JPH01285840A - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JPH01285840A JPH01285840A JP11569888A JP11569888A JPH01285840A JP H01285840 A JPH01285840 A JP H01285840A JP 11569888 A JP11569888 A JP 11569888A JP 11569888 A JP11569888 A JP 11569888A JP H01285840 A JPH01285840 A JP H01285840A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- difference
- measured
- oscillation
- transmissivity
- 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.)
- Pending
Links
- 230000010355 oscillation Effects 0.000 claims abstract description 27
- 238000000862 absorption spectrum Methods 0.000 claims abstract description 21
- 238000002834 transmittance Methods 0.000 claims description 28
- 239000004065 semiconductor Substances 0.000 claims description 7
- 238000005259 measurement Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 54
- 238000010586 diagram Methods 0.000 description 10
- 241000894007 species Species 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241000257465 Echinoidea Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 239000002775 capsule Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔概要〕
大気中の被測定ガスの吸収スペクトルを半導体レーザに
よる測定光によって測定し、この吸収スペク1〜ルに基
づいてガス11度の検出を行なうガスセンサに関し、
吸収スペクトルにおいて透過率差が大きい波長帯の幅が
広いガス種の濃度も正確に検出できることを目的どし、
半導体レーザの2つの発振モードにまたがった2つの波
長を用い、各々の波長にJ3ける透過率の差から被測定
ガスのガス濃度を検出する構成と覆る。[Detailed Description of the Invention] [Summary] This invention relates to a gas sensor that measures the absorption spectrum of a gas to be measured in the atmosphere using measurement light from a semiconductor laser, and detects gas 11 degrees based on this absorption spectrum. With the aim of accurately detecting the concentration of gas species with a wide wavelength band with a large transmittance difference in This is different from the configuration in which the gas concentration of the gas to be measured is detected from the difference between the two.
本発明は、大気中の被測定ガスの吸収スベク1〜ルを半
導体レーザによる測定光によって測定し、この吸収スペ
クトルに基づいてガス濃度の検出を行なうガスセンサに
関づる。The present invention relates to a gas sensor that measures the absorption spectrum of a gas to be measured in the atmosphere using measurement light from a semiconductor laser, and detects the gas concentration based on this absorption spectrum.
近年、公害防止等によって有害ガスの管理が厳しく規制
されており、このような管理分野において有害ガスの濃
度を測定することが行なわれている。ガスセンサの一例
として、波長可変の赤外線レーザダイオード(半導体レ
ーザ)を用い、連続的に波長の変化するレーザ光線を被
測定ガスに投射し、そのガスに特有なレーザ光線の波長
の吸収スペクトルを得、その透過率の差を測定すること
によりガス8度を測定するものがある。In recent years, the management of harmful gases has been strictly regulated due to pollution prevention and the like, and the concentration of harmful gases has been measured in the field of such management. As an example of a gas sensor, a wavelength-tunable infrared laser diode (semiconductor laser) is used to project a laser beam with a continuously changing wavelength onto a gas to be measured, and obtain an absorption spectrum of the wavelength of the laser beam that is unique to that gas. There is a method that measures gas 8 degrees by measuring the difference in transmittance.
この場合、ガス種にJ:つでは透過率差が大きい波長帯
の幅が広いものもあるが、このようなガス種のものも他
のガス種のものと同様にその温度を正確に測定できるこ
とが必要である。In this case, some gases have a wide wavelength band with a large transmittance difference, but the temperature of these gases can be measured as accurately as other gases. is necessary.
(従来の技術)
赤外線レーザダイオードを使用してガスS度を測定する
ガスセンサとして、本出願人は先に例えば、特願昭61
−105090号(特開昭62−261032号)にて
環境の絶対温度変化に対しても安定に濃度測定できる装
置、及び特願昭59−105881号(特開昭60−2
49038号)にて、レーザ光を間欠的に遮光してガス
に投射するためのライトチョッパの速度変動による影響
をなくして高精度に濃度測定できる装置等を提案した。(Prior Art) As a gas sensor for measuring gas S degree using an infrared laser diode, the present applicant has previously proposed, for example, Japanese Patent Application No.
