CN111537414A - Liquid optical cavity enhancement measuring system - Google Patents
Liquid optical cavity enhancement measuring system Download PDFInfo
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- CN111537414A CN111537414A CN202010552789.7A CN202010552789A CN111537414A CN 111537414 A CN111537414 A CN 111537414A CN 202010552789 A CN202010552789 A CN 202010552789A CN 111537414 A CN111537414 A CN 111537414A
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- optical cavity
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- 230000003287 optical effect Effects 0.000 title claims abstract description 47
- 239000007788 liquid Substances 0.000 title claims abstract description 33
- 238000001514 detection method Methods 0.000 claims abstract description 26
- 238000010521 absorption reaction Methods 0.000 claims abstract description 21
- 230000035945 sensitivity Effects 0.000 claims abstract description 10
- 238000004458 analytical method Methods 0.000 claims abstract description 7
- 238000004364 calculation method Methods 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 claims description 23
- 230000003595 spectral effect Effects 0.000 claims description 7
- 230000007547 defect Effects 0.000 claims description 4
- 239000013307 optical fiber Substances 0.000 claims description 4
- 238000002310 reflectometry Methods 0.000 claims description 4
- 230000008033 biological extinction Effects 0.000 claims description 3
- 230000009365 direct transmission Effects 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 18
- 239000002245 particle Substances 0.000 abstract description 8
- 241000195493 Cryptophyta Species 0.000 abstract description 7
- 238000000862 absorption spectrum Methods 0.000 abstract description 6
- 239000002537 cosmetic Substances 0.000 abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 5
- 238000006073 displacement reaction Methods 0.000 abstract description 2
- 239000012535 impurity Substances 0.000 abstract description 2
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 9
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000004062 sedimentation Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
-
- 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
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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- G01N15/075—
Abstract
The invention discloses a liquid optical cavity enhanced measuring system, which comprises a light source module, an optical cavity module and a detection module: the light source module is light modulated after a switchable monochromatic light source or a white light source passes through the collimating lens and the filter; the optical cavity module is a parallel cavity consisting of two planoconcave high-reflection mirrors and is used for enabling light to be reflected for multiple times in the cavity to improve the optical path, and the distance between the high-reflection mirrors can be regulated and controlled through a displacement table; the detection module is an avalanche photodiode and a high-precision grating spectrometer. The optical cavity enhanced light path structure is applied, an absorption coefficient calculation model is established, a monochromatic light incidence system is used for further detecting the solution containing impurities, and different monochromatic wavelength light sources are used for detecting the concentration of substances with different particle sizes, so that the multi-wavelength detection application is formed. When the incoherent broadband light source in a certain waveband range is used for entering the system, the IBBCEAS system is formed, and the absorption spectrum of a trace factor in the liquid can be measured, so that more information can be obtained. The invention has higher sensitivity, and can be used for turbidity detection in commercial cosmetics, sample detection of algae in water and the like, component analysis and the like.
Description
Technical Field
The invention relates to a liquid optical cavity enhanced measuring system.
Background
The liquid optical cavity enhancement technology can be used for concentration measurement and component analysis in liquid and turbid liquid, under the irradiation of monochromatic light, particles of substances and water molecules in the liquid absorb and scatter the light, the light is reflected for many times in the high reflection cavity, the detection optical path is increased, and the absorption and scattering effects are also increased. According to the principle of Mie scattering, the scattering intensity of the particles with different particle sizes to light is different, so that different monochromatic light sources can be replaced according to the different particle sizes of the particles in the liquid, and the concentration of different substances can be conveniently measured. Under the irradiation of a broadband light source in a certain bandwidth range, the particle substances in the liquid can selectively absorb light, and the detection module can obtain the absorption spectrum of the liquid substances, so that the properties of the substances are analyzed. At present, no related equipment system can simultaneously measure the concentration and the absorption spectrum property of substances in liquid.
