WO2009144962A1 - Système de mesure - Google Patents

Système de mesure Download PDF

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Publication number
WO2009144962A1
WO2009144962A1 PCT/JP2009/002419 JP2009002419W WO2009144962A1 WO 2009144962 A1 WO2009144962 A1 WO 2009144962A1 JP 2009002419 W JP2009002419 W JP 2009002419W WO 2009144962 A1 WO2009144962 A1 WO 2009144962A1
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WIPO (PCT)
Prior art keywords
unit
amplification factor
light
amplification
optical fiber
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PCT/JP2009/002419
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English (en)
Japanese (ja)
Inventor
博幸 佐々木
錠一 前
一弘 渡辺
道子 西山
Original Assignee
学校法人創価大学
タマティーエルオー株式会社
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Application filed by 学校法人創価大学, タマティーエルオー株式会社 filed Critical 学校法人創価大学
Publication of WO2009144962A1 publication Critical patent/WO2009144962A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
    • G01D5/35341—Sensor working in transmission
    • G01D5/35345—Sensor working in transmission using Amplitude variations to detect the measured quantity

Definitions

  • the present invention relates to a measurement system using an optical fiber sensor.
  • the amount of transmission light leakage due to the bending of the optical fiber is measured to detect the bending of the optical fiber.
  • the FBG (Fiber-Bragg-Grating) method forms a diffraction grating in the core in the middle of the optical fiber and measures the frequency change of the transmitted light.
  • a specific frequency that is, a wavelength component called a black wavelength is reflected by the diffraction grating section, and the remaining other frequency components pass.
  • the amount of shift of the black wavelength depends on the grating interval, and distortion generated in the diffraction grating due to stress, temperature, or the like is detected from the change in the frequency of the transmitted light.
  • BOTOR method (Brillouin Optical Domain Reflectometer) measures changes in reflection frequency due to Brillouin scattered light caused by distortion of an optical fiber, using a BOTOR measuring instrument.
  • hetero-core type optical fiber sensor The details of the hetero-core type optical fiber sensor are disclosed in International Publication No. 97/48994 Pamphlet and Japanese Patent Application Laid-Open No. 2003-214906.
  • the amount of transmission light leakage due to bending of the optical fiber is very small. Therefore, in order to measure the change in the amount of light received by the light receiving unit, a light emitting unit that emits light of high light intensity is required. Therefore, it is necessary to use a laser diode or the like as the light source. Therefore, in the microbending method, the measurement system including the light emitting unit is expensive.
  • the FBG method requires a light emitting unit that emits light having a variable wavelength in a predetermined range, for example, 1530 nm to 1580 nm, with wavelength accuracy on the order of pm. Therefore, it is difficult to control the light source, and the measurement system including the light emitting unit is expensive.
  • the BOTOR method requires a light emitting unit that emits a light pulse having a high light intensity with a pulse period of 1 ⁇ m or less. It is difficult to turn on / off a light source with high light intensity in a short period, and a measurement system including a light emitting unit becomes expensive.
  • the present invention has been made in view of the above points, and an object of the present invention is to provide a measurement system using an optical fiber sensor that includes a light emitting unit and is inexpensive.
  • the measurement system of the present invention includes a light receiving unit that generates an electric signal according to the intensity of received light, the electric signal input from the light receiving unit, and the electric signal amplified according to an amplification factor set from the outside.
  • a measuring instrument, a light emitting unit, and a core and the core that calculate the amplification factor in the amplification unit according to the digital signal and output the calculated amplification factor to the amplification unit
  • An optical fiber including a clad laminated on the outer periphery of the optical fiber, and a light transmission member composed of a hetero core portion having a core diameter different from the core diameter of the optical fiber, Light from the serial light emitting portion, characterized in that it comprises an optical fiber sensor for emitting the light receiving unit from the exit end of the light
  • the measurement system of the present invention is an optical fiber sensor having an optical fiber including a core and a clad laminated on the outer periphery of the core, and a light transmission member including a hetero-core portion having a core diameter different from the core diameter of the optical fiber. It has.
  • the transmission light loss caused by the bending of the optical fiber sensor in the vicinity of the light transmitting member is much larger than the transmission light loss caused by the bending of the optical fiber in the microbending method. Therefore, unlike the microbending method, it is not necessary to use a laser diode for the light emitting unit, and therefore the measurement system is inexpensive.
