CN105866071B - A kind of fiber optic interferometric method surveys the device of refractive index - Google Patents

A kind of fiber optic interferometric method surveys the device of refractive index Download PDF

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Publication number
CN105866071B
CN105866071B CN201610383317.7A CN201610383317A CN105866071B CN 105866071 B CN105866071 B CN 105866071B CN 201610383317 A CN201610383317 A CN 201610383317A CN 105866071 B CN105866071 B CN 105866071B
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refractive index
sample cell
collimator
faraday
rotating mirror
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CN105866071A (en
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陈建冬
高文智
崔洪亮
李亚
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Jilin University
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Jilin University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41Refractivity; Phase-affecting properties, e.g. optical path length
    • G01N21/45Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41Refractivity; Phase-affecting properties, e.g. optical path length
    • G01N21/45Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
    • G01N2021/458Refractivity; 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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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

The invention discloses a kind of device of optical fibre interference refractive index, including laser light source, circulator, sample cell, photodetector, demodulation module, collimators.One end of sample cell is equipped with collimator, there is 10% reflection, 90% transmission-type lens in collimator, and the rear end of sample cell is faraday's rotating mirror.The light that laser issues becomes directional light incidence into sample cell after collimator, and is reflected in rear end by faraday's rotating mirror.Faraday's rotating mirror avoids the interference in sample cell between incident light and reflected light.The reflected light of collimator and the reflected light two-way light of faraday's rotating mirror can interfere phenomenon.Measurement accuracy of the present invention is high, and structure is simply easily achieved miniaturization, can measure to gas, a variety of samples of liquid, and the range for measuring refractive index is wide, and digitlization automatic measurement may be implemented.

