CN102288550A - Differential measuring method and device applicable to photoelectric detection - Google Patents
Differential measuring method and device applicable to photoelectric detection Download PDFInfo
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- 238000013461 design Methods 0.000 description 6
- 229910000661 Mercury cadmium telluride Inorganic materials 0.000 description 5
- VONWDASPFIQPDY-UHFFFAOYSA-N dimethyl methylphosphonate Chemical compound COP(C)(=O)OC VONWDASPFIQPDY-UHFFFAOYSA-N 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
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- HZCDANOFLILNSA-UHFFFAOYSA-N Dimethyl hydrogen phosphite Chemical class COP(=O)OC HZCDANOFLILNSA-UHFFFAOYSA-N 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical group OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
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- 150000002903 organophosphorus compounds Chemical class 0.000 description 1
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- -1 phosphonate ester compound Chemical class 0.000 description 1
- 230000005622 photoelectricity Effects 0.000 description 1
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Abstract
The invention discloses differential measuring method and device applicable to photoelectric detection. The method comprises the following steps: 1) selecting a range overlapped with one characteristic wave spectrum peak of a chemical substance to be measured on a light spectrum as a resonant wave zone; 2) using a range which comprises the resonant wave zone, but is wider than the resonant wave zone, and is further not overlapped with other wave spectrum peak of the chemical substance to be measured on the light spectrum as a reference wave zone; 3) measuring the intensity I1 and the intensity I2 of an electromagnetic wave signal to be measured at the resonant wave zone and the reference wave zone; and 4) comparing I1 with (I2-I1), and determining a detection result. If the detection result is influenced as the resonant wave zone is too wide, the step 4) is not executed, and the following steps are executed, namely, 5) setting a wavelength range which is narrower than the resonant wave zone and further has representativeness as a second resonant wave zone; 6) measuring the intensity I1' of the electromagnetic wave signal to be measured in the second resonant wave zone; and 7) comparing I1' with (I2-I1'). The device comprises a single-optical-path system and a multi-optical-path system. By using the method and the device, the sensitivity and the precision for detection can be effectively improved, and the manufacturing difficulty of relevant optical components is decreased.
Description
Technical field
The present invention relates to a kind of difference measurement method and device, particularly a kind of difference measurement method and device that is applicable to Photoelectric Detection.
Background technology
Can interact between light and the chemical substance.With the infrared light is example, and after a branch of infrared light saw through certain chemical substance steam, the infrared light of some specific wavelength will be absorbed by the molecule of this chemical substance and be converted into the rotation energy and/or the energy of vibration of these molecules.Otherwise during environment temperature around the temperature of this chemical substance surpasses it, this chemical substance will outwards give off the infrared light of identical specific wavelength.These certain wavelengths are called the characteristic wavelength of this chemical substance.The pairing characteristic wavelength of specific chemical is certain.Utilize this principle, can by measure an infrared radiation signal the relative intensity on the characteristic wavelength of certain chemical substance (promptly with respect in the intensity on the non-characteristic wavelength) detect this infrared radiation signal whether have this kind chemical substance on the path of process; And then, if there is this kind chemical substance, can measure the size of its dosage, perhaps measure temperature difference of itself and surrounding environment etc.
In order to realize above-mentioned Photoelectric Detection, must take the following step: at first, the intensity of measuring light signal on some characteristic wavelengths of chemical substance to be measured, secondly, the intensity of measuring light signal on the some non-characteristic wavelength of chemical substance to be measured, at last, relatively both difference obtain the relative intensity value.This assay method is called difference measurement method or colorimetric measurement method, and wherein selected non-characteristic wavelength is called reference wavelength, and selected characteristic wavelength is also referred to as resonant wavelength.
At present, at the infrared radiation detection apparatus of particular chemicals and infrared thermometer ripe product is arranged all, wherein some model adopts method of difference or colourimetry exactly.And in fact except infrared light, also there is the electromagnetic wave that utilizes other wavelength to carry out the example of difference measurement or colorimetric measurement.