-105090 (Japanese Unexamined Patent Publication No. 62-261032) discloses a device that can stably measure concentration even with changes in the absolute temperature of the environment, and Japanese Patent Application No. 59-105881 (Unexamined Japanese Patent Application No. 60-60
No. 49038), we proposed a device that can measure concentration with high precision by eliminating the influence of speed fluctuations of a light chopper that intermittently blocks laser light and projects it onto the gas.
これらはいずれも、大気中の被測定ガスの吸収スペクト
ルを測定光によって測定し、この吸収スペクトルに基づ
いてガス濃度の測定を行なうものである。All of these methods measure the absorption spectrum of a gas to be measured in the atmosphere using measurement light, and measure the gas concentration based on this absorption spectrum.
第5図は一般のガスセンυの構成図を示す。同図におい
て、半導体レーザ1の出射光はレンズ2にて平行光にさ
れ、ハーフミラ−3,大気中又はセル中の微量な被測定
ガス4を透過してレンズ5にて赤外線セン勺6に集光さ
れ、ここで光電変換され、信号処理回路7に入力される
。半導体レーザ1は、第6図に示すように、レーザ電流
を変化させることにより複数の発振モードM1.M2゜
M3.・・・において波長を連続的に掃引でき、これに
にす、第7図に示すような被測定ガスの吸収スペク1〜
ルを測定できる。信号処理回路7にJ3いて、透過率最
大点と波長λ1の透過率最小点との差が測定され、この
差に比例づる温度が幹出される。FIG. 5 shows a configuration diagram of a general gas sensor υ. In the figure, the emitted light from a semiconductor laser 1 is made into parallel light by a lens 2, passes through a half mirror 3, a trace amount of gas to be measured 4 in the atmosphere or in a cell, and is focused by a lens 5 onto an infrared sensor 6. The light is then photoelectrically converted and input to the signal processing circuit 7. As shown in FIG. 6, the semiconductor laser 1 has multiple oscillation modes M1... by changing the laser current. M2゜M3. The wavelength can be continuously swept in ..., and the absorption spectra 1 to 1 of the measured gas as shown in
can be measured. The signal processing circuit J3 measures the difference between the maximum transmittance point and the minimum transmittance point at wavelength λ1, and outputs a temperature proportional to this difference.
一方、ハーフミラ−3で反射された光はミラー8で反射
され、基準ガスセル9(被測定ガス4と同種で、予め既
知の濃度のガスが封入されているカプセル)を透過し、
レンズ10により赤外線センサ11に集光され、ここで
光電変換され、信号処理回路7と同様の機能を有する信
号処理回路12に入力される。信号処理回路12におい
て、基準ガスセル9に対する信号が算出される。On the other hand, the light reflected by the half mirror 3 is reflected by the mirror 8, and passes through the reference gas cell 9 (a capsule filled with a gas of the same type as the gas to be measured 4 and a known concentration in advance),
The light is focused by the lens 10 onto the infrared sensor 11, photoelectrically converted there, and input to the signal processing circuit 12 having the same function as the signal processing circuit 7. In the signal processing circuit 12, a signal for the reference gas cell 9 is calculated.
信号処理回路7,12の各出力は除算器13に供給され
、ここで、被測定ガス4例の信号の基準ガスセル9II
4の信号に対する比が削算され、表示器14に濃度表示
される。Each output of the signal processing circuits 7 and 12 is supplied to a divider 13, where the signals of the four gases to be measured are divided into reference gas cells 9II.
The ratio to the signal of 4 is subtracted, and the concentration is displayed on the display 14.
