CN202770761U - Device for measuring concentration of trace gas - Google Patents
Device for measuring concentration of trace gas Download PDFInfo
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- CN202770761U CN202770761U CN 201220210744 CN201220210744U CN202770761U CN 202770761 U CN202770761 U CN 202770761U CN 201220210744 CN201220210744 CN 201220210744 CN 201220210744 U CN201220210744 U CN 201220210744U CN 202770761 U CN202770761 U CN 202770761U
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Abstract
The utility model discloses a device for measuring the concentration of trace gas, relates to the field of photoelectricity, and solves the problems of lower resolution, poorer measurement precision and incapability of meeting the practical demand in the conventional trace gas concentration measurement technology. The device comprises a laser of an optical assembly part as well as a spatial beam filter and a sample pool which are arranged in the light path direction of the laser in sequence, wherein the spatial beam filter comprises two focusing lenses and a needle hole positioned between the two focusing lenses; the sample pool comprises a quartz crystal and two micro resonant cavities symmetrically arranged on the two sides of the quartz crystal; and an electric signal control measurement part is electrically connected with the laser and the quartz crystal respectively. The quartz crystal is calibrated by adopting a calibration mode before measurement; and the calibration mode is switched to a measurement mode in the measurement process, and the concentration of the trace gas is measured according to an electric signal obtained by converting a sound signal by the quartz crystal.
Description
Technical field
The utility model relates to photoelectric field, particularly relates to a kind of device of measuring trace gas concentration.
Background technology
Trace gas detection has important application in a plurality of fields such as contamination monitoring, petroleum prospecting, industrial process control, space industry and medical diagnosiss.But the resolution of existing measurement trace gas concentration technology is lower, measuring accuracy is relatively poor, can not practical requirement.
The utility model content
The utility model provides a kind of device of measuring trace gas concentration, and the existing resolution of measuring trace gas concentration technology is lower, measuring accuracy is relatively poor in order to solve, so problem that can not practical requirement.
Device of the present utility model comprises: optical module part and electric signal control survey part; Wherein, described optical module partly comprises: laser instrument, and at spatial beam wave filter and sample cell that the optical path direction that laser instrument penetrates sets gradually, be injected with trace gas in the described sample cell; Described spatial beam wave filter comprises two condenser lenses, and the pin hole between described two condenser lenses, and light path is passed through in described two condenser lenses and pin hole; Comprise quartz crystal oscillator in the described sample cell, and two micro-resonant cavities that are symmetricly set on described quartz crystal oscillator both sides, the axle center of described quartz crystal oscillator and two micro-resonant cavities and light path coaxial, described quartz crystal oscillator plane and light path are perpendicular, light path in described two micro-resonant cavities and quartz crystal oscillator two pass through between raising one's arm; Wherein, described electric signal control survey part is electrically connected with laser instrument and quartz crystal oscillator respectively; Before measuring described trace gas concentration, the electric signal control survey partly adopts calibration mode that quartz crystal oscillator is calibrated; When measuring described trace gas concentration, the electric signal control survey partly switches to measurement pattern, and acoustical signal is transformed the electric signal that obtains according to described quartz crystal oscillator, measures the concentration of described trace gas.
Further, pin hole plane and the light path of spatial beam wave filter are non-perpendicular.The pin hole of spatial beam wave filter and the condenser lens focus between the laser instrument are positioned at described pin hole center; The pin hole of described spatial beam wave filter and the condenser lens imaging point between the sample cell are positioned at quartz crystal oscillator two arm centers.The pinhole diameter of spatial beam wave filter is 50 μ m to 300 μ m.
Further, the length of each micro-resonant cavity is less than 1/2nd wave length of sounds greater than 1/4th wave length of sounds, described wave length of sound refers in the trace gas, the length that acoustic vibration minimum period propagates, and numerical value equals the velocity of sound divided by the resonant frequency of quartz crystal oscillator.The micro-resonant cavity internal diameter is 0.6mm to 1mm, and the gap of each micro-resonant cavity and quartz crystal oscillator is 30 μ m to 50 μ m.
Further, also be equipped with incidence window and outgoing window on the optical path direction of sample cell, and non-perpendicular with light path.
Further, also be equipped with air intake opening and gas outlet on the sample cell, be used for injecting and discharging trace gas.
