CN204882347U - Quasi -real time photomultiplier detains background device - Google Patents
Quasi -real time photomultiplier detains background device Download PDFInfo
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- CN204882347U CN204882347U CN201520581793.0U CN201520581793U CN204882347U CN 204882347 U CN204882347 U CN 204882347U CN 201520581793 U CN201520581793 U CN 201520581793U CN 204882347 U CN204882347 U CN 204882347U
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Abstract
The utility model discloses a quasi -real time photomultiplier detains background device, including the photomultiplier that can be light signal conversion the photosignal, photomultiplier's tube socket and two pulse trigger circuit signal connection, photomultiplier's tube socket still with the data collection card signal connection that is used for receiving the photosignal, two pulse trigger circuit with be used for making the sample send the laser instrument signal connection of fluorescence to the sample lasing in the sample cell, two pulse trigger circuit still with data collection card signal connection. It utilizes two pulse trigger circuit to produce two gate pulses, gathers the the fluorescence signal and the bias light signal of the bias light that has superposeed respectively, and effectively background correction light has improved the measuring accuracy to the influence of fluorescence measuring greatly.
Description
Technical field
The utility model relates to signal measurement technique field, especially one quasi real time photomultiplier buckle Background apparatus.
Background technology
Photomultiplier (PMT) is the high electrooptical device of a kind of sensitivity, and have higher frequency response, be commonly used to the detection realizing faint optical signal, be applied to the fields such as spectral analysis, remote sensing satellite measurement, high-energy physics, medical imaging diagnosis, environmental monitoring, astronomical research.
Photomultiplier has 10
5~ 10
8current gain, its negative electrode noise has considerable influence to measurement, so people reduce the noise of PMT by normally closed pattern, can also reduce the history effect of PMT simultaneously.
In actual detection, due to the impact of bias light change on flashlight, comparatively big error can be caused to measurement.Therefore, consider a kind of gating circuit with button background functions of design, utilize this circuit realiration double sampling: sampled signal light superposes with bias light, once only to sample bias light, the mode background correction light of recycling difference on the impact of signal, thus reaches the object improving measurement accuracy.
Summary of the invention
Technical problem to be solved in the utility model is the present situation for prior art, provides structure simple, and the one that effectively can improve measurement accuracy quasi real time photomultiplier buckle Background apparatus.
The utility model solves the problems of the technologies described above adopted technical scheme:
One quasi real time photomultiplier buckles Background apparatus, include the photomultiplier that light signal can be converted to photosignal, the base of photomultiplier is connected with Two-pulse triggering circuit signal, the base of photomultiplier is also connected with the data acquisition card signal for receiving photosignal, Two-pulse triggering circuit is connected with the laser signal for making sample send fluorescence to the electromagnetic radiation laser in sample cell, and Two-pulse triggering circuit is also connected with data acquisition card signal.
For optimizing technique scheme, the concrete measure taked also comprises:
Above-mentioned Two-pulse triggering circuit comprises two-way pulse-generating circuit:
One tunnel: signal input part is connected with described data acquisition card signal through U11A, U11B;
Another road: signal input part is through U11C, be connected with the 2nd leg signal of monostalbe trigger U12A after U11D, 13rd pin of monostalbe trigger U12A is connected with the 2nd leg signal of monostalbe trigger U13A, 4th pin of monostalbe trigger U12A is connected with the 10th leg signal of monostalbe trigger U13B, 13rd pin of monostalbe trigger U13A and the 5th pin of monostalbe trigger U13B are respectively with the 2nd pin of U14A with the 3rd pin is corresponding is connected, 1st pin of U14A exports through the 10th pin of U11E, after being input to 2nd ~ 9 pins of U15 three-state transceiver, export from 11st ~ 18 pins of U15 and be connected with described photomultiplier tube signal.
The model of above-mentioned monostalbe trigger is 74LS221.
The model of above-mentioned three-state transceiver is 74LS245.
Compared with prior art, the utility model one quasi real time photomultiplier is buckled Background apparatus and is utilized Two-pulse triggering circuit to produce two gating pulses, first gating pulse makes photomultiplier receive fluorescence and bias light, gathered by data collecting card after being converted to photosignal, second gating pulse makes photomultiplier receive bias light, gathered by data collecting card after being converted to photosignal, the background light signal that data collecting card obtains according to the fluorescence signal having superposed bias light obtained for the first time and second time, obtain having deducted the fluorescence signal of bias light after process and complete measurement, the utility model effectively can remove the impact of bias light on fluorescence signal, thus greatly improves the accuracy of measurement.