On the infrared spectrum of chemical substance, its characteristic wavelength is usually expressed as wave spectrum peak or the wave spectrum band with certain width.So when specifically implementing Differential Detection, what at first will do is position and the width of determining resonant wavelength and reference wavelength.Here, we are respectively they be referred to as to resonate wavestrips and with reference to wavestrip.The principle of determining be the resonance wavestrip should with some characteristic peak overlaids of chemical substance to be measured, with reference to wavestrip then not should with any characteristic peak overlaid of chemical substance to be measured.Here, the selection with reference to wavestrip is an easy ignored problems.In fact, when carrying out design of Optical System, the requirement of intimate contradiction is arranged for the selection of reference wavestrip.On the one hand, should be positioned as close to the resonance wavestrip with reference to wavestrip, so that reduce optical system error to greatest extent, on the other hand, should maintain a certain distance with the resonance wavestrip with reference to wavestrip, in order to avoid reduce the intensity of differential signal with reference to the root at wavestrip and characteristic spectrum peak overlaps.Such requirement makes with reference to the selection of wavestrip sometimes very difficult.And that existing technology is considered in this respect is less, usually has certain randomness when the selection of carrying out with reference to wavestrip.For example, United States Patent (USP) № 6853452 (inventor Gabriel Laufer) has proposed a kind of device that uses difference detecting method to carry out the remote measurement of volatile organic compound, but this patent does not provide convictive reason in the selection of reference wavestrip.Undoubtedly, elective is disadvantageous with reference to wavestrip for the signal to noise ratio (S/N ratio) that reduces optical system error and raising differential signal.
Summary of the invention
The present invention proposes a kind of difference measurement method and device that is applicable to Photoelectric Detection, this method is adopting prior art to select reference wave to have the selection problem that can solve effectively at need with reference to wavestrip.
For this reason, the present invention is by the following technical solutions:
A kind of difference measurement method that is applicable to Photoelectric Detection, it comprises the steps:
1.1) select with the some characteristic wave spectrum peak equitant scope of chemical substance to be measured on spectrum as the resonance wavestrip;
1.2) will comprise the resonance wavestrip but than the wideer scope of resonance wavestrip as the reference wavestrip, and this scope not with chemical substance to be measured other wave spectrum peak overlaid on spectrum;
1.3) measure electromagnetic wave signal to be measured respectively in the intensity I of resonance on the wavestrip
1With the intensity I on the reference wavestrip
2
1.4) comparison I
1And I
2-I
1, determine testing result.
Further:
1.3) in, if because of the resonance wavestrip select the too wide requirement that causes testing result not reach expection, then stop step 1.4) and change following steps:
1.5) selected one than the narrow scope of above-mentioned resonance wavestrip as the second resonance wavestrip, this second resonance wavestrip only contains the crest portion at characteristic wave spectrum peak;
1.6) intensity I of mensuration electromagnetic wave signal to be measured in the second resonance wavestrip
1';
1.7) comparison I
1' and I
2-I
1, determine testing result.
In step 1.1) in, for fear of the root at resonance wavestrip pairing characteristic wave spectrum peak with overlap with reference to wavestrip, can select the resonance wavestrip slightly wideer than the characteristic wave spectrum peak of selected chemical substance to be measured.
In step 1.4) in, relatively I of one of following two formula can be adopted
1And I
2-I
1:
Diff represents difference value signal in the formula, and constant term a and b are the parameters of introducing in order to eliminate baseline noise, and constant term k is a scale factor.
In step 1.7) in, relatively I of one of following two formula can be adopted
1' and I
2-I
1:
Diff represents difference value signal in the formula, and constant term a and b are the parameters of introducing in order to eliminate baseline noise, and constant term k is a scale factor.
The present invention has also designed corresponding difference measurement device according to said method, comprises monochromatic light drive test amount device and multi-pass measurement mechanism.
This monochromatic light drive test amount device comprises receiving optics, switching device of optical fiber, filter set, photodetector assembly and signal processing unit, and wherein: described filter set comprises several optical filters, and each optical filter is fixed on the switching device of optical fiber; Described receiving optics is adjusted to a light beam that meets the requirements with light signal to be measured; Described switching device of optical fiber places after the receiving optics, and by the action of this switching device of optical fiber, each optical filter can alternately be cut described light beam it is filtered; Described photodetector assembly places after the switching device of optical fiber, detects the intensity through the light beam after filtering; The output of described photodetector assembly is connected with signal processing unit; Described signal processing unit carries out necessary pre-service (amplification, noise reduction etc.) to the signal from photodetector assembly, compares computing then, and shows operation result.
Further:
Described switching device of optical fiber is rotary disk or stripe board that can be reciprocating.
Described filter set comprises that a feature optical filter and one are with reference to optical filter, wherein: the band of described feature optical filter logical with chemical substance to be measured certain characteristic wave spectrum peak overlaid on spectrum; Described band with reference to optical filter is logical, and to comprise the band of feature optical filter logical but wideer than the latter, and not with chemical substance to be measured other wave spectrum peak overlaid on spectrum.
