CN1108760A - High-precision polarization-modulating type optical fiber sensor compensating method - Google Patents
High-precision polarization-modulating type optical fiber sensor compensating method Download PDFInfo
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- CN1108760A CN1108760A CN 94115471 CN94115471A CN1108760A CN 1108760 A CN1108760 A CN 1108760A CN 94115471 CN94115471 CN 94115471 CN 94115471 A CN94115471 A CN 94115471A CN 1108760 A CN1108760 A CN 1108760A
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000013307 optical fiber Substances 0.000 title claims description 16
- 230000010287 polarization Effects 0.000 claims abstract description 20
- 239000011540 sensing material Substances 0.000 claims abstract description 11
- 230000005540 biological transmission Effects 0.000 claims description 14
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 239000000835 fiber Substances 0.000 abstract description 18
- 230000003287 optical effect Effects 0.000 abstract description 12
- 239000000523 sample Substances 0.000 abstract description 12
- 230000007774 longterm Effects 0.000 abstract description 3
- 238000003384 imaging method Methods 0.000 abstract 1
- 239000013078 crystal Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000005259 measurement Methods 0.000 description 5
- 230000004043 responsiveness Effects 0.000 description 5
- 230000002411 adverse Effects 0.000 description 4
- 230000005684 electric field Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
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Abstract
The high accuracy compensation method, is characterized in that reflecting optical path is adopted in the sensor probe, the same polarization beam splitting prism is used as both polarizer and polarization detector. Two channels of incident lights reflected by the sensing material are splitted and combined and form with two autofocusing lenses into fully symmetrical two sets of collimation imaging systems. Said two channel lights are produced by single light separately. The optic fibre sensor formed by said compensation method features simple structure, high measuring accuracy, and good long term stability.
Description
The invention belongs to the design field of polarization-modulating type optical fiber sensor, particularly the compensation method of this class sensor measurement.
Polarization-modulating type optical fiber sensor has been widely used in the measurement of various physical quantitys.In order to improve the measuring accuracy of polarization-modulating type optical fiber sensor, and can work steadily in the long term when telemeasurement, the adverse effect that its light source luminescent power, fiber transmission attenuation and photodetector responsiveness change measurement result must be compensated.In addition, each optical element loss characteristic variations of sensing probe also must be repaid the influence of measuring.Chinese patent 87104439.0 has proposed a kind of method that two light sources are alternately luminous, double detector is surveyed the realization compensation simultaneously that adopts, as shown in Figure 1, its basic characteristics are to use a polarization splitting prism (11) and to close bundle from the two-way incident beam beam splitting of two light sources (1), (2) (the center light wavelength is identical) in sensing head (23), wherein lead up to sensitive material (9), another road is by sensitive material (9), beam splitting and close bundle after reach two photodetectors by two root receiving fibers respectively.This compensation method can only be to the redeeming that influences of power swing, fiber transmission attenuation and the photodetector responsiveness of light source, and all can't compensate the loss characteristic variations of each optical element of sensor probe.Moreover, this method adopts two light sources, the consistance of the drift characteristic that be difficult to guarantee its centre wavelength and spectral characteristic and produce with factors vary such as extraneous factor such as drive current, temperature has so just reduced the compensation effect of this compensation method, so has been difficult to realize high-acruracy survey.Realize many, the complex structure of the required element of this method in addition, cause certain difficulty for extensively implementing this method.
The objective of the invention is to overcome the weak point of prior art, adopt source, unit timesharing formation double light path and sensing probe to adopt new designs such as reflective light path, make it have better compensation effect, sensor measurement precision height, good stability, simple in structure, volume are become a reality for a short time.
The present invention proposes a kind of high-precision polarization-modulating type optical fiber sensor compensating method, it is characterized in that sensing material places between λ/8 wave plates and the completely reflecting mirror, polarization splitting prism places the opposite side of this λ/8 wave plates, first, second GRIN Lens is vertically set on two adjacent surfaces of this polarization splitting prism respectively, first, two GRIN Lens are with first, two road light beam timesharing collimation is directional light, successively pass through polarization splitting prism, λ/8 wave plates, sensing material, after the total reflective mirror reflection, resolve into transmission and folded light beam, more respectively by first by polarization splitting prism, two GRIN Lens injection fibres are by first, two photodetectors receive delivers to signal processing system.
Said first and second GRIN Lens end face is identical to the spectro-film light path of said Amici prism, constitutes the complete two symmetrical groups colimated light system of structure and two thus and forms the system that resembles.
Said first and second Lu Guangke is produced through a photoswitch timesharing by a branch of light that same light source produces.
Compensation method of the present invention is compared with Chinese patent Z87104439.0 number described compensation method, and its outstanding advantage is: the one, and sensing probe adopts reflective compensation light path, and is not only simple in structure, compact, and the sensitivity of sensor-based system is doubled; The 2nd, the two-way light of time-sharing work all passes through the sensing probe part, thereby each optical element characteristic variations of sensing probe is compensated the adverse effect of measuring; The 3rd, adopt the luminous working method of single light source timesharing, remedied the inconsistent adverse effect that causes of two light source luminescent characteristics;
Therefore this compensation method has more sensing measurement system measuring accuracy height, good long term stability, obtains compensation effect preferably.
