CN108801981A - Trace quantity liquid refractivity measuring device based on self-mixed interference and measurement method - Google Patents
Trace quantity liquid refractivity measuring device based on self-mixed interference and measurement method Download PDFInfo
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- CN108801981A CN108801981A CN201810648448.2A CN201810648448A CN108801981A CN 108801981 A CN108801981 A CN 108801981A CN 201810648448 A CN201810648448 A CN 201810648448A CN 108801981 A CN108801981 A CN 108801981A
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- refractive index
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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
Abstract
The invention discloses a kind of apparatus for measuring refractive index based on self-mixed interference, including light path part and signal processing.The light path part includes laser light source, phase regulator, the catadioptric unit of light path, article carrying platform, and sample is mounted on the article carrying platform, and the catadioptric unit of the laser light source, phase regulator, light path and sample are sequentially connected by an optical path；The signal processing includes signal pre-processing circuit, A/D conversion circuits, DSP data processing units and outlet terminal, the input terminal of the signal pre-processing circuit is connected with the laser light source, the connection of circuit successively of the signal pre-processing circuit, A/D conversion circuits, DSP data processing units and outlet terminal.The invention also discloses a kind of refractive index measurement methods based on self-mixed interference.Measuring device of the present invention is simple in structure, and wide range of measurement, measurement method is easy to operate, high certainty of measurement.
Description
Technical field
The present invention relates to field of optical measuring technologies, and in particular to a kind of trace quantity liquid refractivity based on self-mixed interference
Measuring device and method.
Background technology
Refractive index is one of important optical parameter of substance, by refractive index will appreciate that optical property, the concentration of substance with
And each side such as purity surface properties.In the industrial departments such as food, medicine and colleges and universities' experiment, the refractive index of liquid is all with very high
Application value.In recent years, with the rise and development of the especially water pollution control of biochemical industry, environment pollution control, liquid folding
The research for penetrating rate is also constantly being extended with application field, and the measurement of liquid refractivity shows particularly necessary.
Common method for measuring liquid refractive mainly has：Geometrical optics approach and wave optics method, both be compare through
Allusion quotation and the more mature method of development；It is also a kind of just to have been developed in recent years microcavity resonant wavelength drift method.
It is primarily present problems in existing refractive index measurement method：(1) demand of liquid to be measured is compared very much not
It can realize trace measurement, precious rare sample is difficult to measure；(2) requirement to measuring apparatus instrument is more just carved, especially
It is under the conditions of high-acruracy survey, and measurement process is not easy to operate.So need to also be from terms of the accurate measurement of liquid refractivity
In method and experimentally further innovation and development.
Invention content
The purpose of the present invention is to provide one kind only to need micro-example that can carry out measuring device for liquid refractive index and method,
Its is simple and compact for structure, of low cost, applied widely；Invention also provides a kind of micro folding based on self-mixed interference
Penetrate rate measurement method.
To achieve the above object, the present invention uses following technical scheme：
A kind of apparatus for measuring refractive index based on self-mixed interference, including：
Light path part, the light path part include laser light source, phase regulator and article carrying platform, and the article carrying platform is used
In loading sample；The laser light source, phase regulator and sample are sequentially connected by an optical path with optical axis；
Signal processing, the signal processing include signal pre-processing circuit, A/D conversion circuits, at DSP data
Reason unit and outlet terminal, the input terminal of the signal pre-processing circuit are connected with the laser light source, the Signal Pretreatment
Circuit connects successively for circuit, A/D conversion circuits, DSP data processing units and outlet terminal.
Further, the laser light source uses semiconductor laser, integrally disposed thereon to have photodiode, the light
Electric diode is used to monitor the luminous power of the semiconductor laser.
Further, the article carrying platform is rotary article carrying platform, is equipped at least one sample cell and at least one
Slide clamper.
Further, the sample cell is wedge-shaped specimen cell, and volume can be adjusted.
Further, the phase regulator be in the optical path can time-varying light phase device.
