JP4239799B2 - Spectroscopic specific component sensor - Google Patents

Description

  The present invention relates to a spectroscopic specific component sensor used for identification or quantitative evaluation of chemical substances, for example.

  Conventionally, the spectroscopic measurement technique used for this type of spectroscopic specific component sensor is often used as a method for identifying or quantitatively evaluating chemical substances, and inspected substances using wavelength light in the ultraviolet, visible, and infrared regions. The wavelength characteristics of transmitted light or reflected light when irradiated on the substrate are evaluated. This is one of the analytical means using the wavelength dependence of the absorption of incident light accompanying the chemical structure of the substance.

  In addition to physics and chemistry research applications, industrial applications have been made as tools for process management and quality control in the food industry, chemical industry, agriculture and fishery fields, etc., or for environmental measurement and disaster prevention fields such as gas sensors, humidity sensors, fire sensors Is possible.

  Among the spectroscopic measurement techniques, an analysis technique using infrared light is used for chemical analysis, agricultural food analysis, pharmaceutical use, and the like. For example, in Non-Patent Document 1, a spectrophotometer is used for analysis in a wide wavelength range, and a bandpass filter or an inclined film thickness bandpass filter using an optical multilayer film is used when only a short wavelength range or a specific wavelength component is used. It is described that it may be done. However, since a spectrophotometer that covers a wide wavelength range is large and very expensive, it is effective in the above applications to realize a low-cost, small and compact spectroscopic sensor.

  Conventionally, various infrared gas sensors using gas-specific wavelength absorption characteristics have been proposed. These measure the type and concentration of gas from the amount of light detected by the light receiver. For example, Patent Document 1 discloses a static system using a plurality of spectroscopic-light receivers, and Patent Document 2 discloses a dynamic system including a single light receiving system in which a spectroscopic unit is variably measured. In the static method, a plurality of optical filters and light receiving elements are set and arranged in an element case for the infrared region. In contrast, the dynamic method is composed of a wavelength-variable spectroscopic unit using a Fabry-Perot etalon and a single light receiving element, and is excellent in that it can save power.

Patent Document 3 discloses the following infrared gas analyzer. In the moving mechanism that fixes the multilayer filter and periodically moves it between a certain angle, when the excitation power source of the solenoid is turned on and off at a constant cycle by the control unit, the moving axis of the solenoid reciprocates in the horizontal direction and moves to the lever (B). The mounted and fixed multilayer filter reciprocates within the range of the angle θ. This angle θ is determined by the wavelength light necessary for transmission within a range of approximately 0 to 45 °.
Japanese Patent Laid-Open No. 3-205521 (pages 4 to 6 and FIG. 2) Japanese Laid-Open Patent Publication No. 9-79980 (pages 3 to 4 and FIG. 2) Japanese Patent Laid-Open No. 2001-27601 (pages 2 to 3 and FIG. 2) Yukihiro Ozaki, Kaoru Kawada, “Near-Infrared Spectroscopy”, Academic Publishing Center)

  However, like the above-mentioned conventional infrared gas analyzers, the static method requires the use of a plurality of expensive light receiving elements, and the measurement wavelength is usually limited to a few points, which limits the miniaturization of the elements. Since the dynamic Fabry-Perot structure uses microfabrication technology, it has problems such as multi-step device assembly and manufacturing yield, and there is a problem of variation in measurement wavelength due to processing accuracy for each element. There was a problem in terms of sex.

  The present invention has been made in view of the above-described points, and its object is to provide a spectroscopic method capable of detecting a specific component contained in a fluid with a good production yield and a small optical system. It is to provide a specific component sensor.

The invention according to claim 1 is a spectroscopic specific component sensor for detecting a specific component contained in a fluid consisting of a gas or a liquid, the light source for emitting beam light, and a cylindrical interior formed in the cylindrical shape. Is a flow path for the fluid, and is irradiated with the beam light; a light reflector that is on the opposite side of the light source with respect to the flow path and reflects the beam light; and the flow path with respect to the flow path A light receiver that is on the same side as the light source and receives the light beam reflected by the light reflector, and splits the light beam on an optical axis from the light source to the light receiver via the light reflector. A plurality of optical multilayer filters that transmit light of different wavelength bands, arranged in the optical axis direction, and the plurality of optical multilayer filters are disposed on the optical axis. Individual position control of whether or not to insert Together takes place, characterized in that the chopper for the light beam is inserted on the optical axis in combination as the transmission wavelength band does not overlap with mechanical drive.

