CN105241837B - A kind of infrared gas detection system that can improve detection stability - Google Patents
A kind of infrared gas detection system that can improve detection stability Download PDFInfo
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Abstract
A kind of infrared gas detection system that can improve detection stability, is belonged to infrared gas detection technical field, including Distributed Feedback Laser etc..Distributed Feedback Laser is located at before optical fiber one-to-two coupler, and light path is divided into two-way by optical fiber one-to-two coupler, it reaches photodetector A through gas chamber all the way, and photodetector A outputs meet amplifying circuit A；Another way light path is connected to photodetector B through optical fiber one-to-two coupler, photodetector B outputs meet amplifying circuit B, the output terminal of amplifying circuit A and B are connected respectively to two input terminals of difference channel, its output terminal connects filter circuit, the output terminal of filter circuit is connected with microprocessor, microprocessor connects temperature control circuit and current driving circuit respectively, and temperature control circuit is connected with Distributed Feedback Laser respectively with the output terminal of current driving circuit；The configuration of the present invention is simple, it is easy to realize, has long-time stability high, overcomes the systematic measurement error of prior art, can be widely used in fiber-optic fiber gas detection field.
Description
Technical field
A kind of infrared gas detection system that can improve detection stability, belongs to infrared gas detection technical field.
Background technology
The detection of micro-water content plays the role of important in power industry.Since the mid-80, with power industry
Develop rapidly, sulfur hexafluoride (SF6) electrical equipment is widely used, and specifically includes SF6 breakers, GIS closed groups
Close electric appliance, transformer, voltage transformer, current transformer and all kinds of bushings that SF 6 insulate etc..And building electricity at present
In the project for pressing grade 110kv and the above, SF6 switchgears are all used in sheet.These electrical equipments play in electric system
Very important effect, its reliability of operation are not only related to SF6 electrical equipments in itself, but also influence other equipment, even
The safety of whole power grid.
In operation, SF6 gases can resolve into the fluorine, sulphur and fluorine sulphur compound of monomer after by arc discharge or high temperature, electricity
Arc can be combined to stable SF6 gases again after disappearing.But when containing moisture in gas, fluorine sulphur compound can be reacted with water gives birth to
Into the very strong hydrofluoric acid of corrosivity, sulfuric acid and the very strong chemical substance of other toxicity etc., so as to corrode electrical equipment, equipment is reduced
Insulating capacity, jeopardizes the life security of maintenance personnel.The moisture for wanting SF6 gases in fully erased instrument be it is impossible, still
Moment grasps SF6 gas micro water contents, takes corresponding Control Measure, reduces the moisture in SF6 gases, it is ensured that and
Improve the safe operation reliability of breaker.Except micro-water content in electric system high-tension switch cabinet, the water vapor body in transformer oil
Concentration Testing is also indispensable.
Moisture in SF6 breakers is detected using Infrared spectra adsorption technology, its advantage is that reaction speed is fast,
High sensitivity, and can realize on-line checking.But since optical device such as laser, coupler, collimater, optical fiber are easily subject to temperature
Degree, the influence of ambient stress factor change and change light and power and coupling efficiency occur, transmission light light intensity is changed, from
And the light intensity change brought with gas absorption loss is obscured, measurement error is brought.It has impact on the measurement of Infrared spectra adsorption technology
Precision and long-time stability.
Paper " the angle bias effect analysis of temperature on fiber collimater " [Sun Ming victory photons journal the 10th phase of volume 35
1509-1512 pages of in October, 2006] in mention influence of the temperature to light collimator；Paper " melting cone fiber one-to-two coupler
Temperature-responsive " [Li Chuan, Zhang Yimo, Liu Tiegen, fourth victory sensing technology journal 196-198 pages of in September, 2001 of the 3rd phase of volume 14]
In mention the influence of temperature on fiber one-to-two coupler.
Once there is the solution for this problem, its thinking is to produce analog references optical signal by microprocessor to calibrate
And laser light extraction is adjusted, reduce the systematic error produced by environmental factors such as temperature to a certain extent, but due to laser
Device light power and Injection Current into non-linear relation, with the program obtain without spectral line baseline at absorption and uneven, cause
Signal-to-noise ratio reduces.
