部３におけるコア３１の径ｂｌと光ファイバ２０ａ，２０ｂのコア２１の径ａｌとが界面４で異なっている。このコア径の差に起因して、図２（ａ）に示すように、光の一部のヘテロコア部３のクラッド３２へのリークＷが発生する。 In the configuration in which the hetero core type sensor part SP is joined to the middle part of the optical fibers 20a and 20b, the diameter bl of the core 31 in the hetero core part 3 and the diameter al of the core 21 of the optical fibers 20a and 20b are the interface 4. Is different. Due to the difference in the core diameter, as shown in FIG. 2A, a leak W to the clad 32 of the hetero-core portion 3 that is a part of the light occurs.
　ここで、光ファイバ２０ａのコア２１内においては、センサ光は光ファイバの通常の性質から複数のモードが形成された光として伝わる。光ファイバ２０ａによって伝送される光のモードは、コア２１とクラッド２２との境界における光の反射角として模式的にとらえることも可能である。光のモードを反射角ととらえた場合には、光ファイバ２０ａにおける光の反射角は、非常に多くの離散的な角度であると考えることができる。 Here, in the core 21 of the optical fiber 20a, the sensor light is transmitted as light in which a plurality of modes are formed due to the normal properties of the optical fiber. The mode of light transmitted by the optical fiber 20a can also be schematically taken as the reflection angle of light at the boundary between the core 21 and the clad 22. When the light mode is regarded as a reflection angle, the reflection angle of the light in the optical fiber 20a can be considered as a very large number of discrete angles.
　多様なモードである光は、上記のようなリークＷによって界面４を通過してヘテロコア部３のクラッド３２に入射するときに、モードの規定が解除されてモードが崩される。言い換えれば、ヘテロコア部３内においては、クラッド３２と金属膜５０との境界において光が様々な反射角度で伝わるようになる。これは、光がヘテロコア部３へ入射するときに、モード形態を決定付ける様々な条件（コア径・屈折率・屈折率分布）が変化することと、モード形成の一つの要因であるファイバ長がヘテロコア部３の長さでは不十分であること、に起因すると考えられる。 When light having various modes passes through the interface 4 and enters the clad 32 of the hetero-core portion 3 due to the leakage W as described above, the mode is released and the mode is destroyed. In other words, in the hetero core portion 3, light is transmitted at various reflection angles at the boundary between the clad 32 and the metal film 50. This is because various conditions (core diameter, refractive index, refractive index distribution) that determine the mode form change when light is incident on the hetero-core part 3, and the fiber length that is one factor of mode formation is The length of the hetero core part 3 is considered to be insufficient.
　従って、あるモードに規定されていた光がヘテロコア部３に入射すると、そのモードの規定が解除されてモードが崩され、様々な反射角度で反射する、モードが崩された光となってクラッド３２内にリークする。 Therefore, when light defined in a certain mode is incident on the hetero-core portion 3, the mode is deregulated, the mode is destroyed, and the light is reflected at various reflection angles and becomes a mode-disrupted light. Leaks in.
　このとき、リークした光はヘテロコア部３のクラッド３２と金属膜５０との境界において反射する。このとき、エバネッセント相互作用と呼ばれる現象により、クラッド３２内の光と金属膜５０との間において相互作用が発生し、光損失としてスペクトル上に変化が現れ、反射率が変化し、大部分の場合には、光の反射率が低下して反射光の強度が減少する。 At this time, the leaked light is reflected at the boundary between the clad 32 of the hetero-core portion 3 and the metal film 50. At this time, due to a phenomenon called an evanescent interaction, an interaction occurs between the light in the clad 32 and the metal film 50, a change appears on the spectrum as an optical loss, the reflectivity changes, and in most cases In some cases, the reflectance of light decreases and the intensity of reflected light decreases.
　金属膜５０が存在することによって、表面プラズモン共鳴（Surface Plasmon Resonance：SPR）と呼ばれる現象により光のエネルギーが表面プラズモン共鳴波を作り出すために奪われ、失われる。そのため、金属膜５０を存在させることによって、反射率の変化をより大きくすることができ、光の強度変化の測定を容易化することができる。表面プラズモン共鳴現象については、例えば、非特許文献１等の文献を参照されたい。 The presence of the metal film 50 causes the energy of light to be lost and lost to create a surface plasmon resonance wave by a phenomenon called surface plasmon resonance (SPR). Therefore, the presence of the metal film 50 can increase the change in reflectivity and facilitate the measurement of the change in light intensity. For the surface plasmon resonance phenomenon, refer to a document such as Non-Patent Document 1, for example.
　ここで、金属膜５０に接している物質である湿度に応じて屈折率が変化する膜６０の屈折率に応じて、クラッド３２内の光の反射スペクトルが変化する。例えば、湿度に応じて屈折率が変化する膜６０の屈折率が変化すると、表面プラズモン共鳴を起こす波長が変化し、これにより、クラッド３２内の反射光のスペクトルの減衰ピーク波長に変化が現れる。 Here, the reflection spectrum of the light in the clad 32 changes according to the refractive index of the film 60 whose refractive index changes according to the humidity which is a substance in contact with the metal film 50. For example, when the refractive index of the film 60 whose refractive index changes according to humidity changes, the wavelength causing surface plasmon resonance changes, and this causes a change in the attenuation peak wavelength of the spectrum of the reflected light in the cladding 32.
　従って、ヘテロコア部３内の反射光のスペクトルを測定することによって、膜６０の屈折率を測定することができ、ここで、湿度に応じて屈折率が変化する膜６０の屈折率と雰囲気湿度を予め関係付けておくことで、膜６０の屈折率から、雰囲気中の湿度の値を得ることができる。 Therefore, the refractive index of the film 60 can be measured by measuring the spectrum of the reflected light in the hetero-core part 3, and here, the refractive index and the atmospheric humidity of the film 60 whose refractive index changes according to the humidity can be measured. By relating in advance, the humidity value in the atmosphere can be obtained from the refractive index of the film 60.
