Metal ion detection device and method based on multi-laser self-mixing interference

Abstract

The invention provides a metal ion detection device based on multi-laser self-mixing interference. The metal ion detection device comprises a laser, a driving power supply, a light splitting device and a detector, one side of the laser is provided with a sample cell, the emitting end of the laser is aligned with the sample cell, and one side of the sample cell is provided with a transducer; the output end of the driving power supply is connected to the input end of the laser, the light splitting device splits laser generated by the laser into two beams, one beam of laser penetrates through the sample pool and irradiates the surface of the transducer, the other beam of laser irradiates the input end of the detector, a control module is arranged on one side of the transducer, and the output end of the control module is connected to the input end of the transducer; a Fourier transform module is arranged on one side of the detector, the output end of the detector is connected to the input end of the Fourier transform module, and the Fourier transform module is used for analyzing multiple laser self-mixing interference signals. The multi-laser self-mixing interference method is adopted, the laser and the metal ion solution act for multiple times, the method is suitable for low-concentration metal ion detection, and later metal ion detection is facilitated.

Description

Technical Field

[0001] The present invention relates to the field related to laser precision measurement technology, and in particular to a metal ion detection device and method based on multiple laser self-mixing interference. Background Art

[0002] Trace liquid refers to substances that exist in extremely low concentrations in liquid samples. Metal ion detection has many important meanings, covering many fields such as environmental protection, industrial production, health and safety. With the development of science and technology and the progress of productivity, the detection of trace metal ions can help assess the degree of pollution in water, soil and air; in some industrial processes, the concentration of trace metal ions may affect product quality and production efficiency. For example, in electronic manufacturing and chemical synthesis, strict control of the presence of trace metal ions is an important link to ensure product quality.

[0003] Absorption spectroscopy is a common method for detecting metal ions in liquid samples on the market. The metal concentration is quantified by measuring the light absorption degree of metal ions at a specific wavelength. However, metal ions with extremely low concentrations result in very weak light absorption, making the detection of trace metal ions difficult.

[0004] Therefore, based on the above problems, the present invention provides a metal ion detection device based on multiple laser self-mixing interference. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a metal ion detection device and method based on multiple laser self-mixing interference, which solves the problems mentioned in the background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A metal ion detection device based on multiple laser self-mixing interference, including a laser, a driving power supply, a spectroscopic device, and a detector;

[0008] A sample pool and a spectrometer are installed on one side of the laser, a metal ion solution is stored inside the sample pool, the output ends of the lasers are all aimed at the sample pool, and a transducer is installed on one side of the sample pool;

[0009] The output end of the driving power supply is connected to the input end of the laser, the optical splitter divides the laser light generated by the laser into two beams, one beam of laser light passes through the sample pool in sequence and irradiates the surface of the transducer, and the other beam of laser light irradiates the input end of the detector, a control module is arranged on one side of the transducer, the output end of the control module is connected to the input end of the transducer, and the control module is used to generate a continuous sinusoidal wave signal to continuously control the length of the transducer;

[0010] A Fourier transform module is disposed on one side of the detector, and the output end of the detector is connected to the input end of the Fourier transform module, and the Fourier transform module is used to analyze multiple laser self-mixing interference signals.

[0011] Furthermore, the sample pool is made of highly transparent material.

[0012] Furthermore, the normal line of the transducer is coaxial with the laser light emitted by the laser, and the surface of the transducer is a high-reflection surface.

[0013] The present invention also provides a method for a metal ion detection device based on multiple laser self-mixing interference, comprising the following steps:

[0014] S1, the driving power supply generates current to make the laser emit laser;

[0015] S2. The finely tuned laser is divided into two laser beams by the spectrometer, one of which passes through the sample cell and then irradiates the surface of the transducer, and the other laser beam irradiates the surface of the detector;

[0016] S3, the laser reflected by the transducer passes through the sample cell again, and then returns to the laser, and the laser is reflected multiple times between the transducer surface and the laser output end face, resulting in multiple laser self-mixing interference;

[0017] S4, detecting the optical signal of the laser through a detector to obtain a multiple laser self-mixing interference signal, and the detector converts the multiple laser self-mixing interference signal into an electrical signal;

[0018] S5, the detector transmits the electrical signal of the multiple laser self-mixing interference to the Fourier transform module, and obtains the power spectrum of the multiple laser self-mixing interference through the Fourier transform module;

[0019] S6. Fitting and recording the power spectrum of multiple laser self-mixing interference;

[0020] S7, change the metal ion concentration, then repeat steps S1-S6, and record the fitting coefficient of the frequency meter at this time;

[0021] S8. Record and calculate the metal ion concentration and power spectrum fitting coefficient.