The cavity enhancement technology is a high reflection cavity formed by two plano-concave high reflection mirrors, light is reflected for multiple times in the cavity, absorption and scattering are increased, detection signals become more obvious, the cavity enhancement technology is mostly used for gas measurement, the concentration and the absorption spectrum of trace gas are detected, the cavity enhancement technology is used for measuring substances of liquid, the defect of high cost of liquid substances is overcome, and the application range of the cavity enhancement technology is enlarged.
With the development of the optical cavity enhancement technology, the technology for measuring low-concentration substances is more and more mature, but some current measuring equipment is generally not easy to move and is not expensive, and the device is high in measuring precision, portable and convenient to carry and use for on-site measurement.
Disclosure of Invention
In order to improve the accuracy and sensitivity of the measurement, it is an object of the present invention to provide a liquid optical cavity enhancement technique.
The liquid optical cavity enhancement system comprises a light source module, a light cavity module and a detection module: the light source module is a switchable monochromatic light source or a white light source; the optical cavity module is a parallel cavity consisting of two planoconcave high-reflection mirrors and is used for enabling light to be reflected for multiple times in the cavity to improve the optical path, so that the absorption and scattering of the light are enhanced; the detection module is a switchable avalanche photodiode and a high-precision grating spectrometer. The cavity-enhanced light path structure is applied, an absorption coefficient calculation model is established, and the solution containing impurities can be detected by using the monochromatic light incidence system. When an incoherent broadband light source in a certain waveband range is used for entering the system, the IBBCEAS system is formed and can measure the absorption spectrum of trace factors in liquid, so that more multivariate information such as spectral information and the like can be obtained.
The light source module comprises: the device comprises a monochromatic light source, a white light source, a collimator and a band-pass filter; the monochromatic light source is a monochromatic laser light source, and light emitted by the white light broadband light source is collimated by the collimator, passes through the band-pass filter sheet and then enters the optical cavity module through the reflector.
The optical cavity module is a high-reflection cavity formed by two plano-concave high-reflectivity lenses, a sample to be detected is placed in the high-reflection cavity, and a light source is reflected back and forth in the cavity after entering the high-reflection cavity, so that the optical path is increased, the absorption and scattering of light are enhanced, and the optical cavity module can be used for detecting the concentration of a trace object to be detected in liquid and obtaining better sensitivity.
The detection module comprises an avalanche diode and a grating spectrometer. There is a distinction between the use of the two: when the concentration of a sample is measured, namely incident light is monochromatic light of a narrow-band light source, only a measured intensity signal needs to be acquired, and an avalanche diode is used as a detector for acquiring emergent light intensity information; when the incident light is an incoherent broadband light source, the grating spectrometer is used as a detector for acquiring light intensity information and spectral information of a sample for analysis. Therefore, the system has the following combination mode: when the light source is tunable monochromatic light, the detector is an avalanche diode; when the light source is a broadband light source, the detector is a grating spectrometer.
The absorption coefficient calculation model is as follows: as light enters the cavity and reflects back and forth therein, the sample not only absorbs light but also scatters, thereby modeling in terms of absorption coefficients: where lambda is the wavelength of the incident light,
is the intensity of the reference light,
Is the light intensity of transmitted light,
Is the reflectivity of the highly reflective mirror and,
is the effective length of the optical cavity and,
and
respectively rayleigh scattering and mie scattering extinction coefficients. The calculation formula is as follows:
the optical cavity module is internally provided with a sample to be detected, and because the wavelength of incident light is in a high reflection interval of the high reflection mirror, the light is reflected for many times in the cavity to increase the optical path, so that the defect of insufficient detection sensitivity of single direct transmission is overcome, the concentration limit of the detectable sample is greatly reduced, and the intensity of a weak detection signal is improved.
The sample is focused in the optical fiber through the achromatic lens after being reflected for multiple times in the cavity, and then is transmitted to the detector module through the optical fiber for measurement.
The invention has the beneficial effects that:
the invention firstly establishes an absorption coefficient calculation model of a sample to be measured based on the absorption and scattering effects of the substance, realizes the absorption measurement of the sample, and enhances the absorption and scattering effects of the substance due to multiple reflections of light in an optical cavity consisting of a high reflecting mirror when the light is incident similar to monochromatic light, thereby measuring the sample with lower concentration and forming an absorption spectrum of the substance by an incoherent broadband cavity enhancement technology when a broadband light source irradiation system in a certain range. The system has higher sensitivity, and can be used for turbidity detection in commercial cosmetics, sample detection with small content in water, component analysis and the like.
