CN105866071A - Device for measuring refractive index through optical fiber interferometry - Google Patents
Device for measuring refractive index through optical fiber interferometry Download PDFInfo
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- CN105866071A CN105866071A CN201610383317.7A CN201610383317A CN105866071A CN 105866071 A CN105866071 A CN 105866071A CN 201610383317 A CN201610383317 A CN 201610383317A CN 105866071 A CN105866071 A CN 105866071A
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- refractive index
- collimator
- sample cell
- fiber optic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
- G01N2021/458—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods using interferential sensor, e.g. sensor fibre, possibly on optical waveguide
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- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention discloses a device for measuring a refractive index through an optical fiber interferometry. The device comprises a laser light source, a circulator, a sample reservoir, a photoelectric detector, a demodulation module and a collimator, wherein the collimator is arranged at one end of the sample reservoir; a 10%-reflecting 90%-transmission type lens is arranged in the collimator; a Faraday rotating mirror is arranged at the rear end of the sample reservoir; the light emitted from a laser passes through the collimator, and then becomes parallel light, emits into the sample reservoir and is reflected by the Faraday rotating mirror at the rear end; the Faraday rotating mirror can avoid the interference between the incident light and the reflected light in the sample reservoir; the two paths of light, namely, the reflecting light of the collimator and the reflecting light of the Faraday rotating mirror, have interference phenomenon. The device provided by the invention is high in measuring precision, is simple in structure, is easy to realize miniaturization, can be used for measuring various samples of gas and liquid, is wide in measuring scope of refractive index and can realize the digital automatic measurement.
Description
Technical field
The present invention relates to a kind of fiber optic interferometric method survey refractive index device, by optical fibre interference principle for gas,
The refractive index of liquid carries out the measurement of high-precision digital.
Background technology
At present, the method for traditional mensuration refractive index is mainly by Abbe refractometer measuring instrument, and Abbe refractometer is measured
Instrument mainly by the total reflection principle of light, forms full emission phenomena on the surface of fluid to be measured and prism, thus with critical angle
Position be axis formed light and shade boundary region, by detection light and shade border region position realize the refractive index to sample
Measurement.Due to use total reflection principle, measure refractive index scope be subject to certain restrictions, higher for refractive index or
Relatively low sample can not be measured.Abbe refractometer measuring instrument is built by pure physical optics device, and light path is built and adjustment difficulty,
Instrument integrated operation is complicated, and volume is big, is not easy to realize miniaturization and digitized measurement.Abbe refractometer measuring instrument is used for liquid
The measurement of the refractive index of body, the measurement for gas refracting index has certain limitation.
Pungent superintend and direct strong et al. (a kind of measuring device for liquid refractive index based on fiber optic interferometric, the patent No.:
201520180701.5) report the measuring device for liquid refractive index of a kind of fiber optic interferometric, do not mend between fiber optic interferometric two-arm
Repaying, extraneous vibration and temperature impact can bring additional optical path difference, cause measuring inaccurate, device entirety poor anti jamming capability,
Accuracy and precision declines.
Summary of the invention
In order to overcome tradition refractive index measuring instrument light path to build difficulty, use operation complexity, it is impossible to realize digitized automatic
Measuring, the ranges of indices of refraction of measurement is less waits deficiency, and the present invention provides the instrument of a kind of optical fibre interference refractive index, by light
Fine interferometry technology carries out high-acruracy survey to the refractive index of sample, and capacity of resisting disturbance is strong, refractometry wide ranges, detection
Specimen types is various, and instrument can realize digitized and measure function in real time.
