CN107643110A - A kind of gas micro-flow measurement device and method based on laser interferance method - Google Patents
A kind of gas micro-flow measurement device and method based on laser interferance method Download PDFInfo
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- CN107643110A CN107643110A CN201710765875.4A CN201710765875A CN107643110A CN 107643110 A CN107643110 A CN 107643110A CN 201710765875 A CN201710765875 A CN 201710765875A CN 107643110 A CN107643110 A CN 107643110A
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Abstract
The invention discloses a kind of gas micro-flow measurement device and method based on laser interferance method, the measurement apparatus includes flowmeter vacuum plant and laser interferometer；The resonator of laser interferometer is connected with the pressure stabilizing chamber of flowmeter vacuum plant, the frequency and the relation of gas micro measured using laser interferometer draws normal stream value, and the relation of frequency and gas micro is obtained using constant conductance method.The features such as high sensitivity of the present invention, response are fast, high resolution, effectively realizes the reduction of nearly 5 times of gas micro-flow measurement uncertainty.
Description
Technical field
The present invention relates to vacuum standard Leak calibration technical field, and in particular to the gas micro based on laser interferance method
Measurement apparatus and method.
Background technology
Document " ' Calibration apparatus of vacuum leak by using constant
Volume 22,2007, page 39~page 44 of conductance method ' MAPAN ", describe that Chinese LIP establishes based on solid
The vacuum standard leak hole calibration device of constant current inducing defecation by enema and suppository gas micro-flowmeter, the document are proposed by measuring in gas micro-flowmeter
The conductance value of constant conductance (molecular flow condition) element, the vacuum measured during with reference to flow meters work, you can realize (10-8~
10-3)Pam3/ s calibrating gas flow.
It is, corresponding molecular flow condition stream stable it makes use of vacuum-flow guiding element geometry using the advantages of this method
Invariable, advantages of simple structure and simple is led, obtains calibrating gas flow, but because the device uses capacitor thin film vacuum meter conduct
Main Regulator, the flow meters work pressure is measured, by capacitor thin film vacuum meter zero stability, thermal transpiration effect, membrane metal
The influence of the factors such as creep, the maximum uncertainty of measurement component of flowmeter is introduced, causes the flowmeter uncertainty to be up to
1.2%, precision is not high, can not meet vacuum value accurately trace to the source demand continuous improvement present situation.
The content of the invention
In view of this, should the invention provides a kind of gas micro-flow measurement device and method based on laser interferance method
The features such as measurement apparatus and method high sensitivity, response are fast, high resolution, effectively realizes gas micro-flow measurement uncertainty
Nearly 5 times of reduction.
Specific embodiments of the present invention are as follows：
A kind of gas micro-flow measurement device based on laser interferance method, the measurement apparatus include flowmeter vacuum plant and
Laser interferometer；The resonator of laser interferometer is connected with the pressure stabilizing chamber of flowmeter vacuum plant, surveyed using laser interferometer
Frequency and the relation of gas micro draw normal stream value, the relation of the frequency and gas micro is flowed using fixed
Inducing defecation by enema and suppository obtains.
Further, the frequency and the relation of gas micro areQ is gas miniflow
Amount；M is integer, dimensionless；C is the light velocity in vacuum；D is cavity length；F is frequency；α is gas molecule polarizability；K is
Boltzmann constant；T is voltage stabilizing room temperature；C is constant conductance element molecular flow conductance.
Further, the laser interferometer includes operating laser, reference laser diode, spectroscope, computer, electric current drive
Dynamic device, lock-in amplifier, photodetector, resonator and frequency meter；
Intra resonant cavity both ends set level crossing and concave mirror, refractometry precision to reach 10-11Magnitude；Working laser
Device reaches 10 with reference laser diode precision frequency stabilization-9Magnitude；
The working laser that operating laser is sent enters resonator through spectroscope, by level crossing and concave mirror in resonator
The frequency of working laser is adjusted to after resonance occurs by interior resonance, current driver and lock-in amplifier, photodetector measurement
The beat signal of operating laser and reference laser diode, measures through frequency meter and shows on computers.