Further, the electric signal control survey partly comprises: handover module, be electrically connected with described quartz crystal oscillator, and be used for switching calibration mode and measurement pattern; Signal generating module is electrically connected with described handover module and laser instrument, is used for occuring signal; Lock-in amplifier is electrically connected with described handover module and signal generating module, is used for arranging the Harmonic Detection pattern, and the signal of surveying is carried out demodulation, and draws response curve; Data collecting card is electrically connected with lock-in amplifier, is used for gathering the response curve that lock-in amplifier draws; Computing machine is electrically connected with signal generating module and data collecting card, is used for control signal generation module and sends signal, and analyze the data that data collecting card gathers.Handover module comprises: the electronic switch that is electrically connected with described quartz crystal oscillator input end; Control end and the coupling capacitance that input end is electrically connected with described electronic switch; The integrated transporting discharging that is electrically connected with described quartz crystal oscillator output terminal and amplification resistance, and the output terminal of described integrated transporting discharging is electrically connected lock-in amplifier.Perhaps, handover module comprises: the relay that is electrically connected with described quartz crystal oscillator input end; The coupling capacitance that is electrically connected with normally opened contact and the first signal generator output end of described relay; The triode that is electrically connected with relay coil; The integrated transporting discharging that is electrically connected with described quartz crystal oscillator output terminal and amplification resistance, and the output terminal of described integrated transporting discharging is electrically connected lock-in amplifier.Signal generating module comprises: the first signal generator that output terminal is electrically connected with described handover module; Trigger the secondary signal generator that input end is electrically connected with the triggering output terminal of described first signal generator; With the electronics totalizer that the Laser Modulation input end of described laser instrument is electrically connected, described electronics totalizer also is electrically connected with the triggering output terminal of secondary signal generator; The 3rd signal generator that is electrically connected with an input end of described electronics totalizer.
Further, laser instrument is middle INFRARED QUANTUM CASCADE LASERS, launches mid-infrared laser.
The utility model beneficial effect is as follows:
Opticator of the present utility model comprises laser instrument, and the spatial beam wave filter and the sample cell that set gradually at the optical path direction that laser instrument penetrates; Further, the spatial beam wave filter comprises two condenser lenses and therebetween pin hole, two micro-resonant cavities that comprise quartz crystal oscillator in the sample cell and be symmetricly set on the quartz crystal oscillator both sides.The inventor has considered also that the resonant frequency of quartz crystal oscillator is affected by environment and has changed, and before measuring trace gas concentration quartz crystal oscillator is calibrated and automatically switch calibration mode and measurement pattern.By above-mentioned each device is set, set the relative position between each device, and partly finish calibration, switch and measure operation by the electric signal control survey, thereby so that the device of measurement trace gas concentration of the present utility model has higher resolution and measuring accuracy with respect to prior art, but practical requirement.
Description of drawings
Fig. 1 is the structural representation of the utility model embodiment one;
Fig. 2 is the structural representation of the utility model embodiment two;
Fig. 3 is the structural representation of the utility model embodiment three;
Fig. 4 is quartz crystal oscillator and the micro-resonant cavity position relationship schematic diagram of the utility model embodiment three;
Fig. 5 is quartz crystal oscillator and the micro-resonant cavity internal pressure distribution plan of the utility model embodiment three;
Fig. 6 is the structural representation of the utility model embodiment four;
Fig. 7 is the structural representation of the utility model embodiment five;
Fig. 8 is the signal intensity amplitude comparison diagram of the utility model embodiment five, embodiment one and prior art;
Fig. 9 be the utility model embodiment six repeat circuits and with the connection diagram of its associative cell.
Embodiment
In order to improve resolution and the measuring accuracy of trace gas measurement of concetration technology, to satisfy practical application request, the utility model provides a kind of device of measuring trace gas concentration, below further specifies by some embodiment.
A kind of device of measuring trace gas concentration is provided in embodiment one, the present embodiment, referring to shown in Figure 1, has comprised: optical module part 11 and electric signal control survey part 12.
Wherein, optical module part 11 comprises: laser instrument 111, and the optical path direction that penetrates at laser instrument 111 the spatial beam wave filter 112 and the sample cell 113 that set gradually wherein are injected with trace gas in the sample cell 113.The light beam that laser instrument 111 sends can be the light beam of each infrared band.Spatial beam wave filter 112 comprises two condenser lenses 1121 and 1122, and the pin hole 1123 between two condenser lenses 1121 and 1122, light path from two condenser lenses 1121 and 1122 and pin hole 1123 in pass through.Comprise quartz crystal oscillator 1131 in the sample cell 113, and two micro-resonant cavities 1132 and 1133 that are symmetricly set on quartz crystal oscillator 1131 both sides, quartz crystal oscillator 1131 and two micro-resonant cavities 1132 and 1133 axle center and light path coaxial, quartz crystal oscillator 1131 planes and light path are perpendicular, light path in two micro-resonant cavities 1132 and 1133 and 1131 liang of quartz crystal oscillators pass through between raising one's arm.Electric signal control survey part 12 is electrically connected with laser instrument 111 and quartz crystal oscillator 1131 respectively; Before measuring described trace gas concentration, electric signal control survey part 12 adopts calibration mode that quartz crystal oscillator 1131 is calibrated; When measuring described trace gas concentration, electric signal control survey part 12 switches to measurement pattern, and acoustical signal is transformed the electric signal that obtains according to quartz crystal oscillator 1131, measures trace gas concentration.