　上記のセンサ部ＳＰにおいて、コア２１とコア３１の径の組み合わせによっては、リークＷが大きくなり、伝送するセンサ光のロスも大きくなる。一方、リークＷが小さくなれば、ロスも小さくなる。例えば、ヘテロコア型のセンサ部ＳＰにおいて、リークＷの大きさ、即ちセンサ光のロス量は、センサ部ＳＰ近傍の光ファイバ２０ａ，２０ｂの屈曲の変化により鋭敏に変化することから、センサ部ＳＰを挟む位置である程度の曲率半径となるように光ファイバ２０ａ，２０ｂを屈曲して保持することなどによりリーク量を増やす方向に調整することができ、これによって表面プラズモン現象による測定感度が高められ、湿度測定の感度を向上できる。 In the sensor part SP, depending on the combination of the diameters of the core 21 and the core 31, the leak W increases and the loss of sensor light to be transmitted also increases. On the other hand, if the leak W is reduced, the loss is also reduced. For example, in the hetero-core type sensor unit SP, the magnitude of the leak W, that is, the amount of loss of sensor light changes sharply due to changes in the bending of the optical fibers 20a and 20b in the vicinity of the sensor unit SP. The optical fibers 20a and 20b can be bent and held so as to have a certain radius of curvature at the sandwiched position, and the leakage can be adjusted to increase the measurement sensitivity due to the surface plasmon phenomenon. Measurement sensitivity can be improved.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモンセンサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, the outer periphery of the metal film 50 is a surface plasmon sensor in which a light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b. A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the surface, and the sensitivity to the humidity in the atmosphere can be improved.
　なお、上記の複数の積層されたポリイオン膜から膜６０を構成する場合、例えば、イオンカップリング剤で処理して金属膜５０の表面にプロトン化したアミノ基（－ＮＨ３＋）を導入し、その後、電離したカルボン酸基（－ＣＯＯ－）を有するポリマーの溶液と、プロトン化したアミノ基（－ＮＨ３＋）を有するポリマーの溶液とに交互に浸漬することにより、製造することができる。各ポリイオン層の膜厚などは、ポリマー溶液の濃度や浸漬時間などによって調整できる。 In the case of forming the film 60 from the plurality of stacked polyion films, for example, a protonated amino group (—NH 3+) is introduced into the surface of the metal film 50 by treatment with an ion coupling agent, and then It can be produced by alternately immersing in a solution of a polymer having an ionized carboxylic acid group (—COO—) and a solution of a polymer having a protonated amino group (—NH 3+). The film thickness of each polyion layer can be adjusted by the concentration of the polymer solution, the immersion time, and the like.
　あるいは、例えば、イオンカップリング剤で処理して金属膜５０の表面に電離したカルボン酸基（－ＣＯＯ－）を導入し、その後、プロトン化したアミノ基（－ＮＨ３＋）を有するポリマーの溶液と、電離したカルボン酸基（－ＣＯＯ－）を有するポリマーの溶液とに交互に浸漬するようにしてもよい。また、ゼラチン膜は、例えば、金属膜５０にゼラチン水溶液を塗布して乾燥させて形成することができる。
［第２実施形態］
　センサ部ＳＰとしては、第１実施形態に記載の構成以外の構成を採用することも可能である。本発明の第２実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。本実施形態の湿度測定装置に用いられる光ファイバ型表面プラズモン湿度センサのセンサ部ＳＰ近傍の長手方向の断面図を示す図３（ａ）及び図３（ｂ）に示す。 Alternatively, for example, a carboxylic acid group (—COO—) ionized on the surface of the metal film 50 by treatment with an ion coupling agent is introduced, and then a polymer solution having a protonated amino group (—NH 3+); It may be alternately immersed in a polymer solution having ionized carboxylic acid groups (—COO—). The gelatin film can be formed, for example, by applying a gelatin aqueous solution to the metal film 50 and drying it.
[Second Embodiment]
As sensor part SP, it is also possible to employ | adopt structures other than the structure as described in 1st Embodiment. A humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a second embodiment of the present invention will be described. FIGS. 3A and 3B are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion SP of the optical fiber type surface plasmon humidity sensor used in the humidity measuring apparatus of the present embodiment.
　図３（ａ）では、センサ部ＳＰを構成する光透過部材であるヘテロコア部３のコア３１の径ｂｌが、光ファイバ２０ａ，２０ｂのコア２１の径ａｌよりも大きな構成となっている。上記のヘテロコア部３の外周表面に、金属膜５０が形成されている。 In FIG. 3A, the diameter bl of the core 31 of the hetero-core part 3 which is a light transmitting member constituting the sensor part SP is larger than the diameter al of the core 21 of the optical fibers 20a and 20b. A metal film 50 is formed on the outer peripheral surface of the hetero core portion 3.
　図３（ｂ）では、センサ部ＳＰとして、光ファイバ２０ａ，２０ｂのコア２１の屈折率あるいはクラッド２２の屈折率と同等の屈折率を持つ材料からなる、ヘテロコア部ではない光透過部材３０が光ファイバ２０ａ，２０ｂの中途部に接合されてなる構成となっている。上記の光透過部材３０の外周表面に金属膜５０が形成されており、その外周表面に、ポリイオン膜やゼラチン膜などの雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられている。 In FIG. 3B, the light transmitting member 30 that is not a hetero-core part and made of a material having a refractive index equivalent to the refractive index of the core 21 of the optical fibers 20a and 20b or the refractive index of the cladding 22 is used as the sensor part SP. The fiber 20a, 20b is joined to the middle part. A metal film 50 is formed on the outer peripheral surface of the light transmitting member 30, and a film 60 whose refractive index changes according to the humidity in the atmosphere, such as a polyion film or a gelatin film, is provided on the outer peripheral surface. .