The present invention proposes a kind of high-precision polarization-modulating type optical fiber sensor compensating method specific embodiment, and its principle signal as shown in Figure 2.Light emission one receives and signal processing system (30) is linked to each other by optical cable (50) with sensing probe (40).The light that light source (31) sends is converted to the two-way light that alternately timesharing is sent through photoswitch (32).First via light reaches sensing probe (40) through fiber coupler (33) and optical fiber (38), be directional light by GRIN Lens (41) collimation, successively by polarization splitting prism (43), λ/8 wave plates (44) and sensing material (45), reflect through total reflective mirror (46), light returns along input path, successively by sensing material (45) and λ/8 wave plates (44), be divided into two-beam by polarization splitting prism (43) by different polarization, transmitted light is by GRIN Lens (41) injection fibre (38), and reach photodetector (36) through fiber coupler (33), reflected light is by GRIN Lens (42) injection fibre (39), and reaching photodetector (35) through fiber coupler (34), the photosignal of detector (36) and (35) output is given signal processing system (37).Lens (41) the emergent light direction of propagation is decided to be the Z axle, and X, Y, Z axle are formed right angle right-handed coordinate system, the slow axis of λ/8 wave plates and X-axis angle at 45.
The second road light of control photoswitch (32) conversion reaches sensing probe (40) through fiber coupler (34) and optical fiber (39), be directional light by GRIN Lens (42) collimation, reflect through polarization splitting prism (43), successively by λ/8 wave plates (44) and sensing material (45), reflect through total reflective mirror (46), light returns along input path, successively by sensing material (45) and λ/8 wave plates (44), be divided into two-beam by polarization splitting prism (43) by different polarization, transmitted light is by GRIN Lens (41) injection fibre (38), and reach photodetector (36) through fiber coupler (33), reflected light is by GRIN Lens (42) injection fibre (39), and reaching photodetector (35) through fiber coupler (34), the photosignal of detector (36) and (35) output is given signal processing system (37).
Optical fiber (38) is identical with (39) parameter, GRIN Lens (41) is consistent with the parameter of (42), the two-way light that adopts the single light source timesharing to send has excited identical transmission optical mode in optical fiber (38) and (39), lens (41) are identical to the spectro-film light path of polarization splitting prism (43) with (42) end face, two lens are both as emission, again as receiving, constitute two groups of colimated light systems and two compositions thus and resemble system architecture symmetry fully, thereby it is identical to guarantee that two-way transmission light transmits optical mode in whole optical path.
Introduce compensation principle below:
Light source (31) sends light and is converted to the two-way light that alternately timesharing is sent by photoswitch (32):
When first via light is luminous, the photosignal i of detector (36) and (35) output
36And i
35Be respectively:
i
36＝ 1/2 I
0L
3YL
5L
5L′
3YR
36L
1K
2sin
2（ (π)/4 + (δ)/2 ） （1）
i
35＝ 1/2 I
0L
3YL
5L
6L′
4YR
35L
2KCOS
2（ (π)/4 + (δ)/2 ） （2）
[1], in [2] formula:
I
0-by the first via luminous power of photoswitch (32) outgoing;
L
3Y, L '
3Y-be respectively light positive to the reverse transmission coefficient by fiber coupler (33);
L
5, L
6-be respectively the transmission coefficient of light by optical fiber (38) and optical fiber (39);
L
1, L
2-be respectively the transmission coefficient of getting back to lens (41) and (42) by lens (41) outgoing directional light through light path system;
K-polarization splitting prism (43) transmitted light and catoptrical splitting ratio;
R
36, R
35-be respectively the responsiveness of photodetector (36) and (35);
δ-tested outfield causes the phasic difference that birefringence is introduced X, Y direction polarization in sensing material (45).
When the second road light is luminous, the photosignal i ' of detector (36) and (35) output
36And i '
35Be respectively:
i′
36＝ 1/2 I′
0L
4YL
6L
5L′
3YR
36L′
2Kcos
2（ (π)/4 + (δ)/2 ） （3）
i′
35＝ 1/2 I′
0L
4YL
6L
6L′
4YR
35L′
1sin
2（ (π)/4 + (δ)/2 ） （4）
(3), in (4) formula:
I '
0-by the second tunnel luminous power of photoswitch (2) outgoing;
L
4Y, L '
4Y-be respectively light positive to the reverse transmission coefficient by fiber coupler (34);
L '
1, L '
2-be respectively the transmission coefficient of getting back to lens (41) and (43) by lens (42) outgoing directional light through light path system.
Complete symmetry L by light path system noted earlier
1=L '
1, L
2=L '
2, then signal processing system (37) is carried out following computing to (1)-(4) the represented signal of formula and can be got:
（5）
As seen, Q and light source luminescent power, fiber transmission attenuation and photodetector responsiveness are irrelevant, and the variation of sensing probe Amici prism splitting ratio, optical element loss is also compensated, and have reached the purpose of compensation.
