JPH01254841A - Signal processing method for gas sensor - Google Patents
Signal processing method for gas sensorInfo
- Publication number
- JPH01254841A JPH01254841A JP8444188A JP8444188A JPH01254841A JP H01254841 A JPH01254841 A JP H01254841A JP 8444188 A JP8444188 A JP 8444188A JP 8444188 A JP8444188 A JP 8444188A JP H01254841 A JPH01254841 A JP H01254841A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- measured
- concentration
- lens
- wavelength
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
- 238000003672 processing method Methods 0.000 title claims description 4
- 238000000862 absorption spectrum Methods 0.000 claims abstract description 18
- 230000010355 oscillation Effects 0.000 claims abstract description 11
- 239000004065 semiconductor Substances 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 13
- 238000001514 detection method Methods 0.000 claims description 5
- 238000001228 spectrum Methods 0.000 abstract description 13
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 73
- 230000002452 interceptive effect Effects 0.000 description 21
- 238000005259 measurement Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Investigating Or Analysing Materials By Optical Means (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
〔概 要〕
半導体レーザ素子を用いてガスの濃度を検知するガスセ
ンサに関し、
被測定ガスのスペクトルに対して妨害ガス種の吸収スペ
クトルが重なっている場合に、妨害ガス種の濃度変動に
より被測定ガスの濃度測定値が変動しないようにしたガ
スセンサの信号処理方法の促供を目的とし、
半導体レーザ素子のバイアス電流を変化させることによ
り、波長の変化する赤外レーザ光を出射、該レーザ光を
被測定ガス内に透過させて、前記ガスの赤外吸収スペク
トルを光検知素子で検知し、被測定ガスの濃度を検知す
る方法に於いて、前記レーザ光の発振波長を、前記被測
定ガスの吸収スペクトルに接近した妨害ガスの吸収スペ
クトルの波高が同一レベルと成る二つの波長間を振動す
る矩形波を用いて変調することで構成する。[Detailed Description of the Invention] [Summary] Regarding a gas sensor that detects the concentration of gas using a semiconductor laser element, when the absorption spectrum of the interfering gas species overlaps with the spectrum of the gas to be measured, the interfering gas species The purpose of this research is to promote a signal processing method for gas sensors that prevents the measured concentration value of the measured gas from fluctuating due to concentration fluctuations in the gas. In the method of emitting and transmitting the laser beam into a gas to be measured and detecting the infrared absorption spectrum of the gas with a photodetecting element to detect the concentration of the gas to be measured, the oscillation wavelength of the laser beam is , by modulating using a rectangular wave that oscillates between two wavelengths such that the absorption spectrum of the interfering gas close to the absorption spectrum of the gas to be measured has the same wave height.
本発明は半導体レーザ素子を用いたガスセンサに係り、
該センサで測定すべき被測定ガス種の吸収スペクトルと
被測定ガスに同時に含まれる妨入゛ガス種の吸収スペク
トルが重なった場合でも被測定ガスの濃度が高精度に測
定できるガスセンサの信号処理方法に関する。The present invention relates to a gas sensor using a semiconductor laser element,
A signal processing method for a gas sensor that can measure the concentration of a gas to be measured with high accuracy even when the absorption spectrum of a gas to be measured by the sensor overlaps with the absorption spectrum of an interfering gas contained in the gas to be measured. Regarding.
赤外半導体レーザ素子を用いたガスセンサは、小型、高
感度、保守の容易性等の種々の利点を有しているため、
公害ガスの検知装置等に用いられている。Gas sensors using infrared semiconductor laser elements have various advantages such as small size, high sensitivity, and ease of maintenance.
Used in pollution gas detection devices, etc.
第3図は従来の赤外レーザ方式ガスセンサのブロック図
である。FIG. 3 is a block diagram of a conventional infrared laser type gas sensor.