As seen, opticator comprises laser instrument in the present embodiment, and the spatial beam wave filter and the sample cell that set gradually at the optical path direction that laser instrument penetrates; Further, the spatial beam wave filter comprises two condenser lenses and therebetween pin hole, two micro-resonant cavities that comprise quartz crystal oscillator in the sample cell and be symmetricly set on the quartz crystal oscillator both sides.The inventor has considered also that the resonant frequency of quartz crystal oscillator is affected by environment and has changed, and before measuring trace gas concentration quartz crystal oscillator is calibrated and automatically switch calibration mode and measurement pattern.By above-mentioned each device is set, set the relative position between each device, and partly finish calibration, switch and measure operation by the electric signal control survey, thereby so that the measurement trace gas concentration device of the present embodiment has higher resolution and measuring accuracy with respect to prior art, but practical requirement.
Study discovery through the inventor, the molecular based frequency vibration that is arranged in mid infrared region absorbs the strongest in the infrared active vibration, the detection sensitivity of mid infrared region can reach the ppbV magnitude, exceeds several orders of magnitude than the ppmV level of near infrared region, is best infrared-gas detecting band.The in recent years fast development of middle INFRARED QUANTUM CASCADE LASERS makes the detection Absorption Line that uses in the trace gas measurement of concetration shift from traditional near infrared region (0.78-2.5 μ m) to mid infrared region (2.5-25 μ m).Yet lag behind at present the development of LASER Light Source in the development of this band detection device.On the other hand, its ultimate principle of optoacoustic spectroscopy is when a branch of light with surveying the Absorption Line same frequency passes through from tested gas, the object gas molecule is arrived high-energy state by laser excitation, because the collision de excitation is sent out process, come back to ground state, the generation of simultaneous sound wave, sound wave are detected device and survey and change into the electric signal that is directly proportional with tested gas concentration.The inventor also finds, optoacoustic spectroscopy does not have dependence to wavelength, can be used in theory from ultraviolet to all infrared wave bands, if can be combined mid-infrared laser with optoacoustic spectroscopy, the series of problems that the infrared eye development lags behind and brings in solving surely.Below provide some preferred embodiments that mid-infrared laser is combined with optoacoustic spectroscopy.
A kind of device of measuring trace gas concentration is provided in embodiment two, the present embodiment, referring to shown in Figure 2, has comprised: optical module part 21 and electric signal control survey part 22.
Optical module part 21 comprises: laser instrument 211, and the optical path direction that penetrates at laser instrument 211 the spatial beam wave filter 212 and the sample cell 213 that set gradually are injected with trace gas in the sample cell 213.Laser instrument 211 is middle INFRARED QUANTUM CASCADE LASERS, launches mid-infrared laser.
Wherein, spatial beam wave filter 212 comprises two condenser lenses 2121 and 2122, can be the germainium lens of plating anti-reflection film, also comprises the pin hole 2123 between two condenser lenses 2121 and 2122.Light path from two condenser lenses 2121 and 2122 and pin hole 2123 in pass through, the focus of condenser lens 2121 is positioned at pin hole 2123 centers, the imaging point of condenser lens 2122 is positioned at 2131 liang of arm centers of quartz crystal oscillator.The diameter of pin hole 2123 is 50 μ m to 300 μ m, and plane and the light path of pin hole 2123 are non-perpendicular, and the angulation scope is more than or equal to 40 degree and less than or equal to 80 degree.
Wherein, comprise quartz crystal oscillator 2131 in the sample cell 213, its resonant frequency includes but not limited to 32.768kHz, also comprise two micro-resonant cavities 2132 and 2133 that are symmetricly set on quartz crystal oscillator 2131 both sides, quartz crystal oscillator 2131 and two micro-resonant cavities 2132 and 2133 axle center and light path coaxial, quartz crystal oscillator 2131 planes and light path are perpendicular, light path in two micro-resonant cavities 2132 and 2133 and 2131 liang of quartz crystal oscillators pass through between raising one's arm.Also be equipped with incidence window 2134 and outgoing window 2135 on the optical path direction of sample cell 213, can be made by materials such as zinc selenide infrared in the transmission, germanium, magnesium fluoride, calcium fluoride, be coated with anti-reflection film, and non-perpendicular with light path, the angulation scope is more than or equal to 60 degree and less than or equal to 90 degree.
