WO2009128138A1 - Gas analyzing apparatus with built-in calibration gas cell - Google Patents

Gas analyzing apparatus with built-in calibration gas cell Download PDF

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Publication number
WO2009128138A1
WO2009128138A1 PCT/JP2008/057320 JP2008057320W WO2009128138A1 WO 2009128138 A1 WO2009128138 A1 WO 2009128138A1 JP 2008057320 W JP2008057320 W JP 2008057320W WO 2009128138 A1 WO2009128138 A1 WO 2009128138A1
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Prior art keywords
wavelength
calibration
laser light
gas cell
light source
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PCT/JP2008/057320
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French (fr)
Japanese (ja)
Inventor
直樹 松田
直司 森谷
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株式会社島津製作所
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Priority to PCT/JP2008/057320 priority Critical patent/WO2009128138A1/en
Priority to JP2010508053A priority patent/JP5360053B2/en
Priority to CN200880128659.8A priority patent/CN102007397B/en
Publication of WO2009128138A1 publication Critical patent/WO2009128138A1/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
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
    • 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
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/274—Calibration, base line adjustment, drift correction
    • G01N21/276—Calibration, base line adjustment, drift correction with alternation of sample and standard in optical path
    • 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
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
    • G01N2021/396—Type of laser source
    • G01N2021/399—Diode laser
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/12—Circuits of general importance; Signal processing
    • G01N2201/128—Alternating sample and standard or reference part in one path
    • G01N2201/1285—Standard cuvette

Definitions

  • the present invention relates to a gas analyzer using laser absorption spectroscopy.
  • a calibration gas is introduced into the measurement gas cell, and sensitivity calibration is performed from the output.
  • another optical system, a calibration gas cell, and a photodetector are always provided, and a calibration value is obtained by separating a part of the laser beam as measurement light by a half mirror and guiding it to the calibration gas cell.
  • An analyzer that always has a calibration gas cell has the advantage that the calibration value can always be monitored.
  • the S / N (signal-to-noise) ratio in the measurement photodetector decreases.
  • the measurement photodetector that detects the light that has passed through the measurement gas cell it has a monitor photodetector, which increases the need to adjust characteristics such as sensitivity and linearity between the two photodetectors. Also, the apparatus becomes complicated.
  • An object of the present invention is to eliminate the need to introduce a calibration gas into a measurement gas cell and eliminate the need to provide an extra photodetector in an analyzer for laser absorption spectroscopy measurement.
  • the calibration gas cell in order to solve these problems, can be inserted into the optical path only when necessary.
  • the analyzer of the present invention includes a laser light source that generates laser light as measurement light having a specific wavelength absorbed by a measurement target component in a sample gas, a laser light source drive control device that controls driving of the laser light source, A photodetector arranged at a position for receiving the laser beam; a gas cell for measuring a sample gas arranged on the optical path of the laser beam from the laser light source to the photodetector; and at least one in which a calibration gas is enclosed Calibration gas cell, calibration gas cell mounting mechanism capable of detachably placing one of the calibration gas cells on the optical path of the laser beam, and a measurement target in the sample gas based on the detection signal of the photodetector And an arithmetic unit for calculating the component concentration.
  • the wave number is used instead of the wavelength when specifically indicating the wavelength. Since the wave number corresponds to the wavelength, “wavelength” is used as a concept including “wave number” in the present invention.
  • the calibration gas cell is detachably inserted into the optical path used for gas measurement, it is not necessary to add new parts to the optical system. Further, since the laser beam for measurement is not separated by the half mirror, the light amount of the laser beam can be maintained. Furthermore, since calibration is performed using a photo detector for measurement, highly accurate calibration can be realized.
  • the gas cell for calibration can be manufactured with various specifications by changing parameters such as gas type, concentration, pressure, etc., and it is a means to realize more advanced calibration.
  • a laser light source it can be a laser diode that generates only light of a single wavelength, but as a means for expanding the measurement object, making the analysis object versatile, or improving the S / N ratio, A laser light source capable of changing the wavelength can be used.
  • a laser light source it is common to use a DFB laser (Distributed FeedBack ⁇ Laser) diode having a narrow oscillation spectrum line width, but any kind of laser light source can be used as long as it can achieve the same specifications. .
  • the laser light source drive control device controls the drive of the laser light source so as to generate laser light having a specific wavelength when measuring the measurement target component.
  • the wavelength of the laser beam generated can be adjusted by controlling parameters such as the drive current and the temperature of the laser body.
  • the laser light source drive control device preferably includes a wavelength variation data holding unit that holds wavelength variation data indicating the relationship between the wavelength of the generated laser light and the parameters. Controls the driving of the laser light source so that the laser light source generates laser light of a specific wavelength based on the held wavelength variation data.
  • the wavelength tunable laser light source it is possible to use a temperature adjusting mechanism that adjusts the temperature of the laser body and that can change the generated laser wavelength depending on the temperature of the laser body.
  • the laser light source drive control device supplies a constant reference current to the laser body for driving the laser light source and a temperature control current to the temperature adjustment mechanism for adjusting the temperature of the laser body. It is preferably controlled.
  • the current supply to the temperature adjustment mechanism is controlled so that the temperature of the laser main body becomes constant, and when the generated laser wavelength is changed, the temperature of the laser main body changes.
  • the current supply to the temperature adjustment mechanism is controlled.
  • the wavelength tunable laser light source When laser light having a specific wavelength is generated using a wavelength tunable laser light source, it is necessary to accurately set the driving condition of the laser light source. It is preferable that calibration can be performed at any time. If the spectroscope is used, the output wavelength can be adjusted accurately. However, in the present invention, the laser wavelength can be set accurately without using the spectroscope. For this purpose, the wavelength fluctuation data is calibrated from the relationship between the generated laser wavelength and parameters such as the laser body temperature using the reference peak wavelength.
  • a preferred embodiment of the present invention includes a wavelength calibration gas cell in which a gas having a known absorption peak wavelength is enclosed as a calibration gas cell.
  • the laser light source drive control device preferably includes a wavelength variation data calibration unit that calibrates wavelength variation data based on the wavelength of the absorption peak when the wavelength calibration gas cell is attached to the optical path.
  • Such a plurality of absorption peaks may be generated from one wavelength calibration gas cell.
  • the absorption peak used for wavelength calibration should have a large and sharp intensity compared to other absorption peaks. If a plurality of such appropriate peaks are included in the absorption peak generated from one wavelength calibration gas cell, they can be used.
  • wavelength calibration gas cell when there is one appropriate absorption peak generated from one wavelength calibration gas cell, it is preferable to use a plurality of wavelength calibration gas cells in which different gases are sealed.
  • a wavelength calibration gas cell a first wavelength calibration gas cell in which a gas having an absorption peak wavelength longer than a specific wavelength for measuring a measurement target component is enclosed, and a specific It is preferable to include a second wavelength calibration gas cell in which a gas having an absorption peak wavelength shorter than the wavelength is enclosed.
  • Another advantage of performing wavelength calibration is that the laser device can be driven so as to generate laser light with an optimum wavelength that minimizes the influence of interference.
  • the calibration gas cell includes at least two sensitivity calibration gas cells in which measurement target components having different known concentrations are sealed.
  • the computing device has a calibration curve data holding unit for holding calibration curve data for calculating the concentration of the measurement target component, and a calibration curve data holding unit based on the absorbance when the sensitivity calibration gas cell is mounted in the optical path of the laser beam.
  • a calibration curve data calibration unit for calibrating the calibration curve data.
  • the sensitivity calibration gas cell is arranged on the optical path of the laser beam even when measuring the sample gas.
  • the arithmetic unit includes an absorbance correction unit that subtracts the absorbance of the sensitivity calibration gas cell arranged on the optical path of the laser beam when measuring the sample gas from the absorbance obtained from the photodetector.
  • an absorbance correction unit that subtracts the absorbance of the sensitivity calibration gas cell arranged on the optical path of the laser beam when measuring the sample gas from the absorbance obtained from the photodetector.
  • wavelength calibration using a plurality of gas absorption lines as necessary accurate setting of measurement wavelength to reduce the influence of interference gas, or calibration of calibration curve data
  • gas measurement by laser absorption spectroscopy with higher accuracy becomes possible.
  • CH 4 is a graph showing the absorption spectra due to encapsulated wavelength calibration gas cell.
  • H 2 O is a graph showing the absorption spectra due to encapsulated wavelength calibration gas cell.
  • FIG. 1 schematically shows an analyzer according to one embodiment.
  • the laser light source 2 that generates laser light as measurement light having a specific wavelength that is absorbed by the measurement target component in the sample gas is a DFB laser diode that can change the wavelength.
  • the type of the laser light source that can change the wavelength is not particularly limited.
  • the laser light source 2 incorporates a temperature adjustment mechanism 3 composed of a Peltier element in order to adjust the temperature of the laser body.
  • a laser light source drive control device that controls the drive of the laser light source 2
  • a laser drive circuit 4 and a control unit 6 comprising an arithmetic processing circuit, a dedicated computer, or a general-purpose personal computer are provided.
  • the laser drive circuit 4 supplies a constant reference current Io as a drive current for driving the laser light source 2 by a control signal from the control unit 6.
  • the controller 6 further supplies a current It for temperature control to the Peltier element of the temperature adjusting mechanism 3 in order to adjust the wavelength of the laser light generated from the laser light source 2.
  • the wavelength of the laser light generated from the laser light source 2 is scanned so as to be a specific wavelength for measuring the absorbance when the concentration of the measurement target component in the sample gas is measured or sandwiching the specific wavelength.
  • the temperature control current It is controlled.
  • the temperature of the laser body is adjusted to a constant temperature corresponding to the specific wavelength.
  • the temperature control current It is controlled by the controller 6 so that the temperature of the laser body changes.
  • a photodetector 8 is disposed at a position where the measurement laser beam generated from the laser light source 2 is received.
  • the photodetector 8 is a photodiode or a photomultiplier tube.