In this structure, a plurality of optical multilayer filters can be inserted on the optical axis of the beam light, and a plurality of spectral characteristics can be measured sequentially by a combination of optical multilayer filters inserted on the optical axis. The specific component contained in the fluid can be detected by a small optical system based on the plurality of spectral characteristics. Moreover, the optical path length in the fluid of the beam light can be increased by the light reflector. From the above, a small spectroscopic specific component sensor can be realized. Moreover, in this structure, since the mechanical drive of the optical multilayer filter can be used as a chopper function, a chopper can be made unnecessary.

  According to a second aspect of the present invention, in the first aspect of the invention, the filter spectroscopic unit is provided with a plurality of armatures whose positions are displaced by electromagnetic drive, and the armatures each transmit light of different wavelength bands. A membrane filter is provided. In this structure, since each armature whose position is displaced by electromagnetic drive is provided with an optical multilayer filter, a small-sized filter spectroscopic unit that can be easily controlled at high speed can be configured.

  According to a third aspect of the present invention, in the first aspect of the present invention, the filter spectroscopic unit is provided with a plurality of rotating bodies having a rotation axis substantially orthogonal to the optical axis and rotationally driven. Each of the rotating bodies is provided with the optical multilayer filter that changes the incident angle of the beam light and transmits light of different wavelength bands. In this structure, the incident angle of the beam light can be changed by the rotation angle of the rotator provided with the optical multilayer filter, and the transmission wavelength band of the optical multilayer filter can be shifted. Can be configured.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the filter spectroscopic unit is provided with a plurality of rotating bodies that have a rotation axis substantially parallel to the optical axis and are driven to rotate, and the rotation direction of the rotating body. Each of the rotating bodies is provided with the optical multilayer filter that is composed of an inclined thickness multilayer film whose thickness changes in FIG. In this structure, the film thickness of the optical multilayer filter inserted on the optical axis can be changed depending on the rotation angle of the rotator, and the transmission wavelength band of the optical multilayer filter can be shifted. A simple filter spectroscopic unit can be configured.

  The invention according to claim 5 is the invention according to claim 1, further comprising: a mechanism for rotating the filter spectroscopic unit having a rotation axis substantially orthogonal to the optical axis; and a rotation angle detection unit. The optical multilayer filter that transmits light of different wavelength bands is provided on the mechanism. In this structure, the transmission wavelength band can be shifted by changing the incident angle of the light beam using an optical multilayer filter having a rotation axis perpendicular to the optical axis of the light beam and continuously rotating. Therefore, a small filter spectroscopic unit can be configured with a simple drive system at low cost.

The invention of claim 6 is the invention according to any one of claims 1 to 5, the light receiving element of the light receiver is characterized in that Ru Oh in the pyroelectric element. Since the light reception detection by the pyroelectric element is a differential type, a chopper of the beam light is necessary originally. However, in this structure, the mechanical drive of the optical multilayer filter can be used as a chopper function, so a chopper is unnecessary. Can be.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the light reflector is composed of a metal film and a protective film, and at least one of the light reflectors is disposed on the outer surface of the detector tube. It is characterized by being formed directly. In this structure, since the light reflector is directly formed on the outer surface of the detection tube, the reflected light path length can be increased without increasing the number of components, and the measurement accuracy can be improved. Moreover, corrosion resistance can be ensured by forming a protective film.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein one or a plurality of planar shape portions are provided on a cross section of the detection tube, and the light reflector is provided in the planar shape portion. It is characterized by that. In this structure, since the light reflector is a flat surface, a multiple reflection optical system can be realized without changing the beam light diameter on the reflection surface.

  The invention according to claim 9 is the invention according to any one of claims 1 to 7, characterized in that the detection tube and the light reflector have a curved lens structure. In this structure, it is possible to improve the measurement accuracy by the volume effect by expanding the beam light incident on the detection tube by the lens effect and condensing it at the emission part via the light reflector.