Electric signal control survey part 22 is electrically connected with laser instrument 211 and quartz crystal oscillator 2131 respectively; Before measuring described trace gas, electric signal control survey part 22 adopts calibration mode that quartz crystal oscillator 2131 is calibrated; When measuring described trace gas concentration, electric signal control survey part 22 switches to measurement pattern, and acoustical signal is transformed the electric signal that obtains according to quartz crystal oscillator 2131, measures trace gas concentration.
As seen, device in the present embodiment has advantages of embodiment one, and the inventor considers that the mid-infrared laser source is responsive especially to feedback light, even be reflected back the pattern fluctuation that extremely faint light also can cause laser from lens, air chamber window, micro-resonant cavity, may cause the deviation of measuring.So, the pin hole plane of installing in the present embodiment and the angled design of light path, and sample cell window and the angled design of light path avoided the reflection of light beam effectively, make quantum cascade laser in whole scanning process without Mode-hopping Phenomena.
A kind of device of measuring trace gas concentration is provided in embodiment three, the present embodiment, referring to shown in Figure 3, has comprised: optical module part 31 and electric signal control survey part 32.
Wherein, spatial beam wave filter 312 comprises two condenser lenses 3121 and 3122, and the pin hole 3123 between two condenser lenses 3121 and 3122, light path from two condenser lenses 31121 and 3122 and pin hole 3123 in pass through.
Wherein, comprise quartz crystal oscillator 3131 in the sample cell 313, its resonant frequency includes but not limited to 32.768Hz, also comprise two micro-resonant cavities 3132 and 3133 that are symmetricly set on quartz crystal oscillator 3131 both sides, quartz crystal oscillator 3131 and two micro-resonant cavities 3132 and 3133 axle center and light path coaxial, quartz crystal oscillator 3131 planes and light path are perpendicular, light path in two micro-resonant cavities 3132 and 3133 and 3131 liang of quartz crystal oscillators pass through between raising one's arm. Micro-resonant cavity 3132 and 3133 can adopt stainless steel needle tubing or glass tube, and length is more than or equal to 1/4th wave length of sounds and less than or equal to 1/2nd wave length of sounds, and internal diameter is 0.6mm to 1mm, and external diameter is 0.8mm to 1.4mm; The gap of each micro-resonant cavity and quartz crystal oscillator 3131 is 30 μ m to 50 μ m; Concrete quartz crystal oscillator and micro-resonant cavity position relationship can be referring to shown in Figure 4.
Electric signal control survey part 32 is electrically connected with laser instrument 311 and quartz crystal oscillator 3131 respectively; Before measuring described trace gas concentration, electric signal control survey part 32 adopts calibration mode that quartz crystal oscillator 3131 is calibrated; When measuring described trace gas concentration, the electric signal control survey partly switches to measurement pattern, and acoustical signal is transformed the electric signal that obtains according to quartz crystal oscillator 3131, measures trace gas concentration.
As seen, device in the present embodiment has advantages of embodiment one, and the inventor considers that half-wave standing wave resonance situation is for confined space, if insertion quartz crystal oscillator, because the interference of quartz crystal oscillator, and have the gap between micro-resonant cavity and quartz crystal oscillator, and can destroy resonant condition, resonance effects is had a greatly reduced quality; The inventor considers that also typical mid-infrared laser beam diameter is 3mm, if the internal diameter of micro-resonant cavity is too small, then can cause contacting of laser beam and micro-resonant cavity and quartz crystal oscillator, and then the ground unrest of generation non-zero, this noise exceeds several times to tens times than thermonoise level originally usually, has seriously reduced the detection sensitivity of sensing device.Therefore, the length of single micro-resonant cavity adopts more than or equal to 1/4th wave length of sounds and less than or equal to 1/2nd wave length of sounds in the present embodiment, this is so that the frequency overlap of the frequency of micro-resonant cavity and quartz crystal oscillator, resonance effect strengthens greatly, at this moment micro-resonant cavity is maximum at the opening part air-flow velocity of quartz crystal oscillator direction, and cause acoustic pressure to produce local maximum in the quartz crystal oscillator center from the back draught impact of two micro-resonant cavities, thereby the resonance that has improved greatly output strengthens signal, and concrete quartz crystal oscillator and micro-resonant cavity internal pressure distribution plan can be referring to shown in Figure 5; Employing is more than or equal to 1/4th wave length of sounds and less than or equal to the micro-resonant cavity of 1/2nd wave length of sounds, allow the micro-resonant cavity interior diameter further to increase to 0.6mm to 1mm and do not lose to resonate to strengthen signal, insert spatial filter between laser instrument and the sample cell, further filtering the high-order transverse mode of quanta cascade light beam, be beneficial to and focus on 3mm mid-infrared light bundle touchless ground by micro-resonant cavity and quartz crystal oscillator, through repeatedly test, the energy percent of pass is up to 98%.
