CN1033105A - The method and apparatus of gas detection - Google Patents
The method and apparatus of gas detection Download PDFInfo
- Publication number
- CN1033105A CN1033105A CN88107746A CN88107746A CN1033105A CN 1033105 A CN1033105 A CN 1033105A CN 88107746 A CN88107746 A CN 88107746A CN 88107746 A CN88107746 A CN 88107746A CN 1033105 A CN1033105 A CN 1033105A
- Authority
- CN
- China
- Prior art keywords
- laser
- absorption
- gas
- wavelength
- absorption cell
- 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
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N21/03—Cuvette constructions
- G01N21/031—Multipass arrangements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/08—Optical fibres; light guides
- G01N2201/084—Fibres for remote transmission
Abstract
Be used for detecting equipment in the absorption cell predetermined gas, conduct the absorption cell that outputs to of infrared laser light source, control conduction output changes between at least two wavelength in time, one of two wavelength are easier of gas absorption than another, the size of this wavelength after the conduction is corresponding to detected gas, the output of laser instrument may comprise two frequencies, and a light filter can make these two frequencies alternately pass through.On the other hand, the output of this laser instrument also can be single-frequency, and this frequency sweeping is crossed the frequency that gas absorbs easily.
Description
The present invention relates to the method and apparatus of a detected gas.
In oil, gas, chemicals, petrochemicals, mining industry and aquatic product, the concentration that can accurately and reliably monitor blast and toxic gas is very important, in these local poisonous or the accumulation of explosion gas or the safety that effusion can have a strong impact on factory.
Connecting gas sensor with light transmitting fiber is the technology that just has been suggested, it has compared several advantages with common galvanochemistry, Pellistor, semiconductor and flame ion detector, and these advantages comprise: chemical inertness, to insensitivity, anti-electromagnetic interference (EMI), high sensitivity, stability of poisoning and the security of operating in explosion environment.This sensor also can be used for the sensor-based system that separates, monitors the expense of required sensor to reduce multiple spot in the large-scale industrial production system.
The silicon light transmitting fiber can have been bought, but this fiber is only limited to and is used near infrared wavelength zone (0.8 μ m-1.8 μ m).This is because the silicon light transmitting fiber has quite high loss in ultraviolet, visible and middle infrared spectrum.But, all have harmonic wave to utilize these absorption bands in the light transmitting fiber detector with uniting absorption band ， And and having been proposed in the many common contaminants in near-infrared region.But, these absorption bands than a little less than the main absorption band of the gas molecule of middle infrared many, therefore, the gas concentration that detects the ppm level just needs long absorption light path, adopts long absorption light path then to need high-intensity light.In using, remote measurement just has the problems referred to above.The correction of sensor output also is a problem, because guarantee that the variation of sensor output should be only from the variation of tested gas concentration, this point is extremely important.
The objective of the invention is to provide a kind of equipment and method of detected gas, they have got rid of or have reduced the problem of above-mentioned existence.
The present invention proposes the equipment of predetermined gas in the detection absorption cell, it comprises an infrared laser light source; A control device, control from LASER Light Source send, through light transmitting fiber, to the light transmission of the sensor that connects with an absorption cell; The optical maser wavelength that this absorption cell absorbs changes between two wavelength in time at least, and one of these two wavelength are by said gas absorption, and another is difficult for by said gas absorption; A device that is used to detect gas described in the absorption cell to the absorption signal of described optical maser wavelength; And be used for device that the size of monitoring value is compared with the detected value of the said gas of absorption cell.
LASER Light Source can be a multi-mode laser light source, and its first pattern is at a described wavelength, and second pattern is at described another wavelength; A tunable filter is inserted between LASER Light Source and the absorption cell, and the light transmission control device is controlled the tuning of light filter, thereby makes the laser of first or second pattern alternately pass through absorption cell.LASER Light Source is a laser diode preferably, and it is thermal tuning, so that its strongest longitudinal mode is consistent with the absorption maximum frequency of gas.Light filter can be Fabry-Perot (Fobry-Perot) light filter, and its Free Spectral Range is less than the Free Spectral Range of laserresonator.