　本実施形態の上記以外の構成は、実質的に第１実施形態と同様である。 The configuration of the present embodiment other than the above is substantially the same as that of the first embodiment.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモン湿度センサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。
［第３実施形態］
　本発明の第３実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図４を参照して、この湿度測定装置には、光ファイバ２０ａ，２０ｂの中途部にセンサ部ＳＰが設けられている。光ファイバ２０ａの途中には光カプラ１６が設けられ、光カプラ１６において光ファイバ２０ｃを分岐する構成であり、光ファイバ２０ｂの端部には銀を蒸着して形成された反射部（鏡）１５が設けられている。光ファイバ２０ａ端部が光入射端、光ファイバ２０ｃ端部が光出射端となる。光ファイバ２０ａの光入射端に光源１１が設けられ、光ファイバ２０ｃの光出射端にスペクトラムアナライザ１２が設けられている。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
[Third Embodiment]
A humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a third embodiment of the present invention will be described. Referring to FIG. 4, the humidity measuring device is provided with a sensor part SP in the middle of the optical fibers 20a and 20b. An optical coupler 16 is provided in the middle of the optical fiber 20a, and the optical fiber 20c is branched in the optical coupler 16, and a reflecting portion (mirror) 15 formed by vapor-depositing silver at the end of the optical fiber 20b. Is provided. The end of the optical fiber 20a is the light incident end, and the end of the optical fiber 20c is the light emitting end. A light source 11 is provided at the light incident end of the optical fiber 20a, and a spectrum analyzer 12 is provided at the light emitting end of the optical fiber 20c.
　上記以外の構成は、実質的に第１実施形態と同様である。また、センサ部ＳＰとして第２実施形態に示す構成を用いることも可能である。 Other configurations are substantially the same as those in the first embodiment. Moreover, it is also possible to use the structure shown in 2nd Embodiment as sensor part SP.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモン湿度センサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core part 3 is provided in the middle part of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
　特に、反射部１５で反射した光は、再びセンサ部ＳＰを通過するため、一方向に通過させただけの光と比較してより多くの相互干渉の情報を含んだ光が測定されることとなる。
［第４実施形態］
　本発明の第４実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図５を参照して、この湿度測定装置には、光ファイバ２０ａ，２０ｂの中途部にセンサ部ＳＰが設けられている。　光ファイバ２０ａの光入射端に、レーザダイオードまたは発光ダイオードなどのセンサ光を出射する光源１１ａが設けられ、光ファイバ２０ｂの光出射端に光出射端から出射されるセンサ光を検出する光マルチメータ１２ａが設けられている。レーザダイオードまたは発光ダイオードは単一波長の光を発光するので、受光部には分光しないで光強度をモニタできる光マルチメータを用いることができる。例えば、レーザダイオードまたは発光ダイオードなどの発光波長は、表面プラズモン共鳴が生じる波長を選択し、光マルチメータでモニタする光強度の減衰から、湿度に応じて屈折率が変化する膜６０の屈折率変化を感知することができる。 In particular, since the light reflected by the reflecting portion 15 passes through the sensor portion SP again, light containing more information on mutual interference is measured as compared with light that has just passed in one direction. Become.
[Fourth Embodiment]
A humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a fourth embodiment of the present invention will be described. Referring to FIG. 5, this humidity measuring device is provided with a sensor part SP in the middle of optical fibers 20a and 20b. A light source 11a for emitting sensor light such as a laser diode or a light emitting diode is provided at the light incident end of the optical fiber 20a, and an optical multimeter for detecting sensor light emitted from the light emitting end at the light emitting end of the optical fiber 20b. 12a is provided. Since the laser diode or the light emitting diode emits light of a single wavelength, an optical multimeter that can monitor the light intensity without being split can be used for the light receiving portion. For example, the emission wavelength of a laser diode or a light emitting diode is selected as the wavelength at which surface plasmon resonance occurs, and the refractive index change of the film 60 whose refractive index changes according to humidity from the attenuation of light intensity monitored by an optical multimeter. Can be detected.
