JP6756999B2 - Gas measuring device - Google Patents

Gas measuring device Download PDF

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JP6756999B2
JP6756999B2 JP2018507260A JP2018507260A JP6756999B2 JP 6756999 B2 JP6756999 B2 JP 6756999B2 JP 2018507260 A JP2018507260 A JP 2018507260A JP 2018507260 A JP2018507260 A JP 2018507260A JP 6756999 B2 JP6756999 B2 JP 6756999B2
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light
gas
absorption wavelength
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light receiving
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JPWO2017164033A1 (en
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久一郎 今出
久一郎 今出
亮太 石川
亮太 石川
義憲 井手
義憲 井手
久典 川島
久典 川島
達雄 椎名
達雄 椎名
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Chiba University NUC
Konica Minolta Inc
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Konica Minolta Inc
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers

Description

本発明は、ガス測定装置に関する。 The present invention relates to a gas measuring device.

従来の濃度厚み積を算出するガス測定装置としては、吸収波長と非吸収波長の2波長の受光信号強度の差分を取り濃度厚み積を求める差分吸収法(DIAL,DOAS)によるものと、ガス吸収線を中心に基本波fで変調し、2倍波2fとの受光信号比により濃度厚み積を求める2f検波方式によるものとが挙げられる。
前者は、直接差分による演算で、濃度厚み積を算出する演算処理自体は簡易であり、距離の測定も可能だが、2波長を出射するために、発光周期を遅くする、レーザーダイオードを2個用いるなど複雑な処理、装置構成が必要である。
後者は、微小な信号変化を特定周波数の出力を取り出し演算することにより、高感度に測定が可能で、非常にコンパクトな設計が可能な技術である。しかし濃度厚み積を算出する演算が複雑になり、距離測定も困難となり、発光周期の高速化も難しい。
また、両者とも波長を測定対象の吸収波長位置に一定に保つことが非常に難しいほか、レーザーダイオードの出力に依存し、波長が変わるため、測定中のレーザーパワーを一定にすることも難しい。波長は温度と入力電流により決まるため、ハイパワーで所望の波長を出力することにも制限が生じる。
Conventional gas measuring devices for calculating the concentration-thickness product include a differential absorption method (DIAL, DOAS) in which the difference between the light-receiving signal intensities of two wavelengths, an absorption wavelength and a non-absorption wavelength, is obtained to obtain the concentration-thickness product, and gas absorption. The 2f detection method may be used, in which the line is modulated by the fundamental wave f and the density-thickness product is obtained from the light-receiving signal ratio with the double-wavelength 2f.
The former is a direct difference calculation, and the calculation process itself to calculate the concentration-thickness product is simple and the distance can be measured, but two laser diodes are used to slow down the light emission cycle in order to emit two wavelengths. Complex processing and device configuration are required.
The latter is a technology that enables highly sensitive measurement by extracting and calculating an output of a specific frequency for minute signal changes, and enables a very compact design. However, the calculation of the density-thickness product becomes complicated, the distance measurement becomes difficult, and the light emission cycle becomes difficult to speed up.
In addition, it is very difficult to keep the wavelength constant at the absorption wavelength position of the measurement target in both cases, and it is also difficult to keep the laser power during measurement constant because the wavelength changes depending on the output of the laser diode. Since the wavelength is determined by the temperature and the input current, there is a limit to the output of a desired wavelength with high power.

特許文献1には、一つのレーザー光源と、OPO(光パラメトリック発振)と、エタロン板とを用いてガスの吸収波長、非吸収波長の2波長のレーザー光を外部へ照射し、反射光をダイクロイックミラーで分光し、それぞれの波長に対応した検出器の出力より測定対象の濃度厚み積を算出する発明が記載さている。 In Patent Document 1, one laser light source, OPO (optical parametric oscillation), and an etalon plate are used to irradiate the outside with laser light having two wavelengths of absorption wavelength and non-absorption wavelength of gas, and the reflected light is dichroic. An invention is described in which the density and thickness product of a measurement target is calculated from the output of a detector corresponding to each wavelength by splitting with a mirror.

特開2001−159604号公報Japanese Unexamined Patent Publication No. 2001-159604

しかし、特許文献1に記載の発明にあっては、レーザー光源が一つで済むものの、OPO、さらにはダイクロイックミラー、エタロンフィルタ、2種類の検出器を用いるなど、全体としては必要な構成部品も多く複雑化する。 However, in the invention described in Patent Document 1, although only one laser light source is required, there are also necessary components as a whole, such as using an OPO, a dichroic mirror, an etalon filter, and two types of detectors. It gets a lot more complicated.

本発明は以上の従来技術における問題に鑑みてなされたものであって、比較的簡単な構成で発光及び受光検出、濃度厚み積の算出が可能であり、発光の出力を一定に保った状態で吸収波長及び非吸収波長に亘り波長を変えて出力することができるガス測定装置を提供することを課題とする。 The present invention has been made in view of the above problems in the prior art, and it is possible to detect light emission and light reception and calculate the density-thickness product with a relatively simple configuration, and keep the output of light emission constant. An object of the present invention is to provide a gas measuring device capable of outputting by changing the wavelength over an absorption wavelength and a non-absorption wavelength.

以上の課題を解決するための請求項1記載の発明は、測定対象ガスを検出するための光を発光する発光部と、
前記発光部の発光を制御する制御部と、
前記発光部が発光し空間を経た光を受光する受光部と、
前記受光部が受光した信号を処理する演算部と、を備えて前記空間における測定対象ガスの濃度厚み積を算出するガス測定装置であって、
前記測定対象ガスの光吸収波長を示すリファレンスと、前記発光部が発光し前記リファレンスを経た光を受光するリファレンス受光部と、を備え、
前記制御部は、前記リファレンス受光部の受光信号のフィードバックを得て、前記発光部に矩形波電流を入力することで、前記発光部が発光する光の波長に前記測定対象ガスの吸収波長及び非吸収波長に亘る変化を与え、
前記演算部は、前記受光部が受光した前記吸収波長の光の受光信号及び前記非吸収波長の光の受光信号に基づき、前記測定対象ガスの濃度厚み積を算出するガス測定装置である。
The invention according to claim 1 for solving the above problems includes a light emitting unit that emits light for detecting a gas to be measured and a light emitting unit.
A control unit that controls the light emission of the light emitting unit,
A light receiving unit that emits light and receives light that has passed through space,
A gas measuring device comprising a calculation unit for processing a signal received by the light receiving unit and calculating the concentration-thickness product of the gas to be measured in the space.
A reference indicating the light absorption wavelength of the gas to be measured and a reference light receiving unit that emits light from the light emitting unit and receives light that has passed through the reference are provided.
The control unit obtains the feedback of the light receiving signal of the reference light receiving unit and inputs a rectangular wave current to the light emitting unit, so that the wavelength of the light emitted by the light emitting unit is the absorption wavelength of the gas to be measured and the non-absorption wavelength of the gas to be measured. Gives a change over the absorption wavelength,
The calculation unit is a gas measuring device that calculates the concentration-thickness product of the gas to be measured based on the light receiving signal of the light of the absorption wavelength received by the light receiving unit and the light receiving signal of the light of the non-absorption wavelength.