  • a light emitting unit that emits light with a variable wavelength in a predetermined range with a wavelength accuracy of the order of pm is not required, and the light source can be easily controlled, so that the measurement system is inexpensive.
  • a light emitting unit that emits a light pulse having a high light intensity with a pulse period of 1 ⁇ m or less is not required, and the control of the light source is facilitated, so that the measurement system is inexpensive.
  • the amplification factor calculation unit calculates according to the digital signal and sets the amplification factor.
  • the amplification unit automatically amplifies the electric signal, the performance of the analog-digital conversion unit can be satisfactorily exhibited.
  • the amplification factor calculation unit calculates the amplification factor so that the electric signal amplified by the amplification unit has a value commensurate with an input possible range of the analog-digital conversion unit. It is preferable to do.
  • the measuring instrument has a digital-analog conversion unit that converts the digital amplification factor calculated by the amplification factor calculation unit into analog and inputs the analog amplification factor to the amplification unit.
  • an amplifier that cannot be digitally input can be used.
  • the amplification factor calculation unit calculates the amplification factor set in the amplification unit, and outputs the calculated amplification factor to the amplification unit. Is preferred.
  • the amplification factor calculation unit calculates the amplification factor, and a suitable amplification factor is set in the amplification unit each time.
  • the amplification factor calculation unit calculates an amplification factor set in the amplification unit, and the calculated amplification factor is used as the amplification unit. Is preferably output.
  • the amplification factor calculation unit calculates the amplification factor, and a suitable amplification factor is set in the amplification unit each time.
  • the measurement unit includes a pressing member that outputs an amplification factor calculation setting start signal to the calculation unit when pressed, and the amplification factor calculation setting start signal is input to the calculation unit.
  • the amplification factor calculation unit calculates an amplification factor set in the amplification unit and outputs the calculated amplification factor to the amplification unit.
  • the amplification factor calculation unit calculates the amplification factor, and a suitable amplification factor is set in the amplification unit each time.
  • a plurality of the light transmission members are connected in series to one optical fiber sensor.
  • the light emitting unit includes a light emitting diode or a laser diode as a light source.
  • the light source is downsized and inexpensive, and the control thereof is easy, so that the light emitting unit is downsized and inexpensive.
  • the light receiving unit is constituted by a photodiode.
  • the light receiving section is downsized and inexpensive.
  • FIG. 1 It is a schematic diagram which shows the structure of a measurement system.
  • the sensor part vicinity of an optical fiber sensor is shown notionally, (a) is a perspective view, (b) is longitudinal direction sectional drawing. It is a mimetic diagram showing the composition of the measurement system concerning a 1st embodiment of the present invention. (A) And (b) is longitudinal direction sectional drawing of the sensor part vicinity which concerns on the other example of an optical fiber sensor. It is a schematic diagram which shows the structure of the measurement system which concerns on 2nd Embodiment of this invention.
  • the measurement system includes an optical fiber sensor, a light emitting unit 1, and a measuring instrument 100.
  • light emitted from the light emitting unit 1 connected to one end of the optical fiber sensor is transmitted through the optical fiber sensor, passes through the sensor unit SP, and receives light connected to the other end of the optical fiber sensor.
  • the light intensity received by the unit 11 and received by the measuring instrument 100 is measured.
  • the light emitting unit 1 includes a drive circuit 2 and a light source 3 connected to a power source (not shown). Light is emitted from the light source 3 by driving the drive circuit 2.
  • the light source 3 includes an LED (light emitting diode), an LD (laser diode), and a white light source. Further, as the light source 3, laser plasma, EL (electroluminescence), or the like may be used.
  • the optical fiber sensor includes optical fibers 20a and 20b and a sensor unit SP provided in the middle of the optical fibers 20a and 20b.
  • An optical fiber connector 23a is provided at the end of the optical fiber 20a that is the light incident end of the optical fiber sensor.
  • An optical fiber connector 23b is provided at the end of the optical fiber 20b that is the light emitting end of the optical fiber sensor.
  • the light emitted from the light source 3 of the light emitting unit 1 is incident on the optical fiber 20a through the optical fiber connector 23a, passes through the sensor unit SP, and is emitted to the outside through the optical fiber 20b. .
  • the measuring instrument 100 includes a light receiving unit 11, a preamplifier (amplifying unit) 12, an AD converter (analog-digital conversion unit) 13, and a calculation unit 14.