Drawings
FIG. 1 is a schematic diagram of a liquid optical cavity enhanced measurement system of the present invention:
wherein 1 is the switchable light source, 2 is the collimater, 3 is the filter, 4 is the speculum, changes the optical axis direction, 5 is the diaphragm, 6 and 8 are high reflection mirrors, 7 is the sample that awaits measuring, 9 is achromatic lens, 10 is the optic fibre adapter ring, 11 is the optic fibre, 12 is the detector, 13 is adjustable two-dimentional displacement platform.
Detailed Description
The invention is further elucidated with reference to the drawing.
As shown in fig. 1: the light that light source 1 sent becomes the collimation facula after 2 collimators for the light beam radius through the collimator diminishes and optical density increases, and the light after the collimation filters the wave plate, gets into the optical cavity module after the speculum again, and the optical cavity module comprises 6 and 8 plano-concave high mirrors, and the light beam passes sample 7 many times in the optical cavity, then the transmitted light focuses on in the optic fibre adapter ring behind the achromatism lens, and then gets into in the optic fibre, finally gets into the detector. According to different detection purposes, the system has different combination modes: the detection module is an avalanche diode (APD) for detecting the optical intensity signal when the light source is monochromatic light and is a grating spectrometer that can be replaced with a measured spectral signal when the light source is an incoherent broadband light source.
On one hand, when the concentration of a sample to be measured is measured, the detection module selects the avalanche diode to measure a light intensity signal, the sensitivity of the avalanche diode to the light intensity is high, and the signal collection and storage are controlled through a Labview program. On the other hand, when measuring the spectral information of the sample to be measured, the detection module selects the grating spectrometer to collect data.
When light passes through liquid, liquid can absorb light, and meanwhile, particles in the liquid can scatter light, and there are two kinds of scattering of Rayleigh scattering and Mie's scattering to the weak light signal, light after the collimation need carry out the diaphragm and restrict its light beam size, so absorption coefficient in the intracavity is:
when measuring multiple substances in a liquid, the total absorption coefficient is:
wherein
Is different fromThe absorption coefficient of the substance is such that,
is the number density.
In the example case of the present invention, the light source and the detection module are easily replaced. On the premise of ensuring that the mechanical mechanism does not conflict (the high-reflection mirror keeps a certain distance from the front and rear optical elements), the cavity enhancement technology greatly improves the detection sensitivity and increases the wide applicability of the invention.
As an example, the invention tests and analyzes in the titanium dioxide solution containing the cosmetic, measures the samples by using a 532nm laser and a 635nm laser, measures the light intensity information of the samples with different concentrations of the titanium dioxide solution containing the cosmetic, and has the lowest measurable concentration of 2.5
And the concentration change in the sample supernatant with time change is measured in the process of simulating the sample storage, and the method has certain time resolution. Some additives in the cosmetics are in a suspension state after being mixed with water, so that the concentration is kept unchanged within a certain time, different monochromatic light incidence systems can be adjusted to carry out measurement according to substances in different cosmetics, and the sedimentation rate, the sedimentation or the suspension and other properties of the substances in the water can be obtained to carry out analysis according to concentration change curves of different types of objects in actual measurement.
On the other hand, as an extension of the embodiment, the algae solution can be collected and the spectral information thereof can be measured, and the algae has a characteristic absorption peak in a certain wave band, so that the spectral signal can be greatly changed when the algae-containing solution is measured, and the analysis of the substances in the solution can be further analyzed. When the algae solution is measured, incoherent broadband light with a certain wave band range is selected to form an IBBCEAS system together with the high reflection cavity, the measurement mode overcomes the defect of inaccurate measurement when a microscope is used for observing trace algae and measuring the spectrum of the trace algae, and the sensitivity and the measurement speed are greatly improved.