第3図に示すように従来のガスセンサは、波長可変レー
ザ光を出力するレーザ素子1と、該レーザ光を平行光と
するレンズ2と、該平行光を分割するハーフミラ−3と
、該ハーフミラ−3で分割された一方のレーザ光が被測
定ガス4を透過する長光路セル5と、謹製光路セルから
の透過光を集光するレンズ6と、該レンズ6で集光され
た光を検知して電気信号に変換する光検知器7とより成
る。As shown in FIG. 3, a conventional gas sensor includes a laser element 1 that outputs a variable wavelength laser beam, a lens 2 that converts the laser beam into parallel light, a half mirror 3 that splits the parallel light, and a half mirror 3 that splits the parallel light. A long optical path cell 5 allows one of the laser beams divided by 3 to pass through the gas to be measured 4, a lens 6 condenses the transmitted light from the specially manufactured optical path cell, and the light condensed by the lens 6 is detected. and a photodetector 7 that converts the signal into an electrical signal.
更にハーフミラ−3で分割された他方のレーザ光を、ミ
ラー8を用いて反射させ、濃度既知のガスを収容した参
照セル9と、該参照セル9を透過したレーザ光をレンズ
10を介して検知した後、電気信号に変換する光検知器
11と、前記光検知器7と11の出力信号をそれぞれ処
理する信号処理回路12および13と、各信号処理回路
12.13の出力信号を計算して濃度表示する割算器1
4および表示器15とを備えた構成となっている。Further, the other laser beam split by the half mirror 3 is reflected using the mirror 8, and the reference cell 9 containing a gas of known concentration and the laser beam transmitted through the reference cell 9 are detected via the lens 10. After that, the photodetector 11 converts into an electric signal, the signal processing circuits 12 and 13 process the output signals of the photodetectors 7 and 11, respectively, and the output signals of each signal processing circuit 12.13 are calculated. Divider 1 that displays concentration
4 and a display 15.
このようなガスセンサの動作について図面を用いて説明
すると、半導体レーザ素子lより出射されたレーザ光は
、レンズ2により平行光線にされて被測定ガス、例えば
亜硫酸ガス(SO□)のような公害ガス4内を通過する
。このガス内を透過した光はレンズ6により赤外線検知
器7に集光され、電気信号に変換される。ここで上記し
た半導体レーデ素子1は第4図に示すように素子の印加
電流を変化させることで連続的に波長を変化させること
ができる。To explain the operation of such a gas sensor using drawings, a laser beam emitted from a semiconductor laser element 1 is converted into a parallel beam by a lens 2, and the gas to be measured, for example, a polluting gas such as sulfur dioxide gas (SO□), is Pass through 4. The light transmitted through this gas is focused by a lens 6 onto an infrared detector 7 and converted into an electrical signal. As shown in FIG. 4, the semiconductor radar device 1 described above can continuously change the wavelength by changing the current applied to the device.
従来、このような方法で被測定ガス、例えばSO□ガス
の濃度を検知する場合、第5図に示すように、検知すべ
き被測定ガスの赤外吸収スペクトル21の値をできるだ
けS /N比を良くして測定するために、レーザ発振波
長の変調を例えば前記吸収スペクトルの谷の部分の波長
(A)このAの値は例えば(8゜8451μm)と、該
スペクトルの山に対応する部分の波長(B)、このBの
値は例えば(8,8470tt m )の間で振動する
矩形波22を用いて変調して、検知37にて矩形波の出
力波形23を得ている。Conventionally, when detecting the concentration of a gas to be measured, such as SO□ gas, by such a method, as shown in FIG. In order to improve the measurement, the modulation of the laser oscillation wavelength is, for example, the wavelength (A) of the valley part of the absorption spectrum. The wavelength (B) is modulated using a rectangular wave 22 that oscillates between, for example, (8,8470 tt m ), and a rectangular output waveform 23 is obtained at the detection 37 .