  • the light receiving unit 11 generates an electric signal according to the intensity of received light, and includes a photodiode (FD) or the like.
  • the preamplifier 12 receives an electric signal from the light receiving unit 11 and amplifies the electric signal according to a predetermined amplification factor (gain).
  • the AD converter 13 converts the analog electric signal amplified by the preamplifier 12 into a digital signal.
  • the arithmetic unit 14 receives a digital signal from the AD converter 13, performs predetermined signal processing on the digital signal, and outputs the signal to the outside.
  • the light emitted from the optical fiber connector 23b to the outside is received by the light receiving unit 11.
  • an electrical signal is generated according to the intensity of the received light and is output to the preamplifier 12.
  • the electrical signal generated by the light receiving unit 11 is input to the preamplifier 12, amplified by a set amplification factor, and output to the AD converter 13.
  • the electrical signal amplified by the preamplifier 12 is an analog signal, is input to the AD converter 13, is converted from an analog signal to a digital signal, and is output to the arithmetic unit 14.
  • the digital signal obtained by the AD converter 13 is input to the arithmetic unit 14 and subjected to predetermined signal processing, and is output to the outside from the terminal T or the like.
  • the amplification factor of the electric signal in the preamplifier 12 is fixed to a certain value or can be manually adjusted from the outside.
  • the optical fibers 20a and 20b have a core 21 and a clad 22 provided on the outer periphery of the core 21.
  • the sensor part SP is composed of a heterocore part 30.
  • the hetero core section 30 includes a core 31 having a core diameter bl different from the core diameter al of the optical fibers 20a and 20b, and a clad 32 provided on the outer periphery of the core 31.
  • optical fibers 20a and 20b for example, a single mode fiber having a core diameter al of about 9 ⁇ m or a multimode fiber having a core diameter al of about 50 ⁇ m can be used.
  • the diameter bl of the core 31 in the hetero-core portion 30 is sufficiently smaller than the diameter al of the core 21 of the optical fibers 20a and 20b.
  • the core diameter al is 9 ⁇ m
  • the core diameter bl is 5 ⁇ m.
  • the length cl of the hetero core part 3 is 1 mm thru
  • optical fibers 20a and 20b and the hetero-core part 30 constituting the sensor part SP are substantially coaxial, for example, melted by a generalized discharge so that the cores 21 and 31 are joined to each other at an interface 40 orthogonal to the longitudinal direction. It is joined by wearing.
  • the core diameter bl of the sensor unit SP and the core diameter al of the optical fibers 20a and 20b are at the interface 40. Is different. Due to the difference in the core diameter at the interface 40, a part of the light transmitted through the optical fiber sensor leaks to the clad 32 of the sensor part SP, and a leak W is generated.
  • the intensity of the transmitted light depends on the curvature of the optical fiber sensor in the vicinity of the sensor unit SP and the presence or absence of liquid on the outer periphery of the sensor unit SP. Change occurs. That is, a sensor signal is placed on the light.
  • the light receiving unit 11 receives the light whose intensity has changed, a change in the intensity of the transmitted light is detected, and the curvature of the optical fiber sensor near the sensor unit SP, the presence or absence of liquid on the outer periphery of the sensor unit SP, and the like are identified. Is done.
  • the magnitude of the leak W is expressed by the curvature of the optical fiber sensor in the vicinity of the sensor unit SP, more precisely, the optical fiber sensor. It changes sharply due to the variation in curvature at the curved interface 40, and increases as the curvature increases.
  • the sensor unit SP is configured as described above, and the optical fiber sensor is arranged so that the curvature of the optical fiber sensor in the vicinity of the sensor unit SP changes according to the displacement of the measurement object and the transmission loss of the transmitted light changes.
  • a curvature detection type measurement system capable of measuring the displacement of the measurement object by detecting a change in curvature of the optical fiber sensor can be obtained.
  • the evanescent wave can be generated at the boundary between and can be applied to the outside world.
  • the evanescent wave is an evanescent (Evanescent) that attenuates exponentially with the distance from the boundary surface, such as a light wave generated in the second medium when light in the first medium is totally reflected at the boundary with the second medium. : A wave that gradually disappears) and a light wave that has virtually no energy. The light that has been interacted with the outside by the evanescent wave is incident on the core 21 of the optical fiber 20b again and transmitted.