[0022] In the further step S6, the metal ion fitting coefficient is f, and the formula is:

[0023] P(F)=a1·exp(-F / f)+b1

[0024] Furthermore, the metal ion concentration in S7 is c.

[0025] Furthermore, the relationship between the metal ion concentration c and the power spectrum fitting coefficient f obtained by fitting in S8 is:

[0026] c=a2·exp(-u / f)+b2

[0027] The present invention provides a metal ion detection device and method based on multiple laser self-mixing interference. Compared with the prior art, it has the following beneficial effects:

[0028] 1. The present invention adopts the coordinated setting between various structures. The laser emitted by the laser can be reflected multiple times between the transducer and the output end face of the laser. In the process of multiple reflections, the laser passes through the metal ion solution multiple times, which has the effect of enhancing the effect of the laser and the metal ion solution, and is suitable for low-concentration solution detection;

[0029] 2. The present invention obtains the power spectrum of multiple laser self-mixing interference by Fourier transform, and performs fitting analysis on the power spectrum under different metal ion concentrations, thereby eliminating the influence of background noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of a coordination block diagram of a metal ion detection device based on multiple laser self-mixing interference of the present invention is shown;

[0032] Figure 2 A schematic diagram of the relationship between power spectrum and frequency obtained by the method of the metal ion detection device based on multiple laser self-mixing interference of the present invention is shown;

[0033] Figure 3 A schematic diagram of a block diagram showing the relationship between fitting coefficients and concentrations obtained by the method of the metal ion detection device based on multiple laser self-mixing interference of the present invention;

[0034] Figure 4 A schematic diagram of a frequency-power relationship block diagram obtained by a method of a metal ion detection device based on multiple laser self-mixing interference of the present invention is shown; DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Embodiment 1

[0037] In order to solve the technical problems in the background technology, the following metal ion detection device and method based on multiple laser self-mixing interference are provided:

[0038] Combination Figure 1-4 As shown, the metal ion detection device based on multiple laser self-mixing interference provided by the present invention includes a laser, a driving power supply, a spectroscopic device, and a detector;

[0039] A sample pool and a spectrometer are installed on one side of the laser. A metal ion solution is stored inside the sample pool. The sample pool is made of highly transparent materials to reduce the optical loss of the laser during the reflection process and to ensure the accuracy of signal transmission. The output ends of the lasers are all aligned with the sample pool. A transducer is installed on one side of the sample pool; the transducer is a piezoelectric ceramic crystal; the input end of the piezoelectric ceramic crystal is connected to the input end of the control module, and the control module can control the length of the piezoelectric ceramic crystal to change periodically, thereby changing the phase of the laser and generating multiple laser self-mixing interference. The normal of the piezoelectric ceramic is coaxial with the laser emitted and received by the laser; coaxiality is used to ensure the accuracy of signal transmission.

[0040] The output end of the driving power supply is connected to the input end of the laser, the optical splitter divides the laser light generated by the laser into two beams, one beam of laser light passes through the sample pool in sequence and irradiates the surface of the transducer, and the other beam of laser light irradiates the input end of the detector, a control module is arranged on one side of the transducer, the output end of the control module is connected to the input end of the transducer, and the control module is used to generate a continuous sinusoidal wave signal to continuously control the length of the transducer;

[0041] A Fourier transform module is provided on one side of the detector, and the output end of the detector is connected to the input end of the Fourier transform module, and the Fourier transform module is used to analyze multiple laser self-mixing interference signals. Fourier transform can directly display the power spectrum of multiple laser self-mixing interference signals, which is convenient for operators to observe the influence of changes in metal ion concentration. The normal line of the transducer is coaxial with the laser emitted by the laser, and the surface of the transducer is a high-reflection surface.

[0042] Through the above design, the laser emitted by the laser can be reflected multiple times between the piezoelectric ceramic crystal and the output end face of the laser, and during the multiple reflections, the laser passes through the metal ion solution multiple times, which has the advantages of enhancing the interaction between the laser and the metal ion solution and being suitable for low-concentration solution detection. At the same time, the present invention uses Fourier transform to obtain the power spectrum of multiple laser self-mixing interference, and performs fitting analysis on the power spectrum under different metal ion concentrations, thereby eliminating the influence of background noise.