In another scheme, LASER Light Source is a tunable laser diodes, and absorption cell is directly passed through in its output, and has the device of a tuning laser wavelength, so that length scanning is crossed over the wavelength that said gas absorbs easily.This laser diode can be with two current drives that Sine Modulated is overlapping, and pick-up unit can comprise and therefore, provides a synchronizing indicator in the work of the frequency multiplication place of one of Sine Modulated frequency a second harmonic signal value and be proportional to described gas concentration.The frequency of laser diode can change by the temperature that changes diode current or change diode.
Now, Tong crosses the embodiment with reference to the accompanying drawings to describe the present invention for Li And.
Fig. 1 shows the absorption band in some common contaminants of near infrared spectrum district.
The uppermost figure of Fig. 2 is the absorption spectra of a tested gas, middle figure is the output spectrum of a commercially available laser diode, below figure be when not having the control input during the seeing through peak (solid line) and the predetermined control input arranged of Fabry-Perot filter Fabry-Perot filter see through peak (dotted line), show the position excursion that forms because of the control input through the peak.
Fig. 3 illustrates the γ of methane
2+ 2 γ
3The associating absorption spectrum.
Fig. 4 is the block scheme of gas sensor of the present invention.
Fig. 5 is illustrated among Fig. 4 the recording geometry of sensor output signal when absorption cell replaces emptying or be full of variable concentrations methane.
The sensor that Fig. 6 is illustrated among Fig. 4 changes with the output that methane concentration changes, and dotted line is pointed out the low blast limit of methane in the air.
The sensor of Fig. 7 presentation graphs 4 short and long-time in output signal when monitoring 40 τ methane in the absorption cell.
Fig. 8 is the synoptic diagram of the gas sensor of second embodiment of the present invention.
Fig. 9 illustrates the output that is obtained by Fig. 8 embodiment.
Figure 10 is illustrated in one and determines in the temperature range from alternately exporting that scheme shown in Figure 8 obtains.
Figure 11 illustrates sensor output among Fig. 8 embodiment and the relation between the detected gas concentration change.
By suitable selection with use commercially available thermal tuning laser diode, the present invention can detect majority of gas among Fig. 1, and higher energy is arranged than the output of light emitting diode and thermal light source, therefore use laser diode just can use the multipass absorption cell of long light path and the light transmitting fiber of growing.The present invention is based on utilize the differential absorption of the dusty gas of surveying different wave length that LASER Light Source is launched.LASER Light Source, radiation detector and the electric treatment device that is connected can spread out of to absorbing Chi And radiation delivery through light transmitting fiber away from absorption cell from absorption cell.Light transmitting fiber and remote absorption cell allow the restricted area of application of monitoring rugged surroundings, electrical noise environment and electric instrument and visual line measurement is impossible or the application in inconvenient area.
The near-infrared laser diode usually in the Free Spectral Range of laser diode resonator cavity the longitudinal mode with several discrete frequencies send radiation.Intermediate pattern among Fig. 2 illustrates the emission spectrum of a known laser diode, but this laser diode thermal tuning, so that one of its longitudinal mode is consistent with the survey gaseous absorption line.Figure above among Fig. 2 illustrates the absorption spectrum of the gas of surveying, if output optical alignment And and this collimated light beam of laser diode are entered one scan etalon (Fabry-Perot filter), the Free Spectral Range of this etalon is less than the Free Spectral Range of laser diode resonator cavity, this etalon can be tuning, with make it with the corresponding to mode of laser of gas absorption under resonance, if a square-wave voltage is applied on the control element, for example on the piezoelectric element of scanning standard tool, regulate the size of this voltage, so that entering etalon, the adjacent modes of a laser diode forms resonance (figure below among Fig. 2), then, this etalon alternately conversion between two moulds of laser.Because these two kinds of modes of laser only have a kind of by being surveyed gas absorption, thereby just can detect the existence and the concentration thereof of this gas.
By with laser diode be tuned to suitable wavelengths, may obtain very high selectivity owing to adopt differential absorption techniques and utilize single light emitting diode to detect two wavelength, thereby eliminated and the response of the detecting device relevant problem that is complementary.