Further, the flowmeter vacuum plant passes through pipeline and pressure stabilizing chamber phase by mechanical pump, molecular pump, vacuum valve
Even, absolute pressure formula capacitor thin film vacuum meter is provided with the pipeline, pressure stabilizing chamber is connected with air feed bottle and constant conductance element respectively；
The constant conductance element is used using the different multiple constant conductance element in parallel of conductance, and physical dimension reaches a μm magnitude.
Further, orthobaric volume room is provided with the pipeline, for measuring the volume of pressure stabilizing chamber；The pressure stabilizing chamber with
Differential capacitor thin film vacuum meter is in parallel, for measuring the pressure value at constant conductance element both ends so as to obtaining conductance.
Further, the resonator uses low thermal expansion material.
A kind of gas micro-flow measurement method based on laser interferance method, specific measuring method are as follows：
Step 1: open operating laser, reference laser diode, spectroscope, computer, current driver, lock-in amplifier,
Photodetector and frequency meter；
Step 2: mechanical pump and vacuum valve are opened, to the vacuum chamber collectively formed by pressure stabilizing chamber, resonator and pipeline
It is evacuated, when vacuum chamber internal pressure power is less than 10Pa, opens molecular pump and be evacuated, open absolute pressure formula capacitor thin film vacuum
Vacuum in meter measurement pressure stabilizing chamber, when vacuum is less than or equal to 10-4During Pa, reach capacity vacuum；
Step 3: the constant conductance element of measurement apparatus is connected with the vacuum calibration system of outside；
Step 4: air feed bottle is connected with pressure stabilizing chamber, gas is filled with into pressure stabilizing chamber；
Step 5: obtain resonant frequency by frequency meter, read the resonant frequency of Computer display and that gas is calculated is micro-
Flow.
Further, the constant conductance element is that one is selected in the different multiple constant conductance elements of conductance,
Before the step 1, using the volume of orthobaric volume room measurement pressure stabilizing chamber after being vacuumized to orthobaric volume room, with reference to differential
The constant conductance element pressure at two ends that capacitor thin film vacuum meter and absolute pressure formula capacitor thin film vacuum meter measure is worth to constant conductance
The conductance value of element, suitable constant conductance element is selected according to the size of calibrating gas flow to be measured；During measurement, differential electricity
Hold diagram vacuum gauge to close.
Further, in the step 5, frequency and the relation of gas micro are utilizedMeter
Calculation obtains gas micro, and Q is gas micro；M is integer, dimensionless；C is the light velocity in vacuum；D is cavity length；f
For frequency；α is gas molecule polarizability；K is Boltzmann constant；T is voltage stabilizing room temperature；C is constant conductance element molecular flow
Conductance.
Beneficial effect：
1st, the present invention is avoided using capacitor thin film vacuum meter as Main Regulator under conditions of vacuum environment rarefaction of air
Measurement of vacuum, the uncertainty that pressure measxurement is brought is reduced, make use of laser interferance method high sensitivity, respond fast, resolution
The features such as rate is high, effectively realizes the reduction of nearly 5 times of gas micro-flow measurement uncertainty, and precision is higher.
2nd, the hysteroscope of laserresonator of the present invention is level crossing or concave mirror or combination, compact-sized, stability
It is good.
3rd, the present invention is used using the different multiple constant conductance element in parallel of conductance, and physical dimension reaches a μm magnitude, can
Realize (10-9~10-3)Pam3The measurement of/s calibrating gas flow, compared to the measurement of prior art calibrating gas flow, is opened up
Measurement lower limit has been opened up, has improved measurement accuracy, has been applicable more extensive.
4th, measuring method simplicity of the invention is easily achieved, and precision is higher.
Brief description of the drawings
Fig. 1 is overall structure diagram of the present invention.