第7図に示す如く、従来の測定方法は、半導体レーザの
複数の発振モードM+ 、M2 、M3 、・・・の中
で透過率差が大きい1つのモード(第7図では例えばM
2)を用いて測定していた。この場合CHa (メタ
ンガス)やH2O(水蒸気)等のガスは、吸収スペクト
ルにおいて透過率差が大きく波長帯の幅が狭い(いわゆ
る、吸収スペクトル幅が細い)ので、1つの発振−[−
ドM2のみで十分に測定できる。As shown in FIG. 7, the conventional measurement method focuses on one mode (for example, M
2) was used for measurement. In this case, gases such as CHa (methane gas) and H2O (water vapor) have a large transmittance difference in their absorption spectra and a narrow wavelength band (so-called narrow absorption spectrum width), so one oscillation -[-
Measuring can be carried out satisfactorily with only M2.
然るに、04HIG(ブタンガス)等のガスは、分子中
の原子数が多く、分子団も大ぎい。このために、第8図
に示す如く、吸収スペクトルにおいて透過率差が大きい
波長帯の幅が広くなる(いわゆる、吸収スペクトル幅が
太い)ので、1つの発振モードM2のみでは測定できな
い問題点があった。However, gases such as 04HIG (butane gas) have a large number of atoms in the molecule and a large molecular group. For this reason, as shown in Fig. 8, the width of the wavelength band with a large transmittance difference in the absorption spectrum becomes wide (the so-called absorption spectrum width is wide), so there is a problem that measurement cannot be performed using only one oscillation mode M2. Ta.
本発明は、吸収スペクトルにおいて透過率差が大きい波
長帯の幅が広いガス種の濃度も正確に検出できるガスセ
ンサを提供することを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide a gas sensor that can accurately detect the concentration of a gas species having a wide wavelength band with a large transmittance difference in its absorption spectrum.
〔課題を解決するための手段)
第1図は本発明を説明ブーるための透過率特性図を示す
。本発明は、半導体レーザの2つの発振モードM2.M
3にまたがった2つの波長を用い、各々の波長にお番プ
る透過率に2 、に3の差りから被測定ガスのガス8度
を検出する構成としてなる。[Means for Solving the Problems] FIG. 1 shows a transmittance characteristic diagram for explaining the present invention. The present invention provides two oscillation modes M2. M
The configuration uses two wavelengths spanning 3.3 degrees, and detects 8 degrees of the gas to be measured from the difference of 2 and 3 points in transmittance at each wavelength.
第1図に示づ如く、被測定ガスが透過率差が大きい波長
帯の幅が広い(吸収スペクトル幅が太い)吸収スベクl
−ルをもつ場合、2つの発振七〜ドM2.M3にまたが
−)で夫々の透過率に2 、 K3を測定してその差り
を測定し、その差りから被測定ガスの濃度を検出する。As shown in Figure 1, the gas to be measured has a wide wavelength band with a large transmittance difference (the absorption spectrum is wide).
- M2. 2 and K3 are measured for each transmittance with M3 (-), the difference is measured, and the concentration of the gas to be measured is detected from the difference.
この場合、CaH+a等のように吸収スベク]ヘル幅が
広いガス種でも正確にalIf検出できる。In this case, even gas species such as CaH+a, which have a wide absorption range, can be detected accurately.
(実施例)
第2図は本発明ガスセンサの一実施例の構成図を示し、
同図中、第5図と同一機能をイラする部分には同一番号
をイ」シてその説明を省略覆る3、第2図中、20は発
振モード制御回路で、半導体レー+J’ 1の発振が2
つの発振し一ドにまたがるように、レーザ電流を設定す
る。21は信号処理回路で、2つの発振モードにおける
透過率の差を測定覆る3゜例えば、第1図において、C
4I−ItOW−のガスのJ、うに吸収スペクトルにお
いて透過率差が大きいスを測定(るに際し、発振モード
制御回路20にて発振モードM2.M3の2つの発振モ
ードにまたがるようにレーザ電流を設定する。この場合
、発振波長との関係を第3図(A>に示す如くと覆ると
、従来例のbのは発振モードM2のみとなるようにレー
デ電流を設定していたのに対し、本発明では発振モード
M2.M3の2つの発振モードにまたがるようにレーザ
電流を設定し、第2図に示す信号処理回路21において
、第1図に示す如く、発振t−ドM2での透過率に2と
発振モードM3での透過率に3との差りを測定し、この
透過率差りに比例する濃度を算出する、。(Example) FIG. 2 shows a configuration diagram of an example of the gas sensor of the present invention,
In the same figure, parts that have the same functions as those in FIG. 5 are given the same numbers and their explanations are omitted. is 2
The laser current is set so that it oscillates over one mode. 21 is a signal processing circuit that measures the difference in transmittance in two oscillation modes.For example, in FIG.