Fig. 3 to Fig. 7 shows the embodiments of the invention that detect methane gas in the nitrogen.Fig. 3 provides the γ of methane
2+ 2 γ
3The associating band is at γ
2+ 2 γ
3Absorption maximum appears in 1.331 μ m places in the Q branch of associating band, referring to Fig. 4, a GaInAsp laser diode (1) (Lasertron, QLM1300SM) be chosen in 1.33/ μ m emission, carry out thermal tuning by power supply and temperature-control circuit (2), so that the strongest longitudinal mode of laser instrument and the γ of methane
2+ 2 γ
3The absorption maximum unanimity of the Q branch of band, collimated light beam passes through scanning standard tool (4) with micro objective (3) collimation in the output of laser diode.
The output ， And that takes out etalon with beam splitter (5) monitors with a Ge photodiode (6).One movably be placed on monitor photo-diode with reference to gas absorption cell (7) before, simplified the tuning step that makes the diode wavelength be transferred to absorption peak, controller (8) receives the input of self-servo mechanism (9), to reach fine tuning to etalon (4), servo control mechanism sequentially receives the feedback input of phase sensitive detector (10) and (11), and this phase sensitive detector is connected to detecting device (6) by prime amplifier (12).The output of monitoring detector (6) is by phase sensitive detector (10) and (11) synchronous detection under the higher modulation frequency of etalon sweep frequency and laser diode current.
Main beam is injected 50/125 μ m multimode optical fibre section (13) by etalon (4), this light transmitting fiber conducts this light beam to remote absorption cell (14) through gradient-index lens (15), the output of this absorption cell is injected another 50/125 μ m light transmitting fiber section (17) through lens (16), this light transmitting fiber is transmitted back to second Ge sense photodiode (18) with this signal, the output of this photodiode is amplified And phase sensitive detector (20) by prime amplifier (19), (21) exporting synchronous detection under two same frequencies with monitor photo-diode (6), the ratio of these two frequency outputs is proportional to the absorption of gas, therefore, be proportional to gas concentration.Be full of with reference to gas cell with concentration known gas, the output of monitor photo-diode (6) can be used for the correction of this system.
Said system detected methane with one meter long absorption cell of one way, and Fig. 5 provides the response of this system when absorption cell replaces emptying and fill variable concentrations methane, output signal to gas concentration in absorption cell map a calibration curve.As seen from Figure 6, the methane low concentration watered chant 0 τ time output is good linearity, be full of with 40 τ methane and absorb the output that Chi And monitored 10 hours, tested the stability of this system.The fluctuation of output signal and drift are less than 1%, as shown in Figure 7 during this.
Said system has good stable ， And and with this system of output continuous correction of monitor photo-diode (6), can keep stablizing for a long time.The energy of laser diode allows to use long light path multipass absorption cell, White absorption cell for example, to increase the length of light path, do not need with the cooling detecting device, thereby raising sensitivity, can make detecting device reach the sensitivity of 10ppm magnitude with the multipass absorption cell, sensor is suitable for should general application.
Fig. 8 provides a sensor blocks figure who is suitable for second-harmonic detection.The output of laser diode (22) focuses on lens (23) and (24) and enters light transmitting fiber (25), and be connected to White absorption cell (27) by gradient-index lens (26), absorption cell (27) contains the detected gas sample, the light that enters the White absorption cell repeatedly reflexes to gradient-index lens (28), and these lens are sent into light transmitting fiber (29) to this Shu Guang.Light by light transmitting fiber (29) conduction focuses on diode (31) by lens (30), and the output of diode is fed to lock-in amplifier (33) through prime amplifier (32).Lock-in amplifier (33) receives an input synchronously from modulating oscillator (34), this oscillator is also controlled power supply and temperature controller (35), the work of this controller (35) control laser diode (22), another temperature controller (36) is kept the stability of detecting device (31).
Power supply and temperature controller (35) control laser diode (22) so that its output wavelength is linear sweep, can reach by drive current or its temperature that changes laser diode (22).Modulating oscillator (34) produces two Sine Modulated W
1And W
2Overlap on the laser diode drive current, the output of sensor is at W
1Two frequency multiplication place synchronous detection.
When the wavelength slow scanning of laser diode is passed through to absorb line, can observe second harmonic signal.Select its level and smooth output to take out smooth thin portion so effectively, rather than from crossing over the result that absorption line laser length scanning draws, this result output signal as shown in Figure 9, the size of this signal represents that with arrow P P is proportional to the gas concentration at a frequency absorption line jumpy place.