Wherein, 1- operating lasers, 2- reference laser diodes, 3- spectroscopes I, 4- spectroscopes II, 5- computers, 6- electric currents drive
Dynamic device, 7- lock-in amplifiers, 8- photodetectors I, 9- frequency meters, 10-FS133Pa absolute pressure formula capacitor thin film vacuum meters, 11-
FS133kPa absolute pressure formula capacitor thin film vacuum meters, 12- stop valves I, 13- stop valves II, 14- molecular pumps, 15- push-pull valves, 16- machines
Tool pump, 17- stop valves III, 18-1L orthobaric volumes room, 19-Fabry-Perot resonators, 20- level crossings, 21- concave mirrors, 22-
Stop valve IV, 23- pressure stabilizing chambers, 24- stop valves V, 25-FS133Pa differential pressure type capacitor thin film vacuum meters, 26- stop valves VI, 27-
Photodetector II, 28- stop valves VII, 29- constant conductances element I, 30- stop valves VIII, 31- stop valves Ⅸ, 32- constant conductances
Element II, 33- stop valves Ⅹ, 34- stop valves Ⅺ, 35- needle-valves, 39- air feed bottles I, 40- air feed bottles II, 41- air feed bottles III.
Embodiment
The present invention will now be described in detail with reference to the accompanying drawings and examples.
In vacuum range, pressure is low, rarefaction of air, and the measurement accuracy of gas micro is not high, and the invention provides one
Gas micro-flow measurement device of the kind based on laser interferance method, the measurement apparatus include flowmeter vacuum plant and laser interference
Instrument, laser interferometer is connected with the pressure stabilizing chamber of flowmeter vacuum plant, it is micro- using the frequency that laser interferometer measures and gas
The relation of flow draws normal stream value.
Because flow Q caused by constant conductance method gas micro-flowmeter is determined by gas density and constant conductance element conductance
It is fixed, as shown in formula (1).
Q=ρ kTC (1)
In formula,
ρ-the number density of molecule, m-3；
T- voltage stabilizing room temperatures, K；
K- Boltzmann constants, 1.38 × 10-23J/K；
C- constant conductance element molecular flow conductances, m3/s。
Obtained by The Ideal-Gas Equation pv=NRT, wherein, p represents pressure, and N represents the amount of material, ρ=N/v；
Shown in correlation such as formula (2) between gas density ρ and refractive index n,
In formula, NA- avogadros constant；
AR- gas molar polarizability；
α-gas molecule polarizability；
R- universal gas constants, 8.31J/ (molK).
At low pressures,
It can be obtained by formula (2) and formula (3),
In formula,
α-gas molecule polarizability；
By the condition of optical resonance in Fabry-Perot resonators,
M- integers, dimensionless；
D- cavity lengths, m；
λ-wavelength, m；
Calibrating gas flow can be obtained by formula (1), formula (4) and formula (5), that is, draw the pass of resonant frequency and gas micro
System.
The light velocity in c- vacuum, 299792458m/s, c=λ f；
F- resonant frequencies, Hz.
As shown in figure 1, laser interferometer includes operating laser 1, reference laser diode 2, spectroscope I 3, spectroscope II 4, meter
Calculation machine 5, current driver 6, lock-in amplifier 7, photodetector I 8, photodetector II 27, Fabry-Perot resonators 19
And frequency meter 9；
Operating laser 1 reaches 10 with the precision frequency stabilization of reference laser diode 2-9Magnitude；The inside of Fabry-Perot resonators 19 two
End sets level crossing 20 and concave mirror 21, refractometry precision to reach 10-11Magnitude.
Operating laser 1 is connected by spectroscope I 3 with the arrival end of Fabry-Perot resonators 19, meanwhile, working laser
Device 1 is connected by current driver 6, lock-in amplifier 7 and photodetector II 27 with the port of export of Fabry-Perot resonators 19
Form backfeed loop.Reference laser diode 2 is connected by spectroscope II 4, photodetector I 8, frequency meter 9 with computer 5, simultaneously
Spectroscope II 4 is connected with spectroscope I 3.Fabry-Perot resonators 19 have good stability, including mechanical stability and
Heat endurance, processed from low thermal expansion material such as devitrified glass, invar etc..