A kind of device of measuring trace gas concentration is provided in embodiment four, the present embodiment, referring to shown in Figure 6, has comprised: optical module part 41 and electric signal control survey part 42.
Wherein, optical module part 41 comprises: laser instrument 411, and the optical path direction that penetrates at laser instrument 411 the spatial beam wave filter 412 and the sample cell 413 that set gradually are injected with trace gas in the sample cell 413.Laser instrument 411 is middle INFRARED QUANTUM CASCADE LASERS, launches mid-infrared laser.Spatial beam wave filter 412 comprises two condenser lenses 4121 and 4122, and the pin hole 4123 between two condenser lenses 4121 and 4122, light path from two condenser lenses 4121 and 4122 and pin hole 4123 in pass through.Comprise quartz crystal oscillator 4131 in the sample cell 413, and two micro-resonant cavities 4132 and 4133 that are symmetricly set on quartz crystal oscillator 4131 both sides, quartz crystal oscillator 4131 and two micro-resonant cavities 4132 and 4133 axle center and light path coaxial, quartz crystal oscillator 4131 planes and light path are perpendicular, light path in two micro-resonant cavities 4132 and 4133 and 4131 liang of quartz crystal oscillators pass through between raising one's arm.
Wherein, electric signal control survey part 42 is electrically connected with laser instrument 411 and quartz crystal oscillator 4131 respectively.Before measuring described trace gas, electric signal control survey part 42 adopts calibration mode that quartz crystal oscillator 4131 is calibrated, when measuring trace gas concentration, electric signal control survey part 42 switches to measurement pattern, and acoustical signal is transformed the electric signal obtain according to quartz crystal oscillator 4131, measure trace gas concentration.Specifically, electric signal control survey part 42 comprises: handover module 421, be electrically connected with quartz crystal oscillator 4131, and be used for switching calibration mode and measurement pattern; Signal generating module 422 is electrically connected with handover module 421 and laser instrument 411, is used for occuring signal; Lock-in amplifier 423 is electrically connected with handover module 421 and signal generating module 422, is used for arranging the Harmonic Detection pattern, and the signal of surveying is carried out demodulation, and draws response curve; Data collecting card 424 is electrically connected with lock-in amplifier 423, is used for gathering the response curve that lock-in amplifier 423 draws; Computing machine 425 is electrically connected with signal generating module 422 and data collecting card 424, is used for control signal generation module and sends signal, and analyze the data that data collecting card gathers.
As seen, the device in the present embodiment has advantages of embodiment one, and the electric signal control survey of the present embodiment part has been carried out refinement to the function of switching calibration mode and measurement pattern, the actual demand of measuring again to satisfy first calibration.
A kind of device of measuring trace gas concentration is provided in embodiment five, the present embodiment, referring to shown in Figure 7, has comprised: optical module part 51 and electric signal control survey part 52.
Wherein, spatial beam wave filter 512 comprises two condenser lenses 5121 and 5122, can be the germainium lens of plating anti-reflection film, also comprises the pin hole 5123 between two condenser lenses 5121 and 5122.Light path from two condenser lenses 5121 and 5122 and pin hole 5123 in pass through, the focus of condenser lens 5121 is positioned at pin hole 5123 centers, condenser lens 5122 imaging points are positioned at 5131 liang of arm centers of quartz crystal oscillator.The diameter of pin hole 5123 is 50 μ m to 300 μ m, and pin hole 5123 planes and light path are non-perpendicular, and the angulation scope is more than or equal to 40 degree and less than or equal to 80 degree.
Wherein, comprise quartz crystal oscillator 5131 in the sample cell 513, its resonant frequency includes but not limited to 32.768kHz, also comprise two micro-resonant cavities 5132 and 5133 that are symmetricly set on quartz crystal oscillator 5131 both sides, quartz crystal oscillator 5131 and two micro-resonant cavities 5132 and 5133 axle center and light path coaxial, quartz crystal oscillator 5131 planes and light path are perpendicular, light path in two micro-resonant cavities 5132 and 5133 and 5131 liang of quartz crystal oscillators pass through between raising one's arm. Micro-resonant cavity 5132 and 5133 can adopt stainless steel needle tubing or glass tube, and length is more than or equal to 1/4th wave length of sounds and less than or equal to 1/2nd wave length of sounds, and internal diameter is 0.6mm to 1mm, and external diameter is 0.8 to 1.4mm; The gap of each micro-resonant cavity and quartz crystal oscillator 5131 is 30 μ m to 50 μ m.Also be equipped with incidence window 5134 and outgoing window 5135 on the optical path direction of sample cell 513, can be made by materials such as zinc selenide infrared in the transmission, germanium, magnesium fluoride, calcium fluoride, be coated with anti-reflection film, and non-perpendicular with light path, the angulation scope is more than or equal to 60 degree and less than or equal to 90 degree.Also be equipped with air intake opening 5136 and gas outlet 5137 on the sample cell 513, being used for injection and discharge has trace gas.