The embodiments in the above description can be further combined with the alternatives of the latter, and the embodiments only describe the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention, and various changes and modifications made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention belong to the protection scope of the present invention. The scope of the invention is given by the appended claims and any equivalents thereof.
Claims (7)
1. A liquid optical cavity enhanced measurement system, characterized by: the device comprises a light source module, an optical cavity module and a detection module; the light source module is light modulated by a monochromatic light source or a white light source with switchable or adjustable wavelength after passing through a collimating lens and a filter; the optical cavity module is a parallel cavity formed by two plano-concave high-reflection mirrors and is used for enabling light to be reflected for multiple times in the cavity to improve the optical path, so that the absorption and scattering of the light are enhanced, and the transmitted or reflected light information outside the measurement cavity is used for detecting the concentration of a trace object to be detected in liquid; the detection module is an avalanche photodiode or a high precision grating spectrometer.
2. A liquid optical cavity enhancement measurement system according to claim 1, wherein: the light source module comprises: a monochromatic light source or a white light source with switchable or adjustable wavelength, a collimator and a band-pass filter; the monochromatic light source is a narrow-band laser light source, and light emitted by the white light broadband light source passes through the band-pass filter sheet after being collimated by the collimator and then enters the optical cavity module through the reflector.
3. A liquid optical cavity enhancement measurement system according to claim 1, wherein: the optical cavity module is a high-reflection cavity formed by two high-reflectivity plano-concave lenses, a sample to be detected is placed in the high-reflection cavity, the light source is reflected back and forth in the cavity after entering the high-reflection cavity, the optical path is increased, and therefore absorption and scattering of light are enhanced, and transmission or reflection light information obtained by measurement outside the cavity can be used for detecting the concentration of a trace object to be detected in liquid and obtaining better sensitivity.
4. A liquid optical cavity enhancement measurement system according to claim 1, wherein: the detection module comprises an avalanche diode and a grating spectrometer; there is a distinction between the use of the two: when the concentration of a sample is measured, when incident light is monochromatic light of a narrow-band light source, only a measured intensity signal needs to be obtained, and an avalanche diode is used as a detector for obtaining intensity information of emergent light; when the incident light is a white light broadband light source, the grating spectrometer is used as a detector to acquire transmitted light intensity information and spectral information for analysis.
5. A liquid optical cavity enhancement measurement system according to claim 1, wherein: the absorption coefficient calculation model is as follows: as light enters the cavity and reflects back and forth therein, the sample not only absorbs light but also scatters, thereby modeling in terms of absorption coefficients: where lambda is the wavelength of the incident light,
is the intensity of the reference light,
The transmitted light intensity obtained by the measurement outside the cavity,
Is the reflectivity of the highly reflective mirror and,
is the effective length of the optical cavity and,
and
respectively rayleigh scattering extinction coefficient and mie scattering extinction coefficient; the absorption coefficient calculation formula is as follows:
6. a liquid optical cavity enhancement measurement system according to claim 1, wherein: the optical cavity module is internally provided with a sample to be detected, and because the wavelength of incident light is in a high reflection interval of the high reflection mirror, the light is reflected for many times in the cavity to increase the optical path, so that the defect of insufficient detection sensitivity of single direct transmission is overcome, the concentration limit of the detectable sample is greatly reduced, and the intensity of a weak detection signal is improved.
7. A liquid optical cavity enhancement measurement system according to claim 1, wherein: the sample is focused in the optical fiber through the achromatic lens after being reflected for multiple times in the cavity, and then is transmitted to the detector module through the optical fiber for measurement.
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| CN202010552789.7A CN111537414A (en) | 2020-06-17 | 2020-06-17 | Liquid optical cavity enhancement measuring system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115575326A (en) * | 2022-11-15 | 2023-01-06 | 安徽中科蓝壹信息科技有限公司 | Light path adjusting device and method suitable for broadband cavity enhancement system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115575326A (en) * | 2022-11-15 | 2023-01-06 | 安徽中科蓝壹信息科技有限公司 | Light path adjusting device and method suitable for broadband cavity enhancement system |
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