The present invention also provides a kind of refractive index measurement methods based on self-mixed interference, are filled using refractometry above-mentioned
It sets and measures, include the following steps：
S1, standard film is positioned on objective table, opens laser light source, adjusted article carrying platform, make laser irradiation described
On standard film, and ensures that the laser of reflection can lead to and return to the laser light source；
S2, start phase regulator, input the reference value R of standard film1, it is anti-that DSP data processing units calculate light at this time
Present intensity C1, store C1And R1；
S3, cuvette volume is modulated into appropriate value；
S4, appropriate solution example is instilled into sample cell, adjusts article carrying platform, makes laser irradiation on the sample cell, and
Ensure that the laser of reflection can return to the laser light source；
S5, laser light source is opened, starts phase regulator, it is strong that the DSP data processing units calculate light feedback at this time
Spend C2；Thereafter, according to light feedback intensity C2Calculate detected solution reflectivity R2, R2=R1*(C2/C1)；Finally, it is reflected according to luxuriant and rich with fragrance alunite
Than formula and detected solution reflectivity R2Calculate the refractive index n of detected solution；
S6, the refractive index n of calculated detected solution is shown by outlet terminal.
After adopting the above technical scheme, compared with the background technology, the present invention, having the following advantages that：
1. the configuration of the present invention is simple is compact, the requirement to measuring apparatus instrument is relatively low, of low cost, and device is easy to accurate
Directly.Cuvette volume is adjustable simultaneously, can effectively control amount of samples, can realize the trace measurement of rare sample.
2. the method for the application present invention carries out refractometry, measurable ranges of indices of refraction is big, applied widely；Together
When, measurement method is simple, and global design can integrate, it is easy to accomplish commercial application.
Description of the drawings
Fig. 1 is the schematic diagram of laser self-mixing interference technology.
Fig. 2 is the structural schematic diagram of apparatus for measuring refractive index of the present invention.
Fig. 3 is the flow diagram of refractive index measurement method of the present invention.
Specific implementation mode
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Before embodiment is described, the basic principle of the present invention is illustrated first.The present invention is based on sharp
What the self-mixed interference principle of light was designed, when light phase adjuster changes the light path in light path, carries external cavity path and become
Inner cavity will be influenced by changing the reflected light of signal, and laser power is made to disturb, i.e., luminous power is sensitive to external cavity path variation, sensitive
Precision is half wavelength.
Laser self-mixing interference principle is as shown in Figure 1, interference system is made of semiconductor laser and external reflector.Swash
After the laser of light device outgoing is reflected or is scattered by external reflector, a part of light and the resonant cavity of return laser light device, and by changing
The carrier density become in resonant cavity causes laser medium refractive index to change and then modulates the frequency and light of laser itself
By force.
By L-K equations and FP three mirror cavity model inferences, under weak coupling situation, the frequency and light intensity of laser can be by
Three equation descriptions below：
φF=φ0-Csin(φF+arctanα) (1)
P=P0(1+mG(φF)) (2)
G(φF)=cos (φF) (3)
Wherein, formula (1) is the phase equation of self-mixed interference system, in formula, α indicate line width of semiconductor laser broadening because
Son, φFAnd φ0Indicate that the phase of laser output light when light feedback and unglazed feedback, C are light feedback intensity respectively.
In formula (2), P and P0It is the output power of semiconductor laser when having external cavity light feedback and unglazed feedback respectively；M is
The index of modulation, G (φF) interference interference mirror, it embodies influence of the exocoel light phase to output power.
The value of light feedback intensity C is described by following equation：
WhereinLight is indicated in the intracavity round trip time,Indicate chamber outer two-way time,
Indicate that light enters the coefficient of coup in resonant cavity from exocoel；In formula, n indicates that air refraction, d indicate two reflections of laser cavity
The distance in face, r1And r2Indicate the reflectivity r of two reflectings surface of laser cavity3Indicate the amplitude reflectance of external reflection object.
Meanwhile when light has refractive index for n from one kind1Medium to another kind have refractive index be n2Medium propagate when,
Fresnel equation describes the case where reflection of light.When light is with nearly normal incidence, reflectivity meets following equations：
To sum up, it can be seen that the disturbance situation of luminous power is related to reflectivity simultaneously, in the mistake of same external cavity path variation
The proportional relationships of feedback intensity C of Cheng Zhong, reflectivity and disturbing signal.Reflectivity will be obtained and substitute into Fresnel equation, you can meter
Calculate the refractive index of sample.