請求項2記載の発明は、前記演算部は、前記受光部が受光した前記吸収波長の光の受光信号と、前記非吸収波長の光の受光信号との差分に基づき測定対象ガスの濃度厚み積を算出する請求項1に記載のガス測定装置である。 According to the second aspect of the present invention, the calculation unit uses the concentration-thickness product of the gas to be measured based on the difference between the light receiving signal of the absorption wavelength light received by the light receiving unit and the light receiving signal of the non-absorption wavelength light. The gas measuring device according to claim 1.

請求項3記載の発明は、前記演算部は、前記受光部が受光した前記吸収波長及び前記非吸収波長に亘る受光信号時系列データを得て、当該受光信号時系列データに基づき、前記測定対象ガスの濃度厚み積を算出する請求項1に記載のガス測定装置である。 In the invention according to claim 3, the calculation unit obtains light-receiving signal time-series data over the absorption wavelength and the non-absorption wavelength received by the light-receiving unit, and the measurement target is based on the light-receiving signal time-series data. The gas measuring device according to claim 1, which calculates the concentration-thickness product of gas.

請求項4記載の発明は、前記演算部は、受光信号時系列データを、前記吸収波長の光を受光する吸収線受光期間で積分し当該積分値に基づき、前記測定対象ガスの濃度厚み積を算出する請求項3に記載のガス測定装置である。 In the invention according to claim 4, the calculation unit integrates the received signal time series data in the absorption line light receiving period for receiving light of the absorption wavelength, and based on the integrated value, calculates the concentration thickness product of the gas to be measured. The gas measuring device according to claim 3, which is calculated.

請求項5記載の発明は、前記演算部は、前記非吸収波長の光を受光する非吸収線受光期間で積分し当該積分値と、前記吸収線受光期間の積分値とに基づき、前記測定対象ガスの濃度厚み積を算出する請求項4に記載のガス測定装置である。 In the invention according to claim 5, the calculation unit integrates in the non-absorption line light receiving period for receiving light of the non-absorption wavelength, and the measurement target is based on the integrated value and the integrated value in the absorption line light receiving period. The gas measuring device according to claim 4, wherein the concentration-thickness product of the gas is calculated.

請求項6記載の発明は、前記演算部は、前記非吸収波長の光の受光信号に基づき、測定エラーを判定する請求項1から請求項4のうちいずれか一に記載のガス測定装置である。 The invention according to claim 6 is the gas measuring device according to any one of claims 1 to 4, wherein the calculation unit determines a measurement error based on a received signal of light having a non-absorption wavelength. ..

請求項記載の発明は、前記演算部は、前記受光部が受光した前記吸収波長の光の受光信号と、前記リファレンス受光部が受光した前記吸収波長の光の受光信号とに基づき測定対象ガスの濃度厚み積を算出する請求項に記載のガス測定装置である。 In the invention according to claim 7 , the calculation unit uses the light receiving signal of the absorption wavelength light received by the light receiving unit and the light receiving signal of the absorption wavelength light received by the reference light receiving unit to measure the gas. The gas measuring apparatus according to claim 1 , wherein the concentration-thickness product of

請求項記載の発明は、前記演算部は、前記受光部が受光した前記吸収波長及び前記非吸収波長に亘る受光信号時系列データ、及び前記リファレンス受光部が受光した前記吸収波長及び前記非吸収波長に亘るリファレンス受光信号時系列データを得て、当該受光信号時系列データと当該リファレンス受光信号時系列データとに基づき、前記測定対象ガスの濃度厚み積を算出する請求項に記載のガス測定装置である。 According to the eighth aspect of the present invention, the calculation unit may use time-series data of a light receiving signal over the absorption wavelength and the non-absorption wavelength received by the light receiving unit, and the absorption wavelength and the non-absorption received by the reference light receiving unit. to obtain the reference light reception signal time-series data over a wavelength, based on the said received signal time-series data and the reference received light signal time-series data, gas measurement according to claim 1 for calculating the concentration thickness product of the measurement target gas It is a device.

請求項記載の発明は、前記制御部は、前記発光部の温度を一定に制御する請求項1から請求項のうちいずれか一に記載のガス測定装置である。 The invention according to claim 9 is the gas measuring device according to any one of claims 1 to 8 , wherein the control unit controls the temperature of the light emitting unit to be constant.

請求項10記載の発明は、前記演算部は、前記制御部による前記矩形波電流の入力タイミング信号との同期と、前記矩形波電流の入力に伴う前記発光部が発光する光の波長の時間変化特性データの参照とが可能にされた請求項1から請求項のうちいずれか一に記載のガス測定装置である。 According to a tenth aspect of the present invention, the calculation unit synchronizes with the input timing signal of the square wave current by the control unit, and changes in the wavelength of the light emitted by the light emitting unit with the input of the square wave current. The gas measuring device according to any one of claims 1 to 9 , wherein characteristic data can be referred to.

請求項11記載の発明は、前記発光部の発光素子として分布帰還型レーザダイオード(DFB−LD)を備える請求項1から請求項10のうちいずれか一に記載のガス測定装置である。 The invention of claim 11 wherein is a gas measuring device according to any one of claims 1 to 10 comprising the light emitting portion of the light-emitting element as a distributed feedback laser diode (DFB-LD).

請求項12記載の発明は、前記演算部は、前記発光部の発光タイミングと前記受光部の受光タイミングの時差に基づき、前記発光部から前記受光部までの光路距離を測定する請求項1から請求項11のうちいずれか一に記載のガス測定装置である。 The invention according to claim 12 , wherein the calculation unit measures the optical path distance from the light emitting unit to the light receiving unit based on the time difference between the light emitting timing of the light emitting unit and the light receiving timing of the light receiving unit. Item 2. The gas measuring device according to any one of items 11 .

請求項13記載の発明は、前記発光部が発光する光で前記空間を走査する走査機構を備える請求項1から請求項12のうちいずれか一に記載のガス測定装置である。 The invention according to claim 13 is the gas measuring device according to any one of claims 1 to 12 , further comprising a scanning mechanism for scanning the space with the light emitted by the light emitting unit.

請求項14記載の発明は、前記発光部と、前記受光部とが前記空間を挟んで対向配置される請求項1から請求項12のうちいずれか一に記載のガス測定装置である。 The invention according to claim 14 is the gas measuring device according to any one of claims 1 to 12 , wherein the light emitting unit and the light receiving unit are arranged so as to face each other with the space in between.

本発明によれば、発光部に、矩形波電流等の落差のある2つの値の間で急峻に変化する電流を入力することで、DFB−LDなど発光素子の応答特性を利用して、発光部が発光する光の波長に測定対象ガスの吸収波長及び非吸収波長に亘る変化を与えるので、比較的簡単な構成で発光及び受光検出、濃度厚み積の算出が可能であり、入力電流を一定にすることで発光の出力を一定に保つことができ、これにより発光の出力を一定に保った状態で吸収波長及び非吸収波長に亘り波長を変えて出力することができる。 According to the present invention, by inputting a current that changes sharply between two values having a difference such as a rectangular wave current into a light emitting unit, light emission is performed by utilizing the response characteristics of a light emitting element such as DFB-LD. Since the wavelength of the light emitted by the unit is changed over the absorption wavelength and non-absorption wavelength of the gas to be measured, it is possible to detect light emission and light reception and calculate the concentration thickness product with a relatively simple configuration, and the input current is constant. By setting the light emission output to a constant value, the light emission output can be kept constant, whereby the emission wavelength can be changed over the absorption wavelength and the non-absorption wavelength while the light emission output is kept constant.