ここで第5図の縦軸は赤外光の被測定ガス内に於ける透
過率(%)を示し、横軸はレーザ光の発振波長(μm)
を示す。なお妨害ガスのスペクトル24は説明のため誇
張して大きく書いである。Here, the vertical axis in Figure 5 shows the transmittance (%) of infrared light in the gas under test, and the horizontal axis shows the oscillation wavelength of the laser light (μm).
shows. Note that the spectrum 24 of the interfering gas is exaggerated and drawn in a large size for the sake of explanation.
ところで検知器7で受光する信号は、被測定ガス中に同
時に含まれる妨害ガス、即ち水蒸気(11□0)のスペ
クトル24が重なった状態になっており、この妨害ガス
のスペクトル24に於ける矩形波22の谷に対応する波
長(A)と矩形波22のlIJに対応する波長(B)に
対応する部分との差の値(α)に相当する矩形波のオフ
セント電圧の部分だけ被測定ガスのスペクトルに影響を
及ぼし、被測定ガスのスペクトル測定値の検知器7.に
於ける出力波形23が妨害ガスの濃度変動にともなって
変動して揺らぐ問題点がある。By the way, the signal received by the detector 7 is in a state in which the spectrum 24 of the interfering gas simultaneously contained in the gas to be measured, that is, water vapor (11□0), overlaps with the rectangular shape in the spectrum 24 of this interfering gas. Only the portion of the offset voltage of the rectangular wave corresponding to the difference value (α) between the wavelength (A) corresponding to the trough of the wave 22 and the portion corresponding to the wavelength (B) corresponding to lIJ of the rectangular wave 22 is measured. 7. Detector of spectral measurements of the gas to be measured; There is a problem in that the output waveform 23 fluctuates and fluctuates as the concentration of the interfering gas changes.
従来は、このような妨害ガスの吸収スペクトルの影響を
防止する方法として、レーデ素子を2個用意し、妨害ガ
スと被測定ガスの吸収スペクトルを別個に測定したのち
補正する方法(特願昭61−154488号参照)或い
は、湿度計を用いて妨害ガスの濃度を検知し、この検知
した値で検知器で出力される被測定ガスのスペクトル値
を補正する方法(特開昭62−261032号公報参照
)を採っていた。Conventionally, as a method to prevent the influence of the absorption spectrum of the interfering gas, a method was proposed in which two Raded elements were prepared and the absorption spectra of the interfering gas and the gas to be measured were measured separately and then corrected (Japanese Patent Application No. 1983). 154488)) or a method of detecting the concentration of interfering gas using a hygrometer and correcting the spectrum value of the gas to be measured output by the detector using the detected value (see Japanese Patent Laid-Open No. 62-261032). ).
然し、このような方法ではレーザ素子を2個必要とし、
更にこのレーザ素子に付随して測定回路を別系統に設け
る必要があり、ガスセンサの装置構成が複雑になり、装
置が大型になりまた装置のコストも上昇する問題がある
。However, this method requires two laser elements,
Furthermore, it is necessary to provide a measurement circuit in a separate system in conjunction with this laser element, which complicates the device configuration of the gas sensor, increases the size of the device, and increases the cost of the device.
本発明は上記した問題点を除去し、複雑な装置構成を採
らずに容易に高精度に被測定ガスの濃度が検知できるよ
うなガスセンサの濃度検知方法の提供を目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide a concentration detection method for a gas sensor that eliminates the above-mentioned problems and allows the concentration of a gas to be measured to be detected easily and with high accuracy without requiring a complicated device configuration.
上記問題点を解決する本発明のガスセンサの濃度検知方
法は第1図に示すように、前記レーザ光の発振波長を、
前記被測定ガスの妨害ガスの吸収スペクトル31の波高
が同一レベルと成る二つの波長間を振動する矩形波32
を用いて変調することで構成する。As shown in FIG. 1, the concentration detection method for a gas sensor according to the present invention solves the above problems, as shown in FIG.