  • Refractive index detection type capable of measuring the presence or absence of liquid in the outer periphery of the sensor unit by configuring the sensor unit SP as described above and detecting the refractive index of the substance existing on the outer periphery of the sensor unit SP. Can be obtained.
  • a change in optical loss caused by the sensor unit SP composed of a hetero-core type is monitored as a voltage by the measuring unit 100.
  • the optical loss of 3 dB occurs in the sensor unit SP, for example, the voltage that was 4 V becomes 2 V (half).
  • the electrical signal generated by receiving the light emitted from the output end of the optical fiber 20b by the light receiving unit 11 is relatively weak and is amplified by the preamplifier 12.
  • the light intensity emitted from the light source driven by the drive circuit 2 may slightly change each time a measurement system is constructed or even when the same measurement system is turned on.
  • connection loss slightly changes when the optical fiber sensor and the optical fiber connectors 23a and 23b are connected again. There are things to do.
  • the insertion loss due to the sensor unit SP is slightly different.
  • the insertion loss may vary greatly due to individual differences in the sensor part SP.
  • the intensity of light incident on the light receiving unit 11 is different every time a measurement system is constructed, even when the same measurement system is turned on, or every time the power is turned on, or an optical fiber sensor and optical fiber connectors 23a and 23b. May change slightly each time you connect and.
  • the obtained voltage amplified by the preamplifier 12 may not reach the full scale of the input voltage of the AD converter 13, and at this time, the performance of the AD converter 13 cannot be maximized.
  • a voltage exceeding the input voltage limit of the AD converter 13 may be input, and a normal measurement value may not be obtained.
  • an external input means C for adjusting the amplification factor of the preamplifier 12 may be provided, it is a complicated procedure for the operator to manually adjust the external input means C. It is desirable to omit such procedures.
  • the problem to be solved is that the intensity of the light incident on the light receiving unit 100 varies due to individual differences, environmental differences, and the like. It is difficult to set the preamplifier 12 to amplify the electric signal so that it can be maximized.
  • the measurement system includes an optical fiber sensor, a light emitting unit 1, and a measuring instrument 10.
  • light is emitted from the light emitting unit 1 connected to one end of the optical fiber sensor, and the light transmitted through the optical fiber sensor and passed through the sensor unit SP is connected to the other end of the optical fiber sensor.
  • the light intensity is received by the light receiving unit 11 and measured by the measuring instrument 10.
  • the measuring instrument 10 includes a light receiving unit 11, a preamplifier (amplifying unit) 12, an AD converter (analog-digital conversion unit) 13, a calculation unit 14, an amplification factor calculation unit 15, and a DA converter (digital-analog conversion unit) 16. .
  • the light receiving unit 11 generates an electrical signal according to the intensity of received light, and includes, for example, a photodiode (FD).
  • FD photodiode
  • a CCD (charge coupled device) sensor, a CMOS sensor, a solar panel, or the like may be used as the light receiving unit 11.
  • the preamplifier 12 receives an electric signal from the light receiving unit 11 and amplifies the electric signal according to the amplification factor set and inputted from the outside, here the DA converter 16.
  • the AD converter 13 converts the analog electric signal amplified by the preamplifier 12 into a digital signal.
  • the calculation unit 14 receives a digital signal from the AD converter 13 and performs predetermined signal processing on the digital signal.
  • the amplification factor calculation unit 15 calculates the amplification factor to be set in the preamplifier 12 according to the digital signal. For example, in the amplification factor calculation unit 15, the voltage obtained by the amplification by the preamplifier 12 is further adjusted so that the electric signal amplified by the preamplifier 12 becomes a value suitable for the input possible range of the AD converter 13. The amplification factor is calculated so as to correspond to the full scale of the input voltage.
  • the DA converter 16 converts the digital amplification factor calculated by the amplification factor calculation unit 15 into an analog numerical value and inputs it to the preamplifier 12.
  • the amplification factor calculated by the amplification factor calculation unit 15 is input to the preamplifier 12 and set as the amplification factor of the preamplifier 12.
  • optical fiber sensor and the light emitting unit 1 in the measurement system according to the first embodiment are the same as the optical fiber sensor and the light emitting unit 1 in the measurement system using the measuring instrument 100.
  • the electrical signal generated by the light receiving unit 11 is input to the preamplifier 12, amplified at a predetermined amplification factor, and output to the AD converter 13.