　上記以外の構成は、実質的に第１実施形態と同様である。また、センサ部ＳＰとして第２実施形態に示す構成を用いることも可能である。 Other configurations are substantially the same as those in the first embodiment. Moreover, it is also possible to use the structure shown in 2nd Embodiment as sensor part SP.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモン湿度センサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。
［第５実施形態］
　本発明の第５実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図６を参照して、この湿度測定装置には、光ファイバ２０ａ，２０ｂの中途部にセンサ部ＳＰが設けられている。光ファイバ２０ａの途中には光カプラ１６が設けられ、光カプラ１６において光ファイバ２０ｃを分岐する構成であり、光ファイバ２０ｂの端部には銀を蒸着して形成された反射部（鏡）１５が設けられている。光ファイバ２０ａ端部が光入射端、光ファイバ２０ｃ端部が光出射端となる。光ファイバ２０ａの光入射端に、レーザダイオードまたは発光ダイオードなどのセンサ光を出射する光源１１ａが設けられ、光ファイバ２０ｃの光出射端に光出射端から出射されるセンサ光を検出する光マルチメータ１２ａが設けられている。レーザダイオードまたは発光ダイオードは単一波長の光を発光するので、受光部には分光しないで光強度をモニタできる光マルチメータを用いることができる。例えば、レーザダイオードまたは発光ダイオードなどの発光波長は、表面プラズモン共鳴が生じる波長を選択し、光マルチメータでモニタする光強度の減衰から、湿度に応じて屈折率が変化する膜６０の屈折率変化を感知することができる。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
[Fifth Embodiment]
A humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a fifth embodiment of the present invention will be described. Referring to FIG. 6, this humidity measuring device is provided with a sensor part SP in the middle of the optical fibers 20a and 20b. An optical coupler 16 is provided in the middle of the optical fiber 20a, and the optical fiber 20c is branched at the optical coupler 16. A reflecting portion (mirror) 15 formed by vapor-depositing silver at the end of the optical fiber 20b. Is provided. The end of the optical fiber 20a is the light incident end, and the end of the optical fiber 20c is the light exit end. A light source 11a that emits sensor light such as a laser diode or a light emitting diode is provided at the light incident end of the optical fiber 20a, and an optical multimeter that detects sensor light emitted from the light emitting end at the light emitting end of the optical fiber 20c. 12a is provided. Since the laser diode or the light emitting diode emits light of a single wavelength, an optical multimeter that can monitor the light intensity without being split can be used for the light receiving portion. For example, the emission wavelength of a laser diode or a light emitting diode is selected as the wavelength at which surface plasmon resonance occurs, and the refractive index change of the film 60 whose refractive index changes according to humidity from the attenuation of light intensity monitored by an optical multimeter. Can be detected.
　上記以外の構成は、実質的に第１実施形態と同様である。また、センサ部ＳＰとして第２実施形態に示す構成を用いることも可能である。 Other configurations are substantially the same as those in the first embodiment. Moreover, it is also possible to use the structure shown in 2nd Embodiment as sensor part SP.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモン湿度センサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core part 3 is provided in the middle part of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
　特に、反射部で反射した光は、再びセンサ部ＳＰを通過するため、一方向に通過させただけの光と比較してより多くの相互干渉の情報を含んだ光が測定されることとなる。
［第６実施形態］
　本発明の第６実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図７を参照して、この湿度測定装置には、光ファイバ２０ａ，２０ｂの中途部にセンサ部ＳＰが設けられている。光ファイバ２０ａには、ＯＴＤＲ（Optical time-domain reflectometer）装置７０が接続されている。ＯＴＤＲ装置７０から入射されたセンサ光の後方へのレイリー散乱光をＯＴＤＲ装置７０自身が検出する。 In particular, since the light reflected by the reflecting portion passes through the sensor portion SP again, light containing more information on mutual interference is measured as compared with light that has only been passed in one direction. .
[Sixth Embodiment]
A humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a sixth embodiment of the present invention will be described. Referring to FIG. 7, the humidity measuring device is provided with a sensor part SP in the middle of the optical fibers 20a and 20b. An OTDR (Optical time-domain reflectometer) device 70 is connected to the optical fiber 20a. The OTDR device 70 itself detects Rayleigh scattered light behind the sensor light incident from the OTDR device 70.
　上記以外の構成は、実質的に第１実施形態と同様である。また、センサ部ＳＰとして第２実施形態に示す構成を用いることも可能である。 Other configurations are substantially the same as those in the first embodiment. Moreover, it is also possible to use the structure shown in 2nd Embodiment as sensor part SP.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモン湿度センサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。
［第７実施形態］
　本発明の第７実施形態に係る光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図８を参照して、この湿度測定装置には、光ファイバ２０ａ，２０ｂの中途部にセンサ部ＳＰ１が設けられ、光ファイバ２０ｂ，２０ｃの中途部にセンサ部ＳＰ２が設けられ、さらに光ファイバ２０ｃ，２０ｄの中途部にセンサ部ＳＰ３が設けられている。即ち、複数個のセンサ部ＳＰ１乃至ＳＰ３が１本の光ファイバ上に直列に接続された構成となっている。光ファイバ２０ａには、ＯＴＤＲ装置７０が接続されている。ＯＴＤＲ装置７０からセンサ光が入射されると、複数個のセンサ部ＳＰ１乃至ＳＰ３のそれぞれにおいて後方へのレイリー散乱光が発生し、これをＯＴＤＲ装置７０が検出する。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, in the surface plasmon humidity sensor in which the light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
[Seventh Embodiment]
A humidity measuring apparatus using an optical fiber type surface plasmon humidity sensor according to a seventh embodiment of the present invention will be described. Referring to FIG 8, this humidity measurement device, an optical fiber 20a, the sensor unit SP 1 is provided in an intermediate portion of the 20b, the optical fiber 20b, the sensor unit SP 2 in the middle portion of the 20c provided, further optical fibers 20c, the sensor unit SP 3 in the middle of 20d are provided. That is, a plurality of sensor units SP 1 to SP 3 are connected in series on one optical fiber. An OTDR device 70 is connected to the optical fiber 20a. When the sensor light from the OTDR apparatus 70 is incident, the Rayleigh scattered light backward is generated in each of the plurality of sensor portions SP 1 to SP 3, which OTDR apparatus 70 is detected.
　上記以外の構成は、実質的に第１実施形態と同様である。また、センサ部ＳＰとして第２実施形態に示す構成を用いることも可能である。 Other configurations are substantially the same as those in the first embodiment. Moreover, it is also possible to use the structure shown in 2nd Embodiment as sensor part SP.
　本実施形態の光ファイバ型表面プラズモン湿度センサを用いた湿度測定装置では、光ファイバ２０ａ乃至２０ｄの中途部にヘテロコア部３などの光透過部材が設けられた表面プラズモン湿度センサにおいて、金属膜５０の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 In the humidity measuring apparatus using the optical fiber type surface plasmon humidity sensor of the present embodiment, in the surface plasmon humidity sensor in which a light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a to 20d, the metal film 50 A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the outer peripheral surface, and the sensitivity to the humidity in the atmosphere can be improved.