  • a gas cell 12 for measuring a sample gas is disposed on the optical path 10 of the laser beam for measurement from the laser light source 2 to the photodetector 8.
  • the measurement gas cell 12 is a flow cell, and a sample gas is flowed through it.
  • This analyzer includes at least one calibration gas cell 14 in which a calibration gas is sealed.
  • the types of the calibration gas cell 14 include a wavelength calibration gas cell and a sensitivity calibration gas cell.
  • a calibration gas cell mounting mechanism (not shown in FIG. 1) is provided that can detachably place one of the calibration gas cells on the optical path 10.
  • the detection signal of the photodetector 8 is output to the arithmetic unit 16 which is an arithmetic processing circuit, a dedicated computer or a general-purpose personal computer.
  • the arithmetic device 16 includes a program for calculating the concentration of the measurement target component in the sample gas based on the detection signal of the photodetector 8.
  • control unit 6 and the arithmetic device 16 may be realized by one device or may be realized by another device.
  • the detection signal of the photodetector 8 is also output to the control unit 6.
  • FIG. 2A is a plan view showing in detail the vicinity of the calibration gas cell mounting mechanism.
  • the direction of the optical path 10 of the laser beam is changed by the folding mirror 18, condensed by the collector mirror 20, and guided to the photodetector 8.
  • the laser light is converted into parallel light by an optical system that exits the laser light source 2 and enters the measurement gas cell 12 and is introduced into the cell 12.
  • the laser light exiting the cell 12 is guided from the folding mirror 18 to the condensing mirror 20 while maintaining a parallel light state, and is condensed on the photodiode 8 which is a photodetector by the condensing mirror 20.
  • a calibration gas cell 14 is detachably mounted on the optical path 10 of the laser beam.
  • the calibration gas cell 14 can be disposed on the optical path between the folding mirror 18 and the condenser mirror 20. No vignetting occurs in the laser beam due to the insertion of the calibration gas cell 14, or there is no deviation of the condensing position on the photodetector 8, or the output of the photodetector 8 is constant or can be corrected even if there is a deviation. It is designed to be in good condition.
  • the window plate is provided with a wedge in order to avoid interference caused by the parallel window plates of the gas cells 12 and 14.
  • the support mechanism 22 as a calibration gas cell mounting mechanism has a portion opened at the top so that the calibration gas cell 14 can be fitted and mounted from above.
  • the optical path 10 is positioned so as to pass through the central portion of the gas cell 14.
  • FIG. 3 schematically shows a case where a plurality of calibration gas cells 14a to 14d are provided. Any one of the gas cells 14a to 14d is selected and attached to the support mechanism 22. When the calibration gas cell is not used, none of the gas cells 14 a to 14 d is attached to the support mechanism 22.
  • FIG. 4 shows another embodiment of the calibration gas cell mounting mechanism.
  • the cell holder 23 is rotatably supported by a rotating shaft 25 parallel to the optical axis 10 of the laser beam.
  • one through hole 15 and a plurality of calibration gas cells 14a to 14c are arranged on the circumference with the rotation shaft 25 as the center of the circle.
  • the through hole 15 or any of the gas cells 14a to 14c can be arranged on the optical axis 10.
  • the through hole 15 is positioned so as to be on the optical axis, and when performing wavelength calibration or sensitivity calibration, or when measuring a low concentration sample, any one of the predetermined gas cells 14a to 14c is set. It is arranged on the optical path 10.
  • the control unit 6 holds the wavelength variation data that holds the wavelength variation data indicating the relationship between the parameter that defines the driving condition of the laser light source 2 and the generated laser wavelength.
  • a holding unit 30 is provided.
  • the parameter that defines the driving condition is the temperature of the laser body, that is, the current value It flowing to the Peltier element of the temperature adjustment mechanism 3 built in the laser body.
  • the wavelength variation data indicates the relationship between the current value passed through the Peltier element and the generated laser wavelength.
  • the control unit 6 further includes a wavelength variation data calibration unit 32 that calibrates the wavelength variation data of the wavelength variation data holding unit 30 based on the wavelength of the absorption peak when the wavelength calibration gas cell is attached to the optical path 10 of the laser beam. I have.
  • the control unit 6 also includes an input unit 34 for setting a wavelength for measuring the measurement target component.
  • CO carbon monoxide
  • the control unit 6 sets the temperature of the laser body to a temperature that generates laser light of a specific wavelength suitable for measuring CO based on the wavelength variation data held in the wavelength variation data holding unit 30.
  • the current value It flowing to the Peltier element is controlled.
  • the drive current supplied from the laser drive circuit 4 to the laser light source 2 is always a constant reference current Io during measurement of the measurement target component and during calibration.
  • the measurement gas cell 12 When performing the wavelength calibration, the measurement gas cell 12 is not flowed into the measurement gas cell 12 and the measurement gas cell 12 is replaced with a gas that does not contain a measurement target component such as nitrogen gas.
  • a calibration gas cell As a calibration gas cell, a wavelength calibration gas cell in which CH 4 is enclosed is disposed on the optical path 10, and the temperature of the laser main body is changed by controlling the current value flowing from the control unit 6 to the Peltier element of the temperature adjustment mechanism 3. Go.
  • the wavelength of the laser beam generated from the laser light source 2 changes and wavelength scanning is performed.
  • the absorption spectrum shown in FIG. 6 is obtained.
  • CH 4 has a strong absorption line protruding in the vicinity of 4294 cm ⁇ 1 as indicated by an arrow in FIG.
  • the detailed peak wavelength (wave number) of the absorption line is well known.
  • the wavelength variation data calibrating unit 32 of the control unit 6 takes in the peak wavelength and the temperature of the laser body at that time, that is, the current value It 1 flowing to the Peltier element of the temperature adjusting mechanism 3 as the wavelength variation data.
  • a wavelength calibration gas cell in which H 2 O is sealed is disposed on the optical path 10, and the current value flowing from the control unit 6 to the Peltier element of the temperature control mechanism 3 is similarly controlled to control the laser body. Let's change the temperature. As a result, the wavelength of the laser beam generated from the laser light source 2 is changed and wavelength scanning is performed, and the absorption spectrum shown in FIG. 7 is obtained by this wavelength scanning.
  • H 2 O has a strong absorption line protruding in the vicinity of 4270 ⁇ 1 as indicated by an arrow in FIG. The detailed peak wavelength (wave number) of the absorption line is also well known.
  • the wavelength variation data calibrating unit 32 of the control unit 6 captures the peak wavelength and the temperature of the laser body at that time, that is, the current value It 2 flowing to the Peltier element of the temperature adjusting mechanism 3 as the wavelength variation data.
  • the wavelength variation data calibration unit 32 calibrates the wavelength variation data held in the wavelength variation data holding unit 30 by using the two parameters.
  • the corrected wavelength variation data is illustrated in FIG.
  • wavelength calibration may be performed using three or more peak wavelengths.
  • the control unit 6 When a wavelength (wave number) for measuring the measurement target component is input from the input unit 34 based on the calibrated wavelength variation data, the control unit 6 is set so that the laser body temperature for generating laser light of that wavelength is obtained. Thus, the current value It flowing to the Peltier element of the temperature adjustment mechanism 3 is controlled.
  • CO has nine characteristic absorption lines in the wave number 4270cm -1 as shown in FIG. 9 to 4300cm -1.
  • the CO gas concentration can be measured with any of the absorption lines, but since there are many absorption lines of CH 4 and H 2 O in the vicinity of this frequency, the noise due to the interference of the absorption lines cannot be ignored and the absorption is less affected by interference. It is necessary to select the line well.
  • the control unit 6 controls the wavelength of the laser light generated from the laser light source 2 based on the calibrated wavelength variation data. Is done.
  • Sensitivity calibration is calibration of calibration curve data for converting measured absorbance into a concentration value.
  • the arithmetic device 16 includes a calibration curve data holding unit 40 that holds calibration curve data for calculating a measurement target component concentration, and a sensitivity calibration gas cell mounted on the optical path 10 of the laser beam.
  • the calibration curve data calibration unit 42 calibrates the calibration curve data of the calibration curve data holding unit 40 according to the absorbance at that time.
  • the wavelength of the laser light generated from the laser light source 2 is fixed to a specific wavelength for measuring the measurement target component.
  • the measurement gas cell 12 is not flowed into the measurement gas cell 12, but the measurement gas cell 12 is replaced with a gas that does not contain a measurement target component such as nitrogen gas. It is assumed that the calibration curve data holding unit 40 holds calibration curve data indicated as Ao in FIG.
  • a sensitivity calibration gas cell in which CO as a measurement target component is sealed at a known concentration C 1 is arranged on the optical path 10 to measure the absorbance Ab 1 .
  • a sensitivity calibration gas cell in which CO is sealed at a known concentration C 2 is arranged on the optical path 10 as the sensitivity calibration gas cell 14 and the absorbance Ab 2 is measured.
  • the calibration curve data calibration unit 42 uses the obtained absorbances Ab 1 and Ab 2 at the two CO concentrations C 1 and C 2 as the calibration curve data held in the calibration curve data holding unit 40 in FIG. Calibrate as shown in 1 .
  • the sensitivity calibration may be performed using three or more gas cells for sensitivity calibration with different concentrations, or the sensitivity calibration may be performed with one gas cell for sensitivity calibration assuming that the calibration curve passes through the origin. .
  • the sensitivity calibration gas cell 14 When measuring the CO concentration of the sample gas, the sensitivity calibration gas cell 14 is removed from the optical path 10, the sample gas is flowed into the measurement gas cell 12, and the absorbance Ab is measured.
  • the computing device 16 calculates the concentration by applying the calibrated calibration curve data to the measured absorbance Ab.
  • a sensitivity calibration gas cell 14 in which a measurement target component having an appropriate known concentration is sealed is arranged on the optical path 10 of the laser beam even when measuring the sample gas.
  • the component to be measured is CO
  • the CO concentration enclosed in the sensitivity calibration gas cell is, for example, 1 ppm. It is assumed that the absorbance measurement value by the sensitivity calibration gas cell 14 is Abo without flowing the sample gas into the measurement gas cell 12.
