CN1139800C - Wavelength-modulated polarized surface plasma wave sensor - Google Patents
Wavelength-modulated polarized surface plasma wave sensor Download PDFInfo
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- CN1139800C CN1139800C CNB011366737A CN01136673A CN1139800C CN 1139800 C CN1139800 C CN 1139800C CN B011366737 A CNB011366737 A CN B011366737A CN 01136673 A CN01136673 A CN 01136673A CN 1139800 C CN1139800 C CN 1139800C
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- polarized light
- light
- linearly polarized
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- 238000013461 design Methods 0.000 description 6
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- 239000012467 final product Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
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Abstract
The present invention relates to a wavelength-modulated polarized surface plasma wave sensor which comprises a laser, a polarizer, a sensing component, a 1/4 wave plate, an analyzer, a photoelectric converter, a phase-locking amplifier, a computer and a signal generator. Laser light generated by the laser device passes through the polarizer to be converted into linearly polarized light. The linearly polarized light irradiates a light reflection surface in the sensing component. After the linearly polarized light is reflected, emergent light passes through the 1/4 wave plate to be converted into left-hand turning circular polarized light and right-hand turning circular polarized light. Through the analyzer, the left-hand turning circular polarized light and the right-hand turning circular polarized light are converted into linearly polarized light. Through the photoelectric converter, the linearly polarized light is converted into an electrical signal. After the electrical signal passes through the phase-locking amplifier, the electrical signal is inputted into the computer, and a measuring result is displayed. The signal generator sends out a signal to modulate the wavelength of the laser light of the laser device, and simultaneously, the signal is inputted into the phase-locking amplifier to demodulate a photoelectric conversion signal. An optical system can lead the background of the intensity of direct current light of an operating point to be equal to zero on theory through modulation, and therefore, the influence from white noises of the optical system to measurement is reduced. Therefore, the resolution of the measurement is further improved.
Description
Technical field
The present invention relates to a kind of Wavelength-modulated polarized surface plasma wave sensor, belong to the industrial test technical field.
Background technology
Though be called spr sensor by custom, actual be the SPR testing tool of an optical, mechanical and electronic integration to surface plasma wave sensor [English Surface Plasmon Resonance sensor is called for short spr sensor].This instrument is mainly used in physics, chemistry and biological field about the membrane system The Characteristic Study.Especially in the biological membrane engineering, eucaryotic cell structure, the application in fields such as membrance chemistry has wide future.
The mechanism of spr sensor is P ripple resonance laser surface plasma wave, its reflection coefficient
Very responsive to refractive index near the excitating surface medium.Can determine change of refractive by measurement to the reflected light characteristic.Reflection coefficient
Be plural number, this represents that not only amplitude changes, and the phase place generation transition of reflection.The S ripple can not the excitating surface plasma ripple, and in interested scope, S wave reflection rate is approximately 1, and phase approximation is a constant.Common spr sensor incident wave only contains the P ripple, only utilizes the amplitude characteristic of P wave reflection coefficient, can be called the amplitude type spr sensor.1994, the applicant proposed, and adds the S ripple in incident wave, utilizes P ripple and S wave interference, had so just utilized the amplitude and the phase propetry of P wave reflection coefficient simultaneously, and this spr sensor can provide better resolution.Since 1999, this interferometric sensor had reported in literature successively abroad.Experiment has proved that all this sensor is better than amplitude type.The applicant improved this sensor again afterwards, had added modulation technique and weak signal detection technology, and resolution is improved again, and refractive index resolution can reach 1 * 10
-7The technical disadvantages that exists among the patent CN1215152A that we applied in the past is that working point direct current light intensity background is non-vanishing in theory, (if be zero, sensitivity also is zero).Because white noise is proportional to the evolution of direct current light intensity, thereby the noise of sensor is also bigger.
Summary of the invention
The objective of the invention is to design a kind of Wavelength-modulated polarized surface plasma wave sensor, making it is zero in place, working point direct current light intensity background in theory, thereby further improves the resolution of sensor.