The working laser that operating laser 1 is sent enters Fabry-Perot resonators 19 through spectroscope I 3, passes through level crossing
20 and concave mirror 21 in the interior resonance of Fabry-Perot resonators 19, current driver 6 and lock-in amplifier 7 by working laser
When frequency is adjusted to occur resonance；Photodetector I 8 measures the beat signal of operating laser 1 and reference laser diode 2, due to
The change of gas density causes beat signal also to change in Fabry-Perot resonators 19, measures and shows through frequency meter 9
On computer 5.
Flowmeter vacuum plant is thin by mechanical pump 16, molecular pump 14,1L orthobaric volumes room 18, FS133Pa absolute pressure formula electric capacity
Film vacuum meter 10, FS133kPa absolute pressure formula capacitor thin films vacuum meter 11, pressure stabilizing chamber 23, air feed bottle and constant conductance element composition.
1L orthobaric volumes room 18 is used for the volume for measuring pressure stabilizing chamber 23.
Constant conductance element is used in parallel using constant conductance element I 29, constant conductance element II 32 and stop valve Ⅺ 34,
And physical dimension reaches a μm magnitude, prepared using laser, focused ion beam or micro-nano device processing method or technique, calibration measurement
When stop valve Ⅺ 34 close.Constant conductance element I 29 is different with the conductance of constant conductance element II 32, can select according to the actual requirements
Select use.Connect stop valve VII 28 and stop valve VIII 30 respectively at the entrance and exit of constant conductance element I 29, flowed fixed
Stop valve Ⅸ 31 and stop valve Ⅹ 33 are connected at the entrance and exit of guiding element II 32 respectively.
Mechanical pump 16, push-pull valve 15, molecular pump 14, stop valve II 13 sequentially pass through pipeline and are connected with pressure stabilizing chamber 23, are cutting
Only the pipeline of valve II 13 and pressure stabilizing chamber 23 is provided with 1L orthobaric volumes room 18 and stop valve III 17, while is provided with FS133Pa absolute pressures
Formula capacitor thin film vacuum meter 10 and FS133kPa absolute pressure formula capacitor thin films vacuum meter 11, FS133Pa absolute pressure formula capacitor thin film vacuum
Meter 10 is in parallel with FS133kPa absolute pressure formula capacitor thin film vacuum meters 11 after being connected with stop valve I 12.
Pressure stabilizing chamber 23 is connected with air feed bottle and constant conductance element respectively；The differential electric capacity of pressure stabilizing chamber 23 and FS133Pa is thin
Film vacuum meter 25 is in parallel, and differential capacitor thin film vacuum meter 25 and stop valve VI 26 are used in parallel, and stop valve VI 26 is used for pressure
Differential capacitor thin film vacuum meter 25 returns to zero and overload protection.The differential capacitor thin film vacuum meters 25 of FS133Pa and FS133Pa absolute pressures
Formula capacitor thin film vacuum meter 10 and FS133kPa absolute pressure formula capacitor thin films vacuum meter 11 is used in conjunction with, for measuring constant conductance member
The pressure value at part both ends.
Air feed bottle is formed in parallel by multiple gas cylinders by pipeline, and each gas cylinder is all connected with a stop valve, carries
For multiple gases or mixed gas, as shown in figure 1, air feed bottle I 39, air feed bottle II 40 are in parallel with air feed bottle III 41, the pipe of outlet
Road is provided with needle-valve 35.
Pressure stabilizing chamber 23 connects with Fabry-Perot resonators 19, by the change of gas density in Fabry-Perot resonators 19
Change measures via frequency meter 9, is shown on computer 5.