[0043] Embodiment 2

[0044] like Figure 1-4 As shown, based on the above embodiment, this embodiment further provides the following contents:

[0045] The present invention also provides a method for a metal ion detection device based on multiple laser self-mixing interference, comprising the following steps:

[0046] S1, the driving power supply generates current to make the laser emit laser;

[0047] S2. The finely tuned laser is divided into two laser beams by the spectrometer, one of which passes through the sample cell and then irradiates the surface of the transducer, and the other laser beam irradiates the surface of the detector;

[0048] S3, the laser reflected by the transducer passes through the sample cell again, and then returns to the laser, and the laser is reflected multiple times between the transducer surface and the laser output end face, resulting in multiple laser self-mixing interference;

[0049] S4, detecting the optical signal of the laser through a detector to obtain a multiple laser self-mixing interference signal, and the detector converts the multiple laser self-mixing interference signal into an electrical signal;

[0050] S5, the detector transmits the electrical signal of the multiple laser self-mixing interference to the Fourier transform module, and obtains the power spectrum of the multiple laser self-mixing interference through the Fourier transform module;

[0051] S6, fitting and recording the power spectrum of multiple laser self-mixing interference; in the step S6, the metal ion fitting coefficient is f, and the formula is:

[0052] P(F)=a1·exp(-F / f)+b1

[0053] S7, changing the metal ion concentration, then repeating steps S1-S6, and recording the fitting coefficient of the frequency meter at this time; the metal ion concentration in S7 is c;

[0054] S8, record and calculate the metal ion concentration and the power spectrum fitting coefficient, the relationship between the metal ion concentration c and the power spectrum fitting coefficient f obtained by fitting in S8 is:

[0055] c=a2·exp(-u / f)+b2

[0056] Metal ion detection method based on multiple laser self-mixing interference: This method is based on the following principle: the power spectrum of multiple laser self-mixing interference shows a decay trend, and its period is related to the metal ion concentration, sample cell length, and laser internal parameters;

[0057]

[0058] Among them, P0 is the initial power of the laser, P(t) is the laser power under multiple laser self-mixing interference, r1, r2, r3 are the reflectivities of the rear end face, the output end face and the transducer surface of the laser, respectively, k is the amplitude coefficient of the laser, is the phase of the laser, ζ is the coupling coefficient of the reflected light entering the laser, ε, d, and c are the molar absorption coefficient of the metal ions, the thickness of the metal ion solution (sample cell length), and the metal ion concentration, respectively. σ(t) is the control signal generated by the control module, l is the distance from the laser to the transducer surface, λ is the laser wavelength, and i is the number of reflections.

[0059] Since the change of metal ion concentration in the sample cell causes the change of the attenuation rate of the power spectrum, which further causes the fitting coefficient f of the multiple laser self-mixing interference power spectrum to change, the metal ion concentration c can be written as an expression for the power spectrum fitting coefficient f.

[0060] The detection method comprises the following steps:

[0061] S1, the driving power supply generates current to make the Nd:YAG pure solid-state laser emit a 532nm wavelength laser, and fine-tune the laser wavelength to be within the metal ion Fe 2+ The absorption wavelength of the solution;

[0062] S2, the fine-tuned laser is split into two laser beams by a beam splitter (splitting ratio 5:5), one of which passes through the Fe 2+ The cuvette of the solution is then irradiated on the surface of the piezoelectric ceramic, and another laser beam is irradiated on the surface of the AC type detector;

[0063] S3, the control module generates a sinusoidal control signal with an amplitude of 100mVpp and a frequency of 1kHz, which causes the length of the piezoelectric ceramic to change periodically. The laser reflected by the piezoelectric ceramic passes through the cuvette again and then returns to the Nd:YAG pure solid-state laser. The laser is reflected multiple times between the piezoelectric ceramic surface and the laser output end face, resulting in multiple laser self-mixing interference.