　特に、複数個のセンサ部ＳＰ１乃至ＳＰ３で同時に湿度を測定することが可能であり、より精密な計測が可能である。
［第８実施形態］
　本発明の第８実施形態に係るクレッチマン型表面プラズモン湿度センサを用いた湿度測定装置について説明する。図９を参照して、この湿度測定装置には、ガラス基板などからなる光透過性基板８０の表面に、この表面における光透過性基板中の光の反射により表面プラズモンを発生する金属膜５０が設けられ、金属膜５０の上層に、雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられている。ここで、金属膜５０及び雰囲気中の湿度に応じて屈折率が変化する膜６０は第１実施形態に記載のものと同様である。 In particular, it is possible to measure the humidity at the same time with a plurality of sensor units SP 1 to SP 3 , and more precise measurement is possible.
[Eighth Embodiment]
A humidity measurement apparatus using a Kretschmann type surface plasmon humidity sensor according to an eighth embodiment of the present invention will be described. Referring to FIG. 9, in this humidity measuring apparatus, a metal film 50 that generates surface plasmons by reflection of light in the light-transmitting substrate on the surface is formed on the surface of a light-transmitting substrate 80 made of a glass substrate or the like. A film 60 whose refractive index changes according to the humidity in the atmosphere is provided on the upper layer of the metal film 50. Here, the metal film 50 and the film 60 whose refractive index changes according to the humidity in the atmosphere are the same as those described in the first embodiment.
　光透過性基板８０の側から、光透過性基板８０と金属膜５０の界面に光Ｌｉｎを入射させると、金属膜５０に対する光の入射角と金属膜５０に接触している、雰囲気中の湿度に応じて屈折率が変化する膜６０の屈折率とが所定の関係を満たすときに、表面プラズモン共鳴が発生して反射光の強度が低下する。従って、反射光Ｌｏｕｔを観測することで、雰囲気中の湿度に応じて屈折率が変化する膜６０の屈折率を測定することができる。なお、第１実施形態や第３乃至５実施形態と同様に、光源と受光部を組み合わせて湿度測定装置を構成することができる。 When light Lin is incident on the interface between the light transmissive substrate 80 and the metal film 50 from the light transmissive substrate 80 side, the incident angle of light with respect to the metal film 50 and the humidity in the atmosphere in contact with the metal film 50 When the refractive index of the film 60 whose refractive index changes according to the above relationship satisfies a predetermined relationship, surface plasmon resonance occurs and the intensity of reflected light decreases. Therefore, by observing the reflected light Lout, the refractive index of the film 60 whose refractive index changes according to the humidity in the atmosphere can be measured. As in the first embodiment and the third to fifth embodiments, a humidity measuring device can be configured by combining a light source and a light receiving unit.
　本実施形態のクレッチマン型表面プラズモン湿度センサを用いた湿度測定装置では、光透過性基板８０の表面に、金属膜５０が設けられたクレッチマン型の表面プラズモン湿度センサにおいて、金属膜５０の上層に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。
［第９実施形態］
　本発明の第９実施形態に係る光ファイバ型湿度センサを用いた湿度測定装置について説明する。本実施形態に係る光ファイバ型湿度センサを用いた湿度測定装置の構成は、第１実施形態と同様である。本実施形態の湿度測定装置に用いられる光ファイバ型湿度センサのセンサ部ＳＰ近傍の斜視図を図１０（ａ）に示し、センサ部ＳＰ近傍の長手方向の断面図を示す図１０（ｂ）に示す。 In the humidity measuring apparatus using the Kretschmann type surface plasmon humidity sensor of the present embodiment, in the Kretschmann type surface plasmon humidity sensor in which the metal film 50 is provided on the surface of the light-transmitting substrate 80, the atmosphere is formed above the metal film 50. A film 60 whose refractive index changes according to the humidity inside is provided, and the sensitivity to humidity in the atmosphere can be improved.
[Ninth Embodiment]
A humidity measurement apparatus using the optical fiber type humidity sensor according to the ninth embodiment of the present invention will be described. The configuration of the humidity measuring apparatus using the optical fiber type humidity sensor according to this embodiment is the same as that of the first embodiment. FIG. 10A shows a perspective view of the vicinity of the sensor part SP of the optical fiber type humidity sensor used in the humidity measuring apparatus of the present embodiment, and FIG. 10B shows a longitudinal sectional view of the vicinity of the sensor part SP. Show.
　本実施形態の湿度測定装置に用いられる光ファイバ型表面プラズモン湿度センサは、例えば、コア径５０μｍのマルチモードファイバである一方の光ファイバ２０ａと他方の光ファイバ２０ｂの間に、センサ部ＳＰが設けられた構成である。センサ部ＳＰは、例えば、伝送する光の一部を外界と相互作用させる光透過部材であるヘテロコア部３と、ヘテロコア部３の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜６０とを有する。実質的に、図２（ａ）及び（ｂ）において金属膜５０が省略された構成である。 The optical fiber type surface plasmon humidity sensor used in the humidity measuring apparatus of the present embodiment is provided with a sensor unit SP between one optical fiber 20a and the other optical fiber 20b, which are multimode fibers having a core diameter of 50 μm, for example. It is the structure which was made. For example, the sensor unit SP is provided on the outer surface of the hetero core unit 3 that is a light transmitting member that causes a part of transmitted light to interact with the outside world, and the refractive index changes according to the humidity in the atmosphere. And a film 60 to be used. The metal film 50 is substantially omitted in FIGS. 2A and 2B.