Description

A kind of fiber optic interferometric method surveys the device of refractive index
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 technique
Currently, the method for traditional measurement refractive index mainly passes through Abbe refractometer measuring instrument, Abbe refractometer measurement Instrument is mainly the total reflection principle by light, full transmitting phenomenon is formed on the surface of fluid to be measured and prism, thus with critical angle Position be region that axis forms light and shade boundary, the refractive index to sample is realized in the position by detecting light and shade border region Measurement.Due to the principle with total reflection, the range for measuring refractive index is subject to certain restrictions, it is higher for refractive index or Lower sample can not measure.Abbe refractometer measuring instrument is built by pure physical optics device, optical path build with 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 chiefly used in liquid The measurement of the refractive index of body has certain limitation for the measurement of gas refracting index.
It is pungent superintend and direct it is strong et al. (a kind of measuring device for liquid refractive index based on fiber optic interferometric, the patent No.: 201520180701.5) measuring device for liquid refractive index of fiber optic interferometric a kind of is reported, it is not mended between fiber optic interferometric two-arm It repays, extraneous vibration and temperature influence can bring additional optical path difference, and cause measurement inaccurate, device entirety poor anti jamming capability, Accuracy and precision decline.
Summary of the invention
In order to overcome traditional refractive index measuring instrument optical path to build difficulty, use is complicated for operation, and it is automatic to can not achieve digitlization The deficiencies of measurement, the ranges of indices of refraction of measurement is smaller, the present invention provides a kind of instrument of optical fibre interference refractive index, passes through light Fine interferometry technology carries out high-acruracy survey to the refractive index of sample, and strong antijamming capability, refractometry range is wide, detection Digitlization real-time measurement function may be implemented in specimen types multiplicity, instrument.
The technical solution adopted by the present invention to solve the technical problems is: three ends of circulator respectively with laser, sample Pond is connected with photodetector.The laser that laser issues reaches sample cell by circulator, and sample cell is a transparent glass Glass hole capital after selling all securities has injection port and outlet, and different samples can be injected by injection port, and the sample for detecting completion can lead to Outlet is crossed to be discharged.The front end of sample cell is equipped with optical fiber collimator, and collimator is provided with the saturating of 10% reflection 90% transmission Mirror, lens can be by a part of the reflection of generation incident light back into optical fibers, and a part of light is injected into sample cell by collimator.In addition, The incident light of optical fiber can be converted into directional light injection by collimator, faraday's rotating mirror is housed in the rear end of sample cell, on mirror surface There is etch-proof plated film, corrosion of the sample to faraday's rotating mirror can be prevented.Sample cell is passed through by the directional light of collimator outgoing Afterwards, it is reflected on faraday's rotating mirror of rear end, the reflected light in the reflected light and collimator of sample cell can interfere existing As.The polarization state of incident light can be rotated by 90 ° by faraday's rotating mirror, incident light and faraday's rotating mirror in this way in sample cell Reflected light would not interfere, avoid the variation of the additional striped caused by interfering.When in sample pool be vacuum state When, optical path difference is constant between the reflected light of front collimation device and the reflected light of rear end faraday's rotating mirror, and interference fringe is stablized. When being filled with sample, refractive index can occur to change accordingly in sample pool, and corresponding optical path difference can be generated between two-way reflected light, Interference fringe can also generate corresponding variation.Device sheet is as all optical fibre structure, and measurement accuracy is high, and corresponding speed is fast, avoids The complicated process that conventional light path is built.
When in use, for gas and liquid sample, first sample cell can be evacuated, at this moment the refraction in sample pool Rate is n=1, then tested gas or liquid sample are injected into sample pool, and corresponding refractive index changes, and optical path difference will Corresponding change occurs, while interference fringe will generate corresponding variation, the another of circulator terminates on photodetector Face can detect the corresponding phase change of interference fringe, and demodulation module is demodulated it can be concluded that corresponding interference information later, From which further follow that the refractive index of sample to be tested.
A kind of fiber optic interferometric method surveys the device of refractive index, including laser, circulator, optical fiber collimator, injection port, farad The laser of rotating mirror, outlet, sample cell, photodetector and demodulation module, laser output passes through circulator incidence sample introduction There are collimator in product pond, the front end of sample cell, there is reflection/transmission formula lens in collimator, and there is faraday's rotating mirror in the rear end of sample cell, The reflected light of collimator and the reflected light of faraday's rotating mirror can interfere phenomenon, and the another of circulator is terminated with photodetection Device can convert optical signals to electric signal and pass to demodulation module again, corresponding refractive index value is obtained after being demodulated.
The laser that the laser need to use monochromaticjty good, selects the semiconductor laser of 1550nm.
The wavelength of the laser can choose 1310nm, 1064nm, 780nm or 650nm.
The sample cell is made of transparent glass, length 250mm, internal diameter 10mm, outer diameter 20mm.
The sample cell can be changed to the form of cuboid according to the actual situation.
The sample cell front end is equipped with collimator, the lens equipped with 10% reflection, 90% transmission in collimator.
Lens in the collimator can choose 20% reflection 80% transmission lens, 30% reflection 70% transmission it is saturating Mirror, light transmittance can be selected by different Refractive Index Samples.
The rear end of the sample cell is equipped with faraday's rotating mirror, the polarization state of incident light can be rotated by 90 °.
The host computer should use relevant demodulating algorithm, to obtain the value of corresponding refractive index.
The demodulation module, which can connect PC machine terminal, also can connect embedded system, as Portable type measurement unit.
Compared with existing apparatus for measuring refractive index, the present invention is had the advantage that
(1) all optical fibre structure, instead of building for traditional optical path, the optical path for avoiding complexity is built and calibration procedures, And it can be increased with electromagnetism interference, stability.
(2) optical fibre interference principle is used, measurement accuracy is high, and responding range is big.
(3) light path design can offset the influence of external environment temperature and vibration, improve measurement accuracy and anti-interference Ability.
(4) refractive index of liquids and gases sample can be measured, measurement specimen types are more, refractometry range Greatly.
Detailed description of the invention
Fig. 1 is optical fibre interference refractive index device system diagram.
Fig. 2 is sample cell sectional view.
Specific embodiment
As depicted in figs. 1 and 2, the device that a kind of fiber optic interferometric method surveys refractive index has laser (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) it forms.
A kind of fiber optic interferometric apparatus for measuring refractive index, overall structure are as shown in Figure 1.The laser that semiconductor laser issues It is incident in circulator by optical fiber, circulator will be inside laser irradiation to sample cell further through optical fiber.The front end of sample cell is Optical fiber collimator, the lens for thering is in collimator 10% reflection 90% to transmit.Lens can be by a part of the reflection of generation incident light back into optical fibers Interior, a part of light is injected into sample cell by collimator.In addition, the incident light of optical fiber can be converted into directional light by collimator It projects, faraday's rotating mirror is housed in the rear end of sample cell.By method of the directional light of collimator outgoing after sample cell, in rear end It draws and is reflected on rotating mirror.The polarization state of incident light is rotated by 90 ° outgoing by faraday's rotating mirror, is avoided and is entered in sample cell Penetrate the interference between light and reflected light.In use, collimator is tuned into level first, then being transmitted into sample cell by collimator In light by rear end faraday's rotating mirror reflection and again may be coupled in collimator, in the reflected light and collimator of sample cell Reflected light will interfere phenomenon.
Here the length for enabling connection circulator optical fiber is l1, the length of sample cell is l2.Optical fibre refractivity is n1, sample cell The refractive index of interior sample is n2Light path for collimator reflected light isLight path for sample cell reflected light isThe optical path difference of two-way interference light is The optical path difference of interference is related with the length in Refractive Index Sample pond of sample unrelated with the length of incident optical.So for Extraneous vibration interference, temperature change all will not influence the variation of optical path difference, so that device overall stability improves, anti-interference energy Power is strong.
Sample cell can be evacuated by stock layout hole when use, at this moment form stable interference fringe.Later by sample Product are injected into sample cell by infusing sample hole, are injected the refractive index after sample in sample cell and are occurred corresponding variation, refractive index from Vacuum n=1 changes to n=n2, optical path difference also has corresponding variationInterference fringe will appear movement.Annular The other end of device has also connected photodetector, and photodetector can convert optical signals to electric signal and be transmitted to demodulation module, Demodulating algorithm operation is carried out, the quantity of stripe order recognition is obtained, passes through formula: It can obtain The refractive index of respective sample out.