Accompanying drawing explanation
Fig. 1 is block diagram of the present utility model;
Fig. 2 is the Two-pulse triggering circuit diagram in Fig. 1;
Fig. 3 is the function chard of monostalbe trigger 74LS221;
Fig. 4 is the function chard of three-state transceiver 74LS245;
Fig. 5 is photomultiplier gating pulse sequential chart;
Fig. 6 is the pulse sequence figure that Background apparatus buckled by photomultiplier;
Fig. 7 is the utility model signals collecting comparison diagram in different weather situation;
Fig. 8 is the normalization fluorescence intensity figure adopting optical filter circle collection method to obtain;
Fig. 9 is the normalization fluorescence intensity figure adopting the utility model to collect.
Embodiment
Below in conjunction with accompanying drawing embodiment, the utility model is described in further detail.
Be structural representation of the present utility model as depicted in figs. 1 and 2,
Reference numeral is wherein: photomultiplier 1, Two-pulse triggering circuit 2, data collecting card 3, sample cell 4, laser instrument 5.
The utility model one quasi real time photomultiplier buckles Background apparatus, include the photomultiplier 1 that light signal can be converted to photosignal, the base of photomultiplier 1 is connected with Two-pulse triggering circuit 2 signal, the base of photomultiplier 1 is also connected with data collecting card 3 signal for receiving photosignal, Two-pulse triggering circuit 2 is connected with laser instrument 5 signal for making sample send fluorescence to the electromagnetic radiation laser in sample cell 4, and Two-pulse triggering circuit 2 is also connected with data collecting card 3 signal.
In embodiment, Two-pulse triggering circuit comprises two-way pulse-generating circuit:
One tunnel: signal input part is connected with described data collecting card 3 signal through U11A, U11B;
Another road: signal input part is through U11C, be connected with the 2nd leg signal of monostalbe trigger U12A after U11D, 13rd pin of monostalbe trigger U12A is connected with the 2nd leg signal of monostalbe trigger U13A, 4th pin of monostalbe trigger U12A is connected with the 10th leg signal of monostalbe trigger U13B, 13rd pin of monostalbe trigger U13A and the 5th pin of monostalbe trigger U13B are respectively with the 2nd pin of U14A with the 3rd pin is corresponding is connected, 1st pin of U14A exports through the 10th pin of U11E, after being input to 2nd ~ 9 pins of U15 three-state transceiver, export from 11st ~ 18 pins of U15 and be connected with described photomultiplier 1 signal.
In embodiment, the model of monostalbe trigger is 74LS221.
In embodiment, the model of three-state transceiver is 74LS245.
The implementation method of Background apparatus buckled by above-mentioned quasi real time photomultiplier, comprises the following steps:
Step one: start laser instrument, laser instrument sends Q-switch synchronizing signal triggering Two-pulse triggering circuit and sends pulse signal, and Two-pulse triggering circuit sends two-way pulse, a road trigger data acquisition card job, and photomultiplier work is triggered on another road;
Step 2: Two-pulse triggering circuit sends first gating pulse makes photomultiplier arrive front opening at laser, the sample that laser instrument sets out in laser irradiation sample cell produces fluorescence, photomultiplier receives fluorescence and bias light, and exporting data collecting card to after being converted to photosignal, first gating pulse trigger data acquisition clamping that Two-pulse triggering circuit sends simultaneously is received and has been superposed the fluorescence signal of bias light;
Step 3: Two-pulse triggering circuit sends second gating pulse and makes photomultiplier work, at this moment laser disappears, photomultiplier receives bias light, and exporting data collecting card to after being converted to photosignal, background light signal is received in second gating pulse trigger data acquisition clamping that Two-pulse triggering circuit sends simultaneously;
Step 4: what step 2 obtained has superposed the background light signal obtained in the fluorescence signal deduction step three of bias light, obtains fluorescence signal, completes measurement.
Photomultiplier buckles the pulse sequence figure of Background apparatus as shown in Figure 6.
For the interference avoiding parasitic light and daylight to detect week fluorescent, the photomultiplier of select tape gate, usual photomultiplier is in normally off, needs to be opened by photomultiplier by positive pulse during Received signal strength, receives fluorescence signal.Light pulse for same amplitude inputs, and during without gate-control signal, photomultiplier exports when just having a gate-control signal 1/1000, and to the fatigue improving signal to noise ratio (S/N ratio) and prevent photomultiplier from causing by strong illumination for a long time, good effect is played in impaired and hangover.When pulse width is less than 2.8us, it is certain that photomultiplier exports.Two-pulse triggering circuit provides pulse signal for photomultiplier, the photomultiplier being in normally off is opened when the rising edge of pulse signal arrives, receives fluorescence signal.