A rectangular wave 32 that oscillates between two wavelengths in which the wave height of the interference gas absorption spectrum 31 of the measured gas is at the same level.
It is constructed by modulating using .
本発明の方法は前記レーザ光の発振波長を、前記被測定
ガスに同時に含まれる妨害ガスの吸収スペクトルの波高
が同一レベルと成る二つの波長間を振動する矩形波を用
いて変調することで検知器で受光する信号に妨害ガスの
吸収スペクトルによる干渉が入らないようにする。The method of the present invention modulates the oscillation wavelength of the laser beam using a rectangular wave that oscillates between two wavelengths where the absorption spectrum of the interfering gas simultaneously contained in the gas to be measured has the same level. This prevents interference due to the absorption spectrum of the interfering gas from entering the signal received by the device.
以下・図面を用いて本発明の一実施例につき詳細に説明
する。An embodiment of the present invention will be described in detail below with reference to the drawings.
第1図は本発明の詳細な説明図である。ここで妨害ガス
のスペクトル31は説明のため誇張して大きく書いであ
る。FIG. 1 is a detailed explanatory diagram of the present invention. Here, the spectrum 31 of the interfering gas is exaggerated and drawn in a large size for the sake of explanation.
図示するように被測定ガス(So□)のスペクトル21
に重なった形の妨害ガス(11□0)のスペクトル31
で同一波高レベルD、E間を振動し、被測定ガス(SO
2)のスペクトル21の谷の部分に該当する波長A(8
,8451)人と、前記妨害ガススペクトル31のEの
位置に相当する波長C(8,8458)μmの間を振動
する矩形波32でレーザ素子の発振波長を変調するよう
にする。このようにすれば、前記した従来のように妨害
ガススペクトルのオフセット電圧αの影響が測定値に及
ぼさないので、高信頼度の安定した測定ができる。As shown in the figure, the spectrum 21 of the gas to be measured (So□)
Spectrum 31 of the interfering gas (11□0) superimposed on
The measured gas (SO
Wavelength A (8) corresponding to the valley part of spectrum 21 of 2)
, 8451) The oscillation wavelength of the laser element is modulated by a rectangular wave 32 that oscillates between wavelength C (8,8458) μm corresponding to the position E of the disturbing gas spectrum 31. In this way, since the measurement value is not affected by the offset voltage α of the interfering gas spectrum unlike the conventional method described above, highly reliable and stable measurement can be performed.
このような方法を実施するためのガスセンサの構成は第
2図に示すようになる。The configuration of a gas sensor for carrying out such a method is shown in FIG.
図示するように本発明の方法を実施する装置構成は、前
記第3図に示した従来の装置の光検知器11の出力を、
マイクロコンピュータ46にて解析し、この解析した値
を用いて妨害ガスのスペクトル値が同一レベルとなる波
長A、Cを検知し、その波長A、C間で振動する矩形波
32を用いてレーザ素子1の発振波長を変調する。As shown in the figure, the apparatus configuration for implementing the method of the present invention is such that the output of the photodetector 11 of the conventional apparatus shown in FIG.
The microcomputer 46 analyzes it, uses this analyzed value to detect the wavelengths A and C at which the spectrum values of the interfering gas are at the same level, and uses the rectangular wave 32 that oscillates between the wavelengths A and C to drive the laser element. Modulates the oscillation wavelength of 1.