本発明の一実施形態においてDFB−LDに入力する矩形波電流の波形図である。It is a waveform diagram of the rectangular wave current input to DFB-LD in one Embodiment of this invention. DFB−LDの矩形波電流の入力に対する波長の時間変化を示す一例のグラフである。It is an example graph which shows the time change of the wavelength with respect to the input of the rectangular wave current of DFB-LD. 本発明の一実施形態において受光信号時系列データを表すグラフで、非検出時の例を示す。In one embodiment of the present invention, a graph showing time-series data of received signal signals shows an example at the time of non-detection. 本発明の一実施形態において受光信号時系列データを表すグラフで、検出時の例を示す。In one embodiment of the present invention, a graph showing time-series data of received signal signals shows an example at the time of detection. 本発明の一実施形態において受光信号時系列データを表すグラフで、図3Bの部分拡大図である。It is a graph showing the received signal time series data in one embodiment of the present invention, and is a partially enlarged view of FIG. 3B. 発光素子の入力電流の変化に対する波長の変化の温度特性を示すグラフである。It is a graph which shows the temperature characteristic of the change of a wavelength with respect to the change of the input current of a light emitting element. 本発明の一実施形態に係るガス測定装置の構成ブロック図である。It is a block diagram of the structure of the gas measuring apparatus which concerns on one Embodiment of this invention. 本発明の一実施形態においてリファレンス受光信号時系列データを表す一例のグラフである。It is an example graph which shows the reference light-receiving signal time series data in one Embodiment of this invention. 本発明の一実施形態において受光信号時系列データを表す一例のグラフである。It is an example graph which shows the received signal time series data in one Embodiment of this invention. 本発明の他の一実施形態に係る投光ユニットと受光ユニットに分かれた装置形態の構成ブロック図である。It is a block diagram of the apparatus embodiment which divided into the light emitting unit and the light receiving unit which concerns on another Embodiment of this invention. 本発明の一実施形態において受光信号時系列データを表すグラフで、非検出時の例を示す。In one embodiment of the present invention, a graph showing time-series data of received signal signals shows an example at the time of non-detection. 本発明の一実施形態において受光信号時系列データを表すグラフで、検出時の例を示す。In one embodiment of the present invention, a graph showing time-series data of received signal signals shows an example at the time of detection. 本発明の一実施形態において受光信号時系列データを表すグラフで、測定エラー時の例を示す。In one embodiment of the present invention, a graph showing time-series data of received signal signals shows an example at the time of measurement error. 本発明の一実施形態において利用する距離測定原理の概略を説明する模式図である。It is a schematic diagram explaining the outline of the distance measurement principle used in one Embodiment of this invention.

以下に本発明の一実施形態につき図面を参照して説明する。以下は本発明の一実施形態であって本発明を限定するものではない。 An embodiment of the present invention will be described below with reference to the drawings. The following is an embodiment of the present invention and does not limit the present invention.

DFB−LDに急峻な電流変化を加えた際に、発熱量の増加に伴い活性層の屈折率が上昇し、波長が長波長側にμsからmsオーダーで非線形的に変化することが知られている。本発明はその波長変化により、測定対象ガスの吸収波長及び非吸収波長に亘る変化を与える。DFB−LDに急峻な電流変化を加えるため、図1に示すような矩形波電流を入力する。なお、この矩形波電流を一定にすることで、発光の出力を一定に保つことができる。
DFB−LDに図1の矩形波電流を入力すると、図2に示すようにDFB−LDの出射光の波長が変化する。この波長変化範囲に測定対象ガスの吸収波長があるようにする。
このように波長変化するDFB−LDの出射光を、測定対象空間を経て受光すると、図3A又は図3Bに示すような受光信号時系列データが得られる。図3Aは、測定対象空間に測定対象ガスが無かった場合であり略矩形状の波形となるが、測定対象空間に測定対象ガスがあるとその濃度厚み積に応じて吸収波長の光が吸収されるので図3Bに示すように1つの矩形部aの天面のそれぞれに負のピークa1が生じる。
負のピークa1に隣接する正のピークa2,a3は、非吸収波長の受光信号であるので、負のピークa1と、正のピークa2又はa3との相対性により測定対象ガスの濃度厚み積を算出可能である。例えば、図3Cに示すように、負のピークa1の受光信号と、正のピークa2の受光信号との差分に基づき測定対象ガスの濃度厚み積を算出する。
It is known that when a steep current change is applied to DFB-LD, the refractive index of the active layer increases as the amount of heat generated increases, and the wavelength changes non-linearly from μs to ms order on the long wavelength side. There is. The present invention gives a change over the absorption wavelength and the non-absorption wavelength of the gas to be measured by the wavelength change. In order to apply a steep current change to the DFB-LD, a rectangular wave current as shown in FIG. 1 is input. By keeping the rectangular wave current constant, the output of light emission can be kept constant.
When the rectangular wave current of FIG. 1 is input to the DFB-LD, the wavelength of the emitted light of the DFB-LD changes as shown in FIG. Make sure that the absorption wavelength of the gas to be measured is within this wavelength change range.
When the emitted light of the DFB-LD whose wavelength changes in this way is received through the measurement target space, the received signal time series data as shown in FIG. 3A or FIG. 3B can be obtained. FIG. 3A shows a case where there is no measurement target gas in the measurement target space and the waveform is substantially rectangular. However, when the measurement target gas is in the measurement target space, light having an absorption wavelength is absorbed according to the concentration and thickness product. Therefore, as shown in FIG. 3B, a negative peak a1 is generated on each of the top surfaces of one rectangular portion a.
Since the positive peaks a2 and a3 adjacent to the negative peak a1 are light receiving signals having a non-absorption wavelength, the concentration-thickness product of the gas to be measured is determined by the relative relationship between the negative peak a1 and the positive peak a2 or a3. It can be calculated. For example, as shown in FIG. 3C, the concentration-thickness product of the gas to be measured is calculated based on the difference between the light-receiving signal of the negative peak a1 and the light-receiving signal of the positive peak a2.

以上のような発光素子の入力電流に急峻な電流変化を加えたときの波長変化の応答特性は、図4に示すように温度にも依存する。図4に示すように吸収波長λ1を横切るタイミングが温度によって異なってしまうため、発光素子の温度を一定に保つことが好ましい。 As shown in FIG. 4, the response characteristic of the wavelength change when a steep current change is applied to the input current of the light emitting element as described above also depends on the temperature. As shown in FIG. 4, since the timing of crossing the absorption wavelength λ1 differs depending on the temperature, it is preferable to keep the temperature of the light emitting element constant.