The Wavelength-modulated polarized surface plasma wave sensor of the present invention's design comprises laser instrument, the polarizer, surface plasma wave excitation apparatus, quarter wave plate, analyzer, photoelectric commutator, lock-in amplifier, computing machine and signal generator; The laser that is produced by laser instrument becomes linearly polarized light behind the polarizer, this linearly polarized light incides the light reflection surface in the surface plasma wave excitation apparatus, emergent light after the reflection becomes left-handed behind quarter wave plate and dextrorotation garden polarized light, the garden polarized light becomes linearly polarized light through analyzer, this linearly polarized light is converted into electric signal through photoelectric commutator, this electric signal is imported computing machine behind lock-in amplifier, show measurement result, signal generator sends signal the optical maser wavelength of laser instrument is modulated, import lock-in amplifier simultaneously, photoelectric conversion signal is carried out demodulation.
The sensor of the present invention's design, compared with the prior art, the present invention adopts wavelength-modulated but not the magneto-optic modulation; In addition, the optical system that the present invention provides can be by regulating, and making working point direct current light intensity background is zero in theory, thereby has reduced the influence of white noise to measuring of optical system, can further improve the resolution of measurement.
Description of drawings
Fig. 1 is the prior art structural representation.
Fig. 2 is the structural representation of the sensor that designs of the present invention.
Among Fig. 1 and Fig. 2, the 1st, laser instrument, the 2nd, the polarizer, the 3rd, magneto-optic modulator, the 4th, surface plasma wave excitation apparatus, the 5th, quarter wave plate, the 6th, analyzer, the 7th, photelectric receiver, the 8th, signal generator, the 9th, lock-in amplifier, the 10th, A/D converter, the 11st, computing machine.
Embodiment
As shown in Figure 2, the Wavelength-modulated polarized surface plasma wave sensor of the present invention's design comprises laser instrument, the polarizer, surface plasma wave excitation apparatus, quarter wave plate, analyzer, photoelectric commutator, lock-in amplifier, computing machine and signal generator; The laser that is produced by laser instrument becomes linearly polarized light behind the polarizer, this linearly polarized light incides the light reflection surface in the surface plasma wave excitation apparatus, emergent light after the reflection becomes left-handed behind quarter wave plate and dextrorotation garden polarized light, the garden polarized light becomes linearly polarized light through analyzer, this linearly polarized light is converted into electric signal through photoelectric commutator, this electric signal is imported computing machine behind lock-in amplifier, show measurement result, signal generator sends signal the optical maser wavelength of laser instrument is modulated, import lock-in amplifier simultaneously, photoelectric conversion signal is carried out demodulation.
The principle of work of the sensor is as follows: laser becomes linearly polarized light through the polarizer 2, and incident light promptly contains P ripple E
pContain S ripple E again
sMade folk prescription to P ripple angle be α, then E
p, E
sWith α relation is arranged
E
s/E
p＝tgα
P ripple excitating surface is the ion bulk wave, and its reflection coefficient is
It is refractive index function to be measured.The S ripple can not the excitating surface plasma ripple, and reflection coefficient is
Order
R wherein
sBe about 1,
sBe approximately a constant.The Wavelength of Laser modulation is to realize by the electric current that changes semiconductor laser.If modulated amplitude is M ', modulating frequency Ω.In P wave reflection rate smallest point, this wavelength-modulated is in fact only to
pPlay modulating action, be equivalent to phase modulation (PM).Its phase modulation (PM) amplitude size
λ wherein
0Be resonant wavelength.Light by with P ripple quarter wave plate at 45 after, P ripple and S wavelength-division do not become left-handed and right-circularly polarized light.Become same directional ray polarized light through analyzer, produce and interfere.If the angle of analyzer analyzing direction and P ripple is θ, then photoelectricity by the light intensity signal of receiving the device reception is
Though following formula is complicated, physical significance is simple, and in the situation of θ=0 M=0, following formula is equivalent to E
sRipple and
Two wave interferences, order
p=
P0+ Δ
p wherein
P0Working point for our selection.When not adding modulation, be that zero condition is at working point I:
Like this can be by regulating the polarizer 13, just
Tg α=r
p4.1 formulas are met.By transferring analyzer that 4.2 formulas are met.The direct current light intensity is zero in theory when being implemented in the working point and not modulating.
