Remote online detection equipment for enhancing liquid Raman spectrum signal

Abstract

The invention belongs to the technical field of liquid Raman spectrum monitoring, and particularly relates to remote online detection equipment for enhancing a liquid Raman spectrum signal, comprising: a liquid Raman probe, an inlet of which is communicated with a transmitting end light path of a laser through a laser transmission optical fiber, and an outlet of which is communicated with a receiving end light path of a spectrometer through a signal transmission optical fiber; the liquid sample pool is placed in the middle of the liquid Raman probe, and the laser penetrates through the liquid sample pool for multiple times to generate Raman signals; the signal light concave reflecting mirror is arranged on one side, far away from the spectrograph, of the liquid sample pool and is used for collecting Raman signals far away from the spectrograph and transmitting the Raman signals to the spectrograph; the metal probe is arranged at the top of the liquid sample pool, the tip of the metal probe is located in the liquid sample pool, and the laser beam waist in the liquid Raman probe is located above the metal probe. The Raman signal intensity is remarkably improved by utilizing the combined action of the point effect of the metal probe and the collection of Raman signals far away from the direction of the spectrometer by the signal light concave reflecting mirror.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid Raman spectrum monitoring, and in particular relates to a remote online detection device for enhancing liquid Raman spectrum signals. Background Art

[0002] When monochromatic light (laser) is irradiated onto a sample, the frequency change of Raman scattering (i.e., Raman shift) is related to the vibration energy level of the molecule, which can be used to detect the vibration or rotation performance of each bond of the molecule under different environmental conditions. Therefore, it can be used to qualitatively and quantitatively analyze different molecules and chemical bonds. Currently, Raman spectroscopy technology has been widely used in the identification of material components as a fingerprint spectrum.

[0003] In response to the demand for remote online monitoring of liquid substances, there have been related research reports on backscattering Raman probes. This technology mainly connects the laser and spectrometer through optical fiber to achieve the goal of remote online detection. However, the current products of this type have the disadvantages of low detection sensitivity and large laser loss in liquids, which limits the wide application of this technology in the field of remote online monitoring of liquid substances. Therefore, there is an urgent need for a remote online detection device that enhances the Raman spectroscopy signal of liquids. Summary of the invention

[0004] The purpose of the present invention is to provide a remote online detection device for enhancing the Raman spectrum signal of liquid to solve the above problems.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A remote online detection device for enhancing Raman spectroscopy signals of liquids, comprising:

[0007] The liquid Raman probe has an inlet connected to the optical path of the emitting end of the laser through a laser transmission optical fiber, and an outlet connected to the optical path of the receiving end of the spectrometer through a signal transmission optical fiber;

[0008] A liquid sample pool is placed in the middle of the liquid Raman probe, and the laser penetrates the liquid sample pool multiple times to generate Raman signals;

[0009] A signal light concave reflector is arranged on a side of the liquid sample pool away from the spectrometer, and is used to collect Raman signals in a direction away from the spectrometer and transmit them to the spectrometer;

[0010] The metal probe is arranged on the top of the liquid sample pool, the tip of the metal probe is located in the liquid sample pool, and the laser beam waist in the liquid Raman probe is located above the metal probe.

[0011] Preferably, the liquid Raman probe comprises:

[0012] A first concave reflecting mirror and a second concave reflecting mirror are arranged opposite to each other, the liquid sample pool is located between the first concave reflecting mirror and the second concave reflecting mirror, and the first concave reflecting mirror and the second concave reflecting mirror are used for multiple reflections of laser to generate Raman signals;

[0013] A reflector, the output end of which is optically connected to the incident end of the second concave reflector;

[0014] A laser input part, one end of which is optically connected to the output end of the laser transmission optical fiber, and the other end of which is optically connected to the input end of the reflector;

[0015] The signal output part is arranged on the side of the signal light concave reflector close to the spectrometer, and the Raman signals generated by the first concave reflector and the second concave reflector and the Raman signals collected and reflected by the signal light concave reflector are connected to the spectrometer signal through the signal output part.

[0016] Preferably, the laser input part includes a laser transmission fiber flange, the incident end of the laser transmission fiber flange is optically connected to the output end of the laser transmission fiber, the output end of the laser transmission fiber flange is optically connected to the incident end of a collimating lens, and the output end of the collimating lens is connected to the incident end of the reflector.

[0017] Preferably, the signal output unit comprises a signal collimating lens, a signal focusing lens and a signal transmission optical fiber flange which are sequentially arranged along the propagation direction of the Raman signal;

[0018] The signal collimating lens, the signal focusing lens and the signal transmission optical fiber flange are optically connected;

[0019] The output end of the signal transmission optical fiber flange is optically connected to the input end of the signal transmission optical fiber.