4I-ItOW- gas J, sea urchin absorption spectra where the transmittance difference is large is measured (at this time, the laser current is set in the oscillation mode control circuit 20 so as to span the two oscillation modes M2 and M3). In this case, if we reverse the relationship with the oscillation wavelength as shown in Fig. 3 (A>), we can see that in the conventional example b, the radar current is set so that only the oscillation mode M2 occurs, whereas in the present example In the invention, the laser current is set so as to span two oscillation modes M2 and M3, and in the signal processing circuit 21 shown in FIG. 2, as shown in FIG. The difference between the transmittance in the oscillation mode M3 and the transmittance in the oscillation mode M3 is measured, and the density proportional to this transmittance difference is calculated.
このように、2つの発振モードM2.M3を用い、2つ
の波長で夫々の透過率に2 、に3を測定しているので
、C4HIOWのガスのように透過率差が大きい波長帯
の幅が広い(吸収スペク]・ル幅が太い)ガスを測定す
る際、その透過率差りを正確に測定できる3、信号処理
回路21にて算出された濃度に苅応した信号は除算器1
3に供給され、ここで、従来例と同様にして被測定ガス
4側の信号の基準ガスセル9側の信号に対する比が4算
され、表示器14に濃度表示される。In this way, two oscillation modes M2. Since M3 is used to measure the transmittance of 2 and 3 at two wavelengths, the wavelength band where the transmittance difference is large is wide (absorption spectrum) like C4HIOW gas. ) When measuring gas, the difference in transmittance can be accurately measured 3. The signal corresponding to the concentration calculated by the signal processing circuit 21 is sent to the divider 1.
Here, as in the conventional example, the ratio of the signal on the gas to be measured 4 side to the signal on the reference gas cell 9 side is calculated by 4, and the concentration is displayed on the display 14.
なお、実際には第4図<A)に示す如く、周期的にレー
ザ電流を切断して流づ。この場合、第4図(B)に示す
如く、レーザ電流を切断してセンリ゛出力Bを測定する
ことにより被測定ガスセル自身の透過率を測定し、一方
、2つの発振モードにまたがるレーザ電流設定によるセ
ンυ出力At測定する。ここで、信号処理回路21.1
2でA/Bを算出すれば、被測定ガスセルの窓の汚染等
による影響を防ぐことかできる。In fact, as shown in FIG. 4<A), the laser current is periodically cut off and allowed to flow. In this case, as shown in Fig. 4 (B), the transmittance of the gas cell to be measured is measured by cutting off the laser current and measuring the sensor output B, while setting the laser current across the two oscillation modes. Measure the sensor υ output At. Here, the signal processing circuit 21.1
By calculating A/B in step 2, it is possible to prevent the influence of contamination of the window of the gas cell to be measured.
以ト説明した如く、本発明によれば、2つの発振モード
を用いて透過率差を測定しているので、CaH+o等の
吸収スペクl〜ル幅の広いガス種の濃度も正確に検出で
きる。As explained above, according to the present invention, since the transmittance difference is measured using two oscillation modes, it is possible to accurately detect the concentration of a gas species having a wide absorption spectrum, such as CaH+O.