The specific measuring method of gas micro based on laser interferance method is as follows：
Before measurement starts, the appearance of pressure stabilizing chamber 23 is measured after being vacuumized to 1L orthobaric volumes room 18 using 1L orthobaric volumes room 18
Product, with reference to the differential capacitor thin film vacuum meters 25 of FS133Pa, FS133Pa absolute pressure formula capacitor thin films vacuum meter 10 and FS133kPa
The pressure at the constant conductance element both ends that absolute pressure formula capacitor thin film vacuum meter 11 measures is worth to the stream of different constant conductance elements
Value is led, suitable constant conductance element is selected according to the size of calibrating gas flow to be measured, constant conductance is selected in the present embodiment
Element I 29；During measurement, the differential capacitor thin film vacuum meters 25 of FS133Pa and stop valve III 17 are closed.Formally start to measure.
Driven Step 1: opening operating laser 1, reference laser diode 2, spectroscope I 3, spectroscope II 4, computer 5, electric current
Dynamic device 6, lock-in amplifier 7, photodetector I 8, photodetector II 27 and frequency meter 9；
Step 2: mechanical pump 16, push-pull valve 15, stop valve II 13, stop valve IV 22, stop valve V 24 are opened, to by steady
The vacuum chamber that pressure chamber 23, Fabry-Perot resonators 19 and pipeline collectively form is evacuated, when vacuum chamber internal pressure power
For 8.5Pa when, open molecular pump 14 be evacuated, continuous air extraction 5h, open stop valve I 12, pass through FS133Pa absolute pressure formula electric capacity
The vacuum that diagram vacuum gauge 10 measures in pressure stabilizing chamber 23 is 1.25 × 10-4Pa, reach capacity vacuum；
Step 3: opening stop valve VII 28 and stop valve VIII 30, constant conductance element I 29 is set to connect with vacuum calibration system
It is logical；
Step 4: opening needle-valve 35, N is filled with into pressure stabilizing chamber 23 from air feed bottle 3921.35Pa；
Step 5: adjustment work laser 1, reference laser diode 2, spectroscope I 3, spectroscope II 4, computer 5, electric current drive
Dynamic device 6, lock-in amplifier 7, photodetector I 8 and photodetector II 27, resonant frequency is obtained by frequency meter 9, reads and calculates
The resonant frequency that machine 5 is shown, and according to formula (6), flow value is obtained as 3.017 × 10-7Pam3/s。
In summary, presently preferred embodiments of the present invention is these are only, is not intended to limit the scope of the present invention.
Within the spirit and principles of the invention, any modification, equivalent substitution and improvements made etc., it should be included in the present invention's
Within protection domain.
Claims (9)
1. a kind of gas micro-flow measurement device based on laser interferance method, it is characterised in that the measurement apparatus includes flowmeter
Vacuum plant and laser interferometer；The resonator of laser interferometer is connected with the pressure stabilizing chamber of flowmeter vacuum plant, using swash
Frequency and the relation of gas micro that optical interferometer measures draw the relation of normal stream value, the frequency and gas micro
Obtained using constant conductance method.
2. the gas micro-flow measurement device based on laser interferance method as claimed in claim 1, it is characterised in that the frequency
Relation with gas micro isQ is gas micro；M is integer, dimensionless；C is vacuum
In the light velocity；D is cavity length；F is frequency；α is gas molecule polarizability；K is Boltzmann constant；T is voltage stabilizing room temperature
Degree；C is constant conductance element molecular flow conductance.
3. the gas micro-flow measurement device based on laser interferance method as claimed in claim 1, it is characterised in that the laser
Interferometer includes operating laser, reference laser diode, spectroscope, computer, current driver, lock-in amplifier, photodetection
Device, resonator and frequency meter；
Intra resonant cavity both ends set level crossing and concave mirror, refractometry precision to reach 10-11Magnitude；Operating laser with
Reference laser diode precision frequency stabilization reaches 10-9Magnitude；
The working laser that operating laser is sent enters resonator through spectroscope, by level crossing and concave mirror in resonator it is humorous
Shake, the frequency of working laser is adjusted to after resonance occurs by current driver and lock-in amplifier, photodetector measurement work
The beat signal of laser and reference laser diode, measures through frequency meter and shows on computers.