  According to the present invention, it is possible to detect a specific component contained in a fluid with a small optical system with a good manufacturing yield.

(Embodiment 1)
First, the basic configuration of the first embodiment will be described with reference to FIG. 1 or FIG.

  The spectroscopic specific component sensor according to the first embodiment measures the spectral characteristics of a light-transmitting fluid such as a gas or a liquid, and detects the presence or amount of the specific component of the fluid. FIG. As shown, a light source 2, a detection tube 3, a light reflector 4, a light receiver 5, a filter spectroscopic unit 6, a spectral characteristic measurement control unit 7, and a specific component determination unit 8 are included in the housing 1. Prepare.

  The light source 2 emits beam light for irradiating a fluid object that is an object to be detected. For example, an infrared LED is used as the light source 2. The wavelength region of the light source 2 is, for example, 780 nm to 1 mm in the case of infrared rays.

  The detection tube 3 is formed in a cylindrical shape. The cylindrical inside of the detection tube 3 is a fluid flow path, and the fluid is irradiated with beam light.

  The light reflector 4 is provided on or near the detection tube 3 so as to be opposite to the light source 2 with respect to the flow path of the fluid to be detected, and reflects the irradiated beam light. That is, the beam light applied to the detection tube 3 from the light source 2 passes through the fluid flow path in the detection tube 3, is reflected by the light reflector 4, and then passes through the fluid flow path again. The light reflector 4 is made of, for example, a metal film or a combination of a metal film and a protective film (for example, an organic film). For example, the metal film is formed by vacuum deposition of an aluminum film, a gold film, or the like, or by electroless plating of nickel or the like.

  The light receiver 5 is on the same side as the light source 2 with respect to the flow path of the fluid to be detected, and receives the light beam reflected by the light reflector 4. The light receiver 5 uses, for example, an InGaAs PIN photodiode or a pyroelectric element as a differential detection element as a light receiving element.

  The filter spectroscopic unit 6 is provided on the optical axis from the light source 2 through the light reflector 4 to the light receiver 5. In FIG. 1, it is provided between the light source 2 and the detection tube 3. As shown in FIG. 2A, a plurality of optical multilayer filters 60 are provided inside the filter spectroscopic unit 6, and beam light is dispersed by a combination of the optical multilayer filters 60. The split light is finally received by the light receiver 5 (see FIG. 1). The filter spectroscopic unit 6 is provided with a plurality of armatures 61, for example.

  Each optical multilayer filter 60 is a bandpass filter centered on a predetermined peak wavelength, and can transmit light of different wavelength bands. Also, each optical multilayer filter 60 can control the position of whether or not it is inserted on the optical axis of the beam light. When the optical multilayer filter 60 is inserted on the optical axis of the beam light in such a combination that the respective transmission wavelength bands do not overlap with each other, the beam light can be prevented from being transmitted at all. Also has a function as a chopper for beam light.

  Each armature 61 includes an optical multilayer filter 60 (for example, four) that transmits light in wavelength bands having different peak wavelengths (λ1, λ2, λ3, λ4). Further, the armature 61 is made of, for example, a metal film, and as shown in FIG. 2C, a magnet 62 is provided in the vicinity and the position is displaced by electromagnetic driving. That is, the armature 61 has a driving direction (FIG. 2 (a) perpendicular to the optical axis (left-right direction in FIG. 2 (a)) as shown in FIG. ) In the vertical direction). For example, when the magnet 62 is turned off, the optical multilayer filter 60 on the armature 61 moves by the stroke of the arrow in the vertical direction and is inserted on the optical axis of the beam light.

  As shown in FIG. 1, the spectral characteristic measurement control unit 7 controls whether or not the optical multilayer filter 60 in the filter spectral unit 6 is inserted into the optical axis of the beam light in order to obtain predetermined spectral characteristics. To do. For example, the spectral characteristic measurement control unit 7 controls the movement of each armature 61 (see FIG. 2A) and inserts some of the optical multilayer filter 60 on the optical axis of the beam light. Further, the spectral characteristic measurement control unit 7 stores the amount of received light measured by the light receiver 5.