  • the absorbance measurement value with respect to the concentration of the measurement target component in the sample gas is indicated by Bo in FIG. To change.
  • the concentration of the measurement target component is a low concentration close to 0 with the absorbance Ab 1 , the absorption peak becomes small, the distinction from the background becomes unclear, and the wavelength drift causes Accurate concentration measurement cannot be performed.
  • the concentration of the measurement target component is as low as 0 having the absorbance Ab 1.
  • the absorbance Ab 1 ′ obtained by adding only Abo is detected as the absorbance measurement value, it is possible to perform measurement with a sufficient S / N ratio for correct concentration measurement without losing sight of the absorption peak. become able to.
  • the arithmetic unit 16 includes an absorbance correction unit 44 as shown in FIG.
  • the absorbance correction unit 44 calculates the concentration based on the calibration curve data after performing an operation of subtracting the absorbance Abo from the sensitivity calibration gas cell from the absorbance Ab 1 ′ obtained from the photodetector 8.
  • the component to be measured is CO, and CH 4 and H 2 O are taken up as gases sealed in the wavelength calibration gas cell.
  • this is an example, and the present invention can be applied to other gases. Needless to say.

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Abstract

A gas analyzing apparatus for laser absorption spectroscopy measurement includes a laser light source to generate laser beam with a specific wavelength absorbed by a component being measured in sample gas, a laser light source drive controller to control driving of the laser light source, an optical detector arranged at a location where the laser beam is received, a gas cell for measurement of the sample gas which is arranged on an optical path of the laser beam going from the laser light source to the optical detector, and a computing unit to calculate a concentration of the component being measured in the sample gas in accordance with a detection signal of the optical detector. Further, the gas analyzing apparatus has at least one calibration gas cell where calibration gas is filled with, and a calibration gas cell mounting mechanism capable of locating one of the calibration gas cells in a removable manner on the optical path of the laser beam.

Description

校正用ガスセルを搭載したガス分析装置Gas analyzer with calibration gas cell
　本発明はレーザ吸収分光技術を使ったガス分析装置に関する。 The present invention relates to a gas analyzer using laser absorption spectroscopy.
　レーザ吸収分光を用いたガス計測を行う場合、基本的にはランバート・ベールの法則に従って、論理的に濃度を求めることが可能である。しかし、光学調整には限界があり、理論と完全に一致させるのは困難である。現実的には、ゼロガスや既知濃度のガスを使って、検量線を作成して、吸光度を濃度に換算するのが一般的である。 When performing gas measurement using laser absorption spectroscopy, it is basically possible to determine the concentration logically according to Lambert-Beer's law. However, there is a limit to optical adjustment, and it is difficult to completely match the theory. In practice, it is common to create a calibration curve using zero gas or a gas with a known concentration and convert the absorbance to the concentration.
　その際、計測用ガスセルに校正用ガスを導入して、その出力から感度校正を行っている。他の方法では、別の光学系、校正用ガスセル及び光検出器を常に設けておき、測定光としてのレーザ光の一部をハーフミラーで分離して取り出して校正用ガスセルに導くことによって校正値をモニタする機能をもたせている（特許文献１参照。）。
特開２００５－１０６５４６号公報 At that time, a calibration gas is introduced into the measurement gas cell, and sensitivity calibration is performed from the output. In another method, another optical system, a calibration gas cell, and a photodetector are always provided, and a calibration value is obtained by separating a part of the laser beam as measurement light by a half mirror and guiding it to the calibration gas cell. (See Patent Document 1).
JP 2005-106546 A
　計測用ガスセルを用いた校正を行う場合、校正を行う度に計測用ガスセルに校正用のガスを導入する必要がある。そのためには特別なガス配管及び切替えバルブ等の流路構成をもつ必要がある。さらに校正用のガスも保持しなければならない。そのような装置構成は複雑化し、かつ大型化する。また、校正用ガスが計測用ガスセルのための配管内、バルブ又は計測用ガスセル自体にも吸着し、又は停留することもあるため、測定精度上にも問題がある。 When performing calibration using a measurement gas cell, it is necessary to introduce a calibration gas into the measurement gas cell each time calibration is performed. For this purpose, it is necessary to have a special gas pipe and a flow path configuration such as a switching valve. In addition, a calibration gas must be retained. Such a device configuration is complicated and large. Further, since the calibration gas may be adsorbed or stopped in the piping for the measurement gas cell, the valve or the measurement gas cell itself, there is a problem in measurement accuracy.
　校正用ガスセルを常に備えた分析装置は、常に校正値をモニタリングできるという利点をもつ。しかし、ハーフミラーによって計測用ガスセルに利用できるレーザ光の光量が弱くなるので、計測用光検出器でのＳ／Ｎ（信号対ノイズ）比が低下する。さらに計測用ガスセルを透過した光を検出する計測用光検出器のほかにモニタ用光検出器をもつため、そのことが両光検出器の間の感度及びリニアリティなどの特性を調整する必要を増やし、装置の複雑化も招く。 An analyzer that always has a calibration gas cell has the advantage that the calibration value can always be monitored. However, since the amount of laser light that can be used for the measurement gas cell is weakened by the half mirror, the S / N (signal-to-noise) ratio in the measurement photodetector decreases. In addition to the measurement photodetector that detects the light that has passed through the measurement gas cell, it has a monitor photodetector, which increases the need to adjust characteristics such as sensitivity and linearity between the two photodetectors. Also, the apparatus becomes complicated.
　本発明は、レーザ吸収分光測定のための分析装置において、計測用ガスセルに校正用ガスを導入する必要をなくすとともに、光検出器を余分に設ける必要もなくすことを目的とするものである。 An object of the present invention is to eliminate the need to introduce a calibration gas into a measurement gas cell and eliminate the need to provide an extra photodetector in an analyzer for laser absorption spectroscopy measurement.
　本発明では、これらの問題を解決するために、必要なときにだけ、光路上に校正用ガスセルを挿入できるようにした。 In the present invention, in order to solve these problems, the calibration gas cell can be inserted into the optical path only when necessary.
　すなわち、本発明の分析装置は、試料気体中の測定対象成分により吸収される特定波長の測定光としてのレーザ光を発生するレーザ光源と、レーザ光源の駆動を制御するレーザ光源駆動制御装置と、レーザ光を受光する位置に配置された光検出器と、レーザ光源から光検出器に至るレーザ光の光路上に配置された試料気体の計測用ガスセルと、校正用ガスが封入された少なくとも１つの校正用ガスセルと、校正用ガスセルのうちの１つをレーザ光の光路上に着脱可能に配置することのできる校正用ガスセル装着機構と、光検出器の検出信号に基づいて試料気体中の測定対象成分濃度を算出する演算装置と、を備えている。 That is, the analyzer of the present invention includes a laser light source that generates laser light as measurement light having a specific wavelength absorbed by a measurement target component in a sample gas, a laser light source drive control device that controls driving of the laser light source, A photodetector arranged at a position for receiving the laser beam; a gas cell for measuring a sample gas arranged on the optical path of the laser beam from the laser light source to the photodetector; and at least one in which a calibration gas is enclosed Calibration gas cell, calibration gas cell mounting mechanism capable of detachably placing one of the calibration gas cells on the optical path of the laser beam, and a measurement target in the sample gas based on the detection signal of the photodetector And an arithmetic unit for calculating the component concentration.
　以下の説明において、波長を具体的に示すときに波長に替えて波数を用いる。波数は波長に対応しているので、本発明では「波長」は「波数」を含む概念として使用している。 In the following description, the wave number is used instead of the wavelength when specifically indicating the wavelength. Since the wave number corresponds to the wavelength, “wavelength” is used as a concept including “wave number” in the present invention.
　校正用ガスセルを別にもつことで、計測用ガスセルにガスを導入することも、校正用のガスボンベをもつことも必要がなくなるので、校正作業が簡素化し装置構成が複雑化しない。 By having a gas cell for calibration separately, it is not necessary to introduce gas into the gas cell for measurement or to have a gas cylinder for calibration, so that the calibration work is simplified and the apparatus configuration is not complicated.
　また、ガス計測に使用する光路上に校正用ガスセルを着脱可能に挿入するため、光学系に新たな部品を追加する必要がない。またハーフミラーによって計測用のレーザ光を分離することもないので、レーザ光の光量を維持することができる。さらに、計測用の光検出器を用いて校正を行うので精度の高い校正を実現することができる。 Also, since the calibration gas cell is detachably inserted into the optical path used for gas measurement, it is not necessary to add new parts to the optical system. Further, since the laser beam for measurement is not separated by the half mirror, the light amount of the laser beam can be maintained. Furthermore, since calibration is performed using a photo detector for measurement, highly accurate calibration can be realized.
　校正用ガスセルは、ガス種、濃度、圧力などのパラメータを変えることで様々が仕様のものを作製可能で、より高度な校正を実現できる手段となる。 The gas cell for calibration can be manufactured with various specifications by changing parameters such as gas type, concentration, pressure, etc., and it is a means to realize more advanced calibration.
　レーザ光源としては単一波長の光のみを発生するレーザダイオードとすることもできるが、測定対象を広げたり、分析対象に汎用性をもたせたり、あるいはＳ／Ｎ比を向上させるための手段として、波長変更可能なレーザ光源を使用することができる。レーザ光源には発振スペクトル線幅が細いＤＦＢレーザ（Distributed FeedBack Laser：分布帰還型レーザ）ダイオードを使用することが一般的であるが、同様のスペックを達成できるレーザ光源であればその種類は問わない。波長変更可能なレーザ光源を使用した場合は、レーザ光源駆動制御装置は測定対象成分測定時には特定波長のレーザ光を発生するようにレーザ光源の駆動を制御する。 As a laser light source, it can be a laser diode that generates only light of a single wavelength, but as a means for expanding the measurement object, making the analysis object versatile, or improving the S / N ratio, A laser light source capable of changing the wavelength can be used. As a laser light source, it is common to use a DFB laser (Distributed FeedBack が Laser) diode having a narrow oscillation spectrum line width, but any kind of laser light source can be used as long as it can achieve the same specifications. . When a laser light source capable of changing the wavelength is used, the laser light source drive control device controls the drive of the laser light source so as to generate laser light having a specific wavelength when measuring the measurement target component.