The band of described feature optical filter leads to and chemical substance to be measured certain characteristic wave spectrum peak overlaid and wideer than the latter on spectrum.
Described filter set also comprises one second feature optical filter, the logical crest portion that only comprises the characteristic wave spectrum peak of the pairing chemical substance to be measured of feature optical filter of the band of this second feature optical filter, thus logical narrower than the band of feature optical filter, have more representativeness.
This multi-pass difference measurement device comprises receiving optics, filter set, photodetector assembly and signal processing unit, and wherein: described filter set comprises that a feature optical filter and one are with reference to optical filter; Described receiving optics is adjusted to a plurality of light beams that meet the requirements with light signal to be measured, and the number of the optical filter that is comprised in the number of the light beam of its output and the described filter set is identical; The light beam that each optical filter in the described filter set is cut receiving optics output respectively filters to it; Described photodetector assembly places after the filter set, measures the intensity through each light beam after filtering; Described signal processing unit connects the output of photodetector assembly, and the signal from photodetector assembly is carried out necessary pre-service (amplification, noise reduction etc.), compares computing then, and shows operation result.
Further:
Logical and the some characteristic wave spectrum peak overlaid of chemical substance to be measured on spectrum of the band of the feature optical filter in the described filter set;
The band of the reference optical filter in the described filter set is logical, and to comprise the band of feature optical filter logical but wideer than the latter, and not with chemical substance to be measured other wave spectrum peak overlaid on spectrum.
Described filter set also comprises the second feature optical filter, the logical crest portion that only comprises the characteristic wave spectrum peak of the pairing chemical substance to be measured of feature optical filter of the band of this second feature optical filter, thereby logical narrower than the band of feature optical filter, have more representativeness.
The band of the feature optical filter in the described filter set logical with the some characteristic wave spectrum peak overlaid of chemical substance to be measured on spectrum and wideer than the latter.
Advantage of the present invention is: can effectively improve detection sensitivity and precision, and reduce the manufacture difficulty of relevant optical device.
Description of drawings
Fig. 1 is a difference detecting method synoptic diagram of the present invention;
Fig. 2 is the DMMP infrared spectrogram;
Fig. 3 is a monochromatic light road pick-up unit structural drawing;
Fig. 4 uses the chopper wheel synoptic diagram for optical filter switches;
Fig. 5 is a double light path pick-up unit structural drawing.
Embodiment
The present invention proposes a kind of reference wavestrip system of selection of uniqueness, thereby formed a kind of new difference measurement method.In some cases, this method can overcome the deficiencies in the prior art, effectively improves detection sensitivity and precision, and reduces the manufacture difficulty of relevant optical device.The present invention has also designed corresponding difference measurement device according to said method.
The present invention is further described below in conjunction with drawings and Examples.
The difference measurement method that the present invention proposes is made of following steps:
The first step, determine the resonance wavestrip by following principle: (1) resonance wavestrip and the some characteristic wave spectrum peak overlaid of chemical substance to be measured on spectrum, (2) in some cases, in order to guarantee detection sensitivity and precision, can select the resonance wavestrip slightly wideer than wave spectrum peak.Establishing this scope herein is from λ
1To λ
2(λ
2＞λ
1); λ
1And λ
2Be respectively the initial wavelength at selected chemical substance characteristic wave spectrum to be measured peak and stop wavelength, perhaps, in some cases, in order to guarantee detection sensitivity and precision, λ
1Expression is than a smaller wavelength of initial wavelength at selected chemical substance characteristic wave spectrum to be measured peak; λ
2Expression is than a bigger wavelength of termination wavelength at selected chemical substance characteristic wave spectrum to be measured peak.
Wave spectrum peak on the said herein spectrum is meant an electromagnetic wavelength or wavelength coverage, electromagnetic wave in this wavelength or wavelength coverage is compared with the electromagnetic wave in wave spectrum peak scope not, stronger interaction can take place with chemical substance to be measured in the former, and because there is significant difference in the interaction degree, so on spectrogram, formed crest.So-called characteristic wave spectrum peak is meant that chemical substance to be measured is peculiar or can represents the wave spectrum peak of chemical substance structure feature to be measured.