  The specific component determination unit 8 determines the presence / absence or amount of the specific component of the fluid from the plurality of spectral characteristic measurement results obtained by changing the control of each optical multilayer filter 60.

  Next, the operation of the first embodiment will be described. An infrared LED is used as the light source 2 and an InGaAs PIN photodiode is used as the light receiver 5. As shown in FIG. 2, four band-pass filters 60 are arranged as optical multilayer filters on the armature 61 along the optical axis (in the direction of the arrow) of the beam light. The peak wavelengths of the band pass filter 60 are 1552.5 nm, 1551.7 nm, 1550.9 nm, and 1550.1 nm, respectively. Only one of the bandpass filters 60 is inserted on the optical axis of the beam light under the control of the spectral characteristic measurement control unit 7.

  As shown in FIG. 1, the beam light emitted from the light source 2 enters the filter spectroscopic unit 6. The light beam passes through the bandpass filter 60 set as described above and enters the detection tube 3. The beam light is reflected by the light reflector 4, exits from the detection tube 3, is received by the light receiver 5, and the transmittance for each wavelength of the beam light is measured.

  FIG. 3 shows data obtained by measuring the transmittance with respect to the wavelength of the beam light when only one of the bandpass filters 60 is inserted on the optical axis. The transmittance 0 dB corresponds to the transmittance when the bandpass filter 60 is not provided. The transmittance of each bandpass filter 60 has a transmission wavelength band centered on the peak wavelength.

  When measuring the fluid of the object to be detected, the spectral characteristic measurement control unit 7 (see FIG. 1) determines one or more combinations of the bandpass filters 60 having the transmittance characteristics as described above, and detects them. A fluid substance to be detected is introduced into the tube 3 to measure the spectral characteristics for each combination, and the specific component determination unit 8 (see FIG. 1) determines the specific component of the fluid object.

  As described above, according to the first embodiment, the optical multilayer filter 60 is provided on the armature 61 whose position is displaced by electromagnetic driving so as to be inserted on the optical axis of the beam light, and is inserted on the optical axis. Since a plurality of spectral characteristics can be sequentially measured by the combination of the membrane filter 60, the presence or amount or the amount of a specific component contained in the fluid is reduced in size and high speed in a plane orthogonal to the optical axis. It can be detected by the filter spectroscopic unit 6 which is easy to control. The light reflector 4 can also increase the optical path length of the beam light in the fluid. From the above, a small spectroscopic specific component sensor can be realized.

(Embodiment 2)
The second embodiment includes a light source 2, a detection tube 3, a light reflector 4, a light receiver 5, a filter spectroscopic unit 6, a spectral characteristic measurement control unit 7, and a specific component determination unit 8 in the housing 1. The filter spectroscopic unit 6 is similar to the first embodiment in that a plurality of optical multilayer filters 60 that transmit light in different wavelength bands are provided, but there are the following characteristic portions that are not in the first embodiment. As shown in FIG. 4, the filter spectroscopic unit 6 includes a rotation driving mechanism having a rotation axis substantially orthogonal to the optical axis, and a rotation angle detection unit 64, and transmits light of different wavelength bands on the mechanism. A multilayer filter 60 is provided.

  The rotation driving mechanism of the second embodiment is provided with a rotation angle detection mechanism as will be described later. It has a rotation axis substantially orthogonal to the optical axis of the beam light, and is driven to rotate by a small motor 640. The small motor 640 rotates the slit plate 641 simultaneously with the optical multilayer filter 60. The slit plate 641 has, for example, two slit holes 641a with a 180 degree relationship, and a photocoupler 642 is disposed in the vicinity thereof. When the slit plate 641 is continuously driven to rotate and the slit hole 641a passes through the photocoupler 642, a photocoupler signal as shown in FIG. This photocoupler signal is generated at a preset rotation angle. In FIG. 5, it is set to measure when the incident angle of the light beam is 0 °. By adjusting the positions of the slit hole 641a of the slit plate 641 and the optical multilayer filter 60, the incident angle of the beam light can be changed.