Adopt monostalbe trigger in Two-pulse triggering circuit, monostalbe trigger only has a stable state 0 or 1.The work characteristics of monostalbe trigger is: (1), when not being subject to extraneous trigger pulse effect, monostalbe trigger remains on stable state; (2) when being subject to extraneous trigger pulse effect, monostalbe trigger overturns, and enters " temporary stable state ".If stable state is 0, then stable state is 1 temporarily; (3) through after a while, monostalbe trigger returns stable state from temporary stable state.Monostalbe trigger only depends on the parameter of circuit itself in the time of temporary steady-state residence.
The monostalbe trigger 74LS221 adopted in this Two-pulse triggering circuit is the integrated monostalbe trigger that can not weigh Trigger Function, the impact not by trigger pulse frequency between temporary steady state period.Suppose that the output pulse width of monostalbe trigger is T second, two trigger pulse successively arrival of being separated by τ second, τ <T, so, it enters temporary stable state under the effect of first trigger pulse, and this temporary stable state does not also terminate, and second trigger pulse just reaches.For the monostalbe trigger of Retargetable compiler, circuit will be triggered again, and the width exporting pulse equals τ+T second; For the monostalbe trigger of not Retargetable compiler, circuit will not triggered again, and the width exporting pulse equals T second.The width TW now exporting pulse depends on the resistance value that trigger is external and capacitance:
TW=n2*Rext*Cext≈0.7Rext*Cext。
Wherein: TW unit ns, Rext unit K Ω, Cext unit pF.By selecting suitable time element, output pulse width is adjustable within the scope of 35ns ~ 70s.As Rext=2K Ω, during Cext=0, typical output pulse width is 30ns.The stability of pulse width affects little by power supply and temperature, but large by the impact of the precision of external time element.To output pulse width and input pulse width dutycycle excessive or too small, the value of Rext should be strengthened to reduce pulse jitter as far as possible.As shown in Figure 3, select input and output logic to be that CLEAR=1, A=0, B rising edge triggers in design, export positive pulse signal.The rising edge of B is provided by laser Q switch syncout pulse (having ± 500ns time delay), guarantees to meet laser and sends timing requirements between photomultiplier fluorescence reception.
Due to the amplitude of Two-pulse triggering circuit paired pulses, rising edge and driving force require higher, pulse output stage has added a slice three-state transceiver 74LS245, it is the three-state transceiver of enhancement mode, it is low-power consumption, the COMS integrated circuit of high anti-jamming capacity, can drive 15 LSTTL loads simultaneously.Utilize it that the pulse signal that monostalbe trigger exports is carried out shaping in this circuit, strengthen its high level amplitude and be approximately full width and be added in PMT gating circuit, could the switch transition of driving gate control circuit.Shown in its input and output logical table Fig. 4, Two-pulse triggering circuit as shown in Figure 2.
Wherein, circuit 2-1, utilizes Q pulses generation pulse1, i.e. the trigger pulse of data collecting card; Circuit 2-2, utilizes Q pulse to produce Q1 respectively, Q2 two pulses; Q1, Q2 are input to circuit 2-3, finally produce pulse2, i.e. the gating pulse of photomultiplier; Pulse2 is input to circuit 2-4, is the driving force in order to intensifier pulse, improves pulse to the burst capability of photomultiplier, and the pulse2out finally exported is actual photomultiplier gate pulse signals.
Namely the process that described Two-pulse triggering circuit exports gating pulse is: Q-switch synchronizing signal exports the trigger pulse pulse1 of data collecting card through U11A, U11B; Simultaneously, Q-switch synchronizing signal exports Q1 pulse and Q2 pulse through monostalbe trigger U12A, Q1 Puled input monostalbe trigger U13A, Q2 Puled input monostalbe trigger U13B, Q1 pulse and Q2 pulse respectively correspondence produce pulse2 after inputting monostalbe trigger U13A and monostalbe trigger U13B, and pulse2 is output photoelectric multiplier tube gating pulse after three-state transceiver strengthens.
Q-switch synchronism output makes first order monostalbe trigger produce two anti-phase pulse signals as trigger pulse, the monostalbe trigger being added to the second level respectively produces the pulse of two μ s levels, adds OR circuit and export dipulse.The interval of two pulses and pulse width are all adjustable, and pulsing circuit exports pulse sequence as shown in Figure 5.