In second step, determine with reference to wavestrip by following principle: (1) comprises the resonance wavestrip with reference to wavestrip but is wideer than it, soon is chosen to be from (λ with reference to wavestrip
1-Δ
1) to (λ
2+ Δ
2), Δ herein
1〉=0, Δ
2〉=0 and the two be not zero simultaneously, Δ
1Be meant difference, Δ with reference to initial wavelength with the initial wavelength of resonance wavestrip of wavestrip
2Be meant that (2) are from (λ with reference to the difference of termination wavelength with the termination wavelength of resonance wavestrip of wavestrip
1-Δ
1) to (λ
2+ Δ
2) this scope not with chemical substance to be measured other wave spectrum peak overlaid on spectrum.
In the 3rd step, measure intensity (the be characteristic signal intensity) I of electromagnetic wave signal to be measured respectively in above-mentioned resonance wavestrip
1With above-mentioned intensity (being reference signal intensity) I with reference to wavestrip
2
Said herein electromagnetic wave signal to be measured is meant with chemical substance to be measured and taken place to interact or might interactional electromagnetic wave signal take place with chemical substance to be measured, therefore can realize detection to chemical substance to be measured by detecting it.
The 4th step, relatively I
1(I
2-I
1, determine testing result.Be meant herein the comparison operation result is compared with a standard value as an important evidence, perhaps in continuous coverage, compare, determine current testing result with the measurement result of front.
Comparison operation can be adopted following formula:
Or Diff ∝ I
1-k (I
2-I
1) (2)
Here Diff represents difference value signal, and ∝ represents proportional relation, and constant term k is a scale factor.According to circumstances be multiplied by the important criterion that a coefficient is exactly a testing result, the quality of Diff data directly influences detection sensitivity and precision.
In order to eliminate baseline noise, can in formula (1), introduce two constant term a and b:
Constant term a, b and k can be before Differential Detection by experiment method or the method for Theoretical Calculation assignment in advance.Can get zero at baseline noise than hour a and b, formula this moment (3) has just become formula (1).Under many circumstances, the functional value of Differential Detection result and above-mentioned difference value, such as | Diff|, Diff
2, lnDiff
2, exp Diff etc. is associated.
If because of the resonance wavestrip select the too wide requirement that causes testing result not reach expection, execution in step four not then, then carry out following steps:
The 5th step, selected second a resonance wavestrip narrower than above-mentioned resonance wavestrip, it only contains the top of characteristic peak, thus narrower than the resonance wavestrip, have more representativeness.Concrete width value can be decided as the case may be.Suppose that herein the second resonance wavestrip is from (λ
1+ Δ
3) to (λ
2-Δ
4), (λ
1+ Δ
3)＜(λ
2-Δ
4), Δ
3〉=0, Δ
4〉=0 and the two be not zero simultaneously.
The 6th step, gather electromagnetic wave signal to be measured, measure its intensity (promptly strengthening characteristic signal intensity) I in the second resonance wavestrip
1'.
The 7th step, relatively I
1' and (I
2-I
1), determine testing result.Comparison operation can be adopted following formula:
Or Diff ∝ I
1'-k (I
2-I
1) (5)
Meaning every in the formula is the same.
Below by legend characteristics of the present invention are described more intuitively.Fig. 1 is the spectrogram of width of cloth simulation, and the horizontal ordinate among the figure is represented wavelength.On this width of cloth simulated spectra, two wave spectrum peaks are arranged, and close together, wherein higher crest is represented the characteristic peak of certain chemical substance.If utilize the photoelectricity means that this chemical substance is detected, can adopt the Differential Detection method.The selected naturally A interval of being annotated in the drawings of resonance wavestrip.According to existing technology, select one in the middle of C, the D that is annotated in the drawings with reference to wavestrip and three intervals of E.But in the case of this example, if select the D interval, because the influence of another crest with reference to wavestrip, interval range can only be very narrow, and this just might reduce the signal to noise ratio (S/N ratio) of photodetection, and then the degree of accuracy of influence detection, and interval range is narrow more, and the difficulty that optical device is made is big more.Select the C interval also to have identical problem.If the E interval of being annotated among the selection figure, because A is interval and the E interval is too far away from getting, this just might increase the error of optical system, and is subjected to the influence of various disturbing factors easily.In this case, we select the B interval just can overcome above-mentioned each shortcoming as the reference wavestrip.The B interval is being equal in width to the interval and interval sum of D of C after deduction A interval, width is bigger, can obtain higher signal to noise ratio (S/N ratio).And very near from the A interval, optical system error is less, and the probability that influenced by various disturbing factors is less.Simultaneously, because the interval broad of B, so the manufacture difficulty of relevant optical device is less.The cost of being paid is a just many step subtraction (I
2-I
1).