図5に本発明によるガス測定装置の一例の構成図を示す。
図5に示すようにガス測定装置100は、測定対象ガスG1を検出するための光(測定光101)を発光する発光部102と、発光部102の発光を制御する制御部103と、発光部102が発光し測定対象空間S1を経た光(反射物R1で反射)を受光する受光部104と、受光部104が受光した信号V1を処理する演算部105と、を備える。
また、ガス測定装置100は、測定対象ガスの光吸収波長を示すリファレンス106と、発光部102が発光しリファレンス106を経た光を受光するリファレンス受光部107とを備える。
さらにガス測定装置100は、発光部102が発光した光を測定光101と、リファレンス106参照用の光108とに分配するビームスプリッター109、受光部104の検出値を増幅する増幅器110、リファレンス受光部107の検出値を増幅する増幅器111、増幅器110及び増幅器111の各出力信号をAD変換するAD変換器112等を備える。
発光部102は、発光素子として分布帰還型レーザダイオード(DFB−LD)を備える。
演算部105は、AD変換器112から、受光部104が受光したガスG1の吸収波長及び非吸収波長に亘る受光信号時系列データを得る。
演算部105は、AD変換器112から、リファレンス受光部107が受光したガスG1の吸収波長及び非吸収波長に亘るリファレンス受光信号時系列データを得る。
FIG. 5 shows a configuration diagram of an example of the gas measuring device according to the present invention.
As shown in FIG. 5, the gas measuring device 100 includes a light emitting unit 102 that emits light (measurement light 101) for detecting the measurement target gas G1, a control unit 103 that controls the light emission of the light emitting unit 102, and a light emitting unit. It includes a light receiving unit 104 that emits light from 102 and receives light (reflected by the reflecting object R1) that has passed through the measurement target space S1, and a calculation unit 105 that processes the signal V1 received by the light receiving unit 104.
Further, the gas measuring device 100 includes a reference 106 indicating the light absorption wavelength of the gas to be measured, and a reference light receiving unit 107 that emits light from the light emitting unit 102 and receives light that has passed through the reference 106.
Further, the gas measuring device 100 includes a beam splitter 109 that distributes the light emitted by the light emitting unit 102 into the measurement light 101 and the light 108 for reference to the reference 106, an amplifier 110 that amplifies the detected value of the light receiving unit 104, and a reference light receiving unit. An amplifier 111 that amplifies the detected value of 107, an AD converter 112 that AD-converts each output signal of the amplifier 110 and the amplifier 111, and the like are provided.
The light emitting unit 102 includes a distributed feedback type laser diode (DFB-LD) as a light emitting element.
The calculation unit 105 obtains time-series data of the light-receiving signal over the absorption wavelength and the non-absorption wavelength of the gas G1 received by the light-receiving unit 104 from the AD converter 112.
The calculation unit 105 obtains time-series data of the reference light receiving signal over the absorption wavelength and the non-absorption wavelength of the gas G1 received by the reference light receiving unit 107 from the AD converter 112.

リファレンス106は、測定対象そのものや測定対象が反応する波長とおなじ波長で応答する別の物質や構造物とされる。例えばリファレンス106としては、測定対象の物質を封じ込めたガスセルを使用できる。
リファレンス受光信号時系列データに確実に負のピークa1があるように、制御部103は、リファレンス受光部107の受光信号のフィードバックを得て、電流制御部113を制御して発光部102に矩形波電流を入力することで、発光部102が発光する光の波長に測定対象ガスG1の吸収波長及び非吸収波長に亘る変化を与える。
その間、制御部103は温度制御部114を制御して発光部102の温度を一定に保つ。温度制御部114にペルチェ素子などの温調素子が含まれる。
Reference 106 is the measurement target itself or another substance or structure that responds at the same wavelength as the wavelength with which the measurement target reacts. For example, as the reference 106, a gas cell containing the substance to be measured can be used.
The control unit 103 obtains the feedback of the light-receiving signal of the reference light-receiving unit 107 and controls the current control unit 113 so that the reference light-receiving signal time-series data has a negative peak a1. By inputting a current, the wavelength of the light emitted by the light emitting unit 102 is changed over the absorption wavelength and the non-absorption wavelength of the measurement target gas G1.
During that time, the control unit 103 controls the temperature control unit 114 to keep the temperature of the light emitting unit 102 constant. The temperature control unit 114 includes a temperature control element such as a Peltier element.

演算部105は、受光部104が受光した吸収波長の光の受光信号及び非吸収波長の光の受光信号(受光信号時系列データ)に基づき、測定対象ガスG1の濃度厚み積(下記d・c)を算出する。
各機能ブロック(演算部105、制御部103、温度制御部114、及び電流制御部113)は、例えば、CPU(Central Processing Unit)がROM(Read Only Memory)、RAM(Random Access Memory)、外部記憶装置(例えば、フラッシュメモリやハードディスク)に記憶された制御プログラムや各種データを参照することによって実現される。但し、各機能ブロックの一部又は全部は、CPUによる処理に代えて、又は、これと共に、DSP(Digital Signal Processor)による処理によって実現されてもよい。又、同様に、各機能ブロックの一部又は全部は、ソフトウェアによる処理に代えて、又は、これと共に、専用のハードウェア回路による処理によって実現されてもよい。
演算部105の算出方式の例を以下に挙げる。
The calculation unit 105 is based on the light receiving signal of the light of the absorption wavelength received by the light receiving unit 104 and the light receiving signal of the light of the non-absorption wavelength (light receiving signal time series data), and the concentration thickness product of the gas G1 to be measured (the following d.c.). ) Is calculated.
In each functional block (calculation unit 105, control unit 103, temperature control unit 114, and current control unit 113), for example, the CPU (Central Processing Unit) has a ROM (Read Only Memory), a RAM (Random Access Memory), and an external storage. It is realized by referring to the control program and various data stored in the device (for example, flash memory or hard disk). However, a part or all of each functional block may be realized by processing by a DSP (Digital Signal Processor) instead of or in combination with the processing by the CPU. Similarly, a part or all of each functional block may be realized by processing by a dedicated hardware circuit instead of or together with processing by software.
An example of the calculation method of the calculation unit 105 is given below.

(2値差分方式)
図3Cに示すように、負のピークa1の受光信号V(λ2)と、正のピークa2の受光信号V(λ1)との差分V(λ2)/V(λ1)に基づき測定対象ガスの濃度厚み積を算出する。受光信号V(λ1)は受光部104が受光した吸収波長λ1の光の受光信号に相当し、受光信号V(λ2)は受光部104が受光した非吸収波長λ2の光の受光信号に相当するから、従来の差分吸収法(DIAL,DOAS)と同様に濃度厚み積を算出する。
すなわち、次のようにランベルトベールの法則に基づいて測定対象の吸収帯の信号と非吸収帯の信号の差分でえられる信号から濃度厚み積を算出する方法を実施する。今、測定光101の光路上に測定対象ガスG1が存在しているものと仮定する。吸収波長λ1のレーザー光は、測定対象ガスG1によく吸収され、測定対象ガスG1中を透過した場合吸収波長λ1のレーザー光の強度は、Lambert−Beerの次式1で以下のように表される。
(Bivalent difference method)
As shown in FIG. 3C, the concentration of the gas to be measured is based on the difference V (λ2) / V (λ1) between the received signal V (λ2) of the negative peak a1 and the received signal V (λ1) of the positive peak a2. Calculate the thickness product. The light receiving signal V (λ1) corresponds to the light receiving signal of the light of the absorption wavelength λ1 received by the light receiving unit 104, and the light receiving signal V (λ2) corresponds to the light receiving signal of the light of the non-absorption wavelength λ2 received by the light receiving unit 104. From this, the concentration-thickness product is calculated in the same manner as the conventional differential absorption method (DIAL, DOAS).
That is, the method of calculating the concentration-thickness product from the signal obtained by the difference between the signal in the absorption band and the signal in the non-absorption band to be measured is carried out based on Lambertbert's law as follows. Now, it is assumed that the gas G1 to be measured exists on the optical path of the measurement light 101. When the laser light having an absorption wavelength λ1 is well absorbed by the measurement target gas G1 and passes through the measurement target gas G1, the intensity of the laser light having an absorption wavelength λ1 is expressed by the following equation 1 of Lambert-Beer as follows. To.