　波長可変レーザ光源では駆動電流やレーザ本体の温度といったパラメータを制御することにより発生するレーザ光の波長を調節することができる。そのため、レーザ光源駆動制御装置は発生するレーザ光の波長とパラメータとの関係を示す波長変動データを保持する波長変動データ保持部を備えていることが好ましく、測定対象成分測定時にはレーザ光源駆動制御装置は保持している波長変動データに基づいてレーザ光源が特定波長のレーザ光を発生するようにレーザ光源の駆動を制御する。 In the wavelength tunable laser light source, the wavelength of the laser beam generated can be adjusted by controlling parameters such as the drive current and the temperature of the laser body. For this reason, the laser light source drive control device preferably includes a wavelength variation data holding unit that holds wavelength variation data indicating the relationship between the wavelength of the generated laser light and the parameters. Controls the driving of the laser light source so that the laser light source generates laser light of a specific wavelength based on the held wavelength variation data.
　波長可変レーザ光源の一例として、レーザ本体の温度を調節する温度調節機構を備えてレーザ本体の温度により発生レーザ波長を変化させうるものを使用することができる。その場合、レーザ光源駆動制御装置はレーザ光源を駆動するためのレーザ本体への一定の基準電流と、レーザ本体の温度を調節するための温度調節機構への温度制御用電流とを供給するように制御されるのが好ましい。波長可変レーザ光源からの発生レーザ波長を固定するときはレーザ本体の温度が一定になるように温度調節機構への電流供給が制御され、発生レーザ波長を変化させるときはレーザ本体の温度が変化するように温度調節機構への電流供給が制御される。 As an example of the wavelength tunable laser light source, it is possible to use a temperature adjusting mechanism that adjusts the temperature of the laser body and that can change the generated laser wavelength depending on the temperature of the laser body. In this case, the laser light source drive control device supplies a constant reference current to the laser body for driving the laser light source and a temperature control current to the temperature adjustment mechanism for adjusting the temperature of the laser body. It is preferably controlled. When the generated laser wavelength from the wavelength tunable laser light source is fixed, the current supply to the temperature adjustment mechanism is controlled so that the temperature of the laser main body becomes constant, and when the generated laser wavelength is changed, the temperature of the laser main body changes. Thus, the current supply to the temperature adjustment mechanism is controlled.
　波長可変レーザ光源を使用して特定波長のレーザ光を発生させる場合、レーザ光源の駆動条件を正確に設定する必要があるので、駆動条件設定の基になる波長変動データを必要に応じて、又は任意の時に校正できるようになっていることが好ましい。分光器を使用すれば出力波長を正確に調整することができるが、本発明では分光器を使用しないでレーザ波長を正確に設定できるようにする。そのために、基準となるピーク波長を用いてレーザ本体温度などのパラメータと発生レーザ波長との関係から波長変動データを校正する。 When laser light having a specific wavelength is generated using a wavelength tunable laser light source, it is necessary to accurately set the driving condition of the laser light source. It is preferable that calibration can be performed at any time. If the spectroscope is used, the output wavelength can be adjusted accurately. However, in the present invention, the laser wavelength can be set accurately without using the spectroscope. For this purpose, the wavelength fluctuation data is calibrated from the relationship between the generated laser wavelength and parameters such as the laser body temperature using the reference peak wavelength.
　ここで、本発明の好ましい一形態として、校正用ガスセルとして既知の吸収ピーク波長をもつガスが封入された波長校正用ガスセルを含む。その場合、レーザ光源駆動制御装置は波長校正用ガスセルが光路に装着されたときの吸収ピークの波長を基にして波長変動データを校正する波長変動データ校正部を備えていることが好ましい。 Here, a preferred embodiment of the present invention includes a wavelength calibration gas cell in which a gas having a known absorption peak wavelength is enclosed as a calibration gas cell. In this case, the laser light source drive control device preferably includes a wavelength variation data calibration unit that calibrates wavelength variation data based on the wavelength of the absorption peak when the wavelength calibration gas cell is attached to the optical path.
　波長校正では複数の吸収ピークの波長を使用することにより、より精密に校正することができるようになる。 In wavelength calibration, it becomes possible to calibrate more precisely by using the wavelengths of multiple absorption peaks.
　そのような複数の吸収ピークは１つの波長校正用ガスセルから発生するものを使用してもよい。波長校正に使用する吸収ピークは他の吸収ピークに比べて強度が大きく急峻なものがよい。１つの波長校正用ガスセルから発生する吸収ピークにそのような適当なものが複数含まれていれば、それらを使用することができる。 Such a plurality of absorption peaks may be generated from one wavelength calibration gas cell. The absorption peak used for wavelength calibration should have a large and sharp intensity compared to other absorption peaks. If a plurality of such appropriate peaks are included in the absorption peak generated from one wavelength calibration gas cell, they can be used.
　しかし、１つの波長校正用ガスセルから発生する適当な吸収ピークが１つである場合は、異なるガスが封入された複数の波長校正用ガスセルを使うのが好ましい。その場合、例えば、そのような波長校正用ガスセルとして、測定対象成分を測定するための特定波長よりも長波長側の吸収ピーク波長をもつガスが封入された第１の波長校正用ガスセルと、特定波長よりも短波長側の吸収ピーク波長をもつガスが封入された第２の波長校正用ガスセルを含むものとするのが好ましい。 However, when there is one appropriate absorption peak generated from one wavelength calibration gas cell, it is preferable to use a plurality of wavelength calibration gas cells in which different gases are sealed. In that case, for example, as such a wavelength calibration gas cell, a first wavelength calibration gas cell in which a gas having an absorption peak wavelength longer than a specific wavelength for measuring a measurement target component is enclosed, and a specific It is preferable to include a second wavelength calibration gas cell in which a gas having an absorption peak wavelength shorter than the wavelength is enclosed.
　波長校正を行うことによる他の利点は、干渉の影響を最小限にとどめるような最適な波長のレーザ光が発生するようにレーザ装置を駆動できることである。 Another advantage of performing wavelength calibration is that the laser device can be driven so as to generate laser light with an optimum wavelength that minimizes the influence of interference.
　他の１つの校正は検量線データを校正する感度校正である。そのため、校正用ガスセルとして互いに異なる既知濃度の測定対象成分が封入された少なくとも２個の感度校正用ガスセルを含む。この場合、演算装置は測定対象成分濃度を算出するための検量線データを保持する検量線データ保持部と、感度校正用ガスセルがレーザ光の光路に装着されたときの吸光度により検量線データ保持部の検量線データを校正する検量線データ校正部を備えている。 Another calibration is sensitivity calibration for calibrating calibration curve data. Therefore, the calibration gas cell includes at least two sensitivity calibration gas cells in which measurement target components having different known concentrations are sealed. In this case, the computing device has a calibration curve data holding unit for holding calibration curve data for calculating the concentration of the measurement target component, and a calibration curve data holding unit based on the absorbance when the sensitivity calibration gas cell is mounted in the optical path of the laser beam. A calibration curve data calibration unit for calibrating the calibration curve data.
　感度校正用ガスセルを使用する他の利点は、低濃度試料測定時のＳ／Ｎ比の改良を挙げることができる。吸光度を測定する場合、試料気体中の測定対象成分の濃度が低下してくるにしたがい、バックグラウンドとの区別が不明瞭になり、装置の不安定性などを理由にレーザ光源の波長ドリフトなどが起こると正しい吸収ピークを見つけ難くなり、Ｓ／Ｎ比が低下して測定精度が低下してくる。そこで、好ましい形態として、感度校正用ガスセルは試料気体測定時にもレーザ光の光路上に配置されるものとする。その場合、演算装置は光検出器から求められる吸光度から試料気体測定時にレーザ光の光路上に配置された感度校正用ガスセルによる吸光度を引く吸光度修正部を備える。例えば、感度校正用ガスセルとして測定対象成分を１ｐｐｍの濃度で封入されたものをレーザ光の光路上に配置して試料気体の測定を行うと、仮に試料気体の測定対象成分濃度が０に近づいていっても光検出器は常に濃度１ｐｐｍ以上の測定対象成分を透過したレーザ光を検出することになり、バックグラウンドに対してピーク位置が明瞭となり、Ｓ／Ｎ比の低下を抑えることができるようになる。 Other advantages of using the sensitivity calibration gas cell include an improvement in the S / N ratio when measuring a low concentration sample. When measuring the absorbance, as the concentration of the component to be measured in the sample gas decreases, the distinction from the background becomes unclear and wavelength drift of the laser light source occurs due to instability of the device. Thus, it is difficult to find a correct absorption peak, and the S / N ratio is lowered and the measurement accuracy is lowered. Therefore, as a preferred embodiment, the sensitivity calibration gas cell is arranged on the optical path of the laser beam even when measuring the sample gas. In this case, the arithmetic unit includes an absorbance correction unit that subtracts the absorbance of the sensitivity calibration gas cell arranged on the optical path of the laser beam when measuring the sample gas from the absorbance obtained from the photodetector. For example, when a sample gas is measured by placing a gas cell for sensitivity calibration in which a measurement target component is sealed at a concentration of 1 ppm on the optical path of a laser beam, the measurement target component concentration of the sample gas approaches zero. Even so, the photodetector will always detect laser light that has passed through the component to be measured with a concentration of 1 ppm or more, and the peak position will be clear with respect to the background, so that the S / N ratio can be prevented from decreasing. become.