[0020] Preferably, the liquid sample pool comprises a sample pool metal shell of a cubic structure, transparent window pieces are embedded on the four sides of the sample pool metal shell, and an opening is arranged on the top of the sample pool metal shell.

[0021] Preferably, the laser beam waist in the liquid Raman probe is located 0.1 mm above the metal probe.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] When in use, a liquid sample pool containing a liquid to be tested is placed in the middle of a liquid Raman probe, and a laser is emitted by a laser. The laser is transmitted along a laser transmission optical fiber to achieve long-distance laser output. The laser then enters the liquid Raman probe, reflects multiple times, and penetrates the liquid sample pool to generate a Raman signal. The tip of the metal probe is located in the liquid sample pool, and the laser beam waist in the liquid Raman probe is located above the metal probe. The tip effect of the metal probe is utilized to increase the electric field strength in the tip area, thereby increasing the Raman signal strength. The Raman signal away from the spectrometer direction is collected in conjunction with a signal light concave reflector, and the Raman signal is input into the spectrometer together. The Raman signal strength can be significantly improved by setting the signal light concave reflector and the metal probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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 are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0025] Figure 1 It is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the liquid Raman probe of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the liquid sample pool of the present invention;

[0028] Figure 4 A top view of the liquid sample pool of the present invention;

[0029] Among them, 1. Laser; 2. Laser transmission optical fiber; 3. Liquid Raman probe; 4. Signal transmission optical fiber; 5. Spectrometer; 6. Laser transmission optical fiber flange; 7. Collimating lens; 8. Reflector; 9. First concave reflector; 10. Liquid sample pool; 11. Second concave reflector; 12. Signal collimating lens; 13. Signal focusing lens; 14. Signal transmission optical fiber flange; 15. Signal light concave reflector; 16. Metal probe; 17. Sample pool metal shell; 18. Window piece. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Figures 1 to 4 The present invention discloses a remote online detection device for enhancing Raman spectroscopy signals of liquids, comprising:

[0033] The inlet of the liquid Raman probe 3 is connected to the optical path of the emitting end of the laser 1 through the laser transmission optical fiber 2, and the outlet is connected to the optical path of the receiving end of the spectrometer 5 through the signal transmission optical fiber 4;

[0034] The liquid sample pool 10 is placed in the middle of the liquid Raman probe 3, and the laser penetrates the liquid sample pool 10 multiple times to generate Raman signals;

[0035] The signal light concave reflector 15 is arranged at the side of the liquid sample pool 10 away from the spectrometer 5, and is used to collect the Raman signal in the direction away from the spectrometer 5 and transmit it to the spectrometer 5;

[0036] The metal probe 16 is arranged on the top of the liquid sample pool 10 . The tip of the metal probe 16 is located in the liquid sample pool 10 . The laser beam waist in the liquid Raman probe 3 is located above the metal probe 16 .

[0037] When in use, a liquid sample pool 10 containing a liquid to be tested is placed in the middle of a liquid Raman probe 3, and a laser is emitted by a laser 1. The laser is transmitted along a laser transmission optical fiber 2 to realize long-distance laser output. The laser then enters the liquid Raman probe 3, reflects multiple times, and penetrates the liquid sample pool 10 to generate a Raman signal. The tip of the metal probe 16 is located in the liquid sample pool 10, and the laser beam waist in the liquid Raman probe 3 is located above the metal probe 16. The tip effect of the metal probe 16 is utilized to increase the electric field strength in the tip region, thereby increasing the Raman signal strength. The signal light concave reflector 15 is used to collect Raman signals away from the spectrometer 5, and the Raman signals are input into the spectrometer 5 together. The arrangement of the signal light concave reflector 15 and the metal probe 16 can significantly improve the Raman signal strength.

[0038] Further optimizing the solution, the liquid Raman probe 3 includes:

[0039] A first concave reflecting mirror 9 and a second concave reflecting mirror 11 are arranged opposite to each other, and a liquid sample pool 10 is located between the first concave reflecting mirror 9 and the second concave reflecting mirror 11. The first concave reflecting mirror 9 and the second concave reflecting mirror 11 are used for multiple reflections of laser to generate Raman signals;

[0040] The reflector 8, the output end of which is optically connected to the incident end of the second concave reflector 11;

[0041] A laser input part, one end of which is connected to the output end optical path of the laser transmission optical fiber 2, and the other end of which is connected to the incident end optical path of the reflector 8;

[0042] The signal output part is arranged on the side of the signal light concave reflector 15 close to the spectrometer 5. The Raman signal generated by the first concave reflector 9 and the second concave reflector 11 and the Raman signal collected and reflected by the signal light concave reflector 15 are connected to the spectrometer 5 through the signal output part.