It=Ii×exp(−a・p・d・c)×α・・・式1
ここで、 It:レーザー光の受信強度
Ii:レーザー光の発信強度
a:吸収係数(atm-1・m-1
p:気体圧力(atm)
d:レーザー光が被検出ガス中を透過する長さ(m)
c:測定対象ガスの濃度(ppm)
α:背景におけるレーザー光の散乱係数
従って、測定対象ガスG1の濃度厚み積d・cは吸収波長λ1のレーザー光に付いては、次式2で表される。
It = Ii x exp (-a, p, d, c) x α ... Equation 1
Here, It: laser light reception intensity Ii: laser light transmission intensity a: absorption coefficient (atm -1 · m -1 )
p: Gas pressure (atm)
d: Length (m) through which the laser beam passes through the gas to be detected.
c: Concentration of gas to be measured (ppm)
α: Scattering coefficient of laser light in the background Therefore, the concentration-thickness product d · c of the gas G1 to be measured is expressed by the following equation 2 for the laser light having the absorption wavelength λ1.

Figure 0006756999

ここで、各レーザー光に関する数値については、最後尾に添字の1または2を付けて表示する。
Figure 0006756999

Here, the numerical values related to each laser beam are displayed by adding a subscript 1 or 2 at the end.

一方、非吸収波長λ2のレーザー光は、測定対象ガスG1がレーザー光の通過の途中に発生していたとしても、吸収波長λ1のレーザー光に比較して吸収率が小さく、よく透過する。従って、レーザー光の通過途中に測定対象ガスG1があってもレーザー光の強度は殆ど影響を受けない場合を想定できる。そこで、各レーザー光に対する送信側と受信側のおけるレーザー光の強度の差が、測定対象ガスG1の濃度厚み積に応じて生じると考えるのである。以上の処理が基本であるが、最も簡単な処理系は以下の様に構成できる。ここで、吸収波長λ1のレーザー光が測定対象ガスG1に吸収されて、弱まったレーザー光の強度It1を検出し、さらに非吸収波長λ2のレーザー光が、測定対象ガスG1に若干吸収されて弱まったレーザー光の強度It2を検出する。非吸収波長λ2のレーザー光に対しては、その発信側強度、及び受信側強度に大きな差が生じない場合(散乱係数がほぼ1の場合)は、Ii2≒It2が成立する。さらに発信側におけるλ1、λ2のレーザー光の強度比K=Ii1/Ii2を1とすると、Ii1=Ii2であるから、(Ii1−It1)/Ii1=(It2−It1)/It2となり、これを用いて、式2に適応することによりd・cを算出することができる。なお、ここで、It2は背景についての情報出力であり、(It2−It1)とすることによって測定対象ガスG1の濃度厚み積についての情報のみを出力することが可能となるのである。さらに、It2で除算しているのは、正規化処理である。
以上の処理を実施するために、演算部105は、制御部103による矩形波電流の入力タイミング信号との同期と、図2に示すような矩形波電流の入力に伴う発光部102が発光する光の波長の時間変化特性データの参照とが可能にされていることが好ましい。
なお、SN向上のために、矩形波電流の入力と受光信号の取得を所定時間中に複数回実行し、その全部又は一部に相当する複数回分の受光信号に基づき、例えばその平均値を算出するなどして、濃度厚み積を算出してもよい。
On the other hand, the laser light having the non-absorption wavelength λ2 has a smaller absorption rate than the laser light having the absorption wavelength λ1 and is well transmitted even if the gas G1 to be measured is generated in the middle of the passage of the laser light. Therefore, it can be assumed that the intensity of the laser light is hardly affected even if the gas G1 to be measured is present in the middle of passing the laser light. Therefore, it is considered that the difference in the intensity of the laser light between the transmitting side and the receiving side with respect to each laser light is generated according to the concentration-thickness product of the gas G1 to be measured. The above processing is basic, but the simplest processing system can be configured as follows. Here, the laser light having an absorption wavelength λ1 is absorbed by the measurement target gas G1 to detect the weakened laser light intensity It1, and the laser light having a non-absorption wavelength λ2 is slightly absorbed by the measurement target gas G1 and weakened. The intensity It2 of the laser beam is detected. For laser light having a non-absorption wavelength λ2, Ii2≈It2 holds when there is no significant difference between the intensity on the transmitting side and the intensity on the receiving side (when the scattering coefficient is approximately 1). Furthermore, assuming that the intensity ratio K = Ii1 / Ii2 of the laser light of λ1 and λ2 on the transmitting side is 1, then Ii1 = Ii2, so (Ii1-It1) / Ii1 = (It2-It1) / It2, which is used. Therefore, d · c can be calculated by applying to Equation 2. Here, It2 is an information output about the background, and by setting it as (It2-It1), it is possible to output only the information about the concentration-thickness product of the gas G1 to be measured. Furthermore, what is divided by It2 is the normalization process.
In order to carry out the above processing, the calculation unit 105 synchronizes with the input timing signal of the square wave current by the control unit 103, and the light emitted by the light emitting unit 102 due to the input of the square wave current as shown in FIG. It is preferable that the time-varying characteristic data of the wavelength of the above can be referred to.
In order to improve the SN, the input of the square wave current and the acquisition of the received light signal are executed a plurality of times in a predetermined time, and for example, the average value is calculated based on the received signals for a plurality of times corresponding to all or a part thereof. You may calculate the concentration-thickness product by doing so.

