CN212844874U - Liquid measurement system based on optical cavity enhancement - Google Patents
Liquid measurement system based on optical cavity enhancement Download PDFInfo
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- CN212844874U CN212844874U CN202021121952.6U CN202021121952U CN212844874U CN 212844874 U CN212844874 U CN 212844874U CN 202021121952 U CN202021121952 U CN 202021121952U CN 212844874 U CN212844874 U CN 212844874U
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Abstract
The utility model discloses a liquid measurement system based on optical cavity reinforcing, including light source module, optical cavity module, detection module three: 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; the detection module is an avalanche photodiode and a high-precision grating spectrometer. An optical cavity enhanced light path structure is applied, an absorption coefficient calculation model is established, and the concentration of the solution substance containing impurities can be detected by using a monochromatic light incidence system. 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 utility model discloses possess higher sensitivity, can be arranged to applications such as sample detection, composition analysis such as turbidity detects in the commercial cosmetics, algae in the water.
Description
Technical Field
The utility model relates to a liquid measurement system based on optical cavity reinforcing.
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.
Along with the development of optical cavity reinforcing technique, the material technique of measuring low concentration is more and more mature, but some measuring equipment at present are difficult for removing and price is not very general, the utility model discloses not only measurement accuracy is high and portable, and portable is used for the measurement on the spot.
SUMMERY OF THE UTILITY MODEL
In order to improve the accuracy and the sensitivity of measurement, the utility model aims at providing a liquid measurement system based on optical cavity reinforcing.
A liquid measurement system based on optical cavity enhancement comprises a light source module, an optical 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 when the incident light is the monochromatic light of a narrow-band light source, only the measured intensity signal needs to be obtained, and the avalanche diode is used as a detector for obtaining the intensity information of the emergent light; when the incident light is an incoherent broadband light source and the spectral signal of the sample is measured for analyzing the property of the sample, the grating spectrometer is used as a detector for acquiring the light intensity information and the spectral information of the 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 a referenceThe light intensity,
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 incidence 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 utility model has the advantages that:
the utility model discloses at first based on the absorption and the scattering effect of material, established the absorption coefficient calculation model of the sample that awaits measuring, realized the absorption measurement of sample, when being similar to monochromatic light incidence, in the light cavity that the high reflection mirror is constituteed, because light multiple reflection has strengthened the absorption and the scattering effect of material to can measure the sample of lower concentration, during the broadband light source irradiation system of certain limit, constituted the absorption spectrum that incoherent broadband chamber reinforcing technique measured the material. 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 measurement system based on optical cavity enhancement according to 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 present invention will be further explained with reference to the accompanying drawings.
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: when the light source is monochromatic light and the detection module is an avalanche diode (APD) for detecting the light intensity signal, when the light source is an incoherent broadband light source, the optical grating spectrometer can be replaced by a grating spectrometer for measuring the optical spectrum signal.
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 the absorption coefficient of the different substances,
is the number density.
In the example case of the present invention, the light source and the detection module are conveniently replaced. Under the prerequisite of guaranteeing that mechanical mechanism does not conflict (high reflection mirror keeps the certain distance with preceding back optical element), the sensitivity of surveying is improved greatly to the chamber reinforcing technique, has increased the utility model discloses a wide applicability.
As an example, the utility model discloses test and analysis in the thing (titanium dioxide) solution that contains of cosmetics, used 532nm laser and 635nm laser to measure the sample, measured the luminous intensity information of the different concentration samples of thing titanium dioxide solution that contains in cosmetics, minimum measurable concentration is 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 suspended when mixed with water, so that the concentration is kept constant in a certain time, different monochromatic light incidence systems can be adjusted according to substances in different cosmetics for measurement, and actual measurement is carried outThe sedimentation rate and properties of the substance in water, such as sedimentation or suspension, can be obtained according to concentration change curves of different types of objects in the water for analysis.
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 embodiment in the above description can be further combined with the latter replacement, and the embodiment is only to describe the preferred embodiment of the present invention, not to limit the concept and scope of the present invention, without departing from the design concept of the present invention, and the ordinary skilled person in the art can make various changes and improvements to the technical solution of the present invention, all 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 measurement system based on optical cavity enhancement, 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, the light penetrates through a sample to be detected for multiple times, so that the absorption and scattering of the light are enhanced, and the information of the transmitted or reflected light outside the measuring cavity is used for detecting the concentration of a trace object to be detected in liquid based on an absorption coefficient calculation model; the detection module is an avalanche photodiode or a high precision grating spectrometer.
2. The optical cavity enhancement based liquid measurement system of 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 source is collimated by the collimator, passes through the band-pass filter sheet and then enters the optical cavity module through the reflector.
3. The optical cavity enhancement based liquid measurement system of 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. The optical cavity enhancement based liquid measurement system of 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. The optical cavity enhancement based liquid measurement system of 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. the optical cavity enhancement based liquid measurement system of 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. The optical cavity enhancement based liquid measurement system of 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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