Laser frequency can be controlled with temperature of regulating it or its electric current, but, with transformation temperature than come the controlled frequency can topped much bigger wavelength coverage with variable-current, like this, by changing temperature, the several gas absorption signal of observation are possible in single pass.Figure 10 has provided the output of the lock-in amplifier (33) of Fig. 8, makes figure And computing machine (38) record with registering instrument (37), and Fig. 7 has provided the output of lock-in amplifier when 30 ℃ of scanning.In illustrated embodiment, many spectral lines may appear in the spectrum, and this is because CH
4, H
2O, HF, NH
3, HB
rAnd CO
2Existence.This spectrum can use computing machine (38) to handle, and provides the concentration of various compositions.Secondary modulation W
2Has the effect of eliminating the issuable smooth interference fringe of absorption cell.
CH is pointed out in the test of carrying out
4, HF and H
2The minimum detectable concentration of O is respectively 50ppm-m, 100ppb-m and 50ppm-m.Figure 11 has provided the sensor curve of output of corresponding methane concentration, and from experimental data as can be seen, concentration its output in tens times of scopes all is linear.Owing to measure, the drift in sensor output is inappreciable, and the precision of sensor is by noise limit, rather than by the drift restriction.
At the above-mentioned light transmitting fiber of using in the experiment of Figure 11 for Fig. 8, be the 50/125 μ m light transmitting fiber of 2.5Km single mode fibre and 2.5Km.Because powerful application.This system may allow 10 decibels of (dB) magnitude energy losses, and when the optical element at absorption cell tarnished, this energy loss may occur.By optical fiber switch several absorption cells that are located at the different location are delivered in radiation, that also is possible, like this, just can form sensor network on large tracts of land, so that big quantity sensor is utilized same light source and detection system.
A shortcoming of the method for above-mentioned proposition is to need long light path in absorption cell, so that obtain high sensitivity, this will utilize the multipass absorption cell ， And and the vulnerable to pollution of accurate optical alignment, and it is also very heavy simultaneously.
Claims (8)
1, be used for detecting equipment in the absorption cell predetermined gas, it comprises an infrared laser light source; A light transmission control device, the light transmission of light transmitting fiber to the sensor that connects an absorption cell sent, passed through to control from LASER Light Source, the optical maser wavelength that this absorption cell absorbs changes between two wavelength in time at least, one of these two wavelength are by described gas absorption, and another wavelength is difficult for by described gas absorption; The device of the described wavelength laser signal of gas absorption described in detection absorption cell; And device that the size of monitoring value is compared with the detected value of gas described in the absorption cell.
2, according to the equipment of claim 1, it is characterized in that LASER Light Source is a multi-mode laser source, its first mould is surreptitiously to call on the bucktooth at the humorous Qu J of bucktooth capsule Huan haze ǔ ぃ to herd tunable filter of flat stone with ropes attached at the sides Huan haze ǔ and be inserted between LASER Light Source and the absorption cell, and tuning this light filter of light transmission control device makes first and second Mode for Laser alternately pass through absorption cell.
3, according to the equipment of claim 1 or 2, it is characterized in that LASER Light Source is a laser diode, it is thermal tuning, so that its strongest longitudinal mode is consistent with gas absorption maximum frequency.
4, according to claim 1,2 or 3 equipment, it is characterized in that light filter is the Fabry-Perot filter of a Free Spectral Range less than the Free Spectral Range of laserresonator.
5, according to the equipment of claim 1, it is characterized in that: LASER Light Source is a tunable laser diodes, and absorption cell is directly passed through in its output; The device that also has a tuning laser wavelength makes it to scan the frequency of crossing over the easy described wavelength that absorbs of described gas.
6, according to the equipment of claim 5, it is characterized in that: the electric current with two Sine Modulated of stack comes the driving laser diode, pick-up unit comprises the synchronizing indicator that a letter that is operated in one of two Sine Modulated frequencies is located frequently, therefore, the size of the second harmonic signal of generation is just in the absorption than described gas.
7, according to the equipment of claim 5 or 6, it is characterized in that: have a device that changes the laser diode frequency by the electric current that changes diode.