In some cases, cause the signal to noise ratio (S/N ratio) of differential signal not high enough, can select second a narrower resonance wavestrip A ' to replace A if the resonance wavestrip is too wide.
This detection method has very big application space, such as, in previously described various infrared radiation detection apparatus and infrared thermometer, all can obtain to use.
Application example
Organic phosphorus compound be a class than particular compound, they generally all have the different toxicity of degree, and have stronger volatility, form large-area pollution easily in case be leaked in the air.Therefore, phosphonate ester compound being implemented monitoring has great importance.
With first fluorinated phosphonic acid dimethyl ester (DMMP) is example.Fig. 2 is the infrared spectrogram of DMMP, and the horizontal ordinate among the figure is represented wave number (cm
-1).As can be seen from the figure, this compound is at 1057cm
-1There is a very strong crest at the place, and this is the characteristic peak that is formed by phosphonate groups P-O-C, this external 1074cm
-1Near a stronger peak is also arranged, two peaks overlap and form the wave spectrum band of a broad.All there is other crest to exist on these wave spectrum band both sides.If carry out difference detecting, the resonance wavestrip roughly should be selected 1007～1139cm
-1Between (perhaps being shown between 8.78～9.93 μ m), i.e. zone 2 of being annotated among the figure with wavelength table.If with reference to the zone 6 (939～1007cm that annotated among the wavestrip selection figure
-1Between), so, because width that should the zone is narrower, just following situation may occur: the signal to noise ratio (S/N ratio) of signal is lower, and the manufacture difficulty of optical filter is bigger.If with reference to the zone 8 (＞1336cm that annotated among the wavestrip selection figure
-1), so, because this region distance resonant wavelength zone is far away, just following situation might occur: optical system error is bigger, and it is bigger to be subjected to the probability of various disturbing factors influence.According to method proposed by the invention, the scope of reference wavelength selected the zone 4 (939～1169cm that annotated in the drawings
-1Between, perhaps be shown between 8.55～10.65 μ m with wavelength table), the problems referred to above just might be overcome or alleviate so.
In order to implement above-mentioned infrared monitoring, can make up a monochromatic light road photoelectric detection system as shown in Figure 3 at DMMP.This device comprises that a receiving optics 22, switching device of optical fiber 30, a band lead at 1007～1139cm
-1Between optical filter 26, a band lead at 939～1169cm
-1Between optical filter 28, a photodetector assembly 34 and a signal processing unit 38 form.Wherein: described receiving optics 22 is adjusted to a light beam that meets the requirements with light signal to be measured; Described switching device of optical fiber 30 places after the receiving optics 22, and by the action of this switching device of optical fiber, optical filter 26 and 28 can alternately be cut described light beam it is filtered; Described photodetector assembly 34 places after the switching device of optical fiber 30, detects the intensity through the light beam after filtering; Described signal processing unit 38 is connected with the output of photodetector assembly 34, and the signal from photodetector assembly is carried out necessary pre-service (amplification, noise reduction etc.), compares computing then, and shows operation result.
Receiving optics 22 is combinations of various optical device.Typical receiving optics can be with an autocollimator, such as Newton formula telescope or Cassegrain formula reflecting telescope, is used with some auxiliary lens and constitutes.
The effect of switching device of optical fiber 30 is light beams 24 that it can make optical filter 26 and 28 alternately export by receiving optics 22.Typical switching device of optical fiber is a chopper wheel.This is a rotary disk.Fixed thereon of two optical filters.Two optical filters of rotation by chopper wheel just can alternately enter light path.The structure of chopper wheel is seen shown in Figure 4.The center of rotation of 40 expression chopper wheels among the figure.It is right on the dish a plurality of optical filters can be installed, and realizes the monitoring to multiple compound.In addition, switching device of optical fiber also can adopt a stripe board that can move reciprocatingly.
Photodetector assembly 34 is the devices that light signal can be changed into electric signal, and it is made of light activated element and some annexes.Inject the photosurface of photodetector assembly 34 and change into electric signal 36 through the light signal 32 after filtering.For the infrared light of above-mentioned wavelength coverage, light activated element commonly used is to make with HgCdTe alloy semiconductor material.Possible annex has refrigeration system, beam convergence system etc.The effect of refrigeration system is that light activated element is cooled off.When the HgCdTe detector is surveyed 8～12 microns infrared bands, the HgCdTe detector need be cooled to the performance that just can guarantee detector about absolute temperature 77K and normally bring into play.Because the photosurface of light activated element is very little usually, so if the bundle spot diameter of incident is bigger, a beam convergence system focuses on light beam 32 with regard to needs.Electric signal 36 entering signal the processing units 38 processed and demonstrations of photodetector assembly 34 outputs.Signal processing unit 38 is one and the electric signal of input can be amplified, noise reduction, mould/number conversion, storage, two signals is carried out calculus of differences or other contrast computing, and output and show the electronic circuit of operation result and the combination of program software.A single-chip microcomputer and relevant peripheral hardware can satisfy these requirements.Constant term a in the comparison operation formula, the value of b and k is a problem deserving of attention, each Devices Characteristics is relevant in the parameter of their numerical values recited and optical filter and the whole device, can pre-determine by the method for serial experiment.