The present invention is applicable to the various compensation that utilize plane of polarization rotation or birefringence to change the polarization-modulating type optical fiber sensor that constitutes, to overcome each optical element loss characteristic variations of light source luminescent power, fiber transmission attenuation and photodetector responsiveness and sensing probe, The measuring precision and stability have been improved to measuring the adverse effect that produces.
Concrete applicating example of the present invention:
Optical fibre voltage sensor based on electrooptical effect.
Use Bi
4Ge
3O
12Crystal is as sensing material, and light is along＜110〉direction transmission of crystal, and tested electric field is applied on the crystal along＜110〉direction, and then electric field causes the phasic difference that birefringence produces:
δ＝ (2π)/(λ) n
3y
41E（2L） （6）
(6) in the formula:
Optical wavelength in λ-vacuum;
The refractive index of n-crystal;
y
41The electrooptical coefficient of-crystal;
The optical direction length of L-crystal.
Adopting the centre wavelength of light source is 0.85 μ m, for Bi
4Ge
3O
12Crystal, y
41=0.95 * 10
-12M/v, n=2.07 by measuring the Q value, just can obtain corresponding electric field strength E.
Claims (3)
1, a kind of high-precision polarization-modulating type optical fiber sensor compensating method, it is characterized in that sensing material places between λ/8 wave plates and the completely reflecting mirror, polarization splitting prism places the opposite side of this λ/8 wave plates, first, second GRIN Lens is vertically set on two adjacent surfaces of this polarization splitting prism respectively, first, two GRIN Lens are with first, two road light beam timesharing collimation is directional light, successively pass through polarization splitting prism, λ/8 wave plates, sensing material, after the total reflective mirror reflection, resolve into transmission and folded light beam, more respectively by first by polarization splitting prism, two GRIN Lens injection fibres are by first, two photodetectors receive delivers to signal processing system.
2, method according to claim 1 is characterized in that said first and second GRIN Lens end face is identical to the spectro-film light path of said Amici prism, constitutes the complete two symmetrical groups colimated light system of structure and two thus and forms the system that resembles.
3, method as claimed in claim 1 or 2 is characterized in that said first and second road light is produced through a photoswitch timesharing by a branch of light that same light source produces.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94115471 CN1108760A (en) | 1994-08-31 | 1994-08-31 | High-precision polarization-modulating type optical fiber sensor compensating method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94115471 CN1108760A (en) | 1994-08-31 | 1994-08-31 | High-precision polarization-modulating type optical fiber sensor compensating method |
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| Publication Number | Publication Date |
|---|---|
| CN1108760A true CN1108760A (en) | 1995-09-20 |
Family
ID=5037509
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| CN 94115471 Pending CN1108760A (en) | 1994-08-31 | 1994-08-31 | High-precision polarization-modulating type optical fiber sensor compensating method |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101325455B (en) * | 2008-07-30 | 2010-12-29 | 哈尔滨工程大学 | Apparatus for sensing demodulating double-datum length low coherent optical fiber ring network |
| CN104819737A (en) * | 2015-04-16 | 2015-08-05 | 厦门时变光纤传感技术有限公司 | Optical fiber sensing system and method for acquiring polarization-related measurement data |
| CN108709506A (en) * | 2018-08-01 | 2018-10-26 | 天津博科光电科技有限公司 | A kind of method using in optic fiber displacement sensor probe and optic fiber displacement sensor system |
| CN110044394A (en) * | 2019-05-08 | 2019-07-23 | 浙江大学昆山创新中心 | A kind of novel light wave leads phase-array scanning system |
| CN112198124A (en) * | 2019-11-15 | 2021-01-08 | 北京微芯区块链与边缘计算研究院 | Optical probe of optical fiber type full spectrum water quality sensor |
-
1994
- 1994-08-31 CN CN 94115471 patent/CN1108760A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101325455B (en) * | 2008-07-30 | 2010-12-29 | 哈尔滨工程大学 | Apparatus for sensing demodulating double-datum length low coherent optical fiber ring network |
| CN104819737A (en) * | 2015-04-16 | 2015-08-05 | 厦门时变光纤传感技术有限公司 | Optical fiber sensing system and method for acquiring polarization-related measurement data |
| CN104819737B (en) * | 2015-04-16 | 2017-06-27 | 厦门时变光纤传感技术有限公司 | A kind of method for obtaining the measurement data related to polarization |
| CN108709506A (en) * | 2018-08-01 | 2018-10-26 | 天津博科光电科技有限公司 | A kind of method using in optic fiber displacement sensor probe and optic fiber displacement sensor system |
| CN108709506B (en) * | 2018-08-01 | 2023-11-10 | 天津博科光电科技有限公司 | Optical fiber displacement sensing probe and optical fiber displacement sensing system |
| CN110044394A (en) * | 2019-05-08 | 2019-07-23 | 浙江大学昆山创新中心 | A kind of novel light wave leads phase-array scanning system |
| CN112198124A (en) * | 2019-11-15 | 2021-01-08 | 北京微芯区块链与边缘计算研究院 | Optical probe of optical fiber type full spectrum water quality sensor |
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