The technical solution adopted for the present invention to solve the technical problems is: three ends of circulator respectively with laser instrument, sample
Pond and photodetector connect.The laser that laser instrument sends arrives sample cell through circulator, and sample cell is a transparent glass
Glass hole capital after selling all securities, has injection port and outlet, different samples can be injected by injection port, and the sample detected can lead to
Cross outlet to discharge.The front end of sample cell is equipped with optical fiber collimator, and collimator is saturating built with 10% reflection 90% transmission
Mirror, a part of incident illumination can be reflected back in optical fiber by lens, and a part of light is in collimator is injected into sample cell.It addition,
The incident illumination of optical fiber can be converted into directional light injection by collimator, in the rear end of sample cell equipped with faraday's rotating mirror, on minute surface
There is etch-proof plated film, be possible to prevent the sample corrosion to faraday's rotating mirror.By the directional light of collimator outgoing through sample cell
After, faraday's rotating mirror of rear end reflects, the reflection light in the reflection light of sample cell and collimator can interfere existing
As.Faraday's rotating mirror can be by the polarization state half-twist of incident illumination, the so incident illumination in sample cell and faraday's rotating mirror
Reflection light would not interfere, it is to avoid the change of the additional striped caused by interference.When sample pool being vacuum state
When, between reflection light and the reflection light of rear end faraday's rotating mirror of front collimation device, optical path difference is constant, and interference fringe is stable.
When being filled with sample, in sample pool, refractive index can occur to change accordingly, can produce corresponding optical path difference between two-way reflection light,
Interference fringe also can produce corresponding change.Device is originally as all optical fibre structure, and certainty of measurement is high, and corresponding speed is fast, it is to avoid
The complicated process that conventional light path is built.
In use, for gas and liquid sample, can first sample cell be evacuated, at this moment the refraction in sample pool
Rate is n=1, more tested gas or liquid sample is injected in sample pool, and corresponding refractive index changes, and optical path difference will
Corresponding change occurs, and interference fringe will produce corresponding change simultaneously, and the other end of circulator is connected on photodetector
Face, can detect the change of interference fringe corresponding phase place, and demodulation module is demodulated drawing corresponding interference information afterwards,
From which further follow that the refractive index of testing sample.
Compared with existing apparatus for measuring refractive index, the present invention has the advantage that
(1) all optical fibre structure, instead of building of traditional light path, it is to avoid complicated light path is built and calibration procedures,
And can be with electromagnetism interference, stability increases.
(2) using optical fibre interference principle, certainty of measurement is high, and responding range is big.
(3) this light path design can offset the impact of external ambient temperature and vibration, improves certainty of measurement and anti-interference
Ability.
(4) refractive index of liquids and gases sample can be measured, measure specimen types many, refractometry scope
Greatly.
Accompanying drawing explanation
Fig. 1 is optical fibre interference refractive index device system diagram.
Fig. 2 is sample cell profile.
Detailed description of the invention
As depicted in figs. 1 and 2, the device of a kind of fiber optic interferometric method survey refractive index has laser instrument (1), circulator (2), optical fiber
Collimator (3), injection port (4), faraday's rotating mirror (5), outlet (6), sample cell (7), photodetector (8) and demodulation module
(9) composition.
A kind of fiber optic interferometric apparatus for measuring refractive index, its overall structure is as shown in Figure 1.The laser that semiconductor laser sends
In optical fiber input to circulator, laser is irradiated to inside sample cell by circulator further through optical fiber.The front end of sample cell is
Optical fiber collimator, has the lens of 10% reflection 90% transmission in collimator.A part of incident illumination can be reflected back optical fiber by lens
In, a part of light is in collimator is injected into sample cell.It addition, the incident illumination of optical fiber can be converted into directional light by collimator
Injection, in the rear end of sample cell equipped with faraday's rotating mirror.By the directional light of collimator outgoing after sample cell, in the method for rear end
Draw and reflect on rotating mirror.Faraday's rotating mirror is by the polarization state half-twist outgoing of incident illumination, it is to avoid enter in sample cell
Penetrate the interference between light and reflection light.During use, first by collimator furnishing level, then be transmitted into sample cell by collimator
In light through rear end faraday's rotating mirror reflection and be alternatively coupled in collimator, in the reflection light of sample cell and collimator
Reflection light will interfere phenomenon.
Here order connects a length of l of circulator optical fiber1, a length of l of sample cell2.Optical fibre refractivity is n1, sample cell
The refractive index of interior sample is n2Light path for collimator reflection light isLight path for sample cell reflection light isThe optical path difference of two-way interference light isDry
The optical path difference related to is relevant with the length in the Refractive Index Sample pond of sample, and the length of incident optical is unrelated.So for outward
The vibration interference on boundary, variations in temperature is all without the change affecting optical path difference so that device stability in the large improves, capacity of resisting disturbance
By force.