If the signal to noise ratio (S/N ratio) of testing result is not high enough, perhaps when accuracy of detection is had relatively high expectations, can the setting district between from 1030 to 1101cm
-1As the second resonance wavestrip (the regional 2b that is annotated among Fig. 2).These need are set up the optical filter (being the 26b among Fig. 3) of a corresponding wavelength scope and can be realized on chopper wheel 30.On the other hand, the bandwidth of feature optical filter is relaxed slightly (relax to 1005～1145cm such as the zone 2 of will be annotated among Fig. 2
-1), the root that also might eliminate characteristic peak impacts the intensity of differential signal, and then improves the signal to noise ratio (S/N ratio) of differential signal.
Relevant studies show that, the optimal detection performance of light activated element HgCdTe alloy semiconductor material is relevant with infrared light wavelength, if so 8 conducts of the selection zone that Fig. 2 annotated are with reference to wavestrip, so because zone 8 will certainly cause the output of photodetector assembly 34 not take into account with regional 2 apart from each others and influence detection sensitivity.If the selection 6 zone conducts that Fig. 2 annotated are with reference to wavestrip, because this scope width is narrower, so the intensity of useful light signal 32 will remain on lower level, this certainly will cause the signal to noise ratio (S/N ratio) of electric signal 36 also lower so.The HgCdTe material can constantly have noise output when work, this noise is caused that by thermal perturbation this also needs it is cooled to the reason of 77K low temperature just.
Except monochromatic light road detection scheme shown in Figure 3, can also adopt the multi-pass detection scheme: device is made of two or three light paths (to be measured if desired and strengthens the characteristic signal intensity I
1' be exactly three light channel structures, if do not need to measure I
1' then be bifocal path structure), each optical filter inserts respectively in each light path and filters, and photodetector is measured the intensity after each light beam filters respectively.Fig. 5 is a double light path pick-up unit synoptic diagram.This double light path device comprises a receiving optics 50, feature optical filter 26, one with reference to optical filter 28, photodetector assembly 60 and signal processing unit 66.Receiving optics two light beams 52 of 50 outputs and 54, optical filter 26 and optical filter 28 filter and insert these two light beams respectively it is filtered, arrive photodetector assembly 60 through the light beam 56 after filtering and 58 and be transformed into electric signal 62 and 64, pre-service such as this electric signal input signal processing unit 70 amplifies, noise reduction, compare computing then, and show operation result.
In order to realize double light path output, a simple design of receiving optics 50 is that the receiving optics 22 that two or three are shown in Figure 3 is combined.Another way is that a receiving optics 22 and a beam splitter are united use.So-called beam splitter is exactly a kind of eyeglass that the light beam part of incident can be seen through part reflection.After a branch of light arrived beam splitter, a part of light wherein will be through forming a light beam, and another part is reflected and forms another light beam.Certainly, because two light beams are not in the same way, so the direction that may also need a folding mirror to regulate one of them light beam.
In order to detect the intensity of a plurality of light beams, photodetector assembly 60 can comprise two or three light activated elements, may comprise annexes such as refrigeration system, light beam collecting system in addition.
Similar with monochromatic light road detection system, if the signal to noise ratio (S/N ratio) of testing result is not high enough, perhaps when accuracy of detection is had relatively high expectations, can set up one and strengthen feature optical filter 26b (this moment, device became three light channel structures), perhaps the bandwidth of feature optical filter be relaxed slightly (such as relaxing to 1005～1145cm
-1) improve the signal to noise ratio (S/N ratio) of differential signal.
The multi-pass design proposal is compared with monochromatic light road design proposal respectively relative merits.But no matter adopting the multi-pass design proposal still is monochromatic light road design proposal, and the problem that faces on the reference wavelength scope is selected is similar, no matter is to adopt the zone 6 or the zone 8 of being annotated among Fig. 2 all favourable not as zone 4.