  The optical multilayer filter 60 of the second embodiment is different from the first embodiment in that the optical multilayer filter 60 is a film in which the incident angle of the beam light is variable by rotation. An arbitrary incident angle is set by utilizing the phenomenon that the optical characteristics shift to the short wavelength side when the incident light is obliquely incident. When the incident angle of the optical multilayer filter 60 is controlled, it becomes impossible to transmit the light beam at all, and it has a function as a chopper for the light beam. In this way, the incident angle of the beam light changes, and the transmission wavelength band is shifted by the optical path difference of interference to perform fine adjustment of the transmission wavelength, or it can be removed from the beam optical system itself. A wide wavelength range can be covered by arranging a plurality of the optical multilayer filter 60 as described above.

  Next, an example of a spectroscopic measurement design using the continuously rotating bandpass filter 60 of the second embodiment will be shown. When the incident angle of the beam light is changed, as shown in FIG. 6, the transmittance characteristics for each wavelength change, and the bandpass characteristics of the transmission spectrum of the optical multilayer filter 60 shift to the lower wavelength side. This shows a phenomenon in which the bandpass characteristic of the transmission spectrum shifts to the lower wavelength side.

  When measuring the fluid of the object to be detected, the spectral characteristic measurement control unit 7 shown in FIG. 1 determines one or a plurality of combinations of the optical multilayer filter 60 having the transmittance characteristics as described above, and detects it. A fluid substance as an object to be detected is introduced into the tube 3 to measure the spectral characteristics for each combination, and a specific component determination unit 8 determines a specific component of the fluid substance.

  As described above, according to the second embodiment, in the optical multilayer filter 60 that continuously rotates with the rotation axis substantially orthogonal to the optical axis of the light beam, the incident angle of the light beam changes and the transmission wavelength band is shifted depending on the rotation angle. Therefore, the filter spectroscopic unit 6 that is small in size and can be easily controlled at high speed can be configured with a low-cost and simple drive system.

  As a modification of the second embodiment, as shown in FIG. 7, the filter spectroscopic unit 6 (see FIG. 1) is provided with a plurality of rotating bodies 63 in which the optical axis and the rotation axis are in eccentric positions, Each of the rotating bodies 63 may be provided with an optical multilayer filter 60 in which the incident angle of the light beam is variable depending on the rotation angle of the body 63. With such a configuration, the incident angle of the beam light can be varied depending on the rotation angle of the rotator 63, and the transmission wavelength band of the optical multilayer filter 60 can be shifted. The filter spectroscopic unit 6 that can be easily controlled at high speed can be configured.

(Embodiment 3)
The third embodiment includes a light source 2, a detection tube 3, a light reflector 4, a light receiver 5, a filter spectroscopic unit 6, a spectral characteristic measurement control unit 7, and a specific component determination unit 8 in the housing 1. The filter spectroscopic unit 6 is similar to the first embodiment in that a plurality of optical multilayer filters 60 that transmit light in different wavelength bands are provided, but there are the following characteristic portions that are not in the first embodiment. As shown in FIG. 8, the filter spectroscopic unit 6 (see FIG. 1) is provided with a plurality of rotating bodies 63 that are rotationally driven, and each rotating body 63 includes an optical multilayer filter 60.

  As shown in FIG. 9, the rotating body 63 of the third embodiment is made of, for example, a disk-shaped substrate, and is provided with a rotation angle detection mechanism as described later. The rotation axis is substantially parallel to the optical axis of the beam light, and the rotation axis is deviated from the optical axis. It is rotated by a small motor 640. The small motor 640 rotates the slit plate 641 simultaneously with the rotating body 63. The slit plate 641 is provided with, for example, two slit holes 641a in a 180-degree relationship, and a photocoupler 642 is disposed in the vicinity thereof. When the slit plate 641 is continuously driven to rotate and the slit hole 641a passes through the photocoupler 642, a photocoupler signal is generated. This photocoupler signal is generated at a predetermined rotation angle.