The content of the invention
To overcome the deficiencies in the prior art and defect, the present invention proposes a kind of can improve and detects the red of stability
Outer gas detecting system, by automatically controlling elimination since environmental factor is brought (in addition to gas absorbs) from gain amplifier
Transmission light path in luminous power fluctuation, to overcome the systematic measurement error thus brought.
The technical scheme is that realize in the following manner：
A kind of infrared gas detection system that can improve detection stability, including temperature control circuit, current driving circuit, DFB
Laser, optical fiber one-to-two coupler, gas chamber, photodetector A and B, amplifying circuit A and B are (from gain amplifier and periphery electricity
Road), difference channel, filter circuit and microprocessor, it is characterised in that Distributed Feedback Laser is located at before optical fiber one-to-two coupler,
Two-way light path will be divided into by optical fiber one-to-two coupler all the way, wherein reaching the input terminal of photodetector A, light through gas chamber all the way
The output terminal of electric explorer A is connected to the input terminal of amplifying circuit A；Another way light path is connected to photoelectricity through optical fiber one-to-two coupler
The input terminal of detector B, the output terminal of photodetector B are connected to the input terminal of amplifying circuit B, the output of amplifying circuit A and B
End is connected respectively to the two-way input terminal of difference channel, the input terminal of the output terminal connection filter circuit of difference channel, filtered electrical
The output terminal on road is connected with microprocessor, and microprocessor is connected respectively to temperature control circuit and current driving circuit, temperature control circuit and
The output terminal of current driving circuit is connected with Distributed Feedback Laser respectively；
The temperature control circuit studies the semiconductor laser diode controller LDC501 of system house using Stamford；
The amplifying circuit A and B each includes front and back stages AD603 amplifier chips and an AD8561 comparator core
Resistance R1, negative input end ground connection are connected between piece, the wherein positive-negative input end of prime AD603 amplifier chips；Its output terminal is through electricity
Resistance R2 is connected to the positive input terminal of rear class AD603 amplifier chips；Connected between the positive-negative input end of rear class AD603 amplifier chips
Resistance R3, its negative input end ground connection, output terminal are connected to the output of whole amplifying circuit after resistance R4 is with R5 or R13 series windings
End；The negative input end of AD8561 comparator chips is connected through resistance R6 with the common point of resistance R4, R5, is divided by potentiometer RW1
Its positive input terminal is connected to through resistance R9 after pressure, positive input terminal is grounded through capacitance C2, its outlet internal ground connection, its 8th foot
Be connected to the 2nd foot of two-stage AD603 amplifier chips through resistance R7, the 2nd foot of two-stage AD603 amplifier chips through resistance R8 and
Capacitance C1 is grounded after being in parallel；
The current driving circuit is formed by connecting by the DA mouths of microprocessor with integrated transporting discharging LM358 chips；
The photodetector A and B is PIN photoelectric detector.
The difference channel is amplifier AD8221 chips.
The filter circuit is universal active filter chip UAF42, is low-pass filter structure.
The microprocessor is LPC1758 chips.
The Distributed Feedback Laser is WSLS-137010C1424-20 butterfly-type encapsulation (Distributed
FeedbackLaser distributed feedback laser), wavelength are 1370 ± 2nm.