　光ファイバ２０ａ，２０ｂは、コア２１と、その外周部に設けられたクラッド２２とを有し、ヘテロコア部３は、光ファイバ２０ａ，２０ｂのコア径と異なるコア径を有するコア３１と、その外周部に設けられたクラッド３２とを有する。また、ヘテロコア部３におけるコア３１の径ｂｌは、光ファイバ２０ａ，２０ｂのコア２１の径ａｌより小さく、例えばａｌ＝５０μｍ、ｂｌ＝３μｍである。また、ヘテロコア部３の長さｃｌは、１ｍｍ乃至数ｃｍである。センサ部ＳＰを構成するヘテロコア部３と光ファイバ２０ａ，２０ｂは、例えば、長手方向に直交する界面４でコア同士が接合するようにほぼ同軸に、例えば汎用化されている放電による融着などにより、接合されている。 The optical fibers 20a and 20b have a core 21 and a cladding 22 provided on the outer periphery thereof, and the hetero-core portion 3 has a core 31 having a core diameter different from that of the optical fibers 20a and 20b, and an outer periphery thereof. And a clad 32 provided on the portion. Moreover, the diameter bl of the core 31 in the hetero core part 3 is smaller than the diameter al of the core 21 of the optical fibers 20a and 20b, for example, al = 50 μm and bl = 3 μm. Moreover, the length cl of the heterocore part 3 is 1 mm to several cm. The hetero-core part 3 and the optical fibers 20a and 20b constituting the sensor part SP are, for example, substantially coaxial so that the cores are joined at the interface 4 orthogonal to the longitudinal direction, for example, by fusion using a generalized discharge. Are joined.
　光ファイバ２０ａ，２０ｂ及びヘテロコア部３としては、例えば、シングルモード光ファイバ及びマルチモード光ファイバのいずれをも使用可能であり、これらを組み合わせて使用してもよい。 As the optical fibers 20a and 20b and the hetero core section 3, for example, any of a single mode optical fiber and a multimode optical fiber can be used, and these may be used in combination.
　本実施形態に係るセンサ部ＳＰのヘテロコア部３は、表面側を被覆するように、雰囲気中の湿度に応じて屈折率が変化する膜６０が形成されている。雰囲気中の湿度に応じて屈折率が変化する膜６０は、第１実施形態と同様であり、例えば、複数の積層されたポリイオン膜あるいはゼラチン膜などである。 The film 60 whose refractive index changes according to the humidity in the atmosphere is formed on the hetero core portion 3 of the sensor portion SP according to the present embodiment so as to cover the surface side. The film 60 whose refractive index changes according to the humidity in the atmosphere is the same as in the first embodiment, and is, for example, a plurality of stacked polyion films or gelatin films.
　上記の光ファイバ２０ａ，２０ｂの中途部にヘテロコア型のセンサ部ＳＰが接合されてなる構成において、ヘテロコア部３におけるコア３１の径ｂｌと光ファイバ２０ａ，２０ｂのコア２１の径ａｌとが界面４で異なっている。このコア径の差に起因して、図２（ａ）に示すように、光の一部のヘテロコア部３のクラッド３２へのリークＷが発生する。 In the configuration in which the hetero core type sensor part SP is joined to the middle part of the optical fibers 20a and 20b, the diameter bl of the core 31 in the hetero core part 3 and the diameter al of the core 21 of the optical fibers 20a and 20b are the interface 4. Is different. Due to the difference in the core diameter, as shown in FIG. 2A, a leak W to the clad 32 of the hetero-core portion 3 that is a part of the light occurs.
　ここで、雰囲気中の湿度に応じて屈折率が変化する膜６０の屈折率に応じて、クラッド３２へリークした光の外部への漏れ、即ち、損失が変化する。例えば、雰囲気中の湿度が低くなると、屈折率が変化する膜６０の屈折率が大きくなり、損失は大きくなる。逆に、湿度が高くなると、屈折率が変化する膜６０の屈折率が小さくなり、損失は小さくなる。 Here, according to the refractive index of the film 60 whose refractive index changes according to the humidity in the atmosphere, the leakage of light leaked to the cladding 32, that is, the loss changes. For example, when the humidity in the atmosphere decreases, the refractive index of the film 60 whose refractive index changes increases, and the loss increases. Conversely, when the humidity increases, the refractive index of the film 60 whose refractive index changes decreases, and the loss decreases.
　従って、伝送損失と雰囲気湿度を予め関係付けておくことで、伝送損失から雰囲気中の湿度の値を得ることができる。 Therefore, the humidity value in the atmosphere can be obtained from the transmission loss by relating the transmission loss and the atmospheric humidity in advance.
　本実施形態の光ファイバ型湿度センサを用いた湿度測定装置では、光ファイバ２０ａ，２０ｂの中途部にヘテロコア部３などの光透過部材が設けられた光ファイバ型センサにおいて、光透過部材の外周表面に雰囲気中の湿度に応じて屈折率が変化する膜６０が設けられており、雰囲気中の湿度に対する感度を向上させることができる。 In the humidity measuring apparatus using the optical fiber type humidity sensor of the present embodiment, the outer peripheral surface of the light transmitting member is an optical fiber type sensor in which a light transmitting member such as the hetero core portion 3 is provided in the middle of the optical fibers 20a and 20b. Further, a film 60 whose refractive index changes according to the humidity in the atmosphere is provided, and the sensitivity to the humidity in the atmosphere can be improved.
　センサ部としては、上記のほか、第２実施形態に示す構成において金属膜５０が形成されておらず、光透過部材の外周表面に直接湿度に応じて屈折率が変化する膜が形成された構成とすることもできる。また、湿度測定装置としては、第３乃至第７実施形態の構成に適用することも可能である。 In addition to the above, as the sensor unit, the metal film 50 is not formed in the configuration shown in the second embodiment, and a film in which the refractive index changes directly according to humidity is formed on the outer peripheral surface of the light transmitting member. It can also be. In addition, the humidity measuring device can be applied to the configurations of the third to seventh embodiments.