  As shown in FIG. 8, the optical multilayer filter 60 according to the third embodiment includes a circular type multilayer film having a thickness distribution inclined in the rotation direction of the rotating body 63 as shown in FIG. When the thickness of the film is variable, the transmission wavelength band shifts. As described above, in the plurality of optical multilayer filters 60 of the gradient film thickness type, the rotation axis of the rotating body 63 and the optical axis are deviated, so that the rotational position of each optical multilayer filter 60 can be changed independently to change the film Only the light of an arbitrary wavelength can be transmitted by changing the thickness. When the optical multilayer filter 60 is not used, the light beam in the entire wavelength region is transmitted when the rotating body 63 is driven to rotate and the rotation position is set to the film non-forming part 63a.

  In the third embodiment, a pyroelectric element is used as a light receiving element (not shown) of the light receiver 5 (see FIG. 1). Since the pyroelectric element is a differential detection element, it requires pulsed beam light. Therefore, the optical multilayer filter 60 is used as a chopper for the beam light by controlling the transmission of the beam light by mechanical driving of the optical multilayer filter 60.

  Next, an example of a spectroscopic measurement design using the gradient film thickness type optical multilayer filter 60 of Embodiment 3 will be shown. When the rotational position of the optical multilayer filter 60 is changed, as shown in FIG. 10, the transmittance characteristics for each wavelength change, and the transmission wavelength band of the optical multilayer filter 60 shifts to a lower wavelength side as the film thickness increases. To do.

  When measuring the fluid of the object to be detected, the spectral characteristic measurement control unit 7 shown in FIG. 1 determines one or a plurality of combinations of the optical multilayer filter 60 having the transmittance characteristics as described above, and detects it. A fluid substance as an object to be detected is introduced into the tube 3 to measure the spectral characteristics for each combination, and a specific component determination unit 8 determines a specific component of the fluid substance.

  As described above, according to the third embodiment, since the transmission wavelength band of the optical multilayer filter 60 can be shifted depending on the rotational position of the rotating body 63, the filter is small in size and easy to control at high speed in the plane orthogonal to the optical axis. The spectroscopic unit 6 can be configured.

  Even if a pyroelectric element (not shown) is used for the light receiver 5, the mechanical drive of the optical multilayer filter 60 can be used as a chopper function, so that a chopper can be dispensed with.

(Embodiment 4)
The fourth embodiment includes a light source 2, a detection tube 3, a light reflector 4, a light receiver 5, a filter spectroscopic unit 6, a spectral characteristic measurement control unit 7, and a specific component determination unit 8 in the housing 1. The filter spectroscopic unit 6 is similar to the first embodiment in that a plurality of optical multilayer filters 60 that transmit light in different wavelength bands are provided, but there are the following characteristic portions that are not in the first embodiment. As shown in FIG. 11, the light reflector 4 made of a metal film and a protective film is directly provided on the outer surface of the detection tube 3 and integrated with the detection tube 3. For example, a gold film is vapor-deposited on a part of the outer surface of the sapphire pipe of the detector tube 3 and further coated with an organic protective film.

  In addition, organic gases containing carbon components such as hydrocarbons including methane and carbon monoxide, water vapor, etc. should be applied as sensors for specific gases that have a wavelength absorption range due to their molecular structure in the near infrared or mid infrared range. It is characterized by.

  12 and 13 show the amounts of light when city gas (main component is methane) and carbon monoxide are introduced into the detection tube 3 as the gas of the fluid that is the object to be detected. From these figures, it can be said that Embodiment 4 functions as a gas sensor because wavelength dependence differs for each gas.

  As described above, according to the fourth embodiment, since the light reflector 4 is directly formed on the outer surface of the detection tube 3 as a metal film, the reflected light path length can be increased without increasing the number of components, while maintaining a small and compact optical system. And the measurement accuracy can be improved. Moreover, corrosion resistance can be ensured by forming an organic protective film on the metal film.

  Furthermore, it can be applied as a gas sensor for hydrocarbon-based organic gas containing carbon components, such as water vapor, and water vapor, and a small and compact gas detector can be realized.

  As a modification of the fourth embodiment, as shown in FIG. 14, only one surface of the light reflector 4 made of a metal film may be provided.

  As another modification of the fourth embodiment, a plurality of light reflectors 4 may be provided as shown in FIG. In such a configuration, a multiple reflection optical path is formed, and the reflection optical path length can be further increased without increasing the number of parts of the plurality of light reflectors 4.