　本発明を用いることで、レーザ吸収分光分析において、必要に応じて複数のガス吸収線を用いた波長校正、干渉ガスの影響を少なくするような測定波長の正確な設定、又は検量線データの校正ができるなど、多様な校正ができるようになり、より精度の高いレーザ吸収分光によるガス計測が可能になる。 By using the present invention, in laser absorption spectroscopic analysis, wavelength calibration using a plurality of gas absorption lines as necessary, accurate setting of measurement wavelength to reduce the influence of interference gas, or calibration of calibration curve data Various calibrations can be performed, and gas measurement by laser absorption spectroscopy with higher accuracy becomes possible.
一実施例を概略的に示すブロック図である。It is a block diagram which shows one Example schematically.
同実施例における校正用ガスセル装着機構の付近を詳細に示した平面図である。It is the top view which showed the vicinity of the gas cell mounting mechanism for calibration in the same Example in detail.
校正用ガスセル装着機構としての支持機構を示す正面図である。It is a front view which shows the support mechanism as a gas cell mounting mechanism for calibration.
複数の校正用ガスセルを備えている校正用ガスセル装着機構の一例を模式的に示す概略構成図である。It is a schematic block diagram which shows typically an example of the calibration gas cell mounting mechanism provided with the several calibration gas cell.
複数の校正用ガスセルを備えている校正用ガスセル装着機構の他の例を模式的に示す概略構成図である。It is a schematic block diagram which shows typically the other example of the calibration gas cell mounting mechanism provided with the several gas cell for a calibration.
波長校正を可能にする制御部を示すブロック図である。It is a block diagram which shows the control part which enables wavelength calibration.
ＣＨ4が封入された波長校正用ガスセルによる吸収スペクトルを示すグラフである。CH 4 is a graph showing the absorption spectra due to encapsulated wavelength calibration gas cell.
Ｈ2Ｏが封入された波長校正用ガスセルによる吸収スペクトルを示すグラフである。H 2 O is a graph showing the absorption spectra due to encapsulated wavelength calibration gas cell.
校正された波長変動データを示すグラフである。It is a graph which shows the calibrated wavelength variation data.
ＣＯの吸収スペクトルを示すグラフである。It is a graph which shows the absorption spectrum of CO.
感度校正を可能にする演算装置を示すブロック図である。It is a block diagram which shows the arithmetic unit which enables sensitivity calibration.
検量線データの校正を示すグラフである。It is a graph which shows calibration of calibration curve data.
感度を高める測定方法を示すグラフである。It is a graph which shows the measuring method which raises a sensitivity.
符号の説明Explanation of symbols
　　　２　　　レーザ光源
　　　３　　　温度調節機構
　　　６　　　制御部
　　　４　　　レーザ駆動回路
　　　８　　　光検出器
　　１０　　　レーザ光の光路
　　１２　　　試料気体計測用ガスセル
　　１４，１４ａ～１４ｄ　　　校正用ガスセル
　　１６　　　演算装置
　　２２　　　校正用ガスセル装着機構の支持機構
　　２３　　　セルホルダ
　　１５　　　貫通穴
　　３０　　　波長変動データ保持部
　　３２　　　波長変動データ校正部
　　４０　　　検量線データ保持部
　　４２　　　検量線データ校正部
　　４４　　　吸光度集西部 DESCRIPTION OF SYMBOLS 2 Laser light source 3 Temperature control mechanism 6 Control part 4 Laser drive circuit 8 Photodetector 10 Optical path of laser beam 12 Sample gas measurement gas cell 14, 14a-14d Calibration gas cell 16 Arithmetic device 22 Support mechanism of calibration gas cell mounting mechanism 23 Cell holder 15 Through hole 30 Wavelength variation data holding unit 32 Wavelength variation data calibration unit 40 Calibration curve data holding unit 42 Calibration curve data calibration unit 44 Absorbance collection unit
　図１は一実施例の分析装置を概略的に表したものである。試料気体中の測定対象成分により吸収される特定波長の測定光としてのレーザ光を発生するレーザ光源２は、この実施例では波長変更可能なＤＦＢレーザダイオードである。波長変更可能なレーザ光源-の種類は特に限定されるものではない。レーザ光源２はレーザ本体の温度を調節するためにペルチェ素子からなる温度調節機構３を内蔵している。 FIG. 1 schematically shows an analyzer according to one embodiment. In this embodiment, the laser light source 2 that generates laser light as measurement light having a specific wavelength that is absorbed by the measurement target component in the sample gas is a DFB laser diode that can change the wavelength. The type of the laser light source that can change the wavelength is not particularly limited. The laser light source 2 incorporates a temperature adjustment mechanism 3 composed of a Peltier element in order to adjust the temperature of the laser body.
　レーザ光源２の駆動を制御するレーザ光源駆動制御装置として、レーザ駆動回路４と演算処理回路又は専用コンピュータ又は汎用のパーソナルコンピュータにてなる制御部６を備えている。レーザ駆動回路４は制御部６からの制御信号によりレーザ光源２を駆動する駆動電流として一定の基準電流Ｉｏを供給する。制御部６はさらにレーザ光源２から発生するレーザ光の波長を調節するために温度調節機構３のペルチェ素子に対し温度制御用の電流Ｉｔを供給する。 As a laser light source drive control device that controls the drive of the laser light source 2, a laser drive circuit 4 and a control unit 6 comprising an arithmetic processing circuit, a dedicated computer, or a general-purpose personal computer are provided. The laser drive circuit 4 supplies a constant reference current Io as a drive current for driving the laser light source 2 by a control signal from the control unit 6. The controller 6 further supplies a current It for temperature control to the Peltier element of the temperature adjusting mechanism 3 in order to adjust the wavelength of the laser light generated from the laser light source 2.
　レーザ光源２から発生するレーザ光の波長は試料気体中の測定対象成分濃度を測定するときは吸光度を測定しようとする特定波長になるように、あるいは特定波長を挟むように波長が走査されるように温度制御用電流Ｉｔが制御される。そのときレーザ本体の温度は特定波長に対応した一定温度に調節される。試料気体又は校正用ガスセル中のガスの吸収スペクトルを測定するときはレーザ光源２から発生するレーザ光の波長を走査させる。そのために、レーザ本体の温度が変化していくように制御部６により温度制御用電流Ｉｔが制御される。 The wavelength of the laser light generated from the laser light source 2 is scanned so as to be a specific wavelength for measuring the absorbance when the concentration of the measurement target component in the sample gas is measured or sandwiching the specific wavelength. Thus, the temperature control current It is controlled. At that time, the temperature of the laser body is adjusted to a constant temperature corresponding to the specific wavelength. When measuring the absorption spectrum of the sample gas or the gas in the calibration gas cell, the wavelength of the laser beam generated from the laser light source 2 is scanned. For this purpose, the temperature control current It is controlled by the controller 6 so that the temperature of the laser body changes.
　レーザ光源２から発生する測定用レーザ光を受光する位置には光検出器８が配置されている。光検出器８はフォトダイオード又は光電子増倍管である。 A photodetector 8 is disposed at a position where the measurement laser beam generated from the laser light source 2 is received. The photodetector 8 is a photodiode or a photomultiplier tube.
　レーザ光源２から光検出器８に至る測定用レーザ光の光路１０上には試料気体計測用ガスセル１２が配置されている。計測用ガスセル１２はフローセルであり、試料気体が流される。 A gas cell 12 for measuring a sample gas is disposed on the optical path 10 of the laser beam for measurement from the laser light source 2 to the photodetector 8. The measurement gas cell 12 is a flow cell, and a sample gas is flowed through it.
　この分析装置は校正用ガスが封入された少なくとも１つの校正用ガスセル１４を備えている。校正用ガスセル１４の種類としては波長校正用ガスセルと感度校正用ガスセルがある。そして、校正用ガスセルのうちの１つを光路１０上に着脱可能に配置することのできる校正用ガスセル装着機構（図１では図示を省略している。）が設けられている。 This analyzer includes at least one calibration gas cell 14 in which a calibration gas is sealed. The types of the calibration gas cell 14 include a wavelength calibration gas cell and a sensitivity calibration gas cell. A calibration gas cell mounting mechanism (not shown in FIG. 1) is provided that can detachably place one of the calibration gas cells on the optical path 10.
　光検出器８の検出信号は演算処理回路、専用コンピュータ又は汎用のパーソナルコンピュータにてなる演算装置１６に出力される。演算装置１６は光検出器８の検出信号に基づいて試料気体中の測定対象成分濃度を算出するプログラムを備えている。 The detection signal of the photodetector 8 is output to the arithmetic unit 16 which is an arithmetic processing circuit, a dedicated computer or a general-purpose personal computer. The arithmetic device 16 includes a program for calculating the concentration of the measurement target component in the sample gas based on the detection signal of the photodetector 8.
　制御部６と演算装置１６は１つの装置により実現してもよく、別の装置により実現してもよい。 The control unit 6 and the arithmetic device 16 may be realized by one device or may be realized by another device.
　レーザ光源２から発生するレーザ光の波長を校正する際には光検出器８の検出信号は制御部６にも出力される。 When the wavelength of the laser beam generated from the laser light source 2 is calibrated, the detection signal of the photodetector 8 is also output to the control unit 6.