The method being detected using said detecting system to steam in gas chamber, step are as follows：
1) said detecting system is connected, connects the power supply in light path and each circuit, debugging light path is in each circuit
Normal operating conditions；Under test gas is poured in gas chamber；
2) thermostatic control is carried out to Distributed Feedback Laser by temperature control circuit：Produced using microprocessor in 0.03S time intervals
Interior curent change amplitude is 48mA, and change procedure is raised to 72mA from low to high from 24mA, then again from 72mA from high to low to
24mA is back and forth carried out, and the curent change of setting is to be realized by the voltage signal of microprocessor output in the form of sine wave；
Since Distributed Feedback Laser drive current variations can cause the change of the output wavelength of Distributed Feedback Laser, the electricity set in the microprocessor
Bucklingization exports the output wavelength change so that Distributed Feedback Laser, and the excursion of the output wavelength of Distributed Feedback Laser is driven corresponding to it
The excursion of streaming current, i.e., the excursion of the driving current between 24mA to 72mA contain Distributed Feedback Laser generation
The output wavelength of 1368.597nm, the output wavelength are the corresponding wavelength in water vapor absorption peak；
3) light is not referred to by being used as all the way for gas chamber in the two-way light that will be separated by optical fiber one-to-two coupler, by gas
Room all the way as detection light, adjust the amplification factor of amplifying circuit A and B and difference channel, it is poor that when adjustment is observed with oscillograph
The output signal of parallel circuit output terminal, it is 0mv to 100mv scopes to make amplitude of its output voltage outside water vapor absorption spike length
Interior, this explanation two-way amplifying circuit A is identical with B output signal baseline, while is no more than in the voltage of water vapor absorption spike strong point
3V, to meet the signal amplitude requirement of microprocessor collection；
4) detect optical circuit amplification factor adjust after, by microprocessor the output terminal of filter circuit gather out through
After water vapor absorption at wavelength 1368.597nm and signal that reference light is produced through no water vapor absorption at Same Wavelength all the way, warp
Cross microprocessor to calculate the difference of the two signals and store the difference, above-mentioned collection, calculating and storing process are repeated
1000 times, after the average value for taking this 1000 differences, using before experiment by compareing under different moisture contents, by microwater device reading
The difference (Y-axis) that the correspondence of storage difference corresponding with synchronization detecting system obtains is linear with moisture content (X-axis)
Curve, control obtain vapour concentration；
5) under test gas detection finishes, and closes the power supply of detecting system everywhere.
The final water vapor absorption spike shape of the system detectio of the present invention is to utilize optical fiber one-to-two coupler by laser emitting
Light is divided into two, reference optical signal and detection optical signal, by two-way photodetector A and B and amplifying circuit A and B by two-way
Signal obtains after being subtracted each other by difference channel, receives the telecommunications be converted to by photodetector by gas chamber all the way for optical signal
Number, another way is as referring to signal, i.e., the electric signal that light produces after directly being received without gas chamber by photodetector, when environment because
During plain (such as temperature, stress) change, it can strengthen or decay by the signal light intensity of gas chamber, i.e., into difference channel
Sine wave (optical signal is changed all the way) can increase or reduce all the way, and the sine wave electric signal of reference circuit is constant all the time (pure
Electric signal very little affected by environment, change can be ignored), which results in final absworption peak waveform to be distorted, and waveform occurs
Distortion can make microprocessor calculating difference change, so as to bring measurement error to measuring system, to solve the problems, such as this, can adopt
With from gain amplifier from amplification factor function is controlled, order output signal peak peak holding is constant, to eliminate environmental factor change
Influence to detecting system.
Present system can improve the function of infrared gas detection system stability by being realized from gain amplifier：
1) input amplifier is coupled with photodetector output terminal at two at two, and amplification circuit output end connects respectively
To two input terminals of difference channel.
2) two-way sine wave electric signal, all the way for light beam without gas chamber directly by photodetector receive produce and by
The sine wave electric signal of road amplifying circuit amplification, another way be after transmission light opto-electronic conversion by amplifying circuit amplification just
String ripple signal, the absworption peak waveform obtained after difference channel difference are the waveform that finally gathers of microprocessor, when environment because
When element does not change, gas absworption peak both sides should be in the same horizontal position in final collection waveform.
3) when environmental factor changes, reference light with detection light respectively there occurs different degrees of light intensity change, but due to
Action effect in two-way as amplifying circuit A and B from gain amplifier, by changing electric gain compensation temperature etc. in real time
The variable quantity of light intensity caused by external factor, eliminates the light intensity caused by environmental factor and changes, make to eventually pass through difference channel
Gas afterwards absorbs the influence that peak-to-peak signal changes from light intensity under non-absorbing effect, and gas absworption peak both sides return to same level position
Put.
The present invention has the following advantages that：The convenient installation of the present invention, it is simple in structure.Pass through the automatic control work(from gain amplifier
Can, environmental change and the unstable influence of light source are eliminated, can also be run in the larger environment of the temperature difference, accuracy and spirit
Sensitivity is high, and the response time is short, can monitor vapour concentration in time, easy to operate, pollution-free, this to do as long as changing wave-length coverage
Method can be applied in the detection of other species concentration at the same time, and application is quite varied.