This photomultiplier button Background apparatus is utilized to gather signal in different weather situation, shown in collection result Fig. 7.As seen from Figure 7, two light intensity signals can be adopted in data acquisition each time.First gating pulse adopts the rear orientation light (comprising fluorescence and bias light) of water surface when laser gets to the water surface, adopts when getting to the water surface without laser, the rear orientation light (bias light) of the water surface when second gating pulse arrives.In Fig. 7, a part is owing to being the cloudy day, and background light signal is very little.When in Fig. 7, b part is fine day, receive just to sunlight, background light signal is very strong.Two light intensity datas of homogeneous collection are spaced apart musec order, and interval time is extremely short, and bias light change is very little, can be equal to the bias light sending out the laser moment (during first gating pulse) by approximate for the bias light adopted during second gating pulse.Thus after decreasing and measuring circulation at one in the past, then measure the comparatively big error that bias light brings.
Adopt traditional optical filter circle collection method to carry out identical water body to be measured with the utility model below, both contrasts obtain two different normalization fluorescence intensity figure after digital signal processing.As can be seen from Fig. 8, Fig. 9, same measuring object repeatedly excites the normalization fluorescence intensity collected, and the data discrete of optical filter circle collection is comparatively large, and the normalization fluorescence intensity repeatability obtained after the utility model background correction better.Analyze gained measurement data, the average relative error that optical filter circle collection obtains measurement data is 7.97%, maximum relative error ± 25%.And the utility model obtains the average relative error 0.97% of measurement data, maximum relative error is less than 1.5%, and the utility model substantially increases degree of accuracy.
According to noisiness and the hysteresis characteristic of photomultiplier, long-time easily tired by strong illumination photomultiplier, not only noise is large, also because not recovering to cause conditions of streaking in a period of time after being filled with high light, then the accurate detection of photomultiplier to hypofluorescence signal can be affected after amplifying.The utility model utilizes Two-pulse triggering circuit effectively to achieve the deduction of bias light, eliminates the impact of bias light on fluorescence measurement, also effectively suppresses the noise of photomultiplier and reduces the hysteresis characteristic of photomultiplier.
Most preferred embodiment of the present utility model is illustrated, and the various change made by those of ordinary skill in the art or remodeling all can not depart from scope of the present utility model.
Claims (4)
1. one kind quasi real time photomultiplier buckle Background apparatus, include the photomultiplier (1) that light signal can be converted to photosignal, it is characterized in that: the base of described photomultiplier (1) is connected with Two-pulse triggering circuit (2) signal, the base of described photomultiplier (1) is also connected with data collecting card (3) signal for receiving photosignal, described Two-pulse triggering circuit (2) is connected with laser instrument (5) signal for making sample send fluorescence to the electromagnetic radiation laser in sample cell (4), described Two-pulse triggering circuit (2) is also connected with described data collecting card (3) signal.
2. one according to claim 1 quasi real time photomultiplier buckle Background apparatus, it is characterized in that: described Two-pulse triggering circuit comprises two-way pulse-generating circuit:
One tunnel: signal input part is connected with described data collecting card (3) signal through U11A, U11B;
Another road: signal input part is through U11C, be connected with the 2nd leg signal of monostalbe trigger U12A after U11D, 13rd pin of monostalbe trigger U12A is connected with the 2nd leg signal of monostalbe trigger U13A, 4th pin of monostalbe trigger U12A is connected with the 10th leg signal of monostalbe trigger U13B, 13rd pin of monostalbe trigger U13A and the 5th pin of monostalbe trigger U13B are respectively with the 2nd pin of U14A with the 3rd pin is corresponding is connected, 1st pin of U14A exports through the 10th pin of U11E, after being input to 2nd ~ 9 pins of U15 three-state transceiver, export from 11st ~ 18 pins of U15 and be connected with described photomultiplier (1) signal.
3. one according to claim 2 quasi real time photomultiplier buckle Background apparatus, it is characterized in that: the model of described monostalbe trigger is 74LS221.
4. one according to claim 3 quasi real time photomultiplier buckle Background apparatus, it is characterized in that: the model of described three-state transceiver is 74LS245.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105842221A (en) * | 2016-05-31 | 2016-08-10 | 北京金索坤技术开发有限公司 | Atomic fluorescence spectrometer and background subtraction method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105842221A (en) * | 2016-05-31 | 2016-08-10 | 北京金索坤技术开发有限公司 | Atomic fluorescence spectrometer and background subtraction method thereof |
| CN105842221B (en) * | 2016-05-31 | 2018-10-12 | 北京金索坤技术开发有限公司 | Atomic Fluorescence Spectrometer background deduction method and Atomic Fluorescence Spectrometer |
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