　図２Ａは校正用ガスセル装着機構の付近を詳細に示した平面図である。計測用ガスセル１２から出たレーザ光を光検出器８に導くために、レーザ光の光路１０が折返しミラー１８で方向が変えられ、集光ミラー２０で集光されて光検出器８へ導かれる。レーザ光はレーザ光源２から出て計測用ガスセル１２に入射させる光学系により平行光とされてセル１２に導入される。セル１２を出たレーザ光は平行光の状態を保ったまま折返しミラー１８から集光ミラー２０まで導かれ、集光ミラー２０で光検出器であるフォトダイオード８上に集光される。レーザ光の光路１０上には校正用ガスセル１４が着脱可能に装着できるようになっている。この例では折返しミラー１８と集光ミラー２０の間の光路上に校正用ガスセル１４が配置できるようになっている。校正用ガスセル１４の挿入によってレーザ光にケラレが発生したり、光検出器８上の集光位置のズレが起こらない、またはズレがあっても光検出器８の出力が一定、あるいは補正が可能な状態になるよう設計されている。計測用ガスセル１２と校正用ガスセル１４が配置されている光路では、ガスセル１２，１４の窓板が平行になることで干渉が起こるのを避けるために、窓板にはウェッジが付いている。 FIG. 2A is a plan view showing in detail the vicinity of the calibration gas cell mounting mechanism. In order to guide the laser beam emitted from the measurement gas cell 12 to the photodetector 8, the direction of the optical path 10 of the laser beam is changed by the folding mirror 18, condensed by the collector mirror 20, and guided to the photodetector 8. . The laser light is converted into parallel light by an optical system that exits the laser light source 2 and enters the measurement gas cell 12 and is introduced into the cell 12. The laser light exiting the cell 12 is guided from the folding mirror 18 to the condensing mirror 20 while maintaining a parallel light state, and is condensed on the photodiode 8 which is a photodetector by the condensing mirror 20. A calibration gas cell 14 is detachably mounted on the optical path 10 of the laser beam. In this example, the calibration gas cell 14 can be disposed on the optical path between the folding mirror 18 and the condenser mirror 20. No vignetting occurs in the laser beam due to the insertion of the calibration gas cell 14, or there is no deviation of the condensing position on the photodetector 8, or the output of the photodetector 8 is constant or can be corrected even if there is a deviation. It is designed to be in good condition. In the optical path in which the measurement gas cell 12 and the calibration gas cell 14 are arranged, the window plate is provided with a wedge in order to avoid interference caused by the parallel window plates of the gas cells 12 and 14.
　校正用ガスセル装着機構としての支持機構２２は、図２Ｂに正面図が示されているように、校正用ガスセル１４を上方から嵌め込んで装着できるように上部に開口した部分をもち、その開口部にセル１４を装着すると光路１０がガスセル１４の中心部を透過するように位置決めされるようになっている。 As shown in the front view of FIG. 2B, the support mechanism 22 as a calibration gas cell mounting mechanism has a portion opened at the top so that the calibration gas cell 14 can be fitted and mounted from above. When the cell 14 is mounted, the optical path 10 is positioned so as to pass through the central portion of the gas cell 14.
　図３は複数の校正用ガスセル１４ａ～１４ｄを備えている場合を模式的に示したものである。ガスセル１４ａ～１４ｄはいずれかが選択されて支持機構２２に装着される。校正用ガスセルを使用しないときは、いずれのガスセル１４ａ～１４ｄも支持機構２２に装着されない。 FIG. 3 schematically shows a case where a plurality of calibration gas cells 14a to 14d are provided. Any one of the gas cells 14a to 14d is selected and attached to the support mechanism 22. When the calibration gas cell is not used, none of the gas cells 14 a to 14 d is attached to the support mechanism 22.
　図４は校正用ガスセル装着機構の他の実施例を示したものである。セルホルダ２３はレーザ光の光軸１０と平行な回転軸２５により回転可能に支持されている。セルホルダ２３はその回転軸２５を円の中心とする円周上に１つの貫通穴１５と、複数個の校正用ガスセル１４ａ～１４ｃが配置されている。セルホルダ２３を回転させることにより、貫通穴１５又はいずれかのガスセル１４ａ～１４ｃを光軸１０上に配置することができる。通常の試料気体の測定時は貫通穴１５が光軸上にくるように位置決めし、波長校正もしくは感度校正を行うとき、又は低濃度試料を測定するときに所定のガスセル１４ａ～１４ｃのいずれかを光路１０上に配置する。 FIG. 4 shows another embodiment of the calibration gas cell mounting mechanism. The cell holder 23 is rotatably supported by a rotating shaft 25 parallel to the optical axis 10 of the laser beam. In the cell holder 23, one through hole 15 and a plurality of calibration gas cells 14a to 14c are arranged on the circumference with the rotation shaft 25 as the center of the circle. By rotating the cell holder 23, the through hole 15 or any of the gas cells 14a to 14c can be arranged on the optical axis 10. When measuring a normal sample gas, the through hole 15 is positioned so as to be on the optical axis, and when performing wavelength calibration or sensitivity calibration, or when measuring a low concentration sample, any one of the predetermined gas cells 14a to 14c is set. It is arranged on the optical path 10.
　次に、図５から図９により波長校正について説明する。波長校正を可能にするために、図５に示されるように、制御部６はレーザ光源２の駆動条件を規定するパラメータと発生するレーザ波長との関係を示す波長変動データを保持する波長変動データ保持部３０を備えている。この例では駆動条件を規定するパラメータはレーザ本体の温度、すなわちレーザ本体に内蔵された温度調節機構３のペルチェ素子へ流す電流値Ｉｔである。波長変動データはペルチェ素子へ流す電流値と発生するレーザ波長との関係を示すものとなる。制御部６はさらに、波長校正用ガスセルがレーザ光の光路１０に装着されたときの吸収ピークの波長を基にして波長変動データ保持部３０の波長変動データを校正する波長変動データ校正部３２を備えている。制御部６には、測定対象成分を測定するための波長を設定するための入力部３４も備えている。 Next, wavelength calibration will be described with reference to FIGS. In order to enable the wavelength calibration, as shown in FIG. 5, the control unit 6 holds the wavelength variation data that holds the wavelength variation data indicating the relationship between the parameter that defines the driving condition of the laser light source 2 and the generated laser wavelength. A holding unit 30 is provided. In this example, the parameter that defines the driving condition is the temperature of the laser body, that is, the current value It flowing to the Peltier element of the temperature adjustment mechanism 3 built in the laser body. The wavelength variation data indicates the relationship between the current value passed through the Peltier element and the generated laser wavelength. The control unit 6 further includes a wavelength variation data calibration unit 32 that calibrates the wavelength variation data of the wavelength variation data holding unit 30 based on the wavelength of the absorption peak when the wavelength calibration gas cell is attached to the optical path 10 of the laser beam. I have. The control unit 6 also includes an input unit 34 for setting a wavelength for measuring the measurement target component.
　いま、試料気体中の一酸化炭素（ＣＯ）を測定対象成分とし、波長校正用ガスセルとしてメタン（ＣＨ4）が封入れたガスセルと水蒸気（Ｈ2Ｏ）が封入れたガスセルを用いるものとして説明する。 It is assumed that carbon monoxide (CO) in a sample gas is a measurement target component, and a gas cell in which methane (CH 4 ) is enclosed and a gas cell in which water vapor (H 2 O) is enclosed are used as wavelength calibration gas cells. To do.
　測定対象成分測定時には制御部６は波長変動データ保持部３０に保持している波長変動データに基づいて、レーザ本体の温度がＣＯを測定するのに適した特定波長のレーザ光を発生する温度になるようにペルチェ素子へ流す電流値Ｉｔを制御する。レーザ駆動回路４からレーザ光源２に供給される駆動電流は、測定対象成分測定時も校正時も、常に一定の基準電流Ｉｏである。 At the time of measuring the component to be measured, the control unit 6 sets the temperature of the laser body to a temperature that generates laser light of a specific wavelength suitable for measuring CO based on the wavelength variation data held in the wavelength variation data holding unit 30. Thus, the current value It flowing to the Peltier element is controlled. The drive current supplied from the laser drive circuit 4 to the laser light source 2 is always a constant reference current Io during measurement of the measurement target component and during calibration.
　波長校正を行うときは、計測用ガスセル１２には試料気体は流さないで計測用ガスセル１２中を窒素ガスなどの測定対象成分を含まないガスで置換しておく。校正用ガスセルとして、ＣＨ4が封入された波長校正用ガスセルを光路１０上に配置し、制御部６から温度調節機構３のペルチェ素子へ流す電流値を制御してレーザ本体の温度を変化させていく。これにより、レーザ光源２から発生するレーザ光の波長が変化して波長走査がなされる。この波長走査により、図６に示される吸収スペクトルが得られる。ＣＨ4は図６中に矢印で示されるように、４２９４ｃｍ-1付近に突出した強い吸収線をもっている。その吸収線の詳細なピーク波長（波数）はよく知られている。制御部６の波長変動データ校正部３２はそのピーク波長とそのときのレーザ本体の温度、すなわち温度調節機構３のペルチェ素子へ流す電流値Ｉｔ1を波長変動データとして取り込む。 When performing the wavelength calibration, the measurement gas cell 12 is not flowed into the measurement gas cell 12 and the measurement gas cell 12 is replaced with a gas that does not contain a measurement target component such as nitrogen gas. As a calibration gas cell, a wavelength calibration gas cell in which CH 4 is enclosed is disposed on the optical path 10, and the temperature of the laser main body is changed by controlling the current value flowing from the control unit 6 to the Peltier element of the temperature adjustment mechanism 3. Go. As a result, the wavelength of the laser beam generated from the laser light source 2 changes and wavelength scanning is performed. By this wavelength scanning, the absorption spectrum shown in FIG. 6 is obtained. CH 4 has a strong absorption line protruding in the vicinity of 4294 cm −1 as indicated by an arrow in FIG. The detailed peak wavelength (wave number) of the absorption line is well known. The wavelength variation data calibrating unit 32 of the control unit 6 takes in the peak wavelength and the temperature of the laser body at that time, that is, the current value It 1 flowing to the Peltier element of the temperature adjusting mechanism 3 as the wavelength variation data.
　次に校正用ガスセルとして、Ｈ2Ｏが封入された波長校正用ガスセルを光路１０上に配置し、同様にして制御部６から温度調節機構３のペルチェ素子へ流す電流値を制御してレーザ本体の温度を変化させていく。これにより、レーザ光源２から発生するレーザ光の波長が変化して波長走査がなされ、この波長走査により、図７に示される吸収スペクトルが得られる。Ｈ2Ｏは図７中に矢印で示されるように、４２７０-1付近に突出した強い吸収線をもっている。その吸収線の詳細なピーク波長（波数）もよく知られている。制御部６の波長変動データ校正部３２はそのピーク波長とそのときのレーザ本体の温度、すなわち温度調節機構３のペルチェ素子へ流す電流値Ｉｔ2を波長変動データとして取り込む。 Next, as a calibration gas cell, a wavelength calibration gas cell in which H 2 O is sealed is disposed on the optical path 10, and the current value flowing from the control unit 6 to the Peltier element of the temperature control mechanism 3 is similarly controlled to control the laser body. Let's change the temperature. As a result, the wavelength of the laser beam generated from the laser light source 2 is changed and wavelength scanning is performed, and the absorption spectrum shown in FIG. 7 is obtained by this wavelength scanning. H 2 O has a strong absorption line protruding in the vicinity of 4270 −1 as indicated by an arrow in FIG. The detailed peak wavelength (wave number) of the absorption line is also well known. The wavelength variation data calibrating unit 32 of the control unit 6 captures the peak wavelength and the temperature of the laser body at that time, that is, the current value It 2 flowing to the Peltier element of the temperature adjusting mechanism 3 as the wavelength variation data.