　本発明は上記の説明に限定されない。例えば、用いる光源や受光部などは、上述のものに限らず、種々のものを使用できる。光ファイバはマルチモードファイバでもシングルモードファイバでも使用できる。その他、本発明の要旨を逸脱しない範囲で、種々の変更が可能である。 The present invention is not limited to the above description. For example, the light source and the light receiving unit used are not limited to those described above, and various types can be used. The optical fiber can be a multimode fiber or a single mode fiber. In addition, various modifications can be made without departing from the scope of the present invention.
　本発明の光ファイバ型表面プラズモン湿度センサ、表面プラズモン湿度センサ、及び光ファイバ型湿度センサは、湿度測定装置のヘッドとして適用できる。本発明の湿度測定装置は簡単に湿度を測定する装置として適用できる。 The optical fiber type surface plasmon humidity sensor, surface plasmon humidity sensor, and optical fiber type humidity sensor of the present invention can be applied as a head of a humidity measuring device. The humidity measuring device of the present invention can be applied as a device for measuring humidity easily.

Claims (30)

  1. 光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、前記外周表面における前記光透過部材中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜とを有する光ファイバ型表面プラズモン湿度センサ。 An optical fiber, a light transmission member provided in the middle part of the optical fiber, allowing a part of transmitted light to interact with the outside world, and provided on an outer peripheral surface of the light transmission member, and the light transmission member on the outer peripheral surface An optical fiber type surface plasmon humidity sensor comprising: a metal film that generates surface plasmons by reflection of light therein; and a film that is provided on an outer peripheral surface of the metal film and has a refractive index that changes according to humidity in the atmosphere.
  2. 前記屈折率が変化する膜は、複数の積層されたポリイオン膜である請求項１に記載の光ファイバ型表面プラズモン湿度センサ。 The optical fiber type surface plasmon humidity sensor according to claim 1, wherein the film whose refractive index changes is a plurality of stacked polyion films.
  3. 前記屈折率が変化する膜は、ゼラチン膜である請求項１に記載の光ファイバ型表面プラズモン湿度センサ。 The optical fiber type surface plasmon humidity sensor according to claim 1, wherein the film whose refractive index changes is a gelatin film.
  4. 前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である請求項１に記載の光ファイバ型表面プラズモン湿度センサ。 2. The optical fiber type surface plasmon humidity sensor according to claim 1, wherein the light transmitting member is a hetero core portion having a core diameter different from a core diameter of the optical fiber.
  5. 前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である請求項１に記載の光ファイバ型表面プラズモン湿度センサ。 2. The optical fiber surface plasmon humidity sensor according to claim 1, wherein the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  6. 前記光ファイバがマルチモード光ファイバである請求項１に記載の光ファイバ型表面プラズモン湿度センサ。 The optical fiber type surface plasmon humidity sensor according to claim 1, wherein the optical fiber is a multimode optical fiber.
  7. 前記光ファイバの一方の端部が２本に分岐して光の入射端及び出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている請求項１に記載の光ファイバ型表面プラズモン湿度センサ。 One end portion of the optical fiber is branched into two, and an incident end and an output end of light are provided, and light transmitted through the optical fiber is reflected to the other end portion of the optical fiber to be reflected on the optical fiber. The optical fiber type surface plasmon humidity sensor according to claim 1, further comprising a reflection portion to be returned.
  8. 光透過性基板と、前記光透過性基板の表面に設けられ、前記表面における前記光透過性基板中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の上層に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜とを有する表面プラズモン湿度センサ。 A light transmissive substrate, a metal film provided on a surface of the light transmissive substrate, and generating a surface plasmon by reflection of light in the light transmissive substrate on the surface; an atmosphere provided on an upper layer of the metal film; A surface plasmon humidity sensor having a film whose refractive index changes according to the humidity inside.
  9. 光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜とを有する光ファイバ型湿度センサ。 An optical fiber, a light transmitting member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, provided on the outer peripheral surface of the light transmitting member, and refracted according to the humidity in the atmosphere. An optical fiber type humidity sensor having a film with a variable rate.
  10. 前記屈折率が変化する膜は、複数の積層されたポリイオン膜である請求項９に記載の光ファイバ型湿度センサ。 The optical fiber humidity sensor according to claim 9, wherein the film whose refractive index changes is a plurality of stacked polyion films.
  11. 前記屈折率が変化する膜は、ゼラチン膜である請求項９に記載の光ファイバ型湿度センサ。 The optical fiber type humidity sensor according to claim 9, wherein the film whose refractive index changes is a gelatin film.
  12. 前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である請求項９に記載の光ファイバ型湿度センサ。 The optical fiber humidity sensor according to claim 9, wherein the light transmission member is a hetero core portion having a core diameter different from a core diameter of the optical fiber.
  13. 前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である請求項９に記載の光ファイバ型湿度センサ。 The optical fiber humidity sensor according to claim 9, wherein the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  14. 前記光ファイバがマルチモード光ファイバである請求項９に記載の光ファイバ型湿度センサ。 The optical fiber humidity sensor according to claim 9, wherein the optical fiber is a multimode optical fiber.
  15. 前記光ファイバの一方の端部が２本に分岐して光の入射端及び出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている請求項９に記載の光ファイバ型湿度センサ。 One end portion of the optical fiber is branched into two, and an incident end and an output end of light are provided, and light transmitted through the optical fiber is reflected to the other end portion of the optical fiber to be reflected on the optical fiber. The optical fiber type humidity sensor according to claim 9, further comprising a reflecting portion to be returned.