Based on this, the present invention proposes a kind of trace quantity liquid refractivity measuring device based on self-mixed interference and measurement side
Method.
Embodiment one
Referring to Fig. 2, the invention discloses a kind of apparatus for measuring refractive index based on self-mixed interference, including light path part
And signal processing.The light path part includes that laser light source 11, phase regulator 12, the catadioptric unit 13 of light path, loading are flat
Platform 14；Article carrying platform 14 is for loading sample；Laser light source 11, phase regulator 12, light path are turned back unit 13 and tested
Sample is sequentially connected by an optical path with optical axis.The signal processing includes signal pre-processing circuit 21, A/D conversion circuits 22, DSP
Data processing unit 23 and outlet terminal 24.The input terminal of signal pre-processing circuit 21 is connected with laser light source 11, and signal is located in advance
Managing circuit 21, electric 22 tunnels of A/D conversions, DSP data processing units 23 and outlet terminal 24, circuit connects successively.
In the present embodiment, laser light source 11 uses semiconductor laser, integrally disposed thereon to have photodiode, photoelectricity two
Pole pipe is used to monitor the luminous power of semiconductor laser.Phase regulator 12 uses electrooptic modulator, for generating periodically
Phase change.The catadioptric unit of light path 13 is an option, if the light path of laser light source lasing itself is perpendicular to objective table, nothing
The catadioptric unit in light requirement road.In the present embodiment, the catadioptric unit 13 of light path uses means of reflecting prism, makes light path perpendicular to objective table.Loading
Platform 14 is rotary article carrying platform, while including multiple sample cells and slide clamper, by rotating the standard adjusted with light path
Directly.The sample cell is wedge-shaped specimen cell, can be by adjusting cell cavity thickness and area volume adjusted.
Optical power signals are converted to voltage by the output end of the input terminal connection photodiode of signal pre-processing circuit 21
Signal realizes signal transformation using Current Voltage conversion, every circuits such as value, filtering in the present embodiment.A/D conversion circuits 22
Input terminal connection signal pretreatment circuit 21 output end, output end connects DSP data processing units 23.At DSP data
Unit 23 is managed for realizing data processing, the function of calculating refractive index value, output end connects outlet terminal 24.
It will be understood by those skilled in the art that when laser light source 11 is using other swashing with optical power monitoring function
When light device, the structure of signal processing is also required to do corresponding adjustment, to meet the processing requirement to optical power signals.
Embodiment two
Coordinate shown in Fig. 2 and Fig. 3, the invention discloses a kind of refractive index measurement method based on self-mixed interference, the party
Method uses the apparatus for measuring refractive index based on self-mixed interference of embodiment one, is realized especially by following steps：
S1, standard film is positioned on objective table, opens laser light source, adjusted article carrying platform, make laser irradiation described
On standard film, and ensures that the laser of reflection can lead to and return to the laser light source；
S2, start phase regulator, input the reference value R of standard film1, it is anti-that DSP data processing units calculate light at this time
Present intensity C1(using waveform fitting, characteristic point analysis method or Spectral Analysis Method, waveform fitting is used in the present embodiment), deposits
Store up C1And R1；
S3, the cell cavity thickness and area for adjusting sample cell on article carrying platform 14, keep volume suitable.
S4, appropriate solution example is instilled into sample cell, keeps solution surface horizontal, adjusts article carrying platform, laser irradiation is made to exist
Solution surface, and ensure that the laser of reflection can return to the laser light source；
S5, laser light source is opened, starts phase regulator, it is strong that the DSP data processing units calculate light feedback at this time
Spend C2；Thereafter, according to light feedback intensity C2Calculate detected solution reflectivity R2, R2=R1*(C2/C1)；Finally, it is reflected according to luxuriant and rich with fragrance alunite
Than formula and detected solution reflectivity R2Calculate the refractive index n of detected solution；
I.e.