　このように２種類の校正用ガスセルによって２つの波長のレーザ光を発生するときの電流値Ｉｔ1，Ｉｔ2がパラメータとして得られる。波長変動データ校正部３２はその２つのパラメータにより波長変動データ保持部３０に保持されている波長変動データを校正する。校正された波長変動データを図示すると図８のようになる。もちろん、３つ以上のピーク波長を用いて波長校正を行ってもよい。 In this way, the current values It 1 and It 2 when two wavelengths of laser light are generated by the two types of calibration gas cells are obtained as parameters. The wavelength variation data calibration unit 32 calibrates the wavelength variation data held in the wavelength variation data holding unit 30 by using the two parameters. The corrected wavelength variation data is illustrated in FIG. Of course, wavelength calibration may be performed using three or more peak wavelengths.
　その校正された波長変動データに基づいて測定対象成分を測定するための波長（波数）を入力部３４から入力すると、その波長のレーザ光を発生するためのレーザ本体温度になるように制御部６により温度調節機構３のペルチェ素子へ流す電流値Ｉｔが制御される。 When a wavelength (wave number) for measuring the measurement target component is input from the input unit 34 based on the calibrated wavelength variation data, the control unit 6 is set so that the laser body temperature for generating laser light of that wavelength is obtained. Thus, the current value It flowing to the Peltier element of the temperature adjustment mechanism 3 is controlled.
　測定対象成分であるＣＯについて説明すると、ＣＯは図９に示されるように波数４２７０ｃｍ-1から４３００ｃｍ-1までに９本の特徴的な吸収線をもつ。いずれの吸収線でもＣＯガスの濃度は計測できるが、ＣＨ4、Ｈ2Ｏの吸収線もこの周波数近傍に多数存在するため、吸収線の干渉によるノイズが無視できず、干渉の影響の少ない吸収線をうまく選択する必要がある。そのような干渉の影響の少ない吸収線の波長（波数）を入力部３４から入力することにより、校正された波長変動データに基づいてレーザ光源２から発生するレーザ光の波長が制御部６により制御される。また、それらのＣＯの複数の吸収線のうちの何番目の吸収線を使って測定しているのかも正確に知ることが可能となる。このように、干渉の影響のあるガス種に対し、ＣＯの吸収線を使い分けることで、干渉の影響を最小限にとどめることが可能になる。 Referring to the measurement target component CO, CO has nine characteristic absorption lines in the wave number 4270cm -1 as shown in FIG. 9 to 4300cm -1. The CO gas concentration can be measured with any of the absorption lines, but since there are many absorption lines of CH 4 and H 2 O in the vicinity of this frequency, the noise due to the interference of the absorption lines cannot be ignored and the absorption is less affected by interference. It is necessary to select the line well. By inputting the wavelength (wave number) of such an absorption line that is less affected by interference from the input unit 34, the control unit 6 controls the wavelength of the laser light generated from the laser light source 2 based on the calibrated wavelength variation data. Is done. In addition, it is possible to accurately know the number of absorption lines among the plurality of absorption lines of CO. In this way, the influence of interference can be minimized by properly using the CO absorption line for the gas species that are affected by interference.
　次に感度校正について図１０と図１１を参照して説明する。感度校正とは測定された吸光度を濃度値に変換するための検量線データを校正することである。感度校正時は、校正用ガスセルとして互いに異なる既知濃度の測定対象成分が封入された少なくとも２個の感度校正用ガスセルを用いる。演算装置１６は、図１０に示されるように、測定対象成分濃度を算出するための検量線データを保持する検量線データ保持部４０と、感度校正用ガスセルがレーザ光の光路１０に装着されたときの吸光度により検量線データ保持部４０の検量線データを校正する検量線データ校正部４２を備えている。 Next, sensitivity calibration will be described with reference to FIGS. Sensitivity calibration is calibration of calibration curve data for converting measured absorbance into a concentration value. At the time of sensitivity calibration, at least two sensitivity calibration gas cells in which components to be measured having different known concentrations are sealed are used as calibration gas cells. As shown in FIG. 10, the arithmetic device 16 includes a calibration curve data holding unit 40 that holds calibration curve data for calculating a measurement target component concentration, and a sensitivity calibration gas cell mounted on the optical path 10 of the laser beam. The calibration curve data calibration unit 42 calibrates the calibration curve data of the calibration curve data holding unit 40 according to the absorbance at that time.
　感度校正を行う際、レーザ光源２から発生するレーザ光の波長はその測定対象成分を測定するための特定波長に固定しておく。感度校正を行うときは、計測用ガスセル１２には試料気体は流さないで計測用ガスセル１２中を窒素ガスなどの測定対象成分を含まないガスで置換しておく。検量線データ保持部４０には、図１１にＡｏとして示される検量線データが保持されているとする。 When performing sensitivity calibration, the wavelength of the laser light generated from the laser light source 2 is fixed to a specific wavelength for measuring the measurement target component. When performing sensitivity calibration, the measurement gas cell 12 is not flowed into the measurement gas cell 12, but the measurement gas cell 12 is replaced with a gas that does not contain a measurement target component such as nitrogen gas. It is assumed that the calibration curve data holding unit 40 holds calibration curve data indicated as Ao in FIG.
　感度校正用ガスセル１４として、測定対象成分のＣＯが既知の濃度Ｃ1で封入された感
度校正用ガスセルを光路１０上に配置して吸光度Ａｂ1を測定する。次に、感度校正用ガスセル１４としてＣＯが既知の濃度Ｃ2で封入された感度校正用ガスセルを光路１０上に配置して吸光度Ａｂ2を測定する。検量線データ校正部４２は得られた２つのＣＯ濃度Ｃ1，Ｃ2での吸光度Ａｂ1，Ａｂ2を用いて検量線データ保持部４０に保持されている検量線データを図１１中にＡ1で示されるように校正する。もちろん、３つ以上の濃度の異なる感度校正用ガスセルを使用して感度校正を行ってもよいし、検量線が原点を通ることを仮定して１つ感度校正用ガスセルで感度校正してもよい。 As the sensitivity calibration gas cell 14, a sensitivity calibration gas cell in which CO as a measurement target component is sealed at a known concentration C 1 is arranged on the optical path 10 to measure the absorbance Ab 1 . Next, a sensitivity calibration gas cell in which CO is sealed at a known concentration C 2 is arranged on the optical path 10 as the sensitivity calibration gas cell 14 and the absorbance Ab 2 is measured. The calibration curve data calibration unit 42 uses the obtained absorbances Ab 1 and Ab 2 at the two CO concentrations C 1 and C 2 as the calibration curve data held in the calibration curve data holding unit 40 in FIG. Calibrate as shown in 1 . Of course, the sensitivity calibration may be performed using three or more gas cells for sensitivity calibration with different concentrations, or the sensitivity calibration may be performed with one gas cell for sensitivity calibration assuming that the calibration curve passes through the origin. .
　試料気体のＣＯ濃度を測定するときは、感度校正用ガスセル１４を光路１０から除去し、計測用ガスセル１２に試料気体を流して、吸光度Ａｂを測定する。演算装置１６は測定された吸光度Ａｂに対して、校正された検量線データを適用して濃度を算出する。 When measuring the CO concentration of the sample gas, the sensitivity calibration gas cell 14 is removed from the optical path 10, the sample gas is flowed into the measurement gas cell 12, and the absorbance Ab is measured. The computing device 16 calculates the concentration by applying the calibrated calibration curve data to the measured absorbance Ab.
　感度校正用ガスセル１４を用いて低濃度の測定対象成分を測定する場合に、Ｓ／Ｎ比を向上させる形態を説明する。この場合は、試料気体測定時にもレーザ光の光路１０上に適当な既知濃度の測定対象成分が封入された感度校正用ガスセル１４が配置される。測定対象成分はこの場合はＣＯであり、その感度校正用ガスセルに封入されたＣＯ濃度は例えば１ｐｐｍであるとする。計測用ガスセル１２に試料気体を流さずに感度校正用ガスセル１４による吸光度測定値がＡｂｏであったとする。 A mode of improving the S / N ratio when measuring a low concentration measurement target component using the sensitivity calibration gas cell 14 will be described. In this case, a sensitivity calibration gas cell 14 in which a measurement target component having an appropriate known concentration is sealed is arranged on the optical path 10 of the laser beam even when measuring the sample gas. In this case, the component to be measured is CO, and the CO concentration enclosed in the sensitivity calibration gas cell is, for example, 1 ppm. It is assumed that the absorbance measurement value by the sensitivity calibration gas cell 14 is Abo without flowing the sample gas into the measurement gas cell 12.
　感度校正用ガスセル１４を光路１０上に配置せずに計測用ガスセル１２に試料気体を流して吸光度を測定すると、試料気体中の測定対象成分濃度に対する吸光度測定値は図１２のＢｏで示されるように変化する。そのような測定方法によれば、測定対象成分濃度が吸光度Ａｂ1をもつような０に近い低濃度の場合には、吸収ピークが小さくなり、バックグラウンドとの区別が不明瞭となり、波長ドリフトによって正確な濃度測定を行うことができなくなる。 When the sample gas is flowed into the measurement gas cell 12 without measuring the sensitivity calibration gas cell 14 on the optical path 10 and the absorbance is measured, the absorbance measurement value with respect to the concentration of the measurement target component in the sample gas is indicated by Bo in FIG. To change. According to such a measurement method, when the concentration of the measurement target component is a low concentration close to 0 with the absorbance Ab 1 , the absorption peak becomes small, the distinction from the background becomes unclear, and the wavelength drift causes Accurate concentration measurement cannot be performed.