Obviously, just can the change detection target in the above-mentioned detection device by changing optical filter and/or photodetector.So the application of this device is very widely.In a word, more than describe and just prove an evidence of feasibility of the present invention, and should not become limitation of the present invention.
Claims (16)
1. a difference measurement method that is applicable to Photoelectric Detection is characterized in that comprising the steps:
1.1) select with the some characteristic wave spectrum peak equitant scope of chemical substance to be measured on spectrum as the resonance wavestrip;
1.2) will comprise the resonance wavestrip but than the wideer scope of resonance wavestrip as the reference wavestrip, and this scope not with chemical substance to be measured other wave spectrum peak overlaid on spectrum;
1.3) measure electromagnetic wave signal to be measured respectively in the intensity I of resonance on the wavestrip
1With the intensity I on the reference wavestrip
2
1.4) comparison I
1And I
2-I
1, determine testing result.
2. the difference measurement method that is applicable to Photoelectric Detection as claimed in claim 1 is characterized in that:
1.3) in, if, then stop step 1.4 because of the too wide requirement that causes testing result not reach expection of resonance wavestrip) and change following steps:
1.5) selected one than the narrow scope of above-mentioned resonance wavestrip as the second resonance wavestrip, this second resonance wavestrip only contains the crest portion at characteristic wave spectrum peak;
1.6) intensity I of mensuration electromagnetic wave signal to be measured in the second resonance wavestrip
1';
1.7) comparison I
1' and I
2-I
1, determine testing result.
3. the difference measurement method that is applicable to Photoelectric Detection as claimed in claim 1 or 2 is characterized in that:
In step 1.1) in, for fear of the root at resonance wavestrip pairing characteristic wave spectrum peak with overlap with reference to wavestrip, can select the resonance wavestrip slightly wideer than the characteristic wave spectrum peak of selected chemical substance to be measured.
4. difference measurement method as claimed in claim 1 is characterized in that:
In step 1.4) in, formula adopted
Or Diff ∝ I
1-k (I
2-I
1Compare I
1And I
2-I
1,
Diff represents difference value signal in the formula, and constant term a and b are the parameters of introducing in order to eliminate baseline noise, and k is a scale factor.
5. the difference measurement method that is applicable to Photoelectric Detection as claimed in claim 2 is characterized in that:
In step 1.7) in, formula adopted
Or Diff ∝ I
1'-k (I
2-I
1) comparison I
1' and I
2-I
1,
Diff represents difference value signal in the formula, and constant term a and b are the parameters of introducing in order to eliminate baseline noise, and k is a scale factor.
6. monochromatic light road difference measurement device that is applicable to Photoelectric Detection is characterized in that:
It comprises receiving optics, switching device of optical fiber, filter set, photodetector assembly and signal processing unit, wherein:
Described filter set comprises several optical filters, and each optical filter is fixed on the switching device of optical fiber;
Described receiving optics is adjusted to a light beam that meets the requirements with light signal to be measured;
Described switching device of optical fiber places after the receiving optics, and by the action of this switching device of optical fiber, each optical filter can alternately be cut described light beam it is filtered;
Described photodetector assembly places after the switching device of optical fiber, detects the intensity through the light beam after filtering;
Described signal processing unit connects the output of photodetector assembly, at first comprise the pre-service of necessity of amplification, noise reduction from the signal of photodetector assembly, compares computing then, and shows operation result.
7. the monochromatic light road difference measurement device that is applicable to Photoelectric Detection as claimed in claim 6 is characterized in that described switching device of optical fiber is rotary disk.
8. the monochromatic light road difference measurement device that is applicable to Photoelectric Detection as claimed in claim 6, it is characterized in that described switching device of optical fiber be can be reciprocating stripe board.
9. as the described monochromatic light road difference measurement device that is applicable to Photoelectric Detection of one of claim 6 to 8, it is characterized in that:
Described filter set comprises that a feature optical filter and one are with reference to optical filter, wherein:
Logical and chemical substance to be measured certain the characteristic wave spectrum peak overlaid on spectrum of the band of described feature optical filter;
Described band with reference to optical filter is logical, and to comprise the band of feature optical filter logical but wideer than the latter, and not with chemical substance to be measured other wave spectrum peak overlaid on spectrum.
10. the monochromatic light road difference measurement device that is applicable to Photoelectric Detection as claimed in claim 9 is characterized in that:
The band of described feature optical filter leads to and chemical substance to be measured certain characteristic wave spectrum peak overlaid and wideer than the latter on spectrum.