  As another modification of the fourth embodiment, as shown in FIG. 16, a plurality of light reflectors 4 that are specularly reflected, such as a regular reflection surface metal film, are provided on the outer surface of the detection tube 3 in a spiral manner with the flow path direction as an axis. May be. Since such a configuration forms a multiple reflection optical path in the flow path direction, the reflection optical path length in the detection tube 3 can be greatly increased to improve measurement accuracy.

  Furthermore, as another modification of the fourth embodiment, as shown in FIG. 17, the optical measuring portion of the detection tube 3 has a spherical shape, the outer surface is roughened, and then a light reflector 4 that irregularly reflects, such as a metal film. May be provided on a spherical surface. By irregularly reflecting in this way, the optical path length can be increased by a plurality of multiple reflection optical systems in the detection tube 3, and the measurement accuracy can be improved.

(Embodiment 5)
In the fifth embodiment, the light source 2, the detection tube 3, the light reflector 4, the light receiver 5, the filter spectroscopic unit 6, the spectral characteristic measurement control unit 7, and the specific component determination unit 8 are provided in the housing 1. The filter spectroscopic unit 6 is similar to the first embodiment in that a plurality of optical multilayer filters 60 that transmit light in different wavelength bands are provided, but there are the following characteristic portions that are not in the first embodiment. As shown in FIG. 18, two planar portions 30 are provided on the cross section of the detection tube 3, and each planar portion 30 includes the light reflector 4 on the inner planar portion.

  The optical path of the beam light in the detection tube 3 is sequentially reflected by the light reflectors 4 of the respective planar shapes 30 as indicated by arrows. Further, since the beam light is reflected by the flat portion, the beam light diameter is not deformed.

  As described above, according to the fifth embodiment, since the light reflector 4 is a plane, a multiple reflection optical system is realized without changing the beam light diameter on the reflection surface, and the measurement accuracy is improved by increasing the optical path length. Can do.

  As a modification of the fifth embodiment, three or more planar shape portions 30 may be provided. In such a configuration, the optical path length can be further increased and the measurement accuracy can be improved.

  Further, as another modification of the fifth embodiment, only one planar portion 30 may be provided. Even with such a configuration, deformation of the beam light diameter can be prevented.

(Embodiment 6)
Embodiment 6 includes a light source 2, a detection tube 3, a light reflector 4, a light receiver 5, a filter spectroscopic unit 6, a spectral characteristic measurement control unit 7, and a specific component determination unit 8 in the housing 1. The filter spectroscopic unit 6 is similar to the first embodiment in that a plurality of optical multilayer filters 60 that transmit light in different wavelength bands are provided, but there are the following characteristic portions that are not in the first embodiment. As shown in FIG. 19, the light beam of the detection unit 3 is provided with an entrance lens 31a at the entrance, and an exit lens 31b at the exit, and the detection tube 3 and the light reflector 4 have a curved lens structure.

  The beam diameter of the light beam from the light source 2 is first enlarged by the entrance lens 31a. Next, the beam light whose beam diameter is enlarged is transmitted through the detection tube 3 and reflected by the light reflector 4. Then, the reflected light from the light reflector 4 is condensed and collimated to the emitting lens 31b to become parallel light.

  As described above, according to the sixth embodiment, it is possible to improve the measurement accuracy by the volume effect by expanding the beam light incident on the detection tube 3 by the lens effect and condensing the light beam at the emission part via the light reflector 4. it can.