[0043] A further optimized solution is that the laser input part includes a laser transmission fiber optic flange 6, the incident end of the laser transmission fiber optic flange 6 is optically connected to the output end of the laser transmission fiber 2, the output end of the laser transmission fiber optic flange 6 is optically connected to the incident end of the collimating lens 7, and the output end of the collimating lens 7 is connected to the incident end of the reflector 8.

[0044] According to a further optimized solution, the signal output part includes a signal collimating lens 12, a signal focusing lens 13 and a signal transmission optical fiber flange 14 which are sequentially arranged along the propagation direction of the Raman signal;

[0045] The signal collimating lens 12, the signal focusing lens 13 and the signal transmission optical fiber flange 14 are optically connected;

[0046] The output end of the signal transmission optical fiber flange 14 is optically connected to the input end of the signal transmission optical fiber 4 .

[0047] According to a further optimized solution, the liquid sample pool 10 comprises a sample pool metal shell 17 of a cubic structure, transparent window pieces 18 are embedded on the four sides of the sample pool metal shell 17, and an opening is arranged on the top of the sample pool metal shell 17.

[0048] According to a further optimization scheme, the laser beam waist in the liquid Raman probe 3 is located 0.1 mm above the metal probe 16 .

[0049] The basic process of the device is as follows: the laser emitted by the laser 1 is transmitted to the liquid Raman probe 3 through the optical fiber 2, and the Raman signal generated by the liquid Raman probe 3 is transmitted and coupled to the spectrometer 5 through the optical fiber 4.

[0050] Furthermore, the laser transmission fiber flange 6 in the liquid Raman probe 3 is connected to the laser transmission fiber 2, the laser is collimated by the collimating lens 7, and then coupled to the multi-reflection cavity composed of the first concave reflector 9 and the second concave reflector 11 through the reflector 8, and the generated Raman signal is coupled to the signal transmission fiber flange 14 through the signal collimating lens 12 and the signal focusing lens 13. The signal transmission fiber flange 14 is connected to the signal transmission fiber 4 to transmit the Raman signal light to the spectrometer 5 for spectral data analysis.

[0051] The main function of the signal light concave reflector 15 is to return the Raman signal in this direction and collect it through the signal collimating lens 12 to increase the signal collection efficiency. The liquid sample pool 10 is filled with liquid sample, and the laser interacts with the liquid in the liquid sample to generate Raman signal.

[0052] The laser beam waist at the center of the multi-reflection cavity formed by the first concave reflector 9 and the second concave reflector 11 is located 0.1 mm above the tip of the metal probe 16, integrating the tip effect of the metal probe 16 to increase the electric field strength in this area and improve the Raman signal intensity.

[0053] The liquid sample pool 10 is composed of a sample pool metal shell 17 and four identical windows 18. The four windows 18 are opposite to each other and perpendicular to each other. One group of oppositely arranged windows 18 is used to penetrate the laser, and the other group of oppositely arranged windows 18 is used to transmit Raman signal light. The windows 18 and the sample pool metal shell 17 are sealed with vacuum sealant to ensure that the liquid does not leak out.

[0054] In order to reduce the transmission distance of the laser in the liquid, the liquid sample pool 10 is inserted into the center of the multi-reflection cavity formed by the first concave reflecting mirror 9 and the second concave reflecting mirror 11.

[0055] When detecting chemical components in water, the laser 1 is preferably a 532nm laser, because the attenuation of the 532nm laser in water is relatively small; if oil substances are detected, a 785nm laser is usually used for excitation, mainly because the fluorescence signal generated when 785nm is excited is relatively small. In order to meet the needs of both wavelengths at the same time, when coating the lens, it is necessary to meet the needs of a wide wavelength range of 400-1100nm. The above-mentioned collimating lens 7, reflector 8, first concave reflector 9, second concave reflector 11, signal collimating lens 12, signal focusing lens 13, signal transmission fiber flange 14, signal light concave reflector 15 and window 18 are all coated with high-reflection films or anti-reflection films with a wide wavelength range. Through the above design, the needs of 532nm Raman spectroscopy and 785nm Raman spectroscopy can be met at the same time.

[0056] In the specific working process, the type of liquid in the above-mentioned liquid sample pool 10 can be water, oil, etc. Due to the difference in the refractive index of water and oil, when the sample in the liquid sample pool 10 changes from water to oil, the refractive index of the sample decreases and the effective optical path becomes shorter. At this time, the multiple reflection cavity is slightly misaligned, and it is necessary to readjust the relative position and deflection angle of the first concave reflector 9 and the second concave reflector 11 to increase the number of reflections of the laser in the multiple reflection cavity.