(積分方式)
演算部105は、図6Aに示すようにリファレンス受光信号時系列データを、吸収波長の光を受光する吸収線受光期間t1で積分する。例えば、図6Aに示すようにグラフの落ち込み相当分の面積を算出対象とし、積分値を得る。これを「リファレンス吸収帯積分値Ar」とする。
また、演算部105は、図6Aに示すようにリファレンス受光信号時系列データを、非吸収波長の光を受光する非吸収線受光期間t2で積分し積分値を得る。これを「リファレンス非吸収帯積分値Nr」とする。
演算部105は、図6Bに示すように受光信号時系列データを、吸収波長の光を受光する吸収線受光期間t3で積分する。上記と同様に、図6Bに示すようにグラフの落ち込み相当分の面積を算出対象とし、積分値を得る。これを「測定対象吸収帯積分値As」とする。
また、演算部105は、図6Bに示すように受光信号時系列データを、非吸収波長の光を受光する非吸収線受光期間t4で積分し積分値を得る。これを「測定対象非吸収帯積分値Ns」とする。
演算部105は、各値Ar,Nr,As,Nsとリファレンス106の濃度厚み積とに基づき、測定対象ガスG1の濃度厚み積を算出する。その算出式の一例は次のとおりである。
(測定対象ガスG1の濃度厚み積)=(リファレンスの濃度厚み積)×(Ar/Nr)×(As/Ns)
上記2値差分方式よりデータ数が多くなるため、S/Nを向上することができる。
なお、ここでも、SN向上のために、矩形波電流の入力と受光信号の取得を所定時間中に複数回実行し、その全部又は一部に相当する複数回分の受光信号に基づき、例えばその平均値を算出するなどして、濃度厚み積を算出してもよい。
(Integral method)
As shown in FIG. 6A, the calculation unit 105 integrates the reference light receiving signal time series data in the absorption line light receiving period t1 for receiving the light of the absorption wavelength. For example, as shown in FIG. 6A, the area corresponding to the dip in the graph is set as the calculation target, and the integrated value is obtained. This is referred to as "reference absorption band integral value Ar".
Further, as shown in FIG. 6A, the calculation unit 105 integrates the reference light receiving signal time series data in the non-absorption line light receiving period t2 for receiving light of the non-absorption wavelength to obtain an integrated value. This is referred to as "reference non-absorption band integral value Nr".
As shown in FIG. 6B, the calculation unit 105 integrates the light receiving signal time series data in the absorption line light receiving period t3 for receiving the light of the absorption wavelength. In the same manner as described above, as shown in FIG. 6B, the area corresponding to the dip in the graph is set as the calculation target, and the integrated value is obtained. This is referred to as "measurement target absorption band integral value As".
Further, as shown in FIG. 6B, the calculation unit 105 integrates the received signal time series data in the non-absorption line light receiving period t4 for receiving light having a non-absorbing wavelength to obtain an integrated value. This is referred to as "measurement target non-absorption band integral value Ns".
The calculation unit 105 calculates the concentration-thickness product of the gas G1 to be measured based on the respective values Ar, Nr, As, Ns and the concentration-thickness product of the reference 106. An example of the calculation formula is as follows.
(Concentration-thickness product of gas G1 to be measured) = (Concentration-thickness product of reference) × (Ar / Nr) × (As / Ns)
Since the number of data is larger than that of the binary difference method, the S / N can be improved.
Also here, in order to improve the SN, the input of the square wave current and the acquisition of the received light signal are executed a plurality of times in a predetermined time, and based on the received signals for a plurality of times corresponding to all or a part thereof, for example, the average thereof. The density-thickness product may be calculated by calculating a value or the like.

なお、リファレンス106に基づくデータを演算に使用しない場合は、これを得るための要素は不要である。また、図5に示すような反射物R1からの反射光を受光する装置形態に限らず、図7に示すような投光ユニット120と、受光ユニット121に分かれた装置形態など、発光部102と受光部104とが測定対象空間S1を挟んで対向配置される装置形態であってもよい。
また、図5に示すように、発光部102が発光する光(測定光101)で測定対象空間S1を走査する走査機構115を備えるものとしもよい。走査機構115は、出射及び受光する測定光101を反射するミラー115aとこれを回転駆動する駆動部115bとを有する。ミラー115aとしては、板状のものや断面多角形状で3面以上の反射面を有した多面鏡(ポリゴンミラー)などが一又は複数適用される。駆動部115bは、ミラー115aを回転させるアクチュエーター(モーター)と、その駆動回路を有し、制御部103からの制御信号に基づきミラー115aを回転させる。
走査機構115により、1次元的、2次元的な濃度厚み積の分布を測定することができる。
When the data based on the reference 106 is not used for the calculation, the element for obtaining the data is unnecessary. Further, the device form is not limited to the device form for receiving the reflected light from the reflecting object R1 as shown in FIG. 5, and the light emitting unit 102 includes a device form divided into a light projecting unit 120 and a light receiving unit 121 as shown in FIG. The light receiving unit 104 may be arranged so as to face each other with the measurement target space S1 in between.
Further, as shown in FIG. 5, a scanning mechanism 115 that scans the measurement target space S1 with the light emitted by the light emitting unit 102 (measurement light 101) may be provided. The scanning mechanism 115 includes a mirror 115a that reflects the measurement light 101 that is emitted and received, and a driving unit 115b that rotationally drives the mirror 115a. As the mirror 115a, one or a plurality of plate-shaped mirrors, a multi-sided mirror (polygon mirror) having a polygonal cross section and three or more reflecting surfaces, or the like is applied. The drive unit 115b has an actuator (motor) for rotating the mirror 115a and a drive circuit thereof, and rotates the mirror 115a based on a control signal from the control unit 103.
The scanning mechanism 115 can measure the one-dimensional and two-dimensional distribution of the concentration-thickness product.

次に、演算部105が行う測定エラー判定につき説明する。
受光信号時系列データを表すグラフ形状は、光源の波長変化(図2)と、測定対象ガスの光吸収波長特性によって決まるので、図8Aに示すようなフラットから図8Bに示すような発光波長が吸収波長を通過するときに落ち込む形状が想定される。図8Aはガスによる光吸収が無く正常の場合、図8Bはガスによる光吸収が有り正常の場合である。
ガスの光吸収による負のピークa1における受光強度は、ガスの濃度厚み積によって様々に変わり得る。
しかし、時間軸上で吸収線位置a1以外の位置(例えば図8Cのa4)で変化量は、ガスの有無、濃度厚み積によっては大きく変化しない。
このようなガスの有無、濃度厚み積によっては大きく変化しない時間軸上の位置(例えば図8Cのa4)で、大きく波形の乱れがあれば、測定光の出射先で測定対象ガスG1以外の環境要因等による波長の乱れである可能性が高いので、測定対象ガスG1の測定結果も信頼性が低い。
したがって、演算部105は、時間軸上で吸収線位置a1以外の位置(例えば図8Cのa4)の受光信号に基づき、その変化量が規定値を上回る場合、測定エラーと判定とする。
Next, the measurement error determination performed by the calculation unit 105 will be described.
Since the graph shape representing the received signal time series data is determined by the wavelength change of the light source (FIG. 2) and the light absorption wavelength characteristics of the gas to be measured, the emission wavelength from the flat as shown in FIG. 8A to the emission wavelength as shown in FIG. 8B can be changed. A shape that drops when passing through the absorption wavelength is assumed. FIG. 8A shows a normal case without light absorption by gas, and FIG. 8B shows a normal case with light absorption by gas.
The light receiving intensity at the negative peak a1 due to the light absorption of the gas can vary depending on the concentration and thickness product of the gas.
However, the amount of change at a position other than the absorption line position a1 on the time axis (for example, a4 in FIG. 8C) does not change significantly depending on the presence or absence of gas and the concentration-thickness product.
If there is a large disturbance in the waveform at a position on the time axis (for example, a4 in FIG. 8C) that does not change significantly depending on the presence or absence of such a gas and the concentration-thickness product, an environment other than the gas to be measured G1 is emitted at the emission destination of the measurement light. Since there is a high possibility that the wavelength is disturbed due to factors or the like, the measurement result of the gas G1 to be measured is also low in reliability.
Therefore, the calculation unit 105 determines that a measurement error occurs when the amount of change exceeds the specified value based on the received signal at a position other than the absorption line position a1 on the time axis (for example, a4 in FIG. 8C).