Brief description of the drawings
Fig. 1 is the structure diagram of present system.
Wherein：1st, Distributed Feedback Laser, 2, optical fiber one-to-two coupler, 3, gas chamber, 4, photodetector A, 5, amplifying circuit A,
6th, difference channel, 7, filter circuit, 8, microprocessor, 9, temperature control circuit, 10, current driving circuit, 11, photodetector B,
12nd, amplifying circuit B.
Fig. 2 is the circuit diagram of the amplifying circuit A or B of present system, (rear to be referred to as using two AD603 amplifier chips
Pre-amplifier and post-amplifier), an AD8561 comparator chip be formed by connecting, wherein P1, P2 (are clasped for BNC
Type connector), as a kind of signal I/O mode, another way is then by row's pin J1, J2, J4 come transmission signal, at this
J4 is hanging in system, and wherein J1 (P1) is that J2 (P2) is amplification circuit output end from gain amplifying circuit input terminal.It is wherein front and rear
1 pin of two-stage AD603 chips receives trigger signal Vg+, and NC represents to connect the resistance in figure, and 8 pins connect power Vcc, and 6
Pin meets common ground end Vss, AD603 chips 5 at different levels, the connection of 7 pins, 7 foot of dual-stage amplifier (output terminal) each connecting resistance
R2, R4, post-amplifier output terminal are connected to the output terminal of whole amplifying circuit after resistance R4 is with R5 or R13 series windings, and two just
Negative input end 3,4 feet connect R1, R2 both ends respectively and 3 feet connect input signal, 4 feet ground connection, and 2 feet of two amplifier chips are connected
Connect；The negative input end of AD8561 comparator chips is connected through resistance R6 with the common point of resistance R4, R5, is divided by potentiometer WR1
Its positive input terminal is connected to through resistance R9 after pressure, positive input terminal is grounded through capacitance C2, its outlet internal ground connection, its 8th foot
Be connected to the 2nd foot of two-stage AD603 amplifier chips through resistance R7, the 2nd foot of two-stage AD603 amplifier chips through resistance R8 and
Capacitance C1 is grounded after being in parallel；
Fig. 3 is that the difference channel of present system and filter circuit circuit diagram, difference channel use 8221 chip of amplifier, its
Negative input end connects resistance Rg, positive input terminal connection resistance Rh, the intermediate ends of the 3 feet connection current potential R of 8221 chips and one end, electricity
The other end of position device R connects 2 feet of 8221 chips, and potentiometer R can carry out gain control to difference channel；8221 chips 5,
8 feet connect negative, positive 12V power supplys respectively, and negative, positive 12V power supplys are filtered with being connected capacitance C41, C40 respectively between ground connection；
On the one hand the other end of 7 foot of output terminal connection the resistance Rm, Rm of 8221 chips are grounded through resistance Rn, be on the other hand connected to active
The 4th foot of filtering chip UAF；Filter circuit is the low-pass filter being made of active power filtering chip UAF, wherein resistance Ri connections
In 8 feet and 16 feet of filtering chip UAF, resistance Rk is connected to 9 feet and 14 feet of filtering chip UAF, its 1 foot connection microprocessor
A/D ends carry out data acquisition, 2,12,15 feet ground connection, 10 feet, 11 feet connect negative, positive 12V power supplys, negative, positive 12V power supplys respectively
It is connected to ground respectively through capacitance C43, C42 to be filtered；The resistance value of Ri, Rk, Rm, Rn are used for determining to filter in low-pass filter
Cutoff frequency.
Embodiment
The present invention will be further described with reference to the accompanying drawings and examples, but not limited to this.