When 4.1 formulas and 4.2 formulas all are met,
I＝2r
pE
sE
p[1-cos(Δ
p+MsinΩt)] (5)
Because M and Δ
pAll be small quantity, (5) formula is launched with platform labor formula:
I＝r
pE
sE
p[Δ
p 2+M
2sin
2Ωt] (6)
+2r
pE
sE
pΔ
pMsinΩt
(6) first of formula contains the direct current background, but it is a second order a small amount of, more much smaller than the scheme that previous patent is given.Second for frequency be Ω signal, it is proportional to Δ
pAnd M.Can be with lock-in amplifier with Δ
pDetect.Refractive index detection resolution
With prior art relatively, this scheme debugging is also more convenient.
Optical system shown in Figure 2 is an embodiment.Wherein laser instrument selects semiconductor laser, and power 1.5-3mw gets final product.Polarizer analyzer just can with the absorbing sheet polarizer.Photelectric receiver gets final product with the PIN pipe.Signal generator and lock-in amplifier, computing machine all have product.
In the sensor of the present invention, though on the sensing element light reflection surface golden film thickness can to satisfy working point place direct current light intensity background in very wide scope be zero in theory, it is proper to advise that golden film thickness is got 40-45nm.
At any place of resonance excitation surface plasma wave SPR spectrum, though can be elected to be the working point, making the direct current light intensity is zero in theory.But the suggestion working point is selected in r
PminThe place, or as close as possible.
The adjustment method of the sensor of the present invention's design is as follows:
1, rotate the polarizer, make α=0, this moment, instrument was equivalent to the amplitude type spr sensor, changed incident angle, found r
PminThe position and write down size.
2, rotating the polarizer makes as far as possible
3, do not add modulation signal, rotate the position that analyzer 17 finds direct current light intensity minimum.
4, the fine setting polarizer.Further find the position of direct current light intensity minimum.At this moment the size of direct current should be zero in theory.In fact can reach 1 * 10 of incident intensity
-3Below.
5, add modulation, start working.
The laser of other wavelength or the method for other modulation wavelength do not influence this programme and implement.
With the method for other phase compensation, be zero in theory as long as satisfy working point direct current light intensity, do not influence this programme and implement.
Claims (1)
1, a kind of Wavelength-modulated polarized surface plasma wave sensor, it is characterized in that this sensor comprises laser instrument, the polarizer, the surface plasma wave excitation apparatus, quarter wave plate, analyzer, photoelectric commutator, lock-in amplifier, computing machine and signal generator, the laser that is produced by laser instrument becomes linearly polarized light behind the polarizer, this linearly polarized light incides the light reflection surface in the surface plasma wave excitation apparatus, emergent light after the reflection becomes left-handed behind quarter wave plate and dextrorotation garden polarized light, the garden polarized light becomes linearly polarized light through analyzer, this linearly polarized light is converted into electric signal through photoelectric commutator, this electric signal is imported computing machine behind lock-in amplifier, show measurement result, signal generator sends signal the optical maser wavelength of laser instrument is modulated, import lock-in amplifier simultaneously, photoelectric conversion signal is carried out demodulation.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011366737A CN1139800C (en) | 2001-10-26 | 2001-10-26 | Wavelength-modulated polarized surface plasma wave sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011366737A CN1139800C (en) | 2001-10-26 | 2001-10-26 | Wavelength-modulated polarized surface plasma wave sensor |
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| CN1342895A CN1342895A (en) | 2002-04-03 |
| CN1139800C true CN1139800C (en) | 2004-02-25 |
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| CNB011366737A Expired - Fee Related CN1139800C (en) | 2001-10-26 | 2001-10-26 | Wavelength-modulated polarized surface plasma wave sensor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI548870B (en) * | 2014-10-09 | 2016-09-11 | Adjustable Sensitivity Phase Measurement System |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101398378B (en) * | 2008-01-28 | 2011-06-15 | 国家纳米科学中心 | Phase measurement method of surface plasma resonance and measuring system thereof |
| CN101825568B (en) * | 2010-03-31 | 2012-01-04 | 中国科学院半导体研究所 | Device for detecting medium refraction index change by utilizing spectrum intensity change |
| CN102226722B (en) * | 2011-03-29 | 2013-03-20 | 韦占雄 | Wavelength detector of fiber grating sensor |
-
2001
- 2001-10-26 CN CNB011366737A patent/CN1139800C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI548870B (en) * | 2014-10-09 | 2016-09-11 | Adjustable Sensitivity Phase Measurement System |
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