Electric signal control survey part 52 comprises: the input end of laser instrument 511 is electrically connected with the output terminal of electronics totalizer 521, an input end of electronics totalizer 521 is electrically connected with the 3rd signal generator 522 output terminals, another input end is electrically connected with the output terminal of secondary signal generator 523, the trigger end of the trigger end of secondary signal generator 523 and lock-in amplifier 524 is electrically connected with the synchronous output end of first signal generator 525, the signal output part of first signal generator 525 is electrically connected with coupling capacitance 5261 ends of electronic switch 526, another input end of electronic switch 526 is electrically connected with signal ground, the output terminal of electronic switch 526 is electrically connected with the input end of quartz crystal oscillator 5131, the output terminal of quartz crystal oscillator 5131 is electrically connected with the negative input end of integrated transporting discharging 527, the positive input terminal of integrated transporting discharging 527 is electrically connected with signal ground, the negative input end of integrated transporting discharging 527 and output terminal and having amplifies resistance R 1 (can value 5M to 10M ohm), and the input end of the output terminal of integrated transporting discharging 527 and lock-in amplifier 524 is electrically connected.In addition for realizing the function of automatic calibration quartz crystal oscillator before test, also be provided with data collecting card 528 and computing machine 529, the input end of the output terminal of lock-in amplifier 524 and data collecting card 528 is electrically connected, the input end of the output terminal of data collecting card 528 and computing machine 529 is electrically connected, and the control end of the control end of computing machine 529 and first signal generator 525 is electrically connected.
In quartz crystal oscillator automatic calibration process, the voltage signal of a stack of computing machine 529 control first signal generator 525 outputs, this voltage signal is formed by stacking by the sine wave of 30kHz and the DC level of a 5V, the DC level control electronic switch 526 closed band coupling capacitance ends of connecting wherein, the sinusoidal wave input pin that is directed to quartz crystal oscillator 5131 by coupling capacitance 5261, then first signal generator 525 is controlled by computing machine 529, sine wave freuqency to high frequency direction scanning output, export simultaneously synchronizing signal to lock-in amplifier 524, lock-in amplifier 524 is arranged on the first harmonic detection mode, integrated transporting discharging 527,1 pair of signal of the amplification resistance R of value 5M to 10M ohm amplifies, the output signal of 524 pairs of quartz crystal oscillators 5131 of lock-in amplifier is carried out demodulation, after the response curve that obtains is gathered by data collecting card 528, send computing machine 529 to, computing machine 529 is analyzed the resonant frequency f that draws quartz crystal oscillator 5131
0
In measuring process, computing machine 529 control first signal generators 525 output no-voltages, the synchronous end output frequency of first signal generator 525 is f simultaneously
0/ 2 synchronizing signal is to lock-in amplifier 524 and secondary signal generator 523, and lock-in amplifier 524 is arranged on the second harmonic detection pattern, and secondary signal generator 523 is triggered and produces with f frequently
0/ 2, amplitude is the 6mV sine wave signal, the amplitude of exporting with the 3rd signal generator 522 is that the 20mV triangular signal together is imported into electronics totalizer 521, signal after the stack is admitted to laser instrument 511 input ports quantum cascade laser is carried out frequency modulation (PFM) and scanning, the no-voltage of first signal generator 525 outputs makes electronic switch 526 connect the input pin of signal ground and quartz crystal oscillator 5131, make quartz crystal oscillator 5131 be in measurement pattern, the weak acoustic signal that produces is converted into electric signal by quartz crystal oscillator 5131, delivering to integrated transporting discharging 527 amplifies with amplification resistance R 1, lock-in amplifier 524 is to its demodulation, and data collecting card 528 gathers and transfers to computing machine 529 and carries out record.
As seen, device in the present embodiment has all advantages of embodiment one to four, and preferred serial connection electronic switch between quartz crystal oscillator and the signal generator, cooperate data collecting card, computing machine and first signal generator, realized the quick switching of calibration and measuring process and need not to change any equipment and be electrically connected.Further can be referring to shown in Figure 8, wherein horizontal ordinate is air pressure, ordinate is the signal intensity amplitude, the result that curve A 1 (shown in the solid square form point) records for the measurement mechanism that uses the present embodiment, the result of curve A 3 (shown in the black circle) for using embodiment one described measurement mechanism to record, the result of curve A 2 (shown in the black triangle) for using existing apparatus to record.As seen, the signal amplitude that uses the measurement mechanism of the present embodiment to obtain is to use 30 times of signal amplitude that existing apparatus obtains; The signal amplitude that uses embodiment one described measurement mechanism to obtain is to use 5 times of signal amplitude that existing apparatus obtains.