Embodiment 1：
As shown in Figs. 1-3, a kind of energy improves the infrared gas detection system of detection stability to the embodiment of the present invention 1, including
Temperature control circuit 9, current driving circuit 10, Distributed Feedback Laser 1, optical fiber one-to-two coupler 2, gas chamber 3, photodetector A (4) and B
(11), amplifying circuit A (5) and B (12), difference channel 6, filter circuit 7 and microprocessor 8, it is characterised in that Distributed Feedback Laser 1
Before optical fiber one-to-two coupler 2, two-way light path will be divided into by optical fiber one-to-two coupler 2 all the way, wherein all the way through gas
Room 3 reaches the input terminal of photodetector A (4), and the output terminal of photodetector A (4) is connected to the input of amplifying circuit A (5)
End；Another way light path is connected to the input terminal of photodetector B (11) through optical fiber one-to-two coupler 2, photodetector B's (11)
Output terminal is connected to the input terminal of amplifying circuit B (12), and the output terminal of amplifying circuit A (5) and B (12) are connected respectively to differential electrical
The two-way input terminal on road 6, the input terminal of the output terminal connection filter circuit 7 of difference channel 6, the output terminal of filter circuit 7 and micro-
Processor 8 connects, and microprocessor 8 is connected respectively to temperature control circuit 9 and current driving circuit 10, temperature control circuit 9 and electric current driving
The output terminal of circuit 10 is connected with Distributed Feedback Laser 1 respectively；
The temperature control circuit 9 studies the semiconductor laser diode controller LDC501 of system house using Stamford；
The amplifying circuit A and B each includes front and back stages AD603 amplifier chips and an AD8561 comparator core
Resistance R1, negative input end ground connection are connected between piece, the wherein positive-negative input end of prime AD603 amplifier chips；Its output terminal is through electricity
Resistance R2 is connected to the positive input terminal of rear class AD603 amplifier chips；Connected between the positive-negative input end of rear class AD603 amplifier chips
Resistance R3, its negative input end ground connection, output terminal are connected to the output of whole amplifying circuit after resistance R4 is with R5 or R13 series windings
End；The negative input end of AD8561 comparator chips is connected through resistance R6 with the common point of resistance R4, R5, is divided by potentiometer RW1
Its positive input terminal is connected to through resistance R9 after pressure, positive input terminal is grounded through capacitance C2, its outlet internal ground connection, its 8th foot
Be connected to the 2nd foot of two-stage AD603 amplifier chips through resistance R7, the 2nd foot of two-stage AD603 amplifier chips through resistance R8 and
Capacitance C1 is grounded after being in parallel；
The current driving circuit 10 is formed by connecting by the DA mouths of microprocessor 8 with integrated transporting discharging LM358 chips；
The photodetector A and B is PIN photoelectric detector.
The difference channel 6 is amplifier AD8221 chips.
The filter circuit 7 is universal active filter chip UAF42, is low-pass filter structure.
The microprocessor 8 is LPC1758 chips.
The Distributed Feedback Laser 1 is WSLS-137010C1424-20 butterfly-type encapsulation (Distributed
FeedbackLaser distributed feedback laser), wavelength are 1370 ± 2nm.
Embodiment 2：
The method being detected using said detecting system to steam in gas chamber, step are as follows：
1) said detecting system is connected, connects the power supply in light path and each circuit, debugging light path is in each circuit
Normal operating conditions；Under test gas is poured in gas chamber；
2) thermostatic control is carried out to Distributed Feedback Laser by temperature control circuit：Produced using microprocessor in 0.03S time intervals
Interior curent change amplitude is 48mA, and change procedure is raised to 72mA from low to high from 24mA, then again from 72mA from high to low to
24mA is back and forth carried out, and the curent change of setting is to be realized by the voltage signal of microprocessor output in the form of sine wave；
Since Distributed Feedback Laser drive current variations can cause the change of the output wavelength of Distributed Feedback Laser, the electricity set in the microprocessor
Bucklingization exports the output wavelength change so that Distributed Feedback Laser, and the excursion of the output wavelength of Distributed Feedback Laser is driven corresponding to it
The excursion of streaming current, i.e., the excursion of the driving current between 24mA to 72mA contain Distributed Feedback Laser generation
The output wavelength of 1368.597nm, the output wavelength are the corresponding wavelength in water vapor absorption peak；
3) light is not referred to by being used as all the way for gas chamber in the two-way light that will be separated by optical fiber one-to-two coupler, by gas
Room all the way as detection light, adjust the amplification factor of amplifying circuit A and B and difference channel, it is poor that when adjustment is observed with oscillograph
The output signal of parallel circuit output terminal, it is 0mv to 100mv scopes to make amplitude of its output voltage outside water vapor absorption spike length
Interior, this explanation two-way amplifying circuit A is identical with B output signal baseline, while is no more than in the voltage of water vapor absorption spike strong point
3V, to meet the signal amplitude requirement of microprocessor collection；
4) detect optical circuit amplification factor adjust after, by microprocessor the output terminal of filter circuit gather out through
After water vapor absorption at wavelength 1368.597nm and signal that reference light is produced through no water vapor absorption at Same Wavelength all the way, warp
Cross microprocessor to calculate the difference of the two signals and store the difference, above-mentioned collection, calculating and storing process are repeated
1000 times, after the average value for taking this 1000 differences, using before experiment by compareing under different moisture contents, by microwater device reading
The difference (Y-axis) that the correspondence of storage difference corresponding with synchronization detecting system obtains is linear with moisture content (X-axis)
Curve, control obtain vapour concentration；
5) under test gas detection finishes, and closes the power supply of detecting system everywhere.