  • the electrical signal amplified by the preamplifier 12 is an analog signal, is input to the AD converter 13, is converted from an analog signal to a digital signal, and is output to the calculation unit 14.
  • the digital signal obtained by the AD converter 13 is input to the arithmetic unit 14.
  • the digital signal obtained by the AD converter 13 is input to the amplification factor calculation unit 15 via the calculation unit 14.
  • the amplification factor calculation unit 15 calculates the amplification factor to be set in the preamplifier 12 according to the input digital signal. For example, in the amplification factor calculation unit 15, the voltage obtained by the amplification by the preamplifier 12 is further adjusted so that the electric signal amplified by the preamplifier 12 becomes a value suitable for the input possible range of the AD converter 13.
  • the amplification factor is calculated so as to correspond to the full scale of the input voltage.
  • the digital amplification factor calculated by the amplification factor calculation unit 15 is converted into an analog numerical value by the DA converter 16 and input to the preamplifier 12.
  • the amplification factor calculated by the amplification factor calculation unit 15 is input to the preamplifier 12 and set as the amplification factor of the preamplifier 12. Subsequent amplification in the preamplifier 12 is performed with the newly set amplification factor.
  • predetermined signal processing is performed on the digital signal from the AD converter 13 in the arithmetic unit 14 and output from the terminal T or the like to the outside of the measuring instrument 10.
  • the calculation of the amplification factor in the amplification factor calculation unit 15 and the setting in the preamplifier 12 are, for example, the amplification factor to be set in the preamplifier 12 when the measurement instrument 10 is turned on. And is input to the preamplifier 12 and set as the amplification factor of the preamplifier 12.
  • an amplification factor to be set in the preamplifier 12 is calculated in the amplification factor calculating unit 15, input to the preamplifier 12, and set as the amplification factor of the preamplifier 12.
  • the measuring instrument 10 may further include a button (pressing member) B that outputs an amplification factor calculation setting start signal to the calculation unit 14 when pressed.
  • a button (pressing member) B that outputs an amplification factor calculation setting start signal to the calculation unit 14 when pressed.
  • the amplification factor to be set in the preamplifier 12 is calculated in the amplification factor calculator 15 and input to the preamplifier 12 to be input to the preamplifier 12. Is set as the amplification factor.
  • the step of calculating the amplification factor to be set in the amplification factor calculation unit 15 is repeated a plurality of times.
  • the amplification factor may be calculated until the amplified electric signal has a value commensurate with the input possible range of the AD converter 13.
  • the measuring instrument 10 amplifies the electric signal from the light receiving unit 11 with a predetermined amplification factor, converts it into a digital signal, calculates the amplification factor to be set from the obtained digital signal, and again calculates the amplification factor of the amplification unit. Therefore, even if the intensity of the light incident on the light receiving unit 11 changes due to individual differences of optical fiber sensors or environmental differences, the performance of the AD converter 13 can always be maximized.
  • the preamplifier 12 can be set to amplify the electrical signal.
  • the amplification factor adjustment in the preamplifier 12 is optimized, and the voltage change is transmitted to the AD converter 13. It is about 3V which is close to the input limit voltage.
  • the measuring instrument 10 can automatically maximize the performance of the AD converter 13. Further, in order to maximize the performance of the AD converter 13, it is not necessary to perform a complicated operation of adjusting the amplification factor of the preamplifier 12 by the external input means C as in the measuring instrument 100.
  • the amount of received light changes each time the measuring instrument 100 is turned on or the optical fiber sensor is connected. Therefore, when the voltage does not reach full scale, the performance of the AD converter 13 is improved. I can't make the most of it. Further, there may be an input exceeding the input voltage limit of the AD converter 13, and in some cases, the operator may manually adjust the gain of the preamplifier 12 by the external input means C, and the operation is complicated. Met.
  • the measuring instrument 10 automatically adjusts the amplification factor of the preamplifier 12, so that the performance of the AD converter 13 can be maximized and is easy to use.
  • the output of the light source 3 can be measured even at ⁇ 40 dBm or less, and the sensitivity of the sensor is about 1 dB.
  • the light source 3 emits light with high light intensity that outputs about 0 dBm. Required. Therefore, it is necessary to use an expensive laser diode or the like as the light source 3.
  • the sensitivity of the sensor is about several dB to several tens dB, and the accuracy of the sensor is low. Note that the amount of light received by both light receiving portions 11 is ⁇ 40 dBm or less, and at least about ⁇ 60 dBm.