このように第2図に示すように、マイクロコンピュータ
46のような装置を追加する理由は、レーザ素子は経時
変化するため発振波長が微妙に変化するので濃度測定直
前にレーザの発振波長を高精度に測定する必要があるか
らである。As shown in Figure 2, the reason for adding a device such as the microcomputer 46 is that the oscillation wavelength of the laser element changes slightly over time, so it is possible to adjust the oscillation wavelength of the laser with high precision just before concentration measurement. This is because it is necessary to measure the
このようにすれば妨害ガスのスペクトル値を検知する半
導体レーザ素子を別個に設ける必要がなく、またこの別
個に設けたレーザ素子に付随する測定回路を設ける必要
がないので、簡単な方法で容易に妨害ガスの影響を無く
した状態で第1図の検知器出力波形33に示すように、
被測定ガスの濃度を高精度に検知することができる。In this way, there is no need to separately provide a semiconductor laser element for detecting the spectral value of the interfering gas, and there is no need to provide a measurement circuit associated with this separately provided laser element. As shown in the detector output waveform 33 in Fig. 1, when the influence of interfering gas is eliminated,
The concentration of the gas to be measured can be detected with high accuracy.
以上の説明から明らかなように本発明によれば、簡単な
方法で、妨害ガスの影響を無くした状態で容易に被測定
ガスの濃度を高精度に検知することができ、本発明の方
法をガスセンサに用いれば、高精度のガスセンサが得ら
れる効果がある。As is clear from the above description, according to the present invention, the concentration of the gas to be measured can be easily detected with high accuracy using a simple method without the influence of interfering gases. If used in a gas sensor, a highly accurate gas sensor can be obtained.
第1図は本発明の詳細な説明図、
第2図は本発明の方法を実施するためのガスセンサのブ
ロック図、
第3図は従来の方法に用いるガスセンサのブロック図、
第4図はレーザ素子の印加電流と発振波長との関係図、
第5図は従来の方法の説明図である。
図に於いて、
1はレーザ素子、2はレンズ、3はハーフミラ−14は
被測定ガス、5は長光路セル、6は集光レンズ、7は光
検知器、9は参照セル、10はレンズ、11は光検知器
、12.13は信号処理回路、■4は割算器、15は表
示器、21は被測定ガス吸収スペクトル、24.31は
妨害ガス吸収スペクトル、32は矩形波、33は検知器
出力波形、46はマイクロコンピュータを示す。
A C−+(、Brn)
滲j柊E7ガめ方5天栢げ明図
第1図
′″13
才発叫^方は屯梵北カンのガ゛ズ2>む7’0.77図
嘉 2 !
R/lλはにI下\・ρ“スリブの7°’CJv7図第
3図
→印77[+電え
し一丈−1知1すvri*;Lビギ外p匿1イに℃の匍
ブよr]第4図Fig. 1 is a detailed explanatory diagram of the present invention, Fig. 2 is a block diagram of a gas sensor for carrying out the method of the present invention, Fig. 3 is a block diagram of a gas sensor used in the conventional method, and Fig. 4 is a laser element. FIG. 5 is an explanatory diagram of the conventional method. In the figure, 1 is a laser element, 2 is a lens, 3 is a half mirror, 14 is a gas to be measured, 5 is a long optical path cell, 6 is a condensing lens, 7 is a photodetector, 9 is a reference cell, 10 is a lens , 11 is a photodetector, 12.13 is a signal processing circuit, 4 is a divider, 15 is a display, 21 is a measured gas absorption spectrum, 24.31 is an interfering gas absorption spectrum, 32 is a square wave, 33 indicates the detector output waveform, and 46 indicates the microcomputer. A C-+ (, Brn) 滲ッ柊E7 がめ方 5 天梢 明 fig. Ka 2! R/lλ is under I\・ρ"Sribu's 7°'CJv7 Figure 3 → Mark 77 [+Denshi Ichijo-1chi1suvri*; Figure 4
Claims (1)
り、波長の変化する赤外レーザ光を出射、該レーザ光を
被測定ガス内に透過させて、前記ガスの赤外吸収スペク
トルを光検知素子で検知し、被測定ガスの濃度を検知す
る方法に於いて、前記レーザ光の発振波長を、前記被測
定ガスの吸収スペクトルに近接した妨害ガスの吸収スペ
クトル(31)の波高が同一レベルと成る二つの波長間
を振動する矩形波(32)を用いて変調することを特徴