Embodiment six, provide a kind of device of measuring trace gas concentration, having comprised: optical module part and electric signal control survey part.Adopt the electronic switch 526 in the relay alternative embodiment five in the present embodiment, therefore, the present embodiment only describes relay and the unit related with it, and other parts can be referring to the associated description among the embodiment five.
Referring to shown in Figure 9, the relay 626 that is electrically connected with quartz crystal oscillator 6131 input ends; The coupling capacitance 6261 that is electrically connected with normally opened contact and first signal generator 625 output terminals of relay 626; The triode 6262 that is electrically connected with relay coil; The integrated transporting discharging 627 that is electrically connected with quartz crystal oscillator 6131 output terminals and amplify resistance R 1 (can value 5M to 10M ohm), and the output terminal of described integrated transporting discharging 627 is electrically connected lock-in amplifier 624.
In the step of quartz crystal oscillator calibration: signal by sine wave and DC level stack of computer control first signal generator 625 outputs, wherein DC level control triode 6262 conductings, the coil of relay 626 gets electric, the contact of closure state is normally opened contact, connect band coupling capacitance end 6261, the sinusoidal wave input pin that is directed to quartz crystal oscillator 6131 by coupling capacitance 6261.
In switch mode: the no-voltage of first signal generator 625 outputs is with triode 6262 cut-offs, there is not electric current to pass through from relay coil, the contact of closure state is normally closed contact, the input pin of signal ground and quartz crystal oscillator 6131 is connected, make quartz crystal oscillator 6131 switch to measurement pattern, the acoustical signal that produces is converted into electric signal by quartz crystal oscillator 6131, sends into integrated transporting discharging and amplifies with amplification resistance.
Obviously, those skilled in the art can carry out various changes and modification to the utility model and not break away from spirit and scope of the present utility model.Like this, if of the present utility model these are revised and modification belongs within the scope of the utility model claim and equivalent technologies thereof, then the utility model also is intended to comprise these changes and modification interior.
Claims (13)
1. a device of measuring trace gas concentration is characterized in that, comprising: optical module part and electric signal control survey part;
Wherein, described optical module partly comprises: laser instrument, and at spatial beam wave filter and sample cell that the optical path direction that laser instrument penetrates sets gradually, be injected with trace gas in the described sample cell; Described spatial beam wave filter comprises two condenser lenses, and the pin hole between described two condenser lenses, and light path is passed through in described two condenser lenses and pin hole; Comprise quartz crystal oscillator in the described sample cell, and two micro-resonant cavities that are symmetricly set on described quartz crystal oscillator both sides, the axle center of described quartz crystal oscillator and two micro-resonant cavities and light path coaxial, described quartz crystal oscillator plane and light path are perpendicular, light path in described two micro-resonant cavities and quartz crystal oscillator two pass through between raising one's arm;
Wherein, described electric signal control survey part is electrically connected with laser instrument and quartz crystal oscillator respectively; Before measuring described trace gas concentration, the electric signal control survey partly adopts calibration mode that quartz crystal oscillator is calibrated; When measuring described trace gas concentration, the electric signal control survey partly switches to measurement pattern, and acoustical signal is transformed the electric signal that obtains according to described quartz crystal oscillator, measures described trace gas concentration.
2. device as claimed in claim 1 is characterized in that, pin hole plane and the light path of described spatial beam wave filter are non-perpendicular.
3. device as claimed in claim 1 is characterized in that, the pin hole of described spatial beam wave filter and the condenser lens focus between the laser instrument are positioned at described pin hole center; The pin hole of described spatial beam wave filter and the condenser lens imaging point between the sample cell are positioned at quartz crystal oscillator two arm centers.
4. device as claimed in claim 1 is characterized in that, the pinhole diameter of described spatial beam wave filter is 50 μ m to 300 μ m.
5. device as claimed in claim 1, it is characterized in that, the length of described each micro-resonant cavity is less than 1/2nd wave length of sounds greater than 1/4th wave length of sounds, described wave length of sound refers in the trace gas, the length that acoustic vibration minimum period propagates, numerical value equals the velocity of sound divided by the resonant frequency of quartz crystal oscillator.
6. device as claimed in claim 5 is characterized in that, described micro-resonant cavity internal diameter is 0.6mm to 1mm, and the gap of each micro-resonant cavity and quartz crystal oscillator is 30 μ m to 50 μ m.
7. device as claimed in claim 1 is characterized in that, also is equipped with incidence window and outgoing window on the optical path direction of described sample cell, and non-perpendicular with light path.
8. device as claimed in claim 1 is characterized in that, also is equipped with air intake opening and gas outlet on the described sample cell, is used for injecting and discharging trace gas.