By stock layout hole, sample cell can be evacuated during use, at this moment form stable interference fringe.Afterwards by sample
Product are injected in sample cell by note sample hole, and the refractive index injected after sample in sample cell occurs corresponding change, refractive index from
Vacuum n=1 changes to n=n2, optical path difference also has corresponding changeInterference fringe there will be movement.Annular
The other end of device has also connected photodetector, and photodetector can convert optical signals to the signal of telecommunication and pass to demodulation module,
It is demodulated algorithm computing, draws the quantity of stripe order recognition, pass through formula:The most permissible
Draw the refractive index of respective sample.
Claims (10)
1. fiber optic interferometric method surveys a device for refractive index, including laser instrument (1), circulator (2), optical fiber collimator (3), sample introduction
Mouth (4), faraday's rotating mirror (5), outlet (6), sample cell (7), photodetector (8) and demodulation module (9), laser instrument exports
Laser enter sample cell through circulator incidence, there is collimator the front end of sample cell, has reflection/transmission formula lens in collimator,
There is faraday's rotating mirror the rear end of sample cell, and the reflection light of collimator and the reflection light of faraday's rotating mirror can interfere phenomenon, ring
The other end of shape device is connected to photodetector, can convert optical signals to the signal of telecommunication and pass to demodulation module again, after being demodulated
Obtain corresponding refractive index value.
A kind of fiber optic interferometric method the most according to claim 1 surveys the device of refractive index, it is characterised in that: laser instrument is for single
The laser instrument that color is good, selects the semiconductor laser of 1550nm.
A kind of fiber optic interferometric method the most according to claim 2 surveys the device of refractive index, it is characterised in that: the wavelength of laser instrument
1310nm, 1064nm, 780nm or 650nm can be selected, it is also possible to select suitable wavelength model according to the size of sample refractive index
The laser instrument enclosed.
A kind of fiber optic interferometric method the most according to claim 1 surveys the device of refractive index, it is characterised in that: described sample cell
(7) being made up of clear glass, a length of 250mm, internal diameter is 10mm, external diameter 20mm.
A kind of fiber optic interferometric method the most according to claim 4 surveys the device of refractive index, it is characterised in that: sample cell can root
Other shapes are changed into, such as cuboid according to practical situation.
A kind of fiber optic interferometric method the most according to claim 1 surveys the device of refractive index, it is characterised in that: sample cell front end fills
Having collimator, equipped with the lens of 10% reflection 90% transmission in collimator, sample cell rear end is equipped with completely reflecting mirror.
A kind of fiber optic interferometric method the most according to claim 6 surveys the device of refractive index, it is characterised in that: saturating in collimator
Mirror can select the lens of 20% reflection 80% transmission, the lens of 30% reflection 70% transmission, and light transmittance can be by different refractions
Rate sample selects.
A kind of fiber optic interferometric method the most according to claim 1 surveys the device of refractive index, it is characterised in that: the rear end of sample cell
Equipped with faraday's rotating mirror, can be by the polarization state half-twist of incident illumination.
A kind of fiber optic interferometric method the most according to claim 1 surveys the device of refractive index, it is characterised in that: host computer should be adopted
With relevant demodulating algorithm, draw the value of corresponding refractive index.
A kind of fiber optic interferometric method the most according to claim 1 surveys the device of refractive index, it is characterised in that: demodulation module can
Embedded system can also be connected, as Portable type measurement unit with connection PC terminal.