次に、演算部105が行う距離の測定について説明する。
距離測定原理は、TOF法(Time Of Flight:飛行時間測定法)による。図9に模式的に示すように出射した光が反射物R1で反射し、 戻ってくるまでの時間τに基づき、ガス測定装置100と反射物R1との間の距離L(発光部102から受光部104までの光路距離だと2L)を次式により測定する。
L=(光速)×(τ/2)
以上のように、演算部105は、発光部102の発光タイミングと受光部104の受光タイミングの時差τに基づき、発光部102から受光部104までの光路距離を測定する。なお、図7に示すような発光部102と受光部104とが測定対象空間S1を挟んで対向配置される装置形態の場合は、上記式で2Lが空間S1を横断する距離に相当する。以上のようにして都度測定した距離又は既知の距離により基づき測定対象ガスG1の単位長さあたりの「濃度厚み積」、すなわち、濃度(平均濃度)が算出可能である。したがって、測定対象の空間S1における測定光の光路長が既知又は都度測定される場合は、「濃度厚み積」を単位長さあたりの「濃度厚み積」、すなわち、濃度(平均濃度)への換算値で算出してもよい。
2f方式でも原理的には可能だが、吸収線近傍で波長を変調させる必要があるため、振幅が非常に小さく、距離測定が難しくなる。
一方、本発明によればパルス発光が可能なため、2f検波方式と異なり、回路にクロック機能を持たせれば、1回の出射で距離を測定することができ、回路構成も簡易に距離測定が実現できる。
Next, the distance measurement performed by the calculation unit 105 will be described.
The distance measurement principle is based on the TOF method (Time Of Flight). As schematically shown in FIG. 9, the emitted light is reflected by the reflector R1, and the distance L between the gas measuring device 100 and the reflector R1 (received from the light emitting unit 102) is based on the time τ until it returns. The optical path distance to the part 104 is 2L), which is measured by the following equation.
L = (speed of light) x (τ / 2)
As described above, the calculation unit 105 measures the optical path distance from the light emitting unit 102 to the light receiving unit 104 based on the time difference τ between the light emitting timing of the light emitting unit 102 and the light receiving timing of the light receiving unit 104. In the case of a device in which the light emitting unit 102 and the light receiving unit 104 are arranged so as to face each other with the measurement target space S1 as shown in FIG. 7, 2L corresponds to the distance across the space S1 in the above equation. The "concentration-thickness product" per unit length of the gas G1 to be measured, that is, the concentration (average concentration) can be calculated based on the distance measured each time or the known distance as described above. Therefore, when the optical path length of the measurement light in the space S1 to be measured is known or measured each time, the "concentration thickness product" is converted into the "concentration thickness product" per unit length, that is, the concentration (average density). It may be calculated by a value.
Although it is possible in principle with the 2f method, since it is necessary to modulate the wavelength near the absorption line, the amplitude is very small and distance measurement becomes difficult.
On the other hand, according to the present invention, pulse light emission is possible, so unlike the 2f detection method, if the circuit has a clock function, the distance can be measured with one emission, and the circuit configuration can easily measure the distance. realizable.

以上の実施形態のガス測定装置によれば、発光部102に、落差のある2つの値の間で急峻に変化する電流を入力することで、DFB−LDの応答特性を利用して、発光部102が発光する光の波長に測定対象ガスG1の吸収波長及び非吸収波長に亘る変化を与えるので、比較的簡単な構成で発光及び受光検出、濃度厚み積の算出が可能であり、矩形波電流を一定にすることで発光の出力を一定に保つことができ、これにより発光の出力を一定に保った状態で吸収波長及び非吸収波長に亘り波長を変えて出力することができる。
装置構成も2f検波方式と同等以上に簡易あり、さらに光路距離の測定も可能である。
レーザー光源の駆動制御のみで吸収波長及び非吸収波長が発振可能あり、検出器も一つで測定ができるため、非常に簡易な構成で、ガスの濃度厚み積の演算が実現できる。
また、パルス発光の方がCW発光に比べ、アイセーフティー状態を保ちながらハイパワーで出力が可能となるため、測定可能距離やSN向上に有利に働く。
図1に示すように所定周期のハルス波をDFB−LDに入力することで、図3Bに示すように周期性の受光信号時系列データが得られる。一つの矩形部aを対象に演算するにとどまらず、連続する複数の矩形部aを対象に演算し、それらの演算結果に基づき測定結果を算出することで、S/Nを改善することがきる。その際、上述したエラー判定された矩形部aを演算対象から除外することで、さらにS/Nを改善することがきる。
According to the gas measuring device of the above embodiment, the light emitting unit 102 utilizes the response characteristics of the DFB-LD by inputting a current that changes sharply between two values having a head. Since the wavelength of the light emitted by the 102 is changed over the absorption wavelength and the non-absorption wavelength of the gas G1 to be measured, it is possible to detect light emission and light reception and calculate the density thickness product with a relatively simple configuration, and the rectangular wave current. The output of light emission can be kept constant by making the output constant, so that the output of light emission can be changed and output over the absorption wavelength and the non-absorption wavelength while the output of light emission is kept constant.
The device configuration is as simple as the 2f detection method, and the optical path distance can be measured.
Since absorption wavelength and non-absorption wavelength can be oscillated only by driving control of the laser light source and measurement can be performed with one detector, it is possible to calculate the concentration and thickness product of gas with a very simple configuration.
Further, compared with CW light emission, pulse light emission enables output with high power while maintaining the eye safety state, which is advantageous in improving the measurable distance and SN.
By inputting a Hals wave having a predetermined period to the DFB-LD as shown in FIG. 1, periodic received signal time series data can be obtained as shown in FIG. 3B. It is possible to improve the S / N by calculating not only one rectangular portion a but also a plurality of continuous rectangular portions a and calculating the measurement result based on the calculation results. .. At that time, the S / N can be further improved by excluding the above-mentioned error-determined rectangular portion a from the calculation target.

本発明は、ガス測定及びガス測定装置に利用することができる。 The present invention can be used for gas measurement and gas measurement equipment.

100 ガス測定装置
101 測定光
102 発光部
103 制御部
104 受光部
105 演算部
106 リファレンス
107 リファレンス受光部
109 ビームスプリッター
110 増幅器
111 増幅器
112 AD変換器
113 電流制御部
114 温度制御部
120 投光ユニット
121 受光ユニット
G1 測定対象ガス
R1 反射物
S1 測定対象空間
t1 吸収線受光期間
t2 非吸収線受光期間
t3 吸収線受光期間
t4 非吸収線受光期間
λ1 吸収波長
λ2 非吸収波長
100 Gas measuring device 101 Measurement light 102 Light emitting unit 103 Control unit 104 Light receiving unit 105 Calculation unit 106 Reference 107 Reference light receiving unit 109 Beam splitter 110 Amplifier 111 Amplifier 112 AD converter 113 Current control unit 114 Temperature control unit 120 Light emitting unit 121 Light receiving Unit G1 Measurement target gas R1 Reflector S1 Measurement target space t1 Absorption line light receiving period t2 Non-absorption line light receiving period t3 Absorption line light receiving period t4 Non-absorption line light receiving period λ1 Absorption wavelength λ2 Non-absorption wavelength

Claims (14)