4. the gas micro-flow measurement device based on laser interferance method as claimed in claim 1, it is characterised in that the flow
Meter vacuum plant is connected by mechanical pump, molecular pump, vacuum valve by pipeline with pressure stabilizing chamber, and absolute pressure formula electricity is provided with the pipeline
Hold diagram vacuum gauge, pressure stabilizing chamber is connected with air feed bottle and constant conductance element respectively；The constant conductance element uses conductance not
Same multiple constant conductance element in parallel use, and physical dimension reaches a μm magnitude.
5. the gas micro-flow measurement device based on laser interferance method as claimed in claim 4, it is characterised in that in the pipe
Road is provided with orthobaric volume room, for measuring the volume of pressure stabilizing chamber；The pressure stabilizing chamber is in parallel with differential capacitor thin film vacuum meter,
For measuring the pressure value at constant conductance element both ends so as to obtaining conductance.
6. the gas micro-flow measurement device based on laser interferance method as claimed in claim 3, it is characterised in that the resonance
Chamber uses low thermal expansion material.
A kind of 7. gas micro-flow measurement method based on laser interferance method, it is characterised in that using as claimed in claim 4
Measurement apparatus, specific measuring method are as follows：
Step 1: open operating laser, reference laser diode, spectroscope, computer, current driver, lock-in amplifier, photoelectricity
Detector and frequency meter；
Step 2: opening mechanical pump and vacuum valve, the vacuum chamber collectively formed by pressure stabilizing chamber, resonator and pipeline is carried out
Pumping, when vacuum chamber internal pressure power is less than 10Pa, opens molecular pump and be evacuated, open the measurement of absolute pressure formula capacitor thin film vacuum
The vacuum in pressure stabilizing chamber is measured, when vacuum is less than or equal to 10-4During Pa, reach capacity vacuum；
Step 3: the constant conductance element of measurement apparatus is connected with the vacuum calibration system of outside；
Step 4: air feed bottle is connected with pressure stabilizing chamber, gas is filled with into pressure stabilizing chamber；
Step 5: obtaining resonant frequency by frequency meter, read the resonant frequency of Computer display and gas micro is calculated.
8. the gas micro-flow measurement method based on laser interferance method as claimed in claim 7, it is characterised in that the fixation
Conductance element is that one is selected in the different multiple constant conductance elements of conductance, before the step 1, to orthobaric volume
Room measures the volume of pressure stabilizing chamber using orthobaric volume room after vacuumizing, with reference to differential capacitor thin film vacuum meter and absolute pressure formula electric capacity
The constant conductance element pressure at two ends that diagram vacuum gauge measures is worth to the conductance value of constant conductance element, according to Standard Gases to be measured
The size of body flow selects suitable constant conductance element；During measurement, differential capacitor thin film vacuum meter is closed.
9. the gas micro-flow measurement method based on laser interferance method as claimed in claim 7, it is characterised in that the step
In five, frequency and the relation of gas micro are utilizedGas micro is calculated, Q is gas
Micrometeor；M is integer, dimensionless；C is the light velocity in vacuum；D is cavity length；F is frequency；α polarizes for gas molecule
Rate；K is Boltzmann constant；T is voltage stabilizing room temperature；C is constant conductance element molecular flow conductance.
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| CN112255465A (en) * | 2020-10-14 | 2021-01-22 | 河南师范大学 | Multi-frequency near-zero transmission sensor based on ear-shaped resonator and detection method |
| CN114323420A (en) * | 2021-12-09 | 2022-04-12 | 兰州空间技术物理研究所 | Portable quantum vacuum measuring device |
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| CN112255465A (en) * | 2020-10-14 | 2021-01-22 | 河南师范大学 | Multi-frequency near-zero transmission sensor based on ear-shaped resonator and detection method |
| CN112255465B (en) * | 2020-10-14 | 2024-05-28 | 河南师范大学 | Multi-frequency near-zero transmission sensor based on ear-shaped resonator and detection method |
| CN114323420A (en) * | 2021-12-09 | 2022-04-12 | 兰州空间技术物理研究所 | Portable quantum vacuum measuring device |
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Application publication date: 20180130 |