It is a block diagram of the spectroscopic specific component sensor of Embodiment 1 by this invention. It is a block diagram of an optical multilayer film filter same as the above, (a) is a side view, (b) is a top view, (c) is sectional drawing of A'-A of (b). It is a figure which shows the transmittance | permeability of each bandpass filter same as the above. It is a block diagram of the optical multilayer filter in the spectroscopic specific component sensor of Embodiment 2 by this invention, Comprising: (a) is a top view, (b) is sectional drawing, (c) is a figure which shows a slit board. It is a figure which shows the measurement timing same as the above. It is a figure which shows the transmittance | permeability with respect to the incident angle of the laser beam same as the above. It is a figure which shows the modification of an optical multilayer film filter same as the above. It is a block diagram of the optical multilayer filter in the spectroscopic specific component sensor of Embodiment 3 by this invention. It is a side view of an optical multilayer filter same as the above. It is a figure which shows the transmittance | permeability with respect to the rotation angle of an optical multilayer filter same as the above. It is the installation figure of the light reflector in the spectroscopic specific component sensor of Embodiment 4 by this invention. It is a figure which shows a result when measuring city gas (methane) using the same as the above. It is a figure which shows a result when carbon monoxide gas is measured using the same as the above. It is a figure which shows the modification of a light reflector same as the above. It is a figure which shows several light reflectors same as the above. It is a figure which shows the light reflector provided in the spiral form same as the above. It is an installation figure of the light reflector which carries out the irregular reflection same as the above. It is the installation figure of the light reflector in the spectroscopic specific component sensor of Embodiment 5 by this invention. It is the installation figure of the light reflector in the spectroscopic specific component sensor of Embodiment 6 by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Light source 3 Detector tube 4 Light reflector 5 Light receiver 6 Filter spectroscopy part 60 Optical multilayer filter 7 Spectral characteristic measurement control part 8 Specific component determination part

Claims (9)

A spectroscopic specific component sensor for detecting a specific component contained in a fluid consisting of gas or liquid,
A light source that emits beam light;
A detection tube which is formed in a cylindrical shape and the inside of the cylindrical shape is a flow path of the fluid and is irradiated with the beam light;
A light reflector that reflects the beam light on the opposite side of the light source with respect to the flow path;
A light receiver that is on the same side as the light source with respect to the flow path and receives the beam light reflected by the light reflector;
A filter spectroscopic unit that splits the beam light on an optical axis from the light source via the light reflector to the light receiver,
In the filter spectroscopic unit, a plurality of optical multilayer filters that transmit light of different wavelength bands are arranged in the optical axis direction,
The plurality of optical multilayer filters are individually controlled in position whether or not to be inserted on the optical axis, and are inserted on the optical axis in such a combination that transmission wavelength bands do not overlap by mechanical drive. A spectroscopic specific component sensor, which serves as a chopper for the light beam . A plurality of armatures whose positions are displaced by electromagnetic drive in the filter spectroscopic unit,
The spectroscopic specific component sensor according to claim 1, wherein each of the armatures includes the optical multilayer filter that transmits light of different wavelength bands. The filter spectroscopic unit is provided with a plurality of rotating bodies that have a rotation axis substantially orthogonal to the optical axis and that are driven to rotate,
2. The spectroscopic specification according to claim 1, wherein each of the rotating bodies includes the optical multilayer film filter that transmits light of different wavelength bands by changing an incident angle of the light beam according to a rotation angle of the rotating body. Component sensor. The filter spectroscopic unit is provided with a plurality of rotating bodies that have a rotation axis substantially parallel to the optical axis and are driven to rotate.
2. The spectroscopic structure according to claim 1, wherein each of the rotating bodies includes the optical multilayer filter that is formed of an inclined thickness multilayer film whose film thickness changes in the rotation direction of the rotating body and transmits light of different wavelength bands. Formula specific component sensor. A mechanism having a rotation axis substantially orthogonal to the optical axis in the filter spectroscopic unit, and a rotational drive mechanism;
A rotation angle detector,
The spectroscopic specific component sensor according to claim 1, wherein the optical multilayer filter that transmits light of different wavelength bands is provided on the mechanism. Spectroscopic particular component sensor according to any one of claims 1 to 5 the light-receiving element of the light receiver, characterized in that Ru Oh in the pyroelectric element.   7. The spectroscopic specific component sensor according to claim 1, wherein the light reflector is made of a metal film and a protective film, and at least one light reflector is directly formed on the outer surface of the detection tube. . One or a plurality of planar shape portions are provided on the cross section of the detection tube,
The spectroscopic specific component sensor according to claim 1, wherein the planar shape portion includes the light reflector.   The spectroscopic specific component sensor according to claim 1, wherein the detection tube and the light reflector have a curved lens structure.

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