8,, it is characterized in that having a device that changes the frequency of laser diode by the temperature that changes diode according to the equipment of claim 5 or 6.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8722283 | 1987-09-22 | ||
| GB878722283A GB8722283D0 (en) | 1987-09-22 | 1987-09-22 | Gas detection |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1033105A true CN1033105A (en) | 1989-05-24 |
Family
ID=10624192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN88107746A Pending CN1033105A (en) | 1987-09-22 | 1988-09-22 | The method and apparatus of gas detection |
Country Status (5)
| Country | Link |
|---|---|
| CN (1) | CN1033105A (en) |
| AU (1) | AU2429488A (en) |
| GB (1) | GB8722283D0 (en) |
| WO (1) | WO1989003028A1 (en) |
| ZA (1) | ZA887103B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1297814C (en) * | 2001-03-29 | 2007-01-31 | 日本酸素株式会社 | Method and equipment for determining nitrogen in gas |
| CN100491973C (en) * | 2006-10-11 | 2009-05-27 | 中国科学院上海微系统与信息技术研究所 | One-chip double core or multiple core semiconductor laser gas sensor and its making and using method |
| CN103776799A (en) * | 2012-10-28 | 2014-05-07 | 天津奇谱光电技术有限公司 | Hydrogen sulfide gas sensing equipment |
| CN103776792A (en) * | 2012-10-28 | 2014-05-07 | 天津奇谱光电技术有限公司 | Gas sensing equipment employing tunable Fabry-Perot filter |
| CN104237161A (en) * | 2014-10-15 | 2014-12-24 | 中国科学院合肥物质科学研究院 | Multi-component real-time online remote monitoring device and method for coal spontaneous combustion indicator gas |
| CN104596986A (en) * | 2014-01-14 | 2015-05-06 | 王胤 | Spectrum analysis method and spectrum analysis system |
| CN106461539A (en) * | 2013-12-05 | 2017-02-22 | G·P·克林克翰莫 | Spectrophotometer with variable optical path length cell |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2215039B (en) * | 1988-02-10 | 1992-02-05 | Plessey Co Plc | Improvements relating to optical sensing arrangements |
| US4972077A (en) * | 1988-08-08 | 1990-11-20 | Schlumberger Industries Limited | Wavelength multiplexed optical transducer with a swept wavelength optical source |
| DE3830906A1 (en) * | 1988-09-10 | 1990-03-15 | Draegerwerk Ag | MIRROR ARRANGEMENT FOR A RADIATION IN A MULTIPLE REFLECTION MEASURING CELL |
| US5026992A (en) * | 1989-09-06 | 1991-06-25 | Gaztech Corporation | Spectral ratioing technique for NDIR gas analysis using a differential temperature source |
| DE4000584A1 (en) * | 1990-01-10 | 1991-07-11 | Muetek Gmbh | METHOD AND DEVICE FOR DETERMINING CONCENTRATION OF ISOTOPES |
| US5202570A (en) * | 1990-03-27 | 1993-04-13 | Tokyo Gas Co., Ltd. | Gas detection device |
| GB9015800D0 (en) * | 1990-07-18 | 1990-09-05 | Secretary Trade Ind Brit | Optical long-path monitoring apparatus |
| US5510269A (en) * | 1992-11-20 | 1996-04-23 | Sensors, Inc. | Infrared method and apparatus for measuring gas concentration including electronic calibration |
| US5637872A (en) * | 1995-08-24 | 1997-06-10 | Tulip; John | Gas detector |
| US6121627A (en) * | 1998-08-31 | 2000-09-19 | Tulip; John | Gas detector with reference cell |
| EP1103804B1 (en) * | 1999-11-24 | 2005-08-31 | Siemens Aktiengesellschaft | Method for detection of natural gas |
| US6750467B2 (en) | 2002-05-14 | 2004-06-15 | John Tulip | Vehicle mounted gas detector |
| WO2015038217A1 (en) * | 2013-09-12 | 2015-03-19 | Virginia Tech Intellectual Properties, Inc. | Fiber optic gas monitoring system |
| CN105092527A (en) * | 2014-05-19 | 2015-11-25 | 中国石油化工集团公司 | Gas detector for logging and method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4489239A (en) * | 1982-09-24 | 1984-12-18 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Portable remote laser sensor for methane leak detection |
| GB2165640B (en) * | 1984-10-13 | 1988-05-18 | Stc Plc | Gas or vapour concentration monitoring |
-
1987
- 1987-09-22 GB GB878722283A patent/GB8722283D0/en active Pending
-
1988