  16. 光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、前記外周表面における前記光透過部材中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜と、前記光ファイバの入射端に対してセンサ光を出射する光源と、前記光透過部材を介して前記光ファイバの出射端から出射される前記センサ光を検出する受光部とを有する湿度測定装置。 An optical fiber, a light transmission member provided in the middle part of the optical fiber, allowing a part of transmitted light to interact with the outside world, and provided on an outer peripheral surface of the light transmission member, and the light transmission member on the outer peripheral surface A metal film that generates surface plasmons by reflection of light inside, a film that is provided on the outer peripheral surface of the metal film, and whose refractive index changes according to the humidity in the atmosphere, and a sensor for the incident end of the optical fiber A humidity measuring apparatus comprising: a light source that emits light; and a light receiving unit that detects the sensor light emitted from an emission end of the optical fiber via the light transmitting member.
  17. 前記屈折率が変化する膜は、複数の積層されたポリイオン膜である請求項１６に記載の湿度測定装置。 The humidity measuring apparatus according to claim 16, wherein the film whose refractive index changes is a plurality of stacked polyion films.
  18. 前記屈折率が変化する膜は、ゼラチン膜である請求項１６に記載の湿度測定装置。 The humidity measuring apparatus according to claim 16, wherein the film whose refractive index changes is a gelatin film.
  19. 前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である請求項１６に記載の湿度測定装置。 The humidity measuring device according to claim 16, wherein the light transmitting member is a hetero core portion having a core diameter different from a core diameter of the optical fiber.
  20. 前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である請求項１６に記載の湿度測定装置。 The humidity measuring device according to claim 16, wherein the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  21. 前記光ファイバがマルチモード光ファイバである請求項１６に記載の湿度測定装置。 The humidity measuring apparatus according to claim 16, wherein the optical fiber is a multimode optical fiber.
  22. 前記光ファイバの一方の端部が２本に分岐して前記入射端及び前記出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている請求項１６に記載の湿度測定装置。 One end of the optical fiber branches into two, the incident end and the exit end are provided, and the light transmitted through the optical fiber is reflected on the other end of the optical fiber to the optical fiber. The humidity measuring device according to claim 16, further comprising a reflecting portion to be returned.
  23. 光透過性基板と、前記光透過性基板の表面に設けられ、前記表面における前記光透過性基板中の光の反射により表面プラズモンを発生する金属膜と、前記金属膜の上層に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜と、前記光透過性基板の内側から前記金属膜と前記光透過性基板の界面に向けてセンサ光を出射する光源と、前記金属膜と前記光透過性基板の界面から反射した前記センサ光を検出する受光部とを有する湿度測定装置。 A light transmissive substrate, a metal film provided on a surface of the light transmissive substrate, and generating a surface plasmon by reflection of light in the light transmissive substrate on the surface; an atmosphere provided on an upper layer of the metal film; A film whose refractive index changes according to the humidity therein, a light source that emits sensor light from the inside of the light-transmitting substrate toward the interface between the metal film and the light-transmitting substrate, the metal film, and the light A humidity measuring device comprising: a light receiving unit that detects the sensor light reflected from the interface of the transparent substrate.
  24. 光ファイバと、前記光ファイバの中途部に設けられ、伝送する光の一部を外界と相互作用させる光透過部材と、前記光透過部材の外周表面に設けられ、雰囲気中の湿度に応じて屈折率が変化する膜と、前記光ファイバの入射端に対してセンサ光を出射する光源と、前記光透過部材を介して前記光ファイバの出射端から出射される前記センサ光を検出する受光部とを有する湿度測定装置。 An optical fiber, a light transmitting member provided in the middle of the optical fiber, and a part of the transmitted light interacts with the outside world, provided on the outer peripheral surface of the light transmitting member, and refracted according to the humidity in the atmosphere. A film whose rate changes, a light source that emits sensor light to the incident end of the optical fiber, and a light receiving unit that detects the sensor light emitted from the exit end of the optical fiber via the light transmitting member A humidity measuring device.
  25. 前記屈折率が変化する膜は、複数の積層されたポリイオン膜である請求項２４に記載の湿度測定装置。 The humidity measuring apparatus according to claim 24, wherein the film whose refractive index changes is a plurality of stacked polyion films.
  26. 前記屈折率が変化する膜は、ゼラチン膜である請求項２４に記載の湿度測定装置。 The humidity measuring apparatus according to claim 24, wherein the film whose refractive index changes is a gelatin film.
  27. 前記光透過部材は、前記光ファイバのコア径と異なるコア径を有するヘテロコア部である請求項２４に記載の湿度測定装置。 The humidity measuring device according to claim 24, wherein the light transmission member is a hetero core portion having a core diameter different from a core diameter of the optical fiber.
  28. 前記光透過部材は、前記光ファイバのコアの屈折率あるいはクラッドの屈折率と同等の屈折率を持つ光透過部材である請求項２４に記載の湿度測定装置。 The humidity measuring device according to claim 24, wherein the light transmitting member is a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad.
  29. 前記光ファイバがマルチモード光ファイバである請求項２４に記載の湿度測定装置。 The humidity measuring apparatus according to claim 24, wherein the optical fiber is a multimode optical fiber.
  30. 前記光ファイバの一方の端部が２本に分岐して前記入射端及び前記出射端が設けられ、前記光ファイバの他方の端部に前記光ファイバを伝送する光を反射して前記光ファイバに戻す反射部が設けられている請求項２４に記載の湿度測定装置。 One end of the optical fiber branches into two, the incident end and the exit end are provided, and the light transmitted through the optical fiber is reflected on the other end of the optical fiber to the optical fiber. The humidity measuring device according to claim 24, further comprising a reflecting portion to be returned.
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