とするガスセンサの信号処理方法。By changing the bias current of the semiconductor laser element, an infrared laser beam with a changing wavelength is emitted, the laser beam is transmitted into the gas to be measured, and the infrared absorption spectrum of the gas is detected by a light detection element. In a method for detecting the concentration of a gas to be measured, the oscillation wavelength of the laser beam is set to two wavelengths at which the wave heights of the absorption spectrum (31) of a disturbing gas close to the absorption spectrum of the gas to be measured are at the same level. 1. A signal processing method for a gas sensor, characterized in that modulation is performed using a rectangular wave (32) that oscillates between.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8444188A JPH01254841A (en) | 1988-04-05 | 1988-04-05 | Signal processing method for gas sensor |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8444188A JPH01254841A (en) | 1988-04-05 | 1988-04-05 | Signal processing method for gas sensor |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH01254841A true JPH01254841A (en) | 1989-10-11 |
Family
ID=13830680
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8444188A Pending JPH01254841A (en) | 1988-04-05 | 1988-04-05 | Signal processing method for gas sensor |
Country Status (1)
Country | Link |
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JP (1) | JPH01254841A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5015099A (en) * | 1989-03-23 | 1991-05-14 | Anritsu Corporation | Differential absorption laser radar gas detection apparatus having tunable wavelength single mode semiconductor laser source |
JP2013503466A (en) * | 2009-08-26 | 2013-01-31 | ナノプラス ゲーエムベーハー ナノシステムズ アンド テクノロジーズ | Semiconductor laser with absorber mounted on a laser mirror |
RU2484450C1 (en) * | 2011-11-24 | 2013-06-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Кубанский государственный технологический университет" (ФГБОУ ВПО "КубГТУ") | Infrared detector for measurement of concentration of molecules of toxic gases in air flow |
CN103398976A (en) * | 2013-07-12 | 2013-11-20 | 河南汉威电子股份有限公司 | Reflection type open circuit laser gas detection system |
CN105203460A (en) * | 2015-10-27 | 2015-12-30 | 中国科学院合肥物质科学研究院 | Infrared laser spectrum system for detecting trace quantity of water steam, and detection method thereof |
WO2018135590A1 (en) * | 2017-01-19 | 2018-07-26 | コニカミノルタ株式会社 | Substance detecting device |
-
1988
- 1988-04-05 JP JP8444188A patent/JPH01254841A/en active Pending
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5015099A (en) * | 1989-03-23 | 1991-05-14 | Anritsu Corporation | Differential absorption laser radar gas detection apparatus having tunable wavelength single mode semiconductor laser source |
JP2013503466A (en) * | 2009-08-26 | 2013-01-31 | ナノプラス ゲーエムベーハー ナノシステムズ アンド テクノロジーズ | Semiconductor laser with absorber mounted on a laser mirror |
US8879599B2 (en) | 2009-08-26 | 2014-11-04 | Nanoplus Gmbh Nanosystems And Technologies | Semiconductor laser with absorber applied to a laser mirror |
RU2484450C1 (en) * | 2011-11-24 | 2013-06-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Кубанский государственный технологический университет" (ФГБОУ ВПО "КубГТУ") | Infrared detector for measurement of concentration of molecules of toxic gases in air flow |
CN103398976A (en) * | 2013-07-12 | 2013-11-20 | 河南汉威电子股份有限公司 | Reflection type open circuit laser gas detection system |
CN105203460A (en) * | 2015-10-27 | 2015-12-30 | 中国科学院合肥物质科学研究院 | Infrared laser spectrum system for detecting trace quantity of water steam, and detection method thereof |
WO2018135590A1 (en) * | 2017-01-19 | 2018-07-26 | コニカミノルタ株式会社 | Substance detecting device |
JPWO2018135590A1 (en) * | 2017-01-19 | 2019-11-07 | コニカミノルタ株式会社 | Substance detection device |
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