[0057] The specific operation process is: connect the two ends of the laser transmission optical fiber 2 to the laser 1 and the laser transmission optical fiber flange 6 respectively; connect the two ends of the signal transmission optical fiber 4 to the spectrometer 5 and the signal transmission optical fiber flange 14 respectively. When the liquid sample fills the liquid sample pool 10, turn on the laser 1 and the spectrometer 5, and collect the Raman signal of the liquid in real time for analysis and identification. When changing the sample, fill the liquid sample pool 10 with the sample, readjust the relative position and deflection angle of the first concave reflector 9 and the second concave reflector 11, complete the adjustment of the multiple reflection cavity, turn on the laser 1 and the spectrometer 5, and collect the Raman signal of the sample in real time.

[0058] Compared with the prior art, the present invention has the following advantages and technical effects:

[0059] 1) The present invention applies the multi-reflection cavity and tip-jointly enhanced Raman spectroscopy technology to the remote online detection of liquid Raman spectroscopy.

[0060] 2) Compared with the research technology in the research background, the present invention can make full use of the multi-reflection cavity and tip-jointly enhanced Raman spectroscopy technology to develop a liquid Raman probe, which is connected to a laser and a spectrometer through an optical fiber to achieve remote online high-sensitivity detection of liquid samples.

[0061] 3) The present invention has a lower detection limit and higher sensitivity for the determination of the liquid sample to be tested.

[0062] 4) In the present invention, the liquid sample pool is placed in the center of the multiple reflection cavity, which can reduce the transmission distance of the laser in the liquid and greatly reduce the loss of the laser in the liquid.

[0063] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0064] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A remote online detection device for enhancing Raman spectroscopy signals of liquids, characterized in that: include: The liquid Raman probe (3) has an inlet connected to the optical path of the emitting end of the laser (1) through the laser transmission optical fiber (2), and an outlet connected to the optical path of the receiving end of the spectrometer (5) through the signal transmission optical fiber (4); A liquid sample pool (10) is placed in the middle of the liquid Raman probe (3), and laser light penetrates the liquid sample pool (10) multiple times to generate Raman signals; A signal light concave reflector (15), arranged on a side of the liquid sample pool (10) away from the spectrometer (5), for collecting Raman signals in a direction away from the spectrometer (5) and transmitting the Raman signals to the spectrometer (5); A metal probe (16) is arranged on the top of the liquid sample pool (10), the tip of the metal probe (16) is located in the liquid sample pool (10), and the laser beam waist in the liquid Raman probe (3) is located above the metal probe (16).

2. The remote online detection device for enhancing Raman spectroscopy signals of liquid according to claim 1, characterized in that: The liquid Raman probe (3) comprises: A first concave reflecting mirror (9) and a second concave reflecting mirror (11) are arranged opposite to each other, the liquid sample pool (10) is located between the first concave reflecting mirror (9) and the second concave reflecting mirror (11), and the first concave reflecting mirror (9) and the second concave reflecting mirror (11) are used to generate Raman signals by multiple reflections of laser light; A reflector (8), the output end of which is optically connected to the incident end of the second concave reflector (11); A laser input portion, one end of which is optically connected to the output end of the laser transmission optical fiber (2), and the other end of which is optically connected to the input end of the reflector (8); A signal output unit is arranged on a side of the signal light concave reflector (15) close to the spectrometer (5); the Raman signal generated by the first concave reflector (9) and the second concave reflector (11) and the Raman signal collected and reflected by the signal light concave reflector (15) are connected to the spectrometer (5) through the signal output unit.

3. The remote online detection device for enhancing Raman spectroscopy signals of liquid according to claim 2, characterized in that: The laser input portion comprises a laser transmission optical fiber flange (6), the incident end of the laser transmission optical fiber flange (6) is optically connected to the output end of the laser transmission optical fiber (2), the output end of the laser transmission optical fiber flange (6) is optically connected to the incident end of a collimating lens (7), and the output end of the collimating lens (7) is connected to the incident end of the reflector (8).

4. The remote online detection device for enhancing Raman spectroscopy signals of liquid according to claim 2, characterized in that: The signal output part comprises a signal collimating lens (12), a signal focusing lens (13) and a signal transmission optical fiber flange (14) which are sequentially arranged along the propagation direction of the Raman signal; The signal collimating lens (12), the signal focusing lens (13) and the signal transmission optical fiber flange (14) are optically connected; The output end of the signal transmission optical fiber flange (14) is optically connected to the input end of the signal transmission optical fiber (4).

5. The remote online detection device for enhancing Raman spectroscopy signals of liquid according to claim 1, characterized in that: The liquid sample pool (10) comprises a sample pool metal shell (17) with a cubic structure. Transparent window pieces (18) are respectively embedded on the four sides of the sample pool metal shell (17). An opening is provided on the top of the sample pool metal shell (17).

6. The remote online detection device for enhancing Raman spectroscopy signals of liquid according to claim 1, characterized in that: The laser beam waist in the liquid Raman probe (3) is located 0.1 mm above the metal probe (16).

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