S6, the refractive index n of calculated detected solution is shown by outlet terminal.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
Any one skilled in the art in the technical scope disclosed by the present invention, the change or replacement that can be readily occurred in,
It should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with scope of the claims
Subject to.
Claims (6)
1. a kind of apparatus for measuring refractive index based on self-mixed interference, which is characterized in that including：
Light path part, the light path part include laser light source, phase regulator and article carrying platform, and the article carrying platform is for filling
Carry sample；The laser light source, phase regulator and sample are sequentially connected by an optical path with optical axis；
Signal processing, the signal processing include signal pre-processing circuit, A/D conversion circuits, DSP data processing lists
Member and outlet terminal, the input terminal of the signal pre-processing circuit are connected with the laser light source, the signal pre-processing circuit,
Circuit connects successively for A/D conversion circuits, DSP data processing units and outlet terminal.
2. a kind of apparatus for measuring refractive index based on self-mixed interference as described in claim 1, it is characterised in that：The laser
Light source uses semiconductor laser, integrally disposed thereon to have a photodiode, and the photodiode described is partly led for monitoring
The luminous power of body laser.
3. a kind of apparatus for measuring refractive index based on self-mixed interference as described in claim 1, it is characterised in that：The loading
Platform is rotary article carrying platform, is equipped at least one sample cell and at least one slide clamper.
4. a kind of apparatus for measuring refractive index based on self-mixed interference as claimed in claim 3, it is characterised in that：The sample
Pond is wedge-shaped specimen cell, and volume can be adjusted.
5. a kind of apparatus for measuring refractive index based on self-mixed interference as described in claim 1, it is characterised in that：The phase
Adjuster be in the optical path can time-varying light phase device.
6. a kind of refractive index measurement method based on self-mixed interference, using refractive index as described in any one in claim 1-5
Measuring device measures, which is characterized in that includes the following steps：
S1, standard film is positioned on objective table, opens laser light source, adjusted article carrying platform, make laser irradiation in the standard
On piece, and ensure that the laser of reflection can lead to and return to the laser light source；
S2, start phase regulator, input the reference value R of standard film1, the light feedback intensity of DSP data processing units calculating at this time
C1, store C1And R1；
S3, cuvette volume is modulated into appropriate value；
S4, appropriate solution example is instilled into sample cell, adjusts article carrying platform, makes laser irradiation on the sample cell, and ensure
The laser of reflection can return to the laser light source；
S5, laser light source is opened, starts phase regulator, the DSP data processing units calculate light feedback intensity C at this time2；
Thereafter, according to light feedback intensity C2Calculate detected solution reflectivity R2, R2=R1*(C2/C1)；Finally, according to luxuriant and rich with fragrance alunite reflectivity public affairs
Formula and detected solution reflectivity R2Calculate the refractive index n of detected solution；
S6, the refractive index n of calculated detected solution is shown by outlet terminal.
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| CN201810648448.2A CN108801981B (en) | 2018-06-22 | 2018-06-22 | Micro liquid refractive index measuring device and method based on self-mixing interference |
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| CN201810648448.2A CN108801981B (en) | 2018-06-22 | 2018-06-22 | Micro liquid refractive index measuring device and method based on self-mixing interference |
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| CN108801981B CN108801981B (en) | 2023-01-31 |
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| CN109709072A (en) * | 2018-12-29 | 2019-05-03 | 北京信息科技大学 | A kind of method for measuring liquid refractive |
| CN110554006A (en) * | 2019-09-04 | 2019-12-10 | 中国科学技术大学 | Multi-mode measurement method based on self-interference micro-ring resonant cavity sensor |
| CN111337455A (en) * | 2020-04-17 | 2020-06-26 | 湖南文理学院 | Concentration detection system for electroplating solution |
| CN113310947A (en) * | 2021-07-02 | 2021-08-27 | 阜阳师范大学 | Air refractive index detection device and method based on laser self-mixing interference |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN113310947A (en) * | 2021-07-02 | 2021-08-27 | 阜阳师范大学 | Air refractive index detection device and method based on laser self-mixing interference |
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