Claims (5)
1. a kind of infrared gas detection system that can improve detection stability, including temperature control circuit, current driving circuit, DFB swash
Light device, optical fiber one-to-two coupler, gas chamber, photodetector A and B, amplifying circuit A and B, difference channel, filter circuit and micro-
Processor, it is characterised in that Distributed Feedback Laser is located at before optical fiber one-to-two coupler, will light all the way by optical fiber one-to-two coupler
Road is divided into two-way, wherein reaching the input terminal of photodetector A through gas chamber all the way, the output terminal of photodetector A, which is connected to, to be put
The input terminal of big circuit A；Another way light path is connected to the input terminal of photodetector B, photodetection through optical fiber one-to-two coupler
The output terminal of device B is connected to the input terminal of amplifying circuit B, and the output terminal of amplifying circuit A and B are connected respectively to the two of difference channel
Road input terminal, the input terminal of the output terminal connection filter circuit of difference channel, the output terminal of filter circuit are connected with microprocessor,
Microprocessor is connected respectively to temperature control circuit and current driving circuit, the output terminal of temperature control circuit and current driving circuit respectively and
Distributed Feedback Laser is connected；
The temperature control circuit studies the semiconductor laser diode controller LDC501 of system house using Stamford；
The amplifying circuit A and B each includes front and back stages AD603 amplifier chips and an AD8561 comparator chip,
Resistance R1, negative input end ground connection are connected wherein between the positive-negative input end of prime AD603 amplifier chips；Its output terminal is through resistance R2
It is connected to the positive input terminal of rear class AD603 amplifier chips；Resistance is connected between the positive-negative input end of rear class AD603 amplifier chips
R3, its negative input end ground connection, output terminal are connected to the output terminal of whole amplifying circuit after resistance R4 is with R5 or R13 series windings；
The negative input end of AD8561 comparator chips is connected through resistance R6 with the common point of resistance R4, R5, by potentiometer RW1 partial pressures it
Its positive input terminal is connected to by resistance R9, positive input terminal is grounded through capacitance C2, its outlet internal ground connection, its 8th foot is through electricity
Resistance R7 is connected to the 2nd foot of two-stage AD603 amplifier chips, and the 2nd foot of two-stage AD603 amplifier chips is through resistance R8 and capacitance
C1 is grounded after being in parallel；
The current driving circuit is formed by connecting by the DA mouths of microprocessor with integrated transporting discharging LM358 chips；
The difference channel is amplifier AD8221 chips；
The filter circuit is universal active filter chip UAF42, is low-pass filter structure.
2. a kind of infrared gas detection system that can improve detection stability as claimed in claim 1, it is characterised in that described
Microprocessor be LPC1758 chips.
3. a kind of infrared gas detection system that can improve detection stability as claimed in claim 1, it is characterised in that described
Photodetector A and B be PIN photoelectric detector.
4. a kind of infrared gas detection system that can improve detection stability as claimed in claim 1, it is characterised in that described
Distributed Feedback Laser be WSLS-137010C1424-20 butterfly-type encapsulation distributed feedback laser, wavelength is 1370 ± 2nm.