第1図は本発明を説明するための透過率特性図、第2図
は本発明の一実施例の構成図、
第3図は本発明及び従来における、レーザ電流と発振波
長との関係を示す図、
第4図は本発明によるレーザ電流及びセンサ出ツノを説
明する図、
第5図は一般のガスセンザの構成図、
第6図はレーザ電流と発振波長との関係を示す図、
第7図は1つの発振モードで濃度検出できることを示(
透過率特性図、
第8図は1つの発振モードでは濃度検出できないことを
示す透過率特例図である。
図において、
1は半導体レーザ、
4は被測定ガス、
9は基準ガスセル、
12.21は信8処理回路、
13は除算器、
14は表示器、
20は発振モード制御回路、
M2.M3は発振モード、
K2 、に3は透過率、
hは透過率差
を示す。
一 嗜 噌 帰
−努 ′@1
ム
と
一一司叱 −−言巨 米は
ビ)
7% /% ”+く
のFig. 1 is a transmittance characteristic diagram for explaining the present invention, Fig. 2 is a configuration diagram of an embodiment of the present invention, and Fig. 3 shows the relationship between laser current and oscillation wavelength in the present invention and the conventional method. Figure 4 is a diagram explaining the laser current and sensor output horn according to the present invention, Figure 5 is a configuration diagram of a general gas sensor, Figure 6 is a diagram showing the relationship between laser current and oscillation wavelength, Figure 7 shows that concentration can be detected with one oscillation mode (
Transmittance characteristic diagram, FIG. 8 is a transmittance special diagram showing that concentration cannot be detected in one oscillation mode. In the figure, 1 is a semiconductor laser, 4 is a gas to be measured, 9 is a reference gas cell, 12.21 is a signal processing circuit, 13 is a divider, 14 is a display, 20 is an oscillation mode control circuit, M2. M3 indicates the oscillation mode, K2 and 3 indicate the transmittance, and h indicates the transmittance difference. 7% /% "+ku"
of
Claims (1)
よる測定光によって測定し、該吸収スペクトルに基づい
て該被測定ガスのガス濃度を検出するガスセンサにおい
て、 上記半導体レーザの2つの発振モード(M_2、M_3
)にまたがった2つの波長を用い、 該2つの波長の各々の波長における透過率 (K_2、K_3)の差(h)から上記被測定ガスのガ
ス濃度を検出する構成としてなることを特徴とするガス
センサ。[Scope of Claims] A gas sensor that measures the absorption spectrum of a gas to be measured in the atmosphere using measurement light from a semiconductor laser, and detects the gas concentration of the gas to be measured based on the absorption spectrum, comprising: Oscillation mode (M_2, M_3
), and the gas concentration of the gas to be measured is detected from the difference (h) in transmittance (K_2, K_3) at each of the two wavelengths. gas sensor.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11569888A JPH01285840A (en) | 1988-05-12 | 1988-05-12 | Gas sensor |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11569888A JPH01285840A (en) | 1988-05-12 | 1988-05-12 | Gas sensor |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH01285840A true JPH01285840A (en) | 1989-11-16 |
Family
ID=14669019
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11569888A Pending JPH01285840A (en) | 1988-05-12 | 1988-05-12 | Gas sensor |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH01285840A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006227003A (en) * | 2005-02-08 | 2006-08-31 | General Electric Co <Ge> | Method and system of optical detection for polyphase combustion system |
JP2013003038A (en) * | 2011-06-20 | 2013-01-07 | Nippon Signal Co Ltd:The | Laser measurement device and laser measurement method |
-
1988
- 1988-05-12 JP JP11569888A patent/JPH01285840A/en active Pending
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006227003A (en) * | 2005-02-08 | 2006-08-31 | General Electric Co <Ge> | Method and system of optical detection for polyphase combustion system |
EP1703206A2 (en) * | 2005-02-08 | 2006-09-20 | The General Electric Company | Method and apparatus for the optical detection of multi-phase combustion products |
JP2013003038A (en) * | 2011-06-20 | 2013-01-07 | Nippon Signal Co Ltd:The | Laser measurement device and laser measurement method |
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