9. device as claimed in claim 1 is characterized in that, described electric signal control survey partly comprises:
Handover module is electrically connected with described quartz crystal oscillator, is used for switching calibration mode and measurement pattern;
Signal generating module is electrically connected with described handover module and laser instrument, is used for occuring signal;
Lock-in amplifier is electrically connected with described handover module and signal generating module, is used for arranging the Harmonic Detection pattern, and the signal of surveying is carried out demodulation, and draws response curve;
Data collecting card is electrically connected with lock-in amplifier, is used for gathering the response curve that lock-in amplifier draws;
Computing machine is electrically connected with signal generating module and data collecting card, is used for control signal generation module and sends signal, and analyze the data that data collecting card gathers.
10. device as claimed in claim 9 is characterized in that, described handover module comprises: the electronic switch that is electrically connected with described quartz crystal oscillator input end; Control end and the coupling capacitance that input end is electrically connected with described electronic switch; The integrated transporting discharging that is electrically connected with described quartz crystal oscillator output terminal and amplification resistance, and the output terminal of described integrated transporting discharging is electrically connected lock-in amplifier.
11. device as claimed in claim 9 is characterized in that, described handover module comprises: the relay that is electrically connected with described quartz crystal oscillator input end; The coupling capacitance that is electrically connected with normally opened contact and the first signal generator output end of described relay; The triode that is electrically connected with relay coil; The integrated transporting discharging that is electrically connected with described quartz crystal oscillator output terminal and amplification resistance, and the output terminal of described integrated transporting discharging is electrically connected lock-in amplifier.
12. device as claimed in claim 9 is characterized in that, described signal generating module comprises: the first signal generator that output terminal is electrically connected with described handover module; Trigger the secondary signal generator that input end is electrically connected with the triggering output terminal of described first signal generator; With the electronics totalizer that the Laser Modulation input end of described laser instrument is electrically connected, described electronics totalizer also is electrically connected with the triggering output terminal of secondary signal generator; The 3rd signal generator that is electrically connected with an input end of described electronics totalizer.
13. such as each described device of claim 1 to 12, it is characterized in that, described laser instrument is middle INFRARED QUANTUM CASCADE LASERS, launches mid-infrared laser.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103389270A (en) * | 2012-05-11 | 2013-11-13 | 张妍 | Apparatus for measuring concentration of trace gas, and method thereof |
| CN103792195A (en) * | 2014-01-15 | 2014-05-14 | 山西大学 | Double-optical-path photoacoustic spectrometry detection module and gas concentration detector by adopting module |
| CN104251842A (en) * | 2014-08-29 | 2014-12-31 | 浙江省计量科学研究院 | Method for realization of online calibration of photoacoustic spectroscopy system pool constants by use of oxygen in atmosphere |
| CN108593763A (en) * | 2018-03-26 | 2018-09-28 | 山东大学 | A kind of multicomponent gas real-time detection apparatus based on the demodulation of quartz tuning-fork frequency division |
| CN113218901A (en) * | 2021-05-07 | 2021-08-06 | 安徽大学 | Cavity enhanced spectrum gas detection device and method based on micro quartz crystal oscillator array detector |
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2012
- 2012-05-11 CN CN 201220210744 patent/CN202770761U/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103389270A (en) * | 2012-05-11 | 2013-11-13 | 张妍 | Apparatus for measuring concentration of trace gas, and method thereof |
| CN103792195A (en) * | 2014-01-15 | 2014-05-14 | 山西大学 | Double-optical-path photoacoustic spectrometry detection module and gas concentration detector by adopting module |
| CN103792195B (en) * | 2014-01-15 | 2016-05-11 | 山西大学 | Two light path optoacoustic spectroscopy detecting modules and adopt the gas concentration detector of this module |
| CN104251842A (en) * | 2014-08-29 | 2014-12-31 | 浙江省计量科学研究院 | Method for realization of online calibration of photoacoustic spectroscopy system pool constants by use of oxygen in atmosphere |
| CN108593763A (en) * | 2018-03-26 | 2018-09-28 | 山东大学 | A kind of multicomponent gas real-time detection apparatus based on the demodulation of quartz tuning-fork frequency division |
| CN108593763B (en) * | 2018-03-26 | 2021-03-30 | 山东大学 | Real-time detection device for multi-component gas based on quartz tuning fork frequency division demodulation |
| CN113218901A (en) * | 2021-05-07 | 2021-08-06 | 安徽大学 | Cavity enhanced spectrum gas detection device and method based on micro quartz crystal oscillator array detector |
| CN113218901B (en) * | 2021-05-07 | 2022-10-28 | 安徽大学 | Cavity enhanced spectrum gas detection device and method based on micro quartz crystal oscillator array detector |
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