5. the method being detected using the infrared gas detection system described in claim 1 to steam in gas chamber, step are as follows：
1) said detecting system is connected, connects the power supply in light path and each circuit, debugging light path is in normal with each circuit
Working status；Under test gas is poured in gas chamber；
2) thermostatic control is carried out to Distributed Feedback Laser by temperature control circuit：Produced using microprocessor electric in 0.03S time intervals
Stream amplitude of variation is 48mA, and change procedure is raised to 72mA from low to high from 24mA, then past to 24mA from high to low from 72mA again
Multiple to carry out, the curent change of setting is to be realized by the voltage signal of microprocessor output in the form of sine wave；Due to DFB
Laser drive current change can cause the change of the output wavelength of Distributed Feedback Laser, the voltage change set in the microprocessor
Output is so that the output wavelength change of Distributed Feedback Laser, the excursion of the output wavelength of Distributed Feedback Laser correspond to its driving current
Excursion, i.e., the excursion of the driving current between 24mA to 72mA contains Distributed Feedback Laser generation
The output wavelength of 1368.597nm, the output wavelength are the corresponding wavelength in water vapor absorption peak；
3) light is not referred to by being used as all the way for gas chamber in the two-way light that will be separated by optical fiber one-to-two coupler, by gas chamber
All the way as detection light, the amplification factor of amplifying circuit A and B and difference channel is adjusted, observe differential electrical with oscillograph during adjustment
The output signal of road output terminal, makes its output voltage in the range of the amplitude outside water vapor absorption spike length is 0mv to 100mv,
This explanation two-way amplifying circuit A is identical with B output signal baseline, while is no more than 3V in the voltage of water vapor absorption spike strong point,
To meet the signal amplitude requirement of microprocessor collection；
4) after the amplification factor of detection optical circuit is adjusted, gathered out by output terminal of the microprocessor in filter circuit through steam
After absorption at wavelength 1368.597nm and signal that reference light is produced through no water vapor absorption at Same Wavelength all the way, process are micro-
Processor calculates the difference of the two signals and stores the difference, and above-mentioned collection, calculating and storing process are repeated 1000 times,
After the average value for taking this 1000 differences, using experiment before by compareing under different moisture contents, by microwater device reading with it is same
The difference and the linearity curve of moisture content that the correspondence that moment detecting system corresponds to storage difference obtains, control obtain steam
Concentration；
5) under test gas detection finishes, and closes the power supply of detecting system everywhere.
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| CN110530815A (en) * | 2019-09-23 | 2019-12-03 | 中国石油大学(华东) | Dissolve CO in seabed based on photonic crystal fiber2Gas detection method and system |
| CN111175236A (en) * | 2020-01-09 | 2020-05-19 | 中国原子能科学研究院 | Light path correction method and device for baseline drift in glove box type online spectral analysis |
| CN116660208B (en) * | 2023-05-30 | 2024-01-09 | 埃尔法(山东)仪器有限公司 | Laser gas detection circuit and gas detector |
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| CN104280362A (en) * | 2014-09-22 | 2015-01-14 | 合肥工业大学 | Online high-temperature water vapor laser spectrum detection system |
| CN205157423U (en) * | 2015-11-27 | 2016-04-13 | 济南大学 | Can improve infrared gaseous detecting system who detects stability |
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2015
- 2015-11-27 CN CN201510847875.XA patent/CN105241837B/en not_active Expired - Fee Related
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| JPH11337483A (en) * | 1998-05-28 | 1999-12-10 | Mitsubishi Heavy Ind Ltd | Apparatus and method for measuring exhaust gas of running vehicle |
| JP2010032479A (en) * | 2008-07-25 | 2010-02-12 | Miyama Giken:Kk | Infrared system gas concentration sensor |
| CN103149172A (en) * | 2013-02-28 | 2013-06-12 | 山东大学 | Method for improving stability of infrared gas detection system based on digital potentiometer |
| CN104092443A (en) * | 2014-07-03 | 2014-10-08 | 中国矿业大学(北京) | Automatic gain control circuit used for electrical prospecting |
| CN104280362A (en) * | 2014-09-22 | 2015-01-14 | 合肥工业大学 | Online high-temperature water vapor laser spectrum detection system |
| CN205157423U (en) * | 2015-11-27 | 2016-04-13 | 济南大学 | Can improve infrared gaseous detecting system who detects stability |
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