Claims (6)

1. a kind of fiber optic interferometric method surveys the device of refractive index, including laser (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 output Laser by circulator incidence into sample cell, there is collimator in the front end of sample cell, have reflection/transmission formula lens in collimator, There is faraday's rotating mirror in the rear end of sample cell, and the reflected light of collimator and the reflected light of faraday's rotating mirror can interfere phenomenon, ring The another of shape device is terminated with photodetector, can convert optical signals to electric signal and pass to demodulation module again, after being demodulated Obtain corresponding refractive index value.
2. the device that a kind of fiber optic interferometric method according to claim 1 surveys refractive index, it is characterised in that: the laser Select the semiconductor laser of 1550nm.
3. the device that a kind of fiber optic interferometric method according to claim 1 surveys refractive index, it is characterised in that: the sample cell (7) it is made of transparent glass, length 250mm, internal diameter 10mm, outer diameter 20mm.
4. the device that a kind of fiber optic interferometric method according to claim 1 surveys refractive index, it is characterised in that: sample cell front end dress There are collimator, the lens equipped with 10% reflection, 90% transmission in collimator.
5. the device that a kind of fiber optic interferometric method according to claim 1 surveys refractive index, it is characterised in that: the rear end of sample cell Equipped with faraday's rotating mirror, the polarization state of incident light can be rotated by 90 °.
6. the device that a kind of fiber optic interferometric method according to claim 1 surveys refractive index, it is characterised in that: demodulation module can be with Connection PC machine terminal also can connect embedded system, as Portable type measurement unit.
CN201610383317.7A 2016-06-02 2016-06-02 A kind of fiber optic interferometric method surveys the device of refractive index Expired - Fee Related CN105866071B (en)

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CN106990413B (en) * 2017-06-02 2023-04-18 吉林大学 System and method for heterodyne type full-coherent terahertz three-dimensional high-resolution imaging
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
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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Publication number Priority date Publication date Assignee Title
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

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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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Inventor after: Cui Hongliang

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