- 1988-09-22 CN CN88107746A patent/CN1033105A/en active Pending
- 1988-09-22 ZA ZA887103A patent/ZA887103B/en unknown
- 1988-09-22 AU AU24294/88A patent/AU2429488A/en not_active Abandoned
- 1988-09-22 WO PCT/GB1988/000776 patent/WO1989003028A1/en unknown
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1297814C (en) * | 2001-03-29 | 2007-01-31 | 日本酸素株式会社 | Method and equipment for determining nitrogen in gas |
| CN100491973C (en) * | 2006-10-11 | 2009-05-27 | 中国科学院上海微系统与信息技术研究所 | One-chip double core or multiple core semiconductor laser gas sensor and its making and using method |
| CN103776799A (en) * | 2012-10-28 | 2014-05-07 | 天津奇谱光电技术有限公司 | Hydrogen sulfide gas sensing equipment |
| CN103776792A (en) * | 2012-10-28 | 2014-05-07 | 天津奇谱光电技术有限公司 | Gas sensing equipment employing tunable Fabry-Perot filter |
| CN106461539A (en) * | 2013-12-05 | 2017-02-22 | G·P·克林克翰莫 | Spectrophotometer with variable optical path length cell |
| CN104596986A (en) * | 2014-01-14 | 2015-05-06 | 王胤 | Spectrum analysis method and spectrum analysis system |
| CN104237161A (en) * | 2014-10-15 | 2014-12-24 | 中国科学院合肥物质科学研究院 | Multi-component real-time online remote monitoring device and method for coal spontaneous combustion indicator gas |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8722283D0 (en) | 1987-10-28 |
| AU2429488A (en) | 1989-04-18 |
| WO1989003028A1 (en) | 1989-04-06 |
| ZA887103B (en) | 1989-07-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1033105A (en) | The method and apparatus of gas detection | |
| CA1278196C (en) | System for remote chemical analysis | |
| US4934816A (en) | Laser absorption detection enhancing apparatus and method | |
| US7012696B2 (en) | Optical heterodyne detection in optical cavity ringdown spectroscopy | |
| US6781696B1 (en) | Apparatus and method for a microsphere whispering-gallery mode evanescent-wave sensor | |
| CA1224935A (en) | Optical interferometric reception of ultrasonic energy | |
| US5076699A (en) | Method and apparatus for remotely and portably measuring a gas of interest | |
| JP4775798B2 (en) | Multiple gas concentration simultaneous measurement device | |
| He et al. | Rapidly swept, continuous-wave cavity ringdown spectroscopy with optical heterodyne detection: single-and multi-wavelength sensing of gases | |
| JPH0315742A (en) | Gas detector | |
| CN108279209A (en) | A kind of more gas detecting systems of wave-length coverage and wavelength continuously adjustable | |
| CN208013060U (en) | A kind of more gas detecting systems of wave-length coverage and wavelength continuously adjustable | |
| WO2005108939A1 (en) | Cavity ringdown spectroscopy with swept-frequency laser | |
| US20030089854A1 (en) | Apparatus and method for remotely sensing hydrocarbons and other pollutants in vehicle emissions | |
| JP3114959B2 (en) | Gas concentration detection method and apparatus | |
| US8654801B2 (en) | Light source device, analysis device, and light generation method | |
| Mohebati et al. | Remote detection of gases by diode laser spectroscopy | |
| Romanini et al. | Measurement of trace gases by diode laser cavity ringdown spectroscopy | |
| JP2015076467A (en) | Mid-infrared laser light source | |
| KR100481433B1 (en) | Semiconductor diode laser photo-analyzing system | |
| JP2796650B2 (en) | Multi-gas detector | |
| JP2540670B2 (en) | Multi-type gas detector using optical fiber | |
| KR20010005783A (en) | Method of spectrochemical analysis of impurity in gas | |
| JP2703835B2 (en) | Gas concentration measuring method and its measuring device | |
| JP2015176072A (en) | Mid-infrared laser beam generation device, gas detection device, mid-infrared laser beam generation method, and gas detection method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C01 | Deemed withdrawal of patent application (patent law 1993) | ||
| WD01 | Invention patent application deemed withdrawn after publication |