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| CN201610383317.7A CN105866071B (en) | 2016-06-02 | 2016-06-02 | A kind of fiber optic interferometric method surveys the device of refractive index |
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| CN201610383317.7A CN105866071B (en) | 2016-06-02 | 2016-06-02 | A kind of fiber optic interferometric method surveys the device of refractive index |
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| CN105866071A true CN105866071A (en) | 2016-08-17 |
| CN105866071B CN105866071B (en) | 2019-04-26 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106990413A (en) * | 2017-06-02 | 2017-07-28 | 吉林大学 | The system and method for the full coherent Terahertz three-dimension high-resolution imaging of heterodyne system |
| CN107957407A (en) * | 2017-11-22 | 2018-04-24 | 盘锦雨源新创意开发推广有限公司 | A kind of sonde-type digital display refractometer |
| CN114112994A (en) * | 2021-11-29 | 2022-03-01 | 广东电网有限责任公司广州供电局 | Portable refractive index measuring device |
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| WO2004088290A1 (en) * | 2003-04-02 | 2004-10-14 | Rand Afrikaans University | A fibre optic sensor for measurement of refractive index |
| CN103134775A (en) * | 2011-11-30 | 2013-06-05 | 中国计量学院 | Optical fiber liquid refractive index and temperature sensor |
| CN103412371A (en) * | 2013-07-29 | 2013-11-27 | 华中科技大学 | Faraday rotary mirror capable of simultaneously carrying out polarization state conversion on multiple paths of optical signals |
| CN104535534A (en) * | 2014-12-15 | 2015-04-22 | 哈尔滨工程大学 | Device and method for measuring refractive index distribution profile of optical fiber preform rod based on white light interferometry absolute optical path comparison method |
| CN204359686U (en) * | 2014-12-15 | 2015-05-27 | 哈尔滨工程大学 | A kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference |
| CN104950266A (en) * | 2015-06-19 | 2015-09-30 | 北京航空航天大学 | Optical fiber magnetic field sensor |
| CN205719967U (en) * | 2016-06-02 | 2016-11-23 | 吉林大学 | A kind of fiber optic interferometric method surveys the device of refractive index |
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2016
- 2016-06-02 CN CN201610383317.7A patent/CN105866071B/en not_active Expired - Fee Related
Patent Citations (7)
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| WO2004088290A1 (en) * | 2003-04-02 | 2004-10-14 | Rand Afrikaans University | A fibre optic sensor for measurement of refractive index |
| CN103134775A (en) * | 2011-11-30 | 2013-06-05 | 中国计量学院 | Optical fiber liquid refractive index and temperature sensor |
| CN103412371A (en) * | 2013-07-29 | 2013-11-27 | 华中科技大学 | Faraday rotary mirror capable of simultaneously carrying out polarization state conversion on multiple paths of optical signals |
| CN104535534A (en) * | 2014-12-15 | 2015-04-22 | 哈尔滨工程大学 | Device and method for measuring refractive index distribution profile of optical fiber preform rod based on white light interferometry absolute optical path comparison method |
| CN204359686U (en) * | 2014-12-15 | 2015-05-27 | 哈尔滨工程大学 | A kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference |
| CN104950266A (en) * | 2015-06-19 | 2015-09-30 | 北京航空航天大学 | Optical fiber magnetic field sensor |
| CN205719967U (en) * | 2016-06-02 | 2016-11-23 | 吉林大学 | A kind of fiber optic interferometric method surveys the device of refractive index |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106990413A (en) * | 2017-06-02 | 2017-07-28 | 吉林大学 | The system and method for the full coherent Terahertz three-dimension high-resolution imaging of heterodyne system |
| CN107957407A (en) * | 2017-11-22 | 2018-04-24 | 盘锦雨源新创意开发推广有限公司 | A kind of sonde-type digital display refractometer |
| CN107957407B (en) * | 2017-11-22 | 2023-12-26 | 盘锦雨源新创意开发推广有限公司 | Probe type digital display refractometer |
| CN114112994A (en) * | 2021-11-29 | 2022-03-01 | 广东电网有限责任公司广州供电局 | Portable refractive index measuring device |
| CN114112994B (en) * | 2021-11-29 | 2023-10-20 | 广东电网有限责任公司广州供电局 | Portable refractive index measuring device |
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Inventor after: Chen Jiandong Inventor after: Gao Wenzhi Inventor after: Cui Hongliang Inventor after: Li Ya Inventor before: Chen Jiandong Inventor before: Gao Wenzhi Inventor before: Cui Hongliang Inventor before: Li Ya |
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