[0064] S4, an AC type detector detects the optical signal of the laser and obtains a multiple laser self-mixing interference signal; the detector converts the multiple laser self-mixing interference signal into an electrical signal;

[0065] S5, the AC detector transmits the electrical signal of the multiple laser self-mixing interference to the Fourier transform module, and obtains the power spectrum P(F) of the multiple laser self-mixing interference through the Fourier transform module, and the power spectrum shows an attenuation trend;

[0066] S6. Fit the power spectrum of multiple laser self-mixing interference, such as Figure 2 As shown, obtain and record the current metal ion concentration c = 5×10 -6 mol / L attenuation coefficient f = 20.72kHz, and a1 = 47.71dBm, b1 = -20.73dBm;

[0067] P(F)=a1·exp(-F / f)+b1

[0068] S7, change the metal ion concentration c range to 0-10 -5 mol / L, minimum concentration is 10 -13 mol / L, record the power spectra of different metal ion concentrations, such as Figure 4 As shown, then repeat S1-S6 and record the attenuation coefficient f of the frequency meter at this time, as Figure 3 As shown;

[0069] S8. The relationship between the metal ion concentration c and the power spectrum attenuation coefficient f is obtained by fitting:

[0070] c=a2·exp(-u / f)+b2

[0071] Where a2 = 2.14 × 10 -5 mol / L, b2=-1.12×10 -7 mol / L, u=12.71kHz.

[0072] In summary, the power spectrum of multiple laser self-mixing interference shows an attenuation trend, and its period is related to the metal ion concentration, the sample cell length, and the internal parameters of the laser. The change of the metal ion concentration in the sample cell causes the attenuation rate of the power spectrum to change. The power spectra under different metal ion concentrations are fitted and analyzed to eliminate the influence of background noise.

[0073] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metal ion detection device based on multiple laser self-mixing interference, characterized in that: Including laser, driving power supply, and detector; A sample pool and a spectrometer are installed on one side of the laser, a metal ion solution is stored inside the sample pool, the output ends of the lasers are all aimed at the sample pool, and a transducer is installed on one side of the sample pool; The output end of the driving power supply is connected to the input end of the laser, the optical splitter divides the laser light generated by the laser into two beams, one beam of laser light passes through the sample pool in sequence and irradiates the surface of the transducer, and the other beam of laser light irradiates the input end of the detector, a control module is arranged on one side of the transducer, the output end of the control module is connected to the input end of the transducer, and the control module is used to generate a continuous sinusoidal wave signal to continuously control the length of the transducer; A Fourier transform module is disposed on one side of the detector, and the output end of the detector is connected to the input end of the Fourier transform module, and the Fourier transform module is used to analyze multiple laser self-mixing interference signals.

2. The metal ion detection device based on multiple laser self-mixing interference according to claim 1 is characterized in that: The sample pool is made of highly transparent material.

3. The metal ion detection device based on multiple laser self-mixing interference according to claim 1 is characterized in that: The normal line of the transducer is coaxial with the laser light emitted by the laser, and the surface of the transducer is a high-reflection surface.

4. A method for metal ion detection device based on multiple laser self-mixing interference, characterized in that: The metal ion detection device based on multiple laser self-mixing interference as described in claim 1 comprises the following steps: S1, the driving power supply generates current to make the laser emit laser; S2. The finely tuned laser is divided into two laser beams by the spectrometer, one of which passes through the sample cell and then irradiates the surface of the transducer, and the other laser beam irradiates the surface of the detector; S3, the laser reflected by the transducer passes through the sample cell again, and then returns to the laser, and the laser is reflected multiple times between the transducer surface and the laser output end face, resulting in multiple laser self-mixing interference; S4, detecting the optical signal of the laser through a detector to obtain a multiple laser self-mixing interference signal, and the detector converts the multiple laser self-mixing interference signal into an electrical signal; S5, the detector transmits the electrical signal of the multiple laser self-mixing interference to the Fourier transform module, and obtains the power spectrum of the multiple laser self-mixing interference through the Fourier transform module; S6. Fitting and recording the power spectrum of multiple laser self-mixing interference; S7, change the metal ion concentration, then repeat steps S1-S6, and record the fitting coefficient of the frequency meter at this time; S8. Record and calculate the metal ion concentration and power spectrum fitting coefficient.

5. The method of metal ion detection device based on multiple laser self-mixing interference according to claim 4, characterized in that: In the step S6, the metal ion fitting coefficient is f, and the formula is: P(F)=a1·exp(-F / f)+b1 6. The metal ion detection device and method based on multiple laser self-mixing interference according to claim 4, characterized in that: The metal ion concentration in S7 is c.

7. The metal ion detection device and method based on multiple laser self-mixing interference according to claim 4 is characterized in that: The relationship between the metal ion concentration c and the power spectrum fitting coefficient f obtained by fitting in S8 is: c=a2·exp(-u / f)+b2.

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