11. the monochromatic light road difference measurement device that is applicable to Photoelectric Detection as claimed in claim 9 is characterized in that:
Described filter set also comprises one second feature optical filter, the logical crest portion that only comprises the characteristic wave spectrum peak of the pairing chemical substance to be measured of feature optical filter of the band of this second feature optical filter, thus logical narrower than the band of feature optical filter, have more representativeness.
12. the monochromatic light road difference measurement device that is applicable to Photoelectric Detection as claimed in claim 10 is characterized in that:
Described filter set also comprises one second feature optical filter, the logical crest portion that only comprises the characteristic wave spectrum peak of the pairing chemical substance to be measured of feature optical filter of the band of this second feature optical filter, thus logical narrower than the band of feature optical filter, have more representativeness.
13. a multi-pass difference measurement device that is applicable to Photoelectric Detection is characterized in that:
It comprises receiving optics, filter set, photodetector assembly and signal processing unit, wherein:
Described filter set comprises that a feature optical filter and one are with reference to optical filter;
Described receiving optics is adjusted to a plurality of light beams that meet the requirements with light signal to be measured, and the number of the optical filter that is comprised in the number of the light beam of its output and the described filter set is identical;
The light beam that each optical filter in the described filter set is cut receiving optics output respectively filters to it;
Described photodetector assembly places after the filter set, measures the intensity through each light beam after filtering;
Described signal processing unit connects the output of photodetector assembly, at first comprise the pre-service of necessity of amplification, noise reduction from the signal of photodetector assembly, compares computing then, and shows operation result.
14. the multi-pass difference measurement device that is applicable to Photoelectric Detection as claimed in claim 13 is characterized in that:
Logical and the some characteristic wave spectrum peak overlaid of chemical substance to be measured on spectrum of the band of the feature optical filter in the described filter set;
The band of the reference optical filter in the described filter set is logical, and to comprise the band of feature optical filter logical but wideer than the latter, and not with chemical substance to be measured other wave spectrum peak overlaid on spectrum.
15. the multi-pass difference measurement device that is applicable to Photoelectric Detection as claimed in claim 14 is characterized in that:
Described filter set also comprises the second feature optical filter, the logical crest portion that only comprises the characteristic wave spectrum peak of the pairing chemical substance to be measured of feature optical filter of the band of this second feature optical filter, thereby logical narrower than the band of feature optical filter, have more representativeness.
16., it is characterized in that as claim 14 or 15 described difference measurement devices:
The band of the feature optical filter in the described filter set logical with the some characteristic wave spectrum peak overlaid of chemical substance to be measured on spectrum and wideer than the latter.
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|---|---|---|---|
| CN 201010296529 CN102288550B (en) | 2010-06-21 | 2010-09-29 | Differential measuring method and device applicable to photoelectric detection |
| PCT/CN2010/080236 WO2011160412A1 (en) | 2010-06-21 | 2010-12-24 | Differential measuring method and device adapted for optoelectronic detection |
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| CN201010211731 | 2010-06-21 | ||
| CN201010211731.2 | 2010-06-21 | ||
| CN 201010296529 CN102288550B (en) | 2010-06-21 | 2010-09-29 | Differential measuring method and device applicable to photoelectric detection |
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| CN102288550B CN102288550B (en) | 2013-03-27 |
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Cited By (4)
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|---|---|---|---|---|
| CN107271053A (en) * | 2017-06-30 | 2017-10-20 | 电子科技大学 | A kind of integrated optical circuit device for aero engine turbine blades temperature monitoring |
| US10126251B2 (en) | 2014-12-02 | 2018-11-13 | Kla-Tencor Corporation | Inspection systems and techniques with enhanced detection |
| CN113466258A (en) * | 2021-07-30 | 2021-10-01 | 深圳中科飞测科技股份有限公司 | Detection system and detection method |
| CN115561203A (en) * | 2021-07-01 | 2023-01-03 | 长春理工大学 | Near-infrared fruit sugar degree nondestructive testing device based on multiband difference method |
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| CN115561203A (en) * | 2021-07-01 | 2023-01-03 | 长春理工大学 | Near-infrared fruit sugar degree nondestructive testing device based on multiband difference method |
| CN113466258A (en) * | 2021-07-30 | 2021-10-01 | 深圳中科飞测科技股份有限公司 | Detection system and detection method |
Also Published As
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| CN102288550B (en) | 2013-03-27 |
| WO2011160412A1 (en) | 2011-12-29 |
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