  • the configuration of the drive circuit 2 controlled by the light source 3 is simplified without the need for the light emitting unit 1 that emits light of a predetermined range of variable wavelength with a wavelength accuracy of the order of pm.
  • the measurement system is inexpensive.
  • the configuration of the drive circuit 2 controlled by the light source 3 is simplified without the need for the light emitting unit 1 that emits a light pulse having a high light intensity with a pulse period of 1 ⁇ m or less, and the measurement system is inexpensive. It will be something.
  • sensor part SP you may employ
  • the sensor part SP may be configured such that the diameter bl of the core 31 of the heterocore part 30 is larger than the diameter al of the core 21 of the optical fibers 20a and 20b. Good.
  • the sensor portion SP may be made of a material having a refractive index equivalent to the refractive index of the core 21 or the refractive index of the cladding 22 of the optical fibers 20a and 20b.
  • the sensor part SP can be considered as a kind of hetero-core structure in which the diameter of the core 31 is 0 or the same as the diameter of the clad 32.
  • a plurality of sensor units SP are connected in series on one optical fiber.
  • three sensor units SP 1 , SP 2 , SP 3 are connected in series on the optical fibers 20a, 20b, 20c, 20d.
  • the present invention is not limited to this, and a plurality of sensors other than three are provided.
  • the part SP may be connected.
  • the measurement system according to the second embodiment constitutes a measurement system by incorporating the measuring instrument 10. Therefore, as with the measurement system according to the first embodiment, even if the intensity of light incident on the light receiving unit 11 changes due to individual differences or environmental differences of the optical fiber sensors, the performance of the AD converter 13 is always maintained. So that the amplification factor of the preamplifier 12 can be set automatically.
  • an optical fiber sensor in which a plurality of sensor units SP are connected in series increases the total loss, and measurement is performed while appropriately replacing such an optical fiber sensor and an optical fiber sensor in which only one sensor unit SP is connected. Even in such a case, every time the optical fiber sensor is replaced, the amplification factor in the preamplifier 12 can be automatically set so that the performance of the analog-to-digital converter can always be maximized.
  • the present invention is not limited to the above-described embodiments, and may be a form in which the embodiments are appropriately combined, and various modifications can be made without departing from the gist of the present invention.
  • the DA converter 16 constituting the measuring instrument 10 is not necessary when the preamplifier 12 capable of digital input is used.
  • the calculation unit 14 and the amplification factor calculation unit 15 may be realized on an integrated calculation unit in a computer or the like.
  • a first-stage preamplifier or an offset voltage adjustment circuit may be provided between the light receiving unit 11 and the preamplifier 12.
  • a temperature sensor for measuring the temperature of the light receiving unit 11 is provided in the measuring instrument 10, and the calculation unit 14 is input from the AD converter 13 by the temperature detected by the temperature sensor. The value of the digital signal may be corrected. Further, an operational amplifier may be provided between the preamplifier 12 and the AD converter 13, and the temperature correction may be performed by this operational amplifier. In this case, however, the gain of the preamplifier 12 is required to determine the correction circuit constant.
  • the measurement system of the present invention can be applied to a measurement system using an optical fiber sensor having a hetero core type sensor unit.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Optical Transform (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Abstract

L’invention concerne un système de mesure comportant un détecteur optique à fibres comprenant des fibres optiques (20a, 20b) et une section de détection (SP) composée d’une section (30) à cœur hétérogène ; un appareil (10) de mesure ; et une section photoémettrice (1). L’appareil de mesure (10) est équipé d’une section photoréceptrice (11) qui génère un signal électrique correspondant à l’intensité de lumière reçue ; d’un préamplificateur (12) qui amplifie le signal électrique correspondant à un facteur d’amplification fixé par une section (16) calculant un facteur d’amplification ; d’un convertisseur AN (13) qui convertit le signal électrique amplifié en signal numérique ; une section (14) d’opération qui exécute un traitement prédéterminé du signal numérique ; et d’une section (15) de calcul de facteur d’amplification qui calcule le facteur d’amplification pour le préamplificateur (12). Le coût du système de mesure est bas.
PCT/JP2009/002419 2008-05-30 2009-06-01 Système de mesure WO2009144962A1 (fr)

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JP2008-142996 2008-05-30
JP2008142996A JP2011169592A (ja) 2008-05-30 2008-05-30 計測器及び計測システム

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