　それに対し、この形態により感度校正用ガスセル１４を光路１０上に配置して計測用ガスセル１２に試料気体を流して吸光度を測定すると、測定対象成分濃度が吸光度Ａｂ1をもつような０に近い低濃度の場合であっても吸光度測定値としてはＡｂｏだけ加算された吸光度Ａｂ1'として検出されるので、吸収ピークを見失うことなく、正しい濃度測定に十分なＳ／Ｎ比で測定を行うことができるようになる。 On the other hand, when the sensitivity calibration gas cell 14 is arranged on the optical path 10 and the sample gas is flowed into the measurement gas cell 12 and the absorbance is measured according to this embodiment, the concentration of the measurement target component is as low as 0 having the absorbance Ab 1. Even in the case of the concentration, since the absorbance Ab 1 ′ obtained by adding only Abo is detected as the absorbance measurement value, it is possible to perform measurement with a sufficient S / N ratio for correct concentration measurement without losing sight of the absorption peak. become able to.
　この場合、演算装置１６は、図１０に示されているように、吸光度修正部４４を備えている。吸光度修正部４４は光検出器８から求められる吸光度Ａｂ1'から感度校正用ガスセルによる吸光度Ａｂｏを引く演算を行った後に検量線データに基づいて濃度を算出させる。 In this case, the arithmetic unit 16 includes an absorbance correction unit 44 as shown in FIG. The absorbance correction unit 44 calculates the concentration based on the calibration curve data after performing an operation of subtracting the absorbance Abo from the sensitivity calibration gas cell from the absorbance Ab 1 ′ obtained from the photodetector 8.
　上の説明では、測定対象成分をＣＯとし、波長校正用ガスセルに封入するガスとしてＣＨ4とＨ2Ｏを取りあげているが、これは一例であって、本発明は他のガスにも適用できることはいうまでもない。 In the above description, the component to be measured is CO, and CH 4 and H 2 O are taken up as gases sealed in the wavelength calibration gas cell. However, this is an example, and the present invention can be applied to other gases. Needless to say.

Claims (9)

  1. 　試料気体中の測定対象成分により吸収される特定波長の測定光としてのレーザ光を発生するレーザ光源と、
    　前記レーザ光源の駆動を制御するレーザ光源駆動制御装置と、
    　前記レーザ光を受光する位置に配置された光検出器と、
    　前記レーザ光源から光検出器に至るレーザ光の光路上に配置された試料気体の計測用ガスセルと、
    　校正用ガスが封入された少なくとも１つの校正用ガスセルと、
    　前記校正用ガスセルのうちの１つを前記光路上に着脱可能に配置することのできる校正用ガスセル装着機構と、
    　前記光検出器の検出信号に基づいて試料気体中の測定対象成分濃度を算出する演算装置と、
    を備えたレーザ吸収分光測定のための分析装置。     A laser light source that generates laser light as measurement light of a specific wavelength that is absorbed by the measurement target component in the sample gas;
    A laser light source drive control device for controlling the drive of the laser light source;
    A photodetector disposed at a position for receiving the laser beam;
    A gas cell for measuring a sample gas disposed on an optical path of laser light from the laser light source to a photodetector;
    At least one calibration gas cell filled with a calibration gas;
    A calibration gas cell mounting mechanism capable of detachably disposing one of the calibration gas cells on the optical path;
    An arithmetic device that calculates the concentration of the measurement target component in the sample gas based on the detection signal of the photodetector;
    Analyzing device for laser absorption spectroscopy measurement.
  2. 　前記レーザ光源は波長変更可能なレーザ光源であり、
    　前記レーザ光源駆動制御装置は前記レーザ光源の駆動条件を規定するパラメータと発生するレーザ波長との関係を示す波長変動データを保持する波長変動データ保持部を備えており、
    　測定対象成分測定時には前記レーザ光源駆動制御装置は保持している波長変動データに基づいて前記レーザ光源が特定波長のレーザ光を発生するように前記レーザ光源の駆動を制御するものである請求項１に記載の分析装置。     The laser light source is a laser light source capable of changing a wavelength,
    The laser light source drive control device includes a wavelength fluctuation data holding unit that holds wavelength fluctuation data indicating a relationship between a parameter that defines a driving condition of the laser light source and a generated laser wavelength,
    2. The laser light source drive control device controls driving of the laser light source so that the laser light source generates laser light of a specific wavelength based on wavelength variation data held at the time of measurement of a measurement target component. The analyzer described in 1.
  3. 　前記波長変更可能なレーザ光源はレーザ本体の温度を調節する温度調節機構を備えてレーザ本体の温度により発生レーザ波長を変化させうるものであり、
    　前記レーザ光源駆動制御装置はレーザ光源を駆動するためのレーザ本体への一定の基準電流と、レーザ本体の温度を調節するための前記温度調節機構への電流とを供給するものであり、
    　前記波長変更可能なレーザ光源からの発生レーザ波長を固定するときはレーザ本体の温度が一定になるように前記温度調節機構への電流供給を制御し、発生レーザ波長を変化させるときはレーザ本体の温度が変化するように前記温度調節機構への電流供給を制御するものである請求項２に記載の分析装置。     The laser light source capable of changing the wavelength is provided with a temperature adjusting mechanism for adjusting the temperature of the laser body, and can change the generated laser wavelength according to the temperature of the laser body,
    The laser light source drive control device supplies a constant reference current to the laser main body for driving the laser light source and a current to the temperature adjustment mechanism for adjusting the temperature of the laser main body,
    When fixing the generated laser wavelength from the laser light source capable of changing the wavelength, the current supply to the temperature adjusting mechanism is controlled so that the temperature of the laser main body becomes constant, and when changing the generated laser wavelength, The analyzer according to claim 2, wherein current supply to the temperature adjusting mechanism is controlled so that the temperature changes.
  4. 　前記校正用ガスセルとして既知の吸収ピーク波長をもつガスが封入された波長校正用ガスセルを含み、
    　前記レーザ光源駆動制御装置は前記波長校正用ガスセルが前記光路に装着されたときの吸収ピークの波長を基にして前記波長変動データ保持部の波長変動データを校正する波長変動データ校正部を備えている請求項３に記載の分析装置。     Including a wavelength calibration gas cell in which a gas having a known absorption peak wavelength is enclosed as the calibration gas cell;
    The laser light source drive control device includes a wavelength variation data calibration unit that calibrates the wavelength variation data of the wavelength variation data holding unit based on the wavelength of the absorption peak when the wavelength calibration gas cell is attached to the optical path. The analyzer according to claim 3.
  5. 　前記波長校正用ガスセルとして前記特定波長よりも長波長側の吸収ピーク波長をもつガスが封入された第１の波長校正用ガスセルと、前記特定波長よりも短波長側の吸収ピーク波長をもつガスが封入された第２の波長校正用ガスセルを含む請求項４に記載の分析装置。 As the wavelength calibration gas cell, a first wavelength calibration gas cell in which a gas having an absorption peak wavelength longer than the specific wavelength is sealed, and a gas having an absorption peak wavelength shorter than the specific wavelength are included. The analyzer according to claim 4, comprising an enclosed second wavelength calibration gas cell.
  6. 　前記校正用ガスセルとして互いに異なる既知濃度の測定対象成分が封入された少なくとも１個の感度校正用ガスセルを含み、
    　前記演算装置は測定対象成分濃度を算出するための検量線データを保持する検量線データ保持部と、前記感度校正用ガスセルが前記光路に装着されたときの吸光度により前記検量線データ保持部の検量線データを校正する検量線データ校正部を備えている請求項１から４のいずれか一項に記載の分析装置。     The calibration gas cell includes at least one sensitivity calibration gas cell in which components to be measured having different known concentrations are enclosed,
    The arithmetic unit includes a calibration curve data holding unit for holding calibration curve data for calculating a measurement target component concentration, and a calibration curve data holding unit based on absorbance when the sensitivity calibration gas cell is attached to the optical path. The analyzer according to any one of claims 1 to 4, further comprising a calibration curve data calibration unit that calibrates the line data.
  7. 　前記感度校正用ガスセルは試料気体測定時にもレーザ光の光路上に配置され、
    　前記演算装置は光検出器から求められる吸光度から試料気体測定時にレーザ光の光路上に配置された感度校正用ガスセルによる吸光度を引く吸光度修正部を備えている請求項６に記載の分析装置。     The sensitivity calibration gas cell is arranged on the optical path of the laser beam even when measuring the sample gas,
    The analyzer according to claim 6, further comprising an absorbance correction unit that subtracts the absorbance of a gas cell for sensitivity calibration arranged on the optical path of the laser beam when measuring the sample gas from the absorbance obtained from the photodetector.
  8. 　前記校正用ガスセル装着機構は校正用ガスセルを前記光路上に着脱可能に装着できる支持機構である請求項１から７のいずれか一項に記載の分析装置。 The analyzer according to any one of claims 1 to 7, wherein the calibration gas cell mounting mechanism is a support mechanism capable of detachably mounting the calibration gas cell on the optical path.
  9. 　前記校正用ガスセル装着機構は回転中心を中心とする円周上に貫通穴と複数個の校正用ガスセルが配置されたセルホルダーを備え、該ホルダーを回転させることにより前記光路上に貫通穴又はいずれかの校正用ガスセルを配置するものである請求項１から８のいずれか一項に記載の分析装置。 The calibration gas cell mounting mechanism includes a cell holder in which a through hole and a plurality of calibration gas cells are arranged on a circumference centered on the rotation center, and the through hole or any one of them is formed on the optical path by rotating the holder. The analyzer according to claim 1, wherein the calibration gas cell is arranged.
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