測定対象ガスを検出するための光を発光する発光部と、
前記発光部の発光を制御する制御部と、
前記発光部が発光し空間を経た光を受光する受光部と、
前記受光部が受光した信号を処理する演算部と、を備えて前記空間における測定対象ガスの濃度厚み積を算出するガス測定装置であって、
前記測定対象ガスの光吸収波長を示すリファレンスと、前記発光部が発光し前記リファレンスを経た光を受光するリファレンス受光部と、を備え、
前記制御部は、前記リファレンス受光部の受光信号のフィードバックを得て、前記発光部に矩形波電流を入力することで、前記発光部が発光する光の波長に前記測定対象ガスの吸収波長及び非吸収波長に亘る変化を与え、
前記演算部は、前記受光部が受光した前記吸収波長の光の受光信号及び前記非吸収波長の光の受光信号に基づき、前記測定対象ガスの濃度厚み積を算出するガス測定装置。
A light emitting part that emits light to detect the gas to be measured,
A control unit that controls the light emission of the light emitting unit,
A light receiving unit that emits light and receives light that has passed through space,
A gas measuring device comprising a calculation unit for processing a signal received by the light receiving unit and calculating the concentration-thickness product of the gas to be measured in the space.
A reference indicating the light absorption wavelength of the gas to be measured and a reference light receiving unit that emits light from the light emitting unit and receives light that has passed through the reference are provided.
The control unit obtains the feedback of the light receiving signal of the reference light receiving unit and inputs a rectangular wave current to the light emitting unit, so that the wavelength of the light emitted by the light emitting unit is the absorption wavelength of the gas to be measured and the non-absorption wavelength of the gas to be measured. Gives a change over the absorption wavelength,
The calculation unit is a gas measuring device that calculates the concentration-thickness product of the gas to be measured based on the light receiving signal of the light of the absorption wavelength received by the light receiving unit and the light receiving signal of the light of the non-absorption wavelength.
前記演算部は、前記受光部が受光した前記吸収波長の光の受光信号と、前記非吸収波長の光の受光信号との差分に基づき測定対象ガスの濃度厚み積を算出する請求項1に記載のガス測定装置。 The first aspect of claim 1, wherein the calculation unit calculates the concentration-thickness product of the gas to be measured based on the difference between the light receiving signal of the light of the absorption wavelength received by the light receiving unit and the light receiving signal of the light of the non-absorption wavelength. Gas measuring device. 前記演算部は、前記受光部が受光した前記吸収波長及び前記非吸収波長に亘る受光信号時系列データを得て、当該受光信号時系列データに基づき、前記測定対象ガスの濃度厚み積を算出する請求項1に記載のガス測定装置。 The calculation unit obtains time-series data of the light-receiving signal over the absorption wavelength and the non-absorption wavelength received by the light-receiving unit, and calculates the concentration-thickness product of the gas to be measured based on the time-series data of the light-receiving signal. The gas measuring device according to claim 1. 前記演算部は、受光信号時系列データを、前記吸収波長の光を受光する吸収線受光期間で積分し当該積分値に基づき、前記測定対象ガスの濃度厚み積を算出する請求項3に記載のガス測定装置。 The third aspect of claim 3, wherein the calculation unit integrates the time-series data of the received signal in the absorption line light receiving period for receiving the light of the absorption wavelength, and calculates the concentration-thickness product of the gas to be measured based on the integrated value. Gas measuring device. 前記演算部は、前記非吸収波長の光を受光する非吸収線受光期間で積分し当該積分値と、前記吸収線受光期間の積分値とに基づき、前記測定対象ガスの濃度厚み積を算出する請求項4に記載のガス測定装置。 The calculation unit integrates in the non-absorption line light receiving period for receiving light of the non-absorption wavelength, and calculates the concentration-thickness product of the gas to be measured based on the integrated value and the integrated value in the absorption line light receiving period. The gas measuring device according to claim 4. 前記演算部は、前記非吸収波長の光の受光信号に基づき、測定エラーを判定する請求項1から請求項4のうちいずれか一に記載のガス測定装置。 The gas measuring device according to any one of claims 1 to 4, wherein the calculation unit determines a measurement error based on a received signal of light having a non-absorption wavelength. 前記演算部は、前記受光部が受光した前記吸収波長の光の受光信号と、前記リファレンス受光部が受光した前記吸収波長の光の受光信号とに基づき測定対象ガスの濃度厚み積を算出する請求項に記載のガス測定装置。 The calculation unit calculates the concentration-thickness product of the gas to be measured based on the light receiving signal of the absorption wavelength light received by the light receiving unit and the light receiving signal of the absorption wavelength light received by the reference light receiving unit. Item 1. The gas measuring device according to Item 1 . 前記演算部は、前記受光部が受光した前記吸収波長及び前記非吸収波長に亘る受光信号時系列データ、及び前記リファレンス受光部が受光した前記吸収波長及び前記非吸収波長に亘るリファレンス受光信号時系列データを得て、当該受光信号時系列データと当該リファレンス受光信号時系列データとに基づき、前記測定対象ガスの濃度厚み積を算出する請求項に記載のガス測定装置。 The calculation unit includes time-series data of the light-receiving signal over the absorption wavelength and the non-absorption wavelength received by the light-receiving unit, and time-series of the reference light-receiving signal over the absorption wavelength and the non-absorption wavelength received by the reference light-receiving unit. to obtain data, based on the said received signal time-series data and the reference received light signal time-series data, gas measuring device according to claim 1 for calculating the concentration thickness product of the measurement target gas. 前記制御部は、前記発光部の温度を一定に制御する請求項1から請求項のうちいずれか一に記載のガス測定装置。 The gas measuring device according to any one of claims 1 to 8 , wherein the control unit controls the temperature of the light emitting unit to be constant. 前記演算部は、前記制御部による前記矩形波電流の入力タイミング信号との同期と、前記矩形波電流の入力に伴う前記発光部が発光する光の波長の時間変化特性データの参照とが可能にされた請求項1から請求項のうちいずれか一に記載のガス測定装置。 The calculation unit can synchronize the input timing signal of the square wave current by the control unit and refer to the time change characteristic data of the wavelength of the light emitted by the light emitting unit due to the input of the square wave current. The gas measuring apparatus according to any one of claims 1 to 9 . 前記発光部の発光素子として分布帰還型レーザダイオード(DFB−LD)を備える請求項1から請求項10のうちいずれか一に記載のガス測定装置。 The gas measuring apparatus according to any one of claims 1 to 10 , further comprising a distributed feedback laser diode (DFB-LD) as a light emitting element of the light emitting unit. 前記演算部は、前記発光部の発光タイミングと前記受光部の受光タイミングの時差に基づき、前記発光部から前記受光部までの光路距離を測定する請求項1から請求項11のうちいずれか一に記載のガス測定装置。 The calculation unit corresponds to any one of claims 1 to 11 for measuring the optical path distance from the light emitting unit to the light receiving unit based on the time difference between the light emitting timing of the light emitting unit and the light receiving timing of the light receiving unit. The gas measuring device described. 前記発光部が発光する光で前記空間を走査する走査機構を備える請求項1から請求項12のうちいずれか一に記載のガス測定装置。 The gas measuring device according to any one of claims 1 to 12 , further comprising a scanning mechanism for scanning the space with light emitted by the light emitting unit. 前記発光部と、前記受光部とが前記空間を挟んで対向配置される請求項1から請求項12のうちいずれか一に記載のガス測定装置。 The gas measuring device according to any one of claims 1 to 12 , wherein the light emitting unit and the light receiving unit are arranged so as to face each other with the space interposed therebetween.
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